Climate Change Impacts on Contaminant Transport and Active Layer Groundwater Dynamics in the High Arctic, Canada

The Arctic is warming two to four times faster than the global average, leading to permafrost thaw and changes in groundwater flow due to alterations in the timing and the depth of the active layer. These changes may lead to previously immobilized contaminants being transported through the active layer; these new pathways for contaminant migration raises concerns, given that there are an estimated 13,000 to 20,000 industrially contaminated sites, many of which remain unremediated. Understanding how the mobilization of contaminants in a high-Arctic settings is crucial to understand to ensure the safety of northern community water resources. The objective of our research is to assess how changing active layer dynamics affects the transport behavior of contaminants in a continuous permafrost hillslope environment via a numerical modeling approach.

For this study, we use SUTRA-solice, a version of the US Geological Survey SUTRA model that incorporates mass transport processes with groundwater flow and energy transport with dynamic freeze-thaw processes. We simulate a 280 m long, two-dimensional transect that terminates in a lake. The site has an unconsolidated overburden of 2 m over crystalline bedrock and contains continuous permafrost. The model results focus on seasonal contaminant migration through the active layer and discharge into the lake via groundwater flux. By untangling the relationship between climate change processes (increased temperature, precipitation, etc.) alongside contaminants migration, we are able to understand how constituent migration through evolving active layers will impact down-slope water sources.