Chapter 8 - Mathematical modeling of contaminant transport in the subsurface environment

Abstract

Contaminant transport modeling is a challenging task due to various physical, chemical, and biogeological processes. The transport of multispecies and multiphase contaminants increases the chemical complexity in the modeling framework. The complexity further enhances when modeling is done for aquifer regions with low-permeability regions such as thin clay/silt lenses. A better understanding of these processes in the highly heterogeneous porous system, such as the aquifer–aquitard system, is essential for designing an efficient remediation plan. Therefore this chapter aims to present the framework of contaminant transport models specifically used for saturated porous systems. Furthermore, a mini-review of the fate and transport modeling studies regarding the Indian context is presented. The framework of the transport model and key findings of these studies for highly heterogeneous porous systems are highlighted. It is observed that none of the studies have emphasized the impact of diffusion fluxes into or out of low-permeability regions (silt or clay lenses) on the contaminant transport behavior in the high-permeability region (sandy aquifer). Besides, the transport behavior of conservative contaminants in the dissolved phase for various soil types is analyzed by numerical simulations using the mobile–immobile model. It is stated that the findings of this chapter can be helpful to determine the suitable contaminant transport model considering realistic heterogeneous aquifer conditions, which will further enhance the prediction capability of a mathematical model.