Recent literature shows that much has been learned about the effects of diffusion, dispersion, advection and adsorption on chemical transport in soils (van Genuchten & Wierenga, 1976; Goltz & Roberts, 1988; Ptacek & Gillham, 1992). Numerous models have been developed in attempts to describe the one-dimensional transport of chemicals. These models are important because they continuously increase insight into the basic transport mechanisms involved and, consequently, improve the capability to predict the fate in the soils of such diverse chemicals as pesticides, chlorinated hydrocarbons and heavy metals. .
