Hydrochemical Characteristics, Mechanisms of Formation, and Sources of Different Water Bodies in the Northwest Coal-Electricity Agglomeration Area

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.