Speciation and Potential Ecological Risk of Heavy Metals in Soils from Overlapped Areas of Farmland and Coal Resources in Northern Xuzhou, China.

Contamination caused by heavy metals (HMs) in soil of overlapped area of farmland and coal resources (OAFCR) has impact on crops. The concentrations and speciation of As, Cd, Cr, Cu, Pb and Zn were investigated in topsoil of an OAFCR in Xuzhou, China. The results showed that mean concentrations of all six metals were higher than the background values of Xuzhou city and Cd was moderate accumulated with the maximum Igeo equalled to 2.13. Cd showed moderate contamination level (IPi = 1.75) and potential ecological risk (Er = 44.06). Most of the total Cr, Cu, Ni, Pb, and Zn were presented in the residual forms (above 60%), and the percentages of reducible, oxidisable and residual forms of Pb were 23%, 21% and 43% respectively. Pb and Cd reflected a moderate degree of potential ecological risk and a considerable migration risk and ecotoxicity.