A preliminary study of heavy metal contents in sea water,sediments and cultured shellfish in shellfish culture areas of Xiamen

Based on the data of shellfish culture areas of Xiamen,Fujian province in April and October of 2005,the contents and distributions of heavy metals in the sea water,surface sediments and shellfish organisms were analyzed.Eco-environmental quality and potential ecological risk in the shellfish culture areas were also assessed.The results were summarized as follows.The average contents of Cu,Pb,Cd and Zn were 1.06,1.23,0.05 and 6.28μg·L-1 respectively in the sea water,20.0×10-6,39.5×10-6,0.07×10-6 and 97.3×10-6 respectively in the sediments,and 16.3×10-6,0.24×10-6,0.38 ×10-6 and 63.9 ×10-6 respectively in the shellfish organisms.The results of eco-environmental quality evaluation showed that the contents of four heavy metals in the sea water were below the second degree of Sea Water Quality Standard and belonged to the grade of green,while the contents of four metals in the sediments were all than the values of the first degree of Standard for Marine Sediments Quality and belonged to the grade of less green.Cu,Pb and Cd were more harmful than Zn as their potential ecological risk factors were larger;however,for the whole culture area,the potential ecological risks of heavy metals in the sediments were slight and the environmental quality of the culture areas was good.In addition,according to the standards of Pollution-free Foods,Tolerance Limit of Zinc in Foods,and Marine Biological Quality,the pollution levels of heavy metals in the four species of shellfishes had been assessed as follows.The concentrations of Cu,Pb,Cd and Zn in Ruditapes philippinarum and Sinonovacula constricta were all below the standard values,but the content of Cu in Saccostrea cucullata Born and that of Cd in Tegillarca granosa were above the standard values.