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(33-02) Towards a New Methodology of Ecotoxicity Testing of Metal Contaminated Soils. Peijnenburg, Willie*,1, Groot, Arthur1, Jager, Tjalling1, 1 RIVM, Laboratory for Ecotoxicology, Bilthoven, The Netherlands ABSTRACT- Quality objectives for metals are currently based on total metal loadings. However, the link between total metal concentrations and adverse effects on ecosystems is not straightforward. It is recognised that, especially for site-specific risk assessment, insufficient attention is paid to differences in variability between typical field and laboratory settings, between different field soils, and to differences between natural metal fractions and metals of an anthropogenic origin. In addition, the possibility of adaptation of organisms to widely ranging levels of essential metals is often ignored. With regard to essential elements, it is recognised that species within specific ecosystems may adapt to the metal levels present in the ecosystem. This possibly results in a shift of species sensitivities, and hence in a shift in species diversity. It has therefore been proposed to derive geographically related environmental quality standards that are specific for so-called 'metallo-regions' (a region in which there is similarity with regard to both soil composition, and natural background levels of essential elements). In this contribution the results are presented of a study aimed at filling in some of the knowledge gaps that hinder implementation of the metalloregion-concept. Bioaccumulation studies and toxicity testing were carried out with six terrestrial invertebrate species and two plants in a number of Dutch soils. The soils differed widely with regard to soils properties and metal pools. To investigate the effects of differences in bioavailable natural background concentrations, similar experiments were carried out with a soil containing a zinc gradient due to long term exposure which halted about three decades ago. Bioaccumulation studies focussed on assessing internal steady-state concentrations of both essential and non-regulated metals. Endpoints for toxicity testing included growth, survival, and reproduction, and were expressed on the basis of experimentally determined internal metal levels. Key words: Metals, Bioavailability, Soil, Earthworms |
