Evidence of Metal Interaction in the Bioaccumulation of Cadmium and Zinc in Porcellio Laevis (Isopoda) after Exposure to Individual and Mixed Metals

Abstract

The aim of this study was to determine the accumulation of cadmium and zinc in Porcellio laevis after separate and mixed exposure to these metals. This would give an indication whether cadmium and zinc influence each other’s bioaccumulation. Decaying oak leaves collected from an uncontaminated site (Botanical Gardens of the University of Stellenbosch) were used as substrate in the experiments. The concentrations used were 20, 80 and 160 mg kg−1 (dry mass) cadmium sulphate and 1000, 4000 and 8000 mg kg−1 (dry mass) zinc sulphate. These metals were administered separately and mixed in the experiments. The cadmium and zinc mixtures used were 20 mg kg−1 CdSO4 with 1000 mg kg−1 ZnSO4, 80 mg kg−1 CdSO4 with 4000 mg kg−1 ZnSO4 and 160 mg kg−1 CdSO4 with 8000 mg kg−1 ZnSO4. It was shown that cadmium and zinc accumulated in P. laevis, especially in the hepatopancreas, in both the single-metal and mixed-metal exposures. Cadmium and zinc also exhibited the ability to influence the bioaccumulation of each other in the mixed-metal exposures. It is also concluded that the interaction of these two metals is at least partly dependent on the ratio of exposure concentrations, the actual exposure concentrations, and also the period of exposure.