[Hydrochemical and Stable Isotopic Characteristics and Transformation Relationship of Water Bodies in the Guohe River Basin, Anhui Province]

The Guohe River Basin in Anhui Province was selected as the research area for this study. By collecting surface water, shallow groundwater, and middle-deep groundwater samples, various hydrochemical parameters and stable isotopes of water in different water bodies were analyzed using methods such as the Gibbs diagram, ion ratios, and MixSIAR model to reveal and quantify the transformation relationships between these water bodies. The results indicated that both surface water and groundwater in the study area were predominantly neutral to weakly alkaline. The hydrochemical types of surface water were mainly characterized by Cl·SO₄·HCO₃-Na and Cl·SO₄-Na types, whereas the shallow groundwater exhibited HCO₃-Ca·Mg and HCO₃-Mg·Na types, and the middle-deep groundwater was of the Cl·HCO₃-Na type. The hydrochemical characteristics of various water bodies were influenced by multiple factors such as rock weathering, evaporation concentration, and positive cation exchange. The distribution characteristics of δ¹⁸O and δ²H values in surface water and groundwater indicated that atmospheric precipitation was the main water source. The δ¹⁸O and δ²H in groundwater were significantly correlated with K⁺, Na⁺, Cl^-, SO₄^2-, and NO₃^-. According to the analysis using the MixSIAR model, the contribution of atmospheric precipitation to surface water was 46.5 %, whereas the contribution from shallow groundwater was 53.5 %. The sources of shallow groundwater were identified as atmospheric precipitation (57.4 %) and surface water (42.6 %), and the main source of supply for middle-deep groundwater was lateral flow from upstream groundwater.