Concentrations and assessment of heavy metals in seawater,sediments and aquatic organisms at Yangtze River estuary in spring and summer

Heavy metals in seawater,sediments and aquatic organisms(fishes and crustacean) were determined and simply assessed using single factor index based on the data obtained from two cruises in the Yangtze River estuary in May and August,2009,in addition,the possible sources of contaminants had been discussed.Results showed that both the Cu and Hg concentrations in the surface seawater in May had an overtaking rate of 30%,the bottom water was mainly polluted by Hg,with an overtaking rate of 35%,part of the stations were contaminated by Zn and Pb;in August,both of the surface water and bottom water were contaminated majorly by Cu,Zn and Hg,with the concentration of each heavy metal two times as many as that in May.The descending order of heavy metal pollution in the sediments in May was CdAsCuZnPbHg,while in August was CdCuAsHgZnPb,the overall level of heavy metals in sediments in May was higher than that in August.Concentrations of heavy metals in aquatic organisms turned out to meet the food safety standards.As resuspension in sediments may have an impact on the release of heavy metals from sediments,the enrichment coefficients of heavy metal in sediments fluctuated greatly in May and August;the descending order of enrichment coefficients in fish ranked as CdPbCuZnHgAs,while in crustacean was PbCdHgZn CuAs.