Characterization and causes of interannual variation of antimony contamination in groundwater of a typical antimony mining area

Heavy metal pollution is a prominent problem in the antimony mining area of Xikuangshan in central Hunan. In recent years, integrated waste remediation and ecological restoration projects have been vigorously implemented in mining areas, but the effectiveness of groundwater pollution remediation is unknown. Groundwater samples collected from the antimony mining area for 10 consecutive years from 2013 to 2022 are used to systematically study the chemical characteristics of groundwater, the inter-annual variation characteristics of antimony pollution, and the sources and pathways of antimony contamination by the hydrochemistry analysis, ion correlation analysis, and geostatistics. The results show that (1) the HCO3·SO4—Ca type is the main hydrochemical type of groundwater in Xikuangshan, and the formation process of chemical components in the groundwater is controlled by solid waste leaching and salt rock dissolution. (2) Three aquifers in the mining area are contaminated with antimony to different degrees, esp