Nonconvective movement of VOCs in moist soil

摘要

AbstractNonconvective (stationary) diffusion of a volatile organic compound (VOC) in unsaturated (moist) soil depends on the effective diffusion coefficient for the gas filled voids and on the retardation factor, expressed in terms of the adsorption capacity of the soil particles. Influenced by the water layers partially covering organic and mineral surfaces, the sorptive capacity was assumed to be caused by linear adsorption at the air‐water interface, at the water‐organic and water‐mineral interfaces, and at the gas‐organic and gas‐mineral interfaces. To a lesser extent, the particle porosity and the solubility of the VOC in the water also can affect partitioning. By means of temporal moment and volume averaging methods, mathematical expressions for these effects were developed and evaluated for moist soils of porous and nonporous particles. This approach was successful in interpreting experimental data for equilibrium adsorption coefficients from differen