Transient diffusion, adsorption, and emission of volatile organic vapors in soils with fluctuating low water contents

Laboratory experiments were conducted on large packed soil columns under unsaturated conditions. Trichloroethene (TCE) was introduced at the bottom of the columns. The emissions of TCE from the soil surface was monitored. The retardation of VOC gas transport was determined by sampling the soil-air and the sweep air flushing the column headspace. The transport of VOC gases from experiment initiation until steady-state was simulated using a numerical simulation model. Overall, measured and simulated concentration profiles as well as volatilization fluxes agreed very well.