Effects of water content and temperature on equilibrium distribution of organic pollutants in unsaturated soil

Abstract

The purpose of this research was to quantify the effects of water content (0.3 to 0.75% for sand, and 0.4 to 1.25% for silt-clay) and temperature (4 to 40 °C) on the equilibrium distribution of the priority pollutants, dichloromethane and l,l,l-trichloroethane in dry Korean decomposed granite soil. The values of effective partition coefficient (Kerr) were largely decreased as the water content increased. Organic pollutant partitioning in dry soil is composed of both water saturated site and dry site in sorbent, and dry site which has high partition coefficient, is reduced as the water content increases. As the temperature increased, the Kef f values decreased, and this effect was magnified at lower water contents. The values of Keff were correlated better with the estimated values using proposed model. Therefore, in the analysis of distribution and transport of pollutant in unsaturated soil, the effects of water content and temperature on the partitioning should be considered.

Estimation of pollutant partition in sandy soils with different water contents

“…2 using the results from Table 2. The experimental data adjusted by BET model showed that an increase in soil water content decreased the monolayer capacity and consequently the adsorption capacity of the soil because of the reduction of contact between the gas phase and the solid matrix and the possible existence of competition between the contaminants and the soil water for adsorption sites (Koo et al 1990). Consequently, the concentration in the solid phase decreased and the concentration in the gas phase increased.…”

Gas phase advection and dispersion in unsaturated porous media

“…Such interactions include adsorption of the gas phase compound to the soil gas–soil water interface, dissolution into soil water, and sorption of dissolved solute to the solid phase. The influence of several factors on gas phase retention has been examined, including such variables as solute chemistry [ Li and Voudrias , 1992; Ruiz et al , 1998], mineral composition [ Rhue et al , 1988; Pennell et al , 1992; Ruiz et al , 1998], soil water content [ Unger et al , 1996; Silva , 1997; Garcia‐Herruzo et al , 2000], and temperature [ Koo et al , 1990; Goss , 1992, 1993].…”

Temperature-Dependent Sorption of Naphthalene, Phenanthrene, and Pyrene to Low Organic Carbon Aquifer Sediments

“…The effect of temperature on sorption to natural sorbents has also been reported for HOCs from solvent mixtures (17) and for fungicides from water (18). The effect of temperature on the sorption of organic chemicals in unsaturated systems has been studied more extensively (19)(20)(21). Little work has been done concerning the effect of temperature on the kinetics of sorption of HOCs to model particles (22) or natural sediments.…”

“…The amount of sediment and solution added to tubes was determined gravimetrically through sequential weighing of the tube and cap; tube, cap and soil; and tube, cap, soil, and PAH and/or electrolyte solution. The mass of sediment (20,15, and 10 g for experiments involving naphthalene, phenanthrene, and pyrene, respectively) was chosen to ensure that there would be at least a 50% difference between initial and final aqueous concentrations at equilibrium. All centrifuge tubes were filled to the top with solution to minimize headspace and wrapped with aluminum foil to prevent photodegradation.…”