GEOCHEMICAL TRACERS TO INVESTIGATE WATERSHED AND PERMAFROST DYNAMICS IN ALASKA'S NORTH SLOPE

The rapid pace of climate change in the Arctic is dramatically impacting permafrost-dominated watersheds. Understanding these systems' hydrological and biogeochemical responses to warming is critical for informing Arctic communities and ecosystems and constraining global carbon and water fluxes. This study aims to characterize the impact of seasonality and climate change on groundwater discharge and transport in rivers underlain by permafrost in the North Slope of Alaska. This study will utilize deuterium/hydrogen (δD) and oxygen-18/oxygen-16 (δ18O) stable isotopic ratios of water and the dissolved uranium isotopic composition (234U/238U) to characterize hydrology and water-rock interaction time of watersheds underlain by permafrost. This project will examine variations caused by seasonal permafrost thaw/freeze dynamics, as well as elucidate the source of groundwater discharge and assess major cation and trace metal release from permafrost thaw or the overlaying active layer. Fieldwork, conducted in close proximity to the Toolik Field Station, will involve collecting water samples in watershed drainages and monitoring active layer thickness throughout freeze and thaw seasons. This study employs a multi-faceted approach, including sediment flux measurements, isotopic analysis, and thaw depth monitoring. Results aim to demonstrate the utility of a coupled uranium and water isotope approach to characterizing climate-induced shifts in active layer deepening and permafrost-derived material transport in Arctic rivers.