The Marine Environment: Ecology, Management and Conservation : Ecology, Management and Conservation [1 ed.] 9781620819456, 9781612092652

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Copyright © 2011. Nova Science Publishers, Incorporated. All rights reserved. The Marine Environment: Ecology, Management and Conservation : Ecology, Management and Conservation, Nova Science Publishers, Incorporated,

Copyright © 2011. Nova Science Publishers, Incorporated. All rights reserved. The Marine Environment: Ecology, Management and Conservation : Ecology, Management and Conservation, Nova Science Publishers,

MARINE BIOLOGY

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THE MARINE ENVIRONMENT: ECOLOGY, MANAGEMENT AND CONSERVATION

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MARINE BIOLOGY

THE MARINE ENVIRONMENT: ECOLOGY, MANAGEMENT AND CONSERVATION

ADAM D. NEMETH Copyright © 2011. Nova Science Publishers, Incorporated. All rights reserved.

EDITOR

Nova Science Publishers, Inc. New York The Marine Environment: Ecology, Management and Conservation : Ecology, Management and Conservation, Nova Science Publishers,

Copyright © 2011 by Nova Science Publishers, Inc. All rights reserved. No part of this book may be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic, tape, mechanical photocopying, recording or otherwise without the written permission of the Publisher. For permission to use material from this book please contact us: Telephone 631-231-7269; Fax 631-231-8175 Web Site: http://www.novapublishers.com NOTICE TO THE READER The Publisher has taken reasonable care in the preparation of this book, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained in this book. The Publisher shall not be liable for any special, consequential, or exemplary damages resulting, in whole or in part, from the readers‟ use of, or reliance upon, this material. Any parts of this book based on government reports are so indicated and copyright is claimed for those parts to the extent applicable to compilations of such works.

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Independent verification should be sought for any data, advice or recommendations contained in this book. In addition, no responsibility is assumed by the publisher for any injury and/or damage to persons or property arising from any methods, products, instructions, ideas or otherwise contained in this publication. This publication is designed to provide accurate and authoritative information with regard to the subject matter covered herein. It is sold with the clear understanding that the Publisher is not engaged in rendering legal or any other professional services. If legal or any other expert assistance is required, the services of a competent person should be sought. FROM A DECLARATION OF PARTICIPANTS JOINTLY ADOPTED BY A COMMITTEE OF THE AMERICAN BAR ASSOCIATION AND A COMMITTEE OF PUBLISHERS. Additional color graphics may be available in the e-book version of this book. LIBRARY OF CONGRESS CATALOGING-IN-PUBLICATION DATA The marine environment : ecology, management and conservation / [editor] Adam D. Nemeth. p. cm. Includes index. ISBN:  (eBook) 1. Marine resources. 2. Marine ecology. 3. Marine resources--Management. 4. Marine resources conservation. I. Nemeth, Adam D. GC1015.2.M37 2010 577.7--dc22 2010047114

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CONTENTS Preface Chapter 1

Desalination Impacts on the Marine Environment P. Palomar and I. J. Losada

Chapter 2

International Protection of the Marine Environment Angela Carpenter

Chapter 3

Isolation and Molecular Characterization of Marine Bacteria isolated from the Beagle Channel, Argentina Héctor A. Cristóbal, Adriana E. Alvarenga and Carlos M. Abate

Chapter 4

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vii

Chapter 5

Chapter 6

Chapter 7

Chapter 8

Chapter 9

Ecophysiological Significance of Selective Feeding of Heterotrophic Nanoflagellates in Marine Environment Bidyut R. Mohapatra and Kimio Fukami Microbial Marine Community as Source of Hydrolytic Enzymes. Study on Thermal Adaptation of Esterases and Lipases from Marine Micro-Organisms Luigi Mandrich and Donatella de Pascale

1 51

87

119

141

Potential for Petroleum Aliphatic Hydrocarbon Degradation of the Key Bacteria in Temperate Seas Maki Teramoto and Shigeaki Harayama

157

The Hypersaline Gulf: A Model Study of Potential Impacts of Seawater Desalination on the Marine Environment H. H. Al-Barwani and A. Purnama

167

Dynamics of Suspended Particulate Matter in the Menai Strait (UK) and its Implications for Ecosystem Functioning and Management V. Krivtsov, J. Gascoigne and M. W. Skov

179

Concrete and Marine Environment Moetaz El-Hawary

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vi

Contents

Chapter 10

The Marine Environment: Samples and Analytes M. C. Yebra-Biurrun

Chapter 11

Marine Debris, a Growing Problem: Sources, Distribution, Composition, and Impacts Stelios Katsanevakis

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Index

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277 325

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PREFACE This book presents current research in the study of the marine environment, including the isolation and molecular characterization of marine bacteria; the ecophysiological significance of selective feeding of hetertrophic nanoflagellates; potential impacts of seawater desalination; marine pollution and international protection studies of the marine environment. Chapter 1 – If seawater is considered to be an inexhaustible natural resource, then desalination is a good alternative to be used in scarce areas with irregular river flows or those in which conventional water sources are insufficient or overexploited. Leaving aside the debate regarding excessive water consumption in the developed world or the need for a consistent and simultaneous management of supply and demand of water resources, this chapter will focus on both the positive and negative impact that desalination projects have on the natural environment. Beyond impacts directly related to the various facilities of the project (feed seawater, pumping, plant facilities, regulating reservoir, water supply system, etc.), the main impacts of desalination projects on the environment are: energy consumption and disposal of waste effluent brine into the sea. Energy consumption is associated with the process of salt separation and pumping facilities to transport water. The ongoing technological improvements and energy recovery systems are significantly reducing this consumption. Regarding brine, its physical and chemical properties depend on the feedwater being used and the salt removing technology. In recent years, reverse osmosis has been the most commonly used technology to desalinate seawater, with conversion rates ranging from 30% to 50%. The brine effluent is in this case characterised by an excess of salinity with the presence of trace pollutants. With few exceptions, this effluent is discharged into the sea. Considering these circumstances, some fundamental questions arise: How does brine behave in the sea? What are the potential negative effects of brine disposal for the marine environment? What are the most vulnerable and sensitive marine ecosystems facing brine presence? How can negative impact be minimized? What are the most adequate locations and discharge systems for brine disposal? What aspects of plant design and management should be taken into account to minimize brine disposal impacts? What kind of preliminary studies and data collection are necessary? Which are the available tools for brine discharge behaviour modelling under different representative marine climate scenarios? etc. This chapter will address all these questions to study desalination projects from an environmental point of view, focusing their attention on the brine disposal.

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Adam D. Nemeth

In agreement with the Sustainable Development principles, set up at the 1992 Rio de Janeiro Conference, a methodology to minimize brine impact on the marine environment will be recommended in this chapter, with the aim of making compatible the use of desalination as an important water resource with the environmental protection of the marine environment. The chapter aims to be all encompassing, providing information regarding the fields of science and marine engineering (design of disposal facilities, numerical modelling, marine climate), biology and natural environment (vulnerability of ecosystems, critical salinity limits), or environmental engineering (legislation, environmental assessment, monitoring programmes, prevention and mitigation measures, etc.). All of this will be discussed, while considering the most innovative aspects of the State of the Art and taking into consideration the most recent investigations in marine and environmental engineering and biological issues related with brine disposal into the sea. Chapter 2 – This chapter will consider how the marine environment is managed and protected at an international level. It will set out a brief history of how governance of the marine environment has developed since the doctrine of Freedom of the Seas was set out by Hugo Grotius in the early 1600s through to the post World War II period where developments and triggers ultimately led to a global Law of the Sea Convention. It will then specifically examine the role of the United Nations, including discussion of the 1982 Law of the Sea Convention (LOSC), which set out to produce a comprehensive legal framework to promote the peaceful use of the oceans and its resource, together with other UN conventions related to the marine environment. The chapter will then examine the role and responsibilities of the International Maritime Organization (IMO) and its various committees, as the body responsible for establishing a comprehensive framework of legislation for shipping, including protection of the marine environment from pollution from shipping and the safety of vessels, their crews and passengers, at sea. It will then examine the contribution made by a range of Memoranda on Port State Control organisations (MOUs) which have a role in ensuring that vessels comply with the various international conventions established by the IMO and others. These MOUs, the first of which was established in 1982, provide a framework for vessel inspections to ensure that those vessels which fail to adhere to international standards, or are sub-standard in any way, can be monitored. Vessels which are found to be sub-standard can, ultimately, be prevented from operating until all deficiencies are rectified. Chapter 3 – Approximately 71% of the earth's surface is covered by oceans, and represent an enormous pool of potential microbial biodiversity and exploitable biotechnology or "blue biotechnology". This unexploited region resulted in an increasing interest to study marine microorganisms, the role of them in marine food webs, and biogeochemical cycling. In addition, to emphasize the study of marine bacteria capable of produced different novel enzymes and metabolites, represent a potential to biotechnological applications. Diverse marine microorganisms are classified into extremophiles groups, which play a main role in the biodegradation of organic matter in different marine ecosystems. One of these groups, the cold-adapted microorganisms, is interesting for processes that need cold-active enzymes at low temperatures, for example food processing and cold-wash laundry detergents. In the last decade, the focus of microbial diversity has changed due to 16S rDNA, housekeeping genes and metagenomic studies. As a result, the characterization of new sequences allowed the discovery of new genera of cultivated and uncultivated microorganisms, from samples of the marine ecosystem. These new species belong to the γand α-Proteobacteria divisions.

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Within the areas of exploration to understand the diversity of marine bacteria are subAntarctic waters of the Beagle Channel, Tierra del Fuego, Argentina. The Beagle Channel (55°07'18" S 66°25'00" W) is located at the southern end of America and is the international border between Argentina and Chile. Coastal areas are interesting to study because they are easily accessible and the water temperature ranges between 4.5 and 10°C, optimum for coldadapted microorganisms. Marine bacteria were isolated from benthonic organism‟s intestines, and seawater samples. The samples were taken from different coastal areas of the Beagle Channel; they were enriched in modified LB medium with seawater and cultivated at 4 and 15ºC. Of 296 marine bacteria isolated, 55 were characterized by ARDRA analysis, 16S rDNA sequencing, and construction of phylogenetics trees. The gene sequences allowed us to determine their association with the class Proteobacteria, members of the following genera: Shewanella, Pseudomonas, Pseudoalteromonas, Serratia, Halomonas, Alteromonas, Psychrobacter. These microorganisms showed different glycosyl hydrolases activities, within this group are cellulase, endoglucanase, exoglucanasa, xylanase, β-glucosidase, α-rhamnosidase. In this chapter, the authors focus on the studies of marine bacteria, genes, enzymes and metabolites for biotechnological applications, as well as new cold-active enzymes applied to products whose manufacturing processes are performed at low temperatures. Chapter 4 – Recently with advances in biochemical and molecular microbiological techniques, there has been a growing interest to assess the numerical and functional significance of microorganisms in different ecosystems of our planet. The marine biosphere consists of diverse assemblages of microorganisms with extreme variations in pressure, salinity and temperature. Heterotrophic nanoflagellates (HNF) with a size range from 2 to 20 µm are ubiquitous protozoan communities in marine environments. HNF are considered as primary consumers of bacteria and regulate the bacterial density and the phenotypic and genotypic composition of bacteria by selective grazing in marine environments. HNF mediated grazing is also an important ecological process in marine materials cycling by the production of dissolved organic and dissolved inorganic matter. Despite the pivotal role of HNF in marine microbial food web, the ecophysiological role of HNF is mostly neglected. In this chapter, an overview of the diversity and distribution of HNF in marine environments, seasonal variation of HNF grazing rates on bacteria, the efficacy of HNF as nutrient generators, the nutritional ecology of HNF, mechanism responsible for food bacterial selection by HNF and their contribution to the enzyme pool during selective feeding on bacteria in marine environments is discussed. Chapter 5 – The marine microbial community is still an unexplored habitat, for this reason the attention of many researchers is focused on the isolation and microbiology characterization of micro-organisms isolated from different habitats: from the polar sea, covered by ice for most part of the year, to the deep-sea hydrotherms, where the water temperature can be as high as 90 °C. The marine habitat is very complex and heterogeneous with a unique common factor: salt concentration. The molecular mechanisms of adaptation to the environment of an organism is reflected on different levels, with regards to gene and protein expression, which are intrinsically adapted to the particular physical/chemical state. Amino acid composition is strictly related to environmental adaptation, in this paper, the authors present an up-to-date overview on some features of amino acid composition of

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esterases and lipases from marine sources. In particular, the authors analysed enzymes belonging to the Hormone-Sensitive Lipase family (HSL), isolated from psychrophilic, mesophilic, thermophilic and hyperthermophilic micro-organisms. Chapter 6 – The potential for petroleum aliphatic-hydrocarbon degradation of the key bacteria in temperate seas was evaluated. As the possible key bacteria, Alcanivorax, Marinobacter and three taxonomically novel strains (one showed 96.6% similarity in its 16S rRNA gene sequence to Oleibacter marinus; and the other two showed less than 90% respective similarity to Teredinibacter turnerae and Acinetobacter johnsonii) were isolated after enrichment on crude oil in a continuous supply of Japanese seawater. In contrast to their previous results with tropical seawater, all the Alcanivorax isolates were closely related to Alcanivorax borkumensis, suggesting A. borkumensis to be the key Alcanivorax species characterized for temperate seawater. A. borkumensis strains, especially two new isolates, showed the highest activity for both n-alkane and branched-alkane degradation, indicating that these two new A. borkumensis isolates would be useful for the bioaugmentation strategy. The n-alkane-degrading activities of the Marinobacter isolate and Thalassolituus oleivorans (the already known key species) MIL-1T were the lowest, and their branched-alkanedegrading activities were not significant. These results, providing insights into petroleum biodegradation in temperate seas, will promote the rational bioremediation strategies. Chapter 7 – Seawater desalination is the main and reliable source of water supply for the Gulf countries to sustain and allow the continuing long-term socio-economic development. Building more desalination plants and increasing water production rates appears to be the answer to satisfy the rapidly increasing future water demands, with an estimated annual rate of around 15%. Of all the world's multi-national bodies of water, the Gulf itself is a uniquely small scale, almost enclosed sea and its marine environment conditions are deteriorating rapidly due to substantial construction along the shores and offshore regions, which involve sea bottom dredging for material and its deposition in shallow water to extend land for homes, recreation and industrial facilities, thus altering its coastline. Due to its location in a subtropical, hyper-arid region, its water is naturally characterized by higher temperature and salinity leading to hypersaline conditions. Therefore, any further additional loss of water by desalination plants and returned brine reject could result in increases to the Gulf's salinity, above the already high existing level. The potential impacts of seawater desalination are evaluated using a mathematical model for a semi-enclosed sea of simple geometry. Chapter 8 – The Menai Strait is situated between the Island of Anglesey and the mainland in NW Wales, UK. The Strait has a diverse and well-studied biological community, and for many years have been the subject of intensive research by scientists from Bangor University and other institutions. In 2004 the Menai Strait was designated a Special Area of Conservation under the EC Habitats Directive in recognition of its importance to marine life. Previous research in the Menai Strait revealed that concentrations of suspended particulate matter (SPM) are greater in winter than in summer, and also greater during the spring than the neap tide. Although a considerable proportion of SPM is organic, the majority of suspended sediments is inorganic. Surface inorganic loads appear to correlate positively with tidal range and wind direction, and negatively with temperature. There has been a slight increase in SPM loads throughout the second half of the 20th century, which is a cause of concern because of its potential direct and indirect effects on the local ecology, in particular algae and juvenile fish. Here the authors present an overview of a number of potential effects of SPM on the Menai Strait ecosystem. The authors emphasise the impact on filter feeders, in

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particular the mussel Mytilus edulis, which is naturally encountered in the Strait and is the subject of a thriving commercial fishery. The authors also draw attention to the potential relevance of SPM to the biological community of mud flats and salt marshes. The dynamics of SPM in relation to the tide and other oceanographic variables is then illustrated with a detailed dataset collected over more than seven tidal cycles. The data show clear signs of SPM advection, re-suspension, flocculation and disaggregation, which can be linked to the underlying physical forcing. The authors interpret the importance of SPM for the overall ecosystem functioning and management. Chapter 9 – The main objective of this presented work is to investigate the performance, deterioration and corrosion resistance of different types of concrete in the hot marine environment. and the possibility of introducing epoxy in concrete to improve its durability. The work covers the behavior of conventional concrete, reinforced concrete, epoxy repaired concrete, polymer concrete, polymer modified concrete, epoxy coated bars, concrete made with recycled materials and others. Different concrete mixes with different constituent materials were investigated and addressed. Durability was assessed by either subjecting concrete samples to sea water in the tidal zone or by putting the samples in the testing tanks of a specially manufactured accelerated marine durability system, where they were exposed to cycles of sea water wetting and hot air drying. Chapter 10 – The marine environment is of particular interest because is an important sink for many chemicals, some of which accumulate in the marine food chain. Heavy metals and bio accumulating toxic substances are introduced to the sea from land-based point and non-point sources, from atmospheric fallout and during marine transport of materials. Pollution of the marine environment is a major concern to countries having coastal and marine areas to the overall maintenance and control of the coastal ecosystem. This chapter presents an overview on the importance of monitoring chemicals (inorganic and organic) present at major or minor concentrations in samples from the marine environment (seawater/estuarine water, sediments, seaweeds and marine animals used as seafood). Chapter 11 – The existing knowledge on the sources, distribution, and composition of marine debris worldwide and its impact on marine wildlife as well as the economy, were reviewed by bringing together most of the relevant literature published so far. Marine debris (or marine litter), defined as any manufactured or processed solid material that enters the marine environment, is a greatly underestimated component of marine pollution. Although there are various types of litter, plastics (synthetic organic polymers) make up most of the marine debris worldwide. The important properties (light, strong, resistant to degradation, and low-cost) that make plastics so widely used are also the reasons why plastics are a serious hazard to the marine environment, where they gradually accumulate and may persist for decades. Most marine debris originates from land-based activities, and the main sources include storm water discharges, municipal landfills located near the coast, riverine transport of waste from landfills and other sources, discharges of untreated municipal sewage, the plastic industry and other industrial facilities, unregulated disposal of litter due to absence of waste services or landfills, tourism, all types of vessels, offshore oil and gas platforms, and aquaculture installations. Litter may concentrate on the seafloor and reaches very high densities, especially in coastal areas but also in some accumulation zones in the open sea. Densities that reach many thousands or even millions of items per hectare have been reported on the seafloor or along beaches. Marine debris is a serious threat to marine life and may negatively affect the populations of many species. The entanglement of marine species,

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especially marine mammals, seabirds, turtles, fish, and crustaceans has been frequently described as a serious mortality factor. Marine species may ingest debris items (mostly plastics), presumably mistaking them for prey, which has many harmful effects on their physical condition and survival. Toxic contaminants like PCBs may enter marine food chains through ingested plastics with potentially very negative effects. Drift debris can increase the distribution range of certain marine organisms and assist in the invasion of alien species, which is a primary threat to global biodiversity. High marine litter densities have a potential effect on the structure of benthic communities by altering the characteristics of the local biotope, and may act as the means for the invasion of many hard-substratum species that could displace indigenous fauna due to competition or predation. Marine debris, especially derelict fishing gear, causes substantial damage to coral reefs and coral facies. Marine debris has a considerable economic impact, mainly due to lost tourism, reduction of commercial fish and crustaceans stocks due to ghost fishing, the time and expense of rescue operations for entangled or damaged vessels, costs of clean ups of beaches and coral or rocky reefs, and increased conservation costs of endangered marine species. The effect of marine debris on both marine fauna and the human economy is expected to become a more prominent issue in the future as marine debris concentration in the marine environment continuously increases.

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Chapter 1

DESALINATION IMPACTS ON THE MARINE ENVIRONMENT P. Palomar,1,2 and I. J. Losada2 1

Ministry of the Environment and Rural and Marine Affairs, P. San Juan de la Cruz s/n. 28004 Madrid, Spain 2 Environmental Hydraulics Institute “IH Cantabria”, Universidad de Cantabria, Avda. de los Castros s/n. 39005 Santander, Spain

ABSTRACT

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If seawater is considered to be an inexhaustible natural resource, then desalination is a good alternative to be used in scarce areas with irregular river flows or those in which conventional water sources are insufficient or overexploited. Leaving aside the debate regarding excessive water consumption in the developed world or the need for a consistent and simultaneous management of supply and demand of water resources, this chapter will focus on both the positive and negative impact that desalination projects have on the natural environment. Beyond impacts directly related to the various facilities of the project (feed seawater, pumping, plant facilities, regulating reservoir, water supply system, etc.), the main impacts of desalination projects on the environment are: energy consumption and disposal of waste effluent brine into the sea. Energy consumption is associated with the process of salt separation and pumping facilities to transport water. The ongoing technological improvements and energy recovery systems are significantly reducing this consumption. Regarding brine, its physical and chemical properties depend on the feedwater being used and the salt removing technology. In recent years, reverse osmosis has been the most commonly used technology to desalinate seawater, with conversion rates ranging from 30% to 50%. The brine effluent is in this case characterised by an excess of salinity with the presence of trace pollutants. With few exceptions, this effluent is discharged into the sea. Considering these circumstances, some fundamental questions arise: How does brine behave in the sea? What are the potential negative effects of brine disposal for the marine 

Email: [email protected] , [email protected]

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P. Palomar and I. J. Losada environment? What are the most vulnerable and sensitive marine ecosystems facing brine presence? How can negative impact be minimized? What are the most adequate locations and discharge systems for brine disposal? What aspects of plant design and management should be taken into account to minimize brine disposal impacts? What kind of preliminary studies and data collection are necessary? Which are the available tools for brine discharge behaviour modelling under different representative marine climate scenarios? etc. This chapter will address all these questions to study desalination projects from an environmental point of view, focusing our attention on the brine disposal. In agreement with the Sustainable Development principles, set up at the 1992 Rio de Janeiro Conference, a methodology to minimize brine impact on the marine environment will be recommended in this chapter, with the aim of making compatible the use of desalination as an important water resource with the environmental protection of the marine environment. The chapter aims to be all encompassing, providing information regarding the fields of science and marine engineering (design of disposal facilities, numerical modelling, marine climate), biology and natural environment (vulnerability of ecosystems, critical salinity limits), or environmental engineering (legislation, environmental assessment, monitoring programmes, prevention and mitigation measures, etc.). All of this will be discussed, while considering the most innovative aspects of the State of the Art and taking into consideration the most recent investigations in marine and environmental engineering and biological issues related with brine disposal into the sea.

INTRODUCTION

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Water requirements The global water demand is increasing exponentially due to the development of populations and economic activities demanding it, such as agriculture, industry or tourism. The data on water consumption in the world is provided by the United Nations (UN, UNESCO, and FAO) reveal that worldwide, agriculture accounts for 70% of all water consumption, compared to 20% for industry and 10% for domestic use. In industrialized nations, however, industries consume more than half of the water available for human use. Freshwater withdrawals have tripled over the last 50 years. Demand for freshwater is increasing by 64 billion cubic meters a year (1 cubic meter = 1,000 liters)   

The world‟s population is growing by roughly 80 million people each year. Changes in lifestyles and eating habits in recent years are requiring more water consumption per capita. The production of biofuels has also increased sharply in recent years, with significant impact on water demand. Between 1,000 and 4,000 litres of water are needed to produce a single litre of biofuel. Energy demand is also accelerating, with corresponding implications for water demand.

The water average consumption worldwide per capita is 600m³/hab*year, varying from some countries to other. For example, in Europe, the consumption is 3.500l/hab*day, while in Asia es 1.500l/hab*day, and North America it is 5.100l/hab*day and in Africa, 685l/hab*day.

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Countries with a highest availability of water resources are: Brazil, Russia, Canada, United States, China and Indonesia, which receive 22.070 km3/year [1], compared to the 171 km3/year of the European Union. By contrast, natural water resources are very scarce in Cyprus, Israel, Jordan, Singapore, Libya and UAE, which only reach 4 km3 /year.

Water Sources An effective water policy must consider appropriate demand management strategies, as well as the recovery of costs for water services, education for water saving practices and full implementation and enforcement of environmental legislation, in combination with research and investment in new alternative supply options. Alternative water sources such as water recycling, water reuse and desalination are very important tools in the future water balance between water supply and demand, and therefore in guaranteeing a prolonged availability of this resource. Forty-one percent of the world population lives in areas with a marked water deficit (2.300M inhabitants) and it is expected that by the year 2025 this amount will reach 3.500M. Considering that almost one quarter of the world's population lives less than 25 km from the coast, seawater could become one of the main sources of freshwater in the near future. Between all uses, the 0.34% is from desalination, 73.4% surface water and 18.2% groundwater. In drinking water use the 3.35% is from desalination [2].

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DESALINATION AS A WATER SOURCE Desalination is a rainfall independent source of water for security long term water supplies. Is is expected that in the medium term desalination would be an optimum to apply to different uses of human consumption, such as irrigation. Desalination is any of the several processes involved in removing dissolved minerals (especially salt) from seawater, brackish water, or treated wastewater. A number of technologies have been developed for desalination, including thermal processes and membrane technologies. In the present chapter we will focus on seawater desalination, with the aim of obtaining fresh water for human supply, irrigation or industrial facilities.

Desalination Global Development. Leading Countries Seawater desalination has gained importance in coastal countries where conventional water sources are insufficient or overexploited. It can be considered an inexhaustible natural source that generates a high quality product and guarantees demand supply. On the other hand, desalinated water is expensive (due to high energy consumption) and the brine discharged into the sea has negative effects on some important marine ecosystems. According to 20th International Desalination Association (IDA) Worldwide Desalting Plant Inventory, the production capacity of all desalination plants worldwide was around 44 million cubic meters per day (Mm³/day) by the end of 2006, and is expected to more than double by 2015. This production includes: seawater, brackish water, river water, wastewater, brine, and pure water facilities, which are either in construction, online, or presumed online [3].

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Figure 1. Major desalted water producing countries in the world (Source [3]).

Fifty-seven percent of the plants are Reverse Osmosis (RO) desalination plants, while 27.1% are Multi -Stage Flash distillation plants (MSF). Nineteen percent is produced from brackish water sources and 63% from seawater sources [3]. With respect to location, 6% of the plants are in the Asian Pacific region, 7% in America, 10% in Europe and 77% in the Middle East and North Africa [3]. The six countries with a highest desalination water production capacity are: Saudi Arabia (11Mm³/day), United Arab Emirates (8.2Mm³/day), United States (8Mm³/day), Spain (5.2Mm³/day), Kuwait (2.8Mm³/day) and Algeria (2.6Mm³/day). At the moment the biggest desalination plant in the world is in Ashkelon (Israel), with a 330.000m³/day production capacity, which supplies water to 1.200.000 people. The second biggest one is the Torrevieja (Spain) desalination plant, with a production capacity of 240.000m³/day. Figure 1 shows a map with the highest desalination production in the world [3]. The development of desalination during the last century has been significantly influenced by changes in the prices of fossil fuels, mainly oil: 

50´s: First desalination plants, thermal technologies in Multi-Stage Flash distillation (MSF) and / or multi-effect in vertical tubes (MED), in Jeddah, Kuwait, etc.  60´s and 70´a: Reverse osmosis technologies start to be developed.  80´s: rising of fuel prices by the oil crisis, but the rise is offset by advances in the design of the various techniques of design, so that the desalination capacity continues to increase, mainly with Reverse Osmosis plants.  1986-1988: New oil crisis. Reduction in desalination investments.  1986-2010: The increase in desalination facilities and techniques follows a steady pace. Figure 2 shows the evolution of the capacity contracted and commissioned worldwide from 1980 to 2009.

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Figure 2. Evolution of the global desalination worldwide (Source: GWI DesalData/IWA).

Figure 3. Evolution of capital expenditure in desalination plants (Source: DesalData/Desalination Markets 2010).

Figure 3 shows the evolution of the amount of capital invested in desalination and the forecast for 2016, distinguishing between the different technologies available in the market [4]. The significant role of reverse osmosis, followed by thermal plants MSF, which is mainly used in Middle Eastern countries, is remarkable.

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Water Desalination Technologies Several technologies have been implemented for salt separation. Table 1 shows the main technologies available in the market, indicating the separation mechanism, process involved and the kind of energy used. Table 1. Desalination technologies and their features Separation Mechanism

Energy

Process

Name Multi Stage Flash (MSF)

Water Separation

Thermal + Electrical

Multi Effect Distillation (MED) Termal Vapour Compression (TVC) Solar Desalination (SD) Freezing Formation of hydrates

Evaporation

Crystalization

Electrical

Evaporation and filtration Evaporation Ionic filtration

Electrical

Ionic migration

Chemical

Others

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Salt Removal

ED, 2.220.133 4%

Membrane Distillation (MD) Mechanical Vapor Compression (MVC) Reverse Osmosis (RO) Electrodialysis (ED) Ionic Exchange (IX) Extraction

Other, 901 233 1%

m³/day

MED, 5.629.368 9%

RO, 37.066.568 59% MSF, 17.300.196 27%

RO

MSF

MED

ED

Other

Figure 4. Desalination technologies available in the market worldwide (Source: GWI DesalData/IWA, 2005).

Figure 4 shows the percentage contribution of each technology to the world desalination technologies market in 2005. As shown, multi-stage distillation and particularly reverse osmosis stand out compared to others.

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In thermal processes water is heated until it evaporates, and salts are separated. Subsequently, water is condensed to produce potable water. In industrial processes, water is heated until it reaches boiling temperatures, by reducing pressure in boilers operating at descending temperatures. Among these techniques one of the most important is the MultiStage Flash evaporation. In membrane desalination, salt water is passed through special membranes, which retain the hypersaline effluent and produce fresh water. There are two main types: Electrodialysis Membranes, in which water supplies are kept under pressure to retain the salts by applying an electrical potential, and Reverse Osmosis membranes, which are the most commonly used nowadays. The product of the desalination process is high quality fresh water, free of salts and minerals. It is mainly used for urban supply, so it is subjected to a pre-treatment process by adding the minerals necessary for human consumption. In some areas, where agriculture stands as economically important activity, desalinated water is also used for crop irrigation. The main effluent waste product from the seawater desalination process is a concentrated brine effluent. Its physical properties and chemical composition depend on the technology used for desalination.

Multi-Stage Flash Thermal Distillation Desalination (MSF) Multi Stage Flash distillation is a thermal process in which water boils at progressively lower temperatures (120º - 90º) while also being subjected to progressively lower pressures in the evaporation boilers (4 to 40 stages). The steam obtained during this process is converted to fresh water by condensation. The waste effluent obtained (at 100ºC temperature) is mixed with cold water to reduce its excess of temperature to 10 ° C above the receiving water. The main disadvantages of this technique are: high energy consumption and environmental impacts of the waste effluent (brine) discharged. MSF plants are generally coupled to power generation plants, so that the brine is often mixed with cooling water, generating a final waste effluent which is less dense than seawater. Because of the high energy consumption, most MSF plants operate in oil-producing countries. Reverse Osmosis Desalination Technology (RO) Reverse osmosis is a desalination process in which seawater passes through permeable membranes under high pressure. The natural osmosis process is reversed and while the semipermeable membranes retain the salts, they allow the water molecules to pass through, obtaining fresh water and a brine effluent waste product. In reverse osmosis, seawater is pre-treated to remove particles (sand, shells or seaweed), which otherwise would clog the membranes. Pre-treatment includes screening, sedimentation, filtering and addition of chemical additives to seawater. The RO is a technology which is widely used in desalination of marine waters (seawater desalination reverse osmosis: SWRO), due to its lower energy consumption with respect to distillation technologies. RO is more common worldwide, because it is cheaper and more flexible technology. The main disadvantage of SWRO is the impact of the concentrated waste effluent discharg on the marine environment. Since SWRO (seawater reverse osmosis) is expected to be the most important desalination technology in the future, this chapter will pay particular attention on it.

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The operational process includes: seawater intake and inlet; pre-treatment; high pressure pumping system; reverse osmosis membranes; outlet for discharge; desalinated water posttreatment and distribution system. Figure 5 shows a diagram of the operation scheme in a seawater reverse osmosis plant.

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Figure 5. Operation scheme of a reverse osmosis plant.

Figure 6. Facilities in a SWRO desalination plant. 6A): Tubular membrane modules. 6B) Tubular membrane. 6C) Cartridge Filters. 6D) Micro filtration.

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Figure 6 shows photographs of the battery of filters and reverse osmosis membrane modules in a SWRO desalination plant located in Carboneras (Almería, Spain). Table 2 shows some of the most important features of RO and MSF plants. Differences in energy consumption, economic costs and characteristics of the seawater concentrate (brine) can be noted. Table 2. Main characteristics and differences between RO and MSF desalination plants MSF

RO

Flash Evaporation Electrical: 2.5-5KWh/m³ Thermal: 40 -120 KWh/m³

Solution – diffusion Electrical: 3-4.5KWh/m³ Thermal: None

Total capital costs

High

Low

Energy requirements

Medium

Low

Plant top temperatura level

 120ºC

Seawater temperatura. Limit  35ºC

Medium - High

Very low –low

Medium

High

0.1 – 0.2

0.3 – 0.5

Low (At technical limit)

High

Physico-chemical principle Energy consumption

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Tolerance to changes to in seawater composition Maintenance requirements Ratio between product to total seewater flow (conversion) Potential for further requirements

THE ENVIRONMENTAL IMPACT OF DESALINATION PROJECTS. PREVENTION AND MITIGATION MEASURES Environmental Impact by Type of Desalination Process The main environmental impacts of desalination projects are associated with construction, marine structures, waste water disposal and energy consumption. The importance of these impacts depends on the type of technology used in salt separation. MSF thermal plants work with small conversion rates (10% - 20%), so they need greater amounts of feedwater to produce the same volume of fresh desalinated water. The consequences are: a higher water intake, pipes and outfall structures, increased energy losses in pipes and more concentration of chemical additives required. Energy consumption with this technology is very high, which means a higher fuel consumption [5], and thus, emissions of greenhouse gases. The waste water effluent has a slight hypersalinity with respect to the seawater receiving body. However, it has a significant thermal and chemical pollution capability, thus affecting water quality. In general, MSF brine is less dense than seawater, so it floats and rises to the surface, reducing impact risk on benthic ecosystems, but increasing

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the risk of contamination of recreational or commercial fishing areas. The combustion processes that take place in the plant generate emissions of air pollutants. Finally, visual impact is also significant because of the large amount of piping, tanks and chimneys associated with such plants. RO plants work with conversion rates of 40 - 50%, so that the need of feedwater is smaller, as are the environmental impacts associated to it. Energy consumption is high but much lower than in MSF plants. The waste effluent or brine has no chemical or thermal pollution, but the salt concentration is very high, making it denser than seawater and thus increasing the risk of negative effects on stenohaline benthic ecosystems. RO plants do not include combustion processes resulting in no air pollution. Its visual impact is less because the plants are usually compact. However, an additional solid waste is generated by RO plants compared to those of MSF, since membranes need to be changed at a certain frequency and at the moment they are not reusable [6].

Desalination Plant Location

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Desalination projects include different infrastructures: water intake, desalination plant, storage reservoir, pumping system, distribution system, evacuation and brine discharge system, etc. They also require connection to energy supply. The location of the plant is one of the most important decisions to minimize the occupation and impacts on protected areas and vulnerable species. Plants should be located close to the ocean, to a power source, preferably in industrial zones and away from urban and residential areas, to avoid noise impacts.

Impacts during the Construction Phase. Prevention and Mitigation Measures Terrestrial Environment Impacts during the construction phase include: excavation and trucking works, land occupation, barrier effect, destruction of vegetation, visual impact, etc. These negative effects are associated with the construction of the following elements of the project:     

Desalination plant. Water intake, pipes, outfalls, etc. Storage reservoir and tanks. Distribution and supply systems. Medium voltage power lines and substations.

Figure 7 shows the photographs of some of these elements during the construction of a desalination plant in Aguilas (Murcia, Spain).

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Desalination Impacts on the Marine Environment

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Figure 7. Storage reservoir, water pipes and outfall works during the construction of a desalination plant.

The main prevention measure is an appropriate location of the desalination plant and the associated structures, avoiding protected areas and potential impacts on vulnerable species. Other specific preventive and mitigation measures are: 

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   

Placement of small fences in the perimeter of trenches and excavation areas in order to prevent fauna (turtles, small mammals, etc.) from falling into them. Frequent irrigation of machinery ways, storaging areas of digged material, etc., to prevent small sediment suspension by wind. Signposting and enclosure of the areas used by work machinery. Wooded perimeter protection. Storing the organic soil layer until construction works have concluded and then placing it back on the ground.

Marine Environment Among the most important and significant impacts of seawater desalination projects are those associated with marine structures construction, as the water intake and outlet:   

Impacts on the water quality and on the benthic organisms present in the receiving water body, due to dredging of trenches and placement of new infrastructures. Impacts on navigation and fishing because of the presence of new infrastructures. Impacts on the coastal dynamics of beaches by the presence of structures in the active beach profile zone, which may affect longshore and cross-shore sediment transport.

The second and third impacts can be avoided by locating the marine structures in zones with no interference with other applications or processes, and informing the competent The Marine Environment: Ecology, Management and Conservation : Ecology, Management and Conservation, Nova Science Publishers,

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authorities of these activities. The following pages are dedicated to impacts and prevention and mitigation measures related to marine dredging and location of pipes. To place underwater pipelines (associated with water intake and outfall), seabed dredging and trenching are conducted. The impacts associated with dredging are:   



Occupation and physical destruction of benthic ecosystems located in the dredging area. Effects on water quality due to increase in suspended particles and turbidity (suspended solid concentration in the water column). Reduction in the percentage of light passing through the water column and reaching the seabed. This reduction can affect benthic primary producers. Some scientific studies carried out with Posidonia oceanica seagrasses show that suspended solid concentrations higher than 20mg/l adversely affect their growth [7]. Burial of benthic organisms by suspended solids sedimentation. These particles may be transported by ambient currents and therefore affect benthic organisms even far away from the dredging area. Some scientific studies focused on the seagrass Cymodocea nodosa reveal a critical thickness of 10cm, which must not to be exceeded if to burial and suffocation of the plant are to be avoided [7].

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Figure 8 shows photographs taken during excavation and placement of the outfall of a desalination plant in Spain. To minimize the impacts associated with the maritime construction phase, the following prevention and mitigation measures are proposed. 1) To carry out dredging during calm hydrodynamic periods (as small and shorter waves, weak currents, etc.) so as to reduce the risk of suspended sediments transport and limit expansion of the area affected by the dredge. This measure minimizes the impact exerted on benthic ecosystems which are found at a certain distance form the dredging area. 2) To use turbidity curtains, which are physical barriers designed to control and contain the dispersion of silt and turbidity from the dredging area. These waterproof material curtains, which are sewn to each other, keep themselves vertical thanks to heavy elements which are attached to them. They prevent spread and propagation of suspended material into the upper layers of the water column, covering 2 -3 m vertically from the water surface to the bottom. They become more effective in calm waters and if attached laterally to a physical element (dam, breakwater, etc.). Figures 9, 10 and 11 show turbidity curtains used in the excavation of the outfall trench of the Aguilas desalination plant (Murcia, Spain). The use of these screens prevented the impacts of dredging from reaching the Posidonia oceanica meadow lying 100 m from the dredging area:

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Desalination Impacts on the Marine Environment

Figure 8. Trench dredging and outfall placement of a desalination plant.

Figure 9. Pontoon boat equipped with a backhoe for trench dredging (Source: ACUAMED, www.acuamed.com). The Marine Environment: Ecology, Management and Conservation : Ecology, Management and Conservation, Nova Science Publishers,

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Figure 10. Turbidity curtains weighted in a breakwater, and a dredge working (Source: ACUAMED).

Figure 11. Detail of turbidity curtains. The upper image shows a detail of the floats closer to the breakwater; details of the fastening system of the floats to the curtains; details of the curtain, showing how the sediment adheres to the curtain. In the photos below there are two adjoining curtains without sewing, and a detail of the union of the curtains to the float. (Source: ACUAMED).

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3) Use of innovative dredging techniques which minimize the area affected by dredging, digging and placement of the marine pipes and structures. Figure 12 shows the image of a “post trenching” dredge digging a trench on the seabed and placing an outfall. Post trenching is a technique which minimizes the seabed area affected by the trench and also minimizes the suspension of silt and fine material from the sandy bottom. As an example, with this system, a 4 m wide trench, affects an area of about only 10 m.

Figure 12. Seabed Dredging by the post trenching technique.

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4) Digging a microtunnel below the seabed, to bury pipes when there are protected benthic ecosystems (seagrasses, coral reefs, etc.) in the area to be occupied by the trench. It is important to point out that the rhizomes of some seagrasses, as Posidonia oceanica, reach depths of about 1.5 m below the bed. At present, this technique has limitations of maximum length and diameter of the tunnel. Figure 13 shows a scheme of a microtunnel for burial pipe location below the seabed, and pictures of the microtunnel which was made in the SWRO desalination Plant of San Pedro del Pinatar (Murcia, Spain).

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Figure 13. Microtunnel scheme. 13A) Digging the tunnel. 13B) Placing the pipe. (Source: J. Salinas, Universidad de Almería).

5) Modelling dredging solids suspension, transport and spreading of suspended material. The model must take into account the dredging system configuration, sediment properties, and the prevailing ambient conditions in the marine environment. Based on the results, the dredging system needs to be designed to guarantee good water quality and conservation of marine ecosystems. It is important to make sure that the model used is correctly calibrated.

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Figure 14 shows a diagram of a dredging and sediment plume modelling.

Figure 14. Modelling of a sediment plume caused by dredging a trench, near a protected seagrass area.

Impacts during the Operation Phase of the Plant Energy Requirements Starting up a desalination plant requires high energy input to operate the following facilities:

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Desalination Impacts on the Marine Environment  

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

Pumping system to transport feed seawater from the intake to the desalination plant. Reverse osmosis process: energy is needed for the salt separation process. In MSF plants this energy takes the form of water vapor which condenses inside heat exchangers which are located in the brine boilers. In RO plants, electricity is required to operate the pumps which provide the necessary pressure to the feedwater so that the reverse osmosis process can take place. Pumping system to transport fresh water to the storage reservoir and the distribution system.

Regarding impacts, the energy requirements of desalination plants implie substantial fossil fuels (for thermal plants) and electricity consumption (in the case of RO plants), which in turn involve significant gas emissions per m³ of desalinated water, mainly CO2. The energy requirement is one of the main environmental impacts of desalination projects and a major cause of the high cost of desalinated water. This problem is especially relevant in MSF thermal plants, with values of 8 - 14 Kwh/m³ for conventional thermal electricity and 6 8 kwh/m³ for advanced thermal conversion techniques. In reverse osmosis plants energy consumption is important, but less than in MSF plants. Thanks to improved technologies, consumption is declining. In the last ten years, for example, consumption has fallen by almost half the amount, with current values reaching 3.5 - 2.5 kWh per m3 of desalinated water [8]. Existing MSF and RO plants are powered mainly by conventional sources of energy. Greenhouse gas (GHG) and particles emissions depend on the source of energy. As an example, Table 3 shows the emissions associated to different fossil fuelled plants [9]. The emission of greenhouse gasses associated to desalination plant projects indirectly affects the oceans and seas, because they uptake the anthropogenic carbon dioxide from the atmosphere (acting as greenhouse gasses sinks), resulting in the acidification of seawaters. To minimize the energy requirements of desalination plants, technological improvements have been developed during the last years, as prevention and mitigation measures. Table 3. Greenhouse gas emissions in fossil fuelled desalination plants MSF (Mt/year)

RO (Mt/year)

CO2

SOX

NOX

Particles

CO2

SOX

NOX

Particles

Coal fired

264.5

0.33

0.54

0.04

32.2

0.04

0.07

0.005

Oil fired

216.2

1.31

0.3

0.03

25.7

0.16

0.04

0.003

Gas Turbina (CC)

141.6

0.01

0.23

0.01

12.9

0.001

0.02

0.001

In RO plants, these improvements focus on the installation of more efficient highpressure pumping equipment and hydraulic energy recovery systems. These recovery systems utilize and return back to the process the free energy accumulated within the brine which leaves the membrane modules (about 55% - 60% of the energy used in high-pressure pumps). There are a variety of energy recovery devices. Traditionally, Pelton turbines were used, driving an auxiliary high-pressure pump which supplies seawater to the membrane modules reducing feedwater and energy consumption of the first pump. Recently, exchange pressure

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systems have been imposed as the chosen energy recovery systems because they recover 95% -98% of the brine residual energy, which is reinvested in pumping. They exchange pressurized concentrated salt water within the modules with outside seawater, using the “rotating door” principle showed in figure 15. Although these isobaric systems were limited to small plants, nowadays they can be adapted to larger ones (> 20,000 m³ / day).

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Figure 15. Exchange of pressurized concentrated salt water with seawater (Source: [10]).

The "rotating door" has two compartments: one filled with pressurized concentrated salt water, and another one filled with seawater. The "door" rotates 180 degrees and exchanges the positions of the two compartments (as seen on the left hand side of figure 17). This allows it to introduce seawater into the high-pressure line of the modules, releasing pressurized concentrated salt water to the seawater line. The seawater in the right compartment now flows towards the membranes and is replaced by another dose of concentrated salt water. The concentrated salt-water in the left compartment flows away and is replaced by fresh seawater. The "door" then rotates 180 degrees again. The operation involves pressurizing seawater and depressurizing concentrated salt water. Since water is incompressible, these processes do not involve consumption or waste of energy [10]. Figure 16 shows the energy recovery systems, after a RO process, in desalination plants. Left image shows Pelton turbines in the desalination plant of Carboneras (Almería, Spain), and right image shows an isobaric energy recovery system in the desalination plant of Tordera (Gerona, Spain). As shown on the picture, each membrane module is attached to an isobaric system, recovering part of the energy utilized during the reverse osmosis process. Coupling of renewable energy sources (RES) and desalination systems is holding great promise. Among viable options, the use of energy from wind turbines on land and offshore, using the energy associated with wave processes and seas, and the use of photovoltaic solar energy are currently considered. This measure would require the construction of small plants (