Characteristics and Driving Factor of Hydrochemical Evolution in Karst Water in the Critical Zone of Liupanshui Mining Area

The surface water and groundwater which are critical resources for daily life, industrial and agricultural production exchange frequently in Liupanshui mining area.To ensure the security and sustainability of water system in the karst critical zone, thirty-three water samples were collected from the typical Liupanshui mining area in September 2015. They were analyzed by using the methods of hydrochemistry, correlation analysis and ion ratios. The results show most groundwater hydrochemical type was CaHCO₃ type, and some was Ca-SO₄ type. Most surface water was Ca-HCO₃ type and Ca-SO₄ type. Differently, the mine waste water was Na-HCO₃ type and the acid mine waste water was Ca-SO₄ type. There was a significant positive correlation between Ca²⁺, Mg²⁺ and HCO₃^- which was mainly controlled by reaction between water and carbonate, and some Na⁺ and K⁺ were controlled by reaction between water and silicate. The sources of Cl^- were mainly sewage, most of NO₃^- were affected by agricultural production, and SO₄^2- came from multiple sources. Mining activities, urbanization and agricultural production have affected the compositions of water ions, in addition mining activities have accelerated the dissolution of carbonate. These three factors have made significant changes in the hydrochemistry types. Under these compound influences affected by human activities, mining activities are the key driving factors for the changes of hydrochemical characteristics in water system of the karst critical zone.