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(P106) Bioaccumulation of Metals in Terrestrial Plants and Invertebrates at Vandenberg AFB, California.
Torres, Kevin*,1, Kephart, Bea2, Clark, Donald1, Shibata, Mark1, Rigby, Mark1, Donn, T3, Waitman, Karen1, 1 Tetra Tech, Inc., Lafayette, CA, USA2 Department of the Air Force, Vandenberg AFB, CA, USA3 Entrix, Walnut Creek, CA, USA
ABSTRACT- A field validation study in support of ecological risk assessments (ERAs) at Vandenberg Air Force Base (AFB) successfully addressed key uncertainties evident in predictive ERAs. A major objective of this study was to use regressions to identify relationships between metal concentrations in plant or soil invertebrate tissues and co-located soils. Metal concentrations in tissues and soil were measured across locations comprising both reference and contaminated sites. The overall purpose of these regression models was to characterize the magnitudes of exposures to metals of herbivorous and insectivorous wildlife consuming these tissues at Vandenberg AFB. The regressions showed that concentrations of four of 18 metals significantly increased in plant tissues with increasing soil concentrations, and concentrations of seven of 18 metals significantly increased in soil invertebrate tissues with increasing soil concentrations. The relative slopes and strengths of these bioaccumulation relationships are discussed to infer patterns of metal accumulation in tissues. The study findings suggest that metal exposures of insectivorous wildlife are generally higher than exposures of herbivorous wildlife. For certain metals, differences between rates of bioaccumulation observed in this study and those predicted using models from the literature are apparent. We are applying the Vandenberg AFB-specific bioaccumulation models to improve the accuracy of exposure and risk estimates for wildlife across sites with similar habitats and soil types. This effort shows how a limited field study can provide the client and regulators with critical information to reduce uncertainties and make science-based decisions about the cleanup and future use of sites.
Key words: metals, bioaccumulation, field verification, ecological risk assessment
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