Environmental Chemistry [1 ed.] 9781783320523, 9781842658932

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Environmental Chemistry

Environmental Chemistry

Shweta Sharma Pooja Sharma

a Alpha Science International Ltd. Oxford, U.K.

Environmental Chemistry 422 pgs. | 97 figs. | 25 tbls.

Shweta Sharma Pooja Sharma Department of Chemistry and Environmental Science Northern India Engineering College, Delhi Copyright © 2014 ALPHA SCIENCE INTERNATIONAL LTD. 7200 The Quorum, Oxford Business Park North Garsington Road, Oxford OX4 2JZ, U.K.

www.alphasci.com All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without prior written permission of the publisher. ISBN 978-1-84265-893-2 E-ISBN 978-1-78332-052-3 Printed in India

Preface Environment has been the greatest source of life for the living beings on the earth. It provides an integrated, quantitative and interdisciplinary approach to the study of environmental systems. The book is designed to cater the syllabus of first year undergraduate professional students of universities. It is written in an easy to understand format, the book covers the fundamental aspects of Environmental Science in a precise manner. The book has eight chapters. Chapter 1 explains the multidisciplinary nature of environmental studies. It stresses on the nature, scope, importance and need for public awareness. Chapter 2 covers the ecosystem and explains ecological succession, food chain, ecological pyramids and the type of ecosystems. Chapter 3 discusses biodiversity and its conservation. It gives details on values of biodiversity, biogeographic zones of India, hotspots, threats to biodiversity, human wildlife conflicts and conservation of biodiversity. Chapter 4 presents a detailed study of different type of resources such as forest, water, mineral, food, energy and land resources and its conservation. Chapter 5 is about Chemistry of Environment. It involves twelve principles of Green Technology, Atom Economy, tools of Green Chemistry and zero-waste technology. It also includes an extensive study of Eco-friendly polymers and bioremediation. Chapter 6 contributes to the Environmental Pollution and Control. It discusses air pollution, water pollution, land pollution or soil, marine pollution, noise pollution, thermal pollution, nuclear hazards, solid waste and its management. It is also about chemical toxicology. Chapter 7 discusses disaster management like floods, earthquake, cyclone, landslides, etc.

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Chapter 8 is about social and environment which includes sustainable development, urban problems related to energy and also deals with human population. Any constructive comments and suggestions for improving the book are most welcome from students, teachers and readers, all of which can be mailed to us at [email protected] and lavoniashweta@ yahoo.co.in Shweta Sharma Pooja Sharma

Acknowledgements It is our unique privilege to express profound gratitude to our teachers and guides for their wise, valuable and constructive suggestions. We are fortunate enough to recall the contribution of our esteemed family members whose love and encouragement have always been a source of inspiration for us. Infact, this entire work was accomplished due to their spiritual blessings and moral support. We are extremely thankful to the management of our college (Northern India Engineering College, Delhi) our colleagues and friends. We want to express our sincere thanks to Narosa Publishing House for the sustained interest shown during the entire work. Lastly, we solicit our indebtedness to ALMIGHTY for sustaining our intellectual abilities and wishdom in achieving our goals. Shweta Sharma Pooja Sharma

Contents Preface Acknowledgements

1. The Multidisciplinary Nature of Environmental Studies

v vii

1.1

Introduction; Abiotic Factors; Biotic Factors; Objectives; Multidisciplinary Nature of Environmental Studies; Importance of Environmental Education; Need for Public Awareness; Institutions in Environment; People in Environment

2. Ecosystem

2.1

What is Ecosystem?; Concept of an Ecosystem; Characteristics of an Ecosystem; Structure of an Ecosystem; Abiotic Components; Interaction; Function of an Ecosystem; Food Chain; Types of Food Chain; Significance of Food Chain; Food Web; Types of Food Webs; Applications of Food Webs; Ecological Pyramids; Flow of Energy in an Ecosystem; Ten Per cent Law; Conservation of Energy; Biogeochemical Cycles in an Ecosystem; Types of Biogeochemical Cycles; Carbon Cycle; Oxygen Cycle; Nitrogen Cycle; Nitrogen Fixation Methods; Who Performs Nitrogen Fixation?; Phosphorus Cycle; Sulphur Cycle; Ecological Succession; Primary and Secondary Succession; The Stages of Succession; Secondary Production; Regulation of Ecosystem; Forest Ecosystem; Characteristic Features of Forest Ecosystem; Functions of Forest Ecosystem; Types of Forest Ecosystem; Characteristics of Grassland Ecosystem; Grassland Climate; Grassland Organisms; Types and Characteristics of Deserts; Types and Characteristics of Aquatic Ecosystems

3. Biodiversity and its Conservation What is Biodiversity?; Why is Biodiversity Important?; Types of Biodiversity; Biogeographical Classification of India; The Trans-Himalayan Region; The Indian Desert; The Semi-arid Region; The Western Ghats; The Deccan Peninsula; The Gangetic Plain; The Coastal Region; The North-East; The Indian Islands; Plants in India; Animals

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in India; Environment Service Values; Importance of Biodiversity; Biodiversity at Global, National and Local Levels; Biodiversity at Global Level; Biodiversity at National Level and Local Level; India as a Megadiversity Nation; Hotspots of Biodiversity; Criteria for Betermining Hotspots; Biodiversity Hotspots in India; The Eastern Himalayas; Plants; Vertebrates; Conservation Action and Protected Areas; The Western Ghats and Sri Lanka; Flora and Fauna; Protected Areas; National Parks; Biosphere Reserves; Main Functions of Biosphere Reserves; Ex-Situ Conservation; Use of Seed Bank, Gene Banks or Germplasm; Animal Translocations; Botanical Gardens; Zoological Gardens or Zoos

4. Natural Resources: Problems and Prospects Introduction; Issues with Natural Resources; Ways to Conserve Natural Resources; Forest Resources; Use and Overexploitation of Forests Resources; Uses of Forest; Overexploitation of Forest Resources; Deforestation; Causes of Deforestation; Consequences of Deforestation; Timber Extraction; Mining; Dams and their Effects on Forests and Tribal People; Effects of Dam on Tribal People; Water Resources; Causes for Water Scarcity and its Result; Overutilisation and Pollution of Surface and Groundwater; Floods; Controlling Measures; Flood Management Measures; Flood Management Organisations; Drought; Impact of Droughts; Conflicts Over Water – Equitable Distribution; Dams-Benefits and Problems; Different Methods of Water Conservation; Advantages of Rainwater Harvesting; Watershed Management; Mineral Resources; Processing the Mineral; Causes of Exploitation of Mineral Resources; Environmental Effects of Extracting and using Mineral Resources; Conservation of Mineral Resources; Case Study of Mining in Rajasthan, Bijolia; Food Resources; World Food Problems; Food Security; Major Causes of World Food Shortages; Problems of the Developing World; Problems of the Industrialised World; Problems Linking Industrial and Developing Worlds; Changes Causes by Agriculture and Over-grazing; Overgrazing; Effects of Modern Agriculture; Positive Effects of Agricultural Applications; FertilizerPesticide Problems; Controlling Agricultural Pests; Water Logging; Causes of Water Logging; Effects of Water Logging; Control Measures of Water Logging; Salinity; Causes of Salinity; Impacts of Salinity; Energy Resources; Growing

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Contents

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Energy Needs; Solar Cooker; Biogas Plants; Nuclear Power; Urban Problems Related to Energy; Land Resources; Land as a Resource; Land Degradation; Man-Induced Landslides; Types of Landslides; Causes of Landslides; Man-made Causes; Consequences of Landslides; Mitigatory Measures; Soil Erosion; Erosion Factors; Calculation of Erosion Rates; On-site Impacts of Soil Erosion; Off-site Impacts of Soil Erosion; Desertification; Extent of Desertification; Thar Desert—A case study

5. Chemistry of Environment What is Green Chemistry ?; Need of Green Chemistry; Twelve Principles of Green Chemistry; Concept of Atom Economy; Atom Economy in Catalytic Synthesis of Ethylene Oxide; Atom Economy in Ibuprofen Synthesis; Boots Company Ibuprofen Synthesis; BHC Company Ibuprofen Synthesis; Tools of Green Chemistry; Disadvantages of Phosgene; Advantages of Polycarbonate; Zero Waste Technology; Corporate Initiatives; Clean Development Mechanisms (CDM); CDM Objectives; Environmental Impact Assessment (EIA); Environmental Impact Assessment Notification in India; EIA Study Objectives; Nature of Projects; Advantages of EIA; Eco-Friendly Polymers; Polymer Molecules; Stereoisomerism; Thermoplastic PolymersThermoplastics (T-P); Thermosetting Polymers-Thermosets (T-S); Elastomers; The Need for a Fully Degradable Plastic; Mechanisms of Environmental Degradation in Polymers; Factors Responsible for Degradation of Polymers; Types of Polymer Degradation; Decomposition of Initially Formed Hydroperoxide Group; Environmentally Degradable Polymers; Biodegradable Polymers Classifications; Photobiodegradable Polymers; Sensitised Photodegradation; Stabilization; Hydrobiodegradable Polymers; Degradation Mechanisms; Biopolymers and Bioplastics; BiopolymersBiodegradable Polymers; Biopolymers-History; Biopolymers From Living Organisms; Polymerizable Molecules; How are Biopolymers and Bioplastics Made?; Applications of Biodegradable Polymers; Polylactide or Polylactic Acid(PLA); Polycaprolactone (PCL); PHB (Polyhydroxybutyrate); Bioremediation; History of Bioremediation; Bioremediation Strategies; Advantages and Disadvantages of Bioremediation Technologies; Developments of Phytoremediation

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6. Environmental Pollution

6.1

Pollution and Pollutants; Types of Pollution; Primary and Secondary Pollutants; Environmental Effects; Effects of Photochemical Smog; Prevention and Control of Air Pollution; India’s Coastline; Major Marine Pollutants Worldwide; Effects of Marine Pollution; Control Measures to Protect Marine Environment; Terminology Used in Noise Pollution; Mechanism of Hearing; Major Sources of Noise; Effects of Noise Pollution; Control of Noise Pollution; Measurement of Thermal Pollution; Control of Thermal Pollution; Ethical Solution; Nuclear Hazards; Frequency and Duration of Radioactive Pollution; Man-made; Effects; Control; Case Study; Solid Waste Management; Classification; Disposal Methods; Mismanagement and Side Effects; Chemical Toxicology; What is a Toxic Substance?; Toxic Metals in the Enivronment; Mercury (Hg); Applications; Mercury in the Environment; Health Effects of Mercury; Environmental Effects of Mercury; Arsenic (AS); Applications; Arsenic in the Environment; Health Effects of Arsenic; Environmental Effects of Arsenic; Codmium (Cd); Environmental Effects of Cadmium; Chromium (Cr); Applications; Chromium in the Environment; Health Effects of Chromium; Environmental Effects of Chromium; Lead (Pb); Applications; Lead in the Environment; Health Effects of Lead; Environmental Effects of Lead

7. Disaster Management

7.1

Types of Disasters; Disaster Prevention; Disaster Preparedness; Disaster Relief; Disaster Recovery; Cyclones; Types of Cyclones; How Cyclones are Formed ?; What is an Earthquake ?; Why do Earthquakes Happen ?; Size and Frequency; Human Induced Seismic Activity; Impact of Earthquakes; Tsunami; Nuclear Accidents and Holocaust; Case Studies of Nuclear Accidents

8. Social Issues, Human Population and the Environment Sustainable Development; Approaches to Resource Management; Climate change; Global Warming; Acid Rain; Ozone Layer Depletion; Environmental Ethics: Issues and Possible Solutions; Consumerism and Waste Products; Population Growth; The Definition of Overpopulation; The Causes of Rapid Population Growth; Food Production Distribution; Improvement in Public Health; Conquest of Disease; The Consequences of Rapid Population Growth;

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Family Welfare Programmes; Family Planning; Problems of Urbanisation in India; Wasteland Reclamation; Urban Problems Related to Energy; Resettlement and Rehabilitation of People: Case Studies; HIV/AIDS; Important Features of AIDS; The Virus and Course of Infection; Environmental Laws; The Water Act of 1974 (Amendment, 1988); The Air Act of 1981 (Amendment, 1987); Environmental Protection Act, 1986 (The EP Act); The Wildlife Protection Act of 1972; Forest Conservation Act, 1980; Environmental Management SystemStandards-ISO 14000 Series; Compliance to an ISO 14000 EMS; ISO 14000 Registration; What are the Principles Behind the ISO 14000 Series?; ISO 14000 Standards- “Organisation” and “Product-Oriented”; ISO 14000 and International Trade Index

I.1

CHAPTER

1 The Multidisciplinary Nature of Environmental Studies

INTRODUCTION The word environment is derived from the French verb ‘environner’ which means to ‘encircle or surround’. Thus our environment can be defined as the physical, chemical and biological world that surround us as well as the complex of social and cultural conditions affecting an individual or community. This broad definition includes the natural world and the technological environment as well as the cultural and social contexts that shape human lives. It includes all factors living and nonliving that affect an individual organism or population at any point in the life cycle; set of circumstances surrounding a particular occurrence and all the things that surrounds us. The two major components of environment are (Fig. 1.1): (1) Abiotic Environment: External chemical and physical factors like soil, sediments, nutrients, temperature, light, water and air. This is also called the Physical Environment. (2) Biotic Environment: All living organisms around us viz., plants, animals and microorganisms. This is also called the Living Environment. A large number of individuals belonging to different species which adjust, adopt, interact with each other and share the same general environment and resources form biotic component in an ecosystem based on the function and the general manner in which organisms obtain their food material, inorganic compounds with sunlight. ABIOTIC FACTORS • Temperature also affects the distribution of plants and animals. • As a rule, temperature are lower as you move towards the poles or as you climb in elevations. For this reason arctic or subarctic plant communities can be found at high elevations in the tropics. Com-5/d/Narosa/Environmental Chemistry--3-3-14 IV Proof

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• In the temperate latitudes living tolerate the temperature extremes • In the tropics there is very little organisms have a narrow range of

organisms must be able to of summer and winter. seasonal change and many temperature tolerance.

BIOTIC FACTORS • A living organism is also affected by the living components of its environment. • Competition exists for available food resources. • Predators feed on members of the population. • Microbes can bring diseases. • There may be competition for nesting space. • Plants may compete for the light needed to carryout photosynthesis. • These are many other biological factors determine the success of an individual or species.

Fig. 1.1 Components of Environment

Compared to the generally well defined processes that chemists study in the laboratory, those that occur in the environment are rather complex and must be viewed in terms of simplified models. A large part of this complexity is due to the fact that environmental chemistry must take into account five interacting and overlapping compartments or spheres of the environment, which affect each other and which undergo continual interchanges of matter and energy. Traditionally,

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1.3

environmental science has considered water, air, earth and life — i.e., is, the hydrosphere, the atmosphere, the geosphere and the biosphere (Fig. 1.2). When considered at all, human activities were generally viewed as undesirable perturbations on these other spheres, causing pollution and generally adverse effects. Such a view is too narrow, and we must include a fifth sphere, the anthrosphere, consisting of the things humans make and do. By regarding the anthrosphere as an integral part of the environment, humans can modify their anthrospheric activities to do minimal harm to the environment, or to even improve it. The atmosphere is a very thin layer compared to the size of Earth, with most atmospheric gases lying within a few kilometers of sea level. In addition to providing oxygen for living organisms, the atmosphere provides carbon dioxide required for plant photosynthesis and nitrogen that organisms use to make proteins. The atmosphere serves a vital protective function in that it absorbs highly energetic ultraviolet radiation from the sun that would kill living organisms exposed to it. A particularly important part of the atmosphere in this respect is the stratospheric layer of ozone, an ultraviolet-absorbing form of elemental oxygen. Because of its ability to absorb infrared radiation by which Earth loses the energy that it absorbs from the sun, the atmosphere stabilizes Earth’s surface temperature. The atmosphere also serves as the medium by which the solar energy that falls with greatest intensity in equatorial regions is redistributed away from the Equator. It is the medium in which water vapor evaporated from oceans as the first step in the hydrologic cycle is transported over land masses to fall as rain over land. Earth’s water is contained in the hydrosphere. Although frequent reports of torrential rainstorms and flooded rivers produced by massive storms might give the impression that a large fraction of Earth’s water is fresh water, more than 97% of it is seawater in the oceans. Most of the remaining fresh water is present as ice in polar ice caps and glaciers. A small fraction of the total water is present as vapor in the atmosphere. The water may be present on the surface as lakes, reservoirs and streams, or it may be underground as groundwater. The solid part of earth, the geosphere, includes all rocks and minerals. A particularly important part of the geosphere is soil, which supports plant growth, the basis of food for all living organisms. The lithosphere is a relatively thin solid layer extending from Earth’s surface to depths of 50–100 km. The even thinner outer

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Environmental Chemistry

skin of the lithosphere known as the crust is composed of relatively lighter silicate-based minerals. It is the part of the geosphere that is available to interact with the other environmental spheres and that is accessible to humans. The biosphere is composed of all living organisms. For the most part, these organisms live on the surface of the geosphere on soil, or just below the soil surface. The oceans and other bodies of water support high populations of organisms. Some life forms exist at considerable depths on ocean floors. In general, though the biosphere is a very thin layer at the interface of the geosphere with the atmosphere. The biosphere is involved with the geosphere, hydrosphere and atmosphere in biogeochemical cycles (Fig. 1.2) through which materials such as nitrogen and carbon are circulated. Through human activities, the anthrosphere has developed strong interactions with the other environmental spheres. Many examples of these interactions could be cited. By cultivating large areas of soil for domestic crops, humans modify the geosphere and influence the kinds of organisms in the biosphere. Humans divert water from its natural flow, use it, sometimes contaminate it, then return it to the hydrosphere. Emissions of particles to the atmosphere by human activities affect visibility and other characteristics of the atmosphere. The emission of large quantities of carbon dioxide to the atmosphere by combustion of fossil fuels may be modifying the heat-absorbing characteristics of the atmosphere to the extent that global warming is almost certainly taking place. The anthrosphere perturbs various biogeochemical cycles.

Fig. 1.2 Biogeochemical Cycle

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1.5

OBJECTIVES The chief objective of environmental education is that individual and social groups should acquire awareness, knowledge, develop attitudes, skills, abilities and participation in solving the real life environmental problems. There are three reasons for studying the state of the environment. • The first, is the need for information that clarifies modern environmental concepts like equitable use of natural resources, more sustainable lifestyles etc. • Second, there is a need to change the way in which we view our own environment, using practical approach based on observation and self learning. • Third, there is a need to create a concern for our environment that will trigger pro-environmental action, including simple activities we can do in our day to day life to protect it. Environmental science is essentially the application of scientific methods and principles to the study of environmental issues, so it has probably been around in some forms as long as science itself. Environmental science is often confused with other fields of related interest, especially ecology, environmental studies, environmental education and environmental engineering. Environmental science is not constrained with any one discipline and it is a comprehensive field. Environmental science is not ecology though that discipline may be included. Ecologists are interested in the interactions between some kind of organisms and its surroundings. Most ecological research and training does not focus on environmental problems except as those problems impact the organism of interest. Environmental scientists may or may not include organisms on their field of view. They mostly focus on the environmental problem which may be purely physical in nature. For e.g., Acid deposition can be studied as a problem of emissions and characteristic of the atmosphere without necessarily examining its impact on organisms. There are two types of environments: 1. Natural environment 2. Man-made environment

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1. Natural Environment: The environment in its original form without the interference of human beings is known as natural environment. It operates through self regulating mechanism called homeostasis i.e., any change in the natural ecosystem brought about by natural processes is counter balanced by changes in other components of environment. 2. Man-Made or Anthropogenic Environment: The environment changed or modified by the interference of human beings is called man-made environment. Man is the most evolved creature on this earth. He is modifying the environment according to his requirements without bothering for its consequences. Increased technologies and population explosion are deteriorating the environment more and more. Scope of Environmental Studies: Because, the environment is complex and actually made up of many different environments, including natural, constructed and cultural environments, environmental studies is the inter disciplinary examination of how biology, geology, politics policy studies, law, geology, religion engineering, chemistry and economics combine to inform the consideration of humanity’s effects on the natural world. This subject educates the students to appreciate the complexity of environmental issues and citizens and experts in many fields. By studying environmental science, students may develop a breadth of the interdisciplinary and methodological knowledge in the environmental fields that enables them to facilitate the definition and solution of environmental problems. The scope of environmental studies is that, the current trend of environmental degradation can be reversed if people of educated communities are organised and empowered; experts are involved in sustainable development. Environmental factors greatly influence every organism and their activities. The major areas in which the role of environmental scientists are of vital importance are natural resources, ecosystems, biodiversity and its conservation, environmental pollution, social issues and human population. MULTIDISCIPLINARY NATURE OF ENVIRONMENTAL STUDIES It is essentially a multidisciplinary approach and its components include biology, geology, chemistry, physics, engineering, sociology, health sciences, anthropology, economics, statistics and philosophy (Fig. 1.3).

The Multidisciplinary Nature of Environmental Studies

1.7

Fig. 1.3 Multidisciplinary Nature of Environment Studies

It is essentially a multidisciplinary approach. An understanding of the working of the environment requires the knowledge from wide ranging fields. The Table 1.1 shows a list of topics dealt commonly in air pollution and the related traditional fields of knowledge illustrating the interdisciplinary nature of the subject. Table 1.1 Interdisciplinary Nature of Environmental Science Ex: Air Pollution Environmental issue/topics

Major subject/Topic knowledge required

Nature and reaction of air pollutants effects Physics, Chemistry, Chemical engineering, Zoology, of air pollutants on human beings, animals Botany and various branches of Life sciences. and plants Effect of air pollutants on materials

Meteorology, Thermodynamics, Geography

Effect of climate on air pollution

Mathematical modelling etc.

Air pollution control devices

Physics, Chemistry and various branches of Engineering

History of air pollution and air pollution History episodes Economic impacts of air pollution

Economics, Demography

Sociological impacts of air pollution

Sociology

Alternative fuels

Various branches of Physical sciences

Conservation of resources and pollution Various branches of Physical and Political sciences control Ozone hole and global warming

Almost all fields under the Sun has got something to contribute to the understanding and prevention of these phenomenon

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IMPORTANCE OF ENVIRONMENTAL EDUCATION The environment studies enlighten us, about the importance of protection and conservation of our indiscriminate release of pollution into the environment. At present a great number of environment issues, have grown in size and complexity day-by-day, threatening the survival of mankind on earth. We study about these issues besides and effective suggestions in the environment studies (Fig. 1.4). Environment studies have become significant for the following reasons: 1. Environment Issues Being of International Importance It has been well recognised that environment issues like global warming and ozone depletion, acid rain, marine pollution and biodiversity are not merely national issues but are global issues and hence must be tackled with international efforts and cooperation. 2. Problems Cropped in the Wake of Development Development, in its wake gave birth to Urbanisation, Industrial Growth, Transportation Systems, Agriculture and Housing etc. However, it has become phased out in the developed world. The North, to cleanse their own environment has, fact fully, managed

Fig. 1.4 Major Environmental Problems

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1.9

to move ‘dirty’ factories of South. When the West developed, it did so perhaps in ignorance of the environmental impact of its activities. Evidently such a path is neither practicable nor desirable, even if developing world follows that. 3. Explosively Increase in Pollution World census reflects that one in every seven persons in this planted lives in India. Evidently with 16% of the world’s population and only 2.4% of its land area, there is a heavy pressure on the natural resources including land. Agricultural experts have recognised soils health problems like deficiency of micronutrients and organic matter, soil salinity and damage of soil structure. 4. Need for an Alternative Solution It is essential, specially for developing countries to find alternative paths to an alternative goal. We need a goal as under: (1) A goal, which ultimately is the true goal of development an environmentally sound and sustainable development. (2) A goal common to all citizens of our earth. (3) A goal distant from the developing world in the manner it is from the over-consuming wasteful societies of the “developed” world. 5. Need to Save Humanity from Extinction It is incumbent upon us to save the humanity from extinction. Consequent to our activities constricting the environment and depleting the biosphere, in the name of development. 6. Need for Wise Planning of Development Our survival and sustenance depend. Resources withdraw, processing and use of the product have all to by synchronised with the ecological cycles in any plan of development our actions should be planned ecologically for the sustenance of the environment and development. Four basic requirements of environmental management as under: (i) Impact of human activities on the environment, (ii) Value system, (iii) Plan and design for sustainable development, (iv) Environment education.

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Environmental Chemistry

NEED FOR PUBLIC AWARENESS It is essential to make the public aware of the formidable consequences of the Environmental degradation, if not retorted and reformative measures undertaken, would result in the extinction of life. We are facing various environmental challenges. It is essential to get the country acquainted with these challenges so that their acts may be eco-friendly. Some of these challenges are as under:

1. Growing Population A population of over thousands of millions is growing at 2.11% every year. Over 17 million people are added each year. It puts considerable pressure on its natural resources and reduces the gains of development. Hence, the greatest challenge before us is to limit the population growth. Although population control does automatically lead to development, yet the development leads to a decrease in population growth rates. For this development of the women is essential.

2. Poverty India has often been described a rich land with poor people. The poverty and environmental degradation have a nexus between them. The vast majority of our people are directly dependent on the nature resources of the country for their basic needs of food, fuel, shelter and fodder. About 40% of our people are still below the poverty line. Environment degradation has adversely affected the poor who depend upon the resources of their immediate surroundings. Thus, the challenge of poverty and the challenge environment degradation are two facets of the same challenge. The population growth is essentially a function of poverty. Because, to the very poor, every child is an earner and helper and global concerns have little relevance for him.

3. Agricultural Growth The people must be acquainted with the methods to sustain and increase agricultural growth with damaging the environment. High yielding varieties have caused soil salinity and damage to physical structure of soil.

4. Need to GroundWater It is essential of rationalising the use of groundwater. Factors like community wastes, industrial effluents and chemical fertilizers and

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pesticides have polluted our surface water and affected quality of the groundwater. It is essential to restore the water quality of our rivers and other waterbodies as lakes is an important challenge. It so finding our suitable strategies for consecration of water, provision of safe drinking water and keeping waterbodies clean which are difficult challenges is essential.

5. Development and Forests Forests serve catchments for the rivers. With increasing demand of water, plan to harness the mighty river through large irrigation projects were made. Certainly, these would submerge forests; displace local people, damage flora and fauna. As such, the dams on the river Narmada, Bhagirathi and elsewhere have become areas of political and scientific debate. Forests in India have been shrinking for several centuries owing to pressures of agriculture and other uses. Vast areas that were once green, stand today as wastelands. These areas are to be brought back under vegetative cover. The tribal communities inhabiting forests respects the trees and birds and animal that gives them sustenance. We must recognise the role of these people in restoring and conserving forests. The modern knowledge and skills of the forest department should be integrated with the traditional knowledge and experience of the local communities. The strategies for the joint management of forests should be evolved in a well planned way.

6. Degradation of Land At present out of the total 329 mha of land, only 266 mha possess any potential for production. Of this, 143 mha is agricultural land nearly and 85 suffers from varying degrees of soil degradation. Of the remaining 123 mha, 40 are completely unproductive. The remaining 83 mha is classified as forest land, of which over half is denuded to various degrees. Nearly 406 million head of livestock have to be supported on 13 mha, or less than 4% of the land classified as pasture land, most of which is overgrazed. Thus, our of 226 mha, about 175 mha or 66% is degraded to varying degrees. Water and wind erosion causes further degradation of almost 150 mha. This degradation is to be avoided.

7. Reorientation of Institutions The people should be roused to orient institutions, attitudes and infrastructures, to suit conditions and needs today. The change has

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to be brought in keeping in view India’s traditions for resources use managements and education etc. Change should be brought in education, in attitudes, in administrative procedures and in institutions. Because it affects way people view technology resources and development.

8. Reduction of Genetic Diversity Proper measures to conserve genetic diversity need to be taken. At present most wild genetic stocks have been disappearing from nature. Wilding including the Asiatic lion are facing problem of loss of genetic diversity. The protected areas network like sanctuaries, national parks, biosphere reserves are isolating populations. So, they are decreasing changes of one group breeding with another. Remedial steps are to be taken to check decreasing genetic diversity.

9. Evil Consequences of Urbanisation Nearly 27% Indians live in urban areas. Urbanisation and industrialisation has given birth to a great number of environmental problem that need urgent attention. Over 30% of urban Indians live in slums. Out of India’s 3,245 towns and cities, only 21 have partial or full sewerage and treatment facilities. Hence, coping with rapid urbanisation is a major challenge.

10. Air and Water Pollution Majority of our industrial plants are using outdated and population technologies and makeshift facilities devoid of any provision of treating their wastes. A great number of cities and industrial areas that have been identified as the worst in terms of air and water pollution. Acts are enforced in the country, but their implement is not so easy. The reason is their implementation needs great resources, technical expertise, political and social will. Again the people are to be made aware of these rules. Their support is indispensable to implement these rules. The following measures may help for the environmental awareness. 1. Join a group to study nature, such as WWF-1 or BNHS or another environmental group. 2. Begin reading news paper articles and periodicals like Down to Earth, WWF-1 Newsletter, BNHS, Hornbill, Sanctuary magazine

The Multidisciplinary Nature of Environmental Studies

3.

4.

5.

6. 7.

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etc which will tell you more about our current environmental issues. There are also several environmental websites. Lobby for conserving resources by taking-up the cause of environmental issues during discussions with friends and relatives. Practice and promote issues such as saving paper, saving water, reducing use of plastic, practicing the 3Rs principle of reduce, reuse, recycle and proper waste disposal. Join local movements that support activities like saving trees in your area, go on nature treks, recycle waste, and buy environment friendly products. Practice and promote good civic sense and hygiene such as enforcing no spitting or tobacco chewing, no throwing garbage on the road, no smoking in public places and no urinating or defecating in public places. Take part in events organised on World Environment Day, Wildlife Week etc. Visit a National park or Sanctuary or spend some time in whatever natural habitat you have near your surrounding home.

INSTITUTIONS IN ENVIRONMENT Managing natural resources require efficient institutions at all levels i.e., local, national, regional and global. Institutions, as defined by Young (1999), are systems of rules, decision-making procedures, and programs that give rise to social practices, assign roles to participants in these practices, and guide interactions among the occupants of the relevant roles. Institutions often figure prominently in efforts to solve or manage environmental problems. Several Government and Non-Government Organisations (NGO’S) are working towards environmental protection in our country. They play a role both in causing and in addressing problems arising from human-environment interactions. They have led to a growing interest in environmental protection and conservation of nature and natural resources. Among the large number of institutions that deal with environmental protection and conservation, a few well-known organisation include government organisations like the BSI and ZSI, and NGOs like the BNHS, WWF-1, etc. The Bombay Natural History Society (BNHS), Mumbai: It was founded on September 15, 1883 is one of the largest non-governmental

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organisations in India engaged in conservation and biodiversity research. It supports many research efforts through grants, and publishes a popular magazine called the Hornbill and also an internationally well-known the Journal of the Bombay Natural History Society. Its other publications include Salim Ali’s Handbook on Birds, JC Daniel’s Book of Indian Reptiles. SH Prater’s book of Indian Mammals and PV Bole’s book of Indian Trees. Many prominent naturalists, including the ornithologists Sálim Ali and S. Dillon Ripley have been associated with it. The BNHS has over the years helped the government to frame wildlife-related laws and has taken up battles such as the ‘save the silent valley’ campaign. World Wide Fund for Nature-India (WWF-1), New Delhi: The WWF-1 was initiated in 1969 in Mumbai, after which the headquarters were shifted to Delhi with several State, Divisional and Project offices spread across the India. In the early years it focused attention on wildlife education and awareness. It runs several programs, including the nature clubs of India program for school children and works as a think-tank and lobby force for environmental and development issues. Centre or Science and Environment (CSE), New Delhi: is a public interest research and advocacy organisation based in New Delhi. CSE researches into, lobbies for and communicates the urgency of development that is both sustainable and equitable. It has published a major document on the State of India’s Environment, the first of its kind to be produced as a citizen’s report on the environment. It also publishes a popular magazine, “Down to Earth” which is a science and environment fortnightly. It is involved in the publication of material in the form of books posters, video films and also conducts workshops and seminars on biodiversity related issues. The Centre’s efforts are built around five broad programmes: Communication for Awareness, Research and Advocacy, Education and Training, Knowledge Portal and Pollution Monitoring. C.P.R. Environmental Education Centre, Madras: The CPR-EEC was set up in 1988. CPREEC is a centre of excellence of the Ministry of Environment and Forests (MoEF), Government of India, established jointly by the Ministry and the C.P. Ramaswami Aiyar Foundation. It conducts a variety of programs to increase awareness and knowledge among the public i.e., school children, local communities, woman as main key target groups about the various aspects of environment. Its programs include components on wildlife and biodiversity issues. CPR-

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EEC also publishes large number of textbooks for school children and video on wheels for rural public. The CPR Environmental Education Centre received the Indira Gandhi Paryavaran Puraskar for the year 1996. Centre for Environment Education (CEE) in India was established in August, 1984 as a centre of excellence supported by the Ministry of Environment and Forests. The organisation works towards developing programmes and materials to increase awareness about the environment and sustainable development. The head office is located in Ahmedabad. The Centre has 41 offices including regional cells and several field offices, across India. It has international offices in Australia, Bangladesh and Sri Lanka. CEE’s primary objective is to improve public awareness and understanding of the environment with a view to promoting the conservation and sustainable use of nature and natural resources, leading to a better environment and a better quality of life. To this end, It undertakes demonstration projects in education, communication and development that endorse attitudes, strategies and technologies which are environmentally sustainable. CEE is committed to ensuring that due recognition is given to the role of education in the promotion of sustainable development. Bharati Vidyapeeth University, Institute of Environment Education and Research, Pune was established in 1993. This is part of the Bharati Vidyapeeth deemed University. Its major focus is to spread the message of the need for pro-environmental action in society at large through a dual strategy of formal and non-formal integrated activities. BVIEER is a one of a kind institution that caters to the need of Environment Education at all levels–Ph.D., M.Sc and Diploma. The distinctive characteristics of BVIEER are its wide mandate of teaching, research and extension. It implements a large outreach program that has covered over 435 schools, in which it trains teachers and conduct fortnightly various environment education programs. Biodiversity conservation in a major focus of its research initiatives. It develops low-cost interpretation centres for natural and architectural sites that are highly locale-specific as well as a large amount of innovative environment educational material for a variety of target groups. It has developed a teacher’s handbook linked to school curriculum and a textbook for UGC for the compulsory undergraduate course on environment. Its director has developed a CD-ROM on India’s biodiversity.

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The Salim Ali Centre for Ornithology and Natural History (SACON): It is an autonomous organisation with headquarters at Coimbatore. It is a national centre for information, education and research in ornithology and natural history in India. This institution was Dr. Salim Ali’s dream, which became a reality only after his demise and was named in honor of Salim Ali, the leading pioneer of ornithology in India. Its mission is “To help conserve India’s biodiversity and its sustainable use through research, education and peoples’ participation, with birds at the centre stage”. Wildlife Institute of India (WII), Dehradun: An autonomous institution of MoEF, GOI, established in 1982. It is an internationally acclaimed Institution, which offers training program, academic courses and advisory in wildlife research and management. The Institute is actively engaged in research across the breadth of the country on biodiversity related issues. Its most significant publication has been ‘Planning wildlife and protected area network for India (Rodgers and Panwar, 1988). It has environment impact assessment cell. It trains personnel in ecodevelopment, wildlife biology, habitat management and nature interpretation. Zoological Survey of India (ZSI): A premier organisation in zoological research and studies. The activities of the organisation are coordinated by the Conservation and Survey Division in the MoEF, GOI. This is the only taxonomic organisation in the country involved in the study of all kinds of animals from Protozoa to Mammalia, occurring in all possible habitats from deepest depth of the ocean to the peaks of Himalaya, was established on 1st July, 1916, to promote survey, exploration and research leading to the advancement in our knowledge of the various aspects of the exceptionally rich animal life. Over the years collected type of specimens on the basis of which our animal’s life has been studied. Its origins were collections based at the Indian museum at Calcutta, which was established in 1875. The older collections of the Asiatic society of Bengal and of the Indian museum were also transferred to the ZSI. Today, it has collection over a million specimens. This makes it one of the largest collections in Asia. Currently it is operated from 16 regional centres. The Madras Crocodile Bank Trust (MCBT): MCBT, the first crocodile conservation breeding in Asia, was founded in 1976 to conserve Indian crocodilians and establish program for the conservation and propagation of other species of endangered reptiles. Over the years, over 1500 crocodiles and several hundred eggs have been supplied

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to various state forest departments for restocking programmes in the wild, and for setting up breeding facilities in other state in India and neighboring countries. It is the one, which started the first sea turtle surveys and conservation program in India, including a sea turtle hatchery. It is involved in environmental education programs for the villages and schools that include nature camps, training workshop for teachers and youth from fishing villages. The Andaman and Nicobar islands Environmental team (ANET) a division of the MCBT was constituted in 1992. A base was set up by Harry Andrews in south Andaman for herpetological and other ecological studies in these islands. The Crocodile bank is the site of the irula Snake catchers’ cooperative society, which is an adivasi self-help project and supplies all of India’s snake and scorpion venom needed for the production of antivenom and for medical uses. MCBT personal also initiated the Irula Tribunal Women’s welfare society, which is primarily a society for reforestation of wastelands and income generation projects for irula women. Uttarkhand Seva Nidhi (USKN), Almora: It is a public charitable trust founded in 1967. This organisation was appointed as a nodal agency in 1987 by the Department of Education, Ministry of Human Resources Development, Government of India to undertake localespecific environmental education programmes both in rural schools and villages in the hill districts of Uttar Pradesh, now Uttaranchal. Subsequently, a research and resource centre, the Uttarakhand Environmental Education Centre (UEEC), was set up in 1993, also with support from the Department of Education. As activities continued to increase, a separate organisation, the Uttarakhand Seva Nidhi Paryavaran Shiksha Sansthan (USNPSS), a registered society, was set up in 1999 to handle all the environmental activities of the Nidhi. As Uttaranchal is a fragile ecological zone where human activities can cause extensive land degradation (deforestation and soil erosion) if not carried out in an environmentally-sound manner. The organisation conducts education, training and on the spot problem solving programmes with the aim of helping people to understand their surroundings from a broad ecological point of view and encourage them to organise themselves to deal with environmental problems that affect their daily lives, and to provide training in technical knowhow and practical skills. Its main target is sustainable resource use at the village level through training school children. Its environment education program covers about 500 schools.

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Kalpavriksh: This NGO, initially Delhi-based, is now working from Pune and is active in several other parts of India. Kalpavriksh worked on a variety of fronts: education and awareness; investigation and research; direct action and lobbying, and litigation with regard to environment and development issues. Its activities include talks and audiovisuals in schools and colleges, nature walks and outstation camp, organising student participation in ongoing campaigns including street demonstrations, pushing form consumer awareness regarding organic food, press statements, handling green alerts and meeting with city administrators. Kalpavriksh was among those responsible for developing India’s National Biodiversity Strategy and Action plan in 2003. The Botanical Survey of India (BSI) is an institution set up by the Government of India in 1887 to survey the plant resources of the Indian empire. The Botanical Survey was formally instituted on 13 February 1890 under the direction of Sir George King, who had been superintendent of Royal Botanic Garden, Calcutta since 1871. King became the first ex-officio Director of BSI. Presently, it has nine regional centres. It carries out surveys of plant resources in different regions. It monitors botanical resources by analysing their occurrence, distribution, ecology, economic utility, conservation, environment impact etc. PEOPLE IN ENVIRONMENT There are several internationally known environmentalist. Among those who have made landmark contributions include Charles Darwin, Ralph Emerson, Henry Thoreau, John Muir, Aldo Leopold, Rachel Carson and EO Wilson. Each of these thinkers looked at the environment from a completely different perspective. Charles Darwin: Wrote the origin of species, which brought to light the close relationship between habitats and species. It brought a new way of thinking about man’s relationship with other species that was based on evolution. Ralph Emerson: Spoke of the dangers of commerce to our environment way back in the 1840s. Henry Thoreau: In the 1860s wrote that the wilderness should be preserved after he had lived in the wilderness for a year. Thoreau had many theories and beliefs, which he poured out in his journals and books. Among these, the concept of human ecology of the relationship

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between humans and nature. He saw unity and community as important aspects of nature, and he saw all the disturbances in these links as caused by human beings. “Thank God men cannot fly, and lay waste the sky as well as the earth” is his famous quotation. John Muir: He was a Scottish-born American naturalist, author, and early advocate of preservation of wilderness in the United States. His letters, essays and books telling of his adventures in nature especially in the Sierra Nevada mountains of California, have been read by millions. His activism helped to save the Yosemite Valley, Sequoia National Park and other wilderness areas. He is remembered as having saved the great ancient Sequoia trees in California’s forests. In the 1890s he formed the ‘Sierra club’, which is major conservation NGO in the USA. Aldo Leopold: A forest official in the US in the 1920s, designed the early policies on wilderness conservation and wildlife management. He was considered the father of wildlife ecology and a true Wisconsin hero. His book, ‘A Sand County Almanac’ is acclaimed as the century’s literary landmark in conservation, which guided many to ‘live in harmony with the land and with one another’. Rachel Carson: An American, marine biologist and conservationist whose writings are credited with advancing the global environmental movement. She was nature writer, and written some of the books like ‘The Sea Around Us’ and ‘The Edge of the Sea’. In the late 1950s, Carson turned her attention to conservation and the environmental problems caused by synthetic pesticides. Then in 1962, she wrote ‘Silent Spring’, which was met with fierce denial from chemical companies, spurred a reversal in national pesticide policy—leading to a nationwide ban on DDT and other pesticides—and the grassroots environmental movement the book inspired led to the creation of the Environmental Protection Agency. Carson was posthumously awarded the Presidential Medal of Freedom by Jimmy Carter. EO Wilson: An entomologist, who envisioned that biological diversity was a key to human survival on Earth. He wrote ‘Diversity of life’ in 1993, which was awarded a prize for the best book published on environmental issues. He emphasised the risks to mankind due to manmade disturbances in natural ecosystems that are leading to the rapid extinction of species at the global level. There are several individuals, who have been instrumental in shaping the environmental history of our country. To name a few with their significant contributions goes as follows:

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Salim Ali: An Indian ornithologist and naturalist, known as the “birdman of India”. Salim Ali was among the first Indians to conduct systematic bird surveys across the country. He was instrumental in creating the Bharatpur bird sanctuary (Keoladeo National Park) and prevent the destruction of what is now the Silent Valley National Park. He was awarded India’s second highest Civilian honour, the Padma Vibhushan in 1976. His autobiography, fall of a sparrow, should be read by every nature enthusiast. He was our country’s leading conservation scientist and influenced environmental policies in our country for over 50 years. Smt. Indira Gandhi: As a Prime minister, played a very significant role in the preservation of India’s wildlife. During her period as PM, the network of protected areas (PAs) grew from 65 to 298 and the wildlife protection act was formulated. The Indian Board of wildlife was extremely active as she personally chaired all its meetings. S. P. Godrej: One of India’s greatest supporter of wildlife conservation and nature awareness programs. Between 1975 and 1999 S.P. Godrej received 10 awards for his conservation led to his playing a major advocacy role for wildlife in India. M. S. Swaminathan: He has founded the M.S. Swaminathan Research Foundation in Chennai, which does work on the conservation of biological diversity. Madhav Gadgil: A well-known ecologist in India. His interests range from board ecological issues such as developing community Biodiversity Registers and conserving sacred groves to studies on the behavior of mammals, birds and insects. His research interests include population biology, conservation biology, human ecology and ecological history, and he has published over 215 research papers 6 books and the editor for the series ‘lifescapes of peninsular India’. M. C. Mehta: Renown Environmental lawyer initiated the Government to implement Environmental education in schools and colleges and also struggles for protection of Taj Mahal and cleaning of Ganga water. Anil Agarwal: A journalist, who wrote the first report on the state of India’s Environment in 1982. He was the founder of CES, an active NGO that supports various environmental issues in time to time. Medha Patkar: Known as one of rural India’s champions, has supported the cause of the downtrodden tribal people whose environment is being affected by the dams on the Narmada river.

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Sunderlal Bahuguna: Chipko movement has become an internationally well-known example of a highly successful conservation action program through the efforts of local people for guarding their forest resources. His fight to prevent the construction of the Tehri Dam in a fragile earthquake-prone setting is a battle that he continues to wage. The Garhwal hills will always remember his dedication to the cause for which he has walked over 20 thousand kilometers.

CHAPTER

2 Ecosystem

WHAT IS ECOSYSTEM? All the living things that we know about are found on the Earth. From the biggest whale to the smallest bacteria, they all share this planet with us. The word ecology comes from the Greek word ‘oikos’ meaning ‘our home’. So the study of ecology is about the relationships that exist between all the living organisms (biotic) and non-living things (abiotic) in our environment. The term Ecology was coined by Earnst Haeckel in 1869. It is derived from the Greek words Oikos- home + logos- study. So ecology deals with the study of organisms in their natural home interacting with their surroundings. The surroundings or environment consists of other living organisms (biotic) and physical (abiotic) components. Basically it is diversity and relationships between the numerous living and non-living systems that surround us all. For example, living systems include bacteria, plants and animals, while non-living systems include such things as soil, air and water. Living and non-living systems are closely linked with each other and also each affects the other. CONCEPT OF AN ECOSYSTEM An ‘Ecosystem’ is a region with a specific and recognisable landscape form such as forest, grassland, desert, wetland or coastal area. The nature of the ecosystem is based on its geographical features such as hills, mountains, plains, rivers, lakes, coastal areas or islands. It is also controlled by climatic conditions such as the amount of sunlight, the temperature and the rainfall in the region. All the living organisms in an area live in communities of plants and animals. They interact with their non-living environment, and with each other at different points in time for a large number of reasons. Life can exist only in a small proportion of the earth’s land, water and its atmosphere. At a global level the thin layer of the earth on the land, the sea and the air, forms the biosphere.

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An ecosystem is a community of living organisms (plants, animals and microbes) in conjunction with the non-living components of their environment (things like air, water and mineral soil), interacting as a system. Basically, an ecosystem can be practically defined as a dynamic complex of plant, animal and microorganism communities, and the non-living environment, interacting as a functional unit. Ecosystems may be usefully identified through having strong interactions between components within their boundaries and weak interactions across boundaries. Ecosystems are well recognised as critical in supporting human well-being and the importance of their preservation under anthropogenic climate change. Ecosystems can be any size. An example of an ecosystem is a rotting log; another is a 100 kilometres stretch of coastline; another is the Kalahari Desert. When many similar ecosystems throughout the world are grouped together, we call them a biome. Biomes are large areas with similar flora, fauna, and microorganisms. Examples of biomes are tropical rainforests, tundra, desert, grassland and savannah. The term “ecosystem” was first coined by Roy Clapham in 1930, but it was ecologist Arthur Tansley, who fully defined the ecosystems concept. In his classic article of 1935, Tansley defined ecosystems as “The whole system, including not only the organism-complex, but also the whole complex of physical factors forming what we call the environment”. Eugene Odum, a major figure in advancing the science of ecology, deployed the ecosystem concept in a central role in his seminal textbook on ecology, defining ecosystems as: “Any unit that includes all of the organisms (i.e. the “community”) in a given area interacting with the physical environment so that a flow of energy leads to clearly defined trophic structure, biotic diversity, and material cycles (i.e. exchange of materials between living and non-living parts) within the system is an ecosystem”. CHARACTERISTICS OF AN ECOSYSTEM 1. It is normally an open system with a continuous, but variable influx and loss of materials and energy. 2. An ecosystem is an overall integration of the whole mosaic of interacting organisms and their environment.

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3. It is a basic, functional unit with no limits of boundaries. 4. It consists of biotic and abiotic components interacting with each other. 5. Its functional unit is capable of energy transformation, circulation and accumulation. 6. An ecosystem is the smallest unit of biosphere. 7. Different types of ecosystem are present in different areas. STRUCTURE OF AN ECOSYSTEM By Structure of an Ecosystem, we mean • The composition of biological community including species, numbers, biomass, life history and distribution in space etc. • The quantity and distribution of non-living materials like nutrients, water etc. • The conditions of existence such as temperature, light etc. An ecosystem possesses both biotic (living) and abiotic non-living components. Biotic components: Biotic component of the ecosystem can be categorised as either producers or consumers. Producers are autotrophic organisms with the capability of carrying out photosynthesis and making food themselves, and indirectly for the other organisms as well. In terrestial ecosystems the producers are predominantly green plants, while in freshwater and marine ecosystems the dominant producers are various species of algae. Consumers are heterotrophic organisms that used food that has already been performed by other organisms. It is possible to distinguish four types of consumers, depending on their food source. Producers or autotrophs: These are organisms that make their own organic material from simple inorganic substances. For most of the biosphere the main producers are photosynthetic plants and algae that synthesis glucose from carbon dioxide and and water. The glucose produced is used both as an energy source and combines with other molecules from the soil to build biomass. It is the biomass that provides the total theoretical energy available to all non-photosynthesising organisms in the ecosystem (Fig. 2.1). Consumers or heterotrophs: These are organisms that obtain organic molecules by eating or digesting other organisms. These are the herbivores and carnivores of the ecosystem. By eating other

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Fig. 2.1 Producers

organisms they gain both food as an energy supply and nutrient molecules from within the biomass ingested. For instance to build new protein consumers have to eat protein contain amino acids(Fig. 2.2).

Fig. 2.2 Consumers

Consumers are of following types. Herbivores: Herbivores are living organisms that mostly feed on plant based products like leaves, grass, some fruits and shrubs. Carnivores: Carnivores are meat eating animals, that acquire their food and energy and nutrients needs of their bodies through feeding on other animal tissues. Carnivores can either be scavengers or predators. Scavengers are those consumers who feed on dead organisms that have either died through the natural way or were killed by predators like the lion. The predators rarely eat dead organisms but instead hunt and kill their prey before they eat them. The carnivores are mostly to

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be found in the animal kingdom but there exists some few of them in the plant kingdom. There are carnivorous plants that feed on such things as insects that come near them. Decomposers: These are the waste managers of any ecosystem. They are the final link in a food web, breaking-down dead organic matter (DOM), from producers and consumers and ultimately returning energy to the atmosphere in respiration and inorganic molecules bake to the soil during decomposition. Decomposers can be divided into two groups based on their mode of nutrition. 1. Detritivores are organisms that ingest non-living organic matter. These can include earthworms, beetles and many other invertebrates. 2. Saprotrophs are organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion. These include Fungi and Bacteria (Fig. 2.3).

Fig. 2.3 Decomposers

Abiotic Components Abiotic components of an ecosystem consist of the non-organic aspects of the environment that determine what life forms can thrive. Examples of abiotic components are temperature, average humidity, topography

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and natural disturbances. Temperature varies by latitude; locations near the equator are warmer than are locations near the poles or the temperate zones. Humidity influences the amount of water and moisture in the air and soil, which, in turn, affect rainfall. Topography is the layout of the land in terms of elevation. For example, land located in the rain shadow of a mountain will receive less precipitation. Natural disturbances include tsunamis, lightning storms, hurricanes and forest fires. Actually abiotic components are such physical and chemical factors of an ecosystem as light, temperature, atmosphere gases(nitrogen, oxygen, carbon dioxide are the most important), water, wind, soil. These specific abiotic factors represent the geological, geographical, hydrological and climatological features of a particular ecosystem. Separately: • Water, which is at the same time an essential element to life and a milieu. • Air, which provides oxygen, nitrogen and carbon dioxide, to living species and allows the dissemination of pollen and spores. • Soil, at the same time source of nutriment and physical support. The salinity, nitrogen and phosphorus content, ability to retain water and density are all influential. • Temperature, which should not exceed certain extremes, even if tolerance to heat is significant for some species. • Light, which provides energy to the ecosystem through photosynthesis. • Natural disasters can also be considered abiotic. According to the intermediate disturbance hypothesis, a moderate amount of disturbance does good to increase the biodiversity.

Interaction Biotic components and abiotic components of an ecosystem interact with and affect one another. If the temperature of an area decreases, the life existing there must adapt to it. Global warming, or the worldwide increase in temperature due to the greenhouse effect, will speed up the metabolism rates of most organisms. Metabolic rate increases with temperature because the nutrient molecules in the body are more likely to contact and react with one another when excited by heat. According to “Science News”, tropical ectothermic

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– cold-blooded -- organisms could experience increased metabolic rates from an increase of as little as 5°C because their internal temperature is almost entirely dependent on external temperature. To adapt to these circumstances, cold-blooded life forms could reside in the shade and not actively search for food during daylight when the sun is at its brightest. FUNCTION OF AN ECOSYSTEM The function of an ecosystem is a broad and vast topic. The function of an ecosystem can be best studied by understanding the history of ecological studies. The function of an ecosystem can be studied under the following heads. 1. Trophic level interaction 2. Energy flow 3. Biogeochemical cycles 4. Ecological succession 5. Primary and secondary production 6. Regulation of ecosystem Trophic level interaction deals with how the members of an ecosystem are connected based on nutritional needs. Ecological succession deals with the changes in features/members of an ecosystem over a period of time. Biogeochemistry is focused upon the cycling of essential materials in an ecosystem. Energy flow shows how energy flows in ecosystem while primary and secondary production deals with conversion of radiant energy in organic substances and Ecosystem development and Regulation deals with development and self regulation of ecosystem.

Trophic Level Interaction Trophic level interaction was developed by Zoologist Charles Elton. It deals with who eats who and is eaten by whom in an ecosystem. The study of trophic level interaction in an ecosystem gives us an fair idea about the energy flow through the ecosystem. The trophic level interaction involves three concepts namely (i) Food chain (ii) Food web (iii) Ecological pyramids

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FOOD CHAIN Flow of energy in an ecosystem is one-way process. The sequence of organism through which the energy flows, is known as food chain (Fig. 2.4). The transfer of food energy from the source in plants through a series of organisms with repeated eating and being eaten is referred to as the food chain (Odum 1971). Plants are eaten by insects, insects are eaten by frogs, the frogs are eaten by fish and fishes are eaten by humans. The pattern of eating and being eaten forms a linear chain called food chain. Such a food chain can always be traced back to the producers. Fig. 2.4 Food Chain A food chain shows how energy is transferred from one living organism to another via food. It is important for us to understand how the food chain works, so that we know what are the important living organisms that make-up the food chain and how the ecology is balanced. Photosynthesis is only the beginning of the food chain. There are many types of animals that will eat the products of the photosynthesis process. Examples are deer eating shrub leaves, rabbits eating carrots, or worms eating grass. When these animals eat these plant products, food energy and organic compounds are transferred from the plants to the animals. The primary producers trap radiant energy of the sun and transfers to chemical or potential energy of organic compounds like proteins, fats and carbohydrates. The formation of ATP during photosynthesis is the first nutritional level. ATP is stored in food matter which is utilised by herbivores, the plant eaters. This process constitutes the second tropic level. When a herbivores animal eats the plant, the organic compounds re oxidised and the energy is liberated. Flow of energy is greatly reduced at each successive level of nutrition because

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of the energy utilisation by the organisms and heat loses at each step in transformation of energy. This accounts for the decrease in biomass at each successive level. It should be noted that the number of steps in a food chain are always restricted to maximum four or five steps. Humans are at the end of a number of food chains. TYPES OF FOOD CHAIN There are two types of food chain in the nature.

1. Grazing Food Chain The consumers (which starts the food chain) utilising the plant as their food, constitute grazing food chain (Fig. 2.5). This food chain begins from green plants and the primary consumer is herbivore. Most of the ecosystem in nature follows this type of food chain. From energy view point such chains are very important. For example, Grass Æ Grasshopper Æ Birds Æ Sun Falcon. There are two types of Grazing food Primary Green producers chain such as – plants (a) Predator chain Primary Herbivores (b) Parasitic chain consumers (a) Predator chain: Here one animal captures and devours another animal. Secondary consumers The animal which is being eaten, is called “Prey” and the animal which Carnivores eats it, is called “Predator”. The Tertiary consumers predator chain is formed of plants, herbivores, primar y carnivores, secondary carnivores and so on. Quaternary consumers (b) Parasitic chain: The plants and animals of grazing food chain are infected by parasites. When Decosposers the smaller organisms (parasites) Bacteria consumes larger ones without right and fungi killing of the host, the food chain is called parasitic food chain. Fig. 2.5 Grazing Food Chain

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2. Detritus Food Chain The organic wastes, exudates and dead matter derived from the grazing food chain are generally termed detritus. The energy contained in this detritus in not lost to the ecosystem as a whole; rather it serves as the source of energy for a group of organisms (detritivores) that are separated from the grazing food chain, and generally termed as the detritus food chain (Fig. 2.6).

Fig. 2.6 Detritus Food Chain

The detritus food chain represents an exceedingly important component in the energy flow of an ecosystem. Indeed in some ecosystems, considerably more energy flows through the detritus food chain than through the grazing food chain. In the detritus food chain the energy flow remains as a continuous passage rather than as a stepwise flow between discrete entities. energy storage for detritus food chain may be largely external to the organisms and the detritus itself. The organisms of the detritus food chain are many and include algae, bacteria, slime molds, actinomycetes, fungi. Protozoa, insects mites. Crustacea, centipedes, molluscs, rotifers, annelid worms, nematodes and some vertebrates. Some species are highly specific in their food requirements and some can eat almost anything. In a community of organisms in a shallow sea, about 30% of the total energy flows via detritus food chain. However, in a forest with large biomass of plants and a relatively small biomass of animals even larger portion of energy flow may be obtained via detritus pathways. SIGNIFICANCE OF FOOD CHAIN 1. The knowledge of food chain helps in understanding the feeding relationship as well as the interaction between organism and ecosystem. 2. It also help in understanding the mechanism of energy flow and circulation of matter in ecosystem.

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3. It also helps to understand the movement of toxic substance and the problem associated with biological magnification in the ecosystem. FOOD WEB In an ecosystem, the various food chains are interconnected with each other to form a network. The interlocking of many food chains is called food web (Odum, 1971). A food chain represents only one part of energy flow through an ecosystem, whereas the ecosystem may consist of several interrelated food chains. But for simplicity, in general, a food chain implies a simple isolated relationship which rarely occurs in ecosystems. The same food resource may be a part of more than one chain. This is possible, when the resource is at the lower tropic level. Accordingly, the inter-connected networks of feeding relationships is known as food webs. Most animals in nature utilise more than one species for their food. Therefore, food chains in an ecosystem become inter-connected with each other which are summarised in Fig. 2.7.

Fig. 2.7 Food Web of a Pond Community

Food web of an ecosystem shows how different food chains link together, since most of the animals eat more than one food type and are in turn food for more than one consumer. Several different trophic levels are recognised in any complex food webs. This is mentioned as under: An example of food web may consist of as many as food chain. For Example: (i) Grass Æ Grasshopper Æ Hawk (ii) Grass Æ Grasshopper Æ Lizard Æ Hawk

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(iii) Grass Æ Rabbit Æ Hawk (iv) Grass Æ Mouse Æ Hawk (v) Grass Æ Mouse Æ Snake Æ Hawk Most of the animals are able to eat a variety of foods. A successful herbivore or carnivore is an animal which is able to change its diet and eat what is available at any particular time. A successful predator will also hunt prey which is easy to catch, such as an old or injured animal. It would be a waste of energy to hunt and chase a prey for a long time. TYPES OF FOOD WEBS Food webs describe the relationships — links or connections — among species in an ecosystem, but the relationships vary in their importance to energy flow and dynamics of species populations. Some tropic relationships are more important than others in dictating how energy flows through ecosystems. Some connections are more influential on species population change. Based on different ways in which species influence one another, Robert Paine proposed three types of food webs:

1. Topological Food Webs This type of food webs emphasize feeding relationships among species, portrayed as links in a food web.

2. Energy Flow Food Webs These food webs quantify energy flow from one species to another. Thickness of an arrow reflects the strength of the relationship.

3. Functional Webs or Interaction Food Webs Functional food webs represent the importance of each species in maintaining the integrity of a community and reflect influence on the growth rate of other species. APPLICATIONS OF FOOD WEBS Food webs are constructed to describe species interactions (direct relationships)

The fundamental purpose of food webs is to describe feeding relationship among species in a community. Food webs can be constructed

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to describe the species interactions. All species in the food webs can be distinguished into basal species (autotrophs, such as plants), intermediate species (herbivores and intermediate level carnivores, such as grasshopper and scorpion) or top predators (high level carnivores such as fox). These feeding groups are referred as trophic levels. Basal species occupy the lowest trophic level as primary producer. They convert inorganic chemical and use solar energy to generate chemical energy. The second trophic level consists of herbivores. These are first consumers. The remaining trophic levels include carnivores that consume animals at trophic levels below them. The second consumers (trophic level 3) in the desert food web include birds and scorpions, and tertiary consumers making up the fourth trophic level include bird predators and foxes. Grouping all species into different functional groups or tropic levels helps us simplify and understand the relationships among these species. Food webs can be used to illustrate indirect interactions among species

Indirect interaction occurs when two species do not interact with each other directly, but influenced by a third species. Species can influence one another in many different ways. One example is the keystone predation are demonstrated by Robert Paine in an experiment conducted in the rocky intertidal zone. This study showed that predation can influence the competition among species in a food web. The intertidal zone is home to a variety of mussels, barnacles, limpets, and chitons. All these invertebrate herbivores are preyed upon by the predator starfish Pisaster. Starfish was relatively uncommon in the intertidal zone, and considered less important in the community. When researchers manually removed the starfish from experimental plots while leaving other areas undisturbed as control plots, they found that the number of prey species in the experimental plots dropped from 15 at the beginning of the experiment to 8 (a loss of 7 species) two years after the starfish removal while the total of prey species remained the same in the control plots. He reasoned that in the absence of the predator starfish, several of the mussel and barnacle species (that were superior competitors) excluded the other species and reduced overall diversity in the community. Predation by starfish reduced the abundance of mussel and opened up space for other species to colonise and persist. This type of indirect interaction is called keystone predation.

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Environmental Chemistry

Food webs can be used to study bottom-up or top-down control of community structure

Food webs illustrate energy flow from primary producers to primary consumers (herbivores), and from primary consumers to secondary consumers (carnivores). The structure of food webs suggests that productivity and abundance of populations at any given trophic level are controlled by the productivity and abundance of populations in the trophic level below them). This phenomenon is known as bottom-up control. Correlations in abundance or productivity between consumers and their resources are considered as evidence for bottom-up control. For example, plant population densities control the abundance of herbivore populations which in turn control the densities of the carnivore populations. Thus, the biomass of herbivores usually increases with primary productivity in terrestrial ecosystems. Top-down control occurs when the population density of a consumer can control that of its resource, for example, predator populations can control the abundance of prey species. Under top-down control, the abundance or biomass of lower trophic levels depends on effects from consumers at higher trophic levels. A trophic cascade is a type of topdown interaction that describes the indirect effects of predators. In a trophic cascade, predators induce effects that cascade down the food chain and affect biomass of organisms at least two links away. Nelson Hairston, Frederick Smith and Larry Slobodkin first introduced the concept of top-down control with the frequently quoted “the world is green” proposition. They proposed that the world is green because carnivores depress herbivores and keep herbivore populations in check. Otherwise, herbivores would consume most of the vegetation. Indeed, a bird exclusion study demonstrated that there were significantly more insects and leaf damage in plots without birds compared to the control. Food webs can be used to reveal different patterns of energy transfer in terrestrial and aquatic ecosystems

Patterns of energy flow through different ecosystems may differ markedly in terrestrial and aquatic ecosystems. Food webs (i.e. energy flow webs) can be used to reveal these differences. Shurin provided evidence for systematic difference in energy flow and biomass partitioning between producers and herbivores, detritus and decomposers, and higher trophic levels in food webs. Carbon fixed by primary productivity across different ecosystems was used to show different patterns in food chains between terrestrial and aquatic

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ecosystems. On average, the turnover rate of phytoplankton is 10 to 1000 times faster than that of grasslands and forests, thus, less carbon is stored in the living autotroph biomass pool, and producer biomass is consumed by aquatic herbivores at 4 times the terrestrial rate. Herbivores in terrestrial ecosystems are less abundant but decomposers are much more abundant than in phytoplankton dominated aquatic ecosystems. In most terrestrial ecosystems with high standing biomass and relatively low harvest of primary production by herbivores, the detrital food chain is dominant. In deep-water aquatic ecosystems, with their low standing biomass, rapid turnover of organisms, and high rate of harvest, the grazing food chain may be dominant. ECOLOGICAL PYRAMIDS Charles Elton developed the concept of ecological pyramid. After his name these pyramids are also called as Eltonian pyramids. It is a graphical representation or pyramid shaped diagram which depicts the number of organisms, biomass and productivity at each trophic level. Ecological pyramids begin with the producers at the bottom and proceed through the different trophic level. An ecological pyramid is an illustration of the reduction in energy as you move through each feeding (trophic) level in an ecosystem. The base of the pyramid is large since the ecosystem’s energy factories (the producers) are converting solar energy into chemical energy via photosynthesis. A food chain can also depict a reduction in energy at each feeding level if the arrows, drawn between the different levels, continue to be reduced in size. There are three types of ecological pyramids as follows: 1. Pyramid of number 2. Pyramid of biomass 3. Pyramid of energy

1. Pyramid of Numbers The pyramid of numbers represents the number of organisms in each trophic level. This pyramid consists of a plot of relationships between the number herbivores (primary consumers), first level carnivore (secondary consumers), second level carnivore (tertiary consumers) and so forth. This shape varies from ecosystem to ecosystem because the number of organisms at each level is variable (Fig. 2.8).

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Environmental Chemistry

Fig. 2.8 Pyramid of Number in a Grassland

Upright, partly upright and inverted are the three types of pyramids of numbers. An aquatic ecosystem is an example of upright pyramid where the number of organisms becomes fewer and fewer higher up in the pyramid. A forest ecosystem is an example of a partially upright pyramid, as fewer producers support more primary consumers, but there are less secondary and tertiary consumers. An inverted pyramid of numbers is one where the number of organisms depending on the lower levels grows closer toward the apex. A parasitic food chain is an example. Upright pyramid of number: In aquatic and grassland ecosystem numerous small autotrophs support lesser herbivores which support further smaller number of carnivores and hence the pyramidal structure is upright (Fig. 2.9).

Fig. 2.9

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Partly upright pyramid of number: In forest ecosystem lesser number

of producers support greater number of herbivores who in turn support a fewer number of carnivores (Fig. 2.10).

Fig. 2.10

Inverted pyramid of number: In parasitic food chain one primary producer support numerous parasites which support still more hyperparasites (Fig. 2.11).

Fig. 2.11

The grasses occupy the lowest trophic level and they are abundantly present in the grassland ecosystem. The deers occupy the second level; their number is less than compared to the grasses. The wolves, which feed upon the deers, are far less in number when compared to the number of deers. The lions, which occupy the next trophic level, feed upon wolves, and the number of individuals in the last trophic level is greatly reduced. In the parasitic food chain, the pyramid of numbers is founds to be inverted. Here, a single plant or tree might support varieties of herbivore. These herbivores like birds in turn, support varieties of parasites like lice, bugs that outnumber the herbivores. Subsequently each parasite might support a number of hyperparasites like bacteria and fungi, which will outnumber the parasites. Thus from the producer level onwards, towards the consumers, in the parasitic food chain there is a gradual increase in the number of organisms, instead of the usual decrease.

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Environmental Chemistry

As a result of this, the pyramid becomes inverted in the parasitic food chain. There is a gradual increase in the numbers of individuals from autotrophs to the higher trophic levels. 1. It shows the number of organism at different levels. 2. The smaller animals are preyed upon larger animals and smaller animals increase faster in number of organism at each stage of food chain, makes a triangular figure that is known as pyramid of number. A bar diagram that indicates the relative numbers of organisms at each trophic level in a food chain. The length of each bar gives a measure of the relative numbers. Pyramids begin with producers, usually the greatest number at the bottom decreasing upwards (Fig. 2.12).

Fig. 2.12 Pyramid of Number for a Grazing Ecosystem

Advantages

This is a simple easy method of giving an overview and is good at comparing changes in population numbers with time or season (Fig. 2.13).

Fig. 2.13 Pyramid of Number Oak Wood

Disadvantages

All organisms are included regardless of their size, therefore a system say based on an oak tree would be inverted (have a small bottom and bet larger as it goes up trophic levels). Also they do not allow for juveniles or immature forms. Numbers can be to great to represent accurately.

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2. Pyramid of Biomass Biomass is renewable organic (living) material. A pyramid of biomass is a representation of the amount of energy contained in biomass, at different trophic levels for a particular time. It is measured in grams per meter or calories per meter. This demonstrates the amount of matter lost between trophic levels. Each level is dependent on its lower level for energy, hence the lower level determines how much energy will be available to the upper level. Also, energy is lost in transfer so the amount of energy is less higher up the pyramid. A biomass pyramid represents the actual biomass (dry mass of all organisms) in each trophic level in an ecosystem. Most biomass pyramids narrow sharply from the producer level at the base to the top-level consumers at the peak. There are some exceptions, however, in certain aquatic ecosystems, the zooplankton (primary consumers) consume the phytoplankton (producers) extremely rapidly. As a result, the zooplankton have a greater mass at any given time than the phytoplankton. The phytoplankton grow and reproduce at such a rapid rate that they can support a consumer population that has a greater biomass. A biomass pyramid for this ecosystem would appear top heavy.

Fig. 2.14 Upright Pyramid of Biomass in a Terrestrial Ecosystem

There are two types of biomass pyramids: upright and inverted. An upright pyramid is one where the combined weight of producers is larger than the combined weight of consumers. An example is a forest ecosystem. An inverted pyramid is one where the combined weight of producers is smaller than the combined weight of consumers. An example is an aquatic ecosystem (Fig. 2.14).

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Environmental Chemistry

Upright pyramid of biomass: When larger weight of producers support a smaller weight of consumers an upright pyramid results. e.g., forest ecosystem (Fig. 2.15).

Fig. 2.15 Upright Pyramid of Biomass

Inverted pyramid of biomass: When smaller weight of producers supports larger weight of consumers an inverted pyramid of biomass is formed e.g., aquatic ecosystem (Fig. 2.16).

Fig. 2.16 Inverted Pyramid of Biomass

The biomass in autotrophs like algae, green flagellates, green plants etc., is the maximum. The biomass is considerably less in the next trophic level occupied by secondary consumers like small fishes. The least amount of biomass is present in the last trophic level. 1. This pyramid shows the total biomass at each trophic level in a food chain. 2. It indicates a decrease in the biomass at each trophic level from the base to apex of pyramid.

3. Pyramid of Energy The pyramid of energy represents the total amount of energy consumed by each trophic level. An energy pyramid is always upright as the total amount of energy available for utilisation in the layers above is less than the energy available in the lower levels. This happens because

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Fig. 2.17 Pyramid of Energy

during energy transfer from lower to higher levels, some energy is always lost (Fig. 2.17). Here there will be gradual decrease in the availability of energy from the autotrophs higher trophic levels. In other words, there is decrease in energy flow from autotrophs on at successive trophic levels. The pyramid of energy is drawn after taking into consideration the total quantity of energy utilised by the trophic levels in an ecosystem over a period of time. As the quantity of energy available for utilisation in successive trophic levels is always less because there is loss of energy in each transfer, the energy pyramid will always be upright (Fig. 2.18).

Fig. 2.18

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Environmental Chemistry

In the course of energy flow from one organism to the other, considerable loss of energy happens in the form of heat. More energy is available in the autotrophs i.e., the primary consumers. The least amount of available energy will be in the tertiary consumer. Therefore, shorter the food chain, greater is the amount of energy available at the top. In general, an average of only 10% of the available energy at a trophic level is converted to biomass in the next higher trophic level. The rest of the energy—about 90%—is lost from the ecosystem as heat (Fig. 2.19).

Fig. 2.19 Showing Gradual Loss of Energy

This generalised energy pyramid indicates that only 10% of the energy available at a trophic level is typically converted to new biomass in the next trophic level. The amount of energy available to the top-level consumer is tiny compared to that available to primary consumers. For this reason, it takes a lot of vegetation to support higher trophic levels. This explains why most food chains are limited to three or four levels; there is simply not enough energy at the top of an energy pyramid to support another trophic level. For instance, lions and killer whales have no natural predators; the energy stored in populations of these top-level consumers is not enough to feed yet another trophic level 1. The energy pyramid always upright and errect. 2. It shows the rate of energy flows at different trophic levels.

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3. It shows that energy is maximum at producer level and minimum at the carnivores’ level. 4. At every successive trophic level there is a loss of energy in the form of heat, respiration etc. FLOW OF ENERGY IN AN ECOSYSTEM Ecosystems maintain themselves by cycling energy and nutrients obtained from external sources. At the first trophic level, primary producers (plants, algae, and some bacteria) use solar energy to produce organic plant material through photosynthesis. Herbivores— animals that feed solely on plants—make-up the second trophic level. Predators that eat herbivores comprise the third trophic level; if larger predators are present, they represent still higher trophic levels. Organisms that feed at several trophic levels (for example, grizzly bears that eat berries and salmon) are classified at the highest of the trophic levels at which they feed. Decomposers, which include bacteria, fungi, molds, worms, and insects, breakdown wastes and dead organisms and return nutrients to the soil. On average about 10% of net energy production at one trophic level is passed on to the next level. Processes that reduce the energy transferred between trophic levels include respiration, growth and reproduction, defecation, and nonpredatory death (organisms that die but are not eaten by consumers). The nutritional quality of material that is consumed also influences how efficiently energy is transferred, because consumers can convert high-quality food sources into new living tissue more efficiently than low-quality food sources. The low rate of energy transfer between trophic levels makes decomposers generally more important than producers in terms of energy flow. Decomposers process large amounts of organic material and return nutrients to the ecosystem in inorganic form, which are then taken-up again by primary producers. Energy is not recycled during decomposition, but rather is released, mostly as heat (this is what makes compost piles and fresh garden mulch warm). Figure 2.20 shows the flow of energy (dark arrows) and nutrients (light arrows) through ecosystems. TEN PER CENT LAW Lindemann (1942) put forth 10% law for the transfer of energy from one trophic level to the next.

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Environmental Chemistry

Fig. 2.20 Energy and Nutrient Transfer through Ecosystems

According to the law, during the transfer of organic food from one trophic level to the next, only about 10% of the organic matter is stored as flesh. The remaining is lost during transfer or broken-down in respiration (Fig. 2.21).

Fig. 2.21 Ten Per cent Law

Plants utilise sun energy for primary production and can store only 10% of the utilised energy as net production available for the herbivores. When the plants are consumed by animal, about 10% of the energy in the food is fixed into animal flesh which is available for next trophic level (carnivores). When a carnivore consumes that animal, only about 10% of energy is fixed in its flesh for the higher level. So at each transfer 80-90% of potential energy is dissipated as heat (second law of thermodynamics) where only 10-20% of energy is available to the next trophic level.

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Fig. 2.22 Progressive Loss of Energy in Food Chain

In an ecosystem energy flows as follows: • Solar energy is fixed by the photoautotrophs, called primary producers, like green plants. Primary consumers absorb most of the stored energy in the plant through digestion, and transform it into the form of energy they need, such as adenosine triphosphate (ATP), through respiration. A part of the energy received by primary consumers, herbivores, is converted to body heat (an effect of respiration), which is radiated away and lost from the system. The loss of energy through body heat is far greater in warm-blooded animals, which must eat much more frequently than those that are cold-blooded. Energy loss also occurs in the expulsion of undigested food (egesta) by excretion or regurgitation. • Secondary consumers, carnivores, then consume the primary consumers, although omnivores also consume primary producers. Energy that had been used by the primary consumers for growth and storage is thus absorbed into the secondary consumers through the process of digestion. As with primary consumers, secondary consumers convert this energy into a more suitable form (ATP) during respiration. Again, some energy is lost from the system, since energy which the primary consumers had used for respiration and regulation of body temperature cannot be utilised by the secondary consumers. • Tertiary consumers, which may or may not be apex predators, then consume the secondary consumers, with some energy passed on and some lost, as with the lower levels of the food chain.

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Environmental Chemistry

• A final link in the food chain are decomposers which break down the organic matter of the tertiary consumers (or whichever consumer is at the top of the chain) and release nutrients into the soil. They also breakdown plants, herbivores and carnivores that were not eaten by organisms higher on the food chain, as well as the undigested food that is excreted by herbivores and carnivores. Saprotrophic bacteria and fungi are decomposers, and play a pivotal role in the nitrogen and carbon cycles. CONSERVATION OF ENERGY Laws of physics and chemistry apply to ecosystems, particularly at energy flow as follows • The first law of thermodynamics states that energy cannot be created or destroyed, only transformed. As per first law of thermodynamics Energy enters an ecosystem as solar radiation. This solar energy is then converted to chemical energy by plants and other photosynthetic organisms. During this conversion, some of the energy is dissipated from organisms as heat. Despite this, the total amount of energy does not change. Total solar energy = Total energy stored in organic molecules + Energy reflected and dissipated as heat. • The second law of thermodynamics states that every exchange of energy increases the entropy (disorder) of the universe. • This implies that energy transfers are not completely efficient. Rather, some energy is always lost as heat. • All energy flowing through an ecosystem is ultimately dissipated into space as heat. Thus, without the sun continuously providing energy to Earth, most ecosystems would vanish. BIOGEOCHEMICAL CYCLES IN AN ECOSYSTEM A biogeochemical cycle is a circuit/pathway by which a chemical element moves through the biotic and the abiotic factors of an ecosystem. It is inclusive of the biotic factors, or living organisms, rocks, air, water, and chemicals. The elements that are moving through the biotic or

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abiotic factors may be recycled, or they may be accumulated in a place called a sink/reservoir where they are held for a long period of time. The amount of time that a chemical is held in one place is called residence. A biogeochemical cycle or inorganic-organic cycle is a circulating or repeatable pathway by which either a chemical element or a molecule moves through both biotic and abiotic compartments of an ecosystem. In effect, an element is chemically recycled, although in some cycles there may be places (called “sinks”) where the element accumulates and is held for a long period of time. biogeochemical cycle or substance turnover or cycling of substances is a pathway by which a chemical element or molecule moves through both biotic (biosphere) and abiotic (lithosphere, atmosphere, and hydrosphere) compartments of earth. A cycle is a series of change which comes back to the starting point and which can be repeated. TYPES OF BIOGEOCHEMICAL CYCLES Biogeochemical cycles are basically of two types: (a) Gaseous cycles like carbon (as carbon dioxide), oxygen, nitrogen etc. (b) Sedimentary cycles like sulphur, phosphorus etc. In gaseous cycles, the elements have a main reservoir in the gaseous phase, and the reservoir pool is the atmosphere or water. The biogenetic materials involved in circulation pass through a gaseous phase before completing the cycle. CARBON CYCLE The carbon cycle is one of the major biogeochemical cycles describing the flow of essential elements from the environent to living organisms and back to the environment again. This process is required for the building of all organic compounds and involves the participation of many of the earth’s key forces. The carbon cycle has affected the earth throughout its history; it has contributed to major climatic changes, and it has helped facilitate the evolution of life. The complexities of the carbon cycle are depicted in Fig. 2.23. The carbon cycle is one of the earth’s fastest recycling processes-each atom of carbon has been recycled numerous times. For this reason, the carbon cycle has no specific beginning or ending point.

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Environmental Chemistry

Fig. 2.23 The Complexities of Carbon Cycle

The carbon cycle passes through three main stages: reservoirs, assimilation and release. Much of the earth’s carbon is contained in the atmosphere which serves as a reservoir, and that is where we will begin our explanation. Atmospheric carbon consists mostly of carbon dioxide and has two major sinks: terrestrial ecosystems and marine ecosystems, both of which deal with photosynthesis as a part of assimilation and respiration as a part of release (Fig. 2.24). • Carbon (C) enters the biosphere during photosynthesis: CO2 + H2O Æ C6H12O6 + O2 + H2O • Carbon is returned to the biosphere in cellular respiration: O2 + H2O + C6H12O6 Æ CO2 +H2O + energy • Amount of CO2 during the year: Every year there is a measurable difference in the concentration of atmospheric CO2 in phase with the seasons. For example, in winter there is almost no photosynthesis therefore there is a high concentration of CO2. During the growing season there is a measurable differnece in the concentration of atmospheric CO2 over parts of each day. For example, at sunrise photosynthesis begins with the uptake of CO2, by afternoon plant respiration increases, at

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sunset photosynthesis stops so the concentration of CO2 in the atmosphere increases. • Human induced changes in the global carbon cycle: The Earth is getting warmer. The 20th century has been the warmest in the last 600 years. This century is about 1°F (degree Fahrenheit) warmer than last century. The balance of evidence suggests that burning of fossil fuel (e.g. coal, oil, natural gas), which emits CO2 as a waste, is the cause. CO2 is a “Greenhouse” gas - it traps heat at the Earth’s surface. (H2O vapor and methane are also examples of greenhouse gases). • Signs that the climate is warming: Plants start blooming 8 days earlier in spring than 11 years ago. Birds from the United Kingom lay eggs earlier. Buds on trees appear earlier and leaves fall later in the Northern Hemisphere. Alaska, North West Canada, and Siberia have warmed up as much as 5°F (degrees Fahrenheit) in the last 30 years.

Fig. 2.24 Carbon Cycle

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Environmental Chemistry

Fig. 2.25 Oxygen Cycle

Oxygen Cycle Oxygen (O) atoms cycle through the ecosystem and the biosphere the way other elements do (especially carbon). The Earth has a fixed supply of the element even though it can be found everywhere, including the atmosphere, the oceans, rocks, and all living organisms. While not all organisms need to breathe oxygen, there is definitely oxygen inside of every organism (Fig. 2.25). Early in the evolution of the Earth, oxygen is believed to have been released from water vapor by UV radiation and accumulated in the atmosphere as the hydrogen escaped into the earth’s gravity. Later, photosynthesis became a source of oxygen. Oxygen is also released as organic carbon in CHO, and gets buried in sediments. Oxygen is one of the major compounds found in the atmosphere of the Earth. You never find oxygen floating around as individual atoms. Oxygen is always with other elements. You may find an oxygen molecule that has two oxygen atoms. There are molecules with three oxygen atoms called ozone. You will also find oxygen bound in water molecules and carbon dioxide. That oxygen floats through the atmosphere until it comes down to Earth and starts one of many cycles. There is a large amount of oxygen dissolved in the water of oceans, lakes and streams. As water moves, the oxygen is forced into solution. The organisms that live in the water breathe that oxygen by filtering

Ecosystem Photosynthesis CO2 + H2O O2

H2O

Respiration Sugars + O2

O2 + Sugars CO2

Plants Algae Some Bacteria Energy of Sunlight

2.31

CO2

Sugar and Other Organic Molecules

H2O + CO2 O2

Most Living Organisms

H2O

Useful Chemical Bond Energy

Fig. 2.26

it out of solution the way we do with the air. Over millions of years, oxygen has also become an integral element in our rocks and land. Oxygen bonds with silicon (silicates), iron, and carbon (carbonates) to form many of the compounds in rock. Creatures like lichen are able to breakdown the rocks over thousands of years and release nutrients into the soil (Fig. 2.26). Last are the organisms of the world. They use oxygen in many forms. Their role in the cycle begins with carbon dioxide in the atmosphere. Plants take in that carbon dioxide and combine it with water to create sugars and oxygen molecules. Animals breathe that oxygen and both plants and animals use the sugars for energy. Through the process of metabolism, the sugars are broken-down into water and carbon dioxide. Then the cycle begins again. Fact Sources of Oxygen: (1) Photodissociation of H2O vapor (2) Photosynthesis Since oxygen is so reactive its cycling is complex: (1) As a constituent of CO2 it circulates freely throughout the biosphere. (2) Some CO2 combines with Ca to form carbonates. (3) O2 combines with nitrogen compounds to nitrates. (4) O2 combines with iron compounds to form ferric oxides. (5) Photosynthesis and respiration (6) O2 in the troposphere is reduced to O3 (ozone). Ground level O3 is a pollutant which damages lungs.

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Environmental Chemistry

Fig. 2.27 Nitrogen Cycle

Nitrogen Cycle The nitrogen cycle (Fig. 2.27) represents one of the most important nutrient cycles found in terrestrial ecosystems. Nitrogen is used by living organisms to produce a number of complex organic molecules like amino acids, proteins and nucleic acids. The store of nitrogen found in the atmosphere, where it exists as a gas (mainly N2), plays an important role for life. This store is about one million times larger than the total nitrogen contained in living organisms. Other major stores of nitrogen include organic matter in soil and the oceans. Despite its abundance in the atmosphere, nitrogen is often the most limiting nutrient for plant growth. This problem occurs because most plants can only take up nitrogen in two solid forms: ammonium ion (NH4+) and the ion nitrate (NO3–). Most plants obtain the nitrogen they need as inorganic nitrate from the soil solution. Ammonium is used less by plants for uptake because in large concentrations it is extremely toxic. Animals receive the required nitrogen they need for

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Fig. 2.28 Nitrogen Fixation Method

metabolism, growth, and reproduction by the consumption of living or dead organic matter containing molecules composed partially of nitrogen (Fig. 2.28). Some Facts: • Nitrogen (N) is an essential constituent of protein, DNA, RNA and chlorophyll. • Nitrogen is the most abundant gas in the atmosphere, but it must be fixed or converted into a usable form.

Nitrogen Fixation Methods (1) High energy fixation: A small amount of atmospheric nitrogen is fixed by lightening. The high energy combines N and H2O resulting in ammonia (NH3) and nitrates (NO3). These form are carried to Earth in Precipation. (2) Biological fixation: Achieves 90% of the nitrogen fixation. Atmospheric nitrogen (N2) is split and combined with hydrogen (H) atoms to form ammonia (NH3).

Who Performs Nitrogen Fixation? • Symbiotic bacteria (e.g. Rhizobium spp.) living in association with leguminous (plants in the pea family), and root-noduled nonleguminous plants (e.g. Alnus spp.).

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Environmental Chemistry

• Free-living anaerobic bacteria. • Blue-green algae (cyanobacteria). Once NH3 is in the soil it combines with H+ ions to form ammonium lon (NH4), or without it to form NO3. NH4+ and NO3 are readily absorbed by plants.

Water Cycle Within the water cycle, energy is supplied by the sun, which drives evaporation whether it is from the ocean surfaces or from treetops and leaves. The sun, with the help of wind, also supplies the energy, which drives the weather systems, which moves the water vapors, in the form of clouds, from one place to another, or else it would only rain over oceans (Fig. 2.29).

Fig. 2.29

The Hydrologic Cycle, showing the Transfer of the Water from the Oceans to the Atmosphere to the Continents and Back to the Oceans again

Precipitation occurs when water condenses from a gaseous state in the atmosphere and then falls to earth. Evaporation is the reverse process where liquid water becomes gaseous. Once water condenses, gravity takes over and the water is pulled to the ground. Gravity continues to operate, either pulling the water underground or groundwater across the surface (also called run-off), either way gravity goes on to pull water lower and lower until it reaches the oceans.

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Frozen water (ice) may be trapped at the cooler regions of the Earth such as the poles, glaciers and on mountain as snow or ice, and may remain as such for very long periods. Lakes, ponds and wetlands form where water is temporarily trapped and stored. The oceans are salty because any erosion of minerals that occurs as the water runs to the ocean will add to the mineral content of the ocean water. Water cannot leave the oceans except by evaporation, and evaporation leaves the minerals behind. Thus, rainfall and snowfall are comprised of relatively clean water, with the exception of pollutants that are picked-up, as the waste falls through the atmosphere, an example of this would be acid rain. Organisms play an important role in the water cycle (Fig. 2.30). As you know, most organisms contain a significant amount of water, which is about 90% of their body weight. The water is not contained for a long time and moves out of the organism quickly in most of the cases. Animals and plants lose water through evaporation from the body surfaces and through evaporation from the lungs or other type’s gas exchange mechanisms.

Fig. 2.30

Water Cycle

In plants, water is drawn in at the roots and moves to the gas exchange organs, the leaves, where it evaporates quickly. This special case is 0 called transpiration because it is responsible for so much of the water that enters the atmosphere. In both the plants and

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Environmental Chemistry

animals, the breakdown of carbohydrates (sugars) to produce energy (respiration) and also produces both carbon dioxide and water as waste products. Photosynthesis reverses this reaction, water and carbon dioxide are combined to form carbohydrates. Now, we understand the relevance of the term carbohydrate; it refers to the combination of carbon and water in the sugars, known as carbohydrate. In sedimentary cycles, the elements main reservoir pool is lithosphere and the biogenetic materials involved in circulation are non-gaseous. The sedimentary cycles are usually very slow as the elements may get locked-up in rocks and go out of circulation for long periods.

Phosphorus Cycle Phosphorus moves between plants, animals, bacteria, rock, soil and water. This is also called a biogeochemical cycle (Fig. 2.31). Three natural processes contribute to this cycling of phosphorus - food webs, decomposition and the rock cycle. During the long-term cycling of phosphorus in the Earth’s crust, phosphorus leaches out of soil and weathers out of rock. This inorganic phosphorus flows downstream and eventually accumulates at the bottom of rivers, lakes and oceans. If left undisturbed for millions of years, bottom sediments transform into phosphorus-containing rock.

Fig. 2.31 Phosphorus Cycle

“Stored” phosphorus may return again to the surface during the uplifting of mountains, during the mining of potash or when bottom sediments are disturbed.

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The phosphorus cycle (Fig. 2.32) starts again as water erodes the uplifted phosphorus rock.

Fig. 2.32 Phosphorus Cycle

Some • • • • • • • •

Facts: Component of DNA, RNA, ATP, proteins and enzymes Cycles in a sedimentary cylce A good example of how a mineral element becomes part of an organism. The source of Phosphorus (P) is rock. It is released into the cylce through erosion or mining. It is soluble in H2O as phosphate (PO4) It is taken up by plant roots, then travels through food chains. It is returned to sediment.

Sulphur Cycle Sulphur is one of the components that make-up proteins and vitamins. Proteins consist of amino acids that contain sulphur atoms. Sulphur is important for the functioning of proteins and enzymes in plants, and in animals that depend upon plants for sulphur. Plants absorb sulphur when it is dissolved in water. Animals consume these plants, so that they take up enough sulphur to maintain their health. Most of the earth’s sulphur is tied up in rocks and salts or buried deep in the ocean in oceanic sediments. Sulphur can also be found in the atmosphere. It enters the atmosphere through both natural and human sources. Natural recourses can be for instance volcanic eruptions, bacterial processes, evaporation from water, or decaying organisms.

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Environmental Chemistry

Fig. 2.33 Sulphur Cycle

When sulphur enters the atmosphere through human activity, this is mainly a consequence of industrial processes where sulphur dioxide (SO2) and hydrogen sulphide (H2S) gases are emitted on a wide scale. When sulphur dioxide enters the atmosphere it will react with oxygen to produce sulphur trioxide gas (SO3), or with other chemicals in the atmosphere, to produce sulphur salts. Sulphur dioxide may also react with water to produce sulphuric acid (H2SO4). Sulphuric acid may also be produced from demethylsulphide, which is emitted to the atmosphere by plankton species. All these particles will settle back onto earth, or react with rain and fall back onto earth as acid deposition. The particles will than be absorbed by plants again and are released back into the atmosphere, so that the sulphur cycle will start over again. Some Facts: • Component of protein • Cycles in both a gas and sedimentary cycle • The source of sulfur is the lithosphere(earth’s crust). • Sulphur (S) enters the atmosphere as hydrogen sulfide (H2S) during fossil fuel combustion, volcanic eruprtions, gas exchange at ocean surfaces and decomposition. • H2S is immediately oxidized to sulphur dioxide (SO2) • SO2 and water vapor makes H2SO4 (a weak sulfuric acid), which is then carried to Earth in rainfall.

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Fig. 2.34 Sulphur Cycle

• Sulfur in soluble form is taken up by plant roots and incorporated into amino acids such as cysteine. It then travels through the food chain and is eventually released through decomposition. ECOLOGICAL SUCCESSION Ecological succession is the gradual process by which ecosystems change and develop over time. Nothing remains the same and habitats are constantly changing. The history of an ecosystem from birth to maturity is called ecological succession. The ecological succession is essentially an uninterrupted sequence of changes in the biotic and abiotic components of an area, which leads to a stable ecosystem (the one that is defined as the “climax”), in which components are balanced, i.e., no one prevails over the others, making then disappear. The sequence of communities that replace each other with time within the ecosystem is called “sere” and the different transition stages are called “seral stages”. It is the

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populations themselves that sometimes alter the environment in which they live and cause themselves to disappear in favour of other species of organisms. Examples of this type of evolutionary process can be easily found in nature, where the formation of any new environment (due to a fire in a wood, to the detour of a river, a deserted farmland, etc.) initially causes the so-called “pioneer” organisms to spread, i.e., organisms that can grow despite the harsh conditions of the area (few nutrients). The living activity of these first organisms alters the environment, creating new conditions that are favourable to other, more demanding, organisms. The latter develop, often causing the pioneer organisms to disappear. Succession may be initiated either by formation of new, unoccupied habitat (e.g. a lava flow or a severe landslide) or by some form of disturbance (e.g. fire, severe windthrow, logging) of an existing community. The former case is often referred to as primary succession, the latter as secondary succession. The trajectory of ecological change can be influenced by site conditions, by the interactions of the species present, and by more stochastic factors such as availability of colonists or seeds, or weather conditions at the time of disturbance. Some of these factors contribute to predictability of successional dynamics; others add more probabilistic elements.

Primary and Secondary Succession When succession starts from a bare habitat e.g., bare rock it is called a primary succession. When disturbance has not resulted in the loss of soil or even all species a secondary succession will take place. On a disturbed urban site e.g., waste land where buildings have been removed, it may well be possible for both primary and secondary succession to be observed.

The Stages of Succession In a succession the following stages can be recognised: 1. A pioneer community forms The first colonisers are likely to be certain species of algae, lichens and mosses. These are producers, making their own food through the process of photosynthesis. They are also able to survive without soil, taking up rainwater and mineral salts through the whole of their body surface.

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Pioneer species have to be hardy individuals likely to be able to put up with extreme conditions e.g., large humidity ranges. Twisted moss (Syntrichia ruralis) is a moss which often forms part of the pioneer community on walls, roof tiles and stony and sandy ground. It shows the following characteristics. • Thread-like structures (rhizoids) anchor the shoots onto the surface of the habitat. • Water and mineral salts can be absorbed over the whole body surface as there is no waxy cuticle. • The moss has a cushion or turf growth form which helps to hold water between the shoots. • The shoots twist as they dry out slowing down water loss. • The moss is also able to tolerate severe drying but recovers immediately in the first shower of rain. 2. Changes occur in the habitat The pioneer species begin to have an impact on the site. • Food is present for consumers and decomposers which now arrive. • Soil begins to form as the dead remains of plants and animals accumulate and are broken-down by the decomposers. • Water is held in the habitat both in the living organisms themselves and in the soil. 3. Vascular plants (ferns, their allies and seed plants) colonise These plants have a waxy covering (the cuticle) which protects them from water loss. They have to get most of their water and mineral salts from the soil. These are transported through the plant body by the vascular system. Once soil has formed these plants begin to establish themselves causing further changes to the habitat. Conditions become unsuitable for the pioneers, which disappear as a result. 4. Shrubs and trees arrive The larger woody plants such as shrubs and trees need more soil than the smaller non-woody plants and are also much slower growing, so they usually appear in the later stages of the succession.

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5. A climax community forms If left for long enough a more or less stable community can develop. This is known as the climax community. A good example is undisturbed tropical rain forest. Unfortunately all over the world humans are gradually destroying these communities, because they take a very long time to develop (often hundreds of years), such communities are becoming increasingly scarce. Two other features are characteristic of succession - the quantity (biomass) and variety (biodiversity) of living organisms increases as the succession proceeds. Few species can tolerate the environmental conditions at the pioneer stage but as succession continues ecological conditions become less extreme and more habitats develop so a greater variety and number of organisms are able to colonise. When shrubs and trees begin to arrive the increase in biomass become especially noticeable. The highest biodiversity is not always at the climax community stage. For example, in the dense yew woodland, which forms a climax community on parts of the North Downs, toxic chemicals in the leaves and low light intensity means that the number of species in this sort of woodland is relatively low. In general, communities in early succession will be dominated by fast-growing, well-dispersed species (opportunist, fugitive, or r-selected life histories). As succession proceeds, these species will tend to be replaced by more competitive species. Ecological succession provides diversity and depth to a biotic community. Without it, life cannot grow or progress. Succession, it seems, is the gateway to evolution. There are five main elements to ecological succession: primary succession, secondary succession, pioneer and niche species, climax communities and sub-climax communities.

Primary and Secondary Production in an Ecosystem Primary production in an ecosystem is the amount of light energy converted to chemical energy by autotrophs during a given time period. • The extent of photosynthetic production sets the spending limit for an ecosystem’s energy budget.

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• The amount of solar radiation reaching the Earth’s surface, however, limits photosynthetic output of ecosystems. • The amount of usable solar energy hitting Earth’s surface is even further limited by the fact that: ƒ Only a small fraction of it actually strikes photosynthetic organisms. ƒ Of the radiation that does reach photosynthetic organisms, only certain wavelengths are absorbed. Gross and net primary production • Total primary production is known as the ecosystem’s gross primary production(GPP) (Fig. 2.35). • GPP is therefore the amount of light energy that is converted to chemical energy by photosynthesis per unit time. • Not all of this production stored as organic material in primary producers because they use some as fuel in their own cellular respiration. • Net primary production (NPP) is GPP minus energy used by primary producers for respiration. • Only NPP is available to consumers. • NPP can be expressed as. • Energy per unit time (J/m2 yr) or as. • Biomass (mass of vegetation) added to an ecosystem per unit area per unit time (g/m2 yr). • This should not be confused with the Total biomass of photosynthetic autotrophs present at a given time, which is a measure called the standing crop. • It is the amount of New biomass added in a given period of time Ecosystems vary greatly in NPP and contribution to the total NPP on Earth. • In many ecosystems, NPP is ~ 1/2 of GPP. • Tropical rain forests are among the most productive terrestrial ecosystems. • These biomes contribute a large portion of the planet’s overall NPP. • Estuaries and coral reefs also have very high NPP.

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Fig. 2.35

• Because they cover only ~ 1/10 of the area of tropical rain forests, however, their contribution to the global total is relatively small. • Oceans are relatively unproductive per unit area compared to tropical forests and some other ecosystems. • Because of their vast size, however, the contribute as much to the global NPP as do terrestrial ecosystem.

Secondary Production Secondary production represents the formation of living mass of a heterotrophic population or group of populations over some period of time. It is the heterotrophic equivalent of net primary production by autotrophs. Taken to its extreme, secondary production can represent the formation of mass for an entire trophic level. Animal production, the subject of this article, is almost always measured at the population level regardless of whether one is considering a single population, a group of populations, or an entire trophic

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level. If one seeks to measure production of an entire trophic level, production of all populations within that level, or at least the major ones, must be summed. In contrast, production of non-animal heterotrophs typically is estimated for all populations simultaneously such as from incorporation of radiolabelled leucine (for bacteria). Secondary production historically has been viewed in the context of energy flow through trophic levels. Early energy flow studies used energetic measures (Kilocalories or Kilojoules). Most estimates of production today, however, whether for primary producers (autotrophs) or secondary producers (heterotrophs), are expressed as mass (grams carbon or grams dry mass). While population biomass units are often presented as grams/m2 , the typical unit for secondary production incorporates time (e.g. grams m–2 year–1, grams m–2 week–1). We tend to think of biomass as a structural (or static) variable and production as a functional variable because the latter measures an ecological process through time. It has long been recognised that not all food eaten by an individual is converted into new animal mass. Consider a stream snail grazing on algae. Only a fraction of the material ingested (I) is assimilated (A) from the digestive tract; the remainder passes out as feces (F). Of the material assimilated, only a fraction contributes to growth of an individual’s mass or to reproduction — both of which ultimately represent production (P). Most of the rest is used for respiration (R). A small portion of energy is lost in excretion, but is usually ignored in such energy budgets. Simple equations are used to illustrate the fate of ingested energy, such as I = R + P + F. Alternatively, production is P = I – F – R.

Regulation of Ecosystem Ecosystems are controlled by a multitude of factors, each influencing the other. Almost all living organisms rely on the energy from the sun. Organisms at the base of the food chain, such as phytoplankton and plants, use the sun’s energy directly. Organisms higher on the food chain receive energy from the sun indirectly. The only organisms on the planet capable of producing energy without the sun are microorganisms called chemoautotrophs that often live near deep sea vents and synthesise energy through a chemical process. Within an ecosystem there are trophic levels based on feeding relationships including producers, primary consumers, secondary consumers, tertiary

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consumers and decomposers. Many organisms consume both plants and animals (omnivores) and prey on a variety of species to avoid starvation in case their primary prey becomes scarce; therefore they are sometimes categorised into more than one trophic level depending on the circumstances. Abiotic factors like temperature, light, nutrients, and salinity play a large part in the control of growth, location and abundance of marine populations. Lastly, species within a population are also regulated by competition, predation, parasitism and disease. Every part of the complex web of biotic and abiotic factors fits together to make a system that is balanced and capable of withstanding most changes. FOREST ECOSYSTEM A forest ecosystem is a terrestrial unit of living organisms (plants, animals and microorganisms), all interacting among themselves and with the environment (soil, climate, water and light) in which they live. The environmental “common denominator” of that forest ecological community is a tree, who most faithfully obeys the ecological cycles of energy, water, carbon and nutrients. Forest ecosystems are dominated by trees that can mature to at least 2 metres in height and provide a canopy of at least 20% cover, together with all the native wildlife, including birds, mammals, marsupials, amphibians, reptiles, insects, plants, as well as moss, fungi, microorganisms and non-living things such as water, soil and air interacting within the same area. A forest ecosystem has definite boundaries and includes a forest of trees out to the limit of tree growth. Remember that forests are not the only ecosystems. There are hundreds of thousands of defined and undefined ecosystems that can cover the broadest to the tiniest of areas. An ecosystem can be as small as a pond or a dead tree, or as large as the Earth itself. Actually a forest ecosystem is a natural woodland unit consisting of all plants, animals and microorganisms (Biotic components) in that area functioning together with all of the non-living physical (abiotic) factors of the environment.

Characteristic Features of Forest Ecosystem Forest canopy • The forest canopy is an important feature of a forest ecosystem. It pertains to the top portion of a community of trees or plant

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crowns. A forest canopy serves as the interface between the atmosphere and the land. The canopy is also the upper habitat for other biological organisms in a forest ecosystem. It is mostly composed of large trees. The structure of forest canopy is not the same in every forest ecosystem because it depends on the availability of nutrients, tree arrangement and differences in biological species. More than half of the plant species are found in a forest ecosystem, so the biodiversity is greatest in the forest canopy. Most organisms are able to survive in forest canopy because it is directly exposed to sunlight and rainwater. Forest floor • The forest floor is the most distinct feature of a forest ecosystem. It is composed of fallen leaves, stems, twigs, branches and bark on the surface of the soil. A forest floor also contains organic and inorganic substances. Many living organisms, such as the fungi, bacteria and other microorganisms, inhabit the forest floor. It is rich in nutrients and mineral contents. The forest floor has a significant role in the transfer of nutrients in the life cycle of the forest ecosystem. Most of the carbon and energy from the forest ecosystem is added to the forest floor over time. The majority of nutrients of the forest ecosystem comes from the forest floor due to the decomposition of organic substances. Forest soil • The soil is a feature of a forest ecosystem that is affected by the changes in climate, geology, amount of rainfall and vegetation. The soil of temperate forests is more fertile because trees’ leaves drop to the ground every fall. This litter contributes to the layers of organic material found in forest soil. The old leaves become a source of food for bacteria and fungi. These organisms facilitate the breaking-down of the leaves and other organic material. Decomposition enriches the forest soil as it provides more nutrients to the living trees and plants in the forest ecosystem. However, the soil in tropical rain forests has poor quality because of the torrential rains. The constant rain erodes and dissolves soil nutrients before the trees can benefit from them.

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Functions of Forest Ecosystem Regulatory functions This group of functions relates to the capacity of forest ecosystems to regulate essential ecological processes and life support systems through biogeochemical cycles and other biospheric processes. In addition to maintaining the ecosystem (and biosphere health), these regulatory functions provide many services that have direct and indirect benefits to humans (i.e. clean air, water and soil, and biological control services). Habitat functions Forest ecosystems provide refuge and a reproduction habitat to wild plants and animals and thereby contribute to the (in situ) conservation of biological and genetic diversity and the evolutionary process Production functions Photosynthesis and nutrient uptake by autotrophs converts energy, carbon dioxide, water and nutrients into a wide variety of carbohydrate structures which are then used by secondary producers to create an even larger variety of living biomass. This broad diversity in carbohydrate structures provides forest ecosystem goods for human consumption, ranging from food and raw materials to energy resources and genetic material. Information functions Since most of human evolut ion took place within the context of an undomesticated habitat, forest ecosystems provide an essential ‘reference function’ and contribute to the maintenance of human health by providing opportunities for reflection, spi r it u a l en r ich ment , cognitive development, recreation and aesthetic experience.

Fig. 2.36 Tropical Rain Forest

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Types of Forest Ecosystem Tropical rain forest Days usually last 12 hours, temperatures averaging around 77° F, surplus of rain and high insolation (sunlight) are all attributes of a tropical rain forest year-round. Tropical rain forests cover the Amazon region, as well as equatorial regions in Africa, South-east Asia, the east coast of Central America and elsewhere along the equator. These areas are characterised by broadleaf evergreen trees, vines, tree ferns and palms. Tropical seasonal forest Located on the edges of rain forests are the tropical seasonal forests that receive dwindling and irregular rainfall. These areas are characterised by broadleaf evergreen trees, some deciduous trees and thorn trees. Deciduous trees lose Fig. 2.37 Tropical Seasonal Forest their leaves during the winter. Temperate evergreen and deciduous forest Found in North America, Europe and Asia, temperate evergreen and deciduous forests tend to blend together at times. Needle leaf and broadleaf trees inhabit the forests. In southern and eastern areas that are fervent with evergreen pines, controlled forest fires still take place as the natural cycle of forest re-growth and enrichment. As far as weather conditions, it is a moderate climate with a cold season.

Fig. 2.38 Temperate Evergreen and Deciduous Forest

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Boreal forest The boreal forest, also known as the needle leaf forest, covers most of the subarctic climate areas located in Canada, Alaska, Siberia, Russia and Europe. “Taiga” is a broader term used for boreal forest in order to encompass areas transitioning to arctic climate conditions. While there aren’t any boreal forests in the Southern Hemisphere, there are mountain forests comprised of needle leaf trees that survive all over the world at extremely high elevations.

Fig. 2.39 Boreal Forest

Grassland ecosystem The important plants of grassland are obviously grasses, with small low shrubs and some special trees. Trees are more frequently found near streams and rivers, in grasslands. There are numerous wildflowers that grow up in grasslands. Grasslands are defined as lands prevailed by grasses instead than big trees and shrubs. Early forests turned down and grasslands became distributed. “Grassland” is the term for biomes known in South America as pampas, in North America as prairies, in Asia as steppes and in Africa as savannas (tropical) or veldts. It’s an ecosystem dominated by grasses, often without quite enough water to sustain thickets of trees, and it may cover as much as a quarter of the Earth’s surface. Grassland ecosystems are influenced over time by the organisms and plants that live there, the local climate, the natural landscape and natural disturbances to the environment such as fires or floods. Various species such as buffalo, elephants, badgers, armadillos and many

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insects have adapted to and are located in grassland environments throughout the world. Physical features of grasslands such as wide open grass-covered plains or scattered trees located next to scarce streams help to create a diverse environment within the grassland ecosystem. Grassland biomes are unchanged areas of land where grass is the dominating plant life, as conflicted to some other terrestrial biomes where big trees invade most of the surface of the land. Grassland is found out around the world and has helped as grazing areas for a huge number of animals. Grassland biomes are constituted of large, rolling tracts of land consisting of grasses, flowers, shrubs and herbs. The yearly rainfall they encounter is between 15-35 inches. Grasslands are characterised as lands dominated by grasses rather than large shrubs and trees. Grasslands are dominated by perennial species, whereas in warmer climates annual species form a greater component of the vegetation. Grassland occur naturally on all continents except Antarctica. CHARACTERISTICS OF GRASSLAND ECOSYSTEM

Grassland Climate The climate of grasslands is a little wetter than the climate of deserts. The area between deserts and grasslands where increased rainfall enables some grasses to grow is called the desert-grassland boundary. Because rainfall is an abiotic factor affecting both deserts and grasslands, long-term changes in climate patterns can change the desert-grassland boundary. If rainfall increases, the desert can become grassland. If the climate becomes too dry in a grassland, the biome cannot support the organisms that usually live there and it will become a desert. Grasses can survive temperatures from – 25 to 70 degrees Celsius. Having hot, dry summers, making rainfall a grassland’s most significant limiting factor. However, scientists have determined that natural grass fires, ignited by lightning, also play an important role in the development of grasslands.

Grassland Organisms The occasional fires common in grasslands keep the number of trees and shrubs there low. When Grass fires, destroys trees and saplings because most of their mass is above the ground and therefore vulnerable to

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fire. But grasses have most of their mass below ground, which helps them survive in periods of rainfall. Fires thereby remove species that compete with grasses for resources. Another benefit of fires is that they burn away the layer of dead grass that accumulates during the year, converting it to valuable nutrients. The nutrients act as fertilizer, giving grasslands a deep fertile soil held in place by grass roots. Heat from fires also aids the germination of many grass seeds. Grasses are abundant in grassland areas because of biotic factors as well as abiotic factors. Grazing animals, such as bison and burrowing animals help maintain grasslands with their activities above and below the ground. Grazing animals act as natural lawn mowers, keeping the vegetation close to the ground. When kept this low, tree saplings and shrubs become too damaged to grow well. Animals such as earthworms, prairie dogs, and insects, which aerate the soil by making tunnels and digging, also live below ground. When the soil is aerated, grasses can grow more successfully because nutrients, oxygen, and water can reach their roots more quickly. The amount of rain and when it rains affects the sizes and textures of the grasses. Most tall-grass prairies, where the fertile soils can support grass 2 m tall, have been cleared for crops such as corn and wheat. Short-grass prairies are now used for cattle grazing and irrigated crops. Some grasslands experience cycles of heavy rain followed by long periods of little or no rain, called rainy season and drought seasons. Many plants and trees have adaptations that make them drought resistant. All grasslands contain large grazing animals such as antelope and bison. Their ability to run quickly across the prairie is an adaptation that helps them avoid predators. Some animals such as mice, gophers, and prairie dogs burrow underground and are only active at night, to avoid predators and intense daytime heat. In the North American prairies, coyotes, foxes, snakes, and birds of prey are the top consumers. Tropical grasslands ecosystem Tropical Grasslands are found in Central Africa, Australia, Brazil and India, with an average rainfall from 51 to 127 cm annually. Tropical grasslands are also known as savanna or veldt, are found close to the equator and are hot all year round, with distinctive dry

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and wet seasons. Rain is generally concentrated in 6-8 months and the remaining months have drought conditions. Animal adaptations Savanna mammals tend to reproduce during the hospitable wet season when food is plentiful, affording sufficient nutrition for mothers to nurse their young. If the rains do not arrive on time, it is not uncommon for antelope calves to die. The rainy season provides an abundance of food for the birds, insects, large and small mammals but the remaining dry season brings with it a competition for survival. Water becomes very scarce. Many birds and large mammals migrate to find water, sometimes needing only to move a few miles away because of the variation in rainfall in different nearby areas. Many burrowing animals go into a state of dormancy during this period. Giraffes are an example of an animal who drinks water when it is available, but who is capable of surviving for weeks without any water, drinking morning dew and deriving water from their food. Because of the giraffe’s long neck, it is capable of reaching leaves that are too high for other mammals, and is it also able to see any potential predators from a distance. The African hedgehog can manipulate its backbone in order to curl up into a ball when faced with a predator so that only its spiny armour is exposed. Coupled with this adaptation, the animal has acute auditory (hearing) and olfactory (smelling) senses. Elephants utilise their long trunks to pull off tender leaves above their heads, and move them to their mouths to chew. The Australian wallaroo has furry pads that allow it to climb on rocks and to dig for underground sources of water. Plant adaptations In order to prevent the areas from becoming rainforests, most tropical grasslands are maintained by frequent fires (both natural and manmade) during the dry season, beginning in October. Fires provide opportunistic meals for birds and other animals, who feed off the insects, mice and lizards killed by the fire. The fires produce a fine ash providing nutrients for the new growth of grass. Different plants have adapted to grow in specific savanna areas, depending on how much rainfall occurs.

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Grasses in these areas have very deep roots that remain unharmed during fires, rapidly sending up new shoots once the rains return. Shrubs survive on the subterranean food reserves in their roots until the rainy season. Some trees survive the fires because of their fireresistant bark.

Fig. 2.40 Plant Adaptations

In the protected parks of Africa, elephants can be responsible for creating savannas by destroying trees, thereby paving the way for fires to maintain the grasses that sprout up. Large mammals also contribute to the low density of trees by eating the seedlings. Acacia trees are capable of emitting a foul-tasting poisonous alkaloid, in order to discourage giraffes from eating its leaves. These trees have the amazing ability to communicate danger to their neighbouring acacia trees, which respond by emitting this same chemical into their own leaves. Overgrazing and plowing over of grasslands lead to erosion of the soil during droughts. The loose soil left behind is picked up by strong winds, causing dust storms for miles and the loss of fertility in the earth. Temperate grassland ecosystem Temperate grasslands (Fig. 2.41) are also known as prairie, puszta, pampas, plains or steppes with warm, moist summers (average 18ºC) and cool, dry winters (average 10ºC). It can snow during the winter. The most prominent temperate grasslands are found in the Great

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Plains of Canada and the United States, Argentina, South Africa, Central Eurasia and Australia. There are two distinctive types of temperate grasslands – tallgrass (more than 2 meters) and short-grass less than 60 cm). Trees are generally not found in these regions due to the lack of moisture and their need for a relatively longer life cycle. Grasses such as purple needlegrass, blue grama, buffalo grass and galleta grow in the temperate grasslands.

Fig. 2.41 Temperate Grassland Ecosystem

Much of the temperate grasslands in North America have been converted into farmland and the once teeming herds of bison and pronghorn antelope have dwindled almost to extinction, except in regions where the prairie grasses have been retained. For example, in Southern Saskatchewan province it is still possible to see wild pronghorn, and buffalo have been reintroduced into Grasslands National Park, the newest Canadian park located near Val Marie. Steppes can be found in both Europe and North America where there are hot summers and cold winters, with an average rainfall of 25 – 50 cm. All too frequently the local peoples grow crops such as wheat and allow their livestock to graze, thus destroying the natural grasses. Animal adaptations The most predominant species found in the temperate grasslands are large grass-eating (herbivorous) ungulates (hoofed mammals), who are able to take full advantage of the various grasses found there and who have a specially adaptive digestive system to process the grasses.

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Because of the relatively short height of plants, they are able to see a predator from a distance and have adapted to be able to run swiftly away from danger. Examples of animals that can be found in temperate grasslands of North America include bison, pronghorn antelope, rodents, badgers, coyotes, blackbirds, grouses, quails, hawks, owls, snakes, grasshoppers, leafhoppers and spiders. The Russian steppes are home to tarpan (wild horse), saiga antelope, polecats and mole rats, amongst others. The latter animal lives underground in burrows and is adapted to this lifestyle by virtue of their short limbs, small eyes, tiny external ears and large incisors used for digging. Many grassland mammals have front legs and paws adapted to dig burrows where they can be safe from predators. Many prairie animals have coats that blend in with the surrounding vegetation, so that they are camouflaged from predators. In the colder climates of Eurasia, the snow leopard has a coat of creamy white behind dark rosettes which helps to camouflage them in the snow and rocks. Aardvarks eat only insects, utilising their large claws to dig into anthills and termite mounds, and then utilising their long, sticky tongues to lap up the insects. Prairie dogs mostly eat grasses, seeds, leaves, flowers and fruit (herbivorous), but also eggs and insects. Animals such as red-tailed hawks, owls, skunks, coyotes and opossums are carnivores (meat-eaters) and feast on small mammals. Badgers are an example of an animal that eats both animals and plants (omnivores), choosing from a variety of rodents, frogs, snakes, insects, fruits and roots. As the weather turns cold, animals such as the thirteen-lined ground squirrel digs a deep nest below the frost line, plug the entrance with soil to keep themselves warm. In addition, these squirrels also build two other kinds of burrows – one for hiding for short periods of time and another to nest in during the warmer weather. Plant adaptations The soil of the grasslands is generally deep and fertile, with roots penetrating way below ground where moisture is retained during droughts.

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Perennial grasses bud below ground or just at the surface, making them resistant to drought, fire and cold. The stem is narrow and upright, reducing the affects of heat in the summer. As with the tropical grasslands, the temperate grasslands also rely on seasonal drought, fire and grazing to prevent shrubs and trees from becoming established. Many beautiful wildflowers such as asters, coneflowers, goldenrods, sunflowers, clover, etc., thrive in these regions, as well as certain trees such as willow, oak and cottonwood near the rivers. Insects are attracted to the colourful blossoms of the wildflowers; as the insect feeds, the pollen brushes off on the insect who then carries it to another plant and in the process fertilizes that plant. The stinging nettle plant has a beautiful plant but contains a painful sting to protect itself from humans and grazing animals. Overgrazing and plowing over of grasslands lead to erosion of the soil during droughts. The loose soil left behind is picked up by strong winds, causing dust storms for miles and the loss of fertility in the earth. Regulatory functions The role of grasslands in air quality regulation services rests in avoided emissions of gases rather than direct effects on air quality. Grasslands can be an important source of CH4 and N2O which are associated with livestock and grassland management. Climate change regulation service is usually approached by an amount of carbon sequestered in an ecosystem. Carbon stored in ecosystems is an important indicator of regulation services potential which is directly related to land use disturbances and land management practices. There is growing evidence that temperate grasslands can sequester relatively large amounts of carbon. Carbon sequestered in temperate grasslands is related to net primary production (NPP) as a rate of C supply into soil. On the other hand, carbon is emitted from grassland by heterotrophic respiration, fires, and also changes in soil C pools induced by soil erosion or water drainage. Ecosystem service of water regulation can be defined as influence ecosystems have on the timing and magnitude of water run-off, flooding, and aquifer recharge, particularly in terms of the water storage potential of the ecosystem. Habitat functions Semi-natural grasslands cover probably the most diverse habitats and therefore are extensive repositories of biodiversity and genetic

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materials. Semi-natural grasslands contain exceptional diversity of plants, insects (e.g. butterflies), birds or fungi. Plant populations in semi-natural grasslands exhibit a strong pattern of genetic differentiation and erosion. Genetic diversity is generally negatively related to fragmentation of grasslands and current human population density. Production functions Grasslands are an important source of food resources, namely meat, milk or honey. There is some evidence that livestock performance can be improved by presence of semi-natural herbs and legumes. Although pasture on managed grasslands provides usually forage of better quality, effects on milk and meat of forage from semi-natural grasslands have been documented. Grasslands have effects on surface water as well as groundwater quality and recharge. The main pressures on groundwater include use of agricultural nitrogen fertilizers and pesticides. Grasslands provide forage, fibres and also increasingly recognised their potential to provide bioenergy. Concerning forage quantity, several studies have provided the evidence that species-rich grasslands achieve higher biomass and hence hay yields. Grasslands have been traditionally sources of medicinal plants and other medicinal resources. Pharmaceutical use of medicinal and aromatic plants connected with the content of active substances such as oil or tannins. Medicinal plants collected on grasslands are valuable for traditional medicines or are commercially utilised for the production of teas, oils and other medicines. Information functions Grasslands play an important roles in recreation and human aesthetics. Many outdoor activities, such as bird-watching, hunting, walking and general enjoyment of nature, are linked to open landscapes and extended views. DESERT ECOSYSTEM Deserts are formed in the driest of environment. The temperature of deserts may vary from very hot as in hot deserts, to a very cold as in cold deserts.

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A desert is a type of region or terrain on, Earth’s surface which receives very less rainfall compared to other regions. Deserts are extremely dry regions with very little water around. The most important hot deserts of the world is the Sahara-ArabiaGobi which extends from Africa to Central Asia. It has a highly irregular an insignificant rainfall and low humidity. Hot deserts also occurs in India such as Sindh-Rajasthan desert South America, North America and Australia, cold deserts occurs in Ladakh regions of Himalayas and Tibet. Desert plants which are adapted to drought conditions through reduced leaf size and the dropping of leaves in any conditions both reducing loss via evapotranspiration. The roots of most of the desert plants remain well developed and occur in the top of the soil in order to take maximum possible advantage of any rainfall. Deserts are dry, arid regions of the planet that receive very less rainfall compared to other natural regions and biomes. They constitute a major portion of our planet, and are one of the largest biomes on Earth. The animals present in the desert are reptiles, insects and rodents. All these animals have special morphological, physiological and etiological adaptations for desert. Some desert animals are newly adapted for high extremes of temperatures. In general large animals are very uncommon except male deer. Some desert plant close their petals at night while many plants blossom only at night. There are some insects which remain active during the day while some insects are active at night. Some reptiles and insects are well adapted for their survival in deserts and excrete dry matter, kangaroo, rat and pocket mouse are able to live without drinking water. They do so by extracting the moisture from the seed they eat. The camel and the desert birds (ostrich) have an occasional drink of water but can go for long periods of time using the water stored in the body. Most insects of the deserts are herbivores.

Types and Characteristics of Deserts Deserts are one of the major ecosystems in the world and constitute one fifth of the earth’s land. There are four major types of deserts: • Hot and dry deserts • Semi-arid deserts

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• Coastal deserts • Cold deserts Hot and dry desert The hot and dry deserts are present around the equator and have a warm and hot temperature through out the year. The examples of these types of deserts are: Sahara desert, Sandy Desert of Australia and Sonoran Desert. The temperature The temperature of these deserts remains hot through out the year. The temperature may get a little less hot or in some cases exceptionally cold at times, but the summers are extremely hot. There is almost no or very little rainfall in these deserts because of which there is no humidity in the air which could block the sunrays, hence the sun in these deserts is scorching hot. The nights in these deserts are cooler than the day. During the day, the temperature may reach around 48-49°C. The soil Due to no sub surface water the soil of these deserts is shallow, coarse, rocky and gravely. The soil here is coarse because there is almost no chemical weathering of rocks and the fine dust particles get carried away by the wind. Life The plants found in these deserts are highly specialised plants which have reduced leaves and thick cuticles to prevent water loss. Common plant species of these deserts are: cacti, turpentine bush, brittle bush, prickly pears, yuccas and ocotillo. The animals found here are mostly nocturnal and get out at night when the desert is cooler. There is a majority of reptiles, arachnids and insects while animals such as kangaroo rats are also found in majority. These animals tend to remain buried under the ground during the hot days. Semi-arid desert The semi-arid deserts can be called the moderate versions of hot and dry deserts.

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Common semi-arid deserts of the world are: Sagebrush desert and some deserts of North America, Greenland, Russia, Europe and Northern Asia. Temperature The summers of these deserts are pretty much like the hot and dry deserts and are long and dry, but the only difference is that the temperature does not exceed beyond 38°C. It also gets much cooler at night as compared to the hot and dry deserts. The winters here are better as low concentrations of rainfall are observed. Although rain is of low concentration, it’s enough to give slight moisture in the air. The soil The soil in these deserts varies from sandy, to coarse, to shallow and gravely. Around the mountain slopes the soil is shallow and rocky; around lower slopes it is coarse while around the bottom land it’s fine and sandy. The soil has a very low salt concentration. Life Like the hot and dry deserts, the plants here are highly specialised in conserving water. They have reduced leaved known as spines and thick cuticles. Common plants found here are: white thorn, cat claw, brittle bushes, mesquite and jujube. Animals include both nocturnal and day time animals. Non mammals are reptiles and insects while mammals include: kangaroo rats, rabbits and skunks. Some birds such as borrowing owls are also found here. Coastal desert Coastal deserts are moderate deserts where the temperature is normal throughout the year. The Atacama Desert of Chile is the most famous coastal desert. Temperature The winter in these deserts is cool while summers are warm. The average temperature during summers is 13-24°C and is around 5°C

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during the winters. The rainfall is not very abundant, but on an average 8-13 cm rain falls every year. The soil The soil in these deserts is fine textured, porous and has a moderate salt content. Life The plants here apart from having thick leaves and stems, have an extensive root system which draws maximum water whenever there is a rainfall. The stems of these plants can store a large amount of water for later use. Examples are: salt bush, buck wheat bush, rice grass, and black sage and little leaf horse bush. Animals in this desert are highly specialised in storing waters and are well adapted to the conditions of the desert. A part from reptiles such as lizards and snakes, amphibians like toads and mammals like coyote and badger are also found here. Insects and birds like golden eagle are also present. Cold desert Cold deserts are exceptional deserts where the temperature is extremely cold. The deserts of Antarctic and Green land are included in this category. Temperature The winters in these deserts are extremely cold and are very long. The summers are relatively warmer and moist with abundant rainfall. The temperature may reach up to 26°C during the summers. The soil The soil of these deserts is silty, having a high salt content and is heavy. The soil is also porous at places. Life There is a large population of plants found here. Most of the plants are deciduous, tall and have spikes instead of leaves. Animals include: kangaroo rats, pocket mice, jack rabbits, kit fox, deer and coyote. Because of extreme cold there are very few reptiles and amphibians.

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Table 2.1 Ten Largest Deserts of the World The ten largest deserts Rank Desert 1. Antarctic Desert (Antarctica) 2. Arctic Desert (Arctic) 3. Sahara Desert (Africa) 4. Arabian Desert (Middle East) 5. Gobi Desert (Asia) 6. Patagonian Desert (South America) 7. Great Victoria Desert (Australia) 8. Kalahari Desert (Africa) 9. Great Basin Desert (North America) 10. Thar Desert (India, Pakistan)

Area (km²)

Area (mi²)

14,200,000

5,500,000

13,900,000

5,400,000

9,100,000

3,500,000

2,600,000

1,000,000

1,300,000

500,000

670,000

260,000

647,000

250,000

570,000

220,000

490,000

190,000

450,000

175,000

Function of Desert Ecosystem Like all biomes, deserts function through an intricate ecosystem. All parts of the desert, from its plants to its weather, play an important role in keeping it a living and functional place. A desert ecosystem relies on an area that receives little to no precipitation and the temperature is very hot, according to Controlling Pollution.com, One small change can affect everything that lives there. Desert plants have adapted to retain moisture for long periods of time. A cactus, for example, has less stomata than other plants, which allows it to breathe without losing a lot of moisture, according to CactusJacks.net. Cacti have also adopted cylindrical shapes to help retain and store water. Many of these plants use the moisture they retain to produce fruit, but are covered with thorns and spines that prevent all but the smallest of animals from eating it. But when animals like the kangaroo rat do eat the fruit, there is a transfer of the moisture from the plant to the animal. Larger animals like coyotes and owls in the desert subsist on eating these smaller herbivores and thus also benefit from the water transfer. Deserts are full of burrowing animals. While they are escaping heat that way, they help aerate the soil of the desert with their tunnels and assist in cooling the soil climate. Many animals that live in the desert have adapted so their light fur helps keep out the powerful heat of the sun. Others like reptiles survive by regulating their body temperatures to store heat from the day to warm them during cold nights.

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AQUATIC ECOSYSTEM Aquatic ecosystems include oceans, lakes, rivers, streams, estuaries and wetlands. Within these aquatic ecosystems are living things that depend on the water for survival, such as fish plants, and microorganisms. These ecosystems are very fragile and can be easily disturbed by pollution. All living things within an ecosystem share the same watershed. A watershed is an area of land over which water flows to reach a common body of water such as a lake or pond. We all live in a watershed, or drainage basin. Watersheds can be as large as the Mississippi River drainage basin or as small as a farm with a pond. Your watershed may be made up of mountains, farms, houses, businesses, or towns. An aquatic ecosystem is a group of interacting organisms dependent on one another and their water environment for nutrients (e.g. nitrogen and phosphorus) and shelter. Familiar examples are lakes and rivers, but aquatic ecosystems also include areas such as flood plain marshes, which are flooded with water for only parts of the year. Seemingly inhospitable aquatic ecosystems can sustain life. Even a drop of water is an aquatic ecosystem, since it contains or can support living organisms. In fact, ecologists often study drops of water - taken from lakes and rivers - in the lab to understand how these larger aquatic ecosystems work. Where plants, animals and their physical environment interact in water called aquatic ecosystem.

Types and Characteristics of Aquatic Ecosystems An aquatic ecosystem is broadly classified into marine and freshwater ecosystems. Aquatic ecosystems are systems composed of living organisms and non-living elements interacting in a watery environment. In simple terms, an aquatic ecosystem is a community of plants and animals that primarily depend on water. There are two major types of aquatic ecosystems: • Marine ecosystems • Freshwater ecosystems Marine ecosystems While terrestrial ecosystems cover only about 28%, marine ecosystems cover approximately 71% of the earth’s surface. Different habitats

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ranging from coral reefs to estuaries make up this largest aquatic ecosystem in the planet. Prime examples of marine ecosystems include: • Ocean: Main body of salty water that is further divided into important oceans and smaller seas. Major oceans include the Pacific ocean, Indian ocean, Arctic ocean, Atlantic ocean and Southern ocean. • Intertidal zone: Area which remains underwater at high tide and remains terrestrial at low tide. Different types of habitats including wetlands, rocky cliffs and sandy beaches fall under intertidal zones. • Estuaries: Areas between river and ocean environments that are prone to tides and inflow of both freshwater and saline water. Due to this inflow, estuaries have high levels of nutrients. There are different names of estuaries such as inlets, lagoons, harbors etc. • Coral Reefs: Often referred as the “rainforests of the sea”, coral reefs are mounds found in marine waters as a result of accumulation of calcium carbonate deposited by marine organisms like corals and shellfish. Coral reefs form the most varied marine ecosystems in the planet, but cover less then 1% of the world’s ocean. Nevertheless, around 25% of marine animals including different types of fishes, sponges and mollusks are found in coral reefs. Common species found in marine ecosystems include: • Marine mammals such as seals, whales and manatees. • Different species of fish including mackerel, flounder, dogfish, sea bass etc. • Organisms such as the tiny planktonic, brown algae corals, echinoderms etc. Marine ecosystems are important for the well-being of both terrestrial and aquatic environments. However, they are vulnerable to environmental problems such as climate change, pollution and overfishing, which can be a serious harm to marine biodiversity. Ocean ecosystem Oceans cover approximately 70% of the earth’s surface. Major oceans of the world are Atlantic, Pacific, Indian, Arctic and Antarctic.

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1. An ocean is a huge pool of salty water that extends over almost an infinite large area. 2. Ecosystem of an ocean is very stable and naturally well balanced. 3. They have high concentration of salts. It is about 3.5%. 4. There is abundance of minerals such Na, Cl, Ca, S, Mg etc. 5. Salinity is less near the north and south poles. 6. Salinity is more in deeper regions of the ocean. 7. This type of ecosystem plays an important role in regulating many biogeochemical cycles. 8. Oceans are the major sinks of CO2 and play an important role in biogeochemical cycle. 9. The oceans have two major life zones. 1. Coastal zone With relatively warm, nutrient rich shallow water. Due to high nutrients and ample sunlight this is the zone of high primary productivity. 2. Open sea It is the deeper part of the ocean, away from the continental shelf. It is vertically divided into three regions: (i) Euphatic zone, which receives abundant light and shows high photosynthetic activity. (ii) Bathyal zone receives dim light and is usually geologically active. (iii) Abyssal zone is the dark zone 2000 to 5000 meter deep. It has no sunlight. It is the largest ecological unit but it is an incomplete ecosystem. Various components of the ocean ecosystem are as follows: Abiotic components It is more stable in chemical composition due to being saline and moreover other physio-chemical factors such as dissolved oxygen content, light and temperature are also different. Marine water contains NaCl, Ca, Mg and K salts. Water is strongly buffered. Biotic components (i) Producers These are autotrophs. They are mainly phytoplanktons such as diatoms and some microscopic algae, seaweeds etc.

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(ii) Consumers These all are heterotrophic macro-consumers. They depend for their nutrition on the primary producers. These are: (a) Primary consumers They are herbivores and feed directly on producers, e.g., molluscs, crustaceans etc. (b) Secondary consumers These are carnivorous fishes as Shad, Herring etc. (c) Tertiary consumers They feed on other carnivores of the secondary consumers level. These are the top carnivores in the food chain, e.g., Cod, Haddock, and Halibut etc. (iii) Decomposers The microbes active in the decay of dead organic matter of producers and Macro-consumers are chiefly bacteria and some fungi. Freshwater ecosystems Although freshwater ecosystems are one of the main types of aquatic ecosystems, only 0.8% of the earth’s surface is covered by them. The water in freshwater ecosystems is non-saline (which means water has no salt content). Approximately 41% of the earth’s fishes are found in freshwater ecosystems. Examples of freshwater ecosystems are: • Streams and rivers (Lotic): Lotic ecosystems refer to systems with rapid flowing waters that move in a unidirectional way. Best examples are rivers and streams, which harbor several species of insects and fishes. Crustaceans like crayfish and crabs; and mollusks such as clams and limpets are commonly found in streams and rivers. Various mammals such as beavers, otters and river dolphins also inhabit lotic ecosystems. • Lakes, ponds and pools (Lentic): Lentic ecosystems are still waters such as lakes and ponds that have a community of biotic (living organisms) and abiotic (physical objects) interactions. Ponds and lakes have a diverse variety of organisms including algae, rooted and floating-leaved plants, invertebrates such as

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crabs, shrimps, crayfish, clams etc., amphibians such as frogs and salamanders and reptiles like alligators and water snakes. • Wetlands: The best examples of wetlands include swamps and marshes, where the water is completely or partially shallow. Biologically, wetlands are known to be too diverse as it harbors numerous animals and plant species. Plants such as black spruce, water lilies, mangrove, tamarack and sedges are commonly found in wetlands. Various species of reptiles and amphibians are also found in wetlands. Freshwater ecosystems, which are one of the major types of aquatic ecosystems, are in danger because of the rapid extinction rates of several invertebrates and vertebrates, mainly because of overfishing and other activities that harm the ecosystem. Streams and rivers These are bodies of flowing water moving in one direction. Streams and rivers can be found everywhere—they get their starts at headwaters, which may be springs, snowmelt or even lakes, and then travel all the way to their mouths, usually another water channel or the ocean. The characteristics of a river or stream change during the journey from the source to the mouth. The temperature is cooler at the source than it is at the mouth. The water is also clearer, has higher oxygen levels, and freshwater fish such as trout and heterotrophs can be found there. Towards the middle part of the stream/river, the width increases, as does species diversity—numerous aquatic green plants and algae can be found. Toward the mouth of the river/stream, the water becomes murky from all the sediments that it has picked up upstream, decreasing the amount of light that can penetrate through the water. Since there is less light, there is less diversity of flora, and because of the lower oxygen levels, fish that require less oxygen, such as catfish and carp, can be found. Physical features The limiting factors that govern what organisms can live in lotic ecosystems include current, light intensity, temperature, pH, dissolved oxygen, salinity, and nutrient availability—variables routinely measured by limnologists to develop a profile of the environment. These conditions differ greatly between small headwater streams and the mouths of such great rivers such as the Mississippi and the Amazon. Living occupants of streams and rivers show corresponding differences along the way.

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Small hard water streams, where water first collects by run-off from the land or emerges from springs, are called first-order streams. When two first-order streams meet, they form a second-order stream; two of these converge to form a third-order stream, and so on, until the water may flow into bodies as large as twelfth-order rivers (for example, the Columbia and the Mississippi). Bodies of the first to third order are usually considered streams, and those of the fourth order and larger are considered rivers. Streams provide diverse habitats including relatively swift rapids and quiet pools. They often have hard substrates of stones, rubble, or bedrock to which animals can cling. Flat rocks and rubble typically harbor the greatest species diversity of stream animals. Stream animals often have flat, streamlined bodies that are not easily swept away by currents, and hooks, suckers, or sticky undersides for clinging to substrates. They tend to face into a current and swim against it, behavior called rheotaxis. Food chains and ecosystem structure The bank of a stream or river is called the riparian zone, a place where overhanging foliage provides shade and the tree roots of undercut banks provide shelter. The deep shade produced by riparian foliage limits photosynthesis and primary production of organic nutrients. Much or most of the organic matter that nourishes the stream habitat originates as foliage that falls into the water, ranging from leaves, twigs, and seeds to fallen trees. Aquatic food chains in first-order streams thus begin with coarse particulate organic matter. This matter enters the food chain by way of aquatic bacteria and fungi that decompose it, and animals classified as shredders that tear it into finer particles. Shredders produce nutrient-rich feces that, in turn, are eaten by collectors. Farther downstream where there is more light, algae grow on rocks and other submerged surfaces and support a small community of animal grazers. Most shredders, collectors, and grazers are aquatic insects, but snails, bivalves, and crustaceans also play a part. The total population of these invertebrates is relatively small, however, so there are few predators in headwater streams; there is not enough for them to eat. Rivers, being wider, have more surface exposed to sunlight, so their primary productivity (photosynthesis) is greater. This is aided by inorganic nutrients such as nitrogen and phosphorus flowing down from the smaller-order streams. Fourth to sixth-order rivers

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provide ideal conditions for algae and rooted aquatic plants because of their softer substrates and ample light. Shredders become less abundant, grazers increase, and the relative populations of collectors and predators remain about the same. Species diversity increases in these mid-order rivers, with fish and burrowing animals such as clams and worms becoming more common. High-altitude, cold, oxygen-rich midsized rivers are an ideal haven for trout, which feed on the insect community. The organisms in mid-sized rivers, where there is more photosynthesis, produce more organic matter than they consume, and the excess nourishes the larger rivers downstream. Large rivers (seventh to twelfth-order) are relatively deep and wide. They are rich in organic matter but also contain a lot of inorganic sediment produced by erosion and run-off into the upland waters. Thus, the water is more turbid (muddy), and there is insufficient light to support as much photosynthesis as in smaller rivers. Collectors and predators dominate the consumer community, and consumption exceeds primary production. Fish species such as sturgeon and catfish, which feed on sediments, are more common here than predatory fish. All lotic organisms must adapt to drift, the incessant flow of water toward the sea, carrying nutrients and the organisms themselves downstream. Drift is particularly significant when spring snowmelts and heavy summer rains increase the current. River valleys offer especially rich farmland because of the great quantities of nutrients deposited by periodic flooding. Nutrient loss by drift is compensated for by the continual addition of riparian organic matter to the lowerorder upland streams, while animals compensate for drift by their rheotaxis and other means. Many aquatic insects fly upstream to lay their eggs, and fish such as trout and salmon are well known for their upstream spawning runs. The immature animals drift downstream as they grow and typically reach maturity at lower altitudes, only to repeat the process and deposit their offspring back in the headwaters. Lakes, ponds and pools These regions range in size from just a few square meters to thousands of square kilometers. Scattered throughout the earth, several are remnants from the Pleistocene glaciation. Many ponds are seasonal, lasting just a couple of months (such as sessile pools) while lakes may exist for hundreds of years or more. Ponds and lakes may have limited species diversity since they are often isolated from one another and

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from other water sources like rivers and oceans. Lakes and ponds are divided into three different “zones” which are usually determined by depth and distance from the shoreline. The topmost zone near the shore of a lake or pond is the littoral zone. This zone is the warmest since it is shallow and can absorb more of the Sun’s heat. It sustains a fairly diverse community, which can include several species of algae (like diatoms), rooted and floating aquatic plants, grazing snails, clams, insects, crustaceans, fishes, and amphibians. In the case of the insects, such as dragonflies and midges, only the egg and larvae stages are found in this zone. The vegetation and animals living in the littoral zone are food for other creatures such as turtles, snakes, and ducks. The near-surface open water surrounded by the littoral zone is the limnetic zone. The limnetic zone is well-lighted (like the littoral zone) and is dominated by plankton, both phytoplankton and zooplankton. Plankton are small organisms that play a crucial role in the food chain. Without aquatic plankton, there would be few living organisms in the world, and certainly no humans. A variety of freshwater fish also occupy this zone. Plankton have short life spans—when they die, they fall into the deep-water part of the lake/pond, the profundal zone. This zone is much colder and denser than the other two. Little light penetrates all the way through the limnetic zone into the profundal zone. The fauna are heterotrophs, meaning that they eat dead organisms and use oxygen for cellular respiration. Temperature varies in ponds and lakes seasonally. During the summer, the temperature can range from 4°C near the bottom to 22°C at the top. During the winter, the temperature at the bottom can be 4°C while the top is 0°C (ice). In between the two layers, there is a narrow zone called the thermocline where the temperature of the water changes rapidly. During the spring and fall seasons, there is a mixing of the top and bottom layers, usually due to winds, which results in a uniform water temperature of around 4°C. This mixing also circulates oxygen throughout the lake. Of course there are many lakes and ponds that do not freeze during the winter, thus the top layer would be a little warmer. Wetlands Wetlands are areas of standing water that support aquatic plants. Marshes, swamps, and bogs are all considered wetlands. Plant species adapted to the very moist and humid conditions are called hydrophytes.

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These include pond lilies, cattails, sedges, tamarack, and black spruce. Marsh flora also include such species as cypress and gum. Wetlands have the highest species diversity of all ecosystems. Many species of amphibians, reptiles, birds (such as ducks and waders), and furbearers can be found in the wetlands. Wetlands are not considered freshwater ecosystems as there are some, such as salt marshes, that have high salt concentrations—these support different species of animals, such as shrimp, shellfish, and various grasses. Functions of aquatic ecosystem Aquatic ecosystems perform many important environmental functions. For example, they recycle nutrients, purify water, attenuate floods, recharge ground water and provide habitats for wildlife. Aquatic ecosystems are also used for human recreation, and are very important to the tourism industry, especially in coastal regions. The health of an aquatic ecosystem is degraded when the ecosystem’s ability to absorb a stress has been exceeded. A stress on an aquatic ecosystem can be a result of physical, chemical or biological alterations of the environment. Physical alterations include changes in water temperature, water flow and light availability. Chemical alterations include changes in the loading rates of bio stimulatory nutrients, oxygen consuming materials, and toxins. Biological alterations include over-harvesting of commercial species and the introduction of exotic species. Human populations can impose excessive stresses on aquatic ecosystems. There are many examples of excessive stresses with negative consequences. Consider three. The environmental history of the Great Lakes of North America illustrates this problem, particularly how multiple stresses, such as water pollution, over-harvesting and invasive species can combine. The Norfolk Broadlands in England illustrate similar decline with pollution and invasive species. Lake Pontchartrain along the Gulf of Mexico illustrates the negative effects of different stresses including levee construction, logging of swamps, invasive species and salt water intrusion. Significance of aquatic ecosystems The study of aquatic ecosystem helps to understand the biodiversity (flora and fauna)of the aquatic ecosystem and their interaction with the physical and chemical environment. Aquatic ecosystems are in danger mainly because of human activities like: Overfishing, transportation, waste disposal, recreation and other activities which might harm the ecosystem.

CHAPTER

3

Biodiversity and its Conservation WHAT IS BIODIVERSITY? Biodiversity is the variety of species, their genetic make-up, and the natural communities in which they occur. It includes all of the native plants and animals and the processes that sustain life on Earth. For many groups of organisms, such as insects, fungi and algae, very little is known about them - not even what species occur in Pennsylvania! The need to understand the state’s rich natural resources has never been more critical. The term ecosystem is defined as a community of living organisms combined with their associated physical environment. It is our “home system” that makes life possible. Ecosystems are the full tapestry of nature that support life and they also provide valuable services. • Wetland ecosystems filter out toxins, clean the water and control floods. • Estuaries act as marine-life nurseries. • Forest ecosystems supply fresh water, provide oxygen, control erosion and remove carbon from the atmosphere. Actually Biological diversity, or the shorter “biodiversity”, (bio-diver-si-ty) simply means the diversity, or variety, of plants and animals and other living things in a particular area or region. For instance, the species that inhabit Los Angeles are different from those in San Francisco, and desert plants and animals have different characteristics and needs than those in the mountains, even though some of the same species can be found in all of those areas. Biodiversity also means the number, or abundance of different species living within a particular region. Scientists sometimes refer to the biodiversity of an ecosystem, a natural area made up of a community of plants, animals, and other living things in a particular physical and chemical environment. In practice, “biodiversity” suggests sustaining the diversity of species in each ecosystem as we plan human activities that affect the use of the land and natural resources.

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Environmental Chemistry

Many species, working together, are needed to provide these critical services. The loss of biodiversity reduces nature’s ability to perform these functions. As greater fluctuations occur, ecosystems as a whole become less stable. Instability causes ecosystems to be more vulnerable to extreme conditions and may also decrease productivity. Biodiversity is the variety and differences among living organisms from all sources, including terrestrial, marine, and other aquatic ecosystems and the ecological complexes of which they are a part. This includes genetic diversity within and between species and of ecosystems. Thus, in essence, biodiversity represents all life. India is one of the mega biodiversity centres in the world and has two of the world’s 18 ‘biodiversity hotspots’ located in the Western Ghats and in the Eastern Himalayas. The forest cover in these areas is very dense and diverse and of pristine beauty, and incredible biodiversity. WHY IS BIODIVERSITY IMPORTANT? Everything that lives in an ecosystem is part of the web of life, including humans. Each species of vegetation and each creature has a place on the earth and plays a vital role in the circle of life. Plant, animal, and insect species interact and depend upon one another for what each offers, such as food, shelter, oxygen, and soil enrichment. Maintaining a wide diversity of species in each ecosystem is necessary to preserve the web of life that sustains all living things. In his 1992 best-seller, “The Diversity of Life”, famed Harvard University biologist Edward O. Wilson – known as the “father of biodiversity”, – said, “It is reckless to suppose that biodiversity can be diminished indefinitely without threatening humanity itself”. • The air we breathe is a product of photosynthesis by green plants. • Insects, worms, bacteria, and other tiny organisms break down wastes and aid in the decomposition of dead plants and animals to enrich soils. • More than 90% of the calories consumed by people worldwide are produced from 80 plant species. • Almost 30% of medicines are developed from plants and animals, and many more are derived from these sources. TYPES OF BIODIVERSITY Biodiversity can be subdivided into three levels as follows:

Biodiversity and its Conservation

3.3

Genetic Diversity At finer levels of organisation, biodiversity includes the genetic variation within species, both among geographically separated populations and among individuals within the single population. Differences between individual organisms have two causes: variation in the genetic material which all organisms possess and which is passed on from generation to generation; and variation caused by environmental influence on each individual organism. New genetic variation, which arises by gene and chromosome mutation in individuals and in sexually reproducing organisms, is spread in the population by a recombination of genetic material during cell division preceding sexual reproduction. A great deal of work needs to be done on the conservation of genetic diversity within wild species in India. Protecting the Gir Habitat, for instance, has saved the Asiatic Lion. India also has a long tradition of domestic animal breeding for specific qualities. These include cattle, goats and sheep as well as horses and pigeons for sport. The replacement of numerous locally adapted varieties with a few high yielding strains in the large contiguous areas presents the danger of the spread of serious diseases capable of wiping out the entire crop, as happened prior to the Bengal rice famine in 1942. A productive and stable agriculture requires genetic diversity on the farm. Genetically diverse crop varieties enable farmers to fit their cropping systems to heterogeneous conditions, to enhance the food security of their households and to exploit a range of crop products. The challenges are at least two-fold; to meet farmers’ needs for wide genetic diversity whether through enhanced access to local varieties or newly introduced genetic resources; and to find strategies for linking longer-term conservation goals with immediate product needs.

Species Diversity Biodiversity at its most basic level includes the full range of species on earth from microorgnisms such as viruses, bacteria through the multi cellular kingdom of plants, animals and fungi. Thus, it refers to the variety of species within a region. It measured on the basis of number of species in the region. Species’ richness varies geographically. Out of an estimation 30 million species on earth, only one-sixth has been identified and authenticated in the past 200 years. Only 250,000 species of the total stock are plants.

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Environmental Chemistry

Keystone species have an important role in maintaining the diversity of a whole community of other species. Keystone species would include pollinators, top predators and the decomposer organisms and so-forth. The wild species are of considerable potential benefit to man in medicine, agriculture and industry as a natural source of drugs, food, fuel, fibre, industrial base compounds and additives.

Community and Ecosystem Diversity On the wider scale, biodiversity includes variations in the biological communities in which species live, the ecosystem in which communities exist, and the interactions among these levels. In the living world, interdependence and interaction between organisms and their environment are a very common practice to assert one’s existence on this planet. On the other hand, nature always tries to remain in homeostatic state and various life forms help to maintain this equilibrium. For both these cases, biodiversity serves as the source of livestock. To human beings, it opens avenues for understanding the laws and ways of nature and for making the optimum sustainable use of life support systems gifted to man by nature. The regulation of biogeochemical cycles, maintenance of predatorprey relationships by various types of food chains and food webs and finally the balance of nature are maintained through biodiversity. Again it indirectly influences the climatic factors, soil nature, chemistry of air etc., that are the abiotic elements of an ecosystem. Ecosystem diversity could be best understood if one studies the communities in various ecological niches within the given ecosystem. BIOGEOGRAPHICAL CLASSIFICATION OF INDIA India is the seventh largest country in the world and Asia’s second largest nation with an area of 3,287,263 sq.km encompassing a varied landscape rich in natural resources. India is shielded by the world’s highest mountains, the Himalayas, in the north. The southern part of India takes the shape of a peninsula and divides the Indian Ocean into the Bay of Bengal to the southeast and the Arabian Sea to the south-west. The southern tip of Kanyakumari is washed by the Indian Ocean. The Andaman and Nicobar Islands in the Bay of Bengal and the Lakshadweep group of Islands in the Arabian sea are also a part of India (Fig. 3.1).

Biodiversity and its Conservation

3.5

Fig. 3.1 Biogeographical Classification of India

“India, being a vast country, shows a great diversity in climate, topography and geology and hence the country is very rich in terms of biological diversity. India’s biological diversity is one of the most significant in the world, since India has only 2% of the total landmass of the world containing about 6% of the world’s known wildlife.” India has a great diversity of natural ecosystems from the cold and high Himalayan ranges to the sea coasts, from the wet north-eastern green forests to the dry northwestern arid deserts, different types of forests, wetlands, islands and the oceans. India consists of fertile river plains and high plateaus and several major rivers, including the Ganges, Brahmaputra and Indus. The climate of India is determined by the south-west monsoon between June and October, the northeast monsoon between October and November and dry winds from the north between December and February. From March to May the climate is dry and hot.

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Environmental Chemistry

The country has 10 different biogeographic zones and 26 biotic provinces show in Table 3.1 Table 3.1 Biogegraphical Zones of India S.No.

Biogeographic zones

Biotic provinces

1.

Trans-Himalaya

Ladakh mountains, Tibetan plateau

2.

Himalaya

North-west, West, Central and East Himalayas

3.

Desert

Thar, Kutch

4.

Semi-arid

Punjab plains, Gujarat Rajputana

5.

Western Ghats

Malabar plains, Western ghats

6.

Deccan Peninsula

Central highlands, Chottanagpur, Eastern highlands, Central plateau, Deccan south

7.

Gangetic Plains

Upper and Lower Gangetic plains

8.

Coast

West and East coast, Lakshadweep

9.

North-East

Brahmaputra valley, Northeast hills

Islands

Andaman and Nicobar

10.

1. The Trans-Himalayan Region This area is very cold and arid (4,500 to 6,000 mts. above msl). The only vegetation is a sparse alpine steppe. Extensive areas consist of bare rock and glaciers. The faunal groups best represented here are wild sheep and goats (chief ancestral stock), ibex, snow leopard, marbled cat, marmots and black-necked crane (Fig. 3.2).

Fig. 3.2 Marco Polo Sheep

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2. The Indian Desert The natural vegetation consists of tropical thorn forests and tropical dry deciduous forests, sandy deserts with seasonal salt marshes and mangroves are found in the main estuaries. Typical shrubs are phog growing on sand dunes. Sewan grass covers extensive areas called pali (Fig. 3.3).

Fig. 3.3 Last Surving Wild Ass (Distinct Sub-species)

Thar desert possesses most of the major insect species. 43 reptile species and moderate bird endemism are found here. No niche of the Thar is devoid of birds. The black buck was once the dominant mammal of the desert region, now confined only to certain pockets. The gazelle is the only species of the Indian antelope of which the females have horns. Nilgai, the largest antelope of India and the wild ass, a distinct subspecies, is now confined to the Rann of Kutch which is also the only breeding site in the Indian subcontinent for the flamingoes. Other species like desert fox, great Indian bustard, chinkara and desert cat are also found.

3. The Semi-arid Region The semi-arid region in the west of India includes the arid desert areas of Thar and Rajasthan extending to the Gulf of Kutch and Cambay and the whole Kathiawar peninsula (Fig. 3.4). The natural vegetation consists of tropical thorn forests and tropical dry deciduous forests, moisture forests (extreme north) and

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Environmental Chemistry

mangroves. The sandy plains have a few scattered trees of Acacia and Prosopis. The gravelly plains have Calotropis, Gymnosporia etc. The rocky habitats are covered by bushes of Euphorbia while species of Salvadora and Tamarix occur mainly near saline depressions.

Fig. 3.4 Last Surviving Asiatic Lion

The lion of Gir is the endemic species in this zone.

4. The Western Ghats They cover only 5% of India’s land surface but are home to more than about 4,000 of the country’s plant species of which 1800 are endemic. The monsoon forests occur both on the western margins of the ghats and on the eastern side where there is less rainfall. This zone displays diversity of forests from evergreen to dry deciduous (Fig. 3.5).

Fig. 3.5 Tiger National Animal

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The Nilgiri langur, lion tailed macaque, Nilgiri tahr, Malabar grey hornbill and most amphibian species are endemic to the Western Ghats. 5. The Deccan Peninsula The Deccan Peninsula is a large area of raised land covering about 43% of India’s total land surface. It is bound by the Sathpura range on the north, Western Ghats on the west and Eastern Ghats on the east. The elevation of the plateau varies from 900 meters. in the west to 300 meters. in the east. There are fosur major rivers that support the wetlands of this region which have fertile black and red soil. Large parts are covered by tropical forests. Tropical dry deciduous forests occur in the northern, central and southern part of the plateau. The eastern part of the plateau in Andhra Pradesh, Madhya Pradesh and Odisha has moist deciduous forests (Fig. 3.6). Fauna like tiger, sloth bear, wild boar, gaur, sambar and chital are found throughout the zone along with small relict populations of wild buffaloes, elephants and barasingha.

Fig. 3.6 Asiatic Wild Buffalo

6. The Gangetic Plain The Gangetic plain is one of India’s most fertile regions. The soil of this region is formed by the alluvial deposits of the Ganges and its

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Environmental Chemistry

tributaries. The four important surface differences recognised in the geomorphology of the plains are • Bhabar - Pebble studded zone with porous beds • Terai - Marshy tract • Bhangar - Older alluvium of the flood plain • Terai - Marshy tract • Khadar - Newer alluvium The Gangetic plains stretching from eastern Rajasthan through Uttar Pradesh to Bihar and West Bengal are mostly under agriculture. The large forest area is under tropical dry deciduous forest and the southeastern end of the Gangetic plain merges with the littoral and mangroves regions of the Sunderbans. The fauna includes elephants, black buck, gazelle, rhinoceros, Bengal florican, crocodile, freshwater turtle and a dense waterfowl community.

The Coastal Region The natural vegetation consists of mangroves. Animal species include dugong, dolphins, crocodiles and avifauna. There are 26 species of freshwater turtles and tortoises in India and 5 species of marine turtles, which inhabit and feed in coastal waters and lay their eggs on suitable beaches. Tortoise live and breed mainly on the land. Over 200,000 Olive Ridley turtles come to Odisha to nest in the space of three or four nights. The highest tiger population is found in the Sunderbans along the east coast adjoining the Bay of Bengal. Lakshadweep consists of 36 major islands - 12 atolls, 3 reefs and 5 submerged coral banks - make up this group of islands more than three hundred kilometers to the west of the Kerala coast. The geographical area is 32 sq. km and the usable land area is 26.32 sq. km. The fauna consists mainly of four species of turtles, 36 species of crabs, 12 bivalves, 41 species of sponges including typical coral, ornamental fishes and dugongs. A total of 104 scleractinian corals belonging to 37 genera are reported.

The North-East Biological resources are rich in this zone. The tropical vegetation of north-east India is rich in evergreen and semi-evergreen rain forests, moist deciduous monsoon forests, swamps and grasslands (Fig. 3.7).

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Mammalian fauna includes 390 species of which 63% are found in Assam. The area is rich in smaller carnivores. The country’s highest population of one-horned rhinoceros are found here.

Fig. 3.7 Great Indian One-horned Rhinoceros - Largest of all Existing Rhinoceros

The Indian Islands It is a group of 325 islands: Andaman to the north and Nicobar to the south. The two are separated by about 160 kms., by the 10° Channel of the sea. The rainfall is heavy, with both North-east and Southwest monsoons. At present, 21 of the 325 islands in the Andaman and Nicobar Islands are inhabited. Many unique plants and animals are found here. About 2,200 species of higher plants are found here of which 200 are endemic. The Andaman and Nicobar Islands have tropical evergreen forests and tropical semi-evergreen forests as well as moist deciduous forests and also littoral and mangrove forests (Fig. 3.8). 112 endemic species of avifauna, the Andaman water monitor, giant robber crab, 4 species of turtles, wild boar, Andaman day gecko and the harmless Andaman water snake are found only in these islands. The Narcondam hornbill found only in Narcondam is a large forest bird with a big beak. Coral reefs are stretched over an area of 11,000 sq.km, in the Andamans and 2,700 sq.km in Nicobar.

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Environmental Chemistry

Fig. 3.8 Living Corals

PLANTS IN INDIA Total number of plant species recorded in the world 2,50,000 species in India 45,000 species 33% of the above are native. There are 15,000 flowering plant species which is 6% of the world’s total. Areas rich in endemism are the North-east, the Western Ghats and the North-western and Eastern Himalayas. Andaman and Nicobar Islands contribute at least 200 endemic species to the endemic flora. Table 3.2 Classification Angiosperms Gymnosperms

No. of species 15,000 64

Pteridophytes

1,022

Bryophytes

2,584

Algae

2,500

Biodiversity and its Conservation

Fungi

3.13

23,000

Bacteria

850

Lichens

1,600

(Source: Rao, 1994: BSI, 1992)

According to Dr. M.S. Swaminathan, (1994), 2000 species are in danger of extinction in India. In the Western Ghats alone, 700 angiosperms are in a seriously threatened condition The BSI, (1992), has so far listed 814 plants in various categories such as extinction, endangered, vulnerable and rare. ANIMALS IN INDIA Total animal species recorded in the world 11,96,903 in India 86,874 Table 3.3 Larger animals Mammals Birds

No. of species 390 1,232

Reptiles

456

Amphibians

209

Fishes

2,546

(Source: Faunal diversity in India, ENVIS Centre, Zoological Survey of India, 1998)

India possesses little more than 7% of the total animal species of the world. This percentage is higher than that of the plant species. Out of a total of 86,874 animal species, insects alone comprise 68.52% and chordates 5.7%. Among the large animals, 173 species of mammals, 101 of birds, 15 of reptiles, 3 of amphibians and 2 of fishes are considered endangered.

Value of Biodiversity Throughout earth’s history, healthy ecosystems have usually been resilient enough to adapt to gradual environmental change. Existing species may evolve or new species move in, in response to small changes in the habitat without collapse of the entire system.

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Environmental Chemistry

Biodiversity, the range and variation of species in an ecosystem is a major factor in its resilience. If the environment changes and some organisms can no longer thrive, others will take their place. Many of the species vital to healthy ecosystems may appear insignificant. Insects for example play an essential role in pollinating food crops. The sheer variety of species and habitats on the planet is vast. This is of vital importance because it underpins the functioning of the ecosystems on which we depend for water and food, health and recreation. Values of biodiversity we can understand as: Values of Biodiversity

Direct Values

Consumptive Productive use Values use Values

Indirect Values

Social and Cultural Values

Ethical Values

Aesthetic Values

Option Values

Environment Service Values

Fig. 3.9 Values of Biodiversity

Direct values The direct value include food resources like grains, vegetables, fruits which are obtained from plant resources and meat, fish, egg, milk and milk products from animal resources. These also include other values like medicine, fuel, timber, fiber, wool, wax, resin, rubber, silk and decorative items. The direct values are of two types (i) Consumptive use value and (ii) Productive use value. Consumptive use value These are the direct use values where the biodiversity products can be harvested and consumed directly. Example: Food, fuel and drugs. These goods are consumed locally and do no figure in national and international market.

Biodiversity and its Conservation

3.15

Food The most fundamental value of biological resources particularly plants is providing food. Basically three crops i.e., wheat, maize and rice constitute more than two third of the food requirement all over the world. Fish: Through the development of aquaculture, techniques, fish and fish products have become the largest source of protein in the world. Fuel: Since ages forests have provided wood which is used as a fuel. Moreover fossil fuels like coal, petroleum, natural gas are also product of biodiversity which are directly consumed by humans. Drugs and medicines: The traditional medical practice like ayurveda utilises plants or their extracts directly. In allopathy, the pharmaceutical industry is much more dependent on natural products. Many drugs are derived from plants like Quinine: The famous antimalaria drug is obtained from cinchona tree. Penicillin: A famous antibiotic is derived from pencillium, a fungus. Tetracycline: It is obtained from bacterium. Vinblastin and Vincristine: These two anticancer drugs have been obtained from catharanthus plant which has anti cancer alkaloids. Productive use values: These are the direct use values where the product is commercially sold in national and international market. Many industries are dependent upon these values. Example- Textile, leather, silk, paper and pulp industry etc. Although there is an international ban on trade of products from endangered species like tusks of elephants, wool from sheep, fur of many animals etc. These are traded in market and fetch a booming business. Indirect values: Biodiversity provides indirect benefits to human beings which support the existence of biological life and other benefits which are difficult to quantify. These include social and cultural values, ethical values, aesthetic values, option values and environment service values. Social and cultural value: Many plants and animals are considered holy and sacred in India and are worshipped like Tulsi, peepal, cow, snake etc. In Indian society great cultural value is given to forest and as such tiger, peacock and lotus are named as the national animal, bird and flower respectively. Plants:

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Environmental Chemistry

These values are related to conservation of biodiversity where ethical issue of ‘all life forms must be preserved’ is laid down. There is an existence value which is attached to each species because biodiversity is valuable for the survival of human race. Moreover all species have a moral right to exist independent of our need for them. Aesthetic value: There is a great aesthetic value which is attached to biodiversity. Natural landscapes at undisturbed places are a delight to watch and also provide opportunities for recreational activities like bird watching, photography etc. It promotes eco-tourism which further generates revenue by designing of zoological, botanical gardens, national parks, wildlife conservation etc. Option values: These values include the unexplored or unknown potentials of biodiversity. Ethical:

Environment Service Values The most important benefit of biodiversity is maintenance of environment services which includes • Carbon dioxide fixation through photosynthesis. • Maintaining of essential nutrients by Carbon (C), Oxygen (O), Nitrogen (N), Sulphur (S), Phosphorus (P) cycles. • Maintaining water cycle and recharging of groundwater. • Soil formation and protection from erosion. • Regulating climate by recycling moisture into the atmosphere. • Detoxification and decomposition of waste.

Importance of Biodiversity The importance of biodiversity is often undervalued even though it helps humanity by: • regulating the chemistry of the atmosphere and water supply; • recycling nutrients crucial to the maintenance of the earth’s soil fertility; • providing ecological services such as the mass pollination of the world’s food crops; and • supplying genetic variants for crop development and the creation of new medicines. BIODIVERSITY AT GLOBAL, NATIONAL AND LOCAL LEVELS The enormous diversity of life forms in the biosphere has evolved essentially through the process of trial and error during course of

Biodiversity and its Conservation

3.17

organic evolution. The changes in character of living organism which confer some advantage to the species are retained. The changes in climatic conditions are reflected in the distribution of living organism and the pattern of biodiversity on our planet. The number of species present per unit area decreases as we move from mild tropics to the tundra’s. The Indian region (8° to 30° N and 60° to 97.5°) with total area of 329 million hectares is very rich in biodiversity. It is estimated that about 4500 species of plants occur in this country. The position of Indian sub-continent at the confluence of there biogeography reels is also an important contributing factor and explain the preserve of African, European, Sind, Japanese and Indo-Malayan elements in the flora and fauna in India. It is the sum total of such remarkable diversity that has made India a “gene bank” for a number of food crops, forest trees, medical and aromatic plants and domesticated animal. Warm tropical regions between the tropic of cancer and Capricorn on either side of equator have provided the most suitable habitat living organism. In habitat which does not provide the optimum conditions, organisms have to adopt themselves to the prevailing adverse conditions. Forests are important bioreserves, most of the 1700 million hectares of tropical forests are located in poor countries. The forests surrounding Reo de Aneroid are part of vegetation which is rich in species of plants and animals that are endemic. There are about 53.5% of trees species found only in these forests and studies of birds, reptiles, primates and butterflies have revealed equally high or higher endemics. It is important to preserve the numerous varieties of plants and animals that belong to one species. Each variety within a species contains unique genes and the diversity of genes within a species increases its capacity to adopt to pollution disease and other changes in the environment.

Biodiversity at Global Level The biodiversity of planet Earth is the total variability of life forms. Currently around 1.9 million extant species are believed to have been described, but this is thought to be a significant underestimate of the total number of extant species. Some 250,000 valid fossil species have

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Environmental Chemistry

also been named, but this is believed to be an even smaller proportion of all species that have ever lived. Biodiversity has grown and shrunk in earth’s past due to (presumably) abiotic factors such as extinction events, change in oxygen levels and changing sea levels. Climate change 299 million years ago was one such event. A cooling and drying resulted in catastrophic rainforest collapse and subsequently a great loss of diversity, especially of amphibians.

Fig. 3.10 Biodiversity of the Earth

Current threats to global biodiversity include natural extinction, an event that occurs to species yearly, as well as human actions such as pollution. Invasion of non-native species can also have a negative effect on global biodiversity Scientists have described over 1.7 million of the world’s species of animals, plants and algae as of 2010. The list below gives the number of species known in the world for each major category of animals and plants. The numbers most accurately represent all living species of mammals, birds and coniferous plants. Only for those groups have scientists almost completely identified all the world’s species. Biologists have yet to describe many species of plants, invertebrate animals and lichens. So the number of these species known to science increases substantially every year.

Biodiversity and its Conservation

3.19

The greatest species diversity exists among insects, which account for one million of the earth’s species known to science. Mammals make up one of the smallest groups, with just 5,490 members. Altogether the earth’s oceans, lakes, continents and islands support over 62,000 identified species of vertebrate animals and 320,000 species of plants. Table 3.4 Category

Species

Totals

Vertebrate Animals Mammals

5,490

Birds

9,998

Reptiles

9,084

Amphibians Fishes

6,433 31,300

Total Vertebrates

62,305

Invertebrate Animals Insects Spiders and Scorpions

1,000,000 102,248

Molluscs

85,000

Crustaceans

47,000

Corals

2,175

Others

68,827

Total Invertebrates

1,305,250

Plants Flowering Plants (angiosperms) Conifers (gymnosperms)

281,821 1,021

Ferns and Horsetails

12,000

Mosses

16,236

Red and Green Algae

10,134

Total Plants

321,212

Others Lichens

17,000

Mushrooms

31,496

Brown Algae

3,067

Total Others Total Species

51,563 1,740,330

3.20

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Environmental Chemistry

The species totals do not include domestic animals such as sheep, goats and camels. Nor do they include single-celled organisms such as bacteria.

Biodiversity at National Level and Local Level India has a rich and varied heritage of biodiversity, encompassing a wide spectrum of habitats from tropical rainforests to alpine vegetation and from temperate forests to coastal wetlands. India figured with two hotspots - the Western Ghats and the Eastern Himalayas. India contributes significantly to latitudinal biodiversity trend. With a mere 2.4% of the world’s area, India accounts for 7.31% of the global faunal total with a faunal species count of 89,451 species. India has two major realms called the Palaearctic and the IndoMalayan, and three biomass, namely the tropical humid forests, the tropical dry/deciduous forests, and the warm desert/semi-deserts. India has ten biogeographic regions including the Trans-Himalayan, the Himalayan, the Indian desert, the Semi-arid zone(s), the Western Ghats, the Deccan Peninsula, the Gangetic Plain, North-east India, and the islands and coastal area. India is one of the 12 centres of origin of cultivated plants. India has 5 world heritage sites, 12 biosphere reserves, and 6 ramsar wetlands. Amongst the protected areas, India has 88 national parks and 490 sanctuaries covering an area of 1.53 lakh sq. km. India’s record in agrobiodiversity is equally impressive. There are 167 crop species and wild relatives. India is considered to be the centre of origin of 30,000-50,000 varieties of rice, pigeon-pea, mango, turmeric, ginger, sugarcane, gooseberries etc., and ranks seventh in terms of contribution to world agriculture. INDIA AS A MEGADIVERSITY NATION India’s rich biological diversity - its immense range of ecosystems, species and genetic forms is by virtue of its tropical location, climate and physical features. India’s biogeographical composition is unique as it combines living forms from three major biogeographical realms, namely - Eurasian, Agro-Tropical and Indo-Malayan. India’s fabulous biodiversity is estimated to be over 45,000 plant species representing about 7% of the world’s flora; and its bewildering variety of animal life represents 6.5% of world’s fauna. 15,000 species of flowering plants, 53,430 species of insects; 5050 species of molluscs,

Biodiversity and its Conservation

3.21

6,500 species of other invertebrates; 2,546 species of fishes; 1228 species of birds, 446 species of reptiles, 372 species of mammals and 204 species of amphibians have been identified. In India about 1, 15,000 species of plants and animals have been identified and described. India stands tenth in 25 most plant-rich countries of the world. Plant richness means greater uniqueness of species present. India has been described as one of 12 megadiversity countries possessing a rich means of all living organisms when biodiversity is viewed as a whole. The greater the multidiversity of species, greater is the contribution to biodiversity. There are 25 clearly defined areas in the world called ‘hotspots’ which support about 50,000 endemic plant species, comprising 20% of the world’s total flora. India’s defined location of ‘hotspots’ is the Western Ghats and the North-eastern regions. Forests, which embrace a sizeable portion of biodiversity, now comprise about 64 m. hectares or about 19% of the land area of the country, according to satellite imaging. Roughly 33% of this forest cover represents primary forest. Indian flora comprises about 15,000 flowering plants and bulk of our rich flora is to be found in the North-east, Western Ghats, the North-west and Eastern Himalayas, and the Andaman and Nicobar Islands. Likewise, Assam and the Western Ghats are home to several species of mammal fauna, birds, and reptilian and amphibian fauna. As one of the oldest and largest agriculture societies, India has also a striking variety of at least 166 species of crop plants and 320 species of wild relatives of cultivated crops. There is a vital, but often-neglected factor when we focus on biodiversity. It may be a matter of she surprise for many to understand that the tribals who officially constitute 7.5% of India’s population have preserved 90% of the country’s biocultural diversity. To a large extent, the survival of our biodiversity depends on how best the tribals are looked after. To preserve our rich biodiversity, nine biosphere reserves are set up in specific biogeographic’’ zones: the biggest one is in the Deccan Peninsula in the Nilgiris covering Tamil Nadu, Andhra Pradesh and Karnataka. Others are the Nanda Devi in Uttarakhand in the Western Himalayas, the Nokrek in Meghalaya, Manas and Dibru Saikhowa in Assam, the Sunderban’s in the Gangetic plain in West Bengal, Similar in Odisha, the Great Nicobar and the Gulf of Mannar in Tamil Nadu.

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Environmental Chemistry

Hotspots of Biodiversity Life on Earth faces a crisis of historical and planetary proportions. Unsustainable consumption in many northern countries and crushing poverty in the tropics are destroying wild nature. Biodiversity is besieged. Extinction is the gravest aspect of the biodiversity crisis: it is irreversible. While extinction is a natural process, human impacts have elevated the rate of extinction by at least a thousand, possibly several thousand, times the natural rate. Mass extinctions of this magnitude have only occurred five times in the history of our planet; the last brought the end of the dinosaur age. In a world where conservation budgets are insufficient given the number of species threatened with extinction, identifying conservation priorities is crucial. British ecologist Norman Myers defined the biodiversity hot spot concept in 1988 to address the dilemma that conservationists face: what areas are the most immediately important for conserving biodiversity? A biodiversity hot spot is a biogeographic region with a significant reservoir of biodiversity that is under threat from humans. The biodiversity hotspots hold especially high numbers of endemic species, yet their combined area of remaining habitat covers only 2.3% of the Earth’s land surface. Each hot spot faces extreme threats and has already lost at least 70% of its original natural vegetation. Over 50% of the world’s plant species and 42% of all terrestrial vertebrate species are endemic to the 34 biodiversity hotspots.

Criteria for Betermining Hotspots • No of endemic species i.e., the species which are found no where else • Degree of threat, which is measured in terms of Habitat loss

Biodiversity Hotspots in India A biodiversity hot spot is a biogeographic region with a significant reservoir of biodiversity that is threatened with destruction. An area is designated as a hot spot when it contains at least 0.5% of plant species as endemic. There are 25 such hotspots of biodiversity on a global level, out of which two are present in India.

Biodiversity and its Conservation

3.23

These are: • The Eastern Himalayas • The Western Ghats and Sri Lanka These hotspots covering less than 2% of the world’s land area are found to have about 50% of the terrestrial biodiversity.

The Eastern Himalayas Stretching in an arc over 3,000 kilometers of northern Pakistan, Nepal, Bhutan and the north-western and north-eastern states of India, the Himalaya hot spot includes all of the world’s mountain peaks higher than 8,000 meters. This includes the world’s highest mountain, Sagarmatha (Mt. Everest). This immense mountain range, which covers nearly 750,000 km2, has been divided into two regions: the Eastern Himalaya, which covers parts of Nepal, Bhutan, the north-east Indian states of West Bengal, Sikkim, Assam, Arunachal Pradesh, south-east Tibet, China, and northern Myanmar and the Western Himalaya, covering the KumaonGarhwal, north-west Kashmir and northern part of Pakistan.

Plants Of the estimated 10,000 species of plants in the Himalaya hot spot, about 3,160 are endemic, as are 71 genera. Furthermore, five plant families are endemic to the region, the Tetracentraceae, Hamamelidaceae, Circaesteraceae, Butomaceae and Stachyuraceae. The largest family of flowering plants in the hot spot is the Orchidacea, with 750 species, and a large number of orchids, many representing rather young endemic species, have recently been reported from the hot spot, indicating that further exploration will probably reveal a much higher degree of plant endemism. The Eastern Himalaya is also a center of diversity for several widely distributed plant taxa, such as Rhododendron, Primula, and Pedicularis. In the Himalaya hot spot, a zone of permanent rock and ice begins at about 5,500-6,000 meters; in spite of these harsh conditions, there are records of vascular plants occurring at some of the highest elevations on Earth. Cushion plants have been recorded at more than 6,100 meters, while a high-altitude scree plant in the mustard family, Ermania himalayensis, was found at 6,300 meters on the slopes of Mt. Kamet in the north-western Himalayas.

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Environmental Chemistry

Vertebrates Birds Nearly 980 types of birds have been recorded in the hot spot, i.e., Eastern Himalayas out of these only 15 birds are endemic. The Critically Endangered Himalayan quail (Ophrysia superciliosa) represents an endemic genus in the region, although it has not been recorded with certainty since 1876, despite reports of possible sightings around Nainital in 2003. Bird Life International has identified four Endemic Bird Areas that overlap partially or fully with the Himalaya hot spot. The Western Himalaya EBA has 11 species restricted to it, including the Himalayan quail as well as the cheer pheasant (Catreus wallichii, VU) and the western tragopan (Tragopan melanocephalus, VU). The Eastern Himalaya EBA, which also overlaps with part of the Indo-Burma Hot spot, has nearly 20 endemic species, including four that are fully endemic to the Himalayas: the chestnut-breasted partridge (Arborophila mandellii, VU) and rusty-throated wren babbler (Spelaeornis badeigularis, VU), plus the white-throated tit (Aegithalos niveogularis) and orange bullfinch (Pyrrhula aurantiaca). Some of Asia’s largest birds live in this hot spot, and many are threatened by human activities. For example, some of the region’s vultures (Gyps spp.) have undergone dramatic declines after feeding on the carcasses of cattle that have been treated with the anti-inflammatory drug diclofenac. Of other birds present in the hot spot, the greater and lesser adjutants (Leptoptilos spp.) in the foothill grasslands and broadleaf forests, as well as the hornbills in the broadleaf forests, are threatened by loss of nesting trees and lack of food sources. Other avian flagships include the white-winged duck (Cairina scutulata, EN), the endemic white-bellied heron (Ardea insignis), and the Bengal florican (Houbaropsis bengalensis). Mammals About 300 mammal species have been recorded in the Himalayas, including a dozen that are endemic to the hot spot. Among the endemic species are the golden langur (Trachypithecus geei), restricted to a small area in the Eastern Himalaya, the Himalayan tahr (Hemitragus jemlahicus,) and the pygmy hog (Sus salvanius), which has its stronghold in the Manas National Park. The only endemic genus in the hot spot is the Namadapha flying squirrel (Biswamoyopterus biswasi, CR), described only from a single specimen from Namdapha National Park.

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The mammalian fauna in the lowlands is typically Indo-Malayan, consisting of langurs (Semnopithecus spp.), Asiatic wild dogs (Cuon alpinus), sloth bears (Melursus ursinus), gaurs (Bos gaurus), and several species of deer, such as muntjac (Muntiacus muntjak) and sambar (Cervus unicolor). In the mountains, the fauna transitions into Palearctic species, consisting of snow leopard (Uncia uncia), black bear (Ursus thibetanus), and a diverse ungulate assemblage that includes blue sheep (Pseudois nayaur), takin (Budorcas taxicolor), and argali (Ovis ammon). The alluvial grasslands support some of the highest densities of tigers (Panthera tigris) in the world, while the Brahmaputra and Ganges rivers that flow along the foothills also support globally important populations of the freshwater Gangetic dolphin (Platanista gangetica). Some of the world’s last remaining populations of wild water buffalo (Bubalus bubalis) and swamp deer (Cervus duvaucelii) are restricted to protected areas in southern Nepal and north eastern India. Reptiles Alhough there has been little systematic study of reptiles and amphibians in the Himalaya hot spot, at least 175 reptiles have been documented, of which nearly 50 are endemic. There is just one endemic genus, represented by a single species, the lizard Mictopholis austeniana, known only from the holotype. Other genera are well represented, and have many endemic species. These include Oligodon, Cyrtodactylus and Japalura. Amphibians Among amphibians, there are 105 species known to occur in the hot spot, more than 40 of which are endemic. Most of these are frogs and toads, although there are also two species of caecilians, one of which, (Ichthyophis sikkimensis) is endemic and occurs in northern India (in the States of Sikkim and West Bengal) and extreme eastern Nepal (in Dabugaun in the Ilam District) at elevations of 1,000 to 1,550 meters. Freshwater fishes Fish species from three major drainage systems, the Indus, Ganges, and Brahmaputra, inhabit the Himalaya hot spot, although the ranges of many species only just reach into the cold, high-altitude waterways of this region. As a result, only 30 of nearly 270 species are endemic.

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The three most diverse of the 30 different families represented here are minnows and carps (Cyprinidae; 93 species and 11 endemics), river loaches (Balitoridae; 47 species and 14 endemics), and sisorid catfishes (Sisoridae; 34 species and four endemics). The genus Schizothorax is represented by at least six endemic species in the high mountain lakes and streams, while two other genera of these snowtrout, the genus Ptychobarbus and the Ladakh snowtrout (Gymnocypris biswasi) — a monotypic genus now thought to be extinct — are also unique to the Himalayan region. Human impacts Despite their apparent remoteness and inaccessibility, the Himalayas have not been spared human-induced biodiversity loss. People have lived in the mountains of the Himalayas for thousands of years. In recent decades, greater access to the global market has increased the demand for natural resources in the area encouraged both immigration from outside (such as Arunachal Pradesh) and movement within the region (such as in Nepal). As a result, populations are growing in the most productive ecosystems, which are also some of the richest in biodiversity. Today, remaining habitat in the Himalaya is patchy. The steadily increasing population in the hot spot has led to extensive clearing of forests and grasslands for cultivation, and widespread logging. Both legal and illegal logging often occurs on extremely steep slopes, resulting in severe erosion. Although cultivation has a general upper limit of about 2,100 meters on slopes exposed to monsoons, people farm crops such as barley, potato and buckwheat at high elevations in the inner valleys and transmontane regions, and in some areas, such as Jumla, Kashmir, Lahoul and Ladakh, there are major agriculturally based population centers well above this elevation. The land is also often cleared in the summer months for livestock; the use of fire to clear land poses an additional threat to forest land, as fires sometimes spread out of control. The conversion of forests and grasslands for agriculture and settlements has led to large-scale deforestation and habitat fragmentation in Nepal, and in the Indian states of Sikkim, Darjeeling and Assam. Large areas of remaining habitat in the hot spot are highly degraded. Overgrasing by domestic livestock, including cattle and domesticated yak, is widespread in the lowlands and alpine ecosystems. The flora of fragile alpine meadows has been overexploited for traditional medicine

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(because medicinal plant collectors invariably uproot the entire plant, regrowth is retarded). Fuelwood collection and non-timber forest product extraction, both for domestic consumption and export, has inflicted severe damage to some forest ecosystems. Unplanned and poorly managed tourism has led to environmental deterioration. Political unrest, often in the form of insurgencies, also threatens the integrity of some protected areas. In addition to habitat loss and degradation, which has led to perhaps no more than 25% of the original vegetation in this hotspot still intact, poaching is a serious problem in the Himalayan Mountains, with tigers and rhinoceros hunted for their body parts for traditional Chinese medicine, while snow leopards (Uncia uncia) and red pandas (Ailurus fulgens) are sought for their beautiful pelts. Other threats to biodiversity and forest integrity include mining, the construction of roads and large dams, and pollution due to the use of agrochemicals.

Conservation Action and Protected Areas While the earliest protected areas, in Assam, were established as wildlife sanctuaries in 1928 and 1934, most other protected areas in the region are relatively new, having been established only in the last three or four decades. However, many hill-tribe communities have traditionally recognised and protected sacred groves, which have served as effective refuges for biodiversity for centuries. Today, several protected areas Corbett National Park, Manas National Park, Kaziranga National Park, Chitwan National Park, and Sagarmatha National Park) have been distinguished as World Heritage Sites for their contribution to global biodiversity. In the north-eastern Himalayan states of India, a network of protected areas established in the 1970s and 1980s, including Corbett and Rajaji National Parks. These protected areas harbor important populations of elephants and tigers. In Nepal, 21 protected areas cover at least 26,666 km2 of land. Chitwan, which was established as the country’s first national park in 1973, is well known for its tiger and greater one-horned rhinoceros (Rhinoceros unicornis) populations. Also in Nepal, the Annapurna Conservation Area, the Kanchenjunga Conservation Area and the Makalu-Barun National Park are all run through community-based biodiversity management. Although a protected area system was established in Bhutan as early as the 1960s, this system was dominated by the Jigme Dorji Wangchuck

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National Park. The park was mostly confined to the north of the country, and did little to contribute towards biodiversity conservation because most of the park protected vast areas of permanent rock and ice. In 1995, the protected area system was revised to include all nine of the current protected areas (five national parks, three wildlife sanctuaries, and one strict nature reserve) accounting for almost 26% of the total land area in Bhutan. In 1999, based on a WWF field survey, another 9% was added to the system in the form of 12 biological corridors, which linked the protected areas to create a conservation landscape extending across the country. The biological corridors provide connectivity between parks and reserves for wildlife species such as tigers and snow leopard to follow seasonal movement of their prey species. The Royal Government of Bhutan is committed to maintaining 60% of their forest cover in perpetuity along with the biological corridors.

The Western Ghats and Sri Lanka Of India’s 15,000 plant species with 5,000 endemics (33%), there are 4,050 plants with 1,600 endemics (40%) in a 17,000 sq.km strip of forest along the seaward side of the Western Ghats in Maharashtra, Goa, Karnataka, Tamil Nadu and Kerala. Forest tracts up to 500 m in elevation, comprising one fifth of the entire forest expanse are mostly evergreen, while those in the 500-1500 m range are semi-evergreen. There are two major centres of diversity, the Agasthyamalai Hills and the Silent Valley/New Amarambalam Reserve basin. (Source: Teri, New Delhi).

Flora and Fauna The area has an estimated 3,00,000 hectare (37%) under forest cover and is characterised by a rich diversity of flora and fauna. The region has about 4,500 species of flowering plants. Of these about 1,700 are endemic to the Western Ghats. Nearly one third are rare or threatened and several are believed to be extinct.

Flora Over 5,000 different plants occur in the Western Ghats. Around 1,700 of these are found nowhere else in the world. This includes the wild relatives of many economically important species, such as grains (including rice and barley), fruits (mango, banana and jackfruit), and spices (black pepper, cinnamon, cardamom

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and nutmeg), as well as numerous medicinal plants, such as the highly threatened white damor (Vateria indica). The fragrant resin and seed oil of this large evergreen tree can be used in medicines, as well as in soap and candle manufacturing. Other notable plants that occur in the Western Ghats include Wight’s sago palm (Arenga wightii) whose starch and sap (palm wine) provides an alternate source of food and drink for the local Muthuvans tribes, and Cycas circinalis, an endangered cycad that plays an important role in the ecosystem. Not only does this cycad host the plains cupid butterfly (Edales pandava), but it is also thought that fruit bats feed on its seeds, providing one of the few food sources in the forest during the monsoon season.

Fauna Amphibians Over 117 species belonging to 21 genera are recorded in the forests and coastal areas of this region, of which 76% are endemic to the region. Invertebrates A large variety of insects including some of the spectacular butterflies and moths occur in the dense evergreen highland and lowland forests. It is estimated that India has over 1,400 species of which the Western Ghats harbour nearly 320 species including 37 endemics and 23 others shared with Sri Lanka. The area is host to a large variety of fresh water mollusca, some of which are specific to the region. Fish The fish fauna of both fresh water montane and lowland river streams and water bodies as well as coastal lagoons and backwaters are very many and varied in this region. There is large commercial coastal fishery of finish and shell fish in this region. Reptiles Dense forests of the region are the home of the King Cobra and Rock Python apart from other smaller reptiles. Many species of tortoises including the endemic cane turtle, and terrapin are also found in the Western Ghats. The marsh crocodile or mugger distributed in swamps and larger water bodies of the forested areas.

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Birds About 508 species of birds occur in the Western Ghats (590 if subspecies are included). Among these about 16 species are endemic. Many endemic birds are exclusive to evergreen and Shola forests. Mammals The forests of the area have large herbivores such as gaur, spotted deer sambar, barking deer, elephant, etc. Carnivores are represented by tiger, leopard, jungle cat, leopard cat, fishing cat, Malabar civet, brown palm civet, small Indian civet, two species of mongoose and wild dog. Several genera of mammals are endemic and representatives include slender lorris, the Lion-tailed macaque, 2 species of mongoose, 2 species of civet, Nilgiri langur, Nilgiri tahr, grizzled giant squirrel and the rusty spotted cat. BIODIVERSITY HOTSPOTS IN WORLD

1. Africa Eight Hotspots hold a diversity of plant and animal life, many of which are found nowhere else on Earth. (a) Cape Floristic Region Evergreen fire-dependent shrublands characterise the landscape of the Cape Floristic Region. (b) Coastal Forests of Eastern Africa Though tiny and fragmented, the forest remnants that make up the Coastal Forests of Eastern Africa contain remarkable levels of biodiversity. (c) Eastern Afromontane The mountains of the Eastern Afromontane hot spot are scattered along the eastern edge of Africa, from Saudi Arabia in the north to Zimbabwe in the south. (d) Guinean Forests of Western Africa The lowland forests of West Africa are home to more than a quarter of Africa’s mammals, including more than 20 species of primates. (e) Horn of Africa The arid Horn of Africa has been a renowned source of biological resources for thousands of years. (f) Madagascar and the Indian Ocean Islands Madagascar and its neighboring island groups have an astounding total of eight plant families, four bird families, and five primate families that live nowhere else on earth.

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(g) Maputa la nd-Pondola nd-A lba ny Maputaland-PondolandAlbany, which stretches along the east coast of southern Africa below the Great Escarpment, is an important center of plant endemism. (h) Succulent Karoo The Succulent Karoo of South Africa and Namibia boasts the richest succulent flora on earth, as well as remarkable endemism in plants.

2. Asia-Pacific Composed of large land areas as well as islands dotting the Pacific seas, these 13 hotspots represent important biodiversity. (a) East Melanesian Islands Once largely intact, the 1,600 East Melanesian Islands are now a hotspot due, sadly, to accelerating levels of habitat loss. (b) Himalaya The Himalaya Hotspot is home to the world’s highest mountains, including Mt. Everest. (c) Indo-Burma Encompassing more than 2 million km² of tropical Asia, Indo-Burma is still revealing its biological treasures. (d) Japan The islands that make up the Japanese Archipelago stretch from the humid subtropics in the south to the boreal zone in the north, resulting in a wide variety of climates and ecosystems. (e) Mountains of South-West China With dramatic variations in climate and topography, the Mountains of South-west China support a wide array of habitats including the most endemic-rich temperate flora in the world. (f) New Caledonia An island the size of New Jersey in the South Pacific Ocean, New Caledonia is the home of no less than five endemic plant families. (g) New Zealand A mountainous archipelago once dominated by temperate rainforests, New Zealand harbors extraordinary levels of endemic species. (h) Philippines More than 7,100 islands fall within the borders of the Philippines hot spot, identified as one of the world’s biologically richest countries. (i) Polynesia-Micronesia Comprising 4,500 islands stretched across the southern Pacific Ocean, the Polynesia-Micronesia hot spot is the epicenter of the current global extinction crisis.

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(j) South-west Australia The forest, woodlands, shrublands, and heath of South-west Australia are characterised by high endemism among plants and reptiles. (k) Sundaland The spectacular flora and fauna of the Sundaland hot spot are succumbing to the explosive growth of industrial forestry in these islands. (l) Wallacea The flora and fauna of Wallacea are so varied that every island in this hot spot needs secure protected areas to preserve the region’s biodiversity. (m) Western ghats and Sri Lanka Faced with tremendous population pressure, the forests of the Western Ghats and Sri Lanka have been dramatically impacted by the demands for timber and agricultural land.

3. Europe and Central Asia From the Mediterranean Basin to the Mountains of Central Asia, these four Hotspots are unique in their diversity. (A) Caucasus The deserts, savannas, arid woodlands, and forests that comprise the Caucasus hot spot contain a large number of endemic plant species. (b) Irano-Anatolian Forming a natural barrier between the Mediterranean Basin and the dry plateaus of Western Asia, the mountains and basins that make up the Irano-Anatolian hot spot contain many centers of local endemism. (c) Mediterranean Basin The flora of the Mediterranean basin is dramatic. Its 22,500 endemic vascular plant species are more than four times the number found in all the rest of Europe. (d) Mountains of Central Asia Comprising two of Asia’s major mountain ranges, the Mountains of Central Asia were known to early Persians as the “roof of the world”.

4. North and Central America North and Central America play host to thousands of acres of important habitat. (a) California Floristic Province The California Floristic Province is a zone of Mediterranean-type climate and has the high levels of plant endemism characteristic of these regions. (b) Caribbean Islands The Caribbean Islands support exceptionally diverse ecosystems, ranging from montane cloud forests to cactus

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scrublands, which have been devastated by deforestation and encroachment. (c) Madrean Pine-Oak Woodlands Encompassing Mexico’s main mountain chains, and isolated mountaintop islands in Baja California and the southern United States, the Madrean PineOak Woodlands is an area of rugged mountainous terrain, high relief and deep canyons. (d) Mesoamerica The Mesoamerican forests are the third largest among the world’s hotspots. Their spectacular endemic species include quetzals, howler monkeys, and 17,000 plant species.

5. South America From Brazil’s Cerrado to the Tropical Andes, South America has some of the richest and most diverse life on Earth. (a) Atlantic Forest The Atlantic Forest of tropical South America boasts 20,000 plant species, 40% of which are endemic. (b) Cerrado The Cerrado region of Brazil, comprising 21% of the country, is the most extensive woodland-savanna in South America. (c) Chilean Winter Rainfall-Valdivian Forest A virtual continental island bounded by the Pacific Ocean, the Andes Mountains, and the Atacama Desert, the Chilean Winter Rainfall-Valdivian Forests harbors richly endemic flora and fauna. (d) Tropical Andes The richest and most diverse region on Earth, the Tropical Andes region contains about 5% of all vascular plant species in less than 1% of the world’s land area. (e) Tumbes- Chocó-Magdalena Tumbes- Chocó-Magdalena is bordered by two other hotspots: Mesoamerica to the north, and the Tropical Andes to the east. THREATS TO BIODIVERSITY: HABITAT LOSS, POACHING OF WILDLIFE Extinction is the complete elimination of wild species: It is a Natural but slow process but due to unplanned activities of man, the rate of decline of wildlife has been particularly rapid in the last one hundred years. There are a number of causes which are known to cause the extinction of wildlife.

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Habitat Loss A habitat is the natural home for an animal or plant. Habitat destruction is when an animal or plant loses its natural home, usually caused by something humans have done. If an animal’s habitat gets destroyed, it might die out. If this happens, it can affect all animals above it on the food chain. Habitat destruction is one of the main threats to biodiversity. Biodiversity refers to the various kinds of plants and animals that live in a particular area. Arctic communities have less biodiversity because of the very few species of animals that live there. Tropical forests, however, have thousands of different animal and plant species, making them the most biodiverse areas on earth. Ecologists use biodiversity as a way of measuring how habitats are affected by land use. All species need specific food and a specific habitat to survive. The more specific these needs, the greater the risk to the species if their habitat changes or is lost. We humans are a major cause of habitat destruction. While animal populations do not usually rise sharply, the number of human beings on our planet has risen steeply in the last few centuries. This huge increase is putting pressure on natural resources. Our needs are growing, and these needs are often causing habitat destruction. Here are some major causes of habitat destruction.

Deforestation Deforestation leads to decrease in the area of movement so decreasing their reproductive powers. Main causes of its facing extinction are: (1) Soil erosion (2) Agricultural expansion (3) Oxen grazing (4) Increasing urbanisation (5) Forest affairs due to certain human activities or by chance (6) Development works like dams reservoirs, made railway lines, industries, mines etc. Logging People are cutting down the forests and rain forests for wood and wood products. Usually, only large prime trees are cut down, such as mahogany. However, smaller trees can be destroyed in the process and

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never replaced. Logging can cause soil erosion, and the logging roads that are built can damage rivers and streams. For most of the world’s poor people, wood is the only source of fuel they have. Eighty percent of all wood used worldwide is for fuel. Collecting wood for fuel does not necessarily destroy rain forests, but it does damage or degrade them. Agriculture Wild lands are being cleared for crops and domestic animals. The single biggest cause of deforestation is farming. Animals used to living in a biodiverse habitat cannot survive in an area with one crop. Building roads and cities Humans are clearing trees and wild lands to make room for roads and cities. Cities replace the natural habitat of many species of plants and animals. Highways and freeways can destroy plants and also keep animals from safely traveling through their natural habitat. Forest fires Forest fires destroy or damage between 15 and 36 million acres of tropical forest every year. Sometimes the fires are started on purpose as a way to illegally clear an area of trees.

Poaching Another major problem is the poaching and killing of animals and birds. Many species of animals and birds are hunted for their fleshes, skins, furs, feathers, bones, tusks, horns, venomes and so on. This unjustified killing is going on even today. Apart from poachers and smugglers, various ethnic groups or Adivasis are used to kill faunal wealth for satisfying their faith, taboo or for amusement. In addition, the clearing of natural forests to make room for commercial plantations causes innumerable damage to wildlife. It is followed by monoculture of plants. Monoculture of a particular plant species may result in genetic uniformity and quick mass transport of pathogens during the outbreak of a disease. Monoculture also causes a drastic change in the food habit or certain herbivores and birds depending on plants. It may lead to elimination of species and as a result the food chain of an ecosystem faces a real crisis. In the first of the century, lion and in particular tiger have been decimated by the British and the Indian royalty for purposes of sport

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at present tiger is being killed on account of the sale of its bones and other parts to meet the unprecedented demand for traditional Chinese medicine.

Man Wildlife Conflicts There are about 1,50,000 species of fauna in the world and India possessed about 75,000 species of animals. The illegal poaching and unauthorised hunting has harmed the fauna to such an extent that many species of animals have become extinct and many are on the verge of extinction. At least 30% of the trade is illegal and stands next only in value to narcotics trade. As long as this type of money is involved, rare animals will continue to be killed illegally. There is a conflict between biodiversity conservators and general public because the public is not taking interest in wildlife management. A general awareness has to be developed. People’s participation and more stringent implementation of anti poaching laws and better backup facilities like faster vehicles, modernised weapons and more power to tackle poachers at the field level can perhaps reduce the magnitude of the problem of indiscriminate poaching and extermination of many rare species.

Endangered Species Endangered species are species that have a high likelihood of going extinct in the near future. Endangered species are (according to Mace and Lande) with a 20% probability of extinction within 20 years or 10 generations. Endangered species are those considered to be at risk of extinction, meaning that there are so few left of their kind that they could disappear from the planet altogether. Endangered species are threatened by factors such as habitat loss, hunting, disease and climate change, and usually, endangered species, have a declining population or a very limited range. The current rate of extinction is thought to be far greater than the expected natural rate, with many species going extinct before they have even been discovered. Shockingly, current estimates suggest that a third of the world’s amphibians, a quarter of all mammals and one in eight birds are endangered. Endangered species usually have a small or declining population size or a very limited range, meaning factors such as habitat loss,

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hunting, disease or climate change could cause them to disappear completely within our lifetimes.

Why are Species Endangered? Animals and plants face a large number of different threats with many of them being a direct result of human activity. Some of the most common threats include: • Habitat loss and habitat fragmentation – The ever expanding human population constantly requires additional space and resources. Land is being cleared to harvest products such as timber as well as to make way for human settlement, agriculture and transport links. • Hunting and poaching – A wide variety of animals have been hunted, or fished, beyond sustainable levels and now face possible extinction. Species, such as the tiger, are often hunted because they provide a resource such as food or parts which are used in traditional ‘medicine’. However, some species, such as the cheetah, have been persecuted after gaining a negative reputation for feeding upon livestock or crops or posing a threat to human safety. • Invasive species – Humans have introduced non-native species (both intentionally and accidentally) to a wide variety of habitats, often with devastating consequences. Introduced species may prove highly adaptable and out compete native species for resources. Introduced predators can decimate local species which are not adapted to avoid predation, for example, ground dwelling birds like the kakapo. • Climate change – Droughts, ocean acidification, the loss of sea ice and an increase in storms and extreme weather events can all threaten species’ survival. Sedentary species like plants or specialist species which inhabit small ranges or islands, or those with specific habitat requirements are particularly vulnerable. • Disease – Small populations, especially those which are limited in terms of genetic diversity are particularly vulnerable to disease. Disease can often be spread by domestic animals or accidentally introduced by humans travelling from an affected area to one which had not previously been exposed. • Collection/pet trade – Many animals and plants, such as the Venus flytrap, have been collected from the wild beyond sustainable

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levels to be sold through the pet trade or be kept in private horticultural collections. • Pollution – Acid rain, heavy metals, pesticides, plastic waste and oil spills all harm the environment and put species at risk. Chemicals are particularly harmful to species that live in water.

What is Being Done to Help Endangered Species? Conservation aims to protect the natural world and sustain biodiversity by carefully preserving and managing existing habitats and restoring areas which have been damaged or degraded. Species conservation can also take place outside a species’ natural habitat. For example, caring for an endangered animal in captivity, such as in a zoo, or preserving endangered plants through the use of seed banks. In areas, where humans and animals are competing for space or resources, particularly in poorer developing countries, it is important that conservation work takes into account the needs of local people and works alongside them in protecting their native species. Some commonly used conservation actions are as follows: • Habitat preservation – The ideal solution is to protect habitats before they are damaged. This can be achieved through the creation of national parks and marine protected areas. However, it is important to note that many larger species require extensive territories and designated protected areas may not be large enough to support them. • Habitat restoration – Where a habitat has already been degraded it is sometimes possible to restore the habitat by carefully managing the land, removing invasive species and reintroducing native species that had been lost from the area. Some species are bred in captivity or relocated from other areas for this purpose. • Ex-situ conservation – Many endangered species are bred in captivity to preserve their numbers and in some cases it is possible to reintroduce them to the wild. Some species, like the Golden arrow poison frog, have even been deliberately removed from the wild to protect them from the spread of disease and ensure that a small population is preserved. Plant species are often cultivated in nurseries and preserved via the use of seed banks.

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• Anti-poaching measures – In remote areas guards are sometimes employed to protect endangered species, such as the mountain gorilla, from poachers. This can be a way of involving local communities in the protection of their wildlife whilst also providing some employment opportunities. • Wildlife corridors – Where habitats have been fragmented by divisions such as roads, urban areas or farmland, populations become isolated and are unable to move throughout their natural range to find sufficient resources and mates. Wildlife corridors help to reconnect habitat fragments and maintain genetic diversity. • Laws and policies – Some endangered species are protected by law or trade in them is restricted. CITES (The Convention on International Trade in Endangered Species) is an international agreement between governments to ensure that trade in wild animal and plant specimens does not threaten their survival.

Critically Endangered Species These species with a 50% or greater probability of extinction within 5 years or 2 generations whichever is longer. Critically endangered species probably cannot survive without direct human intervention. Vulnerable species Vulnerable species are not endangered but is facing a very high risk of extinction in the future. Threatened species These species are abundant but are declining in total numbers. Basically threatened species are those that are facing threats to their survival, and may be at risk of extinction or we can say that “A threatened species is a native species that is at risk of becoming endangered in the near future. A threatened species may have a declining population or be exceptionally rare. Like endangered species, the cause of its rarity is variable, but may be due to threats such as habitat destruction, climate change, or pressure from invasive species”.

Why are Species Threatened? Native plant and animal species and their populations are exposed to all kinds of threats that vary between species and populations. Common threats include:

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• Loss, as well as fragmentation and degradation, of habitat • Changed fire patterns (changed frequency, intensity and scale of fire) • Changed quantities and patterns in water and water flows • Competition with introduced plants (e.g. weeds) or feral/exotic animals for resources (e.g. food, light, water, shelter) • Predation by introduced animals (e.g. foxes and feral cats) • Grazing by feral animals (e.g. rabbits) and livestock) • Pollution and diseases (such as the root rot Phytophthora, an infectious soil and waterborne mould that causes plant dieback) • Illegal collecting, hunting and fishing • Climate change.

Rare Species Rare species are species that have small total numbers of individuals but are not necessarily in immediate danger of extinction. These are species with small total population size in the world ,their distribution are usually localised within restricted area of world. There are many ways by which a species can become rare and the process has diverse ecological consequences. Human-induced perturbations such as habitat loss are identified as one of the important causes of rarity. However, intrinsic features such as breeding behaviour, dispersal modes, habitat specificity etc., are also likely to govern the distribution and survival of species in their natural habitats and hence might render species to become rare and endangered. Rare species are organisms that are considered to be very uncommon. They can include both plants and animals. A rare animal can be an endangered species; most rare organisms are considered threatened, as they cannot recover quickly from catastrophic events and face the threat of rapid population decline. Animal species that are considered to be rare do not have to be endangered. They can simply be found in a small concentrated area. Such areas are usually remote and very isolated from the rest of the world. In some of the cases, they may not be threatened at all, naturally existing in small numbers. An official government body may declare a species as rare. States, national governments, and provinces have all designated rare plants

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and animals. To be listed as rare, a species must usually consist of less than 10,000 worldwide. The United States is home to many rare species. The Laysan Duck of Hawaii is a rare bird species. A rare plant species, the Virginia Round-leaf Birch, can be found in Cressy Creek, Virginia. The showy Indian clover, ash meadows stick-leaf, and baker’s larkspur. All rare plants, grow in the United States as well. New Zealand lists several species as being rare, including the black robin and the kakapo. Rare reptile species include the Aruba Island rattlesnake and the Abingdon Island tortoise of Ecuador, while the Javan rhinoceros and the cao-vit crested gibbon, both of Vietnam, are listed as rare mammal species. The Lord Howe Island stick insect is a well-known rare insect species in the scientific community. Earth’s rarest animals exist in numbers fewer than 50. Less than 30 Vancouver Island marmots exist, while the baiji, or Yangtze River dolphin, has less than 20 animals of its kind remaining. The Seychelles sheath-tailed bat is listed as rare with fewer than 50 bats left in existence. Animals with fewer than 100 species left include the tamaraw, or dwarf water buffalo, the northern hairy-nosed wombat, and the Hispid hare. Food chains make no distinction regarding rare animals. Small animals, normally a source of prey, can be rare. The Riverine rabbit is one example. Larger, predatory creatures, such as the Iberian lynx and Ethiopian wolf, are also considered rare species. Many other rare species exist with numbers between 200 to 1,000. Several types of primates, including the yellow-tailed wooly monkey, Tonkin snub-nosed monkey, black-faced lion tamarin, and greater bamboo lemur are listed as rare. The giant panda, one of the most well-known endangered species in the world, is also a rare species.

Endemic Species An endemic species is one whose habitat is restricted to a particular area. The term could refer to an animal, a plant, a fungus, or even a microorganism. The definition differs from “indigenous”, or “native”, species in that the latter, although it occurs naturally in an area, is also found in other areas. Endemic species are often endangered, and particular examples may become a focus point for campaigns to protect biodiversity in a given environment. Some have become national, or regional emblems.

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The term can sometimes be used relatively. A species may be said to be endemic to one tiny area or to a large land mass, such as Australia. When it comes to birds, which are less land-bound than mammals or other animals, biologists might use slightly different terms to talk about what habitats a bird is “endemic” to. Bird experts talk about Endemic Bird Areas or EBAs that represent the total habitat for a bird species. An EBA may include temporary habitats or regions for a bird, as migration patterns broaden the spaces that bird types live in.

How Endemic Species Arise? There are two ways in which a species may come to be endemic to a particular area. An initially widely distributed population may disappear from many of its habitats, due to changes which have occurred. These could be climate changes, an influx of predators, or human activities. Eventually, the organism may be confined to just one area: this type is known as a paleoendemic species. A good example is the giant sequoia tree, which used to be found over large parts of North America, but is now confined to a small part of California. Alternatively, various factors could cause two populations of a given species to become isolated from one another. For example, as a result of plate tectonics, a continent may split apart, forming two new continents, each with its own population of a given organism. Over long periods of time, these two populations evolve differently, because they cannot interbreed with one another, and eventually they are sufficiently different from one another to be classified as separate species. These are known as neoendemic species. In some cases, where a population has been isolated for a very long time, the members may look very different from anything elsewhere on the planet; for example, Australia has a number of unique animals, such as kangaroos and koala bears. Determining whether a species is paleoendemic or neoendemic may not always be easy. Occasionally, when an organism has declined in relatively recent times, it is known from historical records that it was once more widely distributed. In other cases, this can be determined from fossil records, but this depends on such evidence being available — it requires exposed rocks of the right age and type to preserve identifiable fossil remains. An organism may be classed as neoendemic if there is no evidence of it having ever existed outside its current range. Such species may sometimes have specific adaptations for some unique aspect of their habitat.

.

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Endemic Species of India Mammals: Few endemic mammals of India are Anathana ellioti (Scandentia - Tupaiidae) South Indian Tree Shrew Tupaia nicobarica (Scandentia - Tupaiidae) Nicobar Tree Shrew Macaca radiata (Primates - Cercopithecidae) Bonnet Macaque Macaca silenus (Primates - Cercopithecidae) Lion-tailed Macaque Semnopithecus dussumieri (Primates - Cercopithecidae) Southern Plains Gray Langur Semnopithecus hypoleucos (Primates - Cercopithecidae) Black-footed Gray Langur Trachypithecus johnii (Primates - Cercopithecidae) Nilgiri Langur Paraechinus nudiventris (Erinaceomorpha - Erinaceidae) Madras Hedgehog Crocidura andamanensis (Soricomorpha - Soricidae) Miller’s Andaman Spiny Shrew Crocidura hispida (Soricomorpha - Soricidae) Andaman Spiny Shrew Crocidura jenkinsi (Soricomorpha - Soricidae) Jenkin’s Andaman Spiny Shrew Crocidura nicobarica (Soricomorpha - Soricidae) Nicobar Shrew Suncus dayi (Soricomorpha - Soricidae) Day’s Shrew Bird Species: Few endemic birds of India are Megapodius nicobariensis (Megapodiidae) Nicobar Megapode Gallus sonneratii (Phasianidae) Grey Junglefowl Orphrysia superciliosa X? (Phasianidae) Himalayan Quail Perdicula argoondah (Phasianidae) Rock Bush Quail Perdicula erythrorhyncha (Phasianidae) Painted Bush Quail Rhodonessa caryophyllacea X? (Anatidae) Pink-headed Duck Accipiter butleri (Accipitridae) Nicobar Sparrowhawk Spilornis elgeni (Accipitridae) Andaman Serpent Eagle Ardeotis nigriceps (Otidae) Great Indian Bustard Rallina canningi (Rallidae) Andaman Crake Rhinoptilus bitorquatus (Glareolidae) Jerdon’s Courser Columba elphinstonii (Columbidae) Nilgiri Woodpigeon Columba palumboides (Columbidae) Andaman Woodpigeon

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Environmental Chemistry

Macropygia rufipennis (Columbidae) Andaman Cuckoo-Dove Psittacula caniceps (Psittacidae) Nicobar Parakeet Psittacula columboides (Psittacidae) Malabar Parakeet Heteroglaux blewitti (Strigidae) Forest Owlet Ninox affinis (Strigidae) Andaman Hawk-Owl Otus alius (Strigidae) Nicobar Scops Owl Reptile Species: Few endemic reptiles are Amphiesma pealii (Squamata Ophidia - Colubridae) Assam Keelback Amphiesma xenura (Squamata Ophidia - Colubridae) Wall’s Keelback Boiga andamanensis (Squamata Ophidia - Colubridae) Andaman Cat Snake Boiga dightoni (Squamata Ophidia - Colubridae) Travancore Cat Snake Boiga wallachi (Squamata Ophidia - Colubridae) Nicobar Cat Snake Coluber bholanathi (Squamata Ophidia - Colubridae) Sharma’s Racer Coluber gracilis (Squamata Ophidia - Colubridae) Graceful Racer Coluber vittacaudatus (Squamata Ophidia - Colubridae) Coronella brachyura (Squamata Ophidia - Colubridae) Indian Smooth Snake Dendrelaphis grandoculis (Squamata Ophidia - Colubridae) Largeeyed Bronzeback Dendrelaphis humayuni (Squamata Ophidia - Colubridae) Tiwar’s Bronzeback Dinodon gammiei (Squamata Ophidia - Colubridae) Sikkim False Wolf Snake Gongylosoma nicobariensis (Squamata Ophidia - Colubridae) Canorta Island Stripe-necked Snake Lycodon flavomaculatus (Squamata Ophidia - Colubridae) Yellowspotted Wolf Snake Lycodon mackinnoni (Squamata Ophidia - Colubridae) Mackinnon’s Wolf Snake Lycodon tiwarii (Squamata Ophidia - Colubridae) Andaman Wolf Snake

Biodiversity and its Conservation

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Oligodon affinis (Squamata Ophidia - Colubridae) Western Kukri Snake Oligodon brevicauda (Squamata Ophidia - Colubridae) Shorthead Kukri Snake Oligodon erythrorhachis (Squamata Ophidia - Colubridae) Red-striped Kukri Snake Oligodon juglandifer (Squamata Ophidia - Colubridae) Darjeeling Kukri Snake Oligodon melaneus (Squamata Ophidia - Colubridae) Bluebelly Kukri Snake Oligodon melanozonatus (Squamata Ophidia - Colubridae) Abor Hills Kukri Snake Oligodon nikhili (Squamata Ophidia - Colubridae) Palni Hills Kukri Snake Oligodon travancoricus (Squamata Ophidia - Colubridae) Travancore Kukri Snake Oligodon venustus (Squamata Ophidia - Colubridae) Jerdon’s Kukri Snake Oligodon woodmasoni (Squamata Ophidia - Colubridae) Yellowstriped Kukri Snake Psammophis longifrons (Squamata Ophidia - Colubridae) Long Sand Racer

Some Endemic Plants of India Few endemic plants of India are as follows Calacanthus 1 spp. (Acanthaceae) Cynarospermum 1 spp. (Acanthaceae) Haplanthodes 4 spp. (Acanthaceae) Indobanalia 1 spp. (Amaranthaceae) Decalepis 4 spp. (Apocynaceae) Seshagiria 1 spp. (Apocynaceae) Anaphyllum 2 spp. (Araceae) Ivanjohnstonia 1 spp. (Boraginaceae) Haplothismia 1 spp. (Burmanniaceae) Nicobariodendron 1 spp. (Celastraceae) Adenoon 1 spp. (Compositae) Lamprachaenium 1 spp. (Compositae)

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Environmental Chemistry

Leucoblepharis 1 spp. (Compositae) Nanothamnus 1 spp. (Compositae) Sphyranthera 2 spp. (Euphorbiaceae) Jerdonia 1 spp. (Gesneriaceae) Bhidea 3 spp. (Gramineae) Chandrasekharania 1 spp. (Gramineae) Danthonidium 1 spp. (Gramineae) Glyphochloa 8 spp. (Gramineae) Hubbardia 1 spp. (Gramineae) Indopoa 1 spp. (Gramineae) Limnopoa 1 spp. (Gramineae) Lophopogon 2 spp. (Gramineae) Pogonachne 1 spp. (Gramineae) Pseudodanthonia 1 spp. (Gramineae) Silentvalleya 1 spp. (Gramineae) Trilobachne 1 spp. (Gramineae) Triplopogon 1 spp. (Gramineae) Poeciloneuron 2 spp. (Guttiferae) Hardwickia 1 spp. (Leguminosae) Moullava 1 spp. (Leguminosae) Bythophyton 1 spp. (Linderniaceae) Helicanthes 1 spp. (Loranthaceae) Erinocarpus 1 spp. (Malvaceae) Meteoromyrtus 1 spp. (Myrtaceae) Aenhenrya 1 spp. (Orchidaceae)

Conservation of Biodiversity Biodiversity is the degree of variation of life forms within a given species, ecosystem, biome, or planet. Terrestrial biodiversity tends to be highest at low latitudes near the equator which seems to be the result of the warm climate and high primary productivity. Marine biodiversity tends to be highest along coasts in the Western Pacific, where sea surface temperature is highest and in mid-latitudinal band in all oceans. Biodiversity generally tends to cluster in hotspots, and has been increasing through time but will be likely to slow in the future.

Biodiversity and its Conservation

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“Biodiversity conservation altogether means that how we conserve, save and make good use of living beings keeping in mind the benefit of every life form on earth”. Earlier analysis has revealed that among Indian orchids, a greater proportion of species occupying terrestrial habitat are endangered than the epiphytic species and rare orchid’s species differ in their flowering phenology compared to the common ones. In the past, most extinction was due to natural causes. In fact, extinction is a naturally occurring phenomenon at a rate of roughly one to five species per year; however, scientists currently believe that habitats across the globe are losing dozens of species each day. Endangered species - plants and animals in imminent danger of extinction - remain the focus of many national and international conservation programs, particularly “charismatic mega fauna” such as African lions, Siberian tigers, and panda bears. The World Conservation Union (IUCN) maintains a “Red List” of endangered species around the world where species are categorised as extinct, extinct in the wild, critically endangered, endangered, vulnerable, or near threatened. As of September 2007, 41,415 species appear on the IUCN Red List and 16,306 of them are threatened with extinction.

International Union for Conservation of Nature (IUCN) The International Union for Conservation of Nature is the world’s oldest and largest global environmental organisation.

IUCN at a Glance • Founded in 1948 as the world’s first global environmental organisation. • Today the largest professional global conservation network. • A leading authority on the environment and sustainable development. • More than 1,200 member organisations including 200+ government and 900+ non-government organisations. • Almost 11,000 voluntary scientists and experts, grouped in six Commissions in some 160 countries. • IUCN’s work is supported by over 1,000 staff in 45 offices and hundreds of partners in public, NGO and private sectors around the world. The Union’s headquarters are located in Gland, near Geneva, in Switzerland.

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• A neutral forum for governments, NGOs, scientists, business and local communities to find practical solutions to conservation and development challenges. • Thousands of field projects and activities around the world • Governance by a Council elected by member organizations every four years at the IUCN World Conservation Congress. • Funded by governments, bilateral and multilateral agencies, foundations, member organisations and corporations. • Official Observer Status at the United Nations General Assembly.

What does IUCN Do? Conserving biodiversity is central to the mission of IUCN. We demonstrate how biodiversity is fundamental to addressing some of the world’s greatest challenges such as climate change, sustainable development and food security. To deliver conservation and sustainability at both the global and local level, IUCN builds on its strengths in the following areas: • Science – 11,000 experts setting global standards in their fields, for example, the definitive international standard for species extinction risk – the IUCN Red List of Threatened Species. • Action – hundreds of conservation projects all over the world from the local level to those involving several countries, all aimed at the sustainable management of biodiversity and natural resources. • Influence – through the collective strength of more than 1,200 government and non-governmental Member organisations, IUCN influences international environmental conventions, policies and laws.

IUCN Red List Objectives Red data book or red list is a catalogue of taxa that are facing the risk of extinction. The main objectives are: 1. Identification and documentation of endangered species. 2. Providing a global index of the decline of biodiversity. 3. Developing awareness about the importance of threatened biodiversity.

Biodiversity and its Conservation

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4. Defining conservation priorities at the local level and guiding conservation action.

Method of Biodiversity Conservation Biodiversity, or biological diversity, is the variety of all species on earth. It is the different plants, animals and micro-organisms, their genes, and the terrestrial, marine and freshwater ecosystems of which they are a part (Fig. 3.11). Biodiversity is essential both for our existence and intrinsically valuable in its own right. This is because biodiversity provides the fundamental building blocks for the many goods and services a healthy environment provides. These include things that are fundamental to our health, like clean air, fresh water and food products, as well as the many other products such as timber and fibre. Other important services provided by our biodiversity include recreational, cultural and spiritual nourishment that maintain our personal and social wellbeing. Looking after our biodiversity is therefore an important task for all people. The process of protecting an endangered plant or animal species in its natural be process of protecting an endangered plant or animal species in In-situ Conservation:

Fig. 3.11

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Environmental Chemistry

The in-situ conservation strategies stress on protection of total ecosystems through a network of protected areas. It involves the creation of protected areas such as national parks, nature parks, reserves, wetlands protection zones, SPZ (Special Protection Zones), SCZ (Special Conservation Zones) and other types of protected areas.

PROTECTED AREAS To facilitate the growth and reproduction of plants and animals in their habitat, the area is protected by restricting human activities like hunting, firewood collection, timber harvesting etc. Today, there are about 37,000 protected areas, parks, sanctuaries and biosphere reserves all around the world.

The Role of Protected Areas in Maintaining Biodiversity A protected area is a geographically defined area that is designated or regulated and managed to achieve specific conservation objectives. It may be set aside for the protection of biological diversity, and of natural and associated cultural resources and is managed through legal or other effective means. This includes national parks and nature reserves, sustainable use reserves, wilderness areas and heritage sites Protected areas (Pas) have been widely used as a conservation tool in order to maintain a representative sample of unaltered species and eco-systems for the future, and to limit the potential for environmental degradation through human mismanagement of resources. At present, approximately 8,500 Protected areas exist throughout the world in 169 countries and covers about 750 million hectares of marine and terrestrial ecosystems, which amounts to 5.2% of the Earth’s land surface. The World Conservation Union (IUCN) has a key role in promoting the establishment of protected areas throughout the world. Since 1948, IUCN has developed standards and a proper guidelines for protected area management. Protected areas have been established following the categories defined by the IUCN. (It should be noted that strict protection categories (categories I – III) have mostly been applied in the developing countries, whereas categories V and VI are the most commonly used in the developed world).

Biodiversity and its Conservation

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Category I Strict Protection: Sometimes called strict nature reserve/ wilderness areas. Protected areas managed mainly for science or wilderness protection. Generally smaller areas where the preservation of important natural values with minimum human disturbance are emphasized. Category II Ecosystem Conservation and Tourism: Sometimes called national parks. Generally larger areas with a range of outstanding features and ecosystems that people may visit for education, recreation, and inspiration as long as they do not threaten the area’s values. Category III Conservation of Natural Features: Also called natural monuments. These are Similar to National Parks, but usually smaller areas protecting a single spectacular natural feature or historic site. Category IV Conservation through Active Management: Sometimes called habitat and wildlife (species) management areas. Areas managed to protect and utilise wildlife species. Category V Landscape/Seascape Conservation and Recreation: Sometimes called protected landscapes/seascapes. Category VI Sustainable Use of Natural Ecosystems: Sometimes called managed resource protected areas. Protected areas managed mainly for the sustainable use of natural ecosystems. In the past, it was assumed that the best way to preserve biodiversity was to conserve it through protected areas by reducing human activities or completely excluding humans. Population growth and poverty were seen as main causes of environmental degradation; people were regarded as a problem from which the environment needed protecting. Accordingly, protected areas and parks were fenced-off from local people, traditional practices were prohibited, and people were held under penalties of fines or imprisonments for utilising park resources. However, there are very controversial scientific and social problems with this approach, which was characterised by serious conflicts between local communities and the state. India has over 600 protected areas, which includes over 90 national parks, over 500 animal sanctuaries and 15 biosphere reserves. Protected areas contain maximum biological diversity. NATIONAL PARKS It is an protected area which is strictly reserved for the conservation/ betterment of the wildlife and where activities like forestry, grazing and cultivation are not permitted.

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Environmental Chemistry

Their boundaries are well marked and circumscribed. They are usually small reserves spreading in an area of 100 sq.km to 500 sq.km. In national parks, the emphasis is on the preservation of a single plant or animal species. National parks in India are IUCN category II protected areas. India’s first national park was established in 1936 as Indian National Park, now known as Jim Corbett National Park. By 1970, India only had five national parks. In 1972, India enacted the Wildlife Protection Act and Project Tiger to safeguard the habitats of conservation reliant species. Further federal legislation strengthening protections for wildlife was introduced in the 1980s. As of April 2012, there were 102 national parks. All national park lands then encompassed a total 39,919 km2 (15,413 sq.km) km², comprising 1.21% of India’s total surface area. Table 3.5 List of national parks in India No

Name

State

Established

Area (in km²)

Famous For

1. Anshi National Park

Karnataka

2013

250

Bengal tigers, Black panthers and Indian elephants, amongst other distinctive fauna.

2. Balphakram National Park

Meghalaya

2013

220

Wild water buffalo, Bubalus arnee, Red panda, Elephant, Eight species of Cats, ranging from Tiger to Marbled cat

3. Bandhavgarh National Park

Madhya Pradesh

2013

448.85

4. Bandipur National Park

Karnataka

1974

874.20

5. Bannerghatta National Park

Karnataka

1974

106.27

6. Vansda National Park

Gujarat

1979

23.99

7. Betla National Park

Jharkhand

1986

231.67

8. Bhitarkanika National Park

Odisha

1988

145

9. Blackbuck National Park, Velavadar

Gujarat

1976

34.08

Table Contd.

Biodiversity and its Conservation

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Table Contd.

10. Buxa Tiger Reserve

West Bengal

1992

117.10

11. Campbell Bay National Park

Andaman and Nicobar Islands

1992

426.23

12. Chandoli National Park

Maharashtra

2004

317.67

13. Jim Corbett National Park

Uttarakhand

1936

1318.5

14. Dachigam National Park

Jammu and Kashmir

1981

141

15. Darrah National Park

Rajasthan

2004

250

16. Desert National Park

Rajasthan

1980

3162

17. Dibru-Saikhowa National Park

Assam

1999

340

18. Dudhwa National Park

Uttar Pradesh

1977

490.29

19. Eravikulam National Park

Kerala

1978

97

20. Mandla Plant Fossils National Park

Madhya Pradesh

1983

0.27

21. Galathea National Park

Andaman and Nicobar Islands

1992

110

22. Gangotri National Park

Uttarakhand

1989

1552.73

23. Gir Forest National Park

Gujarat

1965

258.71

24. Gorumara National Park

West Bengal

1994

79.45

25. Govind Pashu Vihar Wildlife Sanctuary

Uttarakhand

1990

472.08

26. Great Himalayan National Park

Himachal Pradesh

1984

754.40

27. Gugamal National Park

Maharashtra

1987

361.28

28. Guindy National Park

Tamil Nadu

1976

2.82

Famous for the only living area of Kashmir Stag (the deer of Kashmir )

Table Contd.

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Environmental Chemistry

Table Contd.

29. Marine National Park, Gulf of Kutch

Gujarat

1980

162.89

30. Gulf of Mannar Marine National Park

Tamil Nadu

1980

6.23

31. Hemis National Park

Jammu and Kashmir

1981

4400

32. Harike Wetland

Punjab

1987

86

33. Hazaribagh National Jharkhand Park

1954

183.89

34. Indira Gandhi Wildlife Sanctuary and National Park

Tamil Nadu

1989

117.10

35. Indravati National Park

Chhattisgarh

1981

1258.37

36. Jaldapara National Park

West Bengal

2012

216

37. Ntangki National Park

Nagaland

1993

202.02

38. Kalesar National Park

Haryana

2003

100.88

39. Kanha National Park

Madhya Pradesh

1955

940

40. Kanger Ghati National Park

Chhattisgarh

1982

200

41. Kasu Brahmananda Reddy National Park

Andhra Pradesh

1994

1.42

42. Kaziranga National Park

Assam

1905

471.71

43. Keibul Lamjao National Park

Manipur

1977

40

44. Keoladeo National Park

Rajasthan

1981

28.73

45. Khangchendzonga National Park

Sikkim

1977

1784

46. Kishtwar National Park

Jammu and Kashmir

1981

400

47. Kudremukh National Karnataka Park

1987

600.32

48. Madhav National Park

1959

375.22

Madhya Pradesh

Famous for the Indian Rhinoceros

Table Contd.

Biodiversity and its Conservation

3.55

Table Contd.

49. Mahatma Gandhi Marine National Park

Andaman and Nicobar Islands

1983

281.50

50. Mahavir Harina Vanasthali National Park

Andhra Pradesh

1994

14.59

51. Manas National Park

Assam

1990

500

52. Mathikettan Shola National Park

Kerala

2003

12.82

53. Middle Button Andaman Island National Park and Nicobar Islands

1987

0.64

54. Mollem National Park

Goa

1978

107

55. Mouling National Park

Arunachal Pradesh

1986

483

56. Mount Abu Wildlife Sanctuary

Rajasthan

1960

288.84

57. Mount Harriet National Park

Andaman and Nicobar Islands

58. Mrugavani National Park

Andhra Pradesh

59. Mudumalai National Park

Tamil Nadu

1940

321.55

60. Mukurthi National Park

Tamil Nadu

2001

78.46

61. Murlen National Park

Mizoram

62. Namdapha National Park

Arunachal Pradesh

1974

1985.24

63. Nameri National Park

Assam

1978

137.07

64. Nanda Devi National Park

Uttarakhand

1982

630.33

65. Nandankanan Zoological Park

Odisha

1659

4.006

66. Navegaon National Park

Maharashtra

67. Neora Valley National Park

West Bengal

46.62

3.5

200

133.88 1986

88 Table Contd.

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Environmental Chemistry

Table Contd.

68. Nokrek National Park

Meghalaya

69. North Button Island National Park

Andaman and Nicobar Islands

70. Orang National Park Assam

47.48 1979

144

1999

78.81

71. Palani Hills National Park

Tamil Nadu

736.87

72. Panna National Park

Madhya Pradesh

1981

542.67

73. Pench National Park Madhya Pradesh

1977

758

74. Periyar National Park

Kerala

1982

305

75. Phawngpui Blue Mountain National Park

Mizoram

1992

50

76. Pin Valley National Park

Himachal Pradesh

1987

807.36

77. Rajaji National Park

Uttarakhand

1983

820

78. Nagarhole National Park

Karnataka

1988

643.39

79. Rani Jhansi Marine National Park

Andaman and Nicobar Islands

1996

256.14

80. Ranthambore National Park

Rajasthan

1981

392

81. Saddle Peak National Park

Andaman and Nicobar Islands

32.55

82. Salim Ali National Park

Jammu and Kashmir

9.07

83. Sanjay National Park²

Madhya Pradesh

1981

466.7

84. Sanjay Gandhi National Park

Maharashtra

1969

104

85. Sariska Tiger Reserve

Rajasthan

1955

866

86. Satpura National Park

Madhya Pradesh

1981

524

87. Silent Valley National Park

Kerala

1980

237 Table Contd.

Biodiversity and its Conservation

3.57

Table Contd.

88. Sirohi National Park

Manipur

1982

41.30

89. Simlipal National Park

Odisha

1980

845.70

90. Singalila National Park

West Bengal

1986

78.60

91. South Button Island National Park

Andaman and Nicobar Islands

92. Sri Venkateswara National Park

Andhra Pradesh

1989

353

93. Sultanpur National Park

Haryana

1989

1.43

94. Sundarbans National Park

West Bengal

1984

1330.12

95. Tadoba National Park

Maharashtra

1955

625

96. Valley of Flowers National Park

Uttarakhand

1982

87.50

97. Valmiki National Park

Bihar

98. Papikonda National Park

Andhra Pradesh

5

461.6 2008

1012.85

WILDLIFE SANCTUARIES It is an protected area which is reserved for the conservation of only animals and human activities like harvesting of timber, collection of minor forest products are allowed to a certain extent. Boundaries of sanctuaries are not well defined and controlled biotic interference is permitted e.g., tourist activity. India has over 442 animal sanctuaries, referred to as Wildlife sanctuaries (IUCN Category IV Protected Area). Among these, the 41 Tiger Reserves are governed by Project Tiger, and are of special significance in the conservation of the tiger. Some wildlife sanctuaries are specifically named Bird Sanctuary, e.g., Keoladeo National Park before attaining National Park status. Many National Parks were initially Wildlife Sanctuaries. Wildlife sanctuaries are of national importance to conservation, usually due to some flagship faunal species, are named National Wildlife Sanctuary, like the tri-state National Chambal (Gharial) Wildlife Sanctuary for conserving the gharial.

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BIOSPHERE RESERVES It is a special category of protected areas where human population also forms a part of the system. They are large protected area of usually more than 5000 sq.km. A biosphere reserves has 3 parts—core, buffer and transition zone. 1 The core zone is innermost zone, which is undisturbed and legally protected area. 2 Buffer zone lies b/w the core and transition zone. Some research and educational activities are permitted here. 3 Transition zone is the outermost part of biosphere reserves. Here cropping, forestry, recreation, fishery and other activities are allowed. Main Functions of Biosphere Reserves (1) Conservation To ensure the conservation of ecosystem, species and genetic resources. (2) Development To promote economic development while maintaining cultural, social and ecological identity. (3) Scientific Research To provide support for research related to monitoring and education, local, national and global issues. The principal aims of in situ conservation include: • The creation of protected areas • The promotion of sustainable management of the territory • The protection and restoration of degraded areas • The development of strategies for the conservation of marine environments • The integration of conservation and biodiversity into agricultural, marine, wildlife and urban development policy • The creation of natural corridors linking areas of biological interest to prevent further habitat fragmentation (nature 2000 network) • The introduction of legislation • Information, education and raised awareness • Vocational reconversion (e.g. Poachers become wardens) • The involvement of neighboring communities • The employment of local resources (especially human)

Biodiversity and its Conservation

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Ex-situ Conservation Ex-situ conservation is the preservation of components of biological diversity outside their natural habitats. This involves conservation of genetic resources, as well as wild and cultivated or species, and draws on a diverse body of techniques and facilities. Some of these include: • Gene banks, e.g., seed banks, sperm and ova banks, field banks; • In vitro plant tissue and microbial culture collections; • Captive breeding of animals and artificial propagation of plants, with possible reintroduction into the wild; and • Collecting living organisms for zoos, aquaria, and botanic gardens for research and public awareness. Ex-situ conservation measures can be complementary to in-situ methods as they provide an “insurance policy” against extinction. These measures also have a valuable role to play in recovery programmes for endangered species. The Kew Seed Bank in England has 1.5% of the world’s flora - about 4,000 species - on deposit. In agriculture, ex-situ conservation measures maintain domesticated plants which cannot survive in nature unaided. Ex-situ conservation provides excellent research opportunities on the components of biological diversity. Some of these institutions also play a central role in public education and awareness raising by bringing members of the public into contact with plants and animals they may not normally come in contact with. It is estimated that worldwide, over 600 million people visit zoos every year. 1. Use of Seed Bank, Gene Banks or Germplasm Some seeds show variable periods of dormancy. Most of seed plants therefore can be preserved in the form of their seeds in small packets for long durations. Places where seeds are stored are called seed banks or gene banks or sometimes germplasm banks. Term germplasm refers to any of plant organ or its part(living) from which new plants can be generated. They utilise the technique of cryopreservation in liquid nitrogen at a temperature of – 196 degree Celsius.

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2. Animal Translocations It is release of animals in a new locality. Translocation is carried in following cases: 1. when a species on which an animal is dependent becomes rare. 2. when a species is endemic or restricted to a particular area. 3. Due to habit destruction and unfavorable environment conditions. 4. Increase in population in an area.

3. Botanical Gardens A botanical garden is a place where flowers, fruits and vegetables are grown. The botanical gardens provide beauty and calm environment. Most of them have started keeping exotic plants for educational and research purposes. Many rare and endangered plants lives in botanical garden which have taken task of conservation of plants in a real sense. In India, the 1st botanical garden was established in Mumbai in 1830 by agricultural society and in 1838 one more garden was established in Chennai. Some Botanical gardens of India: Lloyd botanical garden at Darjeeling, Indian botanical garden at Calcutta, National Botanical garden at Lucknow etc.

4. Zoological Gardens or Zoos In Zoos, wild animals are maintained in captivity. Conservation of wild animals species which are rare and endangered. The oldest zoo, the Schonbrumm zoo which exists today also, was established in Vienna in 1759. The first Indian Zoo was set up by Raja Rajendra Mullick Bahadur at marble palace in Calcutta(1854).

CHAPTER

4 Natural Resources: Problems and Prospects

INTRODUCTION Natural resources (also called land or raw materials) occur naturally within environments that exist relatively undisturbed by mankind, in a natural form. Natural resources are derived from the environment. Many of them are essential for our survival while others are used for satisfying our wants. Natural resources may be further classified in different ways. On the basis of origin, resources may be divided into: • Biotic resources – obtained from the biosphere (forests and their products, animals, birds and their products, fish and other marine organisms; mineral fuels (coal, petroleum) are also included in this category because they were formed from decayed organic matter; • Abiotic resources – non-living things (land, water, air, ores). With respect to renewability, natural resources may be divided into: • Non-renewable resources – are formed over long geological periods (minerals and fossil fuels). Their rate of formation is extremely slow, so they cannot be replenished once they get depleted. Metallic minerals can be reused by recycling them. But coal, petroleum and natural gas cannot be recycled. • Renewable resources – can be replenished or reproduced easily, at a rate comparable or faster than its rate of consumption by humans. Some of them (sunlight, air, wind, tides and hydroelectricity) are continuously available and their quantity is not affected by human consumption. They have also been named perpetual resources. Many renewable resources can be depleted by human use, but may also be replenished. Some (agricultural crops) take a short time for renewal, others (water, forests) take a comparatively long time. Renewable resources may also mean

4.2

Environmental Chemistry

commodities such as wood, paper and leather, if harvesting is performed in a sustainable manner. Some natural renewable resources such as geothermal power, freshwater, timber, oxygen and biomass must be carefully managed to avoid exceeding the world’s capacity to replenish them. Natural resources such as land, water, soil, plants and animals must be carefully managed, with a particular focus on how management affects the quality of life for both present and future generations. Natural resource management is interrelated with the concept of sustainable development, a principle that forms a basis for land management throughout the world, and also with urban planning. Renewable resources can also be lost through pollution. Though water renews itself, if it is polluted, it is no longer useful for human use. Urban sprawl, cultivation, irrigation, grazing, deforestation, fishing, hunting, and habitat destruction can all be causes of the destruction of an otherwise renewable resource. ISSUES WITH NATURAL RESOURCES • Natural resources can be depleted, or used to a point that they are no longer available. • Conservation measures are necessary for nonrenewable resources because they are known to be in a non-replenishing supply. • Even though renewable resources can be replaced/reused, if they are used faster than they can be replaced, they can also become depleted. • Soil that is lost because it is left bare of vegetation and allowed to erode depletes the land of the fertile topsoil needed for plant growth in that area. • Depletion of freshwater in an area caused by increased demand by the population living there, by wasteful use of the water, or by pollution, can result in water not being available in needed quantities or being unfit for natural use. • Depletion of a living resource, such as trees being removed without being replanted, can contribute to environmental changes in the land, air and water in that area. • As the number of people on Earth increase, the need for natural resources increases; therefore, it is necessary for people to

Natural Resources: Problems and Prospects

4.3

reduce, reuse, and recycle to prevent the depletion of these natural resources. WAYS TO CONSERVE NATURAL RESOURCES 1. Reducing-involves making a decision to not use a resource when there is an alternative, such as walking or riding a bicycle rather than travelling in a car. 2. Reusing-involves finding a way to use a resource (or product from a resource) again without changing it or reprocessing it, such as washing a drinking glass rather than throwing away plastic or styrofoam. 3. Recycling-involves reprocessing a resource (or product from a resource) so that the materials can be used again as another item, such as metals, glass or plastics being remade into new metals or glass products or into fibers. 4. Protecting-involves preventing the loss of a resource, usually living things, by managing their environment to increase the chances of survival, such as providing wildlife reserves for endangered animals. FOREST RESOURCES

Use and Overexploitation of Forests Resources A forest is a complex ecosystem which is predominantly composed of trees, shrubs and is usually a closed canopy. Forests are storehouses of a large variety of life forms such as plants, mammals, birds, insects and reptiles etc. Also the forests have abundant microorganisms and fungi, which do the important work of decomposing dead organic matter thereby enriching the soil. Nearly billion hectares of forest cover the earth’s surface, roughly 30% of its total land area Plants include the trees, shrubs, climbers, grasses and herbs in the forest. Depending on the physical, geographical, climatic and ecological factors, there are different types of forest like evergreen forest (mainly composed of evergreen tree species i.e., species having leaves all throughout the year) and deciduous forest (mainly composed of deciduous tree species i.e., species having leaf-fall during particular months of the year). The term forest implies ‘natural vegetation’ of the area, existing from thousands of years and supporting a variety of biodiversity, forming a complex ecosystem.

4.4

Environmental Chemistry

Forests are ecological as well as a socio-economic resource. Forests have to be managed judiciously not only because they are source of various products and industrial raw materials but also for environmental protection and various services they provide. Approximately 1/3rd of the earth’s total land area is covered by forests. The forests provide habitat for wildlife, resources such as timber, fire wood, drugs etc., and aesthetic environment. Indirectly, the forests benefit people by protecting watersheds from soil erosion, keeping rivers and reservoirs free of silt, and facilitate the recharging of groundwater. Forest plays an important role in the cycling of carbon, water, nitrogen and other elements. Forests are classified according to their nature and composition, the type of climate in which they thrive, and its relationship with the surrounding environment. India has a many types of forests. They range from rain forest of Kerala and North-east to deciduous forests in the plains, mountain forests to alpine pastures of Ladakh and deserts of Rajasthan. Forests in India can be broadly divided into coniferous forests and broadleaved forests They can also be classified according to the nature of their tree species-evergreen, deciduous, xerophytes or thorn trees, mangroves etc. They can also be classified according to the most abundant species of trees, such as Sal or Teak forests. In many cases, a forest is named after the first three or four most abundant tree species. Coniferous forests grow in the Himalayan mountain region, where the temperatures are low. These forests have tall stately trees with needle-like leaves and downward-sloping branches, so that the snow can slip off the branches. Broad-leaved forests are of several types, such as evergreen forests, deciduous forests, thorn forests, and mangrove forests. Broad-leaved trees usually have large leaves of various shapes and are found in middle to lower latitude. Evergreen forests grow in the high rainfall areas of the Western Ghats, North-eastern India and the Andaman and Nicobar Islands. These forests grow in areas where the monsoon period lasts for several months. Deciduous forests are found in regions with a moderate amount of seasonal rainfall that lasts for only a few months. Most of the forests in which Teak trees grow are of this type. The deciduous trees shed their leaves during the winter and hot summer months.

Natural Resources: Problems and Prospects

4.5

Thorn forests are found in the semi-arid regions of India. The trees, which are sparsely distributed, are surrounded by open grassy areas. Mangroves forests grow along the coast especially in the river deltas. These plants are uniquely adapted to be able to grow in a mix of saline and freshwater. They grow luxuriantly in muddy areas covered with silt that the rivers have brought down. The mangrove trees have breathing roots that emerge from the mud banks. Forest cover includes all lands which have a tree canopy density of 10% and above with area 1 ha or more (Fig. 4.1). • Very Dense Forest: All lands with tree cover of canopy density of 70% and above. • Moderately Dense Forest: All lands with tree cover of canopy density between 40% and 70% • Open Forest: All lands with tree cover of canopy density between 10% and 40% • Scrub: Degraded forest lands with canopy density less than 10%. • Non-forest: Any area not included in the above classes.

Fig. 4.1 Total Forest Cover in India

Uses of Forest Forests play an important role in maintaining ecological balance and contributes to economy also. (i) Forests are natural habitats of plants and animals. (ii) Forests help to maintain ecological balance. (iii) Forests help to control climate and rainfall.

4.6

Environmental Chemistry

(iv) (v) (vi) (vii)

(vii) (viii) (xi) (x)

(xii) (xii) (xiii) (xiv) (xv) (xvi) (xvii)

(xviii) (xix)

Forests help to maintain the oxygen – carbon dioxide balance in nature. Forests provide an environment for many species of plants and animals thus protects and sustains the diversity of nature. Plants reduce soil erosion. Roots help to hold the soil in place They provide shade which prevents the soil to become too dry. Thus increases the soil moisture holding capacity. It controls floods. Plants clean the air, cool it on hot days, conserve heat at night, and act as excellent sound absorbers. They help in groundwater recharge. Dead plants decompose to form humus, organic matter that holds the water and provides nutrients to the soil. Through the process of photosynthesis, forests renew the oxygen supply in the atmosphere by absorbing atmospheric CO2 and moderating the greenhouse effect. Forest play an important role in maintaining water cycle of the area. Forests absorb suspended particles in air thereby reducing pollution. Forests also helps in the process of soil formation by causing weathering of rock. People living in and around forests depend on forests for their livelihood. Industrialists who use the raw materials from forests for manufacturing paper, medicines, furniture etc. It provides valuable items like timber, paper, fuel wood, bamboo, cane, food, fibers and essential oils. Forest plants provide hundreds of medicinal plants, spices, poisons, insecticides, soap substitutes like ritha and shikakai, tendu leaves used in bidi wrapping. Forests also provide fodder for cattle and other grazing animals. Forests are also popular areas for relaxation and recreation and they add to the aesthetic value of the area.

Natural Resources: Problems and Prospects

4.7

Overexploitation of Forest Resources The practice of overexploitation of forest resources has been increasingly observed in the Indian contemporary social scenario. The environmental degradation resulting from overexploitation of forest resources has been affecting the life of communities, both human and plants, ecological imbalance, and finally causing resource crunch. The problem is quite severe in North-eastern region, Himachal Pradesh and Jammu and Kashmir. Lot of transhumance activity of migratory cattle and local biotic pressures for food, fuel wood, fodder, which had resulted in deduction of forests. The causes of overexploitation of forest resources as well as the threatening process to the environment are briefly summarised below: Habitat loss: It is primarily because of human induced activities Agriculture: Shifting agriculture, livestock rearing, grazing, cropplantations. Extraction: Mining, fisheries, timber, harvesting, harvesting of nonwoody vegetation. Development: Industry, human settlement, tourism, infrastructure development (roads, dams) Unspecified causes: Fragmentation, deforestation, drainage, replacement by ground waste. Hunting and Collecting: Food support, cultural uses, medicinal plants. Trade (legal): Food commodities, traditional medicines. Accidental: Trapping, hooking, netting, poisoning. Natural disasters: Volcanoes, drought, floods. Wild fire: Intentional, unintentional and natural. Others: Land and water pollution, global warming, acid rains, ozone hole effect. DEFORESTATION Deforestation is a very broad term, which consists of cutting of trees including repeated lopping, felling, and removal of forest litter, browsing, grazing and trampling of seedlings. It can also be defined as the removal or damage of vegetation in a forest to the extent that it no longer supports its natural flora and fauna.

4.8

Environmental Chemistry

Deforestation refers to the loss of tree cover; land that is permanently converted from forest to non-forest uses such as agricultural pasture, desert, and human settlement. In the beginning of 20th century about 7.0 billion hectares of forests were present over the land of our planet and by 1950 forest covers was reduced to about 4.8 billon. If the present trend continues forests will be reduced to only 2.35 billion ha hectares in 2000 A.D. CAUSES OF DEFORESTATION The most common reason for deforestation is cutting of wood for fuel, lumber and paper. Another important cause relates to the clearing of forest land for agriculture, including conversion to crop land and pasture (Fig. 4.2).

Fig. 4.2 Causes of Deforestation

The main causes of deforestation are: • Agriculture; • Shifting cultivation; • Demand for firewood; • Demand of wood for industry and commercial purposes; • Urbanisation and developmental projects and • Other causes.

Natural Resources: Problems and Prospects

4.9

1. Agriculture The expanding agriculture is one of the most important causes of deforestation. As demands for agricultural products rises, more and more land is brought under cultivation and for that more forests are cleared, grasslands and even marshes, and lands under water are reclaimed.

2. Demand for Firewood Firewood has been used as a source of energy for cooking, heating etc. Almost 44% of the total global wood produced fulfils the fuel requirements of the world. India consumes nearly 135-170 Mt (Million tonnes) of firewood annually and 10-15 ha of forest cover is being stripped-off to meet the minimum fuel needs of urban and rural poor.

3. Wood for Industry and Commercial Use Wood, the versatile forest produce, is used for several industrial purposes, such as making crates, packing cases, furniture, match boxes, wooden boxes, paper and pulp, plywood etc. Unrestricted exploitation of timber as well as other wood products for commercial purposes is the main cause of forest degradation.

4. Urbanisation and Developmental Projects The process of deforestation begins with building of infrastructure in the form of roads, railway lines, building of dams, townships, electric supply etc. Thermal power plants, mining for coal, metal ores and minerals are also important causes of deforestation.

5. Other Causes Forests may sometimes suffer from natural calamities such as overgrazing, floods, forest fires, diseases and termite attack. CONSEQUENCES OF DEFORESTATION Deforestation affects both physical and biological components of the environment. • Soil erosion and flash flood • Climatic change • Loss of biodiversity

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Environmental Chemistry

1. Soil Erosion and Flash Flood A shrinking forest cover coupled with over exploitation of ground water has accelerated erosion along the slopes of the lower Himalayas and Aravali hills, making them prone to landslides. Destruction of the forests has altered rainfall pattern. In 1978 India suffered some of the worst flooding in its history. There was two days of heavy rainfall and 66,000 villages were inundated, 2,000 people drowned, and 40,000 cattle were swept away. Several lives were lost and a huge number of cattle were swept away. Lack of forest cover has resulted in water flowing off the ground, washing away the top soil which is finally deposited as silt in the river beds.

2. Climatic Change Forests enhance local precipitation and improve water holding capacity of soil, regulate water cycle, maintain soil fertility by returning the nutrients to the soil through leaf fall and decomposition of litter. Forests check soil erosion, landslides and reduce intensity of flood and droughts. Forests, being home of wildlife are important assets of aesthetic, touristic and cultural value to the society. Forests have profound effect on the climate. Forest absorbed carbon dioxide from the atmosphere and help in balancing carbon dioxide and oxygen in the atmosphere. The forests play a vital role in maintaining oxygen supply in the air, we breathe. They also play a vital role in the regulation of water (water cycle) in the environment and act as environmental buffers regulating climate and atmospheric humidity. Heat build-up in the atmosphere is one of the important problems of the century known as greenhouse effect is the partly caused by the result from deforestation.

3. Biodiversity Over the past 2000 years, 600 species of animals have become extinct or are going to be extinct from the earth. Similarly, about 3000 species of plants need to be conserved. The shrinkage of green cover has adverse effects on the stability of the ecosystem. Poaching is another factor causing depletion of wildlife. The roll call of victims is endless. In Africa, in recent years, nearly 95% of the black rhino population has been exterminated by poachers for their horns and over one third of Africa’s elephants have been wiped out for ivory. Loss of wildlife in India India has nearly 45,000 species of plants and 75,000 species of animals. This biological diversity ought

Natural Resources: Problems and Prospects

4.11

to be preserved for maintaining stability of ecosystems. Deforestation coupled with desertification has destroyed the natural treasure of the earth to a large extent. The population of elephant, lion and tiger is fast diminishing. ‘Cheetah’ is already extinct. Elephants once found all over India have now disappeared from Andhra Pradesh, Madhya Pradesh and Maharashtra. The Asiatic lion which was very common in Asia has practically vanished from Asia except for a few hundred sq.km (square kilometer) of Gir forest in India. In India four species of mammals and three species of birds have been extinct in the last 100 years. Another 40 species of mammals, 20 species of birds and 12 species of reptiles are considered highly endangered due to overexploitations, of forests. Forests can be conserved by: (i) Afforestation – planting of more trees. (ii) Preventing or reducing deforestation. (iii) Preventing overgrazing by cattle. (iv) By setting up wildlife sanctuaries, national parks, biosphere reserves etc. (v) Undertaking social forestry programs like Van mahotsav, Chipko movement for planting and protecting trees on a large-scale (Fig. 4.3).

Fig. 4.3 Chipko Movement

TIMBER EXTRACTION The chief product that forests supply is wood like timbers. Major forest products consist of timber small wood and fuel wood. Indian forests produce about 5,000 species of wood, of which about 450-species are commercially valuable. Hard woods include important species

4.12

Environmental Chemistry

such as teak, ironwood, mahogany etc. These woods are used for constructional purposes. Population explosion had its tremendous pressure on demand for timber and other wood. Consumption of wood for industrial uses is more in developed countries than the developing countries. India and other tropical countries have particularly abundant timber and heartwood resources. Timber accounts for 25% of all photosynthetic materials produced on the earth and about half of the total biomass produced by a forest. A large number of trees are commercially exploited for timber in different parts of India. Timberbased industries include plywood manufacture, saw milling, paper and pulp, composite wood, matches, man-made fibres, furniture, sports goods, and particle boards. Timber extraction is a significant cause of deforestation in Central Africa and South-eastern Asia. The biggest problem of the Indian forests is the inadequate forest cover. Forests cover only 23.13% of the area against the required coverage of 33%. Major causes responsible for timber famine in Europe in 16th and 17th centuries prevail in these forests too. The major effects of timber extraction on forests and tribal people include: • Poor logging results in a degraded forest. • Soil erosion, especially on slopes. • Sedimentation of irrigation systems. • Floods may be intensified by cutting of trees on upstream. • Loss of biodiversity. • Climatic changes, such as lower precipitation. • Loss of non-timber products and loss of long-term forest productivity on the site affect the subsistence economy of the forest dwellers. • It is a matter of serious concern that the present generation man has forgotten the value of forests. The reckless felling of trees from the very beginning of the present century without caring for environment. MINING It is the extraction of valuable minerals or other geological materials from the earth, usually from an ore body, vein or (coal) seam. Materials

Natural Resources: Problems and Prospects

4.13

recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock salt and potash. There are several negative effects of mining for the environment. 1. Several forests are cleared and this leads to deforestation. 2. Several organisms and animals lose their natural habitat. 3. Loss of biodiversity is lost in this process. 4. It causes a lot of pollution as a lot of chemical waste incurred due to the various processed involved. This waste is released into water bodies, rivers and sea. The major impacts generally encountered in various components of development are summarised below. Land use Removal of vegetation and resettlement of displaced population. There may also be use of the land changes with respect to agriculture, fisheries, recreation sites, housing, forestry areas etc. Landscape Soil erosion, loss of top soil, change in complete geology, creation of huge dumps and voids, disposal of wastes, deforestation etc. Socio-economic Change in employment and income opportunity, infrastructure, community development, communication, transport, educational, commercial, recreational and medical facilities. The major adverse impact, however, is the displacement and rehabilitation/ resettlement of affected people including change in culture, heritage and related features. Hydrology/Water resources Changes in groundwater flow patterns, lowering of water table, changes in the hydrodynamic conditions of river/underground recharge basings, reduction in volumes of subsurface discharge to waterbodies/rivers, disruption and diversion of watercourses/drainages, contamination of waterbodies, affecting the yield of water from borewells and dugwells, land subsidence etc. Water quality Erosion, oil and grease, contamination of waterbodies due to discharge of mine water/effluents, pollution from domestic and sewage effluents, sedimentation of rivers and other stored waterbodies, leachates from wash-off from dumps, solid waste disposal sites, broken rocks, toxic wastes, salinity from mine fires, acid mine drainage etc. Air quality High intensity of dust nuisance problems such as visuals, soiling and degradation of materials etc., and gaseous emissions. Noise and Vibrations Generation of obnoxious levels of noise vibrations.

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Environmental Chemistry

Ecology (flora and fauna) Loss of habitat, biodiversity, rare flora and fauna, fisheries and other aquatic life, migration of wildlife and overall disruption of the ecology of the area. DAMS AND THEIR EFFECTS ON FORESTS AND TRIBAL PEOPLE India is the third largest dam builder country in the world. Now it has over 3600 large dams and over 700 more under construction. Dams are designed to last many decades and so can contribute to the generation of electricity for many years decades. Electricity can be produced at a constant rate. The build up of water in the lake means that energy can be stored until needed, when the water is released to produce electricity. When in use, electricity produced by dam systems do not produce greenhouse gases. They do not pollute the atmosphere. They can be used for irrigation purposes. Often large dams become tourist attractions in their own right. The lake that forms behind the dam can be used for water sports and leisure/pleasure activities. About 4% the world’s population lives in special territories. These indigenous or tribal people have claims on a particular place; they have cultural, spiritual and economic ties with the particular area and in most cases they have ability to manage the area and sustain it. In this way they protect the biodiversity of that particular area and the local culture, including knowledge and resource-management skills of the local community. Practically, large dams are found on all the major rivers of the world, have been criticised for their negative environmental, social and economic consequences. The success of a process known as Compensatory Afforestation, a measure to mitigate the deforestation of 13,000 hectares of forest land, caused by inundation of land by the Sardar Sarovar Dam on the Narmada River in western India. Tribal people and peasants living in or near these forests, traditionally use the forests as an important community resource for firewood, medicinal herbs, forest produce etc. The mitigation process involves tree plantations carried out on 13,000 hectares of land to compensate for the forests lost to flooding. EFFECTS OF DAM ON TRIBAL PEOPLE 1. Construction of big dam leads to the displacement of tribal people. 2. Displacement and cultural change affects the tribal people both mentally and physically.

Natural Resources: Problems and Prospects

4.15

3. They do not accommodate the modern food habits and lifestyle. 4. Tribal people are ill treated by the contractors. 5. Many of the displaced people were not recognised and resettled. or 6. The Physical condition of tribal people will not suit with new areas and hence they will be affected by various diseases. WATER RESOURCES The water available to us on earth today is no different in quantity from what were available thousands of years ago. A fundamental nature need to be kept in mind, as that water in all its forms snow, rain, soil moisture, glaciers, rivers, lakes, other surface water bodies, and groundwater constitutes a unity. The other is that there is a finite quantity of water on earth, and this is neither added to nor destroyed. Right now, we have limited sources of water. We cannot create new water, and whatever quantity is used up in any manner reappears though perhaps not always in a re-usable form. Current Situation • 20% of the world’s population do not have access to safe drinking water. • 40% do not have sufficient water for adequate living and hygiene. • More than 2.2 million people die each year from diseases related to contaminated drinking water. • By 2050, water scarcity will affect more than 2 to 7 billion people out of total 9.3 billion. • India with 16% of the world’s population, has only 4% of the freshwater resources. • Per capita availability of freshwater in India has dropped from 5,177 cubic meters in 1951 to 1,820 cubic meters in 2001. • Urban situation is no better. Water is rationed twice a week in Bangalore, and for 30 minutes a day in Bhopal. • Two out of every three people on earth will have to live in water stressed condition by the year 2025.

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Environmental Chemistry

Uses • Is essential for all forms of life. • Many uses of water include agricultural, industrial, household, recreational and environmental activities. • Virtually all of these human uses require freshwater. Table 4.1 Distribution of Water Usage Purpose

Country India

China

90%

77%

41% (30)

70%

Industry (including power generation)

7%

18%

49% (59)

25%

Domestic Use

3%

5%

10% (11)

5%

Agriculture

USA

World

Causes for Water Scarcity and its Result Population growth, urbanisation and increasing demand from competing uses for drinking, agriculture, industry and energy, the pressure on this finite resource are mounting everyday. Climate change is also affecting the hydrological cycle significantly thereby affecting freshwater production and its distribution. As a result of the extravagance in water usage, the per capita availability of freshwater is declining all over the world. If the present consumption patterns continue, two out of every three persons will be living under ‘water stressed’ conditions by the year 2025.

Overutilisation and Pollution of Surface and Groundwater • Growth of human population - an increasing need for larger amounts of water to fulfill a variety of basic needs. • Overutilisation of water occurs at various levels. • Use of more water than really needed. • Many agriculturists use more water than necessary to grow crops. Ways in which farmers can use less water without reducing yieldsuse of drip irrigation systems. • Agriculture also pollutes surface water and underground water - excessive use of chemical fertilizers and pesticides. Use of biomass as fertilizer, non toxic pesticides such as neem products, integrated pest management systems reduces the agricultural pollution of surface and groundwater.

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• Industry in order to maximise short-term economic gains does not bother its liquid waste and releases it into streams, rivers and the sea. • Sedimentation The deforestation in the catchments is mainly responsible for the erosion of topsoil. The eroded soil gets deposited in to the lake and result in heavy siltation. Apart from siltation the night soil from the sewerage drains, garbage, and other solid wastes deposit in the surface waterbodies and decreasing the water holding capacity of lake. This has led to result of area of the surface waterbodies reducing gradually due to several inlet points and is causing the waterbody heavily silted. • Water quality deterioration weed Due to mixing of raw domestic sewage and pollution from different sources, nutrient level in lower surface groundwater is higher which is responsible for prolific growth of algae, due to this algal bloom, surface water becomes green and they produce obnoxious by decay which create unhealthy environment. • Reduction in area of waterbodies Encroachment of wetland and dumping of waste as well as intake of sewage from various nallahs resulted in reduction of the waterbody. This requires an urgent check to avoid the further deterioration of lake. • Erosion Due to population pressure and unmanaged cattle grazing vegetable cover on catchments of surface waterbodies, has resulted in soil erosion. Soil erosion in the catchments andconsequently siltation within the lake will have to be arrested through suitable measures. • Waste disposal One of the major problems of surface waterbodies is dumping of solid wastes in to the lake. The anthropogenic activities on the bank of the lake like bathing, laundering, cattle bathing and human habitation should be prohibited. FLOODS A flood is an excess of water (or mud) on land that’s normally dry and is a situation wherein the inundation is caused by high flow, or overflow of water in an established watercourse, such as a river, stream, or drainage ditch; or ponding of water at or near the point where the rain fell. This is a duration type event. A flood can strike anywhere without warning, occurs when a large volume of rain falls within a short time.

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Environmental Chemistry

Flooding is primarily caused by natural weather events like rainfall and thunderstorms. Extensive rainfall over a long period of time will also lead to flooding. A flood will also occur when a river overflows its bank and the excess water spills onto the flood plain, which is usually also as a result of heavy rainfall. Some of the factors that may encourage flooding include: • A lack of vegetation and woodland. This is because trees and other forms of vegetation obstruct surface run-offs, while roots of trees take up water from the soil. A lack of vegetation will mean that surface run-offs will be high, and this can lead to flooding. • Drainage basin in urban areas are made of concrete which is impermeable and encourages surface flows. The drainage system takes the water quickly and directly to sewage treatment plants or as in some countries directly to rivers. Heavy rainfall in short periods in instances like this will lead to flooding. Faulty or ill maintained sewer networks and insufficient drainage networks will also encourage flooding. • Buildings and other developments like car parks in inappropriate places such that they prevent rainfall from draining away naturally can also lead to flood events. • Canals, reservoirs and other man-made structures can fail causing flooding to areas downstream. Industrial activities, water mains and pumping stations can also give rise to flooding due to failure. The effects of flooding includes damage to homes and properties, potential loss of lives, disruption in livelihood and communications and usually an economic loss to the Government. This is because businesses may lose stock, patronage and productivity. Flooding can also affect vital infrastructure. Tourism, agriculture and transportation can also be affected. Road links, canals, rail links may become damaged. The repair cost of the damaged infrastructure can be very high and the period before reinstatement long. Potable water supply may be lost or contaminated and these can have significant health effects as well. One good thing about flooding though is the deposition of silt on the flood plain making it fertile for agriculture and thereby supporting the livelihood of inhabitants of such areas by the provision of food. People living on or near floodplains may rely upon regular flooding to help support their farming and therefore provide food.

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Controlling Measures Dam are built along the course of a river. This helps to control the amount of water available for discharge and excess water is held back in this way and released in a controlled manner. This approach helps to reduce the risk of flooding. The stored water can be used to generate hydroelectric power. The downside of building dams is that they are expensive and need to be properly maintained. Floods can also be mitigated against by a process referred to as river engineering. This entails widening or deepening the river channels to enable it carry more water and reduce the risk of flood. This in itself is a potential flood risk because the water flows faster and may soon flood downstream. Proper urban planning entail controlling developments close to a floodplain which helps reduce the chance of flooding. Drainage and sewer systems should be properly planned and well maintained. Afforestation or the planting of trees should be practised in flood plains and areas prone to flooding. This is a low cost and environmentally friendly approach to reduce and prevent floods.

Flood Management Measures • Structural Measures: Physical works for modifying flood magnitude (to keep floods away from people) include Dams and Reservoirs, Embankment, Channel Improvement, River Diversion • Non-structural Measures: planned activity to modify susceptibility to flood damage(to keep people away from floods) ƒ Flood Forecasting and Warning ƒ Flood Plain Zoning ƒ Flood Fighting ƒ Flood Proofing ƒ Flood Insurance ƒ Relief and Rehabilitation

Flood Management Organisations • • • •

State Flood Control Departments Central Water Commission Ganga Flood Control Commission Brahmaputra Board

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Environmental Chemistry

Flood management approaches should be economical, environmentally friendly and socially sustainable. Sustainable developments manage the immediate flood situation (prevention and control) without compromising the needs of future generations. DROUGHT Drought is a climatic anomaly, characterised by deficient supply of moisture resulting either from sub-normal rainfall, erratic rainfall distribution, higher water need or a combination of all the factors. Droughts are the resultant of acute water shortage due to lack of rains over extended periods of time affecting various human activities and lead to problems like widespread crop failure, unreplenished ground water resources, depletion in lakes/reservoirs, shortage of drinking water and, reduced fodder availability etc. Table 4.2 Reported drought events in India over the past 200 years Period

Drought years

Period

Drought years

1801-1825

1801, 4, 6, 12, 19, 25

1901-1925

1901, 4, 5, 7, 11, 18, 20

1826-1850

1832, 33, 37

1926-1950

1939, 41

1851-1875

1853, 60, 62, 66, 68, 73

1951-1975

1951, 65, 66, 71, 72, 74

1876-1900

1877, 83, 91, 97, 99

1975-2000

1977, 78, 79, 82, 83, 85, 87, 88, 92

Drought conditions have been widespread in North Africa, the Mid-East, West Asian countries, India, China and have also known to occur in North-central, and South America. TYPES OF DROUGHTS Drought proceeds in sequential manner. Its impacts are spread across different domains as listed below.

Meteorological Drought Meteorological drought is simple absence/deficit of rainfall from the normal. It is the least severe form of drought and is often identified by sunny days and hot weather.

Hydrological Drought Meteorological drought often leads to reduction of natural stream flows or groundwater levels, plus stored water supplies. Main impact is on water resource systems.

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Agricultural Drought This form of drought occurs when moisture level in soils is insufficient to maintain average crop yields. Initial consequences are in the reduced seasonal output of crops and other related production. An extreme agricultural drought can lead to a famine, which is a prolonged shortage of food in a restricted region causing widespread disease and death from starvation.

Socioeconomic Drought Socioeconomic drought correlates the supply and demand of goods and services with the three above-mentioned types of drought. When the supply of some goods or services such as water and electricity are weather dependant then drought may cause shortages in supply of these economic goods.

IMPACT OF DROUGHTS One of the sectors where the immediate impact of drought is felt is agriculture. With the increased intensity or extended duration of drought prevalence, a significant fall in food production is often noticed. Drought results in crop losses of different magnitude depending on their geographic incidence, intensity and duration. The droughts not only affect the food production at the farm level but also the national economy and the overall food security as well. Their impact is also felt due to: • Deficit in ground water recharge. • Non-availability of quality seeds. • Reduced draught power for agricultural operations due to distress sale of cattle, • Land degradation.

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• Fall in investment capacity of farmers, rice in prices, reduced grain trade and power supply. • Education and awareness of policy makers and the public regarding the importance of improved drought preparedness as a part of integrated water resources management, Case Sudy: Ralegan siddhi The people of Ralegan Siddhi in Maharashtra transformed the dire straits to prosperity (Fig. 4.4). Twenty years ago the village showed all traits of abject poverty. It practically had no trees, the topsoil had blown off, there was no agriculture and people were jobless. Anna Hazare, one of the India’s most noted social activists, started his movement concentrating on trapping every drop of rain, which is basically a drought mitigation practice. So the villagers built check dams and tanks. To conserve soil they planted trees. The result: from 80 acres of irrigated area two decades ago, Ralegan Siddhi has a massive area of 1300 acres under irrigation. The migration for jobs has stopped and the per capita income has increased ten times from ` 225 to 2250 in this span of time. No World Bank funding, no-government grants - only people’s enterprise.

Fig. 4.4 Case Study (Ralegan Siddhi)

Conflicts Over Water – Equitable Distribution Water security is emerging as an increasingly important • Population growth continues to surge, the demand for water is increasing substantially, without a concomitant increase in water resources

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• In South Asia, conflict over freshwater has strained relations between India and Bangladesh, as well as India and Pakistan. 1. The Krishna-Godavari water dispute 2. The Cauvery water dispute 3. The Ravi-Beas water dispute Krishna-Godavari water dispute The Krishna-Godavari water dispute among Maharashtra, Karnataka, Andhra Pradesh (AP), Madhya Pradesh (MP), and Odisha could not be resolved through negotiations. Here Karnataka and Andhra Pradesh are the lower riparian states on the river Krishna, and Maharashtra is the upper riparian state. The dispute was mainly about the inter-state utilisation of untapped surplus water. The Cauvery dispute The core of the Cauvery dispute relates to the re-sharing of waters that are already being fully utilised. Here the two parties to the dispute are Karnataka (old Mysore) and Tamil Nadu (the old Madras Presidency). Between 1968 and 1990, 26 meetings were held at the ministerial level but no consensus could be reached. The Ravi-Beas dispute Punjab and Haryana, the main current parties in this dispute, are both agricultural surplus states, providing large quantities of grain for the rest of India. Because of the scarcity and uncertainty of rainfall, irrigation is the mainstay of agriculture. DAMS-BENEFITS AND PROBLEMS India’s increasing demand for water for intensive irrigated agriculture, for generating electricity, and for consumption in urban and industrial centers, has been met by creating large dams. BENEFITS: dams ensure a year round supply of water for domestic use, provide extra water for agriculture, industry, hydropower generation.

1. Flood Control and Flow Regulation Before diversion schemes and other methods were used to move water, humans and other flora and fauna resided along brooks, streams and rivers. These surface waters are part of a watershed, which is a defined area where precipitation falls to the earth and travels either across the surface or infiltrates into the ground; the water eventually converging into rivers flowing to a sea or ocean One component of a watershed is the floodplain, the area outside the bank of a river where water covers the ground during a flood.

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2. Irrigation and Water Usage With the construction of dams, the immediate availability of water increases. Transporting water for irrigation purposes has been performed for generations.

3. Power Generation The World Bank had assisted many countries in projects in Africa, India, Asia and elsewhere. Industries across the world are using this type of energy, which supplies five to nineteen percent of the total electricity produced in the U.S.

4. Recreation Not only do large dams supply water for food production and storage, provide electricity, and increase navigation, but create new locations for humans and wildlife to enjoy and inhabit. Essentially a large lake, a reservoir provides many people with opportunities to enjoy swimming, fishing, and boating PROBLEMS: They alter river flows, change nature’s flood control mechanisms such as wetlands and flood plains, and destroy the lives of local people and the habitats of wild plant and animal species. Irrigation to support cash crops like sugarcane produces an unequal distribution of water. Large landholders on the canals get the lion’s share of water, while poor, small farmers get less and are seriously affected. 1. Serious impacts on ecosystem – forest and river 2. Fragmentation and physical transformation of rivers 3. Displacement of people 4. Impacts on lives, livelihoods, cultures and spiritual existence of indigenous and tribal people 5. Water logging and salination in surrounding lands 6. Dislodging animal populations 7. Disruption of fish movement and navigational activities 8. Emission of greenhouse gases due to rotting of vegetation. DIFFERENT METHODS OF WATER CONSERVATION According to Indian Meteorological Department (IMD), there are only 40 rainy days in India, and hence a long dry period. India,

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being an agricultural country, its economic development is linked with agriculture. The major limiting factor for agriculture is water. A growing population and consequent need for increase in food production requiring increasing area of agricultural fields and irrigation are resulting in over use of water. Due to overexploitation of water resources, it has become scarce in many parts of our country. Needless to say, water conservation is of great importance to the economic, social and cultural development in India. The techniques for conservation of water are:

Conservation by Surface Water Storage Storage of water by construction of various water reservoirs have been one of the oldest measures of water conservation. The scope of storage varies from region to region depending on water availability and topographic condition.

Conservation of Rainwater Rainwater has been conserved and used for agriculture in several parts of our country since ancient times. The infrequent rain if harvested over a large area can yield considerable amount of water. Contour farming is an example of such harvesting technique involving water and moisture control at a very simple level. It often consists of rows of rocks placed along the contour of steps. Run-off captured by these barriers also allows for retention of soil, thereby serving as erosion control measure on gentle slopes. This technique is especially suitable for areas having rainfall of considerable intensity, spread over large part i.e., in Himalayan area, north-east states and Andaman and Nicobar islands. In areas, where rainfall is scanty and for a short duration, it is worth attempting these techniques, which will induce surface run-off, which can then be stored.

Groundwater Conservation • There is more groundwater than surface water. • Groundwater is less expensive and economic resource and available almost everywhere. • Groundwater is sustainable and reliable source of water supply. • Groundwater is relatively less vulnerable to pollution. • Groundwater is a free of pathogenic organisms. • Groundwater needs little treatment before use.

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• There is no conveyance losses in underground based water supplies. • Groundwater has low vulnerability to drought. • Groundwater is the key to life in arid and semi-arid regions. • Groundwater is source of dry weather flow in some rivers and streams. As we have limited groundwater available, it is very important that we use it economically and judiciously and conserve it to the maximum. Some of the techniques of groundwater management and conservation are described below. (i) Artificial recharge In one of the methods, water is spread over ground to increase area and length of time for water to remain in contact with soil. So as to allow maximum possible opportunity for water to enter into the ground. (ii) Percolation tank method Percolation tanks are constructed across the water course for artificial recharge. The studies conducted in a Maharastra indicates that on an average, area of influence of percolation of 1.2 km2, the average groundwater rise was of the order of 2.5 m and the annual artificial recharge to groundwater from each tanks was 1.5 hec m.

Catchment Area Protection (CAP) Catchment protection plans are usually called watershed protection or management plans. These form are an important measure to conserve and protect the quality of water in a watershed. It helps in withholding run-off water albeit temporarily by a check bund constructed across the streams in hilly terrains to delay the run-off so that greater time is available for water to seep underground. Such methods are in use in north-east states, in hilly areas of tribal belts. This technique also helps in soil conservation. Afforestation in the catchment area is also adopted for water and soil conservation.

Inter-basin Transfer of Water A broad analysis of water and land resources and population statistics of various river basins in our country reveals that areas in western and peninsular regions have comparatively low water resources/cultivable land ratio. Northern and eastern region which are drained by Ganga

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and Brahmaputra have substantial water resources. Hence, the scheme of diverting water from region with surplus water to water defecit region can be adopted Ganga-Cauveri link would enable to transfer of vast quantities of Ganga basin flood water running out to sea, to west and south west India. The transfer of the surplus Ganga water would make up for the periodical shortage in Sone, Narmada, Godaveri, Krishna and Cauveri. The National Grid Commission envisages diversion of part of the surplus discharge in the Ganga near Patna during the high flood period.

Adoption of Drip Sprinkler Irrigation Drip irrigation is an efficient method of irrigation in which a limited area near the plant is irrigated by dripping water. It is suitable method for any area and specially for water scarce areas. This method is particularly useful in row crop. Similarly sprinkler method is also suitable for such water scarce areas. About 80% water consumption can be reduced by this method, whereas the drip irrigation can reduce water consumption by 50 to 70%.

Management of Growing Pattern of Crops In water scarce areas, the crop selection should be based on efficiency of the crop to utilise the water. Some of the plants suitable for water scarce areas are (i) plants with shorter growth period; (ii) high yielding plants that require no increase in water supply; (iii) plants with deep and well trenched roots and (iv) plants which cannot tolerate surface irrigation. (i) Selection of crop varieties Crop performance and yield are the results of genotype expression as modulated by continuous interactions with the environment. Generally, the new varieties of crop do not require more water than the older ones. However, they require timely supply of water because their productivity is high. Frequent light irrigation is more conductive than heavy irrigation at large intervals for obtaining high yields. (ii) Nutritional management Potassium plays a major role under stress conditions. It improves the tissue water potential by osmoregulation, ultimately increasing the water use efficiency. Experiments conducted at the Water Technology Centre, Coimbatore, indicated that foliar application of 0.5% potassium

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chloride can reduce the moisture stress in soyabean, sorghum and groundnut. (iii) Role of antitranspirants Application of antitranspirants reduces transpiration maintaining thereby the tissue water potential. Plants then take up less water from soil. Antitranspirants can prolong the irrigation intervals by slowing down soil water depletion. Application of Kaolin (3%) and lime wash (2%) was found to maintain the water balance of plant and resulted in normal yield of sorghum under moisture stress conditions. Certain growth regulators reduce the plants susceptibility to water stress. Application of cycoel, a growth retardant increases the ability to withstand drought. Cycoel application also reduces production of gibberellic acid which leads to closing of stomata. Transpiration loss of water gets reduced.

Reducing Evapotranspiration Evapotranspiration losses can be reduced by reducing the evaporation from soil surface and transpiration from the plants, in arid zones, considerable amount of water is lost in evaporation from soil surface. This can be prevented by placing water tight moisture barriers or water tight mulches on the soil surface. Non-porous materials like papers, asphalt, plastic foils or metal foils can also be used for preventing evaporation losses. Transpiration losses can be reduced by reducing air movement over a crop by putting wind breaks and evolving such types of crops which possess xerophytic adaptations. (i) Reducing evaporation from various water bodies The quantity of water lost through evaporation is very high in many areas in our country. It is estimated that 10000 hectares of land loses about 160 mm3 of water each year. The water losses through evaporation from storage tanks, reservoirs, irrigation tanks, rivers and canals reduce the water available for various uses. The methods that reduce evaporation from waterbodies are installing wind breaks, reducing energy available for evaporation, constructing artificial aquifers, minimizing exposed surface through reservoir regulation, reducing ratio of area/volume of waterbodies, locating reservoirs at higher altitudes and applying monomolecular firms.

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Recycling of Water The waste water from industrial or domestic sources can be used after proper treatment, for irrigation, recharging groundwater, and even for industrial or municipal use. If agricultural lands are available close to cities, municipal waste water can be easily used for irrigation. Conservation of water in domestic use There is a large scope of conserving water at house hold level. A general awareness among the people about the importance of water and its availability, and need for conservation can help in minimising wastage to a large extent. Losses during water supply also need to be prevented by reducing the leakages. Some of the ways for improving the efficiency of water use at household level are: • Reduce wastage-leaking pipes mean that lot of water never reaches to the people. In Delhi estimated losses are 35-40%. • Closing of taps while not in use. • Better irrigation techniques irrigation systems waste up to 70% water used. In drip irrigation water loss is significantly less. • Use low flush toilets-reducing the amount of water used each time the lavatory is flushed. • Build latrines and compact toilets which can turn human waste into clean, useful manure this is much cheaper than connecting toilet to a piped sewage line. • Use bowls to wash vegetables, dishes instead of running tap. • Greater use of recycled water 4.29 grey water in the home. Instead of using potable or treated water use bath and shower water for watering the plants. • Use washing machine or dish washer when it is fully loaded. Rainwater Harvesting, is an age-old system of collection of rainwater for future use. But systematic collection and recharging of ground water, is a recent development and is gaining importance as one of the most feasible and easy to implement remedy to restore the hydrological imbalance and prevent a crisis. Technically speaking, water harvesting means: A system that collects rainwater from where it falls rather than allowing it to drain away. It includes water that is collected within the boundaries of a property, from roofs and surrounding surfaces. Experts suggest various ways of harvesting water (Fig. 4.5).

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• Capturing run-off from rooftops • Capturing run-off from local catchments • Capturing seasonal flood water from local streams • Conserving water through watershed management Local water harvesting systems developed by local communities and households can reduce the pressure on the state to provide all the financial resources needed for water supply. In addition, involving people will give them a sense of ownership and reduce the burden on government funds.

Fig. 4.5 Rainwater Harvesting

ADVANTAGES OF RAINWATER HARVESTING 1. To meet the ever increasing demand for water. Water harvesting to recharge the groundwater enhances the availability of groundwater at specific place and time and thus assures a continuous and reliable access to groundwater. 2. To reduce the run-off which chokes storm drains and to avoid flooding of roads. 3. To reduce groundwater pollution and to improve the quality of groundwater through dilution when recharged to groundwater thereby providing high quality water, soft and low in minerals. 4. Provides self-sufficiency to your water supply and to supplement domestic water requirement during summer and drought conditions.

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5. It reduces the rate of power consumption for pumping of groundwater. For every 1 m rise in water level, there is a saving of 0.4 kWh of electricity. 6. Reduces soil erosion in urban areas 7. The rooftop rainwater harvesting is less expensive, easy to construct, operate and maintain. 8. In saline or coastal areas, rainwater provides good quality water and when recharged to groundwater, it reduces salinity and helps in maintaining balance between the fresh-saline water interfaces. 9. In Islands, due to limited extent of freshwater aquifers, rainwater harvesting is the most preferred source of water for domestic use. 10. In desert, where rainfall is low, rainwater harvesting has been providing relief to people.

Watershed Management Watershed is an area that contribute water to a stream or a waterbody through run-off or underground path. That is the region from which surface water draws into a river, a lake, wetland or other body of water is called its watershed or drainage basin. As rainwater and melting snow run downhill, they carry sediment and other materials into our streams, lakes, wetlands, and groundwater. A watershed is the area of land that catches all precipitation (such as rain and snow) and drains or seeps into a marsh, stream, river, lake or groundwater. Healthy watersheds are vital for a healthy environment and economy. Because surfaced groundwater is part of the total water cycle, wellhead and aquifer protection follow similar concepts and approaches. Watershed management is a technique for conservation of water and soil in a watershed. The presence of water in soil is essential for the growth of plants and vegetation. Forests and their associated soils and litter layers are excellent filters as well as sponges, and water that passes through this system is relatively pure. Various kinds of forest disturbances can speed up the movement of water from the system and in effect, reduce the filtering action. In mountainous terrain the forests play a prominent role in prevention of soil erosion. Erosion threat can be tackled by the maintenance of continual cover. Deforested land sheds water swiftly, causing sudden rises in the rivers below. Over a large river system, such as that of the Ganga and the Yamuna, forests

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are a definite advantage since they lesson the risk of floods. They also provide conditions more favourable to fishing and navigation than does un-forested land. All natural streams contain varying amounts of dissolved and suspended matter, although streams contain varying amounts of dissolved and suspended matter, although streams issuing from undisturbed watershed are ordinarily of high quality. Waters from forested areas are not only low in foreign substances, but they also are relatively high in oxygen and low in unwanted chemicals. The belief that forests increase rainfall has not been substantiated by scientific inquiry. Local effects can, however, prove substantial, particularly in semiarid regions where every millimeter of rain counts. The air above a forest, as contrasted with grassland, remains relatively cool and humid on hot days, so that showers are more frequent.

Case Study In Gandhigram, a coastal village in Kutch distrirct, the villagers had been facing a drinking water crisis for the past 10 to 12 years. The groundwater table had fallen below the sea level due to over extraction and the seawater had seeped into the ground water aquifers. The villagers formed a village development group, Gram Vikas Mandal. The Mandal took a loan from the bank and the villagers contributed voluntary labor (Shramdan). A check dam was built on a nearby seasonal river, which flowed past the village. Apart from the dam, the villagers also undertook a micro-watershed project, due to these water retention structures, the villagers now have sufficient drinking water, and 400 ha of land, which earlier lay barren, has come under irrigation. Similar examples of people’s initiative in organizing rainwater harvesting can also be seen in the two villages of Khopala and Jhunka in Bhavnagar district of Saurastra. MINERAL RESOURCES Minerals are defined as solid, inorganic, naturally occurring substances with a definite chemical formula and general structure. Resources can also be classified into three major use groups: metallic, energy and non-metallic mineral resources. Metals can be subdivided into two classes, on the basis of their occurrence in the earth’s crust. The geochemically abundant metals are those that individually constitute 0.1% or more of the earth’s crust by weight (such as Fe, Al, Mn, Ti, Si, Mg etc.). Geochemically scarce metals are less

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than 0.1% by weight of the earth’s crust. These are Cu, Pb, Zn, Mo, Hg, Ag, and Au. Mineable deposits of scarce metals tend to be smaller and less common than mineable deposits of abundant metals. The second major group in resource classification is energy minerals. Some resources, such as fossil fuels and radioactive minerals (U, Th), are non-renewable resources. Other energy resources, such as running water and solar heat, are renewable. The third group of resources contains all of these material substances, excluding the metals and energy minerals. Such resources include minerals used as sources of chemicals (halite, borax), plus minerals used as raw materials for fertilizers (phosphates, nitrates). This group also contains industrial minerals used as paints, fillers, abrasives, drilling mud, construction and building materials etc. Water and soil are vital to the production of food. Referring to Indian sub-continent, Indian sub-soils are rich in onshore and off shore crude oils and natural gas, coal, iron ore, copper, bauxite and many such minerals, all of which fall under the category of exhaustible mineral resources. The major mineral rich states in India are Chattisgarh, Jharkhand, Madhya Pradesh, Goa, Karnataka, Odisha, and Maharashtra. Mineral resources are not only common resources of all in the current ‘nation state’, but also in the ‘inter-generational state’. Minerals often require quite a lot of processing to get the desired metals from them. The steps involved are:

1. Locating a Supply of Mineral Minerals sometimes could be located below the surface of the Earth’s crust.

2. Mining Depending upon the location of the ores the following methods are adopted for their extraction: (i) Surface Mining: This is adopted when the mineral is below or just below the surface. The layers of rock and soil covering the mineral deposits are first scrapped-off and discarded as soils, then minerals are removed using appropriate technology. the type of surface mining employed depends on the minerals and the topography of the mine. Thus two different methods: (a) Open Pit Mining: A large hole is dug in the earth to get the minerals. The large pit is a quarry. e.g., Granite

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(b) Strip Mining: A long trench is dug to get the minerals. A series of strips are dug. The strips are parallel to each other. The soil and the rock that are not extracted are put into the previous strip. Rows of dug out materials, known as spoil banks, are created on the surface. (ii) Subsurface Mining: A subsurface mine is deep inside the earth to remove minerals such as coal and valuable minerals like gold ore. The surface of the earth may be disturbed very little. A mass of tunnels or shafts may be used to go into the deposits of minerals. Thus these mines are also termed as deep shaft mines. This type of mining is more expensive and complex.

Processing the Mineral Ore needs to be separated from material that does not contain the desired metal. The common processing are: • Grinding and crushing: Materials are crushed to desired sizes. • Sorting: It is used to separate metal from ore. • Smelting: Heating of ore so the metal separates from the undesirable material. • Purification: Various methods are used to purify the metal from ore. e.g., Some minerals like limestone, sand etc. require less processing. No smelting or purification is needed. CAUSES OF EXPLOITATION OF MINERAL RESOURCES 1. Increase in the sophistication of technology enabling natural resources to be extracted quickly and efficiently. 2. A rapid increase in population. This leads to greater demand for mineral resources. 3. Cultures of consumerism. Materialistic views lead to the mining of gold and diamonds to produce jewellery, unnecessary commodities for human life or advancement. 4. Excessive demand often leads to conflicts due to intense competition. Organisations such as Global Witness and the United Nations have documented the connection. 5. Non-equitable distribution of resources.

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ENVIRONMENTAL EFFECTS OF EXTRACTING AND USING MINERAL RESOURCES The impact of mining in environmental degradation has been receiving attention in recent years. An overwhelmingly large number of small mines being open pit mines, land degradation including deforestation take place consequent to mineral exploitation where the extent of damage caused by mining may not be significant individually, the cumulative effect, especially by a cluster of mines, becomes fairly large. The social, economic and environmental impacts of exploiting metal ores (mineral extraction) and of using mineral resources: Metal ores are obtained by mining/quarrying and that this involved digging up and processing large amounts of rock. Most ores are mined have to be concentrated before the metal is extracted and purified. This often results in lots of waste material that must be dealt with from an environment of view. This means that metal or mineral extraction results in problems and issues in balancing ecological, environmental, economic, social advantage factors. It doesn’t matter whether you are mining and processing iron ore or limestone, many of the advantages and disadvantages are common to these operations Examples of advantages of exploiting it’s own mineral resources: 1. Useful products can be made from metal to enhance our livesmost consumer products we take for granted i.e., we expect to have them at our disposal. 2. Valuable revenue if the mineral or its products are exported. 3. Jobs for people, especially new sources of employment in poor countries or areas of high unemployment in developed countries. 4. Wages earned go into the local/national economy leading to improvements in schools, health service and transport etc. 5. Increase in local facilities promoted e.g., transport systems, like roads, recreational and health social facilities. Examples of disadvantages of exploitation of mineral resources and reduction of its social and environmental impact: 1. Dust from mining-quarrying or processing can be reduced by air filter and precipitation systems and even hosing water on dusty areas or spoil heaps or carried away to somewhere else via tall chimneys.

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2. Scarring of the landscape from mining, quarrying, waste tips etc., as well as loss of wildlife habitat. 3. Noise from process operation or transport of raw materials and products (lorries/trucks/wagons). 4. Difficult to deal with, sound-proofing often not practical, but operations can be reduced for unsociable hours e.g., evening movement. 5. Pollution can be reduced by cleaning the ‘waste’ or ‘used’ air, water and waste gases etc., of toxic or acidic materials e.g., Toxic carbon monoxide from the blast furnace extraction of iron, it can be burnt as a fuel, but it must not be released into the air unless converted to biologically harmless carbon dioxide. 6. Sulphur dioxide gas from copper extraction of its sulphide ore is an irritating poisonous gas which can also cause acid rain, but it can be converted to the useful, therefore saleable, industrial chemical concentrated sulphuric acid, so you can remove a harmful pollutant and recover back some of the metal extraction costs, good green economics. 7. Acidic gases like sulphur dioxide can be removed by bubbling through an alkali solution such as calcium hydroxide solution (‘limewater’) where it is neutralised and oxidised to harmless calcium sulphate. Cleaning a gas in this way is called ‘gas scrubbing’. 8. Mining operations will disfigure the landscape But it can be re-claimed and ‘landscaped’ in an attempt to restore the original flora and fauna. 9. The cost of extracting and purifying metals is quite varied for several reasons. If the ore is plentiful it is cheaper e.g., iron ore, but silver ores and gold are much rarer and on that basis alone they would be a more valuable commodity. Reduction of ores using coke (e.g. iron), made from cheap coal, is cheaper than the electricity bill for extracting aluminium from its molten oxide by electrolysis, but different metals have different properties best suited for particular and different uses. Generally, more reactive metals like Al) are more costly to extract than less reactive metals (like Fe) because of the different energy demands and ease of extraction, which may sometimes be due to more costly technology.

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CONSERVATION OF MINERAL RESOURCES The future supply of a resource depends on its affordable supply and how rapidly that supply is used. A nonrenewable resource generally becomes economically depleted rather than totally depleted. There are five choices at that point: recycle or reuse existing supplies, waste less, use less, find a substitute, or do without. A rising price for a scarce mineral resource can increase supplies and encourage more efficient use. Economics determines what part of a known mineral supply is extracted and used. Higher prices often mean more resources can be used (at a higher extraction cost), but this can be affected by national policies that subsidize exploration or restrict exports/imports. New technologies can increase the mining of low-grade ores at affordable prices, but harmful environmental effects can limit this approach. In 1900, the average copper ore mined in the United State was about 5% copper by weight; today that ratio is 0.5%. Nanotechnology offers new promise (and concerns) for mineral exploration. Scientists and engineers are developing new types of materials that can serve as substitutes for many metals. This is known as the materials revolution. For example, development of silicon and ceramics may replace the need for as much metal. Recycling valuable and scarce metals saves money and has a lower environmental impact than mining and extracting them from their ores. In many cases, metals are actively recycled. We can use mineral resources more sustainably by reducing their use and waste and by finding substitutes with fewer harmful environmental effects. Growing signs point to an ecoindustrial revolution taking place over the next 50 years. The goal is to make industrial manufacturing processes cleaner and more sustainable by redesigning them to mimic how nature deals with wastes.

Case Study of Mining in Rajasthan, Bijolia In order to evaluate scientifically the effect of mining on environment, a study sponsored by Department of Environment and forest, Government of Rajasthan, was carried out in Bijolia Mining area. The findings were sensational and revealing. Bijolia is one of the largest mining areas of Rajasthan where mining on large scale commenced nearly three decades ago. Since then, environment has

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been adversely affected, but no systematic evaluation has been carried out to assess its impact on the nature and socioeconomic system of the people working in and around the mines. FOOD RESOURCES

World Food Problems Food security depends on available world supplies of food, the income of the designated population, accessibility to the available supplies, the consumption rate of food, and the amount that can be set aside for future use.

Food Security “All people, at all times, have the physical and economic access to sufficient, safe and nutritious food to meet their dietary needs and food preferences for an active and healthy life”. Amartya Sen - food entitlement and access to enough food for a healthy lifestyle.

Major Causes of World Food Shortages Food insecurity is not just a problem related to food production; it is closely linked to poverty and economic stagnation. The persistence of widespread food insecurity underscores the futility of increasing production without addressing the underlying social, political, and economic structures that make or keep people poor and hungry. One obviously must look beyond farm size, arable land use, population growth, technology, international trade, and the environment in order to understand the long-term trends in food consumption, production, and distribution. World Wide Problems 1. Natural catastrophes- drought, heavy rain and flooding, crop failures. 2. Environmental degradation- soil erosion and inadequate water resources. 3. Food supply and demand imbalances. 4. Inadequate food reserves. 5. Warfare and civil disturbances. 6. Migration-refugees.

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7. Culturally-based food prejudices. 8. Declining ecological conditions in agricultural regions.

Problems of the Developing World 1. Under development. 2. Excessive population growth. 3. Lack of economic incentives- farmers using inappropriate methods and laboring on land they may lose or can never hope to own. 4. Parents lacking knowledge of basic nutrition for their children. 5. Insufficient government attention to the rural sector.

Problems of the Industrialised World 1. 2. 3. 4. 5. 6.

Excessive use of natural resources. Pollution. Inefficient, animal-protein diets. Inadequate research in science and technology. Excessive government bureaucracy. Loss of farmland to competing uses.

Problems Linking Industrial and Developing Worlds 1. 2. 3. 4. 5. 7. 8. 9.

Unequal access to resources. Inadequate transfer of research and technology. Lack of development planning. Insufficient food aid. Politics of food aid and nutrition education. Inappropriate technological research. Inappropriate role of multinational corporations. Insufficient emphasis on agricultural development for selfsufficiency. World produced enough food to meet basic needs, but still 1 in 6 do not get enough to meet nutritional needs. Human Needs- Large amounts of macronutrients (protein, carbs, fats) and Small amounts of micronutrients (A, C, E, iron, iodine, calcium) 1. Undernutrition- Lack of calories, disease increase, stunted growth etc. (WHO estimate182 million children under 5) Avg. male needs about 2,500 cal per day.

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2. Malnutrition- Lack of nutrients, cannot get enough protein mainly eating corn, rice, wheat huge childhood problem (3 billion worldwide). 3. Overnutrition- Too many calories in animal saturated fats, sugar, salt or Food intake exceeds energy use and causes body fat. It lowers life expectancy, heart disease, lower productivity and quality of life. In developed countries it is 2nd leading preventable cause of death after smoking.

Changes Causes by Agriculture and Over-grazing Hunting and gathering has been the main form of sustenance practiced in the earlier periods of human history. Shifting cultivation or Jhoom farming is a 12000-year old practice and a step towards transition from food collection to food production. It is also known as slash and burn method of farming. Annually about 5 lakhs ha (hectares) of forest is cleared for this type of farming. In this type of cultivation there is a limited use of tools with not very high level of mechanisation. However, this method of cultivation causes extreme deforestation, as after 2-3 years of tilling, the land is left to the mercy of nature to recover. This type of cultivation was always meant to fulfil local needs or onsite demands to meet the requirements of the cultivating villagers. Even today, shifting cultivation is practiced in the states of Assam, Manipur, Meghalaya, Mizoram, Nagaland, Tripura and Andaman and Nicobar Islands. Table 4.3 Industrialized Agriculture

Subsistence Agriculture

Modern agricultural methods

Traditional agricultural methods

Developed countries

Developing countries

Inputs-capital, energy and chemicals

Inputs-labor and land

High yields

Food for family

Shifting Cultivation (type of Subsistence agriculture)- Grow crops, then leave land alone. Slash-and-burn agriculture-clear forest, Grow crops, Soil loses productivity quickly. It supports small populations. Nomadic Herding (type of Subsistence agriculture)-Land not suitable for crops and livestock continually move. Intercropping (type of Subsistence agriculture)-Variety of crops in same field (Polyculture), plants mature at different times and different crops harvested throughout the year.

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Fig. 4.6 Sustainable Agriculture

Sustainable Agriculture- Less chemicals and antibiotics, Water and energy conservation and diverse crops (Fig. 4.6).

Overgrazing Soil degradation caused by overgrazing is a worldwide problem. It occurs when too many animals graze for too long and exceed the carrying capacity of the grassland area. The degradation of an overutilised area occurs mainly where animals prefer to spend extra time because of the attractants that are around gateways, water sources, along fences or farm buildings. High grazing pressure decreases plant density which results in changes of the botanical composition of a pasture. Moreover, overgrazing increases area covered by no vegetation, reduces infiltration, soil moisture and fertility, accelerates run-off and soil erosion, increases soil bulk density, penetration resistance, soil ammonia and nitrate content and changes soil microbial activity. Management practices have been used successfully to improve grazing distribution. These practices include water development, placement of salt and supplements, fertilizer application, fencing, burning, and the planting of special forages which can be used to enhance grazing by livestock in underutilised areas. EFFECTS OF MODERN AGRICULTURE As environmental conditions effect to agricultural practices, agricultural practices also have effects on environment. Namely; agriculture affects

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to global flowing of greenhouse gases. The main reason for the destruction of forest land is to obtain agricultural land. As a result of agricultural land obtaining, greenhouse gases are created at the same time. These greenhouse gases Show the second major negative impact after the negative effects of greenhouse gases which created by the using of the fossil fuels.

Negative Effects

Fig. 4.7 Negative Effects of Agriculture

1. Pesticide usage Pesticides that are used to elimination of harmful insects, microorganisms and other pests which they mixing with soil, water, air and food, they cause to problems on the agricultural foods and affect both human health and natural balance so finally they become an

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environment problem. Pesticide runoff is an important contributor to surface-water contamination. A pesticide that specialised on a harmful doesn’t kill only target, it also kills many harmless organisms. There are hundreds of pesticides that are used in the world. According to WHO’s classification, pesticides are very dangerous, 48 of them are quite dangerous, 118 of them are moderately dangerous and 239 of them are less dangerous of totally 700 mostly used pesticides. A 75% rate of pesticide usage belongs to developed countries. 2. Chemical fertilizer usage The fertilizer which are used to improve plant growth, more and qualified product and some features of soil like physical, chemical and biological structure cause to environmental pollution in case of excessive or wrong usage. Using high amounts of nitrogen fertilizer results to soil washing, contaminates to groundwater, drinking water, stream and sea nonetheless it increases nitrogen amount. This also affects the water organisms and when that kind of waters used to somewhere they break the natural balance of environment. Drinking waters shouldn’t contain more than 20 ppm nitrate. 3. Irrigation Irrigation has big importance to high agricultural yield and quality in arid and semi-arid regions. Wrong irrigations cause to environment problems. Rising of ground water, salinity, fertilizers and chemical additives residues go to deep with irrigation water, trace elements collect in water sources and cause to soil erosion and these kinds of waters make disease and harmful on the whole living organisms so this type of waters are a very important environment problem. Also excessive irrigation as a purpose of agricultural production leads to soil salinity and desertification. 4. Soil tillage Wrong soil tillage with regards of without any concern field location, soil structure and climate conditions cause to soil moving with rain in other words cause erosion. This situation not only cause to inefficient soils, it also pollutes streams and fills up dams with soil etc., serious environment problems. 5. Rotation Bioenergy crops play an ecologically and economically fundamental role as an alternative to agri-food productions and as renewable

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energy sources. Agricultural applications which are without rotation due to lack of knowledge or economical reasons entail to one-way consumption of soil plant nutrition elements, decrease to soil fertility, degradation, increasing of disease and harms in the soil and it also cause to erosion. 6. Plant hormone usage Plant hormone term means that some organic substances that created by plants and can be effective even very low intensity, and they moved in plant for growing and development also they increase the yield. Using of plant hormone is harmless in case of appropriate dosage and time, but the same hormone could make toxic effect if it used careless. The most used hormone is 2.4-D. The amount of this hormone shows difference country to another. As an example Sweden doesn’t give permission any residue of 2.4-D, Germany allowed 2.0 ppm in citrus species and 0.1 ppm for other products.

Positive Effects of Agricultural Applications As agriculture has negative effects on environment it also has positive effects. For instance some regions that have commonly agricultural applications have various favorable environmental effects kind of natural life, oxygen production and climate depending on regions and ecology. As example although fertilizing has negative effects on air, it has indirect positive effects. In the fertilized fields, O2 is consisted by photosynthesis so it increases amount of O2 in atmosphere. Modern agricultural practices use many kinds of chemicals such as fertilizers, pesticides, cleaners, crop preservatives to produce and keeping large amount of high-quality food. Sustainable agriculture which is a new agricultural technique seems environmentally friendly and it is supported by developed countries. Environmentally friendly agriculture has three common applications. These are good agricultural practices, organic agriculture and precision agriculture. Also rotation, sowing of legumes that able to nitrogen fixation and fallowing reduce the negative effect of agriculture on climate change.

Fertilizer-Pesticide Problems Pesticides are the chemical substances that help to control pests and classified as Insecticides, Herbicides, Fungicides, Rodenticides. The four main classes of insecticides are organophosphates, carbamates, chlorinated hydrocarbons, and insecticides derived from plants

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(botanical). A fertiliser is a natural or artificial substance containing the chemical elements that improve growth and productiveness of plants. Fertilizers enhance the natural fertility of the soil or replace the chemical elements taken from the soil by previous crops. The use of manure and composts as fertilizers is probably almost as old as agriculture. Modern chemical fertilizers include one or more of the three elements that are most important in plant nutrition: nitrogen, phosphorus, and potassium (NPK). Pesticides can poison people in different ways: through the skin, through the eyes, through the mouth (by swallowing) or through the air (by breathing). Pesticides poisoning can cause many health problems. A person exposed to pesticides can have more than one sign. Some signs show up when the person is exposed. Nose and Mouth: runny nose, drooling. Head and Eyes: headaches, vision problems, small pupils in the eyes, tears. Chest and Lungs: pain, breathing problems. Stomach: pain, diarrhea, nausea and vomiting. Legs and Arms: muscle cramps or pains, twitching. Skin: itching, rashes, bumps, redness, blister, burning, sweating too much. Hands: damage to fingernails, rashes, numbness and tingling in fingers. Other general signs of pesticides poisoning are: Confusion, weakness, trouble walking, trouble concentrating, muscle twitching, restlessness and anxiety, bad dreams and trouble sleeping Pesticides poison the soil, water and air 1. Soil contamination The transport, persistence or degradation of pesticides in soil depend on their chemical properties as well as physical, chemical and biological properties of the soil. All these factors affect sorption/desorption, volatilisation, degradation, uptake by plants, run-off and leaching of pesticides. 2. Water contamination Water contamination depends mainly on nature of pesticides (water solubility, hydrophobicity), soil properties, weather conditions, landscape and also on the distance from an application site to a water source. Rapid transport to groundwater may be caused by heavy rainfall shortly after application of the pesticide to wet soils. The geographic and seasonal distribution of pesticide occurrence follows patterns in

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land use and pesticide use. Streams and rivers were frequently more polluted that groundwaters and more near the areas with substantial agricultural and/or urban land use. 3. Effects on Organisms Soil microbial population are characterised by fast flexibility and adaptability to changed environmental condition, the application of pesticides (especially long-term) can cause significant irreversible changes in their population. Inhibition of species, which provide key process, can have a significant impact on function of whole terrestrial ecosystem. ƒ Soil invertebrates like Nematodes, springtails, mites and further micro-arthropods, earthworms, spiders, insects and all these small organisms make up the soil food web and enable decomposition of organic compounds such as leaves, manure, plant residues and they also prey on crop pests. Soil organisms enhance soil aggregation and porosity and thus increasing infiltration and reducing run-off. Many pesticides show negative effects on growth and reproduction of earthworms. Pesticides can enter fresh water streams directly via spray drift or indirectly via surface run-off or drain flow. Many pesticides are toxic to freshwater organisms. ƒ Decline of farmland bird species has been reported over several past decades and often attributed to changes in farming practises, such as increase agrochemical inputs, loss of mixture farming or unfarmed structures. Besides lethal and sub lethal effects of pesticides on birds, concern has recently focused on the indirect effects. These effects act mainly via reduction of food supplies (weeds, invertebrates), especially during breeding or winter seasons. As consequence insecticide and herbicide application can lead to reduction of chick survival and bird population. Time of pesticides application plays also important role in availability of food. 4. Effects of Pesticides and Farming Practises on Biodiversity Intensive pesticides and fertilizers usage, loss of natural and semi-natural habitats and decreased habitat heterogeneity and all other aspects of agricultural intensification have undoubted impact on biodiversity decline during last years.

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Controlling Agricultural Pests Several practises (generally Integrated pest management techniques) can be used to minimize unwanted effects of pesticides on farmland birds, such as use of selective pesticides, avoiding spraying in during breeding season and when crops and weeds are in flower, minimise spray drift or creation of headlands (Fig. 4.8).

Fig. 4.8 Integrated Pest Management (IPM) Tools

Case study-first warning signals about pesticides danger In 1962, Rachel Carson, an American courageous woman and scientist, wrote down her nature observation and pointed out sudden dying of birds caused by indiscriminated spraying of pesticides (DDT). Her book, Silent Spring, became a landmark. It changed the existing view on pesticides and has stimulated public concern on pesticides and their impact on health and the environment. Silent Spring facilitated the ban of the DDT in 1972 in the United States. More research has been done and several dangerous and persistent organic pesticides like Dieldrin, Endosulfan and Lindane have been banned or restricted since that time. WATER LOGGING An agricultural land is said to be water-logged, when its productivity gets affected by the high water table. The productivity of land in fact, gets affected when the root zone of the plants gets flooded with water, and thus become ill aerated. Inadequate aeration reduces crop yield.

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Causes of Water Logging Basically, water logging is the rise of water table onto root zone level leading to various problem to crop growth. This may occur due to the following reasons. 1. Over and Intensive Irrigation Under the practice of intensive irrigation, the maximum irrigable area of a small region is irrigated. This leads to, too much of irrigation, in that region, resulting in heavy percolation and subsequent rise of water table. 2. Seepage of Water from Nearby Areas Water from the adjoining high lands may seep into the sub-soil of the affected land and may raise the water table. 3. Seepage of Water Through the Canals/Reservoirs This is major cause of water logging in canal command areas. Water may seep through the beds and sides of the adjoining canals, reservoirs, situated at a higher level than the affected land. This results into high water table in the affected area. 4. Lack of Natural Drainage System If sufficient availability of natural drainage is not there in form of slope, soiIs having less permeabIe sub-stratum such as clay lying below the top layers of pervious soils, will not be able to drain the water deep into the ground. This may lead to rise in water level to the extent that it can affect the root zone and the crop cultivation. 5. Inadequate Surface Drainage Surface drainage system is common passage way for run off water. In absence of proper surface drainage, the water will constantly percolate and will raise the level of the water table leading to water logging. 6. Excessively High Rain Fall This is common source water logging is cities. Even in farm land heavy down pouring may cause water logging. 7. Overgrowth of Weeds and Aquatic Plant During rainy seasons weeds and grasses grow excessively obstructing the passage of water in natural waterways. If a land is continuously submerged by floods, aquatic plants like hyacinths, grasses and weed may grow. They may obstruct the natural surface drainage of the soil, and thus, increasing the chances of water logging. 8. Irregular or Flat Topography Topography also affects natural drainage and thus lead to water logging. In steep terrain, the

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water is drained out quickly. On flat or irregular terrain having depressions, the drainage is very poor. These factors lead to greater detention of water on the land, causing more percolation and water logging, if infiltration of soil is not proper.

Effects of Water Logging 1. Hampering the Nitrification The life of a plant, in fact, depends upon the nutrients like nitrates, and the form in which the nitrates are consumed by the plants is produced by the bacteria, under a process called nitrification. These bacteria need oxygen for their survival. The supply of oxygen gets cutoff when the land becomes ill aerated, resulting in the death of these bacteria, and fall in the production of plant’s food (i.e. nitrates) and consequent reduction in the plant growth, which reduces the crop yield. Apart from ill aeration of the plants, water logging creates many other problems. 2. Delayed Cultural Practices The normal cultivation operations, such as tilling, ploughing, etc., cannot be easily carried out in wet soils. In general, this leads to excessive delay in cultural practices and delayed sowing of crop, less or very poor yield. 3. Overgrowth of Weeds Certain water loving plants like grasses, weeds, etc., grow profusely and luxuriantly in waterlogged lands, thus affecting and interfering with the growth of the crops. 4. A Major Cause of Salinity With the rise of the water table, the plant roots happen to come within the capillary fringe, and water get continuously evaporated by capillarity. Thus, a continuous upward flow of water from the water table to the land-surface gets established. Due to this upward flow of water, the salts, present in the water, also rise towards the surface, resulting in the deposition of salts in the root zone of the crops. The concentration of these alkali salts in the root zone of the crops has a corroding effect on the roots, which reduces the osmotic activity of the plants and checks the plant growth. Such soils are called saline soils. Thus, water logging ultimately leads to salinity, resulting into reduced crop yield. Salinity and water logging are treated as a twin problem as salinity and water logging occurs together. Water logging is followed by salinity.

Control Measures of Water Logging The various measures adopted for controlling water logging are given on the next page:

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1. Lining of Canals and Water courses As seepage is one of the main culprits of rise of water table, attempts should be made to reduce the seepage of water from the canals and watercourses. This can be achieved by lining them. It is a very effective method of controlling water logging. 2. Reduced Intensity of Irrigation The areas where there is a possibility of water logging, intensity of irrigation should be reduced. This can be achieved by crop rotation. This would help controlling water logging in the region. 3. Optimum Use of Water Educating the farmers by proper extension method can bring improvement. As a policy matter, the revenue should not be charged on the basis of irrigated area but should be charged on the basis of the quantity of water utilised. 4. Intercepting Drains These drains are to check the canal water seepage. Intercepting drains along the canals should be constructed, wherever necessary. They would help intercepting seepage water and prevent the water from reaching the area and thus water logging may be prevented. 6. Efficient Drainage System An efficient drainage system should be provided in order to drain away the storm water and the excess irrigation water. A good drainage system consists of surface drains as well as sub-surface drains. 7. Consumptive Use of Surface and Sub-surface Water Conjunctive use is a combined use of sub-surface water or groundwater and the surface water or canal water in a judicious manner to derive maximum benefits. The introduction of lift irrigation to utilise ground water helps in lowering the water table in a canal irrigated area, where water table tends to go up. Thus, consumptive use should be adopted to control water logging. SALINITY Salinity is the accumulation of salts (often dominated by sodium chloride) in soil and water to levels that impact on human and natural assets (e.g. plants, animals, aquatic ecosystems, water supplies, agriculture and infrastructure). Dryland salinity occurs in unirrigated landscapes.

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Causes of Salinity Salinity occurs where salt in the landscape is mobilised and redistributed closer to the soil surface and/or into waterways by rising groundwater. The watertable rises under dryland agriculture because of increasing rates of leakage and groundwater recharge. This occurs if deep-rooted perennial species such as native trees, shrubs and pasture are replaced with shallow-rooted, annual species and long fallows are incorporated into a cropping rotation.

Impacts of Salinity Direct costs of increasing salinity to agricultural producers include: • reduced productivity of agricultural land • reduced agricultural production • reduced farm income • reduced options for production • increased input costs to rectify or reduce impacts of salinity • reduced access and traffic ability on waterlogged land • reduced water quality for stock, domestic and irrigation use • damage to and reduced life of farm structures such as buildings, roads, fences and underground services and pipes • animal health problems e.g., saline water supplies • farm machinery problems (bogging, rusting) • breakdown of soil structure, increased erosion and nutrient loss • loss of beneficial native flora and fauna • decreased land value. Environmental impacts from land and stream salinity include: • decline of native vegetation and loss of habitat • loss of nesting sites and decline in bird populations • decline in wildlife fauna other than birds • reduced food for wildlife populations • increased soil and wind erosion • reduced wetland habitat and decline in fish and aquatic populations • reduced aesthetic value • reduced recreational and tourism values

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• reduced biodiversity in stream fauna, riparian vegetation and wetlands • increases in weeds and undesirable changes in plant populations • damage to wildlife sanctuaries and state and national parks. ENERGY RESOURCES

Growing Energy Needs Energy is a key input for meeting basic needs and for achieving socio-economic development goals that include, inter-alia, fuel for cooking, heating and lighting in households, power for industry, and petroleum products for transportation. The supply of and the demand for virtually every type of energy generates varying degrees of environmental externalities that affect human health, ecological stability,and economic development. These effects can occur at the local, regional, national or transnational level.

Urban areas in developing countries typically generate up to 50%, and often more, of the national gross domestic product. This involves the consumption and transformation of energy resources that are not found within the physical limits of the city. Urban energy demand and consumption are the source of environmental problems in the hinterland. Renewable energy sources also called non-conventional energy, are sources that are continuously replenished by natural processes. For example, solar energy, wind energy, bio-energy-bio-fuels grown sustain ably), hydropower etc., are some of the examples of renewable energy sources.

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A renewable energy system converts the energy found in sunlight, wind, falling-water, sea waves, geothermal heat, or biomass into a form, we can use such as heat or electricity. Most of the renewable energy comes either directly or indirectly from sun and wind and can never be exhausted, and therefore they are called renewable. However, most of the world’s energy sources are derived from conventional sources-fossil fuels such as coal, oil, and natural gases. These fuels are often termed non-renewable energy sources. Although, the available quantity of these fuels are extremely large, they are nevertheless finite and so will in principle ‘run out’ at some time in the future. Renewable energy is derived from resources like the sun and the wind that can easily be replenished. Non-renewable resources are energy sources like petroleum, natural gas, coal and nuclear energy that take millions of years to form. They cannot be recreated over a short period of time. Renewable energy sources are essentially flows of energy, whereas the fossil and nuclear fuels are, in essence, stocks of energy.

Following are examples of renewable energy and their resources:

Solar Energy Energy that is produced from the sun whether it is in the form of sunlight particles that can create electricity (solar electricity or photovoltaics) or in the form of heat to warm water or air space.

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Solar energy is the most readily available and free source of energy since prehistoric times. It is estimated that solar energy equivalent to over 15,000 times the world’s annual commercial energy consumption reaches the earth every year. India receives solar energy in the region of 5 to 7 kWh/m2 for 300 to 330 days in a year. This energy is sufficient to set up 20 MW solar power plant per square kilometre land area. Solar energy can be utilised through two different routes, as solar thermal route and solar electric (solar photovoltaic) routes. Solar thermal route uses the sun’s heat to produce hot water or air, cook food, drying materials etc. Solar photovoltaic uses sun’s heat to produce electricity for lighting home and building, running motors, pumps, electric appliances, and lighting. Low-grade solar thermal devices are used in solar water heaters, air-heaters, solar cookers and solar dryers for domestic and industrial applications.

Solar Cooker Solar cooker is a device, which uses solar energy for cooking, and thus saving fossil fuels, fuel wood and electrical energy to a large extent. However, it can only supplement the cooking fuel, and not replace it totally. It is a simple cooking unit, ideal for domestic cooking during most of the year except during the monsoon season, cloudy days and winter months. Solar Photovoltaic (PV): Photovoltaic is the technical term for solar electric. Photo means “light” and voltaic means “electric”. PV cells are usually made of silicon, an element that naturally releases electrons when exposed to light. Amount of electrons released from silicon cells depend upon intensity of light incident on it. The silicon cell is covered with a grid of metal that directs the electrons to flow in a path to create an electric current. This current is guided into a wire that is connected to a battery or DC appliance. Typically, one cell produces about 1.5 watts of power. Individual cells are connected together to form a solar panel or module, capable of producing 3 to 110 Watts power. Some applications for PV systems are lighting for commercial buildings, outdoor (street) lighting, rural and village lighting etc. Solar electric power systems can offer independence from the utility grid and offer protection during extended power failures. Solar PV systems are found to be economical especially in the hilly and far flung areas where conventional grid power supply will be expensive to reach.

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Case Study Under the Solar Photovolatic, Water Pumping Programme of the Ministry of Nonconventional Energy Sources during 2000-01 the Punjab Energy Development Agency (PEDA) has completed installation of 500 solar pumps in Punjab for agricultural uses. Under this project, 1800 watt PV array was coupled with a 2 HP DC motor pump set. The system is capable of delivering about 140,000 litres water everyday from a depth of about 6–7 metres. This quantity of water is considered adequate for irrigating about 5–8 acres land holding for most of the crops.

Wind Power Energy that is produced from the natural movement of the wind; also considered a form of solar energy because wind is created by differences in the amount of heat that the sun sends to different parts of the earth. Table 4.4 Advantages • Nonpolluting

Disadvantages • High initial investment

• Most abundant energy source available • Dependent on sunny weather • Systems last 15-30 years

• Supplemental energy may be needed in low sunlight areas • Requires large physical space for PV cell panels • Limited availability of polysilicon for panels

Wind energy is basically harnessing of wind power to produce electricity. The kinetic energy of the wind is converted to electrical energy. When solar radiation enters the earth’s atmosphere, different regions of the atmosphere are heated to different degrees because of earth curvature. This heating is higher at the equator and lowest at the poles. Since air tends to flow from warmer to cooler regions, this causes what we call winds, and it is these airflows that are harnessed in windmills and wind turbines to produce power. Wind power is not a new development as this power, in the form of traditional windmills for grinding corn, pumping water, sailing ships - have been used for centuries. Now wind power is harnessed to generate electricity in a larger scale with better technology. Wind electric generator (WEG) converts kinetic energy available in wind to electrical energy by using rotor, gear box and generator. There

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are a large number of manufacturers for wind electric generators in India who have foreign collaboration with different manufacturers of Denmark, Germany, Netherlands, Belgium, USA, Austria, Sweden, Spain and U.K. etc. At present, WEGs of rating ranging from 225 kW to 1000 kW are being installed in our country.

Hydropower Energy that is produced from moving or falling water The potential energy of falling water, captured and converted to mechanical energy by waterwheels, powered the start of the industrial revolution. Wherever sufficient head, or change in elevation, could be found, rivers and streams were dammed and mills were built. Water under pressure flows through a turbine causing it to spin. The Turbine is connected to a generator, which produces electricity. Micro (up to 100 kW) mini hydro (101-1000 kW) schemes can provide power for farms, hotels, schools and rural communities, and help create local industry. Table 4.5 Advantages

Disadvantages

• No emissions

• Environmental impacts by changing the environment in the dam area

• Reliable

• Hydroelectric dams are expensive to build

• Capable of generating large amounts of power

• Dams may be affected by drought

• Output can be regulated to meet demand

• Potential for floods

Biomass Energy Energy that comes from materials that were once living like plants or some types of garbage. Table 4.6 Advantages

Disadvantages

• Abundant supply

• Source must be near usage to cut transportation cos

• Fewer emissions than fossil fuel sources

• Emits some pollution as gas/liquid waste

• Can be used in diesel engines

• Increases nitrogen oxides, an air pollutant emission

• Auto engines easily convert to run on • Uses some fossil fuels in conversion biomass fuel

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Biomass is a renewable energy resource derived from the carbonaceous waste of various human and natural activities. It is derived from numerous sources, including the by-products from the wood industry, agricultural crops, raw material from the forest, household wastes etc. Biomass does not add carbon dioxide to the atmosphere as it absorbs the same amount of carbon in growing as it releases when consumed as a fuel. Its advantage is that it can be used to generate electricity with the same equipment that is now being used for burning fossil fuels.

Biogas Plants Biogas is a clean and efficient fuel, generated from cow-dung, human waste or any kind of biological materials derived through anaerobic fermentation process. The biogas consists of 60% methane with rest mainly carbon dioxide. Biogas is a safe fuel for cooking and lighting. By-product is usable as high-grade manure. Biomass is an important source of energy and the most important fuel worldwide after coal, oil and natural gas. Bio-energy, in the form of biogas, which is derived from biomass, is expected to become one of the key energy resources for global sustainable development. Biomass offers higher energy efficiency through form of Biogas than by direct burning.

Geothermal Energy Energy that comes from heat generated deep inside the Earth from items like hot rocks, hot water and steam. This geothermal energy originates from the original formation of the planet, from radioactive decay of minerals, and from solar energy absorbed at the surface. Geothermal power is cost effective, reliable, sustainable, and environmentally friendly. The Earth’s geothermal resources are theoretically more than adequate to supply humanity’s energy needs, but only a very small fraction may be profitably exploited. Drilling and exploration for deep resources is very expensive.

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It has been used for bathing since Paleolithic times and for space heating since ancient Roman times, but is now better known for generating electricity. A part of direct geothermal heating capacity is installed for district heating, space heating, spas, industrial processes, desalination and agricultural applications. Geothermal electric capacity in the United States is over 3,000 MW. Geothermal power plants use high temperatures deep underground to produce steam, which then powers turbines that produce electricity. Geothermal power plants can draw from underground reservoirs of hot water or can heat water by pumping it into hot, dry rock. High underground high temperatures are accessed by drilling wells, sometimes more than a mile deep. There is a certain environmental risk connected with the use of geothermal heat, namely, hot water from geothermal sources holds dissolved gases and sometimes small amounts of toxic chemicals like mercury, arsenic, boron and antimony. Table 4.7 Advantages

Disadvantages

Minimal environmental impact

• Geothermal fields found in few areas around the world

Power plants have low emissions

• Wells could eventually be depleted

Low cost after initial investment

Geothermal power requires no fuel (except for pumps), and is therefore immune to fuel cost fluctuations, but capital costs are significant. Drilling accounts for over half the costs, and exploration of deep resources entails significant risks.

Ocean Energy Oceans cover more than 70% of Earth’s surface, making them the world’s largest solar collectors. Ocean energy draws on the energy of ocean waves, tides, or on the thermal energy (heat) stored in the ocean. The sun warms the surface water a lot more than the deep ocean water, and this temperature difference stores thermal energy. The ocean contains two types of energy: thermal energy from the sun’s heat, and mechanical energy from the tides and waves. Ocean thermal energy is used for many applications, including electricity generation. There are three types of electricity conversion systems: closed-cycle, open cycle and hybrid. Closed cycle systems use the ocean’s warm surface water to vaporise a working fluid, which has a low boiling point, such as ammonia. The vapour expands and turns a turbine. The turbine then activates a generator to produce electricity. Open-cycle systems actually boil the seawater by operating

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at low pressures. This produces steam that passes through a turbine/ generator. The hybrid systems combine both closed-cycle and opencycle systems. Ocean mechanical energy is quite different from ocean thermal energy. Even though the sun affects all ocean activity, tides are driven primarily by the gravitational pull of the moon, and waves are driven primarily by the winds. A barrage (dam) is typically used to convert tidal energy into electricity by forcing the water through turbines, activating a generator. Tidal electricity generation involves the construction of a barrage across an estuary to block the incoming and outgoing tide. The head of water is then used to drive turbines to generate electricity from the elevated water in the basin as in hydroelectric dams. A tidal range of at least 7 m is required for economical operation and for sufficient head of water for the turbines. Following are examples of non-renewable energy and their resources: Over 85% of the energy used in the world is from non-renewable supplies. Most developed nations are dependent on non-renewable energy sources such as fossil fuels (coal and oil) and nuclear power.

Nuclear Power In most electric power plants, water is heated and converted into steam, which drives a turbine-generator to produce electricity. Fossilfueled power plants produce heat by burning coal, oil or natural gas. In a nuclear power plant, the fission of uranium atoms in the reactor provides the heat to produce steam for generating electricity. Originally, nuclear energy was expected to be a clean and cheap source of energy. Nuclear fission does not produce atmospheric pollution or greenhouse gases and it proponents expected that nuclear energy would be cheaper and last longer than fossil fuels. Unfortunately, because of construction cost overruns, poor management, and numerous regulations, nuclear power ended up being much more expensive than predicted. The nuclear accidents at Three Mile Island in Pennsylvania and the Chernobyl Nuclear Plant in the Ukraine raised concerns about the safety of nuclear power. Furthermore, the problem of safely disposing spent nuclear fuel remains unresolved. The United States has not built a new nuclear facility in over twenty years, but with continued energy crises across the country that situation may change.

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Table 4.8 Advantages

Disadvantages

• No greenhouse gases or CO2 emissi- • Higher capital costs due to safety, emergency, ons containment, radioactive waste and storage systems • Efficient at transforming energy into • Problem of long-term storage of radioactive waste electricity • Refueled yearly (unlike coal plants that • Heated waste water from nuclear plants harms need trainloads of coal every day) aquatic life

Coal Coal is the most abundant fossil fuel in the world with an estimated reserve of one trillion metric tons. Most of the world’s coal reserves exist in Eastern Europe and Asia, but the United States also has considerable reserves. Coal formed slowly over millions of years from the buried remains of ancient swamp plants. During the formation of coal, carbonaceous matter was first compressed into a spongy material called “peat”, which is about 90% water. As the peat became more deeply buried, the increased pressure and temperature turned it into coal. Different types of coal resulted from differences in the pressure and temperature that prevailed during formation. The softest coal (about 50% carbon), which also has the lowest energy output, is called lignite. Lignite has the highest water content (about 50%) and relatively low amounts of smog-causing sulfur. With increasing temperature and pressure, lignite is transformed into bituminous coal(about 85% carbon and 3% water). Anthracite (almost 100% carbon) is the hardest coal and also produces the greatest energy when burned. Less than 1% of the coal found in the United States is anthracite. Most of the coal found in the United States is bituminous. Unfortunately, bituminous coal has the highest sulfur content of all the coal types. When the coal is burned, the pollutant sulfur dioxide is released into the atmosphere. Table 4.9 Advantages

Disadvantages

• Abundant supply

• Emits major greenhouse gases/acid rain

• Currently inexpensive to extract

• High environmental impact from mining and burning, although clearer coal-burning technology is being developed

• Reliable and capable of generating large • Mining can be dangerous for miners amounts of power

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Petroleum Crude oil or liquid petroleum, is a fossil fuel that is refined into many different energy products (e.g. gasoline, diesel fuel, jet fuel, heating oil). Oil forms underground in rock such as shale, which is rich in organic materials. After the oil forms, it migrates upward into porous reservoir rock such as sandstone or limestone, where it can become trapped by an overlying impermeable cap rock. Wells are drilled into these oil reservoirs to remove the gas and oil. Over 70% of oil fields are found near tectonic plate boundaries, because the conditions there are conducive to oil formation. Table 4.10 Advantages • Efficient transportation fuel for the world

Disadvantages • High CO2 emissions

• Basis of many products, from prescription • Supply may be exhausted before natural gas/ drugs to plastics coal resources • Easy to transport

• Possible environmental impact from drilling/ transporting

Urban Problems Related to Energy The problems depends upon the types of energy supply. In the case of wood and charcoal, deforestation is the impact at the regional level while health and safety are affected during the conversion process of biomass into charcoal. The supply processes of petroleum products and natural gas cause land degradation and sulphur emissions at the local level and land/sea spills at the regional level. The conversion processes can lead to global warming through CO2 emissions. Firewood, charcoal, coal and petroleum products all have negative environmental impacts due to emission of particulates, CO2, CO, SO2 at the household, neighbourhood, local and regional levels, depending upon the type of fuels. For example, in purely weight terms, the most important sources of emissions in Delhi are: CO from charcoal (used by industries), and from kerosene (households), and particulates from coal (used by industries). On the other hand, results from Ankara indicate that particulate and SO2 emissions are primarily householdbased, while hydrocarbons, NO and CO are vehicle-generated. The dependence of urban transport on road motor vehicles fuelled by gasoline and diesel oil leads to increasing air pollution. Transport in developing countries contributes to about 30% of the global transportrelated emissions of CO2, NOx and hydrocarbons, and in much higher

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percentage to the emissions of lead, SOx and diesel particulate. It has also about 20% share in the emission of CO2 - a gas mainly responsible for greenhouse effect. The extraction and conversion processes of coal lead to water pollution, respiratory ailments and land degradation at the local level. Electricity generation from hydro affect river ecosystems at the regional level and displacement of populations, etc. at the local level. Nuclear energy generation leads to mine wastes at the local level and fuel cycle radiation at the regional level. Nuclear waste storage poses environmental threats that have local, regional and global connotations. The impact of power plants located in urban areas, can be serious at the local level as a result of the emission of pollutants leading to deterioration of air quality and health hazards affecting concentrated population. Despite the seemingly gloomy picture of deforestation, with economic growth, urban consumers usually make the transition from biofuels to commercial fuels, thus reducing fuel-related pressure on peri-urban forest resources. The change-over could be even more environmentally beneficial if power generation, industry and the transport sectors were to use natural gas. LAND RESOURCES

Land as a Resource Land resource is our basic resource. Land may be defined as a physical environment consisting of relief, soil, hydrology, climate and vegetation in so far as they are determined by the land use. Value of land depends on its size, location, distance from the market and nature of potential use besides productivity. Land systems function through general capabilities of soils that are important for various agricultural, environmental, nature protection, landscape architecture and urban applications. It is useful to us as a source of food, as a place to live, work and play. It has different roles. It is a productive economic factor in agriculture, forestry, grazing, fishing and mining. It is considered as a foundation of social prestige and is the basis of wealth and political power. It has many physical forms like mountains, hills, plains, lowlands and valleys. It is characterised by climate from hot to cold and from humid to dry. Similarly, land supports many kinds of vegetation. In a wide sense, land includes soil and topography along with their physical

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features of a given location. It is in this context that land is defined closely with natural environment. However, it is also regarded as space, situation, and factor of production in economic processes. The upper thin layer of land surface in the form of thin creamy layer of birthday cake is the most favourable medium for plant growth. Plant anchors and draws nutrients and water from this layer. Soil in this layer performs a number of ecosystem services like storage, decomposition, transformation, and detoxification and thereby provides right soil condition for crop/plant growth. Numbers of biogeochemical cycles like carbon, nitrogen, phosphorus and sulfur cycles are being operated and nutrients are being released for plant and soil organisms and thus biomass production are sustained in the earth. Earthworms are another vital species, because they help in the decomposition of organic matter in the soil, as well as improving vital functions such as aeration, water infiltration, and drainage. Soils provides a platform for manmade structures like buildings, road, highways, mall, multiplex etc. It is the platform for civil and engineering works. India is well endowed with cultivable land which has long been a key factor in the country’s socio-economic development. In terms of area, India ranks seventh in the world, while in terms of population it ranks second. With a total area of 328 million hectares, India is one of the big countries. The physical features in India are diverse and complex. There are mountains, hills, plateaus and plains which produce varied human response to the use of land resources. About 30% of India’s surface area is covered by hills and mountains. About 25% of this land is topographically usable which is scattered across the country. LAND DEGRADATION Land degradation, defined as lowering and losing of soil functions, is becoming more and more serious worldwide in recent days, and poses a threat to agricultural production and terrestrial ecosystem. Land degradation includes loss of top soil, physical changes like damage of soil structure (compaction), chemical changes like salinisation, sodification, acidification, deposition of heavy metals and an overall declination of fertility and productivity of soil. It is estimated that nearly 2 billion ha of soil resources in the world have been degraded which includes approximately 22% of the total cropland, pasture, forest, and woodland. Though climatic and geogenic processes are major

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driving forces for land degradation, the impact of anthropogenic factors cannot be overruled particularly when local situations are taken into consideration. Among the anthropogenic processes, agriculture, industrialisation and urbanisation all contribute significantly. Agricultural activities like tillage disintegrates soil structure, causes organic matter depletion encourages soil erosion and nutrient loss. However, tillage practices improve soil air and modify temperatures for seed germinations and microbial activities. Heavy traffic load of tillage implements causes soil compaction. Overirrigation and application of poor quality of irrigation water lead to problems like water logging and soil salinisation. Injudicious application of chemical fertilizers of nitrogen and phosphorus fertilizers and the concentration of livestock and their manures within small areas, have not only causes chemical degradation of agricultural land but also substantially increased the pollution of surface water by run-off and groundwater by leaching of excess nitrogen (as nitrate). Other agricultural chemicals like herbicides and pesticides causes contamination of surface as well as groundwater. The industrial wastes contribute largely to the chemical degradation of the valuable land resources. Improper waste management renders the surrounding areas vulnerable to heavy metal deposition in soil, waterbodies, rivers as well as ground water. Rapid urbanisation also aggravates the problem of land degradation still further. Severe erosion of the productive top soil through wind and water action is aggravated by intensive mining, deforestation, improper range land management as well as injudicious tillage practices in agricultural fields. Besides that a sizeable amount of loss of top has been has been attributed to brick making and pottery affecting the livelihood of many traditional communities. It is important to note that it takes centuries to replenish 2.5 cm of top soil. Causes of land degradation include: 1. Clearance of vegetative cover. 2. Soil erosion by wind or water. 3. Natural conditions e.g., soil type, topography (e.g. steep gradient), weather/climatic conditions e.g., high intensity rainfall, natural hazards. 4. Invasive species. 5. Pollution. 6. Drought i.e., precipitation is significantly lower than average recorded levels for a prolonged period.

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7. Unsustainable agricultural practices. 8. Habitat alteration e.g., urban expansion. Resultant effects include: 1. Decline in the chemical, physical and/or biological properties of soil e.g., lower organic content and nutrient levels, salinisation, pH changes in soil (acidification or alkalinisation) 2. Reduced availability of potable water 3. Lessened volumes of surface water 4. Depletion of aquifers due to lack of recharge 5. Impacts on livestock and agriculture e.g., loss of animals due to dehydration, reduced yields 6. Water and food insecurity, famine 7. Biodiversity loss 8. General reduction of the ability for the community to depend on the natural environment for livelihood 9. Decline in economic productivity and national development 10. Conflict over access to resources 11. Mass migration Degradation encompasses deforestation (tropical and temperate forests) and desertification of drylands (arid, semi-arid and subhumid regions). Almost 75% of the drylands in Latin America and the Caribbean are under moderate to severe desertification.

Man-Induced landslides Landslides belong to a group of geological processes referred to as mass movement: mass movement involves the outward or downward movement of a mass of slope forming material, under the influence of gravity. Landslide forms are distinguishable from other forms of mass movement by the presence of distinct boundaries and rates of movement perceptibly higher than any movement experienced on the adjoining slopes.

Types of Landslides The form and scope of landslides are very diverse and consequently many classifications can be considered. Criteria generally used to distinguish different types of landslide include: the movement mechanism(e.g. fall, topple, slide, spread and flow), the nature of the slope material involved(rock, debris, earth), the form(curved or

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planar) of the surface of rupture, the degree of disruption of the displaced mass, the rate of movement.

Causes of Landslides The causes of landslides are thus generally multiple, a conjunction or superimposition of several factors. Causes are also often divided into two large categories: internal causes and external causes. Internal causes are related to resisting forces. They lead to the failure of the slope without the intervention of perceptible changes on the surface; they are in fact causes which reduce the material’s shear strength. The internal causes which condition the stability of a slope are Geological factors, Morphological features and Climatic conditions. External causes are related to driving forces (e.g. gravity, water through flow, pressure). They determine an increase of the shear stresses by means of more or less evident modifications of slope morphology. Among these processes the following are particularly important: Undercutting due to the erosion of a watercourse or to the excavation for road construction, Exploitation of quarries or open pits, Overloading, Removal of lateral support, Lateral pressure, Tectonic activity, Effect of vegetation.

Man-made Causes • • • • • • • •

Excavation (particularly at the toe of slope Loading of slope crest Draw-down (of reservoir) Deforestation Irrigation Mining Artificial vibrations Water impoundment and leakage from utilities

Consequences of Landslides Landslide hazard is generally neglected with respect to other types of hazards such as of their diversity, their frequency and their wide geographic distribution.

Mitigatory Measures In general the chief mitigatory measures to be adopted for such areas are:

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• Drainage correction, • Proper land use measures, • Reforestation for the areas occupied by degraded vegetation and • Creation of awareness among local population.

Case Study One of the worst tragedies took place at Malpa Uttarkhand (UP) on 11th and 17th August, 1998 when nearly 380 people were killed when massive landslides washed away the entire village. This included 60 pilgrims going to Lake Mansarovar in Tibet. Consequently various land reform measures have been initiated as mitigation measures. The two regions most vulnerable to landslides are the Himalayas and the Western Ghats. The Himalayas mountain belt comprise of tectonically unstable younger geological formations subjected to severe seismic activity. The Western Ghats and Nilgiris are geologically stable but have uplifted plateau margins influenced by neo-tectonic activity. Compared to Western Ghats region, the slides in the Himalayas region are huge and massive and in most cases the overburden along with the underlying lithology is displaced during sliding particularly due to the seismic factor.

Soil Erosion Soil erosion is the detachment, transport and deposition of soil particle on land surface - termed as loss of soil. It is measured as mass/unit area - tonne/ha or Kg/sq.m Causes of Soil Erosion- Human Induced and Natural Causes • Land use - Overgrazing by cattle, Deforestation, arable land use, faulty farming, construction, mining etc. • Agricultural use of land can also produce soil erosion. In developing countries, agricultural soil loss is still a major problem Climatic conditions: precipitation and wind velocity. • Soil: Soil characteristics - texture, structure, water retention and transmission properties. • Hydrology: Infiltration, surface detention, overland flow velocity and subsurface water flow. Land forms: Slope gradient, slope length and shape of slope.

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Erosion Factors The vulnerability of a field to soil erosion is dependent on a number of factors: • The climatic conditions of the area. • The proportion of sand, silt and clay sized particles in a particular soil. • The organic matter level. • The water permeability of the soil. • The length and slope of the field. • Amount of crop rotation. • Direction of cultivation.

Calculation of Erosion Rates Soil conservationists around the world use the Universal Soil Loss Equation to estimate soil erosion rates by water. The equation provides an estimate of the Soil Loss Rate in Tonnes/hectare/year. This estimate can be used for soil conservation planning. The Universal Soil Loss Equation is: A = KR(LS) CP where A = Estimate of the Soil loss rate in Tons/ha/year K = Soil erodibility factor R = Rainfall factor LS = Length/Slope factor C = Crop management factor P = Support Practice factor

On-site Impacts of Soil Erosion 1. Reduction in soil quality resulting from (a) Loss of the nutrientrich upper layers of the soil (b) Reduced water-holding capacity of many eroded soils. 2. Increased use of artificial fertilizers can mitigate the first problem in developed countries. 3. Not an option in most developing countries. 4. On-site impacts of soil erosion are a present-day problem for many of the developing nations.

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Off-site Impacts of Soil Erosion 1. Water erosion’s main off-site effect is the movement of sediment and agricultural pollutants into watercourses. 2. Landslide is a general term for the results of rapid downslope movement of geologic material (rock, dirt, sand). 3. Rock Slides Most rock slides often involve movement along a bedding plane between layers of sedimentary rocks. 4. In the U.S., landslides cause over $1.5 billion in property damage and 25-50 deaths per year.

Protection It is vegetation that keeps soil from eroding. This is because soil is usually covered with shrubs and trees, by dead and decaying matter or by a thick mat of grass. The root systems of plants is able to hold the soil together. Plants slow down water as it flows over the land and it allows much of the rain to soak into the ground. Plants also break the impact of a raindrop before it hits the soil. This reduces water erosion. When this covering is stripped away through deforestation, overgrazing, ploughing and fire, soil erosion is greatly accelerated. Overcultivation and compaction cause the soil to lose its structure and cohesion and it becomes more easily eroded. Soils with high clay content are more cohesive and allow soil particles to stick together. Soil with more clay are less vulnerable to erosion than soil with high sand or silt content.

Prevention There are a number of other conservation practices which can be used by farmers. Any single conservation practice can significantly decrease soil erosion rates. Combining a number of soil conservation practices is often more effective. Making sure there are always plants growing on the soil and that the soil is rich in organic matter are two key methods in prevention. Organic matter binds soil particles together which reduces erosion. Organic matter in soil can be increased with crop rotation or by incorporating organic fertilizers. Crop rotation is also effective at enhancing soil structure. There are also many other methods used by farmers to reduce soil erosion. Mulching is one example. It involves spreading hay or straw over a field as a substitute for a cover crop.

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DESERTIFICATION It can be defined as ‘the diminution or destruction of the biological potential of the land which can ultimately lead to desert like conditions’. The arid and semi-arid areas where climate is dry, restoration is very slow, mining and overgrazing etc., adds to several other desertification pressures. Desertification is a systemic phenomenon resulting from excessive felling of trees which manifests itself in the loss of soil fertility, high wind velocity, low precipitation, increasing aridity and extremes of temperatures in the affected area. This can happen in any climatic zone or ecosystem, resulting from exploitative interaction of man with the natural ecosystem. Most of the deserts of recent origin have resulted form any one or more of the following human activities. (i) Uncontrolled and overexploitation of grazing land, indiscriminate cutting of trees and forest resources leading to drought, soil erosion, deterioration of soil fertility which results in stunted plant growth. (ii) Excessive mining in arid and semi-arid regions for extraction of minerals, coal or limestone resulting in loss of trees, and green cover, and leading to total destruction of conditions conducive to vegetation growing. (iii) Uneconomic land use for agriculture by cultivation on marginal lands affecting adjacent fertile lands and causing soil erosion. (iv) Intensive and uneconomic exploitation of water resources leading to fall in water table, seepage and problems of excessive salinisation of soil. Desertification is a truly worldwide phenomenon and a major threat to humankind. “Desertification” means land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic variations and human activities.

Extent of Desertification About 76.15% of the total Indian desert area has resulted from manmade desertification process. Another 19.5% of the total area is subjected to medium or slight desertification. This area is concentrated mostly along the eastern Rajasthan in the north-east to southwest zone parallel to the foothills of Aravalis. Most of the deserts, in India are found in the states of Rajasthan and Western Gujarat, where about

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23.8 mha area has been affected by desertification. About 4.34% of this area lies in the extreme West of Rajasthan in Jaisalmer district. This desert is concentrated along a belt in Ganganagar, Churu, Bikaner, Jaisalmer, Barmer, Jodhpur, Jalore, Jhunjhunu and Nagaur districts. The predominant processes of desertification in this belt are the expansion of sand cover and shifting sand dunes by wind erosion.

Thar Desert—A case study The Thar desert exhibited spectacular biological diversity because of its evolutionary history and geographical location. This is a extensive region of sandy desert in north-western India and eastern Pakistan. The Thar desert is about 805 km long and about 485 km wide. Rainfall is sparse averaging from 127 to 254 mm annually and temperature rises as high as 52.8°C in July.

Measures designed to combat desertification directly and to promote sustainable management of natural resources (a) (b) (c) (d) (e)

Erosion control. Conservation and sustainable use of land resources. Rehabilitation of degraded land. Better land, water and river basin management. Establishment of sustainable irrigation facilities to secure stable water supplies. (f) Sustainable forest management and effective reforestation programmes (g) Use of modern and safe bio-technologies to disseminate droughtresistant species.

CHAPTER

5 Chemistry of Environment

“We do so much to prepare our children for the future, but are we doing enough to prepare the future for our children”? --Larry Chalfan WHAT IS GREEN CHEMISTRY ? Green chemistry is a revolutionary “Green chemistry is the utilisation philosophy that seeks to unite of a set of principles that reduces or gover nment, academic and induseliminates the use or generation of trial communities by placing more hazardous substances in the design, focus on environmental impmanufacture and application of acts at the earliest stage of innovchemical products”. ation and invention. This approach requires an open and interdisciplinary view of material and product design, applying the prin-ciple that it is better to consider waste prevention options during the design and development phase, rather than disposing or treating waste after a process or material has been developed. Environmentally benign alternatives to current materials and technologies must be systematically introduced across all types of manufacturing to promote a more environmental and economically sustainable future. Green chemistry is the design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances. Green chemistry can be defined as the practice of chemical science and manufacturing in a manner that is sustainable, safe, and nonpolluting and that consumes minimum amounts of materials and energy while producing little or no waste material. The practice of green chemistry begins with recognition that the production, processing, use, and eventual disposal of chemical products may cause harm when performed incorrectly. In accomplishing its objectives, green chemistry and green chemical engineering may modify or totally redesign chemical products and processes with the objective of minimising wastes and the use or generation of particularly dangerous materials.

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Environmental Chemistry

NEED OF GREEN CHEMISTRY Green chemistry represents a major paradigm shift that focuses on environmental protection at the design stage of product and manufacturing processes. It is an innovative way to deal with chemicals before they become hazards, with the goal of making chemicals and products “benign by design”. Green chemistry is a preemptive strategy that reduces the use of toxic substances before they contaminate the environment and our bodies. It is a marked departure from the past where society managed industrial and municipal wastes by disposal or incineration. Green chemistry seeks to dramatically reduce the toxicity of chemicals in the first place, rather than merely manage their toxic waste after use and disposal. TWELVE PRINCIPLES OF GREEN CHEMISTRY 1. Prevention: It is better to prevent waste than to treat or clean up waste after it has been created. 2. Atom Economy: Synthetic methods should be designed to maximise the incorporation of all materials used in the process into the final product. 3. Design Less Hazardous Chemical Synthesis: Wherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to human health and the environment. 4. Design Safer Chemicals: Chemical products should be designed to effect their desired function while minimising their toxicity. 5. Safer Solvents And Auxiliaries: The use of auxiliary substances (e.g. solvents, separation agents etc.) should be made unnecessary wherever possible and innocuous when used. 6. Design For Energy Efficiency: Energy requirements of chemical processes should be recognised for their environmental and economic impacts and should be minimised. If possible, synthetic methods should be conducted at ambient temperature and pressure. 7. Use of Renewable Feedstock: Use raw materials and feedstocks that are renewable rather than depleting. Renewable feedstocks are made from agricultural products or the wastes of other processes. Depleting feedstocks are made from fossil fuels (petroleum, natural gas or coal) or are mined. 8. Reduce Chemical Derivatives: Unnecessary derivatisation (use of blocking groups, protection/deprotection, temporary modification

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of physical/chemical processes) should be minimised or avoided if possible, because such steps require additional reagents and can generate waste. 9. Use catalysts, not stoichiometric reagents: Minimise waste by using catalytic reactions. Catalysts are used in small amounts and can carry out a single reaction many times. They are preferable to stoichiometric reagents, which are used in excess and work only once. 10. Design For Degradation: Chemical products should be designed so that at the end of their function they breakdown into innocuous degradation products and do not persist in the environment. 11. Real-Time Analysis For Pollution Prevention: Analytical methodologies need to be further developed to allow for real-time, inprocess monitoring and control prior to the formation of hazardous substances. 12. Inherently Safer Chemistry for Accident Prevention: Design chemicals and their forms (solid, liquid or gas) to minimise the potential for chemical accidents including explosions, fires, and releases to the environment.

Twelve Principles of Green Chemistry at a Glance Given by John Warner and Paul Anastas.(Table 5.1)

Green Chemistry Challenges • Processing Rapid, high yield transformations at room temperature– catalysis or self-assembly. • Design Better understanding of how molecular structure dictates desirable and undesirable properties. • Structure-Activity Relationships (SARs) • Hazardless, completely recyclable products • Feedstock “Waste” or renewable resources as raw materials. • Decision-making tools Metrics for comparing competing “greener” technologies w/r/t greenness, economics etc.

Concept of Atom Economy Atom economy means maximising the incorporation of material from the starting materials or reagents into the final product. It is essentially pollution prevention at the molecular level. Barry Trost of Stanford University developed the concept of atom economy in 1991. In 1998, he received the Presidential Green

Table 5.1 Examples of 12 principles of green chemistry

5.4 Environmental Chemistry

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5.5

Chemistry Challenge Award for his work. At the award ceremony, Paul Anderson (1997 ACS President) commented, “By introducing the concept of ‘atom economy’, Dr. Trost has begun to change the way in which chemists measure the efficiency of the reactions they design”. This novel approach proposed that as well as the important parameters of selectivity and yield; chemists should also consider how efficiently reactant atoms are utilised in chemical synthesis. In other words, what amounts of reactants end up in the desired product and what amounts are lost as by-products/wastes. The atom economy of a chemical reaction is a measure of the amount of starting materials that become useful products. Inefficient, wasteful processes have low atom economies. Efficient processes have high atom economies, and are important for sustainable development, as they use fewer natural resources and create less waste. The atom economy of a reaction can be calculated: Mass of desired product from equation % Atom economy = ____________________________________ × 100 Total mass of reactants froms equation Step-by-step: How to calculate atom economy? Step 1 Write down the balanced equation. Step 2 Calculate the relative molecular mass of each of the products. Step 3 Calculate the total mass of all the products (remember to account for any numbers in front of the symbols, e.g., 2 Fe2O3 + 3C Æ 4 Fe + 3 CO2). Step 4 Work out which of the products are wanted and calculate their mass (again, do not forget any numbers in front of the symbols). Apply the formula: Mass of desired product from equation % Atom economy = ____________________________________ × 100 Total mass of reactants froms equation ATOM ECONOMY IN CATALYTIC SYNTHESIS OF ETHYLENE OXIDE Mass of desired product from equation = 44 Total mass of reactants from equation = 44 % Atom economy = 44/44 × 100 = 100%

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Environmental Chemistry

ATOM ECONOMY IN IBUPROFEN SYNTHESIS Ibuprofen is the active ingredient in many analgesics and current production is well in excess of 13,000 tonnes per annum. Brand name products such as Nurofen, Brufen and Ibuleve, to name but a few, incorporate Ibuprofen to provide their analgesic action. In addition, ibuprofen is a member of the nonsteroidal anti-inflammatory (NSAI) group of drugs, which combat swelling and inflammation. The traditional synthesis of Ibuprofen was patented in the 1960’s by the Boots Company PLC, Nottingham. Until the early 1990’s, industrial synthesis of the drug was almost exclusively by the Boots methodology. The traditional six-step route to Ibuprofen is shown below.

Boots Company Ibuprofen Synthesis Step 1 Friedel crafts acylation. Acetic anhydride as the acylating agent, in the presence of stoichiometric quantities of aluminium trichloride. Step 2 Darzens condensation. The a-chloroester (5) is treated with sodium ethoxide (6) base to yield the a-chloroenolate (C)C=CO2C2H5) which reacts with 4, forming the epoxide, 7. Step 3 Glycidic acid rearrangement. Treatment of the epoxide species (7) with aqueous acid effects the rearrangement of the carbon skeleton, resulting in the aldehyde (9). Step 4 Oxime formation. The conversion of the aldehyde (9) into the oxime (11) is carried out using hydroxylamine (10). Step 5 Nitrile formation. The oxime species (11) readily loses water to form the corresponding nitrile.

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Step 6 Nitrile hydrolysis. The nitrile species is slowly hydrolysed (two water equivalents) to yield the desired product, Ibuprofen. Mass of desired product from equation % Atom economy = ____________________________________ × 100 Total mass of reactants from equation Mass of desired product from equation = 648 Total mass of reactants from equation = 206 % Atom economy = 206/648 × 100 = 32% A quick glance at the table clearly shows an imbalance heavily in favour of the ‘not utilised’ column. Every reagent used contributes to the waste stream and so the % atom economy of only 32% is to be expected. Steps 1 and 2, in particular, contribute almost 90% of the total mass of atoms not utilised. The number of steps, allied with the use of stoichiometric reagents, makes the Boots synthesis atom uneconomic. Until the early 1990’s, industrial synthesis of the compound was almost exclusively by the Boots route. However, the mid-eighties saw the patent expire on Ibuprofen and furthermore, approval from the Food and Drug Administration (FDA) was given for

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its over-the-counter use. With the potential economic rewards apparent, a number of companies sought to develop novel methodology for the synthesis of Ibuprofen. The BHC Company, a joint venture between the Boots Company and Hoescht Celanese (now Celanese) had the greatest success. In 1992, the company initiated full-scale production of Ibuprofen at its newly built plant in Texas. The various stages of the BHC process are outlined below.

BHC Company Ibuprofen Synthesis Step 1 Novel Friedel-Crafts acylation of isobutylbenzene (1). Ketone functionality introduced to give 4-isobutylacetophenone (3). Identical to the first step in the traditional synthesis, but with anhydrous HF as the acylation catalyst. HF also functions as solvent – product separation easier without use of co-solvent. >90% yield. Step 2 Catalytic hydrogenation of 4-isobutylacetophenone (3), forming 1-(4-isobutylphenyl) ethanol (5). Hydrogenation takes place in the liquid phase over a solid Raney Nickel catalyst. Ketone functionality in 3 reduced to secondary alcohol. Heterogeneous step, therefore easy separation of productcatalyst by simple filtration. 98% efficiency. Step 3 Catalytic carbonylation of 1-(4-isobutylphenyl) ethanol (5), forming Ibuprofen. Liquid phase carbonylation of 5 is achieved with

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CO in the presence of a soluble palladium catalyst. Ibuprofen is removed from the reaction mixture by vacuum distillation. 98% efficiency. • Anhydrous HF catalyst in Step 1 is virtually all recovered and reused. In the traditional synthesis, however, the acylation ‘catalyst’ is aluminium trichloride and is lost in the form of large quantities of aluminium trichloride hydrate waste. • Raney nickel catalyst in Step 2 is virtually all recovered and reused. The catalyst is formed by the action of sodium hydroxide on Ni-Al alloy (2Ni-Al + 2NaOH + 2H2O Æ 2Ni + 2NaAlO2 + 3H2). This highly active form of the metal functions as an extremely efficient hydrogenation catalyst, especially at low temperatures. • Palladium catalyst in Step 3 virtually all recovered and reused. Exists as a soluble complex Æ PdCl2(PPh3)2. This is a homogeneous step, usually applicable where high selectivity is critical and product-catalyst separation problems can be resolved. Mass of desired product from equation % Atom economy = ___________________________________ × 100 Total mass of reactants from equation Mass of desired product from equation = 206 Total mass of reactants from equation = 266 % Atom economy = 206/266 × 100 = 77% • Three steps, all catalytic, compared with six in traditional synthesis using stoichiometric quantities of auxiliary reagents and solvents. • More efficient in both environmentally (e.g. Step 1) and economically when compared with traditional synthesis. • The achievements of the BHC Company were recognised with the Kirpatrick Chemical Engineering Award in 1993 and in 1997, a Presidential Green Chemistry Challenge Award. TOOLS OF GREEN CHEMISTRY Green chemistry is a tool that has the potential to improve almost every single product and process in our material economy. Currently, many green products involve unintended trade-offs in their environmental footprints. Reducing the net environmental footprint requires a holistic life cycle approach. This involves addressing challenges related to what our products are made out of, how they are manufactured, and what happens to them when their useful life is over.

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Environmental Chemistry

Green chemistr y applies across the life cycle of a chemical product, including its design, manufacture, use and ultimate disposal. Green chemistry is also known as sustainable chemistry. Green chemistr y reduces pollution at its source by minimising or eliminating the hazards of chemical feedstocks, reagents, solvents and products (Fig. 5.1). This is unlike treating pollution after it is formed (also called Fig. 5.1 Tools of Green Chemistry remediation), which involves endof-the-pipe treatment or cleaning up of environmental spills and other releases. Remediation may include separating hazardous chemicals from other materials, then treating them so they are no longer hazardous or concentrating them for safe disposal. Most remediation activities do not involve green chemistry. Remediation removes hazardous materials from the environment; on the other hand, green chemistry keeps the hazardous materials out of the environment in the first place.

1. Green Starting Materials Green chemistry tries, when possible, to utilise benign, renewable feedstocks as raw materials. From the point view of green chemistry, combustion of fuels obtained from renewable feedstocks is more preferable than combustion of fossil fuels from depleting finite sources. For example, many vehicles around the world are fueled with diesel oil, and the production of biodiesel oil is a promising possibility. As the name indicates, biodiesel oil is produced from cultivated plants oil, e.g., from soya beans. It is synthesised from fats embedded in plant oils by removing the glycerine molecule (Fig. 5.2) — a valuable raw material for soap production.

Fig. 5.2 Synthetic Scheme for the Production of Biodiesel using Vegetable Oil as a Starting Material

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Biodiesel oil also can be obtained from wasted plant oils, e.g., oils used in restaurants. In the technological process, a potential waste product is transformed into valuable fuel. (Combusted biodiesel oil smells like fried potatoes.) The advantages of using biodiesel oil are obvious. It’s fuel from renewable resources and contrary to normal diesel oil, the combustion of biodiesel does not generate sulphur compounds and generally does not increase the amount of carbon dioxide in the atmosphere.

Fig. 5.3

Large amounts of adipic acid [HOOC(CH2)4 COOH] are used each year for the production of nylon, polyurethanes, lubricants and plasticizers. Benzene — a compound with convinced carcinogenic

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properties — is a standard substrate for the production of this acid. Chemists developed green synthesis of adipic acid using a less toxic substrate. Furthermore, the natural source of this raw material — glucose — is almost inexhaustible(Fig. 5.3). • Polymers from Renewable Resources: Polyhydroxyalkanoates (PHAs)- Fermentation of glucose in the presence of bacteria and propanoic acid (product contains 5-20% polyhydroxyvalerate)

2. Green Reagents reagents should be non-toxic, maximum atom economy and renewable resource, cheap and easily available, no toxic by-products. Disadvantages of phosgene • phosgene is highly toxic, corrosive • requires large amount of CH2Cl2 • polycarbonate contaminated with Cl impurities Advantages of polycarbonate • diphenylcarbonate synthesised without phosgene • eliminates use of CH2Cl2 • higher-quality polycarbonates

3. Green Reactions It is based on concept of “atom economy”. The chemical reaction processes should aim to incorporate all reactants in the final product. Chemical processes should aim to use and generate substances with minimal toxicity to human health and the environment. Modern chemists design reactions with the highest possible atom economy in order to minimise environmental impact.

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Traditional Synthesis of Ibuprofen O AICI3 +

IBu CHO

H

O

CHCO2C2H6

CICH2CO2C2H5

(CH3,CO2),O

C2H5ONa

IBu

CH NOH

H2NOH

H2O IBu C N

IBu

IBu CO2H

60% Waste

Ibuprofen

4. Green Methodologies Two ways • Green catalyst- Enzymes(Biocatalyst) Readily separated, Readily regenerated and recycled, Long service life, Very high rates, Robust to poisons, High selectivity, Mild conditions • Aqueous media There are many potential advantages for using water as a solvent for organic reactions: 1. Cost. Water is the cheapest solvent available on earth; using water as a solvent can make many chemical processes more economical. 2. Safety. Many organic solvents are flammable, potentially explosive, mutagenic, or carcinogenic. Water, on the other hand, is none of these.

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3. Synthetic efficiency. In many organic synthesis, it may be possible to eliminate the need for the protection and deprotection of functional groups and save many synthetic steps. Water-soluble substrates can be used directly. 4. Simple operation. In large industrial processes, isolation of the organic products can be performed by simple phase-separation. It is also easier to control the reaction temperature, since water has the largest heat capacities of all substances. 5. Environmental benefits. It may alleviate the problem of pollution by organic solvents since water can be recycled readily and is benign when released into the environment (when no harmful residue is present). 6. Potential for new synthetic methodologies. Compared to reactions in organic solvents, the use of water as a reaction solvent has been explored much less in organic chemistry. There are many opportunities to develop novel synthetic methodologies that have not been discovered before. Table 5.2 Classification of Enzymes Class

General description

Selected examples

1.

Oxidoreductases

Enzymes of this group catalyse oxidation-reduction reactions involving oxygenation or overall removal or addition of hydrogen atom equivalents.

Alcohol dehydrogenase Glucose oxidase Amino acid oxidase Cytochrome oxidase Catalase Peroxidase Steroid 11 b-monooxygenase

2.

Transferases

These enzymes mediate the transfer of a group, such as aldehydic or ketonic, acyl, sugar, phosphoryl, methyl or a sulphurcontaining one from one molecule to another.

Homocysteine methyltransferase Hexokinase Aryl sulphotransferase Transketolase Transaldolase Alanine aminotransferase

3.

Hydrolases

The range of functional groups hydrolysed by such enzymes is very broad. It includes esters, anhydrides peptides and others. C-O, C-N and C-C bonds may be cleared as well as some others.

Triacylglycerol lipase Pectinesterase Alkaline phosphatase Ribonuclease II Deoxyribonuclease I a-Amylase Cellulase a-D-Glucosidase Aminopeptidase Chymosin (rennin) Trypsin

4.

Lyases

The types of reactions catalysed are additions to, or formation of, double bonds such as C=C, C=O, C=N.

Pyruvate decarboxylase Citrate (pro-3S)-lyase Carbonate dehydratase Enolase Phenylalanine ammonia-lyase

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5.

Isomerases

A variety of isomerizations, including racemization, can be effected.

Methonine racemase Glutamate racemase Glucosaminephosphate isomerase (glutamine-forming) Xylose (glucose) isomerase Alanine racemase UDP glucose 4-epimerase S-Methylmalonyl-CoA mutase

6.

Ligases

These are often called synthetases, and catalyse the formation of C--O, C–S, C–N and C–C bonds with accompanying adenosine triphosphate (ATP) or other nucleoside triphosphate cleavage.

Glutathione synthetase D-Alanylalanine syntheiase Arginyl-tRNA synthetase 5, 10-Metheayltelrahydrofolate synthetase Carbamoyl-phosphate synthetase (ammonia) Pyruvate carboxylase

5. Green Chemical Products These products should be designed so that at the end of their application, the product does not persist in the environment, and it should breakdown into innocuous degradation products. • Consumable - compostable, biodegradable • Stays in Technical Loop - product of service, reusable, recyclable • Minimised hazard in product and manufacturing process. Hazard includes human health, safety and ecological harm.

Dichlorodiphenyltrichloroethane (DDT)- Non-Biodegradable pestcide

Diacylhydrazine-Biodegradable pesticide Biopesticides may include natural plant-derived products, which include alkaloids, terpenoids, phenolics and other secondary chemicals. Certain vegetable oils such as canola oil are known to have pesticidal properties.

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Examples of new “greener” synthetic methods with principles of Green Chemistry 1. Transformation of Aromatic and Aliphatic Alcohals in the Equivalent Carboxyic Acids and Ketones. Green Synthetic Method.

Various aromatic, aliphatic and conjugated alcohols were transformed into the corresponding carboxylic acids and ketones in good yields with aq 70% t-BuOOH in the presence of catalytic `amounts of bismuth(III) oxide. 2. Direct oxidation of methyl group in aromatic nucleus

A methyl group at an aromatic nucleus is oxidized directly to the corresponding carboxylic acid in the presence of molecular oxygen and catalytic hydrobromic acid under photoirradiation. ZERO WASTE TECHNOLOGY Zero waste is a philosophy that encourages the redesign of resource lifecycles so that all products are reused (Fig. 5.4). The process recommended is one similar to the way

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that resources are reused in nature. Zero waste is a goal that is ethical, economical, efficient and visionary, to guide people in changing their lifestyles and practices to emulate sustainable natural cycles, where all discarded materials are designed to become resources for others to use. Zero waste means designing and managing products and processes to systematically avoid and eliminate the volume and toxicity of waste and materials, conserve and recover all resources, and not burn or bury them. Implementing Zero waste will eliminate all discharges to land, water or air that are a threat to planetary, human, animal or plant health. Zero waste can represent an economical alternative to waste systems, where new resources are continually required to replenish wasted raw materials. It can also represent an environmental alternative to waste since waste represents a significant amount of pollution in the world. The term zero waste was first used publicly in the name of a company, Zero Waste Systems Inc (ZWS), which was founded by Ph.D., renown chemist Paul Palmer in the mid 1970s in Oakland, California.

Fig. 5.4

This definition of zero waste describes a so-called ‘whole-system approach’ to redesigning resource flows to minimise harmful emissions and to minimise resource use. It is also a unifying concept for a range of measures aimed at eliminating waste and challenging old ways of thinking. Zero waste can represent an economical alternative to waste systems, where new resources are continually required to replenish wasted

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raw materials. It can also represent an environmental alternative to waste since waste, represents a significant amount of pollution in the world. A special feature of zero waste as a design principle is that it can be applied to any product or process, in any situation or at any level. Thus it applies equally to toxic chemicals as to benign plant matter. It applies to the waste of atmospheric purity by coal burning or the waste of radioactive resources by attempting to designate the excesses of nuclear power plants as “nuclear waste”. All processes can be designed to minimise the need for discard, both in their own operations and in the usage or consumption patterns which the design of their products leads to. Zero waste can even be applied to the waste of human potential by enforced poverty and the denial of educational opportunity. It encompasses redesign for reduced energy wasting in industry or transportation and the wasting of the earth’s rainforests. It is a general principle of designing for the efficient use of all resources, however defined.

Corporate Initiatives An example of a company that has demonstrated a change in landfill waste policy is General Motors (GM). GM has confirmed their plans to make approximately half of its 181 plants worldwide “landfill-free” by the end of 2010. Companies like Subaru, Toyota, and Xerox are also producing landfill-free plants. GM is supposed to have about eighty producing plants twenty months. Furthermore, The United States Environmental Protection Agency (EPA) has worked with GM and other companies for decades to minimise the waste through its Waste Wise program. The goal for General Motors is finding ways to recycle or reuse more than 90% of materials by: selling scrap materials, adopting reusable parts boxes to replace cardboard, and even recycling used work gloves. The remainder of the scraps might be incinerated to create energy for the plants. Besides being nature friendly, it also saves money by cutting out waste and producing a more efficient production. All these organisations push forth to make our world clean and producing zero waste. CLEAN DEVELOPMENT MECHANISMS (CDM) Clean Development Mechanism(CDM) is a unique instrument based on understanding and cooperation among the nations for adopting

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a new outlook for economic activities aiming at protecting the world ecosystem (Fig. 5.5). • Accumulation of Carbon dioxide (CO2), Chloroflorocarbons (CFC), Methane (CH4) and Nitrous oxide (N2O) in the atmosphere cover the Greenhouse gases (GHG) • GHGs are accumulated in the atmosphere due to combustion of fossil fuels like coal, oil and natural gases etc. The Clean Development Mechanism (CDM), a cooperative mechanism established under the Kyoto Protocol, has the potential to assist developing countries in achieving sustainable development by promoting environmentally friendly investment from industrialised country governments and businesses. The 1997 Kyoto Protocol, a milestone in global efforts to protect the environment and achieve sustainable development, marked the first time that governments accepted legally-binding constraints on their greenhouse gas emissions. The Protocol also broke new ground with its innovative “cooperative mechanisms” aimed at cutting the cost of curbing these emissions.

CDM Objectives • To assist developing countries in achieving sustainable development and in contributing to ultimate objectives of United Nations Framework Convention on Climate Change (UNFCCC) • To assist developing countries in achieving compliance with their qualified emission limit and reduction commitments. Specifically, the CDM can contribute to a developing country’s sustainable development objectives through: • Transfer of technology and financial resources; • Sustainable ways of energy production; • Increasing energy efficiency and conservation; • Poverty alleviation through income and employment generation; and • Local environmental side benefits The drive for economic growth presents both threats and opportunities for sustainable development. While environmental quality is an essential element of the development process, in practice, there is considerable tension between economic and environmental objectives. Increased access to energy and provision of basic economic

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Fig. 5.5

services, if developed along conventional paths, could cause longlasting environmental degradation—-both locally and globally. But by charting a different course and providing the technological and financial assistance to follow it, many potential problems could be avoided. ENVIRONMENTAL IMPACT ASSESSMENT (EIA) It can broadly be defined as a study of the effects of a proposed project, plan or program on the environment. The legal, methodological and procedural foundations of EIA were established in 1970 by the enactment of the National Environmental Policy Act (NEPA) in the USA. At the international level, lending banks and bilateral aid agencies have EIA procedures that apply to borrowing and recipient countries. Most developing counties have also embraced and are in the process of formalising EIA through legislation. The paper highlights the evolution to current status, the legal framework, concepts, processes and principles of EIA and associated studies.

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A statement of actual or potential ipact of an actual or potential project or facility on a documented, measured, monitored environment. A very detailed study. Based on an environmental assessment (EA). Categorises the types and levies of effects identified or projected. Objectives: (1) Facilitate decisions: Reduce effects of an existing facility or continuing a proposed project. (2) Design and activate needed monitoring, mitigation and management activities. (3) Present viable option proposals. (4) Lead into an environmental impact report (EIR). EIAs are essential for projects resulting in a major change in land use or located in environmentally sensitive areas.

Environmental Impact Assessment Notification in India EIA is of comparatively recent origin in India and has become an integral part of Environmental Management by EIA notification of 1994 and its subsequent amendments by Ministry of Environment and Forests (MoEF), Govt. of India. The notification specifies 30 categories of projects with potential risks to degrade the Environment. EIA is the systematic, reproducible and interdisciplinary consideration of the potential effects of a proposed action and its reasonable alternatives on the physical, biological, cultural and socioeconomic attributes of a particular geographic area. Also it is a decision making process designed to help integrate economic, social and environmental concerns and of mitigating the adverse environmental impacts of activities related to projects, plans, programs or policies. The effect of pollutant can be divided into long-term (chronic) and short-term (acute) effects. Chronic pollution involved in the introduction of a toxic substance or other anthropogenic factor, often continuously and in fairly low levels, causing degradation of the environment.

EIA Study Objectives The objective of an EIA study is to encourage environmentally viable projects and to provide a second opportunity to the project proponent to rethink on: (a) Alternate production process with less pollutant discharge. (b) Cleaner production practices. (c) Data Collection for project specific environmental parameters. (d) Assessing the impacts on air, water, soil, biological components, natural and man-made components of the environment for technological alternatives wherever possible.

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Environmental Chemistry

(e) Appropriate Environment Management System(EMS) in a long term approach for industrial sustainability.

Nature of Projects • Clean coal and super critical thermal ultra mega power projects • Waste and corex energy generation steel projects • Dirty sponge iron projects • Wind energy projects • Small and large hydro projects • Waste to energy incinerator projects • Hydro fluorocarbon reduction projects • Paper and pulp

Advantages of EIA Though EIA is considered as a mandatory procedure for meeting the statutory requirements, it has many inbuilt advantages to the project proponent and to the society. Few of the advantages are: • More environmental sustainable design. • Better compliance with statutory standards. • Savings in capital and operating costs. • Reduced time and costs for obtaining clearances. • Avoid later plant adaptations. • Reduced health cost. • Increased project acceptance. ECO-FRIENDLY POLYMERS

Introduction Many of important current research problems and technological applications involve polymers. Living organisms are mainly composed of polymerized amino acids (proteins) nucleic acids (RNA and DNA), and other biopolymers. The most powerful computers - our brains - are mostly just a complex polymer material soaking in salty water. We are just making first small steps towards understanding of biological systems.

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Silk fiber is produced by silk worms in a cocoon, to protect the silkworm while it metamorphoses in a moth.

Polymer Molecules • Polymer molecules can be very large (macromolecules) • Most polymers consist of long and flexible chains with a string of C atoms as a backbone • Side-bonding of C atoms to H atoms or radicals • Double bonds are possible in both chain and side bonds • Repeat unit in a polymer chain (“unit cell”) is a mer • Small molecules from which polymer is synthesised is monomer. A single mer is sometimes also called a monomer.

Polymers – materials consisting of polymer molecules that consist of repeated chemical units (‘mers’) joined together, like beads on a string. Some polymer molecules contain hundreds or thousands of monomers and are often called macromolecules. The process by which this is achieved being known as polymerization. • Polymers may be natural, such as leather, rubber, cellulose or DNA, or synthetic, such as nylon or polyethylene. When all mers are the same, then the molecule is called a homopolymer. When there is more than one type of mer present then the molecule is a copolymer. • Mer units, that have 2 active bonds to connect with other mers are called bifunctional. • Mer units that have 3 active bonds to connect with other mers are called trifunctional. They form three-dimensional molecular network structures

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Environmental Chemistry

The physical characteristics of polymer material depend not only on molecular weight and shape, but also on molecular structure: 1. Linear polymers: This is a chain with two ends. van der Waals bonding between chains. Examples: polyethylene, nylon.

2. Branched polymers: with side chains or branches of significant length which are bonded to the main chain at branch points (or junction points). Chain packing efficiency is reduced compared to linear polymers - lower density

3. Cross-linked polymers: with three dimensional structures in which each chain is connected to all others by a sequence of junction points and other chains : said to be crosslinked “characterised by their crosslink density or degree of crosslinking (number of junction points per unit volume)” formed by polymerization or by linking together pre-existing linear chains (i.e. crosslinking) Chains are connected by covalent bonds. Often achieved by adding atoms or molecules that form covalent links between chains. Many rubbers have this structure.

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Stereoisomerism Stereoisomerism: Atoms are linked together in the same order, but can have different spatial arrangement 1. Isotactic configuration: all side groups R are on the same side of the chain.

2. Syndiotactic configuration: side groups R alternate sides of the chain.

3. Atactic configuration: the chain.

random orientations of groups R along

Copolymers (composed of different mers) Copolymers, polymers with at least two different types of mers, can differ in the way the mers are arranged: • statistical copolymers: in which the sequential distribution of the repeat units obeys known statistical laws • random copolymers: a special type of statistical copolymer in which the distribution of repeat units is truly random • alternating copolymers: only two different types of repeat unit arranged alternately along the polymer chain • block copolymers: linear copolymers in which the repeat units exist only in long sequences or blocks, of the same type : -A-A-A-A-A-A-A-A-B-B-B-B-B-B-B-B-B-: AB di-block copolymer -A-A-A-A-A-B-B-B-B-B-B-B-A-A-A-A-: ABA tri-block copolymer

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• graft copolymers: branched polymers in which the branches have a different chemical structure to that of the main chain statistical, random and alternating copolymers: properties intermediate to those of the corresponding homopolymers. • block and graft copolymers: properties characteristic of each of the constituent homopolymers

Polymers can be separated into 3 general categories on thermal stability: 1. Thermoplastic polymers 2. Thermosetting polymers 3. Elastomers

Thermoplastic Polymers–Thermoplastics (T-P) • Solid materials at room temperature but viscous liquids when heated to temperatures of only a few hundred degrees. • This characteristic allows them to be easily and economically shaped into products. • They can be subjected to heating and cooling cycles repeatedly without significant degradation.

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Thermosetting Polymers–Thermosets (T-S) • Cannot tolerate repeated heating cycles as thermoplastics can. • When initially heated, they soften and flow for molding. • But elevated temperatures also produce a chemical reaction that harden the materials into an infusible solid. • If reheated, thermosets degrade and char rather than soften.

Elastomers • Polymers that exhibit extreme elastic extensibility when subjected to relatively low mechanical stress. • Also known as rubbers. • Some Elastomers can be stretched by factor of 10 and yet completely recover to their original shape. • Although their properties are quite different from thermosets, the share a similar molecular structure that is different from the thermoplastics.

The Need for a Fully Degradable Plastic The need for a fully degradable plastic is pressing. Millions of tonnes of plastic waste, including refuse sacks, carrier bags and packaging, are buried in landfill sites around the world each year. China generates about 16 million tones, India 4.5 million tones and the U.K., 1 million tones, of which more than 800,000 tones is waste polyethylene. Other disposal routes are possible for these materials, such as recycling and incineration, but as much of the waste plastic is mixed up with other materials in the domestic and industrial waste streams, separation is costly particularly for small items such as carrier bags. Conventional polyethylene products can take longer than 100 years to degrade, taking up valuable landfill space and potentially preventing the breakdown of biodegradable materials contained, say, in a refuse such Symphony claims that its new plastic could effectively increase the capacity of landfill sites by as much as 20 to 30% by breakingdown in a short time and allowing other materials to degrade.

Mechanisms of Environmental Degradation in Polymers Polymers do not rust, but they can exhibit environmental degradation through various mechanisms. Two main types of degradation are:

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(1) End-chain scission (2) Random chain scission End-chain scission-degradation starts from the chain ends resulting in the release of monomer units (Fig. 5.6).

Fig. 5.6

Random chain scission takes place at any random point along the polymer chain. It results from homolytic bond-cleavage reactions at weak points in the polymer chains (Fig. 5.7).

Fig. 5.7 Random Chain Scission of Polyethylene

Factors Responsible for Degradation of Polymers Both chemical reactants and energy sources contribute to degradation of polymeric materials. Oxygen and water are two of the most important chemical reactants responsible for polymer deterioration. All polymers react with oxygen particularly under extreme conditions, i.e., at elevated temperatures, and some may oxidise even at low temperatures with

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time. Reaction with oxygen accounts for the vast majority of polymer failures occurring during service. This includes attack of ozone on unsaturated polymers under stress. Water reacts with certain polymers containing hydrolysable groups, such as ester and amide groups, and adversely affects important properties, polymer hydrolysis often being catalysed by traces of bases and acids. In addition to oxygen and water, there are many other chemicals to which polymers may be exposed during service. These include solvents, lubricating fluids, detergents and other foreign materials (Fig. 5.8).

Fig. 5.8 Major Causes and Types of Degradation in Polymers

Acceleration of degradation by heat is a general phenomenon responsible for deterioration of polymers either in the presence or absence of chemical reactants. Various forms of radiation and mechanical deformation can also contribute to polymer failure. The major types of degradation of polymers are described below.

Types of Polymer Degradation It is part of a larger group of degradation mechanisms for polymers that can occur from a variety of causes such as: 1. Heat (thermal degradation). 2. Thermo oxidative (thermal degradation and thermal oxidative degradation). 3. Light (photodegradation). 4. Photo oxidative. 5. Stress (Mechanical degradation). 6. Chemical agents (Chemical degradation). 7. Biological agents (Biodegradation).

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1. Thermal Degradation Heat is a major factor in polymer deterioration. Thermal degradation generally involves changes to the molecular weight (and molecular weight distribution) of the polymer and typical property changes include reduced ductility and embrittlement, Chalking, color changes and cracking. Thermal degradation causes chain scission and the reduced chain length reduces the molecular weight. Polyethylenes are also susceptible to thermal degradation and the resulting chain branching and cross-linking reduces the melt flow and produces embrittlement and color changes. PVC is also very susceptible to thermal degradation, particularly during processing. Exposure to elevated temperatures during processing or during service accounts for failure of many different types of polymer. Absorption of thermal energy is the primary environmental factor responsible for pyrolysis in an inert atmosphere or in a vacuum. Dependent on polymer structure, thermal degradation in the absence of oxygen is usually associated with elimination of low molecular weight, volatile fragments. But rupture of polymer chains can also occur by depolymerisation (unzipping reactions, the reverse of chain polymerisation) or by a random process initiated at weak chemical bonds in the chain. Exposure to low temperatures may also be responsible for changes in properties of a polymer.

2. Thermal-oxidative Degradation All organic materials are prone to oxidative degradation. Natural and synthetic polymers are very sensitive to reaction with oxygen, particularly at elevated temperatures. During compounding and processing operations and conversion of polymers to fabricated end products, they are normally exposed to high mechanical deformations and elevated temperatures. Hydroperoxides are known to be the initial product of thermal-oxidative degradation, and these may initiate and accelerate further degradation (Fig. 5.9). Burning is an extreme case of thermal-oxidative degradation, and flammability is a major limiting factor in replacement of metals and other traditional materials by polymers. Polymeric materials are mainly organic in nature and so they burn when the temperature is high enough.

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Fig. 5.9 Mechanism of Thermal-oxidative Degradation

3. Photo-degradation It is the photo-initiated oxidation. Primary effect of light is the generation of free radicals. It has relatively little effect on the propagating steps of the radical chain reactions. To absorb energy chromophoric groups must be present. A variety of oxygen-containing groups is formed during the processing of polymers even under normally oxygen-free conditions due to O2 dissolved in the polymer. e.g., Ketonic, ethylenic and aromatic groups. Aldehydes, ketones and carboxylic acids along or at the end of polymer chains are generated by oxygenated species in photolysis of photo-oxidation. The initiation of photo-oxidation reactions is due to the existence of chromophoric groups in the macromolecules. Photo-oxidation can occur simultaneously with thermal degradation and each of these effects can accelerate the other. The photo-oxidation reactions include chain scission, cross linking and secondary oxidative reactions. The following process steps can be considered: (Fig. 5.10) 1. Initial step: Free radicals are formed by photon absorption. 2. Chain propagation step: A free radical reacts with oxygen to produce a polymer peroxy radical (POO•). This reacts with a polymer molecule to generate polymer hydroperoxide (POOH) and a new polymer alkyl radical (P•). 3. Chain branching: Polymer oxy radicals (PO•) and hydroxy radicals (HO•) are formed by photolysis. 4. Termination step: Cross linking is a result of the reaction of different free radicals with each other.

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Fig. 5.10

where PH = Polymer P• = Polymer alkyl radical PO• = Polymer oxy radical (Polymer alkoxy radical) POO• = Polymer peroxy radical (Polymer alkylperoxy radical) POOH = Polymer hydroperoxide HO• = Hydroxy radical

Decomposition of Initially Formed Hydroperoxide Group The photon energy in solar radiation is the most damaging component of the outdoor environment, serving to initiate a wide variety of chemical changes in polymeric materials. According to the PlanckEinstein law E =hn =hc/l (where E, h, n . c and l are energy, Planck’s constant, frequency and wavelength, respectively), the energy contained in a photon rises as the wavelength decreases. Although the sun emits radiation over a wide range of wavelengths extending from below 100 nm to over 3000 nm, the earth’s atmosphere prevents radiation of wavelength less than approximately 290 nm from reaching the surface. The energy of ultraviolet photons is comparable with that of the dissociation energies of polymeric covalent bonds, which lie in

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the range of approximately 290-460 kJ/mole. Such photons have the capability of altering the polymer’s chemical structure. The deterioration process is frequently some form of photoinitiated oxidation. Typically, the process is initiated when a sufficiently energetic photon strips away a labile proton from the polymer, leaving behind a free radical.

4. Photo-oxidative Degradation Photo-oxidation is the principal reaction in degradation of polymers during exposure to ultraviolet radiation. Photo-oxidation is initiated by energy absorbed from light sources, either artificial light or sunlight. It is the degradation of a polymer surface in the presence of oxygen or ozone. The effect is facilitated by radiant energy such as UV or artificial light. This process is the most significant factor in weathering of polymers. Photo-oxidation is a chemical change that reduces the polymer’s molecular weight. As a consequence of this change the material becomes more brittle, with a reduction in its tensile, impact and elongation strength. Discoloration and loss of surface smoothness accompany photo-oxidation. High temperature and localised stress concentrations are factors that significantly increase the effect of photo-oxidation.

5. Chemical Degradation Apart from oxygen and ozone, a wide variety of chemical reactants can contribute to polymer deterioration. Some, particularly water or other atmospheric contaminants are often present in a normal environment. Effects of water are most evident in hydrolysis of condensation polymers. Polymer hydrolytic degradation may be defined as the scission of chemical bonds in the polymer backbone by the attack of water to form oligomers and finally monomers. In the first step, water contacts the water-labile bond, by either direct access to the polymer surface or by imbibitions into the polymer matrix followed by bond hydrolysis. Hydrolysis reactions may be catalyzed by acids, bases, salts, or enzymes. Resistance of a polymeric material to chemical attack is primarily dependent upon the chemical and physical structure of the polymer and the nature and the effectiveness of the stabilising system used. All the relevant parameters need to be considered carefully before selecting a polymer for a specific application in a chemical environment.

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6. Mechano-Degradation The polymer chain is ruptured by mechanical means. The effect is to reduce the polymer molecular mass. This is sometimes done deliberately. Polymer degradation initiated by mechanical forces is regarded as mechano-degradation. This occurs during processing, milling, grinding or when polymers are subjected to shear, tension or compression during processing or during service. Such degradation in a controlled manner is important during compounding of rubber, when it is used to reduce molecular weight and viscosity and plasticise the rubber prior to curing and vulcanisation. Efficient mixing of vulcanising ingredients can only be achieved after plasticisation of rubber by this process. However, mechano-degradation or stress-induced reactions could also lead to deterioration of useful properties. Usually the chain break is made permanent by chemical agents, particularly oxygen and ozone and mechanical degradation is more accurately described as mechanochemical degredation.

7. Biodegradation The polymer is being broken-down by microorganisms in the presence of oxygen (aerobic) to carbon dioxide, water biomass and mineral salts or any other elements that are present (Mineralisation). Alternatively, any organic substance able to be broken-down without the presence of oxygen (anaerobic) to carbon dioxide, methane, water and biomass over a period of time. Microorganisms generally cause degradation. However, they do not have polymer–specific enzymes. Polymers are to be initially broken-down to smaller fractions. Biodegradability requires • Low molecular weight. • Presence of certain end groups. • Polarity. • Hydrophilicity. e.g., polystyrene is stable but PS copolymerised with vinyl ketone is biodegradable.

Environmentally Degradable Polymers Our modern society is being slowly suffocated by plastic. Almost every product we purchase, food we eat, and drink we consume comes enveloped in plastic. Plastic packaging in addition to providing excellent protection for products is cheap to manufacture, and has an uncanny

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Fig. 5.11 General Mechanism of Plastic Biodegradability

long life. The ‘biodegradability’ of plastics is dependent on the chemical structure of the material and on the constitution of the final product, not just on the raw materials used for its production. Therefore, biodegradable plastics can be based on natural or synthetic resins. Natural biodegradable plastics are based primarily on renewable resources (such as starch) and can be either naturally produced or synthesised from renewable resources. Non-renewable synthetic biodegradable plastics are petroleum-based. A polymer based on the C-C backbone is non-biodegradable, whereas heteroatom-containing polymer backbone is biodegradable (carbonyl bond to O,N and S). Many polymers that are claimed to be ‘biodegradable’ are in fact ‘bio-erodable’, ‘hydro-biodegradable’ or ‘photo-biodegradable’. According to ASTM standard D-5488-94d and European norm EN

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13432, ‘‘biodegradable’’ means ‘‘capable of undergoing decomposition into carbon dioxide, methane, water, inorganic compounds, and biomass’’. The predominant mechanism is the enzymatic action of microorganisms, which can be measured by standard tests over a specific period of time, reflecting available disposal conditions. There are different media (liquid, inert, or compost medium) to analyse biodegradability. Compostability is material biodegradability using compost medium. Biodegradation is the degradation of an organic material caused by biological activity (biotic degradation), mainly microorganisms’ enzymatic action. The end-products are CO2, new biomass, and water (in the presence of oxygen, i.e. aerobic conditions) or methane (in the absence of oxygen, i.e. anaerobic conditions), as defined in the European Standard EN 13432-2000. These different polymer classes all come under the broader category of ‘environmentally degradable polymers’. 1. Biodegradable: the degradation cause by biological activity, particularly by enzyme action in a defined time period, to compost and naturally occurring gasses. 2. Compostable: Compostable plastic: a plastic that undergoes degradation by biological processes during composting to yield CO2, water, inorganic compounds, and biomass at a rate consistent with other known compostable materials and leaves no visible, distinguishable or toxic residue. 3. Hydro-biodegradable and Photo-biodegradable: Hydrobiodegradable and photo-biodegradable polymers are broken-down in a two-step process – an initial hydrolysis or photodegradation stage, followed by further biodegradation. Single degradation phase ‘water-soluble’ and ‘photo-degradable’ polymers also exist. 4. Bio-erodable: This is also known as abiotic disintegration (without the action of microorganism), and may include processes such as dissolution in water, heat or UV ageing. BIODEGRADABLE POLYMERS CLASSIFICATIONS Biodegradable polymers represent a growing field. A vast number of biodegradable polymers (e.g. cellulose, chitin, starch, polyhydroxyalkanoates, polylactide, polycaprolactone, collagen and other polypeptides…) have been synthesised or are formed in natural environment (Fig. 5.12).

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Today, commercial biodegradable plastics are offered on the market by an increasing number of manufacturers. Those most common materials can be classified into the following groups: • Starch-based plastics • Polylactide-based plastics (PLA) • Polyhydroxyalkanoate-based plastics (PHB, PHBV etc.) • Aliphatic-aromatic-polyester-based plastics • Cellulose-based plastics (cellophane, etc.) • Lignin-based plastics

Photobiodegradable Polymers In photobiodegradable plastics the structure of the polymer is altered by UV light in sunlight so that it is now amenable to biodegradation. In other words, the plastics contain an additive which causes the plastic to degrade under conditions of ultraviolet light and oxygen, degrading

Fig. 5.12 Classfication of Biodegradable Polymers

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the chemical bond or link in the polymer or chemical structure of a plastic. Initation: RH Æ R* + H* Propagation: R* + O2 Æ ROO* ROO* + RH Æ ROOH + R* ROOH Æ RO* + OH* ROOH + RH Æ RO* + R* + HOH RH + RO* Æ* ROH + R* Degradation in oxygen begins via an initiation step which produces the radical precursors. Initiation may be induced by physical (e.g. temperature, UV radiation, mechanical treatment) and/or chemical factors (e.g. traces of initiators such as peroxides and hydroperoxides used). When oxygen is allowed to react with the newly formed chain radical (R*), a peroxy radical intermediate is produced during the propagation step. Highly reactive ROO* then abstracts a labile hydrogen from another polymer molecule giving rise to the hydroperoxide species, as well as another polymer radical, through which the process can continue. Monomolecular decomposition of hydroperoxides should have a relatively high activation energy. The alkoxyl radical, RO* can also effectively abstract hydrogen from the remaining polymer.

Sensitised Photodegradation Photodegradation is fast when chromophoric groups like C=O are present. This can be used to facilitate easy degradation of otherwise useless plastic materials. (Controlled service life e.g. of plastic film used for protection of plants) These are sensitised for photodegradation but also stabilised to an extent which ensures them preplanned service life. Photosensitiser (PS) has high absorption coefficient. Polycyclic aromatic compounds such as naphthalene, anthracene etc., transfers energy to ground state O2.

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Aromatic ketones have a higher quantum efficiency for radical formation than aliphatic ketones and photosensitizers such as benzophenone may be deliberately added to polymers in order to increase their rate of photooxidation. Carbon monoxide in the side chain is more effective, Polymers with unsaturated bonds in the main chain are sensitive to photodegradation. Free radicals are formed from these compounds during irradiation. Chromophores incorporated in polymer backbone as comonomer leads to photodegradation of polymers • Copolymers of ethylene with CO • Methylmethacrylate with methyl vinyl ketone • Styrene with phenyl vinyl ketone Metal complexes: The metal salts can be added to the polymer to initiate breakdown process. The metal complexes initiate peroxide formation from molecular oxygen. Examples are: Iron complexes – Fe (II) and Fe (III) complexes of dithiocarbamates. Fe(III) acetyl acetone Benzoyl ferocene Inorganic metal oxides (ZnO, TiO2, FeCl3 etc.)

Stabilization To prevent photodegradation reactions, there are several ways to stabilize the polymer. One can stabilize polymers by keeping the light out, quench excited states before photochemistry occurs, or trap free radicals. This can be achieved by adding UV-absorbers, quenchers, radical scavengers, metal deactivators or synergistic combinations to the polymer. To protect polymers from (UV)-radiation compounds that have the ability to absorb UV radiation, can be applied; these compounds are called UV-absorbers (UVAs). The most important types which are commercially used are: hydroxybenzophenones, hydroxyphenyl benzotriazoles, cyanoacrylates, oxanilides, and more recently-commercialised hydroxyphenyl triazines.

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Hydrobiodegradable Polymers Hydrobiodegradation is initiated by hydrolysis and in the depths of a landfill hydrobiodegradable plastics generate copious quantities of methane by hydrobiodegradable plastics generate copious quantities of methane by anaerobic biodegradation. Methane is 23 times more potent for global warming than CO2. All biodegradable polymers contain hydrolysable bonds, such as glycosides, esters, orthoesters, anhydrides, carbonates, amides, urethanes, ureas etc. Polymers with strong covalent bonds in the backbone (like C-C) and with no hydrolysable groups require longer times to degrade.

Degradation Mechanisms • Enzymatic degradation • Hydrolysis (depend on main chain structure: anhydride > ester > amide)

Formation of bioassimilable sugars, carboxylic acids and alcohols from hetero-chain polymers by biotic or abiotic hydrolysis Examples: cellulose, starch, PHA, PLA, PCL etc. Factors that Accelerate Polymer Degradation • More hydrophilic backbone. • More hydrophilic end groups. • More reactive hydrolytic groups in the backbone. • Less crystallinity.

Biopolymers and Bioplastics Biodegradable plastics and polymers were first introduced in 1980s. There are many sources of biodegradable plastics, from synthetic to

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natural polymers. Natural polymers are available in large quantities from renewable sources, while synthetic polymers are produced from non renewable petroleum resources.

Biopolymers–Biodegradable Polymers • Biopolymers and bioplastics go by many different names. They are often referred to as bio-based plastics and polymers, or as biodegradable plastics or polymers. • Biopolymers are polymers which are present in, or created by, living organisms. These include polymers from renewable resources that can be polymerized to create bioplastics. • Bioplastics are plastics manufactured using biopolymers and are biodegradable.

Biopolymers–History • Biopolymers and bioplastics are not new products. Henry Ford developed a method of manufacturing plastic car parts from soybeans in the mid-1900s. However, World War II sidetracked the production of bioplastic cars. Today, bioplastics are gaining popularity once again as new manufacturing techniques developed through biotechnology are being applied to their production.

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Types of Biopolymers There are two main types of biopolymers: Both types are used in the production of bioplastics.

Biopolymers from Living Organisms • These biopolymers are present in, or created by living organisms. These include carbohydrates and proteins. These can be used in the production of plastic for commercial purposes. Examples are … • Cellulose (Wood, cotton, corn, wheat and others )- This polymer is made up of glucose. It is the main component of plant cell walls. • Soy protein(Soybeans)- Protein which naturally occurs in the soy plant. • Starch (Corn, potatoes, wheat, tapioca and others)- This polymer is one way carbohydrates are stored in plant tissue. It is a polymer made up of glucose. It is not found in animal tissues. • Polyesters (Bacteria)- These polyesters are created through naturally occurring chemical reactions that are carried out by certain types of bacteria.

Polymerizable Molecules • These molecules come from renewable natural resources, and can be polymerized to be used in the manufacture of biodegradable plastics. Examples of these polymers listed in below table: • Lactic Acid(Beets, corn, potatoes, and others)- Produced through fermentation of sugar feed stocks, such as beets, and by converting starch in corn, potatoes, or other starch sources. It is polymerized to produce polylactic acid – a polymer that is used to produce plastic.

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• Triglycerides (Vegetable oils)- These form a large part of the storage lipids found in plant and animal cells. Vegetable oils are one possible source of triglycerides that can be polymerized into plastics. BIOPLASTICS Bioplastics are manufactured using biopolymers which offer a renewable and sustainable alternative to oil-based plastics (petroplastics). Other advantages of bioplastics include novel functional properties and relatively low greenhouse gas (GHG) emissions during manufacture. Bioplastics can be produced from plant starch, cellulose, lignin (wood), oils and proteins. Like petroplastics, bioplastics are compounds constructed of linked molecules that form long polymer chains (biopolymers). Can be polymers that are: • biobased (renewable) and durable • based on fossil resources and ‘biodegradable‘ (compostable) • biobased (renewable resource) and ‘biodegradable’(compostable)

Two concepts 1. Biodegradable/Compostable – end of life functionality 2. Derived from Renewable Resources – start of life: renewable carbon Biodegradable bioplastic a plastic derived from renewable biomass that can be broken-down in the environment by microorganisms. Starchbased bioplastics can be manufactured from either raw or modified starch (e.g. thermoplastic starch or TPS) or from the fermentation of starch-derived sugars (e.g. polylactic acid or PLA). Common starch sources include maize, wheat, potatoes and cassava. Cellulose-based bioplastics are typically chemically-modified plant cellulose materials such as cellulose acetate (CA). Common cellulose sources include wood pulp, hemp and cotton. Lignin-based bioplastics contain wood (or lignocellulosic plant material) produced as a byproduct of the paper milling industry. Plant proteins such as maize ‘zein’ can also be used to manufacture bioplastics. Examples of Leading Compostable Bioplastics • Polysaccharides • Starches (TPS: Thermoplastic Starches) • Cellulosics

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• Polyesters • Polylactic acid (PLA) • Polyhydroxyalkanoates(PHAs: e.g. PHB(polyhydroxybutyrate)) • Polysuccinate esters (PBS, PBAT) (aliphatic/aromatic co-polyesters (AC, AAC) • Polycaprolactone (PCL)

How are Biopolymers and Bioplastics Made? • There are two methods being researched and used to produce plastics from plants:

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Fig. 5.13 Bioplastics Market Share

Fermentation • Fermentation, used for hundreds of years by humans, is even more powerful when coupled with new biotechnology techniques. Fermentation is the use of microorganisms to break down organic substances in the absence of oxygen. There are two ways fermentation can be used to create biopolymers and bioplastics: 1. Bacterial Polyester Fermentation 2. Lactic Acid Fermentation 1. Bacterial polyester fermentation Bacteria are one group of microorganisms that can be used in the fermentation process. Fermentation, in fact, is the process by which bacteria can be used to create polyesters. Bacteria called Ralstonia eutropha are used to do this. The bacteria use the sugar of harvested plants, such as corn, to fuel their cellular processes. The by-product of these cellular processes is the polymer. The polymers are then separated from the bacterial cells (Fig. 5.14).

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Fig. 5.14 Bacterial Polyester Fermentation

2. Lactic acid fermentation • Lactic acid is fermented from sugar, much like the process used to directly manufacture polymers by bacteria. However, in this fermentation process, the final product of fermentation is lactic acid, rather than a polymer. After the lactic acid is produced, it is converted to polylactic acid using traditional polymerization processes.

Growing Plastics in Plants Plants are becoming factories for the production of plastics. Scientists created a plant(Arabidopis thaliana) through genetic engineering (Fig. 5.15).

Fig. 5.15 Growing Plastics in Plants

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Applications of Biodegradable Polymers They can be used for the controlled release of agricultural chemicals. The natural polymers used in controlled release systems are typically starch, cellulose, chitin, aliginic acid and lignin. In horticulture threads, clips, staples, bags of fertilizer, envelopes of ensilage and trays with seeds are applications mentioned for biopolymers. Containers such as biodegradable plant pots and disposable composting containers and bags are other agricultural applications. In marine agriculture, biopolymers are used to make ropes and fishing nets. They are also used as support for the marine cultures. Automotive: The automotive sector aims to prepare lighter cars by use of bioplastics and biocomposites. Natural fibers can replace glass fibers as reinforcement materials in plastic car parts. For example the PLA is mixed with fibers of kenaf for replace the panels of car doors and dashboards (Toyota Internet site). Starch-based polymers are used as additive in the manufacturing of tires. It reduces the resistance to the movement and the consumption of fuel and in fine greenhouse gas emissions (Novamont Internet site). Electronics: PLA and kenaf are used as composite in electronics applications. Compact disks based on PLA are also launched on the market by the Pioneer and Sanyo groups. Fujitsu Company has launched a computer case made of PLA. Construction: PLA fiber is used for the padding and the paving stones of carpet. Its inflammability, lower than that of the synthetic fibers, offers more security. Its antibacterial and antifungal properties avoid allergy problems. The fiber is also resistant to UV radiation. Sports and leisure: Some fishing hooks and biodegradable golf tees (Vegeplast, France) are based on starch. PLA fiber is used for sports clothes. It combines the comfort of the natural fibers and the resistance of synthetic fibers. Biotechnological applications: Chitin acts as an absorbent for heavy and radioactive metals, useful in wastewater treatment. Applications with short-term life character and disposability: Aliphatic polyesters like PLA, PBS, PCL and their copolymers are used as biodegradable plastics for disposable consumer products, like disposable food service items (disposable cutlery and plates, for example). Other products are diapers, cotton stalk and sanitary products. Unusual applications: There are a lot of other applications which do not fit into any of the previous categories. Thus combs, pens Agriculture:

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(Begreen® from Pilot Pen or Green Pen® from Yokozuna), and mouse pads made of biodegradable polymers have also been invented, mostly for use as marketing tools. Biodegradable polymers can be used to modify food textures. Table 5.3 Applications of Biodegradable Polymers Composition

Applications

Starch and polyester

Collection bags for green waste, agricultural films, desposable items.

Rye flower (80%)

Disposable items, flower containers

Starch

Wrapping plastics

PHB/PHV

Razors, bottles

PLA

Sanitary products, sport clothes, conditioning and packaging

Proteins extracted from cotton seed

Agricultural films

Co-polyester

Agricultural films

Co-polyester

Agricultural films

Polyester amide

Disposable items, flower containers

Polylactide or Polylactic Acid(PLA) Polylactide is the most common biopolymer currently on the market. Its chemical name is derived from the lactide molecule that it is polymerized from. Lactide is derived from sources such as starches in corn, potatoes, beets, and other plants. In the United States, it is primarily taken from corn starch; in the rest of the world, sugar cane starches are used. The polymer chain of PLA is made up of these molecules

The manufacture of polyester from lactic acid was pioneered by Carothers in 1932 and further developed by Dupont and Ethicon. Prohibitive production costs restricted the applicability of these polymers outside the medical field until the late 1980s. Since then,

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major breakthroughs in process technology, coupled with decreased costs of biologically produced lactic acid, have led to the commercialscale production of BPs from lactic acid for nonmedical applications. PLA is currently used in packaging (film, thermoformed containers, and short-shelf life bottles). Fabrics produced from PLA provide a silky feel, durability, and moisture-management properties (moisture is quickly wicked away from the body, keeping the wearer dry and comfortable). PLA can be considered as the first biodegradable polymers used in biomedical applications. Starch sugar fermentation products such as polylactic acid (PLA) are used in cold drinks cups and bottles, food packaging film and containers, carpets and clothing. PLA can also be used to manufacture CDs and electronics casings

Polycaprolactone (PCL) PCL is thermoplastic biodegradable polyester synthesised by chemical conversion of crude oil, followed by ring-opening polymerization. PCL has good water, oil, solvent and chlorine resistance, a low melting point, and low viscosity and is easily processed thermally. Polycaprolactone is a relatively cheap cyclic monomer. A semi-crystalline linear polymer is obtained from ring-opening polymerization of e-caprolactone in presence of tin octoate catalyst. PCL is soluble in a wide range of solvents. PCL is a semi-rigid material at room temperature, Polycaprolactone is a biopolymer belonging to the polyester family. It is produced from the e-caprolactone ring molecule, which is derived from crude oil. This is polymerized by a ring-opening process as

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well, taking place as an addition reaction, which joins rings of the molecule together with heat to form the long polymer strands. PCL has a large biomedical application range. PCL is a Food and Drug Administration (FDA) approved material that is used in the human body as a drug delivery device, suture and adhesion barrier. PCL is used in root canal filling.

PHB (Polyhydroxybutyrate) The polyhydroxyalkanates(PHAs) are considered as biodegradable and thus suitable for e.g., short-term packaging, and also considered as biocompatible in contact with living tissues and can be used for biomedical applications (e.g. drug encapsulation, tissue engineering…). PHA can be degraded by abiotic degradation, i.e., simple hydrolysis of the ester bond without requiring the presence of enzymes to catalyze this hydrolysis. During the biodegradation process, the enzymes degrade the residual products till final mineralisation (biotic degradation). The main biopolymer of the PHA family is the polyhydroxybutyrate homopolymer (PHB), but also different poly(hydroxybutyrate-cohydroxyalkanoates) copolyesters exist such as poly(hydroxybutyrate-co-hydroxy valerate) (PHBV), poly(hydroxybutyrate-cohydroxyhexanoate) (PHBHx). PHB is a highly crystalline polyester (above 50%) with a high melting point, 180°C, compared to the other biodegradable polyesters. PHB produced from fermentation of carbohydrate

• • • Uses •

Industrial and home compostable and recyclable Better O2 and CO2 barrier than PLA Limitations: opacity; cost / availability; processing BioTuf® (by Heritage - US) compostable bags

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• Shampoo bottles - US, Germany and Japan • Injection moulded: cutlery, closures,.... • Thermoformed: hot cups, lids, food trays BIOREMEDIATION Bioremediation is the use of microorganisms for the degradation of hazardous chemicals in soil, sediments, water or other contaminated materials. Often the microorganisms metabolize the chemicals to produce carbon dioxide or methane, water and biomass. For example, perchloroethylene and trichloroethylene may degrade to vinyl chloride.

History of Bioremediation • 1972 - First commercial application: Sun Oil pipeline spill in Ambler, Pennsylvania • 1970s - Continuing bioremediation projects by Richard Raymond of Sun Oil. • mid-1980s - emphasis on bioengineering organisms for bioremediation. This technology did not live up to its initial promise • 1990s - emphasis switched to greater reliance on natural microorganisms and techniques to enhance their performance Bioremediation has been described as “a treatability technology that uses biological activity to reduce the concentration or toxicity of a pollutant. It commonly uses processes by which microorganisms transform or degrade chemicals in the environment”. The four requirements of bioremediation are: (Fig. 5.16)

Fig. 5.16

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1. Sufficient microorganisms that can biodegrade the contaminant. 2. Required nutrients are available. 3. Good environmental conditions exist. 4. The time to allow the natural process to degrade the contaminant. Table 5.4 Factors for Bioremediation Factors

Condition required

Microorganisms

Aerobic or Anaerobic

Natural Biological processes of microorganism

Catabolism and Anabolism

Environmental factors

Temperature, pH, Oxygen content, Electron acceptor/donor

Nutrients

Carbon, Nitrogen, Oxygen etc.

Soil Moisture

25-28% of Water holding capacity

Type of soil

Low clay or silt content

Bioremediation is the use of microorganisms to destroy or immobilize waste materials. Microorganisms include: Bacteria (aerobic and anaerobic) Fungi Actinomycetes (filamentous bacteria) We can subdivide these microorganisms into the following groups: Aerobic. In the presence of oxygen. Examples of aerobic bacteria recognised for their degradative abilities are Pseudomonas, Alcaligenes, Sphingomonas, Rhodococcus, and Mycobacterium. These microbes have often been reported to degrade pesticides and hydrocarbons, both alkanes and compounds. Many of these bacteria use the contaminant as the sole source of carbon and energy. Anaerobic. In the absence of oxygen. Anaerobic bacteria are not as frequently used as aerobic bacteria. There is an increasing interest in anaerobic bacteria used for bioremediation of polychlorinated biphenyls (PCBs) in river sediments, dechlorination of the solvent trichloroethylene (TCE) and chloroform. Ligninolytic fungi. Fungi such as the white rot fungus Phanaerochaete chrysosporium have the ability to degrade an extremely diverse range of persistent or toxic environmental pollutants. Common substrates used include straw, saw dust, or corn cobs.

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Methylotrophs. Aerobic bacteria that grow utilising methane for carbon and energy. The initial enzyme in the pathway for aerobic degradation, methane monooxygenase, has a broad substrate range and is active against a wide range of compounds, including the chlorinated aliphatics trichloroethylene and 1,2-dichloroethane.

Bioremediation Strategies Bioremediation can occur either in-situ (at the site of contamination) or ex-situ (contaminant taken out of the site of contamination and treated elsewhere). If the process occurs in the same place affected by pollution then it is called in-situ bioremediation. In contrast, deliberate relocation of the contaminated material (soil and water) to a different place to accelerate biocatalysis is referred to as ex-situ bioremediation.

In-situ Bioremediation In-situ bioremediation is the application of biological treatment to the cleanup of hazardous chemicals present in the subsurface. The optimization and control of microbial transformations of organic contaminants require the integration of many scientific and engineering disciplines.

Biosparging Biosparging involves the injection of air under pressure below the water table to increase groundwater oxygen concentrations and enhance the rate of biological degradation of contaminants by naturally occurring bacteria. Biosparging increases the mixing in the saturated zone and thereby increases the contact between soil and groundwater. The ease and low cost of installing small-diameter air injection points allows considerable flexibility in the design and construction of the system (Fig. 5.17).

Bioventing Bioventing is a promising new technology that stimulates the natural in-situ biodegradation of any aerobically degradable compounds within the soil by providing oxygen to existing soil microorganisms. In contrast to soil-vapor extraction (SVE), bioventing uses low air flow rates to provide only enough oxygen to sustain microbial activity (Fig. 5.18). Oxygen is most commonly supplied through direct air injection into residual contamination in soil by means of wells. Adsorbed fuel residuals

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Fig. 5.17 Biosparging

are biodegraded, and volatile compounds also are biodegraded as vapors move slowly through biologically active soil.

Fig. 5.18 Bioventing

Biostimulation This process involves the stimulation of indigenous microorganisms to degrade the contaminant. The microbial degradation of many pollutants in aquatic and soil environments is limited primarily by the availability of nutrients, such as nitrogen, phosphorus, and oxygen availability. The addition of nitrogen- and phosphorus-containing substrates has been shown to stimulate the indigenous microbial populations.

Bioaugmentation Bioaugmentation is the introduction of a group of natural microbial strains or a genetically engineered variant to treat contaminated soil

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or water. It is commonly used in municipal wastewater treatment to restart activated sludge bioreactors. Most cultures available contain a research based consortium of Microbial cultures, containing all necessary microorganisms At sites where soil and groundwater are contaminated with chlorinated ethenes, such as tetrachloroethylene and trichloroethylene, bioaugmentation is used to ensure that the in-situ microorganisms can completely degrade these contaminants to ethylene and chloride, which are non-toxic.

Ex-situ Bioremediation Composting is a process by which organic wastes are degraded by microorganisms, typically at elevated temperatures. Typical compost temperatures are in the range of 55° to 65°C. The increased temperatures result from heat produced by microorganisms during the degradation of the organic material in the waste. Bioreactors Slurry reactors or aqueous reactors are used for ex-situ treatment of contaminated soil and water pumped up from a contaminated plume. Bioremediation in reactors involves the processing of contaminated solid material (soil, sediment, sludge) or water through an engineered containment system. A slurry bioreactor may be defined as a containment vessel and apparatus used to create a three-phase (solid, liquid, and gas) mixing condition to increase the bioremediation rate of soil bound and water-soluble pollutants as a water slurry of the contaminated soil and biomass(usually indigenous microorganisms) capable of degrading target contaminants.

Advantages and Disadvantages of Bioremediation Technologies The use of intrinsic or engineered bioremediation processes offers several potential advantages that are attractive to site owners, regulatory agencies and the public. These include: 1. Lower cost than conventional technologies 2. Contaminants usually converted to innocuous products. 3. Contaminants are destroyed, not simply transferred to different environmental media. 4. Nonintrusive, potentially allowing for continued site use. 5. Relative ease of implementation.

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However, there are potential disadvantages to bioremediation as well, these include: 1. May be difficult to control. 2. Amendments introduced into the environment to enhance bioremediation may cause other contamination problems. 3. May not reduce concentration of contaminants to required levels. 4. Requires more time. 5. May require more extensive monitoring. 6. Lack of (hydraulic) control. 7. Dynamic process, difficult to predict future effectiveness.

Developments of Phytoremediation Microbes are not the only species that can be enhanced by genetic modification for bioremediatory purposes. Plants have also been studied and used. Bioremediation by plants is called phytoremediation. Phytoremediation is an emerging technology that uses various plants to degrade, extract, contain, or immobilise contaminants from soil and water. This technology has been receiving attention lately as an innovative, cost-effective alternative to the more established treatment methods used at hazardous waste sites. The U.S. Environmental Protection Agency (EPA) seeks to protect human health and the environment from risks associated with hazardous waste sites, while encouraging development of innovative technologies such as phytoremediation to more efficiently clean up these sites. The major advantages of phytoremediation are as follows (i) The cost of the phytoremediation is lower than that of traditional processes both in-situ and ex-situ. (ii) The plants can be easily monitored. (iii) The possibility of the recovery and re-use of valuable products. (iv) It uses naturally occurring organisms and preserves the natural state of the environment. (v) The low cost of phytoremediation (up to 1000 times cheaper than excavation and reburial) is the main advantage of phytoremediation. We can find five types of phytoremediation techniques, classified based on the contaminant fate: phytoextraction, phytotransformation, phytostabilisation, phytodegradation, rhizofiltration. (Table 5.5)

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Table 5.5 Types of Phytoremediation Process

Function

Pollutant

Medium

Plants

Phytoextraction

Remove metals pollutants that accumulate in plants. Remove organics from soil by concentrating them in plant parts

Cd, Pb, Zn, As, Petroleum, Hydrocarbons and Radionuclides

Soil and Groundwater

Viola baoshanensis, Sedum alfredii, Rumex crispus

Phytotranformation

Plant uptake and degradation of organic compounds

Xenobiotic substances

Soil

Cannas

Phytodegradation

Plants and associated DDT, Expolsives, Groundwater microorganisms degrade Waste and organic pollutants Nitrates

Elodea Canadensis, Pueraria

Rhizofiltration

Zn, Pb, Cd, As Roots absorb and Zn, Pb, Cd, As Groundwater adsorb pollutants, mainly metals, form water and aqueous waste streams

Groundwater

Brassica juncea,

Phytostabilization (Immobilization)

Use of plants to reduce the bioavailability of pollutants in the environment

Soil

Anthyllis vulneraria, Festuca arvernensis

Cu, Cd, Cr, Ni, Pb, Zn

1. Phytodegradation Specifically, phytodegradation, also called “phytotransformation”, refers to the uptake of contaminants with the subsequent breakdown, mineralisation, or metabolization by the plant itself through various internal enzymatic reactions.

2. Phytostabilization Phytostabilization refers to the holding of contaminated soils and sediments in place by vegetation, and to immobilizing toxic contaminants in soils. Establishment of rooted vegetation prevents windblown dust, an important pathway for human exposure at hazardous waste sites. Phytostabilization is especially applicable for metal contaminants at waste sites where the best alternative is often to hold contaminants in place. Metals do not ultimately degrade, so capturing those in-situ is the best alternative at sites with low contamination levels (below risk thresholds) or vast contaminated areas where a large-scale removal action or other in-situ remediation is not feasible.

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3. Phytoextraction Phytoextraction refers to the ability of plants to take up contaminants into the roots and translocate them to the aboveground shoots or leaves. For contaminants to be extracted by plants, the constituent must be dissolved in the soil water and come into contact with the plant roots through the transpiration stream.

4. Rhizofiltration Rhizofiltration can be defined as the use of plant roots to absorb, concentrate, and/or precipitate hazardous compounds, particularly heavy metals or radionuclides, from aqueous solutions. Hydroponically cultivated plants rapidly remove heavy metals from water and concentrate them in the roots and shoots. Rhizofiltration is effective in cases where wetlands can be created and all of the contaminated water is allowed to come in contact with roots. Contaminants should be those that sorb strongly to roots, such as lead, chromium (III), uranium, and arsenic (V). Roots of plants are capable of sorbing large quantities of lead and chromium from soil water or from water that is passed through the root zone of densely growing vegetation.

5. Phytotransformation Phytotransformation refers to the uptake of organic contaminants from soil, sediments, or water and, subsequently, their transformation to more stable, less toxic, or less mobile form. Metal chromium can be reduced from hexavalent to trivalent chromium, which is a less mobile and noncarcinogenic form.

CHAPTER

6 Environmental Pollution

Developmental activities such as construction, transportation and manufacturing not only deplete the natural resources but also produce large amount of wastes that leads to pollution of air, water, soil, and oceans; global warming and acid rains. Untreated or improperly treated waste is a major cause of pollution of rivers and environmental degradation causing ill health and loss of crop productivity. In this lesson you will study about the major causes of pollution, their effects on our environment and the various measures that can be taken to control such pollutions. POLLUTION AND POLLUTANTS Human activities directly or indirectly affect the environment adversely. A stone crusher adds a lot of suspended particulate matter and noise into the atmosphere. Automobiles emit from their tail pipes oxides of nitrogen, sulphur dioxide, carbon dioxide, carbon monoxide and a complex mixture of unburnt hydrocarbons and black soot which pollute the atmosphere. Domestic sewage and run-off from agricultural fields, laden with pesticides and fertilizers, pollute water bodies. Effluents from tanneries contain many harmful chemicals and emit foul smell. These are only a few examples which show how human activities pollute the environment. Pollution may be defined as addition of undesirable material into the environment as a result of human activities. The agents which cause environmental pollution are called pollutants. A pollutants may be defined as a physical, chemical or biological substance unintentionally released into the environment which is directly or indirectly harmful to humans and other living organisms. TYPES OF POLLUTION Pollution may be of the following types: I. Air pollution

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II. III. IV. V. VI. VII.

Water pollution Soil pollution Marine pollution Noise pollution Thermal pollution Nuclear hazards

I. Air Pollution The present-day atmosphere is quite different from the natural atmosphere that existed before the Industrial Revolution, in terms of chemical composition. Air pollution is the presence of substances in air in sufficient concentration and for sufficient time, so as to be, or threaten to be injurious to human, plant or animal life, or to property, or which reasonably interferes with the comfortable enjoyment of life and property. Air pollutants arise from both man-made and natural processes. Pollutants are also defined as primary pollutants resulting from combustion of fuels and industrial operations and secondary pollutants, those which are produced due to reaction of primary pollutants in the atmosphere. The ambient air quality may be defined by the concentration of a set of pollutants which may be present in the ambient air we breath in. These pollutants may be called criteria pollutants. Emission standards express the allowable concentrations of a contaminant at the point of discharge before any mixing with the surrounding air. Pollutants that are emitted directly from identifiable sources are produced both by natural events (for example, dust storms and volcanic eruptions) and human activities (emission from vehicles, industries, etc.). These are called primary pollutants. There are five primary pollutants that together contribute about 90% of the global air pollution. These are carbon monooxides, carbon dioxide (CO and CO2), nitrogen oxides, sulfur oxides, volatile organic compounds (mostly hydrocarbons) and suspended particulate matter. Pollutants that are produced in the atmosphere when certain chemical reactions take place among the primary pollutants are called secondary pollutants. e.g., sulfuric acid, nitric acid, carbonic acid etc.

Environmental Pollution

6.3

Primary and Secondary Pollutants Pollutants can be classified as primary or secondary. Primary pollutants are substances which are directly emitted into the atmosphere from sources. The main primary pollutants known to cause harm in high enough concentrations are the following: (Fig. 6.1) • Carbon compounds, such as CO, CO2, CH4 and VOCs; • Nitrogen compounds, such as NO, N2O, and NH3 ; • Sulfur compounds, such as H2S and SO2; • Halogen compounds, such as chlorides, fluorides and bromides • Particulate Matter (PM or “aerosols”), either in solid or liquid form. Secondary pollutants are not directly emitted from sources, but instead form in the atmosphere from primary pollutants (also called “precursors”). The main secondary pollutants known to cause harm in high enough concentrations are the following: • NO2 and HNO3 formed from NO; • Ozone (O3) formed from photochemical reactions of nitrogen oxides and VOCs; • Sulfuric acid droplets formed from SO2 and nitric acid droplets formed from NO2; • Sulfates and nitrates aerosols (e.g. ammonium (bi)sulfate and ammonium nitrate) formed from reactions of sulfuric acid droplets and nitric acid droplets with NH3, respectively • Organic aerosols formed from VOCs in gas-to-particle reactions.

Fig. 6.1 Primary Pollutants

6.4

Environmental Chemistry

Air pollution consists of gas and particle contaminants that are present in the atmosphere. Gaseous pollutants include SO2, NOx, ozone, carbon monoxide (CO), volatile organic compounds (VOCs), certain toxic air pollutants, and some gaseous forms of metals. In addition to gases, the atmosphere contains solid and liquid particles that are suspended in the air. These particles are referred to as aerosols or particulate matter (PM). Aerosols in the atmosphere typically measure between 0.01 and 10 micrometers in diameter.

Causes Air pollution can result from both human and natural actions. Natural sources • Dust from natural sources, usually large areas of land with few or no vegetation. • Methane, emitted by the digestion of food by animals, for example, cattle. • Radon gas from radioactive decay within the Earth’s crust. It is considered to be a health hazard. Radon gas from natural sources can accumulate in buildings, especially in confined areas such as the basement and it is the second most frequent cause of lung cancer, after cigarette smoking. • Smoke and carbon monoxide from wildfires. • Vegetation, in some regions, emits environmentally significant amounts of VOCs on warmer days. • Volcanic activity, which produce sulfur, chlorine and ash particulates. • wind erosion. • pollen dispersal. Anthropogenic sources (man-made sources) • Deforestation • “Stationary Sources” include smoke stacks of power plants, manufacturing facilities (factories) and waste incinerators, as well as furnaces and other types of fuel-burning heating devices. • “Mobile Sources” include combustion of fuels in motor vehicles, marine vessels, aircraft etc. • Chemicals like pesticides and fertilizers, dust and controlled burn practices in agriculture and forestry management.

Environmental Pollution

6.5

• Fumes from paint, hair spray, varnish, aerosol sprays and other solvents. • Waste deposition in landfills, which generate methane. Methane is also an asphyxiant and may displace oxygen in an enclosed space. • Military, such as nuclear weapons, toxic gases, germ warfare and rocketry. Environmental Effects Along with harming human health, air pollution can cause a variety of environmental effects: • Acid rain is precipitation containing harmful amounts of nitric and sulfuric acids. These acids are formed primarily by nitrogen oxides and sulfur oxides released into the atmosphere when fossil fuels are burned. These acids fall to the Earth either as wet precipitation (rain, snow or fog) or dry precipitation (gas and particulates). Some are carried by the wind, sometimes hundreds of miles. In the environment, acid rain damages trees and causes soils and water bodies to acidify, making the water unsuitable for some fish and other wildlife. It also speeds the decay of buildings, statues, and sculptures that are part of our national heritage. Acid rain has damaged Massachusetts lakes, ponds, rivers, and soils, leading to damaged wildlife and forests. • Haze is caused when sunlight encounters tiny pollution particles in the air. Haze obscures the clarity, color, texture and form of what we see. Some haze-causing pollutants (mostly fine particles) are directly emitted to the atmosphere by sources such as power plants, industrial facilities, trucks and automobiles and construction activities. • Effects on wildlife Toxic pollutants in the air contribute to birth defects, reproductive failure and disease in animals. Persistent toxic air pollutants (those that breakdown slowly in the environment) are of particular concern in aquatic ecosystems. • Ozone depletion Thinning of the protective ozone layer can cause increased amounts of UV radiation to reach the Earth, which can lead to more cases of skin cancer, cataracts and impaired immune systems. UV can also damage sensitive crops, such as soybeans and reduce crop yields.

6.6

Environmental Chemistry

• Crop and forest damage Air pollution can damage crops and trees in a variety of ways. Ground-level ozone can lead to reductions in agricultural crop and commercial forest yields, reduced growth and survivability of tree seedlings, and increased plant susceptibility to disease, pests and other environmental stresses. • Global climate change The Earth’s atmosphere appears to be trapping more of the sun’s heat, causing the Earth’s average temperature to rise - a phenomenon known as global warming. Many scientists believe that global warming could have significant impacts on human health, agriculture, water resources, forests, wildlife and coastal areas. • Air pollution can affect our health in many ways (1) aggravation of respiratory and cardiovascular disease; (2) decreased lung function; (3) increased frequency and severity of respiratory symptoms such as difficulty breathing and coughing; (4) increased susceptibility to respiratory infections; (5) effects on the nervous system, including the brain, such as IQ loss and impacts on learning, memory and behavior; (6) cancer and (7) premature death. • Air pollution also damages our environment Ozone can damage vegetation, adversely impacting the growth of plants and trees. These impacts can reduce the ability of plants to uptake CO2 from the atmosphere and indirectly affect entire ecosystems. Visibility is reduced by particles in the air that scatter and absorb light. Typical visual range in the eastern U.S. is 15 to 30 miles, approximately one-third of what it would be without man-made air pollution. In the West, the typical visual range is about 60 to 90 miles, or about one-half of the visual range under natural conditions. • Smog Smog is often used as a generic term for any kind of air pollution that reduces visibility, especially in urban areas. Smog is a synchrony of two words–smoke and fog. Smog can be of two types–industrial or winter smog (e.g. London smog) and photochemical or summer smog (e.g. Los Angeles smog) (Table 6.1). 1. London smog of 1952 are often referred to as industrial smog because SO2 emissions from burning coal play a key role. Typically, industrial smog—also called gray or black smog— develops under cold and humid conditions. Cold temperatures

Environmental Pollution

6.7

are often associated with inversions that trap the pollution near the surface. High humidity allows for rapid oxidation of SO2 to form sulfuric acid and sulfate particles. Events similar to the 1952 London smog occurred in the industrial towns of Liege, Belgium, in 1930, killing more than 60 people, and Donora, Pennsylvania, in 1948, killing 20. Today coal combustion is a major contributor to urban air pollution in China, especially from emissions of SO2 and aerosols. Air pollution regulations in developed countries have reduced industrial smog events, but photochemical smog remains a persistent problem, largely driven by vehicle emissions. 2. Photochemical smog forms when NOx and VOCs react in the presence of solar radiation to form ozone. The solar radiation also promotes formation of secondary aerosol particles from oxidation of NOx, VOCs, and SO2. Photochemical smog typically develops in summer (when solar radiation is strongest) in stagnant conditions promoted by temperature inversions and weak winds. Photochemical smog is a ubiquitous urban problem in the developed world and often blankets large populated regions such as the eastern United States and western Europe for extended periods in summer. Ozone and aerosols are the two main health hazards of photochemical smog. Ozone is invisible, but aerosol particles scatter sunlight, and are responsible for the whitish haze associated with smog. Because ozone is created in the atmosphere, concentrations are often higher downwind of urban areas than in the urban areas themselves. Sun SUN

NO (nitric oxide)

NO2

O

UV H2O

O2

Hodrocarbons

PANs Aldehydes

HNO3 Nitric Acid

O3 Ozone Photochemical Smog

1° Air Pollutants

O2 NO

Fig. 6.2 Photochemical Smog

Hydrocarbons

6.8

Environmental Chemistry

Table 6.1

Differnece between London and Los Angels smog

Characteristics

Industrial/Winter

Photochemical/Summer

First occurrence noted

London

Los Angeles

Principal pollutants

Sulfur oxides, particulate matter

Ozone, nitrogen oxides, hydrocarbons, carbon monoxide, free radicals

Principal sources

Industrial and household fuel combustion (coal, petroleum)

Transportation fuel Combustion (petroleum)

Effects on human

Lung and throat irritation

Eye and throat irritation

Effects on compounds

Reducing

Oxidizing

Time of occurrence of worst episodes

Winter months especially in the early morning

Around mid-day of summer months

Effects of Photochemical Smog (a)

Effects on human health

Low concentrations of ground-level ozone can irritate the eyes, nose and throat. As smog increases, it can trigger more serious health problems, including: • Asthma, bronchitis, coughing and chest pain; • Increased susceptibility to respiratory infections; • Decreased lung function and physical performance. (b) Effects on vegetation and materials Sensitive crops, trees and other vegetation are harmed at lower ozone concentrations than is human health. Ground-level ozone can damage leaves, reduce growth, productivity and reproduction. It can cause vulnerability to insects and disease and even plant death. When ozone levels are fairly high over a long period, agricultural crops can suffer significant harm. Smog can also accelerate the deterioration of rubber, plastics, paints and dyes etc. (c) The enhanced greenhouse effect and acid rain The pollutants emitted into atmosphere are implicated in numerous environmental problems. Ozone, for example, is not only a major component of smog; it also contributes to the enhanced greenhouse effect, which is predicted to lead to global climate change. Similarly,

Environmental Pollution

6.9

NOx - one of the building blocks of ground-level ozone - plays a major role in formation of acid rains.

Common Air Pollutants, their Sources, Effects and Control are 1. Carbon monoxide (CO): Carbon monoxide (CO) is an odorless, colorless gas formed by incomplete combustion of carbon in fuel. Source: The main source is motor vehicle exhaust, along with industrial processes and biomass burning. Effects: At low concentrations, fatigue in healthy people and chest pain in people with heart disease. At higher concentrations, impaired vision and coordination; headaches; dizziness; confusion; nausea. Acute effects are due to the formation of carboxyhaemoglobin in the blood, which inhibits oxygen intake. At moderate concentrations, angina, impaired vision, and reduced brain function may result. At higher concentrations, CO exposure causes central nervous system impairment or death. Control: Transporatation planning, vehicle emission testing, efficient combustion technique, and energy conservation. 2. Oxides of sulphur (SOx): Sulfur dioxide (SO2) is a gas formed when sulfur is exposed to oxygen at high temperatures during fossil fuel combustion, oil refining, or metal smelting. Sulphur dioxide when released in the atmosphere can also convert to SO3, which leads to production of sulphuric acid. When SO3 is inhaled it is likely to be absorbed in moist passages of respiratory tract. When it is entrained in an aerosol, however, it may reach far deeper into the lungs. Sulphur dioxide can damage vegetation and cause corrosion. Airborne sulfates reduce visibility. It is also the cause of acid rain in some countries. 2SO2 Sulfur dioxide

+

O2 Oxygen

Æ

SO3 Sulfur trioxide

Sources: Biomass and fossil fuel combustion in automobiles, Industrial emissions, smelters, Power plants, boilers, sulphuric acid manufacture, ore refining, petroleum refining. Lead ore refining, battery manufacturing Effects – Absorption at upper respiratory tract (sulfite, bisulfite) • Health effects (starting at