CONTAMINATION, RISK ASSESSMENT OF HEAVY METALS IN SURFACE SEDIMENTS FROM A MARICULTURE BAY IN SOUTH CHINA

In order to assess the contamination, ecological and biotoxicity risk of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in mariculture area of China, the total concentrations and speciation of metals were analysed in the sediments from a typical mariculture bay in 2011 and 2013. The results show that most heavy metal concentrations in 2013 were lower than those in 2011. The residual and sulfide -bound fractions were the primal), fractions of heavy metals. The pollution can be described in all the sampling sites of heavy metals (except Cd) with moderate to a very high degree by geo-accumulation index (Igeo), enrichment factor (EF) and pollution load index (PLI). According to the risk assessment code (RAC), Cd, Ni and Pb posed a medium to very high ecological risk. The sampling sites that exhibited the biotoxicity risk in 2013 had higher biotoxicity levels than that in 2011. Based on statistical analysis and environmental investigation, four sites (S1, S2, S4 and S7) were highly affected by the environmental pollutants which primarily resulted from the combustion of gasoline and diesel fuel and the ships protective layer.