DISTRIBUTIONS AND POLLUTION ASSESSMENTS OF HEAVY METALS IN SURFACE SEDIMENTS IN OFFSHORE AREA OF SOUTH YELLOW SEA

It is reported the concentrations of heavy metals Cu,Pb,Zn,Cd,Ni,Cr,As,Hg and grain size in the surface sediments in offshore area of SYS(South Yellow Sea),the distributed characteristics of these heavy metals were analyzed,the correlation between the contents of these heavy metals and grain sizes were discussed,in addition,the methods of pollution indexes and potential ecological risk indexes were used to assess the pollution level and potential harmful effects of heavy metals.The results indicated that the contents of these heavy metals gradually decreased from the offshore area to the open sea area.In survey area,each element had similar pollution sources except As,Hg.The contents of Cu,Cr in some sites exceeded the first class of GB18668-2002,showing low to the second class,the others were lower than the first class.The results of pollution indexes and potential ecological risk indexes revealed that 90%of positions were in a moderate degree of contamination,while 66.7%showed slight ecological risk,30%reached a moderate level of ecological risk.