scholarly journals Non-microbial methane formation in oxic soils

2012 ◽  
Vol 9 (12) ◽  
pp. 5291-5301 ◽  
Author(s):  
A. Jugold ◽  
F. Althoff ◽  
M. Hurkuck ◽  
M. Greule ◽  
K. Lenhart ◽  
...  
Keyword(s):  
Organic Matter ◽  
Large Fraction ◽  
Methane Formation ◽  
Strictly Anaerobic ◽  
Atmospheric Methane ◽  
Methane Cycle ◽  
Alternative Source ◽  
Emission Fluxes ◽  
Methane Fluxes ◽  
Methane Source

Abstract. Methane plays an important role as a radiatively and chemically active gas in our atmosphere. Until recently, sources of atmospheric methane in the biosphere have been attributed to strictly anaerobic microbial processes during degradation of organic matter. However, a large fraction of methane produced in the anoxic soil layers does not reach the atmosphere due to methanotrophic consumption in the overlaying oxic soil. Although methane fluxes from aerobic soils have been observed, an alternative source other than methanogenesis has not been identified thus far. Here we provide evidence for non-microbial methane formation in soils under oxic conditions. We found that soils release methane upon heating and other environmental factors like ultraviolet irradiation, and drying-rewetting cycles. We suggest that chemical formation of methane during degradation of soil organic matter may represent the missing soil source that is needed to fully understand the methane cycle in aerobic soils. Although the emission fluxes are relatively low when compared to those from wetlands, they may be important in warm and wet regions subjected to ultraviolet radiation. We suggest that this methane source is highly sensitive to global change.

scholarly journals Non-microbial methane formation in oxic soils

2012 ◽  
Vol 9 (9) ◽  
pp. 11961-11987 ◽  
Author(s):  
A. Jugold ◽  
F. Althoff ◽  
M. Hurkuck ◽  
M. Greule ◽  
J. Lelieveld ◽  
...  
Keyword(s):  
Organic Matter ◽  
Large Fraction ◽  
Methane Formation ◽  
Strictly Anaerobic ◽  
Atmospheric Methane ◽  
Methane Cycle ◽  
Alternative Source ◽  
Emission Fluxes ◽  
Methane Fluxes ◽  
Methane Source

Abstract. Methane plays an important role as a radiatively and chemically active gas in our atmosphere. Until recently, sources of atmospheric methane in the biosphere have been attributed to strictly anaerobic microbial processes during degradation of organic matter. However, a large fraction of methane produced in the anoxic soil layers does not reach the atmosphere due to methanotrophic consumption in the overlaying oxic soil. Although methane fluxes from aerobic soils have been observed an alternative source other than methanogenesis has not been identified thus far. Here we provide evidence for non-microbial methane formation in soils under oxic conditions. We found that soils release methane upon heating and other environmental factors like ultraviolet irradiation, and drying-rewetting cycles. We suggest that chemical formation of methane during degradation of soil organic matter may represent the missing soil source that is needed to fully understand the complete methane cycle within the pedosphere. Although the emission fluxes are relatively low when compared to those from wetlands, they may be important in warm and wet regions subjected to ultraviolet radiation. We suggest that this methane source is highly sensitive to global change.

scholarly journals Contribution of oxic methane production to surface methane emission in lakes and its global importance

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Marco Günthel ◽  
Daphne Donis ◽  
Georgiy Kirillin ◽  
Danny Ionescu ◽  
Mina Bizic ◽  
...  
Keyword(s):  
Surface Water ◽  
Methane Emission ◽  
Methane Production ◽  
Surface Mixed Layer ◽  
Atmospheric Methane ◽  
Methane Cycle ◽  
Surface Areas ◽  
Balance Analysis ◽  
Littoral Sediment ◽  
Methane Source

AbstractRecent discovery of oxic methane production in sea and lake waters, as well as wetlands, demands re-thinking of the global methane cycle and re-assessment of the contribution of oxic waters to atmospheric methane emission. Here we analysed system-wide sources and sinks of surface-water methane in a temperate lake. Using a mass balance analysis, we show that internal methane production in well-oxygenated surface water is an important source for surface-water methane during the stratified period. Combining our results and literature reports, oxic methane contribution to emission follows a predictive function of littoral sediment area and surface mixed layer volume. The contribution of oxic methane source(s) is predicted to increase with lake size, accounting for the majority (>50%) of surface methane emission for lakes with surface areas >1 km2.

Soils as sources and sinks for atmospheric methane

1997 ◽  
Vol 77 (2) ◽  
pp. 167-177 ◽  
Author(s):  
Edward Topp ◽  
Elizabeth Pattey
Keyword(s):  
Organic Matter ◽  
Methane Oxidation ◽  
Cultural Practices ◽  
Agricultural Soils ◽  
Flux Measurement ◽  
Methane Emissions ◽  
Spatial And Temporal Variability ◽  
Atmospheric Methane ◽  
Bacterial Populations ◽  
Methane Fluxes

Methane is considered to be a significant greenhouse gas. Methane is produced in soils as the end product of the anaerobic decomposition of organic matter. In the absence of oxygen, methane is very stable, but under aerobic conditions it is mineralized to carbon dioxide by methanotrophic bacteria. Soil methane emissions, primarily from natural wetlands, landfills and rice paddies, are estimated to represent about half of the annual global methane production. Oxidation of atmospheric methane by well-drained soils accounts for about 10% of the global methane sink. Whether a soil is a net source or sink for methane depends on the relative rates of methanogenic and methanotrophic activity. A number of factors including pH, Eh, temperature and moisture content influence methane transforming bacterial populations and soil fluxes. Several techniques are available for measuring methane fluxes. Flux estimation is complicated by spatial and temporal variability. Soil management can impact methane transformations. For example, landfilling of organic matter can result in significant methane emissions, whereas some cultural practices such as nitrogen fertilization inhibit methane oxidation by agricultural soils. Key words: Methane, methanogenesis, methane oxidation, soil, flux measurement

Exploring the variation in ecosystem scale methane fluxes and its drivers within a boreal mire complex

2021 ◽  
Author(s):  
Koffi Dodji Noumonvi ◽  
Joshua L. Ratcliffe ◽  
Mats Öquist ◽  
Mats B. Nilsson ◽  
Matthias Peichl
Keyword(s):  
Eddy Covariance ◽  
Land Surface ◽  
Chemical Properties ◽  
Growing Season ◽  
Small Scale ◽  
Atmospheric Methane ◽  
Flux Footprint ◽  
Growing Season Length ◽  
Methane Fluxes ◽  
Northern Peatlands

<p>Northern peatlands cover a small fraction of the earth’s land surface, and yet they are one of the most important natural sources of atmospheric methane. With climate change causing rising temperatures, changes in water balance and increased growing season length, peatland contribution to atmospheric methane concentration is likely to increase, justifying the increased attention given to northern peatland methane dynamics. Northern peatlands often occur as heterogeneous complexes characterized by hydromorphologically distinct features from < 1 m² to tens of km², with differing physical, hydrological and chemical properties. The more commonly understood small-scale variation between hummocks, lawns and hollows has been well explored using chamber measurements. Single tower eddy covariance measurements, with a typical 95% flux footprint of < 0.5 km², have been used to assess the ecosystem scale methane exchange. However, how representative single tower flux measurements are of an entire mire complex is not well understood. To address this knowledge gap, the present study takes advantage of a network of four eddy covariance towers located less than 3 km apart at four mires within a typical boreal mire complex in northern Sweden. The variation of methane fluxes and its drivers between the four sites will be explored at different temporal scales, i.e. half-hourly, daily and at a growing-season scale.</p>

scholarly journals The Use of Radiocarbon Measurements in Atmospheric Studies

Radiocarbon ◽  
1990 ◽  
Vol 32 (1) ◽  
pp. 37-58 ◽  
Author(s):  
M R Manning ◽  
D C Lowe ◽  
W H Melhuish ◽  
R J Sparks ◽  
Gavin Wallace ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Circulation Model ◽  
Current Data ◽  
Atmospheric Methane ◽  
Global Circulation Model ◽  
Fossil Carbon ◽  
Global Circulation ◽  
Methane Source ◽  
Clean Air ◽  
Source Current

14C measured in trace gases in clean air helps to determine the sources of such gases, their long-range transport in the atmosphere, and their exchange with other carbon cycle reservoirs. In order to separate sources, transport and exchange, it is necessary to interpret measurements using models of these processes. We present atmospheric 14CO2 measurements made in New Zealand since 1954 and at various Pacific Ocean sites for shorter periods. We analyze these for latitudinal and seasonal variation, the latter being consistent with a seasonally varying exchange rate between the stratosphere and troposphere. The observed seasonal cycle does not agree with that predicted by a zonally averaged global circulation model. We discuss recent accelerator mass spectrometry measurements of atmospheric 14CH4 and the problems involved in determining the fossil fuel methane source. Current data imply a fossil carbon contribution of ca 25%, and the major sources of uncertainty in this number are the uncertainty in the nuclear power source of 14CH4, and in the measured value for δ14C in atmospheric methane.

scholarly journals δ 13 C methane source signatures from tropical wetland and rice field emissions

2021 ◽  
Vol 380 (2215) ◽  
Author(s):  
James L. France ◽  
Rebecca E. Fisher ◽  
David Lowry ◽  
Grant Allen ◽  
Marcos F. Andrade ◽  
...  
Keyword(s):  
Rice Field ◽  
Ambient Air ◽  
Atmospheric Methane ◽  
Isotopic Signatures ◽  
Methane Budget ◽  
Significant Seasonal Variation ◽  
Methane Source ◽  
Wetland Extent ◽  
Term Monitoring

The atmospheric methane (CH 4 ) burden is rising sharply, but the causes are still not well understood. One factor of uncertainty is the importance of tropical CH 4 emissions into the global mix. Isotopic signatures of major sources remain poorly constrained, despite their usefulness in constraining the global methane budget. Here, a collection of new δ 13 C CH 4 signatures is presented for a range of tropical wetlands and rice fields determined from air samples collected during campaigns from 2016 to 2020. Long-term monitoring of δ 13 C CH 4 in ambient air has been conducted at the Chacaltaya observatory, Bolivia and Southern Botswana. Both long-term records are dominated by biogenic CH 4 sources, with isotopic signatures expected from wetland sources. From the longer-term Bolivian record, a seasonal isotopic shift is observed corresponding to wetland extent suggesting that there is input of relatively isotopically light CH 4 to the atmosphere during periods of reduced wetland extent. This new data expands the geographical extent and range of measurements of tropical wetland and rice δ 13 C CH 4 sources and hints at significant seasonal variation in tropical wetland δ 13 C CH 4 signatures which may be important to capture in future global and regional models. This article is part of a discussion meeting issue ‘Rising methane: is warming feeding warming? (part 2)’.

scholarly journals No detectable aerobic methane efflux from plant material, nor from adsorption/desorption processes

2008 ◽  
Vol 5 (6) ◽  
pp. 1551-1558 ◽  
Author(s):  
M. U. F. Kirschbaum ◽  
A. Walcroft
Keyword(s):  
Zea Mays ◽  
High Surface ◽  
High Surface Area ◽  
Atmospheric Methane ◽  
Plant Materials ◽  
Methane Fluxes ◽  
Detached Leaves ◽  
Filter Papers ◽  
Adsorption Desorption ◽  
Methane Efflux

Abstract. In early 2006, Keppler et al. (Nature, 439:187–191) reported a novel finding that plant leaves, and even simple organic materials, can release methane under aerobic conditions. We investigated here whether the reported methane release might simply arise from methane desorption from sample surfaces after prior exposure to higher methane concentrations. We exposed standard cellulose filter papers (i.e. organic material with a high surface area) to atmospheric methane concentration and then transferred them to a low-methane atmosphere. Our results suggest that any desorption flux was extremely small (−0.0001±0.0019 ngCH4 kgDW−1 s−1) and would play no quantitatively significant role in modifying any measured methane fluxes. We also incubated fresh detached leaves of several species and intact Zea mays seedlings under aerobic and low-light conditions. After correcting for a small measured methane influx into empty chambers, measured rates of methane emission by plant materials were zero or, at most, very small, ranging from −0.25±1.1 ngCH4 kgDW−1 s−1 for Zea mays seedlings to 0.10±0.08 ngCH4 kgDW−1 s−1 for a mixture of freshly detached grasses. These rates were much smaller than the rates originally reported by Keppler et al. (2006).

scholarly journals Mercury Methylation and Demethylation in Anoxic Lake Sediments and by Strictly Anaerobic Bacteria

1998 ◽  
Vol 64 (3) ◽  
pp. 1013-1017 ◽  
Author(s):  
K.-R. Pak ◽  
R. Bartha
Keyword(s):  
Organic Matter ◽  
Anaerobic Bacteria ◽  
Mercury Methylation ◽  
Strictly Anaerobic ◽  
Anoxic Sediment ◽  
Acetogenic Bacteria ◽  
High Potentials ◽  
High Mercury ◽  
Pure Cultures ◽  
Sediment Ph

ABSTRACT After spiking anoxic sediment slurries of three acidic oligotrophic lakes with either HgCl2 at 1.0 μg/ml or CH3HgI at 0.1 μg/ml, both mercury methylation and demethylation rates were measured. High mercury methylation potentials were accompanied by high demethylation potentials in the same sediment. These high potentials correlated positively with the concentrations of organic matter and dissolved sulfate in the sediment and with mercury levels in fish. Adjustment of the acidic sediment pH to neutrality failed to influence either the methylation or the demethylation rate of mercury. The opposing methylation and demethylation processes converged to establish similar Hg2+-CH3Hg+equilibria in all three sediments. Because of their metabolic dominance in anoxic sediments, mercury methylation and demethylation in pure cultures of sulfidogenic, methanogenic, and acetogenic bacteria were also measured. Sulfidogens both methylated and demethylated mercury, but the methanogen tested only catalyzed demethylation and the acetogen neither methylated nor demethylated mercury.

scholarly journals Methane and Global Environmental Change

2018 ◽  
Vol 43 (1) ◽  
pp. 165-192 ◽  
Author(s):  
Dave S. Reay ◽  
Pete Smith ◽  
Torben R. Christensen ◽  
Rachael H. James ◽  
Harry Clark
Keyword(s):  
Climate Change ◽  
Environmental Change ◽  
Industrial Revolution ◽  
Net Primary Production ◽  
Global Climate ◽  
Global Environmental Change ◽  
Climate Change Policy ◽  
Climate Feedback ◽  
Atmospheric Methane ◽  
Methane Fluxes

Global atmospheric methane concentrations have continued to rise in recent years, having already more than doubled since the Industrial Revolution. Further environmental change, especially climate change, in the twenty-first century has the potential to radically alter global methane fluxes. Importantly, changes in temperature, precipitation, and net primary production may induce positive climate feedback effects in dominant natural methane sources such as wetlands, soils, and aquatic ecosystems. Anthropogenic methane sources may also be impacted, with a risk of enhanced emissions from the energy, agriculture, and waste sectors. Here, we review the global sources of methane, the trends in fluxes by source and sector, and their possible evolution in response to future environmental change. We discuss ongoing uncertainties in flux estimation and projection, and highlight the great potential for multisector methane mitigation as part of wider global climate change policy.

scholarly journals Methane-Producing Microbial Community in a Coal Bed of the Illinois Basin

2008 ◽  
Vol 74 (8) ◽  
pp. 2424-2432 ◽  
Author(s):  
Dariusz Strąpoć ◽  
Flynn W. Picardal ◽  
Courtney Turich ◽  
Irene Schaperdoth ◽  
Jennifer L. Macalady ◽  
...  
Keyword(s):  
Organic Matter ◽  
Microbial Community ◽  
Membrane Lipids ◽  
Phylogenetic Analyses ◽  
Coal Bed ◽  
Coal Bed Methane ◽  
Illinois Basin ◽  
Methane Formation ◽  
Small Subunit Rrna

ABSTRACT A series of molecular and geochemical studies were performed to study microbial, coal bed methane formation in the eastern Illinois Basin. Results suggest that organic matter is biodegraded to simple molecules, such as H2 and CO2, which fuel methanogenesis and the generation of large coal bed methane reserves. Small-subunit rRNA analysis of both the in situ microbial community and highly purified, methanogenic enrichments indicated that Methanocorpusculum is the dominant genus. Additionally, we characterized this methanogenic microorganism using scanning electron microscopy and distribution of intact polar cell membrane lipids. Phylogenetic studies of coal water samples helped us develop a model of methanogenic biodegradation of macromolecular coal and coal-derived oil by a complex microbial community. Based on enrichments, phylogenetic analyses, and calculated free energies at in situ subsurface conditions for relevant metabolisms (H2-utilizing methanogenesis, acetoclastic methanogenesis, and homoacetogenesis), H2-utilizing methanogenesis appears to be the dominant terminal process of biodegradation of coal organic matter at this location.

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