A Dynamic Model for Terrestrial Ecological Exposure to Toxic Air Pollutants. R. A. Efroymson, B. E. Sample, B. F. Lyon, G. W. Suter II, C. T. Hunsaker, A. W. Simcock, and D. H. Bennett, Oak Ridge National Laboratory, P. O. Box 2008, Oak Ridge, TN 37831-6036; and Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 90-3058, Berkeley, CA 94720
As part of the Total Risk Integrated Model (TRIM), a U.S. EPA-funded approach to evaluate human health and ecological risk associated with air pollutants, we have developed a submodel, EcoFaTE, for the estimation of terrestrial fate and transport of organic chemicals released into the air. The model has multiple, linked algorithms for plants, terrestrial wildlife, and soil invertebrates. Plant foliage accumulates contaminants from the vapor phase and from wet and dry deposition. In addition, roots and stems take up contaminants from soil water. Current plant algorithms represent single-season exposure of herbaceous plants and of tree foliage and roots. Fruits and seeds, senescence, and litterfall will be included in future versions of the model. The wildlife algorithm represents exposure to contaminants through ingestion of food, water, and soil and through inhalation. The wildlife algorithm is consistent among trophic levels, differing only in species-specific exposure parameters. Mammalian uptake and elimination parameters have been derived for representative mammalian herbivores, avian insectivores, mammalian invertebrate feeders, predators, and insects. EcoFaTE assumes that body burdens of contaminants in earthworms are in equilibrium with contaminant concentrations in surface soil. Algorithms have been developed in concentration form and translated into mass-balance form. Because EcoFaTE is intended to generate probabilistic estimates of exposure, distributions of parameters will be provided for Monte Carlo analyses. The spatial explicitness of EcoFaTE will be provided by a Geographic Information System containing readily available national or regional data sets for land cover, soil, roads, water bodies, and species presence. A default set of data for environmental attributes will be identified. A regional case study of the environmental fate and biotic transfers of polycyclic aromatic hydrocarbons will be presented.
Work sponsored by the U.S. Environmental Protection Agency under IAG #DW89937232-01 with the U.S. Department of Energy.