Distribution and Fractionation of Lead and Cadmium in a Long-Term Zinc Smelting Areas

Pb, Cd contamination is a serious enviroment problem in the process of exploitation and utilization of zinc mine. In this study, the contents and different fractions of Pb, Cd were investigated in a regions of zinc smelting with indigenous method. The results revealed that Pb, Cd pollution were seriously in smelting slags and farmland. The contents of Pb, Cd were 34 times and 9 times as that of the background values of soil. The sequential extraction test showed that 80% of Pb were associated with residual Pb, Fe-Mn oxides bound Pb and Organic bound Pb, while exchangeable fractions Pb was quitely lower.The sequence of Cd fracttions in slags was residual fraction>Fe-Mn oxide-bound>Exchangeable> Carbonate-bound > Organic-bound. The exchangeable fraction Cd in farmland soils was the most and reached 24%~43%. Bioavailability of Cd is very high in the studied area and had huge threat to the crop security and human healthy.