A comprehensive mitigation strategy for heavy metal contamination of farmland around mining areas - Screening of low accumulated cultivars, soil remediation and risk assessment.

A three-year field test was conducted in an area surrounding past mining activity (mining area) to investigate the value of a novel comprehensive remediation strategy for Cd and Pb contamination, which included screening of low accumulated vegetable cultivars that take up Cd and Pb less than normal cultivars, in situ soil remediation using different soil amendments, and health risk assessment that evaluates the possibility of safe consumption for the vegetables. Results showed that cultivar Huoqing 91-5C of which vegetable was selected as a low accumulator of Cd and Pb in a soil contaminated with 0.5 mg kg-1 and 8180 mg kg-1 total Cd and Pb concentrations, respectively. Addition of 20 t ha-1 of biochar with 2 t ha-1 of calcium superphosphate in 10 cm depth could decrease available Cd and Pb by 70% and 85% after 1 year, respectively. Following treatments, hazard quotients for adults and children were below 1, indicating that the vegetables grown were safe for human consumption. The total cost of remediation was $3885 ha-1, so the cost of the remediation of the combination of Cd and Pb was economic in this mining area.