Impact of metal pools and soil properties on metal accumulation in Folsomia candida (Collembola)

Soil-dwelling organisms are exposed to metals in different ways. Evidence e xists for predominant pore water uptake of metals by soft-bodied oligochaet e species. In the present research, uptake kinetics of metals and the metal loid As by the semisoft-bodied springtail Folsomia candida were studied, fo r which uptake via the pore water is less obvious. Springtails were exposed in 16 field soils and in metal-spiked artificial Organization for Economic Cooperation and Development (Paris, France) soil (OECD soil). Subsequently , accumulation parameters were statistically related to soil metal pools an d soil properties. In Cd-spiked OECD soil, internal Cd levels were linearly related to external Cd concentrations, whereas the springtails maintained fixed internal levels of Cu and Zn regardless of spiked concentrations. In the field soils, all body concentrations of the elements As, Cr, and Ni wer e below detection limit. The essential metals Cu and Zn were presumably reg ulated, and no influence of soil characteristics could be demonstrated. For Cd and Pb, accumulation patterns were correlated mainly to solid-phase soi l characteristics. The presence of these explanatory variables in the multi ple correlations suggests that an uptake mechanism that is solely deter-min ed by pore water concentrations should not be taken as a universally applic able principle in risk assessments of metals for soil invertebrates. Cadmiu m in OECD soils was more available for uptake than in the field soils. The difference remained when extractability was taken into account. The results suggest that experiments in OECD soil cannot be used directly in risk asse ssment for nonessential metals (at least for F. candida), although a reduct ion of uncertainties in metal risk assessment can be reached by consistent use of body residues rather than external concentrations.