[Heavy Metal Pollution and Health Risk Assessment in Karst Basin Around a Lead-Zinc Mine]

Water quality is one of the most important environmental issues in the sustainable development of karst areas. To investigate heavy metal pollution and assess health risk in karst water basins around mines, 18 groups of water samples were collected from the river and groundwater in the Sidi River karst basin, and the concentrations of nine types of heavy metals(Cu, Pb, Zn, Cd, Mn, Fe, As, Cr, and Sr) were determined. Sample data were analyzed using principal component analysis, correlation analysis, water quality index, the Nemerow comprehensive pollution index, hazard quotient, and hazard index. The results showed that the Sidi River was slightly alkaline. The farther the river water samples were from the tailings reservoir, the lower were the concentrations of Cu, Pb, Zn, Cd, Mn, Fe, As, and Sr in the river water. Principal component and correlation analyses showed that heavy metals in the Sidi River karst basin mainly came from mine discharge(55.42%), carbonate weathering dissolution(21.41%), and human activities(14.72%). Eighty-two percent of the samples in the river and all the samples in the groundwater were excellent water. The Nemerow comprehensive pollution index in the river was 4.12 with strong pollution. All the hazard indices were below 1, and Pb, Zn, As, Cd, and Cr were potentially threatening metals in the Sidi River karst basin. The concentration of heavy metals changed significantly after entering the karst conduit, indicating that the unique properties of the karst aquifer affected the spatial variation of the heavy metal concentration. The results of this study can provide data reference for water resource prevention and human health protection in the Sidi River karst basin and similar karst basins.