Effects of a trapped NAPL on the diffusive release of organic contaminantsfrom saturated soils

Diffusion-controlled mobility of benzene and toluene in liquid-saturated so ils containing an immobile nonaqueous phase liquid (NAPL) was investigated. Three soil types were examined at NAPL relative saturations of 0, 5, and 2 0%. An equilibrium model accounting for diffusion through and partitioning among liquid and solid phases was shown to accurately predict contaminant r elease. Diffusion through the NAPL at 20% NAPL relative saturation was show n to be the dominant diffusion pathway.