[Hydrochemical Characteristics and Origin of Centralized Groundwater Drinking Water Source in Fuyang City]

Groundwater quality is impacted by the exploitation of residential sewage and industrial and agricultural activities. Groundwater is an important source of drinking water in Fuyang City. In this study, to investigate the hydrochemical characteristics and formation mechanism of the centralized drinking water source in the Fuyang area, a total of 84 sets of groundwater samples were collected. Different techniques, such as the Piper three-line diagram, Gibbs map, correlation analysis, ion proportional coefficient, and factor analysis, were used to reveal the groundwater chemical characteristics, mechanisms of hydrochemical components, and control factors. The findings showed that the ion sources of Ca²⁺-SO₄^2- were weakly correlated and could not coexist in large quantities. Ion sources of groundwater such as Na⁺-Cl^-, F^--B³⁺, Ca²⁺-Mg²⁺, SO₄^2--Cl^-, and Na⁺-SO₄^2- were the same, while the ion sources of Ca²⁺-Na²⁺, Ca²⁺-HCO₃^-, and Mg²⁺-HCO₃^- were different. The results showed that the water body of the concentrated groundwater source in Fuyang City included neutral, alkaline, high salinity, and hydrochemical types （HCO₃-Na）. The groundwater components are mainly affected by the leaching of aquifer rocks and minerals, and the alternating adsorption of cations. Ca²⁺ and Mg²⁺ in groundwater mainly come from the dissolution of calcite. Na⁺ of sodium-containing minerals exchanged with Ca²⁺ and Mg²⁺ in groundwater. The ionic characteristics of groundwater were affected by rock weathering and evaporation. Moreover, rock weathering was more obvious, and external factors changed the ionic composition of groundwater. Thus, the concentration of Na⁺ increased and accumulated in groundwater, while the concentration of Ca²⁺ and Mg²⁺ decreased. Hence, hydrochemical characteristics were related to residents' drinking water health and safety.