ACCUMULATION OF HEAVY METALS IN SURFACE SEDIMENTS FROM THE SEA REGION OF YANGSHAN IN THE YANGTZE ESTUARY WITH ASSESSMENT OF THEIR POTENTIAL ECOLOGICAL RISK

Based on the monitoring data of surface sediments from the Sea Region of Yangshan in the Yangtze Estuary,the degree in spatial fluctuation and accumulation of heavy metals was analyzed by using the method of variation coefficients and accumulation coefficients.The method of potential ecological risk indices presented by Lar Hakanson was used to assess the potential ecological risk of heavy metals.The degree of Hg spatial fluctuation appears to be the highest and other heavy metals being rather lower in surface sediments,with the order of fluctuation degree ranging as the following: Pb Cd Hg Cu Cr As Zn.The degree of Cu accumulation appears to be the highest among all heavy metals analyzed in surface sediments,with Pb being the second,and others lower.The order of the accumulation degree of these heavy metals is as: Cu Pb Zn As Cr Cd Hg.The assessment of potential ecological risk revealed that the potential ecological risk of these heavy metals to the ocean ecology system is very light,which belongs to light potential ecological risk level,with the order of light potential ecological risk level of all these heavy metals ranging as: CuAsHgPbCdCrZn.