Chemical Composition Of Water Research Articles

Exploring Endogenous Processes in Water Supply Systems: Insights from Statistical Methods and δ18O Analysis

Water used for water supply undergoes numerous changes that affect its composition prior to entering the water supply system (WSS). Once it enters the WSS, it is subject to numerous influences altering its physical and chemical composition, redox potential, and microbial quality. Observations of water quality parameters at different locations within the WSS indicate that it is justified to assume that these processes take place from the source to the end user. In this study, we used the results of routine everyday analyses (EC, T, pH, ORP, chloride, nitrate, nitrite, ammonium, and bacteria) supplemented by experimental data from a one-year sampling campaign assessing the main cations and anions and stable isotopes δ2H and δ18O. Through these data, the statistical significance of the differences between the concentrations of the basic water quality parameters among different WSS locations was determined, together with the water retention time in the system. The results indicate minor changes in water chemical composition within the observed WSS, remaining below the prescribed Maximum Contaminant Level (MCL) for human consumption. However, factors such as water retention time, CaCO3 deposition, pH fluctuations, and bacterial growth may influence its suitability, which necessitates further investigation into potential risks affecting water quality.

Element mobility during basalt-water-CO2 interaction: observations in natural systems vs. laboratory experiments and implication for carbon storage

Today, carbon dioxide removal from the atmosphere is the most ambitious challenge to mitigate climate changes. Basalt rocks are abundant on the Earth’s surface (≈ 10%) and very abundant in the ocean floors and subaerial environments. Glassy matrix and minerals constituting these rocks contain metals (Ca2+, Mg2+, Fe2+) that can react with carbonic acid to form metal carbonates (CaCO3, MgO3 and FeCO3). Here, we present a data compilation of the chemical composition of waters circulating in basalt aquifers worldwide and the results of simple basalt-water-CO2 experiments. Induced or naturally occurring weathering of basalts rocks release elements in waters and elemental concentration is closely dependent on water CO2 concentration (and hence on water pH). We also performed two series of experiments where basaltic rock powder interacts with CO2-charged waters for one month at room temperature. Laboratory experiments evidenced that in the first stages of water-rock interaction, the high content of CO2 dissolved in water accelerates the basalt weathering process, releasing in the water not only elements that can form carbonate minerals but also other elements, which depending on their concentration can be essential or toxic for life. Relative mobility of elements such as Fe and Al, together with rare earth elements, increases at low pH conditions, while it decreases notably at neutral pH conditions. The comparison between experimental findings and natural evidence allowed to better understand the geochemical processes in basaltic aquifers hosted in active and inactive volcanic systems and to discuss these findings in light of the potential environmental impact of CO2 storage in mafic and ultramafic rocks.

Hydrochemical properties and heavy metal concentrations (ecological and human risk) of lake Rukwa

This study examined lake Rukwa's hydrochemical characteristics and heavy metal levels (ecological and health hazards). Results showed average pH (8.83-8.95), EC (1470-1572.22 µS/cm), and TDS (1053.04 to 1262.63 Mg/l). The findings reveal that lake Rukwa has Na-K-HCO3 water chemical type. Gibb's diagram revealed that rock weathering and evaporation regulate water's chemical composition. The calcite and sepiolite precipitation enriches the water with Na-CO3-SO4-Cl. The study suggests silicate mineral weathering, rock-water interactions, direct ion exchange, and secondary mineral precipitation govern the geochemical evolution of lake Rukwa. The results revealed that 30% of samples had moderate ecological risk (30 < RI < 60), whereas 70% had severe risk (60 < RI < 120). The oral hazard quotient (HQ) values for lead (Pb) in children were significantly higher (HQ > 1) at all locations, indicating a potential health risk. However, the dermal HQ values were found to be within acceptable levels. Most sites had acceptable Hazard Index (HI) values, except for Pb in children and adults. In Monte Carlo simulations, heavy metal HQ values were below standard limits, except for oral Pb exposure, which exceeded 1 for adults (7.29E-04) and children (2.79E-03). The average CR values for oral and dermal lead in adults (7.29E-04, 3.47E-04) and children (2.79E-03, 1.02E-03) exceeded 1.0E-04, suggesting carcinogenic potential. These findings highlight significant oral and dermal carcinogenic hazards from Pb exposure to lake Rukwa and the necessity for effective comprehensive measures to mitigate these risks.

Ultrasonic cavitation strengthening and generation of superhydrophobicity for the surface of in situ (ZrB2 + Al2O3)/AA6016 matrix composite

To enhance the operating stability and durability of the aluminum matrix composite, the superhydrophobic surface is constructed on the substrate of in situ ZrB2 and Al2O3 nano-particle reinforced AA6016 matrix composite. The method incorporating ultrasonic cavitation treatment and low surface energy modification is applied. The performance of the obtained superhydrophobic surface is investigated through comprehensively analyzing micro and nano surface structures, roughness, water contact angle, chemical composition, and mechanical property. The results indicate that the water contact angle and water sliding angle of the specimen treated with cavitation for 9 min and then modified with fluorosilane attain 163.8° and 7.3°, respectively. High superhydrophobicity is accomplished. Long exposure to ultrasonic cavitation treatment results in the shift from hydrophobicity to hydrophilicity. The presence of particle-reinforced phases induces a pinning effect, causing the accumulation and entanglement of dislocations beneath the surface. This phenomenon leads to a 64.7 % increase in surface hardness, and the thickness of the work hardening layer reaches about 300 μm. The obtained conclusions shed light on the preparation of superhydrophobic surface for the aluminum matrix composite, and the application of aluminum matrix composites in harsh environment is expected to be broadened.

The use of 18S rRNA for identification of the first record of Tadpole Shrimp Lepidurus apus (Linnaeus, 1758) from Jordan

Abstract. Abushattal S, Alnasarat H, Alnaimat SM, Eid E. 2024. The use of 18S rRNA for identification of the first record of Tadpole Shrimp Lepidurus apus (Linnaeus, 1758) from Jordan. Biodiversitas 25: 1223-1229. The tadpole shrimps are living fossils that survive in temporary water pools and are considered benthic organisms that swim and feed on tiny organisms. Two genera of tadpole shrimps exist worldwide: Triops and Lepidurus, which share similar ecological niches and habitats but never coincide. The occurrence of the tadpole shrimp Lepidurus apus in Jordan was confirmed for the first time using the 18S rRNA Gene-Based PCR Assay. The experimental approach encompassed the amplification of biological specimens utilizing a universal amplicon measuring approximately 1,500 base pairs (bp), specifically targeting the 18S ribosomal RNA (rRNA) gene. Subsequently, the acquired sequences underwent scrutiny through BlastN search against the GenBank database for validation and comparative analysis. Genetic analysis was needed to define the species accurately, especially with tadpole shrimp's generally high morphological variability. This species was recorded in a temporary freshwater pool in the desert of Al-Jafr in Ma’an governorate in southern Jordan. The DNA analysis showed a 100% identical sequence of the 18S rRNA gene with Lepidurus apus sequences. This record is important due to the ecological role of the tadpole shrimps as filter feeders, consuming algae, bacteria, and other small particles of organic matter, and as a food source for various fish, birds, and other aquatic animals. In addition, it will pave the way for future research to identify its economic importance, such as its role in mosquito control and its potential role in aquaculture. Finally, tadpole shrimp are sensitive to environmental changes and could be used to indicate climatic changes and habitat degradation. This is mainly due to their sensitivity to changes in water quality, including temperature, pH, and chemical composition, and their niche requirements for survival and reproduction. In addition, monitoring tadpole shrimp distribution and comparing it with historical records can reveal patterns of climate-induced range shifts.

Seasonal Stream Water Chemistry Response To Long-Term Forestry Drainage And Wildfire: A Case Study In A Part Of The Great Vasyugan Mire

Recent research suggests that climate change is contributing to rising solute concentrations in streams. This study focuses on assessing the concentrations of major elements, nutrients, and dissolved organic carbon (DOC), and their release through the bog-river system in the taiga zone of Western Siberia. The research was carried out in the northeastern part of the Great Vasyugan Mire (GVM), the largest mire system that impacts the quality of river water in the Ob River basin. By using PCA and cluster analysis, we examined the long-term dynamics of the chemical composition of headwater streams of the GVM affected by drainage and wildfires. Our data from 2015-2022 revealed that the concentrations of Са2+, Mg2+, K+, Na+, and HCO3- in stream water from the drained area of the GVM were, on average, 1.3 times lower than those at the pristine site. Conversely, the concentrations of NH+4, Fetotal, Cl-, SO42-, NO-3, DOC, and COD were higher, indicating the influence of forestry drainage and the pyrogenic factor. Our findings also demonstrated that the GVM significantly impacts the water chemical composition of small rivers. We observed a close correlation in the concentrations of К+, Na+, Cl-, Fetotal, NH+4, HCO3-, and COD between the GVM and the Gavrilovka River waters. PCA analysis revealed that air temperature influences the concentrations of Са2+, Mg2+, NH4+, NO3-, HCO3-, Fetotal, and DOC in the studied streams, with an inverse correlation with river discharge. The removal of major elements, nutrients, and DOC from the drained area of the GVM was most pronounced in April, being twice as high as in the pristine area. However, the total export from the drainage area of the Gavrilovka in April-September 2022 was 1.3 times lower than in the pristine area, amounting to 8487 kg/km2, with DOC removal at 42%.

Groundwater‐surface water interaction, dissolved organic carbon oxidation and dissolution in carbonate aquifers

AbstractThe high primary porosity and permeability of eogenetic karst aquifers permit water recharged through secondary dissolution features to be temporarily stored in aquifer matrix porosity. The recharged water contains elevated dissolved organic carbon (DOC) concentrations that, when oxidized, enhance limestone dissolution and impact carbon cycling. We evaluate the relationship between DOC oxidation and limestone dissolution using observations at a stream sink‐rise system and reversing spring in the Floridan aquifer, north‐central Florida, USA, where subsurface residence times of recharged water are days and months, respectively. We estimate water chemical compositions during surface water‐groundwater interactions at these two systems with mixing models of surface water and groundwater compositions and compare them with measured DOC, dissolved inorganic carbon (DIC), Ca2+ and dissolved organic nitrogen (DON) concentrations. Differences between measured and modelled concentrations represent net changes that can be attributed to calcite dissolution and redox reactions, including DOC oxidation. DOC losses and Ca2+ gains exhibit significant (p &lt; 0.01) inverse linear correlations at both the reversing spring (slope = −0.9, r2 = 0.99) and the sink‐rise system (slope = −0.4, r2 = 0.72). DOC oxidation in both systems was associated with decreases in the molar C:N ratio (DOC:DON). Significant (p &lt; 0.01) positive linear correlations between increases in Ca2+ and DIC concentrations after correcting for DIC derived from calcite dissolution occurred at both the reversing spring (slope = 1.3, r2 = 0.99) and the sink‐rise system (slope = 1.61, r2 = 0.75). Greater deviations from the expected slope of −1 or +1 at the sink‐rise system than at the reversing spring indicate DOC oxidation contributes less dissolution at the sink‐rise system than at the reversing spring, likely from shorter storage in the subsurface. A portion of the deviation from expected slope values can be explained by the dissolution of Mg‐rich carbonate or dolomite rather than pure calcite dissolution. Despite this, slope values reflect kinetic effects controlling incomplete consumption of carbonic acid during dissolution reactions.

Hydrochemical characteristics of left-bank tributaries of the Dniester within Ternopil Oblast

&#x0D; &#x0D; &#x0D; The purpose of this article is to study the chemical composition of water and the hydrochemical regime of the left-bank tributaries of the Dniester within the Ternopil Oblast at 9 monitoring sites on the Zolota Lypa, Koropets, Strypa, Seret, Nichlava, and Zbruch Rivers. Water quality monitoring data from the State Agency of Water Resources of Ukraine for the period from 1993 to 2020 were used. The hydrographic assessment of the territory following the Water Code of Ukraine showed the presence of two medium-sized rivers (Seret and Zbruch) and four small rivers among the studied rivers. The chemical composition of the water was analyzed by the following groups of components: major ions and water salinity; physicochemical parameters; and biogenic components (nitrogen and phosphorus compounds). It was found that the water of most studied rivers is calcium bicarbonate by hydrochemical type. The water of the Nichlava River is calcium bicarbonate-sulfate. The average annual salinity of the water of the studied rivers varies from 476 mg∙dm-3 to 699 mg∙dm-3. It was determined that the water of most rivers is moderately fresh in terms of mineralization. The water of the Nichlava River is fresh with high mineralization. The hydrochemical regime of rivers is generally related to the hydrological regime. The minimum concentrations of the main ions and salinity values of the studied rivers are observed during the summer-autumn low water mark, which is explained by the significant amount of precipitation and the presence of floods during this period. In winter, the maximums of these indicators are observed. Among the biogenic compounds (ammonium, nitrite, nitrate, phosphate), the clearest manifestation of the hydrochemical regime was recorded for nitrate. The minimum NO3– concentrations are observed in the summer and autumn low-water periods when nitrates are consumed for the development of aquatic plants. In the autumn period, with the death of aquatic plants, nitrates accumulate, and during the winter low water, their maximum average content is observed. The analysis of the monitoring system of the State Agency of Water Resources of Ukraine for the content of the studied components in the water of the left-bank tributaries of the Dniester over a multi-year period for all samples showed that their concentrations were within the regulatory requirements, except for one case. Particularly, in the water of the Nichlava – Borshchiv River, an ammonium concentration of 15 mg∙dm-3 was recorded, which was 7.5 times higher than the standard (August 2, 2000).&#x0D; &#x0D; &#x0D;

Исследование химического состава воды подземного источника, расположенного на пойменном участке реки Малка в нижнем течении

The analysis of an undergroundsourcewaterchemicalcomposition located inthe floodplain oftheMalka River,the largestriver flowing through the territory of the Kabardino-Balkarian Republic, is presented. Data on the quantitativecontent of the groundwater ion-saltcomposition components serve as indicators to identify background concentrations of pollutants in river waters. The observation results of the intra-annual dynamics of flow, temperature, transparency, pH, mineralization, hardness, permanent oxidability, concentrations of carbonates, bicarbonates, chlorides, sulfates, nitrites, nitrates, and total iron are presented. The qualitative trace element composition has been determined. The results of sanitary and microbiological analysis are presented. The theoretical analysis allows us to conclude that the chemical composition of the water under study follows general patterns. The constancy of the underground source waters temperature indicates the deep occurrence of aquifers. The chemical composition of water is determined by the composition of minerals and rocks, which it comes into contact with, remains almost constant throughout the year and, to a small extent, depends on climatic conditions on the surface. Data on the concentration of components of the ion-salt composition and microflora characterizing the water quality of an underground source were obtained. The water of an underground source refers to neutral, fresh, medium hardness, bicarbonate waters that are not contaminated with pathogenic microflora.

Prospects for fisheries use of lake Sobache (Pionerskoe) in the Republic of Khakassia

We assess Sobache (Pionerskoe) lake located in The Republic of Khakassia for aquaculture using. The lake is drainless, the water-surface area is about 1.5 km2. The prevailing depths range from 2 to 4 m. We provide data on the hydrological regime of the lake (temperature, dissolved oxygen level, chemical water composition). 3 species of rotifers, 10 species of cladoceran and 3 species of copepods were found in the zooplankton. The dominant complex consists of the rotifer Asplanhna priodonta, Bosmina longirostris and Ceriodaphnia quadrangula. The zoobenthos community includes 13 groups of organisms, where chironomids predominate in abundance, and gastropods and bivalves predominate in biomass. The ichthyofauna of the lake consists of perch and pike, perch predominates in abundance. Four species of parasites were found, including trematodes and myxporidia. The infection of fish with trematode metacercariae indicates the presence of intermediate hosts in the zoobenthos community of the lake. The detected species of parasites do not pose a danger to human health. The natural fish productivity is estimated at 48.2 kg/ha. We recommended to use the lake for commercial cultivation of fish in polyculture way. We proposed two schemes of fishery exploitation of the lake on the principle of pasturable fish culture: annual cultivation of fish in polyculture (carp, trout, herbivorous fish species) and joint cultivation of fish in polyculture (carp and white amur) by continuous intensive technology (three-year turnover) with carp feeding. The expected yield of fish products varies from 460.0 to 400.0 kg/ha, depending on the chosen technology. These recommendations can contribute to the effective use of the fisheries potential of Sobache (Pionerskoe) lake to provide the region with fresh fish products and create jobs for the local population.

Temporal variability of water chemistry in the Cherkashinskaya well No. 36-RG (Tobolsk district, Tyumen region)

This article focuses on a temporary change in the chemical composition of water in the Cherkashinskaya well No. 36-RG, which is located in the Tobolsk district near the village of Shestakovo. The impact of underground mineral waters on catchments and watercourses can be caused by the open gushing of orphaned geological exploration wells. This can lead to the disturbance of the hydrochemical regime of neighbouring water systems. Publications on this topic are available not only in Tyumen region, but also throughout the Russian Federation. For example, scientific articles and conference proceedings, such as "Groundwater of the East of Russia" (2018), "Issues of studying surface and groundwater of Siberia" (2021), and the International Conference "Underground Waters 2023", are available. The study highlights the behavior of various components of water composition. The article presents changes in the mineralization of groundwater and identifies the main sources of negative impact on its quality. In 2019, the chemical composition of the water in the containing well underwent a transformation. This article focuses on the changes in the chemical composition of water from the Cherkashinskaya well No. 36-RG and its impact on the surrounding areas.

The phenomenon of Peatmass Change and Its Impact on Water Level in The Regenerated Melaleuca Forest Following a Fire Incident in U Minh Thuong National Park, Vietnam

Purpose: The study was conducted in U Minh Thuong National Park to address forest regeneration. Theoretical framework: After a major forest fire in Vietnam, various measures were taken to promote forest regeneration, including afforestation, silvicultural solutions, and hydrological techniques such as rainwater storage to maintain humidity and prevent future fires. Method: Using a drill hand to collect samples at 15 plots to understand forest growth on three thickness levels of a pea. Each site to collect samples is three; each sample was one kg and coded a member of the site as UTM1, UTM2, UTM3, then gets to the Southern Institute of Forestry Science laboratory for analysis. Results and conclusion: There was a relationship between peat chemical indicators and the evolution of the Melaleuca forest. Peat thickness and flooding regime significantly influenced the growth of the Melaleuca forest, while another identified a relationship between peat chemical indicators and forest growth. Peat water's chemical composition changed considerably during the rainy and dry seasons, with nutrient content and pH affecting forest growth. Peat thickness and flooding regime were essential in regulating forest growth. These studies highlight the importance of considering multiple factors, such as peat thickness and chemical properties, when developing effective forest restoration strategies. Implications of the research: By understanding the relationship between peat thickness, chemical properties, and forest growth, forest managers can develop targeted strategies to promote regeneration while minimizing negative impacts on biodiversity. Originality/value: This study explores the relationship between peat thickness, chemical properties, and forest growth in forest regeneration after major fires. It integrates forestry, ecology, and hydrology to provide a holistic understanding of vegetation dynamics and the importance of peatlands in forest regeneration.

Current Ecological State of the Volga-Akhtuba Floodplain Water Bodies (Using the Example of Dudachenok Shallow Channel)

Current ecological state assessment of the water body located on the Volga-Akhtuba floodplain territory (Dudachenok shallow channel) after its environmental rehabilitation was carried out. It was found that almost all the studied indicators correspond to the approved quality standards with the exception of strontium – 4.5 mg/l (MPC – 0.4 mg/l (Order No. 552 dated December 13, 2016), MPC – 7 .0 mg/l (SanPiN 1.2.3685-21 No. 2 dated January 28, 2021)) and barium – 1.25 mg/l (MPC– 0.74 mg/l (Order No. 552 dated December 13, 2016), MPC – 0.7 mg/l (SanPiN 1.2.3685-21 No. 2 dated January 28, 2021)). It is concluded that it is possible to assign a hydrocarbonate class (predominant anion), calcium group (predominant cation) and second type to a water body. A study of bottom sediments revealed that chloride (36 mg/kg) is one of the predominant anions, calcium (27 mg/kg) and sodium (27 mg/kg) are the predominant cations, which agrees with the obtained water chemical composition data. Chemical and toxicological parameters of bottom sediments were analyzed. It was determined that the quantitative content of metals and pesticides does not exceed the maximum permissible concentrations.

Enrichment of arsenic in the Yarlung Tsangpo basin, Southern Tibetan Plateau: Provenance, process, and link with tectonic setting

Geogenic As enrichment is prevalent in freshwater systems worldwide, yet the connection between such enrichment and regional tectonics remains poorly understood, especially within orogenic environments like the Tibetan Plateau. To provide new insights into the sources and processes of arsenic, as well as its relationship with tectonics in the plateau basin, we selected the Yarlung Tsangpo basin, situated at the collision zone between the Indian (Himalaya block) and Eurasian plates (Lhasa block) as the study area. We analyzed and compared the chemical compositions of waters and sediments across various litho-tectonic domains. This also involved assessing arsenic concentrations in river waters, suspended particulate matter (SPM), sediments, geothermal waters, and rocks. The main findings are as follows: (a) High-arsenic geothermal waters and igneous rocks are common in the Lhasa block, and the discharge of these geothermal waters is the main source of dissolved As in river water, whereas erosion of igneous rocks contributes most of the As in sediments. (b) Metal oxides adsorb dissolved As, which leads to further As enrichment in the sediments. (c) The occurrence of high As concentrations in the southern Tibetan Plateau can be explained by a crustal cycling model. Arsenic likely originated in Neo-Tethys oceanic crustal rocks and was concentrated in the upper crust of the active continental margin (Lhasa block) during geological cycling at convergent plate boundaries. These studies highlight the role of tectonic settings on influencing arsenic enrichment in the plateau basin.

Formation of the Chemical Composition of Water in Northern Baikal in the Zone of Mixing with the Water of Its Tributaries

Formation of the Chemical Composition of Water in Northern Baikal in the Zone of Mixing with the Water of Its Tributaries

Seasonal variations and water chemical control mechanism of water quality in a suburban river near a coal city: a case study in the Xinbian River of Suzhou City, Anhui Province, China

Abstract To study the seasonal change rules of water quality indicators and water chemical control mechanisms in the nearby city river Xinbian River, in Suzhou City, Anhui Province, China, nine points were selected and periodically sampled for 12 months. Totally 108 water samples were collected, and basic physical–chemical indicators and routine ions (e.g., Ca2+, Mg2+, Na+, K+, SO42−, Cl−, F−, NO3−, CO32−, and HCO3−) were measured. Piper diagram, Gibbs diagram, and ion ratio method were used. The result shows that the seasonal and upstream-to-downstream variations in pH were less varied, whereas the fluctuation in dissolved oxygen was large. Four ions, namely, SO42-, F−, Cl−, and Na+ generally first decreased overall and then changed from spring to winter. The maximum contents of SO42- (406.03 mg/L), Cl− (250.22 mg/L), and Na+ (269.99 mg/L) in single water samples appeared at the S9 sampling point (Suzhou control gate) in March 2020. The dominant hydrochemical types in summer were Na–Ca–HCO3 and Na–Mg–SO4, while Na–Mg–SO4 and Na–Mg–HCO3 were the main hydrochemical types in the other seasons. The control factors of water chemical composition vary according to the season. However, rock weathering (e.g., silicate dissolution) is the dominant control factor of water chemistry in the studied river section.

How the catchment-river-lake continuum shapes the downstream water quality

Lakes play a crucial role in the nutrient cycling of Earth, despite covering only a small fraction of the planet’s surface. Their interactions with their surrounding catchment areas significantly impact ecosystems and regulatory services. The connection between a lake and its catchment, especially the drainage ratio (catchment area to lake surface area), shapes the characteristics of lakes and their response to catchment processes. Within the catchment area, geological, land cover, and land use factors influence the composition of stream water that flows into the lake. These factors play a role in transporting various substances, both organic and inorganic, to the streams. Lakes act as dynamic filters, altering the chemical composition of water that flows through them. This study aims to investigate how a large, shallow lake impacts the quality of the river water as it passes through. It builds on an analysis of nutrient (carbon, nitrogen, phosphorus, silicon) fluxes into Lake Võrtsjärv, using six years of monthly monitoring data from five main inflows and the outflow. The research explores how catchment characteristics and hydrology affect nutrient concentrations and loadings into the lake, as well as the retention or release of substances by the lake. Findings reveal that catchment characteristics, such as land use and forest cover, significantly influence water quality parameters. Different inflows showed variations in water quality, and annual variations were observed, largely correlated with precipitation and discharge. Võrtsjärv plays a critical role in retaining or releasing nutrients, with varying impacts depending on the water budget of the lake. In years with a positive water balance, the lake retains all nutrients, whereas in dry years only inflowing N and P loads exceed their outflow. Overall, this study underscores the importance of lakes as integral components of catchment ecosystems, shedding light on their complex interactions with the environment and the implications for water quality. It emphasizes the need for careful consideration of land use and hydrological factors in managing and preserving these vital aquatic systems.

Hydrochemical characteristics of underground fluid observation wells in Shandong

To explore the hydrochemical characteristics of underground fluid observation wells in the Shandong area, piper diagram and Na-K-Mg triangle diagram methods were used to analyze the hydrochemical types and water-rock chemistry of water samples from 18 underground fluid observation wells in the study area. The results show that the hydrochemical types of underground fluid observation wells in the Shandong area are mainly SO4·Cl-Ca·Mg type, HCO3-Na type, HCO3-Ca·Mg type, and SO4·Cl-Na type. The chemical composition of water is mainly affected by water-rock interaction, rock salt dissolution, ion exchange, and human activities. Hydrogen and oxygen isotope analysis results show that atmospheric precipitation is the main recharge source of fluid wells in this area, and deep water recharge also plays an important role in some observation wells. The research results determine the hydrogeochemical background and well water source of underground fluid wells in the Shandong area and provide the scientific basis for fluid observation environment analysis, seismic monitoring and prediction, and seismic anomaly verification in the area.

ОСОБЛИВОСТІ ХІМІЧНОГО СКЛАДУ ПІДЗЕМНИХ ВОД У ТЕРИГЕННИХ ВІДКЛАДАХ ЕОЦЕНУ ТА АЛЬБ-СЕНОМАНУ В БАСЕЙНІ ДНІПРА

Background. The Dniprovsko-Donetskyi Artesian Basin is the largest hydrogeological region of the first order in Ukraine in both area and resources. The main forecasted resources within its boundaries are confined to the Eocene aquifer and the Alb-Cenomanian aquifer complex. These aquifer and complex are the principal ones - they are the basis for centralized water supply of a number of large settlements, so studying their chemical composition is of exceptional importance. The parts of the mentioned aquifer and complex that contain drinking water are identified as groundwater bodies (GWBs) – groundwater monitoring objects for which environmental objectives and risks of failure to achieve these objectives should be determined. At the same time, the natural water quality composition of these groundwater bodies groups is characterized by significant spatial heterogeneity, which should be taken into account when determining trends in its changes and specifying environmental objectives. The aim of the study was to establish the peculiarities of the spatial distribution of water with different chemical composition. The object of the study was aquifers in Eocene and Alb-Cenomanian sediments within the Dniprovsko-Donetsky artesian basin (Dnipro River Basin), and the subject was the chemical composition of water in these aquifers. Methods. To achieve these purposes, data on the chemical composition of the aquifer in the Eocene sediments and the aquifer complex in the Alb-Cenomanian sediments were collected, summarized and analyzed from published and fund sources. The information was processed using geographic information systems, and a database was created to generate specialized maps and perform joint data analysis. Results. In the article the mineralization and macrocomponent composition of groundwater in the terrigenous sediments of the Eocene and Albian-Cenomanian of the Dnipro basin are investigated and the peculiarities of their spatial distribution are established. Particular attention is paid to the areas where the exploitation reserves of both groundwater aquifers are explored. The qualitative, including microcomponent, composition of groundwater in terrigenous sediments of the Eocene and Albian-Cenomanian in Chernigiv City was characterized in detail. Peculiarities of formation of the chemical composition of groundwater in terrigenous sediments of the Eocene and Albian-Cenomanian were established. Сonclusions. It has been established that despite the fact that both GWBs are located in the zone of active water exchange, the content of macro- and microcomponents in them is quite different. In particular, in the water in the Alb-Cenomanian sediments, the macrocomponent composition of water is more homogeneous, and the content of macro- and microcomponents is characterized by a smaller range of variation. The identified peculiarities of the natural quality composition of the studied GWBs should be taken into account in the process of groundwater monitoring, in particular, when specifying environmental objectives and determining the frequency of groundwater quality state observations.

Identification of Hydrochemical Characteristics, Spatial Evolution, and Driving Forces of River Water in Jinjiang Watershed, China

Rivers are an important source of water in humid regions, but their availability is greatly limited by water chemistry. In order to accurately identify the changes in river water chemical composition, the compositional analysis method (CoDA) is proposed from the perspective of compositional data analysis theory, which considers the geochemical riverine system as a whole and detects the compositional changes of the entire watershed. The basic data analysis is carried out by traditional analysis methods, and the results show that the hydrochemical characteristics of different sections of the basin have significant features. The water chemistry of Dongxi River is of the HCO3− Ca type. The water of the Xixi River shows a gradual evolution from the HCO3-Ca type and high SO42− content in the upper reaches to the Cl-Ca type in the lower reaches. The hydrochemistry of river water in the watershed is mainly affected by rock weathering leaching (PC1) and agricultural and domestic pollutant discharge (PC2), with a contribution rate of 48.4% and 19.7%, respectively. Rock weathering, mining, and agricultural pollution are the main factors affecting the chemical composition of river water in different regions. The spatial composition of a single sample at different scales is monitored by the Mahalanobis distance approach in an iterative manner to minimize the influence of a single anomaly on the composition center. The results show that the main reasons for the change in river water chemical composition along the Xixi River are attributed to mine pollution, domestic pollution, and tea plantation and that along the Dongxi River is caused by domestic pollution. The hydrochemical composition changes after the confluence of the Xixi River and Dongxi River are mainly affected by human activities and seawater in urban areas. This research could provide new perspectives and methods for detecting the influences of human and natural factors on the hydrochemistry of river water in humid regions worldwide.