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Water resources are relatively scarce in Northwest China. Therefore, this study aimed to identify the hydrochemical characteristics and sources of different water bodies in the Northwest Coal–Electricity Agglomeration area, and the utilization of water resources in the region. Hydrochemical diagrams and correlation analysis were applied to data obtained through the collection of 40, 14, and 42 surface water, shallow groundwater, and deep groundwater samples, respectively. The Positive Definite Matrix Factor Decomposition (PMF) model was used to explore the origins of ions in different water bodies. The results show the following: (1) The rank of anions in surface water, shallow groundwater, and deep groundwater in water bodies of the Bulianta mining area during the wet period according to concentration was as follows: SO42− > Cl− > HCO3− > NO3−; that of cations was as follows: Na+ > Ca2+ > Mg2+ > K+; (2) The chemical composition of surface water is mainly regulated by the dissolution of evaporites; that of shallow groundwater was regulated by silicates; that of deep groundwater was mainly regulated by the hydrolysis of silicates and the dissolution of evaporites; (3) Four main sources of ions in different water bodies were identified, namely agricultural activities, rock weathering, primary geology, and unknown sources. Two natural factors, namely rock weathering and primary geology, and human activities contributed to 35.2% and 38.8% of ions in shallow groundwater, respectively. Rock weathering and human activities contributed to 20.6% and 63.9% of ions of deeper groundwater, respectively. This study can provide a basis for the conservation and rational planning and utilization of water resources in the Northwest Coal–Electricity Agglomeration area. [ABSTRACT FROM AUTHOR]

The Dongting Lake Plain is a major ecological reserve for river and lake wetlands in the Yangtze River Basin, with complex river and lake relationships and frequent water flow exchange. Studies on the hydrochemical characteristics and the mechanism of interaction between groundwater and surface water will actively promote the scientific management, utilization of water resources, and protection of the ecological environment in the Dongting Lake Plain. Based on hydrogeochemical statistics, Gibbs diagrams, ion ratios, rock weathering end-element diagrams, hydrogen–oxygen isotope relationship diagrams, and other technical methods, the chemical characteristics, ion sources, and the distribution of hydrogen–oxygen isotopes of groundwater and surface water in "the Three Inlets" and "the Four Rivers" water system areas as well as the Dongting Lake water were analyzed. Additionally, the interactions between groundwater and surface water and the proportions of these contributions were discussed. The results show that both groundwater and surface water in the Dongting Lake Plain are weakly acidic or alkaline, and the anions are mainly HCO3−, the cations are mainly Ca2+and Mg2+, with the hydrochemical types being mainly HCO3−Ca−Mg and HCO3−Ca. The chemical characteristics of groundwater and surface water are mainly affected by the interaction between water and rock; the ions in surface water mainly come from the weathered dissolution of carbonate and silicate rocks, while the ions in groundwater mainly come from the weathered dissolution of carbonate and silicate rocks, with the dissolution of evaporite rocks locally. Groundwater and surface water are mainly distributed near the local meteoric water line (LMWL), and the slope of the local evaporation line is less than that of the LMWL, which indicates that atmospheric rainfall is an important recharge source for groundwater and surface water and that at the same time, it is affected by evaporation to a certain extent. Part of the groundwater in the Dongting Lake Plain is discharged into the surface rivers in "the Three Inlets" and "the Four Rivers" water system areas, and the other part is directly discharged into Dongting Lake. According to the mass balance relationship of isotopes, the proportions of surface water in "the Three Inlets" and "the Four Rivers" water system areas contributing to Dongting Lake's water are 18.48% and 60.38%, respectively, and the proportion of groundwater in the lake plain contributing to Dongting Lake water is 21.14%. [ABSTRACT FROM AUTHOR]

The assessment of the suitability and status of irrigation water quality from the aspect of its potential negative impact on soil salinization and mapping of spatial distribution within the area of the three Morava rivers, which includes the South, West, and Great Morava basins, was the purpose of this research. A total of 215 samples of irrigation water were tested, and their quality was evaluated based on the analysis of the following parameters: pH, electrical conductivity (EC), total dissolved salt (TDS), sodium adsorption ratio (SAR), and content of SO42−, Cl−, HCO3−, CO3 2−, Mg2+, Ca2+, Na+, and K+. The results showed that the average content of ions was as follows: Ca2+ > Mg2+ > Na+ > K+ and HCO3− > SO42− > Cl− > CO32−. The assessment of irrigation water suitability was determined by calculating the following indices: percentage sodium (Na %), residual sodium carbonate (RSC), permeability index (PI), magnesium hazard (MH), potential salinity (PS), Kelley's index (KI), total hardness (TH), irrigation water quality index (IWQI). Based on Wilcox's diagram, the USSL diagram, and the Doneen chart, it was concluded that most of the samples were suitable for irrigation. Using multivariate statistical techniques and correlation matrices in combination with other hydrogeochemical tools such as Piper's, Chadha's, and Gibbs diagrams, the main factors associated with hydrogeochemical variability were identified. [ABSTRACT FROM AUTHOR]