[Chemical speciations of heavy metals and their risk assessment in agricultural soils in a coal mining area from Xingren County, Guizhou Province, China.].

In this study, total concentrations and chemical speciations of heavy metals (As, Cr, Pb, Zn, Cd, Hg, Cu and Ni) in 64 agricultural soil samples were determined to evaluate the level of contamination from a coal mining area in Xingren County, Guizhou Province. The single factor index, the Hkanson potential ecological risk index and the risk assessment code (RAC) were used for the evaluation of potential ecological and environmental risks in four main utilized types of soils (paddy soil, Coix lacryma-jobi soil, tobacco-growing soil and vegetable soil). The results demonstrated that the concentrations of heavy metals were significantly higher than their soil background values in Guizhou Province, with the exception of Zn.