The transport processes of soluble contaminant in unsaturated soils under pond infiltration

Abstract

A convection-diffusion transport model of soluble contaminant suitable for one-dimensional homogeneous unsaturated three-layered soils is established. The transport processes of soluble contaminant are analyzed by a semi-analytical method, which takes into account the boundary conditions of pond infiltration. Various combined soil layers and various absorption models (e.g. linear or nonlinear adsorption) are discussed. Studies show that, under pond infiltration, the immigration velocity in coarse grained soil will be greater than that in fine grained soil; furthermore the diffusion ratio of the former will also be higher than the latter. Besides, the influence of initial pressure head on immigration velocity can be neglected; however the concentration peaks of contaminant will increase with the decrease of initial pressure head.