Abstract: In this paper, the concentrations of Cd, Cr, Pb, Ni, Cu and Zn in the full dry soft part of the adult clam Moerella iridescens from three geographical populations, Lianyungang population from Hangzhou bay, Zhapu and Cixi population from Haizhou bay were determined by atomic absorption spectrometer. The results indicated that the concentrations of Cd, Cr, Pb, Ni and Cu in the clam from Cixi and Zhapu were significant higher than that in Lianyungang, but a reversed trend was found for Cr. The major contaminant for the three populations M. iridescens was Zn among the six heavy metals and the concentration amounted to 548.589－732.201 μg/g. Overall the heavy metal contamination for M. iridescen was better in Lianyungang population while it was worse in Zhapu population. The results of cluster analysis based on the six heavy metals indicated that the contamination character was similar between Cixi and Zhapu (Euclidean distance 89.79), but that was quite different from Lianyungang (Euclidean distance 139.19 and 204.56 respectively). Therefore, the cluster results based heavy metals was consistent with geographical distance among the three populations of M. iridescens.

Key words: Moerella iridescens, geographical population, heavy metal, contamination assessment, cluster analysis