ENVR 5 |
| The purpose of this study was to assess the extent soil-side processes intercept, sequester and bury at depth three PCBs arriving in vapor and/or aerosol phases. Once deposited on soil these refractory substances can be transported downward by several mechanisms. Vapor phase diffusion and biodiffusion of soil prticles are the main suspects. A theoretical chemodynamic analysis suggests very different transport mechanisms. The vapor one is slow and soil-side controlled while the particle one is fast and air-side controlled. Data is presented on soil biodiffusion coefficients and PCB accumulations. With the apparentt lack of these coefficients we started with Charles Darwin's earthworm data. This, plus other reported soil turnover rates and mixing depths, was converted to the coefficients. Besides earthworms, we found data on ants, termites, badgers, gophers, squirrels and one kangaroo. Comparing the analogous coefficients from the soil profile data on three PCBs appears to confirm a rapid and deep-column chemical penetration due to bioturbation by these soil macrofauna. Rapid biodiffusion is necessary for maintaining what appears to be very high chemical deposition rates from the atmosphere.
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Atmospheric Aerosol Processes
8:30 AM-11:45 AM, Sunday, August 19, 2007 Boston Park Plaza -- Stanbro Rm, Oral
Division of Environmental Chemistry |