Assessing the Potential for Mobilization of Old Soil Carbon After Permafrost Thaw: A Synthesis of C-14 Measurements From the Northern Permafrost Region


Estop-Aragones, Cristian, Olefeldt, David, Abbott, Benjamin W, Chanton, Jeffrey P, Czimczik, Claudia I, Dean, Joshua F ORCID: 0000-0001-9058-7076, Egan, Jocelyn E, Gandois, Laure, Garnett, Mark H, Hartley, Iain P et al (show 10 more authors) (2020) Assessing the Potential for Mobilization of Old Soil Carbon After Permafrost Thaw: A Synthesis of C-14 Measurements From the Northern Permafrost Region. Global Biogeochemical Cycles: an international journal of global change, 34 (9).

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Abstract

<jats:title>Abstract</jats:title><jats:p>The magnitude of future emissions of greenhouse gases from the northern permafrost region depends 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 (<jats:sup>14</jats:sup>C) to quantify the release of this “old” SOC as CO<jats:sub>2</jats:sub> or CH<jats:sub>4</jats:sub> to the atmosphere or as dissolved and particulate organic carbon (DOC and POC) to surface waters. We compiled ~1,900 <jats:sup>14</jats:sup>C 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 <jats:sup>14</jats:sup>C‐CO<jats:sub>2</jats:sub> emissions generally had a modern (post‐1950s) signature, but that well‐drained, oxic soils had increased CO<jats:sub>2</jats:sub> emissions derived from older sources following recent thaw. The age of CO<jats:sub>2</jats:sub> and CH<jats:sub>4</jats:sub> 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 CO<jats:sub>2</jats:sub>, CH<jats:sub>4</jats:sub>, 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 <jats:sup>14</jats:sup>C studies in the permafrost region.</jats:p>

Item Type: Article
Uncontrolled Keywords: permafrost thaw, radiocarbon, carbon dioxide, methane, dissolved organic carbon, particulate organic carbon
Depositing User: Symplectic Admin
Date Deposited: 09 Nov 2020 09:01
Last Modified: 04 Sep 2023 19:35
DOI: 10.1029/2020GB006672
Open Access URL: http://doi.org/10.1029/2020GB006672
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3106184
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