Watershed slope as a predictor of fluvial dissolved organic matter and nitrate concentrations across geographical space and catchment size in the Arctic

• Published in: Environmental Research Letters
• Main Authors: C T Connolly, M S Khosh, G A Burkart, T A Douglas, R M Holmes, A D Jacobson, S E Tank, J W McClelland
• Format: Article in Journal/Newspaper
• Language: English
• Published: IOP Publishing 2018
• Subjects: Arctic; dissolved organic matter; inorganic nitrogen; rivers; watershed slope; Environmental technology. Sanitary engineering; TD1-1066; Environmental sciences; GE1-350; Science; Q; Physics; QC1-999
• Online Access: https://doi.org/10.1088/1748-9326/aae35d; https://doaj.org/article/c3859f1b6a184659b116931abd4a5bf7

Understanding linkages between river chemistry and biological production in arctic coastal waters requires improved estimates of riverine nutrient export. Here we present the results of a synthesis effort focusing on relationships between watershed slope and seasonal concentrations of river-borne dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and nitrate ( ${{{\rm{NO}}}_{3}}^{-}$ ) around the pan-Arctic. Strong negative relationships exist between watershed slope and concentrations of DOC and DON in arctic rivers. Spring and summer concentration-slope relationships for DOC and DON are qualitatively similar, although spring concentrations are higher. Relationships for ${{{\rm{NO}}}_{3}}^{-}$ are more variable, but a significant positive relationship exists between summer ${{{\rm{NO}}}_{3}}^{-}$ concentrations and watershed slopes. These results suggest that watershed slope can serve as a master variable for estimating spring and summer DOC and DON concentrations, and to a lesser degree ${{{\rm{NO}}}_{3}}^{-},$ from drainage areas where field data are lacking, thus improving our ability to develop pan-arctic estimates of watershed nutrient export.