Transport and adsorption of volatile organic compounds in low water content soils

摘要

Scope and method of study. The purpose of this study was to investigate the transport and adsorption of volatile organic compounds in low water content soils. Organic vapor adsorption onto low water content soil is important in the estimation of soil contamination. The accurate prediction of the transportation and volatilization of organic compounds can be very helpful in the evaluation of soil and groundwater quality. A soil adsorption experiment was used to quantify soil adsorption coefficient and the soil column tests were employed to measure gaseous diffusivity. The optimum parameters were determined using the Complex method and the contaminant transport model was solved by finite difference method.;Findings and conclusions. Soil adsorption in low water content soil varied significantly with the soil types and the moisture. The adsorption of organic compounds onto low water content soil may be several orders of magnitude greater than the adsorption onto high water content soil. The Millington-Quirk diffusivity model was found to be a good predictor except in extremely low ($theta <$ 0.002 v/v) water content soil. The removal of volatile organic compounds from low or high water content soil is much more difficult than from moderately dry or wet soil. Even if the measured gas phase concentrations of volatile organic contaminants are small, the contamination in low water content soil may be severe because large amounts of contaminants can be adsorbed by the soil.