Speciation Distribution and Transfer of Heavy Metals in Contaminated Stream Waters around Dabaoshan Mine

The chemical speciation and transfer of heavy metals in water, suspensate and sediments of the Hengshi River with acid mine drainage from Dabaoshan Mine, Guangdong province, were characterized systemically. The results showed that the environmental problem in the water system was Cu, Zn, Cd and Pb related multi-metal pollution. The pollution index (PI) of heavy metals was 2.23～18.11. The levels of water soluble Cu, Zn, Cd and Pb were found as high as 13.82, 50.83, 0.103 and 2.91 mg/L, respectively. Water-soluble, suspensate and total concentrations of Cu, Zn, Cd and Pb, which decreased gradually along the river, have the similar spatial distribution, while As has a little difference. Because of low pH value, fine-grained particles were major fractions for transportation of As, while water-soluble forms were for Cu, Zn, Cd and Pb. Through chemical speciation analysis, the residual speciation was the major species for those five metals in sediments. And the exchangeable speciation of Cd and Pb and organic speciation of Cu and Zn were also relatively high which indicated that they all have potential risk to environment.