Modeling Reactive Solute Transport in Permafrost?Affected Groundwater Systems

Understanding the interactions between ground freeze-thaw, groundwater flow, and solute transport is imperative for evaluating fate of contaminants in permafrost regions. However, predicting migration permafrost-affected systems challenging due to inherent coupling subsurface mass energy processes. To this end, we developed a numerical model that considers coupled heat transfer, transport, including water-ice phase change, solute-dependent porewater freezing, temperature-dependent reaction rates. As an illustrative example, present simulations investigate potential contamination from municipal wastewater lagoon Canadian sub-arctic. Two-dimensional models assuming varying conditions were evaluate possible contaminant scenarios associated with flow river, conservative, degradable, sorbing solutes. Model results reveal important mechanisms controlling behavior aqueous landscapes as well hydrogeologic factors affecting reactive cold Seasonal freeze-thaw episodically restricts connectivity pathways, which attenuates both elevated concentrations can depress freezing temperature produce thaw-induced transport. Both thermally driven solute-enhanced thaw decrease ice content permafrost, have significant implications migration. Therefore, thermo-hydrogeologic process cold-region must be considered when quantitatively assessing impact changing environmental on hydrogeology.