Hydrochemical characteristics and identification of pollution ions of the springs in the south of Yanbian City, China

Abstract

Mathematical statistics, correlation analysis, Piper and Gibbs diagrams, and geographic information system- based multi-criteria decision analysis were used to study the hydrochemical characteristics and identification of hydrochemical ions affected by human activities of the springs in the south of Yanbian City, China. Four criteria were selected: land use/land cover, village density, distance to towns, and distance to main roads. The improved entropy method was used to assign weight to each criterion, followed by evaluating the human activities impact index map, which was used to extract the human activities impact index of springs. The correlation coefficient was calculated to identify the hydrochemical parameters affected by human activities. The results show that the main hydrochemical parameters are Ca²⁺ among cations and HCO₃^- among anions. Ca²⁺, Mg²⁺, HCO₃^-, Cl^-, and total dissolved solids (TDS) have a strong correlation and similar spatial distribution, showing a decreasing trend from northwest to southeast. Most hydrochemical parameters show a similar spatial distribution trend. The hydrochemical types of springs are HCO₃-Ca, HCO₃-Ca•Mg, HCO₃-Na•Ca, and HCO₃-Ca. In the study area, Na⁺, K⁺, TFe, Mn²⁺, F^-, PO₄^3-, and oxygen consumption are negligibly affected by human activities, Mg²⁺, HCO₃^-, and Cl^- were slightly affected, and TDS and total hardness (TH) were strongly affected. With a correlation coefficient of 0.913, nitrate exhibited the highest correlation with the human activities impact index; it was significantly affected by human activities. We conclude that nitrate was the most affected by human activities, followed by TH, TDS, and other hydrochemical parameters.

Keywords: GIS; Human activities; Hydrochemical parameters; Improved entropy method; Spring.