Heavy metals in estuarine shellfish from Oregon.

Abstract

The concentrations of Hg, Zn, Mn, Fe, Cu, and Cd were determined in marine shellfish from the Oregon coast. The levels of these metals in both crustaceans and molluscs were generally typical of those reported from other geographic areas. The primary exception was Cd, which in crustaceans was 5 to 40 times lower and in three of the six marine bivalve molluscs studied was 5 to 25 times lower than that found in most previous studies. The low concentrations of Cd may be due to the lower level and types of industrial activity in coastal Oregon estuaries compared to other regions of the world, and/or to a lower rate of input of this metal from natural weathering processes in this region. No significant variations due either to season or geographical location were apparent in the three principal shellfish species studied.