[Heavy metal concentrations and pollution assessment of edible crops grown on restored manganese mine lands in Guangxi, South China].

A survey on the crops grown on the restored manganese mine lands in Pingle and Lipu of Guangxi was conducted, and the heavy metal concentrations in the edible parts of the crops were analyzed. The results showed that the heavy metal concentrations in the crops were 1.18-20.46 mg x kg(-1) for Zn, 0.52-16.16 mg x kg(-1) for Pb, 0.33-6.62 mg x kg(-1) for Cr, 0.01-6.24 mg x kg(-1) for Cu, and 0.01-2.76 mg x kg(-1) for Cd. Among the crops, beans had the highest concentrations of almost all test metals, followed by potatoes. The assessment of single factor pollution indices indicated that in the main, the crops were not polluted by Zn and Cu, but heavily polluted by Pb, Cr and Cd, with the pollution rate being 100%, 96.9% and 75.0%, respectively. Comprehensive pollution index indicated that all the crops were polluted by heavy metals, with the heavy, medium and light pollution grade being 87.5%, 9.4% and 3.1%, respectively. Planting edible crops directly on manganese mine wastelands might have great risk for human health, and the existing restoration patterns should be reconsidered.