Soil treatment and crop rotation for in situ remediation of heavy metal-contaminated agricultural soil in gold mining areas

Abstract

In many areas of China, agricultural land is subject to heavy metal contamination from mining activity. This study investigates an in situ remediation program suitable for the recovery of heavy metal-contaminated agricultural soil around mining areas. A 1-year field experiment was conducted in a gold mining area of Tongguan, Shaanxi Province, China, to evaluate the effectiveness of engineering remediation measures, including adding a layer of noncontaminated soil, or soil homogenization to 40 cm and 80 cm depths, and three crop rotation systems, including rye-corn rotation, wheat-corn rotation, and potato-adzuki bean rotation on ameliorating heavy metal pollutants from contaminated agricultural soil around mining areas. The results showed that soil treatment and crop rotation significantly decreased soil heavy metal concentrations, with 80 cm homogenization and wheat-corn rotation being most effective. After 1 year of in situ remediation using this combination, the concentrations of Hg, Cd, and Pb in topsoil (0–20 cm) were 71.7%, 82.4%, and 21.8% lower, respectively, than before remediation. The single and Nemero indexes of the edible parts of wheat and corn were both <1, indicating they were safe for consumption. The results provide a solution for the in situ remediation of heavy metal-contaminated agricultural soil in mining areas.