Water, carbon and mercury cycling in Arctic terrestrial and freshwater ecosystems

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Arctic landscapes and ecosystems are highly sensitive to anthropogenic climate warming and global atmospheric pollutants such as mercury (Hg). Climate-driven perturbations to hydrologic and cryospheric regimes will profoundly alter the physical, biogeochemical and ecological processes that regulate Hg transport, fate and effects in terrestrial and aquatic environments. Warmer conditions will increase ecosystem productivity and organic matter concentrations in soils and freshwaters, with important implications for Hg cycling and bioavailability. Reduced snow cover periods and longer growing seasons may enhance terrestrial uptake of Hg, and increases in annual precipitation and rainfall amounts will strengthen terrestrial-aquatic interactions, increasing fluxes of carbon and Hg to downstream freshwater and marine environments. This multitude of effects and their interactions require simultaneous measurement of ecosystem-scale fluxes of water, carbon and mercury, including boundary-layer exchanges in terrestrial and aquatic environments, and streamflow discharge and export from catchments and lakes. ******NSERC funding will be used to expand field research and training opportunities near Iqaluit, Nunavut, in the areas of watershed hydrology, micrometeorology, limnology and contaminants research. The overarching objective is to improve mechanistic understanding of seasonal and inter-annual dynamics and interdependencies of water, carbon and Hg cycling in Canada's eastern Arctic on South Baffin Island, Nunavut. Cumulative annual changes in water, carbon and mercury storage and fluxes will be measured for a headwater catchment and a first-order lake. Surface and subsurface conditions on land and water will be monitored simultaneously, including snow, ice and vegetation phenologies, and ground/water thermal regimes, to identify mechanistic drivers of whole-ecosystem dynamics. Modelling using field observations, remote sensing imagery, and hydro-climatological inputs will be conducted to up-scale empirical observations to the ~52 km2 Apex River watershed near Iqaluit.