Effects of environmental governance in mining areas: The trend of arsenic concentration in the environmental media of a typical mining area in 25 years

Abstract

China has considered different environmental management measures (EMMs) in mining areas. However, their effects remain unclarified. In this study, the achievements and limitations of different EMMs of a typical mining area—Huangchang realgar mine—located in Hunan province were explored. The variations in the arsenic concentrations in the soil, agricultural products, drinking water, and atmosphere in 25 years of EMM implementation were investigated. Source control measures, such as ceasing mining and smelting activities, disposal of waste residues, and purifying wastewater, significantly reduced the arsenic concentrations in the atmosphere and surface water by more than 99%—from 68 μg m−3 and 0.42 mg L−1 to 3.63 ng m−3 and 4.31 μg L−1, respectively. The arsenic concentrations in agricultural products decreased by more than 78.8%—from 1.32 mg kg−1 in wheat to 0.28 mg kg−1 in vegetable and 0.13 mg kg−1 in maize—after the planting structure adjustment (PSA). However, the chronic daily intake of arsenic via product ingestion was 1.5 times higher than the benchmark dose lower confidence limit. Natural attenuation measures exerted limited effects on soil remediation; the arsenic concentration in the soil decreased insignificantly from 291.9 mg kg−1 to 213.3 mg kg−1. With the current attenuation rate, decreasing the soil arsenic concentration to under 30 mg kg−1 would require 47,900 years. The exceeding contaminant concentration in the resuspended dust, surface runoff, and agricultural products from the contaminated soil must be considered. China's EMMs in mining areas have achieved significant results, but the contaminated soil requires more attention and the PSA should accommodate the dietary habits and economic limits.