N.M. V AN STRAALEN** and D.A. KRIVOLUTSKY* **Department of Ecology and Ecotoxicology VrUe Universiteit, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands *Institute of Evolutionary Animal Morphology and Ecology Russian Academy of Sciences, Leninsky Prospekt 33 117071 Moscow, Russian Federation Many industrialized and developing countries are faced with the assessment of potential risks associated with contaminated land. A variety of human activities, including municipal waste disposal, industrial emissions, military testing, and agricultural practices have left their impacts on soils in the form of elevated, and locally high concentrations of toxicants. In several cases sources have not yet been stopped and contamination continues. Decisions on the management of contaminated sites require information on the extent to which toxicants adversely affect the soil ecosystem. For this purpose, it is often insufficient to extrapolate from abiotic sampling. The detection of a toxicant in the abiotic environment usually does not allow a very strong conclusion on the potential hazards.

N.M. V AN STRAALEN** and D.A. KRIVOLUTSKY* **Department of Ecology and Ecotoxicology VrUe Universiteit, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands *Institute of Evolutionary Animal Morphology and Ecology Russian Academy of Sciences, Leninsky Prospekt 33 117071 Moscow, Russian Federation Many industrialized and developing countries are faced with the assessment of potential risks associated with contaminated land. A variety of human activities, including municipal waste disposal, industrial emissions, military testing, and agricultural practices have left their impacts on soils in the form of elevated, and locally high concentrations of toxicants. In several cases sources have not yet been stopped and contamination continues. Decisions on the management of contaminated sites require information on the extent to which toxicants adversely affect the soil ecosystem. For this purpose, it is often insufficient to extrapolate from abiotic sampling. The detection of a toxicant in the abiotic environment usually does not allow a very strong conclusion on the potential hazards.