Distribution and relationships of heavy metals in the giant clam (Tridacna maxima) and associated sediments from different sites in the Egyptian Red Sea Coast

Abstract

The giant clam (Tridacna maxima) and sediments have been collected from clean and contaminated coastal sites of the Egyptian Red Sea. Selected samples of the giant clam shells and the associated surface sediments were analyzed for Fe, Mn, Zn, Cu, Pb, Ni and Cd. Significant spatial differences in metal concentrations in Tridacna maxima and sediments were identified. Copper and lead are greatly enriched in the giant clam shells, which is related to their physiological function. Cd content is higher in Tridacna maxima than in sediments, because of the easy substitution between Cd and Ca. The levels of most metals in the giant clam shells and sediments were higher in the anthropogenic sites than in the uncontaminated sites. Generally, metal variations reflect natural conditions and human activity. Moreover, there are no clear relationships between concentrations of heavy metals in the giant clam shells and those in sediments.