Ratio of In Situ CO<sub>2</sub> to CH<sub>4</sub> Production and Its Environmental Controls in Polygonal Tundra Soils of Samoylov Island, Northeastern Siberia

Galera, Leonardo de Aro; Eckhardt, Tim; Beer, Christian; Pfeiffer, Eva‐Maria; Knoblauch, Christian

doi:10.1029/2022jg006956

Cited by 4 publications

(2 citation statements)

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“…The high ratios indicate that the methanogenic community is viable and active in these active floodplain soils as shown in this study and in an earlier analysis at a nearby lowland site (Laurent et al., 2023); high CH 4 fluxes have been observed in situ from other floodplains in Siberia (Terentieva et al., 2019; van Huissteden et al., 2005). Field observations from other tundra sites in this region show similar trends: CH 4 emissions are driven by production in deep soils which occurs when they are warm enough and redox conditions are favorable, bringing the CH 4 :CO 2 production ratio closer to 1:1 later in the growing and thaw season (Galera et al., 2023). Additional field observations of CH 4 and CO 2 fluxes during the growing season would help to illustrate whether the anaerobic production potentials demonstrated by this incubation translate into significant CH 4 and CO 2 fluxes measured in the field.…”

Section: Discussionmentioning

confidence: 80%

Carbon Stocks and Potential Greenhouse Gas Production of Permafrost‐Affected Active Floodplains in the Lena River Delta

Herbst,

Fuchs,

Liebner

et al. 2024

JGR Biogeosciences

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Arctic warming increases the degradation of permafrost soils but little is known about floodplain soils in the permafrost region. This study quantifies soil organic carbon (SOC) and soil nitrogen stocks, and the potential CH4 and CO2 production from seven cores in the active floodplains in the Lena River Delta, Russia. The soils were sandy but highly heterogeneous, containing deep, organic rich deposits with >60% SOC stored below 30 cm. The mean SOC stocks in the top 1 m were 12.9 ± 6.0 kg C m−2. Grain size analysis and radiocarbon ages indicated highly dynamic environments with sediment re‐working. Potential CH4 and CO2 production from active floodplains was assessed using a 1‐year incubation at 20°C under aerobic and anaerobic conditions. Cumulative aerobic CO2 production mineralized a mean 4.6 ± 2.8% of initial SOC. The mean cumulative aerobic:anaerobic C production ratio was 2.3 ± 0.9. Anaerobic CH4 production comprised 50 ± 9% of anaerobic C mineralization; rates were comparable or exceeded those for permafrost region organic soils. Potential C production from the incubations was correlated with total organic carbon and varied strongly over space (among cores) and depth (active layer vs. permafrost). This study provides valuable information on the carbon cycle dynamics from active floodplains in the Lena River Delta and highlights the key spatial variability, both among sites and with depth, and the need to include these dynamic permafrost environments in future estimates of the permafrost carbon‐climate feedback.

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Section: Discussionmentioning

confidence: 80%

Carbon Stocks and Potential Greenhouse Gas Production of Permafrost‐Affected Active Floodplains in the Lena River Delta

Herbst,

Fuchs,

Liebner

et al. 2024

JGR Biogeosciences

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“…Permafrost thaw and the associated carbon feedbacks have been increasingly well‐studied (Schuur et al., 2022; Sjöberg et al., 2020; Virkkala et al., 2018), both as gradual thaw and abrupt thaw. Site‐level studies indicate that CH 4 and CO 2 emissions can be strongly positively correlated with active layer depth due to the effects of increasing soil temperature on microbial activity, so gradual thaw of permafrost that deepens the soil active layer results in larger C emissions (Celis et al., 2017; Galera et al., 2023). Estimates of C loss from abrupt thaw may exceed those from active layer deepening but are highly uncertain (Estop‐Aragonés et al., 2020; Zolkos et al., 2022).…”

Section: Terrestrial Carbon Fluxes In the Permafrost Regionmentioning

confidence: 99%

Permafrost Carbon: Progress on Understanding Stocks and Fluxes Across Northern Terrestrial Ecosystems

Treat,

Virkkala,

Burke

et al. 2024

JGR Biogeosciences

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Significant progress in permafrost carbon science made over the past decades include the identification of vast permafrost carbon stocks, the development of new pan‐Arctic permafrost maps, an increase in terrestrial measurement sites for CO2 and methane fluxes, and important factors affecting carbon cycling, including vegetation changes, periods of soil freezing and thawing, wildfire, and other disturbance events. Process‐based modeling studies now include key elements of permafrost carbon cycling and advances in statistical modeling and inverse modeling enhance understanding of permafrost region C budgets. By combining existing data syntheses and model outputs, the permafrost region is likely a wetland methane source and small terrestrial ecosystem CO2 sink with lower net CO2 uptake toward higher latitudes, excluding wildfire emissions. For 2002–2014, the strongest CO2 sink was located in western Canada (median: −52 g C m−2 y−1) and smallest sinks in Alaska, Canadian tundra, and Siberian tundra (medians: −5 to −9 g C m−2 y−1). Eurasian regions had the largest median wetland methane fluxes (16–18 g CH4 m−2 y−1). Quantifying the regional scale carbon balance remains challenging because of high spatial and temporal variability and relatively low density of observations. More accurate permafrost region carbon fluxes require: (a) the development of better maps characterizing wetlands and dynamics of vegetation and disturbances, including abrupt permafrost thaw; (b) the establishment of new year‐round CO2 and methane flux sites in underrepresented areas; and (c) improved models that better represent important permafrost carbon cycle dynamics, including non‐growing season emissions and disturbance effects.

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Soil microorganisms and methane emissions in response to short-term warming field incubation in Svalbard

Li,

Zhu,

Yang

et al. 2023

Front. Microbiol.

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IntroductionGlobal warming is caused by greenhouse gases (GHGs). It has been found that the release of methane (CH4) from Arctic permafrost, soil, ocean, and sediment is closely related to microbial composition and soil factors resulting from warming over several months or years. However, it is unclear for how long continuous warming due to global warming affects the microbial composition and GHG release from soils along Arctic glacial meltwater rivers.MethodsIn this study, the soil upstream of the glacial meltwater river (GR) and the estuary (GR-0) in Svalbard, with strong soil heterogeneity, was subjected to short-term field incubation at 2°C (in situ temperature), 10°C, and 20°C. The incubation was carried out under anoxic conditions and lasted for few days. Bacterial composition and CH4 production potential were determined based on high-throughput sequencing and physiochemical property measurements.ResultsOur results showed no significant differences in bacterial 16S rRNA gene copy number, bacterial composition, and methanogenic potential, as measured by mcrA gene copy number and CH4 concentration, during a 7- and 13-day warming field incubation with increasing temperatures, respectively. The CH4 concentration at the GR site was higher than that at the GR-0 site, while the mcrA gene was lower at the GR site than that at the GR-0 site.DiscussionBased on the warming field incubation, our results indicate that short-term warming, which is measured in days, affects soil microbial composition and CH4 concentration less than the spatial scale, highlighting the importance of warming time in influencing CH4 release from soil. In summary, our research implied that microbial composition and CH4 emissions in soil warming do not increase in the first several days, but site specificity is more important. However, emissions will gradually increase first and then decrease as warming time increases over the long term. These results are important for understanding and exploring the GHG emission fluxes of high-latitude ecosystems under global warming.

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Ratio of In Situ CO₂ to CH₄ Production and Its Environmental Controls in Polygonal Tundra Soils of Samoylov Island, Northeastern Siberia

Cited by 4 publications

References 111 publications

Carbon Stocks and Potential Greenhouse Gas Production of Permafrost‐Affected Active Floodplains in the Lena River Delta

Carbon Stocks and Potential Greenhouse Gas Production of Permafrost‐Affected Active Floodplains in the Lena River Delta

Permafrost Carbon: Progress on Understanding Stocks and Fluxes Across Northern Terrestrial Ecosystems

Soil microorganisms and methane emissions in response to short-term warming field incubation in Svalbard

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Ratio of In Situ CO2 to CH4 Production and Its Environmental Controls in Polygonal Tundra Soils of Samoylov Island, Northeastern Siberia

Cited by 4 publications

References 111 publications

Carbon Stocks and Potential Greenhouse Gas Production of Permafrost‐Affected Active Floodplains in the Lena River Delta

Carbon Stocks and Potential Greenhouse Gas Production of Permafrost‐Affected Active Floodplains in the Lena River Delta

Permafrost Carbon: Progress on Understanding Stocks and Fluxes Across Northern Terrestrial Ecosystems

Soil microorganisms and methane emissions in response to short-term warming field incubation in Svalbard

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Ratio of In Situ CO₂ to CH₄ Production and Its Environmental Controls in Polygonal Tundra Soils of Samoylov Island, Northeastern Siberia