Modeling of Heavy Metal Movement in Vegetated, Unsaturated Soils with Emphasis on Geochemistry

In recent years, researchers have focused on modeling of multicomponent reactive transport and have developed models to study the mobility of potentially toxic heavy metals in the subsurface. In this study, a mathematical model for understanding the fate of a typical heavy metal (lead) in unsaturated soil is developed. The entire modeling activity comprises of three parts. During the first part, a geochemical model to describe the soil heavy metal interactions is developed. In the second part, a solute transport model is developed and linked with the unsaturated flow model which incorporates root water uptake. The final part involves the sequential solution of the transport and geochemical models, using the aquifer properties which are typical of contaminated sites in southeast Kansas. The local equilibrium assumption (LEA) is adopted, and the transport and geochemical models are decoupled while solving for the heavy metal transport. The model is used to simulate heavy metal movement through unsaturated soil at the laboratory column scale. The study provides insight on movement of heavy metals in chat-contaminated fields of Southeast Kansas.