Heavy metals in oysters, mussels and clams collected from coastal sites along the Pearl River Delta, South China

Concentrations of 8 heavy metals: cadmium (Cd), copper(Cu), zinc (Zn), lead (Pb), nickel (Ni), chromium (Cr), antimony(Sb) and tin (Sn) were examined in 3 species of bivalves (Pernaviridis, Crassostrea rivularis and Ruditapes philippinarum)collected from 25 sites along the Pearl River Delta coastal watersin the South China Sea from July to August 1996. In general, Cd,Cu, Zn and Sn concentrations in the three bivalve species collectedfrom the Estuarine Zone were significantly higher than thosecollected from the Western and Eastern Zones of the Pearl RiverDelta, which are related to the existence of various anthropogenicactivities in the catchment of the Pearl River Delta. The WesternEstuarine Zone is mainly impacted by Cr, Ni and Cu contamination.In Victoria Harbor, heavy metal contamination is mainly due to Cuand Pb. Cd, Cu and Zn concentrations in oysters were significantlyhigher than those in mussels and clams. This could be explained bythe fact that oysters live mainly in the Estuarine Zone of thePearl River Delta which receives most of the polluting dischargesfrom the catchment of the Delta. During turbid condition, heavymetals (soluble or adsorbed on suspended particulates) dischargedfrom the Delta are filtered from the water column and subsequentlyaccumulated into the soft body tissues of oysters. Heavy metalconcentrations in the three bivalve species were compared with themaximum permissible levels of heavy metals in seafood regulated bythe Public Health and Municipal Services Ordinance, Laws of HongKong, and it was revealed that Cd and Cr concentrations in thethree bivalve species exceeded the upper limits. At certainhotspots in the Delta, the maximum acceptable daily load for Cd wasalso exceeded.

作 者： FANG Zhan-qiang Cheung R.Y.H Wong M.H   作者單位： FANG Zhan-qiang,Cheung R.Y.H(Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong)

Wong M.H(Institute for Natural Resources and Waste Management, and Department of Biology, Hong Kong Baptist University, Kowloon Tong,Hong Kong) 

刊 名： 環境科學學報(英文版)  ISTIC SCI 英文刊名： JOURNAL OF ENVIRONMENTAL SCIENCES  年，卷(期)： 2003 15(1)  分類號： X145  關鍵詞： heavy metals   oyster   mussel   clam   coastal waters