Use of Bioassays for Assessment of Water-Extractable Ecotoxic Potential of Soils

The characterization of contaminated soils is based on heterogeneous strategies considering chemical analyses or bioassays. In the report Bioassays for soils, test methods which are at an advanced state of development and standardization are recommended by the German DECHEMA (German Society for Chemical Apparatus, Chemical Engineering and Biotechnology e.V.). Following this report six soil samples contaminated with different organic and inorganic substances are applied to bioassays using the following organisms: Scenedesmus subspicatus, Daphnia magna, Vibrio fischeri, and Pseudomonas putida. Additionally, they are chemically analyzed. The test results demonstrate that toxic contaminants are present and bioavailable in water elutriates from two soils, indicating the necessity of bioassays and chemical analyses to predict potential risks from contaminated soils. Furthermore it is demonstrated that the described qualitative approach for the assessment of test results is not sufficient to quantify the risk potential of contaminated soils.