Greenhouse gas production in degrading ice-rich permafrost deposits in northeastern Siberia. Walz, J., Knoblauch, C., Tigges, R., Opel, T., Schirrmeister, L., & Pfeiffer, E. Biogeosciences, 15(17):5423–5436, September, 2018. Publisher: Copernicus GmbH
Greenhouse gas production in degrading ice-rich permafrost deposits in northeastern Siberia [link]Paper  doi  abstract   bibtex   
\textlessp\textgreater\textlessstrong\textgreaterAbstract.\textless/strong\textgreater Permafrost deposits have been a sink for atmospheric carbon for millennia. Thaw-erosional processes, however, can lead to rapid degradation of ice-rich permafrost and the release of substantial amounts of organic carbon (OC). The amount of the OC stored in these deposits and their potential to be microbially decomposed to the greenhouse gases carbon dioxide (\textlessspan class="inline-formula"\textgreaterCO$_{\textrm{2}}$\textless/span\textgreater) and methane (\textlessspan class="inline-formula"\textgreaterCH$_{\textrm{4}}$\textless/span\textgreater) depends on climatic and environmental conditions during deposition and the decomposition history before incorporation into the permafrost. Here, we examine potential greenhouse gas production as a result of degrading ice-rich permafrost deposits from three locations in the northeastern Siberian Laptev Sea region. The deposits span a period of about 55 kyr from the last glacial period and Holocene interglacial. Samples from all three locations were incubated under aerobic and anaerobic conditions for 134 days at 4 \textlessspan class="inline-formula"\textgreater$^{\textrm{∘}}$\textless/span\textgreaterC. Greenhouse gas production was generally higher in deposits from glacial periods, where 0.2 %–6.1 % of the initially available OC was decomposed to \textlessspan class="inline-formula"\textgreaterCO$_{\textrm{2}}$\textless/span\textgreater. In contrast, only 0.1 %–4.0 % of initial OC was decomposed in permafrost deposits from the Holocene and the late glacial transition. Within the deposits from the Kargin interstadial period (Marine Isotope Stage 3), local depositional environments, especially soil moisture, also affected the preservation of OC. Sediments deposited under wet conditions contained more labile OC and thus produced more greenhouse gases than sediments deposited under drier conditions. To assess the greenhouse gas production potentials over longer periods, deposits from two locations were incubated for a total of 785 days. However, more than 50 % of total \textlessspan class="inline-formula"\textgreaterCO$_{\textrm{2}}$\textless/span\textgreater production over 785 days occurred within the first 134 days under aerobic conditions, while 80 % were produced over the same period under anaerobic conditions, which emphasizes the nonlinearity of the OC decomposition processes. Methanogenesis was generally observed in active layer samples but only sporadically in permafrost samples and was several orders of magnitude smaller than \textlessspan class="inline-formula"\textgreaterCO$_{\textrm{2}}$\textless/span\textgreater production.\textless/p\textgreater
@article{walz_greenhouse_2018,
	title = {Greenhouse gas production in degrading ice-rich permafrost deposits in northeastern {Siberia}},
	volume = {15},
	issn = {1726-4170},
	url = {https://www.biogeosciences.net/15/5423/2018/},
	doi = {10.5194/bg-15-5423-2018},
	abstract = {{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} Permafrost deposits have been a sink for atmospheric carbon for millennia. Thaw-erosional processes, however, can lead to rapid degradation of ice-rich permafrost and the release of substantial amounts of organic carbon (OC). The amount of the OC stored in these deposits and their potential to be microbially decomposed to the greenhouse gases carbon dioxide ({\textless}span class="inline-formula"{\textgreater}CO$_{\textrm{2}}${\textless}/span{\textgreater}) and methane ({\textless}span class="inline-formula"{\textgreater}CH$_{\textrm{4}}${\textless}/span{\textgreater}) depends on climatic and environmental conditions during deposition and the decomposition history before incorporation into the permafrost. Here, we examine potential greenhouse gas production as a result of degrading ice-rich permafrost deposits from three locations in the northeastern Siberian Laptev Sea region. The deposits span a period of about 55\ kyr from the last glacial period and Holocene interglacial. Samples from all three locations were incubated under aerobic and anaerobic conditions for 134 days at 4\ {\textless}span class="inline-formula"{\textgreater}$^{\textrm{∘}}${\textless}/span{\textgreater}C. Greenhouse gas production was generally higher in deposits from glacial periods, where 0.2\ \%–6.1\ \% of the initially available OC was decomposed to {\textless}span class="inline-formula"{\textgreater}CO$_{\textrm{2}}${\textless}/span{\textgreater}. In contrast, only 0.1\ \%–4.0\ \% of initial OC was decomposed in permafrost deposits from the Holocene and the late glacial transition. Within the deposits from the Kargin interstadial period (Marine Isotope Stage 3), local depositional environments, especially soil moisture, also affected the preservation of OC. Sediments deposited under wet conditions contained more labile OC and thus produced more greenhouse gases than sediments deposited under drier conditions. To assess the greenhouse gas production potentials over longer periods, deposits from two locations were incubated for a total of 785 days. However, more than 50\ \% of total {\textless}span class="inline-formula"{\textgreater}CO$_{\textrm{2}}${\textless}/span{\textgreater} production over 785 days occurred within the first 134 days under aerobic conditions, while 80\ \% were produced over the same period under anaerobic conditions, which emphasizes the nonlinearity of the OC decomposition processes. Methanogenesis was generally observed in active layer samples but only sporadically in permafrost samples and was several orders of magnitude smaller than {\textless}span class="inline-formula"{\textgreater}CO$_{\textrm{2}}${\textless}/span{\textgreater} production.{\textless}/p{\textgreater}},
	language = {English},
	number = {17},
	urldate = {2020-06-10},
	journal = {Biogeosciences},
	author = {Walz, Josefine and Knoblauch, Christian and Tigges, Ronja and Opel, Thomas and Schirrmeister, Lutz and Pfeiffer, Eva-Maria},
	month = sep,
	year = {2018},
	note = {Publisher: Copernicus GmbH},
	keywords = {\#nosource},
	pages = {5423--5436},
}

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