Connectivity and Nitrogen Transport of Two Wetland-Rich Boreal Sites in the Athabasca Oil Sands Region

English Abstract:

Development of the Athabasca Oil Sands Region (AOSR) has increased atmospheric nitrogen emissions. The area surrounding development is comprised of Boreal forests and peatlands. Improved understanding of the hydrological connectivity between Boreal peatlands and uplands is needed to predict the fate and transport of atmospheric N deposited across the region. Two wetlands sites: Jack Pine High (JPH, located 45 km north of Fort McMurray) and Mariana Lakes (ML, located 100 km south of Fort McMurray) were instrumented with piezometers nests and water table wells for this study (n= 108 sampling locations). The wells were placed along transects that cover target landscape units (bog, fen, upland). Wells were sampled for water isotopes and geochemical variables during the summers of 2011-2014 to characterize the baseline geochemistry of groundwater in the different landscape units. Inorganic (nitrate, ammonium) and organic forms of nitrogen (dissolved organic nitrogen), major and minor ions and water isotope tracers (d¹⁸O, d²H and ³H) were measured to identify the various forms of nitrogen in the different landscape units, as well as to assess connectivity and potential for nitrogen transport between the different units. At JPH the connectivity between the uplands and fens is a simple recharge from the upland to the fen. There was little (<0.1-1.5 mg/L) nitrate, ammonium, or dissolved organic nitrate (DON) found throughout JPH. Concentrations of ammonium and DON increased at depths throughout ML. The distribution of ³H with depth within the peatland have shown limited connectivity between the peat and underlying mineral soils.