DISTRIBUTIONS OF HEAVY METALS IN SEAWATER,SEDIMENTS AND ORGANISMS AT DAYA BAY AND THEIR ECOLOGICAL HARM

Heavy metals in water,sediments and organisms(fishes,crustacean and mollusca) and the trends of their content changes were analyzed based on the data obtained from four cruises in the southwest Daya Bay in 1996 and 1997,and the relationships between heavy metals in the sediments and between the heavy metals and their sedimentary environment were discussed.Safe levels for heavy metals in seawater and sediments recommended by NOAA(National Oceanic and Atmospheric Administration) were used to assess the potential ecological harm of heavy metals to aquatic organisms in seawater and sediments at Daya Bay.The results indicated that the average contents of Hg,Cd,As,Pb,Cu,Zn,(Cr) in seawater,sediments,and organisms were 0.058,0.041,2.25,2.4,3.2,42,(2.34) μg·L~(-1),0.162,0.042,8.0,32,24,89 mg·kg~(-1),0.058,0.395,2.22,0.25,3.41,16.1 mg·kg ~(-1),respectively.The contents of heavy metals were negatively correlative to pH values and were irrelevant to the contents of sulfides,oils and organic matter in sediments.Cupper concentration in seawater posed serious threat to aquatic organisms,while the adverse effects of heavy metals in sediments on aquatic organisms was low yet.