An Abrupt Aging of Dissolved Organic Carbon in Large Arctic Rivers.

ABSTRACT: Permafrost thaw in Arctic watersheds threatens to mobilize hitherto sequestered carbon. We examine the radiocarbon activity (F¹⁴C) of dissolved organic carbon (DOC) in the northern Mackenzie River basin. From 2003-2017, DOC-F¹⁴C signatures (1.00 ± 0.04; n = 39) tracked atmospheric ¹⁴CO₂, indicating export of "modern" carbon. This trend was interrupted in June 2018 by the widespread release of aged DOC (0.85 ± 0.16, n = 28) measured across three separate catchment areas. Increased nitrate concentrations in June 2018 lead us to attribute this pulse of ¹⁴C-depleted DOC to mobilization of previously frozen soil organic matter. We propose export through lateral perennial thaw zones that occurred at the base of the active layer

SUBMITTER: Schwab MS 

PROVIDER: S-EPMC7757186 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature