Project Summary (2000-2005)

Human exposure assessment, an essential component of environmental risk analysis, requires quantitative approaches for estimating the distribution and persistence of pollutants at Superfund sites and in environmental media impacted by Superfund sites. This project develops an approach to estimate contaminant concentrations in environmental media to which humans may be exposed. An innovative simulation model is being developed that incorporates the geological heterogeneity of groundwater at a Superfund site. The emphasis is on volatile organic chemicals or VOCs (prevalent Superfund contaminants) and perchlorate (important at some sites). To improve existing predictive models, there is a need a better understanding of some of the environmental processes that collectively govern the fate of Superfund pollutants. To meet this objective, researchers are examining the impact of physical and chemical heterogeneity on transport; the impact of mineral and organic matter composition on reactivity; how variations in oxidation status control both abiotic and biological transformations; how microbial population dynamics determine biodegradation rates; the coupling of transport and transformation processes; and how each of these factors changes when chemical mixtures are present.