Hydrogeochemical Characteristics and Quality Assessment of Groundwater in Xingtai Selenium-Enriched Area, Central...

In this study, a total of 103 groundwater samples were collected from four subareas in the Xingtai Se-enriched area, central North China to explore controlling factors of hydrochemical components and suitability for drinking and irrigation purposes. The results indicate that the groundwater exhibits neutral to slightly alkaline properties. Piper diagram classifies the major groundwater types as SO₄-Ca and Cl-Ca·Mg. Integrated hydrochemical analyses (Gibbs and Gaillardet diagrams, ionic ratios, Chloro-Alkali Index, and Saturation Index) together with statistical approaches (Pearson's correlation analysis and principal component analysis) reveal that hydrogeochemical evolution is governed by water-rock interactions (dissolution of calcite, dolomite, fluorite, gypsum, pyrite, and halite), cation exchange, and anthropogenic influences. Nonpoint sources (fertilizers, manure, and sewage) contribute to the elevations of NO₃ ^- and Cl^- concentrations. Water Quality Index (WQI) assessments indicate 80.58% of samples are suitable for drinking. SO₄ ^2- and NO₃ ^-are identified as key triggers of water quality deterioration, which are linked to carbonate rock dissolution, cation exchange, sulfur-containing minerals dissolution (gypsum and pyrite), and anthropogenic pollution (fertilizers and sewage). USSL classifications indicate 44.67% of samples are suitable for irrigation, contrasting with 1.94% deemed unsuitable, whereas Wilcox diagram categorizations show 43.68% as excellent-to-good and 2.91% as unsuitable. The findings can provide scientific guidance for rationally utilizing the valuable local Se-enriched groundwater resource on the premise of balancing exploitation with protection against hydrogeochemical and anthropogenic contamination.