C2. Modeling Solute Transport in Structured, Heterogeneous Porous Media

Abstract

Knowledge of solute transport in heterogeneous porous media is crucial to monitor contaminant fate and transport in the vadose zone and groundwater systems. In this work, saturated and unsaturated soil columns packed with coarse-grained cores embedded within a fine sand matrix were used to examine the transport behaviors of bromide in heterogeneous porous media. A two-domain model considering solute exchange between zones was developed to describe bromide transport in structured, heterogeneous porous media. Simulations from this two-domain transport/exchange model matched experimental breakthrough concentrations very well for both water-saturated and unsaturated conditions. Experimental and model results show that under saturated conditions, both fast-flow and slow-flow domains affect solute transport in heterogeneous media. Under unsaturated conditions, however, our results indicate that flows in the fast flow domain dominate the solute transport and retention processes.