University of Oulu

Csank, A. Z., Czimczik, C. I., Xu, X., & Welker, J. M. ( 2019). Seasonal patterns of riverine carbon sources and export in NW Greenland. Journal of Geophysical Research: Biogeosciences, 124, 840– 856.

Seasonal patterns of riverine carbon sources and export in NW Greenland

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Author: Csank, Adam Z.1; Czimczik, Claudia I.2; Xu, Xiaomei2;
Organizations: 1Department of Geography, University of Nevada, Reno, NV, USA
2Department of Earth System Science, University of California, Irvine, CA, USA
3Department of Biological Sciences, University of Alaska, Anchorage, AK, USA
4UArctic and Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.3 MB)
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Language: English
Published: American Geophysical Union, 2019
Publish Date: 2019-09-18


Glacial runoff exports large amounts of carbon (C) to the oceans, but major uncertainty remains regarding sources, seasonality, and magnitude. We apportioned C exported by five rivers from glacial and periglacial sources in northwest Greenland by monitoring discharge, water sources (δ18O), concentration and composition of dissolved organic carbon (DOC), and ages (14C) of DOC and particulate organic C over three summers (2010–2012). We found that particulate organic C (F = 1.0366–0.2506) was generally older than DOC in glacial sourced rivers and likely sourced from the physical erosion of aged C pools. Most exported DOC showed strong seasonal variations in sources and discharge. In summer, mean DOC ages ranged from modern to 4,750 cal years BP (F = 1.0022–0.6291); however, the annual C flux from glacially sourced rivers was dominated by young, plant‐derived DOC (F = 0.9667–1.002) exported during the spring freshet. The most aged DOC (F = 0.6891–0.8297) was exported in middle to late summer at lower concentrations and was glacial in origin. Scaled to the whole of Greenland using model‐estimated runoff, we estimate a total riverine DOC flux of 0.29% to 0.45% ± 20% Tg C/year. Our flux results indicate that the highest C fluxes occur during the time of year when the majority of C is modern in age. However, higher melt rates from the Greenland ice sheet and longer growing seasons could result in increasing amounts of ancient C from the Greenland ice sheet and from the periglacial landscape to the ocean.

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Series: Journal of geophysical research. Biogeosciences
ISSN: 2169-8953
ISSN-E: 2169-8961
ISSN-L: 2169-8953
Volume: 124
Issue: 4
Pages: 840 - 856
DOI: 10.1029/2018JG004895
Type of Publication: A1 Journal article – refereed
Field of Science: 1171 Geosciences
1172 Environmental sciences
Funding: This work was funded by the U.S. National Science Foundation (ARC‐0909514 to C. I. C. and ARC‐0909538 to J. M. W.).
Dataset Reference: All data are archived with the NSF Arctic Data Center
Copyright information: ©2019. American Geophysical Union.