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1G - Long-range transport of pollutants (chemicals) (WE13/9) Chemical-specific soil penetration models for regional multimedia models. McKone, Thomas1, 2, Bennett, Deborah3, Macleod, Matthew2, 1 University of California School of Public Health, Berkeley, California, USA2 Lawrance Berkeley National Laboratory, Berkeley, California, USA3 Harvard University School of Public Health, Boston, Massachusetts, USA ABSTRACT- Quantifying the mass transport of chemicals in soil and between soil and atmosphere are key steps in understanding the role soil plays in controlling fate, transport, and exposure to multimedia persistent pollutants. In existing multimedia models there are significant variations in both the complexity and structure applied to the soil compartment. Here a novel approach for constructing soil transport algorithms for multimedia fate models is described and evaluated. The resulting algorithms account for diffusion in gas and liquid components; advection in gas, liquid, or solid phases; and multiple transformation processes. They also provide an explicit quantification of the characteristic soil penetration depth. We construct a compartment model using three and four soil layers to show that we can replicate with high reliability the flux and mass distribution obtained from the exact analytical solution describing the transient dispersion, advection, and transformation of chemicals in soil layers with different properties but a fixed boundary condition at the air-soil surface. The soil compartment algorithms can be dynamically linked to other compartments (air, vegetation, ground water, surface water) in multimedia fate models. We demonstrate and evaluate the performance of the algorithms in a model with applications to benzene, benzo(a)pyrene, methyl-tert-butylether (MTBE), dioxin (TCDD), and tritium. This work is used to provide guidelines for improved modeling of the soil compartment in regional multimedia models. Key words: persistent pollutants, multimedia, penetration depth, transport/fate |
