Distribution of cadmium, lead and zinc amongst the marine sediments, seagrasses and fauna, and the selection of sentinel accumulators, near a lead smelter in South Australia

Abstract

The concentrations of Cd, Pb and Zn in 23 species of marine animal and three species of seagrass were determined from samples collected near a large lead smelter. The spatial patterns of metal distribution in sediments, seagrasses, crustaceans and fish could be described in terms of distance from the smelter, although the fit of the mathematical model was often improved by the inclusion of other environmental variables, such as clay content of the sediment or time of sample collection. In the fish and seagrasses, Zn was the most widely dispersed metal, followed by Cd, then Pb, which was least dispersed.

In general, organisms at higher trophic levels (fish) had lower metal concentrations than primary producers (seagrass). There was evidence for bioaccumulation of metals in many species, especially in the molluscs, but no biomagnification of any metal could be detected.

The strong relationship between distance and metal content of several species of seagrass, fish and crustacean indicates that they are potential sentinel accumulators for monitoring the distribution of Cd, Pb and Zn. Although bivalve molluscs contained high concentrations of Cd, Pb and Zn, their contents did not consistently relate to distance from the smelter, suggesting that, except for Pinna bicolor, they are of little value as sentinel accumulators for these metals. The implications of the results for the design of monitoring programs using sentinel accumulators are discussed.