R7 AM Soil Ecotoxicology and Risk Assessment
Thursday, 17 November 2005: 8:00 AM - 11:40 AM in 327-329

(PEI-1117-793720) Metal toxicity in soils: towards a new generation of toxicity models.

Peijnenburg, Willie¹, Koster, Marijke¹, Vijver, Martina², ¹ RIVM - Laboratory for Ecological Risk Assessment, Bilthoven, Netherlands² Institute of Environmental Sciences (CML), University of Leiden, Leiden, Netherlands

ABSTRACT- Biotic ligand models (BLMs) are increasingly used for assessing the risks of metals in the aquatic environment. It may be hypothesized that the basic principles underlying aquatic BLMs also apply to terrestrial organisms. However, possibly due to the complex interactions of metals with the various soil constituents and due to difficulties encountered in univariately modifying the soil, development of terrestrial BLMs is still in its early stages of development. Several approaches towards assessing the truly bioavailable metal fraction in soil, responsible for toxic effects will be presented in our contribution. These include commonly used toxicity assays with spiked field soils in which various metal pools are quantified, bioassays in artificial quartz sand, and toxicity studies along aged field gradients. In addition, mixture effects are quantified on the basis of bioavailable metal pools and insight in the factors modifying toxicity and the mechanisms of toxicity. To quantify and qualify the abovementioned aspects, the often used terrestrial earthworm Aporrectodea caliginosa is used. The models developed were validated in field soils, contaminated with metals during prolonged periods of time or containing enhanced natural background levels of metals. After discussion of the results, application in regulatory use of the approaches taken will be highlighted and future research directions indicated concerning the development of tools on accurate metal risk assessment.

Key words: Metals, toxicity, soil, BLM