Manual on hydrochemistry: Educational-methodical handbook 9786010450936

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AL-FARABI KAZAKH NATIONAL UNIVERSITY

S. Romanova

MANUAL ON HYDROCHEMISTRY Educational-methodical handbook

Almaty «Qazaq University» 2020

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UDC 556.11:504.4(06)285.21 LBC 24.4я73 R 42 Recommended for publication by the Academic Council of the Faculty of Chemistry and Chemical Technology and publishing board al-Farabi KazNU (Protocol №2 dated 15.01.2020) Reviewer Senior lecturer PhD Sh. Nazarkulova

R 42 

Romanova S. Manual on hydrochemistry: Educational-methodical handbook / S.M. Romanova. – Almaty: Qazaq University, 2020. – 112 p. ISBN 978-601-04-5093-6 Educational-methodical handbook is intended for students and graduate students of universities specializing in the chemistry of natural waters. It includes recommendations on work related to the study of natural water chemistry and methods of field and laboratory analysis of water chemistry components (main ions, organic substances, dissolved gases, pH and eH values, nutrients, some contaminants and trace elements), as well as a number of works on applied hydrochemistry. The devices used for sampling are described, as well as instructions on preliminary preparation and preservation of natural water samples. Metrological assessment of measurement methods is presented. Educational-methodical handbook can be used by specialists in production and research laboratories.

UDC 556.11:504.4(06)285.21 LBC 24.4я73 ISBN 978-601-04-5093-6

© Romanova S., 2020 © Al-Farabi KazNU, 2020

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CONTENT INTRODUCTION .............................................................................................. 5 1. ORGANIZATION OF WORK TO STUDY THE CHEMICAL COMPOSITION OF NATURAL WATERS ....................... 7 2. METHODS OF CHEMICAL ANALYSIS OF NATURAL WATERS ......... 9 2.1 Metrological assessment of measurement methods ...................................... 9 3. WORK PERFORMED IN THE FIELD ......................................................... 16 3.1 Workflow...................................................................................................... 16 3.2 Sampling of natural waters ........................................................................... 16 3.2.1 General provisions ..................................................................................... 16 3.2.2 Water sampling devices used for water sampling ...................................... 18 3.2.3 Preliminary preparation and preservation of samples ................................ 20 3.2.4 Sample storage........................................................................................... 20 3.3 Safety precautions when working on water bodies ....................................... 21 3.4 Identification of unstable components of the chemical composition of natural waters............................................................................. 22 3.4.1 Determination of the physical properties of water ..................................... 22 3.4.2 Determination of hydrogen ion concentration, pH value ........................... 24 3.4.3 Determination of dissolved gases .............................................................. 28 3.4.3.1 Determination of oxygen ........................................................................ 28 3.4.3.2 Determination of carbon dioxide ............................................................ 31 3.4.3.3 Determination of aggressive carbon dioxide........................................... 33 3.5 Field hydrochemical laboratories (FLWA, RLWA, LPW, HL).................... 34 3.6 Determination of nutrient compounds using FLWA and RLWA ................. 37 3.7 Determination of water oxidation ................................................................. 40 3.8 Determination of chemical oxygen consumption ......................................... 43 4. WORKS PERFORMED IN THE LABORATORY ....................................... 46 4.1 Determination of main ion content ............................................................... 46 4.1.1 Determination of calcium ions ................................................................... 46 4.1.2 Determination of magnesium ions ............................................................. 47 4.1.3 Determination of total stiffness.................................................................. 48 4.1.4 Determination of sulphate ions .................................................................. 49 4.1.5 Determination of carbonate and hydrocarbonate ions using direct and backward titration ............................................................. 50 4.1.6 Determination of chloride ions .................................................................. 53 4.1.7 Determination of the amount of sodium and potassium ............................ 54 4.1.8 Determination of dry residue ..................................................................... 55 4.2 Determination of nutrient content ................................................................. 56

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4.2.1 Determination of nitrites ............................................................................ 56 4.2.2 Determination of nitrates ........................................................................... 58 4.2.3 Determination of small quantities of iron .................................................. 61 4.2.4 Determination of phosphate ....................................................................... 62 4.2.5 Determination of silicic acid ...................................................................... 64 4.3 Identification of trace elements..................................................................... 65 4.3.1 Determination of fluorine .......................................................................... 65 4.3.2 Determination of boron ............................................................................. 66 4.3.3 Determining the amount of bromine and iodine ........................................ 67 4.3.4 Determination of iodine ............................................................................. 69 4.3.5 Determination of copper and zinc .............................................................. 71 4.3.6 Determination of manganese ..................................................................... 77 4.3.7 Lead determination .................................................................................... 79 4.3.8 Determination of cadmium ........................................................................ 81 4.4 Identification of pollutants............................................................................ 85 4.4.1 Definition of non-ionic SS (Synthetic Surfactants) ................................... 85 4.4.2 Determination of phenols .......................................................................... 86 4.4.3 Determination of petroleum products ........................................................ 89 4.4.4 Spectrophotometric determination of reducing sugars in fresh water ........................................................................ 93 5. WORKS ON APPLIED HYDROCHEMISTRY ............................................ 96 5.1 Determination of water stability in relation to concrete ................................ 96 5.2 Determination of removable and residual stiffness ....................................... 97 5.3 Determination of carbonate stiffness ............................................................ 99 5.4 Trial water softening with the lime-sodium method ..................................... 99 5.5 Ion-exchange methods of water softening. Determination of cationite exchange capacity under static conditions by 0.1 N sodium hydroxide solution .............................. 100 5.6 Determining the optimum dose of coagulant for water clarification ......................................................................................... 103 5.7 Determination of residual chlorine in tap water ............................................ 104 5.8 Determination of the self-cleaning capacity of natural waters from carbohydrates.................................................................................. 105 6. ROUNDING AND RECORDING OF CHEMICAL WATER ANALYSIS RESULTS ....................................................................... 108 LITERATURE ................................................................................................... 110

 

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INTRODUCTION Natural water, in contact with a huge number of different minerals, gases and organic substances in its circulation, includes a significant number of chemical elements. Natural waters are solutions of complex composition with a very wide range of dissolved substances in terms of their number, concentration, nature and phase state. Currently, with some convention, the chemical composition of natural waters is divided into the following 5 groups: 1. main ions – (content in the largest amount by mass of Cl–, SO 24  , НСО 3 , CO 32  , Na+, K+, Mg2+, Ca2+); 2. dissolved gases (O2, CO2, N2, H2S, CH4, etc.); 3. nutrient elements (compounds N, P, Si, Fe); 4. organic substances; 5. microelements. The composition of water largely determines the quality of products of many industries. Every year increases the need for more detailed information on the chemical composition of natural waters. Issues of rational integrated use of water resources and their effective protection are still relevant today. No less important problem is the efficiency of obtaining hydrochemical information and its comparability. The manual includes the description of methods used for identification of substances that are very common in surface waters, which are necessarily identified virtually in all selected samples, and substances that are relatively rare. Practical classes in hydrochemistry are held in order to familiarize students with the methods of volumetric, weight, colorimetric and other analyses as applied to the determination of the basic ion composition, indicators of the physical and chemical environment, the content of unstable components, nutrients, organic substances and trace elements. A number of works on applied hydrochemistry are presented. The manual is designed to provide students with basic skills in the chemical analysis of natural waters and assessment of its results in 5

order to obtain the ratio of chemical components in waters and some other hydrochemical characteristics. Students are offered the most common in hydrochemical practice, rather fast, convenient and accurate methods of analysis, which can be applied both in stationary and field conditions. The water sampling, pre-treatment and analysis procedure are very important and crucial steps in any hydrochemical, hydrological and hydroecological study. Over time, errors in calculations can be detected and corrected, and the results of the chemical analysis can be processed and interpreted differently; ultimately, the task can be formulated differently. It is impossible to correct incorrect results of the analysis and not to solve any problems on their basis now and in the future. This should always be kept in mind by the specialist performing chemical analysis of natural waters.

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1 ORGANIZATION OF WORK TO STUDY CHEMICAL COMPOSITION OF NATURAL WATERS Based on the results of the analysis of a single water sample, it is possible to get only the most superficial idea of the specific features of its chemical composition. Obviously, such data will not reflect the complex changes that occur with the chemical composition of natural waters during the year, season, and, sometimes, even a day. Study of the hydrochemical regime is possible only by organizing stationary observations of the chemical composition for at least one year. In most cases, expeditionary visits to the object of study should be organized to perform this task. The means transportation are cars, motor boats, boats or ships. A water analysis field laboratory (FLWA, RLWA) is needed to perform chemical analyses directly at the facility, and an unstable components laboratory (UCL) is needed to determine substances whose concentration changes rapidly over time. It is desirable to establish a stationary chemical laboratory near the observation point. The obligatory equipment of the research expedition for the study of chemistry of natural waters is as follows: containers for water sampling – glass bottles of 0.5 liters capacity (packed in wooden boxes); polyethylene canisters of 1, 2, 3, 5 liters capacity (the volume of containers depends on the type of analysis); bathometer – means for sampling from depth; new galvanized or enameled bucket for sampling from the surface. Samples and results of analyses are recorded in a field log or in standard chemical water analysis forms. Thus, the organization of systematic observations on the study of the hydrochemical regime of any type of reservoir consists in carrying out works at the site (in the field) and in the chemical laboratory, where the main part of the chemical analyses is performed. 7

The following types of water tests are used: Reduced analysis – physical properties (temperature, smell, transparency, color, taste), as well as pH values, stiffness (total and carbonate) and components of the chemical composition: СО2, 2  НСО 3 , CO 32  , Cl–, SO 4 , NО 3 , NО 2 , Na+, K+ (difference in the sum of cations and anions), NH 4 , Ca2+, Fe+, Fe3+ are determined. Complete analysis – in addition to the reduced analysis, H2S, СО2 aggressive and permanganate oxidability are determined, Na+ and К+ ions are determined separately. Special analysis – in addition to the complete analysis, trace elements and contaminants such as phenols are identified.

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2 METHODS OF CHEMICAL ANALYSIS OF NATURAL WATERS The problems, related to working out of actions for rational use and protection of objects of the environment, are solved on the wide and reliable experimental basis – techniques of chemical analysis of water, which are developed in the direction of higher specificity, sensitivity and accuracy. Hydrochemistry chemists are increasingly focusing on the automation of methods, their unification, standardization and rapidity. When analyzing natural waters, the following methods are most often used: photometric, titrimetric, spectrophotometric, electrochemical, turbodimetric, gravimetric, mercuric, argentometric, flame photometric methods, potentiometric titration methods and thin layer chromatography with IR and UV endings. In addition, gas chromatographic and atomic absorption methods are also used. The share of instrumental methods of natural water analysis increases. The special literature on hydrochemistry provides information on the methods used to determine the components of the chemical composition of natural waters, as well as information on devices and laboratory scales, including model (metrological) and special purpose scales.

2.1 Metrological assessment of measurement methods Analysis of the chemical composition of water is one of the methods of measurement and is inevitably accompanied by errors. Errors, that distort the true value of the measured value, can occur even with a careful design and use of the most advanced instruments. Therefore, any type of water analysis raises the question of the quality of the method, as well as the value of the permissible errors. 9

In accordance with the general theory of errors, its annex to the analysis of the substance and the recommendations of the International Union of Pure and Applied Chemistry (IUPAC) on the presentation of results of chemical analysis, their quality is characterized by the accuracy, reproducibility and sensitivity of the method of analysis. The evaluation of correctness of the analysis is the absolute (  ) and relative (δ) average systematic errors, which are found by the following formulas:

 = 1/n

n

 (x i 1

i

 μ) ,

where: μ is the true concentration; хi is the result of determination; n is the number of determinations (i = 1, 2, ..., n) or through the average value of determinations Δ =   x – µ, where: х = 1/n

n

 x I ; δ  (x  μ)/μ 100  Δ/μ 100

w

i 1

Random errors characterizing the reproducibility of the analysis are caused by many uncontrollable factors, such as changes in temperature, illumination, attention, mood of the analyst during the analysis, fluctuations in the readings of the device, etc. Random errors with the same probability accept positive and negative values, and their average value tends to zero with an infinite increase in the number of measurements. Random errors cannot be avoided or eliminated completely, but if the analysis is carefully carried out, random error fluctuations within rather narrow limits are achieved. An assessment of the reproducibility of the analysis method is the mean square error (S) and the relative standard deviation (U), which are determined by formulas: n

S=

1/n  1 (x i  x) 2 , U = S / x ∙ 100 ,  i 1

10

where: хi is the result of determination;    x is the arithmetic mean of n determinations; n is the number of determinations (it is desirable that n is greater than 18); i = 1, 2, ..., n. The sensitivity of the method can be assessed either by the results of a blank sample

x 0  x 0  t q S0 , where: x 0 is the sensitivity of the method of analysis;    x 0 is the average value in the series of blank definitions;

S0 is the average square deviation from the results of blank definitions; t q is the value of the Student's criterion (can be assumed to be equal to 3.0) or as a threshold of the minimum, reliably detectable quantities of one or another component. Usually, when developing a method of analysis, its characteristics are evaluated by these indicators. The recommended method specifies reproducibility (mean square error S or standard deviation U) with the concentration interval and the number of determinations on which it is based, and sensitivity. There should be no systematic error, i.e. the method should be correct. When performing chemical analysis of water in practical laboratories in order to improve its quality, it is necessary to carry out systematic control, which provides for external and internal laboratory (internal) control. External control is carried out periodically by sending control samples to the laboratory. Analysis of control samples allows us to determine the errors made both in individual chemical laboratories and in the entire observation system (interlaboratory error). The internal control is carried out systematically in the laboratory and the methodology is as follows. In order to assess the reproducibility of the method, 18-20 of the samples examined in the laboratory are analyzed again during the year. These samples are not taken specifically, but are taken from the 11

remains of the samples analyzed. The analyst should not know which sample it is to exclude the effect of the previously obtained result. For the same purpose, it is desirable that the analyst report the immediate result of the measurement before calculating the concentration of the substance to be measured. Samples for reanalysis should be distributed as uniformly as possible throughout the year (i.e. 1 to 2 per month). Samples can be taken from the same or different water bodies. It is essential that the concentration of the substance to be determined is higher than the sensitivity of the method and for all samples is of the same order, i.e. it does not differ tens and hundreds of times. The samples analyzed twice form the so-called "control pairs". On the basis of the results of the analysis of control pairs obtained during the year, the reproducibility of the determination of each ingredient is assessed using the following formulas S/ =

1  (x 1i  x 2i ) 2 2(N  1) i

or U / = 100

x  x 2i 2 2 ( 1i ) ,  N 1 x 1i  x 2i

where: S / is the mean square error of determinations; U / is the relative standard deviation of determinations; N is the number of pairs of control determinations; x1i , x 2i are the results of the first and second control determinations. The calculated mean square error S / or relative standard deviateon U / is compared to the values S or U, respectively, given in the recommended method. Determine Fisher's criterion F = S / 2/S2 (or U / 2/U2) and, if F  2, the reproducibility of the determinations of the ingredient is considered unsatisfactory and the random error is very big. 12

If the difference between the repeated determinations (in the control pair) Δ i  x1i  x 2i is greater than 4S (or 4U), the control pair should be considered a gross error and excluded from the calculation. If the gross errors are more than 1/3 of the number of determinations, all analyses for the year should be rejected. The correctness of determination is controlled by analyzing the reference samples (distilled water + known additive of the ingredient to be determined). The reference samples are prepared and distributed to the analyst periodically at least 3 times a year in a series of 6 parallel determinations. It is expedient to carry out the analysis of standards also after the next preparation of fresh reagents, construction of calibration schedules, repair of devices, etc. After each series (6 parallel determinations), is calculated the ' average systematic error Δ syst or relative systematic error  / ' Δ syst

1 x i  μ , δ `syst  Δ syst  100 ,  μ n

where: µ is the true content of the ingredient in the reference sample, хi is the result of a single determination of the reference sample, n – the number of determinations. ' ` If Δ syst  S or δsyst  U, respectively, the correctness of the method should be considered unsatisfactory and measures should be taken to reduce the systematic error. Random RMS (root-mean-square) error // S 

1  (x i  x ) 2 , n 1

is calculated from a series of six determinations, or the standard deviation of

S // // U  100 S and U // x //

should also be satisfactory. 13

At the end of the year, the correctness of the analysis can be determined by the results of all the series using the formulas above. To record the results of internal control, a special logbook should be kept; a sample log entry is provided in Table 1. Table 1 Sample record in the Journal of Internal Laboratory Water Quality Control. Ingredient name A. Reproducibility S or U № Date n/a of the first analysis U

Date of the second analysis /

Analysis results х1 F=U

х1 – х2 х1 + х2 x 1  x 2 x1  x 2

 x1  x 2     x1  x 2 

2

Note

х2 /2 /



U2

Correctness № n/a

Date of Analyses

The result of the analysis хi

True meaning

хi – µ

хi - x

(хi - x )2

Note









Guaranteed indicators of accuracy of measurements established at metrological estimation of measurements performance methods (MPM) taking into account all possible measurements of influencing factors of sample and MPM, characterize the accuracy of any of the results of measurements, which can be obtained on the given MPM at its strict observance. The accuracy of measurements made according to MPM in accordance with GOST 8.505.84 shall be expressed by one of the following methods: the limit δ (  ) corresponding to the accepted probability of P, possible values of the measurement error module (total error) or two characteristics of the components of the total error: – reproducibility indicator – the value of the mean square deviation of the random component of the measurement error  (  0), which changes with changes in the content of the component of the same sample at the changes in the influencing factors of the MPM allowed by the method; 14

– the indicator of correctness – the limit corresponding to the accepted probability of P, possible values of the module of the systematic component of the measurement error δ (  с) the content of the component of any sample at the changes of the influencing factors of the sample allowed by the method. On the basis of the allowed accuracy indicators of measurements the accuracy norms of measurements are made on the basis of MPM. They can be established in the standards of accuracy of measurements of the main indicators of water composition (taking into account the accuracy characteristics of MPM), as well as set standards for maximum permissible concentrations (MPC) of water contaminants in water bodies and watercourses, standards of general requirements for methods of determining contaminants in natural waters and treated wastewater, and should be given in the terms of reference for the development (revision) of MPM.

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3 WORK PERFORMED IN THE FIELD    

3.1 Workflow

In the process of work performed directly at the object under study, it is necessary to follow the sequence. When taking samples from the surface of a water body or watercourse, the transparency and colour of the water is primarily determined by means of a disc and a colour scale (only for lakes and reservoirs). Then the temperature of water and air is determined. After thorough and repeated rinsing, a sample is scooped into a clean bucket, the pH value, СО2, CO 32  and О2 content are determined and fixed. The bottles are filled with water for analysis in a stationary chemical laboratory, and part of the water is preserved. If necessary, the taste and smell of the water is determined. The water is taken out again with a bucket for other analyses by means of the field laboratory (FLWA) according to the instructions. When taking samples from depth, the transparency and colour of the water (for lakes and reservoirs) are primarily determined. Then the bathometer is lowered into the water for 10 minutes and raised, then by the thermometer in the bathometer the water temperature is recorded, and simultaneously the air temperature is determined. In the water from the bathometer pH, the content of СО 2 , СО 32  , fixed O2 are determined. The bathometer is lowered to the same depth and the bottles are filled with water. Part of the water is preserved, if necessary, the taste and smell are determined. Other tests performed in the field are carried out according to the instructions of the surfactants.



3.2 Sampling of natural waters 3.2.1 General provisions

Sampling is an essential part of research that determines the quality and reliability of hydrochemical information. The problem of 16

sampling is very complex, so it is almost impossible to give detailed recommendations for all cases and in accordance with all requirements. General requirements for natural water sampling to determine its chemical composition and physical properties are set forth in GOST 17.1.5.05.85. The basic principles to be observed in sampling are as follows. Samples of water taken for analysis should be sufficiently representative, i.e. they should characterize the condition of the water in the water body or part of it for a certain period of time; the process of sampling, pre-treatment, storage and transportation of the sample should not cause significant changes in the chemical composition and properties of the water. Sampling should take into account the specifics of the water body (morphology, hydrology, etc.) and the specificity of the controlled substances (dissolved, suspended, colloidal, etc.). The volume of the sample shall be sufficient for analysis and shall be in accordance with the applicable methodology. A distinction is made between point and combined (average) samples. Point samples are obtained by taking the amount of water required for the analysis once. These samples characterize the water quality at a given point in the water body at the time of sampling. Combined samples are a series of point samples that are combined according to one principle or another. These samples characterize the average water composition over a period of time. Depending on the purpose of the study, sampling may be one-off (irregular), serial or regular. One-off sampling is used relatively infrequently to periodically identify possible changes in water composition and in a well-studied waterbody, if the identified components are not subject to large changes in time, depth and water area of the waterbody. Regular and serial sampling provides more defined and reliable information on the condition of the water body and the quality of its water. When analyzing serial samples, the content of the observed components is determined, taking into account the place and time of sampling. Sampling points shall be selected in accordance with the purposes of the analysis and on the basis of the terrain survey, except for observations for special purposes. Water samples should not be taken for chemical analysis: 17

– in areas directly affected by inflow water; – close to populated areas, if waste water is discharged into the water body; – near enterprises that pollute water with production wastes; – in areas of low water exchange, i.e. in stagnant areas (shallow water and in the sleeves near the shore). In rivers and streams, samples are usually taken at a depth of 20-50 cm from the surface and at a distance from the bottom that allows for sampling equipment. Samples can be mixed in depth or cross section on the flow rod. In seas, lakes, reservoirs, and ponds, samples are taken on a threedimensional grid at least at two levels: at the surface (0.2-0.5 m) and at the bottom (0.5 m from the bottom). At the intermediate horizons, water samples are taken depending on the existing distribution of water layers with different temperatures – higher, lower and in the layer of temperature jump. In order to compare the results of the chemical analysis of water samples, it is advisable to establish standard horizons, for example, 0.5; 2.0; 5; 10; 20; 30; 50; 100; 500 and 1000 m, taking into account thermal stratification. It is advisable to take samples of atmospheric precipitation at meteorological sites. Samplers should be installed in areas protected from dust and accidental contamination at a height of approximately 2.0 m from the ground. Depending on the purpose of the study, the volume of samples may vary from 1 to 20 litres or more. The total volume of water is determined according to the observation program, taking into account the volumes required to determine each ingredient. Water samples for the determination of ingredients with the same pre-treatment, preservation and storage conditions are grouped together. 3.2.2 Water sampling devices used for water sampling The method of taking water samples from a water body depends on the depth from which the samples are to be taken. Samples of water 18

from the surface layer are taken carefully, without shaking a vessel, usually a bottle, from the deep layers – a bathometer. Bathometer should meet the following requirements: – the water passing through it shouldn't stay in it; – the bathometer must be closed tightly to allow samples to be fixed from a certain depth; – sampler material shall be chemically inert. Rutner's and Molchanov's bathometers are the most frequently used for freshwater abstraction. In case of absence of bathometers for water sampling from the surface (0.2-0.5 m) it is possible to use Novok bucket (enameled or plastic). In order to avoid pollution of the bucket it is strictly forbidden to use it for other purposes, the bucket is necessarily rinsed with water repeatedly. To select sea and oceanic waters, specialists use metal bathometers (more often titanium ones) of the BM-48 type or plastic bathometers of a large volume of construction of the Institute of Oceanology of the Russian Federation. Recently, automatic samplers and floating self-propelled devices have become widespread. For quantitative evaluation of some ingredients (e.g., oil products, SS, etc.) in some cases it is necessary to take into account their content in the surface film. For selection of the film, most often used devices are from the plankton network or other materials. Sampling of atmospheric precipitations is carried out in special sludge collectors or with the help of a wide funnel, the tube of which reaches the bottom of the bottle. Snow can be sampled with a nonmetallic spatula directly into wide neck bottles where it lies in the thickest layer. Glass or polyethylene bottles, pre-washed with concentrated hydrochloric acid and degreased with synthetic detergents or a chromium mixture, and carefully rinsed with tap water, then distilled water and water from the water body under study, are usually used for sample storage. Tubes (rubber, cortical or polyethylene) should be prelimnarily boiled in distilled water and when filling the bottle, the tube should be rinsed with the water under investigation. There should be an air gap (2-4 cm) between the plug and the water level.

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3.2.3 Preliminary preparation and preservation of samples Since surface waters are an extremely mobile dynamic system, measures must be taken immediately after sampling to prevent changes in the true chemical composition of the water. If the sample is intended for the determination of dissolved substances, it should be filtered through a 0.45 µm pore size membrane filter immediately after sampling. Some ingredients (dissolved gases, etc.) and physical properties should be determined immediately after sampling, others (nutrient compounds, trace elements, etc.) soon after sampling. Since there is no universal method of preservation, equally suitable for all ingredients of the chemical composition of water, different preservatives are used (Table 2). Preserved water samples are transported as soon as possible in a special container that excludes the possibility of bottle breakage or deformation. Ile River (lower tailrace of the Kapshagai hydropower plant) t° of air 23 °С t° of water 20 °С 4.06.2007 Figure 1. Sample label for natural water bottle.

It is recommended to store the sample in the refrigerator at 3-5 °C before starting the analysis and take it out of the refrigerator only just before starting the work. In conclusion, a label in duplicate is made for each of the containers, where the samples are taken, on which the object of study, the place of sampling, air and water temperature, date of sampling are indicated. A sample label is shown in Figure 1. One copy of the label is glued to the bottle, the other is wrapped up with a tube, bent twice and tied to the bottle neck with a twine. 3.2.4 Sample storage First of all, it should be remembered that in all cases it is necessary to avoid long-term storage of natural water samples. Preservation or 20

fixation of samples on individual components is only used for preservation of samples without changes for the duration of delivery of samples to the laboratory (up to a maximum of three days). Samples should be stored in a specially designated place at a constant (preferably low, 3-5 °C) temperature and protected from direct sunlight. Water samples intended for analysis shall be transported to the laboratory in small batches as soon as possible and should be analyzed immediately. Hydrochemists know that over time, even canned samples lose their representativeness and their further analysis loses its meaning. In addition, it should be remembered that the temperature of the samples should be equal to еру room temperature before starting the analysis. It should be remembered that the accuracy and reliability of the analyses depends largely on the conditions of sampling, transport and storage of the samples. Therefore, all recommendations and instructtions for these operations must be firmly understood and carefully followed. 3.3 Safety precautions when working on water bodies The persons working at the post, the hydrometeorological station, the expedition vessel and the field hydrochemical laboratory shall be acquainted with the safety rules. Post, station, vessel, field laboratory shall have special premises for hydrochemical works of the first day, equipped in accordance with the requirements of safety and sanitary standards. The following should be remembered when working on a water body. It is prohibited: – allow water samples and bottom sediments to be taken by persons who do not know the rules of working on water; – keep unused equipment, devices and unnecessary items in the working area; – use chemical dishes for food storage and eating; – work without protective clothing. It's strictly necessary: – keep the workplace clean and in perfect order; 21

– store reagents and means for water sampling, bottom sediments in the set of field hydrochemical laboratory and in special boxes; – to have means of first aid and to store them in a special firstaid kit. When carrying out hydrochemical works, it is necessary to know that the most dangerous works are during the period of ice drift and unstable freezing. All posts, stations, expeditionary vessels and boats should be equipped with the necessary rescue equipment and first-aid kits. The person taking water and sediment samples should be able to swim and row on a boat or raft. In the event of a water accident, you should immediately get rid of unnecessary items and clothing, hold on to the overturned boat and sail with it to the shore. Do not sail from the overturned boat to the shore. Climb on to the approaching rescue boat only from the stern and not from the side to prevent it from tipping over. Safety rules for working in the chemical laboratory, namely: rules for handling acids, alkalis and other substances, rules for working with glassware, equipment and electrical appliances should be observed by students and once a semester a briefing on SP should be conducted by a responsible employee and the knowledge of basic rules must be checked by the teacher.

3.4 Identification of unstable components of the chemical composition of natural waters

3.4.1 Determination of the physical properties of water The chromaticity of natural waters is conditioned by the presence of iron humates (iron salts of humic acids). The water of the rivers with swampy type of feeding (mainly rivers of northern regions of Russia) has high colour index. The chromaticity is estimated in degrees of platinum-cobalt scale. According to GOST 2874-54 "Drinking water", the colour should be no more than 20о (in some cases, in coordination with the sanitary authorities color up to 35о is allowed). 22

Qualitative assessment is made by comparing it with distilled water: glasses made of colorless glass are filled with separately examined water and distilled water. On a white sheet of paper in daylight, water is viewed from the top and side. On the basis of this, the chromaticity is evaluated, i.e. the observed colour, e.g. brown, yellow, etc., is indicated. In the absence of colouring, the water is considered to be colourless. Quantitative colour is considered according to the platinum-cobalt scale. Preparation of the platinum-cobalt scale. Dissolve 1.245 g of potassium hexachloroplatinate (IV) K2[PtCI6] and 1.01 g of cobalt chloride (СоС12 ∙ 6Н2О) in 200 ml of distilled water. Add 100 ml of concentrated hydrochloric acid (p = 1.19 g/ml). Add distilled water to a volume of 1 liter. The chromaticity of this solution corresponds to 500 degrees. The working scale is prepared by adding a different amount of the main solution to the cylinders and diluting it to 100 ml with distilled water. The main solution can be kept in a dark place for 1 year, and the diluted solutions – 2-3 months. Process of determination. Pour 100 ml of test water into the cylinders. Compare its colouring with the colouring of the scale solutions on a white background when viewed from above. Smells in water may be associated with the life activity of aquatic organisms (higher aquatic plants, algae, etc.), or may appear when they die off. These are natural scents. It also happens that industrial wastewater with admixtures of a certain smell (phenols, formaldehyde, etc.) gets into the water body. These are artificial odours. At first, researchers give qualitative characteristics of the smell according to the relevant signs (swamp, earthy, rotten, fish, aromatic, etc.). The odour strength is assessed by a five-point scale (Table 3). Process of determination. Pour the water to be tested into a lapped flask (2/3 of the volume) and shake it strongly when closed. Then open and immediately note the nature and intensity of the smell. According to GOST 2874-54, the odour intensity of water at 20 °С should not exceed 2 points. Different tastes of water may be due to the presence of chemical compounds (sodium chloride, iron salts, manganese, etc.), as well as products of aquatic organisms. GOST 3354-46 defines 4 types of taste: bitter, sweet, acidic and salty. Other flavors are characterized as offflavors. Quantitative intensity of taste is determined by the same scale as the smell (Table 3). 23

Table 3 Intensity of smell and taste of natural waters Smell (taste)

Intensity

Score in points

lack

Not felt

0

very weak

Only found by an experienced researcher

1

weak

Detected by the consumer when paid attention

2

notable

Easy to detect by the consumer

3

distinct

Water is not suitable for drinking

4

very strong

Water is not suitable for drinking

5

Sanitary safe water is examined in raw form, in other cases – after boiling and subsequent cooling to 18-20 °С. It is not allowed to try the polluted water. To determine the nature and intensity of the taste 10-15 ml of water is collected in the mouth and held for 10-15 seconds, without swallowing. The intensity of taste of drinking water according to GOST 2874-54 should not exceed 2 points. Presence of roughly dispersed impurities in natural water causes its turbidity. Often the characteristic is used as an indirect indicator, while the inverse turbidity is transparency. There are 2 methods of determining water transparency: by cross and font. Determination of water transparency by font is based on finding the maximum height of the water column through which the standard font (appendix) can be read. It is defined in colorless cylinders with a diameter of 3.0-3.5 cm and a height of 60 cm with graduation through each centimeter. The standard font is placed under the cylinder and, changing the amount of water, determines the maximum height of the column (in cm) at which the standard font can be read. According to GOST 2874-54, the transparency of drinking water in accordance with the font should be at least 30 cm. 3.4.2 Determination of hydrogen ion concentration, pH value To determine the pH value of water in the field, colorimetric and electrometric methods are used. The positive quality of pH value de-

24

termination by colorimetric method is its simplicity. The disadvantages of the method include: insufficiently high accuracy of the obtained results, difficulties in determining the pH of colored and turbid water, the need for salt corrections and a significant error in the case of very low mineralization of natural water (the sum of ions less than 30 mg/l). Of all the existing colorimetric methods of determining the pH value of water the method with buffer solutions is the most reliable. Its principle is that if we add a certain amount of organic dye to the water under study, then depending on the pH value of the water the dye will take on a certain color. The obtained coloring of the examined water is compared with a scale consisting of tubes with solutions, concentration of hydrogen ions in which corresponds to certain pH values. It is obvious that if the color of the water under study coincides with the color of the solution of one of the tubes the scale of pH value will be the same. Organic multicolor dyes are the most widely used dyes that change the color of solutions in the scale tubes. Since each indicator changes its color in sharp tones only in a certain range of pH values, it is necessary to use several indicators, choosing the most convenient in terms of gradation of transition shades, and the least correction. In this respect, the following set of indicators is useful for the entire pH range relevant to natural waters: methyl red ......................... 4.4 – 6.0 bromothymol blue ............. 6.0 – 7.6 cresol red ........................... 7.6 – 8.2 thymol blue.........................8.2 – 9.0 A similar scale prepared through 0.2 pH units, allows us to determine easily by interpolation pH value with an accuracy to 0.1 units, and after getting some skills – to 0.05 pH units. The colorimetric method of pH value determination is suitable for waters of different salinity, however, at a very low concentration (up to 30 mg/l) there is a significant error due to H+ and OH  ions appearing in the test water as a result of dissociation of the indicator. Preliminary instructions. The pH value of the water is determined directly at the object immediately after taking the water sample. In the case of a stationary examination of a particular object, it is possible to 25

provide the observation point with a range of pH within which a change in pH is usually observed during the year, with a known margin in either direction. The indication of the amount of pH value to be added to the indicator should be very strictly adhered to, otherwise incorrect results will be obtained. Comparison of colours should be made in the shade or in diffuse sunlight, as the gradation of tones is less distinguishable in direct sunlight. In order to better capture the tones of the tubes, the tubes should be viewed against a white background, keeping them at a distance of 25 cm in front of each other in a slightly inclined position. Process of determination. The tube supplied with the scale, which should be made of the same glass and diameter as the scale tube, shall be rinsed 2-3 times with the water just extracted from the examined water body and filled with water up to the mark, i.e. so that the tube has the same amount of water as the solution in the scale tubes. Then, in the tube, the indicator solution is added by the pipette attached to the scale in the amount specified for each scale (0.2-0.5 ml). Close the tube with a stopper, carefully mix its contents by turning it upside down (without shaking it) and compare the color established in the water with the color of the tubes of the scale of the interval, for which the water indicator poured into the tube is designed. If the color in the tube is outside the scale range for this indicator, the definition is repeated, taking a different indicator. When changing the indicator, the pipette should be thoroughly rinsed with distilled water or (which is better) another pipette designed specifically for this indicator. If the colour of the water being tested matches the colour of one of the test tubes of the scale, the pH value of the water being tested can be considered as corresponding to the pH value indicated on the test tube. If the colour in the tube is intermediate between two scale tubes, the pH value is interpolated. The potentiometric method of determining the pH value of water with a glass electrode is more versatile and precise. pH-meters make it possible to take measurements with an accuracy of 0.01-0.05 units. The method is based on the measurement of the potential difference between the outer surface of the glass membrane of the electrode and the studied solution, on the one hand, and the inner surface of the membrane and the standard acid solution, on the other hand. Since the 26

internal standard glass electrode solution has a constant activity of hydrogen ions, the potential on the inner surface of the membrane does not change and the measured potential difference is determined by the potential arising on the boundary between the outer surface of the electrode and the studied solution. Measurements are made relative to the potential of another comparison electrode. As the latter, an electrode whose potential is virtually independent of the activity of hydrogen ions, such as calomel or silver chloride is chosen. Preliminary instructions. Measurements of the pH value are made directly at the facility shortly after the sample is taken. Process of determination. Specific recommendations on how to prepare a pH-meter for operation are set out in the instructions for the instrument. Check and install the so-called "mechanical zero" of the device before switching it on. The pH-meter is switched on and after heating up and setting "electric zero" it is checked and corrected by two or three buffer solutions. For this purpose, glass, silver chloride electrodes and a thermometer with a scale value of 0.10-0.05 °С are immersed in a cup with a buffer solution. The pH measurement is started by making sure that there are no air bubbles on the surface of the glass electrode ball. Having measured the pH value of the buffer solution, its value is recorded and after 2-3 minutes its measurement is repeated. If both pH values are the same, the electrode potential is considered to be stable and the scale correction is started according to the instructions to the device. Then similar operations are carried out with the second and third buffer solutions, after rinsing the electrodes and thermometer 2-3 times with distilled water and removing drops by pure filter paper. After checking and correcting the scale of the device, the glasses, electrodes and thermometer are thoroughly rinsed with distilled water and then examined. The natural water is poured into the glass and the pH value is measured in the same way as in the case of buffer solutions. The measurements are repeated 2-3 times or more at intervals of 2-3 minutes. The last 2 readings of the device should be the same. Reagents: 1. Potassium biftalate solution, 0.05 M. 1.612 g of recrystallized potassium biftalate dried at 110-120 °С is dissolved in a 1 liter measuring flask and the volume of the solution is brought to the mark. The pH value of this solution at 20 °C is 4.00. 27

2. Phosphate buffer solution. 3.40 g of twice recrystallized from water and dried at 110-120 °C KH2PO4 and 4.45 g. NaH2PO4 ∙ 2H2O recrystallized from water and dried over CaC12, are dissolved in distilled water in a 1 liter measuring flask and the volume of the solution is brought to the mark. The pH value of this solution at 20 °C is 6.88. 3. Sodium tetraborate solution, 0.01M. 3.81 g of recrystallized from water and dried over sodium bromide of Na2B4O7 ∙ 10H2O is dissolved in distilled water in a 1 liter measuring flask and the volume of the solution is brought to the mark. The pH value of this solution at 20 °C is 9.22. 3.4.3 Determination of dissolved gases 3.4.3.1 Determination of oxygen The method is based on the ability of manganese hydroxide to oxidize in an alkaline medium into a compound of higher valence, quantitatively binding the oxygen dissolved in water, and to transform in an acidic medium again into divalent compounds, oxidizing the equivalent (to bound oxygen) amount of iodine. The iodine released is determined by titration with thiosulphate. Process of determination. The water, which has just been extracted from the reservoir, is thoroughly rinsed three times with a lapped cap with a known volume. Then immerse the glass tip of the rubber syphon tube in the vial to the bottom so that the water overflowed over the edge. Immediately after that (without covering the vial with a plug), a pipette of 1 ml of manganese chloride solution is injected into the vial, and then 1 ml of alkaline potassium iodide solution is gently poured into it. The pipette should be immersed first to half of the vial, then, as it is poured out, lift it upwards. After the introduction of reagents, close the vial cap, making sure that there are no air bubbles left in the vial, and its contents are thoroughly mixed by repeated sharp turning upside down. In this state, the vial is left to stand until it is convenient for titration (should not be left for more than 24 hours). Before titration, 5 ml of HCl solution (2:1) should be added. Pouring out of the transparent liquid is not important for the determination. The content is mixed well. Manganite residue deposited in an alkaline environment dissolves, oxidizes iodides, and the liquid is colored yellow from the released iodine. After that, the content of the vial is poured 28

into a flask of 250-500 ml and titrated with 0.02 N sodium thiosulphate solution. Titration is carried out by continuous mixing until the liquid color changes to slightly yellow, after which about 1 ml of freshly prepared starch solution is added, and continues to be titrated by drops until the blue color disappears. The coloring should disappear from one last drop of sodium thiosulphate solution. Calculation. The content of oxygen dissolved in water is calculated by the formula: С = (8 ∙ V1 ∙ C1 ∙ 1000) / (V – 2) , where: C is oxygen content, mg/l; C1 is molar concentration of sodium thiosulphate equivalent, mol/l equivalent; V1 is volume of Na2S2O3 solution used for titration of the sample, ml; V is volume of the vial, ml; 2 is volume of water spilled out of the vial with addition of 2 ml of reagents. Reagents: 1. Alkaline potassium iodide solution (KI + NaOH). First of all, it is necessary to check the initial reagents for the content of oxidizing agents. To test the preparation KI for its purity, weigh 1 g of dry salt, dissolve in a conical flask 50 ml of distilled water, which should be preliminarily boiled and cooled. If the KI preparation is sufficiently clean, no blue coloring should appear in the solution for 5 minutes. In case of appearance of coloring of the preparation, KI is cleaned. The cleaning method is given in /1/. If the initial reagents KI and NaOH do not require cleaning, then dissolving 75 g of potassium iodide in 50 ml of distilled water, mix it with a solution consisting of 250 g of NaOH and 150-200 ml of distilled water, after which the total volume is brought up to 500 ml. In the absence of NaOH it is possible to use KOH (350 g), and instead of KI it is possible to use NaI (68 g). 2. Manganese chloride solution. 210 g of dry MnCl2 ∙ 4H2O is dissolved in distilled water and brought to 500 ml. If the solution is turbid, it should be filtered. Manganese sulfate (MnSO4 ∙ 4H2O) can also be used in the amount of 240 g or (MnSO4 ∙ 2H2O) in the amount of 200 g. 29

The prepared MnCl2 solution is checked for purity as follows. Add 1 ml of manganese chloride solution, 0.2 g of dry potassium iodide, 5 ml of hydrochloric acid solution and 1 ml of starch solution to 100 ml of distilled water. Absence of blue coloring after 10 minutes indicates purity of the reagent. Otherwise, for every 100 ml of MnCl2 solution, about 0.5-1.0 g of dry sodium carbonate is added and the solution is left for 24 hours, after which the precipitate is filtered out. 3. Sodium thiosulfate solution, 0.02 mol/l eq. 5 g of Na2S2O3 ∙ 52H2O is dissolved in 1 liter of boiled distilled water. For better preservation, 10 ml of amyl alcohol or 2 ml of xylene or chloroform should be added to the solution. The solution is stored in a dark vial connected to the burette by means of a siphon. The prepared solution should be used for work not earlier than after 10 days, as at first it changes its titre. Under these storage conditions, the solution is suitable for one year if there is no noticeable residue. 4. Potassium bichromate solution, 0.02 mol/l eq. K2Cr2O7 has solubility 50.5% at 100 °C, and at 20 °C – about 11%. Salt is dried to a constant weight in a drying closet at 180-200 °C. The resulting product is stored in a desiccator in a bucket. To prepare the solution, weigh 0.9806 g. of salt dissolved in boiled distilled water in a measuring flask of 1 liter and then bring to the mark. This solution is exactly 0.02 mol/l eq. and is used to install and check the concentration of sodium thiosulphate solution. If the subsample of K2Cr2O7 is not 0.9806 g, but a different one (a), and if it is dissolved in V ml rather than in 1 liter, the concentration of the resulting solution is calculated by the formula: C = (a ∙ 1000) / (49.032 ∙ V) 5. Hydrochloric acid solution, HCl (2:1). Mix 2 volumes of concentrated acid (ρ = 1.19 g/ml) and 1 volume of distilled water. This solution should be checked for free chlorine. For this purpose, 50 ml of distilled water, 1 ml of starch solution, 1 g of dry tested for purity KI or 10 ml of purified 10% potassium iodide solution and 10 ml of tested HCI solution (2:1) are added to the flask. Lack of coloring after 10 minutes or very little blue indicates purity of acid. Muriatic acid free of impurities can also be obtained by distillation of concentrated HCl, with the first fraction being discarded. Instead of HCl solution (2:1), sulphuric acid solution (1:4) can be used. 30

6. 0.5% starch solution. About 0.1 g of rice or wheat starch was stirred in the cold with 20 ml of distilled water and heated in a test tube to boil. Good starch should give a sharp transition of color from blue to colorless without intermediate violet tones when titrating with sodium thiosulphate. This starch solution is only suitable for about 24 hours. 7. Potassium iodide, KI. It is used in dry form to determine the concentration of sodium thiosulphate solution. KI should be stored in a dark vial wrapped in black paper (or in a dark place). It is necessary to check KI for impurities and, if necessary, clean it in the above way. In case of using the purified solution of KI in all cases instead of 1 g of dry KI take 10 ml of 10 % solution of KI, which is prepared and cleaned as needed in small quantities. Determination of molar concentration of sodium thiosulphate equivalent. 35 ml of distilled water is added to a 200 ml conical flask with a beaker, 1 g of dry KI is poured, 15 ml of potassium bichromate solution and 10 ml of HC1 solution (2:1) are precisely measured with a pipette. Titrate with Na2S2O3 solution immediately after dissolution of KI, and titrate with continuous mixing of the liquid. At the onset of weak yellow (lemon) coloring, 1 ml of starch solution is added to the flask, 100 ml of distilled water and titration is continued until the transition from blue to slightly greenish (color Cr3+). The process is repeated and, if the difference does not exceed 0.05 ml, the arithmetic mean value is taken as the final result. The sodium thiosulphate solution concentration is calculated by the ratio: N1 / N2 = a / n, wherefrom N1 = N2 ∙ a / n, where: N1 is molar concentration of Na2S2O3 solution equivalent; N2 is molar concentration of K2Cr2O7 solution equivalent; a is volume of sodium thiosulphate solution that was titrated, ml; n is volume of potassium bichromate solution taken for determination of normality, ml. 3.4.3.2 Determination of carbon dioxide The volumetric analysis method is based on the fact that the alkalis added to the water, reacting with carbon dioxide, convert it into

31

НСО 3 ions. The resulting increase in pH value is recorded by the indicator phenolphthalein (the solution is titrated to a weak pink color). Process of determination. A 200 ml measuring flask and cap are rinsed with water just taken from the water body, then the glass tip of the rubber tube is lowered to the bottom of the flask, filled with water to the marker, and no air bubbles are allowed (syphon principle). Next, 2 ml of phenolphthalein solution is added to the flask, covered with a rubber plug, and the contents of the flask are carefully mixed by carefully tilting the flask. If the water in the flask takes on a pink color, more intense than the mineral standard, then CO2 is not present and the content of carbonate ions is determined in the water. If the water remains colorless, CO2 should be determined. For this purpose, titrate with Na2CO3 solution (0.02 or 0.05 mol/l eq.) until the disappearing first color will not become stable and the liquid will take a little pink hue for 5 minutes. The color intensity at which the titration is to be considered complete is determined by comparing it with a standard solution of a certain color, poured into the same flask of 200 ml. The determination is considered complete when the same coloring as the standard is not changed within 5 minutes. Calculation. Molar mass of Na2CO3 equivalent corresponds to 44 mg/mol of CO2. Converted to 1 liter of water, we have in mg/l CO2: С=

44  N  n  1000 , V

where: N is molar concentration of soda equivalent; n is volume of soda solution used for titration, ml; V is volume of sample taken for determination, ml. Reagents: 1. Soda solution, 0.02 mol/l ekv. It is prepared from the chemically pure substance dried at 270 °С. A subsample of 0.424 g Na2SO3 is dissolved in distilled water in a measuring flask for 200 ml. It is desirable to boil and cool the water beforehand. If the weight of the subsample is not 0.424 g, but "b" and it is dissolved in a V ml vessel, the molar concentration of the equivalent is calculated by the formula: 32

N

b  1000  , 106  V 

where: 106 is the molar mass of soda. 2. 0.1% solution of phenolphthalein is prepared by dissolution of 0.100 g of phenolphthalein in 100 ml of 60% ethyl alcohol. 3. Mineral standard solution. To obtain the solution weigh 2.000 g of COC12 ∙ 6H2O and 2.000 g of CuSO4 ∙ 5H2O, dissolve in distilled water, add 1 ml of concentrated hydrochloric acid and bring the volume to 200 ml. This is a replacement standard solution. It is used to prepare a working standard solution by diluting it 10 times. 4. Segmental salt solution (КNaС4Н4О6) is prepared by dissolving 50 g of salt in 100 ml of distilled water. 3.4.3.3 Determination of aggressive carbon dioxide

Aggressive carbon dioxide is able to dissolve СаСО3. Determination of aggressive CO2 is based on the shaking of the test water with the powder CaCO3 and determination of its amount, which has been transferred to the solution. The content of hydrocarbonate ions is determined in a separate sample of the water under study. Process of determination. The bottle with a capacity of 0.25 litres is filled with water from the top of the siphon so that a certain amount of water is poured out. The tube is removed and the bottle is filled with about 1.5 g of synthesized CaCO3 powder. The bottle is plugged and shaken for 6 hours to keep the calcium carbonate particles suspended. At the end of this period, the water is filtered out, 100 ml of filtrate is taken out and the concentration of hydrocarbonate ions is determined. Calculation. The content of aggressive CO2 in mg/l is calculated by the formula:

C

V2  V1   N  E  1000 , V3

33

where: V1 is the volume of HCl solution used for control determination of НСО 3 ions (before contact of water with calcium carbonate), ml; V2 is the volume of HCl solution used for water titration after contact with calcium carbonate, ml; V3 is the volume of water for titration, ml; N is molar concentration of hydrochloric acid equivalent; E is equivalent of aggressive CO2 equal to 29. Reagents: 1. Synthesized powder СаСО3. 2. Hydrochloric acid, 0.05 mol/l eq. (prepared from fixanal). 3. Methylorange, 0.1%. 3.5 Field hydrochemical laboratories (FLWA, RLWA, LPW, HL)

FLWA is a field laboratory for general water analysis. The laboratory is designed to determine the physical properties and chemical composition of natural waters in the field under hydrological, hydrochemical, hydrogeological and other works. The laboratory consists of two wooden cases: the main size is 44x15x30 cm and the spare size is 30x20x32 cm, containing a set of reagents and laboratory equipment (Figure 2). The main reagent case weighs about 10 kg, the spare case weighs 25 kg.

Figure 2. Field Hydrochemical Laboratory for General Water Analysis (FLWA)

34

Figure 3. Water Route Laboratory (RLWA) 1 – field turbometer; 2 – flip-up lid for turbometer and tubes storage; 3 – removable box for pipettes and other equipment; 4 – stand for droppers and tubes.

Figure 4. Field laboratory for the determination of specific petroleum water (LPW) components

The reagents in the main case allow 40 to 50 analyses to be performed. The number of reagents contained in the spare case is designned for 250 tests. With the help of this laboratory it is possible to carry out the analyses accurately enough, allowing us to classify natural waters, to stu-

35

dy dynamics of their salt composition and to give them technical, household and sanitary estimation. In addition to determining the physical properties of water, the laboratory allows for chemical analysis of the components listed in Table 4. Table 4 List of definitions and methods of analysis in the laboratory FLWA Component Hydrogen ion concentration Free carbon dioxide Aggressive carbon dioxide

Ammonium ion (NH4 )

Method of determination Colorimetric with universal indicator Volumetric, 0.1N NaOH titration Volumetric, determination of alkalinity before and after interaction with СаСО3 Colorimetric Colorimetric Colorimetric with КСNS solution Colorimetric with КСNS solution Colorimetric with Nessler's reagent

Nitrite – ion (NО 2 )

Colorimetric with Griss's reagent

Nitrate ion (NО 3 )

Colorimetric, based on the reduction of NО3- to NН4+ Volumetric, titrated 0.1N HCl with phenolphthalein Volumetric, 0.1n HCl titration with methyl orange Volumetric, trilometric Volumetric, trilometric Volumetric, trilometric and computation Turbidimetric and volumetric trilometric

Oxygen Hydrogen sulfide Iron (П) Iron (Ш)

Carbonate – ion (CO 32  ) Hydrocarbonate – Ion (HCO 3 ) Calcium ion (Са2+) Magnesium ion (Мg2+) Total hardness Sulfate ion (SO24 ) Chloride – ion (С1-) Sodium ion (Na+) Amount of minerals

Volumetric Argentometric with potassium chromate indicator Calculation Calculation

RLWA is a water analysis route laboratory. This laboratory is designed to determine the physical properties and chemical composition

36

of water (at least 17 components) during survey and prospecting hydrogeological works (Figure 3). LPW is a field laboratory for determination of specific components of oil waters, namely, bromine, iodine, boric acid and naphthenic acids (Figure 4). HL-2 is a field laboratory for hydrochemical prospecting of ore deposits, designed for a wide range of works in hydrogeochemical prospecting of sulfide ore deposits. The laboratory allows us to perform up to 10 analyses simultaneously and contains the necessary equipment both for sampling and analysis. This laboratory is very convenient for walking routes and on bases of geological field parties.



3.6 Determination of nutrient compounds using FLWA and RLWA Determination of iron ions (П) Pour the test water into a tube up to 5 ml, add a full blade of potassium hydrosulfate and a tablet of red blood salt (К3[Fe(CN)6]) or 0.1 g of powdered red blood salt/sugar mixture. The solution in the tube is shaken, inserted into the comparator and colorimetrated, looking at the content of the tube from the side. The colorimetric scale is made for the following values: 0 2 4 6 8 10 Fe2+, mg/l Mmole/l eqv. 0 0.07 0.14 0.21 0.28 0.36 If the amount of Fe2+ is less than 2 mg/l, a few pellets of sodium or potassium persulfate are added the new water sample and to the method described for the determination of Fe3+ ions is used. The data for the total amount of iron id obtained. To find the Fe2+ ion content, the Fe3+ ion content is calculated from the results of the determination. Determination of iron ions (III) The examined water is poured into a tube up to 5 ml, a full blade of potassium hydrosulfate and 0.5 ml of 10% potassium rhodanide solution are added. The solution in the tube is shaken, inserted into the comparator and after 3 minutes colorimetrized, studying the contents of the tube from above. The colorimetric scale is made for the following values: Fe3+, mg/l 0.3 0.5 0.8 1.0 1.5 2.0 37

If the coloring of the liquid is more intense than the brightest standard, the solution is colorimetrated by looking at the contents of the tube from the side. In such cases, the result is tripled. Determination of nitrite ions The test water is poured into a tube up to 5 ml, a tablet (in the absence of a tablet a small glass powder spatula) of the Griss reagent is added. The solution is shaken until the crystals are dissolved and after 15 – 20 minutes it is colorimetrated, looking at the contents of the tube from above. The colorimetric scale is made for the following values: 0.01 0.02 0.05 0.10 0.20 0.50 NО2-, mg/l If the coloring of the liquid is more intense than the brightest standard, the solution is colorimetrated by looking at the contents of the tube from the side. In such cases, the result is tripled. If, when viewed from the side, the coloring is brighter than the brightest standard, the determination is repeated for a new sample previously diluted with several times distilled water. The result is multiplied by the number of dilutions. Determination of ion nitrate content The determination is based on the reduction of nitrate ions to ammonium ions in the alkaline solution with the help of Devarda alloy and on the colorimetric determination of the latter with the Nessler reagent. The determination of nitrate ions is necessarily preceded by the determination of ammonium ions in water and reagents used. From the obtained result of the determination, which is the total concentration of NН 4 obtained after reduction of NO 3 and the amount of

NН 4 contained in water, subtract the amount of the latter. 20 ml of water is measured in a 25 ml tube, 1 ml of 25% NaOH solution is added, and one measure of Devarda alloy (about 0.1 g). The tube is covered with filter paper and left for at least 10 hours and no more than overnight. Simultaneously, the blank determination is performed. For this purpose, in a 25-ml tube 20 ml of ammonium-free distilled water is added, 1 ml of 25% NaOH solution and one measure of Devarda alloy (about 0.1 g), the solution is mixed and left for the same period. Then select with a pipette, carefully, without agitation, the sediment, 5 ml of the reduced solutions, transfer them to tubes for 38

colorimetry, add 3 drops of Nessler's reagent, shake the solutions and after 3 minutes colorimeterize in the comparator, looking at the content from above. If coloring of the liquid is more intense than the brightest standard, the solution is colorimetrated by looking at the contents of the tube from the side. In such cases, the result is tripled. If, when viewed from the side, the color is brighter than the brightest standard, the determination is repeated. For this purpose, 1 ml of the reduced solution is taken, transferred to a 5 ml tube, ammonium-free distilled water is added to the mark (i.e., the water under test is diluted 5 times), 3 drops of Nessler's reagent are added and the color is determined as described above. If the coloring of the liquid is even more intense than the brightest standard, 1 ml of the original reduced solution is taken for determination, transferred to a 10 ml tube and ammonium-free distilled water is added to the mark. The solution is stirred and 1 or 2 ml are taken out, transferred to a 5 ml tube, diluted with ammonium-free distilled water to the mark, i.e., the test water is diluted 50 or 25 times, 3 drops of Nessler reagent are added and its color is determined as described above. Calculation of results: (а – (b1 + b) . 3.44 = c mg/l NО 3 , 

where: a is the content of NН 4 after reduction in the studied water;  b1 is the concentration of NН 4 found in the water;  b is the content of NН 4 found in the blank sample; 

3.44 is the conversion factor from NН 4 to NО 3 . In the case when the determination is made in diluted water, the calculation of the content of nitrate ions is made by multiplying "c" by A, where A is a number showing how many times the water was diluted.

Determination of ammonium ion content The test water is poured into a tube up to 5 ml, approximately a quarter of a glass spatula of segmental salt is poured, the contents of the tube are shaken before dissolving the crystals and 3 drops of Nessler's reagent are added. The solution is shaken up again and after 3 minutes it is colorimetrated, looking at the contents of the tube from above. 39

The colorimetric scale is made for the following values: 

NН 4 , mg/l 0.05 0.1

0.2

0.4

0.7

1.0

1.5

If the coloring of the liquid is more intense than the brightest standard, the solution is colorimetrated by looking at the contents of the tube from the side. In such cases, the result is tripled. If, even when viewed from the side, the coloring of the liquid is more intense than the brightest standard, the determination is repeated from a new sample, previously diluted several times by the distilled water.

3.7 Determination of water oxidation

Water oxidation is expressed by the number of mgs of atomic oxygen spent on oxidation of organic matter in 1 liter of water. If the concentration of chlorides in the test water is not higher than 100 mg/l, organic matter is oxidized in an acidic environment (Kubel method). In case of higher chloride content (over 300 mg/l) the oxidation reaction of KMnO4 in alkaline medium (Schultz method) is used. Determination of permanganate oxidation of water in acidic environment (Kubel method). Oxidation is carried out by a solution of potassium permanganate in a sulfuric environment during boiling:

MnO 4 + 8H+ + 5e = Mn2+ + 4H2O Process of determination. 100 ml of water is added to the conical flask (or, if the organic matter content is higher, a smaller volume with a corresponding addition of up to 100 ml of biodistilled water), glass capillaries are added, 5 ml of diluted H2SO4 (1:3) and 10 ml of KMnO4 0.05 mol/l eq solution are added. The mixture is boiled exactly 10 minutes after the first bubble appears. If the solution remains pink, 10 ml of H2C2O4 0.05 mol/l eq solution is added to it. Bleached, still hot mixture (80-90 °C) is titrated with KMnO4 solution until slightly pink color appers, which does not disappear within 2-3 minutes. If the 40

solution in the process of boiling acquires a brown color, it indicates a lack of sulfuric acid. In this case, a certain volume of KMnO4 solution of a given concentration should be added to the sample and boiled for 10 minutes. Calculation: Х =

/V1  V2   H1  V3  H2 /  8 1000 , V

where: X is water oxidation, mg/l; V is water volume, ml; V1 is KMnO4 solution volume before boiling water, ml; V2 is KMnO4 solution volume after boiling water, ml; V3 is H2C2O4 solution volume, ml; H1 is concentration of KMnO4 solution, mol/l of equivalent substance; H2 is concentration of H2C2O4 solution, mol/l of equivalent substance; 8 is oxygen equivalent. Reagents: 1. Sulphuric acid (1:3). One volume of concentrated sulphuric acid, pre-boiled (under draught) to remove organic matter and nitrates, is mixed with three volumes of bidistilled water. The density of the obtained solution should be about 1.27. 2. KMnO4 solution with concentration of C(1/Z x) = 0.05 (prepared from fixanal). 3. H2C2O4 solution of C(1/Z x) = 0.05 (prepared from fixanal). Determination of permanganate oxidation in alkaline environment Process of determination. The conical flask is filled with 100 ml of test water, 3 ml of 33% sodium hydroxide solution, 20 ml of 0.01 N (or 0.05 N) potassium permanganate solution and several capillaries. The mixture is heated so that it boils after 5 minutes and boils for exactly 10 minutes. If the mixture becomes green during boiling, the determination should be repeated with a sample diluted with bidistilled water, and in this case it is also necessary to have an excess of 41

KMnO4 when boiling. After boiling the contents of the flask are cooled down (20-30 minutes) to room temperature. Then such a volume of diluted H2SO4 is carefully brought in a flask which is necessary for neutralisation of alkalinity of water and the added alkali. To neutralize 3 ml of 33% NaOH solution it is necessary to use about 3.6 ml of diluted H2SO4. This ratio should be checked. After mixing, 0.5 g of crystalline KI and another 3 ml of diluted H2SO4 are added to the contents of the flask. The released iodine is titrated with 0.01N sodium thiosulphate solution in the presence of starch. Calculation. It is necessary to determine the ratio between potassium permanganate and sodium thiosulphate solutions. For this purpose, 0.5 g. of crystalline KI is poured into the flask and dissolved in 2 ml of distilled water. Then 3 ml of diluted H2SO4, 20 ml of KMnO4 solution and 100 ml of distilled water are added. The released iodine is titrated with 0.01 N sodium thiosulphate solution in the presence of starch. Permanganate oxidation in an alkaline medium in mg/l is determined by the formula: X

a  b   k  0.01  8  1000 , V

where: a, b is the volume of thiosulphate solution consumed in determining the ratio and titration of the sample of test water, ml; k is the correction factor of thiosulphate solution to bring it to the exact 0.01N; 8 is oxygen equivalent; V is the volume of test water, ml. Reagents: 1. Sulphuric acid (1:3). Prepared in the same way as described above. 2. Sodium hydroxide, 33% solution. 50 g of NaOH chemically pure and free of organic substances and nitrates are dissolved in 100 ml of bidistilled water. It is necessary to check (approximately) the concentration of each newly prepared solution. Preliminary cleaning of alkali from possible specified impurity is made by heating it in a silver or nickel cup at a temperature about 600 °С. 42

3. KMnO4 solution with concentration of C (1/Z x) = 0.01 or 0.05 (prepared from fixanal). 4. Sodium thiosulphate, concentration C (1/Z x) = 0.01 (prepared from fixanal). 5. Potassium iodide crystal, grade chemically pure 3.8 Determination of chemical oxygen consumption Bichromate Oxidation (COC – chemical oxygen consumption) Potassium bichromate oxidation occurs in an acidic environment (sulphuric acid must be in excess) in the presence of a silver sulphate catalyst:

Cr2O 72  + 14 H+ + 6e = 2Cr3+ + 7H2O Excess potassium bichromate added to the water sample is titrated with a solution of Maura salt. Process of determination. If the expected bichromate oxidation is 50-200 mg/l, 0.25 N solution is used for oxidation of K2Cr2O7. If the expected oxidation of the water under test is greater than 200 mg/l, it should be diluted with bidistilled water before determination. To determine take 20 ml of water and add it to the round bottom flask, add 10 ml of 0.25 N solution of K2Cr2O7, 0.4 g of silver sulfate, capillaries and stir. If the chloride content exceeds 10 mg in the taken volume of water, add HgSO4 in the amount of 0.1 g per 10 mg of chlorides. Then, gently add 30 ml of concentrated sulfuric acid to the flask, stir, put a grinded cap with a return condenser and boil the mixture uniformly for 2 hours. After cooling the condenser is removed, 100 ml of distilled water, and 5-7 drops of indicator solution are poured into the flask. The solution acquires the color of strong tea. Excess potassium bichromate is titrated with 0.25 N solution of Maura salt until the solution is colored from one drop to dark green. In the same way the blank experiment with 20 ml of distilled water is done. 43

Calculation: X

a  b   k  0.25  8 1000 , V

where: a, b are the volumes of Mora salt solution, spent on blank experiment and on titration of the test water sample, ml; k is the correction factor of Mora salt solution to bring it to exact 0.25 N; 8 is the oxygen equivalent; V is the volume of test water, ml. If 0.025 N potassium bichromate solution was used for oxidation, then in the formula 0.25 is replaced by 0.025 and the corresponding value of the coefficient "k" is used. Reagents: 1. Potassium bichromate solution. 0.25 N or 0.025 N (prepared from fixanal). If there is no fixanal, the 0.25 N solution is prepared by weighing 12.2580g K2Cr2O7 CP, pre-dried for 2 h at 105 °C and dissolved in distilled water in a measuring flask of 1 liter, the volume of which is filled to the mark. 2. H2SO4 grade ch.p. concentrated, boiled. 3. Ag2SO4 Ch.pure crystalline. 4. Solution of Maura salt, 0.25 N (prepared from fixanal). If there is no fixanal, 98 g of salt Fe(NH4)2(SO4)2 ∙ 6H2O is dissolved in distilled water. Add 20 ml of concentrated H2SO4 and after cooling add distilled water up to 1 liter. The concentration of this solution should be set for each series of definitions: 25 ml of potassium bichromate solution is diluted in a flask with distilled water up to 200 ml, 15 ml of H2SO4 solution (1:1) is added and 0.25 N is titrated with Mora salt solution in the presence of 5 drops of N-phenylanthranilic acid solution (transfer of coloring from red-violet to brown-green) or 3 drops of ferroin solution (transfer of coloring from blue-green to reddish blue). Correction (k) to the concentration of 0.25 N of Mora salt solution is determined from the ratio k = a: n, where n is the number of ml of Mora salt solution used for titration of 25 ml of 0.25 N of K2Cr2O7 solution (a). 44

5. N-phenylanthranilic acid solution: dissolve 0.25 g of reagent in 12 ml of 0.1 N NaOH solution and dilute with distilled water to 250 ml. 6. Ferroin indicator solution: dissolve 1.485 g of monohydrate 1.10-phenantroline and 0.695 g of FeSO4 ∙ 7H2O in distilled water and dilute to 100 ml.

45

4 WORKS PERFORMED IN THE LABORATORY 4.1 Determination of the main ion content 4.1.1 Determination of calcium ions

The determination is based on the formation of Са2+ ions with murexide a low-dissociated compound stable at pH = 10.0, painted in crimson color. During titration, calcium ions are bound by trilon B into an even less dissociated complex, and the murexide colors the alkaline solution into violet. Process of determination. In a conical flask pour 50 ml of water with a pipette and throw the indicator paper congo. Acidify with hydrochloric acid of concentration (1:1) until the indicator paper turns blue – violet. Boil the solution for 2-3 minutes and cool to 40-50 °C, close with a cork. After cooling, pour 2 ml of 20% alkali solution into the flask, add a small amount of murexide and immediately titrate with trilon B solution of the concentration of C (1/Z x) = 0.05 until the color changes from red to the unchanged purple color. Calculation: Х = N  n  1000 , V

where: X is the content of calcium ions, mmole/l equivalent; N is concentration of trilon solution B, C(1/Z x) = 0.05; n is the volume of trilon B consumed for titration, ml; V is the volume of water taken for analysis, ml. To calculate the content of calcium ions in mg/l the obtained value of X is multiplied by 20.04, where 20.04 is the equivalent of Ca2+ ion. 46

Reagents: 1. Trilon B solution with concentration of C (1/Z x) = 0.05 (prepared from fixanal). In case of absence of fixanal it is possible to take 9.32 g of the preparation, place it in a 1L measuring flask, dissolve in distilled water and fill the volume to the mark. Determination of the concentration of Trilon B solution is carried out using the standard solution of MgSO4 (in the kits for determining the total hardness of water there are ampoules-fixanals with samples of MgSO4 ∙ 7Н2О). Into the conical flask 100 ml of 0.01 N magnesium sulphate solution is poured with a pipette, 5 ml of ammonium buffer mixture and several crystals of dark blue chromium indicator are added to it. Titrate with trilon B solution until red color turns blue. 2. Sodium hydroxide solution, 20%. 3. Murexide. 1 g of indicator and 100 g of sodium chloride CP is grounded in a mortar. 4. Congo indicator paper. 4.1.2 Determination of magnesium ions

The method is based on the titration of magnesium ions with trilon B in the presence of black eriochrome (or black chromogen, or ET-00, or dark blue chromium) in the same solution in which Са2+ ions were bound in the complex with trilon B in the presence of murexide indicator. For titration of magnesium ions, the coloration of the solution caused by murexide must be destroyed. Process of determination. Neutralize the solution after determination of Са2+ ions with hydrochloric acid (1:1) until the Congo paper becomes blue-violet. After 10-15 minutes, when the solution becomes colorless, add 10 ml of the buffer solution, add 4 drops of black eriochrome and immediately titrate with trilon B solution concentration of C (1/Z x) = 0.05 with intensive mixing before the transition from red through purple to blue (heating up to 40-50 °C increases the clarity of color). Calculation: Х=

N  n  1000 , V 47

where: X is the content of magnesium ions, mmol/l equivalent; N is the concentration of trilon B solution, C(1/Z x) = 0.05; n is the volume of trilon B consumed for titration, ml; V is the volume of water taken for analysis, ml. To calculate the content of magnesium ions in mg/l, the resulting value of X is multiplied by 12.16, where 12.16 is the equivalent of Мg2+ ion. Reagents: 1. Trilon B solution with concentration of C(1/Z x) = 0.05 (prepared from fixanal). 2. Hydrochloric acid (1:1). 3. Buffer solution. Dissolve 20 g of NH4Cl in a small volume of distilled water, add 100 ml of NH3 (25%) and bring the volume of the solution with distilled water to a mark of 1 liter. 4. Black Eriochrome. Rubbing in the mortar of 1 g indicator and 100 g of chemical pure sodium chloride.

4.1.3 Determination of total hardness

The method is based on formation by Ca2+ and Mg2+ ions of strong intra-complex compounds with trilon B. Process of determination. A conical flask or any other 250 ml flask should be supplied with the required volume of water (so that the total content of Ca2+ and Mg2+ ions does not exceed 0.5 mmol/l equivalent). Then, if necessary, dilute with distilled water to a volume of 50 ml, add 10 ml of buffer solution, 4 drops of acid chromium indicator dark blue and the solution is titrated with trilon B, with energetic mixing before the transition of coloring through purple, violet – blue to pure blue at the equivalence point. The re-titrated solution can serve as a reference. Calculation: Х=

V1  N  1000 , V2

48

where: X is the total hardness, mol/l eq.; N is the concentration of trilon B solution, C(1/Z x) = 0.05; V1 is the volume of trilon B consumed for titration, ml; V2 is the volume of water taken for analysis, ml. Reagents: 1. Trilon B solution with concentration of C(1/Z x) = 0.05 (prepared from fixanal). 2. Buffer solution. Dissolve 20 g of NH4Cl in a small volume of distilled water, add 100 ml of NH3 (25%) and bring the volume of the solution with distilled water to the mark 1 liter. 3. Black Eriochrome. Grind 1 g of indicator and 100 g of chemically pure sodium chloride in a mortar. 4.1.4 Determination of sulphate ions

The weight determination is based on the low solubility of ВаSO4 in a weak hydrochloric acid solution. When performing the analysis it is necessary to keep in mind that the accuracy is ensured only if all the conditions of the list are met, because other substances contained in the solution can be co-settled with ВаSO4. Nevertheless, this method, although laborious, is the most accurate in comparison with the volumetric and turbidimetric methods. The accuracy of the determination is 2 mg SO 24  in 1 liter of water. Process of determination. Depending on the expected content of 2 SO 4 ions, it is precisely measured with a pipette or measuring flask from 50 to 500 ml of water in such a way that the weight of the sludge does not exceed 300 mg. At a low content of sulfate ions (less than 10 mg/l) the required volume of water is poured into a chemical glass, acidified by HCl (1:1) (on methylorange) and concentrated by evaporation in a sand or water bath to a volume of 50-70 ml. If evaporation is accompanied by precipitation, it is filtered out through a dense paper filter. For every 100 ml of water, 2 ml of HCl (1:1) is added, heated to the boiling point and 10-15 ml of hot barium chloride solution is added with constant stirring, and further work is carried out as described below. 49

The required volume of fresh water (rivers, lakes, etc.) is poured into a heat-resistant chemical glass, acidified with a few drops of HCl solution (1:1) by methylorange to a strongly acidic reaction and evaporated in a sand bath to a volume of 50-70 ml. The hot 5% ВаСl2 solution is poured in drops of 5-10 ml into the hot evaporated analyzed solution with constant mixing with a glass rod, which remains in the glass until the end of the experiment. Check the completeness of sulfate ions deposition and leave the solution with sediment on a warm tile (not less than 3 hours), and then overnight at room temperature or in the cold. The next day, the sludge is filtered out, transferred quantitatively to the filter and washed with hot distilled water until a negative reaction to Cl  ions. Filters with sediment after drying are transferred to weighted crucibles and calcined at 500-600 °C to a constant weight. Calculation: Х = 0,4115  а  1000  1000 , V where: X is the sulfate ions content, mg/l; a is the sludge mass, g; V is the volume of analyzed water, ml. To calculate the SO 24  ion content in mol/l equivalent, the obtained value of X should be divided by 48.03, where 48.03 is the equivalent of sulfate ion. Reagents: 1. Solution ВаС12, 5%. 2. Solution of АgNO3. 10 g salt is dissolved in 100 ml of distilled water and 1 ml of concentrated HNO3 is added. 3. HCl (concentrated, chemically pure). 4. Methylorange solution, 0.5%. 4.1.5 Determination of carbonate and hydrocarbonate ions using direct and backward titration

Direct titration method. When titrating water containing СО 32  ions with hydrochloric acid with phenolphthalein indicator (before 50

discoloration), СО 32  ions are converted into HCO 3 : СО 32  + Н+ = = HCO3 , i.e. half of carbonate ions are titrated. Further titration with acid with methyl orange results in complete decomposition of HCO 3 ions formed during the first titration and contained in water:

HCO3 + Н+ = Н2О + СО2 . Process of determination. In the conical flask measure with a pipette 50-100 ml of the analyzed water, add 5 drops of 1% solution of phenolphthalein and in the case of pink coloring titrate with the solution of HCl of known concentration, carefully, by drops until discoloration. Write down the consumed volume of the acid. Further, 3 drops of 0.1% of methylorange solution are added to the same solution and titrated with the same hydrochloric acid solution until the yellow color of the liquid changes to low pink (or peach) one. Calculation:

V  V   N  1000 , Х1 = 2V1  N  1000 , Х2 = 2 1 V V where: X1 is the content of СО 32  ions, mol/l equivalent; X2 is the content of HCO 3 ions, mol/l equivalent; V1 is the volume of НСl solution of concentration N consumed for titration of V ml of water with phenolphthalein, ml; V2 НСl volume of HCl solution of N concentration consumed for titration of V ml of water with methylorange, ml; V НСl volume of analyzed water, ml; N НСl concentration of hydrochloric acid, mmole/l equivalent. To calculate the content of СО 32  ions in mg/l, the value of X1 should be multiplied by 30.0, and the value of НСО 3 ions – by 61.02, where 61.02 and 30.0, respectively, are the equivalents of НСО 3 and СО 32  ions. 51

Reagents: 1. HC1, 0.1 or 0.05 mmol/l equivalent (prepared from fixation). 2. Alcohol solution of phenolphthalein, 1%. 3. Methylorange solution, 0.1%. The reverse titration method allows determining the total content of carbonate and hydrocarbonate ions. Process on determination. In a 200 ml conical flask, 100 ml of the analyzed water is measured with a pipette, 5-7 drops of Groag indicator solution are added and the volume of 0.05 HCl from the burette is added to make the liquid red. After adding 1-2 ml of HCl solution, the flask is placed on an electric tile and boiled for exactly 10 minutes. Cool down to 50-70 °C and titrate the excess of hydrochloric acid with the solution of borax, mixing the contents of the flask, until the transition of the solution color from bright pink to pinkish-yellow (yellowish-greenish color appears in the titrated solution). Calculation:

Х=

H1  V1  H 2  V2   1000 , V

where: X is the content of HCO3 + СО 32  , mmol/l eq.; H1 is the HCl solution of C (1/Z x) = 0.05; V1 is the volume of HCl solution used for titration, ml; H2 is the solution of C (1/Z x) = 0.05; V2 is the volume of the solution of C (1/Z x) solution used for titration, ml; V is the volume of analyzed water. If there were СО 32  ions in the water and their content was determined, the content of carbonate ions must be subtracted from the obtained value in order to calculate the HCO3 concentration. To find the content of HCO3 ions in mg/l, the value in mol/l equivalent should be multiplied by the equivalent of this ion, equal to 61.02, and carbonate ion, respectively, 30.0.

52

Reagents: 1. HCl, 0.05 mmol/l equivalent (prepared from fixanal). 2. Borate solution, 0.05 mmol/l equivalent. For this purpose, 4.7672 g of Na2B4O7 is weighed after dissolution of the suspension in distilled water in a 0.5 liter measuring flask, and the volume is brought to the mark. The solution is kept in a vial with a lapped cap and for protection against evaporation the cap is filled with paraffin. Determination of borate solution concentration. In the titrated sample, the solution in which has a neutral reaction to the indicator Groag, measure 5 ml of the working solution of borate from the burette and with continuous blowing of СО2 free air, titrate it with 0.05 N solution of HCl until the transition of color from green to raspberry. The determination is carried out with parallel samples. Calculation of the results: Н2 = (Н1 ∙ v)/c, where: H2 is the concentration of borate solution, mol/l eq.; H1 is the concentration of HCl solution, mol/l eq.; v is the volume of HCl solution, ml; c is the volume of borate solution, ml. 3. Solution of Groag indicator. A weight of 0.5 g. of methylroth was rubbed in an agate mortar with 7-10 ml of ethyl alcohol, then the indicator solution was washed in several portions of alcohol into a 100 ml measuring flask and the volume was brought to the mark. The resulting solution is then transferred into a dark glass bottle and 4 ml of 1% aqueous methylenblau solution is added to it. The color transition point of this indicator шы at pH = 5.0. In acidic environment, the color is raspberry, and in neutral and alkaline – green. 4.1.6 Determination of chloride ions

The determination is based on the titration of chloride ions with AgNO3 solution in the presence of potassium chromate indicator K2CrO4. The first drop of excess silver nitrate solution forms with potassium chromate silver chromate precipitate, staining the solution in brown color. Proсess of determination. To 50 ml or less volume of test water, brought by distilled water to 50 ml, add 0.5 ml of 10% potassium chromate solution and titrate with silver nitrate solution by droplets at constant mixing until the appearance of non-extinct light brown liquid 53

color from one drop. The titrated solution is poured into a separate vial and handed over to the laboratory assistant for work on the extraction of silver ions. Calculation: Х=

V1  N 1000 , V

where: X is the content of Сl  ions, mol/l equivalent; V1 is the volume of solution АgNO3, ml; N is the concentration of solution of silver nitrate, mol/l equivalent substance; V is the volume of tested water, ml. To calculate the content of chloride ions in mg/l, X value should be multiplied by 35.46, where 35.46 is the equivalent of Сl  ion. Reagents: 1. Silver nitrate solution, 0.02 or 0.05 mmol/l equivalent. The water solution of silver nitrate in the light is unstable. Therefore, it should be stored in a dark glass jar, periodically checking the concentration of the solution in a standard sodium chloride solution. 2. Potassium chromate solution, 10%. 4.1.7 Determination of the amount of sodium and potassium

The total concentration of alkaline metals, sodium and potassium ions, is calculated by the difference between the sum of mole/l of anion equivalent ( HCO3 , СО 32  , SO 24  , С1¯) and the sum of mole/l of cation equivalent (Са2+, Мg2+). Only the ions with the content greater than 0.01 mmol/l equivalent are taken into account. To recalculate the calculated content of the sum of alkali metals from mmole/l equivalent in mg/l, the obtained value should be multiplied by an empirical coefficient equal to 25. In hydrochemical practice, there are various methods for determining the concentration of alkali metals, the detailed description of which is given in the manuals /1-3/. 54

4.1.8 Determination of dry residue

When water evaporates, the substances dissolved in it either precipitate or are destroyed and partially or completely evaporate. The mass of the resulting dry residue is related to the mineralization of water and depends on both the content of dissolved inorganic and organic substances and the form in which these compounds are in solution. The determination of the dry residue is of great practical importance. It is possible to estimate the total mineralization of water, to assess the content of dissolved organic matter, and to verify the correctness of the results obtained during the general chemical analysis of water. The dry residue is very precisely determined by the weight method, but does not coincide with the total content of ions determined in the analysis. This is due to the presence of dissolved substances in the water, which are not determined by the analysis, as well as chemical changes in the salt part of the sludge during the evaporation of water. For example, evaporation destroys hydrocarbons, hydrolyses calcium and magnesium salts, and does not fully volatilize the crystallization water contained in sulfate salts. Therefore, in the process of determining the dry residue, soda is added to the analyzed water, which converts the soluble salts into carbonates, which in turn completely dehydrate the sludge. The dry residue determined by the surface water analysis usually slightly exceeds the sum of the minerals determined by the chemical analysis. However, if the amount of the dry residue found in the analysis of waters with little dissolved organic matter exceeds the sum of ions determined analytically by 5 percent or more, then errors have been made in the analysis of the water. Process on the determination. A porcelain cup designed for evaporation of the sample under study is dried at 105-110 oC to a constant weight. Then soda (sodium carbonate) is added to it in the amount exceeding the supposed content of dissolved salts in the analyzed sample volume by about 2-3 times. (The amount of dissolved salts is pre-calculated after determining the basic chemical composition of the sample water). 55

A cup with sodium carbonate is weighed and a certain amount of water, which is chosen so that the weight of the resulting dry residue was 50-500 mg, is placed in it. A cup of water is placed on a water bath and evaporated dry. Wipe the cup with the sludge with filter paper, put in a drying closet and dry at a temperature of 150-180 oC for 2-3 hours to a constant weight. Calculation. The value of dry residue (X) in mg/l is calculated by the formula: X

a  b 1000 , V

where: a is the weight of the cup with dry residue, mg; c is the weight of the cup with soda, mg; V is the volume of water taken for determination, ml 4.2 Determination of biogenic content 4.2.1 Determination of nitrites

Determination of nitrites by spectrophotometric method with Griss reagent. The method is based on the ability of primary aromatic amines in the presence of nitric acid to form intensively colored diazocompounds. Optical density of the formed diazo-compounds is determined at λ = 536 nm. The method is applicable for determination of nitrites in surface waters with nitrogen content from 0.007 to 0.35 mg/l. Process of determination: 50 ml of test water (or a smaller volume brought to 50 ml by distilled water) is placed in a 100 ml conical flask, about 0.1 g of Griss dry reagent (at the tip of the scalpel) or 2.5 ml of its solution is added and thoroughly mixed. After 40 min (by stopwatch) the optical density of the solution is measured on a spectrophotometer or photo-colorimeter (green light filter) in cells with a layer thickness of 1 cm against distilled water. At low nitrite concentrations (0.007-0.05 mg/l), it is advisable to use a cuvette with a layer thickness of 5 cm (in this case, when constructing 56

the calibration curve also use cuvettes with a layer thickness of 5 cm). At the same time, the optical density of the water sample under study is determined without adding reagents. Its value is subtracted from the optical density of the sample. The nitrite content in mg/l is determined by the graduation curve. Construction of a graduation curve. 0; 0.1; 0.2; 0.4; 0.8; 1.0; 1.5; 2.0; 3.0 ml of standard solution are added to 50 ml measuring flasks and the volume is brought to the mark with distilled water. Concentrations of these solutions, respectively, are equal: 0; 0.01; 0.02; 0.04; 0.08; 0.10; 0.15; 0.20; 0.30 mg/l. Determine as described above (see "Process of determination"). Optical density of solutions is measured against distilled water. A graduation curve is drawn by plotting the nitrite concentration in mg/l on the abscissa axis and the optical density on the ordinate axis. Calculation: The mg/l nitrite content is calculated by the formula: Cx = c ∙ n , where: C is the concentration of nitrites found by the grading curve, mg/l; n is the degree of dilution of the initial water sample (if the sample under study is not diluted, n = 1; if taken 10 ml and diluted to 50 ml, n = 5, etc.). Reagents: 1) Grissant reagent. Griss's dry ready-made reagent, "puriss", prestripped in a mortar to a homogeneous mass. If there is no ready-made reagent, it is prepared as follows: (a) A solution of α-naphthylamine. 0.2 g of α-naphthylamine is dissolved in several drops of ice acetic acid and the volume is increased to 150 ml by 12% acetic acid. Stored in a dark vial with a lapped cap for several months; b) Sulfanilic acid solution. 0.5 g of sulfanilic acid is dissolved in a small amount of 12% acetic acid and the volume is increased to 150 ml. Stored in a dark vial with a lapped cap for several months; c) Acetic acid, 12%. 25 ml of glacial acetic acid is diluted with distilled water to 200 ml. Stored in a vial with a lapped cap for several months. 57

For operation, α-naphthylamine and sulfanilic acid solutions are mixed in equal quantities immediately before use. 2) Standard solutions of sodium nitrite NaNO2, "puriss": (a) Standard replacement solution, 250 mg/l. 0.6157 g of sodium nitrite dried at 110 °C and cooled in a desiccator above calcium chloride is dissolved in a measuring flask of 500 ml distilled water. Stored at a temperature of 3-5 °C for several weeks; b) Working standard solution, 5 mg/l. 5 ml of the standard replacement solution is diluted in a measuring flask of 250 ml with distilled water. Prepared before use. 4.2.2 Determination of nitrates

The method is based on the reduction of nitrates by metal cadmium

NO 3 + Cd + H2O = NO 2 + 2OH  + Cd2+ followed by the determination of the resulting nitrites with Griss's reagent. The efficiency of cadmium as a reducing agent increases significantly if it has been previously treated with a solution of copper salt. Restored copper settles on the surface of cadmium, forming a galvanic pair with it. The degree of nitrate reduction depends on the pH of the solution and the maximum one is at pH = 9.6. The duration of the cadmium reducer is quite long – several hundred samples. The method is intended for determination of nitrates in surface waters with the content of 0.01-0.35 mg/l. In case of higher concentrations of nitrates, the sample should be diluted with twice distilled water before determination. Process of determination. Two portions of the test water are selected for analysis: 25 and 100 ml. In the first of them nitrites are determined (see "Determination of nitrites"), and in the second one nitrates are reduced to nitrites. For this purpose, 2 ml of ammonium chloride solution is added to 100 ml of analyzed water, placed in a flask or a 250 ml glass. The contents of the flask are stirred and passed through a cadmium reducer at a rate of 8-10 ml/min by stopwatch. The first 70 ml of the 58

sample, passed through the reducer, is discarded, the next 25 ml is taken to a separate receiver and immediately about 10 mg of Griss dry reagent (on the tip of the scalpel) is added. The mixture is stirred and after 40 min the optical density of the solution is measured on a spectrophotometer (λ = 536 nm) or photo-colorimeter (green filter) in cells with a layer thickness of 1 cm against distilled water. At low concentrations of nitrates (0.010-0.100 mg/l), it is advisable to use cells with a layer thickness of 5 cm (in this case, cells with a layer thickness of 5 cm are also used in the construction of the calibration curve). Nitrate content in mg/l is found by the graduation curve. Construction of a graduation curve. 0; 0.1; 0.2; 0.3; 0.4; 6.0 ml of working standard solution are added to measuring flasks per 100 ml and the volume is brought to the mark with distilled water. The concentration of these solutions, respectively, is equal to: 0; 0.025; 0.050; 0.10; 0.15; 0.20; 0.30 mg/l. Determine as described above (see "Process of determination"). Optical density of solutions is measured against distilled water. A graduation curve is drawn by plotting the nitrate concentration in mg/l on the abscissa axis and the optical density on the ordinate axis. Calculation. The content of Cx nitrates in mg/l is calculated by the formula: Cx = С ∙ n – С1 where: C is the concentration (mg/l) of nitrates and nitrites in the solution passed through the reducer. The latter is found by the graduation curve for nitrates; n is the degree of dilution of the initial water sample; C1 is the nitrite concentration in the test water, found by the calibration curve for nitrites, mg/l. Reagents: 1. Ammonium chloride solution NH4Cl, "puriss". 175 mg ammonium chloride is dissolved in distilled water, and the volume of the solution is brought to 500 ml with water. The solution is stable for several months.

59

2. Solution of copper sulfate CuSO4 ∙ 5H2O, "puriss". 20 g. of copper sulfate is dissolved in distilled water, and the volume of the solution is brought to 1 liter with water. Prepare before use. 3. Cadmium metal, 99.9 %, copper-coated. The gearbox is filled with copper cadmium in the form of sawdust. If it is not available, the sawdust is obtained as follows: cadmium sticks are fixed in the bench vise and chiseled with fret saw. The resulting sawdust is sifted through sieves with hole sizes of 2 and 0.5 mm. They use a fraction of sawdust that has passed through the first sieve and has not passed through the second sieve. 100 g of the obtained sawdust washed with distilled water, acidified hydrochloric acid, pour 500 ml of copper sulfate solution and stirred until the solution is discolored. Copper-coated cadmium, together with the solution, is transferred to a reducer column filled with distilled water so that there are no air bubbles. Copper-coated cadmium is transferred to the column by continuous tapping with a glass rod with a rubber tube at the end. It is necessary that the cadmium fills the column evenly without any cavities. The height of the copper cadmium layer should be at least 25 cm. Before starting work, 300-500 ml of standard potassium nitrate solution with 0.2 mg/l nitrate content is passed through the column. Then the column is washed with 100 ml of distilled water and the standard solutions are passed to build a graduation curve. To check the reduced capacity of cadmium, a standard nitrate solution with a concentration of 0.1 mg/l is passed through the reducer before each series of samples and the resulting nitrite ions are determined. The optical density of the resulting solution is compared to the graduation curve, and if the density has decreased by more than 10%, cadmium must be regenerated. For this purpose, it is transferred to a 500 ml glass and washed with 300 ml of 5% hydrochloric acid. The acid is decanted and the procedure is repeated. The metal is finally washed with distilled water to 6 pH of rinsing water and dried. Weigh 100 g of cadmium and recool the purified cadmium as described above. 4. Hydrochloric acid, 5%. 143 ml of concentrated hydrochloric acid is diluted to 1 l with distilled water. 5. Griss reagent, "puriss". The ready dry reagent is grinded in a mortar before use. 60

6. Standard solutions of potassium nitrate: (a) Standard replacement solution, 250 mg/l. A weight of 0.902 g dried at 110 °C and cooled in the desiccator over calcium chloride chemically pure KNO3 is dissolved in distilled water, and the volume of the solution is brought up to 500 ml; b) Working standard solution, 5 mg/l. 5 ml of the standard replacement solution is diluted with distilled water up to 250 ml. 4.2.3 Determination of small quantities of iron

The determination is based on the reaction of sulfosalicylic acid with iron salts in an alkaline environment with the formation of yellow iron complex. In this way it is possible to determine 0.1-10 mg/l of iron. Relative error is 0.1 mg/l. Process of determination. In the chemical cup measure 100 ml of analyzed water with a pipette, pour 5 ml of concentrated HCl and put on a water bath. Evaporate the solution to 5-6 ml. To the remaining solution add several crystals of ammonium persulfate (NH4)2S2O8, the solution is cooled and transferred quantitatively from the cup to the measuring flask of 50 ml (carefully rinse the cup with distilled water and transfer into the same flask up to 25 ml). Then add 2.5 ml of 30% sulfosalicylic acid solution, mix the solution and add 10% ammonia solution (NH4OH) until yellow color (usually 7-8 ml). Bring the volume to the mark with distilled water and mix thoroughly. After 5 minutes, determine the optical density and subtract the value of the optical density of the blank definition performed in the same way with distilled water from the value found. Find the iron content on the graduation curve. Plotting a graduation curve. 0.0; 0.10; 0.20; 0.50; 0.70; 1.00; 1.20; 1.70; 2.00; 3.00 ml of the standard solution of 10 µg/ml is injected into 50 ml measuring flasks and added with distilled water to the volume of 25 ml. The solutions obtained contain, respectively, 0; 10; 20; 50; 70; 100; 120; 170; 200; 300 µg/ml of iron. Then 0.5 ml of HCl concentrated, 2.5 ml of sulfosalicylic acid and 10 % of NH4OH solution are added before yellow coloring. The volume is brought to the mark with distilled water, thoroughly mixed and after 5 minutes the optical density is measured. Subtract the optical density of the blank definition from the optical density of the analyzed solution and draw a graph in the coordinates of the optical density – iron concentration. 61

Equipment. Photoelectrocolorimeter FEC-M 56 or another brand with blue filter, cell 5 cm. Reagents: 1. Sulfosalicylic acid solution, 30%; 2. HCl (d = 1.19) "puriss"; 3. NH4OH, 10%; 25%; 4. Standard iron solution containing 100 µg/ml. 0.8634 g FeNH4(SO4)2. ∙ 12H2О "puriss" lilac crystals are dissolved in 50 ml of 1 N HCl and the volume of distilled water is brought to 1 liter. The working standard iron solution of 10 µg/ml is prepared from the standard iron solution (100 µg/ml) by dilution of 10 times. 4.2.4 Determination of phosphate

Photocolorimetric method based on formation of complex phosphoric-molybdenum acid H7[P(Mo2O7)6] · 28H2О is used for determination of phosphates. This acid in a strongly acidic solution is reduced by ascorbic acid in the presence of potassium antimonymolybdenum to the phosphorus-molybdenum complex colored in an intense blue color. The addition of antimony and potassium tartrate promotes faster and more intensive development of the solution's coloring. It has been established that antimony is a part of the complex formed. The method allows us to determine without dilution up to 0.1 mg in 1 liter of water. The relative error of the method is ± 10%, the sensitivity is 0.003 mg/l. Process of determination. 40 ml of the test water is taken out with a pipette into a 50 ml measuring flask, 8 ml of mixed reagent is added, the volume is brought to the mark with bidistilled water and thoroughly mixed. After 10 minutes, the optical density of the solution is measured on a photocolorimeter (red filter, 2.0 cm thick cells) or spectrophotometer at λ = 882 nm. From the found value of extinction the extinction of the blank definition is subtracted (42 ml of bidistilled water, 8 ml of mixed reagent). If the water under examination is stained or slightly cloudy, its optical density is measured separately at 882 nm and subtracted from the result obtained. The phosphate content (in mg/l) is determined by the grading curve. 62

Plotting a graduation curve. In a series of measuring flasks for 50 ml measure with a pipette 0; 0.5; 1.0; 2.0; 4.0; 5.0; 10 ml of standard working solution of potassium phosphate and bring the volume to the mark with distilled water. In the obtained series of standard phosphate solutions with concentrations of 0; 0.01; 0.02; 0.04; 0.08; 0.10; 0.20 mg/l, definitions are made as described above. The value of the optical density of the blank definition is subtracted from the optical density of standard solutions. A graduation curve is drawn by plotting the phosphorus concentration in mg/l on the abscissa axis and the optical density on the ordinate axis. Reagents. 1. Sulphuric acid solution H2SO4 = 5 mol/l. 70 ml of concentrated sulphuric acid (d = 1.84) is diluted in 500 ml of distilled water. 2. Ammonium molybdate (NH4)2MoO4. 20 g ammonium molybdate solution is dissolved in 500 ml of distilled water. 3. Ascorbic acid 0.1 mol/l. 1.31 g of ascorbic acid is dissolved in 75 ml of distilled water. This solution should be prepared on the day of determination. To preserve the solution, 25 mg of ethylenediaminederived acetic acid (dynatrium salt) and 0.5 mg of formic acid per 75 ml solution are added. 4. К(SbO)C4H4O6. ∙ 1/2H2O antimony-wine potassium solution containing 1 mg/ml of antimony. 0.2726 g of salt is dissolved in 100 ml of distilled water. 5. Mixed reagent is prepared by mixing 125 ml of sulfuric acid solution with concentration of 5 mol/l and 37.5 ml of ammonium molybdate solution. Then 75 ml of ascorbic acid solution and 12.5 ml of antimony and potassium tartrate solution are added. It is recommended to store this solution for not more than 24 hours. 6. Reserve standard solution of potassium phosphate KH2PO4. 0.1757 g of potassium phosphate (pre-dried at 105 °C to a constant mass) is dissolved in distilled water and 2 ml of chloroform is added. The volume is brought up to 1 liter with distilled water. 1 ml of the obtained potassium phosphate solutions contains 0.04 mg of phosphorus. 7. Working standard solution of potassium phosphate. 5 ml of the standard reserve solution is diluted to 200 ml with distilled water. 1 ml contains 0.001 mg. 63

4.2.5 Determination of silicic acid

The photocolorimetric method is based on the ability of silicon compounds to form complex compounds with molybdates in the presence of mineral acids in yellow color – heteropoly acids H8Si2(Mo2O7)6. This method can be used in the analysis of transparent and slightly turbid water samples. The relative error of the method is ± 5%. Sensitivity is 0.1 mg/l silicon. Process of determination. 50 ml of test water is placed in a 100 ml glass or flask, 2 ml of hydrochloric acid solution and 3 ml of ammonium molybdate solution are added and left to stand for 15 minutes. After 15 minutes, photocolorimetry is started using a 5 cm ditch and a blue filter. The color is stable for 40 minutes. Simultaneously with a series of definitions, a blank experiment is performed (2 ml of hydrochloric acid and 3 ml of ammonium molybdate are added to 50 ml of distilled water). The value of the optical density of the blank experiment is subtracted from the optical density of the test water. The silicon content in mg/l is determined by the graduation curve. Plotting a graduation curve. A standard solution of sodium silicone solution in the amount shown in Table 5 is added to a series of flasks with a capacity of 50 ml, and determination is carried out as described above. The optical density of the blank experiment is subtracted from the optical density of standard solutions. A graduation curve is drawn by plotting the silicon concentration in mg/l on the abscissa axis and the optical density on the ordinate axis. Reagents: 1) The basic standard silicon solution is prepared as follows. 0.335 g of "puriss" sodium hexafluorosilicate Na2SiF6, pre-crushed in agate mortar and dried in a drying cabinet at 120-150 °C, is dissolved in a measuring flask of 500 ml within 2 hours. For this purpose, pour 200-250 ml of hot distilled water and shake until dissolved. To speed up the dissolution process, the flask is placed in a boiling water bath. After cooling the solution, its volume is brought to the mark with distilled water and mixed. The concentration of this solution is 100 mg/l of silicon. 64

Table 5 Standard solution volume and silicon content for calibration curve Volume of standard silicon solution with concentration 10 mg/l, ml

Silicon content, mg/l

0 1.0 2.0 3.0 4.0 5.0

0 0.2 0.4 0,6 0.8 1.0

Volume of standard silicon solution, with a concentration of 100 mg/l, ml 0 0.5 1.0 2.5 5.0 7.5

Silicon content, mg/l

0 1.0 2.0 5.0 10.0 15.0

This solution is used to prepare a second standard solution. For this purpose, 10 ml of the main standard solution is taken and diluted with up to 100 ml of distilled water. The concentration of this solution is 10 mg/l Si. When stored in polyethylene containers, the main solution is stable for several months. 2) Ammonium molybdate solution. 8.3 ml of "puriss" ammonium molybdate (NH4)6Mo7O24 · 4H2O is dissolved in distilled water and brought to 100 ml in a measuring flask. The solution should be prepared in small quantities, resuming it after 10 days. 3) Hydrochloric acid solution. 42 ml of "puriss" concentrated HCl is diluted with distilled water up to 100 ml. 4.3 Identification of trace elements 4.3.1 Determination of fluorine

Colorimetric zirconium-alizarin determination of fluorine. The reaction of fluoride ions with zirconium (IV) produces complex fluoride salts. The stability of these complexes is greater than that of colored zirconium complexes with organic dyes, in this case with alizarin sulfonate. Extraction of the equivalent amount of dye from the complex salt is revealed by the change in color, the intensity of which corresponds to the concentration of fluorine. 65

Preparation of the standard scale and the process of determination. Measure 0; 1.0; 2.0; 3.0; ... 30 ml of standard working solution in Nessler cylinders and bring the volume up to 100 ml with distilled water. Solutions will contain, respectively, 0; 0.05; 0.10; 0.15 ... 1.50 mg/l of fluorine. The same cylinders shall be filled with 100 ml of transparent sample. The standard solutions of 5 ml of acidic zirconiumalizarin reagent are added to the samples and mixed. After 1 hour, the coloring obtained is compared to the standard. Fresh standard solutions must be prepared for each definition cycle. For the analysis of samples with an approximately known concentration of fluorine, a number of standards should be prepared that are close in concentration to the expected concentration of fluorine in the sample. Reagents. 1. Zirconium-alizarin reagent. 0.30 g ZrOCI2 · 8H2O is dissolved in 50 ml distilled water. In addition to the obtained solution, a solution containing 0.07 g of sodium alizarin-sulfonate (red C alizarin) in 50 ml of distilled water is added. Then a diluted acid solution is prepared. For this purpose, 100 ml of concentrated hydrochloric acid is mixed with 300 ml of distilled water and 33.3 ml of concentrated sulphuric acid is mixed with 400 ml of distilled water. After cooling, the two acid solutions are combined. The mixture of acids is added to the mixture of alizarin-sulfonate and zirconium salt and the volume is increased to 1 liter with distilled water. The solution remains stable for 6 months. Store it in a dark bottle. 2. The basic standard solution of sodium fluoride. Dissolve 0.221 g of NaF (Pure for analysis, pre-dried at 105 °C) in distilled water and bring the volume up to 1 liter. The solution contains 0.100 mg F  in 1 ml. 3. Working standard solution of sodium fluoride. Dilute 50 ml of the basic standard solution with distilled water, bringing the volume to 1 liter. In all cases, the freshly prepared solution should be used. In 1 ml of the working standard solution contains 0.005 mg F  . 4.3.2 Determination of boron

Colorimetric determination of boron with carmine acid. Solution of carmine acid with sulfuric acid in the presence of borates changes the color from red to blue. 66

Process of determination. 10-50 ml of water (depending on the boron content) is placed in a platinum cup, 1 ml of 10% NaCl and 0.5 ml of 10% NaOH is added. The solution is evaporated in a sand bath (without cracking the dry residue). Add 3 ml of 0.025% carmine and 12 ml of concentrated sulphuric acid to the cooled dry residue (work under draught). The solution is thoroughly stirred with a glass rod made of borone-free glass and poured into a glass tube made of borone-free glass with a lapped cap. The next day the solution is stirred again, poured into the cuvette at 30 mm and colorimetrated using a red filter. A solution with 3 ml of 0.025% carmine and 12 ml of concentrated sulfuric acid is used as a reference (zero solution). Plotting a graduation curve. Standard solutions containing 1, 2, 4, 6, 8, 10 µg/l boron are treated as a sample. The optical density – boron concentration – is plotted in coordinates. Reagents: 1. Sodium caustic – "puriss", 10% solution; 2. Sodium chloride, "puriss", 10% solution; 3. Carmine, 0.025% solution in sulfuric acid. 0.250 g of carmine grinded in a thin powder was placed in small cups and poured with small portions of sulfuric acid (d = 1.84), stirred with a glass rod to dissolve the carmine, poured into a liter measuring flask, brought by the same acid to the mark. 4. Boric acid (standard solution). 0.286 g of recrystallized boric acid ("puriss") is dissolved in a measuring flask for 500 ml with distilled water. The resulting solution contains 100 µg/l. The standard solution containing 10 µg/l is prepared from the previous one by 10-times dilution. 4.3.3 Determining the amount of bromine and iodine

The determination is based on the oxidation of bromine and iodine ions up to BrO3 and IO3 by potassium hypochlorite, destruction of the excess of the latter by sodium ants and iodometric determination of the sum of iodine and bromine. Process of determination. The required volume of water is poured into the cup for 100-150 ml in portions (from 100 to 400 ml) and evaporated in a water bath to the volume of 20-25 ml. Throw a blue 67

litmus paper into this cup and acidify with sulfuric acid until red. Also, 4 ml of saturated boric acid solution (radially along the glass wall) and 1 ml of KCIO are injected there, and put on a boiling water bath for 5 minutes (Br¯ to BrO3 and J¯ to JO3 ). Then, 2 ml of 20% sodium formate solution is applied, and the solution is moved to the tile (asbestos) for 5 minutes. The solution is then cooled. 20 drops of 5% ammonium molybdate solution, 4 to 8 ml of sulphuric acid, several potassium iodide crystals and 0.5 ml of starch are added to the cooled solution. Titrate immediately with sodium hyposulfite. Reagents. 1. Potassium hypochlorite solution, KClO. It is prepared by passing Cl2 current into KOH solution (chlorine is passed evenly and slowly) containing 125 g/l (31.25 g KOH of "CP" brand for 250 ml H2O). The solution must be cooled down well (before the solution starts to freeze) before the chlorine passes through and during saturation. Saturation ends when the remaining KOH forms a 0.3 mol/l solution. Readiness test: take 5 ml of KClO, heat to boil, add a few drops of 3% hydrogen peroxide solution before stopping gas production, cool, add a few drops of methylorange and titrate 0.1 mol/l HCl. Titration should take 15 ml of acid. The experiment is blank. 2. A saturated boric acid solution is prepared from recrystallized boric acid (H3BO3); 3. 1% ammonium molybdate solution; 4. 20% sodium formate solution Nа2HCO2; 5. 0.5% soluble starch solution (0.5 g of starch diluted in 10 ml of distilled water) Bring 90 ml of distilled water to boil and pour 10 ml of diluted starch into it); 6. Kl, crystals; 7. H2SO4 1.5 mol/l. Mix 500 ml of water and 41 ml of 98% H2SO4 d = 1.84; 8. Na2S2O3 0.001 mol/l (prepared from fixanal). 20 ml of Na2S2O3 C = 0.05 mol/l is poured into a 1 l measuring flask and brought to the mark with distilled water; 9. Standard solution of potassium bromide containing 0.01 mg/ml Br. First, a standard solution containing 1 mg/ml Br is prepared. For this purpose, 1.4893 g of KBr is dissolved in a 1 litre measuring flask. The obtained solution is diluted 100 times and contains 0.01 mg/ml Br. 68

10. Standard solution of potassium iodide containing 1 mg/l I. 1.3080 g KI is dissolved by distilled water in a 1 litre measuring flask. This solution is then diluted 100 times and contains 0.01 mg/ml of iodine. Determining the normality of sodium thiosulphate. In a 50 ml flask, 5 ml of standard KBr solution containing 0.01 mg/ml Br is taken, then it is acidified with 3 drops of sulfuric acid, 4 drops of saturated boric acid solution and 1 ml of KClO are added. The solution is heated for 5 minutes in a water bath, 2 ml of 20% sodium formate solution is added and boiled for 5 minutes on an asbestos mesh. The solution is cooled to room temperature, 4 ml of sulphuric acid is added, 15 drops of 1% ammonium molybdate solution, 2-3 KI crystalline crystals and 0.5 ml of starch are added. The released iodine is immediately titrated with sodium thiosulphate solution. Calculation. The amount of bromine and iodine (µg/l) is calculated using the formula: С (Br¯ + J¯) =

T  V1 1000 1000 , V2

where: T is the sodium thiosulphate titer; V1 is the volume of sodium thiosulphate, ml; V2 is the volume of water sample, ml 4.3.4 Determination of iodine

The essence of the method is based on the catalytic action of iodide present in water on the redox reaction: 2Ce4+ + As3+ → 2Ce3+ + As5+ The reaction rate is directly proportional to the iodide concentration. The iodine content is determined after the inhibition of the reaction by introducing a known amount of divalent iron, the excess of which is then determined. The role of the background of the catalytic action of iodine is played by sodium chloride. 69

Process of determination. Place 20 ml of natural water in 100 ml chemical glasses (make a dash of 25 ml on the glass beforehand). In addition to the sample, 2 ml of H2SO4 solution with a concentration of 6.25 mol/l, 4 ml of 20% sodium chloride solution (or 23% of KCl solution) are added to the sample and distilled water is purified to 25 ml. Pour 5 ml of Na3AsO3 solution from a burette, stir the solution and pour 5 ml of Ce(SO4)2 solution 0.004 mol/l. Again stir the solution and place in the mold for 40 min at t = 20 °C. After 40 minutes, 5 ml of Maura salt and 4 drops of phenylanthranilic acid are added to the solution. Slowly, the droplets are titrated with cerium sulfate until a redviolet colouring does not disappear within 1 minute. It is convenient to thermostat several samples simultaneously. Simultaneously with the water sample, two blank samples are performed with reducing agents contained in the water (water sample without Na3AsO3, carried out through the whole process of analysis). Sample for reducing agents. The aliquot sample is acidified with sulfuric acid and titrated with phenylanthranilic acid using cerium sulfate. If more than 0.1 ml of cerium sulfate was used for the determination, the same amount of cerium sulfate is added to the other basic aliquot sample without introducing an indicator, which was used for titration of the previous aliquot part and the analysis is continued as described above. The iodine content of the titrated solution is found by the calibration schedule. If the iodine content is such that the flow rate of cerium sulfate does not follow a straight-line graph, the analysis is repeated, changing the volume of the analyzed water. Building a graduation curve. Standard solutions of potassium iodide containing 0.1 mg/ml and 1 µg/ml of iodine in the following quantities are placed in glasses with a capacity of 100 ml: 0; 0.05; 0.1; 0.2; 0.3; 0.5; 1.0 µg/ml. Add 15 ml of distilled water and 2 ml of sulphuric acid solution with concentration of 6.25 mol/l, 4 ml of 20% sodium chloride solution to each cup and top up to 25 ml mark. Then, 5 ml of Na3AsO3 solution is added from the burette as described above. According to the data obtained, a graph is drawn up. The reagents used must not contain iodine. 70

Reagents: 1. Sulphate cerium, C = 0.004 mol/l in 0.5 mol/l sulfuric acid. 3.2345 g Ce(SO4)2 to dissolve in H2SO4 C = 0.5 mol/l and to bring the same acid to a mark of 1 l. The titre is set according to Maura's salt; 2. Mora salt, FeSO4 · (NH4)2SO4, C = 0.01 mol/l in sulfuric acid (1:10). 3.95 g of Maura salt is dissolved in 200 ml of sulfuric acid (1:10), after dissolving the salt, the solution is brought to 1 liter in a measuring flask with acid; 3. Sodium trioxoarsenate (III) Na3AsO3, C = 0.007 mol/l in sulfuric acid C = 0.5 mol/l. 2.598 g of sodium trioxoarsenate (III) salt should be dissolved in sulfuric acid of the specified concentration and brought up to 1 liter in a measuring flask. 4. Sulphuric acid H2SO4, C = 6.25 mol/l. 350 ml of concentrated sulphuric acid (d = 1.84) should be brought to 1 l with distilled water; 5. Sodium chloride NaCl, 20% solution; 6. Phenylanthranilic acid, 0.03% solution in 0.3% solution of sodium carbonate; 7. Sulphuric acid, С = 0.5 mol/l. The solution contains 28 ml of concentrated sulphuric acid (d = 1.84) in 1 l of the solution. 8. Standard solution: a) Reserve solution, 0.1 mg/ml iodine. Dissolve 0.1308 g of KI in 1 liter water; b) The working solution, 1 µg/ml is prepared on the day of determination of the reserve solution. 4.3.5 Determination of copper and zinc

The quantitative determination of copper is based on the formation of yellow-colored copper diethyldithiocarbamate at the interaction of lead diethyldithiocarbamate in chloroform with copper ions contained in water:

71

Quantitative determination of zinc is made in the water sample after extraction of copper diethyl dithiocarbamate and is based on its interaction with diphenyltiocarboson (dithizone) in tetrachloride carbon, which results in formation of zinc dithizonate colored red:

The linear relationship between the copper and zinc content of the sample and the optical density remains within the range of 0.5-10 µg. Process of determination of copper content. 250 ml of pre-filtered membrane filter and acidified sample is placed in a 500 ml flat-bottom flask. Add 0.25 g of ammonium persulfate. The sample is boiled for 20 minutes to convert all forms of metal into ionic state, cooled and transferred to a 500 ml separating funnel. Add 3-4 drops of methylroth and neutralize with ammonia until yellow (the interval of transition from red to yellow at pH = 4.2 – 6.2). Then 10 ml of 10 % potassiumsodium tartar solution and 10 ml of acetate buffer are added and 10 ml of lead diethyl dithiocarbamate solution are extracted in chloroform for 2 minutes. After separation of layers, copper diethyl dithiocarbamate extract is transferred into a 2 cm thick cell. Optical density of copper diethyldithiocarbamate extract is measured on a spectrophotometer at a wavelength of 430 nm (ν = 23256 cm-1) or on a photoelectrocolorimeter with a violet filter in cells with a layer thickness of 2 cm against chloroform. Measurement of optical density is carried out quickly to avoid evaporation of chloroform. Copper content is found by the graduation curve. If the copper content in the sample exceeds 10 µg, the extraction is repeated until the chloroform color disappears. The extracts are drained together. If necessary, use the aliquot part of the extract, diluting it with pure chloroform. 72

Calculation: Copper content of Cx in µg/l is determined by the formula

Cx = C-r , where: C is the concentration of copper, found on the graduation curve, µg / l Сu, p is the degree of dilution of the original water sample (if the sample under study is not diluted, p = 1). Progress of determining the zinc content. Aqueous solution in the separating funnel after separation of chloroform extract of copper diethyl dithiocarbamate is washed by 5 ml of pure carbon tetrachloride and the funnel is shaken for 30 seconds. After separating the layers of tetrachloric carbon, it is separated and discarded. In addition to the solution, 4 ml of 25% sodium thiosulphate solution and 10 ml of 0.004% dithion solution in CCl4 are added and shaken for 2 minutes. Tetrachloride carbon containing zinc dithionate is transferred to a 1 cm thick cell and the optical density of the solution against tetrachloride carbon is measured on the spectrophotometer at a wavelength of 535 nm (ν = 18,700 m-1 or on a photoelectric colorimeter with a green filter). The content is found by the grading curve. If the sample contains more than 10 µg of zinc, a second extraction is performed before the extract becomes green. The extracts are drained together. If necessary, the aliquot part of the extract is diluted with 0.004 % dithion solution. Calculation. The zinc content of Cx in µg/l Zn is determined by the formula: Cx = C-r , where: C is the concentration of Zn, found by the calibration curve, µg/L Zn; p is the degree of dilution of the original water sample (if the sample under study is not diluted, p = 1). Plotting a graduation curve. Pour 250 ml of bidistilled water into four flasks per 500 ml, add 5 ml of HC1 solution and pour 1.0; 3.0; 6.0; 10 ml of copper and zinc working solution, respectively. Then 73

0.25 g of ammonium persulfate is added to each flask, boiled for 20 minutes, the solutions are cooled and determined as described above (see "Process of determination"). A graduation curve is drawn by plotting the concentration of copper or zinc on the abscissa axis in µg/l, and the optical density on the ordinate axis. Reagents: 1) Lead diethyl dithiocarbamate solution (C4H10NCS2)2Pb. 160 mg of salt is dissolved in chloroform and the solution in a measuring flask is brought up to 1 liter. If there is no ready lead diethyl dithiocarbamate, it is prepared as follows. a) 100 mg of lead acetate Pb(CH3COO)2 ∙ 3H2O "puriss" is acidified with one drop of concentrated nitric acid and dissolved in 10 ml of twice distilled water; b) 500 mg of sodium diethyldithiocarbamate is dissolved in 100 ml of bidistillate. The solution is placed in a separating funnel for 250 ml and 10 ml of chloroform is added. The contents of the funnel are shaken for 2 minutes, and after separation of liquids the chloroform layer is drained and discarded. This operation of cleaning the solution is performed twice. Then the aqueous solution is filtered through a paper filter prewashed with hydrochloric acid solution (1:20) and twice distilled water; c) 250 ml of chloroform, lead acetate solution (see point "a") and 50 ml of sodium diethyl dithiocarbamate solution are added to the separating funnel per 1 liter. White lead diethyldithiocarbamate precipitate is formed. The contents of the funnel are shaken until the white residue is dissolved. To rinse, a pack of paper filters is taken with white ribbon, placed in a Buechner funnel and, with the help of a vacuum pump, the filters are rinsed with 500 ml HC1 (1:20), then rinsed with bidistillate until a neutral reaction of rinsing water (control with universal indicator paper). The same filters are used in all cases when it is recommended to take the filter washed with HC1 solution. After the liquids have been separated, another 10 ml of sodium diethyl dithiocarbamate solution is added. If this results in the formation of sludge in the water layer, the contents of the funnel are shaken again until the sludge dissolves completely in the chloroform. This operation is interrupted if no white residue falls out after the sodium diethyl dithiocarbamate solution has been added. The chloroform layer is separated, filtered through a paper filter previously dampened with chloroform and diluted with chloroform to 1 liter. 74

2) Dithizone solutions: a) The main solution, 0.1%; 100 mg of dithizone is wetted with tetrachloric carbon and then dissolved in a 100 ml measuring flask in tetrachloric carbon and labeled. The dithizone solution is filtered through a paper filter previously moistened with tetrachloric carbon; b) Worker, 0,004 % solution. 4 ml of 0.1% dithizone solution is diluted with tetrachloric carbon in a 100 ml measuring flask in such a way that the optical density of the solution is equal to 0.600 ± 0.010 with respect to tetrachloric carbon. The solution is prepared on the day of determination. Cleaning up the dithizone. If necessary, the dithizone is cleaned as follows. 10 mg of dithizone is dissolved in 100 ml of chloroform. The solution is transferred to the separating funnel for 500 ml, 100 ml of ammonia solution is added (diluted to 100 ml of 1 ml of concentrated 25% ammonia twice with distilled water) and 5 ml of 5% of ascorbic acid solution. After separation of the liquid layers, the chloroform layer is discharged into a clean separating funnel. Aqueous solution of dithizone is filtered into a 1 liter flask through a paper filter washed with hydrochloric acid solution (1:20) and twice distilled water. A new portion of ammonia solution is added to the chloroform solution, 5 ml of 5% ascorbic acid solution and the contents of the funnel are shaken again within 2 minutes. The operation of dithizone purification is repeated 5-6 times until the aqueous ammonia solution is colored orange. All portions of aqueous dithizone solution are filtered into a 1 litre flask. Hydrochloric acid (1:1) should be added before the dithizone precipitates. The sludge is filtered out through a paper filter, washed 3 times with 1% solution of ascorbic acid and dried in the air. Purified dithizone is stored in a dark place. 3) Potassium-sodium solution of tartaric acid KNaC4H4O6 · 4H2O "puriss. spec." 10% – solution. 100 g of salt is dissolved in a 1 litre measuring flask in twice distilled water. To clean the solution of potassium-sodium tartar from heavy metals, pour 5 ml of 0.1% solution of dithizone in tetrachloride carbon and shake for 2 minutes. The operation is repeated twice. The dithizone residues are removed by shaking the solution with 10 ml of carbon tetrachloride twice. The solution is filtered through a paper filter washed with hydrochloric acid solution (1:20) and twice distilled water. 75

4) Acetate buffer solution. 100 ml 2 mol/l of CH3COOH solution is mixed with 900 ml of CH3COONa C = 2 mol/l (245 g of sodium acetate is dissolved in twice distilled water in a 1 l measuring flask). The buffer solution is cleaned with 0.1% dithizone solution in tetrachloride carbon as described above (see p. 3). 5) Sodium thiosulphate solution Na2S2O3 · 5H2O "puriss. spec.", 25% solution. 250 g of sodium thiosulphate is dissolved in twice distilled water in a 1 litre measuring flask. Purification is carried out with 0.1% dithizone solution in tetrachloric carbon as described above (see p. 3). 6) Ascorbic acid grade "puriss". 7) Hydrochloric acid solution HC1, C = 6 mol/l. The solution is obtained by isopiestic distillation of concentrated HCl. It is poured on the bottom of the desiccator and a cup with the same volume of bidistillate is placed on the insert. After two days, a balance is established and the cup produces a HCl solution with a concentration of 6 mol/l. This HCl solution can be obtained by conventional distillation in a glass grinding machine. For this purpose, the concentrated acid is diluted twice and distilled. We should remind that isopiestic solutions are two or more solutions of non-volatile components in the same solvent, having a common equilibrium vapor phase (i.e., in isopiestic equilibrium). 8) Ammonia solution NH4OH "puriss" is obtained in the same way as HCl C = 6 mol/l. 9) Chloroform CHCl3 "puriss". Chloroform is cleaned by distillation with a deflegmator at 61.2 °C using a water bath. Heavy metal impurities are eliminated by extraction with hydrochloric acid solution C = 6 mol/l. 10) Four-chlorinated carbon CCl4 "puriss". Four-chlorine carbon is purified by distillation in the device made of glass "pyrex" with a deflegmator at a temperature of 76.5 °C, using a water bath. Heavy metals are removed by shaking off carbon tetrachloride with hydrochloric acid solution. 11) Methyl red indicator, pH = 4.2-6.2. Dissolve 0.2 mg of methyl red in a 100 ml measuring flask in 60% alcohol rectification. 12) Ammonium persulfate, (NH4)2S2O8 "puriss. spec." purify by recrystallization: 700 g of ammonium persulfate is dissolved in 700 ml of twice distilled water, heated to 40-50 °C. Quickly filter the solution through a folded filter and cool the filtrate in water with ice. Crystals of purified ammonium persulfate are sucked off at the Buechner funnel and washed with a small amount of water twice distilled. 76

13) Standard zinc solutions: a) A basic standard solution containing 100 µg/ml zinc. 0.100 mg of "puriss" metal zinc is dissolved in a tube of 2 ml hydrochloric acid (1:1). The solution is transferred to a measuring flask and the volume is increased twice with distilled water to 1 liter; b) Working standard solution with zinc content of 1 µg/ml. 1 ml of the basic standard solution is diluted twice with distilled water in a 100 ml measuring flask. The working standard solution is prepared immediately before use. 14) Standard copper solutions: a) A basic standard solution with a copper content of 100 µg/ml. 0.3928 g CuSO4 · 5H2O "puriss" is dissolved in a 1 litre measuring flask in a small amount of double distilled water. Pour in 10 ml of sulfuric acid (1:1) and bring the volume of the solution to 1 liter twice distilled water; b) A basic standard solution containing 1 µg/ml of copper. 1 ml of the basic standard copper sulphate solution is diluted with twice distilled water in a 100 ml measuring flask. The working standard solution is prepared immediately before use. 15) Hydrochloric acid HCl (1:20) is prepared by mixing 1 volume of concentrated acid (d = 1.19) and 20 volumes of distilled water. 16) Hydrochloric acid (1:1) is prepared by mixing 1 volume of concentrated acid (d = 1.19) and 1 volume of distilled water. 4.3.6 Determination of manganese

The method is based on the interaction of manganese with formaldexime in an alkaline medium with the formation of dissolved formaldeximate of manganese, painted in reddish-brown color, having a composition (CH2NO)3 Mn, in which manganese is present in a trivalent state. Process of determination. Direct determination of Mn in natural waters containing no more than 20 mg/ml Mn. A pipette of 25 ml of water is oured into a 100 ml cup, 2 ml of tartaric acid solution is injected and neutralized with ammonia (1:1) up to pH = 10 (about 1.5-2.0 ml on universal paper). Then pour 5 ml of ammonia buffer solution and 2 ml of formaldexime, the solution is 77

mixed. After 10 minutes, 2 ml of 0.1 mol/l trilon B solution and 2 ml of 10% hydroxylamine solution are added, diluted with water up to 50 ml and after 10 minutes the optical density (green filter) is measured using 50 mm long cells. The Mn content is determined by the grading curve. Plotting a graduation curve. In the measuring flasks per 100 ml is added: 0; 2; 5; 5; 10; 20; 40; 50 ml of working standard solution of potassium permanganate containing 10 µg/ml of manganese and 50 ml of working standard solution of iron containing 10 µg/ml of iron. Add 2 ml of tartaric acid and continue the analysis as described above. The scale is stable for 17 hours. Calculation. The manganese content of Cx in µg/l Mn is determined by the formula: Cx = Cp , where: C is the concentration of Mn, found on the grading curve, µg/l Mn; p is the degree of dilution of the original water sample (if the sample under study is not diluted, p = 1). Reagents: 1) Standard manganese solution. 2.877 g of KMnO4 is dissolved in water, 50 ml of H2SO4 (1:4) and sodium sulphite are added until the solution is completely discolored, after which the solution is boiled until SO2 is removed and diluted with water up to 1 litre. Get a standard replacement solution containing 1 ml of 1 mg Mn+2. The working solution is prepared by diluting the spare solution 100 times (10 µg/ml). 2) Tartaric acid. 30g tartaric acid is dissolved in 100ml distilled water. 3) Formaldoxime. 8 g hydroxylamine hydroxylamine is dissolved in 100 ml of distilled water, add 4 ml 37% of paraformaldehyde (fomalin) and heat to boil. After complete dissolution of the suspension, dilute with water to 200 ml. The solution is suitable for several weeks. When preparing this reagent formalin should be fresh, not polymerrized. 4) Buffer solution, pH = 10, chloride-ammonia. 54 g NH4C1 is dissolved in 350 ml of concentrated NH4OH and diluted with water to 1 liter. 78

5) Standard iron solution, Fe2+, 1 mg/ml. 3.516 g of Maura salt is transferred to a 0.5 l measuring flask, salt is dissolved in distilled water, 2 ml of concentrated sulphuric acid is added and the distilled water is brought to the mark. The working solution with a concentration of 10 mg/ml Fe is prepared by diluting the main one 100 times. 6) Trilon B solution at a concentration of 0.1 mol/l. 7) Hydroxylamine hydroxylamine hydrochloric acid, 10% solution. 8) Ammonia, 1:1. 4.3.7 Lead determination

The method is based on the interaction of lead with definylthyocarbazone (dithizone) in carbon tetrachloride with the formation of a complex compound colored red. The optical density of the complex compound solution is determined at λ = 520 nm. The linear dependence between the optical density of the solution and the lead concentration remains within the range from 2 to 30 µg/l Pb. The method is designed for surface water analysis. By this method it is possible to determine the lead content from 2 to 30 µg/l. Process of determination. 0.5 liters of acidified water is placed in a flask on 1 liter, add 0.5 g of ammonium persulfate and, after inserting a plug – refrigerator into the flask neck, boil over low heat for 20 minutes, and then the sample is cooled under a stream of water. Approximately 15 ml of purified NH4OH is added to the cooled sample and the acidity of the medium is brought to pH = 2 by drops (control by universal indicator paper). The sample is transferred to a separating funnel of 1 litre and copper is extracted by 10 ml of dithizone solution in CCl4 by shaking it for 2 min. After separation of water and organic phases, the extract is drained and discarded. Copper extraction is repeated until the organic solvent layer stops coloring (usually 1-2 times). In addition to the sample purified of copper, 5-6 drops of phenolic red indicator are added and the sample is neutralized by drops of purified NH4OH until orange (pH = 6.8 – 7.3). Then 5 ml of potassium hexacyanoferrate (II) solution, 5 ml of hydroxylamine solution of hydrochloric acid, 5 ml of sodium citric acid solution are added and the 79

contents of the funnel are shaken for 30 seconds. Then, the purified NH4OH is added in drops until raspberry coloring and an excess of 5 drops (pH = 8.0 – 8.5). Then, 10 ml of dithizone solution is added to CCl4 and lead is extracted by shaking the mixture for 2 min. After separation of the mixture, a colored layer of organic solvent is drained into the ditch by filtering it through a funnel with a thin layer of cotton wool. Immediately measure the optical density of the solution on a photoelectrocolorimeter (λ = 520 nm, green optical filter) in a cell with a layer thickness of 2 cm against tetrachloric carbon. Lead content is found by the graduation curve. Plotting a graduation curve. 500 ml of twice distilled water are poured into four flasks per 1 liter, acidified by 10 ml of HCl, 1.0; 5.0; 10.0; 15.0 ml of lead working solution are added, which corresponds to 2.0; 10.0; 20.0; 30.0 µg/l of lead, and 0.5 g of ammonium persulfate are added to the neck of the flask and refrigerators are inserted. Then boil at low heat for 20 minutes. Next, repeat all the operations as described above (see "Proceess of determination"). The optical density of the extracts is measured against the carbon tetrachloride. A graduation curve is drawn by plotting the lead concentration on the abscissa axis (in µg/l) and the optical density on the ordinate axis. The use of a constant density dithizone solution in CCl4 eliminates the need for frequent reproduction of the graduation curve. In this case, the construction of the graduation curve should be repeated after a new batch of reagents has been prepared. Reagents: 1) Double distilled water (bidistillate). 2) Ammonia NH4OH, "puriss. spec.", solution 6 mol/l. 3) Tetrachloric carbon CCl4, "puriss". 4) Hydrochloric acid solution HCl, "puriss" (1:1). To 500 ml of twice distilled water, 500 ml of concentrated HCl is added. 5) Standard lead nitrate solutions Pb(NO3)2, "puriss". a) Basic standard solution, 100 µg/ml. A sample of 0.1600 g Pb(NO3)2, "puriss", dried to a constant mass at 100-105 °C, dissolve in a measuring flask for 1 liter in a small amount of water twice distilled, acidify by 2 ml of purified concentrated HNO3 and bring the bidistillate to the mark. The solution is stable throughout a year. It is stored in a vial with a lapped cap at room temperature; 80

b) Working standard solution, 1 µg/l. 1 ml of the basic standard solution is diluted twice with distilled water in a 100 ml measuring flask. The solution is prepared on the day of determination. 6) Potassium hexacyanoferrate (II) solution K4Fe(CN)6 . 3H2O, "puriss". 1 g salt is dissolved twice with distilled water in a 50 ml measuring flask. Freshly prepared solution should be used. 7) Hydroxylamine solution of hydroxylamine hydrochloric NH4OH . HC1, "puriss. spec." or "puriss" 10 g of salt is dissolved twice with distilled water in a 500 ml measuring flask. 8) Dithizone solutions in tetrachloric carbon: a) Basic 0.01 % solution. 0.05 g of purified dithizone is dissolved in 500 ml of purified carbon tetrachloride. The solution is stored in a dark vial at a temperature of 3-5 °C for several months; b) Working 0.001 % solution. 25 ml of the main solution is diluted with carbon tetrachloride, and the volume is brought up to 250 ml. The optical density is measured on a photoelectric-colorimeter (λ = 520 nm, green filter, cuvette with a layer thickness of 2 cm) opposite the pure CCl4, setting the optical density to 0.350. The solution is prepared on the day of determination and stored in a dark vial. 9) Sodium citric sodium solution Na2C6H5O7 ∙ 5,5H2O, "puriss. spec." or "puriss." 100 g of salt is dissolved in a 500 ml measuring flask. 10) Phenolic red solution, 0.1%. 0.1 g of indicator is dissolved in 100 ml of 20% alcohol-rectificate solution. 4.3.8 Determination of cadmium  

The method is based on the interaction of cadmium and dithizone with the formation of a raspberry-pink complex, extracted by carbon tetrachloride:

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The optical density of the extract is determined at λ = 540 nm. The linear dependence between the optical density of solutions and the concentration of cadmium remains within the range of 1 to 20 µg/l. The duration of the unit sample determination is about 1.5 hours. Process of determination. 0.5 liters of analyzed water, acidified with 10 ml of HC1 0.1 mmol/l eq., placed in a conical flask per 1 liter, add 0.5 g of ammonium persulfate, insert a refrigerator plug into the flask neck, heat to boiling and boil for 20-25 minutes. The sample is cooled and transferred to a separating funnel with a capacity of 1 liter, 2 ml of hydroxylimine salt solution, 1 ml of sodium lemonate solution, 2 ml of dimethyl glyoxime solution and neutralized by methyl red ammonia solution to yellow indicator. Then add another 3 ml of ammonia solution, 5 ml of 0.05% dithizone solution in CCl4 and shake the mixture for 2 min. After separation of CCl4, it is poured into the second separating funnel, and 5 ml of 0.05% dithizone solution is added again to the aqueous solution and the extraction is repeated for 2 minutes. This operation is repeated until the color of the newly added portion of the dithizone solution stops changing when shaken with the solution under analysis. The combined extracts are washed 2 times with small portions of bidistillate and removed from them with cadmium, treating 2 times with portions of 4 ml HC1 0.1 mmol/l eq., strongly shaking the mixture for 3 min. At each treatment the CCl4 layer is then discarded. To the hydrochloric acid water solution remaining in the separating funnel, 10 ml of purified CCl4 is added and the mixture is shaken for 2 min. After separation CCl4 is discarded. Add 5 ml of sodium hydroxide solution to the aqueous solution and extract 0.005% cadmium of dithizone solution, adding the last portion of 2 ml and shaking the mixture for 2 min. Extraction is continued until the organic solvent layer stops staining pink after shaking with the sample solution. All portions of the extract are placed in a separating funnel with a capacity of 250 ml, pour 10 ml of bidistillate and shake the mixture for 2 minutes. After the mixture has been stratified, the extract is transferred to a graduated tube with a lapped tube, brought to 25 ml by purified CCl4 and mixed. The optical density of the extract is measured relative to CCl4 on a spectrophotometer at λ = 540 nm or photoelectrocolorimeter (green filter) in a ditch with a layer thickness of 3 cm. The cadmium content in µg/l is found by the calibration curve. 82

Building a graduation curve. 0.0; 0.5; 1.0; 2.0; 5.0 and 10.0 ml of standard working solution of cadmium are placed in conical flasks per 1 liter, diluted with 500 ml of bidistillate. Concentration of the obtainned solutions, respectively, is equal: 0.0; 1; 2; 4; 10; 20 µg/l cadmium. Then, 10 ml of HCl solution is added to the solution with 6 mmol/l eq. and cadmium is determined as described above (see "Process of determination"). The optical density of the extracts is measured relative to carbon tetrachloride. A calibration curve is drawn by plotting the cadmium concentration on the abscissa axis (in µg/l), and the optical density on the ordinate axis. Reagents: 1) Dithizone solutions: a) 0.05% (by volume) solution. A weight of 0.050 g of purified dithizone is dissolved in 100 ml of purified CCl4. The solution is filtered through a paper filter and stored in a vial of dark glass at 3-5 °C for several months; b) 0.005% solution is prepared by dilution of 0.05% solution 10 times per day of determination. Cleaning of the dithizone, see p. 51 p. 2. 2) Sodium hydroxide solution, "puriss". 25 g NaOH is dissolved in 75 ml bidistillate. The solution is tested for purity by diluting it with an equal volume of biodistillate and shaking it with the dithizone solution in CCl4. The layer of CCl4 (if yellow, sodium hydroxide is not suitable). 3) Tetrachloric carbon, CCl4, "puriss", purified of decay products. Prepare a 1% solution of hydroxylamine hydrochloride and neutralize it with ammonia by methyl red. Then, for every 100 ml of CCl4, 10 ml of neutralized hydroxylamine salt solution is added and shaken in a separating funnel. This operation is repeated 1-2 times and the reagent purified in this way is distilled. 4) Hydroxylamine hydrochloride solution, "puriss". Suspension of 1 g NН2ОН . НСl is dissolved in 100 ml of bidistillate, 2-3 drops of methyl red solution are added to the solution and neutralized with ammonia before yellow staining of the solution. The solution is purified by extraction by 0.05% dithizone solution in CCl4, in portions of 5-10 ml until the change of dithizone color stops. Duration of each extraction is 1 min. After that, the remains of dithizone are extracted 83

from the solution by extraction by tetrachloric carbon in portions of 10 ml until the next portion of CCl4 becomes colorless. The duration of each extraction is 1 min. 5) Sodium lemonade solution, "puriss". Suspension 50 g Nа3С6Н5О7 ∙ 5.5 Н2О is dissolved in 50 ml of bidistillate, leached with 25% ammonia to pH = 8-9 on a universal indicator paper and purified in the separating funnel from trace elements by dithizone solution as well as by hydroxylamine hydrochloride solution. 6) Hydrochloric acid solutions: a) Distilled hydrochloric acid solution, concentration 6.0 mmol/l equivalent. Prepared from concentrated HCl by its distillation (see p. ... p. 7); b) Hydrochloric acid solution, concentrations of 0.01 mmol/l equivalent. Prepared by dilution of 0.67 ml of hydrogenated hydrochloric acid with twice distilled water to 400 ml. 7) Ammonia solution, 12.5%. Pour a concentrated ammonia solution (0.5 l) onto the bottom of the desiccator with a diameter of the upper part of the body of 250 mm, place a cup with twice distilled water (0.5 l) on the net of the desiccator, then close the desiccator with the lid. The ammonia solution formed in the cup is used 24 hours later. 8) Ammonium nanosulphuric (NН4)2S2О8, "puriss. spec.". Cleaning method, see p. 52 p. 12. 9) Methyl red solution. 0.04 g of the reagent is dissolved in 20 ml of 60% ethanol distillation rectificate. 10) Standard solutions of cadmium chloride, "puriss". a) Basic standard solution, 100 µg/ml cadmium. 0.1016 g of СdCl2 ∙ 2.5H2O is dissolved in 10 ml of overturned hydrochloric acid in a 500 ml measuring flask and the volume of the solution is brought to the mark with twice distilled water. The solution is stored for several months at room temperature in a vial with a lapped plug; b) Working standard solution, 1 µg/ml cadmium. 1 ml of the basic standard solution is acidified with 1 ml of distilled hydrochloric acid in a 100 ml measuring flask and the volume of the solution is brought to the mark twice with distilled water. The solution is prepared on the day of determination.

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4.4 Identification of pollutants 4.4.1 Determination of non‐ionic SS (Synthetic Surfactants)

The method is based on the interaction of non-ionic synthetic surfactants (SS) with Nessler's reagent and acidic environment, accompanied by formation of an insoluble complex: 2[RO − (CH2 – O − CH2)X − (CH2 – O − CH2)Y − CH2 − CH2OH] + XК2HgI4 – 2[RO − (CH2 – O − CH2)X − (CH2 – O − CH2)Y − CH2 − CH2OH]+ ∙ X[HgI4]Process of determination. Pour 50 ml of the sample under examination into a 100 ml cup and add 0.6 ml of concentrated nitric acid. The mixture is stirred and added with 1 ml of Nessler reagent, stirred again and left for 1 hour. The optical density of the solutions is measured on a photo-colorimeter-nephelmeter with a green filter in cells with a layer thickness of 3 cm against distilled water. The content of non-ionic SS is determined by the graduation curve. Building a graduation curve. Pour 0.0; 5.0; 10.0; 30.0; 50.0; 100.0 ml of standard working solution into measuring flasks per 100 ml and bring the volume of solution to the mark with distilled water. Concentrations of these solutions, respectively, are equal: 0; 7.5; 15; 45; 75; 150 µg of non-ionogenic SS in 50 ml. From each flask, 50 ml of the solution is taken out with a pipette and transferred into 100 ml glasses, 0.6 ml of concentrated nitric acid is added. The mixture in each cup is stirred, 1 ml of Nessler reagent is added, stirred again and after 1 hour the optical density of solutions is measured on a photoelectric colorimeter with a green filter with a layer thickness of 3 cm against distilled water. The optical density of the solution without the working standard solution is subtracted from the measurement results. If the water samples to be tested require pre-treatment (anionic transmission, air purging of the acidified sample, protein deposition), a series of standard solutions should be treated in the same way. Calculation: The content of ionogenic SS (Cx) in µg/l is found by the formula: Сх = C 1000 , V 85

where: C is the concentration of non-ionic SS found by the grading curve, µg in the sample; V is the sample volume, ml. Reagents: 1) Nessler reagent, "p.a.". 2) Nitric acid (HNO3), chemically pure, concentrated. 3) Standard solutions for non-ionic SS: a) Basic standard solution, 3 g/l. 3 g of solvassol 0 (lauryl alcohol with 20 molecules of ethylene oxide per 1 molecule of alcohol) is diluted in a measuring flask per 1 liter of distilled water and the volume is brought to the mark; b) Working standard solution, 3 mg/l. 1 ml of the main solution shall be diluted with distilled water in a measuring flask of 1 l. The working solution is prepared immediately before the analysis. 4.4.2 Determination of phenols

Determination of the total content of volatile phenols using dimethylaminoantipyrine (amidopirin). The method is based on the interaction of phenols with dimethylaminoantipyrine in an alkaline medium (pH = 9.3) in the presence of ammonium persulfate with the formation of an antipyrine dye. The method is designed for the analysis of waters with phenol content less than 50 µg/l. The method is recommended for systematic observation of phenol content in surface waters. Process of determination. 450 ml of distillation is obtained as follows. For distillation of volatile phenols, the volume of samples shall be taken depending on their concentrations in water (Table 6). Table 6 Volumes of water sample and distillation Expected concentration of phenols, µg/l 1-5 5-50 Volume of sample taken for distillation, ml 1000 500* Dispersal volume, ml 800 450 *- To determine the total content of phenols, a sample of 500 ml is used.

86

Copper sulfate solution and concentrated sulfuric acid at the rate of 1 ml for every 100 ml of the sample are added to the water sample placed in the flask of the device (Fig. 5). Pour 10 ml of 0.01n sodium hydroxide solution into the receiving flask and set it so that the bottom end of the refrigerator tube is immersed in the solution. Distillation is performed with moderate heating (vigorous boiling is unacceptable). If the distillation turns out to be acidic, it is neutralized by several drops of 1 mol/l of sodium hydroxide solution on the indicator paper, brought by distilled phenol-free water up to 500 ml, transferred to a separating funnel per 1 liter and 10 ml of buffer solution, 1.5 ml of dimethylaminoantipirin and 15 ml of ammonium persulfate solution are added. The contents of the funnel are stirred after adding each reagent and then left for 45 minutes. Then add 20 ml of the extraction mixture and shake vigorously for 2 minutes. After the separation of the liquid, the extract is separated and filtered through a paper filter. The optical density of the extract is measured on a spectrophotometer at λ = 460 nm or a photoelectric-colorimeter with a blue filter in cells with a layer thickness of 10 mm. It is necessary to ensure that the water sample and the scale of standard solutions have the same pH value (9.3) and temperature. Plotting a graduation curve. 0.0; 1.0; 2.5; 5.0; 10.0; 15.0; 25.0 ml of the working standard solution containing 1 mg/l phenol is poured into measuring flasks per 500 ml and the volume is brought to the mark with distilled water. The obtained solutions with concentration of 0; 2; 5; 10; 20; 30; 50 µg/l of phenol are treated in the same way as the samples (see "Process of determination"). The optical density is measured against the extraction mixture. A graduation curve is drawn by plotting the optical density on the ordinate axis and the concentraFigure 5. Grinding device for distillation of volatile phenols with tion of phenols in µg/l on the abwater vapor scissa axis. 87

Calculation: The content of Cx phenols in µg/l is found by the formula:

Cx = s ∙ n , where: Cx is the concentration of phenols found according to the calibration curve, µg/l of phenols, n is the degree of dilution of the sample under study. Reagents: All reagents are prepared on distilled water that does not contain phenol or free chlorine. 1) Phenol-free water. Distilled water is double distilled by adding potassium permanganate and sodium hydroxide solution a second time to the distillation flask. 2) The solution of dimethylaminoantipirin (in powder) is dissolved in distilled water in a 100 ml measuring flask and the volume is brought to the mark. Store the solution at a temperature of 3-5 °C. Suitable for use 3-5 days. 3) Ammonium persulfate (NH4)2S2O8, "puriss" or "p.a." 50 g ammonium persulfate solution is dissolved in 200 ml of distilled water in a 250 ml measuring flask, neutralized with a concentrated ammonia solution on litmus paper, the volume is brought to 250 ml and filtered. The solution is suitable for use within 30 days. 4) Buffer solution, pH = 9.3. A weight of 50 g of ammonium chloride, "puriss", is dissolved in 900 ml of distilled water, adding 40 ml of concentrated ammonia solution, and the volume is brought by distilled water to 1 l. 5) Extraction mixture. 100 ml of chloroform, "puriss" or "p.a." is mixed with 200 ml of isoamyl alcohol "puriss". 6) Solution of copper sulfate CuSO4 . 5H2O, "puriss". The weight of 100 g of copper sulfate is dissolved in distilled water and the volume of the solution in the measuring flask is increased to 1 liter. 7) Sulphuric acid H2SO4, "puriss", concentrated (density 1.84). 8) Sodium hydroxide solution. Sodium hydroxide sample weighing 4g is dissolved with distilled water in a 100 ml measuring flask and the volume is brought to the mark. 9) Sodium hydroxide solution, 0.05 mol/l, "puriss". 2 g of sodium hydroxide sample is dissolved with distilled water and the volume is brought up to 1 liter. 88

10) Basic standard solution of phenol, 10 mg/ml. 10 g sample freshly prepared at 181 °C phenol is dissolved with distilled water in a 1 liter measuring flask and the volume is brought up to the mark. a) 1st working standard solution of phenol, 100 µg/ml. 5 ml of the basic standard solution is dissolved with distilled water in a measuring flask and brought up to 500 ml. Prepared on the day of analysis. b) 2nd working standard solution of phenol, 1 µg/ml. Dilute 5 ml of the 1st working standard phenol solution with distilled water in a measuring flask up to 500 ml. The solution is prepared immediately before use. 4.4.3 Determination of petroleum products

Determination of oil products by column chromatography with infrared spectrophotometric endings. The method is based on the separation of oil products from water by extraction of carbon tetrarchloride, chromatographic separation of oil products from compounds of other classes in the column filled with aluminum oxide, and quantitative determination of the intensity of absorption of C-H bonds of methylene (-CH2-) and methyl (-CH3-) groups in the infrared region of the spectrum (2700-3100 cm-1). The linear dependence between the optical density of solutions and the concentration of oil products remains within the range from 0 to 1 mg/sample. The method most fully reflects the total content of oil products and is designed for the analysis of waters with their content from 0.05 to 0.1 mg/l and higher. Process of determination. At the sampling site or in the laboratory a water sample of 2 liters is placed in a bottle with a lapped cap with a crane or a separating funnel, 25 ml of carbon tetrachloride are added, with which first the walls of the bottle with the sample are rinsed, and the mixture is shaken several times manually, opening the cap for the release of solvent vapors. The sample is then placed in a shaker and extracted for 30 minutes. The extraction can be done by intensively mixing the mixture with a glass mechanical stirrer driven by an electric motor at a speed of about 2000 rpm. The bottle is turned upside down, fixed in a tripod and left for 15-20 minutes until the emulsion is completely layered. A layer of carbon tetrachloride is poured into a conical flask with a lapped plug. Add 5 g of anhydrous sodium sulfate to the extract and dry it for 30 minutes. 89

Transmission

Dehydrated extract is poured into another flask with a lapped plug, preventing sodium sulfate from entering it. The latter is rinsed with two portions (2 ml each) of carbon tetrachloride, which is added to the extract. The extract is mixed and passed through the aluminium oxide column at a rate of 0.3 ml/min. Make sure that the CCl4 level in the column does not fall below the aluminium oxide layer. The column should be covered with a watch glass or cap to prevent hydrocarbons from escaping. The eluate is collected in a measuring cylinder, and the first 4 ml of eluate is passed through the column again after passing the sample, rinsing the flask in which the extract was placed. After that, the volume of eluate in the measuring cylinder is brought up to 30 ml with carbon tetrachloride. The intensity of absorption of the resulting solution is measured on an infrared spectrophotometer in the range of wavelengths 2700-3100 cm-1 in cells with a layer thickness of 5 cm. One cell is filled with tetrachloric carbon, previously passed through the column with aluminum oxide (comparison cell), the other – with the examined solution (measurement cell). Optical density is calculated using the baseline method. The base line is drawn as a tangent (AB) to the base of the two peaks corresponding to the symmetrical and asymmetrical valence oscillations of -H2and -CH3- groups, as shown in Figure 6.

Wavelength  sm-1 Figure 6. Measurement of absorption intensity: AB – base line; I0 – intensity of incident radiation; I – intensity of radiation passing through the solution.

90

Optical density is calculated by the formula: Е = lg

J0 , J

where: J0 is the intensity of incident radiation; J is the intensity of the radiation passed through the solution, and J0 and J correspond to the lengths of the sections of the se and oe; c is the point of intersection of the base line of the perpendicular passing through the maximum absorption of asymmetric valence oscillations (ν = 2926 cm-1) of groups -CH2- (point d) to the lines of the left (line RK) and 100% transmission (line AB). The content of oil products is found by the graduation curve. Building a graduation curve. 0; 6.6; 13.1; 19.7; 25.0 ml of working standard solution of artificial mixture of hydrocarbons (n-hexadecane-isooctane-benzene) is poured into measuring flasks of 50 ml capacity and the volume is brought to the mark with tetrachloric carbon. Concentrations of these solutions, respectively, are equal: 0; 0.005; 0.010; 0.015; 0.019 mg/ml. Measure the absorption rate of solutions in cells with a layer thickness of 50 mm and calculate the optical density as described above. A graduation curve is drawn by plotting on the abscissa axis the content of oil products in mg/ml (concentration of standard solutions in mg/ml multiplied by the volume of eluate – 30 ml), on the ordinate axis – the optical density. Calculation: The oil product content of Cx in µg/l is found by the formula: Сх = C 1000 , V where: C is the petroleum product content found from the graduation curve, mg/sample; V is the sample volume, ml. Preparation of chromatographic column. 6-g sample of anhydrous aluminum oxide is placed in a glass of 50 ml, pour 10-15 ml of CCl4, the mixture is mixed and transferred to a chromatographic column, the crane is kept open. Several times the glass is rinsed with 91

tetrachloric carbon (5 ml each), which is transferred to the chromatograph column. A piece of glass wool is placed on top of the Al2O3 to prevent agitation. When the last portion of CCl4 lowers to the surface of the aluminium oxide, the edges of the column are closed (30 ml of carbon tetrachloride flowing through the column filled with aluminium oxide is used to fill the comparison cell). The column prepared in this way is used 1 time. Reagents: 1) Aluminum oxide A12O3, anhydrous, "p.a.". The sorbent is sifted through a sieve with a hole size of 0.1 mm and cleaned by treatment with carbon tetrachloride in the Soxhlet apparatus for 14 hours. Before use, the reagent is incinerated at 600°C for seven days. 2) Tetrachloric carbon CCI4, "puriss". Check the purity of each batch for absorption at 2700-3100 cm-1. For comparison, tetrachloric carbon pre-dried with anhydrous sodium sulfate, distilled at t = 76.7 °C and passed through a column filled with incinerated A12O3. In the presence of impurities all batch of CCl4 is cleaned. For this purpose, add about 10 g of anhydrous sodium sulphate to 1 liter of CCl4, decant, distill, selecting the fraction with t = 76.7-76.8 °C and pass through the column (d = 5 cm, l = 50 cm), filled with incinerated A12O3 (250 g). 3) Sodium sulfate (Na2SO4), anhydrous, "puriss". Before use, dry at 120 °C for 8 hours. 4) Isooctane C8H10, "puriss". 5) Hexadecane C16H34, "puriss". 6) Benzene C6H6, "puriss". 7) Standard solutions of artificial mixture of hydrocarbons hexadecane-isooctane-benzene: a) Basic standard solution, 7.6 mg/ml. 3.75 ml n-hexadecane, 3.76 ml isooctane and 2.50 ml benzene are taken with a pipette. The mixture is mixed, 1 ml is taken and dissolved in carbon tetrachloride in a 100 ml measuring flask; b) Working standard solution 0.038 mg/ml. 0.5 ml of the main solution is diluted with carbon tetrachloride in a 100 ml measuring flask. 8) Filter paper. 9) Glass wool. Wool is cleaned by washing with carbon tetrarchloride. 92

4.4.4 Spectrophotometric determination of reducing sugars in fresh water

The method is based on the reaction of reduction of Сu2+ ions by sugars in an alkaline environment. The degree of oxidation of sugars by divalent copper in an alkaline environment can be different, depending on the conditions of the reaction. Therefore, the methods of quantitative determination of sugars, based on this reaction, provide a comparison of the amounts of copper oxide (1), formed during processing of the studied and standard solutions in exactly the same conditions. As the reaction is influenced by various mineral impurities, the preparation of natural water samples should include the removal of minerals with the help of ionites. The minimum sugar content determined by this method is about 5 µg/l in the sample. The accuracy of the determination is 15-20%. Process of determination. 100 ml of the examined water is passed through the chromatographic columns with ionites KU-2 and AN-22 at a rate of 10-12 drops per minute. Having discarded the first 50 ml of filtrate, the next 30 ml is taken for determination and, having evaporated them dry in a water bath, the dry residue is transferred to a centrifuge tube of 1 ml of distilled water and 1 ml of alkaline copper reagent. The reaction of divalent copper sugar recovery is performed by heating the mixture in boiling water for exactly 5 minutes (by stopwatch), after which the contents of the tubes are quickly cooled with cold water. Up to 10 ml of bidistillate is added to the tube, the solution is centrifuged, the new portion of bidistillate (10 ml) is drained, and centrifuged again. This operation is repeated three times. After removing the last portion of rinsing water, oxidize Cu2O with a mixture of concentrated HCl and HNO3 (2 drops of HCl and 1 drop of HNO3). The contents of the tubes are evaporated almost dry (the remains of chlorine are removed by an air current) and transferred to a separating funnel of 5 ml of distilled water, purified from traces of copper ions by cationization. 1 ml of sodium diethyldithiocarbamate solution and 5 ml of mixture of CCl4 with isobutyl alcohol are added to the funnel. The mixture is shaken for 2 min. And after layering, the layer of organic solvent is separated. Thin water emulsion is destroyed by adding 0.5 ml of isobutyl alcohol to the mixture, after which the optical density of the solution is measured at a wavelength of 433 mmc. 93

The amount of sugars is determined by a graduation curve based on the results of extinction measurements of the processed standard sugar solutions (e.g. glucose) in a similar way. The linear dependence of the extinction of copper diethyl dithiocarbamate solution (in a mixture of butyl or isobutyl alcohol and CCl4) on the reducing sugar content in the sample remains within the range of 0-30 µg. Reagents: 1) KU-2 cation exchanger. Cationite fraction with particle size 0.25-0.5 mm is shaken several times with distilled water and separated from smaller particles by decantation. Then, the cationite loaded into the columns is treated 5-6 times with HCl solution of 1 mol/l eq concentration, distilled water and ammonia solution of 2 mol/l eq concentration; transferring the resin into hydrogen form (washing with HCl solution of 1 mol/l eq. concentration), washed from excess acid with distilled water. 2) Anionite AN-22. Having isolated the anionite fraction (diameter 0.25-0.5 mm) in the above described way, "train" by successsive passing through it: 100 ml of NaOH solution with concentration of 1 mol/l eq., 0.5 l of distilled water and 100 ml of HC1 solution with concentration of 1 mol/l eq. This operation is repeated 5-6 times. Then anionite is transferred to hydroxyl form (NaOH concentration of 1 mol/l eq.) and washed from excess alkali with distilled water. 3) Alkaline copper reagent. The reagent is prepared from two solutions: a) 12.5 g of anhydrous sodium carbonate and 12.5 g of sodium carbonate and 12.5 g of sodium segmental salt are dissolved in 300 ml of distilled water containing 20 ml of NaOH solution with concentration of 1 mol/l eq; segmental salt – double salt of tartaric acid КООС (СНОН)2СООNа. b) 3 g CuSO4 ∙ 5H2O is dissolved in 50 ml of distilled water. Before using the solution "b" is poured into the solution "a", and the volume of the mixture is brought up to 500 ml with water. All components of the reagent should not contain impurities of organic substances capable of restoring Cu2+ in an alkaline environment. The suitability of the reagent is established by conducting an idle experiment. It is desirable to prepare the reagent before use (daily). 94

4) Sodium diethyldithiocarbamate solution. 1 g of the reagent is dissolved in 20 ml of distilled water. The solution is placed in a separating funnel with a capacity of 50-100 ml, pour 5-6 ml of CCl4 and extract impurities of heavy metals. The purified solution is filtered through a dense paper filter. It should be remembered that the solution of sodium diethyldithiocarbamate is unstable and should be prepared before use. 5) Mixture of CCl4 and isobutyl alcohol for extraction. The mixture consists of two volumes of CCl4 and one volume of isobutyl alcohol. 6) Isobutyl alcohol.

95

5 WORKS ON APPLIED HYDROCHEMISTRY     5.1 Determination of water stability with respect to concrete

Stability is one of the main technological indicators of natural water quality. It is characterized by the ratio of the content of different forms of carbon dioxide. Water is considered to be stable if it does not dissolve concrete as a result of action of aggressive carbon dioxide and carbonates are not deposited on it because of water saturation with calcium carbonate (GOST 3313-46). Stability is determined by basic and auxiliary methods. The main (carbonate) method is to compare the total alkalinity of water before and after contact with chemically pure calcium carbonate. This water property is characterized by the stability index C0, which is the ratio of the initial alkalinity of the water AWorigin to the alkalinity corresponding to the state of saturation of the water with calcium carbonate AWsatur. Water is considered stable at С0 = 1. If AWsatur > AWorigin, i.e. C0 > 1, the water is unstable. When it passes through the pipes, the alkalinity decreases due to the release of excess СаСО3. If the water contains free CO2, exceeding the equilibrium one, the AWsatur < AWorigin, and C0 < 1. Such water is considered to be aggressive with respect to concrete. An auxiliary method of stability determination is to compare the pH values of the raw water (pHorigin) and the pH value of the water saturated with СаСО3 (pHsatur). The stability index in this method (Cv) is found by the formula: Cv = pHorigin / pHsatur Water stability is also characterized by the stability index: I = pHorigin – pHsatur 96

At I = 0 water is stable, at I > 0 it is unstable, at I < 0 it is aggressive. Sodium hydroxide, lime, filtration through filters with carbonate loading are used to stabilize aggressive natural waters. Unstable water is acidified or subjected to recarbonization. Process of determination. Measure with a pipette 100 ml of the examined water and determine the total alkalinity in the sample. Take a bottle of 500 ml, measure 400 ml of water and put 15 g of powdered СаСО3 in it. Cover the vial with a rubber plug and place in the shaking device. Shake the sample for an hour (with an oxidation of more than 8 mg/l – 2 hours). Replace the rubber plug with another one – with a chlorocalcium tube containing sodium nitrate and a glass tube, the lower end of which does not reach the bottom of the bottle by 3 cm. The upper end of this tube should be hermetically connected with a rubber hose to the funnel having a porous glass plate. The funnel is freely placed in a conical flask, located 70-75 cm below the bottle of test water. To make water get into the flask, suck off air from the funnel with a vacuum pump. Use a pipette to measure 100 ml of filtrate and determine the alkalinity of the methylorange. Calculation: Calculate the stability index C0 according to the above formula. Reagents: 1. Calcium carbonate, powder "puriss". 2. Methylorange solution, 1%  

5.2 Determination of removable and residual hardness

The determination is based on comparing the values of carbonate hardness in the water sample before and after boiling. In this case, calcium and magnesium hydrocarbons are converted into carbonates, and the volume of hydrochloric acid used for titration of boiled sample characterizes the value of residual hardness. Removable hardness is found by the difference between carbonate and residual hardness. Process of determination. In a conical flask of 250 ml, measure 100 ml of the test water with a pipette. Titrate 0.1 n with hydrochloric acid in the presence of 2-3 drops of methylorange before the yellow color changes to pink-orange. The volume of acid used for titration should be recorded. 97

Rinse the flask with distilled water and measure 100 ml of water again. Use a heat-resistant glass pencil to mark the water level in the flask. Close the flask with a funnel and boil for 1 hour. When boiling, the СаСО3 residue is formed. As the water evaporates, carefully pour the distilled water into the flask to the mark. After cooling, filter the boiled water through a dry filter into a clean dry flask, rinse the filter 2-3 times with a small volume of distilled water (combine the rinse water with the filtered sample). Apply 2-3 drops of methylorange and titrate with hydrochloric acid until pink and orange. This volume of acid should also be recorded. Calculation. The remaining hardness is calculated using the formula: Hres =

V2  N 1000 , V3

where: Hres is the residual water hardness, mmol/l eq.; V2 is the volume of HCl working solution for water titration after boiling, ml; N is the concentration of HCl, mmol/l eq. Removing hardness is calculated by the formula: Hrem =

V1  V2   N 1000 , V3

where: Hrem is the removing water hardness, mmol/l eq.; V1 is the volume of HCl working solution for titration of water sample before boiling, ml; V2 is the volume of HCl working solution for titration of water sample after boiling, ml; N is the concentration of HCl, mmol/l eq.; V3 is the volume of water sample, ml. Reagents: 1. Hydrochloric acid solution, 0.10 mmol/l eq. 2. Methylorange solution, 1%

98

5.3 Determination of carbonate hardness

The method is based on the binding of НСО 3 and СО 32  ions by acid in the presence of methylorange. In waters in which НСО 3 < < (Са2+ + Мg2+), carbonate hardness will correspond to total alkalinity. Process of determination. Measure 100 ml of the test water into a 250 ml conical flask with a pipette. Pipette 2-3 drops of a methylorange solution and titrate the sample with 0.1 N HC1 solution until the yellow color turns to orange. Calculation.

H car 

V1  N  1000 , V2

where: Hcar is the carbonate hardness, mol/l eq .; V1 is the volume of hydrochloric acid for titration of a water sample, ml; N is the concentration of hydrochloric acid, mol/l eq. (or 0.1 n); V2 is the sample volume of water, ml. Reagents: 1. HCl, 0.1 N solution. 2. A solution of methylorange, 0.1% 5.4 Test water softening with the lime‐sodium method

Test water softening is carried out to determine the optimum reagent dosage and control the process. In the natural water to be softened, carbonate and non-carbonate hardness, free carbon dioxide and magnesium ions content are determined in advance. These data are needed to calculate the dose of lime and soda. Process of determination. In separate samples of the natural water under study, the total carbonate and non-carbonate hardness, the content of free carbon dioxide and the concentration of Ca2+ ions should be determined. The content of Mg2+ ions can be found by the difference between the total hardness and the content of Ca2+ ions (in mol/l eq.). Based on the analysis of the source water, calculate the mass of lime 99

and soda for water softening. Weigh the found mass of lime and soda on a technochemical scale with an accuracy of 0.01 g. Pour 1 liter of softened water into a conical flask of 2 liters, add the necessary mass of lime and soda and shake for 3-5 minutes. Allow the resulting sludge to stand still, then filter it through a dense filter. The first portions of filtrate throw away, and in the following (200 ml) determine the total, carbonate, non-carbonate hardness, the content of free carbon dioxide and the concentration of Ca2 + and Mg2 + ions. An example of calculation. Water analysis has found: non-carbonate hardness of water is 3.0 mmol/l eq.; carbonate hardness is 4.5 mmol/l eq.; magnesium hardness is 2.4 mmol/l eq.; CO2 free is 8.0 mg/l. Find the mass of lime for softening water. Dlime = 28 (0.0455 ∙ 8 + 4.5 + 2.4 + 0.2) = 209 mg/l. If softened with quenched lime, the conversion factor is not 28, but 37. Besides, it is necessary to take into account the fact that the calculation is made for 100% lime. The mass of soda for water softening is calculated on the basis of non-carbonate hardness: Dsoda = (3 + 0.2) ∙ 53 mg/l. Calculation is given in terms of anhydrous salt Na2CO3. In our example, the soda dose is equal to Dsoda = (3 + 0.2) ∙ 53 = 169.6 mg/l. Reagents: 1. Na2CO3 (anhydrous salt or Na2CO3 crystallide). 2. Unquenched CaO or quenched lime Ca(OH)2. 3. Reagents for determination of total and carbonate hardness, calcium, magnesium and free CO2. 5.5 Ion‐exchange methods of water softening. Determination of cationite exchange capacity under static conditions by 0.1 N sodium hydroxide solution

Ion-exchange methods of water softening are based on the ability of some minerals, artificially obtained inorganic materials and synthetic polymeric resins of a certain structure to exchange ions Н+, Na+, etc. for ions Са2+, Мg2+ contained in water. Ion exchange materials capable of exchanging cations are called cationites, and ionites exchanging 100

anions are called anion exchangers. Organic ionites are insoluble but limited swelling polymer resins, which include acidic (cationites) or basic (anionic) groups. Water softening occurs when it passes through a layer of cationite containing H+ or Na+ ions associated with acidic groups. The scheme of Na cationic process is as follows: Са2+ + 2NaR  CaR2 + 2Na+ , where R is an insoluble anion of cationite. Ion exchange occurs in an equivalent ratio and is a reversible process. This means that the spent CaR2 cationite can be regenerated by passing through it a solution of sodium chloride (at Na – cationic exchange) or hydrochloric acid (at H – cationic exchange). For example, CaR2 + 2 Na+  Са2+ + 2 NaR. The main characteristic of ionites is the dynamic exchange capacity, which is determined by the number of mole/l equivalent per liter or mole/l equivalent per m3, absorbed by swollen ionite. When water passes through the H- cationic or OH- anionic filters in series, the water is desalted. In hydrochemical practice and at water treatment strong acid cationite of KU-2 brand (universal cationite) is widely used. The active group of this cationite is the SO2OH or SO2ONa sulfogroup. The static method of determining the exchange capacity of ionites is used in standard tests to obtain a comparative characteristic of differrent brands of ionites. It consists in the long-term contact of a certain amount of ionite with an alkali solution (for cationites) or an acid solution (for anionites) of a certain concentration. Usually 0.1 N sodium hydroxide solution is used to determine the exchange capacity of cationites, and 0.1 N sulphuric acid solution is used for anionites. Process of determination. On the analytical scales take a sample of cationite in H-form with known humidity of such mass that it corresponds to 1 g of dry product. Place the sample in a conical flask for 300-500 ml and pour 200 ml of 0.1 N sodium hydroxide solution. Close the flask with a cap and leave for 24 hours, stirring periodically. Then separate the cationite from the solution by filtering through the filter wetted with the resulting solution. Pipette 25 ml of filtrate and titrate with 0.1 N hydrochloric acid solution in the presence of 2 drops of methyl red until yellow color changes to red. 101

Calculation: Ec 

200  N



 8  VHCL  N HCL  1000 , g  100  W 

NaOH

where: Ec is the static cationite exchange capacity, mmol/g equivalent; NNaOH is the concentration of sodium hydroxide, mol/l equivalent (or normal concentration); VHCl is the volume of HC1 for titration, ml; NHCl is the concentration of HC1, mol/l equivalent; g is the cationite weight, g.; W is the cationite humidity, %. The exchange capacity of anionites is determined by 0.1 N sulfuric acid solution. Titrate the filtrate with 0.1 N sodium hydroxide solution. Calculate according to the above formula taking into account the above changes. Reagents: 1. Cationite KU-2. A 200 g weight sample of technical cationite with a grain size of 0.25-0.5 mm is placed in a chemical glass and filled with a saturated solution of sodium chloride (5-fold volume). After 24 hours the solution is drained, washed with distilled water and transferred to a large separating funnel. To convert cationite into H-form it is treated 5 times by not less than 30-fold volume of 5% HCI (cationite is kept in contact with acid for at least 2 hours, mixing periodically). Hydrochloric acid cationite is processed until it disappears in the washing solution of Fe3+ ions (40% sample – with ammonium rhodonium solution). After that, the cationite is washed with distilled water until ionic chloride (silver nitrate sample) disappears in the filtrate. The prepared cationite is dried on filter paper as long as the cationite grains are freely separated from each other. Store it in a vial with a lapped cap. 2. NaON solution with concentration of 0.1 mol/l eq. The exact concentration is determined by HCI concentration of 0.1 mol/l eq., which is prepared from fixanal. 3. HCI solution with a concentration of 0.1 mol/l eq. (prepared from fixanal). 4. Methyl red, 0.2% in ethyl alcohol. 102

5.6 Determining the optimum dose of coagulant for water clarification

The amount of coagulant injected into a certain amount of treated water is called a coagulant dose. It is usually expressed in mole/l equivalent, mg/l, g/m3 or g/m3 equivalents. The coagulant dose corresponding to the best clarification or discoloration of the water is called the optimum. The correct dosage of coagulant affects the effectiveness of coagulation. In case of insufficient amount of coagulant, hydroxide flakes are not enough for complete release of water from colloidal impurities, and in case of excess, flake formation deteriorates. Depending on the conditions, the dosage of aluminium coagulant varies between 0.2-1.0 mol/l eq. (20-100 mg/l), for iron – 0.1-0.5 mol/l eq. Optimal dose of coagulant is determined by trial coagulation of water. Process of determination. Pre-determine the transparency of the source water by font. For this purpose, pour the test water into 5 cylinders with a capacity of 0.5 liters. Each of them should be filled with a pipette for 5 ml with 0.5, 1.0, 1.5, 2.0, 2.5 ml of 5% aluminum sulfate solution, respectively. Thoroughly mix water in cylinders after coagulant administration with glass stirrer for 2 min. Allow the solutions to stand still. After 10 min determine the transparency of water in each cylinder by font. The dosage of coagulant, at which the maximum transparency of water will be achieved, corresponds to the optimal one. The task. 1. Calculate the dose of coagulant injected in mg/l (g/m3) converted to anhydrous salt. 2. Based on the experiment, draw up a graph plotting the water transparency in cm on the axis of ordinates and the coagulant dose in mg/l on the abscissa axis. 3. Using the total hydrolysis equation Al2(SO4)3, knowing the optimal coagulant dose, calculate the alkalinity of water required for normal coagulation. Reagents: 1. Al2(SO4)3 ∙ 18H2O. (55% solution in terms of anhydrous salt).

103

5.7 Determination of residual chlorine in tap water

Various methods are used to disinfect water in order to reduce bacterial contamination. Chemical methods include treatment of water with free chlorine and its oxygen compounds, chloramines – organic and inorganic, ozone, salts of heavy metals (silver, copper, etc.). According to GOST 2874-54, after a 30-minute contact of chlorine with water, the amount of residual chlorine in water should be no more than 0.5 mg/l and no less than 0.3 mg/l at the exit from the treatment facilities and no less than 0.1 mg/l at the most remote points of the water supply facility. Residual chlorine in drinking water at preliminary clarification shall be determined after every hour. Active chlorine in chlorine-containing compounds, residual chlorine in water and chlorine absorption of water are determined by the method of iodometry. Process of determination. In a conical flask of 250 ml, measure with a pipette 100 ml of natural chlorinated or tap water, pour 5 ml of 10% solution of KJ, 5 ml of acetate buffer mixture and 1 ml of 1% starch solution. Titrate the sample with 0.005 mmol/l eq. sodium thiosulphate until the blue color of the solution disappears. Calculation. Х=

V1  N1  E 1000 , V2

where: X is the content of residual chlorine, mg/l; V1 is the volume of Na2S2O3 working solution for water sample titration, ml; N1 is the concentration of Na2S2O3 working solution, mol/l equivalent; V2 is the volume of water under study, ml; E is the equivalent of chlorine (35.45). Reagents: 1. Na2S2O3 solution with concentration of 0.005 mol/l equivalent. 2. KJ, 10% solution (potassium iodide should be cleared of free iodine. Method of purification see the work on the determination of dissolved oxygen). 104

3. Acetate buffer mixture. It is prepared by mixing equal volumes of solutions of СН3СООН and СН3СООNa with concentrations of 1.0 mol/l eq. 4. Starch solution, 1%.

5.8 Determination of the self‐cleaning capacity of natural waters from carbohydrates

A complex of natural hydrological, chemical and biological processes occurring in polluted water bodies and aimed at restoring the original properties and composition of water. Study of the processes of self-purification of natural waters is carried out to obtain quantitative characteristics of the state of the polluted water body, necessary for prediction of the chemical composition and properties of water, establishment of maximum allowable loads of sewage, balance of chemicals, calculation of the removal of chemicals by river runoff and other tasks. Studies are carried out in the pollution zone, where natural hydrochemical and hydrobiological processes are disturbed and the concentration of contaminants in accordance with sanitary or other indicators exceeds the established norms. The sites to be monitored shall be selected on the basis of the analysis of available materials on the characteristics of the water body and sources of pollution and the data of reconnaissance survey, during which the quantity, chemical composition and regime of wastewater discharge, concentration of pollutants, conditions of their release, length of the pollution zone shall be specified. The work is carried out at several sites: one is above the pollution source (background site) and several sites are below it. Self-cleaning capacity (SC, %) of water at a certain section of the water body is calculated by equation: СС =

C0  Ct  100 , C0

where: C0 is the concentration of substance in the initial site, mg/l; 105

Ct is the concentration of substance in the final site of the site after time t, mg/l. Potential capabilities of the reservoir for self-cleaning are determined by such processes as sedimentation, sorption, dilution and decomposition of complex organic substances. Wastewater from food, textile, hydrolysis and other industries discharged into water bodies and watercourses contains, in addition to various contaminants, carbohydrates. The latter consume a large amount of oxygen for their oxidation, which is necessary for the life of natural water bodies. At oxidation of carbohydrates , a hydrocarbon chain of these compounds can be destroyed, and one- and two-base organic acids can be formed. In the conditions of natural reservoirs the decomposition of carbohydrates mainly proceeds due to the processes of biochemical oxidation. The process of carbohydrate decomposition by microorganisms in aerobic conditions is associated with the use of chemical energy, which is released in the reaction: С6Н12О6 + 6О2 = 6СО2 + 6Н2О + 674 cal . Part of this energy is spent on synthetic processes related to the construction of the body of microorganisms. Process of determination. Carbohydrate decomposition is studied by means of laboratory modeling. In 5.0 l bottles, fresh water is poured into the bottles from the watercourse or water body, where the salt of magnesium ammonium phosphate NH4MgPO4 (0.1 g per 1 liter) is added beforehand in order to better trace the processes of ammonification and nitrification. Then, carbohydrate solutions are added so that the initial glucose concentration was equal to 1.0; 5.0; 25.0; and 50.0 mg/l; l – sorboses – 5.0 and 25.0 mg/l; maltose – 5.0 and 25.0 mg/l. After careful mixing, the initial concentration of carbohydrates is determined by spectrophotometric method every day for 20-30 days. Concentrations of nitrite and nitrate ions, ammonium ions, dissolved oxygen in water, as well as chemical oxygen consumption are determined by the methods given in this book.

106

Bottles with solutions are placed in the laboratory, where the air temperature varies from 18 to 25 °C. The results of the experiment are recorded in the table and the obtained data are discussed. Conclusions are made about the time of decomposition of carbohydrates, as well as about slowing down or speeding up of the nitrification processes at a specific concentration of carbohydrates.

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6 ROUNDING AND RECORDING OF CHEMICAL WATER ANALYSIS RESULTS The results of the chemical analysis of natural waters are rounded off according to Table 7. Table 7 Rounding off of the results of water chemical analysis Component Na+ +

K+

Indicator range,mg/l Rounding, mg/l mmole/l eqv.

Ca2+

Mg2+

2

SO 4

range, mg/l

5.0-10.0

10.0-20.0

0,2

0,5

1,0

0,005

0,01

0,02

0,05

1.0-20.0

20.0-50.0

50.0-100

100-200

0.5

1.0

2.0

5.0

0.02

0.05

0.10

0.20

0.5-10.0

10.0-20.0

20.0-50.0

50.0-100

range, mg/l Rounding, mg/l

0.20

0.50

1.0

2.0

mmole/l eqv.

0.02

0.05

0.1

0.2

20-100

100-200

200-500

500-1000

1

2

5

10

range, mg/l Rounding, mg/l range, mg/l mmole/l eqv.

CO2

2.0-5.0

0,1

mmole/l eqv.

Rounding, mg/l Stiffness

0.1-2.0

Rounding, mg/l

mmole/l eqv. Cl-

Concentration limits

0.02

0.05

0.1

0.2

1.0-20.0

20.0-50.0

50-100

100-200

0.5

2

5

10 0.20

0.01

0.05

0.10

0.05-1.00

1.00-2.00

2.00-5.00

Rounding, mmole/l eq.

0.02

0.10

0.20

range, mg/l

1-50

50-100

100-200

200-500

1

2

5

10

Range, mmol/l eqv.

Rounding, mg/l

108

Results of chemical composition of water of any object are recorded in a certain form in the form of tables of the following kind: Table 8 Physical properties and pH values of the X river water (2007) No. Samples.

Place of selection

Smell

Transparency

Color

Taste

Temperature, °С

рН

15

Almaty

odorless

5 cm

colorless

fresh

18

7,60

Note: g is omitted in case of its constancy Table 9 Gas composition and nutrients in the water of the X river, mg/l No. Samples. 15

Selection Date 5.04.07

О2

СО2

H2S NO2-

NO3-

NH4+

Fe

P

Si

Table 10 Content of main ions in the water of X river, mmol/l eq. mg/l No. Samples. 15

2  Cl- Ion RigiSelec- Ca2+ Mg2+ Na+ + K+ HCO 2  CO 2  SO 4 3 3 tion sum, dity, Date mg/l 1/z(C) mol/l 5.04.19

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LITERATURE 1. John M. Melack. Saline Lakes, 2005. – P. 316. 2. H.T. El-Dessouky, H.M. Ettouney. Fundamentals of Salt Water Desalination. ELSEVIER SCIENCE B.V., 2012. – Р. 691. 3. Guidance on chemical analysis of land surface waters (edited by A.D. Semenova). – L.: Hydrometeoizdat, 1997. – 541 p. 4. Unified methods of water quality research. Part 1. Methods of chemical analysis of water. – M.: CMEA, 1977. – 831 p. 5. Reference book on hydrochemistry (edited by A.M. Nikanorova). – L.: Hydrometeoizdat, 1989. – 391 p. 6. GOST 8.505 – 84. Metrological attestation of methods for measuring the content of substances and materials components. 7. Metrological certification of methods for measuring water sample component contents: methodological guidelines (RD 52.24.51-85). – L.: Hydrometeoizdat, 1989. – 80 p. 8. Kudryashov G.M. Safety rules for the works in the laboratory of the surface water and atmosphere chemistry. – L.: Gidrometeoizdat, 1987. – 16 p. 9. Zakharov L.N. Safety technique in the chemical laboratories. – L.: Chemistry, 1985. – 182 p. 10. Nikanorov A.M. Hydrochemistry. – L.: Hydrometeoizdat, 1989. – 351 p. 11. Ibragimova M.A., Romanova S.M. Chemical analysis of natural waters: methodological guide to the special course "Chemistry of natural waters". Part 1. – Alma-Ata: Kazakh University, 1980. – 43 p. 12. Alekseev R.I., Korovin Yu.I. Guidance on calculation and processing of the quantitative analysis results. – M.: Atomizdat, 1972. – 72 p. 13. Doyerfel K. Statistics in analytical chemistry. – M.: Mir, 1989. – 258 p. 14. Chemnitz Y. Mathematical processing of dependent measurement results. – M.: Nedra, 1980. – 190 p. 15. Nalimov V.V. Application of the mathematical statistics for the substance analysis. – M.: Fizmatgiz, 1978. – 432 p. 16. Papazov M.G.; Mogilny S.G. Error theory and the method of the least squares. – M.: Subsoil, 1989. – 304 p. 17. Recommendations for presenting the results of chemical analysis (IUPAC Commission on Analytical Nomenclature (translation). – ZHA, 1971. – Vol. 26, issue 5. – 1021 p. 18. Taube P.R., Baranova A.G. Workshop on water chemistry. – M.: Higher School, 1971. – 128 p. 19. Ibragimova M.A., Romanova S.M., Taranina G.V. Chemical analysis of natural waters. Part 2. – Alma-Ata: Kazakh University, 1988. – 34 p. 20. Zenin A.A., Belousova N.V. Hydrochemical dictionary. – L.: Hydrometeoizdat, 1988. – 239 p. 21. Modern methods of natural water analysis (edited by Lazareva K.G.). – М: AS USSR, 1962. – 203 p.

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22. Romanova S.M. Chemistry of natural waters (lecture course). – Almaty: DOIVA "Brotherhood", 2004. – 198 p. 23. Shaova L.G.; Kaplin, V.T. Self-purification of the natural waters from the carbohydrates (in Russian) // Hydrochemical materials. – L.: Hydrometeoizdat, 1969. – Volume 49. – Р. 166-174. 24. Denisova A.I. Formation of the hydrochemical regime of the Dnieper reservoirs and methods of its forecasting. – Kiev: Naukova Dumka, 1979. – 290 p. 25. Amirgaliev N.A. Artificial water bodies of Northern and Central Kazakhstan (hydrochemistry and water quality). – Almaty: SIC Bastau, 1998. – 191 p. 26. Romanova S.M. Anthropogenic transformation of hydrochemical regime and water quality of Kazakhstan's non-waste water bodies. – Diss... Doctor of Geography (25.00.27 – Land hydrology, water resources, hydrochemistry). – Almaty, 2006. – 583 p. 27. Gorev L.N., Peleshenko V.I. Hydrochemical research methodology. – Kiev: Vishya School, 1985. – 215 p. 28. F.A. Comin and T.G. Northcote. Saline Lakes. 1988. – P. 312. 29. Stuart H. Hurlbert. Saline Lakes V., 1991. – P. 330. 30. John M. Melack , Robert Jellison & David B. Herbse. Saline Lakes, 1999. – Р. 341. 31. Nissenbaum A. Hypersaline brines, 1980. – Vol. 28. – Р. 281. 32. Ronald E. Hester (auth.), J. Braunstein, Gleb Mamantov, G.P. Smith (eds.). Advances in Molten Salt Chemistry. – Volume 1. Springer US., 1971. – Р. 289. 33. John E. Lind Jr. (auth.), J. Braunstein, Gleb Mamantov, G.P. Smith (eds.). Advances in Molten Salt Chemistry. – Volume 2. Springer US., 1973. – Р. 289. 34. Ernie R. Lewis, Stephen E. Schwartz(auth.). Sea Salt Aerosol Production: Mechanisms, Methods, Measurements and Models – A Critical Review. American Geophysical Union, 2004. – Р. 421. 35. O. Braitsch (auth.). Salt Deposits Their Origin and Composition. SpringerVerlag Berlin Heidelberg, 1971. – Р. 310. 36. L.V. Woodcock (auth.), J. Braunstein, Gleb Mamantov, G.P. Smith (eds.). Advances in Molten Salt Chemistry. – Volume 3., 2008, Springer US. – Р. 467. 37. G. Belenitskaya. Salt Systems of the Earth: Distribution, Tectonic and Kinematic History, Salt-Naphthids Interrelations, Discharge Foci, Recycling, 2019. – Р. 698. 38. Hardy, Henry Reginald; Lux, Karl-Heinz; Minkley, Wolfgang; Wallner, Manfred. The mechanical behavior of salt – understanding of THMC processes in salt., 2017. – Р. 468.

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Еducational issue

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MANUAL ON HYDROCHEMISTRY Educational-methodical handbook Editor L. Strautman Typesetting U. Moldasheva Cover design R. Skakov Cover design photos were used from sites www.olahaldor.artstation.com

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