[Hydrochemical Characteristics and Water Quality Evaluation of Groundwater in the Hualiangting Reservoir Basin of Taihu County].

This study focused on the Hualiangting Reservoir Basin in Taihu County, where 42 well water samples and 20 spring water samples were collected to measure the primary hydrochemical indicators. Using a comprehensive suite of methods including mathematical statistics, Piper diagrams, Gibbs diagrams, ion ratios, and factor analysis, the study examined the characteristics and influencing factors of well and spring water within the area. Water quality was assessed based on the entropy-weighted quality index （EWQI）, and the potential risks associated with nitrate （NO₃^-） levels in the groundwater were evaluated using the health risk assessment model （HHRA）. The results indicated that the groundwater was generally weakly alkaline, with sodium （Na⁺）, calcium （Ca²⁺）, and bicarbonate （HCO₃^-） being the predominant ions. The hydrochemical type was mainly characterized as the bicarbonate-sodium-calcium type. The formation of wells and spring water was primarily influenced by rock weathering and cation exchange adsorption. The main sources of Ca²⁺, magnesium （Mg²⁺）, and HCO₃^- in the groundwater were carbonate dissolution, while agricultural activities and domestic sewage discharge led to increased concentrations of Na⁺, chloride （Cl^-）, and NO₃^-. Overall, the water quality in the area was good, ranging from fair to excellent. The health risk assessment demonstrated a low non-carcinogenic risk for men, women, and children, with children facing a significantly higher risk compared to that of adults. The findings of this study provide valuable guidance for the sustainable development, utilization, and protection of groundwater resources in the Hualiangting Reservoir Basin.