The biogeochemical response of High Arctic surface waters to changing permafrost and hydrology

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The proposed research investigates the control that spatial and temporal variations in hydrologic processes (such as precipitation and soil moisture) and permafrost disturbances (such as active layer detachments, ALDs) exert on active layer biogeochemical processes and on downstream river water quality, especially nutrients and organic matter, in High Arctic watersheds. This integrated research program will provide baseline knowledge required to develop means of predicting the water quality response of High Arctic rivers to projected climate change. My research is necessitated by the potential for climate change in permafrost regions to have widespread impacts on hydrology and permafrost stability, which combined will significantly impact terrestrial ecosystem function, river water quality and downstream aquatic ecosystems. Recent studies show that warming, permafrost disturbances and changes in precipitation regimes can lead to increases in nutrients and dissolved organic matter (DOM) concentrations in arctic rivers. These increases occur primarily in the late season when rainfall and concentrated subsurface water sources contribute to runoff. However, there are still conflicting accounts of the relationship between climate and the riverine transport of solutes, inorganic nitrogen (N) and DOM. These conflicts are due in part to differences in the nature of the permafrost and geologic substrate, as well as a general lack of understanding of the spatial and temporal variability in the biogeochemical processes controlling solute production and storage in the watershed, and the hydrologic processes controlling solute mobilization and export in runoff. This research addresses this knowledge gap by combining catchment scale studies of (1) the sources and quality of subsurface water flow, with small-scale field and lab experiments investigating the control of (2) the physical and geomorphological characteristics of soils, and (3) rainfall on biogeochemical processes in the active layer. It is the integrated nature of this research, and the explicit linking of investigations of the watershed scale geomorphic and seasonal hydrological controls on solute mobilization, with site-specific studies examining the key physical controls on subsurface water flow and biogeochemical controls on nutrient and DOM cycling in the active layer that makes this research novel and highly relevant. This work will facilitate moving from site-specific knowledge, to a catchment scale understanding of the impact of changing climate on water quality in permafrost watersheds. The research will generate quantitative data that is critical to informing policy and managing High Arctic water resources to ensure healthy ecosystems and protect water security in Arctic communities that are already subject to perceptible regional climate change. Highly qualified personnel (HQP) will be trained at the Cape Bounty Arctic Watershed Observatory (CBAWO), a collaborative and integrated watershed research station that is unique in the Canadian Arctic. The proposed research program will provide eight HQP with a project management experience, and a breadth of field and analytical skills. Students exit the program with the advanced knowledge required to assess the vulnerability of artic watersheds and ecosystems to climate change and human impacts. The careers secured by graduates of my research program demonstrate that the knowledge and skill sets HQP acquire are highly valued by private industry and government. HQP will be poised to contribute to decision-making, and the development of practices that will improve our ability to manage Arctic environments and water resources in a changing climate, and thus benefit the health and economic well being of all Canadians.