K. Lock et Cr. Janssen, Zinc and cadmium body burdens in terrestrial oligochaetes: Use and significance in environmental risk assessment, ENV TOX CH, 20(9), 2001, pp. 2067-2072
Uptake and elimination kinetics of zinc and cadmium were studied in the oli
gochaetes Enchytraeus albidus and Eisenia fetida. Even at the highest expos
ure concentrations where E. fetida survived, the internal zinc concentratio
n was still regulated to a constant level. Enchytraeus albidus could not re
gulate the internal zinc concentration as well, and the body burden increas
ed after exposure to high zinc concentrations. After transfer to clean soil
, the internal zinc concentration dropped back to the control level within
a few weeks. For both species, internal cadmium concentrations did not reac
h equilibrium during the uptake experiments. The internal concentrations ca
using 50% reduction in cocoon production for E. fetida exposed to cadmium v
aried between different soil types, indicating that no fixed critical body
burdens exist. For both zinc and cadmium, bioaccumulation factors decreased
with increasing soil metal concentrations. Bioaccumulation factors may the
refore be poor indicators of environmental risk. Their dependence on the to
tal soil concentration makes bioaccumulation factors also unsuitable for as
sessing the influence of soil characteristics on the bioavailability of met
als in contaminated field soils. For the same reason, uptake rate constants
are probably not suited for this purpose.