Douglas, Madison M. and Li, Gen K. and Fischer, Woodward W. and Rowland, Joel C. and Kemeny, Preston C. and West, A. Joshua and Schwenk, Jon and Piliouras, Anastasia P. and Chadwick, Austin J. and Lamb, Michael P. (2022) Organic carbon burial by river meandering partially offsets bank erosion carbon fluxes in a discontinuous permafrost floodplain. Earth Surface Dynamics, 10 (3). pp. 421-435. ISSN 2196-632X. doi:10.5194/esurf-10-421-2022. https://resolver.caltech.edu/CaltechAUTHORS:20220520-231800000
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Abstract
Arctic river systems erode permafrost in their banks and mobilize particulate organic carbon (OC). Meandering rivers can entrain particulate OC from permafrost many meters below the depth of annual thaw, potentially enabling the production of greenhouse gases. However, the amount and fate of permafrost OC that is mobilized by river erosion is uncertain. To constrain OC fluxes due to riverbank erosion and deposition, we collected riverbank and floodplain sediment samples along the Koyukuk River, which meanders through discontinuous permafrost in the Yukon River watershed, Alaska, USA, with an average migration rate of 0.52 m yr⁻¹. We measured sediment total OC (TOC) content, radiocarbon activity, water content, bulk density, grain size, and floodplain stratigraphy. Radiocarbon activity and TOC content were higher in samples dominated by silt as compared to sand, which we used to map OC content onto floodplain stratigraphy and estimate carbon fluxes due to river meandering. Results showed that the Koyukuk River erodes and re-deposits a substantial flux of OC each year due to its depth and high migration rate, generating a combined OC flux of a similar magnitude to the floodplain net ecological productivity. However, sediment being eroded from cutbanks and deposited as point bars had similar OC stocks (mean ± 1 SD of 125.3±13.1 kg OC m⁻² in cutbanks versus 114.0±15.7 kg OC m⁻² in point bars) whether or not the banks contained permafrost. We also observed radiocarbon-depleted biospheric OC in both cutbanks and permafrost-free point bars. These results indicate that a substantial fraction of aged biospheric OC that is liberated from floodplains by bank erosion is subsequently re-deposited in point bars rather than being oxidized. The process of aging, erosion, and re-deposition of floodplain organic material may be intrinsic to river–floodplain dynamics, regardless of permafrost content.
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| Additional Information: | © Author(s) 2022. This work is distributed under the Creative Commons Attribution 4.0 License. Received: 15 Oct 2021 – Discussion started: 03 Nov 2021 – Revised: 18 Mar 2022 – Accepted: 12 Apr 2022 – Published: 10 May 2022. We thank the Koyukuk-hotana Athabascans of Huslia, First Chief Norman Burgett, and the Huslia Tribal Council for land access and US Fish and Wildlife Service (USFWS) – Koyukuk National Wildlife refuge for research permitting and logistical assistance. Shawn Huffman, Alvin Attla, and Virgil Umphenour provided field support and local expertise. We also thank Alex Sessions and Fenfang Wu for use of equipment and assistance with preparing samples for TOC analysis and Matthew Kirby for use of the Malvern Mastersizer and assistance with grain size analysis. We acknowledge financial support from the Department of Energy Office of Science, Biological and Environmental Research, Earth and Environmental Systems Sciences Division, Subsurface Biogeochemical Research Program Early Career Award to Joel C. Rowland; Caltech Terrestrial Hazards Observation and Reporting Center, Foster and Coco Stanback, the Linde Family, and the Resnick Sustainability Institute to Michael P. Lamb and Woodward W. Fischer; the Caltech Center for Environmental Microbial Interactions to Woodward W. Fischer; National Science Foundation Awards 2127442 and 2031532; the National Defence Science and Engineering Graduate Fellowship for Madison M. Douglas and Preston C. Kemeny; and the Fannie and John Hertz Foundation Cohen/Jacobs and Stein Family Fellowship for Preston C. Kemeny. Author contributions. MPL, JCR, WWF, AJW, GKL, and MMD conceptualized the study. MPL, AJW, JCR and GKL determined the methodology. MMD, GKL, JCR, PCK, AJW, JS, APP, AJC, and MPL collected field data. MMD, GKL, PCK, and AJW assisted with geochemistry. MPL supervised the work. MMD conducted data analysis and wrote the original draft, and all authors contributed to the review and editing of the paper. Data availability. All datasets are included in the paper and Supplement. The supplement related to this article is available online at: https://doi.org/10.5194/esurf-10-421-2022-supplement. Competing interests. One author is a member of the editorial board of Earth Surface Dynamics. The peer-review process was guided by an independent editor, and the authors also have no other competing interests to declare. Review statement. This paper was edited by Robert Hilton and reviewed by Jordon Hemingway and one anonymous referee. | ||||||||||||||||||||||
| Group: | Caltech Center for Environmental Microbial Interactions (CEMI), Resnick Sustainability Institute | ||||||||||||||||||||||
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| Issue or Number: | 3 | ||||||||||||||||||||||
| DOI: | 10.5194/esurf-10-421-2022 | ||||||||||||||||||||||
| Record Number: | CaltechAUTHORS:20220520-231800000 | ||||||||||||||||||||||
| Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20220520-231800000 | ||||||||||||||||||||||
| Official Citation: | Douglas, M. M., Li, G. K., Fischer, W. W., Rowland, J. C., Kemeny, P. C., West, A. J., Schwenk, J., Piliouras, A. P., Chadwick, A. J., and Lamb, M. P.: Organic carbon burial by river meandering partially offsets bank erosion carbon fluxes in a discontinuous permafrost floodplain, Earth Surf. Dynam., 10, 421–435, https://doi.org/10.5194/esurf-10-421-2022, 2022. | ||||||||||||||||||||||
| Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | ||||||||||||||||||||||
| ID Code: | 114863 | ||||||||||||||||||||||
| Collection: | CaltechAUTHORS | ||||||||||||||||||||||
| Deposited By: | George Porter | ||||||||||||||||||||||
| Deposited On: | 24 May 2022 14:18 | ||||||||||||||||||||||
| Last Modified: | 24 May 2022 14:18 |
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