Shuiwen dizhi gongcheng dizhi (Sep 2023)
Characterization and causes of interannual variation of antimony contamination in groundwater of a typical antimony mining area
Abstract
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, especially the Shetianqiao Formation aquifer, with an average antimony concentration of 7.139 mg/L, which is significantly affected by the oxidation of pyroxene. The sources of antimony in the Xikuangshan Formation and the Lower Carbonifer aquifer are mainly controlled by the leaching of solid waste such as tailings and waste rocks. (3) The average value of antimony mass concentration in groundwater in the Shetianqiao Formation aquifer varies greatly during the 10 years. From 2013 to 2015, the average value of antimony concentration was 13.31 mg/L, decreasing year by year. From 2016 to 2018, the average value of antimony concentration is 7.28 mg/L, increasing slightly year by year. From 2019 to 2022 the average value of antimony concentration is 6.06 mg/L, with an overall decreasing trend. Analysis shows that the ecological environment in the mining area is gradually improving. This study will provide a scientific basis for assessment of the effectiveness of the implementation of ecological restoration projects in mining areas, as well as the prevention and control of heavy metal pollution in mining areas.
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