Multivariate test designs to asses the influence of zinc and cadmium bioavailability in soils on the toxicity to Enchytraeus albidus

Multivariate test designs were used to identify and quantify the soil param eters important for determining the ecotoxicological effects of zinc and ca dmium to the potworm Enchytraeus albidus. The application of a fractional f actorial design (FFD) revealed that the acute toxicity of zinc and cadmium to E. albidus can vary over more than two orders of magnitude, depending on the composition of the (artificial) soils. The differences in metal ecotox icity were determined mainly by pH and organic matter content or cation exc hange capacity (CEC). Using a central composite design, models were develop ed describing the ecotoxicity of zinc and cadmium to E. albidus as a functi on of these parameters. To validate the developed surface response models, two field soils and the standard artificial soil prescribed by the Organiza tion for Economic Cooperation and Development (OECD) were spiked with zinc and cadmium, and the acute toxicity to E. albidus was assessed. These valid ation experiments confirmed that the toxicity of zinc and cadmium could be predicted by the pH and the CEC of a soil with toxicity decreasing with inc reasing pH. and CEC.