[Hydrochemical Characteristics of Groundwater and the Origin in Alluvial-proluvial Fan of Qinhe River].

To study the hydrochemical characteristics of groundwater and the factors controlling the alluvial-proluvial fan of the Qinhe River, 60 samples were collected including 9 surface water samples and 51 groundwater samples. The distribution characteristics of the hydrochemistry and major controlling factors of hydrochemical evolution processes of surface water and groundwater in the study area were analyzed by using mathematical statistics, the Schakerev classification, Piper diagrams, Schoeller diagrams, Gibbs plots, and ion ratios. The results show that:① the major anions and cations of surface water and groundwater in the study area are Ca ²⁺ , Mg ²⁺ , SO ₄ ^2- , and HCO ₃ ^- . The recharge sources of surface water and groundwater are closely related; ② the major hydrochemical types of the groundwater are HCO ₃ -Ca, HCO ₃ -Ca·Mg, and HCO ₃ ·SO ₄ -Ca·Mg, while the major hydrochemical type of surface water is HCO ₃ ·SO ₄ -Ca·Mg; and ③ the major ions of surface water and groundwater are affected by carbonate mineral weathering and dissolution, ion exchange, and evaporation. Sulfuric acid and carbonic acid were involved in carbonate mineral weathering and dissolution.