2023 Volume 65 Issue 3 Pages 167-176
Heterogeneous solute transport in a soil is often described with the mobile-immobile model (MIM). Although the mobile phase fraction, θm /θ, and the exchange rate coefficient between the mobile and immobile phases, α, cannot be determined independently, the MIM is flexible to fit various nonequilibrium solute transport by optimizing θm /θ and α. Two examples were discussed as the MIM applications: an aggregated Andisols and a nonaggregated dune sand, demonstrating equilibrium transport in a saturated aggregated soil, and nonequilibrium transport in an unsaturated dune sand. The MIM can be further applied to diffusion-controlled adsorption and mixed aerobic and anaerobic conditions in an aggregated soil.
