pH controls over anaerobic carbon mineralization, the efficiency of methane production, and methanogenic pathways in peatlands across an ombrotrophic–minerotrophic gradient

Ye, Rongzhong; Jin, Qusheng; Bohannan, B. J. M.; Keller, Jason K.; McAllister, Steven A.; Bridgham, Scott D.

doi:10.1016/j.soilbio.2012.05.015

Cited by 196 publications

(162 citation statements)

References 60 publications

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“…4A) driven by changing plant inputs and increasing pH (Table 1 and Table S1). However, pH's effect on decomposition (both directly through impacts on microbial activity and indirectly via shifting organic acids to their less inhibitory anionic forms) is unlikely to be the sole process governing decomposition rates in this system, given Ye et al's (45) demonstration that incubating bog peat at fen-typical pH did not stimulate fen-like CH 4 production to the levels seen in fen peat. Phenolic abundance may also decrease along the thaw sequence due to the enzymatic latch mechanism (46), whereby the enzyme phenol oxidase (which degrades phenolic compounds) depends on bimolecular oxygen availability.…”

Section: Discussionmentioning

confidence: 88%

Changes in peat chemistry associated with permafrost thaw increase greenhouse gas production

Hodgkins¹,

Tfaily²,

McCalley

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

271

360

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Carbon release due to permafrost thaw represents a potentially major positive climate change feedback. The magnitude of carbon loss and the proportion lost as methane (CH 4 ) vs. carbon dioxide (CO 2 ) depend on factors including temperature, mobilization of previously frozen carbon, hydrology, and changes in organic matter chemistry associated with environmental responses to thaw. While the first three of these effects are relatively well understood, the effect of organic matter chemistry remains largely unstudied. To address this gap, we examined the biogeochemistry of peat and dissolved organic matter (DOM) along a ∼40-y permafrost thaw progression from recently-to fully thawed sites in Stordalen Mire (68.35°N,19.05°E), a thawing peat plateau in northern Sweden. Thaw-induced subsidence and the resulting inundation along this progression led to succession in vegetation types accompanied by an evolution in organic matter chemistry. Peat C/N ratios decreased whereas humification rates increased, and DOM shifted toward lower molecular weight compounds with lower aromaticity, lower organic oxygen content, and more abundant microbially produced compounds. Corresponding changes in decomposition along this gradient included increasing CH 4 and CO 2 production potentials, higher relative CH 4 /CO 2 ratios, and a shift in CH 4 production pathway from CO 2 reduction to acetate cleavage. These results imply that subsidence and thermokarst-associated increases in organic matter lability cause shifts in biogeochemical processes toward faster decomposition with an increasing proportion of carbon released as CH 4 . This impact of permafrost thaw on organic matter chemistry could intensify the predicted climate feedbacks of increasing temperatures, permafrost carbon mobilization, and hydrologic changes.H igh-latitude soils in the Northern Hemisphere contain an estimated 1,400-1,850 petagrams (Pg) of carbon, of which ∼277 Pg is in peatlands within the permafrost zone (1, 2). This quantity of 277 Pg represents over one-third of the carbon stock in the atmosphere (ca. 800 Pg) (3). The fate of this carbon in a warming climate-i.e., the responses of net carbon balance and CH 4 emissions-is important in predicting climate feedbacks of permafrost thaw. Although northern peatlands are currently a net carbon sink, and have been since the end of the last glaciation, they are a net source of CH 4 (4, 5), emitting 0.046-0.09 Pg of carbon as CH 4 per year (4, 6, 7). Due to CH 4 's disproportionate global warming potential (33× CO 2 for 1 kg CH 4 vs. 1 kg CO 2 at a 100-y timescale) (8), this is equivalent to 6-12% of annual fossil fuel emissions of CO 2 (8.7 Pg of C) (9). The thaw of permafrost peatlands may alter their CH 4 and CO 2 emissions due to mobilization of formerly frozen carbon, higher temperatures, altered redox conditions, and evolving organic matter chemistry. Changes in carbon emissions, and in CH 4 emission in particular, could have potentially significant climate impacts. CH 4 is produced by two primary mechanisms (10-12),...

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Section: Discussionmentioning

confidence: 88%

Changes in peat chemistry associated with permafrost thaw increase greenhouse gas production

Hodgkins¹,

Tfaily²,

McCalley

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

271

360

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“…This phenomenon is confirmed in controlled anaerobic incubations of thawing permafrost soils, in which alternate inorganic TEAs are known to be low (Hodgkins et al , 2015. Hypothesized explanations for this puzzle include the presence of organic TEAs (Bridgham et al 1998), the buildup of fermentation by-products such as acetate (which, intriguingly, is often not consumed by acetoclastic methanogens in bogs) (Duddleston et al 2002, Keller & Bridgham 2007, and the presence of phenols or aromatic substances that may have an antibiotic or toxic effect on microbes (Bridgham et al 2013, Hines et al 2008, Ye et al 2012). …”

Section: Figurementioning

confidence: 83%

Permafrost Meta-Omics and Climate Change

Mackelprang

Saleska²,

Jacobsen

et al. 2016

Annu. Rev. Earth Planet. Sci.

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Permanently frozen soil, or permafrost, covers a large portion of the Earth's terrestrial surface and represents a unique environment for cold-adapted microorganisms. As permafrost thaws, previously protected organic matter becomes available for microbial degradation. Microbes that decompose soil carbon produce carbon dioxide and other greenhouse gases, contributing substantially to climate change. Next-generation sequencing and other -omics technologies offer opportunities to discover the mechanisms by which microbial communities regulate the loss of carbon and the emission of greenhouse gases from thawing permafrost regions. Analysis of nucleic acids and proteins taken directly from permafrost-associated soils has provided new insights into microbial communities and their functions in Arctic environments that are increasingly impacted by climate change. In this article we review current information from various molecular -omics studies on permafrost microbial ecology and explore the relevance of these insights to our current understanding of the dynamics of permafrost loss due to climate change.

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“…The lower pH inhibits methanogen growth [34]. Higher pH enhances CH 4 production when pH ranges from 3 to 7 [35]. The production of CH 4 declines when pH exceeds 8 [36].…”

Section: Influence Factors Of Ghg Emissionmentioning

confidence: 99%

Emission Laws and Influence Factors of Greenhouse Gases in Saline-Alkali Paddy Fields

Tang

Liang

et al. 2016

Sustainability

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Abstract:The study of greenhouse gas emissions has become a global focus, but few studies have considered saline-alkali paddy fields. Gas samples and saline-alkali soil samples were collected during the green, tillering, booting, heading and grain filling stages. The emission fluxes of CO 2 , CH 4 , and N 2 O as well as the pH, soil soluble salt, available nitrogen, and soil organic carbon contents were detected to reveal the greenhouse gas (GHG) emission laws and influence factors in saline-alkali paddy fields. Overall, GHG emissions of paddy soil during the growing season increased, then decreased, and then increased again and peaked at booting stage. The emission fluxes of CO 2 and CH 4 were observed as having two peaks and a single peak, respectively. Both the total amount of GHG emission and its different components of CO 2 , CH 4 , and N 2 O increased with the increasing reclamation period of paddy fields. A positive correlation was found between the respective emission fluxes of CO 2 , CH 4 , and N 2 O and the available nitrogen and SOC, whereas a negative correlation was revealed between the fluxes of CO 2 , CH 4 , and N 2 O and soil pH and soil conductivity. The study is beneficial to assessing the impact of paddy reclamation on regional greenhouse gas emissions and is relevant to illustrating the mechanisms concerning the carbon cycle in paddy soils.

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pH controls over anaerobic carbon mineralization, the efficiency of methane production, and methanogenic pathways in peatlands across an ombrotrophic–minerotrophic gradient

Cited by 196 publications

References 60 publications

Changes in peat chemistry associated with permafrost thaw increase greenhouse gas production

Changes in peat chemistry associated with permafrost thaw increase greenhouse gas production

Permafrost Meta-Omics and Climate Change

Emission Laws and Influence Factors of Greenhouse Gases in Saline-Alkali Paddy Fields

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