Abstract:

Contents of heavy metals (Cu,Zn,Pb,Cd) were measured in water and sediment collected in May 2011 from seven sampling sites in Lake Poyang.The pollution status of sediment was evaluated by the geoaccumulation index,potential ecological risk index and ecotoxicological effects.The results showed that the content of Cu,Zn,Pb,Cd in water of Lake Poyangs main tributary estuaries conformed the quality standard for fisheries,so it is with the environmental quality for grade I surface water except for some individual sampling sites.The contents of the analyzed heavy metals in sediment of Lake Poyang were all higher than their background values,indicating an accumulation trend.The pollution was severe in sediments of Rao River estuary,Xin River estuary and Sanjiangkou Region while mild in Main southern lake region.The pollution order of analyzed heavy metals in water and sediment were Pb＞Cd＞Zn＞Cu and Cu＞Zn＞Pb＞Cd,respectively.Pearson correlation analyses showed significant relationships among Cu,Zn,Cd in sediment,providing similar geochemical character among the elements.This meant that there was combined pollution among Cu,Zn,Cd in sediment respectively.The order of integrative pollution status of each sampling site by geoaccumulation index was as follows: Xin River Estuary＞Rao River Estuary＞Sanjiangkou Region＞Xiu River Estuary＞Nanjishan Region＞Fu River Estuary＞Main Southern Lake Region.The potential ecological risk of the analyzed heavy metals was arranged in the following order：Cd＞Cu＞Pb＞Zn.Furthermore,there is high potential ecological risk with Cd while medium level with Cu,Zn and Pb.Our results further revealed that the most bentonic organisms were beyond obvious hazard although sediment in estuaries of Lake Poyangs tributaries was polluted by those four heavy metals,whereas the ecotoxicological effect of Cu was severe in Rao River Estuary and Xin River Estuary,which caused obvious hazard on bentonic organisms