Chemical Composition Of Water Research Articles

НАВЧАЛЬНИЙ ПОСІБНИК З ГІДРОЕКОЛОГІЧНИХ АСПЕКТІВ ВОДОПОСТАЧАННЯ ТА ВОДОВІДВЕДЕННЯ – СПІЛЬНИЙ ПРОЄКТ ДВОХ УНІВЕРСИТЕТІВ (2023 р.)

The article presents and analyzes the study guide “Hydroecological aspects of water supply and sewerage”, published in 2023 by V.K. Khilchevskyi (Taras Shevchenko Kyiv National University), M.R. Zabokrytska and V.Yu. Stelmakh (Lesia Ukrainka Volyn National University). The study guide “Hydroecological aspects of water supply and sewerage” has 12 chapters, which can be conventionally structured into five parts: the role of the components of the chemical composition of water in human life (chapter 1); water resources and water use (chapter 2-3); technological aspects of water supply, rationing and control (chapter 4-7); technological aspects of sewerage, regulation and control (chapter 8-10); water supply and drainage in the cities of Kyiv and Lutsk (Chapter 11); water quality assessment of water bodies for water supply and environmental purposes (Chapter 12). The authors of the study guide emphasize that when using water objects for water supply, it is necessary to take into account the possibility of their contamination – the excess of pollutants or indicators of the physical properties of water in maximum permissible concentrations, which causes a violation of water quality standards. In Ukraine, there have been many changes related to both water monitoring and the regulatory framework for water quality assessment for various purposes, which is due to the course of integration with methodical approaches in this field in the European Union. A significant incentive for this process was the signing of the Association Agreement between Ukraine and the EU in 2014, which led to the reform of many spheres of activity, including those related to the management of water resources and their quality. The study guide is intended for students studying in the educational programs “Hydrology” and “Management and ecology of water resources” specialty 103 “Earth sciences”. It can also be useful for students of other educational programs of specialties 103 “Earth Sciences” and 106 “Geography”, in which they study issues of water resources, water supply and drainage.

ГИДРОХИМИЯ МАЛЫХ РЕК У ГОРОДА ВЯЗЕМСКИЙ

The paper provides characteristics of small rivers water chemical composition in the Vyazemsky area. The assumption is made that river waters were polluted by biogenic and organic nutrients due to to the discharge of untreated domestic wastewater.

К ВОПРОСУ О МЕХАНИЗМЕ ИЗМЕНЕНИЯ ХИМИЧЕСКОГО СОСТАВА ВОДЫ САМОИЗЛИВАЮЩИХСЯ СКВАЖИН В УСЛОВИЯХ НЕСТАЦИОНАРНОГО РЕЖИМА (НА ПРИМЕРЕ СКВАЖИНЫ ГК-1, ПОЛУОСТРОВ КАМЧАТКА)

The ГК-1 self-discharging well is located in the southeastern part of the Kamchatka Peninsula. The well is part of a network of continuous observations of the groundwater regime, conducted in order to identify and study the hydrogeochemical precursors of strong Kamchatka earthquakes. The article discusses data on changes in the flow rate and chemical composition of well water for the period from 1970 to 2022. The subject of the analysis is the hydrogeochemical effects appearing under the conditions of non-stationary regime arising due to drainage of the pressure reservoir by the well and as a result of changes in bottom-hole pressure. The mechanisms of formation of long-term (decades) and relatively short-term (tens of days) changes in the chemical composition of water at the mouth of the ГК-1 self-discharging well are discussed within the framework of the concepts of water-bearing rocks as a heterogeneous block medium with double porosity.

Changes in water chemical composition in Lake Vedlozero and one of its bays as a result of anthropogenic eutrophication

Lake Vedlozero is an accumulating system of a variety of anthropogenic impacts. Since the 1970s, significant changes have occurred in the landscape structure of stream catchments in the southeastern and western parts of the lake’s drainage basin. Deforestation, conversion to arable land and drainage have enriched the lake water with nutrients and organic matter. The northeastern bay of the lake receives substantial amounts of wastewater from the village of Vedlozero and water from the River Vokhtozerka, affected by agriculture in the catchment. High average annual concentrations of total phosphorus (47–173 μg/l) in the water of the bay cause continuous blooming during the open water period. Blooming intensively in the bay, blue-green algae (cyanobacteria) release toxic substances (neuro-, hepato-, and dermatotoxins) dangerous for humans and animals. Massive development of cyanobacteria in the northeastern bay of Lake Vedlozero in summer now causes skin disorders, specifically allergic dermatitis, in Vedlozero village inhabitants (especially children) who swim in the lake.

Analyses of the geometrical properties of fine recycled aggregates

The acquisition of natural sand and dumping of fine recycled aggregates (FRA) are two serious environmental problems that can be solved simultaneously by using FRA as replacement of natural sand in high-end applications. In the past, FRA has been considered an unwanted by-product of construction and demolition waste (CDW) processing, due to the high levels of contaminations and high content of fines. However, FRA is currently considered as a new secondary raw material with large potential. Due to the increasing interests in FRA it is of utmost importance to extensively examine their characteristics. To date, research has been done on the water absorption, density, chemical and mineralogical composition, and size distribution of the FRA. However, knowledge on the geometrical properties of FRA is limited. In this paper the geometrical properties of several types of FRA are examined using digital image processing (DIP). The effect of processing methods, crusher openings and crushing cycles are considered to gain new insights into the characteristics of FRA.

Karst Hydrogeochemical Characteristics and Controlling Factors of Carlin-type Gold Mining Area Based on Hydrochemistry and Sulfur Isotope

Mining activities change the groundwater level and flow conditions through pumping and drainage, which enhances the interaction between groundwater and aquifer rocks; mine drainage is discharged into the surface water system, which affects the whole karst water hydrogeochemical process. Based on hydrogeochemistry and the δ34S isotope, the hydrogeochemical processes, characteristics, and main controlling factors for waste water, karst groundwater, and surface water in a typical Carlin gold mining area and its surrounding areas were revealed. The results showed that:chemical compositions of groundwater and surface water unaffected by gold mining activities were mainly controlled by the weathering of limestone and dolomitic limestone; Ca2+, Mg2+, and HCO3- were main ions; and the water chemical types were Ca-HCO3. The mine wastewater and its downstream receiving water were affected by the dissolution of carbonate and silicate minerals, and cation exchange also played a role; the main ions were Ca2+, Mg2+, Na+, and SO42-, and the hydrochemical type gradually evolved from Ca-HCO3 to Ca-SO4. SO42- was the characteristic component in various water bodies affected by mining, and the concentration of SO42- gradually decreased from top to bottom in the well. The values of δ34S for unaffected groundwater and surface water were positive, and SO42- was mainly derived from realgar oxidation. Conversely, mine wastewater and downstream water were negative, SO42- was mainly influenced by the mixing action of realgar oxidation and meteoric precipitation, and pyrite also contributed to a certain extent. At the same time, NO3- came from agricultural fertilizer and rural domestic sewage discharge directly. Principal component analysis (PCA) further demonstrated:sulfide mineral oxidation and mining activities were the main controlling factors for the water chemical composition of mine wastewater and downstream water, whereas unaffected groundwater and surface water were mainly influenced by water-rock (carbonate rock) interactions. Agricultural fertilizer and rural sewage discharge also had a certain influence. Therefore, the study area should strengthen the interception of surface water, control-block-management of sulfide oxidation, rural domestic sewage treatment, and agricultural fertilizer.

Trace Element Compositions and Water Quality Assessment in the Angara River Source (Baikal Region, Russia)

The relevance of studying the spatial-temporal dynamics in the trace element composition of the water at the Angara River source is associated not only with determining the degree of anthropogenic load on the local area of the water body but also with the use of the water chemical composition of the Angara River source as an integral indicator of the hydrochemical state of the entire Lake Baikal. The current work is based on monthly monitoring studies conducted from March 2021 to February 2022 along the left shore, middle part, and right shore of the Angara River source. In water samples, the concentrations of Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Sn, Cs, Tl, Pb, Th, and U were measured by inductively coupled plasma mass spectrometry. The results indicated that the concentrations of the trace elements lie within mean + 1SD: Cd in 97% of samples; U in 94% of samples; Tl in 92%; Al, Cr, Co, Ni, Cu, Zn, Sn, Pb, and Cs in over 80%; Fe in 78% of samples; and Mn and Th in over 60% of samples. Such results show a high degree of consistency in the water trace element composition at the source of the Angara River. The major factors responsible for the water hydrochemistry at the Angara River source include the runoff of Lake Baikal, the anthropogenic effect of Listvyanka and Port Baikal settlements, and water transport activity. The concentrations of all trace elements in the water of the Angara River source are substantially below the standards for drinking water. At the same time, the single-factor pollution index revealed water samples with considerable contamination by Fe, Zn, Sn, Al, Cs, Mn, Cu, Tl, Cd, Pb, and Th and very high contamination by Cr, Fe, Co, Cs, Tl, Pb, and Th. The pollution load index has classified most of the water samples as having baseline levels of pollutants. Three samples taken from the left shore, four from the middle part, and seven from the right shore were classified as polluted. This means that the ongoing anthropogenic impact may worsen the water quality and have a negative impact on living organisms. The obtained results make a clear case for strengthening environmental protection measures to minimize the anthropogenic effect on the ecosystems of Lake Baikal and Angara River.

Water Chemical Composition of the Selenga River in High Water Level Period

Water Chemical Composition of the Selenga River in High Water Level Period

HYDROCHEMICAL STUDIES OF THE TROUT FARMING AREA IN KONDOPOGA BAY OF LAKE ONEGO IN THE WINTER OF 2022

Hydrochemical studies of the trout farming area in Kondopoga Bay of Lake Onego were carried out in the winter of 2022. Surveys at the deep-water site near the cages revealed dissolved oxygen starvation (0.8 mg/l) and a high content of ammonium (0.410 mg N/l) and mineral phosphorus (787 μg P/l, or 97 % of total phosphorus) in the near bottom level, which is comparable to wastewater from the Kondopoga pulp-and-paper mill. At other sites located in the trout farming area and at K50 located in the zone affected by Kondopoga PPM wastewater, which spreads over the bottom of the bay in winter, the dissolved oxygen content varied from 6.8 to 13.1 mg/l, the concentrations of NH4 + (up to 0.068 mg N/l) and Pmin (up to 51 μg P/l) were significantly lower than near the cages. Our data indicate the trout farms have a significant effect on the water chemical composition, confirmed by a previously detected long-term trend for an increase in TP content and intensive growth of phytoplankton in the central part of Kondopoga Bay.

Specifics of Chemical Composition Origin of Surface Water in the Arctic Zone of Western Siberia

—One of the most urgent problems on which current studies of Arctic and subarctic territories are focused is how permafrost thawing can affect organic carbon fluxes and how these fluxes can influence the geochemistry of the surface and ground water. In addition to disturbing the carbon balance, permafrost thawing provokes the release of a significant amount of other chemical elements entering natural waters. The paper presents original data obtained by studying surface water in 2020 in the Yamalo–Nenets Autonomous District, which is situated in the Arctic zone of the Russian Federation. Permafrost is widespread in the study area, as also are facilities of the oil and gas industry. This predetermines the importance of research on the chemical composition of natural water, its formation, and ecological–geochemical status, which are critical aspects for assessing the anthropogenic load and predicting the influence of climate changes on the biogeochemical cycles of chemical elements. In the course of our fieldwork, 47 surface water samples were taken in the basins of the Taz, Pur, Ob, and Nadym rivers: 23 samples from rivers and streams and 24 samples from lakes and thaw depressions. The sampling sites were chosen to as comprehensively as possible cover the lake–stream–river system in the catchment areas of major rivers of the Yamalo–Nenets Autonomous District. The chemical composition of the water samples was analyzed at a certified laboratory using methods conventionally applied in solving such problems. The data were processed using statistical methods, including the principal component analysis (PCA). Data analysis demonstrates that surface water in the study area is ultrafresh, with neutral or weakly alkaline pH values. Hydrocarbonate, calcium, and magnesium ions dominate in the ionic composition of the water, and ammonium contents are high in the waters of the lakes and thaw depressions. In addition, the ammonium concentration strongly positively correlates with the content of dissolved organic carbon (DOC) and the values of chemical oxygen demand (COD) and permanganate index (PI). It was found out that the streams (springs and rivers) differ from the lakes and the water of the thaw depressions in higher concentrations of main ions that are brought to the water mainly by natural factors (these are {text{HC}}{{{text{O}}}_{{text{3}}}}^{ - }, Ca2+, Mg2+, and Na+) and higher total dissolved solids (TDS) and pH values. In contrast, the water of the thaw depressions is characterized by the highest concentrations of DOC and the values of other parameters related to organic matter (N–{text{N}}{{{text{H}}}_{4}}^{ + }, COD, and PI). It was shown that the main factors that control the chemical composition of the water are its interaction with organic matter from organic (peat) soil horizons and the mineral components of the underlying rocks and soils. The former factor most significantly impacts the water of the thaw depressions, and the latter one affects mainly the chemical composition of the rivers and streams. The relatively high contents of the chloride and sodium ions in the water of the largest lakes are probably caused by the anthropogenic load.

Understanding the hydrochemical functioning of glacierized catchments of the Upper Indus Basin in Ladakh, Indian Himalayas.

Recent studies have endorsed that surface water chemical composition in the Himalayas is impacted by climate change-induced accelerated melting of glaciers. Chemical weathering dynamics in the Ladakh region is poorly understood, due to unavailability of in situ dataset. The aim of the present study is to investigate how the two distinct catchments (Lato and Stok) drive the meltwater chemistry of the Indus River and its tributary, in the Western Himalayas. Water samples were collected from two glaciated catchments (Lato and Stok), Chabe Nama (tributary) and the Indus River in Ladakh. The mildly alkaline pH (range 7.3-8.5) and fluctuating ionic trend of the meltwater samples reflected the distinct geology and weathering patterns of the Upper Indus Basin (UIB). Gibbs plot and mixing diagram revealed rock weathering outweighed evaporation and precipitation. The strong associations between Ca2+-HCO3-, Mg2+-HCO3-, Ca2+-Mg2+, Na+-HCO3-, and Mg2+-Na+ demonstrated carbonate rock weathering contributed to the major ion influx. Principal component analysis (PCA) marked carbonate and silicates as the most abundant minerals respectively. Chemical weathering patterns were predominantly controlled by percentage of glacierized area and basin runoff. Thus, Lato with the larger glacierized area (~ 25%) and higher runoff contributed low TDS, HCO3-, Ca2+, and Na+ and exhibited higher chemical weathering, whereas lower chemical weathering was evinced at Stok with the smaller glacierized area (~ 5%). In contrast, the carbonate weathering rate (CWR) of larger glacierized catchments (Lato) exhibits higher average value of 15.7 t/km2/year as compared to smaller glacierized catchment (Stok) with lower average value 6.69 t/km2/year. However, CWR is high in both the catchments compared to silicate weathering rate (SWR). For the first time, in situ datasets for stream water chemical characteristics have been generated for Lato and Stok glaciated catchments in Ladakh, to facilitate healthy ecosystems and livelihoods in the UIB.

The Role of the Catchment Area in Shaping Water Quality in the Lowland Springs of the Knyszyn Forest (NE Poland)

The Puszcza Knyszyńska springs are an important element of the environment, conditioning the high geo- and biodiversity in the region. These springs are layered outflows that drain the waters of the Quaternary level. More than 200 outflows have been cataloged, and 80 of them have measured/estimated yields and analyses of their water qualities. During periods of low water levels, the discharge efficiency most often fluctuated within a range of 0.5–2.0 dm3·s–1. In light of the applicable legal standards, the tested waters were of excellent quality. They belonged to the two hydrochemical types HCO3-Ca and HCO3-Ca-Mg, indicating the Quaternary aquifer’s homogeneity in the post-glacial areas. Small concentrations of most of the chemical parameters of water were found in the forest springs. Larger transformations in the chemical composition of water occurred in the outflows located in agricultural land and rural areas. A characteristic feature of the chemical composition of the water in the region’s lowland springs was an increased concentration of biogenic compounds (nitrogen, phosphorus, and carbon compounds), both organic and inorganic. The average concentration of dissolved organic carbon in the water of the lowland springs in summer exceeded 4 mg·dm−3. In some outflows, most often of a swamp nature or located in peat areas, the concentration of dissolved organic carbon even exceeded a dozen or so mg·dm−3.

Wildfire Smoke Influence on Cloud Water Chemical Composition at Whiteface Mountain, New York.

Wildfires significantly impact air quality and climate, including through the production of aerosols that can nucleate cloud droplets and participate in aqueous-phase reactions. Cloud water was collected during the summer months (June-September) of 2010-2017 at Whiteface Mountain, New York and examined for biomass burning influence. Cloud water samples were classified by their smoke influence based on backward air mass trajectories and satellite-detected smoke. A total of 1,338 cloud water samples collected over 485days were classified by their probability of smoke influence, with 49% of these days categorized as having moderate to high probability of smoke influence. Carbon monoxide and ozone levels were enhanced during smoke influenced days at the summit of Whiteface Mountain. Smoke-influenced cloud water samples were characterized by enhanced concentrations of potassium, sulfate, ammonium, and total organic carbon, compared to samples lacking identified influence. Five cloud water samples were examined further for the presence of dissolved organic compounds, insoluble particles, and light-absorbing components. The five selected cloud water samples contained the biomass burning tracer levoglucosan at 0.02-0.09μM. Samples influenced by air masses that remained aloft, above the boundary layer during transport, had lower insoluble particle concentrations, larger insoluble particle diameters, and larger oxalate:sulfate ratios, suggesting cloud processing had occurred. These findings highlight the influence that local and long-range transported smoke have on cloud water composition.

Assessment of risk for the development of non-cancirogenic effects in using water from non-centralized water suppliers in the Tomsk region

Introduction. Iron is a widespread element in groundwater, which is used for domestic and drinking water supply. When using waters from non-centralized sources, deironing of waters, as a rule, is not carried out. When such waters are used for drinking purposes, there is a likely risk of negative effects for public health. Materials and methods. Forty six sources of non-centralized water supply (private wells, water wells, springs) were studied It considered assessing the health risk with oral administration of the components through drinking water into the body. Results. For single samples in the chemical composition of waters there were determined high contents of total hardness, SO42-, Cl-, NO3-. Waters with Fe and Mn concentrations many times higher than the normative values are widespread. The main non-carcinogenic risk is iron and nitrates, which have been identified as warning and high risk levels. For other components, the values of the hazard coefficient are within the range of the minimum and acceptable levels of risk. The probability of occurrence of negative effects for the children’s age group is possible with an iron content of 5 mg/l and more, for an adult - 11 mg/l and more. Limitations. The limitation related to the incomplete route of exposure to chemical components, since only one medium (drinking water) and only one route of exposure (oral exposure) was considered on the risk assessment. This study is also limited by the number of water samples. Conclusion. The health risk associated with high iron content in water has been set for children and adults. For the children’s group (up to 6 years), the risk of developing diseases of non-infectious etiology is significantly higher, than for the adult group, as shown by the results. When iron-containing waters are used for drinking purposes, there is a risk of non-infectious pathologies.

Mortality risk evaluation methods for total dissolved gas supersaturation to fish based on a mitigation measure of utilizing activated carbon

The proper water chemical composition of aquaculture water is very important for fish farming in reservoirs or fish multiplication stations. Gas bubble disease (GBD) is mainly caused by total dissolved gas supersaturation (TDGS) in water and is a common problem that affects the healthy growth of fish. Extensive measures have been taken to mitigate TDGS levels in water where fish live, while methods for quantitatively evaluating the mitigation effect of the proposed measures on fish exposed to TDGS are still lacking. In this paper, an activated carbon (AC) adsorption experiment for supersaturated total dissolved gas (TDG) dissipation was conducted, and the experimental results indicated that AC addition could effectively accelerate supersaturated TDG dissipation. Based on fish tolerance experiments conducted by Huang (2010), two models, including a mortality risk degree evaluation model and a mortality rate calculation model, were developed to quantitatively evaluate the mortality risk mitigation effect of AC addiction on fish exposed to unsteady TDGS levels. Application of the results of the mortality risk degree evaluation model has shown that AC addition can help alleviate the mortality risk of fish suffering from TDGS. Application of the results of the mortality rate calculation model has also demonstrated that the final mortality rate of the fish group in the case with AC addition was lower than that of the case without added AC, and the final mortality rate decreased as the specific surface area and dosage of AC increased. Furthermore, an equation that related the required AC mass and a given harvested fish mass was established. This paper provides a reference for evaluating the effects of various mitigation measures to alleviate the risk posed to fish by TDGS.

Uncertainty propagation in pore water chemical composition calculation using surrogate models

Performance assessment in deep geological nuclear waste repository systems necessitates an extended knowledge of the pore water chemical conditions prevailing in host-rock formations. In the last two decades, important progress has been made in the experimental characterization and thermodynamic modeling of pore water speciation, but the influence of experimental artifacts and uncertainties of thermodynamic input parameters are seldom evaluated. In this respect, we conducted an uncertainty propagation study in a reference geochemical model describing the pore water chemistry of the Callovian-Oxfordian clay formation. Nineteen model input parameters were perturbed, including those associated to experimental characterization (leached anions, exchanged cations, cation exchange selectivity coefficients) and those associated to generic thermodynamic databases (solubilities). A set of 13 quantities of interest were studied by the use of polynomial chaos expansions built non-intrusively with a least-squares forward stepwise regression approach. Training and validation sets of simulations were carried out using the geochemical speciation code PHREEQC. The statistical results explored the marginal distribution of each quantity of interest, their bivariate correlations as well as their global sensitivity indices. The influence of the assumed distributions for input parameters uncertainties was evaluated by considering two parametric domain sizes.

Methane-rich thermal and mineral waters of the Avachinsky Depression, Kamchatka

Wells up to 3000 m deep at the foot of the active volcanoes Koryaksky and Avachinsky within the Avachinsky Depression revealed a basin of saline waters (up to 22 g/l), methane-rich gas (CH4 up to 75 vol% in dry gas) with a temperature up to about 70 °C in the western part of the explored area (Ketkino Field) and colder ones - to the east, closer to the Pacific coast. This article presents data on the chemical composition including trace elements, and isotopic compositions of these waters that include δD and δ18O of waters, 87Sr/86Sr of the dissolved Sr, 3He/4He, δ13C of CH4 and CO2 in gases, and δ34S of the dissolved H2S and SO4. The composition of the waters is sodium chloride, with very low contents of sulfate and magnesium in waters of the western section of the basin, high calcium (up to 960 ppm), and unusually high concentrations of strontium (up to 54 ppm). The N2/Ar ratio is generally 2–3 times higher than in the air, i.e. non-atmospheric nitrogen is present. A distinctive geochemical feature of the basin is the significant difference between δ13C–CH4 and 87Sr/86Sr in the thermal Ketkino fluids comparing to colder fluids of other parts of the basin, despite the practically identical composition of waters and gases. Possible scenarios of water-rock interaction responsible for the chemical composition of waters are discussed.

Use of analysis of seasonal hydrochemical regime for better understanding of mine water genesis and more accurate estimate of its impact on stream water quality at flooded Rudňany ore mine

Seasonal hydrochemical regime of water flowing out of the Rochus Fe-Cu mine in the Spiš-Gemer Ore Mts. was monitored by discharge measurements and laboratory analyses of mine water chemical composition. Regression analysis of these data showed a statistically significant dependence of concentration of many important chemical elements on mine water discharge. The obtained data made it possible to better understand the processes of mine water chemical composition genesis, as well as to determine in more detail the degree of its environmental impact. Geochemical calculations and forward geochemical modelling suggest that chemical composition of mine water is formed in three stages. First phase takes place in the aeration zone of the mine, where ankerite dissolution, intensified by pyrite oxidation, dominates. In saturated zone of the mine, ankerite dissolution is probably controlled by CO2 input in open carbonate system. These two main geochemical processes take place permanently and at the time of low flow conditions they lead to relatively stable composition of water outflowing from mine. In time of higher flow conditions, concentration of SO4, Mg, Ca, Na and As significantly increases, probably as a consequence of mixing with stagnant water from deeper or hydraulically more isolated parts of the flooded mine. Water flowing out from mine enters the Rudniansky potok creek and contaminates it mainly by manganese. The limit for Mn content in surface water is exceeded here at the time of low flow conditions – usually for 180 days a year. Anomalous concentrations of SO4, Mg, As and Sb in mine water are sufficiently diluted in stream water were they do not exceed environmental limits.

PROBLEMS OF DRINKING WATER SUPPLY IN SMALL SETTLEMENTS OF THE SOUTHERN URALS AND THE CIS-URALS

The article discusses the issue of water supply sources for small settlements located on the territory of the Southern Urals and the Cis-Urals. Based on almost 30 years of monitoring of a well used for the water supply of a summer country house, it is shown that the trend of the groundwater level in this area tends to decrease. At the same time, observations of chemical composition of water revealed an increase in the amount of nitrates. It has been established that the level of groundwater depends on the amount of precipitation. Their amount also affects the level of nitrates in groundwater. With an increase in precipitation, the amount of nitrates decreases. The problems shown indicate the need to control the quality of water used for non-centralized water supply of small settlements.

Assessment of water quality and irrigation suitability of the Hrazdan river and several canals fed from it

The chemical composition of waters of the Arzni-Shamiram and Lower Hrazdan canals fed by the Hrazdan River, as well as Hrazdan River water in that area, was studied, and their suitability for irrigation was assessed. Water samples were collected from 7 sampling points and the total amount of salts, electrical conductivity (EC), pH, bicarbonates as well as some toxic microelements (Al, As, Be, Cd, Co, Cr, Cu, Fe, Li, Mn, Mo, Zn, Ni, Pb, Se, V) were determined. It has been shown that waters of the Arzni-Shamiram canal are suitable for irrigation. The water pollution processes in the Lower Hrazdan Canal is observed. Despite the fact that the concentrations of some heavy metals and hydrocarbonates don't exceed the MPC for irrigation, depending on amount and composition of wastewater discharging this system, there is a high probability that their concentrations in the canal exceeds the permissible limit in the near future.