Heavy Metals in Sediment of Lake Taihu's Zhushan Bay:Chemical Speciation and Risk Evaluation

Sedimentary cores from Zhushan Bay was analyzed for chemical speciation of heavy metals(incl.Cr,Ni,Cu,Zn,Cd and Pb) by BCR 3-stage sequential extraction method,and meanwhile their vertical distribution characteristics in the sediment were investigated.It was found the top sediment in particular,was typical of enrichment of heavy metals,and top sediment around the river inlets contained much higher heavy metals than in other places,in terms of both total and extractable contents.The human activity factor evaluation(AF) indicated that apart from Cr,heavy metals' enrichment in the sediment was notable,particularly Cd and Pb.Additionally,result of the ecological risk evaluation revealed that top sediment of 15 cm depth had very high level of Cd with greater RSP values;pollution of Zn within 10 cm depth was severe,while the pollution level of Ni,Cu and Pb within 5 cm-depth sediment were from moderate and severe,and in the depth from 5 to 10 cm pollution of heavy metals was at mild or moderate levels.