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(M/MF153) Metal body burdens in terrestrial invertebrates: use and significance in environmental risk assessment. Lock, Koen1, Janssen, Colin1, 1 ABSTRACT- Bioconcentration factors are frequently used in environmental risk assessments and the derivation of quality criteria to assess the risk and bioavailability of metals in soils. In the present study, uptake and elimination kinetics of zinc and cadmium were studied in the earthworm Eisenia fetida. Even at the highest exposure concentrations where E. fetida survived, the internal zinc concentration was regulated to a constant level. Internal cadmium concentrations did not reach equilibrium during the uptake experiments which lasted for 3 weeks. The internal cadmium concentrations decreased very slowly when exposed animals were transferred to clean substrate. The internal concentrations causing 50% reduction in cocoon production for E. fetida exposed to cadmium varied between different soil types indicating there are no fixed critical body burdens. For both zinc and cadmium, bioconcentration factors decreased exponentially with increasing soil metal concentrations. Bioconcentration factors may therefore be poor indicators of environmental risk. Their dependence on the total soil concentration makes bioconcentration factors also unsuitable for assessing the influence of soil characteristics on the bioavailability of metals in contaminated field soils. Key words: internal concentrations, Eisenia fetida, zinc, cadmium |
