Is bog water chemistry affected by increasing N and S deposition from oil sands development in Northern Alberta, Canada?

Nitrogen and sulfur emissions from oil sands operations in northern Alberta, Canada have resulted in increasing deposition of N and S to the region's ecosystems. To assess whether a changing N and S deposition regime affects bog porewater chemistry, we sampled bog porewater at sites at different distances from the oil sands industrial center from 2009 to 2012 (10-cm intervals to a depth of 1 m) and from 2009 to 2019 (top of the bog water table only). We hypothesized that: (1) as atmospheric N and S deposition increases with increasing proximity to the oil sands industrial center, surface porewater concentrations of NH, NO, DON, and SO would increase and (2) with increasing N and S deposition, elevated porewater concentrations of NH, NO, DON, and SO would be manifested increasingly deeper into the peat profile. We found weak evidence that oil sands N and S emissions affect bog porewater NH-N, NO-N, or DON concentrations. We found mixed evidence that increasing SO deposition results in increasing porewater SO concentrations. Current SO deposition, especially at bogs closest to the oil sands industrial center, likely exceeds the ability of the Sphagnum moss layer to retain S through net primary production, such that atmospherically deposited SO infiltrates downward into the peat column. Increasing porewater SO availability may stimulate dissimilatory sulfate reduction and/or inhibit CH production, potentially affecting carbon cycling and gaseous fluxes in these bogs.