Organic carbon characteristics in ice-rich permafrost in alas and Yedoma deposits, central Yakutia, Siberia
Permafrost ground is one of the largest repositories of terrestrial organic carbon and might become or already is a carbon source in response to ongoing global warming. With this study of syngenetically frozen, ice-rich and organic carbon (OC)-bearing Yedoma and associated alas deposits in central Y...
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ftcopernicus:oai:publications.copernicus.org:bg82092 2023-05-15T16:37:24+02:00 Organic carbon characteristics in ice-rich permafrost in alas and Yedoma deposits, central Yakutia, Siberia Windirsch, Torben Grosse, Guido Ulrich, Mathias Schirrmeister, Lutz Fedorov, Alexander N. Konstantinov, Pavel Y. Fuchs, Matthias Jongejans, Loeka L. Wolter, Juliane Opel, Thomas Strauss, Jens 2020-07-23 info:eu-repo/semantics/application/pdf https://doi.org/10.5194/bg-17-3797-2020 https://www.biogeosciences.net/17/3797/2020/ eng eng info:eu-repo/grantAgreement/EC/FP7/338335 doi:10.5194/bg-17-3797-2020 https://www.biogeosciences.net/17/3797/2020/ info:eu-repo/semantics/openAccess eISSN: 1726-4189 info:eu-repo/semantics/Text 2020 ftcopernicus https://doi.org/10.5194/bg-17-3797-2020 2020-07-27T16:22:01Z Permafrost ground is one of the largest repositories of terrestrial organic carbon and might become or already is a carbon source in response to ongoing global warming. With this study of syngenetically frozen, ice-rich and organic carbon (OC)-bearing Yedoma and associated alas deposits in central Yakutia (Republic of Sakha), we aimed to assess the local sediment deposition regime and its impact on permafrost carbon storage. For this purpose, we investigated the Yukechi alas area (61.76495 ∘ N, 130.46664 ∘ E), which is a thermokarst landscape degrading into Yedoma in central Yakutia. We retrieved two sediment cores (Yedoma upland, 22.35 m deep, and alas basin, 19.80 m deep) in 2015 and analyzed the biogeochemistry, sedimentology, radiocarbon dates and stable isotope geochemistry. The laboratory analyses of both cores revealed very low total OC (TOC) contents ( <0.1 wt %) for a 12 m section in each core, whereas the remaining sections ranged from 0.1 wt % to 2.4 wt % TOC. The core sections holding very little to no detectable OC consisted of coarser sandy material were estimated to be between 39 000 and 18 000 BP (years before present) in age. For this period, we assume the deposition of organic-poor material. Pore water stable isotope data from the Yedoma core indicated a continuously frozen state except for the surface sample, thereby ruling out Holocene reworking. In consequence, we see evidence that no strong organic matter (OM) decomposition took place in the sediments of the Yedoma core until today. The alas core from an adjacent thermokarst basin was strongly disturbed by lake development and permafrost thaw. Similar to the Yedoma core, some sections of the alas core were also OC poor ( <0.1 wt %) in 17 out of 28 samples. The Yedoma deposition was likely influenced by fluvial regimes in nearby streams and the Lena River shifting with climate. With its coarse sediments with low OC content (OC mean of 5.27 kg m −3 ), the Yedoma deposits in the Yukechi area differ from other Yedoma sites in North Yakutia that were generally characterized by silty sediments with higher OC contents (OC mean of 19 kg m −3 for the non-ice wedge sediment). Therefore, we conclude that sedimentary composition and deposition regimes of Yedoma may differ considerably within the Yedoma domain. The resulting heterogeneity should be taken into account for future upscaling approaches on the Yedoma carbon stock. The alas core, strongly affected by extensive thawing processes during the Holocene, indicates a possible future pathway of ground subsidence and further OC decomposition for thawing central Yakutian Yedoma deposits. Other/Unknown Material Ice lena river permafrost Republic of Sakha Sakha Thermokarst wedge* Yakutia Yakutia Republic Siberia Copernicus Publications: E-Journals Sakha Biogeosciences 17 14 3797 3814 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
Permafrost ground is one of the largest repositories of terrestrial organic carbon and might become or already is a carbon source in response to ongoing global warming. With this study of syngenetically frozen, ice-rich and organic carbon (OC)-bearing Yedoma and associated alas deposits in central Yakutia (Republic of Sakha), we aimed to assess the local sediment deposition regime and its impact on permafrost carbon storage. For this purpose, we investigated the Yukechi alas area (61.76495 ∘ N, 130.46664 ∘ E), which is a thermokarst landscape degrading into Yedoma in central Yakutia. We retrieved two sediment cores (Yedoma upland, 22.35 m deep, and alas basin, 19.80 m deep) in 2015 and analyzed the biogeochemistry, sedimentology, radiocarbon dates and stable isotope geochemistry. The laboratory analyses of both cores revealed very low total OC (TOC) contents ( <0.1 wt %) for a 12 m section in each core, whereas the remaining sections ranged from 0.1 wt % to 2.4 wt % TOC. The core sections holding very little to no detectable OC consisted of coarser sandy material were estimated to be between 39 000 and 18 000 BP (years before present) in age. For this period, we assume the deposition of organic-poor material. Pore water stable isotope data from the Yedoma core indicated a continuously frozen state except for the surface sample, thereby ruling out Holocene reworking. In consequence, we see evidence that no strong organic matter (OM) decomposition took place in the sediments of the Yedoma core until today. The alas core from an adjacent thermokarst basin was strongly disturbed by lake development and permafrost thaw. Similar to the Yedoma core, some sections of the alas core were also OC poor ( <0.1 wt %) in 17 out of 28 samples. The Yedoma deposition was likely influenced by fluvial regimes in nearby streams and the Lena River shifting with climate. With its coarse sediments with low OC content (OC mean of 5.27 kg m −3 ), the Yedoma deposits in the Yukechi area differ from other Yedoma sites in North Yakutia that were generally characterized by silty sediments with higher OC contents (OC mean of 19 kg m −3 for the non-ice wedge sediment). Therefore, we conclude that sedimentary composition and deposition regimes of Yedoma may differ considerably within the Yedoma domain. The resulting heterogeneity should be taken into account for future upscaling approaches on the Yedoma carbon stock. The alas core, strongly affected by extensive thawing processes during the Holocene, indicates a possible future pathway of ground subsidence and further OC decomposition for thawing central Yakutian Yedoma deposits. |
format |
Other/Unknown Material |
author |
Windirsch, Torben Grosse, Guido Ulrich, Mathias Schirrmeister, Lutz Fedorov, Alexander N. Konstantinov, Pavel Y. Fuchs, Matthias Jongejans, Loeka L. Wolter, Juliane Opel, Thomas Strauss, Jens |
spellingShingle |
Windirsch, Torben Grosse, Guido Ulrich, Mathias Schirrmeister, Lutz Fedorov, Alexander N. Konstantinov, Pavel Y. Fuchs, Matthias Jongejans, Loeka L. Wolter, Juliane Opel, Thomas Strauss, Jens Organic carbon characteristics in ice-rich permafrost in alas and Yedoma deposits, central Yakutia, Siberia |
author_facet |
Windirsch, Torben Grosse, Guido Ulrich, Mathias Schirrmeister, Lutz Fedorov, Alexander N. Konstantinov, Pavel Y. Fuchs, Matthias Jongejans, Loeka L. Wolter, Juliane Opel, Thomas Strauss, Jens |
author_sort |
Windirsch, Torben |
title |
Organic carbon characteristics in ice-rich permafrost in alas and Yedoma deposits, central Yakutia, Siberia |
title_short |
Organic carbon characteristics in ice-rich permafrost in alas and Yedoma deposits, central Yakutia, Siberia |
title_full |
Organic carbon characteristics in ice-rich permafrost in alas and Yedoma deposits, central Yakutia, Siberia |
title_fullStr |
Organic carbon characteristics in ice-rich permafrost in alas and Yedoma deposits, central Yakutia, Siberia |
title_full_unstemmed |
Organic carbon characteristics in ice-rich permafrost in alas and Yedoma deposits, central Yakutia, Siberia |
title_sort |
organic carbon characteristics in ice-rich permafrost in alas and yedoma deposits, central yakutia, siberia |
publishDate |
2020 |
url |
https://doi.org/10.5194/bg-17-3797-2020 https://www.biogeosciences.net/17/3797/2020/ |
geographic |
Sakha |
geographic_facet |
Sakha |
genre |
Ice lena river permafrost Republic of Sakha Sakha Thermokarst wedge* Yakutia Yakutia Republic Siberia |
genre_facet |
Ice lena river permafrost Republic of Sakha Sakha Thermokarst wedge* Yakutia Yakutia Republic Siberia |
op_source |
eISSN: 1726-4189 |
op_relation |
info:eu-repo/grantAgreement/EC/FP7/338335 doi:10.5194/bg-17-3797-2020 https://www.biogeosciences.net/17/3797/2020/ |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/bg-17-3797-2020 |
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Biogeosciences |
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17 |
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14 |
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3797 |
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3814 |
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1766027701422915584 |