Toxicokinetics of metals in the earthworm Lumbricus rubellus exposed to natural polluted soils – relevance of laboratory tests to the field situation

• We estimated bioavailability of Cd, Pb, Cu and Zn to the earthworm L. rubellus.
• Earthworms intensively accumulated Cd and Pb.
• Uptake rate constants of Cd and Pb increased with soil pH.
• Earthworms showed efficient regulation of Cu and Zn internal concentrations.
• Toxicokinetics was predictive of metal accumulation by earthworms in the field.

The aim of this study was to estimate the bioavailability of essential (Zn, Cu) and non-essential metals (Cd, Pb) to the earthworm Lumbricus rubellus exposed to soils originating from a gradient of metal pollution in Southern Poland. Metal uptake and elimination kinetics were determined and related to soils properties. Experimental results were compared with tissue metal concentrations observed in earthworms from the studied transect. Cd and Pb were intensively accumulated by the earthworms, with very slow or no elimination. Their uptake rate constants, based on 0.01 M CaCl2-extractable concentrations in the soils, increased with soil pH. Internal concentrations of Cu and Zn were maintained by the earthworms at a stable level, suggesting efficient regulation of these metals by the animals. The estimated uptake and elimination kinetics parameters enabled fairly accurate prediction of metal concentrations reached within a life span of L. rubellus in nature.