Methane oxidation and pathways of production in a Texas paddy field deduced from measurements of flux, δ<sup>l3</sup>C, and δD of CH<sub>4</sub>

Tyler, S. C.; Bilek, R. S.; Sass, Ronald L.; Fisher, Frank M.

doi:10.1029/97gb01624

Cited by 135 publications

(200 citation statements)

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“…Water resulting from the methane combustion also was collected and frozen into a single glass tube. The measurements of d 13 C-CH 4 and d 2 H-CH 4 were performed in 1997 at the University of California, Irvine, using a Finnigan-MAT 252 isotope ratio mass spectrometer equipped with a tube cracker inlet system (Tyler et al, 1997). The CO 2 samples intended for 13 C analysis were run directly.…”

Section: Oxidation and Mass Spectrometrymentioning

confidence: 99%

Stable carbon and hydrogen isotope measurements on Black Sea water-column methane

Reeburgh

Tyler

Carroll

2006

Deep Sea Research Part II: Topical Studies in Oceanography

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We report measurements of d 13 C-CH 4 and d 2 H-CH 4 at a central station in the Black Sea. We considered the Black Sea as a ''biogeochemical bucket'' and the single station as a basin-wide integrator of processes affecting methane. Considering the rapid (3.6-18 yr) turnover of methane and the similarity of these stable isotope distributions to the methane concentration and oxidation rate profiles [Reeburgh, Ward, Whalen, Sandbeck, Kilpatrick, Kerkhof, 1991. Black Sea methane geochemistry. Deep-Sea Research 38, S1189-S1210], it appears that methane is being added approximately as fast as it is being oxidized. Methane can be thought of as ''running in place'' in the Black Sea water column.Recent reports of extensive vents on the northern side of the Black Sea suggest that they might be a methane source capable of effectively balancing the Black Sea methane budget. Unfortunately, we have limited information on basin-wide seep fluxes and cannot identify them with stable isotope measurements. Methane oxidation (and accompanying isotope fractionation) is so extensive that the water-column stable isotope measurements provide little information on methane sources. Future measurements of 14 C-CH 4 should permit partitioning Black Sea methane sources into fossil and recent components. r

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Section: Oxidation and Mass Spectrometrymentioning

confidence: 99%

Stable carbon and hydrogen isotope measurements on Black Sea water-column methane

Reeburgh

Tyler

Carroll

2006

Deep Sea Research Part II: Topical Studies in Oceanography

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“…Other studies also found more reasonable values for ƒ mc when assuming α mc = 1.07 (Conrad et al, 2002;Fey et al, 2004). It is also notable that most previous studies have reported δ ac values of acetoclastic methanogenesis in the range of -23 ‰ to -46 ‰ (Goevert and Conrad, 2009;Krzycki et al, 1987;Nakagawa et al, 2002;Sugimoto and Wada, 1993;Tyler et al, 1997). Therefore the postulated δ ac values of -23 ‰ to -34 ‰ in this study are in good agreement with the δ ac values of acetoclastic methanogenesis currently reported in the literature.…”

Section: Pathway Contribution In Coal-treated Cultures and A Conceptumentioning

confidence: 79%

Carbon and hydrogen isotope fractionation during methanogenesis: A laboratory study using coal and formation water

Susilawati

Golding

Baublys

et al. 2016

International Journal of Coal Geology

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Carbon and hydrogen isotope compositions of CH 4 generated via methanogenesis in cultures of South Sumatra Basin (SSB) coalbed methane (CBM) formation waters grown on coal, acetate and H 2 +CO 2 were investigated. CH 4 production and molecular analysis confirmed the presence of active microbial communities that are able to convert coal into CH 4 using both acetoclastic and hydrogenotrophic pathways. The representative bacterial sequences were dominated by Bacteroidetes, Firmicutes and Deltaproteobacteria, while Methanosaeta and Methanosarcina were the most prevalent archaeal methanogens present in the cultures.CH 4 produced in this study's culturing experiments has δ 13 C values in the range of -50 ‰ to -20 ‰, with most values falling outside the current understanding of the carbon isotopic boundaries for biogenic CH 4 (-110 ‰ to -30 ‰). However, the corresponding apparent carbon isotopic α factor (α c = 1.02±0.006), and isotopic effect (ε c = -20.1 ‰ ±15.3) showed that CH 4 in SSB cultures was predominantly produced by acetoclastic methanogenesis, which is consistent with the results of molecular DNA analysis. In addition, the calculated contribution of CO 2 reduction from the δ 13 C values of coaltreated cultures was overall < 50 %, further confirming the high contribution of the acetoclastic pathway to CH 4 production in the SSB cultures. The outcome of this experimental study also suggests that δ 2 H-CH 4 values may not provide a reliable basis for distinguishing methanogenic pathways, while apparent carbon isotopic fractionation factor (α c ) and isotope effect (ε c ) are considered more useful indicators of the methanogenic pathway.The high δ 13 C-CH 4 values (>-30 ‰) and the dominance of Methanosaeta over Methanosarcina indicate that methanogens within the SSB cultures were operating at low substrate concentrations. An unusually positive δ 13 C-CH 4 suggests a substrate depletion effect, which is thought to be related to a decrease in the relative abundance of key bacterial coal degraders with formation water inoculum storage time. Closer observation of δ 13 C-CH 4 values during the growth of cultures within a single experiment also showed a 13 C-enrichment trend over time. At log phase of growth, the CH 4 produced was 13 C-depleted when compared to the stationary phase that also indicates substrate depletion effects. Finally, the δ 13 C-CH 4 values encountered in this study (as high as -20 ‰) highlight the possible positive extension of δ 13 C-CH 4 values of acetoclastic methanogenesis from those currently reported in the literature for natural and experimental samples (as high as -30 ‰).Keywords: Biogenic gas, coal, culture experiment, isotopic composition INTRODUCTIONArchaeal methanogens are the only known microorganisms capable of forming CH 4 . These strictly anaerobic microbes are restricted to utilizing simple compounds that contain no more than two carbon atoms. As such, complex organic compounds in anoxic environments (e.g., marine sediments, rice paddies, subsurface shales and coalbeds) ...

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“…These conditions were consistently maintained throughout the sampling period to maintain uniformity in environmental conditions. The fraction of oxidation was determined using in-situ stable isotope tracing technique (Chanton et al, 1997;Tyler et al, 1997). The method makes use of naturally occurring carbon isotope ratios ( 13 C/ 12 C) between above-and below-ground was used in this research.…”

Section: Site Characteristicsmentioning

confidence: 99%

“…In a similar way, just recently, the use of hydrogen isotopes (δD) has been used in trying to understand the biogeochemistry of individual CH 4 sources (Wahlen, 1994;Quay et al, 1999;Rice et al 2009;Tyler et al, 1997). The hydrogen isotopic composition, δD, is calculated in the same way using the D/H ratio for standard mean (0.0001558) for R standard (Gonfiantini et al, 1995).…”

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confidence: 99%

“…Typically, values of α ox have been found to be dependent on both temperature (Coleman et al 1981;King et al, 1989 ) and CH 4 concentrations, with values lying in the range 1.022 to 1.050 for temperatures between 15 o C and 26 o C (Cabral et al, 2010;Tyler et al, 1997;Reeburgh et., 1997). Various models have been developed that relate α ox and soil temperature ( Fig.…”

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Feedbacks of Methane and Nitrous Oxide Emissions from Rice Agriculture

Sithole

2000

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The effect of global warming on methane (CH 4 ) and nitrous oxide (N 2 O) emissions from agriculture was investigated and simulated from a soil warming experiment.Experiments were designed and installed in a temperature controlled greenhouse. The relationships between elevated temperatures and CH 4 and N 2 O emissions were determined and calculated as the Q 10 s of production, emission and oxidation. A study of the populations of methanogens and methanotrophs at a range of soil temperatures was performed based on soil molecular DNA analysis.This study showed that global warming would increase CH 4 emissions from rice agriculture and that the resultant emissions will be potentially large enough to cause changes in the present atmospheric concentrations. This research also showed that this increase was most evident for soil temperatures below 30 o C, above which emissions decreased with increasing temperature. The seasonal average Q 10 s of CH 4 emission, production, oxidation, methanogen and methanotroph populations were found to be 1.7, 2.6 and 2.2, 2.6 and 3.8, respectively, over a temperature of 20-32 o C. Considering that the processes of CH 4 production and emission are similar to those in natural wetlands, which is the largest source of atmospheric CH 4 , the contribution of this feedback is likely to cause a significant increase to the present CH 4 atmospheric budget if the current global warming trend persists over the next century.ii The Q 10 s of N 2 O emissions and production were 0.5-3.3 and 0.4-2.9, respectively. The low Q 10 values found for N 2 O suggest that although global warming will have a direct impact on the production and emission rates. Nevertheless, the magnitude of the impact of global on both CH 4 and N 2 O emissions from agriculture is likely to vary from one region to another due to the spatial variations in agricultural soil temperatures and the likely changes in the global regional distribution of water resources (water tables, rainfall patterns), water management practices and the responses of terrestrial CH 4 and N 2 O sources such as natural wetlands and plants.iii Acknowledgements

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Methane oxidation and pathways of production in a Texas paddy field deduced from measurements of flux, δ^l3C, and δD of CH₄

Cited by 135 publications

References 67 publications

Stable carbon and hydrogen isotope measurements on Black Sea water-column methane

Stable carbon and hydrogen isotope measurements on Black Sea water-column methane

Carbon and hydrogen isotope fractionation during methanogenesis: A laboratory study using coal and formation water

Feedbacks of Methane and Nitrous Oxide Emissions from Rice Agriculture

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Methane oxidation and pathways of production in a Texas paddy field deduced from measurements of flux, δl3C, and δD of CH4

Cited by 135 publications

References 67 publications

Stable carbon and hydrogen isotope measurements on Black Sea water-column methane

Stable carbon and hydrogen isotope measurements on Black Sea water-column methane

Carbon and hydrogen isotope fractionation during methanogenesis: A laboratory study using coal and formation water

Feedbacks of Methane and Nitrous Oxide Emissions from Rice Agriculture

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Product

Resources

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Methane oxidation and pathways of production in a Texas paddy field deduced from measurements of flux, δ^l3C, and δD of CH₄