Organic carbon burial by river meandering partially offsets bank erosion carbon fluxes in a discontinuous permafrost floodplain

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 permafr...

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Published in:Earth Surface Dynamics
Main Authors: Douglas, Madison M., Li, Gen K., Fischer, Woodward W., Rowland, Joel C., Kemeny, Preston C., West, A. Joshua, Schwenk, Jon, Piliouras, Anastasia P., Chadwick, Austin J., Lamb, Michael P.
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2022
Subjects:
Online Access:https://doi.org/10.5194/esurf-10-421-2022
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spelling ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00060942 2023-05-15T15:15:25+02:00 Organic carbon burial by river meandering partially offsets bank erosion carbon fluxes in a discontinuous permafrost floodplain Douglas, Madison M. Li, Gen K. Fischer, Woodward W. Rowland, Joel C. Kemeny, Preston C. West, A. Joshua Schwenk, Jon Piliouras, Anastasia P. Chadwick, Austin J. Lamb, Michael P. 2022-05 electronic https://doi.org/10.5194/esurf-10-421-2022 https://noa.gwlb.de/receive/cop_mods_00060942 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00060482/esurf-10-421-2022.pdf https://esurf.copernicus.org/articles/10/421/2022/esurf-10-421-2022.pdf eng eng Copernicus Publications Earth Surface Dynamics -- http://www.earth-surf-dynam.net/ -- http://www.bibliothek.uni-regensburg.de/ezeit/?2736054 -- 2196-632X https://doi.org/10.5194/esurf-10-421-2022 https://noa.gwlb.de/receive/cop_mods_00060942 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00060482/esurf-10-421-2022.pdf https://esurf.copernicus.org/articles/10/421/2022/esurf-10-421-2022.pdf https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess CC-BY article Verlagsveröffentlichung article Text doc-type:article 2022 ftnonlinearchiv https://doi.org/10.5194/esurf-10-421-2022 2022-05-15T23:09:49Z 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. Article in Journal/Newspaper Arctic permafrost Yukon river Alaska Yukon Niedersächsisches Online-Archiv NOA Arctic Yukon Earth Surface Dynamics 10 3 421 435
institution Open Polar
collection Niedersächsisches Online-Archiv NOA
op_collection_id ftnonlinearchiv
language English
topic article
Verlagsveröffentlichung
spellingShingle article
Verlagsveröffentlichung
Douglas, Madison M.
Li, Gen K.
Fischer, Woodward W.
Rowland, Joel C.
Kemeny, Preston C.
West, A. Joshua
Schwenk, Jon
Piliouras, Anastasia P.
Chadwick, Austin J.
Lamb, Michael P.
Organic carbon burial by river meandering partially offsets bank erosion carbon fluxes in a discontinuous permafrost floodplain
topic_facet article
Verlagsveröffentlichung
description 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.
format Article in Journal/Newspaper
author Douglas, Madison M.
Li, Gen K.
Fischer, Woodward W.
Rowland, Joel C.
Kemeny, Preston C.
West, A. Joshua
Schwenk, Jon
Piliouras, Anastasia P.
Chadwick, Austin J.
Lamb, Michael P.
author_facet Douglas, Madison M.
Li, Gen K.
Fischer, Woodward W.
Rowland, Joel C.
Kemeny, Preston C.
West, A. Joshua
Schwenk, Jon
Piliouras, Anastasia P.
Chadwick, Austin J.
Lamb, Michael P.
author_sort Douglas, Madison M.
title Organic carbon burial by river meandering partially offsets bank erosion carbon fluxes in a discontinuous permafrost floodplain
title_short Organic carbon burial by river meandering partially offsets bank erosion carbon fluxes in a discontinuous permafrost floodplain
title_full Organic carbon burial by river meandering partially offsets bank erosion carbon fluxes in a discontinuous permafrost floodplain
title_fullStr Organic carbon burial by river meandering partially offsets bank erosion carbon fluxes in a discontinuous permafrost floodplain
title_full_unstemmed Organic carbon burial by river meandering partially offsets bank erosion carbon fluxes in a discontinuous permafrost floodplain
title_sort organic carbon burial by river meandering partially offsets bank erosion carbon fluxes in a discontinuous permafrost floodplain
publisher Copernicus Publications
publishDate 2022
url https://doi.org/10.5194/esurf-10-421-2022
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https://esurf.copernicus.org/articles/10/421/2022/esurf-10-421-2022.pdf
geographic Arctic
Yukon
geographic_facet Arctic
Yukon
genre Arctic
permafrost
Yukon river
Alaska
Yukon
genre_facet Arctic
permafrost
Yukon river
Alaska
Yukon
op_relation Earth Surface Dynamics -- http://www.earth-surf-dynam.net/ -- http://www.bibliothek.uni-regensburg.de/ezeit/?2736054 -- 2196-632X
https://doi.org/10.5194/esurf-10-421-2022
https://noa.gwlb.de/receive/cop_mods_00060942
https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00060482/esurf-10-421-2022.pdf
https://esurf.copernicus.org/articles/10/421/2022/esurf-10-421-2022.pdf
op_rights https://creativecommons.org/licenses/by/4.0/
uneingeschränkt
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op_rightsnorm CC-BY
op_doi https://doi.org/10.5194/esurf-10-421-2022
container_title Earth Surface Dynamics
container_volume 10
container_issue 3
container_start_page 421
op_container_end_page 435
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