Abstract:
Changing climate has direct effects on both the land, through permafrost thaw, and on the hydrologic cycle, via the amount and timing of seasonal inputs of snow and rainfall. Deeper thaw and degradation of permafrost alters surface and subsurface hydraulic properties, which can allow water to infiltrate and circulate more deeply, pool in new depressions, and flow through new pathways on altered surface topography. These changes in permafrost and hydrology are leading to changes in the mobilization and transport of carbon, nutrients, and metal contaminants within surface waters. There is a great need to better understand the mobilization, and especially the fate, of permafrost derived materials, as these are altering aquatic ecosystems and water quality in culturally important waterways, and have the potential to feedback on the atmospheric CO2 budget and therefore global climate change.
Research at the Cape Bounty Arctic Watershed Observatory in the Canadian High Arctic has been examining climate driven permafrost and hydrological changes and their impacts on surface water biogeochemistry for more than fifteen years. This seminar will review studies from Cape Bounty and other High Arctic sites that illustrate how changes in permafrost hydrology are driving changes in the nature of dissolved organic matter and nutrient fluxes, the relative importance of dissolved vs particulate fluxes, and the total fluxes of mercury in these watersheds.
This body of research highlights that improving our ability to project and model the biogeochemical response of permafrost watersheds to future warming, and the fate of permafrost derived carbon, nutrients and contaminant fluxes requires a better understanding of the spatial variability of the permafrost characteristics. Specifically, we need to be able to identify and model the permafrost characteristics that 1) determine the source and likely nature of the material reservoirs (i.e. how does the composition and distribution of organic matter, nutrients and contaminants vary in permafrost); and those characteristics that 2) dictate the potential for hydrological connectivity with these material reservoirs to be established (e.g. the abundance and distribution of ice in the upper permafrost, and the intensity and seasonality of surface water inputs).