Proposed Methodology to Assess Ecological Exposure and Risk for 3MRA. S. M. Beaulieu, J. S. McLean, and G. T. Conrad, Research Triangle Institute, Research Triangle Park, NC; and D. A. Cozzie, US Environmental Protection Agency, Washington, DC
To support 3MRA, we developed a methodology to represent habitat types and ecological receptors at an appropriate level of resolution for a national, site-based analysis. The methodology draws on the conceptual framework presented in EPA’s Ecological Risk Assessment Guidelines and provides a flexible system to assess the potential for adverse ecological effects in representative terrestrial and freshwater habitats across a sample population of facilities in the contiguous US. The ecological exposure module consists of a representative habitat scheme to allow resolution of major types of terrestrial and freshwater systems (including wetlands). The spatial characteristics of the site-based database were determined using a GIS delineation tool to define habitat boundaries and linkages, wetland areas, and surface water bodies. A cross-referencing database was developed to automate the selection of receptors and assigns them to habitats based on habitat characteristics and ecological region, and the exposure simulation module is supported by an extensive exposure factors database containing information on dietary habits, natural history, etc. The exposure module includes an iterative algorithm that cycles through the database on minimum and maximum prey preferences to simulate dietary variability. The ecological risk module employs a traditional hazard quotient approach to estimating ecological risks to a variety or ecological receptors, including plants, mammals, birds, amphibians, soil and sediment organisms. The risk results are aggregated by habitat type (e.g., forested wetlands), habitat group (e.g., terrestrial), receptor group (e.g., mammals), and other descriptors such as habitat distance to waste management facility.
Work supported by U.S. EPA under Contract 68-W98-0085.
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