Organic-matter quality of deep permafrost carbon : a study from Arctic Siberia

The organic-carbon (OC) pool accumulated in Arctic permafrost (perennially frozen ground) equals the carbon stored in the modern atmosphere. To give an idea of how Yedoma region permafrost could respond under future climatic warming, we conducted a study to quantify the organic-matter quality (here...

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Main Authors: Strauss, Jens, Schirrmeister, Lutz, Mangelsdorf, K., Eichhorn, L., Wetterich, S., Herzschuh, Ulrike
Format: Text
Language:English
Published: Universität Potsdam 2019
Subjects:
Ice
Online Access:https://dx.doi.org/10.25932/publishup-40953
https://publishup.uni-potsdam.de/40953
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language English
description The organic-carbon (OC) pool accumulated in Arctic permafrost (perennially frozen ground) equals the carbon stored in the modern atmosphere. To give an idea of how Yedoma region permafrost could respond under future climatic warming, we conducted a study to quantify the organic-matter quality (here defined as the intrinsic potential to be further transformed, decomposed, and mineralized) of late Pleistocene (Yedoma) and Holocene (thermokarst) deposits on the Buor-Khaya Peninsula, northeast Siberia. The objective of this study was to develop a stratigraphic classified organic-matter quality characterization. For this purpose the degree of organic-matter decomposition was estimated by using a multiproxy approach. We applied sedimentological (grain-size analyses, bulk density, ice content) and geochemical parameters (total OC, stable carbon isotopes (delta C-13),total organic carbon : nitrogen (C / N) ratios) as well as lipid biomarkers (n-alkanes, n-fatty acids, hopanes, triterpenoids, and biomarker indices, i.e., average chain length, carbon preference index (CPI), and higher-plant fatty-acid index (HPFA)). Our results show that the Yedoma and thermokarst organic-matter qualities for further decomposition exhibit no obvious degradation-depth trend. Relatively, the C / N and delta C-13 values and the HPFA index show a significantly better preservation of the organic matter stored in thermokarst deposits compared to Yedoma deposits. The CPI data suggest less degradation of the organic matter from both deposits, with a higher value for Yedoma organic matter. As the interquartile ranges of the proxies mostly over-lap, we interpret this as indicating comparable quality for further decomposition for both kinds of deposits with likely better thermokarst organic-matter quality. Supported by principal component analyses, the sediment parameters and quality proxies of Yedoma and thermokarst deposits could not be unambiguously separated from each other. This revealed that the organic-matter vulnerability is heterogeneous and depends on different decomposition trajectories and the previous decomposition and preservation history. Elucidating this was one of the major new contributions of our multiproxy study. With the addition of biomarker data, it was possible to show that permafrost organic-matter degradation likely occurs via a combination of (uncompleted) degradation cycles or a cascade of degradation steps rather than as a linear function of age or sediment facies. We conclude that the amount of organic matter in the studied sediments is high for mineral soils and of good quality and therefore susceptible to future decomposition. The lack of depth trends shows that permafrost acts like a giant freezer, preserving the constant quality of ancient organic matter. When undecomposed Yedoma organic matter is mobilized via thermokarst processes, the fate of this carbon depends largely on the environmental conditions; the carbon could be preserved in an undecomposed state till refreezing occurs. If modern input has occurred, thermokarst organic matter could be of a better quality for future microbial decomposition than that found in Yedoma deposits. : Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe, 514
format Text
author Strauss, Jens
Schirrmeister, Lutz
Mangelsdorf, K.
Eichhorn, L.
Wetterich, S.
Herzschuh, Ulrike
spellingShingle Strauss, Jens
Schirrmeister, Lutz
Mangelsdorf, K.
Eichhorn, L.
Wetterich, S.
Herzschuh, Ulrike
Organic-matter quality of deep permafrost carbon : a study from Arctic Siberia
author_facet Strauss, Jens
Schirrmeister, Lutz
Mangelsdorf, K.
Eichhorn, L.
Wetterich, S.
Herzschuh, Ulrike
author_sort Strauss, Jens
title Organic-matter quality of deep permafrost carbon : a study from Arctic Siberia
title_short Organic-matter quality of deep permafrost carbon : a study from Arctic Siberia
title_full Organic-matter quality of deep permafrost carbon : a study from Arctic Siberia
title_fullStr Organic-matter quality of deep permafrost carbon : a study from Arctic Siberia
title_full_unstemmed Organic-matter quality of deep permafrost carbon : a study from Arctic Siberia
title_sort organic-matter quality of deep permafrost carbon : a study from arctic siberia
publisher Universität Potsdam
publishDate 2019
url https://dx.doi.org/10.25932/publishup-40953
https://publishup.uni-potsdam.de/40953
long_lat ENVELOPE(127.803,127.803,72.287,72.287)
ENVELOPE(135.167,135.167,60.567,60.567)
geographic Arctic
Buor-Khaya
Khaya
geographic_facet Arctic
Buor-Khaya
Khaya
genre Arctic
Ice
permafrost
Thermokarst
Siberia
genre_facet Arctic
Ice
permafrost
Thermokarst
Siberia
op_rights Creative Commons - Namensnennung, 4.0 International
https://creativecommons.org/licenses/by/4.0
op_rightsnorm CC-BY
op_doi https://doi.org/10.25932/publishup-40953
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spelling ftdatacite:10.25932/publishup-40953 2023-05-15T15:08:00+02:00 Organic-matter quality of deep permafrost carbon : a study from Arctic Siberia Strauss, Jens Schirrmeister, Lutz Mangelsdorf, K. Eichhorn, L. Wetterich, S. Herzschuh, Ulrike 2019 application/pdf application/zip https://dx.doi.org/10.25932/publishup-40953 https://publishup.uni-potsdam.de/40953 en eng Universität Potsdam Creative Commons - Namensnennung, 4.0 International https://creativecommons.org/licenses/by/4.0 CC-BY article-journal Text ScholarlyArticle 2019 ftdatacite https://doi.org/10.25932/publishup-40953 2021-11-05T12:55:41Z The organic-carbon (OC) pool accumulated in Arctic permafrost (perennially frozen ground) equals the carbon stored in the modern atmosphere. To give an idea of how Yedoma region permafrost could respond under future climatic warming, we conducted a study to quantify the organic-matter quality (here defined as the intrinsic potential to be further transformed, decomposed, and mineralized) of late Pleistocene (Yedoma) and Holocene (thermokarst) deposits on the Buor-Khaya Peninsula, northeast Siberia. The objective of this study was to develop a stratigraphic classified organic-matter quality characterization. For this purpose the degree of organic-matter decomposition was estimated by using a multiproxy approach. We applied sedimentological (grain-size analyses, bulk density, ice content) and geochemical parameters (total OC, stable carbon isotopes (delta C-13),total organic carbon : nitrogen (C / N) ratios) as well as lipid biomarkers (n-alkanes, n-fatty acids, hopanes, triterpenoids, and biomarker indices, i.e., average chain length, carbon preference index (CPI), and higher-plant fatty-acid index (HPFA)). Our results show that the Yedoma and thermokarst organic-matter qualities for further decomposition exhibit no obvious degradation-depth trend. Relatively, the C / N and delta C-13 values and the HPFA index show a significantly better preservation of the organic matter stored in thermokarst deposits compared to Yedoma deposits. The CPI data suggest less degradation of the organic matter from both deposits, with a higher value for Yedoma organic matter. As the interquartile ranges of the proxies mostly over-lap, we interpret this as indicating comparable quality for further decomposition for both kinds of deposits with likely better thermokarst organic-matter quality. Supported by principal component analyses, the sediment parameters and quality proxies of Yedoma and thermokarst deposits could not be unambiguously separated from each other. This revealed that the organic-matter vulnerability is heterogeneous and depends on different decomposition trajectories and the previous decomposition and preservation history. Elucidating this was one of the major new contributions of our multiproxy study. With the addition of biomarker data, it was possible to show that permafrost organic-matter degradation likely occurs via a combination of (uncompleted) degradation cycles or a cascade of degradation steps rather than as a linear function of age or sediment facies. We conclude that the amount of organic matter in the studied sediments is high for mineral soils and of good quality and therefore susceptible to future decomposition. The lack of depth trends shows that permafrost acts like a giant freezer, preserving the constant quality of ancient organic matter. When undecomposed Yedoma organic matter is mobilized via thermokarst processes, the fate of this carbon depends largely on the environmental conditions; the carbon could be preserved in an undecomposed state till refreezing occurs. If modern input has occurred, thermokarst organic matter could be of a better quality for future microbial decomposition than that found in Yedoma deposits. : Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe, 514 Text Arctic Ice permafrost Thermokarst Siberia DataCite Metadata Store (German National Library of Science and Technology) Arctic Buor-Khaya ENVELOPE(127.803,127.803,72.287,72.287) Khaya ENVELOPE(135.167,135.167,60.567,60.567)