Metamorphization of zonal hydrochemical composition of surface and groundwater of Ukraine under the influence of anthropogenic and natural factors

An integrated method of functional diagnostics of basin geosystems through quantitative assessment of anthropogenic (drainage reclamation) or natural factors (climate) on the change of hydrochemical composition of surface and groundwater is presented. The method is based on the natural latitudinal and vertical zonation of the hydrochemical composition of surface and groundwater, as a manifestation of the geomembrane properties of the pedosphere. The stages of the quantitative assessment of the impact of increasing drainage reclamation areas in the Styr and Irpin river basins, were a linear regression analysis of chronological series of the content of each of the macrocomponents of the river water composition in the closing line for 1947-1989, and also the dynamics of increasing reclamation areas and correlation analysis of the obtained dependencies. To increase the closeness of the correlation, the hydrochemical composition was presented in %-equivalent form, which most accurately characterizes the ratio of macrocomponents, but does not depend on the total mineralization of water. A decrease in the content of such typomorphic ions as hydrocarbons and calcium and an increase in the content of other macrocomponents and mineralization were found statistically significantly with increasing drainage areas. In general, with increasing areas of drainage reclamation, there is an aridization of the hydrochemical composition of river water. The change of hydrochemical type of river water according to the classification of О.О. Alekina. The obtained parametric models of time trends of the content of macrocomponents of hydrochemical composition allowed to determine the limiting area of reclamation of the basins of two rivers and to predict changes in the hydrochemical type of water in the direction of its aridization. Stopping the construction of new reclamation systems and reducing the efficiency of agricultural use of drained lands leads to the restoration of the hydrochemical composition of rivers in the direction of their reclamation development. Approbation of the created method of functional diagnostics was carried out on five reclamation systems of Prykarpattia and in the basin of the Western Bug river and its branches proved its high efficiency and perspective for the creation of parametric models of the influence of natural and anthropogenic factors on chemical composition and quality of water resources.

Geochemical Features of the Thermal and Mineral Waters From the Apuseni Mountains (Romania)

The Apuseni Mountains are located between the large geothermal area of the Pannonian Basin and the low thermal flux Transylvanian Basin. Thermal and mineral waters have been sampled from 42 points along a NW-SE transect. The general chemistry and the water isotope (deuterium and oxygen-18) composition were analyzed. Most of the thermal aquifers are located in carbonate reservoirs. The waters mainly belong to the Ca-HCO3 hydrochemical type, excepting the western side, towards the Pannonian Basin, where the Na-HCO3 type may occur. The isotope composition indicates aquifer recharge from precipitation. The geochemical characteristics and the structural position of the study area suggest two distinct geothermal contexts. The Southern Apuseni area geothermal features are likely connected to the Neogene—Early Quaternary magmatic activity from the Mureş Valley and Zarand Depression. The geothermal manifestations in the north-western part of the study area, at the border between the Northern Apuseni and the Pannonian Depression, share features of the latter one.

Groundwater Hydrochemical Characteristics in a Plain River Network Region: Effects of Dissolved Organic Carbon and Possible Traceability of Pollution Sources

The chemical composition of groundwater indicates the water quality and provides useful information for identifying pollution sources. The aim of this study was to explore the effects of dissolved organic matter inputs on the ionic composition of groundwater and identify ions that can be used as indicators of pollution sources. Descriptive statistics, a Piper diagram, a Gibbs plot, major ion ratios, and Pearson’s correlation coefficients were used to analyze the chemical data of 40 groundwater samples collected from the shallow aquifer surrounding Lake Taihu. The results showed that the water quality index values of most sampling points were less than 50 (excellent water quality), except for one point in the southeast direction of the lake basin (good water quality). The dominant hydrochemical type of groundwater was Ca–Mg–HCO3 type, and rock dominance was the major mechanism controlling the groundwater chemistry. With an increasing concentration of dissolved organic carbon, the Na+, Mg2+, and HCO3- concentrations all showed a sharp increase followed by a slow increase, while the NO3– concentration initially decreased sharply and then decreased slowly. The K+ concentration was positively correlated with total dissolved nitrogen and phosphorus, nitrate, As, and Cd concentrations (p < 0.05). The Ca2+, Na+, Mg2+, Cl-, HCO3-, and CO32- concentrations were all positively correlated with Pb concentration (p < 0.001). The results indicated that high organic matter inputs can directly or indirectly change the hydrochemical type of groundwater, and K+ can be used as a tracer ion for the sources of As and Cd in groundwater in the study area.

Geochemical Characteristics of Alluvial Aquifer in the Varaždin Region

The variation in the major groundwater chemistry can be controlled by dissolution and precipitation of minerals, oxidation-reduction reactions, sorption and exchange reactions, and transformation of organic matter, but it can also occur as a result of anthropogenic influence. The alluvial aquifer represents the main source of potable water for public water supply of the town Varaždin and the surrounding settlements. Sampling campaigns were carried out from June 2017 until June 2019 to collect groundwater samples from nine observation wells. Major cations and anions, dissolved organic carbon and nutrients were analyzed in the Hydrochemical Laboratory of Croatian Geological survey. The sampled waters belong to the CaMg-HCO3 hydrochemical type, except the water from observation well P-4039 that belongs to NaCa-HCO3 hydrochemical type. It was identified that groundwater chemistry is mainly controlled by hydrogeological environment (natural mechanism), but anthropogenic influence is not negligible. The results of this research have significant implications on sustainable coexistence between agricultural production and water supply.

Hydrochemical characteristics and influencing factors of mine water in Tangjiahui mining area

In water-deficient areas, the reuse of water discharged from coal mining is highly desirable. In order to study the water quality in the Tangjiahui mining area in Jungar Coalfield (Inner Mongolia, China), 34 groups of mine water samples collected at various stages during coal mining process were analyzed for their hydrochemical characteristics using conventional and statistical methods. A Piper trilinear diagram was used to analyze the main ion composition characteristics and the hydrochemical type of the mine water. Gibbs map and ion correlation methods were used to investigate the sources and influencing factors of the main ions in mine water. The results showed that the TH of the mine water in the study area was in the range of 219.52–390.6 mg/L with an average of 315.04 mg/L, which can be classified as slightly hard/ hard water. The TDS was in the range of 926.61–1889.56 mg/L with an average of 1514.31 mg/L, which mostly belongs to brackish water. The cation content in the mine water was ranked from the highest to the lowest as Na + > Ca 2+ > Mg 2+ , while the anion content was ranked as Cl − > HCO 3 − > SO 4 2− . The Na + mass concentration was in the range of 179.00–523.06 mg/L with an average of 399.77 mg/L, while the Cl − mass concentration was in the range of 207.10–812.63 mg/L with an average of 550.88 mg/L. The hydrochemical type of the mine water was Cl-Na. According to the correlation matrix of the various chemical indicators in the mine water, the TDS was significantly positively correlated with Na + , Ca 2+ , Cl − , and SO 4 2− . Of these, the main sources of TDS were Na + and Cl − , as these had correlation coefficients > 0.9. The hydrochemical characteristics of the mine water were mainly controlled by the condensation-crystallization and anti-cation exchange, which indicated the main ions were largely derived from the dissolution of halite . Due to its high TDS, EC,SAR, and Na% values, the mine water in the study area was not suitable for human consumption and agricultural irrigation. These results can provide a reference towards water resource management and the sustainable use of mine water by local governments.

Irrigation water quality may improve in arid regions of China

The stability and safety of water environment are the foundation of agricultural development. The possibility of salinization and desertification in the oasis agricultural area is much higher than that in other areas, for the population density, lack of water resources and high salinity. Therefore, it is necessary to study the water environment of irrigation water in this area, so as to make a reasonable water resource utilization and protection plan. In the agricultural irrigation period (from Apr. to Sep.) and non-irrigation period (from Oct. to Mar. of the next year), there were 9 sampling points set up from the source area to the oasis of the middle and lower reaches in Shiyang River Basin. Evaluating the irrigation water quality of surface water by ion concentration, SAR and end-member mixing diagram. The results shown: (1) the dilution effect of precipitation has a decisive influence on the ion concentration of surface water in the watershed. Due to the overlapping of irrigation period and rainy season, rainfall dilution makes irrigation water quality better. (2) There are spatial differences in hydrochemical types. The upstream hydrochemical type is mainly Ca-HCO3 type. The hydrochemical type of the middle and lower reaches is Ca (Na) - HCO3 mixed type. The upstream surface water is very suitable for agricultural irrigation, and the middle and downstream oasis area is suitable. (3) Surface rock weathering and evaporation crystallization are the main factors affecting the hydrochemical characteristics of surface water. Due to changes in the underlying surface environment in a short time, it is unlikely that the water quality will deteriorate. (4) In recent years, with the increase in precipitation caused by climate change and the strict environmental protection policies, the risk of deterioration of irrigation water quality is greatly reduced, surface water may be more suitable for agricultural irrigation.

Modern carbonate formation in low-mineralized flowing waters

Continental carbonate formation in low-mineralized flowing waters of temperate latitude is rare phenomenon. Taking this into account a study was conducted of crustate and stalactite-like authigenic calcite aggregates formed in the thalwegs of the ravines of the Volga Upland. According to chemical and isotopic analysis, modern carbonates are formed from poorly mineralized, meteoric waters of medium hardness, hydrocarbonate-magnesium-calcium hydrochemical type. It has been established that newly formed carbonate aggregates are characterized by the predominance of lightweight carbon and oxygen in the crystal structure. The osmotic hypothesis of the formation of lime-calcite aggregates is proposed.

Analysis of the Hydrochemical Characteristics and the Evolutionary Stages of Brine in Mahai Salt Lake in the Qaidam Basin

The objective of this study was to contribute to the understanding of the hydrochemical processes and evolution of brine in the Qaidam basin, in order to provide a theoretical basis for the application of brine resources in the region. The hydrochemical characteristics and evolutionary stages of brine in Mahai Salt Lake were investigated using factor analysis on brine chemistry data from 109 sampling points. Our results showed that the centre of the Salt Lake has the highest concentration of total dissolved solids (TDS), and the hydrochemical type of brine is chloride-magnesium. The brine at the centre of the lake is at the later stages of mirabilite precipitation, and the content of K+ is relatively stable. Comparatively, the hydrochemical type of brine in the slope area of the Salt Lake is Cl-Na-Mg, and is at the early stages of brine evolution. It is of guiding significance to further develop and utilize brine resources, especially to evaluate its resource development potential.

Hydrochemistry and Environmental Isotope Characteristics of Groundwater in the Kashgar Delta Area, Xinjiang, China

The hydrochemistry and isotope characteristics of groundwater of different geomorphological types in the Kashgar Delta in Xinjiang, China were studied using isotopic analyses. Results showed that groundwater in the study area was mainly recharged by precipitation, and that groundwater ions were mainly affected by weathering-leaching of rock salt and evaporite as well as cation exchange and adsorption. The hydrochemical type of phreatic water in the alluvial-proluvial gravel plain on the piedmont slope was mainly SO4·Cl-Na·Ca type, with an average age of 28a. The phreatic water in the fluvial plain had shallow buried depth and intense evaporation. The hydrochemical type of phreatic water varied from SO4·Cl-Na·Mg type to Cl-Na type, with an average age of 99a. Along the groundwater flow path eastward, confined water in the fluvial plain experienced gradually more intense cation exchange and stronger adsorption. The major hydrochemical type of which was the SO4·Cl-Na type, with an average age of 30405a.

HYDROCHEMICAL STUDY OF THE HOT GROUNDWATER OF AMPELIA AREA, EASTERN THESSALY, GREECE. A NEW AREA WITH GEOTHERMAL INTEREST

Ampelia area is a newly discovered area with geothermal interest and no surface manifestations (hidden resource). It is located in Farsala basin and belongs to the Enipeas graben. The geothermal anomaly is related with the E-W trending faults, which mainly control the basin development and the NNW-SSE trending faults of the area. The temperature values from the deep water boreholes (>200m depth) range from 20 to 41oC. The chemical composition of the studied groundwater samples varies in all chemical parameters. Most of the samples have affected by shallow cold aquifers (high E.C. and NO3- values). The most representative samples (T > 30oC) are from the deepest boreholes (hydrochemical type Na-HCO3), which cut the fractured crystalline basement, i.e. limestones, flysch and ophiolitic rocks. They present the highest pH values (pH > 8) and the lowest E.C. compared with the rest of the samples. Their Ni and Cr concentrations are very low, indicating that the groundwater is notin contact with the ultramafic rocks from the ophiolite sequence. According to silica chemical geothermometers for the most representative samples, the expected temperature values of a potential geothermal reservoir range from ~ 60 to 100oC.