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Greenhouse gas production and lipid biomarker distribution in Yedoma and Alas thermokarst lake sediments in Eastern Siberia.

https://arctichealth.org/en/permalink/ahliterature311240
Source
Glob Chang Biol. 2021 Mar 28; :
Publication Type
Journal Article
Date
Mar-28-2021
Author
Loeka L Jongejans
Susanne Liebner
Christian Knoblauch
Kai Mangelsdorf
Mathias Ulrich
Guido Grosse
George Tanski
Alexander N Fedorov
Pavel Ya Konstantinov
Torben Windirsch
Julia Wiedmann
Jens Strauss
Author Affiliation
Alfred Wegener Institute Helmholtz Center for Polar and Marine Research, Permafrost Research Section, Potsdam, Germany.
Source
Glob Chang Biol. 2021 Mar 28; :
Date
Mar-28-2021
Language
English
Publication Type
Journal Article
Abstract
Permafrost thaw leads to thermokarst lake formation and talik growth tens of meters deep, enabling microbial decomposition of formerly frozen organic matter (OM). We analyzed two 17-m-long thermokarst lake sediment cores taken in Central Yakutia, Russia. One core was from an Alas lake in a Holocene thermokarst basin that underwent multiple lake generations, and the second core from a young Yedoma upland lake (formed ~70 years ago) whose sediments have thawed for the first time since deposition. This comparison provides a glance into OM fate in thawing Yedoma deposits. We analyzed total organic carbon (TOC) and dissolved organic carbon (DOC) content, n-alkane concentrations, and bacterial and archaeal membrane markers. Furthermore, we conducted 1-year-long incubations (4°C, dark) and measured anaerobic carbon dioxide (CO2 ) and methane (CH4 ) production. The sediments from both cores contained little TOC (0.7 ± 0.4 wt%), but DOC values were relatively high, with the highest values in the frozen Yedoma lake sediments (1620 mg L-1 ). Cumulative greenhouse gas (GHG) production after 1 year was highest in the Yedoma lake sediments (226 ± 212 µg CO2 -C g-1  dw, 28 ± 36 µg CH4 -C g-1  dw) and 3 and 1.5 times lower in the Alas lake sediments, respectively (75 ± 76 µg CO2 -C g-1  dw, 19 ± 29 µg CH4 -C g-1  dw). The highest CO2 production in the frozen Yedoma lake sediments likely results from decomposition of readily bioavailable OM, while highest CH4 production in the non-frozen top sediments of this core suggests that methanogenic communities established upon thaw. The lower GHG production in the non-frozen Alas lake sediments resulted from advanced OM decomposition during Holocene talik development. Furthermore, we found that drivers of CO2 and CH4 production differ following thaw. Our results suggest that GHG production from TOC-poor mineral deposits, which are widespread throughout the Arctic, can be substantial. Therefore, our novel data are relevant for vast ice-rich permafrost deposits vulnerable to thermokarst formation.
PubMed ID
33774862 View in PubMed
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Nearshore Zone Dynamics Determine Pathway of Organic Carbon From Eroding Permafrost Coasts.

https://arctichealth.org/en/permalink/ahliterature304693
Source
Geophys Res Lett. 2020 Aug 16; 47(15):e2020GL088561
Publication Type
Journal Article
Date
Aug-16-2020
Author
Dirk Jong
Lisa Bröder
George Tanski
Michael Fritz
Hugues Lantuit
Tommaso Tesi
Negar Haghipour
Timothy I Eglinton
Jorien E Vonk
Author Affiliation
Department of Earth Sciences Vrije Universiteit Amsterdam Amsterdam The Netherlands.
Source
Geophys Res Lett. 2020 Aug 16; 47(15):e2020GL088561
Date
Aug-16-2020
Language
English
Publication Type
Journal Article
Abstract
Collapse of permafrost coasts delivers large quantities of particulate organic carbon (POC) to Arctic coastal areas. With rapidly changing environmental conditions, sediment and organic carbon (OC) mobilization and transport pathways are also changing. Here, we assess the sources and sinks of POC in the highly dynamic nearshore zone of Herschel Island-Qikiqtaruk (Yukon, Canada). Our results show that POC concentrations sharply decrease, from 15.9 to 0.3 mg L-1, within the first 100-300 m offshore. Simultaneously, radiocarbon ages of POC drop from 16,400 to 3,600 14C years, indicating rapid settling of old permafrost POC to underlying sediments. This suggests that permafrost OC is, apart from a very narrow resuspension zone (
PubMed ID
32999517 View in PubMed
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Transformation of terrestrial organic matter along thermokarst-affected permafrost coasts in the Arctic.

https://arctichealth.org/en/permalink/ahliterature279291
Source
Sci Total Environ. 2017 Jan 11;
Publication Type
Article
Date
Jan-11-2017
Author
George Tanski
Hugues Lantuit
Saskia Ruttor
Christian Knoblauch
Boris Radosavljevic
Jens Strauss
Juliane Wolter
Anna M Irrgang
Justine Ramage
Michael Fritz
Source
Sci Total Environ. 2017 Jan 11;
Date
Jan-11-2017
Language
English
Publication Type
Article
Abstract
The changing climate in the Arctic has a profound impact on permafrost coasts, which are subject to intensified thermokarst formation and erosion. Consequently, terrestrial organic matter (OM) is mobilized and transported into the nearshore zone. Yet, little is known about the fate of mobilized OM before and after entering the ocean. In this study we investigated a retrogressive thaw slump (RTS) on Qikiqtaruk - Herschel Island (Yukon coast, Canada). The RTS was classified into an undisturbed, a disturbed (thermokarst-affected) and a nearshore zone and sampled systematically along transects. Samples were analyzed for total and dissolved organic carbon and nitrogen (TOC, DOC, TN, DN), stable carbon isotopes (d(13)C-TOC, d(13)C-DOC), and dissolved inorganic nitrogen (DIN), which were compared between the zones. C/N-ratios, d(13)C signatures, and ammonium (NH4-N) concentrations were used as indicators for OM degradation along with biomarkers (n-alkanes, n-fatty acids, n-alcohols). Our results show that OM significantly decreases after disturbance with a TOC and DOC loss of 77 and 55% and a TN and DN loss of 53 and 48%, respectively. C/N-ratios decrease significantly, whereas NH4-N concentrations slightly increase in freshly thawed material. In the nearshore zone, OM contents are comparable to the disturbed zone. We suggest that the strong decrease in OM is caused by initial dilution with melted massive ice and immediate offshore transport via the thaw stream. In the mudpool and thaw stream, OM is subject to degradation, whereas in the slump floor the nitrogen decrease is caused by recolonizing vegetation. Within the nearshore zone of the ocean, heavier portions of OM are directly buried in marine sediments close to shore. We conclude that RTS have profound impacts on coastal environments in the Arctic. They mobilize nutrients from permafrost, substantially decrease OM contents and provide fresh water and nutrients at a point source.
PubMed ID
28088543 View in PubMed
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