A snapshot of CO2 and CH4 evolution in a thermokarst pond near Igarka, northern Siberia

Blodau, Christian; Rees, Rainer; Flessa, Heiner; Rodionov, Andrej; Guggenberger, Georg; Knorr, Klaus‐Holger; Shibistova, Olga; Zrazhevskaya, G. K.; Mikheeva, N.; Kasansky, Oleg A.

doi:10.1029/2007jg000652

Cited by 15 publications

(12 citation statements)

References 47 publications

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“…(2006) estimated that molecular diffusion of methane was 5% of total emissions from Siberian thermokarst lakes. The present study CH 4 fluxes were indeed lower than what was measured in other thermokarst lakes and ponds (Walter et al 2006;Wickland et al 2006;Blodau et al 2008) or permafrost-influenced aquatic systems (Nakano et al 2000; Strö m and Christensen 2007) but close to estimates based on the eddy covariance method in polygonal tundra (similar to the present study arctic site; Sachs et al 2008). However, ebullition in Canadian thaw ponds is possibly lower than ebullition from thick yedoma organic sediments beneath Siberian thaw lakes (Walter et al 2008).…”

Section: Discussionsupporting

confidence: 82%

Variability in greenhouse gas emissions from permafrost thaw ponds

Laurion¹,

Vincent²,

MacIntyre³

et al. 2009

Limnology & Oceanography

218

268

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Arctic climate change is leading to accelerated melting of permafrost and the mobilization of soil organic carbon pools that have accumulated over thousands of years. Photochemical and microbial transformation will liberate a fraction of this carbon to the atmosphere in the form of CO 2 and CH 4 . We quantified these fluxes in a series of permafrost thaw ponds in the Canadian Subarctic and Arctic and further investigated how optical properties of the carbon pool, the type of microbial assemblages, and light and mixing regimes influenced the rate of gas release. Most ponds were supersaturated in CO 2 and all of them in CH 4 . Gas fluxes as estimated from dissolved gas concentrations using a wind-based model varied from 220.5 to 114.4 mmol CO 2 m 22 d 21 , with negative fluxes recorded in arctic ponds colonized by benthic microbial mats, and from 0.03 to 5.62 mmol CH 4 m 22 d 21 . From a time series set of measurements in a subarctic pond over 8 d, calculated gas fluxes were on average 40% higher when using a newly derived equation for the gas transfer coefficient developed from eddy covariance measurements. The daily variation in gas fluxes was highly dependent on mixed layer dynamics. At the seasonal timescale, persistent thermal stratification and gas buildup at depth indicated that autumnal overturn is a critically important period for greenhouse gas emissions from subarctic ponds. These results underscore the increasingly important contribution of permafrost thaw ponds to greenhouse gas emissions and the need to account for local and regional variability in their limnological properties for global estimates.

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Section: Discussionsupporting

confidence: 82%

Variability in greenhouse gas emissions from permafrost thaw ponds

Laurion¹,

Vincent²,

MacIntyre³

et al. 2009

Limnology & Oceanography

218

268

View full text Add to dashboard Cite

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“…A host of factors can influence methanogenic pathways including substrate quality, pH, temperature, diversity of archea, H 2 partial pressure, and iron (Fe) content in northern aquatic sediments [ Nozhevnikova et al , 1994, Valentine et al , 2004, Conrad , 2005; Penning et al , 2005; Blodau et al , 2008]. High availability of labile organic substrates in lake and wetland sediments, particularly in sediments containing live plants, can support acetate production [ Duddleston et al , 2002], leading to methanogenesis by acetate fermentation; whereas environments with less labile organic substrates, or the absence of particular compounds exuded by living plants, can be dominated by the CO 2 reduction pathway [ Nakagawa et al , 2002].…”

Section: Discussionmentioning

confidence: 99%

Methane production and bubble emissions from arctic lakes: Isotopic implications for source pathways and ages

et al. 2008

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[1] This study reports an atmospheric methane (CH 4 ) source term previously uncharacterized regarding strength and isotopic composition. Methane emissions from 14 Siberian lakes and 9 Alaskan lakes were characterized using stable isotopes ( 13 C and D) and radiocarbon ( 14 C) analyses. We classified ebullition (bubbling) into three categories (background, point sources, and hot spots) on the basis of fluxes, major gas concentrations, and isotopic composition. Point sources and hot spots had a strong association with thermokarst (thaw) erosion because permafrost degradation along lake margins releases ancient organic matter into anaerobic lake bottoms, fueling methanogenesis. With increasing ebullition rate, we observed increasing CH 4 concentration of greater radiocarbon age, depletion of 13 C CH4 , and decreasing bubble N 2 content. Microbial oxidation of methane was observed in bubbles that became trapped below and later within winter lake ice; however, oxidation appeared insignificant in bubbles sampled immediately after release from sediments. Methanogenic pathways differed among the bubble sources: CO 2 reduction supported point source and hot spot ebullition to a large degree, while acetate fermentation appeared to contribute to background bubbling. To provide annual whole-lake and regional CH 4 isofluxes for the Siberian lakes, we combined maps of bubble source distributions with long-term, continuous flux measurements and isotopic composition. In contrast to typical values used in inverse models of atmospheric CH 4 for northern wetland sources (d 13 C CH4 = À58%, 14 C age modern), which have not included northern lake ebullition as a source, we show that this large, new source of high-latitude CH 4 from lakes is isotopically distinct (d 13 C CH4 = À70%, 14 C age 16,500 years, for North Siberian lakes).Citation: Walter, K. M., J. P. Chanton, F. S. Chapin III, E. A. G. Schuur, and S. A. Zimov (2008), Methane production and bubble emissions from arctic lakes: Isotopic implications for source pathways and ages,

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“…However, the vast area of western Siberia containing the largest peat resources in the world, dominated by discontinuous permafrost and thus being potentially the most vulnerable part of the boreal permafrostbearing zone, remains poorly understood. In contrast to several studies on the western Siberian rivers (Frey and Smith, 2005;Frey et al, 2007;Frey and McClelland, 2009;Gordeev et al, 2004), lakes and Arctic ponds of eastern and central Siberia (Semiletov et al, 1996;Zimov et al, 1997;Blodau et al, 2008), the lakes of western Siberia remained virtually unexplored, both from the viewpoint of OC and bacterioplankton concentration as well as the trace element (TE) speciation and colloidal status. In consideration of the very high proportion of newly formed lakes in western Siberia (up to 48% of the surface area) (Zimov et al, 1997;Hinkel et al, 2003;Riordan et al, 2006) and as high as 60-80% in the Pur Taz and Nadum river basins (Zakharova et al, 2009), there is little doubt that the western Siberian thermokarst lakes are likely to act as an important source of CO 2 in the atmosphere.…”

Section: Introductionmentioning

confidence: 94%

Effect of permafrost thawing on organic carbon and trace element colloidal speciation in the thermokarst lakes of western Siberia

et al. 2011

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To examine the mechanisms of carbon mobilization and biodegradation during permafrost thawing and to establish a link between organic carbon (OC) and other chemical and microbiological parameters in forming thermokarst (thaw) lakes, we studied the biogeochemistry of OC and trace elements (TEs) in a chronosequence of small lakes that are being formed due to permafrost thawing in the northern part of western Siberia. Twenty lakes and small ponds of various sizes and ages were sampled for dissolved and colloidal organic carbon, metals and culturable heterotrophic bacterial cell number. We observed a sequence of ecosystems from peat thawing and palsa degradation due to permafrost subsidence in small ponds to large, km-size lakes that are subject to drainage to, finally, the khasyrey (drained lake) formation. There is a systematic evolution of both total dissolved and colloidal concentration of OC and TEs in the lake water along with the chronosequence of lake development that may be directly linked to the microbial mineralization of dissolved organic matter and the liberation of the inorganic components (Fe, Al, and TEs) from the organo-mineral colloids. In this chronosequence of lake development, we observed an apparent decrease in the relative proportion of low molecular weight <1 kDa (1 kDa ~ 1 nm) OC concentration along with a decrease in the concentration of total dissolved (<0.45 μm) OC. This decrease was accompanied by an increase in the small size organic ligands (probably autochthonous exometabolites produced by the phytoplankton) and a simultaneous decrease in the proportion of large-size organic (humic) complexes of allochthonous (soil) origin. This evolution may be due to the activity of heterotrophic bacterioplankton that use allochthonous organic matter and dissolved nutrients originating from peat lixiviation. Most insoluble TEs demonstrate a systematic decrease in concentration during filtration (5 μm, 0.45 μm) exhibiting a similar pattern among different samples. At the same time, there is an increase in the relative proportion of large size particles over the <1 kDa fraction for most insoluble elements along the chronosequence of lake evolution. TEs are likely to be bound to colloidal OC and coprecipitate with the mineral (Fe, Al) part of the colloids. Upon progressive consumption of dissolved OC by the heterotrophic bacteria, there is liberation of Fe, Al, and insoluble TEs in the water column that may be subjected to coagulation in the form of particles or large-size mineral colloids

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A snapshot of CO₂ and CH₄ evolution in a thermokarst pond near Igarka, northern Siberia

Cited by 15 publications

References 47 publications

Variability in greenhouse gas emissions from permafrost thaw ponds

Variability in greenhouse gas emissions from permafrost thaw ponds

Methane production and bubble emissions from arctic lakes: Isotopic implications for source pathways and ages

Effect of permafrost thawing on organic carbon and trace element colloidal speciation in the thermokarst lakes of western Siberia

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