Test designs to assess the influence of soil characteristics on the toxicity of copper and lead to the oligochaete Enchytraeus albidus.

Abstract

Statistical test designs were used to identify and quantify the soil parameters important for determining the ecotoxicological effects of copper and lead to the potworm Enchytraeus albidus. The application of a Fractional Factorial Design revealed that the acute toxicity of copper and lead to E. albidus can vary over more than two orders of magnitude depending on the physico-chemical characteristics of the (artificial) soils. The differences in metal ecotoxicity were mainly determined by pH and organic matter content or cation exchange capacity (CEC). Using a Central Composite Design, models were developed describing the ecotoxicity of copper and lead to E. albidus as a function of these parameters. To validate the developed response surface models, two field soils and the standard artificial soil prescribed by OECD were spiked with copper and lead and the acute toxicity to E. albidus was assessed. These validation experiments confirmed that the toxicity of copper and lead could be predicted using information on the total metal concentration, the pH and the CEC of the soil with toxicity decreasing with increasing pH and CEC.