Pollution Of Natural Waters Research Articles

REMOVAL OF Bi(III) IONS BY PHYTIC ACID DERIVATIVES FROM RICE BRAN

Creation of new multifunctional materials based on renewable raw materials is a major direction in recent years. Large-tonnage waste of rice production (husk, straw, bran) of the Far East is a promising raw material base for obtaining such materials. Composition of rice bran includes inositol hexaphosphoric acid and its derivatives (phytin, phosphoinositol) which are capable of chelating polyvalent metal ions. Bismuth (III) is one of natural water pollutants that come from leaching of bismuth-containing minerals and activities of pharmaceutical and perfume industries. The goal of this work is to study removal conditions of bismuth (III) ions from aqueous solutions of a phytic acid derivative obtained from rice bran. It is shown in the work that with a sorbent: solution ratio of 1: 100, bismuth ions are removed from the solution by 89 %. It was found that removal of bismuth cations depends on the initial concentration (3.17–51.90 mg/l) and varies from 13 to 96 %. A comparative analysis also showed that chromium (III) ions are removed from aqueous solutions by a phosphorus-containing product better than bismuth (III) ions. These studies allow us to give recommendations on the choice of materials for treating solutions from heavy metal ions, expanding the range of currently used natural sorbents based on plant materials and solving at the same time an urgent environmental and economic problem - the disposal of rice production wastes.

Mechanism and kinetics of ClO[rad]-mediated degradation of aromatic compounds in aqueous solution: DFT and QSAR studies

The action of ClO is more prominent than HO and Cl in the advanced oxidation degradation of some pollutants. However, studies on the pollutant degradation mechanism and kinetics by ClO are limited. In this study, 43 different kind of aromatic compounds which are important anthropogenic and natural water pollutants were selected as models to investigate their ClO oxidation mechanism and kinetics computationally. The results showed that radical adduct formation (RAF) rather than single electron transfer (SET) reaction was prominent in ClO-initiated reactions of aromatic compounds. In subsequent reactions of the ClO-adduct, the Cl end of the -OCl moiety shifted to the benzene ring, which was the key to hydroxylation and chlorination of aromatic compounds by ClO. The calculated ClO initiated reaction rate constants (kClO) of aromatic compounds were 102–1010 M−1 s−1. ClO was highly reactive to phenolates, anilines and alkoxy/hydroxyl aromatic compounds. Upon the deprotonation of phenol to phenolate, the kClO value increased by 4 orders of magnitude. The kClO values of alkoxybenzenes were higher for compounds with shorter alkyl side chains and more alkoxy substituents. The kClO increased for anilines with longer alkyl side chains. The kClO quantitative structure-activity relationships (QSARs) models were developed to predict the reactivity of ClO to complex aromatic compounds in aquatic systems.

ПІДРУЧНИК «АГРОГІДРОХІМІЯ» (2021 р.) - ВНЕСОК У РЕАЛІЗАЦІЮ ПОЛОЖЕНЬ «НІТРАТНОЇ ДИРЕКТИВИ» 91/676/ЄEC В УКРАЇНІ

The article presents and analyzes the textbook “Agrohydrochemistry” (author V.K. Khilchevsky – professor of the Taras Shevchenko National University of Kyiv), published in 2021. The textbook examines the main problems associated with the growth of the chemicalization of agriculture and the protection of water resources. Due to agriculture, there is a noticeable impact on the quality of natural waters in the world, especially in regions of intensive agriculture, to which Ukraine belongs. Increased concentrations of nutrients and various types of pesticides are found in the waters of small and large rivers, groundwater. Therefore, the issues of studying the main sources of agricultural pollution of natural waters and the processes that contribute to this are relevant. Among the main sources of pollution of natural waters with wastewater, namely industrial, household and agricultural – the latter have a specific character of formation and flow into water bodies. If industrial and domestic wastewater is localized behind the formation and place of discharge into the sewer network, then the formation and supply of chemicals from agricultural land is dispersed throughout the catchment area and natural ways of entering (hydrographic network) into water bodies. The attention of the world community to the impact of agrochemicals on the quality of natural waters is evidenced by the Directive 91/676/EU adopted in the European Union of December 12, 1991 “On the protection of waters from pollution caused by nitrates from agricultural sources” (abbreviated as “Nitrogen Directive”), which in turn is a local manifestation of the integrating directive 2000/60/EC of October 23, 2000 “On the establishment of a framework for Community activities in the field of water policy” (abbreviated WFD – “EU Water Framework Directive”), aimed at achieving a good ecological state of natural waters in the regions river basins. Agrohydrochemistry is a direction in hydrochemistry that studies the effect of agrochemical agents on the chemical composition of natural waters using theoretical methods and the results of experimental studies in watersheds. The textbook, which consists of 9 chapters, gives an idea of the formation of the balance of chemicals in the soil, the use of various types of fertilizers and pesticides, and the possible ways of their entry into water bodies. Methods for calculating the flow of chemicals into water bodies are presented. The theoretical provisions are illustrated by the materials of our own research on the effect of agrochemicals on the chemical composition of river waters in the Dnieper basin. The textbook is designed for students of the specialty “Earth Sciences” of educational programs of the hydrological profile of higher educational institutions..

Reducing the Negative Technogenic Impact of the Mining Enterprise on the Environment through Management of the Water Balance

In terms of anthropogenic impact of mining and processing enterprises, the adjacent territories are contaminated by upstream tailings dams. The contamination is developed by active seepage of liquid waste through the body of the dams. The authors have analyzed water balance at the Kachkanar Mining and Processing Plant tailings dump (Russia, Ural Region). The company develops vanadium-containing titanium-magnetite iron ores with low ore (15%). This, along with high productivity, has determined the formation of a large number of tailings and significant amount of wastewater. The purpose of the studies is to substantiate the need to manage the seepage discharge process by means of enclosing dams to ensure environmentally safe operation of the tailings dump. The research objectives included field measurements of seepage volumes, their evaluation by computational methods and analysis of anthropogenic geochemical load on natural waters. The obtained results show an increase in seepage discharge volume from 41.91 million m3 (in 2017) to 81.44 million m3 (in 2026) as the height of the dams increases. These losses will lead to water shortages in the enterprise’s water recycling system. Calculation of pollutants in wastewater with the exception of natural component showed the leading role of technogenic factor in the content of Ti (up to 84%), V (up to 96%), Co (up to 86%) and Mo (up to 93%). Increasing the volume of seepage discharge will lead to an increase in natural water pollution within the area. Ecologically efficient management of the enterprise’s water balance is ensured by the use of tailings thickening technology and implementation of closed water supply systems.

Estimating soil ammonium adsorption using pedotransfer functions in an irrigation district of the North China Plain

Extensive use of chemical fertilizers in agriculture can induce high concentration of ammonium nitrogen (NH 4 + -N) in soil. Desorption and leaching of NH 4 + -N has led to pollution of natural waters. The adsorption of NH 4 + -N in soil plays an important role in the fate of the NH 4 + -N. Understanding the adsorption characteristics of NH 4 + -N is necessary to ascertain and predict its fate in the soil-water environment, and pedotransfer functions (PTFs) could be a convenient method for quantification of the adsorption parameters. Ammonium nitrogen adsorption capacity, isotherms, and their influencing factors were investigated for various soils in an irrigation district of the North China Plain. Fourteen agricultural soils with three types of texture (silt, silty loam, and sandy loam) were collected from topsoil to perform batch experiments. Silt and silty loam soils had higher NH 4 + -N adsorption capacity than sandy loam soils. Clay and silt contents significantly affected the adsorption capacity of NH 4 + -N in the different soils. The adsorption isotherms of NH 4 + -N in the 14 soils fit well using the Freundlich, Langmuir, and Temkin models. The models’ adsorption parameters were significantly related to soil properties including clay, silt, and organic carbon contents and Fe 2+ and Fe 3+ ion concentrations in the groundwater. The PTFs that relate soil and groundwater properties to soil NH 4 + -N adsorption isotherms were derived using multiple regressions where the coefficients were predicted using the Bayesian method. The PTFs of the three adsorption isotherm models were successfully verified and could be useful tools to help predict NH 4 + -N adsorption at a regional scale in irrigation districts.

Порівняльна оцінка якості питної води окремих населених пунктів Могилів-Подільського району Вінницької області

The work is devoted to the actual problem of environmental safety and quality assessment of various water sources Mohyliv-Podilsky district of Vinnitsa region. It has been carried out hydrochemical analysis and calculated an index of pollution of natural waters, biological testing performed using a battery of test organisms, given recommendations to improve the water quality of the study area.It has been established that the most indicative parameters of pollution of water supply sources are hardness indicators, concentration of cadmium, lead, nitrates. None of the investigated sources have corresponded to the “clean water” indicator. Water samples that as a result of hydro-chemical analysis had been characterized by relatively safe, exhibited chronic toxicity for invertebrates. It has been found that water from a centralized source is characterized by the acute toxicity and leads to changes in living organisms at the cellular level. It is recommended to carry out quarterly water sampling in the indicated sources; minimization of the use of nitrogen fertilizers in settlements, in particular, near water supply sources.

An Enemy of the People

An Enemy of the People

Water protection aggregation systems for cleaning surface waste water from the territories of poultry farms

During the operation of poultry farms a large amount of poultry manure is accumulated. Surface wastewater from landfills for storing poultry manure can become the main source of pollution of natural waters. Thus, one of the most important problems of environmental protection is the development of effective systems for protecting aquatic ecosystems from pollution by waste water generated at landfills for storing poultry manure. The purpose of research was the analysis of water protection systems for treatment of surface wastewater from the territory of poultry farms. The authors of the article consider the problem of protection of water bodies from contamination by surface wastewater from the catchment area of poultry farms. The example of surface wastewater from the catchment area of the poultry farm “Sverdlovskaya” has shown the negative impact on water ecosystems. Our own studies of snow contamination from the catchment area of the poultry farm have shown a high content of not only organic and biogenic substances, but also heavy metals. A biotechnology of wastewater treatment using natural ion-exchange materials, followed by bioregeneration of the latter by higher aquatic vegetation, has been developed. The use of an accumulative phytofilter is an effective method of protecting water ecosystems from contamination by surface wastewater from catchment areas of poultry farms, and the design ensures not only the environmental friendliness of the technology, but also naturally fits into the landscape of the area.

Correction: Goddijn-Murphy, L. and Williamson, B. On Thermal Infrared Remote Sensing of Plastic Pollution in Natural Waters. Remote Sensing, 2019, 11, 2159

The authors wish to make the following corrections to this paper [...]

Tetracycline antibiotics as precursors of dichloroacetamide and other disinfection byproducts during chlorination and chloramination

Pollution of natural water and even source water with pharmaceuticals is problematic worldwide and raises concern about the possibility of disinfection byproduct (DBP) formation during subsequent water treatment. In this study, the formation of DBPs, especially dichloroacetamide (DCAcAm), was investigated during chlorination and chloramination of tetracyclines, which are a class of broad-spectrum antibiotics. DBPs including DCAcAm were formed during chlorination and chloramination of tetracycline (TC). Although the concentrations and theoretical cytotoxicity of the DBPs formed from TC were affected by the contact time, disinfectant dose, and pH, DCAcAm was the main contributor determining the yields and cytotoxicity of the measured DBPs. The DCAcAm yields from four tetracycline antibiotics ranged from 0.43% to 54.26% for chlorination. For chloramination, the DCAcAm yields reached 44.57%, and the nitrogen in DCAcAm mainly came from tetracycline antibiotics rather than chloramines. ClO2 pre-oxidation and UV photolysis decreased DCAcAm formation during chlorination and chloramination of TC. The high yields observed in this study suggest that tetracycline antibiotics are possible precursors of DCAcAm.

TIME-SPACE ASSESSMENT OF WATER QUALITY OF MIASS RIVER

The pollution of natural waters, both sea and fresh, is a crucial issue all over the world. Most of the large and small rivers, streams, and reservoirs almost in every federal district of the Russian Federation are characterized as polluted and dirty. The Miass River is one of the main among the large rivers in South Ural. The ecological state of the river is characterised as bad. This work assesses a thirteen-year change of water quality in the Miass River and Argazinskoe and Shershnevskoe reservoirs, which are the source of drinking water for the residential area of the Chelyabinsk region. The river water is used to provide the cities and towns of the region, as well as numerous industrial and farming enterprises with water. Besides, effluents are discharged into the Miass river along its whole length. The results of many years of observation have shown, that heavy metals and biogenic substances are the main pollutants for the river. This work aims toanalyse episodes of high and extremely high pollution of the water bodies. Episodes of high and extremely high levels of Cu, Zn and Mn are recorded annually at dam part of Argazinskoe reservoir. Episodes of high and extremely high levels of biogenic elements are recorded for the stretches of the river downstream of Chelyabinsk. Currently, some measures within the project «Clean Water» are planned to improve water quality in the studied water bodies.

QUALITY OF NATURAL WATERS IN AGROLANDSCAPES OF THE FOREST-STEPPE ZONE DEPENDING ON ANTHROPOGENIC LOAD

Pollution and depletion of water resources is becoming a global environmental problem today. Theissue of quality control of drinking and pond water in rural areas is an urgent, multifaceted problem, as it directly affects the health of the population.Therefore, on the basis of monitoring studies, the assessment of the state of natural waters (drinking water of decentralized water supply and open reservoirs — ponds) in the agro-landscapes of the ForestSteppe zone for various agro-technogenic use was carried out. The state of natural waters has been studied by the method of agroecological monitoring. Conducted monitoring studies of the state of natural waters indicate their significant non-compliance with regulatory requirements, both for drinking purposes and for fishery needs. It is determined that their quality condition is due to the hydrological regime and the level of anthropogenic load, which leads to an increase in the content of pollutants in natural waters suchas nitrates, ammonium compounds, copper, nickel, chlorides. Most often, water from the wells of the surveyed rural settlements had an excess of nitrates. Ammonium compounds were one of the most common water pollutants in ponds. This is due to the violation of sanitary requirements of the territory, non-compliance with the rules of disposal of livestock and household waste, which occurs even if the territory of the entire agricultural landscape is involved in organic farming.Therefore, the issue of natural water quality control and reduction of risks of their pollution is important from the point of view of improving the quality of drinking water and preservation of open natural reservoirs, as it directly affects the health of the population. Studies show that to prevent contamination of groundwater (wells) and surface water bodies (ponds), it is necessary to anticipate the risks of contaminants entering groundwater and the likelihood of their lateral leaching.

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Anthropogenic pollution of natural waters by pesticides became a global problem with the beginning of their widespread use in the 1960s of the twentieth century. The most studied cells’ response to the pesticides is an increase in the content of reactive oxygen species (ROS) and, as a consequence, the development of oxidative stress. The proliferative activity of cells is regulated by various factors and largely depends on the expression of proteins involved in the DNA replication. Among such proteins are replicative proteins A (RPA), which binds single-stranded DNA (ssDNA) of eukaryotes. Disruption of RPA-associated cellular activity initiates genomic imbalance, so the expression and content of RPA1 serves as a marker not only of the cell cycle stability, but also the relevant response to DNA damage caused by ecotoxicants.The aim of our study is to determine the oxidative stress development and the RPA1 protein state as a response of rainbow trout’s brain cells to the influence of sublethal concentrations of the lambda-cyhalothrin. A model experiment on the neurotoxicity of lambda-cyhalothrin was performed on the rainbow trout (Oncorhynchus mykiss) under experimental conditions in a la-boratory. The obtained results indicate that sublethal concentrations of lambda-cyhalothrin in the water induce a significant increase in ROS generation in the rainbow trout’s brain. It was found that the content of ROS in the fish brain in all experimental groups depends on both the lambda-cyhalothrin concentration and the duration of exposure to the pesticide. Oxidative stress under the influence of lambda-cyhalothrin increases the content of stress-regulating protein RPA1 in the fish brain, inhibits transcriptional activity and limits the DNA breaks repair, which, in turn, can lead to genomic instability and activation of apoptosis. This indicates a high sensitivity of the mechanism of DNA replication to the neurotoxic effect of synthetic pyrethroids. Thus, the detected increased expression of RPA1 protein may be an adequate biomarker of cellular response to the toxic effects of synthetic pyrethroids in the brain of fish. Further studies of the effect of pyrethroids on key proteins of the aquatic organisms’ reaction to intoxication are of great importance for the determination of indicative biomarkers of pesticide pollution and its potential risk

Toxic Elements in the Soils of Urban Ecosystems and Technogenic Sources of Pollution

Using physicochemical methods of analysis (XRF and AAS), the elemental composition of urban soils of large urban ecosystems of one of the industrially developed regions of Russia was studied. It was revealed that most of the soils of urban ecosystems have technogenic anomalies in a number of heavy metals and metalloids: As, Co, Ni, Pb, Zn, Cr. An abnormally high iron content in the soils of the region was established compared with the world level and clarke of element in the soils. Without exception, all studied urbanozems are characterized by a high S content. Territories with a moderately hazardous and dangerous pollution level, which amounted to 20% of the studied urban ecosystems, respectively, were identified by the total pollution index. Sources of toxic elements in urban soils are metallurgical, defense, metalworking and chemical industries. The industrial production and toxicant-polluted urban soils considered in the article are a potential source of pollution of natural waters and surface layers of the atmosphere. The soils of cities and sanitary protection zones of industrial enterprises with geochemical anomalies require bioremediation

Природные воды и почвы агроландшафта под воздействием аэротехногенного загрязнения

The area of lands in Karelia that do not satisfy sanitary and hygienic standards is increasing. The major shift is observed in areas under influence of industrial enterprises which emissions influence the condition of soil cover and surrounding water bodies. The study shows results of research of natural waters and soils of agricultural lands that are under influence of a mining company in Karelia. The purpose of research is to study aerial technogenic influence on soils of reclaimed agricultural lands nearby a quarry of a mining company. Among purposes were research of element structure of snow fallout and soils. A shift in physical and chemical characteristics of soils was found during research of dust pollution of agrolandscape. As a result of research a concentration ratio of some chemical elements was estimated as well as total indicators and levels of pollution of natural waters and soils. Content of chemical elements (Fe, Mn, Ni, Co, Cu, Cr) can be described by high level of concentration ratio, and these elements are the main pollutants. Recomendations were suggested to organise sanitary protection dust-catching forest belts along the source of technogenic pollution as well as carrying out of intensive dust-catching activities.

Nano Structured and Pyrolytic Deposited Carbon Electrodes for Detection of Nitroaromates – a Comparison

IntroductionNitroaromatics like 2,4,6-trinitrotoluene (TNT) and 2,4-dinitrotoluene (DNT) are long-lasting organic pollutants in natural water and soil caused mainly by the military usage. Nano structured electrodes are established in detection of such compounds in water by linear sweep voltammetry (DP) [1]. On the other hand, it could be shown that screen printed carbon electrodes [2] and such made of pyrolytic deposited carbon are also suited for that purpose [3]. Both kind of electrodes were investigated regarding the determination of nitroaromatic compounds in aqueous solution. The aim of this paper is to compare the performance of both electrodes in comparison to commercial electrodes respecting sensitivity, selectivity and long-term stability.ExperimentalElectrodes using carbon nano-tubes and gold nano-particles on printed carbon are commercially available (DropSens, Spain DRP-110CNT-GNP). Screen printed electrodes (SPCE) of 3mm in diameter were industrially like produced on an alumina substrate with a commercial carbon ink (DuPont) carbon paste. Pyrolytic graphite layer were deposited by high temperature decomposition (1050 °C) of aromatic vapor for 15 min with high reproducibility (PyGE). Solid state analyses as XRD and SEM analysis show crystalline carbon with a sp2 hybridization (Fig. 1). The setup of the electrodes is seen in Fig. 2. All experiments were performed in a three electrode arrangement using platinum counter electrode and Ag/AgCl,Cl--reference electrode in a buffer solution. Voltammetric experiments were performed by a PalmSens potentiostate (Palm Instruments, NL). DRP-110CNT-GNP were investigated by linear sweep voltammetrie. SPCE and PyGE were measured in differential pulse voltammetry mode (DPV). The parameter for the DPV were selected as follows: scan rates of 15 mV∙s-1 to 20 mV∙s-1, amplitude of 50 mV and step height of 5 mVResults and discussionThe potentials of the single reduction peak of nitro-aromates can be clearly separated (Fig. 3) for both kind of electrodes, SPCE and PyGE. The nitroaromates trinitrotoluene (TNT) and dinitrotoluene (DNT) are reduced and dopamine is oxidized in DPV mode (Fig.4). The peak currents are proportional to the TNT concentrations with a sensitivity of 2.7 nA/ppb for SPCE (Fig.5) and 0.78 for PyGE (Fig. 6) at the characteristic peak potential of -0.59 V (R²=0.99). Commercial electrodes DRP-110CNT-GNP made of carbon with gold nano particles require a special treatment in cyclo-voltammertic mode up to stable measuring conditions. The sensitivity of 2.8 nA/ppb is high compared to PyGEs. The relative errors in measuring cycles (35 %) are very much higher than those for PyGEs (5 %). PyGE do not need a special pretreatment before use.Screen printed and pyrolytic deposited carbon electrodes can be applied in air saturated aqueous solutions like in field application. For both electrodes, SCPE and PyGE, the oxygen reduction peak do not interfere with the reduction of the nitro groups. The manufacturing tolerances become smaller in the row DRP-110CNT-GNP, SPCE, PyGE. PyGEs can be produced in few steps with very small deviations. They can stored in air or in water over years without a loss of performance. Commercial electrodes are very complex in setup and obviously not so easy to produce in proper quality. Furthermore, their signals are remarkably influenced by oxygen so that measurements in air are not possible.

Photo-mechanism of phenolic pollutants in natural water: Effect of salts

The effect of a natural water matrix on the photodegradation of four phenolic compounds: phenol, 4-chlorophenol, 4-nitrophenol and methyl-p-hydroxybenzoate, has been studied with two commercial TiO2 catalysts with very different physico-chemical properties (Hombikat UV-100 and Aeroxide® P25). Small changes in the photodegradation rates of these four aromatic compounds were observed to compare both TiO2 photocatalysts. The photocatalytic process starts with addition of HO to the aromatic ring in a two-step process (addition-elimination). Hammett linear free energy relationships show the second step is rate-determining, electron-withdrawing substituents leading to a reduction in reaction rate. A photo-mechanism mediated by HO radicals formed from the photogenerated holes was the most significant when TiO2 Hombikat was used in tap water. On the contrary, the conduction band electrons and ROS generated from CB electrons played a major role in the photocatalytic degradation over TiO2 P25. The loss of activity found when P25 was employed in the presence of Na2CO3 or NaHCO3 was mainly due to the change in pH, because no effect on HO radical formation was detected. In contrast, the presence of ions enhanced photoactivity and faster HO radical formation was detected in the case of TiO2 Hombikat. These significant differences can be well related to the fact that Hombikat has presented a larger surface area and a more negatively charged surface than P25, which prevents anions from being strongly adsorbed.

Geological Environment Role in the Formation of Hydrogeoecological Conditions within Large Industrial Zones

Natural and man-made conditions of the Nizhnekamskaya industrial zone are discussed in the article. This zone includes large petrochemical and oil refineries, PJSC «Nizhnekamskneftekhim» is one of the largest companies in Europe. The article shows that significant changes in the composition of natural waters are manifested within the territory of a large operating surface landfill for industrial waste and in its vicinity. Here, the salinity of underground water can reach 12 g/l, and the concentration of petroleum products and phenols, which are characteristic pollutants, reaches 982 and 14 mg/l. Within the industrial site, underground water salinity reaches 1.25 g/l, their hardness is 18 mmol/l, and permanganate index is 17.3 mgO/l. The intensity of pollution of natural waters decreases with increasing distance from the boundaries of industrial zones. There are no signs of pollution of natural waters at a distance of 1.0-1.5 km from the landfill. The composition of natural waters has not changed over the past 40 years outside the industrial zone. Here, HCO3/Ca and HCO3/Mg-Ca are developed; waters with mineralization up to 0.5-0.6 g/l and total hardness up to 7 mmol/l are favorable for drinking. Natural water pollution is local, since the geological environment has high buffer properties. The nature of the geological section, consisting mainly of clay rocks, the favorable quality of precipitation at their rate of 550 mm / year determine these properties. The predominant type of pollutants, represented mainly by organic substances (petroleum products, phenols, etc.), which are subjected to chemical and biological degradation, also determine these properties. In addition, vertical hydrogeochemical zonality plays an important role. It changes with an increase in the depth of the HCO3/Ca waters of the waters of HCO3/Na composition. At the same time, the salinity of underground water is in the range of 430-600 mg/l, and the hardness decreases from 6.4-7.3 to 0.5-2.3 mmol/l. This determines the possibility of obtaining potable quality water in any part of the industrial zone, where the optimal depths of wells’ filters are 140-160 m.

Ракообразные дельты реки Волги в условиях аварийных нефтяных разливов

The article describes the dangerous consequences of petroleum products - the most dangerous pollutants of the aquatic environment, which disturb many natural processes and relationships, changing the habitat of aquatic organisms.A variety of sources contributes to the pollution of natural waters with various fractional composition of petroleum products. The complex studies of oil pollution of water bodies were carried out in the vicinities of Astrakhan in places of accidental oil spills in 2013-2015. Analysis of the study results confirmed the need to assess the extent of water pollution by hydrocarbons, not only in terms of the mass concentration of oil in the water, but also in biological parameters of the harmless concentration of the toxicant, because under equal levels of mass concentration oil contaminants with different fractional composition have different degree of toxic effects on living organisms. The heavy oil fractions of the oil products had the maximum effect on Daphnia magna Straus. The limit of harmless concentration of oil products dissolved in natural waters of the Serebryanaya Volozhka canal was 0.034-0.136 mg/dm3; the limit of harmless concentrations of oil products spilled on the water surface made 0.014 mg/dm3. This is 3.6 times less than maximum permissible coefficient of oil products in the water bodies of Russia (0.05 mg/dm3). Bioassay methods, along with the traditional analytical methods have to be used in a comprehensive study of oil pollution of the aquatic environment.

Techno-Economic Evaluation of Iron and Aluminum Coagulants on Se(IV) Removal

Research on selenium pollution in natural waters is continuous and discouraging. In this study, coagulation/precipitation was applied with the use of Fe(II), Fe(III), and poly-aluminum chloride (PACl) salts for Se(IV) removal at concentration range 10–100 μg Se(IV)/L that is commonly found in drinking waters. Prehydrolyzed Fe(III)-FeCl3 delivered the best uptake capacity (Q10 = 8.9 mg Se(IV)/g Fe(III) at pH 6) at the residual concentration equal to the drinking water regulation limit of 10 μg/L. This was much higher than the efficiencies achieved when applying the other coagulants: i.e., Q10 = 7.3 mg Se(IV)/g Fe3+-FeClSO4, Q10 = 6.4 mg Se(IV)/g prehydrolyzed Fe(III)-Fe2(SO4)3 and 0.7 mg Se(IV)/g Al-PACl at pH 6, and Q10 = 0.45 mg Se(IV)/g Fe(II) at pH 7.2. Comparing the different sources of Fe(III), it is apparent that Se(IV) uptake capacity is inhibited by the presence of SO42− in crystal structure of prehydrolyzed Fe2(SO4)3, while prehydrolyzed FeCl3 favors Se(IV) uptake. Temperature effect data showed that coagulation/precipitation is exothermic. In techno-economic terms, the optimal conditions for Se(IV) removal are coagulation/precipitation at pH values lower than 7 using prehydrolyzed Fe(III)-FeCl3, which provides a combination of minimum sludge production and lower operating cost.