An Abrupt Aging of Dissolved Organic Carbon in Large Arctic Rivers

Schwab, Melissa S. and Hilton, Robert G. and Raymond, Peter A. and Haghipour, Negar and Amos, Edwin and Tank, Suzanne E. and Holmes, Robert M. and Tipper, Edward T. and Eglinton, Timothy I. (2020) An Abrupt Aging of Dissolved Organic Carbon in Large Arctic Rivers. Geophysical Research Letters, 47 (23). ISSN 0094-8276 DOI

[img] Text
2020GL088823.pdf - Published Version
Available under License Creative Commons Attribution.

Download (7MB)
Official URL:


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 weakened by preceding warm summer and winter seasons. Although we are not yet able to ascertain the broader significance of this “anomalous” mobilization event, it highlights the potential for rapid and large‐scale release of aged carbon from permafrost.

Item Type: Article
Uncontrolled Keywords: 2020AREP; IA76
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
07 - Gold Open Access
Journal or Publication Title: Geophysical Research Letters
Volume: 47
Identification Number:
Depositing User: Sarah Humbert
Date Deposited: 23 Dec 2020 18:43
Last Modified: 23 Dec 2020 18:43

Actions (login required)

View Item View Item

About cookies