EVALUATION ON HEAVY METAL CONTENTS IN SEDIMENTS AND OYSTERS IN DIFFERENT OYSTER CULTURE BEDS OF ZHUJIANG RIVER ESTUARY

The contents and distributions of heavy metals in sediments and oysters from oyster culture beds of the Zhujiang River estuary were investigated.Sediments and Crassostrea rivularis samples were colleted from 9 sites along the coastal Zhujiang River estuary in January,2003.Contents of Cd,Cu,Zn,Pb,Cr and Ni in sediments and oyster samples were measured by a flame atomic spectrophotometer.Standard reference materials Buffalo River Sedimentand Standard Oyster tissue 1566a were also digested and analyzed by a flame atomic absorption spectrophotometer for quality control.The results showed that the average contents of Cd,Cu,Zn,Pb,Cr and Ni in the sediments were 0.35—3.8,32.4—108.0,58—395,13.2—96.1,14.7—39.9 and 9.35—40.15μg·g~(-1)(dry weight),respectively,and those in the oysters were 0.11—12.07,128.8—380.6,1456.2—1938.4,0.43—0.98,(3.26)—10.53 and 1.44—3.31μg·g~(-1)(dry weight),respectively.The contents of Cd and Cr in the oysters were remarkably correlated with those in the sediments(p0.01,p0.05,respectively),thus the oysters can be used as bio-indicators of Cd and Cr.The results also showed that the contents of Pb and Cr in the oysters were all below the limits of hygeian evaluating criterion for edible oysters set by China.However,the content of Cd in the oysters from six sampling sites and the content of Cu from four sampling sites were above the limits(1.00 and 50.00μg·g~(-1),wet weight),which should be paid more attention by related branches.