A model is proposed for the sorption of organic solutes from aqueous solutions by soils. This model is formulated by assuming that the uptake process is controlled by the pore diffusion of solutes within the soil pellets as well as the partition of solutes into the soil organic matter. A general expression of the solute uptake in the Laplace domain is obtained, which together with appropriate macroscopic conservation equations and standard Laplace transform inversion techniques, may be used to obtain the extent of sorption and the distribution of organics under a variety of conditions. Comparisons between model predictions and experiments indicate that the inclusion of the partition effect is indeed important in most of the cases.
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