Uptake of Zn, Cd, and Hg by Fish in the Presence of Competing Compartments

Abstract

Rainbow trout (Salmo gairdneri) were exposed to Zn, Cd, and Hg in the presence of competing compartments compartmentalized in a novel experimental apparatus. In fish, uptake of Hg was more than doubled in the presence of Zn and Cd (0.45 μg/g). Organic matter decreased the uptake of Hg and Zn but enhanced that of Cd. We concluded that (1) equilibration with one heavy metal ion did not limit the fish in accumulating another heavy metal ion, and in addition to Hg uptake, 0.55 μg Cd/g and 22 μg Zn/g (wet weight) were taken up by fish, suggesting the possible existence of multiple binding sites in fish, (2) mass balancing showed excellent recoveries for Cd and Zn and losses up to 50% for Hg, and (3) the calculated partition coefficients (fish/substrate) for Zn, Cd, and Hg showed that these compartments are critical in the flux of Zn and Cd whereas sediment and suspended solids only determine the flux of Hg.