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EFFECT OF SOIL PROPERTIES ON THE TOXICITY AND BIOAVAILABILITY OF METALS
Citation:
Bradham, K, N. Basta, R. Lano, J. Schroder, AND M. Payton. EFFECT OF SOIL PROPERTIES ON THE TOXICITY AND BIOAVAILABILITY OF METALS. Presented at 7th International Conference on the Biogeochemistry of Trace Elements, Uppsala, Sweden, June 15-19, 2003.
Impact/Purpose:
To develop faster, lower cost, greener laboratory-based methods with optimum contamination controls and sensitive analytical methods for identified high priority EDCs
Description:
Heavy metal and organic chemical contamination of soils is a worldwide problem posing a risk to humans and more directly, soil organisms. Due to widespread metal contamination, it is necessary to characterize soils suspected of metal contamination and determine if the metal levels in these soils pose a hazard. Peer-reviewed, ecologically based soil screening levels (Eco-SSLs) are currently being developed in the U.S. to protect ecological receptors from the toxic effects of heavy metals and organic contaminants. Eco-SSLs are measures of chemicals in soil, which are believed to pose little or no risk to ecological receptors. If site measurements of chemicals are compared to Eco-SSLs and found to be lower, then these sites can be removed from further evaluation in the ecological risk assessment process. Metal toxicity is often not directly related to the total concentration of metals present due to a number of modifying factors that depend, in part, on soil chemical properties. Soil organic matter, pH, and clay content are soil chemical properties that influence metal toxicity and bioavailability. Risk is directly related to metal bioavailability, which depends upon metal concentration, the geochemical forms of metal, the species of organism exposed, physical and chemical characteristics of the exposure environment, and the exposure duration. In order to understand metal bioavailability in soils, chemical and biological techniques are needed to measure the portion of metal that is theoretically bioavailable to soil organisms. These can range from direct measures of bioavailability such as internal concentrations to indirect measures such as chemical extractions. The primary objective of this research was to examine the interaction between different combinations of soil modifying factors (pH, organic matter content, clay content) on metal bioavailability to provide data useful for the development of Eco-SSLs and for reducing uncertainty associated with the determination of site-specific ecological risks.
The research in this manuscript has been funded by the U.S. Environmental Protection Agency, Office of Research and Development, National Center for Exposure Assessment. Although the research described in this paper has been funded by the U.S. EPA to Dr. Roman Lanno and Dr. Nicholas Basta of Oklahoma State University, it has not been subjected to the Agency's required peer and policy review and therefore does not necessarily reflect the views of the Agency and no official endorsement should be inferred.