[Groundwater Chemical Characteristics, Control Factors, and Health Risks in the Dahei River Basin of Typical...

As an important ecological security barrier and core area for economic development in China, mastering the groundwater aquatic environment status of the basin is of great significance for the ecological protection and high-quality development of the Yellow River Basin. In order to explore the main controlling factors of groundwater hydrochemistry and health risks in typical tributary basins, based on the test data of 135 sets of groundwater samples from the Dahei River Basin in 2023 during abundant and depleted periods, we analyzed and explored the characteristics of the groundwater hydrochemistry and the main controlling factors in different periods by using mathematical statistics, Piper's trilinear diagrams, Gibbs' diagrams, ionic ratios, and PMF source analysis. We also applied the entropy-weighted water-quality index （EWQI） and health risk assessment model （HHRA） to evaluate the groundwater quality and health risk. The results showed that： ① The groundwater in the Dahei River Basin was weakly alkaline, mainly hard and medium-hard freshwater, and the primary hydrochemistry was of HCO₃-Ca·Mg type. ② The quality of groundwater was better in general, and the quality of groundwater was better during the period of abundant water than that during the period of depletion. The order of the risk of non-carcinogenic health effects on different groups of people was as follows： infants>children>female>male, and the risk of non-carcinogenic health effects was generally higher during depletion than that during the abundant water period. ③ The formation of groundwater hydrochemistry was mainly controlled by water-rock interactions and cation exchange, with Na⁺ mainly derived from the dissolution of silicate rock salts and Ca²⁺, Mg²⁺, and HCO₃^- mainly derived from the dissolution of carbonate rocks. ④ The PMF source analysis identified four influencing factors, namely, water-rock interaction-agricultural activities, domestic wastewater-industrial activities, agricultural-industrial activities, and the factor of evaporation and concentration, The contribution ratio of the influencing factors in different hydrological periods varied, with water-rock action-agricultural activities dominating in the abundant water period, while human activities and evaporation concentration were more prominent in the dry water period. By revealing the control factors of groundwater hydrochemistry and their health risks in typical tributaries of the Yellow River Basin, scientific references can be provided for the control and management of regional groundwater quality standards.