Assessing the potential for mobilization of old soil carbon after permafrost thaw: a synthesis of 14C measurements from the northern permafrost region

Estop-Aragonés, C. et al. (2020) Assessing the potential for mobilization of old soil carbon after permafrost thaw: a synthesis of 14C measurements from the northern permafrost region. Global Biogeochemical Cycles, 34(9), (doi: 10.1029/2020GB006672)

[img] Text
222767.pdf - Published Version
Available under License Creative Commons Attribution Non-commercial.



The magnitude of future emissions of greenhouse gases from the northern permafrost region depend crucially on the mineralization of soil organic carbon (SOC) that has accumulated over millennia in these perennially frozen soils. Many recent studies have used radiocarbon (14C) to quantify the release of this “old” SOC as CO2 or CH4 to the atmosphere or as dissolved and particulate organic carbon (DOC and POC) to surface waters. We compiled ~1,900 14C measurements from 51 sites in the northern permafrost region to assess the vulnerability of thawing SOC in tundra, forest, peatland, lake, and river ecosystems. We found that growing season soil 14C‐CO2 emissions generally had a modern (post‐1950s) signature, but that well‐drained, oxic soils had increased CO2 emissions derived from older sources following recent thaw. The age of CO2 and CH4 emitted from lakes depended primarily on the age and quantity of SOC in sediments and on the mode of emission, and indicated substantial losses of previously‐frozen SOC from actively expanding thermokarst lakes. Increased fluvial export of aged DOC and POC occurred from sites where permafrost thaw caused soil thermal erosion. There was limited evidence supporting release of previously‐frozen SOC as CO2, CH4, and DOC from thawing peatlands with anoxic soils. This synthesis thus suggests widespread but not universal release of permafrost SOC following thaw. We show that different definitions of “old” sources among studies hamper the comparison of vulnerability of permafrost SOC across ecosystems and disturbances. We also highlight opportunities for future 14C studies in the permafrost region.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Garnett, Dr Mark
Authors: Estop-Aragonés, C., Olefeldt, D., Abbott, B. W., Chanton, J. P., Czimczik, C. I., Dean, J. F., Egan, J. E., Gandois, L., Garnett, M. H., Hartley, I. P., Hoyt, A., Lupascu, M., Natali, S. M., O'Donnell, J. A., Raymond, P. A., Tanentzap, A. J., Tank, S. E., Schuur, E. A.G., Turetsky, M., and Walter Anthony, K.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Global Biogeochemical Cycles
Publisher:American Geophysical Union
ISSN (Online):1944-9224
Published Online:02 September 2020
Copyright Holders:Copyright © 2020 The Authors
First Published:First published in 34(9):e2020GB006672
Publisher Policy:Reproduced under a Creative Commons license

University Staff: Request a correction | Enlighten Editors: Update this record