|
(30-08) Bioavailability in Standardized Soil Toxicity Tests: Fact or Fiction? Lanno, Roman*,1, Basta, Nick2, Bradham, Karen3, Booth, Lynn1, 1 Department of Entomology, Columbus, OH, USA2 Department of Plant and Soil Sciences, Stillwater, OK, USA3 Department of Zoology, Stillwater, OK, USA ABSTRACT- Soils are a tremendously heterogeneous environmental matrix with varying spatial and temporal gradients of organic carbon, pH, and particle size distribution. These soil physical and chemical characteristics in turn are involved in determining the bioavailability of chemicals to soil-dwelling invertebrates. Much effort in recent years has been devoted to developing new endpoints for assessing effects (e.g., biomarkers) while our understanding of chemical exposure in soil systems is poor. Standard protocols suggest determining total chemical concentrations as estimates of chemical exposure, yet total chemical levels are not related to toxicity in soils differing in physical/chemical characteristics. Chemical exposure measurements in toxicity tests do not account for changes in chemical concentration over the course of an experiment due to partitioning to soil or biodegradation. It has been suggested that exposure should be based upon the bioavailable fraction of the chemical in the soil but it is unclear how this should be measured and applied to standard toxicity tests. This presentation will present examples of how measures of the bioavailable fraction of metals (liquid extraction) and PAHs (solid-phase microextraction, SPME) can be applied in determining exposure in standard soil toxicity testing approaches. Key words: soil, toxicity test, bioavailability, test methods |
