Active layer slope disturbances affect seasonality and composition of dissolved nitrogen export from High Arctic headwater catchments

• Main Authors: Lafrenière, Melissa J, Louiseize, Nicole L, Lamoureux, Scott
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: NRC Research Press (a division of Canadian Science Publishing) 2017
• Subjects: Arctic; Climate change
• Online Access: http://hdl.handle.net/1807/77500; http://www.nrcresearchpress.com/doi/abs/10.1139/AS-2015-0009

This study investigates the impacts of active layer detachments (ALDs) on nitrogen in seasonal runoff from High Arctic hillslope catchments. We examined dissolved nitrogen in runoff from an undisturbed catchment (Goose; GS) and one that was disturbed (Ptarmigan; PT) by ALDs, prior to disturbance (2007) and five years after disturbance (2012). The seasonal dynamics of N species concentrations and fluxes were similar in both catchments in 2007, but the mean seasonal nitrate concentration and mass flux from the disturbed catchment were on the order of 30 times higher relative to the undisturbed catchment in 2012. Stormflow yielded 45% and 60% of the 2012 TDN flux in GS and PT, respectively, although rainfall runoff provided less than 25% of seasonal discharge. Results support that through the combined effects of increased disturbance and rainfall, climate change stands to significantly enhance the export of nitrate from High Arctic watersheds. This study highlights that the increase in the delivery of nitrate from disturbance is especially pronounced late in the season when downstream productivity and the biological demand for this often limiting nutrient is high. Our results also demonstrate that the impact of ALDs on nitrate export can persist more than five years following disturbance. The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author.