Chemical Volatilization in Nearly Dry Soils under Non‐Isothermal Conditions

Abstract

AbstractA theoretical investigation of the volatilization of chemical contaminants in the top layer of a nearly dry soil column under nonisothermal conditions is presented in this paper. The proposed one‐dimensional model considers the effect of natural convection, and the variations of diffusivity and vapor phase adsorption with temperature on contaminant flux across the soil‐air interface. The study has shown that natural convection effects are small. Diurnal temperature changes were found to lead to fluctuations in the concentration profiles and the volatilization flux due to alternating adsorption/desorption processes in the soil. These diurnal changes in concentration cannot be determined from isothermal calculations. Finally, it is suggested that a simple linear isothermal diffusion model may be adequate for describing the chemical concentration profiles at times that are sufficiently long past the initial soil contamination event.