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Sample records for aerobic methane release

  1. Light-Dependent Aerobic Methane Oxidation Reduces Methane Emissions from Seasonally Stratified Lakes

    PubMed Central

    Oswald, Kirsten; Milucka, Jana; Brand, Andreas; Littmann, Sten; Wehrli, Bernhard; Kuypers, Marcel M. M.; Schubert, Carsten J.

    2015-01-01

    Lakes are a natural source of methane to the atmosphere and contribute significantly to total emissions compared to the oceans. Controls on methane emissions from lake surfaces, particularly biotic processes within anoxic hypolimnia, are only partially understood. Here we investigated biological methane oxidation in the water column of the seasonally stratified Lake Rotsee. A zone of methane oxidation extending from the oxic/anoxic interface into anoxic waters was identified by chemical profiling of oxygen, methane and δ13C of methane. Incubation experiments with 13C-methane yielded highest oxidation rates within the oxycline, and comparable rates were measured in anoxic waters. Despite predominantly anoxic conditions within the zone of methane oxidation, known groups of anaerobic methanotrophic archaea were conspicuously absent. Instead, aerobic gammaproteobacterial methanotrophs were identified as the active methane oxidizers. In addition, continuous oxidation and maximum rates always occurred under light conditions. These findings, along with the detection of chlorophyll a, suggest that aerobic methane oxidation is tightly coupled to light-dependent photosynthetic oxygen production both at the oxycline and in the anoxic bottom layer. It is likely that this interaction between oxygenic phototrophs and aerobic methanotrophs represents a widespread mechanism by which methane is oxidized in lake water, thus diminishing its release into the atmosphere. PMID:26193458

  2. Environmental control on aerobic methane oxidation in coastal waters

    NASA Astrophysics Data System (ADS)

    Steinle, Lea; Maltby, Johanna; Engbersen, Nadine; Zopfi, Jakob; Bange, Hermann; Elvert, Marcus; Hinrichs, Kai-Uwe; Kock, Annette; Lehmann, Moritz; Treude, Tina; Niemann, Helge

    2016-04-01

    Large quantities of methane are produced in anoxic sediments of continental margins and may be liberated to the overlying water column, where some of it is consumed by aerobic methane oxidizing bacteria (MOB). Aerobic methane oxidation (MOx) in the water column is consequently the final sink for methane before its release to the atmosphere, where it acts as a potent greenhouse gas. In the context of the ocean's contribution to atmospheric methane, coastal seas are particularly important accounting >75% of global methane emission from marine systems. Coastal oceans are highly dynamic, in particular with regard to the variability of methane and oxygen concentrations as well as temperature and salinity, all of which are potential key environmental factors controlling MOx. To determine important environmental controls on the activity of MOBs in coastal seas, we conducted a two-year time-series study with measurements of physicochemical water column parameters, MOx activity and the composition of the MOB community in a coastal inlet in the Baltic Sea (Boknis Eck Time Series Station, Eckernförde Bay - E-Bay). In addition, we investigated the influence of temperature and oxygen on MOx during controlled laboratory experiments. In E-Bay, hypoxia developed in bottom waters towards the end of the stratification period. Constant methane liberation from sediments resulted in bottom water methane accumulations and supersaturation (with respect to the atmospheric equilibrium) in surface waters. Here, we will discuss the factors impacting MOx the most, which were (i) perturbations of the water column (ii) temperature and (iii) oxygen concentration. (i) Perturbations of the water column caused by storm events or seasonal mixing led to a decrease in MOx, probably caused by replacement of stagnant water with a high standing stock of MOB by 'new' waters with a lower abundance of methanotrophs. b) An increase in temperature generally led to higher MOx rates. c) Even though methane was

  3. Toxic effects of butyl elastomers on aerobic methane oxidation

    NASA Astrophysics Data System (ADS)

    Niemann, Helge; Steinle, Lea I.; Blees, Jan H.; Krause, Stefan; Bussmann, Ingeborg; Lehmann, Moritz F.; Treude, Tina

    2013-04-01

    Large quantities of the potent greenhouse gas methane are liberated into the water column of marine and lacustrine environments where it may be consumed by aerobic methane oxidising bacteria before reaching the atmosphere.The reliable quantification of aerobic methane oxidation (MOx) rates is consequently of paramount importance for estimating methane budgets and to understand the controls on water column methane cycling. A widely used set of methods for measuring MOx rates is based on the incubation of water samples during which the consumption of methane is monitored, for instance with radio-tracer assays. Typically, incubation vessels are sealed with butyl rubber stoppers because these elastomers are essentially impermeable for gases at the relevant time scales. We tested the effect of different stopper materials (unmodified- and halogenated butyl rubber) on MOx activity in environmental samples and in cultures of methane oxidising bacteria. MOx rates in samples sealed with unmodified butyl rubber were > 75% lower compared to parallel incubations with halogenated butyl rubber seals, suggesting inhibiting/toxic effects associated with the use of unmodified butyl elastomers. To further explore the cause of these effects, we analysed aqueous extracts of the different stoppers. Halogenated butyl rubber stoppers appeared to bleed off comparably little amounts of organics. In stark contrast, extracts of unmodified butyl rubber were contaminated with various organic compounds including potential bactericides such as benzyltoluenes, phenylalkanes and benzuothiazoles. We also found tetramethylthiourea, a scavenger of active oxygen species, which may inhibit the MOx pathway.

  4. Investigating the chemical and isotopic kinetics of aerobic methane oxidation in the Northern US Atlantic Margin, Hudson Canyon

    NASA Astrophysics Data System (ADS)

    Chan, E. W.; Kessler, J. D.; Shiller, A. M.; Redmond, M. C.; Arrington, E. C.; Valentine, D. L.

    2015-12-01

    Recent discoveries of methane seepage along the US Atlantic margin have led to speculation on the fate of the released methane. Here we examine the kinetics of aerobic methane oxidation to gain a fundamental understanding of this methane sink. In order to look at this process in its entirety, a unique mesocosm incubation system was developed with a Dissolved Gas Analyzer System (DGAS) to monitor in real time the chemical and isotopic changes involved with aerobic methane oxidation. This system measures changes in methane, carbon dioxide, and oxygen concentrations as well as the stable carbon isotopes of methane and carbon dioxide with time. In addition samples are strategically removed to characterize trace metals, nutrients, cell counts, and microbial community genetics. This presentation will detail the results obtained from samples collected inside the Hudson Canyon at the edge of the methane clathrate stability zone and outside the Hudson Canyon, not influenced by the methane seepage. These results show that in both environments along the Atlantic margin, methane was consumed aggressively but the timing of consumption varied based on location. In addition, these results are leading to insights into the chemical requirements needed for aerobic methane oxidation and the resulting isotopic fractionation.

  5. Aerobic Methane Oxidation in Alaskan Lakes Along a Latitudinal Transect

    NASA Astrophysics Data System (ADS)

    Martinez-Cruz, K. C.; Sepulveda-Jauregui, A.; Walter Anthony, K. M.; Anthony, P.; Thalasso, F.

    2013-12-01

    Karla Martinez-Cruz* **, Armando Sepulveda-Jauregui*, Katey M. Walter Anthony*, Peter Anthony*, and Frederic Thalasso**. * Water and Environmental Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, Alaska. ** Biotechnology and Bioengineering Department, Cinvestav, Mexico city, D. F., Mexico. Methane (CH4) is the third most important greenhouse gas in the atmosphere, after carbon dioxide and water vapor. Boreal lakes play an important role in the current global warming by contributing as much as 6% of global atmospheric CH4 sources annually. On the other hand, aerobic methane oxidation (methanotrophy) in lake water is a fundamental process in global methane cycling that reduces the amount of CH4 emissions to the atmosphere. Several environmental factors affect aerobic methane oxidation in the water column both directly and indirectly, including concentration of CH4 and O2, temperature and carbon budgets of lakes. We analyzed the potential of aerobic methane oxidation (PMO) rates in incubations of water collected from 30 Alaskan lakes along a north-south transect during winter and summer 2011. Our findings showed an effect of CH4 and O2 concentrations, temperature and yedoma thawing permafrost on PMO activity in the lake water. The highest PMO rates were observed in summer by lakes situated on thawing yedoma permafrost, most of them located in the interior of Alaska. We also estimated that 60-80% of all CH4 produced in Alaskan lakes could be taken up by methanotrophs in the lake water column, showing the significant influence of aerobic methane oxidation of boreal lakes to the global CH4 budget.

  6. Aerobic methane emissions from stinkweed (Thlaspi arvense) capsules

    PubMed Central

    Qaderi, Mirwais M; Reid, David M

    2014-01-01

    Aerobic methane (CH4) emission from plant vegetative parts has been confirmed by many studies. However, the origin of aerobic CH4 from plants and its emission from reproductive parts have not been well documented. We determined the effects of developmental stages (early, mid, late) and incubation conditions (darkness, dim light, bright light) on CH4 emissions from stinkweed (Thlaspi arvense) capsules. We found that CH4 emissions from capsules varied with developmental stage and incubation light. Methane emission was highest for the late harvested capsules and for those incubated under lower (dim) light condition. Our results also showed a significant negative correlation between CH4 emission and capsule moisture content. We conclude that CH4 emissions vary with capsule age and diurnal light environment. PMID:25482797

  7. Environmental Controls on Aerobic Methane Oxidation in Coastal Waters

    NASA Astrophysics Data System (ADS)

    Steinle, L.; Maltby, J.; Engbersen, N.; Zopfi, J.; Bange, H. W.; Elvert, M.; Hinrichs, K. U.; Kock, A.; Lehmann, M. F.; Treude, T.; Niemann, H.

    2015-12-01

    Large quantities of the greenhouse gas CH4 are produced in anoxic sediments of continental margins and may be liberated to the overlying water column, and later into the atmosphere. Indeed, coastal seas account for more than 75% of global oceanic CH4 emissions. Yet, aerobic CH4 oxidizing bacteria (MOB) consume an important part of CH4 in the water column, thus mitigating CH4 release to the atmosphere. Coastal oceans are highly dynamic systems, in particular with regard to the variability of temperature, salinity and oxygen concentrations, all of which are potential key environmental factors controlling MOx. To determine the most important controlling factors, we conducted a two-year time-series study with measurements of CH4, MOx, the composition of the MOB community, and physicochemical water column parameters in a coastal inlet in the Baltic Sea (Eckernförde(E-) Bay, Boknis Eck Time Series Station). In addition, we investigated the influence of temperature and oxygen on MOx during controlled laboratory experiments. In E-Bay, seasonal stratification leads to hypoxia in bottom waters towards the end of the stratification period. Methane is produced year-round in the sediments, resulting in accumulation of methane in bottom waters, and supersaturation (with respect to the atmospheric equilibrium) in surface waters. Here, we will discuss the factors impacting MOx the most, which were a) perturbations of the water column caused by storm events, currents or seasonal mixing, b) temperature and c) oxygen concentration. a) Perturbations of the water column led to a sharp decrease in MOx within hours, probably caused by replacement of 'old' water with a high standing stock of MOB by 'new' waters with a lower abundance of MOB. b) An increase in temperature generally led to higher MOx rates. c) Even though CH4 was abundant at all depths, MOx was highest in bottom waters (1-5 nM/d), which usually contain the lowest O2 concentrations. Lab-based experiments with adjusted O2

  8. Assessing the Efficacy of the Aerobic Methanotrophic Biofilter in Methane Hydrate Environments

    SciTech Connect

    Valentine, David

    2012-09-30

    In October 2008 the University of California at Santa Barbara (UCSB) initiated investigations of water column methane oxidation in methane hydrate environments, through a project funded by the National Energy Technology Laboratory (NETL) entitled: assessing the efficacy of the aerobic methanotrophic biofilter in methane hydrate environments. This Final Report describes the scientific advances and discoveries made under this award as well as the importance of these discoveries in the broader context of the research area. Benthic microbial mats inhabit the sea floor in areas where reduced chemicals such as sulfide reach the more oxidizing water that overlies the sediment. We set out to investigate the role that methanotrophs play in such mats at locations where methane reaches the sea floor along with sulfide. Mats were sampled from several seep environments and multiple sets were grown in-situ at a hydrocarbon seep in the Santa Barbara Basin. Mats grown in-situ were returned to the laboratory and used to perform stable isotope probing experiments in which they were treated with 13C-enriched methane. The microbial community was analyzed, demonstrating that three or more microbial groups became enriched in methane?s carbon: methanotrophs that presumably utilize methane directly, methylotrophs that presumably consume methanol excreted by the methanotrophs, and sulfide oxidizers that presumably consume carbon dioxide released by the methanotrophs and methylotrophs. Methanotrophs reached high relative abundance in mats grown on methane, but other bacterial processes include sulfide oxidation appeared to dominate mats, indicating that methanotrophy is not a dominant process in sustaining these benthic mats, but rather a secondary function modulated by methane availability. Methane that escapes the sediment in the deep ocean typically dissolved into the overlying water where it is available to methanotrophic bacteria. We set out to better understand the efficacy of this

  9. Aerobic methane production in surface waters of the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Finke, N.; Crespo-Medina, M.; Schweers, J.; Joye, S. B.

    2011-12-01

    Near surface water of the global oceans often show elevated methane concentrations compared to the water column below with concentrations in supersaturation in regard to the atmosphere (Lamontagne et al. 1973), resulting in a source of this potent greenhouse gas to the atmosphere. The mechanisms leading to methane supersaturation in surface waters remains unclear. Incubations with Trichodesmium-containing Pacific surface water suggested methylphosphonate as potential methane precursor under phosphate limiting conditions (Karl et al. 2008), whereas in phosphate rich Arctic surface waters, DMSP addition stimulated methane production (Damm et al. 2010). Surface waters of the Gulf of Mexico typically exhibit a methane maximum that is conincident with the deep chlorophyll maximum, below the depths where Trichodesmium is abundant. Addition of methylphosphonate, dimethylsulfoniopropionate (DMSP) or methane thiol (MeSH), the proposed methane precursor in DMSP conversion to methane, to oxic sea water did not affect methane production within the chlorophyll maximum at most stations, whereas methyl phosphonate addition stimulated methane production in the surface water and proposed deep Trichodesmium horizon. Pre-filtration of the water through a 10 μm sieve, which eliminated Trichodesmium, or through a 1.2 μm filter, which eliminated additional cyanobacteria such as Synechococcus, did not reduce methane production. Under dark oxic and dark anoxic conditions, however, methane production was reduced 5 and 7-20 fold, respectively, indicating that anerobic methane production in anoxic microniches is not responsible for the methane production. The reduction of methane production under dark conditions suggests that methane production is, in some yet unrecognized way, linked to phototrophic metabolism. Cyanobacteria are likely not responsible for the observed aerobic methane production in the surface waters of the Gulf of Mexico and while methylphosphonate is a potential

  10. Geographic and seasonal variation of dissolved methane and aerobic methane oxidation in Alaskan lakes

    NASA Astrophysics Data System (ADS)

    Martinez-Cruz, K.; Sepulveda-Jauregui, A.; Anthony, K. Walter; Thalasso, F.

    2015-03-01

    Methanotrophic bacteria play an important role oxidizing a significant fraction of methane (CH4) produced in lakes. Aerobic CH4 oxidation depends on lake CH4 and oxygen (O2) concentrations, temperature, and organic carbon input to lakes, including from thawing permafrost in thermokarst (thaw)-affected lakes. Given the large variability in these environmental factors, CH4 oxidation is expected to be subject to large seasonal and geographic variations, which have been scarcely reported in the literature. In the present study, we measured CH4 oxidation rates in 30 Alaskan lakes along a north-south latitudinal transect during winter and summer with a new field laser spectroscopy method. Additionally, we measured dissolved CH4 and O2 concentrations. We found that in the winter, aerobic CH4 oxidation was mainly controlled by the dissolved O2 concentration, while in the summer it was controlled primarily by the CH4 concentration, which was in deficit compared to dissolved O2. The permafrost environment of the lakes was identified as another key factor. Thermokarst (thaw) lakes formed in yedoma-type permafrost had significantly higher CH4 oxidation rates compared to other thermokarst and non-thermokarst lakes formed in non-yedoma permafrost environments. These results confirm that landscape processes play an important role in lake CH4 cycling.

  11. Molecular characterization of a microbial consortium involved in methane oxidation coupled to denitrification under micro-aerobic conditions

    PubMed Central

    Liu, Jingjing; Sun, Faqian; Wang, Liang; Ju, Xi; Wu, Weixiang; Chen, Yingxu

    2014-01-01

    Methane can be used as an alternative carbon source in biological denitrification because it is nontoxic, widely available and relatively inexpensive. A microbial consortium involved in methane oxidation coupled to denitrification (MOD) was enriched with nitrite and nitrate as electron acceptors under micro-aerobic conditions. The 16S rRNA gene combined with pmoA phylogeny of methanotrophs and nirK phylogeny of denitrifiers were analysed to reveal the dominant microbial populations and functional microorganisms. Real-time quantitative polymerase chain reaction results showed high numbers of methanotrophs and denitrifiers in the enriched consortium. The 16S rRNA gene clone library revealed that Methylococcaceae and Methylophilaceae were the dominant populations in the MOD ecosystem. Phylogenetic analyses of pmoA gene clone libraries indicated that all methanotrophs belonged to Methylococcaceae, a type I methanotroph employing the ribulose monophosphate pathway for methane oxidation. Methylotrophic denitrifiers of the Methylophilaceae that can utilize organic intermediates (i.e. formaldehyde, citrate and acetate) released from the methanotrophs played a vital role in aerobic denitrification. This study is the first report to confirm micro-aerobic denitrification and to make phylogenetic and functional assignments for some members of the microbial assemblages involved in MOD. PMID:24245852

  12. Molecular characterization of a microbial consortium involved in methane oxidation coupled to denitrification under micro-aerobic conditions.

    PubMed

    Liu, Jingjing; Sun, Faqian; Wang, Liang; Ju, Xi; Wu, Weixiang; Chen, Yingxu

    2014-01-01

    Methane can be used as an alternative carbon source in biological denitrification because it is nontoxic, widely available and relatively inexpensive. A microbial consortium involved in methane oxidation coupled to denitrification (MOD) was enriched with nitrite and nitrate as electron acceptors under micro-aerobic conditions. The 16S rRNA gene combined with pmoA phylogeny of methanotrophs and nirK phylogeny of denitrifiers were analysed to reveal the dominant microbial populations and functional microorganisms. Real-time quantitative polymerase chain reaction results showed high numbers of methanotrophs and denitrifiers in the enriched consortium. The 16S rRNA gene clone library revealed that Methylococcaceae and Methylophilaceae were the dominant populations in the MOD ecosystem. Phylogenetic analyses of pmoA gene clone libraries indicated that all methanotrophs belonged to Methylococcaceae, a type I methanotroph employing the ribulose monophosphate pathway for methane oxidation. Methylotrophic denitrifiers of the Methylophilaceae that can utilize organic intermediates (i.e. formaldehyde, citrate and acetate) released from the methanotrophs played a vital role in aerobic denitrification. This study is the first report to confirm micro-aerobic denitrification and to make phylogenetic and functional assignments for some members of the microbial assemblages involved in MOD.

  13. Evaluation of Heat Induced Methane Release from Methane Hydrates

    NASA Astrophysics Data System (ADS)

    Leeman, J.; Elwood-Madden, M.; Phelps, T. J.; Rawn, C. J.

    2010-12-01

    Clathrates, or gas hydrates, structurally are guest gas molecules populating a cavity in a cage of water molecules. Gas hydrates naturally occur on Earth under low temperature and moderate pressure environments including continental shelf, deep ocean, and permafrost sediments. Large quantities of methane are trapped in hydrates, providing significant near-surface reserves of carbon and energy. Thermodynamics predicts that hydrate deposits may be destabilized by reducing the pressure in the system or raising the temperature. However, the rate of methane release due to varying environmental conditions remains relatively unconstrained and complicated by natural feedback effects of clathrate dissociation. In this study, hydrate dissociation in sediment due to localized increases in temperature was monitored and observed at the mesoscale (>20L) in a laboratory environment. Experiments were conducted in the Seafloor Process Simulator (SPS) at Oak Ridge National Laboratory (ORNL) to simulate heat induced dissociation. The SPS, containing a column of Ottawa sand saturated with water containing 25mg/L Sno-Max to aid nucleation, was pressurized and cooled well into the hydrate stability field. A fiber optic distributed sensing system (DSS) was embedded at four depths in the sediment column. This allowed the temperature strain value (a proxy for temperature) of the system to be measured with high spatial resolution to monitor the clathrate formation/dissociation processes. A heat exchanger embedded in the sediment was heated using hot recirculated ethylene glycol and the temperature drop across the exchanger was measured. These experiments indicate a significant and sustained amount of heat is required to release methane gas from hydrate-bearing sediments. Heat was consumed by hydrate dissociated in a growing sphere around the heat exchanger until steady state was reached. At steady state all heat energy entering the system was consumed in maintaining the temperature profile

  14. High resolution and comprehensive techniques to analyze aerobic methane oxidation in mesocosm experiments

    NASA Astrophysics Data System (ADS)

    Chan, E. W.; Kessler, J. D.; Redmond, M. C.; Shiller, A. M.; Arrington, E. C.; Valentine, D. L.; Colombo, F.

    2015-12-01

    Many studies of microbially mediated aerobic methane oxidation in oceanic environments have examined the many different factors that control the rates of oxidation. However, there is debate on how quickly methane is oxidized once a microbial population is established and what factor(s) are limiting in these types of environments. These factors include the availability of CH4, O2, trace metals, nutrients, and the density of cell population. Limits to these factors can also control the temporal aspects of a methane oxidation event. In order to look at this process in its entirety and with higher temporal resolution, a mesocosm incubation system was developed with a Dissolved Gas Analyzer System (DGAS) coupled with a set of analytical tools to monitor aerobic methane oxidation in real time. With the addition of newer laser spectroscopy techniques (cavity ringdown spectroscopy), stable isotope fractionation caused by microbial processes can also be examined on a real time and automated basis. Cell counting, trace metal, nutrient, and DNA community analyses have also been carried out in conjunction with these mesocosm samples to provide a clear understanding of the biology in methane oxidation dynamics. This poster will detail the techniques involved to provide insights into the chemical and isotopic kinetics controlling aerobic methane oxidation. Proof of concept applications will be presented from seep sites in the Hudson Canyon and the Sleeping Dragon seep field, Mississippi Canyon 118 (MC 118). This system was used to conduct mesocosm experiments to examine methane consumption, O2 consumption, nutrient consumption, and biomass production.

  15. Geographic and seasonal variation of dissolved methane and aerobic methane oxidation in Alaskan lakes

    NASA Astrophysics Data System (ADS)

    Martinez-Cruz, K.; Sepulveda-Jauregui, A.; Anthony, K. Walter; Thalasso, F.

    2015-08-01

    Methanotrophic bacteria play an important role oxidizing a significant fraction of methane (CH4) produced in lakes. Aerobic CH4 oxidation depends mainly on lake CH4 and oxygen (O2) concentrations, in such a manner that higher MO rates are usually found at the oxic/anoxic interface, where both molecules are present. MO also depends on temperature, and via methanogenesis, on organic carbon input to lakes, including from thawing permafrost in thermokarst (thaw)-affected lakes. Given the large variability in these environmental factors, CH4 oxidation is expected to be subject to large seasonal and geographic variations, which have been scarcely reported in the literature. In the present study, we measured CH4 oxidation rates in 30 Alaskan lakes along a north-south latitudinal transect during winter and summer with a new field laser spectroscopy method. Additionally, we measured dissolved CH4 and O2 concentrations. We found that in the winter, aerobic CH4 oxidation was mainly controlled by the dissolved O2 concentration, while in the summer it was controlled primarily by the CH4 concentration, which was scarce compared to dissolved O2. The permafrost environment of the lakes was identified as another key factor. Thermokarst (thaw) lakes formed in yedoma-type permafrost had significantly higher CH4 oxidation rates compared to other thermokarst and non-thermokarst lakes formed in non-yedoma permafrost environments. As thermokarst lakes formed in yedoma-type permafrost have been identified to receive large quantities of terrestrial organic carbon from thaw and subsidence of the surrounding landscape into the lake, confirming the strong coupling between terrestrial and aquatic habitats and its influence on CH4 cycling.

  16. Dissimilatory perchlorate reduction linked to aerobic methane oxidation via chlorite dismutase

    NASA Astrophysics Data System (ADS)

    Oremland, R. S.; Baesman, S. M.; Miller, L. G.

    2013-12-01

    accumulation of chloride ions either in spent media or in slurries prepared from Searsville Lake soil, neither of these oxyanions evoked methane oxidation when added to either anaerobic mixed cultures or soils enriched in methanotrophs. This result leads us to surmise that the release of O2 during enzymatic perchlorate reduction was low, and that the oxygen produced was unavailable to the aerobic methanotrophs. This was borne out by patterns of O2 and CO2 production during experiments with lake soil, growth media, and pure cultures of dissimilatory perchlorate reducing bacteria. We observed that O2 release during incubation of D. agitata CKB with 10 mM ClO4- or ClO3- was decoupled from metabolism. More O2 was released during incubations without added acetate than with 10 mM acetate and an even greater amount of O2 was released during incubation with heat-killed cells. This suggests a chemical mechanism of O2 production during reaction with ClO4- and ClO3-. Hence, perchlorate reducing bacteria need not be present to facilitate O2 release from the surface of Mars, in support of recent interpretations of Viking LR and GEx experiments.

  17. Aerobic and anaerobic methane oxidation in terrestrial mud volcanoes in the Northern Apennines

    NASA Astrophysics Data System (ADS)

    Wrede, C.; Brady, S.; Rockstroh, S.; Dreier, A.; Kokoschka, S.; Heinzelmann, S. M.; Heller, C.; Reitner, J.; Taviani, M.; Daniel, R.; Hoppert, M.

    2012-07-01

    Methane oxidizing prokaryotes are ubiquitous in oxic and anoxic habitats wherever C1-compounds are present. Thus, methane saturated mud volcano fluids should be a preferred habitat of methane consuming prokaryotes, using the readily available electron donors. In order to understand the relevance of methane as a carbon and energy source in mud volcano communities, we investigate the diversity of prokaryotic organisms involved in oxidation of methane in fluid samples from the Salse di Nirano mud volcano field situated in the Northern Apennines. Cell counts were at approximately 0.7 × 106 microbial cells/ml. A fraction of the microbial biomass was identified as ANME (anaerobic methanotroph) archaea by fluorescence in situ hybridization (FISH) analysis. They are associated in densely colonized flakes, of some tens of μm in diameter, embedded in a hyaline matrix. Diversity analysis based on the 16S rDNA genes, retrieved from amplified and cloned environmental DNA, revealed a high proportion of archaea, involved in anaerobic oxidation of methane (AOM). Aerobic methane-oxidizing proteobacteria could be highly enriched from mud volcano fluids, indicating the presence of aerobic methanotrophic bacteria, which may contribute to methane oxidation, whenever oxygen is readily available. The results imply that biofilms, dominated by ANME archaea, colonize parts of the mud volcano venting system.

  18. A genomic view of methane oxidation by aerobic bacteria and anaerobic archaea

    PubMed Central

    Chistoserdova, Ludmila; Vorholt, Julia A; Lidstrom, Mary E

    2005-01-01

    Recent sequencing of the genome and proteomic analysis of a model aerobic methanotrophic bacterium, Methylococcus capsulatus (Bath) has revealed a highly versatile metabolic potential. In parallel, environmental genomics has provided glimpses into anaerobic methane oxidation by certain archaea, further supporting the hypothesis of reverse methanogenesis. PMID:15693955

  19. Fractionation of the methane isotopologues 13CH4, 12CH3D, and 13CH3D during aerobic oxidation of methane by Methylococcus capsulatus (Bath)

    NASA Astrophysics Data System (ADS)

    Wang, David T.; Welander, Paula V.; Ono, Shuhei

    2016-11-01

    Aerobic oxidation of methane plays a major role in reducing the amount of methane emitted to the atmosphere from freshwater and marine settings. We cultured an aerobic methanotroph, Methylococcus capsulatus (Bath) at 30 and 37 °C, and determined the relative abundance of 12CH4, 13CH4, 12CH3D, and 13CH3D (a doubly-substituted, or "clumped" isotopologue of methane) to characterize the clumped isotopologue effect associated with aerobic methane oxidation. In batch culture, the residual methane became enriched in 13C and D relative to starting methane, with D/H fractionation a factor of 9.14 (Dε/13ε) larger than that of 13C/12C. As oxidation progressed, the Δ13CH3D value (a measure of the excess in abundance of 13CH3D relative to a random distribution of isotopes among isotopologues) of residual methane decreased. The isotopologue fractionation factor for 13CH3D/12CH4 was found to closely approximate the product of the measured fractionation factors for 13CH4/12CH4 and 12CH3D/12CH4 (i.e., 13C/12C and D/H). The results give insight into enzymatic reversibility in the aerobic methane oxidation pathway. Based on the experimental data, a mathematical model was developed to predict isotopologue signatures expected for methane in the environment that has been partially-oxidized by aerobic methanotrophy. Measurement of methane clumped isotopologue abundances can be used to distinguish between aerobic methane oxidation and alternative methane-cycling processes.

  20. Strong release of methane on Mars in northern summer 2003.

    PubMed

    Mumma, Michael J; Villanueva, Geronimo L; Novak, Robert E; Hewagama, Tilak; Bonev, Boncho P; Disanti, Michael A; Mandell, Avi M; Smith, Michael D

    2009-02-20

    Living systems produce more than 90% of Earth's atmospheric methane; the balance is of geochemical origin. On Mars, methane could be a signature of either origin. Using high-dispersion infrared spectrometers at three ground-based telescopes, we measured methane and water vapor simultaneously on Mars over several longitude intervals in northern early and late summer in 2003 and near the vernal equinox in 2006. When present, methane occurred in extended plumes, and the maxima of latitudinal profiles imply that the methane was released from discrete regions. In northern midsummer, the principal plume contained approximately 19,000 metric tons of methane, and the estimated source strength (>/=0.6 kilogram per second) was comparable to that of the massive hydrocarbon seep at Coal Oil Point in Santa Barbara, California. PMID:19150811

  1. Effects of exogenous aerobic bacteria on methane production and biodegradation of municipal solid waste in bioreactors.

    PubMed

    Ge, Sai; Liu, Lei; Xue, Qiang; Yuan, Zhiming

    2016-09-01

    Landfill is the most common and efficient ways of municipal solid waste (MSW) disposal and the landfill biogas, mostly methane, is currently utilized to generate electricity and heat. The aim of this work is to study the effects and the role of exogenous aerobic bacteria mixture (EABM) on methane production and biodegradation of MSW in bioreactors. The results showed that the addition of EABM could effectively enhance hydrolysis and acidogenesis processes of MSW degradation, resulting in 63.95% reduction of volatile solid (VS), the highest methane production rate (89.83Lkg(-1) organic matter) ever recorded and a threefold increase in accumulative methane production (362.9L) than the control (127.1L). In addition, it is demonstrated that white-rot fungi (WRF) might further promote the methane production through highly decomposing lignin, but the lower pH value in leachate and longer acidogenesis duration may cause methane production reduced. The data demonstrated that methane production and biodegradation of MSW in bioreactors could be significantly enhanced by EABM via enhanced hydrolysis and acidogenesis processes, and the results are of great economic importance for the future design and management of landfill. PMID:26601890

  2. Effects of exogenous aerobic bacteria on methane production and biodegradation of municipal solid waste in bioreactors.

    PubMed

    Ge, Sai; Liu, Lei; Xue, Qiang; Yuan, Zhiming

    2016-09-01

    Landfill is the most common and efficient ways of municipal solid waste (MSW) disposal and the landfill biogas, mostly methane, is currently utilized to generate electricity and heat. The aim of this work is to study the effects and the role of exogenous aerobic bacteria mixture (EABM) on methane production and biodegradation of MSW in bioreactors. The results showed that the addition of EABM could effectively enhance hydrolysis and acidogenesis processes of MSW degradation, resulting in 63.95% reduction of volatile solid (VS), the highest methane production rate (89.83Lkg(-1) organic matter) ever recorded and a threefold increase in accumulative methane production (362.9L) than the control (127.1L). In addition, it is demonstrated that white-rot fungi (WRF) might further promote the methane production through highly decomposing lignin, but the lower pH value in leachate and longer acidogenesis duration may cause methane production reduced. The data demonstrated that methane production and biodegradation of MSW in bioreactors could be significantly enhanced by EABM via enhanced hydrolysis and acidogenesis processes, and the results are of great economic importance for the future design and management of landfill.

  3. Field assessment of semi-aerobic condition and the methane correction factor for the semi-aerobic landfills provided by IPCC guidelines

    SciTech Connect

    Jeong, Sangjae; Nam, Anwoo; Yi, Seung-Muk; Kim, Jae Young

    2015-02-15

    Highlights: • CH{sub 4}/CO{sub 2} and CH{sub 4} + CO{sub 2}% are proposed as indices to evaluate semi-aerobic landfills. • A landfill which CH{sub 4}/CO{sub 2} > 1.0 is difficult to be categorized as semi-aerobic landfill. • Field conditions should be carefully investigated to determine landfill types. • The MCF default value for semi-aerobic landfills underestimates the methane emissions. - Abstract: According to IPCC guidelines, a semi-aerobic landfill site produces one-half of the amount of CH{sub 4} produced by an equally-sized anaerobic landfill site. Therefore categorizing the landfill type is important on greenhouse gas inventories. In order to assess semi-aerobic condition in the sites and the MCF value for semi-aerobic landfill, landfill gas has been measured from vent pipes in five semi-aerobically designed landfills in South Korea. All of the five sites satisfied requirements of semi-aerobic landfills in 2006 IPCC guidelines. However, the ends of leachate collection pipes which are main entrance of air in the semi-aerobic landfill were closed in all five sites. The CH{sub 4}/CO{sub 2} ratio in landfill gas, indicator of aerobic and anaerobic decomposition, ranged from 1.08 to 1.46 which is higher than the values (0.3–1.0) reported for semi-aerobic landfill sites and is rather close to those (1.0–2.0) for anaerobic landfill sites. The low CH{sub 4} + CO{sub 2}% in landfill gas implied air intrusion into the landfill. However, there was no evidence that air intrusion has caused by semi-aerobic design and operation. Therefore, the landfills investigated in this study are difficult to be classified as semi-aerobic landfills. Also MCF of 0.5 may significantly underestimate methane emissions compared to other researches. According to the carbon mass balance analyses, the higher MCF needs to be proposed for semi-aerobic landfills. Consequently, methane emission estimate should be based on field evaluation for the semi-aerobically designed landfills.

  4. Evaluation of methyl fluoride and dimethyl ether as inhibitors of aerobic methane oxidation

    USGS Publications Warehouse

    Oremland, R.S.; Culbertson, C.W.

    1992-01-01

    Methyl fluoride (MF) and dimethyl ether (DME) were effective inhibitors of aerobic methanotrophy in a variety of soils. MF and DME blocked consumption of CH4 as well as the oxidation of 14CH4 to 14CO2, but neither MF nor DME affected the oxidation of [14C]methanol or [14C]formate to 14CO2. Cooxidation of ethane and propane by methane-oxidizing soils was also inhibited by MF. Nitrification (ammonia oxidation) in soils was inhibited by both MF and DME. Production of N2O via nitrification was inhibited by MF; however, MF did not affect N2O production associated with denitrification. Methanogenesis was partially inhibited by MF but not by DME. Methane oxidation was ~100-fold more sensitive to MF than was methanogenesis, indicating that an optimum concentration could be employed to selectively block methanotrophy. MF inhibited methane oxidation by cell suspensions of Methylococcus capsulatus; however, DME was a much less effective inhibitor.

  5. Aerobic methane oxidation in a coastal environment with seasonal hypoxia - a time series study

    NASA Astrophysics Data System (ADS)

    Steinle, Lea; Bethke, Christina; Schweers, Johanna; Bange, Hermann; Kock, Annette; Lehmann, Moritz F.; Treude, Tina; Niemann, Helge

    2014-05-01

    In the coastal ocean, methane is generally produced in anoxic sediments from where it can migrate through the water column to the atmosphere. A significant amount of methane is consumed along this passage by a series of microbial filter systems. Over the last 15 years, researchers focused on the first filter in marine sediments, the anaerobic oxidation of methane (AOM). Comparably little is known about the second filter, the aerobic methane oxidation (MOx), which is mediated by bacteria and takes place in the oxic water column. MOx is particularly important in shallow coastal environments that account for more than 75 % of the global oceanic methane emissions. Key environmental factors possibly controlling MOx in these systems are subjected to strong temporal variations since coastal regions are highly dynamic systems. We will present results from a time-series study on methane cycling in the water column of a coastal inlet in the southwestern Baltic Sea (Eckernförde Bay, Boknis Eck Time Series Station, 54°31.823 N, 10°02.764 E, 28m water depth; www.bokniseck.de). Results from monthly samplings for the last 8 years revealed year-round methane seepage from the seafloor and methane supersaturation (with respect to the atmospheric equilibrium) of surface waters. Seasonal stratification during the summer months leads to intermittent oxygen depletion (hypoxic to anoxic) in bottom waters in late summer to early fall. The frequency of these low-oxygen events increased over the last 20 years. In addition to oxygen fluctuations, bottom water salinity can vary strongly (17-24 psu) due to regular inflows of salty North Sea water through the Kattegat. Over the course of one and a half years, we investigated MOx rates, the methanotrophic community, methane concentrations and physicochemical parameters of the water column on a quarterly basis. Albeit methane concentrations were high throughout the water column (20-120 nM), methane turnover showed a clear spatial pattern. That

  6. Modeling of methane release from intact coal

    SciTech Connect

    Odintsev, V.N.

    2005-09-15

    Development of percolating clusters when loading samples of a geomaterial that is hierarchically and stochastically heterogeneous is modeled. The conditions are analyzed for propagation of crack under pressure of methane in the transition phase from a bound state into a free one on the faces of the growing crack in coal.

  7. Isotopic composition of methane released from wetlands: Implications for the increase in atmospheric methane

    SciTech Connect

    Quay, P.D.; King, S.L.; Lansdown, J.M.; Wilbur, D.O. )

    1988-12-01

    Measurements of the delta-C{sup 13} of methane released from tropical, temperate, and arctic wetland sites are reported. The mean delta C{sup 13} values (relative to PDB carbonate standard) for peat bogs and Alaskan tundra are {minus}53 + or{minus}8, {minus}66 + or{minus}5 and {minus}64 + or{minus}5{per thousand}, respectively. These measurements combined with methane flux estimates yield a flux-weighted global average delta-C{sup 13} value of {minus}59 + or{minus}6{per thousand} for methane released from wetlands, a major natural methane source. The agreement between the measured delta-C{sup 13} for methane emitted from wetlands and the calculated steady state value of approximately {minus}6{per thousand} for the delta-C{sup 13} of preindustrial methane sources suggests that methane was predominantly produced biogenically in the preindustrial era. The industrial era time rate of change of the delta-C{sup 13} of the global methane flux is calculated from estimates of the growth rate of the major anthropogenically derived methane sources and the C{sup 13} composition of these sources, and compared to the measured change in the delta-C{sup 13} of methane during the last 300 years. Based on these results, it is estimated that 13 + or{minus}8% of the current global methane flux is derived abiogenically from natural gas and biomass burning, whereas the remainder is derived biogenically primarily from wetlands, rice paddies, and livestock. 40 refs., 5 figs., 2 tabs.

  8. The effect of widespread early aerobic marine ecosystems on methane cycling and the Great Oxidation

    NASA Astrophysics Data System (ADS)

    Daines, Stuart J.; Lenton, Timothy M.

    2016-01-01

    The balance of evidence suggests that oxygenic photosynthesis had evolved by 3.0-2.7 Ga, several hundred million years prior to the Great Oxidation ≈2.4 Ga. Previous work has shown that if oxygenic photosynthesis spread globally prior to the Great Oxidation, this could have supported widespread aerobic ecosystems in the surface ocean, without oxidising the atmosphere. Here we use a suite of models to explore the implications for carbon cycling and the Great Oxidation. We find that recycling of oxygen and carbon within early aerobic marine ecosystems would have restricted the balanced fluxes of methane and oxygen escaping from the ocean, lowering the atmospheric concentration of methane in the Great Oxidation transition and its aftermath. This in turn would have minimised any bi-stability of atmospheric oxygen, by weakening a stabilising feedback on oxygen from hydrogen escape to space. The result would have been a more reversible and probably episodic rise of oxygen at the Great Oxidation transition, consistent with existing geochemical evidence. The resulting drop in methane levels to ≈10 ppm is consistent with climate cooling at the time but adds to the puzzle of what kept the rest of the Proterozoic warm. A key test of the scenario of abundant methanotrophy in oxygen oases before the Great Oxidation is its predicted effects on the organic carbon isotope (δ13Corg) record. Our open ocean general circulation model predicts δC13org ≈ - 30 to -45‰ consistent with most data from 2.65 to 2.45 Ga. However, values of δC13org ≈ - 50 ‰ require an extreme scenario such as concentrated methanotroph production where shelf-slope upwelling of methane-rich water met oxic shelf water.

  9. Astronomical pacing of methane release in the Early Jurassic period.

    PubMed

    Kemp, David B; Coe, Angela L; Cohen, Anthony S; Schwark, Lorenz

    2005-09-15

    A pronounced negative carbon-isotope (delta13C) excursion of approximately 5-7 per thousand (refs 1-7) indicates the occurrence of a significant perturbation to the global carbon cycle during the Early Jurassic period (early Toarcian age, approximately 183 million years ago). The rapid release of 12C-enriched biogenic methane as a result of continental-shelf methane hydrate dissociation has been put forward as a possible explanation for this observation. Here we report high-resolution organic carbon-isotope data from well-preserved mudrocks in Yorkshire, UK, which demonstrate that the carbon-isotope excursion occurred in three abrupt stages, each showing a shift of -2 per thousand to -3 per thousand. Spectral analysis of these carbon-isotope measurements and of high-resolution carbonate abundance data reveals a regular cyclicity. We interpret these results as providing strong evidence that methane release proceeded in three rapid pulses and that these pulses were controlled by astronomically forced changes in climate, superimposed upon longer-term global warming. We also find that the first two pulses of methane release each coincided with the extinction of a large proportion of marine species. PMID:16163353

  10. Astronomical pacing of methane release in the Early Jurassic period.

    PubMed

    Kemp, David B; Coe, Angela L; Cohen, Anthony S; Schwark, Lorenz

    2005-09-15

    A pronounced negative carbon-isotope (delta13C) excursion of approximately 5-7 per thousand (refs 1-7) indicates the occurrence of a significant perturbation to the global carbon cycle during the Early Jurassic period (early Toarcian age, approximately 183 million years ago). The rapid release of 12C-enriched biogenic methane as a result of continental-shelf methane hydrate dissociation has been put forward as a possible explanation for this observation. Here we report high-resolution organic carbon-isotope data from well-preserved mudrocks in Yorkshire, UK, which demonstrate that the carbon-isotope excursion occurred in three abrupt stages, each showing a shift of -2 per thousand to -3 per thousand. Spectral analysis of these carbon-isotope measurements and of high-resolution carbonate abundance data reveals a regular cyclicity. We interpret these results as providing strong evidence that methane release proceeded in three rapid pulses and that these pulses were controlled by astronomically forced changes in climate, superimposed upon longer-term global warming. We also find that the first two pulses of methane release each coincided with the extinction of a large proportion of marine species.

  11. Diversity and abundance of aerobic and anaerobic methane oxidizers at the Haakon Mosby Mud Volcano, Barents Sea.

    PubMed

    Lösekann, Tina; Knittel, Katrin; Nadalig, Thierry; Fuchs, Bernhard; Niemann, Helge; Boetius, Antje; Amann, Rudolf

    2007-05-01

    Submarine mud volcanoes are formed by expulsions of mud, fluids, and gases from deeply buried subsurface sources. They are highly reduced benthic habitats and often associated with intensive methane seepage. In this study, the microbial diversity and community structure in methane-rich sediments of the Haakon Mosby Mud Volcano (HMMV) were investigated by comparative sequence analysis of 16S rRNA genes and fluorescence in situ hybridization. In the active volcano center, which has a diameter of about 500 m, the main methane-consuming process was bacterial aerobic oxidation. In this zone, aerobic methanotrophs belonging to three bacterial clades closely affiliated with Methylobacter and Methylophaga species accounted for 56%+/-8% of total cells. In sediments below Beggiatoa mats encircling the center of the HMMV, methanotrophic archaea of the ANME-3 clade dominated the zone of anaerobic methane oxidation. ANME-3 archaea form cell aggregates mostly associated with sulfate-reducing bacteria of the Desulfobulbus (DBB) branch. These ANME-3/DBB aggregates were highly abundant and accounted for up to 94%+/-2% of total microbial biomass at 2 to 3 cm below the surface. ANME-3/DBB aggregates could be further enriched by flow cytometry to identify their phylogenetic relationships. At the outer rim of the mud volcano, the seafloor was colonized by tubeworms (Siboglinidae, formerly known as Pogonophora). Here, both aerobic and anaerobic methane oxidizers were found, however, in lower abundances. The level of microbial diversity at this site was higher than that at the central and Beggiatoa species-covered part of the HMMV. Analysis of methyl-coenzyme M-reductase alpha subunit (mcrA) genes showed a strong dominance of a novel lineage, mcrA group f, which could be assigned to ANME-3 archaea. Our results further support the hypothesis of Niemann et al. (54), that high methane availability and different fluid flow regimens at the HMMV provide distinct niches for aerobic and

  12. Diversity and Abundance of Aerobic and Anaerobic Methane Oxidizers at the Haakon Mosby Mud Volcano, Barents Sea▿

    PubMed Central

    Lösekann, Tina; Knittel, Katrin; Nadalig, Thierry; Fuchs, Bernhard; Niemann, Helge; Boetius, Antje; Amann, Rudolf

    2007-01-01

    Submarine mud volcanoes are formed by expulsions of mud, fluids, and gases from deeply buried subsurface sources. They are highly reduced benthic habitats and often associated with intensive methane seepage. In this study, the microbial diversity and community structure in methane-rich sediments of the Haakon Mosby Mud Volcano (HMMV) were investigated by comparative sequence analysis of 16S rRNA genes and fluorescence in situ hybridization. In the active volcano center, which has a diameter of about 500 m, the main methane-consuming process was bacterial aerobic oxidation. In this zone, aerobic methanotrophs belonging to three bacterial clades closely affiliated with Methylobacter and Methylophaga species accounted for 56% ± 8% of total cells. In sediments below Beggiatoa mats encircling the center of the HMMV, methanotrophic archaea of the ANME-3 clade dominated the zone of anaerobic methane oxidation. ANME-3 archaea form cell aggregates mostly associated with sulfate-reducing bacteria of the Desulfobulbus (DBB) branch. These ANME-3/DBB aggregates were highly abundant and accounted for up to 94% ± 2% of total microbial biomass at 2 to 3 cm below the surface. ANME-3/DBB aggregates could be further enriched by flow cytometry to identify their phylogenetic relationships. At the outer rim of the mud volcano, the seafloor was colonized by tubeworms (Siboglinidae, formerly known as Pogonophora). Here, both aerobic and anaerobic methane oxidizers were found, however, in lower abundances. The level of microbial diversity at this site was higher than that at the central and Beggiatoa species-covered part of the HMMV. Analysis of methyl-coenzyme M-reductase alpha subunit (mcrA) genes showed a strong dominance of a novel lineage, mcrA group f, which could be assigned to ANME-3 archaea. Our results further support the hypothesis of Niemann et al. (54), that high methane availability and different fluid flow regimens at the HMMV provide distinct niches for aerobic and

  13. Palaeoceanography: methane release in the Early Jurassic period.

    PubMed

    Wignall, Paul B; McArthur, John M; Little, Crispin T S; Hallam, Anthony

    2006-06-01

    Dramatic global warming, triggered by release of methane from clathrates, has been postulated to have occurred during the early Toarcian age in the Early Jurassic period. Kemp et al. claim that this methane was released at three points, as recorded by three sharp excursions of delta13C(org) of up to 3 per thousand magnitude. But they discount another explanation for the excursions: namely that some, perhaps all, of the rapid excursions could be a local signature of a euxinic basin caused by recycling of isotopically light carbon from the lower water column. This idea has been proposed previously (see ref. 3, for example) and is supported by the lack evidence for negative delta13C excursions in coeval belemnite rostra. Kemp et al. dismiss this alternative, claiming that each abrupt shift would have required the recycling of about double the amount of organic carbon that is currently present in the modern ocean; however, their measurements are not from an ocean but from a restricted, epicontinental seaway and so would not require whole-ocean mixing to achieve the excursions. PMID:16738612

  14. Palaeoceanography: methane release in the Early Jurassic period.

    PubMed

    Wignall, Paul B; McArthur, John M; Little, Crispin T S; Hallam, Anthony

    2006-06-01

    Dramatic global warming, triggered by release of methane from clathrates, has been postulated to have occurred during the early Toarcian age in the Early Jurassic period. Kemp et al. claim that this methane was released at three points, as recorded by three sharp excursions of delta13C(org) of up to 3 per thousand magnitude. But they discount another explanation for the excursions: namely that some, perhaps all, of the rapid excursions could be a local signature of a euxinic basin caused by recycling of isotopically light carbon from the lower water column. This idea has been proposed previously (see ref. 3, for example) and is supported by the lack evidence for negative delta13C excursions in coeval belemnite rostra. Kemp et al. dismiss this alternative, claiming that each abrupt shift would have required the recycling of about double the amount of organic carbon that is currently present in the modern ocean; however, their measurements are not from an ocean but from a restricted, epicontinental seaway and so would not require whole-ocean mixing to achieve the excursions.

  15. Improvement of methane generation capacity by aerobic pre-treatment of organic waste with a cellulolytic Trichoderma viride culture.

    PubMed

    Wagner, Andreas Otto; Schwarzenauer, Thomas; Illmer, Paul

    2013-11-15

    Trichoderma viride is known as a potent cellulose decomposer and was successfully used to improve and accelerate the decomposition process of aerobic composting. In contrast, the role of fungi as pre-treatment organisms for anaerobic digestion is not clear, since the fast aerobic decomposition is thought to be responsible for a rapid depletion of easily available nutrients, leading to a lack of these for the anaerobic community. In the present study carried out in lab-scale, the application of T. viride for the aerobic pre-incubation of organic matter derived from the inlet port of a 750,000 L anaerobic digester led to an increase in total gas and methane production in a subsequent anaerobic digestion step. A high cellulase activity caused by the addition of T. viride seemed to be responsible for a better nutrient availability for anaerobic microorganisms. Therefore, aerobic pre-incubation of organic residues with T. viride for subsequent anaerobic digestion is a promising approach in order to increase methane yields. PMID:23988521

  16. Improvement of methane generation capacity by aerobic pre-treatment of organic waste with a cellulolytic Trichoderma viride culture.

    PubMed

    Wagner, Andreas Otto; Schwarzenauer, Thomas; Illmer, Paul

    2013-11-15

    Trichoderma viride is known as a potent cellulose decomposer and was successfully used to improve and accelerate the decomposition process of aerobic composting. In contrast, the role of fungi as pre-treatment organisms for anaerobic digestion is not clear, since the fast aerobic decomposition is thought to be responsible for a rapid depletion of easily available nutrients, leading to a lack of these for the anaerobic community. In the present study carried out in lab-scale, the application of T. viride for the aerobic pre-incubation of organic matter derived from the inlet port of a 750,000 L anaerobic digester led to an increase in total gas and methane production in a subsequent anaerobic digestion step. A high cellulase activity caused by the addition of T. viride seemed to be responsible for a better nutrient availability for anaerobic microorganisms. Therefore, aerobic pre-incubation of organic residues with T. viride for subsequent anaerobic digestion is a promising approach in order to increase methane yields.

  17. Aerobic cometabolic degradation of trichloroethene by methane and ammonia oxidizing microorganisms naturally associated with Carex comosa roots.

    PubMed

    Powell, C L; Nogaro, G; Agrawal, A

    2011-06-01

    The degradation potential of trichloroethene by the aerobic methane- and ammonia-oxidizing microorganisms naturally associated with wetland plant (Carex comosa) roots was examined in this study. In bench-scale microcosm experiments with washed (soil free) Carex comosa roots, the activity of root-associated methane- and ammonia-oxidizing microorganisms, which were naturally present on the root surface and/or embedded within the roots, was investigated. Significant methane and ammonia oxidation were observed reproducibly in batch reactors with washed roots incubated in growth media, where methane oxidation developed faster (2 weeks) compared to ammonia oxidation (4 weeks) in live microcosms. After enrichment, the methane oxidizers demonstrated their ability to degrade 150 μg l(-1) TCE effectively at 1.9 mg l(-1) of aqueous CH(4). In contrast, ammonia oxidizers showed a rapid and complete inhibition of ammonia oxidation with 150 μg l(-1) TCE at 20 mg l(-1) of NH(4)(+)-N, which may be attributed to greater sensitivity of ammonia oxidizers to TCE or its degradation product. No such inhibitory effect of TCE degradation was detected on methane oxidation at the above experimental conditions. The results presented here suggest that microorganisms associated with wetland plant roots can assist in the natural attenuation of TCE in contaminated aquatic environments.

  18. Variability in aerobic methane oxidation over the past 1.2 Myrs recorded in microbial biomarker signatures from Congo fan sediments

    NASA Astrophysics Data System (ADS)

    Talbot, Helen M.; Handley, Luke; Spencer-Jones, Charlotte L.; Dinga, Bienvenu Jean; Schefuß, Enno; Mann, Paul J.; Poulsen, John R.; Spencer, Robert G. M.; Wabakanghanzi, Jose N.; Wagner, Thomas

    2014-05-01

    Methane (CH4) is a strong greenhouse gas known to have perturbed global climate in the past, especially when released in large quantities over short time periods from continental or marine sources. It is therefore crucial to understand and, if possible, quantify the individual and combined response of these variable methane sources to natural climate variability. However, past changes in the stability of greenhouse gas reservoirs remain uncertain and poorly constrained by geological evidence. Here, we present a record from the Congo fan of a highly specific bacteriohopanepolyol (BHP) biomarker for aerobic methane oxidation (AMO), 35-aminobacteriohopane-30,31,32,33,34-pentol (aminopentol), that identifies discrete periods of increased AMO as far back as 1.2 Ma. Fluctuations in the concentration of aminopentol, and other 35-aminoBHPs, follow a pattern that correlates with late Quaternary glacial-interglacial climate cycles, with highest concentrations during warm periods. We discuss possible sources of aminopentol, and the methane consumed by the precursor methanotrophs, within the context of the Congo River setting, including supply of methane oxidation markers from terrestrial watersheds and/or marine sources (gas hydrate and/or deep subsurface gas reservoir). Compound-specific carbon isotope values of -30‰ to -40‰ for BHPs in ODP 1075 and strong similarities between the BHP signature of the core and surface sediments from the Congo estuary and floodplain wetlands from the interior of the Congo River Basin, support a methanotrophic and likely terrigenous origin of the 35-aminoBHPs found in the fan sediments. This new evidence supports a causal connection between marine sediment BHP records of tropical deep sea fans and wetland settings in the feeding river catchments, and thus tropical continental hydrology. Further research is needed to better constrain the different sources and pathways of methane emission. However, this study identifies the large potential

  19. Aerobic biotransformation of N-nitrosodimethylamine and N-nitrodimethylamine in methane and benzene amended soil columns.

    PubMed

    Weidhaas, Jennifer; Dupont, R Ryan

    2013-07-01

    Aerobic biotransformation of N-nitrosodimethylamine (NDMA), an emerging contaminant of concern, and its structural analog N-nitrodimethylamine (DMN), was evaluated in benzene and methane amended groundwater passed through laboratory scale soil columns. Competitive inhibition models were used to model the kinetics for NDMA and DMN cometabolism accounting for the concurrent degradation of the growth and cometabolic substrates. Transformation capacities for NDMA and DMN with benzene (13 and 23μg (mgcells)(-1)) and methane (0.14 and 8.4μg (mgcells)(-1)) grown cultures, respectively are comparable to those presented in the literature, as were first order endogenous decay rates estimated to be 2.1×10(-2)±1.7×10(-3)d(-1) and 6.5×10(-1)±7.1×10(-1)d(-1) for the methane and benzene amended cultures, respectively. These studies highlight possible attenuation mechanisms and rates for NDMA and DMN biotransformation in aerobic aquifers undergoing active remediation, natural attenuation or managed aquifer recharge with treated wastewater (i.e., reclaimed water).

  20. Temperature-induced increase in methane release from peat bogs: a mesocosm experiment.

    PubMed

    van Winden, Julia F; Reichart, Gert-Jan; McNamara, Niall P; Benthien, Albert; Damsté, Jaap S Sinninghe

    2012-01-01

    Peat bogs are primarily situated at mid to high latitudes and future climatic change projections indicate that these areas may become increasingly wetter and warmer. Methane emissions from peat bogs are reduced by symbiotic methane oxidizing bacteria (methanotrophs). Higher temperatures and increasing water levels will enhance methane production, but also methane oxidation. To unravel the temperature effect on methane and carbon cycling, a set of mesocosm experiments were executed, where intact peat cores containing actively growing Sphagnum were incubated at 5, 10, 15, 20, and 25°C. After two months of incubation, methane flux measurements indicated that, at increasing temperatures, methanotrophs are not able to fully compensate for the increasing methane production by methanogens. Net methane fluxes showed a strong temperature-dependence, with higher methane fluxes at higher temperatures. After removal of Sphagnum, methane fluxes were higher, increasing with increasing temperature. This indicates that the methanotrophs associated with Sphagnum plants play an important role in limiting the net methane flux from peat. Methanotrophs appear to consume almost all methane transported through diffusion between 5 and 15°C. Still, even though methane consumption increased with increasing temperature, the higher fluxes from the methane producing microbes could not be balanced by methanotrophic activity. The efficiency of the Sphagnum-methanotroph consortium as a filter for methane escape thus decreases with increasing temperature. Whereas 98% of the produced methane is retained at 5°C, this drops to approximately 50% at 25°C. This implies that warming at the mid to high latitudes may be enhanced through increased methane release from peat bogs.

  1. Effect of process design and operating parameters on aerobic methane oxidation in municipal WWTPs.

    PubMed

    Daelman, Matthijs R J; Van Eynde, Tamara; van Loosdrecht, Mark C M; Volcke, Eveline I P

    2014-12-01

    Methane is a potent greenhouse gas and its emission from municipal wastewater treatment plants (WWTPs) should be prevented. One way to do this is to promote the biological conversion of dissolved methane over stripping in aeration tanks. In this study, the well-established Activated Sludge Model n°1 (ASM1) and Benchmark Simulation Model n°1 (BSM1) were extended to study the influence of process design and operating parameters on biological methane oxidation. The aeration function used in BSM 1 was upgraded to more accurately describe gas-liquid transfer of oxygen and methane in aeration tanks equipped with subsurface aeration. Dissolved methane could be effectively removed in an aeration tank at an aeration rate that is in agreement with optimal effluent quality. Subsurface bubble aeration proved to be better than surface aeration, while a CSTR configuration was superior to plug flow conditions in avoiding methane emissions. The conversion of methane in the activated sludge tank benefits from higher methane concentrations in the WWTP's influent. Finally, if an activated sludge tank is aerated with methane containing off-gas, a limited amount of methane is absorbed and converted in the mixed liquor. This knowledge helps to stimulate the methane oxidizing capacity of activated sludge in order to abate methane emissions from wastewater treatment to the atmosphere. PMID:25225767

  2. Effect of process design and operating parameters on aerobic methane oxidation in municipal WWTPs.

    PubMed

    Daelman, Matthijs R J; Van Eynde, Tamara; van Loosdrecht, Mark C M; Volcke, Eveline I P

    2014-12-01

    Methane is a potent greenhouse gas and its emission from municipal wastewater treatment plants (WWTPs) should be prevented. One way to do this is to promote the biological conversion of dissolved methane over stripping in aeration tanks. In this study, the well-established Activated Sludge Model n°1 (ASM1) and Benchmark Simulation Model n°1 (BSM1) were extended to study the influence of process design and operating parameters on biological methane oxidation. The aeration function used in BSM 1 was upgraded to more accurately describe gas-liquid transfer of oxygen and methane in aeration tanks equipped with subsurface aeration. Dissolved methane could be effectively removed in an aeration tank at an aeration rate that is in agreement with optimal effluent quality. Subsurface bubble aeration proved to be better than surface aeration, while a CSTR configuration was superior to plug flow conditions in avoiding methane emissions. The conversion of methane in the activated sludge tank benefits from higher methane concentrations in the WWTP's influent. Finally, if an activated sludge tank is aerated with methane containing off-gas, a limited amount of methane is absorbed and converted in the mixed liquor. This knowledge helps to stimulate the methane oxidizing capacity of activated sludge in order to abate methane emissions from wastewater treatment to the atmosphere.

  3. Quantification of ebullitive and diffusive methane release to atmosphere from a water storage

    NASA Astrophysics Data System (ADS)

    Grinham, Alistair; Dunbabin, Matthew; Gale, Deborah; Udy, James

    2011-12-01

    Accurately quantifying total freshwater storage methane release to atmosphere requires the spatial-temporal measurement of both diffusive and ebullitive emissions. Existing floating chamber techniques provide localised assessment of methane flux, however, significant errors can arise when weighting and extrapolation to the entire storage, particularly when ebullition is significant. An improved technique has been developed that compliments traditional chamber based experiments to quantify the storage-scale release of methane gas to atmosphere through ebullition using the measurements from an Optical Methane Detector (OMD) and a robotic boat. This provides a conservative estimate of the methane emission rate from ebullition along with the bubble volume distribution. It also georeferences the area of ebullition activity across entire storages at short temporal scales. An assessment on Little Nerang Dam in Queensland, Australia, demonstrated whole storage methane release significantly differed spatially and throughout the day. Total methane emission estimates showed a potential 32-fold variation in whole-of-dam rates depending on the measurement and extrapolation method and time of day used. The combined chamber and OMD technique showed that 1.8-7.0% of the surface area of Little Nerang Dam is accounting for up to 97% of total methane release to atmosphere throughout the day. Additionally, over 95% of detectable ebullition occurred in depths less than 12 m during the day and 6 m at night. This difference in spatial and temporal methane release rate distribution highlights the need to monitor significant regions of, if not the entire, water storage in order to provide an accurate estimate of ebullition rates and their contribution to annual methane emissions.

  4. Semi-aerobic fermentation as a novel pre-treatment to obtain VFA and increase methane yield from primary sludge.

    PubMed

    Peces, M; Astals, S; Clarke, W P; Jensen, P D

    2016-01-01

    There is a growing trend to consider organic wastes as potential sources of renewable energy and value-add products. Fermentation products have emerged as attractive value-add option due to relative easy production and broad application range. However, pre-fermentation and extraction of soluble products may impact down-stream treatment processes, particularly energy recovery by anaerobic digestion. This paper investigates primary sludge pre-fermentation at different temperatures (20, 37, 55, and 70°C), treatment times (12, 24, 48, and 72h), and oxygen availability (semi-aerobic, anaerobic); and its impact on anaerobic digestion. Pre-fermentation at 20 and 37°C succeeded for VFA production with acetate and propionate being major products. Pre-fermentation at 37, 55, and 70°C resulted in higher solubilisation yield but it reduced sludge methane potential by 20%. Under semi-aerobic conditions, pre-fermentation allowed both VFA recovery (43gCODVFAkg(-1)VS) and improved methane potential. The latter phenomenon was linked to fungi that colonised the sludge top layer during pre-fermentation. PMID:26551651

  5. Uncorking the bottle: What triggered the Paleocene/Eocene thermal maximum methane release?

    NASA Astrophysics Data System (ADS)

    Katz, Miriam E.; Cramer, Benjamin S.; Mountain, Gregory S.; Katz, Samuel; Miller, Kenneth G.

    2001-12-01

    The Paleocene/Eocene thermal maximum (PETM) was a time of rapid global warming in both marine and continental realms that has been attributed to a massive methane (CH4) release from marine gas hydrate reservoirs. Previously proposed mechanisms for this methane release rely on a change in deepwater source region(s) to increase water temperatures rapidly enough to trigger the massive thermal dissociation of gas hydrate reservoirs beneath the seafloor. To establish constraints on thermal dissociation, we model heat flow through the sediment column and show the effect of the temperature change on the gas hydrate stability zone through time. In addition, we provide seismic evidence tied to borehole data for methane release along portions of the U.S. continental slope; the release sites are proximal to a buried Mesozoic reef front. Our model results, release site locations, published isotopic records, and ocean circulation models neither confirm nor refute thermal dissociation as the trigger for the PETM methane release. In the absence of definitive evidence to confirm thermal dissociation, we investigate an alternative hypothesis in which continental slope failure resulted in a catastrophic methane release. Seismic and isotopic evidence indicates that Antarctic source deepwater circulation and seafloor erosion caused slope retreat along the western margins of the North Atlantic in the late Paleocene. Continued erosion or seismic activity along the oversteepened continental margin may have allowed methane to escape from gas reservoirs trapped between the frozen hydrate-bearing sediments and the underlying buried Mesozoic reef front, precipitating the Paleocene/Eocene boundary methane release. An important implication of this scenario is that the methane release caused (rather than resulted from) the transient temperature increase of the PETM. Neither thermal dissociation nor mechanical disruption of sediments can be identified unequivocally as the triggering mechanism

  6. Combined thermophilic aerobic process and conventional anaerobic digestion: effect on sludge biodegradation and methane production.

    PubMed

    Dumas, C; Perez, S; Paul, E; Lefebvre, X

    2010-04-01

    The efficiency of hyper-thermophilic (65 degrees Celsius) aerobic process coupled with a mesophilic (35 degrees Celsius) digester was evaluated for the activated sludge degradation and was compared to a conventional mesophilic digester. For two Sludge Retention Time (SRT), 21 and 42 days, the Chemical Oxygen Demand (COD) solubilisation and biodegradation processes, the methanisation yield and the aerobic oxidation were investigated during 180 days. The best results were obtained at SRT of 44 days; the COD removal yield was 30% higher with the Mesophilic Anaerobic Digestion/Thermophilic Aerobic Reactor (MAD-TAR) co-treatment. An increase of the sludge intrinsic biodegradability is also observed (20-40%), showing that the unbiodegradable COD in mesophilic conditions becomes bioavailable. However, the methanisation yield was quite similar for both processes at a same SRT. Finally, such a process enables to divide by two the volume of digester with an equivalent efficiency.

  7. Limits on methane release and generation via hypervelocity impact of Martian analogue materials

    NASA Astrophysics Data System (ADS)

    Price, M. C.; Ramkissoon, N. K.; McMahon, S.; Miljković, K.; Parnell, J.; Wozniakiewicz, P. J.; Kearsley, A. T.; Blamey, N. J. F.; Cole, M. J.; Burchell, M. J.

    2014-04-01

    The quantity of methane in Mars' atmosphere, and the potential mechanism(s) responsible for its production, are still unknown. In order to test viable, abiotic, methangenic processes, we experimentally investigated two possible impact mechanisms for generating methane. In the first suite of experiments, basaltic rocks were impacted at 5 km s-1 and the quantity of gases (CH4, H2, He, N2, O2, Ar and CO2) released by the impacts was measured. In the second suite of experiments, a mixture of water ice, CO2 ice and anhydrous olivine grains was impacted to see if the shock induced rapid serpentinization of the olivine, and thus production of methane. The results of both suites of experiments demonstrate that impacts (at scales achievable in the laboratory) do not give rise to detectably enhanced quantities of methane release above background levels. Supporting hydrocode modelling was also performed to gain insight into the pressures and temperatures occurring during the impact events.

  8. Methane release from sediment seeps to the atmosphere is counteracted by highly active Methylococcaceae in the water column of deep oligotrophic Lake Constance.

    PubMed

    Bornemann, Maren; Bussmann, Ingeborg; Tichy, Lucas; Deutzmann, Jörg; Schink, Bernhard; Pester, Michael

    2016-08-01

    Methane emissions from freshwater environments contribute substantially to global warming but are under strong control of aerobic methane-oxidizing bacteria. Recently discovered methane seeps (pockmarks) in freshwater lake sediments have the potential to bypass this control by their strong outgassing activity. Whether this is counteracted by pelagic methanotrophs is not well understood yet. We used a (3)H-CH4-radiotracer technique and pmoA-based molecular approaches to assess the activity, abundance and community structure of pelagic methanotrophs above active pockmarks in deep oligotrophic Lake Constance. Above profundal pockmarks, methane oxidation rates (up to 458 nmol CH4 l(-1) d(-1)) exceeded those of the surrounding water column by two orders of magnitude and coincided with maximum methanotroph abundances of 0.6% of the microbial community. Phylogenetic analysis indicated a dominance of members of the Methylococcaceae in the water column of both, pockmark and reference sites, with most of the retrieved sequences being associated with a water-column specific clade. Communities at pockmark and reference locations also differed in parts, which was likely caused by entrainment of sediment-hosted methanotrophs at pockmark sites. Our results show that the release of seep-derived methane to the atmosphere is counteracted by a distinct methanotrophic community with a pronounced activity throughout bottom waters. PMID:27267930

  9. Methane release from sediment seeps to the atmosphere is counteracted by highly active Methylococcaceae in the water column of deep oligotrophic Lake Constance.

    PubMed

    Bornemann, Maren; Bussmann, Ingeborg; Tichy, Lucas; Deutzmann, Jörg; Schink, Bernhard; Pester, Michael

    2016-08-01

    Methane emissions from freshwater environments contribute substantially to global warming but are under strong control of aerobic methane-oxidizing bacteria. Recently discovered methane seeps (pockmarks) in freshwater lake sediments have the potential to bypass this control by their strong outgassing activity. Whether this is counteracted by pelagic methanotrophs is not well understood yet. We used a (3)H-CH4-radiotracer technique and pmoA-based molecular approaches to assess the activity, abundance and community structure of pelagic methanotrophs above active pockmarks in deep oligotrophic Lake Constance. Above profundal pockmarks, methane oxidation rates (up to 458 nmol CH4 l(-1) d(-1)) exceeded those of the surrounding water column by two orders of magnitude and coincided with maximum methanotroph abundances of 0.6% of the microbial community. Phylogenetic analysis indicated a dominance of members of the Methylococcaceae in the water column of both, pockmark and reference sites, with most of the retrieved sequences being associated with a water-column specific clade. Communities at pockmark and reference locations also differed in parts, which was likely caused by entrainment of sediment-hosted methanotrophs at pockmark sites. Our results show that the release of seep-derived methane to the atmosphere is counteracted by a distinct methanotrophic community with a pronounced activity throughout bottom waters.

  10. Methane release from igneous intrusion of coal during Late Permian extinction events

    SciTech Connect

    Retallack, G.J.; Jahren, A.H.

    2008-01-15

    Unusually large and locally variable carbon isotope excursions coincident with mass extinctions at the end of the Permian Period (253 Ma) and Guadalupian Epoch (260 Ma) can be attributed to methane outbursts to the atmosphere. Methane has isotopic values {delta}{sup 13}C low enough to reduce to feasible amounts the carbon required for isotopic mass balance. The duration of the carbon isotopic excursions and inferred methane releases are here constrained to < 10,000 yr by counting annual varves in lake deposits and by estimating peat accumulation rates. On paleogeographic maps, the most marked carbon isotope excursions form linear arrays back to plausible methane sources: end-Permian Siberian Traps and Longwood-Bluff intrusions of New Zealand and end-Guadalupian Emeishan Traps of China. Intrusion of coal seams by feeder dikes to flood basalts could create successive thermogenic methane outbursts of the observed timing and magnitude, but these are unreasonably short times for replenishment of marine or permafrost sources of methane. Methane released by fracturing and heating of coal during intrusion of large igneous provinces may have been a planetary hazard comparable with bolide impact.

  11. Hypotheses for a Near-Surface Reservoir of Methane and Its Release on Mars

    NASA Astrophysics Data System (ADS)

    Hu, R.; Bloom, A. A.; Gao, P.; Miller, C. E.; Yung, Y. L.

    2015-12-01

    The Curiosity rover recently detected a background of 0.7 ppb and spikes of 7 ppb of methane on Mars. This in situ measurement reorients our understanding of the Martian environment and its potential for life, as the current theories do not entail any active source or sink of methane. In particular, the 10-fold elevation during the southern winter indicates episodic sources of methane that are yet to be discovered. Using the temperature and humidity measurements from the rover, we find that perchlorate salts in the regolith deliquesce to form liquid solutions, and deliquescence progresses to deeper subsurface in the season of the methane spikes. We therefore formulate the following three testable hypotheses as an attempt to explain the apparent variability of the atmospheric methane abundance. The first scenario is that the regolith in Gale Crater adsorbs methane when dry and releases this methane to the atmosphere upon deliquescence. The adsorption energy needs to be 36 kJ mol-1 to explain the magnitude of the methane spikes, higher than laboratory measurements. The second scenario is that microorganisms exist and convert organic matter in the soil to methane when they are in liquid solutions. This scenario does not require regolith adsorption. The third scenario is that deep subsurface aquifers sealed by ice or clathrate produce bursts of methane as a result of freezing and thawing of the permafrost, as the terrestrial arctic tundra. Continued monitoring of methane by Curiosity will test the existence of the near-surface reservoir and its exchange with the atmosphere.

  12. Methane oxidation activity and diversity of aerobic methanotrophs in pH-neutral and semi-neutral thermal springs of the Kunashir Island, Russian Far East.

    PubMed

    Kizilova, A K; Sukhacheva, M V; Pimenov, N V; Yurkov, A M; Kravchenko, I K

    2014-03-01

    Aerobic methane oxidation has been mostly studied in environments with moderate to low temperatures. However, the process also occurs in terrestrial thermal springs, where little research on the subject has been done to date. The potential activity of methane oxidation and diversity of aerobic methanotrophic bacteria were studied in sediments of thermal springs with various chemical and physical properties, sampled across the Kunashir Island, the Kuriles archipelago. Activity was measured by means of the radioisotope tracer technique utilizing (14)C-labeled methane. Biodiversity assessments were based on the particulate methane monooxygenase (pmoA) gene, which is found in all known thermophilic and thermotolerant methanotrophs. We demonstrated the possibility of methane oxidation in springs with temperature exceeding 74 °C, and the most intensive methane uptake was shown in springs with temperatures about 46 °C. PmoA was detected in 19 out of 30 springs investigated and the number of pmoA gene copies varied between 10(4) and 10(6) copies per ml of sediment. Phylogenetic analysis of PmoA sequences revealed the presence of methanotrophs from both the Alpha- and Gammaproteobacteria. Our results suggest that methanotrophs inhabiting thermal springs with temperature exceeding 50 °C may represent novel thermophilic and thermotolerant species of the genera Methylocystis and Methylothermus, as well as previously undescribed Gammaproteobacteria. PMID:24343375

  13. Release of ANP and fat oxidation in overweight persons during aerobic exercise in water.

    PubMed

    Fenzl, M; Schnizer, W; Aebli, N; Schlegel, C; Villiger, B; Disch, A; Gredig, J; Zaugg, T; Krebs, J

    2013-09-01

    Exercise in water compared to land-based exercise (LE) results in a higher release of natriuretic peptides, which are involved in the regulation of exercise-induced adipose tissue lipolysis. The present study was performed to compare the release of atrial natriuretic peptide (ANP) and free fatty acids (FFA) during prolonged aerobic water-based exercise (WE) with the release after an identical LE. 14 untrained overweight subjects performed 2 steady state workload tests on the same ergometer in water and on land. Before and after exercise, venous blood samples were collected for measuring ANP, FFA, epinephrine, norepinephrine, insulin and glucose. The respiratory exchange ratio (RER) was determined for fat oxidation.The exercises resulted in a significant increase in ANP in LE (61%) and in WE (177%), and FFA increased about 3-fold in LE and WE with no significant difference between the groups. Epinephrine increased, while insulin decreased similarly in both groups. The RER values decreased during the exercises, but there was no significant difference between LE and WE. In conclusion, the higher ANP concentrations in WE had no additional effect on lipid mobilization, FFA release and fat oxidation. Moderate-intensity exercises in water offer no benefit regarding adipose tissue lipolysis in comparison to LE.

  14. Nanostructural control of methane release in kerogen and its implications to wellbore production decline

    NASA Astrophysics Data System (ADS)

    Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

    2016-06-01

    Despite massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix-a limiting step in shale gas extraction. Using molecular simulations, we here show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30-47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3-35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release.

  15. Nanostructural control of methane release in kerogen and its implications to wellbore production decline

    DOE PAGES

    Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

    2016-06-16

    In spite of the massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix–a limiting step in shale gas extraction. Here we show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30–47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases, and we usemore » molecular simulations to demonstrate it. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3–35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Finally, our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release.« less

  16. Nanostructural control of methane release in kerogen and its implications to wellbore production decline

    PubMed Central

    Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

    2016-01-01

    Despite massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix–a limiting step in shale gas extraction. Using molecular simulations, we here show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30–47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3–35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release. PMID:27306967

  17. Nanostructural control of methane release in kerogen and its implications to wellbore production decline

    NASA Astrophysics Data System (ADS)

    Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

    2016-06-01

    Despite massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix–a limiting step in shale gas extraction. Using molecular simulations, we here show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30–47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3–35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release.

  18. Nanostructural control of methane release in kerogen and its implications to wellbore production decline.

    PubMed

    Ho, Tuan Anh; Criscenti, Louise J; Wang, Yifeng

    2016-01-01

    Despite massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix-a limiting step in shale gas extraction. Using molecular simulations, we here show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30-47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3-35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release. PMID:27306967

  19. Ice-sheet-driven methane storage and release in the Arctic.

    PubMed

    Portnov, Alexey; Vadakkepuliyambatta, Sunil; Mienert, Jürgen; Hubbard, Alun

    2016-01-01

    It is established that late-twentieth and twenty-first century ocean warming has forced dissociation of gas hydrates with concomitant seabed methane release. However, recent dating of methane expulsion sites suggests that gas release has been ongoing over many millennia. Here we synthesize observations of ∼1,900 fluid escape features--pockmarks and active gas flares--across a previously glaciated Arctic margin with ice-sheet thermomechanical and gas hydrate stability zone modelling. Our results indicate that even under conservative estimates of ice thickness with temperate subglacial conditions, a 500-m thick gas hydrate stability zone--which could serve as a methane sink--existed beneath the ice sheet. Moreover, we reveal that in water depths 150-520 m methane release also persisted through a 20-km-wide window between the subsea and subglacial gas hydrate stability zone. This window expanded in response to post-glacial climate warming and deglaciation thereby opening the Arctic shelf for methane release. PMID:26739497

  20. Ice-sheet-driven methane storage and release in the Arctic

    NASA Astrophysics Data System (ADS)

    Portnov, Alexey; Vadakkepuliyambatta, Sunil; Mienert, Jürgen; Hubbard, Alun

    2016-01-01

    It is established that late-twentieth and twenty-first century ocean warming has forced dissociation of gas hydrates with concomitant seabed methane release. However, recent dating of methane expulsion sites suggests that gas release has been ongoing over many millennia. Here we synthesize observations of ~1,900 fluid escape features--pockmarks and active gas flares--across a previously glaciated Arctic margin with ice-sheet thermomechanical and gas hydrate stability zone modelling. Our results indicate that even under conservative estimates of ice thickness with temperate subglacial conditions, a 500-m thick gas hydrate stability zone--which could serve as a methane sink--existed beneath the ice sheet. Moreover, we reveal that in water depths 150-520 m methane release also persisted through a 20-km-wide window between the subsea and subglacial gas hydrate stability zone. This window expanded in response to post-glacial climate warming and deglaciation thereby opening the Arctic shelf for methane release.

  1. Ice-sheet-driven methane storage and release in the Arctic

    PubMed Central

    Portnov, Alexey; Vadakkepuliyambatta, Sunil; Mienert, Jürgen; Hubbard, Alun

    2016-01-01

    It is established that late-twentieth and twenty-first century ocean warming has forced dissociation of gas hydrates with concomitant seabed methane release. However, recent dating of methane expulsion sites suggests that gas release has been ongoing over many millennia. Here we synthesize observations of ∼1,900 fluid escape features—pockmarks and active gas flares—across a previously glaciated Arctic margin with ice-sheet thermomechanical and gas hydrate stability zone modelling. Our results indicate that even under conservative estimates of ice thickness with temperate subglacial conditions, a 500-m thick gas hydrate stability zone—which could serve as a methane sink—existed beneath the ice sheet. Moreover, we reveal that in water depths 150–520 m methane release also persisted through a 20-km-wide window between the subsea and subglacial gas hydrate stability zone. This window expanded in response to post-glacial climate warming and deglaciation thereby opening the Arctic shelf for methane release. PMID:26739497

  2. Modeling of Oceanic Gas Hydrate Instability and Methane Release in Response to Climate Change

    SciTech Connect

    Reagan, Matthew; Reagan, Matthew T.; Moridis, George J.

    2008-04-15

    Paleooceanographic evidence has been used to postulate that methane from oceanic hydrates may have had a significant role in regulating global climate, implicating global oceanic deposits of methane gas hydrate as the main culprit in instances of rapid climate change that have occurred in the past. However, the behavior of contemporary oceanic methane hydrate deposits subjected to rapid temperature changes, like those predicted under future climate change scenarios, is poorly understood. To determine the fate of the carbon stored in these hydrates, we performed simulations of oceanic gas hydrate accumulations subjected to temperature changes at the seafloor and assessed the potential for methane release into the ocean. Our modeling analysis considered the properties of benthic sediments, the saturation and distribution of the hydrates, the ocean depth, the initial seafloor temperature, and for the first time, estimated the effect of benthic biogeochemical activity. The results show that shallow deposits--such as those found in arctic regions or in the Gulf of Mexico--can undergo rapid dissociation and produce significant methane fluxes of 2 to 13 mol/yr/m{sup 2} over a period of decades, and release up to 1,100 mol of methane per m{sup 2} of seafloor in a century. These fluxes may exceed the ability of the seafloor environment (via anaerobic oxidation of methane) to consume the released methane or sequester the carbon. These results will provide a source term to regional or global climate models in order to assess the coupling of gas hydrate deposits to changes in the global climate.

  3. Methane oxidation in a crude oil contaminated aquifer: Delineation of aerobic reactions at the plume fringes

    NASA Astrophysics Data System (ADS)

    Amos, Richard T.; Bekins, Barbara A.; Delin, Geoffrey N.; Cozzarelli, Isabelle M.; Blowes, David W.; Kirshtein, Julie D.

    2011-07-01

    High resolution direct-push profiling over short vertical distances was used to investigate CH 4 attenuation in a petroleum contaminated aquifer near Bemidji, Minnesota. The contaminant plume was delineated using dissolved gases, redox sensitive components, major ions, carbon isotope ratios in CH 4 and CO 2, and the presence of methanotrophic bacteria. Sharp redox gradients were observed near the water table. Shifts in δ 13C CH4 from an average of - 57.6‰ (± 1.7‰) in the methanogenic zone to - 39.6‰ (± 8.7‰) at 105 m downgradient, strongly suggest CH 4 attenuation through microbially mediated degradation. In the downgradient zone the aerobic/anaerobic transition is up to 0.5 m below the water table suggesting that transport of O 2 across the water table is leading to aerobic degradation of CH 4 at this interface. Dissolved N 2 concentrations that exceeded those expected for water in equilibrium with the atmosphere indicated bubble entrapment followed by preferential stripping of O 2 through aerobic degradation of CH 4 or other hydrocarbons. Multivariate and cluster analysis were used to distinguish between areas of significant bubble entrapment and areas where other processes such as the infiltration of O 2 rich recharge water were important O 2 transport mechanisms.

  4. Methane oxidation in a crude oil contaminated aquifer: Delineation of aerobic reactions at the plume fringes

    USGS Publications Warehouse

    Amos, R.T.; Bekins, B.A.; Delin, G.N.; Cozzarelli, I.M.; Blowes, D.W.; Kirshtein, J.D.

    2011-01-01

    High resolution direct-push profiling over short vertical distances was used to investigate CH4 attenuation in a petroleum contaminated aquifer near Bemidji, Minnesota. The contaminant plume was delineated using dissolved gases, redox sensitive components, major ions, carbon isotope ratios in CH4 and CO2, and the presence of methanotrophic bacteria. Sharp redox gradients were observed near the water table. Shifts in ??13CCH4 from an average of - 57.6??? (?? 1.7???) in the methanogenic zone to - 39.6??? (?? 8.7???) at 105 m downgradient, strongly suggest CH4 attenuation through microbially mediated degradation. In the downgradient zone the aerobic/anaerobic transition is up to 0.5 m below the water table suggesting that transport of O2 across the water table is leading to aerobic degradation of CH4 at this interface. Dissolved N2 concentrations that exceeded those expected for water in equilibrium with the atmosphere indicated bubble entrapment followed by preferential stripping of O2 through aerobic degradation of CH4 or other hydrocarbons. Multivariate and cluster analysis were used to distinguish between areas of significant bubble entrapment and areas where other processes such as the infiltration of O 2 rich recharge water were important O2 transport mechanisms. ?? 2011 Elsevier B.V. All rights reserved.

  5. Halite as a Methane Sequestration Host: A Possible Explanation for Periodic Methane Release on Mars, and a Surface-accessible Source of Ancient Martian Carbon

    NASA Technical Reports Server (NTRS)

    Fries, M. D.; Steele, Andrew; Hynek, B. M.

    2015-01-01

    We present the hypothesis that halite may play a role in methane sequestration on the martian surface. In terrestrial examples, halite deposits sequester large volumes of methane and chloromethane. Also, examples of chloromethane-bearing, approximately 4.5 Ga old halite from the Monahans meteorite show that this system is very stable unless the halite is damaged. On Mars, methane may be generated from carbonaceous material trapped in ancient halite deposits and sequestered. The methane may be released by damaging its halite host; either by aqueous alteration, aeolian abrasion, heating, or impact shock. Such a scenario may help to explain the appearance of short-lived releases of methane on the martian surface. The methane may be of either biogenic or abiogenic origin. If this scenario plays a significant role on Mars, then martian halite deposits may contain samples of organic compounds dating to the ancient desiccation of the planet, accessible at the surface for future sample return missions.

  6. Antibacterial Action of Nitric Oxide-Releasing Chitosan Oligosaccharides against Pseudomonas aeruginosa under Aerobic and Anaerobic Conditions

    PubMed Central

    Reighard, Katelyn P.

    2015-01-01

    Chitosan oligosaccharides were modified with N-diazeniumdiolates to yield biocompatible nitric oxide (NO) donor scaffolds. The minimum bactericidal concentrations and MICs of the NO donors against Pseudomonas aeruginosa were compared under aerobic and anaerobic conditions. Differential antibacterial activities were primarily the result of NO scavenging by oxygen under aerobic environments and not changes in bacterial physiology. Bacterial killing was also tested against nonmucoid and mucoid biofilms and compared to that of tobramycin. Smaller NO payloads were required to eradicate P. aeruginosa biofilms under anaerobic versus aerobic conditions. Under oxygen-free environments, the NO treatment was 10-fold more effective at killing biofilms than tobramycin. These results demonstrate the potential utility of NO-releasing chitosan oligosaccharides under both aerobic and anaerobic environments. PMID:26239983

  7. Surface release of methane into the atmosphere of Mars: A new model study

    NASA Astrophysics Data System (ADS)

    Viscardy, Sébastien; Daerden, Frank; Neary, Lori; García Muñoz, Antonio; Carine Vandaele, Ann

    2015-04-01

    In the past decade, the detection of methane (CH4) in the atmosphere of Mars has been reported several times (Krasnopolsky et al., Icarus, 2004, Formisano et al., Science, 2004, Mumma et al., Science, 2009, Fonti and Marzo, A&A, 2010 , Webster et al., Science, 2014). These observations have strongly drawn the attention of the scientific community and triggered a renewed interest in Mars as their implications for the geochemical or biological activities are remarkable. However, given that methane is expected to have a photochemical lifetime of several centuries, the relatively fast loss rates of methane estimated from Earth-based measurements remain unexplained (Lefèvre and Forget, Nature, 2009). Although this gave rise to objections against the validity of those observations (Zahnle et al., Icarus, 2011), recent in situ measurements (Webster et al., Science, 2014) confirmed that methane is being occasionally released into the atmosphere from an unknown source (possibly from the ground). In this context, we aim to investigate the time and space evolution of methane after different surface release scenarios using a 3D Global Circulation Model (GCM) for the atmosphere of Mars (Daerden et al., 2015). This work continues on that of Mischna et al. (PSS, 2011). We specifically focus on the vertical distribution of methane in order to provide useful information for the highly sensitive NOMAD solar occultation channel (Drummond et al., PSS, 2011) on the future ExoMars Trace Gas Orbiter mission.

  8. Release of isoprene and monoterpenes during the aerobic decomposition of orange wastes from laboratory incubation experiments.

    PubMed

    Wang, Xinming; Wu, Ting

    2008-05-01

    The release of isoprene and 12 monoterpenes during the decomposition of orange wastes was studied under controlled aerobic conditions in laboratory for a period of 2 months. Monoterpenes (mainly limonene, beta-myrcene, sabinene, and alpha-pinene) dominated among the released volatile organic compounds, but isoprene was only a very minor constituent. Two time windows with peak microbial activity were indicated by CO2 emission fluxes and waste temperature, both of which reached their maximums 3-4 days and 15-20 days after the incubation, respectively. Although isoprene had only one emission peak synchronizing with the first peak microbial activity, monoterpenes had relatively high emission rates, but they decreased at the beginning without correlation to the first peak of microbial activity, due largely to direct volatilization of these monoterpenes primarily present in orange substrates as inherited constituents. However, after the initial decrease the emission rates of monoterpenes rose again in conjunction with the second peak of microbial activity, indicating secondary production of these monoterpenes through microbial activity. On the basis of monitored emission fluxes, the amounts of secondarily formed monoterpenes from microbial activity well surpassed those inherited in the orange wastes. Production of total terpenes reached 1.10 x 10(4) mg kg(-1) (dry weight), of which limonene alone was 63%. For either limonene or total terpenes, about 95% of their emission occurred in the first 30 days, implying that organic wastes might give off considerable amount of terpenes during early disposal under aerobic conditions before the conventional anaerobic landfilling, and emission measurements just in landfills might underestimate the waste-related emissions of reactive organic gases. PMID:18522104

  9. Methylated silicates may explain the release of chlorinated methane from Martian soil

    NASA Astrophysics Data System (ADS)

    Bak, Ebbe N.; Jensen, Svend J. Knak; Nørnberg, Per; Finster, Kai

    2016-01-01

    The only organic compounds that have been detected in the Martian soil are simple chlorinated compounds released from heated surface material. However, the sources of the organic carbon are in dispute. Wind abraded silicates, which are widespread on the Martian surface, can sequester atmospheric methane which generates methylated silicates and thus could provide a mechanism for accumulation of reduced carbon in the surface soil. In this study we show that thermal volatilization of methylated silicates in the presence of perchlorate leads to the production of chlorinated methane. Thus, methylated silicates could be a source of the organic carbon released as chlorinated methane upon thermal volatilization of Martian soil samples. Further, our experiments show that the ratio of the different chlorinated compounds produced is dependent on the mass ratio of perchlorate to organic carbon in the soil.

  10. Phylogenetic and enzymatic diversity of deep subseafloor aerobic microorganisms in organics- and methane-rich sediments off Shimokita Peninsula.

    PubMed

    Kobayashi, Tohru; Koide, Osamu; Mori, Kozue; Shimamura, Shigeru; Matsuura, Takae; Miura, Takeshi; Takaki, Yoshihiro; Morono, Yuki; Nunoura, Takuro; Imachi, Hiroyuki; Inagaki, Fumio; Takai, Ken; Horikoshi, Koki

    2008-07-01

    "A meta-enzyme approach" is proposed as an ecological enzymatic method to explore the potential functions of microbial communities in extreme environments such as the deep marine subsurface. We evaluated a variety of extra-cellular enzyme activities of sediment slurries and isolates from a deep subseafloor sediment core. Using the new deep-sea drilling vessel "Chikyu", we obtained 365 m of core sediments that contained approximately 2% organic matter and considerable amounts of methane from offshore the Shimokita Peninsula in Japan at a water depth of 1,180 m. In the extra-sediment fraction of the slurry samples, phosphatase, esterase, and catalase activities were detected consistently throughout the core sediments down to the deepest slurry sample from 342.5 m below seafloor (mbsf). Detectable enzyme activities predicted the existence of a sizable population of viable aerobic microorganisms even in deep subseafloor habitats. The subsequent quantitative cultivation using solid media represented remarkably high numbers of aerobic, heterotrophic microbial populations (e.g., maximally 4.4x10(7) cells cm(-3) at 342.5 mbsf). Analysis of 16S rRNA gene sequences revealed that the predominant cultivated microbial components were affiliated with the genera Bacillus, Shewanella, Pseudoalteromonas, Halomonas, Pseudomonas, Paracoccus, Rhodococcus, Microbacterium, and Flexibacteracea. Many of the predominant and scarce isolates produced a variety of extra-cellular enzymes such as proteases, amylases, lipases, chitinases, phosphatases, and deoxyribonucleases. Our results indicate that microbes in the deep subseafloor environment off Shimokita are metabolically active and that the cultivable populations may have a great potential in biotechnology.

  11. Phylogenetic and enzymatic diversity of deep subseafloor aerobic microorganisms in organics- and methane-rich sediments off Shimokita Peninsula.

    PubMed

    Kobayashi, Tohru; Koide, Osamu; Mori, Kozue; Shimamura, Shigeru; Matsuura, Takae; Miura, Takeshi; Takaki, Yoshihiro; Morono, Yuki; Nunoura, Takuro; Imachi, Hiroyuki; Inagaki, Fumio; Takai, Ken; Horikoshi, Koki

    2008-07-01

    "A meta-enzyme approach" is proposed as an ecological enzymatic method to explore the potential functions of microbial communities in extreme environments such as the deep marine subsurface. We evaluated a variety of extra-cellular enzyme activities of sediment slurries and isolates from a deep subseafloor sediment core. Using the new deep-sea drilling vessel "Chikyu", we obtained 365 m of core sediments that contained approximately 2% organic matter and considerable amounts of methane from offshore the Shimokita Peninsula in Japan at a water depth of 1,180 m. In the extra-sediment fraction of the slurry samples, phosphatase, esterase, and catalase activities were detected consistently throughout the core sediments down to the deepest slurry sample from 342.5 m below seafloor (mbsf). Detectable enzyme activities predicted the existence of a sizable population of viable aerobic microorganisms even in deep subseafloor habitats. The subsequent quantitative cultivation using solid media represented remarkably high numbers of aerobic, heterotrophic microbial populations (e.g., maximally 4.4x10(7) cells cm(-3) at 342.5 mbsf). Analysis of 16S rRNA gene sequences revealed that the predominant cultivated microbial components were affiliated with the genera Bacillus, Shewanella, Pseudoalteromonas, Halomonas, Pseudomonas, Paracoccus, Rhodococcus, Microbacterium, and Flexibacteracea. Many of the predominant and scarce isolates produced a variety of extra-cellular enzymes such as proteases, amylases, lipases, chitinases, phosphatases, and deoxyribonucleases. Our results indicate that microbes in the deep subseafloor environment off Shimokita are metabolically active and that the cultivable populations may have a great potential in biotechnology. PMID:18368287

  12. Compositional and functional stability of aerobic methane consuming communities in drained and rewetted peat meadows.

    PubMed

    Krause, Sascha; Niklaus, Pascal A; Badwan Morcillo, Sara; Meima Franke, Marion; Lüke, Claudia; Reim, Andreas; Bodelier, Paul L E

    2015-11-01

    The restoration of peatlands is an important strategy to counteract subsidence and loss of biodiversity. However, responses of important microbial soil processes are poorly understood. We assessed functioning, diversity and spatial organization of methanotrophic communities in drained and rewetted peat meadows with different water table management and agricultural practice. Results show that the methanotrophic diversity was similar between drained and rewetted sites with a remarkable dominance of the genus Methylocystis. Enzyme kinetics depicted no major differences, indicating flexibility in the methane (CH4) concentrations that can be used by the methanotrophic community. Short-term flooding led to temporary elevated CH4 emission but to neither major changes in abundances of methane-oxidizing bacteria (MOB) nor major changes in CH4 consumption kinetics in drained agriculturally used peat meadows. Radiolabeling and autoradiographic imaging of intact soil cores revealed a markedly different spatial arrangement of the CH4 consuming zone in cores exposed to near-atmospheric and elevated CH4. The observed spatial patterns of CH4 consumption in drained peat meadows with and without short-term flooding highlighted the spatial complexity and responsiveness of the CH4 consuming zone upon environmental change. The methanotrophic microbial community is not generally altered and harbors MOB that can cover a large range of CH4 concentrations offered due to water-table fluctuations, effectively mitigating CH4 emissions.

  13. Dynamic simulations of potential methane release from East Siberian continental slope sediments

    NASA Astrophysics Data System (ADS)

    Stranne, C.; O'Regan, M.; Dickens, G. R.; Crill, P. M.; Miller, C.; Preto, P.; Jakobsson, M.

    2015-12-01

    Sediments deposited along continental margins of the Arctic Ocean presumably host large amounts of CH4 in gas hydrates. Here we apply numerical simulations to assess the potential of gas hydrate dissociation and methane release from the East Siberian slope over the next 100 years. Simulations are based on a hypothesized bottom water warming of 3 °C, and an assumed starting distribution of gas hydrate. The simulation results show that methane hydrate dissociation in these sediments is relatively slow, and that gas fluxes toward the seafloor are limited by low sediment permeability. The latter is true even when sediment fractures are permitted to form through overpressure. With an initial gas hydrate distbution dictated by present-day pressure and temperature conditions, nominally 0.35 gigaton of CH4 are released from the East Siberian slope during the first 100 years of the simulation. However, this methane discharge is reduced significantly (to ~0.05 Gt) if Arctic Ocean history is considered. This is because a lower sea level during the last glacial maximum must result in depleted gas hydrate abundance within the most sensitive region of the modern gas hydrate stability zone. In any case, even if methane reached the atmosphere, amounts coming from East Siberian slopes would be minimal compared to present-day atmospheric methane inputs from other sources.

  14. Quantification of methane fluxes from industrial sites using a combination of a tracer release method and a Gaussian model

    NASA Astrophysics Data System (ADS)

    Ars, S.; Broquet, G.; Yver-Kwok, C.; Wu, L.; Bousquet, P.; Roustan, Y.

    2015-12-01

    Greenhouse gas (GHG) concentrations keep on increasing in the atmosphere since industrial revolution. Methane (CH4) is the second most important anthropogenic GHG after carbon dioxide (CO2). Its sources and sinks are nowadays well identified however their relative contributions remain uncertain. The industries and the waste treatment emit an important part of the anthropogenic methane that is difficult to quantify because the sources are fugitive and discontinuous. A better estimation of methane emissions could help industries to adapt their mitigation's politic and encourage them to install methane recovery systems in order to reduce their emissions while saving money. Different methods exist to quantify methane emissions. Among them is the tracer release method consisting in releasing a tracer gas near the methane source at a well-known rate and measuring both their concentrations in the emission plume. The methane rate is calculated using the ratio of methane and tracer concentrations and the emission rate of the tracer. A good estimation of the methane emissions requires a good differentiation between the methane actually emitted by the site and the methane from the background concentration level, but also a good knowledge of the sources distribution over the site. For this purpose, a Gaussian plume model is used in addition to the tracer release method to assess the emission rates calculated. In a first step, the data obtained for the tracer during a field campaign are used to tune the model. Different model's parameterizations have been tested to find the best representation of the atmospheric dispersion conditions. Once these parameters are set, methane emissions are estimated thanks to the methane concentrations measured and a Bayesian inversion. This enables to adjust the position and the emission rate of the different methane sources of the site and remove the methane background concentration.

  15. Microbial community structure in a thermophilic aerobic digester used as a sludge pretreatment process for the mesophilic anaerobic digestion and the enhancement of methane production.

    PubMed

    Jang, Hyun Min; Park, Sang Kyu; Ha, Jeong Hyub; Park, Jong Moon

    2013-10-01

    An effective two-stage sewage sludge digestion process, consisting of thermophilic aerobic digestion (TAD) followed by mesophilic anaerobic digestion (MAD), was developed for efficient sludge reduction and methane production. Using TAD as a biological pretreatment, the total volatile suspended solid reduction (VSSR) and methane production rate (MPR) in the MAD reactor were significantly improved. According to denaturing gradient gel electrophoresis (DGGE) analysis, the results indicated that the dominant bacteria species such as Ureibacillus thermophiles and Bacterium thermus in TAD were major routes for enhancing soluble organic matter. TAD pretreatment using a relatively short SRT of 1 day showed highly increased soluble organic products and positively affected an increment of bacteria populations which performed interrelated microbial metabolisms with methanogenic species in the MAD; consequently, a quantitative real-time PCR indicated greatly increased Methanosarcinales (acetate-utilizing methanogens) in the MAD, resulting in enhanced methane production.

  16. Mapping methane concentrations from a controlled release experiment using the next generation Airborne Visible/Infrared Imaging Spectrometer (AVIRISng)

    NASA Astrophysics Data System (ADS)

    Thorpe, A. K.; Frankenberg, C.; Roberts, D. A.; Aubrey, A. D.; Green, R. O.; Hulley, G. C.; Hook, S. J.

    2014-12-01

    Airborne imaging spectrometers like the next generation Airborne Visible/Infrared Imaging Spectrometer (AVIRISng) are well suited for monitoring local methane sources by covering large regions with the high spatial resolution necessary to resolve emissions. As part of a field campaign with controlled methane releases at the Rocky Mountain Oilfield Testing Center (RMOTC), a number of methane plumes were clearly visible at multiple flux rates and flight altitudes. Images of plumes appeared consistent with wind directions measured at ground stations and were present for fluxes as low as 14.2 cubic meters of methane per hour, equivalent to 0.09 kt/year. Direct comparison of results from AVIRISng and plume dispersion models is ongoing and will be used to assess the potential of constraining emission fluxes using AVIRISng. Methane plumes observed at RMOTC with the Hyperspectral Thermal Emission Spectrometer (HyTES) will also be presented. This controlled release experiment was used to determine the methane sensitivity of AVIRISng and inform sensor design for future imaging spectrometers that could constrain natural and anthropogenic methane emissions on local and regional scales. Imaging spectrometers permit direct attribution of emissions to individual point sources which is particularly useful given the large uncertainties associated with anthropogenic emissions, including industrial point source emissions and fugitive methane from the oil and gas industry. Figure caption: a. AVIRISng true color image indicating tube trailer (TT), meteorological tower (MT), and release point (RP). b. Prominent methane plume and measured enhancements for 70.8 cubic meters per hour methane flux is consistent with wind speed and direction (see arrow) measured by meteorological tower. A linear transect is shown in red and corresponds to enhancements shown in c. d. True color image showing release point (RP). e. Smaller methane plume for 14.2 cubic meters per hour flux. f. Methane

  17. Observations of the release of non-methane hydrocarbons from fractured shale.

    PubMed

    Sommariva, Roberto; Blake, Robert S; Cuss, Robert J; Cordell, Rebecca L; Harrington, Jon F; White, Iain R; Monks, Paul S

    2014-01-01

    The organic content of shale has become of commercial interest as a source of hydrocarbons, owing to the development of hydraulic fracturing ("fracking"). While the main focus is on the extraction of methane, shale also contains significant amounts of non-methane hydrocarbons (NMHCs). We describe the first real-time observations of the release of NMHCs from a fractured shale. Samples from the Bowland-Hodder formation (England) were analyzed under different conditions using mass spectrometry, with the objective of understanding the dynamic process of gas release upon fracturing of the shale. A wide range of NMHCs (alkanes, cycloalkanes, aromatics, and bicyclic hydrocarbons) are released at parts per million or parts per billion level with temperature- and humidity-dependent release rates, which can be rationalized in terms of the physicochemical characteristics of different hydrocarbon classes. Our results indicate that higher energy inputs (i.e., temperatures) significantly increase the amount of NMHCs released from shale, while humidity tends to suppress it; additionally, a large fraction of the gas is released within the first hour after the shale has been fractured. These findings suggest that other hydrocarbons of commercial interest may be extracted from shale and open the possibility to optimize the "fracking" process, improving gas yields and reducing environmental impacts.

  18. Observations of the release of non-methane hydrocarbons from fractured shale.

    PubMed

    Sommariva, Roberto; Blake, Robert S; Cuss, Robert J; Cordell, Rebecca L; Harrington, Jon F; White, Iain R; Monks, Paul S

    2014-01-01

    The organic content of shale has become of commercial interest as a source of hydrocarbons, owing to the development of hydraulic fracturing ("fracking"). While the main focus is on the extraction of methane, shale also contains significant amounts of non-methane hydrocarbons (NMHCs). We describe the first real-time observations of the release of NMHCs from a fractured shale. Samples from the Bowland-Hodder formation (England) were analyzed under different conditions using mass spectrometry, with the objective of understanding the dynamic process of gas release upon fracturing of the shale. A wide range of NMHCs (alkanes, cycloalkanes, aromatics, and bicyclic hydrocarbons) are released at parts per million or parts per billion level with temperature- and humidity-dependent release rates, which can be rationalized in terms of the physicochemical characteristics of different hydrocarbon classes. Our results indicate that higher energy inputs (i.e., temperatures) significantly increase the amount of NMHCs released from shale, while humidity tends to suppress it; additionally, a large fraction of the gas is released within the first hour after the shale has been fractured. These findings suggest that other hydrocarbons of commercial interest may be extracted from shale and open the possibility to optimize the "fracking" process, improving gas yields and reducing environmental impacts. PMID:24978099

  19. The role of subglacial microbes in carbon cycling and methane release in the past and present

    NASA Astrophysics Data System (ADS)

    Stibal, M.; Bech Mikkelsen, A.; Wadham, J. L.; Telling, J.; Hawkings, J.; Lis, G. P.; Lawson, E. C.; Hasan, F.; Dubnick, A.; Elberling, B.; Jacobsen, C. S.

    2012-12-01

    Subglacial environments are largely anoxic, contain organic carbon (OC) overridden by glacier ice during periods of advance, and harbour active microbial communities. This creates favourable conditions for a variety of microbial metabolisms, including methanogenesis. Yet little is known of the past and present potentials of subglacial microbes to take part in carbon cycling including methane production. Here we present data on the abundance and diversity of prokaryotic microbes, the activity of methanogenic archaea and the amount and character of OC in subglacial sediment and runoff from the Greenland Ice Sheet and compare them to those from other Arctic glaciers. The investigated Greenland subglacial sediment was of Holocene-aged soil origin and contained less bioavailable OC compared to subglacial sediments of lacustrine origin. The total microbial abundance and diversity was relatively low and the community was dominated by Proteobacteria. The identified clones were related to bacteria with both aerobic and anaerobic metabolisms, indicating the presence of both oxic and anoxic conditions in the sediments. Significant numbers of methanogens (up to 7×104 cells g-1) were detected and clones of Methanomicrobiales were identified in the clone library. Long lag periods (up to >200 days) were observed before significant methane concentrations (~0.2 pmol g-1 day-1 at 1C) were measured in long-term incubation experiments. These rates were lower than those measured in subglacial sediments containing more bioavailable OC. We use the measured rates of methanogenesis to estimate the potential for methane production beneath the Laurentide/Inuitian/Cordilleran and Fennoscandian Ice Sheets during a typical 85 ka Quaternary glacial/interglacial cycle. We predict that contrasting rates of methane production are likely to occur beneath glaciers that overran different types of substrate. Methane production from overridden soils such as those in Greenland is likely to be lower than

  20. Characterization of Methane Degradation and Methane-Degrading Microbes in Alaska Coastal Water

    SciTech Connect

    Kirchman, David L.

    2012-03-29

    The net flux of methane from methane hydrates and other sources to the atmosphere depends on methane degradation as well as methane production and release from geological sources. The goal of this project was to examine methane-degrading archaea and organic carbon oxidizing bacteria in methane-rich and methane-poor sediments of the Beaufort Sea, Alaska. The Beaufort Sea system was sampled as part of a multi-disciplinary expedition (Methane in the Arctic Shelf or MIDAS) in September 2009. Microbial communities were examined by quantitative PCR analyses of 16S rRNA genes and key methane degradation genes (pmoA and mcrA involved in aerobic and anaerobic methane degradation, respectively), tag pyrosequencing of 16S rRNA genes to determine the taxonomic make up of microbes in these sediments, and sequencing of all microbial genes (metagenomes ). The taxonomic and functional make-up of the microbial communities varied with methane concentrations, with some data suggesting higher abundances of potential methane-oxidizing archaea in methane-rich sediments. Sequence analysis of PCR amplicons revealed that most of the mcrA genes were from the ANME-2 group of methane oxidizers. According to metagenomic data, genes involved in methane degradation and other degradation pathways changed with sediment depth along with sulfate and methane concentrations. Most importantly, sulfate reduction genes decreased with depth while the anaerobic methane degradation gene (mcrA) increased along with methane concentrations. The number of potential methane degradation genes (mcrA) was low and inconsistent with other data indicating the large impact of methane on these sediments. The data can be reconciled if a small number of potential methane-oxidizing archaea mediates a large flux of carbon in these sediments. Our study is the first to report metagenomic data from sediments dominated by ANME-2 archaea and is one of the few to examine the entire microbial assemblage potentially involved in

  1. Demonstration of Technologies for Remote and in Situ Sensing of Atmospheric Methane Abundances - a Controlled Release Experiment

    NASA Astrophysics Data System (ADS)

    Aubrey, A. D.; Thorpe, A. K.; Christensen, L. E.; Dinardo, S.; Frankenberg, C.; Rahn, T. A.; Dubey, M.

    2013-12-01

    It is critical to constrain both natural and anthropogenic sources of methane to better predict the impact on global climate change. Critical technologies for this assessment include those that can detect methane point and concentrated diffuse sources over large spatial scales. Airborne spectrometers can potentially fill this gap for large scale remote sensing of methane while in situ sensors, both ground-based and mounted on aerial platforms, can monitor and quantify at small to medium spatial scales. The Jet Propulsion Laboratory (JPL) and collaborators recently conducted a field test located near Casper, WY, at the Rocky Mountain Oilfield Test Center (RMOTC). These tests were focused on demonstrating the performance of remote and in situ sensors for quantification of point-sourced methane. A series of three controlled release points were setup at RMOTC and over the course of six experiment days, the point source flux rates were varied from 50 LPM to 2400 LPM (liters per minute). During these releases, in situ sensors measured real-time methane concentration from field towers (downwind from the release point) and using a small Unmanned Aerial System (sUAS) to characterize spatiotemporal variability of the plume structure. Concurrent with these methane point source controlled releases, airborne sensor overflights were conducted using three aircraft. The NASA Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) participated with a payload consisting of a Fourier Transform Spectrometer (FTS) and an in situ methane sensor. Two imaging spectrometers provided assessment of optical and thermal infrared detection of methane plumes. The AVIRIS-next generation (AVIRIS-ng) sensor has been demonstrated for detection of atmospheric methane in the short wave infrared region, specifically using the absorption features at ~2.3 μm. Detection of methane in the thermal infrared region was evaluated by flying the Hyperspectral Thermal Emission Spectrometer (Hy

  2. Methane release from pingo-like features across the South Kara Sea shelf, an area of thawing offshore permafrost

    NASA Astrophysics Data System (ADS)

    Serov, Pavel; Portnov, Alexey; Mienert, Jurgen; Semenov, Peter; Ilatovskaya, Polina

    2015-08-01

    The Holocene marine transgression starting at ~19 ka flooded the Arctic shelves driving extensive thawing of terrestrial permafrost. It thereby promoted methanogenesis within sediments, the dissociation of gas hydrates, and the release of formerly trapped gas, with the accumulation in pressure of released methane eventually triggering blowouts through weakened zones in the overlying and thinned permafrost. Here we present a range of geophysical and chemical scenarios for the formation of pingo-like formations (PLFs) leading to potential blowouts. Specifically, we report on methane anomalies from the South Kara Sea shelf focusing on two PLFs imaged from high-resolution seismic records. A variety of geochemical methods are applied to study concentrations and types of gas, its character, and genesis. PLF 1 demonstrates ubiquitously low-methane concentrations (14.2-55.3 ppm) that are likely due to partly unfrozen sediments with an ice-saturated internal core reaching close to the seafloor. In contrast, PLF 2 reveals anomalously high-methane concentrations of >120,000 ppm where frozen sediments are completely absent. The methane in all recovered samples is of microbial and not of thermogenic origin from deep hydrocarbon sources. However, the relatively low organic matter content (0.52-1.69%) of seafloor sediments restricts extensive in situ methane production. As a consequence, we hypothesize that the high-methane concentrations at PLF 2 are due to microbial methane production and migration from a deeper source.

  3. Reconstruction of past methane availability in an Arctic Alaska wetland indicates climate influenced methane release during the past ~12,000 years

    USGS Publications Warehouse

    Wooller, Matthew J.; Pohlman, John W.; Gaglioti, Benjamin V.; Langdon, Peter; Jones, Miriam; Anthony, Katey M. Walter; Becker, Kevin W.; Hinrichs, Kai-Uwe; Elvert, Marcus

    2012-01-01

    Atmospheric contributions of methane from Arctic wetlands during the Holocene are dynamic and linked to climate oscillations. However, long-term records linking climate variability to methane availability in Arctic wetlands are lacking. We present a multi-proxy ~12,000 year paleoecological reconstruction of intermittent methane availability from a radiocarbon-dated sediment core (LQ-West) taken from a shallow tundra lake (Qalluuraq Lake) in Arctic Alaska. Specifically, stable carbon isotopic values of photosynthetic biomarkers and methane are utilized to estimate the proportional contribution of methane-derived carbon to lake-sediment-preserved benthic (chironomids) and pelagic (cladocerans) components over the last ~12,000 years. These results were compared to temperature, hydrologic, and habitat reconstructions from the same site using chironomid assemblage data, oxygen isotopes of chironomid head capsules, and radiocarbon ages of plant macrofossils. Cladoceran ephippia from ~4,000 cal year BP sediments have δ13C values that range from ~−39 to −31‰, suggesting peak methane carbon assimilation at that time. These low δ13C values coincide with an apparent decrease in effective moisture and development of a wetland that included Sphagnum subsecundum. Incorporation of methane-derived carbon by chironomids and cladocerans decreased from ~2,500 to 1,500 cal year BP, coinciding with a temperature decrease. Live-collected chironomids with a radiocarbon age of 1,640 cal year BP, and fossil chironomids from 1,500 cal year BP in the core illustrate that ‘old’ carbon has also contributed to the development of the aquatic ecosystem since ~1,500 cal year BP. The relatively low δ13C values of aquatic invertebrates (as low as −40.5‰) provide evidence of methane incorporation by lake invertebrates, and suggest intermittent climate-linked methane release from the lake throughout the Holocene.

  4. Dynamic simulations of potential methane release from East Siberian continental slope sediments

    NASA Astrophysics Data System (ADS)

    Stranne, C.; O'Regan, M.; Dickens, G. R.; Crill, P.; Miller, C.; Preto, P.; Jakobsson, M.

    2016-03-01

    Sediments deposited along continental margins of the Arctic Ocean presumably host large amounts of methane (CH4) in gas hydrates. Here we apply numerical simulations to assess the potential of gas hydrate dissociation and methane release from the East Siberian slope over the next 100 years. Simulations are based on a hypothesized bottom water warming of 3°C, and an assumed starting distribution of gas hydrate. The simulation results show that gas hydrate dissociation in these sediments is relatively slow, and that CH4 fluxes toward the seafloor are limited by low sediment permeability. The latter is true even when sediment fractures are permitted to form in response to overpressure in pore space. With an initial gas hydrate distribution dictated by present-day pressure and temperature conditions, nominally 0.35 Gt of CH4 are released from the East Siberian slope during the first 100 years of the simulation. However, this CH4 discharge becomes significantly smaller (˜0.05 Gt) if glacial sea level changes in the Arctic Ocean are considered. This is because a lower sea level during the last glacial maximum (LGM) must result in depleted gas hydrate abundance within the most sensitive region of the modern gas hydrate stability zone. Even if all released CH4 reached the atmosphere, the amount coming from East Siberian slopes would be trivial compared to present-day atmospheric CH4 inputs from other sources.

  5. Thermogenic Methane release as a Cause for the Long Duration of the PETM

    NASA Astrophysics Data System (ADS)

    Frieling, J.

    2015-12-01

    The Paleocene-Eocene Thermal Maximum (PETM; 55 Ma) was a ~170 kyr period of global warming associated with rapid and massive injections of 13C-depleted carbon into the ocean and atmosphere, reflected in sedimentary components as a negative carbon isotope excursion (CIE). Carbon cycle modelling has indicated that the shape of the CIE, which consists of a rapid onset, a prolonged phase of stable low δ13C and subsequent recovery, is best explained by an initial large pulse (3,000 Pg), followed by ~50 kyr of slow continuous release of 13C-depleted carbon (1,480 Pg). Suggested sources include submarine methane hydrates, terrigenous organic matter and thermogenic methane and CO2 from hydrothermal vent complexes in the Norwegian Sea. Here, we test the latter hypothesis by dating the active phase of a hydrothermal vent relative to the CIE through dinoflagellate cyst and carbon isotope stratigraphy. We find that activity in this vent system post-dates the onset of the PETM, excluding the possibility that it triggered the PETM. However, our record indicates the vent system was active during the ~60 kyr long "body" phase and thus represents the first actual proof of PETM carbon release from a particular reservoir. To test whether the pulsed release of carbon from these vent systems may have caused the long duration of the body of the PETM, we conduct a suite of experiments using a simple carbon cycle box model (LOSCAR). Our experiments indicate that pulsed carbon input from several vent systems over a prolonged period as suggested from the vent-literature (4-12 pulses within 60 kyr; total volume of 1,480 Pg) matches the CIE and deep ocean carbonate dissolution as recorded in sediment records. We therefore conclude that methane and CO2 from the Norwegian Sea vent complexes may have been the main source of carbon during the PETM, following its dramatic onset.

  6. Methane emission estimates using chamber and tracer release experiments for a municipal waste water treatment plant

    NASA Astrophysics Data System (ADS)

    Yver Kwok, C. E.; Müller, D.; Caldow, C.; Lebègue, B.; Mønster, J. G.; Rella, C. W.; Scheutz, C.; Schmidt, M.; Ramonet, M.; Warneke, T.; Broquet, G.; Ciais, P.

    2015-07-01

    This study presents two methods for estimating methane emissions from a waste water treatment plant (WWTP) along with results from a measurement campaign at a WWTP in Valence, France. These methods, chamber measurements and tracer release, rely on Fourier transform infrared spectroscopy and cavity ring-down spectroscopy instruments. We show that the tracer release method is suitable for quantifying facility- and some process-scale emissions, while the chamber measurements provide insight into individual process emissions. Uncertainties for the two methods are described and discussed. Applying the methods to CH4 emissions of the WWTP, we confirm that the open basins are not a major source of CH4 on the WWTP (about 10 % of the total emissions), but that the pretreatment and sludge treatment are the main emitters. Overall, the waste water treatment plant is representative of an average French WWTP.

  7. Surface release of methane on Mars: A model study in the framework of the future NOMAD mission

    NASA Astrophysics Data System (ADS)

    Viscardy, S.; Daerden, F.; Neary, L.; García Muñoz, A.; Vandaele, A.-C.

    2015-10-01

    Two connected tasks are tackled in this work in order to provide useful information for the highly sensitive NOMAD solar occultation channel [1] on the future ExoMars Trace Gas Orbiter mission. Firstly,an analysis of potential chemical by-products of methane is carried out using a 1D model for atmospheric chemistry. Secondly, we aim to investigate the time and space evolution of methane after different surface release scenarios using a 3D Global Circulation Model (GCM) for the atmosphere of Mars(GEM-Mars), focusing specifically on the vertical distribution of methane.

  8. Monitoring Production of Methane from Spills of Gasoline at UST Release Sites (Boston, MA)

    EPA Science Inventory

    Anaerobic biodegradation of the BTEX compounds can produce substantial concentrations of methane in ground water at gasoline spill sites. This methane can escape the ground water, move through the unsaturated zone and potentially produce explosive concentrations of methane in c...

  9. Methane emission estimates using chamber and tracer release experiments for a municipal waste water treatment plant

    NASA Astrophysics Data System (ADS)

    Yver-Kwok, C. E.; Müller, D.; Caldow, C.; Lebègue, B.; Mønster, J. G.; Rella, C. W.; Scheutz, C.; Schmidt, M.; Ramonet, M.; Warneke, T.; Broquet, G.; Ciais, P.

    2015-03-01

    This study presents two methods for estimating methane emissions from a waste water treatment plant (WWTP) along with results from a measurement campaign at a WWTP in Valence, France. These methods, chamber measurements and tracer release, rely on Fourier Transform Infrared (FTIR) spectroscopy and Cavity Ring Down Spectroscopy (CRDS) instruments. We show that the tracer release method is suitable to quantify facility- and some process-scale emissions, while the chamber measurements, provide insight into individual process emissions. Uncertainties for the two methods are described and discussed. Applying the methods to CH4 emissions of the WWTP, we confirm that the open basins are not a major source of CH4 on the WWTP (about 10% of the total emissions), but that the pretreatment and sludge treatment are the main emitters. Overall, the waste water treatment plant represents a small part (about 1.5%) of the methane emissions of the city of Valence and its surroundings, which is lower than the national inventories.

  10. Major implication of the littoral zone for methane release from boreal lakes

    NASA Astrophysics Data System (ADS)

    Juutinen, Sari; Alm, Jukka; Larmola, Tuula; Huttunen, Jari T.; Morero, Micaela; Martikainen, Pertti J.; Silvola, Jouko

    2003-12-01

    Transitions between aquatic and terrestrial environments can be recognized as biogeochemically active ecotones that support high CH4 release. We studied the links between littoral CH4 fluxes and aquatic vegetation, hydrologic conditions, and sediment quality, and integrated the CH4 fluxes into a whole-lake assessment. Methane fluxes were measured using a closed chamber method in the littoral and pelagic zones of three Finnish mid-boreal lakes from May to October. The cumulative CH4 fluxes were spatially integrated over the lake relative to the vegetation coverage in the littoral, and to depth zones in the pelagic regions. During the ice-free period, 66-77% of the CH4 was released from the littoral zone, and the mean CH4 effluxes from these lakes were 0.08-0.42 mol m-2 ice-free season-1. Littoral and pelagic productivity was reflected in CH4 release from the lakes. Our results show that estimates of lake CH4 release should include an assessment of the vegetated littoral zone.

  11. The Rate of Permafrost Carbon Release Under Aerobic and Anaerobic Decomposition

    NASA Astrophysics Data System (ADS)

    Lee, H.; Vogel, J. G.; Schuur, E. A.; Inglett, K. S.

    2008-12-01

    One of the ecological consequences caused by increased temperature in northern ecosystems is permafrost thawing. When ice-rich permafrost thaws, the land surface may develop lakes but could also drain, depending on the soil ice content and topographic position. More than 50% of terrestrial soil carbon is stored in the permafrost region, which may be subjected to faster decomposition due to permafrost thaw. As a result of thaw effects on hydrology, soil organic matter from permafrost may be deposited in an oxic or an anoxic environment after permafrost thaw. We tested how the oxygen status and soil substrate quality affect CO2 and CH4 emissions from permafrost soil by conducting laboratory soil incubation experiment. We measured CO2 emissions from aerobic incubations, and CO2 and CH4 from anaerobic incubations. Soil C to N ratios and enzyme activities (glucosidase, phosphatase, and aminopeptidase) were also analyzed to compare the organic matter quality of permafrost soils from different sites. The mass of C lost after 108 days of aerobic soil incubation ranged 0.06-7.98 mg C gdw-1 for mineral soil layers and 2.21-18.56 mg C gdw-1 for organic soil layers. In the anaerobic incubations, C loss in the form of CO2 emissions was 0.04-4.87 mg C gdw-1 while CH4 emissions were 0.00-0.23 mg C gdw- 1. The total C loss was about 3 times lower for the anaerobic soil incubations compared to the aerobic incubations. The carbon loss from CO2 emissions in aerobic incubation showed a linear relationship with C:N (R2=0.58). Overall, rates of C loss were 4-57 times higher in organic soils than mineral soils, which indicated the importance of substrate quality in the decomposition of permafrost carbon. The initial soil enzyme activities were higher in organic soils as compared to mineral soils for all the enzymes tested. Aminopeptidase activity was linearly correlated with C to N ratio (R2=0.78) and both phosphatase and glucosidase were exponentially correlated with %C (R2

  12. Measuring in situ dissolved methane concentrations in gas hydrate-rich systems, Part 1: Investigating the correlation between tectonics and methane release from sediments

    NASA Astrophysics Data System (ADS)

    Lapham, L.; Wilson, R. M.; Paull, C. K.; Chanton, J.; Riedel, M.

    2010-12-01

    In 2009, an area of extended methane venting at 1200 meters water depth was found with high resolution AUV bathymetry scans on the Northern Cascadia Margin that was previously unknown. When visited by ROV, we found seafloor cracks with active bubble streams and thin bacterial mats suggesting shallow gas and possible pore-fluid saturation. Upon coring into the cracks, a hard-substrate (carbonate or gas hydrate) was punctured and gas flows began. With these observations, we asked the question “is this shallow gas released from the seafloor from regional tectonic activity, and, if so, what is the temporal variability of such release events?” To answer this, we deployed a long term pore-water collection device at one of these gas crack sites, informally named “bubbly gulch”, for 9 months. The device is made up of 4 OsmoSamplers that were each plumbed to a port along a 1-meter probe tip using small diameter tubing. By osmosis, the samplers collected water samples slowly through the ports and maintained them within a 300 meter-long copper tubing coil. Because of the high methane concentrations anticipated, in situ pressures were maintained within the coil by the addition of a high pressure valve. Water samples were collected from the overlying water, at the sediment-water interface, and 6 and 10 cm into the sediments. Bottom water temperatures were also measured over the time series to determine pumping rates of the samplers but also to look for any temporal variability. In May 2010, the samplers were retrieved by ROV during efforts to install seafloor instruments for Neptune Canada. In a land-based lab, the coils were sub-sampled by cutting every 4 meters of tubing. With a pumping rate of 0.5 mL/day, this allowed a temporal resolution of 6 days. To date, one sampler coil has been sub-sampled and measured for methane concentrations and stable carbon isotopes. Preliminary results from this coil show pore-fluids nearly saturated with respect to methane, ~45 m

  13. [Effect of natural and hydrothermal synthetic goethite on the release of methane in the anaerobic decomposition process of organic matter].

    PubMed

    Yao, Dun-Fan; Chen, Tian-Hu; Wang, Jin; Zhou, Yue-Fei; Yue, Zheng-Bo

    2013-02-01

    The effects of natural goethite (NGt) and synthetic goethite (SGt) on the release of methane in the anaerobic biochemical system consisted of dissimilatory iron-reducing bacteria (DIRB) and methane-producing bacteria (MPB) were investigated through batch tests with sodium acetate as the carbon source. To explore the effects and mechanisms of both mineral materials on the release of methane in the anaerobic decomposition process of organic matter in the presence of DIRB, the main gas components and total organic carbon (TOC) , total inorganic carbon (TIC), and Fe2+ in the aqueous phase of the experimental process were determined and XRD analyses were conducted for the solid-phase product. Moreover, the minerals were analyzed by specific surface area (BET), X-ray diffraction (XRD), X-ray fluorescence (XRF). Modified Gompertz equation was used to fit the cumulative methane and carbon dioxide. Results showed that the maximum cumulative production of methane was brought forward by 60-78 days by the addition of goethite and CO2 was effectively reduced by 30% - 67% compared with the control samples. SGt was more effective than NGt in promoting the release of CH4 and reducing the CO, emission. Furthermore, the analysis of the solid product showed that the addition of goethite can fix part of CO2 by the formation of siderite.

  14. Sorption and Release of Organics by Primary, Anaerobic, and Aerobic Activated Sludge Mixed with Raw Municipal Wastewater

    PubMed Central

    Modin, Oskar; Saheb Alam, Soroush; Persson, Frank; Wilén, Britt-Marie

    2015-01-01

    New activated sludge processes that utilize sorption as a major mechanism for organics removal are being developed to maximize energy recovery from wastewater organics, or as enhanced primary treatment technologies. To model and optimize sorption-based activated sludge processes, further knowledge about sorption of organics onto sludge is needed. This study compared primary-, anaerobic-, and aerobic activated sludge as sorbents, determined sorption capacity and kinetics, and investigated some characteristics of the organics being sorbed. Batch sorption assays were carried out without aeration at a mixing velocity of 200 rpm. Only aerobic activated sludge showed net sorption of organics. Sorption of dissolved organics occurred by a near-instantaneous sorption event followed by a slower process that obeyed 1st order kinetics. Sorption of particulates also followed 1st order kinetics but there was no instantaneous sorption event; instead there was a release of particles upon mixing. The 5-min sorption capacity of activated sludge was 6.5±10.8 mg total organic carbon (TOC) per g volatile suspend solids (VSS) for particulate organics and 5.0±4.7 mgTOC/gVSS for dissolved organics. The observed instantaneous sorption appeared to be mainly due to organics larger than 20 kDa in size being sorbed, although molecules with a size of about 200 Da with strong UV absorbance at 215–230 nm were also rapidly removed. PMID:25768429

  15. Sorption and release of organics by primary, anaerobic, and aerobic activated sludge mixed with raw municipal wastewater.

    PubMed

    Modin, Oskar; Saheb Alam, Soroush; Persson, Frank; Wilén, Britt-Marie

    2015-01-01

    New activated sludge processes that utilize sorption as a major mechanism for organics removal are being developed to maximize energy recovery from wastewater organics, or as enhanced primary treatment technologies. To model and optimize sorption-based activated sludge processes, further knowledge about sorption of organics onto sludge is needed. This study compared primary-, anaerobic-, and aerobic activated sludge as sorbents, determined sorption capacity and kinetics, and investigated some characteristics of the organics being sorbed. Batch sorption assays were carried out without aeration at a mixing velocity of 200 rpm. Only aerobic activated sludge showed net sorption of organics. Sorption of dissolved organics occurred by a near-instantaneous sorption event followed by a slower process that obeyed 1st order kinetics. Sorption of particulates also followed 1st order kinetics but there was no instantaneous sorption event; instead there was a release of particles upon mixing. The 5-min sorption capacity of activated sludge was 6.5±10.8 mg total organic carbon (TOC) per g volatile suspend solids (VSS) for particulate organics and 5.0±4.7 mgTOC/gVSS for dissolved organics. The observed instantaneous sorption appeared to be mainly due to organics larger than 20 kDa in size being sorbed, although molecules with a size of about 200 Da with strong UV absorbance at 215-230 nm were also rapidly removed.

  16. Contrasting natural abundance radiocarbon signatures of methane released upon permafrost decomposition. (Invited)

    NASA Astrophysics Data System (ADS)

    Chanton, J.; Walter Anthony, K. M.; Prater, J.; Whiting, G.

    2009-12-01

    Thawing of permafrost releases frozen organic matter to microbial respiration and may vastly increase local carbon pools available for decomposition. Thermokarst landforms develop upon melting when soil collapses into the volume formerly occupied by ice. The degree of collapse depends on the amount of ground ice which had been present. With collapse, water-filled features may result, ranging from wetlands to lakes depending upon the degree of collapse. Water filled features then results in anaerobic conditions, and subsequent methane production and transport to the atmosphere. Two contrasting situations under which organic matter decomposition originating from thawed permafrost occurs are peatlands, represented by the discontinuous permafrost boreal peatlands of western Canada, and the Pleistocene-aged Yedoma Ice Complex’s organic-rich mineral soils of Siberia. The degree of collapse in these features varies by an order of magnitude, 1 m and 30 m respectively. In contrast to the over 40,000-year old radiocarbon-depleted methane generated in Siberian thermokarst lakes, the wetlands formed from permafrost collapse in western Canada generate more modern respiration products. Two peatland permafrost collapse features were investigated in detail. At site L, Δ14C values of respiration products were modern, and ranged from +110‰ to 0‰. In contrast to what would have been expected if the decay of thawed peat dominated microbial respiration, the most 14C enriched values were found near the collapse edge where recently thawed permafrost was being added. At site M, respiration products ranged from +100‰ to -400‰, and again the most enriched values were found associated with the collapsing edge. The Δ14C values of permafrost plateau peat ranged from -30‰ to -327‰ as a function of depth from 40 to 140 cm. These results indicate that in contrast to the Yedoma Siberian thermokarst features, organic inputs from permafrost degradation are not the dominant substrates

  17. Methane Release and Pingo-Like Feature Across the South kara Sea Shels, an Area of Thawing Offshore Permafrost

    NASA Astrophysics Data System (ADS)

    Serov, P.; Portnov, A.; Mienert, J.

    2015-12-01

    Thawing subsea permafrost controls methane release from the Russian Arctic shelf having a considerable impact on the climate-sensitive Arctic environment. Our recent studies revealed extensive gas release over an area of at least 7500 km2and presence of pingo-like features (PLFs), showing severe methane leakage, in the South Kara Sea in water depths >20m (Serov et al., 2015). Specifically, we detected shallow methane ebullition sites expressed in water column acoustic anomalies (gas flares and gas fronts) and areas of increased dissolved methane concentrations in bottom water, which might be sufficient sources of carbon for seawater-atmosphere exchange. A study of nature and source of leaking gas was focused on two PLFs, which are acoustically transparent circular mounds towering 5-9 m above the surrounding seafloor. One PLF (PLF 2) connects to biogenic gas from deeper sources, which is reflected in δ13CCH4 values ranging from -55,1‰ to -88,0‰ and δDCH4values varied from -175‰ to -246‰. Low organic matter content (0.52-1.69%) of seafloor sediments restricts extensive in situ methane production. The formation of PLF 2 is directly linked to the thawing of subsea permafrost and, possibly, decomposition of permafrost related gas hydrates. High accumulations of biogenic methane create the necessary forces to push the remaining frozen layers upwards and, therefore, form a topographic feature. We speculate that PLF 1, which shows ubiquitously low methane concentrations, is either a relict submerged terrestrial pingo, or a PLF lacking the necessary underlying methane accumulations. Our model of glacial-interglacial permafrost evolution supports a scenario in which subsea permafrost tapers seaward and pinches out at 20m isobaths, controlling observed methane emissions and development of PLFs. Serov. P., A. Portnov, J. Mienert, P. Semenov, and P. Ilatovskaya (2015), Methane release from pingo-like features across the South Kara Sea shelf, an area of thawnig

  18. Geochemical and geophysical evidence of methane release over the East Siberian Arctic Shelf

    NASA Astrophysics Data System (ADS)

    Shakhova, N.; Semiletov, I.; Leifer, I.; Salyuk, A.; Rekant, P.; Kosmach, D.

    2010-08-01

    The East Siberian Arctic Shelf (ESAS), which includes the Laptev Sea, the East Siberian Sea, and the Russian part of the Chukchi Sea, has not been considered to be a methane (CH4) source to hydrosphere or atmosphere because subsea permafrost, which underlies most of the ESAS, was believed, first, not to be conducive to methanogenesis and, second, to act as an impermeable lid, preventing CH4 escape through the seabed. Here recent observational data obtained during summer (2005-2006) and winter (2007) expeditions indicate the ubiquitous presence of elevated dissolved CH4 and an elevated atmospheric CH4 mixing ratio. The CH4 data were also analyzed together with high resolution seismic (HRS) data obtained by means of a "Sonic M-141" system consisting of a high-resolution profiler and side-scan sonar mounted in a towed fish during the Transdrift-X Expedition (2004) onboard the R/V Yakov Smirnitskiy. Results show anomalously high concentrations of dissolved CH4 (up to 5 μM) and an episodically (nongradually) increasing atmospheric mixing ratio of CH4 (up to 8.2 ppm) in some areas of the ESAS. A most likely source is year-round CH4 release through taliks (columns of thawed sediments within permafrost) from seabed CH4 reservoirs such as shallow hydrates and geological sources. Such releases occur not only within the areas underlain by fault zones but also outside of them. This points to permafrost's failure to further preserve CH4 deposits in the ESAS. The total amount of carbon preserved within the ESAS as organic matter and ready to release CH4 from seabed deposits is predicted to be ˜1400 Gt. Release of only a small fraction of this reservoir, which was sealed with impermeable permafrost for thousands of years, would significantly alter the annual CH4 budget and have global implications, because the shallowness of the ESAS allows the majority of CH4 to pass through the water column and escape to the atmosphere.

  19. Controls on methane released through ebullition in peatlands affected by permafrost degradation

    USGS Publications Warehouse

    Klapstein, Sara J.; Turetsky, Merritt R.; McGuire, Anthony; Harden, Jennifer W.; Czimczik, C.I.; Xu, Xiaomei; Chanton, J.P.; Waddington, James Michael

    2014-01-01

    Permafrost thaw in peat plateaus leads to the flooding of surface soils and the formation of collapse scar bogs, which have the potential to be large emitters of methane (CH4) from surface peat as well as deeper, previously frozen, permafrost carbon (C). We used a network of bubble traps, permanently installed 20 cm and 60 cm beneath the moss surface, to examine controls on ebullition from three collapse bogs in interior Alaska. Overall, ebullition was dominated by episodic events that were associated with changes in atmospheric pressure, and ebullition was mainly a surface process regulated by both seasonal ice dynamics and plant phenology. The majority (>90%) of ebullition occurred in surface peat layers, with little bubble production in deeper peat. During periods of peak plant biomass, bubbles contained acetate-derived CH4 dominated (>90%) by modern C fixed from the atmosphere following permafrost thaw. Post-senescence, the contribution of CH4 derived from thawing permafrost C was more variable and accounted for up to 22% (on average 7%), in the most recently thawed site. Thus, the formation of thermokarst features resulting from permafrost thaw in peatlands stimulates ebullition and CH4 release both by creating flooded surface conditions conducive to CH4 production and bubbling as well as by exposing thawing permafrost C to mineralization.

  20. Controls on methane released through ebullition in peatlands affected by permafrost degradation

    NASA Astrophysics Data System (ADS)

    Klapstein, Sara J.; Turetsky, Merritt R.; McGuire, A. David; Harden, Jennifer W.; Czimczik, Claudia I.; Xu, Xiaomei; Chanton, Jeffrey P.; Waddington, James M.

    2014-03-01

    Permafrost thaw in peat plateaus leads to the flooding of surface soils and the formation of collapse scar bogs, which have the potential to be large emitters of methane (CH4) from surface peat as well as deeper, previously frozen, permafrost carbon (C). We used a network of bubble traps, permanently installed 20 cm and 60 cm beneath the moss surface, to examine controls on ebullition from three collapse bogs in interior Alaska. Overall, ebullition was dominated by episodic events that were associated with changes in atmospheric pressure, and ebullition was mainly a surface process regulated by both seasonal ice dynamics and plant phenology. The majority (>90%) of ebullition occurred in surface peat layers, with little bubble production in deeper peat. During periods of peak plant biomass, bubbles contained acetate-derived CH4 dominated (>90%) by modern C fixed from the atmosphere following permafrost thaw. Post-senescence, the contribution of CH4 derived from thawing permafrost C was more variable and accounted for up to 22% (on average 7%), in the most recently thawed site. Thus, the formation of thermokarst features resulting from permafrost thaw in peatlands stimulates ebullition and CH4 release both by creating flooded surface conditions conducive to CH4 production and bubbling as well as by exposing thawing permafrost C to mineralization.

  1. Monitoring Production of Methane from Spills of Gasoline at UST Release Sites.

    EPA Science Inventory

    ORD-362 (Rev 06/10/05) (Webforms v2.4) Abstract: Anaerobic biodegradation of the BTEX compounds can produce substantial concentrations of methane in ground water at gasoline spill sites. This methane can escape the ground water, move through the unsaturated zone and potentiall...

  2. Release of Methane from Bering Sea Sediments During the Last Glacial Period

    SciTech Connect

    Mea Cook; Lloyd Keigwin

    2007-11-30

    Several lines of evidence suggest that during times of elevated methane flux the sulfate-methane transition zone (SMTZ) was positioned near the sediment-water interface. We studied two cores (from 700 m and 1457 m water depth) from the Umnak Plateau region. Anomalously low d13C and high d18O in benthic and planktonic foraminifera in these cores are the consequence of diagenetic overgrowths of authigenic carbonates. There are multiple layers of authigenic-carbonate-rich sediment in these cores, and the stable isotope compositions of the carbonates are consistent with those formed during anaerobic oxidation of methane (AOM). The carbonate-rich layers are associated with biomarkers produced by methane-oxidizing archaea, archaeol and glyceryl dibiphytanyl glyceryl tetraether (GDGT). The d13C of the archaeol and certain GDGTs are isotopically depleted. These carbonate- and AOM-biomarker-rich layers were emplaced in the SMTZ during episodes when there was a high flux of methane or methane-rich fluids upward in the sediment column. The sediment methane in the Umnak Plateau region appears to have been very dynamic during the glacial period, and interacted with the ocean-atmosphere system at millennial time scales. The upper-most carbonate-rich layers are in radiocarbon-dated sediment deposited during interstitials 2 and 3, 28-20 ka, and may be associated with the climate warming during this time.

  3. Degrading Sub-Sea Permafrost and Sedimentary Methane Release in the Southern Laptev Sea, Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Semiletov, I. P.; Shakhova, N. E.; Dudarev, O.; Tumskoy, V.; Kosmach, D.; Samarkin, V.; Joye, S. B.; Charkin, A.; Bukhanov, B.; Chuvilin, E.; Romanovskii, N.

    2012-12-01

    There remains substantial uncertainty regarding several aspects of CH4 release from the East Siberian Arctic Shelf (ESAS). To accurately predict future CH4 releases, we must understand the size of the reservoir (the amount of trapped CH4 that potentially could be released: hydrates, free gas, modern production), as well the processes that have kept it trapped and those that control its release. The main results to be considered here are related to permafrost stability and biological methane production: 1) Are changing ESAS thermal conditions causing the permafrost to thaw? 2) Do accelerated rates of permafrost degradation lead to development of taliks that act as CH4 vents to the overlying seawater and to the atmosphere? 3) Does biological CH4 production occur in permafrost and the overlying sediments? 4) How do CH4 oxidation rates compare to CH4 production rates? To address these questions, in April of 2011 and March-April of 2012 we drilled five boreholes (with depth up to 58 m below sediment surface) in the seasonally ice-covered eastern part of the shallow shelf, east off the Lena Delta, where specific geochemical and geophysical surveys were conducted in summer 2008, 2009, 2010, and 2011. The study area includes three main types of sub-sea degradation and talik formation: 1) fault zones, with significant upward heat flux, 2) areas impacted by a river, with downward heating effect, and 3) background areas (with more-or-less stable sub-sea permafrost). Therefore, we can extend the obtained results to the entire ESAS. The thermal regime at different sites differed significantly between sites. We did not encounter sub-sea permafrost at four sites from five. At site located east of the Sardahskaya channel of the Lena River mouth the temperature along the borehole was positive and increased from 0.5C in the sediment upper boundary layer to 2.7C at 15 m depth while the temperature at the freezing point deviated between -.08C and -1.3C, decreasing with depth, assuming

  4. Improving methane production and phosphorus release in anaerobic digestion of particulate saline sludge from a brackish aquaculture recirculation system.

    PubMed

    Zhang, Xuedong; Ferreira, Rui B; Hu, Jianmei; Spanjers, Henri; van Lier, Jules B

    2014-06-01

    In this study, batch tests were conducted to examine the effects of trehalose and glycine betaine as well as potassium on the specific methanogenic activity (SMA), acid and alkaline phosphatase activity of anaerobic biomass and phosphorus release in anaerobic digestion of saline sludge from a brackish recirculation aquaculture system. The results of ANOVA and Tukey's HSD (honestly significant difference) tests showed that glycine betaine and trehalose enhanced SMA of anaerobic biomass and reactive phosphorus release from the particulate waste. Moreover, SMA tests revealed that methanogenic sludge, which was long-term acclimatized to a salinity level of 17 g/L was severely affected by the increase in salinity to values exceeding 35 g/L. Addition of compatible solutes, such as glycine betaine and trehalose, could be used to enhance the specific methane production rate and phosphorus release in anaerobic digestion from particulate organic waste produced in marine or brackish aquaculture recirculation systems.

  5. Molecular analysis of deep-sea hydrothermal vent aerobic methanotrophs by targeting genes of 16S rRNA and particulate methane monooxygenase.

    PubMed

    Elsaied, Hosam Easa; Hayashi, Toru; Naganuma, Takeshi

    2004-01-01

    Molecular diversity of deep-sea hydrothermal vent aerobic methanotrophs was studied using both 16S ribosomalDNA and pmoA encoding the subunit A of particulate methane monooxygenase (pMOA). Hydrothermal vent plume and chimney samples were collected from back-arc vent at Mid-Okinawa Trough (MOT), Japan, and the Trans-Atlantic Geotraverse (TAG) site along Mid-Atlantic Ridge, respectively. The target genes were amplified by polymerase chain reaction from the bulk DNA using specific primers and cloned. Fifty clones from each clone library were directly sequenced. The 16S rDNA sequences were grouped into 3 operational taxonomic units (OTUs), 2 from MOT and 1 from TAG. Two OTUs (1 MOT and 1 TAG) were located within the branch of type I methanotrophic ?-Proteobacteria. Another MOT OTU formed a unique phylogenetic lineage related to type I methanotrophs. Direct sequencing of 50 clones each from the MOT and TAG samples yielded 17 and 4 operational pmoA units (OPUs), respectively. The phylogenetic tree based on the pMOA amino acid sequences deduced from OPUs formed diverse phylogenetic lineages within the branch of type I methanotrophs, except for the OPU MOT-pmoA-8 related to type X methanotrophs. The deduced pMOA topologies were similar to those of all known pMOA, which may suggest that the pmoA gene is conserved through evolution. Neither the 16S rDNA nor pmoA molecular analysis could detect type II methanotrophs, which suggests the absence of type II methanotrophs in the collected vent samples.

  6. Effects of long-term supplementation of chestnut and valonea extracts on methane release, digestibility and nitrogen excretion in sheep.

    PubMed

    Wischer, G; Greiling, A M; Boguhn, J; Steingass, H; Schollenberger, M; Hartung, K; Rodehutscord, M

    2014-06-01

    The long-term effects of adding chestnut (CHE; Castanea sativa) and valonea (VAL; Quercus valonea) tannin-rich extracts to sheep feed were investigated. In Experiment 1, sheep (65 kg BW) were fed 842 g/day of a ryegrass-based hay. The control-treated animals (CON) received 464 g/day of concentrate, and tannin-treated animals received the same amount of concentrate additionally containing 20 g of the respective tannin-rich extract. Hay and concentrates were offered together in one meal. After the onset of treatment, methane release was measured in respiration chambers for 23.5-h intervals (nine times) in a 190-days period. Faeces and urine were collected three times (including once before the onset of the tannin treatment) to assess digestibility and urinary excretion of purine derivatives. Based on the results obtained from Experiment 1, a second experiment (Experiment 2) was initiated, in which the daily tannin dosage was almost doubled (from 0.9 (Experiment 1) to 1.7 g/kg BW0.75). With the exception of the dosage and duration of the treatment (85 days), Experiment 2 followed the same design as Experiment 1, with the same measurements. In an attempt to compare in vitro and in vivo effects of tannin supplementation, the same substrates and tannin treatments were examined in the Hohenheim gas test. In vitro methane production was not significantly different between treatments. None of the tannin-rich extract doses induced a reduction in methane in the sheep experiments. On the 1st day of tannin feeding in both experiments, tannin inclusion tended to decrease methane release, but this trend disappeared by day 14 in both experiments. In balance period 3 of Experiment 1, lower dry matter and organic matter digestibility was noted for tannin treatments. The digestibility of CP, but not NDF or ADF, was reduced in both experiments. A significant shift in N excretion from urine to faeces was observed for both tannin-rich extracts in both experiments, particularly in

  7. Impacts of an ethanol-blended fuel release on groundwater and fate of produced methane: Simulation of field observations

    NASA Astrophysics Data System (ADS)

    Rasa, Ehsan; Bekins, Barbara A.; Mackay, Douglas M.; Sieyes, Nicholas R.; Wilson, John T.; Feris, Kevin P.; Wood, Isaac A.; Scow, Kate M.

    2013-08-01

    In a field experiment at Vandenberg Air Force Base (VAFB) designed to mimic the impact of a small-volume release of E10 (10% ethanol and 90% conventional gasoline), two plumes were created by injecting extracted groundwater spiked with benzene, toluene, and o-xylene, abbreviated BToX (no-ethanol lane) and BToX plus ethanol (with-ethanol lane) for 283 days. We developed a reactive transport model to understand processes controlling the fate of ethanol and BToX. The model was calibrated to the extensive field data set and accounted for concentrations of sulfate, iron, acetate, and methane along with iron-reducing bacteria, sulfate-reducing bacteria, fermentative bacteria, and methanogenic archaea. The benzene plume was about 4.5 times longer in the with-ethanol lane than in the no-ethanol lane. Matching this different behavior in the two lanes required inhibiting benzene degradation in the presence of ethanol. Inclusion of iron reduction with negligible growth of iron reducers was required to reproduce the observed constant degradation rate of benzene. Modeling suggested that vertical dispersion and diffusion of sulfate from an adjacent aquitard were important sources of sulfate in the aquifer. Matching of methane data required incorporating initial fermentation of ethanol to acetate, methane loss by outgassing, and methane oxidation coupled to sulfate and iron reduction. Simulation of microbial growth using dual Monod kinetics, and including inhibition by more favorable electron acceptors, generally resulted in reasonable yields for microbial growth of 0.01-0.05.

  8. Impacts of an ethanol-blended fuel release on groundwater and fate of produced methane: simulation of field observations

    USGS Publications Warehouse

    Rasa, Ehsan; Bekins, Barbara A.; Mackay, Douglas M.; de Sieyes, Nicholas R.; Wilson, John T.; Feris, Kevin P.; Wood, Isaac A.; Scow, Kate M.

    2013-01-01

    In a field experiment at Vandenberg Air Force Base (VAFB) designed to mimic the impact of a small-volume release of E10 (10% ethanol and 90% conventional gasoline), two plumes were created by injecting extracted groundwater spiked with benzene, toluene, and o-xylene, abbreviated BToX (No-Ethanol Lane) and BToX plus ethanol (With-Ethanol Lane) for 283 days. We developed a reactive transport model to understand processes controlling the fate of ethanol and BToX. The model was calibrated to the extensive field dataset and accounted for concentrations of sulfate, iron, acetate, and methane along with iron-reducing bacteria, sulfate-reducing bacteria, fermentative bacteria, and methanogenic archaea. The benzene plume was about 4.5 times longer in the With-Ethanol Lane than in the No-Ethanol Lane. Matching this different behavior in the two lanes required inhibiting benzene degradation in the presence of ethanol. Inclusion of iron reduction with negligible growth of iron-reducers was required to reproduce the observed constant degradation rate of benzene. Modeling suggested that vertical dispersion and diffusion of sulfate from an adjacent aquitard were important sources of sulfate in the aquifer. Matching of methane data required incorporating initial fermentation of ethanol to acetate, methane loss by outgassing, and methane oxidation coupled to sulfate and iron reduction. Simulation of microbial growth using dual Monod kinetics, and including inhibition by more favorable electron acceptors, generally resulted in reasonable yields for microbial growth of 0.01-0.05.

  9. Impacts of an ethanol-blended fuel release on groundwater and fate of produced methane: Simulation of field observations

    PubMed Central

    Bekins, Barbara A.; Mackay, Douglas M.; de Sieyes, Nicholas R.; Wilson, John T.; Feris, Kevin P.; Wood, Isaac A.; Scow, Kate M.

    2014-01-01

    In a field experiment at Vandenberg Air Force Base (VAFB) designed to mimic the impact of a small-volume release of E10 (10% ethanol and 90% conventional gasoline), two plumes were created by injecting extracted groundwater spiked with benzene, toluene, and o-xylene, abbreviated BToX (No-Ethanol Lane) and BToX plus ethanol (With-Ethanol Lane) for 283 days. We developed a reactive transport model to understand processes controlling the fate of ethanol and BToX. The model was calibrated to the extensive field dataset and accounted for concentrations of sulfate, iron, acetate, and methane along with iron-reducing bacteria, sulfate-reducing bacteria, fermentative bacteria, and methanogenic archaea. The benzene plume was about 4.5 times longer in the With-Ethanol Lane than in the No-Ethanol Lane. Matching this different behavior in the two lanes required inhibiting benzene degradation in the presence of ethanol. Inclusion of iron reduction with negligible growth of iron-reducers was required to reproduce the observed constant degradation rate of benzene. Modeling suggested that vertical dispersion and diffusion of sulfate from an adjacent aquitard were important sources of sulfate in the aquifer. Matching of methane data required incorporating initial fermentation of ethanol to acetate, methane loss by outgassing, and methane oxidation coupled to sulfate and iron reduction. Simulation of microbial growth using dual Monod kinetics, and including inhibition by more favorable electron acceptors, generally resulted in reasonable yields for microbial growth of 0.01-0.05. PMID:24678130

  10. Impacts of an ethanol-blended fuel release on groundwater and fate of produced methane: Simulation of field observations.

    PubMed

    Rasa, Ehsan; Bekins, Barbara A; Mackay, Douglas M; de Sieyes, Nicholas R; Wilson, John T; Feris, Kevin P; Wood, Isaac A; Scow, Kate M

    2013-08-01

    In a field experiment at Vandenberg Air Force Base (VAFB) designed to mimic the impact of a small-volume release of E10 (10% ethanol and 90% conventional gasoline), two plumes were created by injecting extracted groundwater spiked with benzene, toluene, and o-xylene, abbreviated BToX (No-Ethanol Lane) and BToX plus ethanol (With-Ethanol Lane) for 283 days. We developed a reactive transport model to understand processes controlling the fate of ethanol and BToX. The model was calibrated to the extensive field dataset and accounted for concentrations of sulfate, iron, acetate, and methane along with iron-reducing bacteria, sulfate-reducing bacteria, fermentative bacteria, and methanogenic archaea. The benzene plume was about 4.5 times longer in the With-Ethanol Lane than in the No-Ethanol Lane. Matching this different behavior in the two lanes required inhibiting benzene degradation in the presence of ethanol. Inclusion of iron reduction with negligible growth of iron-reducers was required to reproduce the observed constant degradation rate of benzene. Modeling suggested that vertical dispersion and diffusion of sulfate from an adjacent aquitard were important sources of sulfate in the aquifer. Matching of methane data required incorporating initial fermentation of ethanol to acetate, methane loss by outgassing, and methane oxidation coupled to sulfate and iron reduction. Simulation of microbial growth using dual Monod kinetics, and including inhibition by more favorable electron acceptors, generally resulted in reasonable yields for microbial growth of 0.01-0.05.

  11. The Carbon and Hydrogen Stable Isotope Composition of Methane Released from Natural Wetlands and Ruminants

    NASA Astrophysics Data System (ADS)

    Lansdown, John Malcolm

    The delta^{13} {rm C} of CH_4 emitted from the tropical Amazon river floodplain, temperate peat bogs in Washington and Minnesota, and the arctic Alaskan tundra was -59, -73, -66, and -65perthous, respectively. The deltaD of CH_4 from these sites was -294, -308, -339, and -391perthous, respectively, and a linear relationship was observed between the deltaD of CH_4 and soil water. A ^{13} C balance between CH_4, CO _2 and soil organic matter indicated a higher percentage of CH_4 production via methyl conversion at the Amazon floodplain than at the other wetland sites and that the anoxic CO _2 flux was 1.5 to 2.0 times the CH _4 flux. The ^{13} C balance provided greater constraint on the anoxic CO_2 flux than calculations based on soil water gradients. An in situ value of 0.774 for the hydrogen kinetic isotope effect during microbial CH _4 oxidation was estimated from the increase in the delta^{13} {rm C} and deltaD of CH_4 in flux samples from the Amazon site. The average delta^{13 }{rm C} of CH_4 released from an acidic peat bog in Washington state (pH = 3.5) was -73perthous, lower than previously measured at freshwater wetland sites. Soil incubations with ^{14 }C-labeled CO_2 and acetate substrates showed that CO_2 reduction accounted for essentially all methane production in the bog. An in situ value of 0.933 for the carbon kinetic isotope effect for CO_2 reduction was calculated from the delta^{13 }{rm C} of the CH_4 flux and soil water CO_2.. The delta^{13} {rm C} and deltaD of CH_4 emitted from ruminants was measured and averaged -63 and -404perthous, respectively. CO _2 reduction accounted for ~70% of rumen CH_4 production based on the change in the delta ^{13}{rm C} and deltaD of rumen CH_4 vs. time during normal conditions and after the addition of deuterated water to the rumen. These results contrast the dogma in the literature that CO_2 reduction accounts for essentially all CH _4 production in the rumen. A global budget for the deltaD of CH_4 was

  12. Fluxes and fate of dissolved methane released at the seafloor at the landward limit of the gas hydrate stability zone offshore western Svalbard

    NASA Astrophysics Data System (ADS)

    Graves, Carolyn A.; Steinle, Lea; Rehder, Gregor; Niemann, Helge; Connelly, Douglas P.; Lowry, David; Fisher, Rebecca E.; Stott, Andrew W.; Sahling, Heiko; James, Rachael H.

    2015-09-01

    Widespread seepage of methane from seafloor sediments offshore Svalbard close to the landward limit of the gas hydrate stability zone (GHSZ) may, in part, be driven by hydrate destabilization due to bottom water warming. To assess whether this methane reaches the atmosphere where it may contribute to further warming, we have undertaken comprehensive surveys of methane in seawater and air on the upper slope and shelf region. Near the GHSZ limit at ˜400 m water depth, methane concentrations are highest close to the seabed, reaching 825 nM. A simple box model of dissolved methane removal from bottom waters by horizontal and vertical mixing and microbially mediated oxidation indicates that ˜60% of methane released at the seafloor is oxidized at depth before it mixes with overlying surface waters. Deep waters are therefore not a significant source of methane to intermediate and surface waters; rather, relatively high methane concentrations in these waters (up to 50 nM) are attributed to isopycnal turbulent mixing with shelf waters. On the shelf, extensive seafloor seepage at <100 m water depth produces methane concentrations of up to 615 nM. The diffusive flux of methane from sea to air in the vicinity of the landward limit of the GHSZ is ˜4-20 μmol m-2 d-1, which is small relative to other Arctic sources. In support of this, analyses of mole fractions and the carbon isotope signature of atmospheric methane above the seeps do not indicate a significant local contribution from the seafloor source.

  13. Impacts of a massive release of methane and hydrogen sulfide on oxygen and ozone during the late Permian mass extinction

    NASA Astrophysics Data System (ADS)

    Kaiho, Kunio; Koga, Seizi

    2013-08-01

    The largest mass extinction of animals and plants in both the ocean and on land occurred in the late Permian (252 Ma), largely coinciding with the largest flood basalt volcanism event in Siberia and an oceanic anoxic/euxinic event. We investigated the impacts of a massive release of methane (CH4) from the Siberian igneous province and the ocean and/or hydrogen sulfide (H2S) from the euxinic ocean on oxygen and ozone using photochemical model calculations. Our calculations indicated that an approximate of 14% decrease in atmospheric O2 levels would have occurred in the case of a large combined CH4 and H2S flux to the atmosphere, whereas an approximate of 8 to 10% decrease would have occurred from the CH4 flux and oxidation of all H2S in the ocean. The slight decrease in atmospheric O2 levels may have contributed to the extinction event. We demonstrate for the first time that a massive release of CH4 from the Siberian igneous province and a coincident massive release of CH4 and H2S did not cause ozone collapse. A collapse of stratospheric ozone leading to an increase in UV is not supported by the maximum model input levels for CH4 and H2S. These conclusions on O2 and O3 are correspondent to every H2S release percentages from the ocean to the atmosphere.

  14. Methane release from the terrestrial ecosystems of greenhouse climates: Challenges and potential (Invited)

    NASA Astrophysics Data System (ADS)

    Pancost, R. D.; Collinson, M.; Evershed, R. P.; Bingham, E.; Talbot, H.; Weijers, J.; Wilde, V.; Riegel, W.

    2009-12-01

    Recent circulation and geochemical modelling suggests that atmospheric methane could have been an important driver of global temperatures during past greenhouse climates. Such conclusions are largely based on our understanding of modern wetland biogeochemistry, including the impact of hydrology, temperature and primary photosynthetic production on rates of methanogenesis. However, validation of these parameters, and of course direct validation of past wetland methane fluxes or atmospheric methane concentrations, are either challenging or currently not possible. Here, we discuss prospects for using lipid biomarkers (and complementary approaches) in lignites to interrogate methane cycling and the environmental conditions that drive it. Potential new proxies include the MBT/CBT index from which mean air temperatures can be reconstructed, allowing direct validation that temperate and polar wetlands experienced greater temperatures during greenhouse times. Second, compound-specific dD values, when coupled to reconstructed vegetation and charcoal records, can provide expanded insight into past wetland hydrology. And finally, the concentrations, distributions and carbon isotopic compositions of archaeal ether lipids and bacterial hopanoids provide direct evidence for increased methanogen or methanotroph biomasss, respectively. This final proxy is based directly on our ongoing investigations of a half dozen Holocene and modern peat deposits; in these, archaeol concentrations range from 0 to 30 ug per g of peat, and putative methanotroph hopanoids represent less than 3% if the total bacteriohopanoids. We illustrate the potential for such an integrated approach using the SE England Cobham lignite deposited during the Palaeocene Eocene Thermal Maximum (PETM). During the PETM, an increase in precipitation and/or runoff and a cessation of fires (collectively revealed by lithologic and vegetation change) apparently drove a dramatic increase in methane production as revealed by a

  15. Seafloor methane: Atlantic bubble bath

    NASA Astrophysics Data System (ADS)

    Kessler, John

    2014-09-01

    The release of large quantities of methane from ocean sediments might affect global climate change. The discovery of expansive methane seeps along the US Atlantic margin provides an ideal test bed for such a marine methane-climate connection.

  16. Evidence for large methane releases to the atmosphere from deep-sea gas-hydrate dissociation during the last glacial episode

    PubMed Central

    de Garidel-Thoron, Thibault; Beaufort, Luc; Bassinot, Franck; Henry, Pierre

    2004-01-01

    Past atmospheric methane-concentration oscillations recorded in polar ice cores vary together with rapid global climatic changes during the last glacial episode. In the “clathrate gun hypothesis,” massive releases of deep-sea methane from marine gas-hydrate dissociation led to these well known, global, abrupt warmings in the past. If evidence for such releases in the water column exists, however, the mechanism and eventual transfer to the atmosphere has not yet been documented clearly. Here we describe a high-resolution marine-sediment record of stable carbon isotopic changes from the Papua Gulf, off Papua New Guinea, which exhibits two extremely depleted excursions (down to -9‰) at ≈39,000 and ≈55,000 years. Morphological, isotopic, and trace metal evidence dismisses authigenic calcite as the main source of depleted carbon. Massive methane release associated with deep-sea gas-hydrate dissociation is the most likely cause for such large depletions of δ13C. The absence of a δ13C gradient in the water column during these events implies that the methane rose through the entire water column, reaching the sea–air interface and thus the atmosphere. Foraminiferal δ18O composition suggests that the rise of the methane in the water column created an upwelling flow. These inferred emission events suggest that during the last glacial episode, this process was likely widespread, including tropical regions. Thus, the release of methane from the ocean floor into the atmosphere cannot be dismissed as a strong positive feedback in climate dynamics processes. PMID:15197255

  17. Non-linear dynamics of stable carbon and hydrogen isotope signatures based on a biological kinetic model of aerobic enzymatic methane oxidation.

    PubMed

    Vavilin, Vasily A; Rytov, Sergey V; Shim, Natalia; Vogt, Carsten

    2016-06-01

    The non-linear dynamics of stable carbon and hydrogen isotope signatures during methane oxidation by the methanotrophic bacteria Methylosinus sporium strain 5 (NCIMB 11126) and Methylocaldum gracile strain 14 L (NCIMB 11912) under copper-rich (8.9 µM Cu(2+)), copper-limited (0.3 µM Cu(2+)) or copper-regular (1.1 µM Cu(2+)) conditions has been described mathematically. The model was calibrated by experimental data of methane quantities and carbon and hydrogen isotope signatures of methane measured previously in laboratory microcosms reported by Feisthauer et al. [ 1 ] M. gracile initially oxidizes methane by a particulate methane monooxygenase and assimilates formaldehyde via the ribulose monophosphate pathway, whereas M. sporium expresses a soluble methane monooxygenase under copper-limited conditions and uses the serine pathway for carbon assimilation. The model shows that during methane solubilization dominant carbon and hydrogen isotope fractionation occurs. An increase of biomass due to growth of methanotrophs causes an increase of particulate or soluble monooxygenase that, in turn, decreases soluble methane concentration intensifying methane solubilization. The specific maximum rate of methane oxidation υm was proved to be equal to 4.0 and 1.3 mM mM(-1) h(-1) for M. sporium under copper-rich and copper-limited conditions, respectively, and 0.5 mM mM(-1) h(-1) for M. gracile. The model shows that methane oxidation cannot be described by traditional first-order kinetics. The kinetic isotope fractionation ceases when methane concentrations decrease close to the threshold value. Applicability of the non-linear model was confirmed by dynamics of carbon isotope signature for carbon dioxide that was depleted and later enriched in (13)C. Contrasting to the common Rayleigh linear graph, the dynamic curves allow identifying inappropriate isotope data due to inaccurate substrate concentration analyses. The non-linear model pretty adequately described experimental

  18. Extensive release of methane from Arctic seabed west of Svalbard during summer 2014 does not influence the atmosphere

    NASA Astrophysics Data System (ADS)

    Myhre, C. Lund; Ferré, B.; Platt, S. M.; Silyakova, A.; Hermansen, O.; Allen, G.; Pisso, I.; Schmidbauer, N.; Stohl, A.; Pitt, J.; Jansson, P.; Greinert, J.; Percival, C.; Fjaeraa, A. M.; O'Shea, S. J.; Gallagher, M.; Le Breton, M.; Bower, K. N.; Bauguitte, S. J. B.; Dalsøren, S.; Vadakkepuliyambatta, S.; Fisher, R. E.; Nisbet, E. G.; Lowry, D.; Myhre, G.; Pyle, J. A.; Cain, M.; Mienert, J.

    2016-05-01

    We find that summer methane (CH4) release from seabed sediments west of Svalbard substantially increases CH4 concentrations in the ocean but has limited influence on the atmospheric CH4 levels. Our conclusion stems from complementary measurements at the seafloor, in the ocean, and in the atmosphere from land-based, ship and aircraft platforms during a summer campaign in 2014. We detected high concentrations of dissolved CH4 in the ocean above the seafloor with a sharp decrease above the pycnocline. Model approaches taking potential CH4 emissions from both dissolved and bubble-released CH4 from a larger region into account reveal a maximum flux compatible with the observed atmospheric CH4 mixing ratios of 2.4-3.8 nmol m-2 s-1. This is too low to have an impact on the atmospheric summer CH4 budget in the year 2014. Long-term ocean observatories may shed light on the complex variations of Arctic CH4 cycles throughout the year.

  19. Methane flux in potential hydrate-bearing sediments offshore southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, Nai-Chen; Yang, Tsanyao Frank; Chuang, Pei-Chuan; Hong, Wei-Li; Chen, Hsuan-Wen; Lin, Saulwood; Lin, Li-Hung; Mastumoto, Ryo; Hiruta, Akihiro; Sun, Chih-Hsien; Wang, Pei-Ling; Yang, Tau; Jiang, Shao-yong; Wang, Yun-shuen; Chung, San-Hsiung; Chen, Cheng-Hong

    2016-04-01

    Methane in interstitial water of hydrate-bearing marine sediments ascends with buoyant fluids and is discharged into seawater, exerting profound impacts on ocean biogeochemistry and greenhouse effects. Quantifying the exact magnitude of methane transport across different geochemical transitions in different geological settings would provide bases to better constrain global methane discharge to seawater and to assess physio-chemical contexts imposed on microbial methane production and consumption and carbon sequestration in marine environments. Using sediments collected from different geological settings offshore southwestern Taiwan through decadal exploration on gas hydrates, this study analyzed gas and aqueous geochemistry and calculated methane fluxes across different compartments. Three geochemical transitions, including sulfate-methane transition zone (SMTZ), shallow sediments, and sediment-seawater interface were specifically focused for the flux calculation. The results combined with previous published data showed that methane fluxes at three interfaces of 2.71×10-3 to 3.52×10-1, 5.28×10-7 to 1.08×100, and 1.34×10-6 to 3.17×100 mmol m-2 d-1, respectively. The ranges of fluxes suggest that more than 90 % of methane originating from depth was consumed by anaerobic methanotrophy at the SMTZ, and further >90% of the remnant methane was removed by aerobic methanotrophy prior to reaching the sediment-seawater interface. Exceptions are sites at cold seeps where the percentage of methane released into seawater can reach more than 80% of methane at depth. Most sites with such high methane fluxes are located at active margin where thrusts and diapirism are well developed. Carbon mass balance method was applied for the calculation of anaerobic oxidation of methane (AOM) and organotrophic sulfate reduction rates at SMTZ. Results indicated that AOM rates were comparable with fluxes deduced from concentration gradients for most sites. At least 60% of sulfate

  20. Methane emissions and contaminant degradation rates at sites affected by accidental releases of denatured fuel-grade ethanol.

    PubMed

    Sihota, Natasha J; Mayer, K Ulrich; Toso, Mark A; Atwater, Joel F

    2013-08-01

    The recent increase in the use of denatured fuel-grade ethanol (DFE) has enhanced the probability of its environmental release. Due to the highly labile nature of ethanol (EtOH), it is expected to rapidly biodegrade, increasing the potential for inducing methanogenic conditions in the subsurface. As environmental releases of DFE can be expected to occur at the ground surface or in the vadose zone (e.g., due to surficial spills from rail lines or tanker trucks and leaking underground storage tanks), the potential for methane (CH4) generation at DFE spill sites requires evaluation. An assessment is needed because high CH4 generation rates may lead to CH4 fluxes towards the ground surface, which is of particular concern if spills are located close to human habitation-related to concerns of soil vapor intrusion (SVI). This work demonstrates, for the first time, the measurement of surficial gas release rates at large volume DFE spill sites. Two study sites, near Cambria and Balaton, in MN are investigated. Total carbon emissions at the ground surface (summing carbon dioxide (CO2) and CH4 emissions) are used to quantify depth-integrated DFE degradation rates. Results from both sites demonstrate that substantial CO2 and CH4 emissions do occur-even years after a spill. However, large total carbon fluxes, and CH4 emissions in particular, were restricted to a localized area within the DFE source zone. At the Balaton site, estimates of total DFE carbon losses in the source zone ranged between 5 and 174 μmol m(-2) s(-1), and CH4 effluxes ranged between non-detect and 9 μmol m(-2) s(-1). At the Cambria site estimates of total DFE carbon losses in the source zone ranged between 8 and 500 μmol m(-2) s(-1), and CH4 effluxes ranged between non-detect and 393 μmol m(-2) s(-1). Substantial CH4 accumulation, coupled with oxygen (O2) depletion, measured in samples collected from custom-designed gas collection chambers at the Cambria site suggests that the development of explosion

  1. Methane emissions and contaminant degradation rates at sites affected by accidental releases of denatured fuel-grade ethanol

    NASA Astrophysics Data System (ADS)

    Sihota, Natasha J.; Mayer, K. Ulrich; Toso, Mark A.; Atwater, Joel F.

    2013-08-01

    The recent increase in the use of denatured fuel-grade ethanol (DFE) has enhanced the probability of its environmental release. Due to the highly labile nature of ethanol (EtOH), it is expected to rapidly biodegrade, increasing the potential for inducing methanogenic conditions in the subsurface. As environmental releases of DFE can be expected to occur at the ground surface or in the vadose zone (e.g., due to surficial spills from rail lines or tanker trucks and leaking underground storage tanks), the potential for methane (CH4) generation at DFE spill sites requires evaluation. An assessment is needed because high CH4 generation rates may lead to CH4 fluxes towards the ground surface, which is of particular concern if spills are located close to human habitation—related to concerns of soil vapor intrusion (SVI). This work demonstrates, for the first time, the measurement of surficial gas release rates at large volume DFE spill sites. Two study sites, near Cambria and Balaton, in MN are investigated. Total carbon emissions at the ground surface (summing carbon dioxide (CO2) and CH4 emissions) are used to quantify depth-integrated DFE degradation rates. Results from both sites demonstrate that substantial CO2 and CH4 emissions do occur—even years after a spill. However, large total carbon fluxes, and CH4 emissions in particular, were restricted to a localized area within the DFE source zone. At the Balaton site, estimates of total DFE carbon losses in the source zone ranged between 5 and 174 μmol m- 2 s- 1, and CH4 effluxes ranged between non-detect and 9 μmol m- 2 s- 1. At the Cambria site estimates of total DFE carbon losses in the source zone ranged between 8 and 500 μmol m- 2 s- 1, and CH4 effluxes ranged between non-detect and 393 μmol m- 2 s- 1. Substantial CH4 accumulation, coupled with oxygen (O2) depletion, measured in samples collected from custom-designed gas collection chambers at the Cambria site suggests that the development of explosion or

  2. Methane emissions and contaminant degradation rates at sites affected by accidental releases of denatured fuel-grade ethanol.

    PubMed

    Sihota, Natasha J; Mayer, K Ulrich; Toso, Mark A; Atwater, Joel F

    2013-08-01

    The recent increase in the use of denatured fuel-grade ethanol (DFE) has enhanced the probability of its environmental release. Due to the highly labile nature of ethanol (EtOH), it is expected to rapidly biodegrade, increasing the potential for inducing methanogenic conditions in the subsurface. As environmental releases of DFE can be expected to occur at the ground surface or in the vadose zone (e.g., due to surficial spills from rail lines or tanker trucks and leaking underground storage tanks), the potential for methane (CH4) generation at DFE spill sites requires evaluation. An assessment is needed because high CH4 generation rates may lead to CH4 fluxes towards the ground surface, which is of particular concern if spills are located close to human habitation-related to concerns of soil vapor intrusion (SVI). This work demonstrates, for the first time, the measurement of surficial gas release rates at large volume DFE spill sites. Two study sites, near Cambria and Balaton, in MN are investigated. Total carbon emissions at the ground surface (summing carbon dioxide (CO2) and CH4 emissions) are used to quantify depth-integrated DFE degradation rates. Results from both sites demonstrate that substantial CO2 and CH4 emissions do occur-even years after a spill. However, large total carbon fluxes, and CH4 emissions in particular, were restricted to a localized area within the DFE source zone. At the Balaton site, estimates of total DFE carbon losses in the source zone ranged between 5 and 174 μmol m(-2) s(-1), and CH4 effluxes ranged between non-detect and 9 μmol m(-2) s(-1). At the Cambria site estimates of total DFE carbon losses in the source zone ranged between 8 and 500 μmol m(-2) s(-1), and CH4 effluxes ranged between non-detect and 393 μmol m(-2) s(-1). Substantial CH4 accumulation, coupled with oxygen (O2) depletion, measured in samples collected from custom-designed gas collection chambers at the Cambria site suggests that the development of explosion

  3. Anaerobic methane oxidation coupled to denitrification is the dominant methane sink in a deep lake

    PubMed Central

    Deutzmann, Joerg S.; Stief, Peter; Brandes, Josephin; Schink, Bernhard

    2014-01-01

    Anaerobic methane oxidation coupled to denitrification, also known as “nitrate/nitrite-dependent anaerobic methane oxidation” (n-damo), was discovered in 2006. Since then, only a few studies have identified this process and the associated microorganisms in natural environments. In aquatic sediments, the close proximity of oxygen- and nitrate-consumption zones can mask n-damo as aerobic methane oxidation. We therefore investigated the vertical distribution and the abundance of denitrifying methanotrophs related to Candidatus Methylomirabilis oxyfera with cultivation-independent molecular techniques in the sediments of Lake Constance. Additionally, the vertical distribution of methane oxidation and nitrate consumption zones was inferred from high-resolution microsensor profiles in undisturbed sediment cores. M. oxyfera-like bacteria were virtually absent at shallow-water sites (littoral sediment) and were very abundant at deep-water sites (profundal sediment). In profundal sediment, the vertical distribution of M. oxyfera-like bacteria showed a distinct peak in anoxic layers that coincided with the zone of methane oxidation and nitrate consumption, a strong indication for n-damo carried out by M. oxyfera-like bacteria. Both potential n-damo rates calculated from cell densities (660–4,890 µmol CH4⋅m−2⋅d−1) and actual rates calculated from microsensor profiles (31–437 µmol CH4⋅m−2⋅d−1) were sufficiently high to prevent methane release from profundal sediment solely by this process. Additionally, when nitrate was added to sediment cores exposed to anoxic conditions, the n-damo zone reestablished well below the sediment surface, completely preventing methane release from the sediment. We conclude that the previously overlooked n-damo process can be the major methane sink in stable freshwater environments if nitrate is available in anoxic zones. PMID:25472842

  4. [Impact of Salinity on Leachate Treatment and N2O Releases from Semi-aerobic Aged-refuse Bioreactor].

    PubMed

    Li, Wei-hua; Sun, Ying-jie; Liu, Zi-liang; Ma, Qiang; Yang, Qiang

    2016-02-15

    Semi-aerobic Aged-refuse Bioreactor (SAARB) has a good effect on nitrogen removal in leachate, but a strong greenhouse gas (N2O) was generated during the nitrification and denitrification process. The effect of salinity (7-30 g x L(-1)) on the leachate treatment and the N2O production from SAARB system was investigated. Experimental results showed that salinity ranging from 7 to 30 g x L(-1) had no significant effect on COD removal, and the removal efficiency was always more than 85%. On the contrary, it had a strong influence on the removal of nitrogen. The removal efficiencies of NH4+ -N and TN decreased from 98. 23% and 91.48% at 7 g x L(-1) salt to 31.75% and 34.24% at 30 g x L(-1) salt, respectively. Moreover, there was significant nitrite (NO2- -N) accumulation in the presence of 30 g x L(-1) salt. Meanwhile, salinity had different inhibition strength on nitrification and denitrification bacteria, and the order of inhibition strength was as follows: nitrification bacteria > denitrification bacteria. In addition, the N2O production increased with salinity concentration, and the highest N2O accumulation (1397 microg +/- 369.88 microg) was observed with addition of 30 g x L(-1) salt, which accounted for 8.87%o of the total nitrogen removal. Meanwhile, it was 6-117 times higher in the presence of 30 g x L(-1) salt than that in low salinity conditions (7-20 g x L(-1)). And the peak time of the N2O production showed a delayed trend. These results indicated that salinity recirculation in leachate had a negative effect on the nitrogen removal and N2O production. Overall, salinity seemed to be a key parameter during leachate recirculation. PMID:27363172

  5. [Impact of Salinity on Leachate Treatment and N2O Releases from Semi-aerobic Aged-refuse Bioreactor].

    PubMed

    Li, Wei-hua; Sun, Ying-jie; Liu, Zi-liang; Ma, Qiang; Yang, Qiang

    2016-02-15

    Semi-aerobic Aged-refuse Bioreactor (SAARB) has a good effect on nitrogen removal in leachate, but a strong greenhouse gas (N2O) was generated during the nitrification and denitrification process. The effect of salinity (7-30 g x L(-1)) on the leachate treatment and the N2O production from SAARB system was investigated. Experimental results showed that salinity ranging from 7 to 30 g x L(-1) had no significant effect on COD removal, and the removal efficiency was always more than 85%. On the contrary, it had a strong influence on the removal of nitrogen. The removal efficiencies of NH4+ -N and TN decreased from 98. 23% and 91.48% at 7 g x L(-1) salt to 31.75% and 34.24% at 30 g x L(-1) salt, respectively. Moreover, there was significant nitrite (NO2- -N) accumulation in the presence of 30 g x L(-1) salt. Meanwhile, salinity had different inhibition strength on nitrification and denitrification bacteria, and the order of inhibition strength was as follows: nitrification bacteria > denitrification bacteria. In addition, the N2O production increased with salinity concentration, and the highest N2O accumulation (1397 microg +/- 369.88 microg) was observed with addition of 30 g x L(-1) salt, which accounted for 8.87%o of the total nitrogen removal. Meanwhile, it was 6-117 times higher in the presence of 30 g x L(-1) salt than that in low salinity conditions (7-20 g x L(-1)). And the peak time of the N2O production showed a delayed trend. These results indicated that salinity recirculation in leachate had a negative effect on the nitrogen removal and N2O production. Overall, salinity seemed to be a key parameter during leachate recirculation.

  6. Estimate of methane release from temperate natural wetlands using ENVISAT/SCIAMACHY data in China

    NASA Astrophysics Data System (ADS)

    Zhang, Xiuying; Jiang, Hong; Lu, Xuehe; Cheng, Miaomiao; Zhang, Xiaomin; Li, Xinhui; Zhang, Linjing

    2013-04-01

    Since wetlands are the largest natural sources of atmospheric CH4, it is important to estimate the CH4 emissions from natural wetlands at regional scale and over a long time period. The annual CH4 efflux from temperate natural wetlands excluding water surface in China was estimated, based on atmospheric CH4 concentrations from SCIAMACHY/ENVISAT. The atmospheric CH4 concentrations showed obvious seasonal cycles, and CH4 emission from natural wetlands dominated the temporal variations of CH4 concentrations in north China, accounting for about 67.94% of the variations of CH4 concentrations. The chemical transport model, MOZART-4 (Model for Ozone and Related Chemical Tracers, version 4), was used to simulate the space-borne CH4 column concentrations to the surface level, and then the relationship between surface concentrations and emissions of CH4 from natural wetlands was simulated by a linear regression model. The results showed that the estimated annual budget of CH4 emission from natural wetlands in the temperate zone of China was about 4.76 Tg CH4, which was within the range of 2.38-4.91 Tg CH4 estimated by spatial distribution of wetland and the published CH4 release fluxes during the 1990s-2000s. This demonstrated that the method of using space-borne CH4 column concentrations to estimate CH4 emissions from natural wetlands was reliable.

  7. Enhanced U(VI) release from autunite mineral by aerobic Arthrobacter sp. in the presence of aqueous bicarbonate

    SciTech Connect

    Katsenovich, Yelena P.; Carvajal, Denny A.; Wellman, Dawn M.; Lagos, Leonel E.

    2012-05-01

    The bacterial effect on U(VI) release from the autunite mineral (Ca[(UO2)(PO4)]2•3H2O) was investigated to provide a more comprehensive understanding of the important microbiological processes affecting autunite stability within subsurface bicarbonate-bearing environments. Experiments were performed in a culture of the Arthrobacter oxydans G975 strain, herein referred to as G975, a soil bacterium previously isolated from Hanford Site soil. 91 mg of autunite powder and 50 mL of phosphorous-limiting sterile media were amended with bicarbonate (ranging between 1 and 10 mM) in glass reactor bottles and inoculated with the G975 strain after the dissolution of autunite was at steady state. SEM observations indicated that G975 formed a biofilm on the autunite surface and penetrated the mineral cleavages. The mineral surface colonization by bacteria tended to increase concomitantly with bicarbonate concentrations. Additionally, a sterile culture-ware with inserts was used in non-contact dissolution experiments where autunite and bacteria cells were kept separately. The data suggest that G975 bacteria is able to enhance the release of U(VI) from autunite without direct contact with the mineral. In the presence of bicarbonate, the damage to bacterial cells caused by U(VI) toxicity was reduced, yielding similar values for total organic carbon (TOC) degradation and cell density compared to U(VI)-free controls. The presence of active bacterial cells greatly enhanced the release of U(VI) from autunite in bicarbonate-amended media.

  8. Investigating the Hydro-geochemical Impact of Fugitive Methane on Groundwater: The Borden Aquifer Controlled Release Study

    NASA Astrophysics Data System (ADS)

    Cahill, A. G.; Parker, B. L.; Cherry, J. A.; Mayer, K. U.; Mayer, B.; Ryan, C.

    2015-12-01

    Shale gas development by hydraulic fracturing is believed by many to have the potential to transform the world's energy economy. The propensity of this technique to cause significant environmental impact is strongly contested and lacks evidence. Fugitive methane (CH4), potentially mobilized during well drilling, the complex extraction process and/or leaking well seals over time is arguably the greatest concern. Advanced understanding of CH4 mobility and fate in the subsurface is needed in order to assess risks, design suitable monitoring systems and gain public trust. Currently knowledge on subsurface CH4 mobilization and migration at scales relevant to shale gas development is lacking. Consequently a shallow aquifer controlled CH4 release experiment is being conducted at the Borden aquifer research facility (an unconfined, unconsolidated silicate sand aquifer) in Ontario, Canada. During the experiment, 100 m3 of gas phase CH4 was injected into the saturated zone over approximately 60 days through 2 inclined sparging wells (4.5 and 9 m depth) at rates relevant to natural gas well casing vent flows. The gas mobility and fate is being comprehensively monitored temporally and spatially in both the saturated and unsaturated zones considering; aqueous chemistry (including stable isotopes), soil gas characterization, surface efflux, geophysics (GPR and ERT), real time sensors (total dissolved gas pressure, soil moisture content, CH4 and CO2), mineralogical and microbiological characterization before, during and after injection. An overview of this unique study will be given including experimental design, monitoring system configuration and preliminary results. This multidisciplinary study will provide important insights regarding the mechanisms and rates for shallow CH4 migration, attenuation and water quality impacts that will inform baseline groundwater monitoring programs and retrospective forensic studies.

  9. Investigating the Hydro-geochemical Impact of Fugitive Methane on Groundwater: The Borden Aquifer Controlled Release Study

    NASA Astrophysics Data System (ADS)

    Cahill, A. G.; Parker, B. L.; Cherry, J. A.; Mayer, K. U.; Mayer, B.; Ryan, C.

    2014-12-01

    Shale gas development by hydraulic fracturing is believed by many to have the potential to transform the world's energy economy. The propensity of this technique to cause significant environmental impact is strongly contested and lacks evidence. Fugitive methane (CH4), potentially mobilized during well drilling, the complex extraction process and/or leaking well seals over time is arguably the greatest concern. Advanced understanding of CH4 mobility and fate in the subsurface is needed in order to assess risks, design suitable monitoring systems and gain public trust. Currently knowledge on subsurface CH4 mobilization and migration at scales relevant to shale gas development is lacking. Consequently a shallow aquifer controlled CH4 release experiment is being conducted at the Borden aquifer research facility (an unconfined, unconsolidated silicate sand aquifer) in Ontario, Canada. During the experiment, 100 m3 of gas phase CH4 was injected into the saturated zone over approximately 60 days through 2 inclined sparging wells (4.5 and 9 m depth) at rates relevant to natural gas well casing vent flows. The gas mobility and fate is being comprehensively monitored temporally and spatially in both the saturated and unsaturated zones considering; aqueous chemistry (including stable isotopes), soil gas characterization, surface efflux, geophysics (GPR and ERT), real time sensors (total dissolved gas pressure, soil moisture content, CH4 and CO2), mineralogical and microbiological characterization before, during and after injection. An overview of this unique study will be given including experimental design, monitoring system configuration and preliminary results. This multidisciplinary study will provide important insights regarding the mechanisms and rates for shallow CH4 migration, attenuation and water quality impacts that will inform baseline groundwater monitoring programs and retrospective forensic studies.

  10. Effect of twenty minutes of aerobic exercise on in vivo platelet release in moderately trained females: radioimmunoassay of platelet factor 4 and beta-thromboglobulin

    SciTech Connect

    Rudmann, S.V.

    1986-01-01

    Circulating blood platelets serve an important role in the physiological process of hemostasis. Physical exercise has been documented to result in alterations in many hemostatic parameters including platelet size, number and function. Most published research data support the hypotheses that both hemostasis and fibrinolysis become activated as a consequence of various levels of physical exercise. The purpose of this study was to determine the effect of twenty minutes aerobic exercise on platelet activation in vivo. Platelet activation in vivo is associated with the release of platelet granular contents. Platelet alpha granules contain two platelet specific proteins: platelet factor 4 (PF4) and beta-thromboglobulin (BTG). Elevated plasma levels of these proteins are a specific marker of in vivo platelet activation. Subjects were moderately trained female volunteers between the ages of 22 and 40 years. Subjects were exercised or twenty minutes on a bicycle ergometer at workloads that represented 65 to 75% of their functional capacity. Blood specimens were drawn within five minutes of exercise. Plasma samples from exercise and control subjects were assayed for PF4 and BTG using a sensitive competitive-binding radioimmunoassay procedure. The mean plasma levels of both proteins were significantly greater in the exercising subjects when compared with the non-exercising controls. Data from this study support the following research hypotheses: BTG plasma levels will be significantly higher in exercising subjects than in non-exercising controls, and PF4 plasma levels will be significantly higher in exercising subjects than in non-exercising controls.

  11. Planktonic and sediment-associated aerobic methanotrophs in two seep systems along the North American margin.

    PubMed

    Tavormina, Patricia L; Ussler, William; Orphan, Victoria J

    2008-07-01

    Methane vents are of significant geochemical and ecological importance. Notable progress has been made toward understanding anaerobic methane oxidation in marine sediments; however, the diversity and distribution of aerobic methanotrophs in the water column are poorly characterized. Both environments play an essential role in regulating methane release from the oceans to the atmosphere. In this study, the diversity of particulate methane monooxygenase (pmoA) and 16S rRNA genes from two methane vent environments along the California continental margin was characterized. The pmoA phylotypes recovered from methane-rich sediments and the overlying water column differed. Sediments harbored the greatest number of unique pmoA phylotypes broadly affiliated with the Methylococcaceae family, whereas planktonic pmoA phylotypes formed three clades that were distinct from the sediment-hosted methanotrophs and distantly related to established methanotrophic clades. Water column-associated phylotypes were highly similar between field sites, suggesting that planktonic methanotroph diversity is controlled primarily by environmental factors rather than geographical proximity. Analysis of 16S rRNA genes from methane-rich waters did not readily recover known methanotrophic lineages, with only a few phylotypes demonstrating distant relatedness to Methylococcus. The development of new pmo primers increased the recovery of monooxygenase genes from the water column and led to the discovery of a highly diverged monooxygenase sequence which is phylogenetically intermediate to Amo and pMMO. This sequence potentiates insight into the amo/pmo superfamily. Together, these findings lend perspective into the diversity and segregation of aerobic methanotrophs within different methane-rich habitats in the marine environment.

  12. Rapid warming at the Palaeocene-Eocene Thermal Maximum drives rapid hydrate dissociation but only modest and delayed methane release to the ocean

    NASA Astrophysics Data System (ADS)

    Minshull, Tim; Marin-Moreno, Hector; Wilson, Paul; Armstrong McKay, David

    2016-04-01

    During the Palaeocene-Eocene Thermal Maximum (PETM), the carbon isotopic signature δ13C of the ocean-atmosphere system decreased abruptly - the record in deep sea benthic foraminifera shows an excursion of at least 2.5 to 3.0 ‰ VPDB. This global carbon isotope excursion (CIE) has been attributed to large-scale methane hydrate dissociation in response to rapid ocean warming. There is increasing evidence for warming-induced hydrate dissociation in the modern ocean and the PETM may represent an analogue for this process. We ran a thermohydraulic modeling code to simulate hydrate dissociation due to ocean warming for a range of possible PETM scenarios. Our results show that hydrate dissociation in response to such warming is rapid but methane release to the ocean is modest, and delayed by hundreds to thousands of years by transport processes through the hydrate stability field. In our simulations most of the dissociated hydrate methane remains beneath the seabed, either in solution or as free gas below the irreducible gas saturation, and the small fraction (≤0.13) released to the ocean is delivered over several kyr. We conclude that hydrate dissociation cannot have been largely responsible for the CIE unless the late Palaeocene hydrate inventory greatly exceeded most current estimates.

  13. Removal of atmospheric methane in shallow subterranean environments

    NASA Astrophysics Data System (ADS)

    Alvarez-Gallego, Miriam; Fernandez-Cortes, Angel; Cuezva, Soledad; García-Antón, Elena; Calaforra, Jose Maria; Cañaveras, Juan Carlos; Sanchez-Moral, Sergio

    2015-04-01

    Methane (CH4) is considered as the third most important greenhouse gas, after water and carbon dioxide, contributing substantially to radiative forcing. About 90% of the removal of CH4 from the atmosphere occurs through reaction with hydroxyl radicals. Moreover, secondary methane sink is related to soils by microbial oxidation in the aerobic zone of soils. Our monitoring results in subterranean environments have shown that there is an active remove of atmospheric methane without a significant intervention of methanotrophic bacteria. Several caves were monitored to identify the environmental factors controlling the gases exchange (CH4, CO2 and 222Rn) between subterranean environments, soils and atmosphere. Real-time and spots measurements of these greenhouse gases were measured using a cavity ring-down spectroscopy (CRDS) technique. Our results determine that concentrations of 222Rn and CO2 rise during the period of cave isolation (barely any exchange with the exterior atmosphere), contrary to the methane concentration decrease. The subterranean methane concentration was usually lower than the atmospheric and soil mean values. In addition, zero methane concentrations (ppm) were registered during several months in the most isolated caves. Our hypothesis is that an active process of methane oxidation is occurring in the underground atmosphere, akin to the photolysis effect that occurs in the troposphere-stratosphere region. Thus, negative and positive ions were measured inside the subterranean atmospheres to verify the correlation between the ionization by the 222Rn alpha particle decay and to the depletion of methane concentration. High negative correlations between negative ions and methane were obtained. Therefore, it is suggested that the oxidative gases (CO2, O2, H2Ov…), presented inside the subterranean environment, would be ionized by the energy released by 222Rn alpha particle decay, reacting and, consequently, oxidizing the atmospheric methane content.

  14. Carbon Release from Melting Arctic Permafrost on the North Slope, AK: 12CO2 and 13CO2 Concentrations and Fluxes, and Their Relationship to Methane and Methane Isotope Concentrations Measured in August 2013

    NASA Astrophysics Data System (ADS)

    Munster, J. B.; Sayres, D. S.; Healy, C. E.; Dumas, E. J.; Dobosy, R.; Kochendorfer, J.; Heuer, M.; Meyers, T. P.; Baker, B.; Anderson, J. G.

    2014-12-01

    One of the most important uncertainties in climate change is the positive feedback mechanism associated with the melting Arctic. As the Arctic permafrost destabilizes, labile carbon stored in the permafrost is subject to respiration and methanogenesis, producing greenhouse gases CO2 and CH4. Understanding the timing and rate of this release is paramount to our long-term understanding of the global climate structure, yet the remote location of the North Slope logistically precludes widespread tower measurements, necessitating airborne measurements. Presented are 12C and 13C CO2 concentration flux measurements taken via an aircraft at a height of 10-30m during mid to late August 2013 from the north slope of Alaska. The data show different regimes for CO2 vs δ-13C over regions within a roughly 100km box, indicating heterogenous landscape with differing dominant biological processes. The data are compared to CH4 measurements that were taken simultaneously, showing highly varying concentrations of CH4 with several different archetypical relationships to the total CO2 regimes. The relationship between CO2, δ-13C CO2, and CH4 concentrations provide further insight into the biological processes occurring in the melting Arctic permafrost. The data show that the dominant uptake and emission processes change by time of day and location. While the CO2 and isotopologue data alone indicates whether a region is dominant in respiration or photosynthesis, combining the data with CH4 measurements provides insight into the provenance of the CH4 as well as methanogenic biological pathways active on the North Slope, while mass balance between CH4, CO2 or δ-13C CO2 determines whether the methane signature is from methanogenesis, natural hydrocarbon seeps, or methane flaring. The data show few if any cases for which increases in methane concentrations are accompanied by a deviation in CO2 or δ-13C CO2 that would indicate incomplete methane flaring or natural seeps.

  15. Quantifying methane emission from fugitive sources by combining tracer release and downwind measurements - a sensitivity analysis based on multiple field surveys.

    PubMed

    Mønster, Jacob G; Samuelsson, Jerker; Kjeldsen, Peter; Rella, Chris W; Scheutz, Charlotte

    2014-08-01

    Using a dual species methane/acetylene instrument based on cavity ring down spectroscopy (CRDS), the dynamic plume tracer dispersion method for quantifying the emission rate of methane was successfully tested in four measurement campaigns: (1) controlled methane and trace gas release with different trace gas configurations, (2) landfill with unknown emission source locations, (3) landfill with closely located emission sources, and (4) comparing with an Fourier transform infrared spectroscopy (FTIR) instrument using multiple trace gasses for source separation. The new real-time, high precision instrument can measure methane plumes more than 1.2 km away from small sources (about 5 kg h(-1)) in urban areas with a measurement frequency allowing plume crossing at normal driving speed. The method can be used for quantification of total methane emissions from diffuse area sources down to 1 kg per hour and can be used to quantify individual sources with the right choice of wind direction and road distance. The placement of the trace gas is important for obtaining correct quantification and uncertainty of up to 36% can be incurred when the trace gas is not co-located with the methane source. Measurements made at greater distances are less sensitive to errors in trace gas placement and model calculations showed an uncertainty of less than 5% in both urban and open-country for placing the trace gas 100 m from the source, when measurements were done more than 3 km away. Using the ratio of the integrated plume concentrations of tracer gas and methane gives the most reliable results for measurements at various distances to the source, compared to the ratio of the highest concentration in the plume, the direct concentration ratio and using a Gaussian plume model. Under suitable weather and road conditions, the CRDS system can quantify the emission from different sources located close to each other using only one kind of trace gas due to the high time resolution, while the FTIR

  16. Alteration of rare earth element distribution as a result of microbial activity and empirical methane injection

    NASA Astrophysics Data System (ADS)

    Castillo, D. J.; Davies, N. W.; Thurber, A. R.; Haley, B. A.; Colwell, F. S.

    2014-12-01

    As a result of warming, methane is being released into the marine environment in areas that have not historically experienced methane input. While methane is a potent greenhouse gas, microbial oxidation of methane within the sediment greatly limits the role of marine methane sources on atmospheric forcing. However, in these areas of new methane release, consumption of methane prior to its release into the atmosphere is a result of the response of the microbial community to this new input of methane. Further, rare earth elements (REEs) are not currently thought to be involved with microbial activity, but this assumption has not been rigorously tested. Here we test that: (1) microbial communities will rapidly respond to the onset of methane emission, and (2) the microbial response to this methane input will impact the distribution of REEs within the sediment. Undisturbed cores sampled from a tidal flat at Yaquina Bay, OR, were brought back to a lab and injected with anoxic seawater (as a control) or anoxic sea water saturated with methane gas for a total of 2 weeks. Aerobic methanotrophs proliferated over this short time period, becoming an abundant member of the microbial community as identified using fatty acid biomarkers. Excitingly, the experimental injection of methane also shifted the distribution of REEs within the sediment, a trend that appeared to follow the microbial response and that was different from the control cores. Further, the lightest REEs appeared to be used more than the heavier ones, supporting that the REEs are being actively used by the microbes. While we focused on identifying the response of those microbes responsible in methane-cycling, we also identified how the entire microbial community shifts as a result of methane input, and correlating with shifts in REE distribution. Here we have empirically demonstrated the rapid response of methanotrophs to the onset of methane emission and that REE distribution within the sediment is likely

  17. Aerobic Conditions are Required for Rapid Carbon Losses following Permafrost Thaw

    NASA Astrophysics Data System (ADS)

    Cooper, M. D. A.; Estop-Aragones, C.

    2015-12-01

    Permafrost soils store between 1,330-1,580 billion tonnes of carbon (C), which may start to be released to the atmosphere if warming promotes widespread thaw. Considerable uncertainty remains regarding how rapidly this C may be released and what proportion will be released as the more powerful greenhouse gas, methane (CH4), rather than carbon dioxide (CO2). Central to answering these questions, is quantifying in situ rates of old, previously-frozen C release under aerobic conditions versus anaerobic conditions. To meet this aim, we investigated the amount and form (CH4 versus CO2) of previously-frozen C released in response to 1) forest fire-induced permafrost thaw (aerobic soil conditions) and 2) permafrost plateau collapse in peatlands which results in waterlogging (anaerobic conditions), in the Yukon and Northwest Territories of Canada. We quantified in situ rates of CO2 and CH4 release, using a novel collar design to either include or exclude C released from deep soil layers, and collected samples for 14CO2 and 14CH4 analysis. Our 14CO2 results identified substantial rates of old C release from burnt forests where the organic horizon was thick and deep thaw was observed. In contrast, in the wetlands old C release was barely detectable as CO2 (<1%), and, although high CH4 fluxes were measured, a maximum of 1.5-2g m-2 yr-1 was derived from previously-frozen C. Furthermore, because peat accumulation increased substantially (>4 times), , thaw resulted in net C gain in the wetland. However, the high rate of CH4 release, albeit derived mainly from contemporary sources, means that permafrost plateau collapse can still represent a positive feedback to climate change in terms of global warming potential. Overall, our results indicate a much greater release of permafrost C under aerobic conditions, with little release of previously-frozen C as either CO2 or CH4 under anaerobic conditions.

  18. Release of thermogenic-methane in the Hammerfest Basin after the Last Glacial Maximum. Indications from numerical modelling and 3D seismic reflection data

    NASA Astrophysics Data System (ADS)

    Anka, Z.; Rodrigues, E.; Ostanin, I.; di Primio, R.; Stoddart, D.; Horsfield, B.

    2012-04-01

    suggest that the leaked thermogenic methane was probably trapped as gas hydrate deposits during the glacial events and then released at once upon hydrate destabilisation during the Last Glacial Maximun (LGM). These results are supported by the identification on the 3D seismic data of both buried and seafloor mega-pockmarks (1-2 km wide), giant pockmarks (100-300 m wide) and pockmarks (up to100 m wide), which are linked to deep, shallow and Intra Paleocene regional faults. The described mechanism allows the temporal focussing of significant amounts of deep thermogenic fluids, including methane, in shallower levels of the basin and further sudden release to the hydrosphere. Predicted leaked volumes of thermogenic methane are at least 200 Tg only from this area of the Hammerfest Basin.

  19. Source and fate of methane seeping from continental margin sediments offshore Svalbard

    NASA Astrophysics Data System (ADS)

    Graves, C. A.; Stott, A.; Steinle, L.; Niemann, H.; Treude, T.; Berndt, C.; Wright, I. C.; Connelly, D.; James, R. H.

    2013-12-01

    A significant proportion of the world's organic carbon is currently trapped in and beneath submarine methane hydrates (e.g. Milkov, 2004). As ocean bottom waters warm, the gas hydrate stability zone (GHSZ) contracts, releasing gaseous methane into the sediments and potentially into the overlying water column and the atmosphere. In 2008, more than 250 plumes of methane gas were discovered rising from the seabed offshore Svalbard immediately upslope of the current GHSZ. As recent increases in ocean bottom water temperature may have destabilized hydrate in sediments beneath the plume locations, gas seepage has been hypothesized to be the result of this process (Westbrook et al., 2009). The implications of methane seepage offshore Svalbard in the context of changing global climate depend on the source and fate of the methane in these bubble plumes. To provide support for, or evidence contrary to, a gas-hydrate dissociation mechanism for methane release and to constrain potential atmospheric emission signatures we have characterized the chemical and isotopic signatures of: (i) hydrate recovered from within the GHSZ, (ii) shallow gas in sediments near the seep sites, (iii) plume gas bubbles, and (iv) dissolved gas in the water column. The absence of significant proportions of higher hydrocarbons in all samples suggests that the methane has a biogenic source, while methane carbon isotopic signatures point to a mixed biogenic and thermogenic origin. The chemical and isotopic composition of the hydrate-bound methane is consistent with that of the free gas in sediments below the seafloor seeps as well as the gas that escapes into the overlying water column. Away from bubble plume inputs (δ13C-CH4 -51 to -57 ‰) dissolved methane concentrations decrease while δ13C-CH4 values increase, indicating active aerobic oxidation of methane in the water column and implying surface seawater δ13C-CH4 values of < -20 ‰. Despite widespread methane supersaturated surface waters

  20. Carbon isotope (δ13C) excursions suggest times of major methane release during the last 14 ka in Fram Strait, the deep-water gateway to the Arctic

    NASA Astrophysics Data System (ADS)

    Consolaro, C.; Rasmussen, T. L.; Panieri, G.; Mienert, J.; Bünz, S.; Sztybor, K.

    2014-10-01

    We present results from a sediment core collected from a pockmark field on the Vestnesa Ridge (∼80° N) in the eastern Fram Strait. This is the only deep-water gateway to the Arctic, and one of the northernmost marine gas hydrate provinces in the world. Eight 14C AMS dating reveals a detailed chronology for the last 14 ka BP. The δ13C record measured on the benthic foraminiferal species Cassidulina neoteretis shows two distinct intervals with negative values, as low as -4.37‰ in the Bølling-Allerød interstadials and as low as -3.41‰ in the early Holocene. After cleaning procedure designed to remove all authigenic carbonate coatings on benthic foraminiferal tests, the 13C values are still negative (as low as -2.75‰). We have interpreted these negative carbon isotope excursions (CIEs) to record past methane release events, resulting from the incorporation of 13C-depleted carbon from methane emissions into the benthic foraminiferal shells. The CIEs during the Bølling-Allerød interstadials and the early Holocene relate to periods of ocean warming, sea level rise and increased concentrations of methane (CH4) in the atmosphere. CIEs with similar timing have been reported from other areas in the North Atlantic suggesting a regional event. The trigger mechanisms for such regional events remain to be determined. We speculate that sea-level rise and seabed loading due to high sediment supply in combination with increased seismic activity as a result of rapid deglaciation may have triggered the escape of significant amounts of methane to the seafloor and the water column above.

  1. Monitoring Production of Methane and Carbon Dioxide and Consumption of Oxygen at Spills of Gasoline at UST Release Sites

    EPA Science Inventory

    Methane is rarely measured at fuel spill sites, and most commonly the measurements are made on samples of ground water. Many ground water monitoring wells are intentionally screened across the water table. This was done to allow them to sample free product. However, if there is s...

  2. Ecological release and niche partitioning under stress: Lessons from dorvilleid polychaetes in sulfidic sediments at methane seeps

    NASA Astrophysics Data System (ADS)

    Levin, Lisa A.; Ziebis, Wiebke; Mendoza, Guillermo F.; Bertics, Victoria J.; Washington, Tracy; Gonzalez, Jennifer; Thurber, Andrew R.; Ebbe, Brigitte; Lee, Raymond W.

    2013-08-01

    Organisms inhabiting methane seep sediments are exposed to stress in the form of high levels of hydrogen sulfide, which result mainly from sulfate reduction coupled to anaerobic methane oxidation. Dorvilleidae (Polychaeta) have successfully invaded this ecosystem, and multiple species in divergent genetic clades co-occur at high densities. At methane seeps in the NE Pacific off California and Oregon, the genera Ophryotrocha, Parougia and Exallopus are especially well represented. To test the hypothesis that dorvilleid coexistence is facilitated by niche partitioning through sulfide tolerance and trophic patterns, we examined dorvilleid species-specific patterns of occurrence and nutrition at methane seeps off Eel R. [ER] on the Californian continental slope and at Hydrate Ridge [HR] on the Oregon continental slope, and in two habitats (clam bed and microbial mat) characterized by lower and higher hydrogen sulfide levels, respectively. Microelectrode measurements of hydrogen sulfide enabled characterization of environmental sulfide levels for species sampled in background sediment cores and in colonization trays. Dorvilleids tolerated H2S levels from 10 μM to over 2.6 mM, with the majority of species inhabiting sediments with similar environmental H2S concentrations (median 85-100 μM). Dorvilleid species richness was greater at HR than ER, but did not differ between clam bed and microbial mat habitats. Species distribution patterns reflected preferences for ER clam bed (lower sulfide levels), ER mat and HR clam bed (moderate sulfide levels), or HR mat (very high sulfide levels). Nutritional patterns, including trophic diversity and functional similarity, were examined using community stable isotope metrics based on δ15N and δ13C. Within each region, dorvilleid species exhibited multiple trophic strategies. Co-existing congeners typically exhibited distinct isotope signatures, suggesting trophic partitioning. Trophic diversity and δ15N range for whole

  3. Mars Methane Plume Tracer

    NASA Astrophysics Data System (ADS)

    Mischna, M. A.; Banfield, D.; Sykes, I.

    2014-07-01

    Putative releases of methane from the martian surface may be challenging to detect from orbit. Successful detections depend on the character of the plume itself (duration, magnitude, expanse), but also on the observing platform.

  4. A large thermogenic-methane release event in the SW Barents Sea, during the Last Glacial Maximum. Indications from numerical modelling and seismic reflection data

    NASA Astrophysics Data System (ADS)

    Anka, Z.; Rodrigues, E.; di Primio, R.; Ostanin, I.; Stoddart, D.; Horsfield, B.

    2011-12-01

    The Barents Sea, located in the Norwegian Artic area, has undergone a series of tectonic, paleoceanographic and paleo-climatic events during the Cenozoic, which most likely have caused the redistribution and leakage of hydrocarbons accumulations (Ohm et al., 2008). (Dimakis et al., 1998). Present-day under-filled accumulations are known to have leaked in the past providing a source of hydrocarbons, mostly thermogenic methane. However, the timing, extent and driving factors for this event are largely unconstrained. We built a 3D basin model of the Hammerfest Basin in the SW Barents Sea, in order to quantify the masses of liquid and gaseous hydrocarbons generated, accumulated and eventually leaked from the reservoirs during the evolution of the basin. Particular emphasis was placed on analysing the fate of leaked volumes within the dynamics of Plio-Quaternary glacial cycles and formation or destabilization of gas hydrate deposits. The model was calibrated with maturity and temperature well data and reconstructs, with large degree of accuracy, the composition and volume of the hydrocarbons, particularly the gaseous phase present in the main reservoirs. Our results predict the development of overpressures in the reservoirs due to the ice loading of the basin during the glacial periods. Pressure fluctuations derived from cyclic loading-unloading during the glacial-interglacial periods reached up to 5 MPa. The under-filled nature of the present-day accumulations would result from leakage events during the episodes of glacial retreat, in the transition from glacial to interglacial periods. Considerations of the gas hydrate stability conditions in the basin during the time span between 1.00Ma and ≈11,500 years indicate that the leaking thermogenic methane was probably trapped as gas hydrate deposits during the glacial events and then released at once upon hydrate destabilisation during the Last Glacial Maximun (LGM). These results are supported by the presence of km

  5. Microbiological investigation of methane- and hydrocarbon-discharging mud volcanoes in the Carpathian Mountains, Romania.

    PubMed

    Alain, Karine; Holler, Thomas; Musat, Florin; Elvert, Marcus; Treude, Tina; Krüger, Martin

    2006-04-01

    Paclele Mici is a terrestrial mud volcano field located in the Carpathian Mountains (Romania), where thermal alteration of sedimentary organic compounds leads to methane, higher hydrocarbons and other petroleum compounds that are continuously released into the environment. The hydrocarbons represent potential substrates for microorganisms. We studied lipid biomarkers, stable isotope ratios, the effect of substrate (methane, other organic compounds) addition and 16S rRNA genes to gain insights into the hitherto unknown microbial community at this site. Quantitative real-time polymerase chain reaction analysis demonstrated that bacteria were much more abundant than archaea. Phylogenetic analyses of 16S rDNA clone sequences indicated the presence of bacterial and archaeal lineages generally associated with the methane cycle (methanogens, aerobic and anaerobic methanotrophs), the sulfur cycle (sulfate reducers), and groups linked to the anaerobic degradation of alkanes or aromatic hydrocarbons. The presence of sulfate reducers, methanogens and methanotrophs in this habitat was also confirmed by concurrent surveys of lipid biomarkers and their isotopic signatures. Incubation experiments with several common and complex substrates revealed the potential of the indigenous microbial community for sulfate reduction, methanogenesis and aerobic methanotrophy. Additionally, consistently to the detection of methane-oxidizing archaea (ANME) and 13C-depleted archaeal lipids, a weak but significant activity of anaerobic methane oxidation was measured by radiotracer techniques and in vitro. This survey is the first to report the presence and activity of ANME in a terrestrial environment.

  6. Novel microbial communities of the Haakon Mosby mud volcano and their role as a methane sink.

    PubMed

    Niemann, Helge; Lösekann, Tina; de Beer, Dirk; Elvert, Marcus; Nadalig, Thierry; Knittel, Katrin; Amann, Rudolf; Sauter, Eberhard J; Schlüter, Michael; Klages, Michael; Foucher, Jean Paul; Boetius, Antje

    2006-10-19

    Mud volcanism is an important natural source of the greenhouse gas methane to the hydrosphere and atmosphere. Recent investigations show that the number of active submarine mud volcanoes might be much higher than anticipated (for example, see refs 3-5), and that gas emitted from deep-sea seeps might reach the upper mixed ocean. Unfortunately, global methane emission from active submarine mud volcanoes cannot be quantified because their number and gas release are unknown. It is also unclear how efficiently methane-oxidizing microorganisms remove methane. Here we investigate the methane-emitting Haakon Mosby Mud Volcano (HMMV, Barents Sea, 72 degrees N, 14 degrees 44' E; 1,250 m water depth) to provide quantitative estimates of the in situ composition, distribution and activity of methanotrophs in relation to gas emission. The HMMV hosts three key communities: aerobic methanotrophic bacteria (Methylococcales), anaerobic methanotrophic archaea (ANME-2) thriving below siboglinid tubeworms, and a previously undescribed clade of archaea (ANME-3) associated with bacterial mats. We found that the upward flow of sulphate- and oxygen-free mud volcano fluids restricts the availability of these electron acceptors for methane oxidation, and hence the habitat range of methanotrophs. This mechanism limits the capacity of the microbial methane filter at active marine mud volcanoes to <40% of the total flux. PMID:17051217

  7. [Microbial Processes and Genesis of Methane Gas Jets in the Coastal Areas of the Crimea Peninsula].

    PubMed

    Malakhova, T V; Kanapatskii, T A; Egorov, V N; Malakhova, L V; Artemov, Yu G; Evtushenko, D B; Gulin, S B; Pimenov, N V

    2015-01-01

    Hydroasoustic techniques were used for detection and mapping of gas jet areas in the coastal regions of the Crimean peninsula. Gas seep areas in the bays Laspi, Khersones, and Kazach'ya were chosen for detailed microbiological investigation. The first type of gas jets, observed in the Laspi Bay, was probably associated with discarge of deep thermogenic methane along the faults. Methane isotopic composition was char- acterized by Δ13C of -35.3 degrees. While elevated rates of aerobic methane oxidation were revealed in the sandy sediments adjacent to the methane release site, no evidence of bacterial mats was found. The second type of gas emission, observed in the Khersones Bay, was accompanied by formation of bacterial biofilms of the "Thiodendron" microbial community type, predominated by filamentous, spirochete-like organisms, in the areas of gas seepage. The isotopic composition of methane was there considerably lower (-60.4 degrees), indicating a considerable contribution of modern microbial methane to the gas bubbles discharged in this bay. Activity of the third type of gas emission, the seeps of the Kazach'ya Bay, probably depended directly on modern microbial processes of organic matter degradation in the upper sediment layers. The rates of sulfate reduction and methanogenesis were 260 and 34 μmol dm(-3) day(-1), respectively. Our results indicate different mechanisms responsible for formation of methane jets in the Laspi Bay and in the coastal areas of the Heracles Peninsula, where the bays Kazach'ya and Khersones are located.

  8. [Microbial Processes and Genesis of Methane Gas Jets in the Coastal Areas of the Crimea Peninsula].

    PubMed

    Malakhova, T V; Kanapatskii, T A; Egorov, V N; Malakhova, L V; Artemov, Yu G; Evtushenko, D B; Gulin, S B; Pimenov, N V

    2015-01-01

    Hydroasoustic techniques were used for detection and mapping of gas jet areas in the coastal regions of the Crimean peninsula. Gas seep areas in the bays Laspi, Khersones, and Kazach'ya were chosen for detailed microbiological investigation. The first type of gas jets, observed in the Laspi Bay, was probably associated with discarge of deep thermogenic methane along the faults. Methane isotopic composition was char- acterized by Δ13C of -35.3 degrees. While elevated rates of aerobic methane oxidation were revealed in the sandy sediments adjacent to the methane release site, no evidence of bacterial mats was found. The second type of gas emission, observed in the Khersones Bay, was accompanied by formation of bacterial biofilms of the "Thiodendron" microbial community type, predominated by filamentous, spirochete-like organisms, in the areas of gas seepage. The isotopic composition of methane was there considerably lower (-60.4 degrees), indicating a considerable contribution of modern microbial methane to the gas bubbles discharged in this bay. Activity of the third type of gas emission, the seeps of the Kazach'ya Bay, probably depended directly on modern microbial processes of organic matter degradation in the upper sediment layers. The rates of sulfate reduction and methanogenesis were 260 and 34 μmol dm(-3) day(-1), respectively. Our results indicate different mechanisms responsible for formation of methane jets in the Laspi Bay and in the coastal areas of the Heracles Peninsula, where the bays Kazach'ya and Khersones are located. PMID:26964364

  9. Microbial production and oxidation of methane in deep subsurface

    NASA Astrophysics Data System (ADS)

    Kotelnikova, Svetlana

    2002-10-01

    microbially to carbon dioxide. Microbial methane oxidation is a biogeochemical process that limits the release of methane, a greenhouse gas from anaerobic environments. Anaerobic methane oxidation plays an important role in marine sediments. Similar processes may take place in deep subsurface and thus fuel the deep microbial community. Organisms or consortia responsible for anaerobic methane oxidation have not yet been cultured, although diverse aerobic methanotrophs have been isolated from a variety of underground niches. The presence of aerobic methanotrophs in the anoxic subsurface remains to be explained. The presence of methane in the deep subsurface have been shown all over the world. The flux of gases between the deep subsurface and the atmosphere is driven by the concentration gradient from depth to the atmosphere. However, methane is consumed by methanotrophs on the way of its evolution in oxidized environments and is transformed to organic form, available for further microbial processing. When the impact of subsurface environments to global warming is estimated, it is necessary to take into account the activity of methane-producing Archaea and methane-oxidizing biofilters in groundwater. Microbial production and oxidation of methane is involved in the carbon cycle in the deep subsurface environments.

  10. Permafrost and gas hydrate related methane release in the Arctic and its impact on climate change - European cooperation for long-term monitoring: COST Action PERGAMON (www.cost-pergamon.eu)

    NASA Astrophysics Data System (ADS)

    Greinert, Jens; Treude, Tina; Members, Pergamon

    2010-05-01

    The Arctic is a key area in our warming world as massive releases of terrestrial and oceanic methane could increase atmospheric methane concentrations much faster than expected. The vast Arctic shelf might become a major emitter of methane in the future. Only a few projects are engaged in research on methane seepage in this area. The exchange of information about ongoing and planned activities in the Arctic with respect to gas hydrate destabilization and permafrost thawing is low within the EU and almost non-existent at an international level. The aim of the COST Action PERGAMON is to promote networking internationally within the EU and beyond: data integration of terrestrial studies from wetlands and permafrost regions marine research on gas release from seeps due to decomposing gas hydrate and/or permafrost melting and atmospheric investigations carried out by monitoring stations and via satellite is urgently needed to achieve a better understanding of methane emission processes in high latitude areas. The "official" main objective of PERGAMON is to quantify the methane input from marine and terrestrial sources into the atmosphere in the Arctic region, and ultimately to evaluate the impact of Arctic methane seepage on the global climate. This will be achieved by studying the origin and type of occurrence (dissolved/free gas, gas hydrate) of different methane sources (both on land and in the sub-seabed) as well as methane migration mechanisms, biogeochemical turnover, release mechanisms, and finally by quantifying the flux into the atmosphere. Biannual meetings and open workshops/conferences that will be announced throughout the scientific community serve as a platform to exchange and proliferate knowledge on methane in the Arctic. At present, fourteeen European countries are partners in PERGAMON, several non-COST country institutions are currently applying to participate (e.g. the US and Russia). PERGAMON aims to be open for new members, suggestions and input at

  11. Geochemical and Hydrological limitation of carbon sequestration and methane release in anoxic peat soil from the Luther Marsh, Canada

    NASA Astrophysics Data System (ADS)

    Bonaiuti, Simona; Blodau, Christian

    2015-04-01

    In deep peat layers, anaerobic respiration showed a slow-down due to the lack of solute transport which causes an accumulation of metabolic end products (i.e. DIC and CH4). This accumulation can lower the Gibbs free energy levels available to the terminal respiration processes, potentially leading to an inhibition in the decomposition. In particular, this state can affect the methanogenesis, acetogenesis and fermentation processes which occur near thermodynamic minimum energy levels. We conducted a column experiments with an ombrothrophic bog peat over a period of 300 days at 20° C, to test the hypothesis that alteration in solute and gas transport rates can remove this biogeochemical inactivation of DIC and methane turnover rates. To this end, we tested a i) control treatment with no gas and solute transport, ii) advective flow treatment with a flow water of 10 mm d-1, iii) ebullition treatment with methane removal by conduit transport as surrogate for bubbling, and iv) an O2-free atmosphere treatment to test the effect of remote transport of electron on anaerobic decomposition, in absence of oxygen compared to the other treatment. We determined detailed concentration depth profiles of dissolved inorganic carbon (DIC), methane (CH4) and relevant decomposition intermediates (i.e. H2, Fe, nitrate, acetate, formiate and propionate), every 15 days at the beginning and every ca. 2 months after 75 days. CO2 and CH4 fluxes were measured using a static chamber approach. Net turnover of DIC and CH4 in depth layers was calculated for individual depth intervals from mass balance approach based on diffusive mass fluxes between adjacent depth layers and change in storage over time. Thermodynamic energy levels of relevant electron accepting processes were calculated over time. In the initial phase of the experiments, DIC and CH4 concentrations increased mostly below the water table level at 10 cm depth and over time in all treatments. After 45 days of incubation, CH4

  12. Methane bioattenuation and implications for explosion risk reduction along the groundwater to soil surface pathway above a plume of dissolved ethanol.

    PubMed

    Ma, Jie; Rixey, William G; DeVaull, George E; Stafford, Brent P; Alvarez, Pedro J J

    2012-06-01

    Fuel ethanol releases can stimulate methanogenesis in impacted aquifers, which could pose an explosion risk if methane migrates into enclosed spaces where ignitable conditions exist. To assess this potential risk, a flux chamber was emplaced on a pilot-scale aquifer exposed to continuous release (21 months) of an ethanol solution (10% v:v) that was introduced 22.5 cm below the water table. Despite methane concentrations within the ethanol plume reaching saturated levels (20-23 mg/L), the maximum methane concentration reaching the chamber (21 ppm(v)) was far below the lower explosion limit in air (50,000 ppm(v)). The low concentrations of methane observed in the chamber are attributed to methanotrophic activity, which was highest in the capillary fringe. This was indicated by methane degradation assays in microcosms prepared with soil samples from different depths, as well as by PCR measurements of pmoA, which is a widely used functional gene biomarker for methanotrophs. Simulations with the analytical vapor intrusion model "Biovapor" corroborated the low explosion risk associated with ethanol fuel releases under more generic conditions. Model simulations also indicated that depending on site-specific conditions, methane oxidation in the unsaturated zone could deplete the available oxygen and hinder aerobic benzene biodegradation, thus increasing benzene vapor intrusion potential. Overall, this study shows the importance of methanotrophic activity near the water table to attenuate methane generated from dissolved ethanol plumes and reduce its potential to migrate and accumulate at the surface.

  13. Measurements and Simulations of Methane Concentration During a Controlled Release Experiment for Top-down Emission Quantification by In Situ and Remote Sensing

    NASA Astrophysics Data System (ADS)

    Nottrott, A.; Rahn, T. A.; Costigan, K. R.; Canfield, J.; Arata, C.; Dubey, M.; Frankenberg, C.; Thorpe, A. K.; Aubrey, A. D.

    2013-12-01

    Natural gas has been widely touted as a transition fuel because it produces fewer greenhouse gas (GHG) emissions from combustion than coal or oil. However, considering the lifecycle GHG emissions from the entire natural gas production process it is unclear whether the environmentally detrimental aspects of drilling, refining and transportation offset the benefits associated with reduced GHG emissions during combustion. Bottom-up estimates of methane (CH4) leaks from natural gas production range from 1-10% of total production, but actual emissions have not yet been verified with measurements. A large scale, outdoor, controlled release experiment was conducted to measure CH4 emissions from quasi-point sources at local spatial scales in top-down framework. The experiment was designed to quantify the sensitivity of remotely sensed observations from three airborne hyperspectral sensors AVIRIS, CARVE and HyTES. Release rates ranged from 10-5000 scf/hr. CH4 concentration fluctuations and boundary layer turbulence were measured at 20 Hz on towers located downwind of release locations. Analytical footprint and computational fluid dynamics models are employed to simulate boundary layer turbulence fields and aid in the interpretation of in situ data. CH4 emissions rates are calculated with an uncertainty of 20-70% using only in situ measurements as input to a concentration footprint model. The Weather Research and Forecasting (WRF) model is used to simulate local atmospheric conditions during the experiment, and provide boundary conditions to force very high resolution, terrain resolving large-eddy simulations (LES). WRF simulations are initialized and nudged with fields from the North American Mesoscale Forecast System (NAM) 40 km analysis, and incorporate the effects of topography at sub one-kilometer scales. The HIGRAD LES model is run with a horizontal grid resolution up to 2 meters. Methane sources are simulated in HIGRAD, and model output is used to augment spatially

  14. Photoinduced CO release, cellular uptake and cytotoxicity of a tris(pyrazolyl)methane (tpm) manganese tricarbonyl complex.

    PubMed

    Niesel, Johanna; Pinto, Antonio; Peindy N'Dongo, Harmel W; Merz, Klaus; Ott, Ingo; Gust, Ronald; Schatzschneider, Ulrich

    2008-04-21

    Cell viability studies of HT29 colon cancer cells treated with the CO-releasing compound [Mn(CO)(3)(tpm)]PF(6) revealed a significant photoinduced cytotoxicity comparable to that of established agent 5-fluorouracil (5-FU), while controls kept in the dark were unaffected at up to 100 microM.

  15. Impacts of an ethanol-blended fuel release on groundwater and fate of produced methane: Simulation of field observations

    EPA Science Inventory

    In a field experiment at Vandenberg Air Force Base (VAFB) designed to mimic the impact of a small-volume release of E10, two plumes were created by injecting extracted groundwater spiked with benzene, toluene, and o-xylene, abbreviated BToX (No-Ethanol Lane) and BToX plus ethanol...

  16. Short-term variations of methane concentrations and methanotrophic activity in a coastal inlet (Eckernförde Bay, Germany)

    NASA Astrophysics Data System (ADS)

    Richner, Dominik; Niemann, Helge; Steinle, Lea; Schneider von Deimling, Jens; Urban, Peter; Hoffmann, Jasper; Schmidt, Mark; Treude, Tina; Lehmann, Moritz

    2016-04-01

    Large quantities of methane are produced in anoxic sediments of continental margins and may be liberated into the overlying water column and, potentially, into the atmosphere. However, a sequence of microbially mediated methane oxidation pathways in sediments and the water column mitigate the contribution of oceans to the atmospheric methane budget. Of particular importance are methanotrophic bacteria in the water column that mediate the aerobic oxidation of methane (MOx), and represent the final sink for methane before its release to the atmosphere where it acts as a potent greenhouse gas. However methane cycling in (aerobic) marine waters is not well constrained. Particularly little is known about spatiotemporal aspects of MOx activity and the underlying key physical, chemical and biological factors. Here we show results from our investigations on methane dynamics on very short time scales of hours to days in the Eckernförde Bay (E-Bay), a costal inlet of the Baltic Sea in northern Germany featuring seasonal bottom water hypoxia/anoxia. In autumn 2014, we observed highly spatiotemporal variations in water column methane contents and MOx activity: Anoxic bottom waters in a trough in the northern part of the bay contained extremely high methane concentrations of up to 800 nM, which sharply declined at the midwater redox interface (methane remained supersaturated with respect to the atmospheric equilibrium throughout the water column at all times). The methane decrease at the redox interface was related to highly active MOx communities consuming methane under microoxic conditions at rates of up 40 nM/d. About 12 hours later, the methane content and the extend of bottom water anoxia was much lower and MOx activity was highly reduced in the northern part but strongly elevated in the southern part of the bay. A few days later, bottom water anoxia, methane loading and MOx activity was partially re-established. In this contribution, we will discuss potential forcing

  17. Gas hydrate formation in the deep sea: In situ experiments with controlled release of methane, natural gas, and carbon dioxide

    USGS Publications Warehouse

    Brewer, P.G.; Orr, F.M.; Friederich, G.; Kvenvolden, K.A.; Orange, D.L.

    1998-01-01

    We have utilized a remotely operated vehicle (ROV) to initiate a program of research into gas hydrate formation in the deep sea by controlled release of hydrocarbon gases and liquid CO2 into natural sea water and marine sediments. Our objectives were to investigate the formation rates and growth patterns of gas hydrates in natural systems and to assess the geochemical stability of the reaction products over time. The novel experimental procedures used the carrying capacity, imaging capability, and control mechanisms of the ROV to transport gas cylinders to depth and to open valves selectively under desired P-T conditions to release the gas either into contained natural sea water or into sediments. In experiments in Monterey Bay, California, at 910 m depth and 3.9??C water temperature we find hydrate formation to be nearly instantaneous for a variety of gases. In sediments the pattern of hydrate formation is dependent on the pore size, with flooding of the pore spaces in a coarse sand yielding a hydrate cemented mass, and gas channeling in a fine-grained mud creating a veined hydrate structure. In experiments with liquid CO2 the released globules appeared to form a hydrate skin as they slowly rose in the apparatus. An initial attempt to leave the experimental material on the sea floor for an extended period was partially successful; we observed an apparent complete dissolution of the liquid CO2 mass, and an apparent consolidation of the CH4 hydrate, over a period of about 85 days.

  18. Characterization and biological abatement of diffuse methane emissions and odour in an innovative wastewater treatment plant.

    PubMed

    Barcón, Tamara; Hernández, Jerónimo; Gómez-Cuervo, Santiago; Garrido, Juan M; Omil, Francisco

    2015-01-01

    An innovative and patented process for medium-high strength sewage which comprises an anaerobic step followed by a hybrid anoxic-aerobic chamber and a final ultrafiltration stage was characterized in terms of methane fugitive emissions as well as odours. The operation at ambient temperature implies higher methane content in the liquid anaerobic effluent, which finally causes concentrations around 0.01-2.4% in the off-gas released in the anoxic-aerobic chamber (1.25% average). Mass balances indicate that these emissions account for up to 30-35% of the total methane generated in the anaerobic reactor. A conventional biofilter (BF) operated at an empty bed residence time of 4 min was used to treat these emissions for 70 d. In spite of the fluctuations in the methane inlet concentrations derived from the operation of the wastewater treatment plant (WWTP), it was possible to operate at pseudo-steady-state conditions, achieving average removal efficiencies of 76.5% and maximum elimination capacities of 30.1 g m(-3) h(-1). Odour removal was quantified as 99.1%. Fluorescence in situ hybridization probes as well as metabolic activity assays demonstrated the suitability of the biomass developed in the WWTP as inoculum to start up the BF due to the presence of methanotrophic bacteria.

  19. Quantifying the flux and fate of methane into the Hudson Canyon at the edge of methane clathrate hydrate stability

    NASA Astrophysics Data System (ADS)

    Kessler, J. D.; Leonte, M.; Garcia-Tigreros Kodovska, F.; Chan, E. W.; Valentine, D. L.; Kellermann, M. Y.; Arrington, E. C.; Navarrete, L. C.; Weinstein, A.; Chepigin, A.; Weber, T.; Ruppel, C. D.; Scranton, M. I.

    2015-12-01

    Methane seeps were investigated in the Hudson Canyon, along the northern US Atlantic Margin on the R/V Endeavor in July 2014. These seeps are located along the upper feather-edge of the methane clathrate hydrate stability zone. Water column samples were collected guided by the acoustic identification of bubble streams in a 32 km2 region. This presentation details the measurements of dissolved methane concentration, natural stable isotopes, potential methane oxidation rates, and current velocity which were used in chemical and isotopic models to quantify (1) the total emission of methane to the water column in this region and (2) the extent of aerobic methane oxidation. In addition, the timing, efficiency, and kinetics of aerobic methane oxidation were investigated with mesocosm incubations of seawater in a unique experimental design that enabled high temporal resolution data acquisition. Finally, the ultimate fate of methane carbon was assessed with high precision measurements of pH.

  20. Methane release from the East Siberian Arctic Shelf: The role of subsea permafrost and other controlling factors as inferred from decadal observational and modeling efforts

    NASA Astrophysics Data System (ADS)

    Shakhova, N. E.

    2015-12-01

    Sustained methane (CH4) release from thawing Arctic permafrost to atmosphere may be a positive, major feedback to climate warming. East Siberian Arctic Shelf (ESAS) atmospheric CH4 venting was reported as on par with flux from Arctic tundra. Unlike release when ancient carbon in thawed on-land permafrost is mobilized, ESAS CH4 release is not determined by modern methanogenesis. Pre-formed CH4 largely stems from seabed deposits. Our investigation, including observational studies using hydrological, biogeochemical, geophysical, geo-electrical, microbiological, and isotopic methods, and modeling efforts to assess current subsea permafrost state and the ESAS' contribution to the regional CH4 budget, have clarified processes driving ESAS CH4 emissions. Subsea permafrost state is a major emission determinant; rates vary by 3-5 orders of magnitude. Outer ESAS CH4 emission rates, where subsea permafrost is predicted to be degraded due to long submergence by seawater, in places are similar to near-shore rates, where deep/open taliks can form due to combined heating effects of seawater, river runoff, geothermal flux, and pre-existing thermokarst. Progressive subsea permafrost thawing and decreasing ice extent could significantly increase ESAS CH4 emissions. Subsea permafrost drilling results reveal modern recently submerged subsea permafrost degradation rates, contradicting previous hypotheses that thousands of years required to form escape paths for permafrost-preserved gas. We used a decadal observational ESAS water column and atmospheric boundary layer (ABL) data set to define the minimum source strength required to explain observed seasonally-increased ABL CH4 concentration. Modeling results agree with estimates from in-situ sonar data. In <10 m shallow water ≤72% of CH4 remains in surfacing bubbles. Dissolved CH4 fate largely depends on 3 factors: dissolved CH4 water column turnover time, water column stability against vertical mixing, and turbulent diffusion and

  1. Methane oxidation coupled to oxygenic photosynthesis in anoxic waters

    PubMed Central

    Milucka, Jana; Kirf, Mathias; Lu, Lu; Krupke, Andreas; Lam, Phyllis; Littmann, Sten; Kuypers, Marcel MM; Schubert, Carsten J

    2015-01-01

    Freshwater lakes represent large methane sources that, in contrast to the Ocean, significantly contribute to non-anthropogenic methane emissions to the atmosphere. Particularly mixed lakes are major methane emitters, while permanently and seasonally stratified lakes with anoxic bottom waters are often characterized by strongly reduced methane emissions. The causes for this reduced methane flux from anoxic lake waters are not fully understood. Here we identified the microorganisms and processes responsible for the near complete consumption of methane in the anoxic waters of a permanently stratified lake, Lago di Cadagno. Interestingly, known anaerobic methanotrophs could not be detected in these waters. Instead, we found abundant gamma-proteobacterial aerobic methane-oxidizing bacteria active in the anoxic waters. In vitro incubations revealed that, among all the tested potential electron acceptors, only the addition of oxygen enhanced the rates of methane oxidation. An equally pronounced stimulation was also observed when the anoxic water samples were incubated in the light. Our combined results from molecular, biogeochemical and single-cell analyses indicate that methane removal at the anoxic chemocline of Lago di Cadagno is due to true aerobic oxidation of methane fuelled by in situ oxygen production by photosynthetic algae. A similar mechanism could be active in seasonally stratified lakes and marine basins such as the Black Sea, where light penetrates to the anoxic chemocline. Given the widespread occurrence of seasonally stratified anoxic lakes, aerobic methane oxidation coupled to oxygenic photosynthesis might have an important but so far neglected role in methane emissions from lakes. PMID:25679533

  2. Methane oxidation coupled to oxygenic photosynthesis in anoxic waters.

    PubMed

    Milucka, Jana; Kirf, Mathias; Lu, Lu; Krupke, Andreas; Lam, Phyllis; Littmann, Sten; Kuypers, Marcel M M; Schubert, Carsten J

    2015-09-01

    Freshwater lakes represent large methane sources that, in contrast to the Ocean, significantly contribute to non-anthropogenic methane emissions to the atmosphere. Particularly mixed lakes are major methane emitters, while permanently and seasonally stratified lakes with anoxic bottom waters are often characterized by strongly reduced methane emissions. The causes for this reduced methane flux from anoxic lake waters are not fully understood. Here we identified the microorganisms and processes responsible for the near complete consumption of methane in the anoxic waters of a permanently stratified lake, Lago di Cadagno. Interestingly, known anaerobic methanotrophs could not be detected in these waters. Instead, we found abundant gamma-proteobacterial aerobic methane-oxidizing bacteria active in the anoxic waters. In vitro incubations revealed that, among all the tested potential electron acceptors, only the addition of oxygen enhanced the rates of methane oxidation. An equally pronounced stimulation was also observed when the anoxic water samples were incubated in the light. Our combined results from molecular, biogeochemical and single-cell analyses indicate that methane removal at the anoxic chemocline of Lago di Cadagno is due to true aerobic oxidation of methane fuelled by in situ oxygen production by photosynthetic algae. A similar mechanism could be active in seasonally stratified lakes and marine basins such as the Black Sea, where light penetrates to the anoxic chemocline. Given the widespread occurrence of seasonally stratified anoxic lakes, aerobic methane oxidation coupled to oxygenic photosynthesis might have an important but so far neglected role in methane emissions from lakes.

  3. Phospholipid-Derived Fatty Acids and Their Stable and Radiocarbon Isotope Values as Indicators of Bacterial Methane Oxidation at a Thermogenic Methane Seep

    NASA Astrophysics Data System (ADS)

    Mills, C. T.; Dias, R. F.; Slater, G. F.; Reddy, C. M.; Mandernack, K. W.

    2004-12-01

    The importance of aerobic methanotrophy as a filter for biogenic methane emissions is well documented for environments such as natural wetlands, landfills, and rice paddies, but less is known about methane oxidation in soils overlying thermogenic methane seeps. We are utilizing phospholipid-derived fatty acids (PLFAs) extracted from soils overlying a high-rate, coal-bed methane seep in Southwestern Colorado to investigate the location and extent of bacterial methane consumption within the soil column. PLFAs have been widely used as indicators of both quantities and types of viable bacterial populations. Two specific PLFAs, 16:1ω 8 and 18:1ω 8, appear to be unique to type I and type II methanotrophs, respectively. We have detected higher abundances of these methanotroph biomarkers in surface soils ( ˜0-30 cm) under wetter soil conditions and near the water table ( ˜150 cm) under drier conditions. Maximum concentrations of both type I and type II methanotroph PLFA biomarkers were greatest in the shallow soils during wetter conditions with the type I maximum located just above the type II maximum. This is consistent with pure culture studies that have shown type I methanotrophs to prefer higher oxygen, lower methane conditions and type II methanotrophs to prefer lower oxygen, higher methane conditions. Soil gas methane concentrations during this wetter period were approximately 30% at 20 cm depth and 80% at 100 cm depth. During a drier period a type II methanotroph biomarker maximum was observed near the water table but no type I maximum was observed. Soil gas methane concentrations at this time were less than 1% at 20 cm and 25% at 100 cm. These data suggest that methanotrophs may consume a significant fraction of the methane as it rises through the soil column. Greater saturation of soil pore spaces during wetter conditions may inhibit atmospheric oxygen diffusion into deeper soils forcing methanotrophs to reside in the shallow soils and resulting in larger

  4. Biotic landfill cover treatments for mitigating methane emissions.

    PubMed

    Hilgeri, Helene; Humer, Marion

    2003-05-01

    Landfill methane (CH4) emissions have been cited as one of the anthropogenic gas releases that can and should be controlled to reduce global climate change. This article reviews recent research that identifies ways to enhance microbial consumption of the gas in the aerobic portion of a landfill cover. Use of these methods can augment CH4 emission reductions achieved by gas collection or provide a sole means to consume CH4 at small landfills that do not have active gas collection systems. Field studies indicate that high levels of CH4 removal can be achieved by optimizing natural soil microbial processes. Further, during biotic conversion, not all of the CH4 carbon is converted to carbon dioxide (CO2) gas and released to the atmosphere; some of it will be sequestered in microbial biomass. Because biotic covers can employ residuals from other municipal processes, financial benefits can also accrue from avoided costs for residuals disposal.

  5. Regulation of Methane Oxidation in a Freshwater Wetland by Water Table Changes and Anoxia

    NASA Technical Reports Server (NTRS)

    Roslev, Peter; King, Gary M.

    1996-01-01

    The effects of water table fluctuations and anoxia on methane emission and methane oxidation were studied in a freshwater marsh. Seasonal aerobic methane oxidation rates varied between 15% and 76% of the potential diffusive methane flux (diffusive flux in the absence of aerobic oxidation). On an annual basis, approximately 43% of the methane diffusing into the oxic zone was oxidized before reaching the atmosphere. The highest methane oxidation was observed when the water table was below the peat surface. This was confirmed in laboratory experiments where short-term decreases in water table levels increased methane oxidation but also net methane emission. Although methane emission was generally not observed during the winter, stems of soft rush (Juncus effusus) emitted methane when the marsh was ice covered. Indigenous methanotrophic bacteria from the wetiand studied were relatively anoxia tolerant. Surface peat incubated under anoxic conditions maintained 30% of the initial methane oxidation capacity after 32 days of anoxia. Methanotrophs from anoxic peat initiated aerobic methane oxidation relatively quickly after oxygen addition (1-7 hours). These results were supported by culture experiments with the methanotroph Methylosinus trichosporium OB3b. This organism maintained a greater capacity for aerobic methane oxidation when starved under anoxic compared to oxic conditions. Anoxic incubation of M. trichosporium OB3b in the presence of sulfide (2 mM) and a low redox potential (-110 mV) did not decrease the capacity for methane oxidation relative to anoxic cultures incubated without sulfide. The results suggest that aerobic methane oxidation was a major regulator of seasonal methane emission front the investigated wetland. The observed water table fluctuations affected net methane oxidation presumably due to associated changes in oxygen gradients. However, changes from oxic to anoxic conditions in situ had relatively little effect on survival of the methanotrophic

  6. Are methane production and cattle performance related?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methane is a product of fermentation of feed in ruminant animals. Approximately 2 -12% of the gross energy consumed by cattle is released through enteric methane production. There are three primary components that contribute to the enteric methane footprint of an animal. Those components are dry ...

  7. Explicit Microbial Processes to Simulate Methane Production and Oxidation in Wetlands in the GFDL Land Model

    NASA Astrophysics Data System (ADS)

    Smolander, S.; Sulman, B. N.; Shevliakova, E.

    2015-12-01

    Recent observational studies highlighted the need to include explicit treatment of the soil microbial processes into the next generation of Earth System Models (ESMs). These processes shape most soil biogeochemical cycles and control releases of the most potent greenhouses gases carbon dioxide and methane. Currently global ecosystem models usually parameterize methane production as a fraction of soil heterotrophic respiration. This lumps the pathways of several different functional groups of microbes into one production rate, possibly modified by a number of environmental factor multipliers. Methane oxidation is usually more explicitly modeled by Michaelis-Menten kinetics, but if the maximum rate, before environmental multipliers, is a constant parameter, this essentially implies a constant methanotrophic microbe population size. We present an explicit model for wetland soil microbial processes in an ESM context. We introduce a growth and decomposition model for four functional groups of microbes involved in methane production and oxidation, so microbial populations can grow when conditions are favorable and substrate is available. When soil conditions are anoxic, fermenting microbes transform available soil carbon into intermediate substrates, and two different kinds of methanogenic microbes live on their preferred substrates producing methane. Methane is transported through aerobic layers of the soil column, where methanotrophic microbes oxidize part of the methane, and the rest escapes to the atmosphere. We present initial simulations using the new model in the context of existing measurements of methane emissions and microbial populations at the site level, and discuss the implications of including these processes in an ESM. This explicit process model establishes a foundation for improving dynamic ecosystem-climate feedbacks in ESM simulations, and facilitates more detailed experimental verification of wetland biogeochemical processes.

  8. Energy from anaerobic methane production. [Sweden

    SciTech Connect

    Not Available

    1982-02-01

    Since 1970 Swedish researchers have been testing the ANAMET (anaerobic-aerobic-methane) process, which involves converting industrial wastewaters via an initial anaerobic microbiological step followed by an aerobic one. Recycling the biomass material in each step allows shorter hydraulic retention times without decreasing stability or solids reduction. Since the first ANAMET plants began operating at a Swedish sugar factory in 1972, 17 more plants have started up or are under construction. Moreover, the ANAMET process has engendered to offshoot BIOMET (biomass-methane) process, a thermophilic anaerobic scheme that can handle sugar-beet pulp as well as grass and other soft, fast-growing biomasses.

  9. Aerobic microorganism for the degradation of chlorinated aliphatic hydrocarbons

    DOEpatents

    Fliermans, Carl B.

    1989-01-01

    A chlorinated aliphatic hydrocarbon-degrading microorganism, having American Type Culture Collection accession numbers ATCC 53570 and 53571, in a biologically pure culture aseptically collected from a deep subsurface habitat and enhanced, mineralizes trichloroethylene and tetrachloroethylene to HCl, H.sub.2 O and Co.sub.2 under aerobic conditions stimulated by methane, acetate, methanol, tryptone-yeast extract, propane and propane-methane.

  10. Evaluation of Biodegradability of Waste Before and After Aerobic Treatment

    NASA Astrophysics Data System (ADS)

    Suchowska-Kisielewicz, Monika; Jędrczak, Andrzej; Sadecka, Zofia

    2014-12-01

    An important advantage of use of an aerobic biostabilization of waste prior to its disposal is that it intensifies the decomposition of the organic fraction of waste into the form which is easily assimilable for methanogenic microorganisms involved in anaerobic decomposition of waste in the landfill. In this article it is presented the influence of aerobic pre-treatment of waste as well as leachate recirculation on susceptibility to biodegradation of waste in anaerobic laboratory reactors. The research has shown that in the reactor with aerobically treated waste stabilized with recilculation conversion of the organic carbon into the methane is about 45% higher than in the reactor with untreated waste stabilized without recirculation.

  11. Teaching Aerobic Fitness Concepts.

    ERIC Educational Resources Information Center

    Sander, Allan N.; Ratliffe, Tom

    2002-01-01

    Discusses how to teach aerobic fitness concepts to elementary students. Some of the K-2 activities include location, size, and purpose of the heart and lungs; the exercise pulse; respiration rate; and activities to measure aerobic endurance. Some of the 3-6 activities include: definition of aerobic endurance; heart disease risk factors;…

  12. The regulation of methane oxidation in soil

    NASA Technical Reports Server (NTRS)

    Mancinelli, R. L.

    1995-01-01

    The atmospheric concentration of methane, a greenhouse gas, has more than doubled during the past 200 years. Consequently, identifying the factors influencing the flux of methane into the atmosphere is becoming increasingly important. Methanotrophs, microaerophilic organisms widespread in aerobic soils and sediments, oxidize methane to derive energy and carbon for biomass. In so doing, they play an important role in mitigating the flux of methane into the atmosphere. Several physico-chemical factors influence rates of methane oxidation in soil, including soil diffusivity; water potential; and levels of oxygen, methane, ammonium, nitrate, nitrite, and copper. Most of these factors exert their influence through interactions with methane monooxygenase (MMO), the enzyme that catalyzes the reaction converting methane to methanol, the first step in methane oxidation. Although biological factors such as competition and predation undoubtedly play a role in regulating the methanotroph population in soils, and thereby limit the amount of methane consumed by methanotrophs, the significance of these factors is unknown. Obtaining a better understanding of the ecology of methanotrophs will help elucidate the mechanisms that regulate soil methane oxidation.

  13. Carbon isotope fractionation during microbial methane oxidation

    NASA Astrophysics Data System (ADS)

    Barker, James F.; Fritz, Peter

    1981-09-01

    Methane, a common trace constituent of groundwaters, occasionally makes up more than 20% of the total carbon in groundwaters1,2. In aerobic environments CH4-rich waters can enable microbial food chain supporting a mixed culture of bacteria with methane oxidation as the primary energy source to develop3. Such processes may influence the isotopic composition of the residual methane and because 13C/12C analyses have been used to characterize the genesis of methanes found in different environments, an understanding of the magnitude of such effects is necessary. In addition, carbon dioxide produced by the methane-utilizing bacteria can be added to the inorganic carbon pool of affected groundwaters. We found carbon dioxide experimentally produced by methane-utilizing bacteria to be enriched in 12C by 5.0-29.6‰, relative to the residual methane. Where methane-bearing groundwaters discharged into aerobic environments microbial methane oxidation occurred, with the residual methane becoming progressively enriched in 13C. Various models have been proposed to explain the 13C/12C and 14C content of the dissolved inorganic carbon (DIC) of groundwaters in terms of additions or losses during flow in the subsurface4,5. The knowledge of both stable carbon isotope ratios in various pools and the magnitude of carbon isotope fractionation during various processes allows geochemists to use the 13C/12C ratio of the DIC along with water chemistry to estimate corrected 14C groundwater ages4,5. We show here that a knowledge of the carbon isotope fractionation between CH4 and CO2 during microbial methane-utilization could modify such models for application to groundwaters affected by microbial methane oxidation.

  14. Reductive dechlorination of Tri- and tetrachloroethylenes depends on transition from aerobic to anaerobic conditions.

    PubMed Central

    Kästner, M

    1991-01-01

    Aerobic enrichment cultures from contaminated groundwaters dechlorinated trichloroethylene (TCE) (14.6 mg/liter; 111 mumol/liter) and tetrachloroethylene (PCE) (16.2 mg/liter; 98 mumol/liter) reductively within 4 days after the transition from aerobic to anaerobic conditions. The transformation products were equimolar amounts of cis-1,2-dichloroethylene and traces of 1,1-dichloroethylene. No other chlorinated product and no methane were detected. The change was accompanied by the release of sulfide, which caused a decrease in the redox potential from 0 to -150 mV. In sterile control experiments, sulfide led to the abiotic formation of traces of 1,1-dichloroethylene without cis-1,2-dichloroethylene production. The reductive dechlorination of PCE via TCE depended on these specific transition conditions after consumption of the electron acceptor oxygen or nitrate. Repeated feeding of TCE or PCE to cultures after the change to anaerobic conditions yielded no further dechlorination. Only aerobic subcultures with an air/liquid ratio of 1:4 maintained dechlorination activities; anaerobic subcultures showed no transformation. Bacteria from noncontaminated sites showed no reduction under the same conditions. PMID:1892393

  15. Comparison of aerobic and anaerobic biotreatment of municipal solid waste.

    PubMed

    Borglin, Sharon E; Hazen, Terry C; Oldenburg, Curtis M; Zawislanski, Peter T

    2004-07-01

    To increase the operating lifetime of landfills and to lower leachate treatment costs, an increasing number of municipal solid waste (MSW) landfills are being managed as either aerobic or anaerobic bioreactors. Landfill gas composition, respiration rates, and subsidence were measured for 400 days in 200-L tanks filled with fresh waste materials to compare the relative effectiveness of the two treatments. Tanks were prepared to provide the following conditions: (1) air injection and leachate recirculation (aerobic), (2) leachate recirculation (anaerobic), and (3) no treatment (anaerobic). Respiration tests on the aerobic wet tank showed a steady decrease in oxygen consumption rates from 1.3 mol/day at 20 days to 0.1 mol/day at 400 days. Aerobic wet tanks produced, on average, 6 mol of carbon dioxide (CO2)/kg of MSW as compared with anaerobic wet tanks, which produced 2.2 mol methane/kg of MSW and 2.0 mol CO2/kg methane. Over the test period, the aerobic tanks settled on average 35%, anaerobic tanks settled 21.7%, and the no-treatment tank settled 7.5%, equivalent to overall mass loss in the corresponding reactors. Aerobic tanks reduced stabilization time and produced negligible odor compared with anaerobic tanks, possibly because of the 2 orders of magnitude lower leachate ammonia levels in the aerobic tank. Both treatment regimes provide the opportunity for disposal and remediation of liquid waste.

  16. Effectiveness of a polyamide film releasing lactic acid on the growth of E. coli O157:H7, Enterobacteriaceae and Total Aerobic Count on vacuum-packed beef.

    PubMed

    Smulders, F J M; Paulsen, P; Vali, S; Wanda, S

    2013-10-01

    The suitability of a polyamide 6 monolayer film containing lactic acid for use as an antimicrobial package for fresh beef cuts was studied. The release of lactic acid in an aqueous environment was immediate (within 1h) and was from approx. 55 μg lactic acid/cm(2) film at 0-8°C to approx. 67 μg lactic acid/cm(2) film at 12-20°C. Beef was contaminated with an Escherichia coli O157:H7 isolate with known minimum inhibitory concentration against lactic acid (0.09% v/v), then wrapped with the lactic-acid polyamide film and vacuum packaged. During storage at 12°C, the numbers of E. coli were 1 log unit lower than that of a control (untreated polyamide film) and decreased by an additional 1 log during storage for 14 days.

  17. Methane sources and production in the northern Cascadia margin gas hydrate system

    USGS Publications Warehouse

    Pohlman, J.W.; Kaneko, M.; Heuer, V.B.; Coffin, R.B.; Whiticar, M.

    2009-01-01

    The oceanographic and tectonic conditions of accretionary margins are well-suited for several potential processes governing methane generation, storage and release. To identify the relevant methane evolution pathways in the northern Cascadia accretionary margin, a four-site transect was drilled during Integrated Ocean Drilling Program Expedition 311. The ??13C values of methane range from a minimum value of - 82.2??? on an uplifted ridge of accreted sediment near the deformation front (Site U1326, 1829 mbsl, meters below sea level) to a maximum value of - 39.5??? at the most landward location within an area of steep canyons near the shelf edge (Site U1329, 946 mbsl). An interpretation based solely on methane isotope values might conclude the 13C-enrichment of methane indicates a transition from microbially- to thermogenically-sourced methane. However, the co-existing CO2 exhibits a similar trend of 13C-enrichment along the transect with values ranging from - 22.5??? to +25.7???. The magnitude of the carbon isotope separation between methane and CO2 (??c = 63.8 ?? 5.8) is consistent with isotope fractionation during microbially mediated carbonate reduction. These results, in conjunction with a transect-wide gaseous hydrocarbon content composed of > 99.8% (by volume) methane and uniform ??DCH4 values (- 172??? ?? 8) that are distinct from thermogenic methane at a seep located 60 km from the Expedition 311 transect, suggest microbial CO2 reduction is the predominant methane source at all investigated sites. The magnitude of the intra-site downhole 13C-enrichment of CO2 within the accreted ridge (Site U1326) and a slope basin nearest the deformation front (Site U1325, 2195 mbsl) is ~ 5???. At the mid-slope site (Site U1327, 1304 mbsl) the downhole 13C-enrichment of the CO2 is ~ 25??? and increases to ~ 40??? at the near-shelf edge Site U1329. This isotope fractionation pattern is indicative of more extensive diagenetic alteration at sites with greater 13C

  18. Arctic permafrost: Microbial lid on subsea methane

    NASA Astrophysics Data System (ADS)

    Thornton, Brett F.; Crill, Patrick

    2015-08-01

    Submarine permafrost thaw in the Arctic has been suggested as a trigger for the release of large quantities of methane to the water column, and subsequently the atmosphere -- with important implications for global warming. Now research shows that microbial oxidation of methane at the thaw front can effectively prevent its release.

  19. [Application of cowl in semi-aerobic landfill and its influence in initial stage].

    PubMed

    Han, Dan; Zhao, You-cai; Xue, Bin-jie; Gao, Pin

    2009-10-15

    Enhancement of semi-aerobic landfill performance through a cowl installed on the gas ventilation pipeline using a simulated landfill box with 2 m x 1 m x 2 m in size was investigated, aiming at the maximum methane emission reduction. Influence of cowl on semi-aerobic environment formation was explored, and variety of methane and carbon dioxide concentrations at different wind speeds and mechanism of cowl operation were identified to provide information on design and improvement of semi-aerobic landfill. The results show that the cowl speeds up the semi-aerobic environment to shape, from over 50 days down to approximately 40 days, and reduces methane emission by promoting methane transformation to carbon dioxide. When the cowl is taken off suddenly during the normal operation, carbon dioxide concentration falls to 15.88% from the initial 16.67% immediately, and methane concentration increases to 16.12% from 6.14%. However, the carbon dioxide and methane concentration becomes 19.18% and 10.05%, respectively, as the cowl is taken on again. Additionally, methane emissions in the exhaust gas were monitored at different wind speeds of 2.0, 3.5, 5.0, 6.5, 8.0 m/s, and finds that the methane concentration reduces from the initial 15% to below 5% when the wind speed increases from 2 m/s to 8 m/s.

  20. [Research progress in microbial methane oxidation coupled to denitrification].

    PubMed

    Zhu, Jing; Yuan, Meng-Dong; Liu, Jing-Jing; Huang, Xiao-Xiao; Wu, Wei-Xiang

    2013-12-01

    Methane oxidation coupled to denitrification is an essential bond to connect carbon- and nitrogen cycling. To deeply research this process will improve our understanding on the biochemical cycling of global carbon and nitrogen. As an exogenous gaseous carbon source of denitrification, methane can both regulate the balance of atmospheric methane to effectively mitigate the greenhouse effect caused by methane, and reduce the cost of exogenous carbon source input in traditional wastewater denitrification treatment process. As a result, great attention has being paid to the mechanical study of the process. This paper mainly discussed the two types of methane oxidation coupled to denitrification, i. e., aerobic methane oxidation coupled to denitrification (AME-D) and anaerobic methane oxidation coupled to denitrification (ANME-D), with the focus on the microbiological coupling mechanisms and related affecting factors. The existing problems in the engineering application of methane oxidation coupled to denitrification were pointed out, and the application prospects were approached. PMID:24697087

  1. [Research progress in microbial methane oxidation coupled to denitrification].

    PubMed

    Zhu, Jing; Yuan, Meng-Dong; Liu, Jing-Jing; Huang, Xiao-Xiao; Wu, Wei-Xiang

    2013-12-01

    Methane oxidation coupled to denitrification is an essential bond to connect carbon- and nitrogen cycling. To deeply research this process will improve our understanding on the biochemical cycling of global carbon and nitrogen. As an exogenous gaseous carbon source of denitrification, methane can both regulate the balance of atmospheric methane to effectively mitigate the greenhouse effect caused by methane, and reduce the cost of exogenous carbon source input in traditional wastewater denitrification treatment process. As a result, great attention has being paid to the mechanical study of the process. This paper mainly discussed the two types of methane oxidation coupled to denitrification, i. e., aerobic methane oxidation coupled to denitrification (AME-D) and anaerobic methane oxidation coupled to denitrification (ANME-D), with the focus on the microbiological coupling mechanisms and related affecting factors. The existing problems in the engineering application of methane oxidation coupled to denitrification were pointed out, and the application prospects were approached.

  2. Methane conversion

    SciTech Connect

    Jones, C.A.; Leonard, J.J.; Sofranko, J.A.

    1984-04-17

    Another version of Arco's process for reforming methane or natural gas into a synthesis gas uses bismuth oxide as the reforming agent; it also requires no nickel or noble metal catalyst. The methane-containing gas contacts bismuth oxide at temperatures of 900/sup 0/-1560/sup 0/F. The oxide is reduced by methane and easily regenerated with an oxygen-containing gas. The oxide Bi/sub 2/O/sub 3/ is a particularly effective synthesizing agent.

  3. Combustion of Methane Hydrate

    NASA Astrophysics Data System (ADS)

    Roshandell, Melika

    A significant methane storehouse is in the form of methane hydrates on the sea floor and in the arctic permafrost. Methane hydrates are ice-like structures composed of water cages housing a guest methane molecule. This caged methane represents a resource of energy and a potential source of strong greenhouse gas. Most research related to methane hydrates has been focused on their formation and dissociation because they can form solid plugs that complicate transport of oil and gas in pipelines. This dissertation explores the direct burning of these methane hydrates where heat from the combustion process dissociates the hydrate into water and methane, and the released methane fuels the methane/air diffusion flame heat source. In contrast to the pipeline applications, very little research has been done on the combustion and burning characteristics of methane hydrates. This is the first dissertation on this subject. In this study, energy release and combustion characteristics of methane hydrates were investigated both theoretically and experimentally. The experimental study involved collaboration with another research group, particularly in the creation of methane hydrate samples. The experiments were difficult because hydrates form at high pressure within a narrow temperature range. The process can be slow and the resulting hydrate can have somewhat variable properties (e.g., extent of clathration, shape, compactness). The experimental study examined broad characteristics of hydrate combustion, including flame appearance, burning time, conditions leading to flame extinguishment, the amount of hydrate water melted versus evaporated, and flame temperature. These properties were observed for samples of different physical size. Hydrate formation is a very slow process with pure water and methane. The addition of small amounts of surfactant increased substantially the hydrate formation rate. The effects of surfactant on burning characteristics were also studied. One finding

  4. Terrestrial plant methane production and emission.

    PubMed

    Bruhn, Dan; Møller, Ian M; Mikkelsen, Teis N; Ambus, Per

    2012-03-01

    In this minireview, we evaluate all experimental work published on the phenomenon of aerobic methane (CH(4) ) generation in terrestrial plants and plant. Clearly, despite much uncertainty and skepticism, we conclude that the phenomenon is true. Four stimulating factors have been observed to induce aerobic plant CH(4) production, i.e. cutting injuries, increasing temperature, ultraviolet radiation and reactive oxygen species. Further, we analyze rates of measured emission of aerobically produced CH(4) in pectin and in plant tissues from different studies and argue that pectin is very far from the sole contributing precursor. In consequence, scaling up of aerobic CH(4) emission needs to take into consideration other potential sources than pectin. Due to the large uncertainties related to effects of stimulating factors, genotypic responses and type of precursors, we conclude that current attempts for upscaling aerobic CH(4) into a global budget is inadequate. Thus it is too early to draw the line under the aerobic methane emission in plants. Future work is needed for establishing the relative contribution of several proven potential CH(4) precursors in plant material.

  5. Potential methane production and methane oxidation rates in peatland ecosystems of the Appalachian Mountains, United States

    SciTech Connect

    Yavitt, J.B.; Lang, G.E.; Downey, D.M. )

    1988-09-01

    Potential rates of methane production and carbon dioxide production were measured on 11 dates in 1986 in peat from six plant communities typical of moss-dominated peatlands in the Appalachian Mountains. Annual methane production ranged from 2.7 to 17.5 mol/sq m, and annual carbon dioxide production ranged from 30.6 to 79.0 mol/sq m. The wide range in methane production values among the communities found within a single peatland indicates that obtaining one production value for a peatland may not be appropriate. Low temperature constrained the potential for methane production in winter, while the chemical quality of the peat substrate appears to control methane production in the summer. Methane oxidation was measured throughout the peat profile to a depth of 30 cm. Values for methane oxidation ranged from 0.08 to 18.7 microM/hr among the six plant communities. Aerobic methane-oxidizing bacteria probably mediated most of the activity. On a daily basis during the summer, between 11 and 100% of the methane produced is susceptible to oxidation within the peat column. Pools of dissolved methane and dissolved carbon dioxide in pore waters were less than 0.2 and less than 1.0 mol/sq m, respectively, indicating that methane does not accumulate in the pore waters. Peatlands have been considered as an important source of biologically produced methane. Despite the high rates of methane production, the high rates of methane oxidation dampen the potential emission of methane to the atmosphere. 41 refs., 7 figs., 4 tabs.

  6. Sinking methane.

    PubMed

    Reay, David S

    2003-02-01

    Concentrations of the powerful greenhouse gas, methane, in our atmosphere have doubled since the beginning of the industrial age. Reducing these levels is a vital part of global efforts to combat global warming. Could we make use of the Earth's own methane sinks?

  7. Redefining the isotopic boundaries of biogenic methane: Methane from endoevaporites

    NASA Astrophysics Data System (ADS)

    Tazaz, Amanda M.; Bebout, Brad M.; Kelley, Cheryl A.; Poole, Jennifer; Chanton, Jeffrey P.

    2013-06-01

    The recent reports of methane in the atmosphere of Mars, as well as the findings of hypersaline paleoenvironments on that planet, have underscored the need to evaluate the importance of biological (as opposed to geological) trace gas production and consumption, particularly in hypersaline environments. Methane in the atmosphere of Mars may be an indication of extant life, but it may also be a consequence of geologic activity and/or the thermal alteration of ancient organic matter. On Earth these methane sources can be distinguished using stable isotopic analyses and the ratio of methane (C1) to C2 and C3 alkanes present in the gas source (C1/(C2 + C3)). We report here that methane produced in hypersaline environments on Earth has an isotopic composition and alkane content outside the values presently considered to indicate a biogenic origin. Methane-rich bubbles released from sub-aqueous substrates contained δ13CCH4 and δ2HCH4 values ranging from -65‰ to -35‰ and -350‰ to -140‰ respectively. Higher salinity endoevaporites yielded what would be considered non-biogenic methane based upon stable isotopic and alkane content, however incubation of crustal and algal mat samples resulted in methane production with similar isotopic values. Radiocarbon analysis indicated that the production of the methane was from recently fixed carbon. An extension of the isotopic boundaries of biogenic methane is necessary in order to avoid the possibility of false negatives returned from measurements of methane on Mars and other planetary bodies.

  8. Methane oxidation linked to chlorite dismutation

    PubMed Central

    Miller, Laurence G.; Baesman, Shaun M.; Carlström, Charlotte I.; Coates, John D.; Oremland, Ronald S.

    2014-01-01

    We examined the potential for CH4 oxidation to be coupled with oxygen derived from the dissimilatory reduction of perchlorate, chlorate, or via chlorite (ClO−2) dismutation. Although dissimilatory reduction of ClO−4 and ClO−3 could be inferred from the accumulation of chloride ions either in spent media or in soil slurries prepared from exposed freshwater lake sediment, neither of these oxyanions evoked methane oxidation when added to either anaerobic mixed cultures or soil enriched in methanotrophs. In contrast, ClO−2 amendment elicited such activity. Methane (0.2 kPa) was completely removed within several days from the headspace of cell suspensions of Dechloromonas agitata CKB incubated with either Methylococcus capsulatus Bath or Methylomicrobium album BG8 in the presence of 5 mM ClO−2. We also observed complete removal of 0.2 kPa CH4 in bottles containing soil enriched in methanotrophs when co-incubated with D. agitata CKB and 10 mM ClO−2. However, to be effective these experiments required physical separation of soil from D. agitata CKB to allow for the partitioning of O2 liberated from chlorite dismutation into the shared headspace. Although a link between ClO−2 and CH4 consumption was established in soils and cultures, no upstream connection with either ClO−4 or ClO−3 was discerned. This result suggests that the release of O2 during enzymatic perchlorate reduction was negligible, and that the oxygen produced was unavailable to the aerobic methanotrophs. PMID:24987389

  9. Methane oxidation linked to chlorite dismutation

    USGS Publications Warehouse

    Miller, Laurence G.; Baesman, Shaun M.; Carlström, Charlotte I.; Coates, John D.; Oremland, Ronald S.

    2014-01-01

    We examined the potential for CH4 oxidation to be coupled with oxygen derived from the dissimilatory reduction of perchlorate, chlorate, or via chlorite (ClO−2) dismutation. Although dissimilatory reduction of ClO−4 and ClO−3 could be inferred from the accumulation of chloride ions either in spent media or in soil slurries prepared from exposed freshwater lake sediment, neither of these oxyanions evoked methane oxidation when added to either anaerobic mixed cultures or soil enriched in methanotrophs. In contrast, ClO−2 amendment elicited such activity. Methane (0.2 kPa) was completely removed within several days from the headspace of cell suspensions of Dechloromonas agitata CKB incubated with either Methylococcus capsulatus Bath or Methylomicrobium album BG8 in the presence of 5 mM ClO−2. We also observed complete removal of 0.2 kPa CH4 in bottles containing soil enriched in methanotrophs when co-incubated with D. agitata CKB and 10 mM ClO−2. However, to be effective these experiments required physical separation of soil from D. agitata CKB to allow for the partitioning of O2 liberated from chlorite dismutation into the shared headspace. Although a link between ClO−2 and CH4 consumption was established in soils and cultures, no upstream connection with either ClO−4 or ClO−3 was discerned. This result suggests that the release of O2 during enzymatic perchlorate reduction was negligible, and that the oxygen produced was unavailable to the aerobic methanotrophs.

  10. Large methane reserves beneath Antarctica?

    NASA Astrophysics Data System (ADS)

    Wadham, J. L.; Tulaczyk, S. M.; Stibal, M.; Arndt, S.; Telling, J.; Lis, G.; Lawson, E. C.; Dubnick, A.; Tranter, M.; Sharp, M. J.; Anesio, A.

    2010-12-01

    Once thought to be devoid of life, the Antarctic Ice Sheet is now known to be a dynamic reservoir of metabolically active microbial cells and organic carbon. Its potential to support the degradation of organic carbon to methane, however, has not yet been evaluated. Large marine sedimentary basins beneath the ice sheet (estimated to cover up to 50% by area and contain sedimentary sequences up to 3 km thick) remain thawed during glaciation. These basins are estimated to contain ~7000 Pg of organic carbon, assuming that sedimentary basins account for 1 and 2 M km2 of the West and East Antarctic Ice Sheets respectively, the organic carbon content of overridden marine sediments is 0.5 % and the mean sediment depth is 1 km. We predict that this carbon is microbially cycled to methane under anoxic conditions beneath the ice sheet. Laboratory experimental data are consistent with this and show that organic carbon overridden by glaciers and ice sheets produces methane under anoxic conditions, and at rates similar to those observed in sub-seafloor sediments. We numerically model the accumulation of methane in Antarctic sedimentary basins and show that sediment porewaters become over-saturated with methane over >1 Myr and that typical pressure/temperature conditions favour methane hydrate formation down to between ~500m and ~1000m in the sedimentary column. We calculate conservatively that a minimum of ~70 and ~360 PgC of releasable methane (clathrate + free gas) could be produced beneath the West and East Antarctic Ice Sheets over 3 and 30 Myr of glaciation respectively, which is of a similar order of magnitude to methane present as hydrate in Arctic permafrost. The stability of this releasable methane reserve depends sensitively upon in situ pressure conditions, and hence ice thickness. We show that only modest ice sheet retreat rates (700-2000 km2 a-1) are required to stimulate out gassing of releasable methane from Antarctic sedimentary basins at rates sufficient to

  11. Breaking methane

    PubMed Central

    Rosenzweig, Amy C.

    2015-01-01

    The most powerful oxidant found in nature is compound Q, an enzymatic intermediate that oxidizes methane. New spectroscopic data have resolved the long-running controversy about Q’s chemical structure. PMID:25607367

  12. Harnessing methane

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    The total methane resource in hydrates—ice-like substances found in deep ocean sediments and Arctic permafrost—exceeds the energy content of all other fossil fuel resources,such as coal, oil, and conventional gas, according to the U.S. Geological Survey (USGS).The Methane Hydrate Research and Development Act, signed into law by U.S. President Bill Clinton on May 3, establishes a new federal commitment to developing methane hydrates, which has been touted as a potentially clean energy source that could make the U.S. less dependent on foreign sources of energy. The bill authorizes $47.5 million over five years for the Department of Energy to establish a federal methane hydrate research and development program.

  13. Carbon isotope (δ13C) excursions suggest times of major methane release during the last 14 kyr in Fram Strait, the deep-water gateway to the Arctic

    NASA Astrophysics Data System (ADS)

    Consolaro, C.; Rasmussen, T. L.; Panieri, G.; Mienert, J.; Bünz, S.; Sztybor, K.

    2015-04-01

    We present results from a sediment core collected from a pockmark field on the Vestnesa Ridge (~ 80° N) in the eastern Fram Strait. This is the only deep-water gateway to the Arctic, and one of the northernmost marine gas hydrate provinces in the world. Eight 14C AMS dates reveal a detailed chronology for the last 14 ka BP. The δ 13C record measured on the benthonic foraminiferal species Cassidulina neoteretis shows two distinct intervals with negative values termed carbon isotope excursion (CIE I and CIE II, respectively). The values were as low as -4.37‰ in CIE I, correlating with the Bølling-Allerød interstadials, and as low as -3.41‰ in CIE II, correlating with the early Holocene. In the Bølling-Allerød interstadials, the planktonic foraminifera also show negative values, probably indicating secondary methane-derived authigenic precipitation affecting the foraminiferal shells. After a cleaning procedure designed to remove authigenic carbonate coatings on benthonic foraminiferal tests from this event, the 13C values are still negative (as low as -2.75‰). The CIE I and CIE II occurred during periods of ocean warming, sea-level rise and increased concentrations of methane (CH4) in the atmosphere. CIEs with similar timing have been reported from other areas in the North Atlantic, suggesting a regional event. The trigger mechanisms for such regional events remain to be determined. We speculate that sea-level rise and seabed loading due to high sediment supply in combination with increased seismic activity as a result of rapid deglaciation may have triggered the escape of significant amounts of methane to the seafloor and the water column above.

  14. Thermal properties of methane gas hydrates

    USGS Publications Warehouse

    Waite, William F.

    2007-01-01

    Gas hydrates are crystalline solids in which molecules of a “guest” species occupy and stabilize cages formed by water molecules. Similar to ice in appearance (fig. 1), gas hydrates are stable at high pressures and temperatures above freezing (0°C). Methane is the most common naturally occurring hydrate guest species. Methane hydrates, also called simply “gas hydrates,” are extremely concentrated stores of methane and are found in shallow permafrost and continental margin sediments worldwide. Brought to sea-level conditions, methane hydrate breaks down and releases up to 160 times its own volume in methane gas. The methane stored in gas hydrates is of interest and concern to policy makers as a potential alternative energy resource and as a potent greenhouse gas that could be released from sediments to the atmosphere and ocean during global warming. In continental margin settings, methane release from gas hydrates also is a potential geohazard and could cause submarine landslides that endanger offshore infrastructure. Gas hydrate stability is sensitive to temperature changes. To understand methane release from gas hydrate, the U.S. Geological Survey (USGS) conducted a laboratory investigation of pure methane hydrate thermal properties at conditions relevant to accumulations of naturally occurring methane hydrate. Prior to this work, thermal properties for gas hydrates generally were measured on analog systems such as ice and non-methane hydrates or at temperatures below freezing; these conditions limit direct comparisons to methane hydrates in marine and permafrost sediment. Three thermal properties, defined succinctly by Briaud and Chaouch (1997), are estimated from the experiments described here: - Thermal conductivity, λ: if λ is high, heat travels easily through the material. - Thermal diffusivity, κ: if κ is high, it takes little time for the temperature to rise in the material. - Specific heat, cp: if cp is high, it takes a great deal of heat to

  15. Aerobic Conditioning Class.

    ERIC Educational Resources Information Center

    Johnson, Neil R.

    1980-01-01

    An aerobic exercise class that focuses on the conditioning of the cardiovascular and muscular systems is presented. Students complete data cards on heart rate, pulse, and exercises to be completed during the forty minute course. (CJ)

  16. Dairy livestock methane remediation and global warming.

    PubMed

    Nusbaum, Neil J

    2010-10-01

    One of the major greenhouse gases is the methane released from ruminants. Greenhouse gas emissions in the agricultural portion of the economy may benefit from biologically based remediation strategies, including potential use of probiotics in animal husbandry. A broad range of disciplines (including climatologists, microbiologists, biochemists, physical chemists, agricultural economists) can assist in biological strategies to reduce agricultural methane emissions.

  17. Anaerobic digestion of dairy cattle manure autoheated by aerobic pretreatment

    SciTech Connect

    Achkari-Begdouri, A.

    1989-01-01

    A novel way to heat anaerobic digesters was investigated. Dairy cattle manure was autoheated by an aerobic pretreatment process and then fed to the anaerobic digester. Important physical properties of the dairy cattle manure were determined. These included bulk density, specific heat, thermal conductivity and the rheological properties; consistency coefficient, behavior index and apparent viscosity. These parameters were used to calculate the overall heat transfer coefficients, and to estimate the heat losses from the aerobic reactor to the outside environment. The total energy balance of the aerobic treatment system was then established. An optimization study of the main parameters influencing the autoheating process showed that the total solids, the air flow rate and the stirring speed for operation of the aerobic pretreatment should be approximately 7%, 70 L/H and 1,400 rpm respectively. Temperatures as high as 65C were reached in 40 hours of aerobic treatment. At the above recommended levels of total solids, the air flow rate and the stirring speed, there was little difference in the energy requirements for heating the influent by aeration and heating the influent by a conventional heating system. In addition to the temperature increase, the aerobic pretreatment assisted in balancing the anaerobic digestion process and increased the methanogenesis of the dairy cattle manure. Despite the 8% decomposition of organic matter that occurred during the aerobic pretreatment process, methane production of the digester started with the aerobically heated manure was significantly higher (at least 20% higher) than of the digester started with conventionally heated manure. The aerobic system successfully autoheated the dairy cattle manure with an energy cost equal to that of conventionally heated influent.

  18. Methane in permafrost - Preliminary results from coring at Fairbanks, Alaska

    USGS Publications Warehouse

    Kvenvolden, K.A.; Lorenson, T.D.

    1993-01-01

    Permafrost has been suggested as a high-latitude source of methane (a greenhouse gas) during global warming. To begin to assess the magnitude of this source, we have examined the methane content of permafrost in samples from shallow cores (maximum depth, 9.5m) at three sites in Fairbanks, Alaska, where discontinuous permafrost is common. These cores sampled frozen loess, peat, and water (ice) below the active layer. Methane contents of permafrost range from <0.001 to 22.2mg/kg of sample. The highest methane content of 22.2mg/kg was found in association with peat at one site. Silty loess had high methane contents at each site of 6.56, 4.24, and 0.152mg/kg, respectively. Carbon isotopic compositions of the methane (??13C) ranged from -70.8 to -103.9 ???, and hydrogen isotopic compositions of the methane (??D) from -213 to -313 ???, indicating that the methane is microbial in origin. The methane concentrations were used in a one dimensional heat conduction model to predict the amount of methane that will be released from permafrost worldwide over the next 100 years, given two climate change scenarios. Our results indicate that at least 30 years will elapse before melting permafrost releases important amounts of methane; a maximum methane release rate will be about 25 to 30 Tg/yr, assuming that methane is generally distributed in shallow permafrost as observed in our samples.

  19. Trichloroethylene Biodegradation by a Methane-Oxidizing Bacterium †

    PubMed Central

    Little, C. Deane; Palumbo, Anthony V.; Herbes, Stephen E.; Lidstrom, Mary E.; Tyndall, Richard L.; Gilmer, Penny J.

    1988-01-01

    Trichloroethylene (TCE), a common groundwater contaminant, is a suspected carcinogen that is highly resistant to aerobic biodegradation. An aerobic, methane-oxidizing bacterium was isolated that degrades TCE in pure culture at concentrations commonly observed in contaminated groundwater. Strain 46-1, a type I methanotrophic bacterium, degraded TCE if grown on methane or methanol, producing CO2 and water-soluble products. Gas chromatography and 14C radiotracer techniques were used to determine the rate, methane dependence, and mechanism of TCE biodegradation. TCE biodegradation by strain 46-1 appears to be a cometabolic process that occurs when the organism is actively metabolizing a suitable growth substrate such as methane or methanol. It is proposed that TCE biodegradation by methanotrophs occurs by formation of TCE epoxide, which breaks down spontaneously in water to form dichloroacetic and glyoxylic acids and one-carbon products. Images PMID:16347616

  20. [Study on technological characters of anaerobic-aerobic bioreactor landfill].

    PubMed

    Chen, Zhu-Lei; Zhou, Chuan-Bin; Liu, Ting; Jiang, Juan; Cao, Li; Lü, Zhi-Zhong; Li, Xi-Kun; Li, Xiao-Bao

    2007-04-01

    A technology of anaerobic-aerobic landfill bioreactor aimed at reusing landfill site is studied, and it's based on landfill bioreactor technology. A set of stimulating equipment is designed, and the technology characters are studied. In the anaerobic period, technological conditions are controlled by the means of leachate recirculation. The main experimental results are: pH, R1 rises to 6.7 - 7.8 in 6 weeks, and R2 is under 6.8 in 17 weeks; COD concentration of leachate, R1 declines to 10 617 mg/L in 13 weeks, while R2 rises to 60 000 mg/L in 5 weeks, and keeps stabilization in long time; the cumulating methane production, R1 reaches 44% in 8 weeks, while R2 almost cannot produce methane. The stabilization can be evaluated by pH of leachate, COD and BOD5/COD decreasing ratio, and cumulating methane production. They are main evidences to transform anaerobic period to aerobic period. In the aerobic period, odor and moisture are reduced by the means of aeration. The main experimental results are: ammonia concentration reduces to 1.16 mg/m3 in 19 days, and the odor concentration reduces to 19 in 23 days; the moisture of the wastes reduces to 26% in 14 days. The technological indexes to evaluate finishing of this period can be determined by the ultimately purpose of exploited wastes. Numerical modeling has been researched with the use of experimental data. The succession of microbes in the anaerobic-aerobic course is studied by RISA (ribosomal intergenic spacer analysis) analysis. There are 4 preponderant groups in this course, and some facultative anaerobes play important roles in the transition of anaerobic period to aerobic period.

  1. Methane clathrates in the solar system.

    PubMed

    Mousis, Olivier; Chassefière, Eric; Holm, Nils G; Bouquet, Alexis; Waite, Jack Hunter; Geppert, Wolf Dietrich; Picaud, Sylvain; Aikawa, Yuri; Ali-Dib, Mohamad; Charlou, Jean-Luc; Rousselot, Philippe

    2015-04-01

    We review the reservoirs of methane clathrates that may exist in the different bodies of the Solar System. Methane was formed in the interstellar medium prior to having been embedded in the protosolar nebula gas phase. This molecule was subsequently trapped in clathrates that formed from crystalline water ice during the cooling of the disk and incorporated in this form into the building blocks of comets, icy bodies, and giant planets. Methane clathrates may play an important role in the evolution of planetary atmospheres. On Earth, the production of methane in clathrates is essentially biological, and these compounds are mostly found in permafrost regions or in the sediments of continental shelves. On Mars, methane would more likely derive from hydrothermal reactions with olivine-rich material. If they do exist, martian methane clathrates would be stable only at depth in the cryosphere and sporadically release some methane into the atmosphere via mechanisms that remain to be determined. In the case of Titan, most of its methane probably originates from the protosolar nebula, where it would have been trapped in the clathrates agglomerated by the satellite's building blocks. Methane clathrates are still believed to play an important role in the present state of Titan. Their presence is invoked in the satellite's subsurface as a means of replenishing its atmosphere with methane via outgassing episodes. The internal oceans of Enceladus and Europa also provide appropriate thermodynamic conditions that allow formation of methane clathrates. In turn, these clathrates might influence the composition of these liquid reservoirs. Finally, comets and Kuiper Belt Objects might have formed from the agglomeration of clathrates and pure ices in the nebula. The methane observed in comets would then result from the destabilization of clathrate layers in the nuclei concurrent with their approach to perihelion. Thermodynamic equilibrium calculations show that methane-rich clathrate

  2. Methane clathrates in the solar system.

    PubMed

    Mousis, Olivier; Chassefière, Eric; Holm, Nils G; Bouquet, Alexis; Waite, Jack Hunter; Geppert, Wolf Dietrich; Picaud, Sylvain; Aikawa, Yuri; Ali-Dib, Mohamad; Charlou, Jean-Luc; Rousselot, Philippe

    2015-04-01

    We review the reservoirs of methane clathrates that may exist in the different bodies of the Solar System. Methane was formed in the interstellar medium prior to having been embedded in the protosolar nebula gas phase. This molecule was subsequently trapped in clathrates that formed from crystalline water ice during the cooling of the disk and incorporated in this form into the building blocks of comets, icy bodies, and giant planets. Methane clathrates may play an important role in the evolution of planetary atmospheres. On Earth, the production of methane in clathrates is essentially biological, and these compounds are mostly found in permafrost regions or in the sediments of continental shelves. On Mars, methane would more likely derive from hydrothermal reactions with olivine-rich material. If they do exist, martian methane clathrates would be stable only at depth in the cryosphere and sporadically release some methane into the atmosphere via mechanisms that remain to be determined. In the case of Titan, most of its methane probably originates from the protosolar nebula, where it would have been trapped in the clathrates agglomerated by the satellite's building blocks. Methane clathrates are still believed to play an important role in the present state of Titan. Their presence is invoked in the satellite's subsurface as a means of replenishing its atmosphere with methane via outgassing episodes. The internal oceans of Enceladus and Europa also provide appropriate thermodynamic conditions that allow formation of methane clathrates. In turn, these clathrates might influence the composition of these liquid reservoirs. Finally, comets and Kuiper Belt Objects might have formed from the agglomeration of clathrates and pure ices in the nebula. The methane observed in comets would then result from the destabilization of clathrate layers in the nuclei concurrent with their approach to perihelion. Thermodynamic equilibrium calculations show that methane-rich clathrate

  3. A New Screening Method for Methane in Soil Gas Using Existing Groundwater Monitoring Wells

    EPA Science Inventory

    Methane in soil gas may have undesirable consequences. The soil gas may be able to form a flammable mixture with air and present an explosion hazard. Aerobic biodegradation of the methane in soil gas may consume oxygen that would otherwise be available for biodegradation of gasol...

  4. Pingos, craters and methane-leaking seafloor in the central Barents Sea: signals of decomposing gas hydrate releasing gas from deeper hydrocarbon reservoirs?

    NASA Astrophysics Data System (ADS)

    Andreassen, K.; Plaza-Faverola, A. A.; Winsborrow, M.; Deryabin, A.; Mattingsdal, R.; Vadakkepuliyambatta, S.; Serov, P.; Mienert, J.; Bünz, S.

    2015-12-01

    A cluster of large craters and mounds appear on the gas-leaking sea floor in the central Barents Sea around the upper limit for methane hydrate stability, covering over 360 km2. We use multibeam bathymetry, single-beam echo sounder and high-resolution seismic data to reveal the detailed geomorphology and internal structure of craters and mounds, map the distribution gas in the water and to unravel the subsurface plumbing system and sources of gas leakage. Distinct morphologies and geophysical signatures of mounds and craters are inferred to reflect different development stages of shallow gas hydrate formation and dissociation. Over 600 gas flares extending from the sea floor into the water are mapped, many of these from the seafloor mounds and craters, but most from their flanks and surroundings. Analysis of geophysical data link gas flares in the water, craters and mounds to seismic indications of gas advection from deeper hydrocarbon reservoirs along faults and fractures. We present a conceptual model for formation of mounds, craters and gas leakage of the area.

  5. Dance--Aerobic and Anaerobic.

    ERIC Educational Resources Information Center

    Cohen, Arlette

    1984-01-01

    This article defines and explains aerobic exercise and its effects on the cardiovascular system. Various studies on dancers are cited indicating that dance is an anaerobic activity with some small degree of aerobic benefit. (DF)

  6. [Aerobic methanotrophic communities in the bottom sediments of Lake Baikal].

    PubMed

    Gaĭnutdinova, E A; Eshinimaev, B Ts; Tsyrenzhapova, I S; Dagurova, O P; Suzina, N E; Khmelenina, V N; Namsaraev, B B; Trotsenko, Iu A

    2005-01-01

    The results of the first methodical investigation into the aerobic methanotrophic communities inhabiting the bottom sediments of Lake Baikal are reported. Use of the radioisotopic method revealed methane consumption in 12 10- to 50-cm-long sediment cores. The maximum methane consumption rates (495-737 microl/(dm3 day) were recorded in sediments in the regions of hydrothermal vents and oil and gas occurrence. Methane consumption was most active in the surface layers of the sediments (0-4 cm); it decreased with the sediment depth and became negligible or absent at depths below 20 cm. The number of methanotrophic bacteria usually ranged from 100 to 1000 cells/cm3 of sediment and reached 1 million cells/cm3 in the regions of oil and gas occurrence. The 17 enrichment cultures obtained were represented mainly by morphotype II methanotrophs. Phylogenetic analysis of the enrichment cultures in terms of the amino acid sequence of the alpha subunit of the membrane-bound methane monooxygenase revealed the predominance of methanotrophs of the genus Methylocystis. The results obtained suggest the presence of an active aerobic methanotrophic community in Lake Baikal. PMID:16211862

  7. Methane seepage along the Hikurangi Margin offshore New Zealand: 6 years of multidisciplinary studies

    NASA Astrophysics Data System (ADS)

    Greinert, J.; Bialas, J.; Klaucke, I.; Crutchley, G.; Dale, A.; Linke, P.; Sommer, S.; Bowden, D.; Rowden, A.; de Haas, H.; de Stigter, H.; Faure, K.

    2012-12-01

    Detailed studies in 2006, 2007 and 2011 along the east coast of New Zealand's North Island highlighted the close link of sub-bottom fluid pathways and seafloor expressions of methane seepage such as clam fields, carbonate build-ups, tubeworms, bacterial mats and methane release (Marine Geology 272). Prior to our studies, only accidental observations of hydroacoustic anomalies, recoveries of calyptogena shells and methane-derived carbonate chimneys indicated active seepage. Wide areas of the sub-seafloor show BSR structures, gas migration pathways, gas chimneys and blanking zones, which are closely linked to actual seep sites. Sidescan surveys showed four prominent seep areas at Omakere Ridge in 1120m water depth, three of them perfectly matching the shapes and locations of faults seen in high resolution 3D-seismic surveys. The fourth seep, Bear's Paw, on its western side represents an old seep which developed into a cold water coral habitat. At the actively seeping eastern part, gas hydrates could be retrieved and bubble release was observed hydroacoustically and confirmed by high dissolved methane values (380nM). No strong microbial oxidation effects could be found in δ13C values plotting along a mixing curve between pure seep (-70 ‰PDB) and atmospheric methane (-47 ‰PDB). Lander deployments show a tide-influenced gas discharge with sometimes eruptive bubble release with possible plume development transporting methane-charged water higher up into the water column. Rock Garden, with just above 600m water depth at its top outside the gas hydrate stability zone, hosts two main seep areas. ROV observations at Faure Site document eruptive releases of free gas from decimeter-wide craters at the seafloor. Flux estimates show peak releases of 420ml/min with bubbles up to 9mm in diameter. Concentrations of dissolved methane reach up to 3500nM close to the bottom, but higher concentrations are limited to below 400m of water depth; here, methane is transported towards

  8. Methane production and methanogen levels in steers that differ in residual gain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methane gas released by cattle is a product of fermentation in the digestive tract. The two primary sites of methane fermentation in ruminants are the reticulum-rumen complex, and the cecum. Methane release from cattle represents a 2 to 12% loss of the energy intake. Reducing the proportion of fe...

  9. Airborne Methane Measurements using Optical Parametric Amplifiers

    NASA Astrophysics Data System (ADS)

    Riris, H.; Numata, K.; Li, S.; Wu, S.; Ramanathan, A.; Dawsey, M.; Abshire, J. B.; Kawa, S. R.; Mao, J.

    2012-12-01

    We report on airborne methane measurements with an active sensing instrument using widely tunable, seeded optical parametric generation (OPG). Methane is a strong greenhouse gas on Earth and it is also a potential biogenic marker on Mars and other planetary bodies. Methane in the Earth's atmosphere survives for a shorter time than CO2 but its impact on climate change can be larger than CO2. Carbon and methane emissions from land are expected to increase as permafrost melts exposing millennial-age carbon stocks to respiration (aerobic-CO2 and anaerobic-CH4) and fires. Methane emissions from clathrates in the Arctic Ocean and on land are also likely to respond to climate warming. However, there is considerable uncertainty in present Arctic flux levels, as well as how fluxes will change with the changing environment and more measurements are needed. In this paper we report on an airborne demonstration of atmospheric methane column optical depth measurements at 1.65 μm using widely tunable, seeded optical parametric amplifier (OPA) and a photon counting detector. Our results show good agreement between the experimentally derived optical depth measurements and theoretical calculations and follow the expected changes for aircraft altitudes from 3 to 11 km. The technique has also been used to measure carbon dioxide and monoxide, water vapor, and other trace gases in the near and mid-infrared spectral regions on the ground.

  10. Comparison of Two Techniques to Calculate Methane Oxidation rates in Samples Obtained From the Hudson Canyon Seep Field in the North Atlantic

    NASA Astrophysics Data System (ADS)

    Leonte, M.; Kessler, J. D.; Chepigin, A.; Kellermann, M. Y.; Arrington, E.; Valentine, D. L.; Sylva, S.

    2014-12-01

    Aerobic methane oxidation, or methanotrophy, is the dominant process by which methane is removed from the water column in oceanic environments. Therefore, accurately quantifying methane oxidation rates is crucial when constructing methane budgets on a local or global scale. Here we present a comparison of two techniques used to determine methane oxidation rates based on samples obtained over the Hudson Canyon seep field in the North Atlantic. Traditional methane oxidation rate measurements require inoculation of water samples with isotopically labeled methane and tracking the changes to methane concentrations and isotopes as the samples are incubated. However, the addition of methane above background levels is thought to increase the potential for methane oxidation in the sample. A new technique to calculate methane oxidation rates is based on kinetic isotope models and incorporates direct measurements of methane concentrations, methane 13C isotopes, and water current velocity. Acoustic instrumentation (ADCP) aboard the R/V Endeavor was used to obtain water current velocity data while water samples were collected for methane concentration and isotopic ratio analysis. Methane δ13C measurements allow us to attribute changes in methane concentration to either water dispersion or bacterial methane oxidation. The data obtained from this cruise will tell us a comprehensive story of methane removal processes from this active seep field. The kinetic isotope models will allow us to estimate the total flux of methane from the seep site and calculate methane oxidation rates at different depths and locations away from seafloor plumes.

  11. Methane flux time series for tundra environments

    SciTech Connect

    Whalen, S.C.; Reeburgh, W.E. )

    1988-12-01

    Seasonal measurements of net methane flux were made at permanent sites representing important components of arctic tundra. The sites include Eriophorum tussocks, intertussock depressions, moss-covered areas, and Carex stands. Methane fluxes showed high diel, seasonal, intra site, and between site variability. Eriophorum tussocks and Carex dominated methane release to the atmosphere, with mean annual net methane fluxes of 8.05 + or{minus}2.50 g CH{sub 4}/sq m and 4.88 + or{minus}0.73 g CH{sub 4}/sq m, respectively. Methane fluxes form the moss sites and intertussock depressions were much lower. Over 90% of the mean annual methane flux from the Eriophorum, intertussock depressions, and Carex sites occurred between thaw and freeze-up. Some 40% of the mean annual methane flux from the moss sites occurred during winter. Composite methane fluxes for tussock tundra and Carex-dominated wet meadow tundra environments were produced by weighting measured component fluxes according to areal coverage. Tussock and wet meadow tundra account for an estimated global methane emission of 19-33 Tg/yr. 39 refs., 7 figs., 2 tabs.

  12. Release and fate of fluorocarbons in a shredder residue landfill cell: 1. Laboratory experiments.

    PubMed

    Scheutz, Charlotte; Fredenslund, Anders M; Nedenskov, Jonas; Kjeldsen, Peter

    2010-11-01

    The shredder residues from automobiles, home appliances and other metal-containing products are often disposed in landfills, as recycling technologies for these materials are not common in many countries. Shredder waste contains rigid and soft foams from cushions and insulation panels blown with fluorocarbons. The objective of this study was to use laboratory experiments to estimate fluorocarbon release and attenuation processes in a monofill shredder residue (SR) landfill cell. Waste from the open SR landfill cell at the AV Miljø landfill in Denmark was sampled at three locations. The waste contained 1-3% metal and a relatively low fraction of rigid polyurethane (PUR) foam particles. The PUR waste contained less blowing agent (CFC-11) than predicted from a release model. However, CFC-11 was steadily released in an aerobic bench scale experiment. Anaerobic waste incubation bench tests showed that SRSR produced significant methane (CH(4)), but at rates that were in the low end of the range observed for municipal solid waste. Aerobic and anaerobic batch experiments showed that processes in SRSR potentially can attenuate the fluorocarbons released from the SRSR itself: CFC-11 is degraded under anaerobic conditions with the formation of degradation products, which are being degraded under CH(4) oxidation conditions prevailing in the upper layers of the SR. PMID:20435458

  13. Cryolava flow destabilization of crustal methane clathrate hydrate on Titan

    NASA Astrophysics Data System (ADS)

    Davies, Ashley Gerard; Sotin, Christophe; Choukroun, Mathieu; Matson, Dennis L.; Johnson, Torrence V.

    2016-08-01

    To date, there has been no conclusive observation of ongoing endogenous volcanic activity on Saturn's moon Titan. However, with time, Titan's atmospheric methane is lost and must be replenished. We have modeled one possible mechanism for the replenishment of Titan's methane loss. Cryolavas can supply enough heat to release large amounts of methane from methane clathrate hydrates (MCH). The volume of methane released is controlled by the flow thickness and its areal extent. The depth of the destabilisation layer is typically ≈30% of the thickness of the lava flow (≈3 m for a 10-m thick flow). For this flow example, a maximum of 372 kg of methane is released per m2 of flow area. Such an event would release methane for nearly a year. One or two events per year covering ∼20 km2 would be sufficient to resupply atmospheric methane. A much larger effusive event covering an area of ≈9000 km2 with flows 200 m thick would release enough methane to sustain current methane concentrations for 10,000 years. The minimum size of "cryo-flows" sufficient to maintain the current atmospheric methane is small enough that their detection with current instruments (e.g., Cassini) could be challenging. We do not suggest that Titan's original atmosphere was generated by this mechanism. It is unlikely that small-scale surface MCH destabilisation is solely responsible for long-term (> a few Myr) sustenance of Titan's atmospheric methane, but rather we present it as a possible contributor to Titan's past and current atmospheric methane.

  14. Ebullitive methane emissions from oxygenated wetland streams.

    PubMed

    Crawford, John T; Stanley, Emily H; Spawn, Seth A; Finlay, Jacques C; Loken, Luke C; Striegl, Robert G

    2014-11-01

    Stream and river carbon dioxide emissions are an important component of the global carbon cycle. Methane emissions from streams could also contribute to regional or global greenhouse gas cycling, but there are relatively few data regarding stream and river methane emissions. Furthermore, the available data do not typically include the ebullitive (bubble-mediated) pathway, instead focusing on emission of dissolved methane by diffusion or convection. Here, we show the importance of ebullitive methane emissions from small streams in the regional greenhouse gas balance of a lake and wetland-dominated landscape in temperate North America and identify the origin of the methane emitted from these well-oxygenated streams. Stream methane flux densities from this landscape tended to exceed those of nearby wetland diffusive fluxes as well as average global wetland ebullitive fluxes. Total stream ebullitive methane flux at the regional scale (103 Mg C yr(-1) ; over 6400 km(2) ) was of the same magnitude as diffusive methane flux previously documented at the same scale. Organic-rich stream sediments had the highest rates of bubble release and higher enrichment of methane in bubbles, but glacial sand sediments also exhibited high bubble emissions relative to other studied environments. Our results from a database of groundwater chemistry support the hypothesis that methane in bubbles is produced in anoxic near-stream sediment porewaters, and not in deeper, oxygenated groundwaters. Methane interacts with other key elemental cycles such as nitrogen, oxygen, and sulfur, which has implications for ecosystem changes such as drought and increased nutrient loading. Our results support the contention that streams, particularly those draining wetland landscapes of the northern hemisphere, are an important component of the global methane cycle.

  15. Aerobic methanotrophic communities at the Red Sea brine-seawater interface

    PubMed Central

    Abdallah, Rehab Z.; Adel, Mustafa; Ouf, Amged; Sayed, Ahmed; Ghazy, Mohamed A.; Alam, Intikhab; Essack, Magbubah; Lafi, Feras F.; Bajic, Vladimir B.; El-Dorry, Hamza; Siam, Rania

    2014-01-01

    The central rift of the Red Sea contains 25 brine pools with different physicochemical conditions, dictating the diversity and abundance of the microbial community. Three of these pools, the Atlantis II, Kebrit and Discovery Deeps, are uniquely characterized by a high concentration of hydrocarbons. The brine-seawater interface, described as an anoxic-oxic (brine-seawater) boundary, is characterized by a high methane concentration, thus favoring aerobic methane oxidation. The current study analyzed the aerobic free–living methane-oxidizing bacterial communities that potentially contribute to methane oxidation at the brine-seawater interfaces of the three aforementioned brine pools, using metagenomic pyrosequencing, 16S rRNA pyrotags and pmoA library constructs. The sequencing of 16S rRNA pyrotags revealed that these interfaces are characterized by high microbial community diversity. Signatures of aerobic methane-oxidizing bacteria were detected in the Atlantis II Interface (ATII-I) and the Kebrit Deep Upper (KB-U) and Lower (KB-L) brine-seawater interfaces. Through phylogenetic analysis of pmoA, we further demonstrated that the ATII-I aerobic methanotroph community is highly diverse. We propose four ATII-I pmoA clusters. Most importantly, cluster 2 groups with marine methane seep methanotrophs, and cluster 4 represent a unique lineage of an uncultured bacterium with divergent alkane monooxygenases. Moreover, non-metric multidimensional scaling (NMDS) based on the ordination of putative enzymes involved in methane metabolism showed that the Kebrit interface layers were distinct from the ATII-I and DD-I brine-seawater interfaces. PMID:25295031

  16. Non-microbial methane emissions from soils

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Hou, Longyu; Liu, Wei; Wang, Zhiping

    2013-12-01

    Traditionally, methane (CH4) is anaerobically formed by methanogenic archaea. However, non-microbial CH4 can also be produced from geologic processes, biomass burning, animals, plants, and recently identified soils. Recognition of non-microbial CH4 emissions from soils remains inadequate. To better understand this phenomenon, a series of laboratory incubations were conducted to examine effects of temperature, water, and hydrogen peroxide (H2O2) on CH4 emissions under both aerobic and anaerobic conditions using autoclaved (30 min, 121 °C) soils and aggregates (>2000 μm, A1; 2000-250 μm, A2; 250-53 μm, M1; and <53 μm, M2). Results show that applying autoclaving to pre-treat soils is effective to inhibit methanogenic activity, ensuring the CH4 emitted being non-microbial. Responses of non-microbial CH4 emissions to temperature, water, and H2O2 were almost identical between aerobic and anaerobic conditions. Increasing temperature, water of proper amount, and H2O2 could significantly enhance CH4 emissions. However, the emission rates were inhibited and enhanced by anaerobic conditions without and with the existence of H2O2, respectively. As regards the aggregates, aggregate-based emission presented an order of M1 > A2 > A1 > M2 and C-based emission an order of M2 > M1 > A1 > A2, demonstrating that both organic carbon quantity and property are responsible for CH4 emissions from soils at the scale of aggregate. Whole soil-based order of A2 > A1 > M1 > M2 suggests that non-microbial CH4 release from forest soils is majorly contributed by macro-aggregates (i.e., >250 μm). The underlying mechanism is that organic matter through thermal treatment, photolysis, or reactions with free radicals produce CH4, which, in essence, is identical with mechanisms of other non-microbial sources, indicating that non-microbial CH4 production may be a widespread phenomenon in nature. This work further elucidates the importance of non-microbial CH4 formation which should be distinguished

  17. Thinking Like a Wildcatter: Prospecting for Methane in Arabia Terra, Mars

    NASA Technical Reports Server (NTRS)

    Allen, C. C.; Oehler, D. Z.

    2005-01-01

    Methane has been detected in the martian atmosphere at a concentration of approximately 10 ppb. The lifetime of such methane against decomposition by solar radiation is approximately 300 years, strongly suggesting that methane is currently being released to the atmosphere. By analogy to Earth, possible methane sources on Mars include active volcanism, hot springs, frozen methane clathrates, thermally-matured sedimentary organic matter, and extant microbial metabolism. The discovery of any one of these sources would revolutionize our understanding of Mars.

  18. Methane emission from flooded soils - from microorganisms to the atmosphere

    NASA Astrophysics Data System (ADS)

    Conrad, Ralf

    2016-04-01

    Methane is an important greenhouse gas that is affected by anthropogenic activity. The annual budget of atmospheric methane, which is about 600 million tons, is by more than 75% produced by methanogenic archaea. These archaea are the end-members of a microbial community that degrades organic matter under anaerobic conditions. Flooded rice fields constitute a major source (about 10%) of atmospheric methane. After flooding of soil, anaerobic processes are initiated, finally resulting in the disproportionation of organic matter to carbon dioxide and methane. This process occurs in the bulk soil, on decaying organic debris and in the rhizosphere. The produced methane is mostly ventilated through the plant vascular system into the atmosphere. This system also allows the diffusion of oxygen into the rizosphere, where part of the produced methane is oxidized by aerobic methanotrophic bacteria. More than 50% of the methane production is derived from plant photosynthetic products and is formed on the root surface. Methanocellales are an important group of methanogenic archaea colonizing rice roots. Soils lacking this group seem to result in reduced root colonization and methane production. In rice soil methane is produced by two major paths of methanogenesis, the hydrogenotrophic one reducing carbon dioxide to methane, and the aceticlastic one disproportionating acetate to methane and carbon dioxide. Theoretically, at least two third of the methane should be produced by aceticlastic and the rest by hydrogenotrophic methanogenesis. In nature, however, the exact contribution of the two paths can vary from zero to 100%. Several environmental factors, such as temperature and quality of organic matter affect the path of methane production. The impact of these factors on the composition and activity of the environmental methanogenic microbial community will be discussed.

  19. Methane venting to the atmosphere from sediments

    NASA Astrophysics Data System (ADS)

    Shakhova, Natalia; Semiletov, Igor; Salyuk, Anatoly; Joussupov, Vladimir; Kosmach, Denis; Gustafsson, Orjan; Leifer, Ira

    2010-05-01

    Sustained release of methane to the atmosphere from thawing Arctic permafrost likely is a strong positive feedback to climate warming. A climate impact of Arctic methane releases is implied by past climate shifts and may play a role in the renewed growth of contemporary atmospheric methane. Observed Arctic warming in early 21st century is stronger than predicted by several degrees, which may accelerate thaw-release of methane. The East Siberian Arctic Shelf (ESAS, encompassing the Laptev, East Siberian and Russian part of the Chuckchi Seas) occupies an area of 2.1×106 km2, three times as great as terrestrial Siberian wetlands. It is a shallow seaward extension of the Siberian tundra that was flooded during the Holocene transgression 7-15 kyr ago. The ESAS sub-sea permafrost, (frozen sediments inter-layered with the flooded peatland) contains not only comparable amounts of carbon as still land-fast permafrost in the Siberian tundra, but also sequesters permafrost-related seabed deposits of CH4. Remobilization to the atmosphere of only a small fraction of the methane trapped in ESAS sediments could trigger abrupt climate warming. Currently it is hypothesized that sub-sea permafrost acts as a lid retaining this shallow methane reservoir. However, estimates of ESAS methane emissions based on recent observations indicate the current atmospheric budget, which arises from gradual diffusion and ebullition, is on par with estimates of methane emissions from the entire World Ocean. Large transient emissions remain to be assessed; yet initial data suggest this component could increase significantly annual emissions. These study results show methane leakage from the shallow ESAS needs consideration in interactions between the biogeosphere and a warming Arctic climate.

  20. The role of methane in mammalian physiology-is it a gasotransmitter?

    PubMed

    Boros, Mihály; Tuboly, Eszter; Mészáros, András; Amann, Anton

    2015-01-27

    Mammalian methanogenesis is widely considered to be an exclusive sign of anaerobic microbial activity in the gastrointestinal tract. This commonly held view was challenged, however, when in vitro and in vivo investigations demonstrated the possibility of nonmicrobial methane formation in aerobic organisms, in plants and animals. The aim of this review is to discuss the available literature data on the biological role of methane. When we evaluate the significance of methane generation in the mammalian physiology, the question may be examined: is it a gas mediator? Overall the data do not fully support the gasotransmitter concept, but they do support the notion that methane liberation may be linked to redox regulation and may be connected with hypoxic events leading to, or associated with a mitochondrial dysfunction. In this respect, the available information suggests that hypoxia-induced methane generation may be a necessary phenomenon of aerobic life, and perhaps a surviving evolutionary trait in the eukaryote cell.

  1. Atmospheric distribution of methane on Mars: A model study

    NASA Astrophysics Data System (ADS)

    Viscardy, Sébastien; Daerden, Frank; Neary, Lori

    2016-10-01

    In the past decade, the detection of methane (CH4) in the atmosphere of Mars has been reported several times. These observations have strongly drawn the attention of the scientific community and triggered a renewed interest in Mars as their implications for the geochemical or biological activities are remarkable. However, given that methane is expected to have a photochemical lifetime of several centuries, the relatively fast loss rates of methane estimated from Earth-based measurements remain unexplained. Although this gave rise to objections against the validity of those observations, recent in situ measurements confirmed that methane is being occasionally released into the atmosphere from an unknown source (possibly from the ground). Additionally, ExoMars/TGO was launched to Mars in March 2016. NOMAD, one of the instruments onboard TGO, will provide the first global detailed observations of methane on Mars. It is in this context that we present a model study of the behavior of methane plumes.A general circulation model for the atmosphere of Mars is applied to simulate surface emission of methane and to investigate its vertical distribution during the first weeks after the release. Such surface emissions were suggested to explain observations of methane. Previous GCM simulations focused on the horizontal evolution of the methane, but the present study focuses on the three-dimensional dispersion of methane throughout the atmosphere after the surface release. It is found that a highly nonuniform vertical distribution, including distinct vertical layers, can appear throughout the atmosphere during the first weeks after the emission. This is explained by the global circulation patterns in the atmosphere at the time of the emission. Large Hadley cells transport the methane rapidly to other locations over the planet, and methane will be stretched out in layers along the general circulation streamlines at heights corresponding to strong zonal jets.This result changes

  2. A methane-driven microbial food web in a wetland rice soil.

    PubMed

    Murase, Jun; Frenzel, Peter

    2007-12-01

    Methane oxidation is a key process controlling methane emission from anoxic habitats into the atmosphere. Methanotrophs, responsible for aerobic methane oxidation, do not only oxidize but also assimilate methane. Once assimilated, methane carbon may be utilized by other organisms. Here we report on a microbial food web in a rice field soil driven by methane. A thin layer of water-saturated rice field soil was incubated under opposing gradients of oxygen and (13)C-labelled methane. Bacterial and eukaryotic communities incorporating methane carbon were analysed by RNA-stable isotope probing (SIP). Terminal restriction fragment length polymorphism (T-RFLP) and cloning showed that methanotrophs were the most prominent group of bacteria incorporating methane carbon. In addition, a few Myxobacteria-related sequences were obtained from the 'heavy' rRNA fraction. Denaturing gradient gel electrophoresis (DGGE) targeting 18S rRNA detected various groups of protists in the 'heavy' rRNA fraction including naked amoeba (Lobosea and Heterolobosea), ciliates (Colpodea) and flagellates (Cercozoa). Incubation of soil under different methane concentrations in air resulted in the development of distinct protozoan communities. These results suggest that methane carbon is incorporated into non-methanotrophic pro- and microeukaryotes probably via grazing, and that methane oxidation is a shaping force of the microeukaryotic community depending on methane availability.

  3. Carbon and hydrogen isotope fractionation during nitrite-dependent anaerobic methane oxidation by Methylomirabilis oxyfera

    NASA Astrophysics Data System (ADS)

    Rasigraf, Olivia; Vogt, Carsten; Richnow, Hans-Hermann; Jetten, Mike S. M.; Ettwig, Katharina F.

    2012-07-01

    Anaerobic oxidation of methane coupled to nitrite reduction is a recently discovered methane sink of as yet unknown global significance. The bacteria that have been identified to carry out this process, Candidatus Methylomirabilis oxyfera, oxidize methane via the known aerobic pathway involving the monooxygenase reaction. In contrast to aerobic methanotrophs, oxygen is produced intracellularly and used for the activation of methane by a phylogenetically distinct particulate methane monooxygenase (pMMO). Here we report the fractionation factors for carbon and hydrogen during methane oxidation by an enrichment culture of M. oxyfera bacteria. In two separate batch incubation experiments with different absolute biomass and methane contents, the specific methanotrophic activity was similar and the progressive isotope enrichment identical. Headspace methane was consumed up to 98% with rates showing typical first order reaction kinetics. The enrichment factors determined by Rayleigh equations were -29.2 ± 2.6‰ for δ13C (εC) and -227.6 ± 13.5‰ for δ2H (εH), respectively. These enrichment factors were in the upper range of values reported so far for aerobic methanotrophs. In addition, two-dimensional specific isotope analysis (Λ = ( α H - 1 - 1)/( α C - 1 - 1)) was performed and also the determined Λ value of 9.8 was within the range determined for other aerobic and anaerobic methanotrophs. The results showed that in contrast to abiotic processes biological methane oxidation exhibits a narrow range of fractionation factors for carbon and hydrogen irrespective of the underlying biochemical mechanisms. This work will therefore facilitate the correct interpretation of isotopic composition of atmospheric methane with implications for modeling of global carbon fluxes.

  4. Aerobic landfill bioreactor

    DOEpatents

    Hudgins, Mark P; Bessette, Bernard J; March, John C; McComb, Scott T.

    2002-01-01

    The present invention includes a system of decomposing municipal solid waste (MSW) within a landfill by converting the landfill to aerobic degradation in the following manner: (1) injecting air via the landfill leachate collection system (2) injecting air via vertical air injection wells installed within the waste mass; (3) applying leachate to the waste mass using a pressurized drip irrigation system; (4) allowing landfill gases to vent; and (5) adjusting air injection and recirculated leachate to achieve a 40% to 60% moisture level and a temperature between 120.degree. F. and 140.degree. F. in steady state.

  5. Aerobic landfill bioreactor

    DOEpatents

    Hudgins, Mark P; Bessette, Bernard J; March, John; McComb, Scott T.

    2000-01-01

    The present invention includes a method of decomposing municipal solid waste (MSW) within a landfill by converting the landfill to aerobic degradation in the following manner: (1) injecting air via the landfill leachate collection system (2) injecting air via vertical air injection wells installed within the waste mass; (3) applying leachate to the waste mass using a pressurized drip irrigation system; (4) allowing landfill gases to vent; and (5) adjusting air injection and recirculated leachate to achieve a 40% to 60% moisture level and a temperature between 120.degree. F. and 140.degree. F. in steady state.

  6. Aerobic landfill bioreactor

    SciTech Connect

    Hudgins, M.P.; Bessette, B.J.; March, J.; McComb, S.T.

    2000-02-15

    The present invention includes a method of decomposing municipal solid waste (MSW) within a landfill by converting the landfill to aerobic degradation in the following manner: (1) injecting air via the landfill leachate collection system (2) injecting air via vertical air injection wells installed within the waste mass; (3) applying leachate to the waste mass using a pressurized drip irrigation system; (4) allowing landfill gases to vent; and (5) adjusting air injection and recirculated leachate to achieve a 40% to 60% moisture level and a temperature between 120 F and 140 F in steady state.

  7. Low-Impact Aerobics: Better than Traditional Aerobic Dance?

    ERIC Educational Resources Information Center

    Koszuta, Laurie Einstein

    1986-01-01

    A form of dance exercise called low-impact aerobics is being touted as a misery-free form of aerobic dance. Because this activity is relatively new, the exact kinds and frequencies of injuries are not known and the fitness benefits have not been examined. (MT)

  8. Microbial Methane Oxidation Rates in Guandu Wetland of northern Taiwan

    NASA Astrophysics Data System (ADS)

    Yu, Zih-Huei; Wang, Pei-Ling; Lin, Li-Hung

    2016-04-01

    Wetland is one of the major sources of atmospheric methane. The exact magnitude of methane emission is essentially controlled by microbial processes. Besides of methanogenesis, methanotrophy oxidizes methane with the reduction of various electron acceptors under oxic or anoxic conditions. The interplay of these microbial activities determines the final methane flux under different circumstances. In a tidal wetland, the cyclic flooding and recession of tide render oxygen and sulfate the dominant electron acceptors for methane oxidation. However, the details have not been fully examined, especially for the linkage between potential methane oxidation rates and in situ condition. In this study, a sub-tropical wetland in northern Taiwan, Guandu, was chosen to examine the tidal effect on microbial methane regulation. Several sediment cores were retrieved during high tide and low tide period and their geochemical profiles were characterized to demonstrate in situ microbial activities. Incubation experiments were conducted to estimate potential aerobic and anaerobic methane oxidation rates in surface and core sediments. Sediment cores collected in high tide and low tide period showed different geochemical characteristics, owning to tidal inundation. Chloride and sulfate concentration were lower during low tide period. A spike of enhanced sulfate at middle depth intervals was sandwiched by two sulfate depleted zones above and underneath. Methane was accumulated significantly with two methane depletion zones nearly mirroring the sulfate spike zone identified. During the high tide period, sulfate decreased slightly with depth with methane production inhibited at shallow depths. However, a methane consumption zone still occurred near the surface. Potential aerobic methane oxidation rates were estimated between 0.7 to 1.1 μmole/g/d, showing no difference between the samples collected at high tide or low tide period. However, a lag phase was widely observed and the lag phase

  9. Making methane visible

    NASA Astrophysics Data System (ADS)

    Gålfalk, Magnus; Olofsson, Göran; Crill, Patrick; Bastviken, David

    2016-04-01

    Methane (CH4) is one of the most important greenhouse gases, and an important energy carrier in biogas and natural gas. Its large scale emission patterns have been unpredictable and the source and sink distributions are poorly constrained. Remote assessment of CH4 with high sensitivity at m2 spatial resolution would allow detailed mapping of near ground distribution and anthropogenic sources and sinks in landscapes but has hitherto not been possible. Here we show that CH4 gradients can be imaged on methane imaging will include a lake, barn, sewage sludge deposit, waste incineration plant, and controlled gas releases. We will also present successful simultaneous imaging of another important greenhouse gas, nitrous oxide, with the same instrument.

  10. Aerobic Fitness and School Children.

    ERIC Educational Resources Information Center

    Hinkle, J. Scott

    1997-01-01

    Provides school counselors with information on aerobic exercise (specifically running) and the psychological, behavioral, and physical benefits children obtained by participating in fitness programs. Recommends collaboration between school counselors and physical education teachers and gives a preliminary discussion of aerobic running and its…

  11. Aerobic Fitness and School Children.

    ERIC Educational Resources Information Center

    Hinkle, J. Scott

    1992-01-01

    Provides school counselors with information regarding aerobic exercise (specifically running), and the psychological, behavioral, and physical benefits children obtain by participating in fitness programs. Presents methods of collaboration between school counselors and physical education teachers. Offers preliminary discussion of aerobic running…

  12. Exercise, Animal Aerobics, and Interpretation?

    ERIC Educational Resources Information Center

    Oliver, Valerie

    1996-01-01

    Describes an aerobic activity set to music for children that mimics animal movements. Example exercises include walking like a penguin or jumping like a cricket. Stresses basic aerobic principles and designing the program at the level of children's motor skills. Benefits include reaching people who normally don't visit nature centers, and bridging…

  13. Waste degradation and gas production with enzymatic enhancement in anaerobic and aerobic landfill bioreactors.

    PubMed

    Hettiaratchi, J P A; Jayasinghe, P A; Bartholameuz, E M; Kumar, S

    2014-05-01

    The presence of lignin is the limiting factor at later stages of biodegradation of municipal solid waste under aerobic or anaerobic conditions. Supplying enzymes into the system could facilitate lignin degradation, thereby aiding anaerobic and aerobic waste degradation processes. A comprehensive set of laboratory experiments were conducted under both anaerobic and aerobic conditions to evaluate the feasibility of using enzymes in accelerating lignin-rich waste degradation. After 30 days of anaerobic operation, MnP and LiP enzyme treated reactors produced 36 and 23 times higher cumulative methane (CH4), respectively, compared to that of the control reactor devoid of enzyme treatments. The carbon dioxide (CO2) yield of MnP enhanced aerobic reactor showed more than two-fold increase.

  14. Waste degradation and gas production with enzymatic enhancement in anaerobic and aerobic landfill bioreactors.

    PubMed

    Hettiaratchi, J P A; Jayasinghe, P A; Bartholameuz, E M; Kumar, S

    2014-05-01

    The presence of lignin is the limiting factor at later stages of biodegradation of municipal solid waste under aerobic or anaerobic conditions. Supplying enzymes into the system could facilitate lignin degradation, thereby aiding anaerobic and aerobic waste degradation processes. A comprehensive set of laboratory experiments were conducted under both anaerobic and aerobic conditions to evaluate the feasibility of using enzymes in accelerating lignin-rich waste degradation. After 30 days of anaerobic operation, MnP and LiP enzyme treated reactors produced 36 and 23 times higher cumulative methane (CH4), respectively, compared to that of the control reactor devoid of enzyme treatments. The carbon dioxide (CO2) yield of MnP enhanced aerobic reactor showed more than two-fold increase. PMID:24684817

  15. Prospecting for Methane in Arabia Terra, Mars - First Results

    NASA Technical Reports Server (NTRS)

    Allen, Carlton C.; Oehler, Dotoyhy Z.; Venechuk, Elizabeth M.

    2006-01-01

    Methane has been measured in the Martian atmosphere at concentrations of approx. 10 ppb. Since the photochemical lifetime of this gas is approx. 300 years, it is likely that methane is currently being released from the surface. Possible sources for the methane include 1) hydrothermal activity, 2) serpentinization of basalts and other water-rock interactions, 3) thermal maturation of sedimentary organic matter, and 4) metabolism of living bacteria. Any such discovery would revolutionize our understanding of Mars. Longitudinal variations in methane concentration, as measured by the Planetary Fourier Spectrometer (PFS) on Mars Express, show the highest values over Arabia Terra, Elysium Planum, and Arcadia-Memnonia, suggesting localized areas of methane release. We are using orbital data and methodologies derived from petroleum exploration in an attempt to locate these release points.

  16. Effects of permafrost thaw on northern wetland methane emissions

    NASA Astrophysics Data System (ADS)

    Turetsky, M. R.; Olefeldt, D.; Waddington, J. M.

    2012-12-01

    There has been a renewed interest in northern, high latitude methane emissions because of 1) the recent unexpected increase in atmospheric methane concentrations after a period of stability, 2) large releases of methane in bubbles from arctic thermokarst lakes, and 3) the recent discovery that high latitude soil carbon stocks are much larger than previously recognized. Global inverse modeling shows that Arctic methane emissions increased by 30% from 2003-2007, and that high latitude emissions were more sensitive to warming than water table fluctuations. Arctic wetlands and lakes likely have contributed at least partly to recent increases in atmospheric methane concentrations. Across the circumpolar region, thermokarst associated with permafrost thaw is creating lakes and wetlands that tend to have elevated methane emissions. Thaw wetlands in interior Alaska release methane primarily through plants, especially Carex species, as well as ebullition (bubbles). Ebullition was sensitive to soil temperature both in the field and in a laboratory experiment, indicating that continued warming may contribute to increases in northern wetland methane emissions by increasing the area of thaw wetlands on the landscape as well as by stimulating bubble formation and release. A meta-analysis of data from more than 300 sites suggests that increased methane emissions following permafrost thaw are more likely related to altered water table position, soil temperature and vegetation composition, rather than increases in unfrozen soil carbon stocks.

  17. Martian zeolites as a source of atmospheric methane

    NASA Astrophysics Data System (ADS)

    Mousis, Olivier; Simon, Jean-Marc; Bellat, Jean-Pierre; Schmidt, Frédéric; Bouley, Sylvain; Chassefière, Eric; Sautter, Violaine; Quesnel, Yoann; Picaud, Sylvain; Lectez, Sébastien

    2016-11-01

    The origin of the martian methane is still poorly understood. A plausible explanation is that methane could have been produced either by hydrothermal alteration of basaltic crust or by serpentinization of ultramafic rocks producing hydrogen and reducing crustal carbon into methane. Once formed, methane storage on Mars is commonly associated with the presence of hidden clathrate reservoirs. Here, we alternatively suggest that chabazite and clinoptilolite, which belong to the family of zeolites, may form a plausible storage reservoir of methane in the martian subsurface. Because of the existence of many volcanic terrains, zeolites are expected to be widespread on Mars and their Global Equivalent Layer may range up to more than ∼1 km, according to the most optimistic estimates. If the martian methane present in chabazite and clinoptilolite is directly sourced from an abiotic source in the subsurface, the destabilization of a localized layer of a few millimeters per year may be sufficient to explain the current observations. The sporadic release of methane from these zeolites requires that they also remained isolated from the atmosphere during its evolution. The methane release over the ages could be due to several mechanisms such as impacts, seismic activity or erosion. If the methane outgassing from excavated chabazite and/or clinoptilolite prevails on Mars, then the presence of these zeolites around Gale Crater could explain the variation of methane level observed by Mars Science Laboratory.

  18. Technical Note: Methionine, a precursor of methane in living plants

    NASA Astrophysics Data System (ADS)

    Lenhart, K.; Althoff, F.; Greule, M.; Keppler, F.

    2015-03-01

    When terrestrial plants were identified as producers of the greenhouse gas methane, much discussion and debate ensued not only about their contribution to the global methane budget but also with regard to the validity of the observation itself. Although the phenomenon has now become more accepted for both living and dead plants, the mechanism of methane formation in living plants remains to be elucidated and its precursor compounds to be identified. We made use of stable isotope techniques to verify the in vivo formation of methane, and, in order to identify the carbon precursor, 13C positionally labeled organic compounds were employed. Here we show that the amino acid L-methionine acts as a methane precursor in living plants. Employing 13C-labeled methionine clearly identified the sulfur-bound methyl group of methionine as a carbon precursor of methane released from lavender (Lavandula angustifolia). Furthermore, when lavender plants were stressed physically, methane release rates and the stable carbon isotope values of the emitted methane greatly increased. Our results provide additional support that plants possess a mechanism for methane production and suggest that methionine might play an important role in the formation of methane in living plants, particularly under stress conditions.

  19. Technical note: Methionine, a precursor of methane in living plants

    NASA Astrophysics Data System (ADS)

    Lenhart, K.; Althoff, F.; Greule, M.; Keppler, F.

    2014-11-01

    When terrestrial plants were identified as producers of the greenhouse gas methane, much discussion and debate ensued, not only about their contribution to the global methane budget, but also with regard to the validity of the observation itself. Although the phenomenon has now become more accepted for both living and dead plants, the mechanism of methane formation in living plants remains to be elucidated and its precursor compounds identified. We made use of stable isotope techniques to verify in vivo formation of methane and, in order to identify the carbon precursor, 13C-positionally labelled organic compounds were employed. Here we show that the amino acid L-methionine acts as a methane precursor in living plants. Employing 13C-labelled methionine clearly identified the sulphur-bound methyl group of methionine as a carbon precursor of methane released from lavender (Lavandula angustifolia). Furthermore, when lavender plants were stressed physically, methane release rates and the stable carbon isotope values of the emitted methane greatly increased. Our results provide additional support that plants possess a mechanism for methane production and suggest that methionine might play an important role in the formation of methane in living plants, particularly under stress conditions.

  20. A conduit dilation model of methane venting from lake sediments

    USGS Publications Warehouse

    Scandella, B.P.; Varadharajan, C.; Hemond, Harold F.; Ruppel, C.; Juanes, R.

    2011-01-01

    Methane is a potent greenhouse gas, but its effects on Earth's climate remain poorly constrained, in part due to uncertainties in global methane fluxes to the atmosphere. An important source of atmospheric methane is the methane generated in organic-rich sediments underlying surface water bodies, including lakes, wetlands, and the ocean. The fraction of the methane that reaches the atmosphere depends critically on the mode and spatiotemporal characteristics of free-gas venting from the underlying sediments. Here we propose that methane transport in lake sediments is controlled by dynamic conduits, which dilate and release gas as the falling hydrostatic pressure reduces the effective stress below the tensile strength of the sediments. We test our model against a four-month record of hydrostatic load and methane flux in Upper Mystic Lake, Mass., USA, and show that it captures the complex episodicity of methane ebullition. Our quantitative conceptualization opens the door to integrated modeling of methane transport to constrain global methane release from lakes and other shallow-water, organic-rich sediment systems, and to assess its climate feedbacks.

  1. Ductile flow of methane hydrate

    USGS Publications Warehouse

    Durham, W.B.; Stern, L.A.; Kirby, S.H.

    2003-01-01

    Compressional creep tests (i.e., constant applied stress) conducted on pure, polycrystalline methane hydrate over the temperature range 260-287 K and confining pressures of 50-100 MPa show this material to be extraordinarily strong compared to other icy compounds. The contrast with hexagonal water ice, sometimes used as a proxy for gas hydrate properties, is impressive: over the thermal range where both are solid, methane hydrate is as much as 40 times stronger than ice at a given strain rate. The specific mechanical response of naturally occurring methane hydrate in sediments to environmental changes is expected to be dependent on the distribution of the hydrate phase within the formation - whether arranged structurally between and (or) cementing sediments grains versus passively in pore space within a sediment framework. If hydrate is in the former mode, the very high strength of methane hydrate implies a significantly greater strain-energy release upon decomposition and subsequent failure of hydrate-cemented formations than previously expected.

  2. Global dispersion and local diversification of the methane seep microbiome

    PubMed Central

    Ruff, S. Emil; Biddle, Jennifer F.; Teske, Andreas P.; Knittel, Katrin; Boetius, Antje

    2015-01-01

    Methane seeps are widespread seafloor ecosystems shaped by the emission of gas from seabed reservoirs. The microorganisms inhabiting methane seeps transform the chemical energy in methane to products that sustain rich benthic communities around the gas leaks. Despite the biogeochemical relevance of microbial methane removal at seeps, the global diversity and dispersion of seep microbiota remain unknown. Here we determined the microbial diversity and community structure of 23 globally distributed methane seeps and compared these to the microbial communities of 54 other seafloor ecosystems, including sulfate–methane transition zones, hydrothermal vents, coastal sediments, and deep-sea surface and subsurface sediments. We found that methane seep communities show moderate levels of microbial richness compared with other seafloor ecosystems and harbor distinct bacterial and archaeal taxa with cosmopolitan distribution and key biogeochemical functions. The high relative sequence abundance of ANME (anaerobic methanotrophic archaea), as well as aerobic Methylococcales, sulfate-reducing Desulfobacterales, and sulfide-oxidizing Thiotrichales, matches the most favorable microbial metabolisms at methane seeps in terms of substrate supply and distinguishes the seep microbiome from other seafloor microbiomes. The key functional taxa varied in relative sequence abundance between different seeps due to the environmental factors, sediment depth and seafloor temperature. The degree of endemism of the methane seep microbiome suggests a high local diversification in these heterogeneous but long-lived ecosystems. Our results indicate that the seep microbiome is structured according to metacommunity processes and that few cosmopolitan microbial taxa mediate the bulk of methane oxidation, with global relevance to methane emission in the ocean. PMID:25775520

  3. Global dispersion and local diversification of the methane seep microbiome.

    PubMed

    Ruff, S Emil; Biddle, Jennifer F; Teske, Andreas P; Knittel, Katrin; Boetius, Antje; Ramette, Alban

    2015-03-31

    Methane seeps are widespread seafloor ecosystems shaped by the emission of gas from seabed reservoirs. The microorganisms inhabiting methane seeps transform the chemical energy in methane to products that sustain rich benthic communities around the gas leaks. Despite the biogeochemical relevance of microbial methane removal at seeps, the global diversity and dispersion of seep microbiota remain unknown. Here we determined the microbial diversity and community structure of 23 globally distributed methane seeps and compared these to the microbial communities of 54 other seafloor ecosystems, including sulfate-methane transition zones, hydrothermal vents, coastal sediments, and deep-sea surface and subsurface sediments. We found that methane seep communities show moderate levels of microbial richness compared with other seafloor ecosystems and harbor distinct bacterial and archaeal taxa with cosmopolitan distribution and key biogeochemical functions. The high relative sequence abundance of ANME (anaerobic methanotrophic archaea), as well as aerobic Methylococcales, sulfate-reducing Desulfobacterales, and sulfide-oxidizing Thiotrichales, matches the most favorable microbial metabolisms at methane seeps in terms of substrate supply and distinguishes the seep microbiome from other seafloor microbiomes. The key functional taxa varied in relative sequence abundance between different seeps due to the environmental factors, sediment depth and seafloor temperature. The degree of endemism of the methane seep microbiome suggests a high local diversification in these heterogeneous but long-lived ecosystems. Our results indicate that the seep microbiome is structured according to metacommunity processes and that few cosmopolitan microbial taxa mediate the bulk of methane oxidation, with global relevance to methane emission in the ocean.

  4. Modeling the Terrestrial Contribution to the Global Methane Balance

    NASA Astrophysics Data System (ADS)

    Smith, Amy Tetlow

    Most of the methane emitted into the atmosphere is produced microbiologically. Methanogenic bacteria in soils and sediments of natural wetlands are one of the largest sources of methane. The activity of these organisms is closely linked to environmental conditions. A climate -driven model of methane flux across the terrestrial surface is developed for analysis of atmosphere-biosphere interactions. The methane-flux model is based on temperature response of bacterial populations, and the requirement of anaerobic conditions for growth of methanogenic bacteria or the requirement of aerobic conditions for growth of methane-oxidizing bacteria. A biological inertia factor is also used to reflect dependence on previous bacterial conditions. Model parameters are fit for characteristic ecosystems based on the availability of appropriate time -series data. Using air temperature and precipitation climatologies as both direct and indirect model input, monthly methane fluxes are calculated for muskeg tundra, wet-meadow tundra, temperate and tropical wetlands, cool woods, and tropical savanna. Ecosystem models performed well in diverse environments. Annual -flux totals based on these models are consistent with published methane-budget estimates. To evaluate the global distribution of methane flux, emission estimates from rice cultivation, grazing animals, termites, biomass burning, and fossil fuel extraction and transportation are combined with the ecosystem-model estimates. The resulting global distribution of methane flux shows that the mid-latitudes of the northern hemisphere are the strongest methane source zone. Summer and fall are the most important emission seasons for in any latitudinal zone. My estimated atmospheric residence time of methane, calculated using this global-flux distribution, also agrees well with other published values.

  5. Kinetics of aerobic cometabolic biodegradation of chlorinated and brominated aliphatic hydrocarbons: A review.

    PubMed

    Jesus, João; Frascari, Dario; Pozdniakova, Tatiana; Danko, Anthony S

    2016-05-15

    This review analyses kinetic studies of aerobic cometabolism (AC) of halogenated aliphatic hydrocarbons (HAHs) from 2001-2015 in order to (i) compare the different kinetic models proposed, (ii) analyse the estimated model parameters with a focus on novel HAHs and the identification of general trends, and (iii) identify further research needs. The results of this analysis show that aerobic cometabolism can degrade a wide range of HAHs, including HAHs that were not previously tested such as chlorinated propanes, highly chlorinated ethanes and brominated methanes and ethanes. The degree of chlorine mineralization was very high for the chlorinated HAHs. Bromine mineralization was not determined for studies with brominated aliphatics. The examined research period led to the identification of novel growth substrates of potentially high interest. Decreasing performance of aerobic cometabolism were found with increasing chlorination, indicating the high potential of aerobic cometabolism in the presence of medium- and low-halogenated HAHs. Further research is needed for the AC of brominated aliphatic hydrocarbons, the potential for biofilm aerobic cometabolism processes, HAH-HAH mutual inhibition and the identification of the enzymes responsible for each aerobic cometabolism process. Lastly, some indications for a possible standardization of future kinetic studies of HAH aerobic cometabolism are provided.

  6. Kinetics of aerobic cometabolic biodegradation of chlorinated and brominated aliphatic hydrocarbons: A review.

    PubMed

    Jesus, João; Frascari, Dario; Pozdniakova, Tatiana; Danko, Anthony S

    2016-05-15

    This review analyses kinetic studies of aerobic cometabolism (AC) of halogenated aliphatic hydrocarbons (HAHs) from 2001-2015 in order to (i) compare the different kinetic models proposed, (ii) analyse the estimated model parameters with a focus on novel HAHs and the identification of general trends, and (iii) identify further research needs. The results of this analysis show that aerobic cometabolism can degrade a wide range of HAHs, including HAHs that were not previously tested such as chlorinated propanes, highly chlorinated ethanes and brominated methanes and ethanes. The degree of chlorine mineralization was very high for the chlorinated HAHs. Bromine mineralization was not determined for studies with brominated aliphatics. The examined research period led to the identification of novel growth substrates of potentially high interest. Decreasing performance of aerobic cometabolism were found with increasing chlorination, indicating the high potential of aerobic cometabolism in the presence of medium- and low-halogenated HAHs. Further research is needed for the AC of brominated aliphatic hydrocarbons, the potential for biofilm aerobic cometabolism processes, HAH-HAH mutual inhibition and the identification of the enzymes responsible for each aerobic cometabolism process. Lastly, some indications for a possible standardization of future kinetic studies of HAH aerobic cometabolism are provided. PMID:26874310

  7. Methane on Mars: Measurements and Possible Origins

    NASA Technical Reports Server (NTRS)

    Mumma, Michael J.; Villanueva, Geronimo L.; Novak, Robert E.; Radeva, Yana L.; Kaufl, H. Ulrich; Tokunaga, Alan; Encrenaz, Therese; Hartogh, Paul

    2011-01-01

    The presence of abundant methane in Earth's atmosphere (1.6 parts per million) requires sources other than atmospheric chemistry. Living systems produce more than 90% of Earth's atmospheric methane; the balance is of geochemical origin. On Mars, methane has been sought for nearly 40 years because of its potential biological significance, but it was detected only recently [1-5]. Its distribution on the planet is found to be patchy and to vary with time [1,2,4,5], suggesting that methane is released recently from the subsurface in localized areas, and is then rapidly destroyed [1,6]. Before 2000, searchers obtained sensitive upper limits for methane by averaging over much of Mars' dayside hemisphere, using data acquired by Marsorbiting spacecraft (Mariner 9) and Earth-based observatories (Kitt Peak National Observatory, Canada- France-Hawaii Telescope, Infrared Space Observatory). These negative findings suggested that methane should be searched at higher spatial resolution since the local abundance could be significantly larger at active sites. Since 2001, searches for methane have emphasized spatial mapping from terrestrial observatories and from Mars orbit (Mars Express).

  8. The effect of coal-bed methane water on spearmint and peppermint

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Coal bed methane (CBM) is extracted from underground coal seams, flooded with water. In order to reduce the pressure and release the methane, the trapped water needs to be pumped out. The resulting ‘waste water’ is known as coal-bed methane water (CBMW). Major concerns with the use of CBMW are the h...

  9. What's the Deal with Methane at LUST Spill Sites? Part 1

    EPA Science Inventory

    This article is specifically intended to discuss methane produced from releases of ethanol and gasoline-ethanol mixtures. There may be other sources of methane at a site, including leaks of natural gas or methane produced from the natural decay of buried plant tissues or from th...

  10. What's the Deal with Methane at LUST Spill Sites? Part 2: Vapor Intrusion

    EPA Science Inventory

    This article is specifically intended to discuss methane produced from releases of ethanol and gasoline-ethanol mixtures. There may be other sources of methane at a site, including leaks of natural gas or methane produced from the natural decay of buried plant tissues or from the...

  11. Methane emissions from cattle differing in feed intake and feed efficiency fed a high concentrate diet

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methane gas released by cattle is a product of fermentation of feed in the digestive tract and represents a loss of feed energy. In addition to being a dietary energy loss, methane is considered a greenhouse gas. Developing strategies to reduce methane emissions from cattle have the potential to i...

  12. Coal-bed methane water effects on dill and essential oils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pumping water from coal seams decreases the pressure in the seam and in turn releases trapped methane; this is the most common and economic way of methane extraction. The water that is pumped out is known as coal-bed methane water (CBMW), which is high in sodium and other salts. In past 25 years, th...

  13. Effects of oral nitroethane administration on enteric methane emissions and ruminal fermentation in cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methane is a potent greenhouse gas and its release to the atmosphere is considered to contribute to global warming. Ruminal enteric methane production represents a loss of 2% to 15% of the animal’s energy intake and contributes nearly 20% of the United States total methane emissions. Studies have ...

  14. Diversity of methanotrophs in Zoige wetland soils under both anaerobic and aerobic conditions.

    PubMed

    Yun, Juanli; Ma, Anzhou; Li, Yaoming; Zhuang, Guoqiang; Wang, Yanfen; Zhang, Hongxun

    2010-01-01

    Zoige wetland is one of the most important methane emission centers in China. The oxidation of methane in the wetland affects global warming, soil ecology and atmospheric chemistry. Despite their global significance, microorganisms that consume methane in Zoige wetland remain poorly characterized. In this study, we investigated methanotrophs diversity in soil samples from both anaerobic site and aerobic site in Zoige wetland using pmoA gene as a molecular marker. The cloning library was constructed according to the pmoA sequences detected. Four clusters of methanotrophs were detected. The phylogenetic tree showed that all four clusters detected were affiliated to type I methanotrophs. Two novel clusters (cluster 1, cluster 2) were found to relate to none of the recognized genera of methanotrophs. These clusters have no cultured representatives and reveal an ecological adaptation of particular uncultured methanotrophs in Zoige wetland. Two clusters were belonging to Methylobacter and Methylococcus separately. Denaturing gradient gel electrophoresis gel bands pattern retrieved from these two samples revealed that the community compositions of anaerobic soil and aerobic soil were different from each other while anaerobic soil showed a higher metanotrophs diversity. Real-time PCR assays of the two samples demonstrated that aerobic soil sample in Zoige wetland was 1.5 times as much copy numbers as anaerobic soil. These data illustrated that methanotrophs are a group of microorganisms influence the methane consumption in Zoige wetland.

  15. Comparison of biogas recovery from MSW using different aerobic-anaerobic operation modes.

    PubMed

    Xu, Qiyong; Tian, Ying; Kim, Hwidong; Ko, Jae Hac

    2016-10-01

    Aeration pretreatment was demonstrated as an efficient technology to promote methane recovery from a bioreactor landfill with high food waste content. In this study, a short-term experiment was conducted to investigate the effects of aerobic-anaerobic operation modes on biogas recovery. Three landfill-simulated columns (anaerobic control (A1), a constant aeration (C1) and a gradually reduced aeration (C2)) were constructed and operated for 130days. The aeration frequency was adjusted by oxygen consumption in an aerated MSW landfill. After aerobic pretreatment was halted, the methanogenic phase was rapidly developed in both the C1 and C2 columns, reducing the volatile fatty acid (VFA) concentrations and increasing pH. The methane volumes per dry MSW produced from the C1 and C2 columns were approximately 62L/kg VS and 75L/kg VS, respectively, while methane produced from the A1 column was almost negligible. The result clearly showed that aerobic pretreatment with gradual reduction of aeration rates could not only improve methane recovery from waste decomposition, but also enhance leachate COD and VFA removal. PMID:27426021

  16. Methane Trapping Capacity of the Early Martian Cryosphere

    NASA Astrophysics Data System (ADS)

    Lasue, J.; Langlais, B.; Quesnel, Y.; Chassefière, E.

    2014-07-01

    We demonstrate that the methane trapping capacity of the early martian cryosphere is comparable to the quantity possibly released by the early serpentinization that would have been necessary to generate the observed martian remanent magnetic field.

  17. Methane Plumes on Mars

    NASA Video Gallery

    Spectrometer instruments attached to several telescopes detect plumes of methane emitted from Mars during its summer and spring seasons. High levels of methane are indicated by warmer colors. The m...

  18. Up with methane

    SciTech Connect

    Barlaz, M.A.; Milke, M.W.; Ham, R.K.

    1986-12-01

    Methane production from municipal refuse represents a rapidly developing source of energy which remains underutilized. Part of the problem is the small amount of methane which is typically collected relative to the refuse's methane generation potential. This study was undertaken to define the parameters which affect the onset of methane production and methane yields in sanitary landfills. Ultimately, we need to develop refuse disposal methods which enhance its methane production potential. Included in the study were tests of how introduction of old refuse, use of sterile cover soil, addition of acetate to refuse, and use of leachate, recycling and neutralization affect methane generation. A more thorough understanding of how the microbes present in refuse react to different variables is the first step in the development of techniques for stimulating methane production in sanitary landfills.

  19. Identification of active aerobic methanotrophs in plateau wetlands using DNA stable isotope probing.

    PubMed

    Deng, Yongcui; Cui, Xiaoyong; Dumont, Marc G

    2016-08-01

    Sedge-dominated wetlands on the Qinghai-Tibetan Plateau are methane emission centers. Methanotrophs at these sites play a role in reducing methane emissions, but relatively little is known about the composition of active methanotrophs in these wetlands. Here, we used DNA stable isotope probing to identify the key active aerobic methanotrophs in three sedge-dominated wetlands on the plateau. We found that Methylocystis species were active in two peatlands, Hongyuan and Dangxiong. Methylobacter species were found to be active only in Dangxiong peat. Hongyuan peat had the highest methane oxidation rate, and cross-feeding of carbon from methanotrophs to methylotrophic Hyphomicrobium species was observed. Owing to a low methane oxidation rate during the incubation, the labeling of methanotrophs in Maduo wetland samples was not detected. Our results indicate that there are large differences in the activity of methanotrophs in the wetlands of this region. PMID:27369086

  20. Quantifying factors limiting aerobic degradation during aerobic bioreactor landfilling.

    PubMed

    Yazdani, Ramin; Mostafid, M Erfan; Han, Byunghyun; Imhoff, Paul T; Chiu, Pei; Augenstein, Don; Kayhanian, Masoud; Tchobanoglous, George

    2010-08-15

    A bioreactor landfill cell at Yolo County, California was operated aerobically for six months to quantify the extent of aerobic degradation and mechanisms limiting aerobic activity during air injection and liquid addition. The portion of the solid waste degraded anaerobically was estimated and tracked through time. From an analysis of in situ aerobic respiration and gas tracer data, it was found that a large fraction of the gas-filled pore space was in immobile zones where it was difficult to maintain aerobic conditions, even at relatively moderate landfill cell-average moisture contents of 33-36%. Even with the intentional injection of air, anaerobic activity was never less than 13%, and sometimes exceeded 65%. Analyses of gas tracer and respiration data were used to quantify rates of respiration and rates of mass transfer to immobile gas zones. The similarity of these rates indicated that waste degradation was influenced significantly by rates of oxygen transfer to immobile gas zones, which comprised 32-92% of the gas-filled pore space. Gas tracer tests might be useful for estimating the size of the mobile/immobile gas zones, rates of mass transfer between these regions, and the difficulty of degrading waste aerobically in particular waste bodies. PMID:20704218

  1. Heat pipe methanator

    DOEpatents

    Ranken, William A.; Kemme, Joseph E.

    1976-07-27

    A heat pipe methanator for converting coal gas to methane. Gravity return heat pipes are employed to remove the heat of reaction from the methanation promoting catalyst, transmitting a portion of this heat to an incoming gas pre-heat section and delivering the remainder to a steam generating heat exchanger.

  2. Molecular and isotopic insights into methane oxidation in Lake Kivu

    NASA Astrophysics Data System (ADS)

    Zigah, P. K.; Wehrli, B.; Schubert, C. J.

    2013-12-01

    Lake Kivu is a meromictic lake in the East African Rift Valley, located between the Republic of Rwanda and the Democratic Republic of Congo. The hypolimnion is permanently stratified and contain an unusually high amount of dissolved methane (CH4; ~ 60 km3) and carbon dioxide (CO2; ~300 km3) at standard temperature and pressure. While microbial-mediated methane oxidation is an important sink of methane in the lake, little is known about the distribution of microbes involved in the methane oxidation. To provide insights into methanotrophy in the lake, we analyzed depth profile of CH4, δ13C-CH4 and δ13C-DIC, δ13C-POC and the biomarkers of methanotrophic archaea and bacteria and their stable carbon isotopic composition from suspended particulate matter isolated from the lake water column. Our preliminary data show enhanced methane oxidation in oxic-anoxic transition zone in the water column. Depth distribution of diagnostic methanotrophic archaeal biomarkers such as archaeol and hydroxyarchaeol suggest archaea might be involved in anaerobic methane oxidation. Phospholipid fatty acids and diplopterol distribution and carbon isotopic signatures indicate bacteria-mediated anaerobic (and aerobic) methane oxidation in the lake.

  3. Ground and Airborne Methane Measurements using Optical Parametric Amplifiers

    NASA Astrophysics Data System (ADS)

    Numata, K.; Riris, H.; Li, S.; Wu, S.; Kawa, S. R.; Abshire, J. B.; Dawsey, M.; Ramanathan, A.

    2011-12-01

    We report on ground and airborne methane measurements with an active sensing instrument using widely tunable, seeded optical parametric generation (OPG). The technique has been used to measure methane, CO2, water vapor, and other trace gases in the near and mid-infrared spectral regions. Methane is a strong greenhouse gas on Earth and it is also a potential biogenic marker on Mars and other planetary bodies. Methane in the Earth's atmosphere survives for a shorter time than CO2 but its impact on climate change can be larger than CO2. Carbon and methane emissions from land are expected to increase as permafrost melts exposing millennial-age carbon stocks to respiration (aerobic-CO2 and anaerobic-CH4) and fires. Methane emissions from clathrates in the Arctic Ocean and on land are also likely to respond to climate warming. However, there is considerable uncertainty in present Arctic flux levels, as well as how fluxes will change with the changing environment. For Mars, methane measurements are of great interest because of its potential as a strong biogenic marker. A remote sensing instrument that can measure day and night over all seasons and latitudes can localize sources of biogenic gas plumes produced by subsurface chemistry or biology, and aid in the search for extra-terrestrial life. In this paper we report on remote sensing measurements of methane using a high peak power, widely tunable optical parametric generator (OPG) operating at 3.3 um and 1.65 um. We have demonstrated detection of methane at 3.3 μm and 1650 nm in an open path and compared them to accepted standards. We also report on preliminary airborne demonstration of methane measurements at 1.65 um.

  4. Ground and Airborne Methane Measurements Using Optical Parametric Amplifiers

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Riris, Haris; Li, Steve; Wu, Stewart; Kawa, Stephan R.; Abshire, James Brice; Dawsey, Martha; Ramanathan, Anand

    2011-01-01

    We report on ground and airborne methane measurements with an active sensing instrument using widely tunable, seeded optical parametric generation (OPG). The technique has been used to measure methane, CO2, water vapor, and other trace gases in the near and mid-infrared spectral regions. Methane is a strong greenhouse gas on Earth and it is also a potential biogenic marker on Mars and other planetary bodies. Methane in the Earth's atmosphere survives for a shorter time than CO2 but its impact on climate change can be larger than CO2. Carbon and methane emissions from land are expected to increase as permafrost melts exposing millennial-age carbon stocks to respiration (aerobic-CO2 and anaerobic-CH4) and fires. Methane emissions from c1athrates in the Arctic Ocean and on land are also likely to respond to climate warming. However, there is considerable uncertainty in present Arctic flux levels, as well as how fluxes will change with the changing environment. For Mars, methane measurements are of great interest because of its potential as a strong biogenic marker. A remote sensing instrument that can measure day and night over all seasons and latitudes can localize sources of biogenic gas plumes produced by subsurface chemistry or biology, and aid in the search for extra-terrestrial life. In this paper we report on remote sensing measurements of methane using a high peak power, widely tunable optical parametric generator (OPG) operating at 3.3 micrometers and 1.65 micrometers. We have demonstrated detection of methane at 3.3 micrometers and 1650 nanometers in an open path and compared them to accepted standards. We also report on preliminary airborne demonstration of methane measurements at 1.65 micrometers.

  5. Comparison of Aerobic and Anaerobic Biodegradation of Sugarcane Vinasse.

    PubMed

    Mota, V T; Araújo, T A; Amaral, M C S

    2015-07-01

    Vinasse is the main liquid waste from ethanol production, and it has a considerable pollution potential. Biological treatment is a promising alternative to reduce its organic load. The aim of this study was to analyze the biodegradation of sugarcane juice vinasse in aerobic and anaerobic conditions. The content of carbohydrates, proteins and volatile fatty acids was evaluated. Vinasse samples showed a high biodegradability (>96.5 %) and low percentage of inert chemical oxygen demand (COD) (<3.2 %) in both aerobic and anaerobic conditions. The rates of substrate utilization were slightly higher in aerobic reactors, but COD stabilization occurred simultaneously in the anaerobic reactors, confirming its suitability for anaerobic digestion. Inert COD in anaerobic conditions was lower than in aerobic conditions. On the other hand, COD from metabolic products in the anaerobic reactors was higher than in the aerobic ones, indicating an increased release of soluble microbial products (SMPs) by anaerobic microorganisms. The results indicated that carbohydrates were satisfactorily degraded and protein-like substances were the major components remaining after biological degradation of vinasse. PMID:25957273

  6. Sedimentary Rocks and Methane - Southwest Arabia Terra

    NASA Technical Reports Server (NTRS)

    Allen, Carlton C.; Oehler, Dorothy Z.; Venechuk, Elizabeth M.

    2006-01-01

    We propose to land the Mars Science Laboratory in southwest Arabia Terra to study two key aspects of martian history the extensive record of sedimentary rocks and the continuing release of methane. The results of this exploration will directly address the MSL Scientific Objectives regarding biological potential, geology and geochemistry, and past habitability.

  7. News from the "blowout", a man-made methane pockmark in the North Sea: chemosynthetic communities and microbial methane oxidation

    NASA Astrophysics Data System (ADS)

    Steinle, Lea I.; Wilfert, Philipp; Schmidt, Mark; Bryant, Lee; Haeckel, Matthias; Lehmann, Moritz F.; Linke, Peter; Sommer, Stefan; Treude, Tina; Niemann, Helge

    2013-04-01

    The accidental penetration of a base-Quaternary shallow gas pocket by a drilling rig in 1990 caused a "blowout" in the British sector of the North Sea (57°55.29' N, 01°37.86' E). Large quantities of methane have been seeping out of this man-made pockmark ever since. As the onset of gas seepage is well constrained, this site can be used as a natural laboratory to gain information on the development of methane oxidizing microbial communities at cold seeps. During an expedition with the R/V Celtic Explorer in July and August 2012, we collected sediments by video-guided push-coring with an ROV (Kiel 6000) along a gradient from inside the crater (close to where a jet of methane bubbles enters the water column) outwards. We also sampled the water column in a grid above the blowout at three different depths. In this presentation, we provide evidence for the establishment of methanotrophic communities in the sediment (AOM communities) on a time scale of decades. Furthermore, we will report data on methane concentrations and anaerobic methane oxidation rates in the sediment. Finally, we will also discuss the spatial distribution of methane and aerobic methane oxidation rates in the water column.

  8. Enhanced lifetime of methane bubble streams within the deep ocean

    NASA Astrophysics Data System (ADS)

    Rehder, Gregor; Brewer, Peter W.; Peltzer, Edward T.; Friederich, Gernot

    2002-08-01

    We have made direct comparisons of the dissolution and rise rates of methane and argon bubbles experimentally released in the ocean at depths from 440 to 830 m. The bubbles were injected from the ROV Ventana into a box open at the top and the bottom, and imaged by HDTV while in free motion. The vehicle was piloted upwards at the rise rate of the bubbles. Methane and argon show closely similar behavior at depths above the methane hydrate stability field. Below that boundary (~520 m) markedly enhanced methane bubble lifetimes are observed, and are attributed to the formation of a hydrate skin. This effect greatly increases the ease with which methane gas released at depth, either by natural or industrial events, can penetrate the shallow ocean layers.

  9. Martian Methane From a Cometary Source: A Hypothesis

    NASA Technical Reports Server (NTRS)

    Fries, M.; Christou, A.; Archer, D.; Conrad, P.; Cooke, W.; Eigenbrode, J.; ten Kate, I. L.; Matney, M.; Niles, P.; Sykes, M.; Steele, A.; Treiman, A.

    2016-01-01

    In recent years, methane in the martian atmosphere has been detected by Earth-based spectroscopy, the Planetary Fourier Spectrometer on the ESA Mars Express mission, and the NASA Mars Science Laboratory. The methane's origin remains a mystery, with proposed sources including volcanism, exogenous sources like impacts and interplanetary dust, aqueous alteration of olivine in the presence of carbonaceous material, release from ancient deposits of methane clathrates, and/or biological activity. An additional potential source exists: meteor showers from the emission of large comet dust particles could generate martian methane via UV pyrolysis of carbon-rich infall material. We find a correlation between the dates of Mars/cometary orbit encounters and detections of methane on Mars. We hypothesize that cometary debris falls onto Mars during these interactions, generating methane via UV photolysis.

  10. Nitrate-dependent anaerobic methane oxidation in a freshwater sediment

    NASA Astrophysics Data System (ADS)

    Norði, Katrin á.; Thamdrup, Bo

    2014-05-01

    Anaerobic oxidation of methane coupled to denitrification (DAOM) is a novel process of potential importance to the regulation of methane emissions from freshwater environments. We established nitrate-enriched microcosms of sediment from a freshwater pond in order to quantify the role of this process in a simulated natural redox zonation. The microcosms were allowed to acclimate to nitrate levels of 1-2 mmol L-1 in the overlying water for 16 months leading to a nitrate penetration of 4 cm. The nitrate enrichment significantly stimulated AOM relative to controls, and based on the similar concentrations of sulfate and reactive Fe(III) in the control sediment we conclude that the observed AOM was coupled to denitrification. DAOM occurred at rates that were two orders of magnitude lower than aerobic methane oxidation rates reported in freshwater sediments, and the process appeared to be limited by nitrate or nitrite even at millimolar nitrate concentrations. By contrast, ammonium was efficiently consumed at the base of the nitrate zone, presumably by the anammox process. Although DAOM was stimulated by nitrate enrichment, there were no significant differences between the methane emission from the control and nitrate-enriched microcosms. Our results provide the first experimental evaluation of the kinetics of DAOM in whole sediment cores and indicate that AOM coupled to denitrification can consume a substantial part of the methane flux in nitrate-rich environments. Because it is much less efficient in scavenging methane than its aerobic counterpart, the anaerobic process will, however, mainly be of significance in the regulation of methane emission from oxygen-depleted systems.

  11. Methane photochemistry and methane production on Neptune

    NASA Astrophysics Data System (ADS)

    Romani, P. N.; Atreya, S. K.

    1988-06-01

    The Neptune stratosphere's methane photochemistry is presently studied by means of a numerical model in which the observed mixing ratio of methane prompts photolysis near the CH4 homopause. Haze generation by methane photochemistry has its basis in the formation of hydrocarbon ices and polyacetylenes; the hazes can furnish the requisite aerosol haze at the appropriate pressure levels required by observations of Neptune in the visible and near-IR. Comparisons of model predictions with Uranus data indicate a lower ratio of polyacetylene production to hydrocarbon ice, as well as a lower likelihood of UV postprocessing of the acetylene ice to polymers on Neptune, compared to Uranus.

  12. Methane photochemistry and methane production on Neptune

    NASA Technical Reports Server (NTRS)

    Romani, P. N.; Atreya, S. K.

    1988-01-01

    The Neptune stratosphere's methane photochemistry is presently studied by means of a numerical model in which the observed mixing ratio of methane prompts photolysis near the CH4 homopause. Haze generation by methane photochemistry has its basis in the formation of hydrocarbon ices and polyacetylenes; the hazes can furnish the requisite aerosol haze at the appropriate pressure levels required by observations of Neptune in the visible and near-IR. Comparisons of model predictions with Uranus data indicate a lower ratio of polyacetylene production to hydrocarbon ice, as well as a lower likelihood of UV postprocessing of the acetylene ice to polymers on Neptune, compared to Uranus.

  13. Methane photochemistry and methane production on Neptune

    SciTech Connect

    Romani, P.N.; Atreya, S.K.

    1988-06-01

    The Neptune stratosphere's methane photochemistry is presently studied by means of a numerical model in which the observed mixing ratio of methane prompts photolysis near the CH4 homopause. Haze generation by methane photochemistry has its basis in the formation of hydrocarbon ices and polyacetylenes; the hazes can furnish the requisite aerosol haze at the appropriate pressure levels required by observations of Neptune in the visible and near-IR. Comparisons of model predictions with Uranus data indicate a lower ratio of polyacetylene production to hydrocarbon ice, as well as a lower likelihood of UV postprocessing of the acetylene ice to polymers on Neptune, compared to Uranus. 65 references.

  14. Late Archean rise of aerobic microbial ecosystems

    PubMed Central

    Eigenbrode, Jennifer L.; Freeman, Katherine H.

    2006-01-01

    We report the 13C content of preserved organic carbon for a 150 million-year section of late Archean shallow and deepwater sediments of the Hamersley Province in Western Australia. We find a 13C enrichment of ≈10‰ in organic carbon of post-2.7-billion-year-old shallow-water carbonate rocks relative to deepwater sediments. The shallow-water organic-carbon 13C content has a 29‰ range in values (−57 to −28‰), and it contrasts with the less variable but strongly 13C-depleted (−40 to −45‰) organic carbon in deepwater sediments. The 13C enrichment likely represents microbial habitats not as strongly influenced by assimilation of methane or other 13C-depleted substrates. We propose that continued oxidation of shallow settings favored the expansion of aerobic ecosystems and respiring organisms, and, as a result, isotopic signatures of preserved organic carbon in shallow settings approached that of photosynthetic biomass. Facies analysis of published carbon-isotopic records indicates that the Hamersley shallow-water signal may be representative of a late Archean global signature and that it preceded a similar, but delayed, 13C enrichment of deepwater deposits. The data suggest that a global-scale expansion of oxygenated habitats accompanied the progression away from anaerobic ecosystems toward respiring microbial communities fueled by oxygenic photosynthesis before the oxygenation of the atmosphere after 2.45 billion years ago. PMID:17043234

  15. Titan's Methane Cycle is Closed

    NASA Astrophysics Data System (ADS)

    Hofgartner, J. D.; Lunine, J. I.

    2013-12-01

    Doppler tracking of the Cassini spacecraft determined a polar moment of inertia for Titan of 0.34 (Iess et al., 2010, Science, 327, 1367). Assuming hydrostatic equilibrium, one interpretation is that Titan's silicate core is partially hydrated (Castillo-Rogez and Lunine, 2010, Geophys. Res. Lett., 37, L20205). These authors point out that for the core to have avoided complete thermal dehydration to the present day, at least 30% of the potassium content of Titan must have leached into an overlying water ocean by the end of the core overturn. We calculate that for probable ammonia compositions of Titan's ocean (compositions with greater than 1% ammonia by weight), that this amount of potassium leaching is achievable via the substitution of ammonium for potassium during the hydration epoch. Formation of a hydrous core early in Titan's history by serpentinization results in the loss of one hydrogen molecule for every hydrating water molecule. We calculate that complete serpentinization of Titan's core corresponds to the release of more than enough hydrogen to reconstitute all of the methane atoms photolyzed throughout Titan's history. Insertion of molecular hydrogen by double occupancy into crustal clathrates provides a storage medium and an opportunity for ethane to be converted back to methane slowly over time--potentially completing a cycle that extends the lifetime of methane in Titan's surface atmosphere system by factors of several to an order of magnitude over the photochemically-calculated lifetime.

  16. Methane emission from sewers.

    PubMed

    Liu, Yiwen; Ni, Bing-Jie; Sharma, Keshab R; Yuan, Zhiguo

    2015-08-15

    Recent studies have shown that sewer systems produce and emit a significant amount of methane. Methanogens produce methane under anaerobic conditions in sewer biofilms and sediments, and the stratification of methanogens and sulfate-reducing bacteria may explain the simultaneous production of methane and sulfide in sewers. No significant methane sinks or methanotrophic activities have been identified in sewers to date. Therefore, most of the methane would be emitted at the interface between sewage and atmosphere in gravity sewers, pumping stations, and inlets of wastewater treatment plants, although oxidation of methane in the aeration basin of a wastewater treatment plant has been reported recently. Online measurements have also revealed highly dynamic temporal and spatial variations in methane production caused by factors such as hydraulic retention time, area-to-volume ratio, temperature, and concentration of organic matter in sewage. Both mechanistic and empirical models have been proposed to predict methane production in sewers. Due to the sensitivity of methanogens to environmental conditions, most of the chemicals effective in controlling sulfide in sewers also suppress or diminish methane production. In this paper, we review the recent studies on methane emission from sewers, including the production mechanisms, quantification, modeling, and mitigation. PMID:25889543

  17. Methane emission from sewers.

    PubMed

    Liu, Yiwen; Ni, Bing-Jie; Sharma, Keshab R; Yuan, Zhiguo

    2015-08-15

    Recent studies have shown that sewer systems produce and emit a significant amount of methane. Methanogens produce methane under anaerobic conditions in sewer biofilms and sediments, and the stratification of methanogens and sulfate-reducing bacteria may explain the simultaneous production of methane and sulfide in sewers. No significant methane sinks or methanotrophic activities have been identified in sewers to date. Therefore, most of the methane would be emitted at the interface between sewage and atmosphere in gravity sewers, pumping stations, and inlets of wastewater treatment plants, although oxidation of methane in the aeration basin of a wastewater treatment plant has been reported recently. Online measurements have also revealed highly dynamic temporal and spatial variations in methane production caused by factors such as hydraulic retention time, area-to-volume ratio, temperature, and concentration of organic matter in sewage. Both mechanistic and empirical models have been proposed to predict methane production in sewers. Due to the sensitivity of methanogens to environmental conditions, most of the chemicals effective in controlling sulfide in sewers also suppress or diminish methane production. In this paper, we review the recent studies on methane emission from sewers, including the production mechanisms, quantification, modeling, and mitigation.

  18. Importance of the autumn overturn and anoxic conditions in the hypolimnion for the annual methane emissions from a temperate lake.

    PubMed

    Encinas Fernández, Jorge; Peeters, Frank; Hofmann, Hilmar

    2014-07-01

    Changes in the budget of dissolved methane measured in a small temperate lake over 1 year indicate that anoxic conditions in the hypolimnion and the autumn overturn period represent key factors for the overall annual methane emissions from lakes. During periods of stable stratification, large amounts of methane accumulate in anoxic deep waters. Approximately 46% of the stored methane was emitted during the autumn overturn, contributing ∼80% of the annual diffusive methane emissions to the atmosphere. After the overturn period, the entire water column was oxic, and only 1% of the original quantity of methane remained in the water column. Current estimates of global methane emissions assume that all of the stored methane is released, whereas several studies of individual lakes have suggested that a major fraction of the stored methane is oxidized during overturns. Our results provide evidence that not all of the stored methane is released to the atmosphere during the overturn period. However, the fraction of stored methane emitted to the atmosphere during overturn may be substantially larger and the fraction of stored methane oxidized may be smaller than in the previous studies suggesting high oxidation losses of methane. The development or change in the vertical extent and duration of the anoxic hypolimnion, which can represent the main source of annual methane emissions from small lakes, may be an important aspect to consider for impact assessments of climate warming on the methane emissions from lakes.

  19. Ruminant Methane δ (13C/12C) - Values: Relation to Atmospheric Methane

    NASA Astrophysics Data System (ADS)

    Rust, Fleet

    1981-03-01

    The δ (13C/12C) - values of methane produced by fistulated steers, dairy cattle, and wethers, and dairy and beef cattle herds show a bimodal distribution that appears to be correlated with the plant type (C3 or C4, that is, producing either a three- or a four-carbon acid in the first step of photosynthesis) consumed by the animals. These results indicate that cattle and sheep, on a global basis, release methane with an average δ (13C/12C) value of -60 and -63 per mil, respectively. Together they are a source of atmospheric methane whose δ (13C/12C) is similar to published values for marsh gas and cannot explain the 20 per mil higher values for atmospheric methane.

  20. Using the Deepwater Horizon Disaster to Investigate Natural Biogeochemical Cycling Associated with Rapid Methane Emissions (Invited)

    NASA Astrophysics Data System (ADS)

    Kessler, J. D.; Valentine, D. L.; Yvon-Lewis, S. A.; Heintz, M. B.; Hu, L.; Garcia Tigreros, F.; Du, M.; Chan, E. W.

    2010-12-01

    On April 20, a violent methane discharge severed the Deepwater Horizon rig from its well and oil and gas began spilling into the deep Gulf of Mexico at depths of ca. 1.5 km simulating a natural, rapid, and short-term methane release in deepwater. Given the estimated rates of emission of total material as well as the fraction methane by weight, one can estimate that a total of 0.1 to 0.3 Tg (10^12 g) of methane were emitted from a localized area in only 83 days. Measurements of methane oxidation and sea-air methane flux were measured in June indicating that at that time, oxidation rates were slow and sea-air fluxes were relatively insignificant. A deepwater methane plume was identified and in June 2010, the depth of the methane plume was on average from 950 - 1150 m with the maximum methane concentration measured being 183 μM. Analyses of diffusion, advective mixing, and methane oxidation were used to estimate that this plume has a lifetime of years to decades with the main controlling factor being the rate of methane oxidation. The persistent nature of this deepwater methane plume allows it to be used as a natural laboratory to investigate key hypotheses concerning the biogeochemical cycling of methane and oxygen associated with rapid, short-term methane discharges.

  1. Method for removal of methane from coalbeds

    DOEpatents

    Pasini, III, Joseph; Overbey, Jr., William K.

    1976-01-01

    A method for removing methane gas from underground coalbeds prior to mining the coal which comprises drilling at least one borehole from the surface into the coalbed. The borehole is started at a slant rather than directly vertically, and as it descends, a gradual curve is followed until a horizontal position is reached where the desired portion of the coalbed is intersected. Approaching the coalbed in this manner and fracturing the coalbed in the major natural fraction direction cause release of large amounts of the trapped methane gas.

  2. Anaerobic oxidation of methane: an "active" microbial process.

    PubMed

    Cui, Mengmeng; Ma, Anzhou; Qi, Hongyan; Zhuang, Xuliang; Zhuang, Guoqiang

    2015-02-01

    The anaerobic oxidation of methane (AOM) is an important sink of methane that plays a significant role in global warming. AOM was first found to be coupled with sulfate reduction and mediated by anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB). ANME, often forming consortia with SRB, are phylogenetically related to methanogenic archaea. ANME-1 is even able to produce methane. Subsequently, it has been found that AOM can also be coupled with denitrification. The known microbes responsible for this process are Candidatus Methylomirabilis oxyfera (M. oxyfera) and Candidatus Methanoperedens nitroreducens (M. nitroreducens). Candidatus Methylomirabilis oxyfera belongs to the NC10 bacteria, can catalyze nitrite reduction through an "intra-aerobic" pathway, and may catalyze AOM through an aerobic methane oxidation pathway. However, M. nitroreducens, which is affiliated with ANME-2d archaea, may be able to catalyze AOM through the reverse methanogenesis pathway. Moreover, manganese (Mn(4+) ) and iron (Fe(3+) ) can also be used as electron acceptors of AOM. This review summarizes the mechanisms and associated microbes of AOM. It also discusses recent progress in some unclear key issues about AOM, including ANME-1 in hypersaline environments, the effect of oxygen on M. oxyfera, and the relationship of M. nitroreducens with ANME. PMID:25530008

  3. Methanotrophy potential versus methane supply by pore water diffusion in peatlands

    NASA Astrophysics Data System (ADS)

    Hornibrook, E. R. C.; Bowes, H. L.; Culbert, A.; Gallego-Sala, A. V.

    2009-08-01

    Low affinity methanotrophic bacteria consume a significant quantity of methane in wetland soils in the vicinity of plant roots and at the oxic-anoxic interface. Estimates of the efficiency of methanotrophy in peat soils vary widely in part because of differences in approaches employed to quantify methane cycling. High resolution profiles of dissolved methane abundance measured during the summer of 2003 were used to quantity rates of upward methane flux in four peatlands situated in Wales, UK. Aerobic incubations of peat from a minerotrophic and an ombrotrophic mire were used to determine depth distributions of kinetic parameters associated with methane oxidation. The capacity for methanotrophy in a 3 cm thick zone immediately beneath the depth of nil methane abundance in pore water was significantly greater than the rate of upward diffusion of methane in all four peatlands. Rates of methane diffusion in pore water at the minerotrophic peatlands were small (<10%) compared to surface emissions during June to August. The proportions were notably greater in the ombrotrophic bogs because of their typically low methane emission rates. Methanotrophy appears to consume entirely methane transported by pore water diffusion in the four peatlands with the exception of 4 of the 33 gas profiles sampled. Flux rates to the atmosphere regardless are high because of gas transport through vascular plants, in particular, at the minerotrophic sites. Cumulative rainfall amount 3-days prior to sampling correlated well with the distance between the water table level and the depth of 0 μmol l-1 methane, indicating that precipitation events can impact methane distributions in pore water. Further work is needed to characterise the kinetics of methane oxidation spatially and temporally in different wetland types in order to determine generalized relationships for methanotrophy in peatlands that can be incorporated into process-based models of methane cycling in peat soils.

  4. Methane-Powered Vehicles

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Liquid methane is beginning to become an energy alternative to expensive oil as a power source for automotive vehicles. Methane is the principal component of natural gas, costs less than half as much as gasoline, and its emissions are a lot cleaner than from gasoline or diesel engines. Beech Aircraft Corporation's Boulder Division has designed and is producing a system for converting cars and trucks to liquid methane operation. Liquid methane (LM) is a cryogenic fuel which must be stored at a temperature of 260 degrees below zero Fahrenheit. The LM system includes an 18 gallon fuel tank in the trunk and simple "under the hood" carburetor conversion equipment. Optional twin-fuel system allows operator to use either LM or gasoline fuel. Boulder Division has started deliveries for 25 vehicle conversions and is furnishing a liquid methane refueling station. Beech is providing instruction for Northwest Natural Gas, for conversion of methane to liquid state.

  5. Mars methane engine

    NASA Technical Reports Server (NTRS)

    Bui, Hung; Coletta, Chris; Debois, Alain

    1994-01-01

    The feasibility of an internal combustion engine operating on a mixture of methane, carbon dioxide, and oxygen has been verified by previous design groups for the Mars Methane Engine Project. Preliminary stoichiometric calculations examined the theoretical fuel-air ratios needed for the combustion of methane. Installation of a computer data acquisition system along with various ancillary components will enable the performance of the engine, running on the described methane mixture, to be optimized with respect to minimizing excess fuel. Theoretical calculations for stoichiometric combustion of methane-oxygen-carbon dioxide mixtures yielded a ratio of 1:2:4.79 for a methane-oxygen-carbon dioxide mixture. Empirical data shows the values to be closer to 1:2.33:3.69 for optimum operation.

  6. Atmospheric methane emissions along the western Svalbard margin

    NASA Astrophysics Data System (ADS)

    Pohlman, J.; Greinert, J.; Silyakova, A.; Casso, M.; Ruppel, C. D.; Mienert, J.; Lund Myhre, C.; Bunz, S.

    2014-12-01

    Documented warming of intermediate waters by ~1oC over the past 30 years along the western Svalbard margin has been suggested as a driver of climate-change induced dissociation of marine methane hydrate. However, recent evidence suggests methane release from gas hydrate has been occurring for thousands of years near the upper limit of methane hydrate stability and that seasonal changes in bottom water temperature may be more important than longer-term warming of intermediate waters. Nevertheless, this area has been and remains an active area for researching the physical and climate controls of methane release from the seafloor, yet the amount of methane reaching the atmosphere (the ultimate climate driver) in this region is largely unknown. As part of the MOCA project led by the Norwegian Institute for Air Research (NILU), water column and atmospheric marine boundary layer methane data were collected in June 2014 aboard the R/V Helmer Hanssenduring a collaboration among CAGE at University of Tromsӧ, NILU, GEOMAR, and the USGS. The results provide a continuous record of surface methane concentration and carbon isotope data from continental slope sites near temperature-sensitive hydrate-bearing seeps along the shelf-break and upper slope, the deep-water pockmarked gas-venting Vestnesa Ridge and a shallow water seep area within the Forlandet moraine complex at the shelf. Surface water methane and associated data used to calculate sea-air fluxes were obtained with the cavity ring-down spectrometer-based USGS Gas Analysis System (USGS-GAS). Only the shallow seep site (~90 m water depth) had appreciable methane in surface waters. We conducted an exhaustive survey of this site, mapping the full extent of the surface methane plume. To provide three-dimensional constraints, we acquired 65 vertical dissolved methane profiles to delineate the vertical and horizontal extent of the subsurface methane plume. Using these data, we assess how effectively shallow arctic seeps

  7. Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming.

    PubMed

    Walter, K M; Zimov, S A; Chanton, J P; Verbyla, D; Chapin, F S

    2006-09-01

    Large uncertainties in the budget of atmospheric methane, an important greenhouse gas, limit the accuracy of climate change projections. Thaw lakes in North Siberia are known to emit methane, but the magnitude of these emissions remains uncertain because most methane is released through ebullition (bubbling), which is spatially and temporally variable. Here we report a new method of measuring ebullition and use it to quantify methane emissions from two thaw lakes in North Siberia. We show that ebullition accounts for 95 per cent of methane emissions from these lakes, and that methane flux from thaw lakes in our study region may be five times higher than previously estimated. Extrapolation of these fluxes indicates that thaw lakes in North Siberia emit 3.8 teragrams of methane per year, which increases present estimates of methane emissions from northern wetlands (< 6-40 teragrams per year; refs 1, 2, 4-6) by between 10 and 63 per cent. We find that thawing permafrost along lake margins accounts for most of the methane released from the lakes, and estimate that an expansion of thaw lakes between 1974 and 2000, which was concurrent with regional warming, increased methane emissions in our study region by 58 per cent. Furthermore, the Pleistocene age (35,260-42,900 years) of methane emitted from hotspots along thawing lake margins indicates that this positive feedback to climate warming has led to the release of old carbon stocks previously stored in permafrost. PMID:16957728

  8. Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming.

    PubMed

    Walter, K M; Zimov, S A; Chanton, J P; Verbyla, D; Chapin, F S

    2006-09-01

    Large uncertainties in the budget of atmospheric methane, an important greenhouse gas, limit the accuracy of climate change projections. Thaw lakes in North Siberia are known to emit methane, but the magnitude of these emissions remains uncertain because most methane is released through ebullition (bubbling), which is spatially and temporally variable. Here we report a new method of measuring ebullition and use it to quantify methane emissions from two thaw lakes in North Siberia. We show that ebullition accounts for 95 per cent of methane emissions from these lakes, and that methane flux from thaw lakes in our study region may be five times higher than previously estimated. Extrapolation of these fluxes indicates that thaw lakes in North Siberia emit 3.8 teragrams of methane per year, which increases present estimates of methane emissions from northern wetlands (< 6-40 teragrams per year; refs 1, 2, 4-6) by between 10 and 63 per cent. We find that thawing permafrost along lake margins accounts for most of the methane released from the lakes, and estimate that an expansion of thaw lakes between 1974 and 2000, which was concurrent with regional warming, increased methane emissions in our study region by 58 per cent. Furthermore, the Pleistocene age (35,260-42,900 years) of methane emitted from hotspots along thawing lake margins indicates that this positive feedback to climate warming has led to the release of old carbon stocks previously stored in permafrost.

  9. Anaerobic oxidation of methane in grassland soils used for cattle husbandry

    NASA Astrophysics Data System (ADS)

    Bannert, A.; Bogen, C.; Esperschütz, J.; Koubová, A.; Buegger, F.; Fischer, D.; Radl, V.; Fuß, R.; Chroňáková, A.; Elhottová, D.; Šimek, M.; Schloter, M.

    2012-04-01

    While the importance of anaerobic methane oxidation has been reported for marine ecosystems, the role of this process in soils is still questionable. Grasslands used as pastures for cattle-overwintering show an increase in anaerobic soil micro-sites caused by animal treading and excrement deposition. Therefore anaerobic potential methane oxidation activity of severely impacted soil from a cattle winter pasture was investigated in an incubation experiment under anaerobic conditions using 13C-labeled methane. We were able to detect a high microbial activity utilizing CH4 as nutrient source shown by the respiration of 13CO2. Measurements of possible terminal electron acceptors for anaerobic oxidation of methane were carried out. Soil sulfate concentrations were too low to explain the oxidation of the amount of methane added, but enough nitrate and iron(III) were detected. However, only nitrate was consumed during the experiment. 13C-PLFA analyses clearly showed the utilization of CH4 as nutrient source mainly by organisms harbouring 16:1ω7 PLFAs. These lipids were found in Gram-negative microorganisms and anaerobes. The fact that these lipids are also typical for type I methanotrophs, known as aerobic methane oxidizers, might indicate a link between aerobic and anaerobic methane oxidation.

  10. Detecting Methane Leaks

    NASA Technical Reports Server (NTRS)

    Grant, W. B.; Hinkley, E. D.

    1984-01-01

    Remote sensor uses laser radiation backscattered from natural targets. He/Ne Laser System for remote scanning of Methane leaks employs topographic target to scatter light to receiver near laser transmitter. Apparatus powered by 1.5kW generator transported to field sites and pointed at suspected methane leaks. Used for remote detection of natural-gas leaks and locating methane emissions in landfill sites.

  11. Methane emissions from cattle.

    PubMed

    Johnson, K A; Johnson, D E

    1995-08-01

    Increasing atmospheric concentrations of methane have led scientists to examine its sources of origin. Ruminant livestock can produce 250 to 500 L of methane per day. This level of production results in estimates of the contribution by cattle to global warming that may occur in the next 50 to 100 yr to be a little less than 2%. Many factors influence methane emissions from cattle and include the following: level of feed intake, type of carbohydrate in the diet, feed processing, addition of lipids or ionophores to the diet, and alterations in the ruminal microflora. Manipulation of these factors can reduce methane emissions from cattle. Many techniques exist to quantify methane emissions from individual or groups of animals. Enclosure techniques are precise but require trained animals and may limit animal movement. Isotopic and nonisotopic tracer techniques may also be used effectively. Prediction equations based on fermentation balance or feed characteristics have been used to estimate methane production. These equations are useful, but the assumptions and conditions that must be met for each equation limit their ability to accurately predict methane production. Methane production from groups of animals can be measured by mass balance, micrometeorological, or tracer methods. These techniques can measure methane emissions from animals in either indoor or outdoor enclosures. Use of these techniques and knowledge of the factors that impact methane production can result in the development of mitigation strategies to reduce methane losses by cattle. Implementation of these strategies should result in enhanced animal productivity and decreased contributions by cattle to the atmospheric methane budget.

  12. Die aerobe Glykolyse der Tumorzelle

    NASA Astrophysics Data System (ADS)

    Schneider, Friedhelm

    1981-01-01

    A high aerobic glycolysis (aerobic lactate production) is the most significant feature of the energy metabolism of rapidly growing tumor cells. Several mechanisms, which may be different in different cell lines, seem to be involved in this characteristic of energy metabolism of the tumor cell. Changes in the cell membrane leading to increased uptake and utilization of glucose, a high level of fetal types of isoenzymes, a decreased number of mitochondria and a reduced capacity to metabolize pyruvate are some factors which must be taken into consideration. It is not possible to favour one of them at the present time.

  13. Metagenomics in methane seep detection and studies of the microbial methane sediment filter

    NASA Astrophysics Data System (ADS)

    Gunn Rike, Anne; Håvelsrud, Othilde Elise; Haverkamp, Thomas; Kristensen, Tom; Jakobsen, Kjetill

    2013-04-01

    Metanotrophic prokaryotes with their capacity to oxidize methane to biomass and CO2 contribute considerably in reduction of the global methane emission from oceans. Metagenomic studies of seabed sediments represent a new approach to detect marine methane seeps and to study whether the inhabiting microbial consortium represent a microbial methane filter. We have used next generation high throughput DNA sequencing technology to study microbial consortia and their potential metabolic processes in marine sediment samples from the Håkon Mosby mud volcano (HMMV) in the Barents Sea, the Tonya Seep in the Coal Oil Point area in California and from the pockmarked area at the Troll oil and gas field in the North Sea. Annotation of archaeal reads from the HMMV metagenome resulted in hits to all enzymes supposed to be involved in the anaerobic oxidation of methane (AOM) carried out by anaerobic methanotrophic archaea (ANME). The presence of several ANME taxa at HMMV has previously been well described (1). The stratification analysis of the Tonya seep sediment showed that both aerobic and anaerobic methanotrophs were present at both layers investigated, although total archaea, ANME-1, ANME-2 and ANME-3 were overabundant in the deepest layer. Several sulphate reducing taxa (possibly syntrophic ANME partners) were detected. The Tonya Seep sediment represent a robust methane filter where presently dominating methanotrophic taxa could be replaced by less abundant methanotrophs should the environmental conditions change (2). In the Troll pockmarked sediments several methanotrophic taxa including ANME-1, ANME-2 and candidate division NC10 were detected although there was an overabundance of autotrophic nitrifiers (e.g. Nitrosopumilis, Nitrococcus, Nitrospira) using CO2 as the carbon source. Methane migrating upwards through the sediments is probably oxidized to CO2 in AOM resulting in an upward CO2 flux. The CO2 entering the seafloor may contribute to maintain the pockmark structure

  14. Exhaled methane concentration profiles during exercise on an ergometer

    PubMed Central

    Szabó, A; Ruzsanyi, V; Unterkofler, K; Mohácsi, Á; Tuboly, E; Boros, M; Szabó, G; Hinterhuber, H; Amann, A

    2016-01-01

    Exhaled methane concentration measurements are extensively used in medical investigation of certain gastrointestinal conditions. However, the dynamics of endogenous methane release is largely unknown. Breath methane profiles during ergometer tests were measured by means of a photoacoustic spectroscopy based sensor. Five methane-producing volunteers (with exhaled methane level being at least 1 ppm higher than room air) were measured. The experimental protocol consisted of 5 min rest—15 min pedalling (at a workload of 75 W)—5 min rest. In addition, hemodynamic and respiratory parameters were determined and compared to the estimated alveolar methane concentration. The alveolar breath methane level decreased considerably, by a factor of 3–4 within 1.5 min, while the estimated ventilation-perfusion ratio increased by a factor of 2–3. Mean pre-exercise and exercise methane concentrations were 11.4 ppm (SD:7.3) and 2.8 ppm (SD:1.9), respectively. The changes can be described by the high sensitivity of exhaled methane to ventilationperfusion ratio and are in line with the Farhi equation. PMID:25749807

  15. Global Methane Biogeochemistry

    NASA Astrophysics Data System (ADS)

    Reeburgh, W. S.

    2003-12-01

    Methane (CH4) has been studied as an atmospheric constituent for over 200 years. A 1776 letter from Alessandro Volta to Father Campi described the first experiments on flammable "air" released by shallow sediments in Lake Maggiore (Wolfe, 1996; King, 1992). The first quantitative measurements of CH4, both involving combustion and gravimetric determination of trapped oxidation products, were reported in French by Boussingault and Boussingault, 1864 and Gautier (1901), who reported CH4 concentrations of 10 ppmv and 0.28 ppmv (seashore) and 95 ppmv (Paris), respectively. The first modern measurements of atmospheric CH4 were the infrared absorption measurements of Migeotte (1948), who estimated an atmospheric concentration of 2.0 ppmv. Development of gas chromatography and the flame ionization detector in the 1950s led to observations of vertical CH4 distributions in the troposphere and stratosphere, and to establishment of time-series sampling programs in the late 1970s. Results from these sampling programs led to suggestions that the concentration of CH4, as that of CO2, was increasing in the atmosphere. The possible role of CH4 as a greenhouse gas stimulated further research on CH4 sources and sinks. Methane has also been of interest to microbiologists, but findings from microbiology have entered the larger context of the global CH4 budget only recently.Methane is the most abundant hydrocarbon in the atmosphere. It plays important roles in atmospheric chemistry and the radiative balance of the Earth. Stratospheric oxidation of CH4 provides a means of introducing water vapor above the tropopause. Methane reacts with atomic chlorine in the stratosphere, forming HCl, a reservoir species for chlorine. Some 90% of the CH4 entering the atmosphere is oxidized through reactions initiated by the OH radical. These reactions are discussed in more detail by Wofsy (1976) and Cicerone and Oremland (1988), and are important in controlling the oxidation state of the atmosphere

  16. Methane Oxidation in Termite Hindguts: Absence of Evidence and Evidence of Absence▿

    PubMed Central

    Pester, Michael; Tholen, Anne; Friedrich, Michael W.; Brune, Andreas

    2007-01-01

    A steep oxygen gradient and the presence of methane render the hindgut internal periphery of termites a potential habitat for aerobic methane-oxidizing bacteria. However, methane emissions of various termites increased, if at all, only slightly when termites were exposed to an anoxic (nitrogen) atmosphere, and 14CH4 added to the air headspace over live termites was not converted to 14CO2. Evidence for the absence of methane oxidation in living termites was corroborated by the failure to detect pmoA, the marker gene for particulate methane monooxygenase, in hindgut DNA extracts of all termites investigated. This adds robustness to our concept of the degradation network in the termite hindgut and eliminates the gut itself as a potential sink of this important greenhouse gas. PMID:17261514

  17. The Transition from Aerobic to Anaerobic Metabolism.

    ERIC Educational Resources Information Center

    Skinner, James S.; McLellan, Thomas H.

    1980-01-01

    The transition from aerobic to anaerobic metabolism is discussed. More research is needed on different kinds of athletes and athletic activities and how they may affect aerobic and anaerobic metabolisms. (CJ)

  18. Effects of Environmental Conditions on an Urban Wetland's Methane Fluxes

    NASA Astrophysics Data System (ADS)

    Naor Azrieli, L.; Morin, T. H.; Bohrer, G.; Schafer, K. V.; Brooker, M.; Mitsch, W. J.

    2013-12-01

    Methane emissions from wetlands are the largest natural source of uncertainty in the global methane (CH4) budget. Wetlands are highly productive ecosystems with a large carbon sequestration potential. While wetlands are a net sink for carbon dioxide, they also release methane, a potent greenhouse gas. To effectively develop wetland management techniques, it is important to properly calculate the carbon budget of wetlands by understand the driving factors of methane fluxes. We constructed an eddy flux covariance system in the Olentangy River Wetland Research Park, a series of created and restored wetland in Columbus Ohio. Through the use of high frequency open path infrared gas analyzer (IRGA) sensors, we have continuously monitored the methane fluxes associated with the wetland since May 2011. To account for the heterogeneous landscape surrounding the tower, a footprint analysis was used to isolate data originating from within the wetland. Continuous measurements of the meteorological and environmental conditions at the wetlands coinciding with the flux measurements allow the interactions between methane fluxes and the climate and ecological forcing to be studied. The wintertime daily cycle of methane peaks around midday indicating a typical diurnal pattern in cold months. In the summer, the peak shifts to earlier in the day and also includes a daily peak occurring at approximately 10 AM. We believe this peak is associated with the onset of photosynthesis in Typha latifolia flushing methane from the plant's air filled tissue. Correlations with methane fluxes include latent heat flux, soil temperature, and incoming radiation. The connection to radiation may be further evidence of plant activity as a driver of methane fluxes. Higher methane fluxes corresponding with higher soil temperature indicates that warmer days stimulate the methanogenic consortium. Further analysis will focus on separating the methane fluxes into emissions from different terrain types within

  19. The future of methane

    SciTech Connect

    Howell, D.G.

    1995-12-31

    Natural gas, mainly methane, produces lower CO{sub 2}, CO, NO{sub x}, SO{sub 2} and particulate emissions than either oil or coal; thus further substitutions of methane for these fuels could help mitigate air pollution. Methane is, however, a potent greenhouse gas and the domestication of ruminants, cultivation of rice, mining of coal, drilling for oil, and transportation of natural gas have all contributed to a doubling of the amount of atmospheric methane since 1800. Today nearly 300,000 wells yearly produce ca. 21 trillion cubic feet of methane. Known reserves suggest about a 10 year supply at the above rates of recovery; and the potential for undiscovered resources is obscured by uncertainty involving price, new technologies, and environmental restrictions steming from the need to drill an enormous number of wells, many in ecologically sensitive areas. Until all these aspects of methane are better understood, its future role in the world`s energy mix will remain uncertain. The atomic simplicity of methane, composed of one carbon and four hydrogen atoms, may mask the complexity and importance of this, the most basic of organic molecules. Within the Earth, methane is produced through thermochemical alteration of organic materials, and by biochemical reactions mediated by metabolic processes of archaebacteria; some methane may even be primordial, a residue of planetary accretion. Methane also occurs in smaller volumes in landfills, rice paddies, termite complexes, ruminants, and even many humans. As an energy source, its full energy potential is controversial. Methane is touted by some as a viable bridge to future energy systems, fueled by the sun and uranium and carried by electricity and hydrogen.

  20. Membrane thickening aerobic digestion processes.

    PubMed

    Woo, Bryen

    2014-01-01

    Sludge management accounts for approximately 60% of the total wastewater treatment plant expenditure and laws for sludge disposal are becoming increasingly stringent, therefore much consideration is required when designing a solids handling process. A membrane thickening aerobic digestion process integrates a controlled aerobic digestion process with pre-thickening waste activated sludge using membrane technology. This process typically features an anoxic tank, an aerated membrane thickener operating in loop with a first-stage digester followed by second-stage digestion. Membrane thickening aerobic digestion processes can handle sludge from any liquid treatment process and is best for facilities obligated to meet low total phosphorus and nitrogen discharge limits. Membrane thickening aerobic digestion processes offer many advantages including: producing a reusable quality permeate with minimal levels of total phosphorus and nitrogen that can be recycled to the head works of a plant, protecting the performance of a biological nutrient removal liquid treatment process without requiring chemical addition, providing reliable thickening up to 4% solids concentration without the use of polymers or attention to decanting, increasing sludge storage capacities in existing tanks, minimizing the footprint of new tanks, reducing disposal costs, and providing Class B stabilization.

  1. Methanation assembly using multiple reactors

    DOEpatents

    Jahnke, Fred C.; Parab, Sanjay C.

    2007-07-24

    A methanation assembly for use with a water supply and a gas supply containing gas to be methanated in which a reactor assembly has a plurality of methanation reactors each for methanating gas input to the assembly and a gas delivery and cooling assembly adapted to deliver gas from the gas supply to each of said methanation reactors and to combine water from the water supply with the output of each methanation reactor being conveyed to a next methanation reactor and carry the mixture to such next methanation reactor.

  2. Arthritis and Aerobic Exercise: A Review.

    ERIC Educational Resources Information Center

    Ike, Robert W.; And Others

    1989-01-01

    Arthritic patients who regularly do aerobic exercise make significant gains in aerobic and functional status, and in subjective areas like pain tolerance and mood. Still, they are often advised to curtail physical activity. Guidelines are presented for physicians prescribing aerobic exercise. An exercise tolerance test is recommended. (SM)

  3. Sea-floor methane blow-out and global firestorm at the K-T boundary

    USGS Publications Warehouse

    Max, M.D.; Dillon, William P.; Nishimura, C.; Hurdle, B.G.

    1999-01-01

    A previously unsuspected source of fuel for the global firestorm recorded by soot in the Cretaceous-Tertiary impact layer may have resided in methane gas associated with gas hydrate in the end-Cretaceous seafloor. End-Cretaceous impact-generated shock and megawaves would have had the potential to initiate worldwide oceanic methane gas blow-outs from these deposits. The methane would likely have ignited and incompletely combusted. This large burst of methane would have been followed by longer-term methane release as a part of a positive thermal feedback in the disturbed ocean-atmosphere system.

  4. Methane Hydrates: More Than a Viable Aviation Fuel Feedstock Option

    NASA Technical Reports Server (NTRS)

    Hendricks, Robert C.

    2007-01-01

    Demand for hydrocarbon fuels is steadily increasing, and greenhouse gas emissions continue to rise unabated with the energy demand. Alternate fuels will be coming on line to meet that demand. This report examines the recovering of methane from methane hydrates for fuel to meet this demand rather than permitting its natural release into the environment, which will be detrimental to the planet. Some background on the nature, vast sizes, and stability of sedimentary and permafrost formations of hydrates are discussed. A few examples of the severe problems associated with methane recovery from these hydrates are presented along with the potential impact on the environment and coastal waters. Future availability of methane from hydrates may become an attractive option for aviation fueling, and so future aircraft design associated with methane fueling is considered.

  5. Revised methane emissions from the East Siberian Artic Shelf

    NASA Astrophysics Data System (ADS)

    Berchet, Antoine; Bousquet, Philippe; Pison, Isabelle; Locatelli, Robin; Chevallier, Frédéric; Paris, Jean-Daniel; Dlugokencky, Ed; Laurila, Tuomas; Viisanen, Yrjo; Worthy, Doug; Nisbet, Euan; Fischer, Rebecca; Lowry, David; France, James

    2015-04-01

    The Arctic Ocean Continental Shelf (ESAS) emits very uncertain amounts of methane into the atmosphere. Representing a great portion of the Arctic Ocean, with important sedimentation on the continental plateau from the Lena river, ESAS may contribute significantly to regional methane emissions into the atmosphere. Previous studies based on oceanographic campaigns estimated emissions from this area at 17 TgCH4.y-1. Here, comparing observations and regional simulations of atmospheric methane mixing ratios, methane emissions from ESAS are revised at 1.6±2.6 TgCH4.y-1 for the East Siberian Arctic Shelf, 6 to 10 times smaller than previously estimated. We also confirm the high variability and heterogeneity of the methane releases from this region.

  6. Geologic emissions of methane to the atmosphere.

    PubMed

    Etiope, Giuseppe; Klusman, Ronald W

    2002-12-01

    The atmospheric methane budget is commonly defined assuming that major sources derive from the biosphere (wetlands, rice paddies, animals, termites) and that fossil, radiocarbon-free CH4 emission is due to and mediated by anthropogenic activity (natural gas production and distribution, and coal mining). However, the amount of radiocarbon-free CH4 in the atmosphere, estimated at approximately 20% of atmospheric CH4, is higher than the estimates from statistical data of CH4 emission from fossil fuel related anthropogenic sources. This work documents that significant amounts of "old" methane, produced within the Earth crust, can be released naturally into the atmosphere through gas permeable faults and fractured rocks. Major geologic emissions of methane are related to hydrocarbon production in sedimentary basins (biogenic and thermogenic methane) and, subordinately, to inorganic reactions (Fischer-Tropsch type) in geothermal systems. Geologic CH4 emissions include diffuse fluxes over wide areas, or microseepage, on the order of 10(0)-10(2) mg m(-2) day(-1), and localised flows and gas vents, on the order of 10(2) t y(-1), both on land and on the seafloor. Mud volcanoes producing flows of up to 10(3) t y(-1) represent the largest visible expression of geologic methane emission. Several studies have indicated that methanotrophic consumption in soil may be insufficient to consume all leaking geologic CH4 and positive fluxes into the atmosphere can take place in dry or seasonally cold environments. Unsaturated soils have generally been considered a major sink for atmospheric methane, and never a continuous, intermittent, or localised source to the atmosphere. Although geologic CH4 sources need to be quantified more accurately, a preliminary global estimate indicates that there are likely more than enough sources to provide the amount of methane required to account for the suspected missing source of fossil CH4.

  7. Determination of endogenous methane formation by photoacoustic spectroscopy.

    PubMed

    Tuboly, E; Szabó, A; Erős, G; Mohácsi, A; Szabó, G; Tengölics, R; Rákhely, G; Boros, M

    2013-12-01

    Aerobic methane generation was demonstrated earlier in plants and eukaryotes under various stress conditions. Our aims were to develop a real-time and noninvasive detection system for monitoring the methane production of small animals and humans with our without exposure to various treatments. A near-infrared diode laser technique was employed with photoacoustic spectroscopy to monitor a methane-containing atmosphere online. The whole-body methane generation of anesthetized mice and rats was determined under baseline conditions and following reduction of the intestinal methanogenic flora or after lipopolysaccharide administration. Single-breath methane analyses were also carried out in a cross-sectional clinical study in order to obtain comparative human data. The whole-body methane production of mice was significantly decreased after antibiotic treatment (M: 1.71 ppm cm(-2) 10(3); p25: 1.5 ppm cm(-2) 10(3); p75: 2.11 ppm cm(-2) 10(3)) and increased significantly in endotoxemia (M: 4.53 ppm cm(-2) 10(3); p25: 4.37 ppm cm(-2) 10(3); p75: 5.38 ppm cm(-2) 10(3)), while no difference was observed between the rat groups. The methane content of the exhaled breath in humans was found to be between 0 and 37 ppm. Photoacoustic spectroscopy is a reliable tool with which to monitor the in vivo dynamics of stress-induced methane production in laboratory animals, even in a very low concentration range. PMID:24185326

  8. Methane drizzle on Titan.

    PubMed

    Tokano, Tetsuya; McKay, Christopher P; Neubauer, Fritz M; Atreya, Sushil K; Ferri, Francesca; Fulchignoni, Marcello; Niemann, Hasso B

    2006-07-27

    Saturn's moon Titan shows landscapes with fluvial features suggestive of hydrology based on liquid methane. Recent efforts in understanding Titan's methane hydrological cycle have focused on occasional cloud outbursts near the south pole or cloud streaks at southern mid-latitudes and the mechanisms of their formation. It is not known, however, if the clouds produce rain or if there are also non-convective clouds, as predicted by several models. Here we show that the in situ data on the methane concentration and temperature profile in Titan's troposphere point to the presence of layered optically thin stratiform clouds. The data indicate an upper methane ice cloud and a lower, barely visible, liquid methane-nitrogen cloud, with a gap in between. The lower, liquid, cloud produces drizzle that reaches the surface. These non-convective methane clouds are quasi-permanent features supported by the global atmospheric circulation, indicating that methane precipitation occurs wherever there is slow upward motion. This drizzle is a persistent component of Titan's methane hydrological cycle and, by wetting the surface on a global scale, plays an active role in the surface geology of Titan.

  9. Biotic systems to mitigate landfill methane emissions.

    PubMed

    Huber-Humer, Marion; Gebert, Julia; Hilger, Helene

    2008-02-01

    Landfill gases produced during biological degradation of buried organic wastes include methane, which when released to the atmosphere, can contribute to global climate change. Increasing use of gas collection systems has reduced the risk of escaping methane emissions entering the atmosphere, but gas capture is not 100% efficient, and further, there are still many instances when gas collection systems are not used. Biotic methane mitigation systems exploit the propensity of some naturally occurring bacteria to oxidize methane. By providing optimum conditions for microbial habitation and efficiently routing landfill gases to where they are cultivated, a number of bio-based systems, such as interim or long-term biocovers, passively or actively vented biofilters, biowindows and daily-used biotarps, have been developed that can alone, or with gas collection, mitigate landfill methane emissions. This paper reviews the science that guides bio-based designs; summarizes experiences with the diverse natural or engineered substrates used in such systems; describes some of the studies and field trials being used to evaluate them; and discusses how they can be used for better landfill operation, capping, and aftercare.

  10. Methane conversion process

    SciTech Connect

    Gaffney, A.M.; Jones, C.A.; Sofranko, J.A.

    1989-01-03

    This patent describes a process for the conversion of methane to higher hydrocarbons and coproduct water wherein methane is contacted at reactive conditions with a conversion catalyst comprised of a reducible metal oxide selected from the group consisting of an oxide of manganese, tin, indium, germanium, antimony, leads, bismuth, cerium, praseodymium, terbium, iron, and ruthenium. The improvement consists of: pretreating the catalyst before use in the conversion of methane to higher hydrocarbons and coproduct water with a reducing agent at 650/sup 0/C to 1200/sup 0/C for a time sufficient to improve the bulk density and attrition resistance of the catalyst and thereafter contacting the pretreated catalyst with methane at methane conversion conditions effective to form higher hydrocarbons and coproduct water.

  11. Methane storage capacity of the early martian cryosphere

    NASA Astrophysics Data System (ADS)

    Lasue, Jeremie; Quesnel, Yoann; Langlais, Benoit; Chassefière, Eric

    2015-11-01

    Methane is a key molecule to understand the habitability of Mars due to its possible biological origin and short atmospheric lifetime. Recent methane detections on Mars present a large variability that is probably due to relatively localized sources and sink processes yet unknown. In this study, we determine how much methane could have been abiotically produced by early Mars serpentinization processes that could also explain the observed martian remanent magnetic field. Under the assumption of a cold early Mars environment, a cryosphere could trap such methane as clathrates in stable form at depth. The extent and spatial distribution of these methane reservoirs have been calculated with respect to the magnetization distribution and other factors. We calculate that the maximum storage capacity of such a clathrate cryosphere is about 2.1 × 1019-2.2 × 1020 moles of CH4, which can explain sporadic releases of methane that have been observed on the surface of the planet during the past decade (∼1.2 × 109 moles). This amount of trapped methane is sufficient for similar sized releases to have happened yearly during the history of the planet. While the stability of such reservoirs depends on many factors that are poorly constrained, it is possible that they have remained trapped at depth until the present day. Due to the possible implications of methane detection for life and its influence on the atmospheric and climate processes on the planet, confirming the sporadic release of methane on Mars and the global distribution of its sources is one of the major goals of the current and next space missions to Mars.

  12. Factors influencing the stable carbon isotopic signature of methane from combustion and biomass burning

    NASA Astrophysics Data System (ADS)

    Chanton, Jeffrey P.; Rutkowski, Christine M.; Schwartz, Candace C.; Ward, Darold E.; Boring, Lindsay

    2000-01-01

    Factors controlling the δ13C of methane released by combustion include the combustion efficiency of the fire and the δ13C of the fuel. Smoldering fires produced 13C-depleted methane relative to hot, flaming fires in controlled forest and grassland burns and within a wood stove. Pine forest burns in the southeastern United States produced methane which ranged from -21 to -30‰, while African grassland burns varied from -17 to -26‰, depending upon combustion phase. African woodland burns produced methane at -30‰. In forest burns in the southeastern United States, the δ13C of methane released with smoldering was significantly 13C depleted relative to methane released under hot flaming conditions. Methane released with smoldering was depleted by 2-3‰ relative to the fuel δ13C, but this difference was not significant. The δ13C of methane produced in a variety of wood stove conditions varied from -9 to -25‰ and also depended upon combustion efficiency. Similar results were found for methane produced by gasoline automobile engines, where the δ13C of methane varied from -9 to -22‰. For combustion occurring within the confining chamber of a wood stove or engine the δ13C of methane was clearly 13C enriched relative to the δ13C of the fuel, possibly because of preferential combustion of 12CH4 in the gas phase. Significant quantities of ethylene (up to 25 to 50% of methane concentrations) were produced in southeastern U.S. forest fires, which may have consequences for physiological and reproductive responses of plants in the ecosystem. Methane production in these fires varied from 0.2 to 8.5% of the carbon dioxide production.

  13. Bacterial community composition and abundance in leachate of semi-aerobic and anaerobic landfills.

    PubMed

    Zhang, Wei; Yue, Bo; Wang, Qi; Huang, Zechun; Huang, Qifei; Zhang, Zengqiang

    2011-01-01

    The abundance and phylogenetic composition of bacterial community in leachate of semi-aerobic and anaerobic landfill were compared through real-time polymerase chain reaction and denaturing gradient gel electrophoresis. In semi-aerobic landfill scenario, the bacterial 16S rRNA copy numbers in leachate had no significant reduction from initial stage to stable period. In the scenario of anaerobic landfill, the largest bacterial 16S rRNA gene copy number was found in leachate at initial stage, but it reduced significantly at stable period. Moreover, methane-oxidizing bacteria population in stable period was lower than that in initial period in both two landfill processes. However, semi-aerobic landfill leachate had more methanotrophic bacteria populations than that in the anaerobic one. Furthermore, according to the sequences and phylogenetic analysis, obvious difference could be detected in bacterial community composition in different scenarios. Proteobacteria and bacteroidetes took up a dominantly higher proportion in semi-aerobic landfill leachate. To summarize up, different landfill methods and its landfill ages had crucial impacts on bacterial abundance and composition in leachate of semi-aerobic and anaerobic landfills.

  14. Acid-Tolerant Moderately Thermophilic Methanotrophs of the Class Gammaproteobacteria Isolated From Tropical Topsoil with Methane Seeps.

    PubMed

    Islam, Tajul; Torsvik, Vigdis; Larsen, Øivind; Bodrossy, Levente; Øvreås, Lise; Birkeland, Nils-Kåre

    2016-01-01

    Terrestrial tropical methane seep habitats are important ecosystems in the methane cycle. Methane oxidizing bacteria play a key role in these ecosystems as they reduce methane emissions to the atmosphere. Here, we describe the isolation and initial characterization of two novel moderately thermophilic and acid-tolerant obligate methanotrophs, assigned BFH1 and BFH2 recovered from a tropical methane seep topsoil habitat. The new isolates were strictly aerobic, non-motile, coccus-shaped and utilized methane and methanol as sole carbon and energy source. Isolates grew at pH range 4.2-7.5 (optimal 5.5-6.0) and at a temperature range of 30-60°C (optimal 51-55°C). 16S rRNA gene phylogeny placed them in a well-separated branch forming a cluster together with the genus Methylocaldum as the closest relatives (93.1-94.1% sequence similarity). The genes pmoA, mxaF, and cbbL were detected, but mmoX was absent. Strains BFH1 and BFH2 are, to our knowledge, the first isolated acid-tolerant moderately thermophilic methane oxidizers of the class Gammaproteobacteria. Each strain probably denotes a novel species and they most likely represent a novel genus within the family Methylococcaceae of type I methanotrophs. Furthermore, the isolates increase our knowledge of acid-tolerant aerobic methanotrophs and signify a previously unrecognized biological methane sink in tropical ecosystems. PMID:27379029

  15. Acid-Tolerant Moderately Thermophilic Methanotrophs of the Class Gammaproteobacteria Isolated From Tropical Topsoil with Methane Seeps

    PubMed Central

    Islam, Tajul; Torsvik, Vigdis; Larsen, Øivind; Bodrossy, Levente; Øvreås, Lise; Birkeland, Nils-Kåre

    2016-01-01

    Terrestrial tropical methane seep habitats are important ecosystems in the methane cycle. Methane oxidizing bacteria play a key role in these ecosystems as they reduce methane emissions to the atmosphere. Here, we describe the isolation and initial characterization of two novel moderately thermophilic and acid-tolerant obligate methanotrophs, assigned BFH1 and BFH2 recovered from a tropical methane seep topsoil habitat. The new isolates were strictly aerobic, non-motile, coccus-shaped and utilized methane and methanol as sole carbon and energy source. Isolates grew at pH range 4.2–7.5 (optimal 5.5–6.0) and at a temperature range of 30–60°C (optimal 51–55°C). 16S rRNA gene phylogeny placed them in a well-separated branch forming a cluster together with the genus Methylocaldum as the closest relatives (93.1–94.1% sequence similarity). The genes pmoA, mxaF, and cbbL were detected, but mmoX was absent. Strains BFH1 and BFH2 are, to our knowledge, the first isolated acid-tolerant moderately thermophilic methane oxidizers of the class Gammaproteobacteria. Each strain probably denotes a novel species and they most likely represent a novel genus within the family Methylococcaceae of type I methanotrophs. Furthermore, the isolates increase our knowledge of acid-tolerant aerobic methanotrophs and signify a previously unrecognized biological methane sink in tropical ecosystems. PMID:27379029

  16. Lidar for monitoring methane emission in Siberian permafrost

    NASA Astrophysics Data System (ADS)

    Grishkanich, A. S.; Zhevlakov, A. P.; Sidorov, I.; Elizarov, V. V.; Mak, A. A.; Kascheev, S. V.

    2016-03-01

    Identifying methane anomalies responsible for the temperature increase, by hiking trails in the Arctic requires great human labor .According to the tentative forecast by the year 2100 Arctic permafrost will greatly deteriorate, which will have numerous consequences. Indeed, release of less than 0.1% of the organic carbon stored in the upper 100-meter permafrost level (approximately 10000 ppm of carbon in the CH4 form) can double concentration of atmospheric methane, which is roughly 20 times more potent greenhouse gas than the CO2. Necessary to create a Raman lidar for monitoring of emissions of methane hydrate from the permafrost.

  17. Mechanism of methane transport from the rhizosphere to the atmosphere through rice plants

    SciTech Connect

    Nouchi, Isamu ); Mariko, Shigeru ); Aoki, Kazuyuki )

    1990-09-01

    To clarify the mechanisms of methane transport from the rhizosphere into the atmosphere through rice plants (Oryza sativa L.), the methane emission rate was measured from a shoot whose roots had been kept in a culture solution with a high methane concentration or exposed to methane gas in the gas phase by using a cylindrical chamber. No clear correlation was observed between change in the transpiration rate and that in the methane emission rate. Methane was mostly released from the culm, which is an aggregation of leaf sheaths, but not from the leaf blade. Micropores which are different from stomata were newly found at the abaxial epidermis of the leaf sheath by scanning electron microscopy. The measured methane emission rate was much higher than the calculated methane emission rate that would result from transpiration and the methane concentration in the culture solution. Rice roots absorb methane gas in the gas phase without water uptake. These results suggest that methane dissolved in the soil water surrounding the roots diffuses into the cell-wall water of the root cells, gasifies in the root cortex, and then is mostly released through the micropores in the leaf sheaths.

  18. Ultraviolet-radiation-induced methane emissions from meteorites and the Martian atmosphere.

    PubMed

    Keppler, Frank; Vigano, Ivan; McLeod, Andy; Ott, Ulrich; Früchtl, Marion; Röckmann, Thomas

    2012-06-01

    Almost a decade after methane was first reported in the atmosphere of Mars there is an intensive discussion about both the reliability of the observations--particularly the suggested seasonal and latitudinal variations--and the sources of methane on Mars. Given that the lifetime of methane in the Martian atmosphere is limited, a process on or below the planet's surface would need to be continuously producing methane. A biological source would provide support for the potential existence of life on Mars, whereas a chemical origin would imply that there are unexpected geological processes. Methane release from carbonaceous meteorites associated with ablation during atmospheric entry is considered negligible. Here we show that methane is produced in much larger quantities from the Murchison meteorite (a type CM2 carbonaceous chondrite) when exposed to ultraviolet radiation under conditions similar to those expected at the Martian surface. Meteorites containing several per cent of intact organic matter reach the Martian surface at high rates, and our experiments suggest that a significant fraction of the organic matter accessible to ultraviolet radiation is converted to methane. Ultraviolet-radiation-induced methane formation from meteorites could explain a substantial fraction of the most recently estimated atmospheric methane mixing ratios. Stable hydrogen isotope analysis unambiguously confirms that the methane released from Murchison is of extraterrestrial origin. The stable carbon isotope composition, in contrast, is similar to that of terrestrial microbial origin; hence, measurements of this signature in future Mars missions may not enable an unambiguous identification of biogenic methane.

  19. Ultraviolet-radiation-induced methane emissions from meteorites and the Martian atmosphere.

    PubMed

    Keppler, Frank; Vigano, Ivan; McLeod, Andy; Ott, Ulrich; Früchtl, Marion; Röckmann, Thomas

    2012-06-01

    Almost a decade after methane was first reported in the atmosphere of Mars there is an intensive discussion about both the reliability of the observations--particularly the suggested seasonal and latitudinal variations--and the sources of methane on Mars. Given that the lifetime of methane in the Martian atmosphere is limited, a process on or below the planet's surface would need to be continuously producing methane. A biological source would provide support for the potential existence of life on Mars, whereas a chemical origin would imply that there are unexpected geological processes. Methane release from carbonaceous meteorites associated with ablation during atmospheric entry is considered negligible. Here we show that methane is produced in much larger quantities from the Murchison meteorite (a type CM2 carbonaceous chondrite) when exposed to ultraviolet radiation under conditions similar to those expected at the Martian surface. Meteorites containing several per cent of intact organic matter reach the Martian surface at high rates, and our experiments suggest that a significant fraction of the organic matter accessible to ultraviolet radiation is converted to methane. Ultraviolet-radiation-induced methane formation from meteorites could explain a substantial fraction of the most recently estimated atmospheric methane mixing ratios. Stable hydrogen isotope analysis unambiguously confirms that the methane released from Murchison is of extraterrestrial origin. The stable carbon isotope composition, in contrast, is similar to that of terrestrial microbial origin; hence, measurements of this signature in future Mars missions may not enable an unambiguous identification of biogenic methane. PMID:22678286

  20. Characterization of methanotrophic bacterial populations in natural and agricultural aerobic soils of the European Russia

    NASA Astrophysics Data System (ADS)

    Kravchenko, Irina; Sukhacheva, Marina; Kizilova, Anna

    2014-05-01

    Atmospheric methane contributes to about 20% of the total radiative forcing by long-lived greenhouse gases, and microbial methane oxidation in upland soils is the only biological sink of methane. Microbial methane oxidation in aerated upland soils is estimated as 15 - 45 Tg yr-1 or 3-9% of the annual sink. Therefore there is need of extensive research to characterize methanotrophic activity in various ecosystems for possible application to reduce atmospheric methane fluxes and to minimize global climate change. The vast majority of known aerobic methanotrophs belongs to the Proteobacteria and placed in the families Methylococcaceae in the Gammaproteobacteria, and Methylocystaceae and Beijerinckiaceae in the Alphaproteobacteria. Known exceptions include the phylum Verrucomicrobia and uncultured methanotrophs such as Candidatus 'Methylomirabilis oxyfera' affiliated with the 'NC10' phylum. Plenty of studies of aerobic methane oxidation and key players of the process have been performed on various types of soils, and it was found that Methylocystis spp and uncultivated methanotrophs are abundant in upland soils. Two of the uncultured groups are upland soil cluster alphaproteobacteria (USCa) and gammaproteobacteria (USCg), as revealed by cultivation-independent surveys of pmoA diversity. Russia is extremely rich in soil types due to its vast territories, and most of these soils have never been investigated from the aspect of methanotrophy. This study addresses methane oxidation activity and diversity of aerobic methanotrophic bacteria in eight types of natural aerobic soils, four of which also had been under agricultural use. Methane fluxes have been measured by in situ static chamber method and methane oxidation rates in soil samples - by radioisotope tracer (14CH4) technique. Changes in methanotroph diversity and abundance were assessed by cloning and Sanger sequencing, and quantitative real-time PCR of pmoA genes. Methanotrophic population of unmanaged soils turned

  1. A model study of mechanisms of methane transfer from Arctic shelf to the atmosphere

    NASA Astrophysics Data System (ADS)

    Stepanenko, V. M.; Iakovlev, N. G.

    2012-04-01

    A possible positive feedback to rapid climate warming in Arctic - degradation of methane hydrates in the shelf bottom ground - has recently attracted attention of many research groups. This was primarily caused by new empirical evidence of very high concentrations of dissolved methane in Russian Arctic and methane fluxes to the atmosphere. A number of studies were conducted to access a possible effect of methane hydrates degradation in response to future warming of the ocean. Climate change scenarios were used to force the models of heat transfer in shelf ground. However, in majority of these works it was assumed that all methane released from shelf bottom reaches atmosphere. This precludes the possibility of taking into account methane bubbles dissolution, methane oxidation and subsequent ocean acidification effects. In this study we apply three modeling frameworks for quantifying these effects. First, one-dimensional (in vertical) model of water reservoir is used (Stepanenko et al. 2011), calculating vertical profiles of dissolved methane, bubbles' parameters and emission to the atmosphere. This model utilizes a bubble model by McGinnis et al. (2006), and diffusion-reaction equations for methane, oxygen and carbon dioxide concentrations in dissolved state. Thus, interaction between bubbles and dissolved gases and methane oxidation are described explicitly. Second, one-dimensional methane model is forced by temperature profile and eddy diffusion coefficients from 3D ocean dynamics model (Iakovlev 2009). And third, methane model is coupled to 3D ocean dynamics model allowing to reproduce advection of methane by oceanic currents in addition to above mentioned processes. This set of experiments allows to assess a significance of ocean dynamics for bottom-released methane transport and methane emission to the atmosphere. Since a number of parameters (e.g. initial bubble radius at the bottom, constants entering reaction rates formulae) are highly uncertain due to lack

  2. Methane Emission through Trees in Temperate and Tropical Wetlands

    NASA Astrophysics Data System (ADS)

    Pangala, S. R.; Gauci, V.; Hornibrook, E. R.; Gowing, D.

    2012-12-01

    Methane produced in wetland soil generally is thought to be emitted by a combination of three key processes: 1) diffusion through water-filled pores, 2) abrupt release of bubbles (ebullition), and 3) via internal spaces within the stems of herbaceous plants adapted to live in waterlogged soils. The capacity for trees to mediate methane emissions has received limited attention despite mesocosm studies of seedlings and saplings demonstrating that wetland trees have a significant capacity to transport soil-produced methane to the atmosphere. Notably ~60% of global wetlands are forested. We present in situ measurements of methane flux from a temperate carr (swamp) composed of alder (Alnus glutinosa) and birch (Betula pubescens) situated in the United Kingdom and a tropical forested peat swamp located in Borneo. The in situ data are complemented by a mesocosm experiment in which methane emissions were measured from alder saplings subjected to two water-regime treatments. In both the in situ and mesocosm studies, emissions from trees are compared to methane flux from the ground surface, the latter occurring via pore water diffusion, ebullition or via the aerenchyma of herbaceous plants. We show that tree stem emissions are controlled by a number of factors including tree species, soil pore-water concentration and stem lenticel density. Our results demonstrate that the omission of tree-mediated methane fluxes from measurement campaigns conducted in forested wetland can significantly underestimate the total ecosystem flux of methane.

  3. Martian Atmospheric Methane Plumes from Meteor Shower Infall: A Hypothesis

    NASA Technical Reports Server (NTRS)

    Fries, M.; Christou, A.; Archer, D.; Conrad, P.; Cooke, W.; Eigenbrode, J.; ten Kate, I. L.; Matney, M.; Niles, P.; Sykes, M.

    2016-01-01

    Methane plumes in the martian atmosphere have been detected using Earth-based spectroscopy, the Planetary Fourier Spectrometer on the ESA Mars Express mission, and the NASA Mars Science Laboratory. The methane's origin remains a mystery, with proposed sources including volcanism, exogenous sources like impacts and interplanetary dust, aqueous alteration of olivine in the presence of carbonaceous material, release from ancient deposits of methane clathrates, and/or biological activity. To date, none of these phenomena have been found to reliably correlate with the detection of methane plumes. An additional source exists, however: meteor showers could generate martian methane via UV pyrolysis of carbon-rich infall material. We find a correlation between the dates of Mars/cometary orbit encounters and detections of methane on Mars. We hypothesize that cometary debris falls onto Mars during these interactions, depositing freshly disaggregated meteor shower material in a regional concentration. The material generates methane via UV photolysis, resulting in a localized "plume" of short-lived methane.

  4. Anaerobic oxidation of methane: progress with an unknown process.

    PubMed

    Knittel, Katrin; Boetius, Antje

    2009-01-01

    Methane is the most abundant hydrocarbon in the atmosphere, and it is an important greenhouse gas, which has so far contributed an estimated 20% of postindustrial global warming. A great deal of biogeochemical research has focused on the causes and effects of the variation in global fluxes of methane throughout earth's history, but the underlying microbial processes and their key agents remain poorly understood. This is a disturbing knowledge gap because 85% of the annual global methane production and about 60% of its consumption are based on microbial processes. Only three key functional groups of microorganisms of limited diversity regulate the fluxes of methane on earth, namely the aerobic methanotrophic bacteria, the methanogenic archaea, and their close relatives, the anaerobic methanotrophic archaea (ANME). The ANME represent special lines of descent within the Euryarchaeota and appear to gain energy exclusively from the anaerobic oxidation of methane (AOM), with sulfate as the final electron acceptor according to the net reaction: CH(4) + SO(42-) ---> HCO(3-) + HS(-) + H(2)O. This review summarizes what is known and unknown about AOM on earth and its key catalysts, the ANME clades and their bacterial partners.

  5. Aerobic microbial enhanced oil recovery

    SciTech Connect

    Torsvik, T.; Gilje, E.; Sunde, E.

    1995-12-31

    In aerobic MEOR, the ability of oil-degrading bacteria to mobilize oil is used to increase oil recovery. In this process, oxygen and mineral nutrients are injected into the oil reservoir in order to stimulate growth of aerobic oil-degrading bacteria in the reservoir. Experiments carried out in a model sandstone with stock tank oil and bacteria isolated from offshore wells showed that residual oil saturation was lowered from 27% to 3%. The process was time dependent, not pore volume dependent. During MEOR flooding, the relative permeability of water was lowered. Oxygen and active bacteria were needed for the process to take place. Maximum efficiency was reached at low oxygen concentrations, approximately 1 mg O{sub 2}/liter.

  6. Methane emission by camelids.

    PubMed

    Dittmann, Marie T; Runge, Ullrich; Lang, Richard A; Moser, Dario; Galeffi, Cordula; Kreuzer, Michael; Clauss, Marcus

    2014-01-01

    Methane emissions from ruminant livestock have been intensively studied in order to reduce contribution to the greenhouse effect. Ruminants were found to produce more enteric methane than other mammalian herbivores. As camelids share some features of their digestive anatomy and physiology with ruminants, it has been proposed that they produce similar amounts of methane per unit of body mass. This is of special relevance for countrywide greenhouse gas budgets of countries that harbor large populations of camelids like Australia. However, hardly any quantitative methane emission measurements have been performed in camelids. In order to fill this gap, we carried out respiration chamber measurements with three camelid species (Vicugna pacos, Lama glama, Camelus bactrianus; n = 16 in total), all kept on a diet consisting of food produced from alfalfa only. The camelids produced less methane expressed on the basis of body mass (0.32±0.11 L kg⁻¹ d⁻¹) when compared to literature data on domestic ruminants fed on roughage diets (0.58±0.16 L kg⁻¹ d⁻¹). However, there was no significant difference between the two suborders when methane emission was expressed on the basis of digestible neutral detergent fiber intake (92.7±33.9 L kg⁻¹ in camelids vs. 86.2±12.1 L kg⁻¹ in ruminants). This implies that the pathways of methanogenesis forming part of the microbial digestion of fiber in the foregut are similar between the groups, and that the lower methane emission of camelids can be explained by their generally lower relative food intake. Our results suggest that the methane emission of Australia's feral camels corresponds only to 1 to 2% of the methane amount produced by the countries' domestic ruminants and that calculations of greenhouse gas budgets of countries with large camelid populations based on equations developed for ruminants are generally overestimating the actual levels.

  7. Methods to determine aerobic endurance.

    PubMed

    Bosquet, Laurent; Léger, Luc; Legros, Patrick

    2002-01-01

    Physiological testing of elite athletes requires the correct identification and assessment of sports-specific underlying factors. It is now recognised that performance in long-distance events is determined by maximal oxygen uptake (V(2 max)), energy cost of exercise and the maximal fractional utilisation of V(2 max) in any realised performance or as a corollary a set percentage of V(2 max) that could be endured as long as possible. This later ability is defined as endurance, and more precisely aerobic endurance, since V(2 max) sets the upper limit of aerobic pathway. It should be distinguished from endurance ability or endurance performance, which are synonymous with performance in long-distance events. The present review examines methods available in the literature to assess aerobic endurance. They are numerous and can be classified into two categories, namely direct and indirect methods. Direct methods bring together all indices that allow either a complete or a partial representation of the power-duration relationship, while indirect methods revolve around the determination of the so-called anaerobic threshold (AT). With regard to direct methods, performance in a series of tests provides a more complete and presumably more valid description of the power-duration relationship than performance in a single test, even if both approaches are well correlated with each other. However, the question remains open to determine which systems model should be employed among the several available in the literature, and how to use them in the prescription of training intensities. As for indirect methods, there is quantitative accumulation of data supporting the utilisation of the AT to assess aerobic endurance and to prescribe training intensities. However, it appears that: there is no unique intensity corresponding to the AT, since criteria available in the literature provide inconsistent results; and the non-invasive determination of the AT using ventilatory and heart rate

  8. Quantifying Methane Fluxes Simply and Accurately: The Tracer Dilution Method

    NASA Astrophysics Data System (ADS)

    Rella, Christopher; Crosson, Eric; Green, Roger; Hater, Gary; Dayton, Dave; Lafleur, Rick; Merrill, Ray; Tan, Sze; Thoma, Eben

    2010-05-01

    Methane is an important atmospheric constituent with a wide variety of sources, both natural and anthropogenic, including wetlands and other water bodies, permafrost, farms, landfills, and areas with significant petrochemical exploration, drilling, transport, or processing, or refining occurs. Despite its importance to the carbon cycle, its significant impact as a greenhouse gas, and its ubiquity in modern life as a source of energy, its sources and sinks in marine and terrestrial ecosystems are only poorly understood. This is largely because high quality, quantitative measurements of methane fluxes in these different environments have not been available, due both to the lack of robust field-deployable instrumentation as well as to the fact that most significant sources of methane extend over large areas (from 10's to 1,000,000's of square meters) and are heterogeneous emitters - i.e., the methane is not emitted evenly over the area in question. Quantifying the total methane emissions from such sources becomes a tremendous challenge, compounded by the fact that atmospheric transport from emission point to detection point can be highly variable. In this presentation we describe a robust, accurate, and easy-to-deploy technique called the tracer dilution method, in which a known gas (such as acetylene, nitrous oxide, or sulfur hexafluoride) is released in the same vicinity of the methane emissions. Measurements of methane and the tracer gas are then made downwind of the release point, in the so-called far-field, where the area of methane emissions cannot be distinguished from a point source (i.e., the two gas plumes are well-mixed). In this regime, the methane emissions are given by the ratio of the two measured concentrations, multiplied by the known tracer emission rate. The challenges associated with atmospheric variability and heterogeneous methane emissions are handled automatically by the transport and dispersion of the tracer. We present detailed methane flux

  9. Methane emissions from Carex rostrata

    NASA Astrophysics Data System (ADS)

    Yelverton, C. A.; Varner, R. K.; Roddy, S.; Noyce, G. L.

    2013-12-01

    Peatlands, especially in northern regions, are known for their contribution to the increase of methane (CH4) in the atmosphere. Methane emissions from peatlands are strongly correlated with water table, temperature, and species composition. Sedges, in particular, are a conduit for the release of CH4 directly to the atmosphere. This study examines the impact of clipping and sealing sedges (Carex rostrata) on CH4 emissions from a temperate peatland (Sallie's Fen, Barrington, NH, USA). Measurements of CH4 fluxes, dissolved CH4, and environmental conditions were made over a six-year period. Data from 2008 to 2013 show that the presence of Carex rostrata in this peatland increases CH4 emissions. Clipped plots have both lower seasonal and annual CH4 emissions, compared to control plots. By studying the type of environment associated with C. rostrata through measurements of water-table depth, pore water characteristics, and the peat, surface, and air temperature of each surrounding location, further studies will show how these factors affect the rate at which CH4 is emitted into the atmosphere.

  10. Methane oxidation and methanotrophs: resistance and resilience against model perturbations

    NASA Astrophysics Data System (ADS)

    Ho, A.; Frenzel, P.

    2009-04-01

    Biodiversity is claimed to be essential for ecosystem functioning. However, most experiments on biodiversity and ecosystem functioning (BEF) have been made on higher plants, while only few studies have dealt with microbial communities. Overall microbial diversity may be very high, and general functions like aerobic carbon mineralization are assumed to be supported by highly redundant communities. Therefore, we focused on methane oxidation, a microbial process of global importance mitigating methane emissions from wetland, rice fields, and landfills. We used a rice paddy as our model system, where >90% of potentially emitted methane may be oxidized in the oxic surface layer. This community is presumed to consist of 10-20 taxa more or less equivalent to species. We focused on the ability of methanotrophs to recover from a disturbance causing a significant die-off of all microbial populations. This was simulated by mixing native with sterile soil in two ratios (1:4 and 1:40). Microcosms were incubated and the temporal shift of the methanotrophic communities was followed by pmoA-based Terminal Restriction Length Polymorphism (T-RFLP), qPCR, and a pmoA-based diagnostic microarray. We consistently observed distinctive temporal shifts between Methylocystaceaea and Methylococcacea, a rapid population growth leading to the same or even higher cell numbers as in microcosms made from native soil alone, but no effect on the amount of methane oxidized. The ratio of different methanotrophs changed with treatment, while the number of taxa stayed nearly the same. Overall, methanotrophs showed a remarkable resilience compensating for die-offs. It has to be noted, however, that our experiment focused on methanotrophs adapted to and living at high methane fluxes. Quite different, methanotrophs living in upland soils do not mitigate methane emissions, but are the only biological sink to atmospheric methane. These microbes are severely substrate limited, and will be much more

  11. Methane-derived carbon flow through microbial communities in arctic lake sediments.

    PubMed

    He, Ruo; Wooller, Matthew J; Pohlman, John W; Tiedje, James M; Leigh, Mary Beth

    2015-09-01

    Aerobic methane (CH4 ) oxidation mitigates CH4 release and is a significant pathway for carbon and energy flow into aquatic food webs. Arctic lakes are responsible for an increasing proportion of global CH4 emissions, but CH4 assimilation into the aquatic food web in arctic lakes is poorly understood. Using stable isotope probing (SIP) based on phospholipid fatty acids (PLFA-SIP) and DNA (DNA-SIP), we tracked carbon flow quantitatively from CH4 into sediment microorganisms from an arctic lake with an active CH4 seepage. When 0.025 mmol CH4 g(-1) wet sediment was oxidized, approximately 15.8-32.8% of the CH4 -derived carbon had been incorporated into microorganisms. This CH4 -derived carbon equated to up to 5.7% of total primary production estimates for Alaskan arctic lakes. Type I methanotrophs, including Methylomonas, Methylobacter and unclassified Methylococcaceae, were most active at CH4 oxidation in this arctic lake. With increasing distance from the active CH4 seepage, a greater diversity of bacteria incorporated CH4 -derived carbon. Actinomycetes were the most quantitatively important microorganisms involved in secondary feeding on CH4 -derived carbon. These results showed that CH4 flows through methanotrophs into the broader microbial community and that type I methanotrophs, methylotrophs and actinomycetes are important organisms involved in using CH4 -derived carbon in arctic freshwater ecosystems.

  12. Methane heat transfer investigation

    NASA Technical Reports Server (NTRS)

    Cook, R. T.

    1984-01-01

    Future high chamber pressure LOX/hydrocarbon booster engines require copper-base alloy main combustion chamber coolant channels similar to the SSME to provide adequate cooling and resuable engine life. Therefore, it is of vital importance to evaluate the heat transfer characteristics and coking thresholds for LNG (94% methane) cooling, with a copper-base alloy material adjacent to the fuel coolant. High-pressure methane cooling and coking characteristics were recently evaluated using stainless-steel heated tubes at methane bulk temperatures and coolant wall temperatures typical of advanced engine operation except at lower heat fluxes as limited by the tube material. As expected, there was no coking observed. However, coking evaluations need be conducted with a copper-base surface exposed to the methane coolant at higher heat fluxes approaching those of future high chamber pressure engines.

  13. Methane heat transfer investigation

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Future high chamber pressure LOX/hydrocarbon booster engines require copper base alloy main combustion chamber coolant channels similar to the SSME to provide adequate cooling and reusable engine life. Therefore, it is of vital importance to evaluate the heat transfer characteristics and coking thresholds for LNG (94% methane) cooling, with a copper base alloy material adjacent to he fuel coolant. High pressure methane cooling and coking characteristics recently evaluated at Rocketdyne using stainless steel heated tubes at methane bulk temperatures and coolant wall temperatures typical of advanced engine operation except at lower heat fluxes as limited by the tube material. As expected, there was no coking observed. However, coking evaluations need be conducted with a copper base surface exposed to the methane coolant at higher heat fluxes approaching those of future high chamber pressure engines.

  14. Enzymatic Oxidation of Methane

    SciTech Connect

    Sirajuddin, S; Rosenzweig, AC

    2015-04-14

    Methane monooxygenases (MMOs) are enzymes that catalyze the oxidation of methane to methanol in methanotrophic bacteria. As potential targets for new gas-to-liquid methane bioconversion processes, MMOs have attracted intense attention in recent years. There are two distinct types of MMO, a soluble, cytoplasmic MMO (sMMO) and a membrane-bound, particulate MMO (pMMO). Both oxidize methane at metal centers within a complex, multisubunit scaffold, but the structures, active sites, and chemical mechanisms are completely different. This Current Topic review article focuses on the overall architectures, active site structures, substrate reactivities, proteinprotein interactions, and chemical mechanisms of both MMOs, with an emphasis on fundamental aspects. In addition, recent advances, including new details of interactions between the sMMO components, characterization of sMMO intermediates, and progress toward understanding the pMMO metal centers are highlighted. The work summarized here provides a guide for those interested in exploiting MMOs for biotechnological applications.

  15. Inventory of methane emissions from U.S. cattle

    NASA Astrophysics Data System (ADS)

    Westberg, H.; Lamb, B.; Johnson, K. A.; Huyler, M.

    2001-01-01

    Many countries, including the United States, are in the process of inventorying greenhouse gas emissions as a prerequisite for designing control strategies. We have developed a measurement-based inventory of methane emissions from cattle in the United States. Methane emission factors were established for the major livestock groups using an internal tracer method. The groups studied included cows, replacement heifers, slaughter cattle, calves, and bulls in the beef sector and cows plus replacement heifers in the dairy industry. Since methane emission is dependent on the quality and quantity of feed, diets were chosen that are representative of the feed regimes utilized by producers in the United States. Regional cattle populations, obtained from U.S. Department of Agriculture statistics, were combined with the methane emission factors to yield regional emission estimates. The methane totals from the five regions were then summed to give a U.S. inventory of cattle emissions for 1990, 1992, 1994, 1996, and 1998. Annual releases ranged from 6.50 Tg in 1990 to a high of 6.98 Tg in 1996. On a regional scale the North Central region of the United States had the largest methane emissions from livestock followed by the South Central and the West. The beef cow group released the most methane (˜2.5 Tg yr-1) followed by slaughter cattle (˜1.7 Tg yr-1) and dairy cows at about 1.5 Tg yr-1. Methane released by cattle in the United States contributes about 11% of the global cattle source.

  16. Electrochemical methane sensor

    DOEpatents

    Zaromb, S.; Otagawa, T.; Stetter, J.R.

    1984-08-27

    A method and instrument including an electrochemical cell for the detection and measurement of methane in a gas by the oxidation of methane electrochemically at a working electrode in a nonaqueous electrolyte at a voltage about 1.4 volts vs R.H.E. (the reversible hydrogen electrode potential in the same electrolyte), and the measurement of the electrical signal resulting from the electrochemical oxidation.

  17. Laser beam methane detector

    NASA Technical Reports Server (NTRS)

    Hinkley, E. D., Jr.

    1981-01-01

    Instrument uses infrared absorption to determine methane concentration in liquid natural gas vapor. Two sensors measure intensity of 3.39 mm laser beam after it passes through gas; absorption is proportional to concentration of methane. Instrument is used in modeling spread of LNG clouds and as leak detector on LNG carriers and installations. Unit includes wheels for mobility and is both vertically and horizontally operable.

  18. Methane oxidation and molecular characterization of methanotrophs from a former mercury mine impoundment

    USGS Publications Warehouse

    Baesman, Shaun; Miller, Laurence G.; Wei, Jeremy H.; Cho, Yirang; Matys, Emily D.; Summons, Roger E.; Welander, Paula V.; Oremland, Ronald S.

    2015-01-01

    The Herman Pit, once a mercury mine, is an impoundment located in an active geothermal area. Its acidic waters are permeated by hundreds of gas seeps. One seep was sampled and found to be composed of mostly CO2 with some CH4 present. The δ13CH4 value suggested a complex origin for the methane: i.e., a thermogenic component plus a biological methanogenic portion. The relatively 12C-enriched CO2 suggested a reworking of the ebullitive methane by methanotrophic bacteria. Therefore, we tested bottom sediments for their ability to consume methane by conducting aerobic incubations of slurried materials. Methane was removed from the headspace of live slurries, and subsequent additions of methane resulted in faster removal rates. This activity could be transferred to an artificial, acidic medium, indicating the presence of acidophilic or acid-tolerant methanotrophs, the latter reinforced by the observation of maximum activity at pH = 4.5 with incubated slurries. A successful extraction of sterol and hopanoid lipids characteristic of methanotrophs was achieved, and their abundances greatly increased with increased sediment methane consumption. DNA extracted from methane-oxidizing enrichment cultures was amplified and sequenced for pmoA genes that aligned with methanotrophic members of the Gammaproteobacteria. An enrichment culture was established that grew in an acidic (pH 4.5) medium via methane oxidation.

  19. Methane Oxidation and Molecular Characterization of Methanotrophs from a Former Mercury Mine Impoundment

    PubMed Central

    Baesman, Shaun M.; Miller, Laurence G.; Wei, Jeremy H.; Cho, Yirang; Matys, Emily D.; Summons, Roger E.; Welander, Paula V.; Oremland, Ronald S.

    2015-01-01

    The Herman Pit, once a mercury mine, is an impoundment located in an active geothermal area. Its acidic waters are permeated by hundreds of gas seeps. One seep was sampled and found to be composed of mostly CO2 with some CH4 present. The δ13CH4 value suggested a complex origin for the methane: i.e., a thermogenic component plus a biological methanogenic portion. The relatively 12C-enriched CO2 suggested a reworking of the ebullitive methane by methanotrophic bacteria. Therefore, we tested bottom sediments for their ability to consume methane by conducting aerobic incubations of slurried materials. Methane was removed from the headspace of live slurries, and subsequent additions of methane resulted in faster removal rates. This activity could be transferred to an artificial, acidic medium, indicating the presence of acidophilic or acid-tolerant methanotrophs, the latter reinforced by the observation of maximum activity at pH = 4.5 with incubated slurries. A successful extraction of sterol and hopanoid lipids characteristic of methanotrophs was achieved, and their abundances greatly increased with increased sediment methane consumption. DNA extracted from methane-oxidizing enrichment cultures was amplified and sequenced for pmoA genes that aligned with methanotrophic members of the Gammaproteobacteria. An enrichment culture was established that grew in an acidic (pH 4.5) medium via methane oxidation.

  20. Methane Oxidation and Molecular Characterization of Methanotrophs from a Former Mercury Mine Impoundment

    PubMed Central

    Baesman, Shaun M.; Miller, Laurence G.; Wei, Jeremy H.; Cho, Yirang; Matys, Emily D.; Summons, Roger E.; Welander, Paula V.; Oremland, Ronald S.

    2015-01-01

    The Herman Pit, once a mercury mine, is an impoundment located in an active geothermal area. Its acidic waters are permeated by hundreds of gas seeps. One seep was sampled and found to be composed of mostly CO2 with some CH4 present. The δ13CH4 value suggested a complex origin for the methane: i.e., a thermogenic component plus a biological methanogenic portion. The relatively 12C-enriched CO2 suggested a reworking of the ebullitive methane by methanotrophic bacteria. Therefore, we tested bottom sediments for their ability to consume methane by conducting aerobic incubations of slurried materials. Methane was removed from the headspace of live slurries, and subsequent additions of methane resulted in faster removal rates. This activity could be transferred to an artificial, acidic medium, indicating the presence of acidophilic or acid-tolerant methanotrophs, the latter reinforced by the observation of maximum activity at pH = 4.5 with incubated slurries. A successful extraction of sterol and hopanoid lipids characteristic of methanotrophs was achieved, and their abundances greatly increased with increased sediment methane consumption. DNA extracted from methane-oxidizing enrichment cultures was amplified and sequenced for pmoA genes that aligned with methanotrophic members of the Gammaproteobacteria. An enrichment culture was established that grew in an acidic (pH 4.5) medium via methane oxidation. PMID:27682090

  1. Timescales of methane seepage on the Norwegian margin following collapse of the Scandinavian Ice Sheet.

    PubMed

    Crémière, Antoine; Lepland, Aivo; Chand, Shyam; Sahy, Diana; Condon, Daniel J; Noble, Stephen R; Martma, Tõnu; Thorsnes, Terje; Sauer, Simone; Brunstad, Harald

    2016-01-01

    Gas hydrates stored on continental shelves are susceptible to dissociation triggered by environmental changes. Knowledge of the timescales of gas hydrate dissociation and subsequent methane release are critical in understanding the impact of marine gas hydrates on the ocean-atmosphere system. Here we report a methane efflux chronology from five sites, at depths of 220-400 m, in the southwest Barents and Norwegian seas where grounded ice sheets led to thickening of the gas hydrate stability zone during the last glaciation. The onset of methane release was coincident with deglaciation-induced pressure release and thinning of the hydrate stability zone. Methane efflux continued for 7-10 kyr, tracking hydrate stability changes controlled by relative sea-level rise, bottom water warming and fluid pathway evolution in response to changing stress fields. The protracted nature of seafloor methane emissions probably attenuated the impact of hydrate dissociation on the climate system. PMID:27167635

  2. Timescales of methane seepage on the Norwegian margin following collapse of the Scandinavian Ice Sheet.

    PubMed

    Crémière, Antoine; Lepland, Aivo; Chand, Shyam; Sahy, Diana; Condon, Daniel J; Noble, Stephen R; Martma, Tõnu; Thorsnes, Terje; Sauer, Simone; Brunstad, Harald

    2016-05-11

    Gas hydrates stored on continental shelves are susceptible to dissociation triggered by environmental changes. Knowledge of the timescales of gas hydrate dissociation and subsequent methane release are critical in understanding the impact of marine gas hydrates on the ocean-atmosphere system. Here we report a methane efflux chronology from five sites, at depths of 220-400 m, in the southwest Barents and Norwegian seas where grounded ice sheets led to thickening of the gas hydrate stability zone during the last glaciation. The onset of methane release was coincident with deglaciation-induced pressure release and thinning of the hydrate stability zone. Methane efflux continued for 7-10 kyr, tracking hydrate stability changes controlled by relative sea-level rise, bottom water warming and fluid pathway evolution in response to changing stress fields. The protracted nature of seafloor methane emissions probably attenuated the impact of hydrate dissociation on the climate system.

  3. Timescales of methane seepage on the Norwegian margin following collapse of the Scandinavian Ice Sheet

    PubMed Central

    Crémière, Antoine; Lepland, Aivo; Chand, Shyam; Sahy, Diana; Condon, Daniel J.; Noble, Stephen R.; Martma, Tõnu; Thorsnes, Terje; Sauer, Simone; Brunstad, Harald

    2016-01-01

    Gas hydrates stored on continental shelves are susceptible to dissociation triggered by environmental changes. Knowledge of the timescales of gas hydrate dissociation and subsequent methane release are critical in understanding the impact of marine gas hydrates on the ocean–atmosphere system. Here we report a methane efflux chronology from five sites, at depths of 220–400 m, in the southwest Barents and Norwegian seas where grounded ice sheets led to thickening of the gas hydrate stability zone during the last glaciation. The onset of methane release was coincident with deglaciation-induced pressure release and thinning of the hydrate stability zone. Methane efflux continued for 7–10 kyr, tracking hydrate stability changes controlled by relative sea-level rise, bottom water warming and fluid pathway evolution in response to changing stress fields. The protracted nature of seafloor methane emissions probably attenuated the impact of hydrate dissociation on the climate system. PMID:27167635

  4. Timescales of methane seepage on the Norwegian margin following collapse of the Scandinavian Ice Sheet

    NASA Astrophysics Data System (ADS)

    Crémière, Antoine; Lepland, Aivo; Chand, Shyam; Sahy, Diana; Condon, Daniel J.; Noble, Stephen R.; Martma, Tõnu; Thorsnes, Terje; Sauer, Simone; Brunstad, Harald

    2016-05-01

    Gas hydrates stored on continental shelves are susceptible to dissociation triggered by environmental changes. Knowledge of the timescales of gas hydrate dissociation and subsequent methane release are critical in understanding the impact of marine gas hydrates on the ocean-atmosphere system. Here we report a methane efflux chronology from five sites, at depths of 220-400 m, in the southwest Barents and Norwegian seas where grounded ice sheets led to thickening of the gas hydrate stability zone during the last glaciation. The onset of methane release was coincident with deglaciation-induced pressure release and thinning of the hydrate stability zone. Methane efflux continued for 7-10 kyr, tracking hydrate stability changes controlled by relative sea-level rise, bottom water warming and fluid pathway evolution in response to changing stress fields. The protracted nature of seafloor methane emissions probably attenuated the impact of hydrate dissociation on the climate system.

  5. Conversion of methane to higher hydrocarbons (Biomimetic catalysis of the conversion of methane to methanol). Final report

    SciTech Connect

    Watkins, B.E.; Taylor, R.T.; Satcher, J.H.

    1993-09-01

    In addition to inorganic catalysts that react with methane, it is well-known that a select group of aerobic soil/water bacteria called methanotrophs can efficiently and selectively utilize methane as the sole source of their energy and carbon for cellular growth. The first reaction in this metabolic pathway is catalyzed by the enzyme methane monooxygenase (MMO) forming methanol. Methanol is a technology important product from this partial oxidation of methane since it can be easily converted to liquid hydrocarbon transportation fuels (gasoline), used directly as a liquid fuel or fuel additive itself, or serve as a feedstock for chemicals production. This naturally occurring biocatalyst (MMO) is accomplishing a technologically important transformation (methane directly to methanol) for which there is currently no analogous chemical (non-biological) process. The authors approach has been to use the biocatalyst, MMO, as the initial focus in the development of discrete chemical catalysts (biomimetic complexes) for methane conversion. The advantage of this approach is that it exploits a biocatalytic system already performing a desired transformation of methane. In addition, this approach generated needed new experimental information on catalyst structure and function in order to develop new catalysts rationally and systematically. The first task is a comparative mechanistic, biochemical, and spectroscopic investigation of MMO enzyme systems. This work was directed at developing a description of the structure and function of the catalytically active sites in sufficient detail to generate a biomimetic material. The second task involves the synthesis, characterization, and chemical reactions of discrete complexes that mimic the enzymatic active site. These complexes were synthesized based on their best current understanding of the MMO active site structure.

  6. Methane seepage and gas hydrates: The need for multidisciplinary and long-term methane flux studies

    NASA Astrophysics Data System (ADS)

    Greinert, J.

    2012-12-01

    Methane seepage and gas hydrates started to receive more interest in the marine science community in the early 80s; exploratory studies followed, which were often hampered by the limited technical capabilities when compared to modern technologies that are available today (e.g. ROVs, high resolution 3D seismic, pressurized coring). General research topics have changed from curiosity-driven 'what is out there' towards gaining a detailed understanding of microbial processes in the sediment and geophysical quantifications of gas hydrates in their different locations around the world. Environmental questions fueled by the 'clathrate gun hypothesis' and the possible future impact of decomposing gas hydrates on atmospheric methane concentrations became research topics for a number of scientists, whereas others are researching gas hydrates and its potential use as an energy resource coupled with CO2-sequestering. Today the general phenomenon of gas hydrate related seepage and the biogeochemical processes involved are well understood. Large uncertainties still exist with regard to large-scale methane flux extrapolations from the seafloor through the water column and into the atmosphere, mainly due to lack of multidisciplinary and long-term observations . Studying the temporal variability of fluid and bubble release from the seafloor in high spatial and temporal resolution still does not do away with the problem of how to extrapolate such local flux measurements, considering tidal, seasonal changes, let alone changes on a longer time scale (glacial/interglacial). Examples provided from studies in the Pacific, the Black Sea and North Sea as well as from offshore Svalbard will highlight the temporal variability of bubble release, the impact of environmental parameters on this release and biogeochemical processes related to methane oxidation and production in the water column. Although the assumption is true that bubble release from deeper than 100m water depth will not

  7. Effects of increasing temperatures on methane concentrations and methanogenesis during experimental incubation of sediments from oligotrophic and mesotrophic lakes

    NASA Astrophysics Data System (ADS)

    Fuchs, Andrea; Lyautey, Emilie; Montuelle, Bernard; Casper, Peter

    2016-05-01

    Global warming is expected to raise temperatures in freshwater lakes, which have been acknowledged to contribute up to 10% of the atmospheric methane concentrations. Increasing temperature enhances methane production and oxidation rates, but few studies have considered the balance between both processes at experimentally higher temperatures within lake sediments. The temperature dependence of methane concentrations, methane production rates, and methanogenic (mcrA) and methanotrophic (pmoA) community size was investigated in intact sediment cores incubated with aerobic hypolimnion water at 4, 8, and 12°C over 3 weeks. Sediment cores of 25 cm length were collected at two temperate lakes—Lake Stechlin (Germany; mesotrophic-oligotrophic, maximum depth 69.5 m) and Lake Geneva (France/Switzerland; mesotrophic, maximum depth 310 m). While methane production rates in Lake Stechlin sediments did not change with increasing temperatures, methane concentrations decreased significantly. In contrast, methane production rates increased in 20-25 cm in Lake Geneva sediments with increasing temperatures, but methane concentrations did not differ. Real-time PCR demonstrated the methanogenic and methanotrophic community size remained stable independently of the incubation temperature. Methane concentrations as well as community sizes were 1-2 orders of magnitude higher in Lake Stechlin than in Lake Geneva, while potential methane production rates after 24 h were similar in both lakes, with on average 2.5 and 1.9 nmol g-1 DW h-1, respectively. Our results suggest that at higher temperatures methane oxidation could balance, and even exceed, methane production. This suggests that anaerobic methane oxidation could be involved in the methane balance at a more important rate than previously anticipated.

  8. Aerobic granular processes: Current research trends.

    PubMed

    Zhang, Quanguo; Hu, Jianjun; Lee, Duu-Jong

    2016-06-01

    Aerobic granules are large biological aggregates with compact interiors that can be used in efficient wastewater treatment. This mini-review presents new researches on the development of aerobic granular processes, extended treatments for complicated pollutants, granulation mechanisms and enhancements of granule stability in long-term operation or storage, and the reuse of waste biomass as renewable resources. A discussion on the challenges of, and prospects for, the commercialization of aerobic granular process is provided. PMID:26873285

  9. Performance evaluation of an anaerobic/aerobic landfill-based digester using yard waste for energy and compost production.

    PubMed

    Yazdani, Ramin; Barlaz, Morton A; Augenstein, Don; Kayhanian, Masoud; Tchobanoglous, George

    2012-05-01

    The objective of this study was to evaluate a new alternative for yard waste management by constructing, operating and monitoring a landfill-based two-stage batch digester (anaerobic/aerobic) with the recovery of energy and compost. The system was initially operated under anaerobic conditions for 366 days, after which the yard waste was aerated for an additional 191 days. Off gas generated from the aerobic stage was treated by biofilters. Net energy recovery was 84.3MWh, or 46kWh per million metric tons of wet waste (as received), and the biochemical methane potential of the treated waste decreased by 83% during the two-stage operation. The average removal efficiencies of volatile organic compounds and non-methane organic compounds in the biofilters were 96-99% and 68-99%, respectively.

  10. Performance evaluation of an anaerobic/aerobic landfill-based digester using yard waste for energy and compost production.

    PubMed

    Yazdani, Ramin; Barlaz, Morton A; Augenstein, Don; Kayhanian, Masoud; Tchobanoglous, George

    2012-05-01

    The objective of this study was to evaluate a new alternative for yard waste management by constructing, operating and monitoring a landfill-based two-stage batch digester (anaerobic/aerobic) with the recovery of energy and compost. The system was initially operated under anaerobic conditions for 366 days, after which the yard waste was aerated for an additional 191 days. Off gas generated from the aerobic stage was treated by biofilters. Net energy recovery was 84.3MWh, or 46kWh per million metric tons of wet waste (as received), and the biochemical methane potential of the treated waste decreased by 83% during the two-stage operation. The average removal efficiencies of volatile organic compounds and non-methane organic compounds in the biofilters were 96-99% and 68-99%, respectively. PMID:22317795

  11. Hypotheses for Near-Surface Exchange of Methane on Mars

    NASA Astrophysics Data System (ADS)

    Hu, Renyu; Bloom, A. Anthony; Gao, Peter; Miller, Charles E.; Yung, Yuk L.

    2016-07-01

    The Curiosity rover recently detected a background of 0.7 ppb and spikes of 7 ppb of methane on Mars. This in situ measurement reorients our understanding of the martian environment and its potential for life, as the current theories do not entail any geological source or sink of methane that varies sub-annually. In particular, the 10-fold elevation during the southern winter indicates episodic sources of methane that are yet to be discovered. Here we suggest a near-surface reservoir could explain this variability. Using the temperature and humidity measurements from the rover, we find that perchlorate salts in the regolith deliquesce to form liquid solutions, and deliquescence progresses to deeper subsurface in the season of the methane spikes. We therefore formulate the following three testable hypotheses. The first scenario is that the regolith in Gale Crater adsorbs methane when dry and releases this methane to the atmosphere upon deliquescence. The adsorption energy needs to be 36 kJ mol-1 to explain the magnitude of the methane spikes, higher than existing laboratory measurements. The second scenario is that microorganisms convert organic matter in the soil to methane when they are in liquid solutions. This scenario does not require regolith adsorption but entails extant life on Mars. The third scenario is that deep subsurface aquifers produce the bursts of methane. Continued in situ measurements of methane and water, as well as laboratory studies of adsorption and deliquescence, will test these hypotheses and inform the existence of the near-surface reservoir and its exchange with the atmosphere.

  12. Draft Genome Sequence of Methyloferula stellata AR4, an Obligate Methanotroph Possessing Only a Soluble Methane Monooxygenase.

    PubMed

    Dedysh, Svetlana N; Naumoff, Daniil G; Vorobev, Alexey V; Kyrpides, Nikos; Woyke, Tanja; Shapiro, Nicole; Crombie, Andrew T; Murrell, J Colin; Kalyuzhnaya, Marina G; Smirnova, Angela V; Dunfield, Peter F

    2015-01-01

    Methyloferula stellata AR4 is an aerobic acidophilic methanotroph, which, in contrast to most known methanotrophs but similar to Methylocella spp., possesses only a soluble methane monooxygenase. However, it differs from Methylocella spp. by its inability to grow on multicarbon substrates. Here, we report the draft genome sequence of this bacterium. PMID:25745010

  13. Lower limb loading in step aerobic dance.

    PubMed

    Wu, H-W; Hsieh, H-M; Chang, Y-W; Wang, L-H

    2012-11-01

    Participation in aerobic dance is associated with a number of lower extremity injuries, and abnormal joint loading seems to be a factor in these. However, information on joint loading is limited. The purpose of this study was to investigate the kinetics of the lower extremity in step aerobic dance and to compare the differences of high-impact and low-impact step aerobic dance in 4 aerobic movements (mambo, kick, L step and leg curl). 18 subjects were recruited for this study. High-impact aerobic dance requires a significantly greater range of motion, joint force and joint moment than low-impact step aerobic dance. The peak joint forces and moments in high-impact step aerobic dance were found to be 1.4 times higher than in low-impact step aerobic dance. Understanding the nature of joint loading may help choreographers develop dance combinations that are less injury-prone. Furthermore, increased knowledge about joint loading may be helpful in lowering the risk of injuries in aerobic dance instructors and students.

  14. Methane Emissions from Upland Forests

    NASA Astrophysics Data System (ADS)

    Megonigal, Patrick; Pitz, Scott; Wang, Zhi-Ping

    2016-04-01

    Global budgets ascribe 4-10% of atmospheric methane sinks to upland soils and assume that soils are the sole surface for methane exchange between upland forests and the atmosphere. The dogma that upland forests are uniformly atmospheric methane sinks was challenged a decade ago by the discovery of abiotic methane production from plant tissue. Subsequently a variety of relatively cryptic microbial and non-microbial methane sources have been proposed that have the potential to emit methane in upland forests. Despite the accumulating evidence of potential methane sources, there are few data demonstrating actual emissions of methane from a plant surface in an upland forest. We report direct observations of methane emissions from upland tree stems in two temperate forests. Stem methane emissions were observed from several tree species that dominate a forest located on the mid-Atlantic coast of North America (Maryland, USA). Stem emissions occurred throughout the growing season while soils adjacent to the trees simultaneously consumed methane. Scaling fluxes by stem surface area suggested the forest was a net methane source during a wet period in June, and that stem emissions offset 5% of the soil methane sink on an annual basis. High frequency measurements revealed diurnal cycles in stem methane emission rates, pointing to soils as the methane source and transpiration as the most likely pathway for gas transport. Similar observations were made in an upland forest in Beijing, China. However, in this case the evidence suggested the methane was not produced in soils, but in the heartwood by microbial or non-microbial processes. These data challenge the concept that forests are uniform sinks of methane, and suggest that upland forests are smaller methane sinks than previously estimated due to stem emissions. Tree emissions may be particularly important in upland tropical forests characterized by high rainfall and transpiration.

  15. Methane Gas Emissions - is Older Infrastructure Leakier?

    NASA Astrophysics Data System (ADS)

    Wendt, L. P.; Caulton, D.; Zondlo, M. A.; Lane, H.; Lu, J.; Golston, L.; Pan, D.

    2015-12-01

    Large gains in natural gas production from hydraulic fracturing is reinvigorating the US energy economy. It is a clean burning fuel with lower emissions than that of coal or oil. Studies show that methane (CH4) leaks from natural gas infrastructure vary widely. A broader question is whether leak rates of methane might offset the benefits of combustion of natural gas. Excess methane (CH4) is a major greenhouse gas with a radiative forcing constant of 25 times that of CO2 when projected over a 100-year period. An extensive field study of 250 wells in the Marcellus Shale conducted in July 2015 examined the emission rates of this region and identifed super-emitters. Spud production data will provide information as to whether older infrastructure is responsible for more of the emissions. Quantifying the emission rate was determined by extrapolating methane releases at a distance from private well pads using an inverse Gaussian plume model. Wells studied were selected by prevailing winds, distance from public roads, and topographical information using commercial (ARCGIS and Google Earth), non-profit (drillinginfo), and government (State of PA) databases. Data were collected from the mobile sensing lab (CH4, CO2 and H2O sensors), as well as from a stationary tower. Emission rates from well pads will be compared to their original production (spud dates) to evaluate whether infrastructure age and total production correlates with the observed leak rates. Very preliminary results show no statistical correlation between well pad production rates and observed leak rates.

  16. Arctic Methane Hydrates: A Potential Greenhouse Gas Hazard

    NASA Astrophysics Data System (ADS)

    Light, M. P. R.; Solana, C.

    Methane is one of the most important greenhouse gases present in the atmosphere, having 20 times more warming potential than CO2 over a 100 yr period and 56 times more over a 20 yr period. The submarine arctic ice contains abundant methane trapped as hydrates below the continental shelf and its edge. The reserves in this area are estimated at more than 140 times the volume of methane in the atmosphere and, if released relatively quickly, the effects could be catastrophic. Although some authors have established that submarine hydrates will remain stable for the next 1000 yr, this estimation could change if other phenomena are taken into account. Hydrates within the continental shelf in the Arctic are more unstable because of the increase in oceanic temperatures over the last 10,000 yr. A warm (2C maximum) intermediate depth (5- 500 m) current recently detected in the Arctic basin flowing along the shelf edge will further destabilize the methane hydrates exposed there. In addition, the presence of seismic activity along the Arctic mid-ocean ridge and in the northern Alaska region, with magnitudes greater than 3.5 Richter and epicentres less than 30 km deep, could trigger slope failures where the methane hydrate is unstable, releasing huge volumes of methane into the atmosphere. Therefore, identifying those areas that are potentially unstable under these new conditions and the possibilities of reducing the hazard are a priority in our research.

  17. Assessing Enhanced Anaerobic and Intrinsic Aerobic Biodegradation of Trichloroethene

    NASA Astrophysics Data System (ADS)

    Sorenson, K. S.; Ely, R. L.; Martin, J. P.; Alvarez-Cohen, L.; Kauffman, M. E.

    2001-12-01

    Biodegradation of chloroethenes can proceed either anaerobically or aerobically; however, the techniques for monitoring the two pathways are quite different. At the Idaho National Engineering and Environmental Laboratory's Test Area North (TAN, a combination of anaerobic and aerobic biodegradation of trichloroethene (TCE) is being employed for restoration of a large plume of contaminated groundwater. During stimulation of anaerobic biodegradation of TCE through lactate addition, several assessment tools have proven effective for various objectives. Monitoring TCE and its lesser chlorinated degradation products provides a straightforward assessment tool for the occurrence of degradation. It does not, however, provide information regarding the potential for reductive dechlorination, nor progress from less suitable to more suitable conditions. A technique for obtaining this information is monitoring redox-sensitive geochemical parameters such as dissolved iron, sulfate, methane, and oxidation-reduction potential. This approach was demonstrated by the strong correlation of steps in the reductive dechlorination pathway to redox conditions at the TAN site. Yet another tool is required to determine adequacy of conditions for efficient dechlorination. Dechlorination efficiency appears to be dependent upon the predominant electron donor utilization (or fermentation) process occurring at any given time, an observation consistent with thermodynamic considerations. Thus, monitoring of added electron donor and intermediate product concentrations can help determine an efficient operations strategy. One final tool demonstrated at the TAN site was monitoring stable carbon isotope ratios. As TCE was dechlorinated, a clear fractionation occurred from cis-dichloroethene to vinyl chloride, and from vinyl chloride to ethene. This fractionation provides a clear signature of reductive dechlorination. Assessment of aerobic biodegradation of chloroethenes at TAN is more challenging because

  18. Methane concentrations and oxidation in nearshore waters of the Lena River Delta

    NASA Astrophysics Data System (ADS)

    Joye, S. B.; Samarkin, V.; Shakhova, N. E.; Semiletov, I. P.

    2014-12-01

    The Arctic is warming dramatically, with potentially catastrophic impacts on climate change through rapid mobilization of labile carbon reservoirs sequestered presently in permafrost. Increasingly, Arctic feedbacks are recognized as key contributors to climate change, including cycles associated with the powerful greenhouse gas methane, whose atmospheric concentration has more than doubled since the pre-industrial epoch. Sustained methane release to the atmosphere from thawing Arctic permafrost and delivery to the coastal ocean through groundwater or riverine discharge or expulsion from the seabed is a positive and likely highly significant feedback to climate warming. Microbially-mediated methane oxidation provides a key sink and effective biofilter that can limit methane fluxes from coastal environments to the atmosphere. We examined methane dynamics on the East Siberian Arctic Shelf by determining concentrations and oxidation rates at a series of stations near the Lena River Delta and moving offshore. Methane concentrations and oxidation rates were highly elevated in and near the river mouth compared to offshore waters, except when the offshore waters were impacted by seabed methane seepage. The regulation of methane oxidation in Arctic waters appears two-fold: first, rates are strongly related to methane availability and second, in the presence of methane, nutrient availability strongly regulates methane consumption. Along the Lena river delta, elevated concentrations of both nutrients and methane create ideal conditions to support high rates of pelagic methanotrophy. Offshore, where nutrient concentrations are lower and more limiting, methane oxidation rates are considerably lower. These data suggest that, at present, nearshore waters are fairly efficient methane sinks while in offshore waters, pelagic methanotrophy is inefficient, allowing methane to escape to the atmosphere.

  19. Formation of methane fields in the Golubaya bay of the Black Sea

    NASA Astrophysics Data System (ADS)

    Kovaleva, Elena

    2014-05-01

    Study of formation of methane fields in water environments is essential for search of oil and gas in bottom sediments of the aquatories [Egorov et al., 2008]. Methane acts as a tracer of various biogeochemical processes in freshwater and marine waters as well. Moreover, in recent years estimation of methane emission is one of tasks of current climate research because of high contribution of methane in the greenhouse effect [Bazhin, 2000]. The Black Sea is the largest methane reservoir in the world [Lein, Ivanov, 2005]. The Golubaya Bay of the Black Sea acts as a peculiar model of formation and variability of methane fields in the marine environment. The main purpose of our study is to identify factors that influence the high methane saturation in the aerobic coastal waters. Data collection took place in the Golubaya and the Gelendzhikskaya bays and in the Ashamba River since 1999 to 2013. Water samples were analyzed by the head-space method with further gas chromatographic determination of methane concentrations [Bolshakov, Egorov, 1987]. Methane saturation in the Golubaya Bay waters exceeds the equilibrium with the atmosphere value 10-100 times. According to the simultaneous measurements of methane in two bays in different seasons, methane saturation in the Golubaya Bay is higher than in the Gelendzhikskaya Bay. The smaller bottom depth and accordingly the larger biological productivity in the Golubaya Bay may be the reason of it. Microbial production of methane in aerobic waters of the bay is associated with zone of zooplankton concentration and products of its vital activity [Lein, Ivanov, 2009]. It is known that formation of methane is intense in periodically flooded soils where anaerobic conditions are formed. That causes development of methanogenic bacteria [Alekseev et al., 1978]. Distribution of methane in marine and river waters illustrates that the river runoff and groundwater supply are some of the sources of high methane saturation in the Golubaya Bay

  20. Modelling Methane Dynamics from Northern Wetlands with JSBACH

    NASA Astrophysics Data System (ADS)

    Tomasic, M. A.; Vesala, T.; Getzieh, R.; Raivonen, M.; Brovkin, V.; Hölttä, T.

    2010-12-01

    Methane emissions from northern boreal peatlands are an important part of the global methane budget, and their role is expected to increase in the future climate scenarios. A new methane emission model for the JSBACH land surface component of the MPI Earth system Model (MPI-ESM) is developed. The approach is partly based on previous CH4 wetland hydrology modelling approaches from the LPJ-WHY-ME (Lund-Potsdam-Jena Wetland Hydrology Methane) model (Wania et al. 2009). In a first step, it comprises three pathways of emission: 1) diffusion through the peat layers; 2) plant mediated transport; 3) bubble formation and release to the atmosphere. For the third point we plan to test a different methane bubble formation approach than Wania et al. (2009). Our approach will be related to the nucleation theory (Hölttä et al. 2002) and we will derive the methane concentration in bubbles and link them to the saturation levels of methane in wetlands. Before its final implementation, the CH4 model will be tested as a stand alone version with data from measurement stations in Finland and Canada.

  1. Sources of atmospheric methane from coastal marine wetlands

    NASA Technical Reports Server (NTRS)

    Harriss, R. C.; Sebacher, D. I.; Bartlett, K. B.; Bartlett, D. S.

    1982-01-01

    Biological methanogenesis in wetlands is believed to be one of the major sources of global tropospheric methane. The present paper reports measurements of methane distribution in the soils, sediments, water and vegetation of coastal marine wetlands. Measurements, carried out in the salt marshes Bay Tree Creek in Virginia and Panacea in northwest Florida, reveal methane concentrations in soils and sediments to vary with depth below the surface and with soil temperature. The fluxes of methane from marsh soils to the atmosphere at the soil-air interface are estimated to range from -0.00067 g CH4/sq m per day (methane sink) to 0.024 g CH4/sq m per day, with an average value of 0.0066 g CH4/sq m per day. Data also demonstrate the important role of tidal waters percolating through marsh soils in removing methane from the soils and releasing it to the atmosphere. The information obtained, together with previous studies, provides a framework for the design of a program based on in situ and remote sensing measurements to study the global methane cycle.

  2. Quantitative spatiotemporal characterization of methane venting from lake sediments

    NASA Astrophysics Data System (ADS)

    Scandella, B.; Pillsbury, L.; Weber, T.; Ruppel, C. D.; Hemond, H.; Juanes, R.

    2014-12-01

    Methane is a potent greenhouse gas, and the production and emission of methane from sediments in inland waters and shallow oceans both contributes to and may be exacerbated by climate change. In some of these shallow-water settings, methane fluxes are often controlled by episodic free-gas venting. The fraction of the methane released from the sediments that bypasses dissolution in the water column and reaches the atmosphere impacts the magnitude of the climate forcing, and this fraction depends critically on the mode and spatiotemporal characteristics of the bubble releases. The spacing and persistence of the gas vents may be determined by the heterogeneity of the methane source, but within regions of uniform methanogenesis they arise from the competition between mechanisms driving lateral and vertical transport of methane in the sediments. Here, we present measurements of the spacing, persistence and variability in intensity of methane vents within a wide area of lake sediments (~400 m2) and over a multi-month period. The measurements were made using a fixed-location Imagenex DeltaT 837B multibeam sonar, which was calibrated to quantify gas fluxes with unprecedented spatial and temporal resolution (~0.5 m, 6 Hz). Drops in hydrostatic pressure were a characteristic trigger for the sonar-detected ebullition events, and the episodicity of the fluxes is reproduced with a mechanistic numerical model of methane venting through dynamic conduits that dilate in response to hydrostatic unloading. The spatial characteristics of the sonar-detected vents inform conceptual and mathematical models of methane transport and release from deformable sediments, as well as the uncertainty associated with upscaling. Taken together, these results point towards a better understanding of the microscale processes controlling methane venting from deformable sediments, as well as their impact on large-scale methane fluxes from shallow-water bodies. Figure: Top: time series of daily sonar

  3. Contribution of oceanic gas hydrate dissociation to the formation of Arctic Ocean methane plumes

    SciTech Connect

    Reagan, M.; Moridis, G.; Elliott, S.; Maltrud, M.

    2011-06-01

    Vast quantities of methane are trapped in oceanic hydrate deposits, and there is concern that a rise in the ocean temperature will induce dissociation of these hydrate accumulations, potentially releasing large amounts of carbon into the atmosphere. Because methane is a powerful greenhouse gas, such a release could have dramatic climatic consequences. The recent discovery of active methane gas venting along the landward limit of the gas hydrate stability zone (GHSZ) on the shallow continental slope (150 m - 400 m) west of Svalbard suggests that this process may already have begun, but the source of the methane has not yet been determined. This study performs 2-D simulations of hydrate dissociation in conditions representative of the Arctic Ocean margin to assess whether such hydrates could contribute to the observed gas release. The results show that shallow, low-saturation hydrate deposits, if subjected to recently observed or future predicted temperature changes at the seafloor, can release quantities of methane at the magnitudes similar to what has been observed, and that the releases will be localized near the landward limit of the GHSZ. Both gradual and rapid warming is simulated, along with a parametric sensitivity analysis, and localized gas release is observed for most of the cases. These results resemble the recently published observations and strongly suggest that hydrate dissociation and methane release as a result of climate change may be a real phenomenon, that it could occur on decadal timescales, and that it already may be occurring.

  4. Seasonal Oxygen Dynamics in a Thermokarst Bog in Interior Alaska: Implications for Rates of Methane Oxidation

    NASA Astrophysics Data System (ADS)

    Neumann, R. B.; Moorberg, C.; Wong, A.; Waldrop, M. P.; Turetsky, M. R.

    2015-12-01

    Methane is a potent greenhouse gas, and wetlands represent the largest natural source of methane to the atmosphere. However, much of the methane generated in anoxic wetlands never gets emitted to the atmosphere; up to >90% of generated methane can get oxidized to carbon dioxide. Thus, oxidation is an important methane sink and changes in the rate of methane oxidation can affect wetland methane emissions. Most methane is aerobically oxidized at oxic-anoxic interfaces where rates of oxidation strongly depend on methane and oxygen concentrations. In wetlands, oxygen is often the limiting substrate. To improve understanding of belowground oxygen dynamics and its impact on methane oxidation, we deployed two planar optical oxygen sensors in a thermokarst bog in interior Alaska. Previous work at this site indicated that, similar to other sites, rates of methane oxidation decrease over the growing season. We used the sensors to track spatial and temporal patterns of oxygen concentrations over the growing season. We coupled these in-situ oxygen measurements with periodic oxygen injection experiments performed against the sensor to quantify belowground rates of oxygen consumption. We found that over the season, the thickness of the oxygenated water layer at the peatland surface decreased. Previous research has indicated that in sphagnum-dominated peatlands, like the one studied here, rates of methane oxidation are highest at or slightly below the water table. It is in these saturated but oxygenated locations that both methane and oxygen are available. Thus, a seasonal reduction in the thickness of the oxygenated water layer could restrict methane oxidation. The decrease in thickness of the oxygenated layer coincided with an increase in the rate of oxygen consumption during our oxygen injection experiments. The increase in oxygen consumption was not explained by temperature; we infer it was due to an increase in substrate availability for oxygen consuming reactions and

  5. [Methanogens and manipulation of methane production in the rumen].

    PubMed

    Guo, Yan-qiu; Hu, Wei-lian; Liu, Jian-xin

    2005-02-01

    Methanogens belong to the kingdom of Euryarchaeota in the domain of Archaea. They are characterized by their ability to produce methane under anaerobic conditions. Methane production in the rumen represents a loss of energy for the host animal, and, in addition, methane eructated by ruminants may contribute to a greenhouse effect or global warming. Reduction or elimination of methanogenesis in the rumen has been touted as a way of improving animal production and may marginally benefit to control of anthropogenic release of methane. More and more scientists focus on ruminal methanogens and methanogenesis recently. Authors summarized the manipulation of methanogenesis in the rumen, including defaunation, feed formulation, adding electron acceptors and stimulation of acetogens. The characteristics of methanogenic Archaea and the recent knowledge of the methanogenesis in the rumen were also reviewed in this article.

  6. A Geochemical Model for the Origin of Methane on Titan

    NASA Astrophysics Data System (ADS)

    Glein, C. R.; Shock, E. L.

    2007-12-01

    hypothesis states that high temperatures driven by radioactive decay [4] changed the chemistry of the core via metamorphism. Preliminary calculations indicate that hydrous minerals recrystallize into anhydrous minerals by releasing water, which oxidizes Fe metal, producing dihydrogen (i.e., reducing conditions). In response, organic matter in the core is broken down into carbon-bearing solids, liquids, and gases, including methane. In time, methane can migrate into the ocean, where it can be trapped in clathrate hydrates and subsequently released into the atmosphere [3]. References: [1] Owen T.C. (2000) P&SS 48, 747-752. [2] Niemann H.B. et al. (2005) Nature 438, 779-784. [3] Tobie G. et al. (2006) Nature 440, 61-64. [4] Grasset O. et al. (2000) P&SS 48, 617-636.

  7. Use of aerobic spores as a surrogate for cryptosporidium oocysts in drinking water supplies.

    PubMed

    Headd, Brendan; Bradford, Scott A

    2016-03-01

    Waterborne illnesses are a growing concern among health and regulatory agencies worldwide. The United States Environmental Protection Agency has established several rules to combat the contamination of water supplies by cryptosporidium oocysts, however, the detection and study of cryptosporidium oocysts is hampered by methodological and financial constraints. As a result, numerous surrogates for cryptosporidium oocysts have been proposed by the scientific community and efforts are underway to evaluate many of the proposed surrogates. The purpose of this review is to evaluate the suitability of aerobic bacterial spores to serve as a surrogate for cryptosporidium oocysts in identifying contaminated drinking waters. To accomplish this we present a comparison of the biology and life cycles of aerobic spores and oocysts and compare their physical properties. An analysis of their surface properties is presented along with a review of the literature in regards to the transport, survival, and prevalence of aerobic spores and oocysts in the saturated subsurface environment. Aerobic spores and oocysts share many commonalities with regard to biology and survivability, and the environmental prevalence and ease of detection make aerobic spores a promising surrogate for cryptosporidium oocysts in surface and groundwater. However, the long-term transport and release of aerobic spores still needs to be further studied, and compared with available oocyst information. In addition, the surface properties and environmental interactions of spores are known to be highly dependent on the spore taxa and purification procedures, and additional research is needed to address these issues in the context of transport.

  8. Degradation of municipal solid waste in simulated landfill bioreactors under aerobic conditions.

    PubMed

    Slezak, Radoslaw; Krzystek, Liliana; Ledakowicz, Stanislaw

    2015-09-01

    In this study the municipal solid waste degradation processes in simulated landfill bioreactors under aerobic and anaerobic conditions is investigated. The effect of waste aeration on the dynamics of the aerobic degradation processes in lysimeters as well as during anaerobic processes after completion of aeration is presented. The results are compared with the anaerobic degradation process to determine the stabilization stage of waste in both experimental modes. The experiments in aerobic lysimeters were carried out at small aeration rate (4.41⋅10(-3)lmin(-1)kg(-1)) and for two recirculation rates (24.9 and 1.58lm(-3)d(-1)). The change of leachate and formed gases composition showed that the application of even a small aeration rate favored the degradation of organic matter. The amount of CO2 and CH4 released from anaerobic lysimeter was about 5 times lower than that from the aerobic lysimeters. Better stabilization of the waste was obtained in the aerobic lysimeter with small recirculation, from which the amount of CO2 produced was larger by about 19% in comparison with that from the aerobic lysimeter with large leachate recirculation.

  9. Characteristics of slush and boiling methane and methane mixtures.

    NASA Technical Reports Server (NTRS)

    Sindt, C. F.; Ludtke, P. R.

    1971-01-01

    Methane gas of two purities, 99.97% and 99%, was condensed to study the characteristics of the boiling liquid and the slush. In addition, binary mixtures of nitrogen and methane, and those of ethane and methane, and propane and methane, were also studied. Potential advantages of these gases when employed as fuels for high-performance aircraft, rocket engines, and motor vehicles are emphasized.

  10. Methane formation and methane oxidation by methanogenic bacteria.

    PubMed Central

    Zehnder, A J; Brock, T D

    1979-01-01

    Methanogenic bacteria were found to form and oxidize methane at the same time. As compared to the quantity of methane formed, the amount of methane simultaneously oxidized varied between 0.3 and 0.001%, depending on the strain used. All the nine tested strains of methane producers (Methanobacterium ruminantium, Methanobacterium strain M.o.H., M. formicicum, M. thermoautotrophicum, M. arbophilicum, Methanobacterium strain AZ, Methanosarcina barkeri, Methanospirillum hungatii, and the "acetate organism") reoxidized methane to carbon dioxide. In addition, they assimilated a small part of the methane supplied into cell material. Methanol and acetate also occurred as oxidation products in M. barkeri cultures. Acetate was also formed by the "acetate organism," a methane bacterium unable to use methanogenic substrates other than acetate. Methane was the precursor of the methyl group of the acetate synthesized in the course of methane oxidation. Methane formation and its oxidation were inhibited equally by 2-bromoethanesulfonic acid. Short-term labeling experiments with M. thermoautotrophicum and M. hungatii clearly suggest that the pathway of methane oxidation is not identical with a simple back reaction of the methane formation process. Images PMID:762019

  11. Sonogashira and "Click" reactions for the N-terminal and side-chain functionalization of peptides with [Mn(CO)3(tpm)]+-based CO releasing molecules (tpm = tris(pyrazolyl)methane).

    PubMed

    Pfeiffer, Hendrik; Rojas, Alfonso; Niesel, Johanna; Schatzschneider, Ulrich

    2009-06-14

    A recently identified photoactivatable CO releasing molecule (CORM) based on [Mn(CO)(3)(tpm)](+) was conjugated to functionalized amino acids and model peptides using the Pd-catalyzed Sonogashira cross-coupling and the alkyne-azide 1,3-dipolar cycloaddition ("Click reaction"). Both were found to be fully compatible with all functional groups present. The CORM-peptide conjugates were isolated in reasonable yield and high purity, as indicated by IR spectroscopy, ESI mass spectrometry and RP-HPLC. The myoglobin assay was used to demonstrate that they have CO release properties identical those of the parent compound. This work thus opens the way for a targeted delivery of CORMs to cellular systems.

  12. Metagenomics of Hydrocarbon Resource Environments Indicates Aerobic Taxa and Genes to be Unexpectedly Common

    PubMed Central

    2013-01-01

    Oil in subsurface reservoirs is biodegraded by resident microbial communities. Water-mediated, anaerobic conversion of hydrocarbons to methane and CO2, catalyzed by syntrophic bacteria and methanogenic archaea, is thought to be one of the dominant processes. We compared 160 microbial community compositions in ten hydrocarbon resource environments (HREs) and sequenced twelve metagenomes to characterize their metabolic potential. Although anaerobic communities were common, cores from oil sands and coal beds had unexpectedly high proportions of aerobic hydrocarbon-degrading bacteria. Likewise, most metagenomes had high proportions of genes for enzymes involved in aerobic hydrocarbon metabolism. Hence, although HREs may have been strictly anaerobic and typically methanogenic for much of their history, this may not hold today for coal beds and for the Alberta oil sands, one of the largest remaining oil reservoirs in the world. This finding may influence strategies to recover energy or chemicals from these HREs by in situ microbial processes. PMID:23889694

  13. Aerobic rice mechanization: techniques for crop establishment

    NASA Astrophysics Data System (ADS)

    Khusairy, K. M.; Ayob, H.; Chan, C. S.; Fauzi, M. I. Mohamed; Mohamad Fakhrul, Z. O.; Shahril Shah, G. S. M.; Azlan, O.; Rasad, M. A.; Hashim, A. M.; Arshad, Z.; E, E. Ibrahim; Saifulizan, M. N.

    2015-12-01

    Rice being the staple food crops, hundreds of land races in it makes the diversity of rice crops. Aerobic rice production was introduced which requires much less water input to safeguard and sustain the rice production and conserve water due to decreasing water resources, climatic changes and competition from urban and industrial users. Mechanization system plays an important role for the success of aerobic rice cultivation. All farming activities for aerobic rice production are run on aerobic soil conditions. Row seeder mechanization system is developed to replace conventional seeding technique on the aerobic rice field. It is targeted for small and the large scale aerobic rice farmers. The aero - seeder machine is used for the small scale aerobic rice field, while the accord - seeder is used for the large scale aerobic rice field. The use of this mechanization machine can eliminate the tedious and inaccurate seeding operations reduce labour costs and increases work rate. The machine is easy to operate and it can increase crop establishment rate. It reduce missing hill, increasing planting and crop with high yield can be produce. This machine is designed for low costs maintenance and it is easy to dismantle and assemble during maintenance and it is safe to be used.

  14. Aerobic Dancing--A Rhythmic Sport.

    ERIC Educational Resources Information Center

    Sorensen, Jacki

    Fitness programs now and in the future must offer built-in cardiovascular conditioning, variety, novelty, and change to meet the physical, mental, and emotional needs of our society. Aerobic dancing (dancing designed to train and strengthen the heart, lungs, and vascular system) is one of the first indoor group Aerobic exercise programs designed…

  15. Skeletal Muscle Hypertrophy after Aerobic Exercise Training

    PubMed Central

    Konopka, Adam R.; Harber, Matthew P.

    2014-01-01

    Current dogma suggests aerobic exercise training has minimal effect on skeletal muscle size. We and others have demonstrated that aerobic exercise acutely and chronically alters protein metabolism and induces skeletal muscle hypertrophy. These findings promote an antithesis to the status quo by providing novel perspective on skeletal muscle mass regulation and insight into exercise-countermeasures for populations prone to muscle loss. PMID:24508740

  16. Identifying active methane-oxidizers in thawed Arctic permafrost by proteomics

    NASA Astrophysics Data System (ADS)

    Lau, C. M.; Stackhouse, B. T.; Chourey, K.; Hettich, R. L.; Vishnivetskaya, T. A.; Pfiffner, S. M.; Layton, A. C.; Mykytczuk, N. C.; Whyte, L.; Onstott, T. C.

    2012-12-01

    The rate of CH4 release from thawing permafrost in the Arctic has been regarded as one of the determining factors on future global climate. It is uncertain how indigenous microorganisms would interact with such changing environmental conditions and hence their impact on the fate of carbon compounds that are sequestered in the cryosol. Multitudinous studies of pristine surface cryosol (top 5 cm) and microcosm experiments have provided growing evidence of effective methanotrophy. Cryosol samples corresponding to active layer were sampled from a sparsely vegetated, ice-wedge polygon at the McGill Arctic Research Station at Axel Heiberg Island, Nunavut, Canada (N79°24, W90°45) before the onset of annual thaw. Pyrosequencing of 16S rRNA gene indicated the occurrence of methanotroph-containing bacterial families as minor components (~5%) in pristine cryosol including Bradyrhizobiaceae, Methylobacteriaceae and Methylocystaceae within alpha-Proteobacteria, and Methylacidiphilaceae within Verrucomicrobia. The potential of methanotrophy is supported by preliminary analysis of metagenome data, which indicated putative methane monooxygenase gene sequences relating to Bradyrhizobium sp. and Pseudonocardia sp. are present. Proteome profiling in general yielded minute traces of proteins, which likely hints at dormant nature of the soil microbial consortia. The lack of specific protein database for permafrost posted additional challenge to protein identification. Only 35 proteins could be identified in the pristine cryosol and of which 60% belonged to Shewanella sp. Most of the identified proteins are known to be involved in energy metabolism or post-translational modification of proteins. Microcosms amended with sodium acetate exhibited a net methane consumption of ~65 ngC-CH4 per gram (fresh weight) of soil over 16 days of aerobic incubation at room temperature. The pH in microcosm materials remained acidic (decreased from initial 4.7 to 4.5). Protein extraction and

  17. Method of making compost and spawned compost, mushroom spawn and generating methane gas

    SciTech Connect

    Stoller, B.B.

    1981-04-28

    Newly designed ribbon-type mixers provide an improved method for making composts, aerating composts, growing mushroom spawn, generating methane gas, and filling conveyors in the mushroom-growing industry. The mixers may be the double-ribbon type for purely mixing operations or the single-ribbon type for moving the material from one place to another. Both types can operate under pressure. In preparing compost for mushroom growing, operators can first use the airtight mixers for a preliminary anaerobic fermentation to produce methane, then by changing the atmosphere to an oxidizing one, complete the compost preparation under the necessary aerobic conditions.

  18. Anaerobic oxidation of methane: an “active” microbial process

    PubMed Central

    Cui, Mengmeng; Ma, Anzhou; Qi, Hongyan; Zhuang, Xuliang; Zhuang, Guoqiang

    2015-01-01

    The anaerobic oxidation of methane (AOM) is an important sink of methane that plays a significant role in global warming. AOM was first found to be coupled with sulfate reduction and mediated by anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB). ANME, often forming consortia with SRB, are phylogenetically related to methanogenic archaea. ANME-1 is even able to produce methane. Subsequently, it has been found that AOM can also be coupled with denitrification. The known microbes responsible for this process are Candidatus Methylomirabilis oxyfera (M. oxyfera) and Candidatus Methanoperedens nitroreducens (M. nitroreducens). Candidatus Methylomirabilis oxyfera belongs to the NC10 bacteria, can catalyze nitrite reduction through an “intra-aerobic” pathway, and may catalyze AOM through an aerobic methane oxidation pathway. However, M. nitroreducens, which is affiliated with ANME-2d archaea, may be able to catalyze AOM through the reverse methanogenesis pathway. Moreover, manganese (Mn4+) and iron (Fe3+) can also be used as electron acceptors of AOM. This review summarizes the mechanisms and associated microbes of AOM. It also discusses recent progress in some unclear key issues about AOM, including ANME-1 in hypersaline environments, the effect of oxygen on M. oxyfera, and the relationship of M. nitroreducens with ANME. PMID:25530008

  19. Enhanced coalbed methane recovery

    SciTech Connect

    Mazzotti, M.; Pini, R.; Storti, G.

    2009-01-15

    The recovery of coalbed methane can be enhanced by injecting CO{sub 2} in the coal seam at supercritical conditions. Through an in situ adsorption/desorption process the displaced methane is produced and the adsorbed CO{sub 2} is permanently stored. This is called enhanced coalbed methane recovery (ECBM) and it is a technique under investigation as a possible approach to the geological storage of CO{sub 2} in a carbon dioxide capture and storage system. This work reviews the state of the art on fundamental and practical aspects of the technology and summarizes the results of ECBM field tests. These prove the feasibility of ECBM recovery and highlight substantial opportunities for interdisciplinary research at the interface between earth sciences and chemical engineering.

  20. Transformations in methane hydrates

    USGS Publications Warehouse

    Chou, I.-Ming; Sharma, A.; Burruss, R.C.; Shu, J.; Mao, Ho-kwang; Hemley, R.J.; Goncharov, A.F.; Stern, L.A.; Kirby, S.H.

    2000-01-01

    Detailed study of pure methane hydrate in a diamond cell with in situ optical, Raman, and x-ray microprobe techniques reveals two previously unknown structures, structure II and structure H, at high pressures. The structure II methane hydrate at 250 MPa has a cubic unit cell of a = 17.158(2) A?? and volume V = 5051.3(13) A??3; structure H at 600 MPa has a hexagonal unit cell of a = 11.980(2) A??, c = 9.992(3) A??, and V = 1241.9(5) A??3. The compositions of these two investigated phases are still not known. With the effects of pressure and the presence of other gases in the structure, the structure II phase is likely to dominate over the known structure I methane hydrate within deep hydrate-bearing sediments underlying continental margins.

  1. Filamentous bacteria existence in aerobic granular reactors.

    PubMed

    Figueroa, M; Val del Río, A; Campos, J L; Méndez, R; Mosquera-Corral, A

    2015-05-01

    Filamentous bacteria are associated to biomass settling problems in wastewater treatment plants. In systems based on aerobic granular biomass they have been proposed to contribute to the initial biomass aggregation process. However, their development on mature aerobic granular systems has not been sufficiently studied. In the present research work, filamentous bacteria were studied for the first time after long-term operation (up to 300 days) of aerobic granular systems. Chloroflexi and Sphaerotilus natans have been observed in a reactor fed with synthetic wastewater. These filamentous bacteria could only come from the inoculated sludge. Thiothrix and Chloroflexi bacteria were observed in aerobic granular biomass treating wastewater from a fish canning industry. Meganema perideroedes was detected in a reactor treating wastewater from a plant processing marine products. As a conclusion, the source of filamentous bacteria in these mature aerobic granular systems fed with industrial effluents was the incoming wastewater.

  2. Methane-Powered Airplane

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Beech Aircraft's Corporation's Boulder Division developed expertise in producing superinsulated virtually leak-proof cryogenic equipment for storing liquid oxygen and hydrogen fuels in NASA's Apollo, Skylab and Space Shuttle programs. Boulder Division used this experience in designing a fuel storage tank for liquid methane, a "cryogenic" fuel that must be supercooled to keep it liquid. Beech Aircraft is producing a four-place lightplane powered by liquid methane (LM) which is stored in two of these specially designed cryogenic storage tanks holding 18 gallons each.

  3. Biomimetic methane oxidation

    SciTech Connect

    Watkins, B.E.; Droege, M.W.; Taylor, R.T.; Satcher, J.H.

    1992-06-12

    Methane monooxygenase (MMO) is an enzyme found in methanotrophs that catalyses the selective oxidation of methane to methanol. MMO is protein complex one component of which is a binuclear metal center containing oxygenase. We have completed one round of a design/synthesis/evaluation cycle in the development of coordination complexes that mimic the structure/function of the MMO active site. One of these, a binuclear, coordinately-asymmetric copper complex, is capable of oxidizing cyclohexane to a mixture of cyclohexanol and cyclohexanone in the presence of hydrogen peroxide.

  4. The fate of methane clathrate hydrate within Titan

    NASA Astrophysics Data System (ADS)

    Tobie, G.; Lunine, J. I.; Sotin, C.

    2004-12-01

    Titan has a thick atmosphere composed primarily of nitrogen and methane. Methane is known to be irreversibly consumed photochemically on a timescale of a few tens of million years, which implies that any replenishment process must occur to maintain the methane abundance to its current value. Methane is believed to have been trapped within clathrate hydrate, a particular structure of ice, in Saturn's subnebula environnement, and then to have been incorporated within Titan's interior. Although the major part of clathrates is likely to have been devolatilized during the late stage of Titan's accretion, a significant portion could have "survived" within the deeper interior and could have been released later in Titan's history. Through coupled thermal and orbital calculations including a full description of the tidal dissipation, the heat transfer,the H2O-NH3 phase diagram and the methane clathrate stability, we study the possible evolution of clathrate distribution within Titan's interior, its effect of the thermal evolution, and the process of degassing from the interior. We show that only models with a few percent of ammonia and a significant fraction of methane clathrate within the interior can explain both the conservation of Titan's high eccentricity over the age of the solar system and the methane replenishment of the atmosphere. In our preferred scenario, two episodes of methane degassing are predicted: one during the first billion years and a second one after 3.5-4 Ga, explaining the present-day atmospheric methane abundance. Forthcoming data from the NASA/ESA Cassini-Huygens mission will allow us to test the present predictions.

  5. Methane on Titan: Photochemical-Meteorological-Hydrogeochemical Cycle

    NASA Astrophysics Data System (ADS)

    Atreya, S. K.; Niemann, H. B.; Owen, T. C.; Adams, E. Y.; Demick, J. E.; GCMS Team

    2005-08-01

    Photochemically driven destruction of methane in Titan's stratosphere leads to irreversible conversion to heavier hydrocarbons (1). The latter would largely condense out of the atmosphere (2). In the absence of recycling, Titan's methane would thus be destroyed in 10-100 million years (1). However, methane is key to the maintenance of Titan's nitrogen atmosphere. Without warming provided by CH4-generated hydrocarbon hazes in the stratosphere and pressure induced opacity in the infrared, particularly by H2-N2 and CH4-N2 collisions in the troposphere, the atmosphere would gradually diminish to tens of millibar pressure (3). Thus, the source-sink cycle of methane is crucial to the evolutionary history of Titan and its atmosphere. The GCMS measurements show that a ``methalogical" cycle with surface evaporation, cloud formation, followed by precipitation (rain) of methane exists. However, this ``closed" cycle does not recycle methane lost to heavy hydrocarbons. A source is required. Unlike the deep, hot, H2-rich interiors of the giant planets, Titan's interior is ill suited for thermochemical conversion of hydrocarbons back to methane. Instead we propose that serpentinization is an effective process for producing methane in Titan's interior (4). Hydration of ultramafic silicates, followed by reaction between the released H2 gas and CO2 or carbon grains can produce large quantities of CH4 at relatively mild (40-90oC) temperatures. Such thermal conditions are believed to exist below the purported water-ammonia ocean (5). Storage of methane produced via serpentinization can occur in form of clathrates. Evidence of outgassing from Titan's interior is provided by GCMS (6) and VIMS (7) data. (1) Wilson, Atreya, JGR 109, E06002, doi:10.1029/2003JE002181, 2004. (2) Wilson, Atreya, PSS 51, 1017, 2003. (3) Lorenz etal. Science 275, 642, 1997. (4) Owen etal. Phys. Uspekhi, in press. (5) Grasset, Pargamin, PSS 53, 371, 2005. (6) Niemann etal., Submitted to Nature, 2005. (7) Sotin

  6. Methane-Oxidizing Enzymes: An Upstream Problem in Biological Gas-to-Liquids Conversion.

    PubMed

    Lawton, Thomas J; Rosenzweig, Amy C

    2016-08-01

    Biological conversion of natural gas to liquids (Bio-GTL) represents an immense economic opportunity. In nature, aerobic methanotrophic bacteria and anaerobic archaea are able to selectively oxidize methane using methane monooxygenase (MMO) and methyl coenzyme M reductase (MCR) enzymes. Although significant progress has been made toward genetically manipulating these organisms for biotechnological applications, the enzymes themselves are slow, complex, and not recombinantly tractable in traditional industrial hosts. With turnover numbers of 0.16-13 s(-1), these enzymes pose a considerable upstream problem in the biological production of fuels or chemicals from methane. Methane oxidation enzymes will need to be engineered to be faster to enable high volumetric productivities; however, efforts to do so and to engineer simpler enzymes have been minimally successful. Moreover, known methane-oxidizing enzymes have different expression levels, carbon and energy efficiencies, require auxiliary systems for biosynthesis and function, and vary considerably in terms of complexity and reductant requirements. The pros and cons of using each methane-oxidizing enzyme for Bio-GTL are considered in detail. The future for these enzymes is bright, but a renewed focus on studying them will be critical to the successful development of biological processes that utilize methane as a feedstock. PMID:27366961

  7. Diversity and Habitat Preferences of Cultivated and Uncultivated Aerobic Methanotrophic Bacteria Evaluated Based on pmoA as Molecular Marker

    PubMed Central

    Knief, Claudia

    2015-01-01

    Methane-oxidizing bacteria are characterized by their capability to grow on methane as sole source of carbon and energy. Cultivation-dependent and -independent methods have revealed that this functional guild of bacteria comprises a substantial diversity of organisms. In particular the use of cultivation-independent methods targeting a subunit of the particulate methane monooxygenase (pmoA) as functional marker for the detection of aerobic methanotrophs has resulted in thousands of sequences representing “unknown methanotrophic bacteria.” This limits data interpretation due to restricted information about these uncultured methanotrophs. A few groups of uncultivated methanotrophs are assumed to play important roles in methane oxidation in specific habitats, while the biology behind other sequence clusters remains still largely unknown. The discovery of evolutionary related monooxygenases in non-methanotrophic bacteria and of pmoA paralogs in methanotrophs requires that sequence clusters of uncultivated organisms have to be interpreted with care. This review article describes the present diversity of cultivated and uncultivated aerobic methanotrophic bacteria based on pmoA gene sequence diversity. It summarizes current knowledge about cultivated and major clusters of uncultivated methanotrophic bacteria and evaluates habitat specificity of these bacteria at different levels of taxonomic resolution. Habitat specificity exists for diverse lineages and at different taxonomic levels. Methanotrophic genera such as Methylocystis and Methylocaldum are identified as generalists, but they harbor habitat specific methanotrophs at species level. This finding implies that future studies should consider these diverging preferences at different taxonomic levels when analyzing methanotrophic communities. PMID:26696968

  8. Performance evaluation of an anaerobic/aerobic landfill-based digester using yard waste for energy and compost production

    SciTech Connect

    Yazdani, Ramin; Barlaz, Morton A.; Augenstein, Don; Kayhanian, Masoud; Tchobanoglous, George

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Biochemical methane potential decreased by 83% during the two-stage operation. Black-Right-Pointing-Pointer Net energy produced was 84.3 MWh or 46 kWh per million metric tons (Mg). Black-Right-Pointing-Pointer The average removal efficiency of volatile organic compounds (VOCs) was 96-99%. Black-Right-Pointing-Pointer The average removal efficiency of non-methane organic compounds (NMOCs) was 68-99%. Black-Right-Pointing-Pointer The two-stage batch digester proved to be simple to operate and cost-effective. - Abstract: The objective of this study was to evaluate a new alternative for yard waste management by constructing, operating and monitoring a landfill-based two-stage batch digester (anaerobic/aerobic) with the recovery of energy and compost. The system was initially operated under anaerobic conditions for 366 days, after which the yard waste was aerated for an additional 191 days. Off gas generated from the aerobic stage was treated by biofilters. Net energy recovery was 84.3 MWh, or 46 kWh per million metric tons of wet waste (as received), and the biochemical methane potential of the treated waste decreased by 83% during the two-stage operation. The average removal efficiencies of volatile organic compounds and non-methane organic compounds in the biofilters were 96-99% and 68-99%, respectively.

  9. Temporal resilience and dynamics of anaerobic methane-oxidizing microbial communities to short-term changes in methane partial pressures

    NASA Astrophysics Data System (ADS)

    Klasek, S.; Tiantian, Y.; Torres, M. E.; Colwell, F. S.; Wang, F.; Liang, L.

    2015-12-01

    Marine sediments produce tens to hundreds of teragrams of methane annually, which is released from the seabed at thousands of cold seeps distributed globally along continental margins. Around 80-90% of this methane is consumed in shallower sediment layers before reaching the hydrosphere, in a microbially-mediated process known as anaerobic oxidation of methane (AOM) However, cold seeps appear to exhibit temporal variation in gas flux intensity, and AOM filter efficiency at cold seeps generally decreases with fluid flow rate. To our knowledge, the degree to which temporal heterogeneity in subsurface methane flux stimulates AOM community growth and adaptation to increased methane concentrations has not been investigated. Static high-pressure bioreactors were used to incubate sulfate-methane transition zone (SMTZ) and methanogenic zone sediments underlying a Mediterranean mud volcano gas flare under in situ temperature and pressure at 8 MPa methane. Sulfide production rates of 0.4 μmol/cm3/day in both sediment regimes after 4 months of incubation suggested the resilience of the marine subsurface methane filter may extend well below the SMTZ (40 cm). Similar incubations of SMTZ samples from below a gas flare off Svalbard at saturating (3.8 MPa) and 0.2 MPa methane are being sampled after 1 week, 4 weeks, and 4 months; sulfide production rates of 8-18 nmol/cm3/day were first observed after 4 weeks of incubation. Sediment samples at all specified time points for both sets of incubations were collected for nucleic acid extraction and cell fixation. Anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB) are expected dominant taxa in enriched and non-enriched communities. 16S rDNA community analysis is expected to reveal additional microbial players involved in the short-term adaptation to higher methane partial pressures in the marine subsurface. Increased AOM community activity (RNA/DNA ratio) and copy numbers of methane cycling transcripts (mcr

  10. Methane-related microbial processes and metabolic stratification in a terrestrial mud volcano, southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Cheng, T.; Lin, L.; Wang, P.; Chu, P.; Wu, J.

    2009-12-01

    -oxidizing gamma-proteobacteria members were mainly observed in the uppermost sediment samples. Delta-proteobacteria 16S sequences including Desulfuromonadales, Syntrophus, and Desulfomonales constituted significant proportions along the entire depth range. These findings concluded that methanogens were ubiquitously dispersed and actively expressed in the near-surface sediment of the terrestrial mud volcano while aerobic and anaerobic methane oxidation accounted for the methane consumption above SMT. Methane ascending from deep-reservoir would be altered substantially by microbial processes in both isotope compositions and abundances.

  11. Observed variations of methane on Mars unexplained by known atmospheric chemistry and physics.

    PubMed

    Lefèvre, Franck; Forget, François

    2009-08-01

    The detection of methane on Mars has revived the possibility of past or extant life on this planet, despite the fact that an abiogenic origin is thought to be equally plausible. An intriguing aspect of the recent observations of methane on Mars is that methane concentrations appear to be locally enhanced and change with the seasons. However, methane has a photochemical lifetime of several centuries, and is therefore expected to have a spatially uniform distribution on the planet. Here we use a global climate model of Mars with coupled chemistry to examine the implications of the recently observed variations of Martian methane for our understanding of the chemistry of methane. We find that photochemistry as currently understood does not produce measurable variations in methane concentrations, even in the case of a current, local and episodic methane release. In contrast, we find that the condensation-sublimation cycle of Mars' carbon dioxide atmosphere can generate large-scale methane variations differing from those observed. In order to reproduce local methane enhancements similar to those recently reported, we show that an atmospheric lifetime of less than 200 days is necessary, even if a local source of methane is only active around the time of the observation itself. This implies an unidentified methane loss process that is 600 times faster than predicted by standard photochemistry. The existence of such a fast loss in the Martian atmosphere is difficult to reconcile with the observed distribution of other trace gas species. In the case of a destruction mechanism only active at the surface of Mars, destruction of methane must occur with an even shorter timescale of the order of approximately 1 hour to explain the observations. If recent observations of spatial and temporal variations of methane are confirmed, this would suggest an extraordinarily harsh environment for the survival of organics on the planet.

  12. Emissions of methane and nitrous oxide from outdoor-stored broiler litter using tunable-diode laser spectroscopy

    NASA Astrophysics Data System (ADS)

    de Wit, William Harrison

    Handling and storage of a variety of types of agricultural wastes results in the formation and release of nitrous oxide (N2O) and methane (CH4) gases to the atmosphere. These gases contribute to climate change through the greenhouse effect. Few studies have examined evolution of these gases from stored poultry litter in North America. Although N 2O is a by-product of nitrification, it is largely produced as an intermediate product of denitrification and is produced most intensely when both aerobic and anaerobic conditions are present. CH4 emissions, however, are typically associated with anaerobic reactions. Outdoor storage of broiler litter provides an excellent media for which both aerobic and anaerobic zones can coexist, particularly when the litter is of varying ages from multiple broiler flocks (cycles). It provides a large amount of nitrogen for bacterial nitrification/denitrification processes as well as Carbon to support anaerobic bacterial fermentation. The objective of the study was to quantify N 2O and CH4 emissions for broiler litter stored in an uncovered, outdoor bunker by conducting small-scale dynamic flux chamber studies and full-scale field experiments. The field experiments used a modified micrometeorological mass balance approach to monitor emissions from stored broiler litter in a three-walled concrete bunker. Atmospheric concentrations of N2O and CH4 were measured using tunable-diode laser spectroscopy. Field experiments over the course of approximately four months yielded average emission rates of 14+/-17mug m-2 s -1 and 84+/-61 mug m-2 s-1 for N2O and CH4 respectively that agreed well with the trends of emission rates observed in the dynamic flux chamber experiments. The primary drivers of emissions of both CH4 and N2O appeared to be temperature and moisture content while organic carbon and organic nitrogen (loss on ignition, nitrate concentrations) contents were also important factors.

  13. High rate of methane leakage from natural gas production

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2013-10-01

    Natural gas production is growing as the United States seeks domestic sources of relatively clean energy. Natural gas combustion produces less carbon dioxide emissions than coal or oil for the amount of energy produced. However, one source of concern is that some natural gas leaks to the atmosphere from the extraction point, releasing methane, a potent greenhouse gas.

  14. Methane emissions from the 2015 Aliso Canyon blowout in Los Angeles, CA.

    PubMed

    Conley, S; Franco, G; Faloona, I; Blake, D R; Peischl, J; Ryerson, T B

    2016-03-18

    Single-point failures of natural gas infrastructure can hamper methane emission control strategies designed to mitigate climate change. The 23 October 2015 blowout of a well connected to the Aliso Canyon underground storage facility in California resulted in a massive release of natural gas. Analysis of methane and ethane data from dozens of plume transects, collected during 13 research-aircraft flights between 7 November 2015 and 13 February 2016, shows atmospheric leak rates of up to 60 metric tons of methane and 4.5 metric tons of ethane per hour. At its peak, this blowout effectively doubled the methane emission rate of the entire Los Angeles basin and, in total, released 97,100 metric tons of methane to the atmosphere. PMID:26917596

  15. Synthetic methylotrophy: engineering the production of biofuels and chemicals based on the biology of aerobic methanol utilization.

    PubMed

    Whitaker, William B; Sandoval, Nicholas R; Bennett, Robert K; Fast, Alan G; Papoutsakis, Eleftherios T

    2015-06-01

    Synthetic methylotrophy is the development of non-native methylotrophs that can utilize methane and methanol as sole carbon and energy sources or as co-substrates with carbohydrates to produce metabolites as biofuels and chemicals. The availability of methane (from natural gas) and its oxidation product, methanol, has been increasing, while prices have been decreasing, thus rendering them as attractive fermentation substrates. As they are more reduced than most carbohydrates, methane and methanol, as co-substrates, can enhance the yields of biologically produced metabolites. Here we discuss synthetic biology and metabolic engineering strategies based on the native biology of aerobic methylotrophs for developing synthetic strains grown on methanol, with Escherichia coli as the prototype.

  16. Open Path Tracer Measurements of Methane Emissions from Free Ranging Cattle

    NASA Astrophysics Data System (ADS)

    Griffith, D. W.; Tonini, M.; Bryant, G. R.; Eckard, R.; Grainger, C.; McGinn, S. M.

    2006-12-01

    This paper addresses the need for more accurate and representative measurements of methane emissions from cattle in their natural environments. Improved measurements are or will be required to quantify methane emissions for national greenhouse gas budgets and future carbon trading schemes, and to assess the effectiveness of proposed mitigation strategies. We describe measurements of methane emissions from free- ranging cattle grazing in their natural outdoor environments in Australia and New Zealand. We employ a novel tracer method in which nitrous oxide is released at a known rate from fenceline tubing or canisters attached to individual cows, and the mixing ratios of methane, nitrous oxide and carbon dioxide are measured continuously and simultaneously downwind by open path FTIR spectroscopy. Correlations between methane, nitrous oxide and carbon dioxide can be used to infer the herd-average methane flux directly. Measurements will be compared with the more conventional SF6 ruminal tracer technique.

  17. Aerobic biotransformation of polybrominated diphenyl ethers (PBDEs) by bacterial isolates.

    PubMed

    Robrock, Kristin R; Coelhan, Mehmet; Sedlak, David L; Alvarez-Cohent, Lisa

    2009-08-01

    Polybrominated diphenyl ethers (PBDEs) are flame retardants that have been used in consumer products and furniture for three decades. Currently, very little is known about their fate in the environment and specifically about their susceptibility to aerobic biotransformation. Here, we investigated the ability of the polychlorinated biphenyl (PCB) degrading bacteria Rhodococcus jostii RHA1 and Burkholderia xenovorans LB400 to transform mono- through hexa-BDEs at ppb levels. We also tested the PBDE transforming abilities of the related strain Rhodococcus sp. RR1 and the ether-degrading Pseudonocardia dioxanivorans CB1190. The two PCB-degrading strains transformed all of the mono- through penta-BDEs and strain LB400 transformed one of the hexa-BDEs. The extent of transformation was inversely proportional to the degree of bromination. Strains RR1 and CB1190 were only able to transform the less brominated mono- and di-BDE congeners. RHA1 released stoichiometric quantities of bromide while transforming mono- and tetra-BDE congeners. LB400 instead converted most of a mono-BDE to a hydroxylated mono-BDE. This is the first report of aerobic transformation of tetra-, penta,- and hexa-BDEs as well as the first report of stoichiometric release of bromide during PBDE transformation.

  18. Aerobic biotransformation of polybrominated diphenyl ethers (PBDEs) by bacterial isolates

    PubMed Central

    Robrock, Kristin R.; Coelhan, Mehmet; Sedlak, David; Alvarez-Cohen, Lisa

    2009-01-01

    Polybrominated diphenyl ethers (PBDEs) are flame retardants that have been used in consumer products and furniture for three decades. Currently, very little is known about their fate in the environment and specifically about their susceptibility to aerobic biotransformation. Here, we investigated the ability of the polychlorinated biphenyl (PCB) degrading bacteria Rhodococcus jostii RHA1 and Burkholderia xenovorans LB400 to transform mono- through hexa-BDEs at ppb levels. We also tested the PBDE transforming abilities of related strain Rhodococcus sp. RR1 and the ether-degrading Pseudonocardia dioxanivorans CB1190. The two PCB-degrading strains transformed all of the mono- through penta-BDEs and strain LB400 transformed one of the hexa-BDEs. The extent of transformation was inversely proportional to the degree of bromination. Strains RR1 and CB1190 were only able to transform the less brominated mono- and di- BDE congeners. RHA1 released stoichiometric quantities of bromide while transforming mono- and tetra-BDE congeners. LB400 instead converted most of a mono-BDE to a hydroxylated mono-BDE. This is the first report of aerobic transformation of tetra-, penta- and hexa-BDEs as well as the first report of stoichiometric release of bromide during PBDE transformation. PMID:19731666

  19. Methane emissions from natural wetlands

    SciTech Connect

    Meyer, J.L.; Burke, R.A. Jr.

    1993-09-01

    Analyses of air trapped in polar ice cores in conjunction with recent atmospheric measurements, indicate that the atmospheric methane concentration increased by about 250% during the past two or three hundred years (Rasmussen and Khalil, 1984). Because methane is a potent ``greenhouse`` gas, the increasing concentrations are expected to contribute to global warning (Dickinson and Cicerone, 1986). The timing of the methane increase suggests that it is related to the rapid growth of the human population and associated industrialization and agricultural development. The specific causes of the atmospheric methane concentration increase are not well known, but may relate to either increases in methane sources, decreases in the strengths of the sinks, or both.

  20. Direct Aromaization of Methane

    SciTech Connect

    George Marcelin

    1997-01-15

    The thermal decomposition of methane offers significant potential as a means of producing higher unsaturated and aromatic hydrocarbons when the extent of reaction is limited. Work in the literature previous to this project had shown that cooling the product and reacting gases as the reaction proceeds would significantly reduce or eliminate the formation of solid carbon or heavier (Clo+) materials. This project studied the effect and optimization of the quenching process as a means of increasing the amount of value added products during the pyrolysis of methane. A reactor was designed to rapidly quench the free-radical combustion reaction so as to maximize the yield of aromatics. The use of free-radical generators and catalysts were studied as a means of lowering the reaction temperature. A lower reaction temperature would have the benefits of more rapid quenching as well as a more feasible commercial process due to savings realized in energy and material of construction costs. It was the goal of the project to identify promising routes from methane to higher hydrocarbons based on the pyrolysis of methane.

  1. Methane Clathrate Hydrate Prospecting

    NASA Technical Reports Server (NTRS)

    Duxbury, N.; Romanovsky, V.

    2003-01-01

    A method of prospecting for methane has been devised. The impetus for this method lies in the abundance of CH4 and the growing shortages of other fuels. The method is intended especially to enable identification of subpermafrost locations where significant amounts of methane are trapped in the form of methane gas hydrate (CH4(raised dot)6H2O). It has been estimated by the U.S. Geological Survey that the total CH4 resource in CH4(raised dot) 6H2O exceeds the energy content of all other fossil fuels (oil, coal, and natural gas from non-hydrate sources). Also, CH4(raised dot)6H2O is among the cleanest-burning fuels, and CH4 is the most efficient fuel because the carbon in CH4 is in its most reduced state. The method involves looking for a proxy for methane gas hydrate, by means of the combination of a thermal-analysis submethod and a field submethod that does not involve drilling. The absence of drilling makes this method easier and less expensive, in comparison with prior methods of prospecting for oil and natural gas. The proposed method would include thermoprospecting in combination with one more of the other non-drilling measurement techniques, which could include magneto-telluric sounding and/or a subsurface-electrical-resistivity technique. The method would exploit the fact that the electrical conductivity in the underlying thawed region is greater than that in the overlying permafrost.

  2. Methane from shallow seep areas of the NW Svalbard Arctic margin does not reach the sea surface

    NASA Astrophysics Data System (ADS)

    Silyakova, Anna; Greinert, Jens; Jansson, Pär; Ferré, Bénédicte

    2015-04-01

    Methane, an important greenhouse gas, leaks from large areas of the Arctic Ocean floor. One overall question is how much methane passes from the seabed through the water column, potentially reaching the atmosphere. Transport of methane from the ocean floor into and through the water column depends on many factors such as distribution of gas seeps, microbial methane oxidation, and ambient oceanographic conditions, which may trigger a change in seep activity. From June-July 2014 we investigated dissolved methane in the water column emanating from the "Prins Karls Forland seeps" area offshore the NW Svalbard Arctic margin. Measurements of the spatial variability of dissolved methane in the water column included 65 CTD stations located in a grid covering an area of 30 by 15 km. We repeated an oceanographic transect twice in a week for time lapse studies, thus documenting significant temporal variability in dissolved methane above one shallow seep site (~100 m water depth). Analysis of both nutrient concentrations and dissolved methane in water samples from the same transect, reveal striking similarities in spatial patterns of both dissolved methane and nutrients indicating that microbial community is involved in methane cycling above the gas seepage. Our preliminary results suggest that although methane release can increase in a week's time, providing twice as much dissolved gas to the water column, no methane from a seep reaches the sea surface. Instead it spreads horizontally under the pycnocline. Yet microbial communities react rapidly to the methane supply above gas seepage areas and may also have an important role as an effective filter, hindering methane release from the ocean to the atmosphere during rapid methane ebullition. This study is funded by CAGE (Centre for Arctic Gas Hydrate, Environment and Climate), Norwegian Research Council grant no. 223259.

  3. Fit women are not able to use the whole aerobic capacity during aerobic dance.

    PubMed

    Edvardsen, Elisabeth; Ingjer, Frank; Bø, Kari

    2011-12-01

    Edvardsen, E, Ingjer, F, and Bø, K. Fit women are not able to use the whole aerobic capacity during aerobic dance. J Strength Cond Res 25(12): 3479-3485, 2011-This study compared the aerobic capacity during maximal aerobic dance and treadmill running in fit women. Thirteen well-trained female aerobic dance instructors aged 30 ± 8.17 years (mean ± SD) exercised to exhaustion by running on a treadmill for measurement of maximal oxygen uptake (VO(2)max) and peak heart rate (HRpeak). Additionally, all subjects performed aerobic dancing until exhaustion after a choreographed videotaped routine trying to reach the same HRpeak as during maximal running. The p value for statistical significance between running and aerobic dance was set to ≤0.05. The results (mean ± SD) showed a lower VO(2)max in aerobic dance (52.2 ± 4.02 ml·kg·min) compared with treadmill running (55.9 ± 5.03 ml·kg·min) (p = 0.0003). Further, the mean ± SD HRpeak was 182 ± 9.15 b·min in aerobic dance and 192 ± 9.62 b·min in treadmill running, giving no difference in oxygen pulse between the 2 exercise forms (p = 0.32). There was no difference in peak ventilation (aerobic dance: 108 ± 10.81 L·min vs. running: 113 ± 11.49 L·min). In conclusion, aerobic dance does not seem to be able to use the whole aerobic capacity as in running. For well endurance-trained women, this may result in a lower total workload at maximal intensities. Aerobic dance may therefore not be as suitable as running during maximal intensities in well-trained females.

  4. Formation of methane nano-bubbles during hydrate decomposition and their effect on hydrate growth.

    PubMed

    Bagherzadeh, S Alireza; Alavi, Saman; Ripmeester, John; Englezos, Peter

    2015-06-01

    Molecular dynamic simulations are performed to study the conditions for methane nano-bubble formation during methane hydrate dissociation in the presence of water and a methane gas reservoir. Hydrate dissociation leads to the quick release of methane into the liquid phase which can cause methane supersaturation. If the diffusion of methane molecules out of the liquid phase is not fast enough, the methane molecules agglomerate and form bubbles. Under the conditions of our simulations, the methane-rich quasi-spherical bubbles grow to become cylindrical with a radius of ∼11 Å. The nano-bubbles remain stable for about 35 ns until they are gradually and homogeneously dispersed in the liquid phase and finally enter the gas phase reservoirs initially set up in the simulation box. We determined that the minimum mole fraction for the dissolved methane in water to form nano-bubbles is 0.044, corresponding to about 30% of hydrate phase composition (0.148). The importance of nano-bubble formation to the mechanism of methane hydrate formation, growth, and dissociation is discussed.

  5. Did geologic emissions of methane play any role in Quaternary climate change?

    NASA Astrophysics Data System (ADS)

    Etiope, Giuseppe; Milkov, Alexei V.; Derbyshire, Edward

    2008-03-01

    The "methane-led hypotheses" assume that gas hydrates and marine seeps are the sole geologic factors controlling Quaternary atmospheric and climate changes. Nevertheless, a wider class of geologic sources of methane exist which could have played a role in past climate changes. Beyond offshore seepage, relevant geologic emissions of methane (GEM) are from onshore seepage, including mud volcanism, microseepage and geothermal flux; altogether GEM are the second most important natural source of atmospheric methane at present. The amount of methane entering the atmosphere from onshore GEM seems to prevail on that from offshore seepage. Onshore sources inject a predominantly isotopically heavy ( 13C-enriched) methane into the atmosphere. They are controlled mainly by endogenic (geodynamic) processes, which induce large-scale gas flow variations over geologic and millennial time scales, and only partially by exogenic (surface) conditions, so that they are not affected by negative feedbacks. The eventual influence on atmospheric methane concentration does not necessarily require catastrophic or abrupt releases, as proposed for the "clathrate gun hypothesis". Enhanced degassing from these sources could have contributed to the methane trends observed in the ice core records, and could explain the late Quaternary peaks of increased methane concentrations accompanied by the enrichment of isotopically heavy methane, as recently observed. This hypothesis shall be tested by means of robust multidisciplinary studies, mainly based on a series of atmospheric, biologic and geologic proxies.

  6. Methane capture from livestock manure.

    PubMed

    Tauseef, S M; Premalatha, M; Abbasi, Tasneem; Abbasi, S A

    2013-03-15

    It has been estimated that livestock manure contributes about 240 million metric tons of carbon dioxide equivalent of methane to the atmosphere and represents one of the biggest anthropogenic sources of methane. Considering that methane is the second biggest contributor to global warming after carbon dioxide, it is imperative that ways and means are developed to capture as much of the anthropogenic methane as possible. There is a major associated advantage of methane capture: its use as a source of energy which is comparable in 'cleanness' to natural gas. The present review dwells upon the traditional ways of methane capture used in India, China, and other developing countries for providing energy to the rural poor. It then reviews the present status of methane capture from livestock manure in developed countries and touches upon the prevalent trends.

  7. Future methane emissions from animals

    SciTech Connect

    Anastasi, C.; Simpson, V.J. )

    1993-04-20

    The authors project future methane emissions from animals to the year 2025. They review the present estimated sources of methane from enteric fermentation in animals. Ruminant animals produce the highest concentrations of methane. Methane is a byproduct of anaerobic breakdown of carbohydrates by microbes in the digestive tract of herbatious animals. In general the methane production depends on the variety of animal, the quality of the feed, and the feeding level. Since cattle, sheep, and buffalo account for roughly 91% of all animal methane emission, they only study these animals in detail. Results suggest a rise in methane production of roughly 1% per year averaged through 2025. Increasing levels are found to originate from developed countries even though the feedstock levels are lower.

  8. Methane Emissions from Woody Stems of Tropical and Temperate Wetland Trees

    NASA Astrophysics Data System (ADS)

    Pangala, S. R.; Hornibrook, E. R.; Gowing, D. J.; Bastviken, D.; Enrich-Prast, A.; Gauci, V.

    2013-12-01

    Wetland-adapted trees are known to transport and release soil-produced methane to the atmosphere through woody stem surfaces, yet the magnitude and controls of tree-mediated methane emissions remain unknown for mature forests. Although 60% of global wetlands are forested, and many tropical forests are either permanently or seasonally flooded, the ecosystem level contribution of tree-mediated methane flux relative to other gas transport pathways (e.g., ebullition, pore-water diffusion and via aerenchyma of herbaceous plants) has received limited attention. The role of trees as a conduit for methane export from soil to the atmosphere was assessed in situ in a temperate forested wetland (Flitwick Moor, UK) and tropical forested wetlands in Borneo, Indonesia and Amazonia, Brazil. Mesocosm experiments also were conducted in the temperate region to characterise emission characteristics of Alnus glutinosa saplings subjected to different water-table treatments. Methane emissions from trees were compared to fluxes from the soil surface in both the in situ and mesocosm studies. Temperate and tropical tree species both released significant quantities of methane from stem surfaces. Emission rates for young trees exceeded that of mature trees by several orders of magnitude on a stem surface area basis. Key factors controlling rates of tree-mediated flux were tree physiology (e.g., wood specific density, stem lenticel density), abiotic conditions (e.g., soil temperature) and methane gas transport mechanisms (e.g., passive diffusion, convective transport). Tree-mediated methane emissions contributed 6 to 87% of total ecosystem methane flux with the largest relative contribution from trees occurring in tropical wetlands. Recent data from Amazonian wetlands demonstrate very high rates of tree-mediated methane emission relative to other types of forested wetlands. These results indicate that exclusion of tree-mediated methane fluxes from measurement campaigns conducted in forested

  9. Carbon Isotopic Constraints on Arctic Methane Sources, 2008-2010

    NASA Astrophysics Data System (ADS)

    Fisher, R. E.; Lowry, D.; Lanoiselle, M.; Sriskantharajah, S.; Nisbet, E. G.

    2010-12-01

    Arctic methane source strengths are particularly vulnerable to large changes with year-to year meteorological variations and with climatic change. A global increase in methane seen in 2007 (Dlugokencky et al., 2009) may have been in part be due to elevated wetland emissions caused by a warm, wet summer over large parts of Siberia. In 2010 wildfires over large areas of Russia will have added methane to the Arctic atmosphere. Carbon isotopic composition of methane in air from the Arctic arriving at a measurement station can be used to identify sources of the gas. Measurement of methane δ13C in air close to sources, including wetlands, permafrost, pine forest and submarine methane clathrate has extended the available data of source signatures of methane from northern sources. Keeling plot analysis of diurnal records from field campaigns in Arctic wetlands show that bulk wetland methane emissions are typically close to δ13CCH4 -69±1 ‰. Air samples from Zeppelin (Spitsbergen, Norway), Pallas (Finland) and Barra (Outer Hebrides, Scotland) have been regularly analysed for methane δ13C. Summer campaigns at Zeppelin point to a 13C depleted bulk Arctic source of dominantly biogenic origin, at -67‰. In spring, while the wetlands are still frozen, the source signature is more enriched, -53‰, with trajectory analysis implying a large contribution from onshore gas fields. Arctic methane emissions respond rapidly to warming with strong positive feedbacks. With rapid warming there is the potential to release large stores of carbon from permafrost and methane hydrates. Isotopic data are powerful discriminants of sources. High frequency, ideally continuous, monitoring of methane δ13C from a number of Arctic sites, onshore and offshore, coupled with back-trajectory analysis and regional modelling, will be important if future changes in Arctic source strengths are to be quantified. Reference: Dlugokencky, E. J., et al. (2009), Observational constraints on recent increases

  10. Experimental study on combustion of a methane hydrate sphere

    NASA Astrophysics Data System (ADS)

    Yoshioka, Tomoki; Yamamoto, Yuji; Yokomori, Takeshi; Ohmura, Ryo; Ueda, Toshihisa

    2015-10-01

    The combustion behavior of a methane hydrate sphere under normal gravity is experimentally investigated. The initial diameter of the sphere is 20 mm. Variation in temperature at the center of the sphere ( T c) is measured with a K-type thermocouple at ignition temperatures ( T c,i) from 193 to 253 K at 20 K intervals. Variation in the near-surface temperature of the sphere ( T s) is measured at ignition temperatures ( T s,i) from 233 to 263 K at 10 K intervals. Two combustion phases are observed. When the hydrate is ignited, a stable flame envelope is formed around the sphere (phase 1). In phase 1, the surface of the sphere is dry. After a few seconds, water formed by dissociation of the methane hydrate appears on the surface and methane bubbles are formed by methane ejected from inside the sphere (phase 2), thus destabilizing the flame and causing local extinction. Methane bubbles move down along the surface and merge into a large methane bubble at the bottom of the sphere. This bubble bursts, releasing methane to form a temporary flame, and the water drops from the hydrate sphere. Water on the surface is cooled by the hydrate inside, and an ice shell confines the methane gas that dissociated inside the sphere. Because the dissociation occurs continuously inside the hydrate, the inner pressure gradually increases and at some instant, the ice cracks and methane gas is ejected from the cracks, which results in a micro-explosion with a flame. In phase 1, the surface temperature is below the freezing point of water, and so the surface remains dry and a stable flame envelope is formed; in phase 2, the surface temperature is above the freezing point, and so water appears on the surface. When the temperature at the center of the sphere is lower (193, 213, or 233 K), some methane hydrate remains even after flame extinction because heat transfer from the flame decreases in phase 2 as a result of local extinction. The diameter of the sphere decreases during combustion in

  11. Methane Production by Microbial Mats Under Low Sulfate Concentrations

    NASA Technical Reports Server (NTRS)

    Bebout, Brad M.; Hoehler, Tori M.; Thamdrup, Bo; Albert, Dan; Carpenter, Steven P.; Hogan, Mary; Turk, Kendra; DesMarais, David J.

    2003-01-01

    Cyanobacterial mats collected in hypersaline salterns were incubated in a greenhouse under low sulfate concentrations ([SO4]) and examined for their primary productivity and emissions of methane and other major carbon species. Atmospheric greenhouse warming by gases such as carbon dioxide and methane must have been greater during the Archean than today in order to account for a record of moderate to warm paleoclemates, despite a less luminous early sun. It has been suggested that decreased levels of oxygen and sulfate in Archean oceans could have significantly stimulated microbial methanogenesis relative to present marine rates, with a resultant increase in the relative importance of methane in maintaining the early greenhouse. We maintained modern microbial mats, models of ancient coastal marine communities, in artificial brine mixtures containing both modern [SO4=] (ca. 70 mM) and "Archean" [SO4] (less than 0.2 mM). At low [SO4], primary production in the mats was essentially unaffected, while rates of sulfate reduction decreased by a factor of three, and methane fluxes increased by up to ten-fold. However, remineralization by methanogenesis still amounted to less than 0.4 % of the total carbon released by the mats. The relatively low efficiency of conversion of photosynthate to methane is suggested to reflect the particular geometry and chemical microenvironment of hypersaline cyanobacterial mats. Therefore, such mats w-ere probably relatively weak net sources of methane throughout their 3.5 Ga history, even during periods of low- environmental levels oxygen and sulfate.

  12. Nitrogen oxides and methane treatment by non-thermal plasma

    NASA Astrophysics Data System (ADS)

    Alva, E.; Pacheco, M.; Colín, A.; Sánchez, V.; Pacheco, J.; Valdivia, R.; Soria, G.

    2015-03-01

    Non thermal plasma was used to treat nitrogen oxides (NOx) and methane (CH4), since they are important constituents of hydrocarbon combustion emissions processes and, both gases, play a key role in the formation of tropospheric ozone. These gases are involved in environmental problems like acid rain and some diseases such as bronchitis and pneumonia. In the case of methane is widely known its importance in the global climate change, and currently accounts for 30% of global warming. There is a growing concern for methane leaks, associated with a rapid expansion of unconventional oil and gas extraction techniques as well as a large-scale methane release from Arctic because of ice melting and the subsequent methane production of decaying organic matter. Therefore, methane mitigation is a key to avoid dangerous levels of global warming. The research, here reported, deals about the generation of non-thermal plasma with a double dielectric barrier (2DBD) at atmospheric pressure with alternating current (AC) for NOx and CH4 treatment. The degradation efficiencies and their respective power consumption for different reactor configurations (cylindrical and planar) are also reported. Qualitative and quantitative analysis of gases degradation are reported before and after treatment with cold plasma. Experimental and theoretical results are compared obtaining good removal efficiencies, superior to 90% and to 20% respectively for NOx and CH4.

  13. Overestimating climate warming-induced methane gas escape from the seafloor by neglecting multiphase flow dynamics

    NASA Astrophysics Data System (ADS)

    Stranne, C.; O'Regan, M.; Jakobsson, M.

    2016-08-01

    Continental margins host large quantities of methane stored partly as hydrates in sediments. Release of methane through hydrate dissociation is implicated as a possible feedback mechanism to climate change. Large-scale estimates of future warming-induced methane release are commonly based on a hydrate stability approach that omits dynamic processes. Here we use the multiphase flow model TOUGH + hydrate (T + H) to quantitatively investigate how dynamic processes affect dissociation rates and methane release. The simulations involve shallow, 20-100 m thick hydrate deposits, forced by a bottom water temperature increase of 0.03°C yr-1 over 100 years. We show that on a centennial time scale, the hydrate stability approach can overestimate gas escape quantities by orders of magnitude. Our results indicate a time lag of > 40 years between the onset of warming and gas escape, meaning that recent climate warming may soon be manifested as widespread gas seepages along the world's continental margins.

  14. Recent findings on methane emissions from vegetation (Invited)

    NASA Astrophysics Data System (ADS)

    Keppler, F.; Roeckmann, T.; Vigano, I.; Hamilton, J. T.; McLeod, A.

    2009-12-01

    Three years ago, Keppler et al. (2006) reported from laboratory experiments that living plants, plant litter and the structural plant component pectin emit methane to the atmosphere under aerobic conditions. These observations caused considerable controversy amongst the scientific community and the general public because of their far-reaching implications for two main reasons. Firstly, it is generally accepted knowledge that the reduced compound methane can only be produced naturally from organic matter by methanogens in the absence of oxygen, or at high temperatures, e.g. in biomass burning. The fact that no mechanism for ‘aerobic’ production of methane had been identified at the molecular level in plants added to the consternation. Secondly, the first extrapolations from laboratory measurements to the global scale indicated that these emissions could constitute a substantial fraction of the total global emissions of methane. After publication of the findings of Keppler et al. (2006), their extrapolation procedure employed was severely criticised, and other up-scaling calculations suggested much lower methane emissions. However, it became clear, that without further insight into the mechanism of the ‘aerobic’ production of methane, any up-scaling approach would have considerable uncertainties and thus be of questionable value. Whilst several subsequent studies (e.g. Dueck et al., 2007, Nisbet et al., 2009) could not confirm the original findings of Keppler et al. (2006) others (e.g. McLeod et al., 2008) including stable isotope studies (e.g. Vigano et al., 2009) verified methane formation from both dead plant tissues and living intact plants (Brüggemann et al. 2009).Therefore, the principle scientific questions are now: if, by how much, and by what mechanisms is methane emitted from dead plant matter and living vegetation. An overview of the current state of knowledge and the most recent findings will be presented. References: Brüggemann N, et al. (2009

  15. Effect Of Imposed Anaerobic Conditions On Metals Release From Acid-Mine Drainage Contaminated Streambed Sediments

    EPA Science Inventory

    Remediation of streams influenced by mine-drainage may require removal and burial of metal-containing bed sediments. Burial of aerobic sediments into an anaerobic environment may release metals, such as through reductive dissolution of metal oxyhydroxides. Mining-impacted aerob...

  16. Methane Fluxes to the Atmosphere from Perennial Hydrocarbon Plumes in the Northern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Solomon, E.; Kastner, M.; MacDonald, I.

    2006-12-01

    isotopic fractionation factor of 1.025 for aerobic methane oxidation and the δ13C-CH4 of the bottom waters, only 3-12% of the methane is oxidized in the water column. As a result, plume methane concentrations in the mixed layer are highly enriched with respect to seawater in equilibrium with air, and are 28 to 940 times supersaturated. The average wind speed in 2002 and 2003 at the study sites was 5.82 m/s. From this speed we compute minimum and maximum methane fluxes from the mixed layer to the atmosphere of 0.183 and 16.4 mmol/m2d, respectively. These are diffusive flux estimates based on mixed layer methane concentrations and do not take into account the advective flux of oil coated gas bubbles reaching the sea surface, thus are minimum methane inputs to the atmosphere from the hydrocarbon plumes. The northwestern GOM continental slope between Louisiana and Texas, ~8% of the total surface area of the GOM, contains an estimated 59,000 km2 of gas hydrate deposits and over 300 perennial hydrocarbon seeps. Extrapolating the minimum fluxes obtained at the 6 plumes examined in this study to the area occupied by gas hydrate deposits in the NW GOM yields methane fluxes ranging from 0.063 to 5.7 Tg CH4/yr. The estimated flux out of the NW GOM alone is ~50% of the global oceanic flux of 10 Tg CH4/yr. The resulting methane fluxes attained from this novel sampling method suggests hydrocarbon seeps in the GOM and similar seeps in other oil-rich regions are globally significant sources of 14C- depleted methane to the atmosphere that should be considered in the global methane budget.

  17. Large-scale simulation of methane dissociation along the West Spitzbergen Margin

    SciTech Connect

    Reagan, M.T.; Moridis, G.J.

    2009-07-15

    Vast quantities of methane are trapped in oceanic hydrate deposits, and there is concern that a rise in the ocean temperature will induce dissociation of these hydrate accumulations, potentially releasing large amounts of methane into the atmosphere. The recent discovery of active methane gas venting along the landward limit of the gas hydrate stability zone (GHSZ) on the shallow continental slope west of Spitsbergen could be an indication of this process, if the source of the methane can be confidently attributed to dissociating hydrates. In the first large-scale simulation study of its kind, we simulate shallow hydrate dissociation in conditions representative of the West Spitsbergen margin to test the hypothesis that the observed gas release originated from hydrates. The simulation results are consistent with this hypothesis, and are in remarkable agreement with the recently published observations. They show that shallow, low-saturation hydrate deposits, when subjected to temperature increases at the seafloor, can release significant quantities of methane, and that the releases will be localized near the landward limit of the top of the GHSZ. These results indicate the possibility that hydrate dissociation and methane release may be both a consequence and a cause of climate change.

  18. Comparison of Leachate Quality from Aerobic and Anaerobic Municipal Solid Waste Bioreactors

    NASA Astrophysics Data System (ADS)

    Borglin, S. E.; Hazen, T. C.; Oldenburg, C. M.

    2002-12-01

    Municipal solid waste landfills are becoming a drain on the resources of local municipalities as the requirements for stabilization and containment become increasingly stringent. Current regulations limit the moisture in the landfill to minimize leachate production and lower the potential for release of leachate to the environment. Recent research has shown that addition and recycling of moisture in the waste optimizes the biodegradation of stabilization and also provides a means for leachate treatment. This study compares the characteristics of leachate produced from aerobic and anaerobic laboratory bioreactors, and leachate collected from a full-scale anaerobic bioreactor. The laboratory reactors consisted of 200-liter tanks filled with fresh waste materials with the following conditions: (a) aerobic (air injection with leachate recirculation), (b) anaerobic (leachate recirculation). The leachate from the reactors was monitored for metals, nutrients, organic carbon, and microbiological activity for up to 500 days. Leachate from the aerobic tank had significantly lower concentrations of all potential contaminants, both organic and metal, after only a few weeks of operation. Metals leaching was low throughout the test period for the aerobic tanks, and decreased over time for the anaerobic tanks. Organic carbon as measured by BOD, COD, TOC, and COD were an order of magnitude higher in the leachate from the anaerobic system. Microbiological assessment by lipid analysis, enzyme activity assays, and cell counts showed high biomass and diversity in both the aerobic and anaerobic bioreactors, with higher activity in the anaerobic leachate. Results from the full-scale anaerobic bioreactor were not significantly different from those of the laboratory anaerobic bioreactor. The reduction in noxious odors was a significant advantage of the aerobic system. These results suggest that aerobic management of landfills could reduce or eliminate the need for leachate treatment

  19. The Energetics of Aerobic versus Anaerobic Respiration.

    ERIC Educational Resources Information Center

    Champion, Timothy D.; Schwenz, Richard W.

    1990-01-01

    Background information, laboratory procedures, and a discussion of the results of an experiment designed to investigate the difference in energy gained from the aerobic and anaerobic oxidation of glucose are presented. Sample experimental and calculated data are included. (CW)

  20. Neuromodulation of Aerobic Exercise—A Review

    PubMed Central

    Heijnen, Saskia; Hommel, Bernhard; Kibele, Armin; Colzato, Lorenza S.

    2016-01-01

    Running, and aerobic exercise in general, is a physical activity that increasingly many people engage in but that also has become popular as a topic for scientific research. Here we review the available studies investigating whether and to which degree aerobic exercise modulates hormones, amino acids, and neurotransmitters levels. In general, it seems that factors such as genes, gender, training status, and hormonal status need to be taken into account to gain a better understanding of the neuromodular underpinnings of aerobic exercise. More research using longitudinal studies and considering individual differences is necessary to determine actual benefits. We suggest that, in order to succeed, aerobic exercise programs should include optimal periodization, prevent overtraining and be tailored to interindividual differences, including neuro-developmental and genetically-based factors. PMID:26779053

  1. Neuromodulation of Aerobic Exercise-A Review.

    PubMed

    Heijnen, Saskia; Hommel, Bernhard; Kibele, Armin; Colzato, Lorenza S

    2015-01-01

    Running, and aerobic exercise in general, is a physical activity that increasingly many people engage in but that also has become popular as a topic for scientific research. Here we review the available studies investigating whether and to which degree aerobic exercise modulates hormones, amino acids, and neurotransmitters levels. In general, it seems that factors such as genes, gender, training status, and hormonal status need to be taken into account to gain a better understanding of the neuromodular underpinnings of aerobic exercise. More research using longitudinal studies and considering individual differences is necessary to determine actual benefits. We suggest that, in order to succeed, aerobic exercise programs should include optimal periodization, prevent overtraining and be tailored to interindividual differences, including neuro-developmental and genetically-based factors. PMID:26779053

  2. Conditioning and Aerobics for Older Americans.

    ERIC Educational Resources Information Center

    Hansen, Joyce

    1980-01-01

    A class designed for the maintenance and gradual improvement of senior citizens' physical fitness includes relaxation training, flexibility and stretching exercises, interval training activities (designed as a link between less strenuous exercise and more strenuous activities), and aerobic exercises. (CJ)

  3. Microbial Removal of Atmospheric Carbon Tetrachloride in Bulk Aerobic Soils▿

    PubMed Central

    Mendoza, Y.; Goodwin, K. D.; Happell, J. D.

    2011-01-01

    Atmospheric concentrations of carbon tetrachloride (CCl4) were removed by bulk aerobic soils from tropical, subtropical, and boreal environments. Removal was observed in all tested soil types, indicating that the process was widespread. The flux measured in field chamber experiments was 0.24 ± 0.10 nmol CCl4 (m2 day)−1 (average ± standard deviation [SD]; n = 282). Removal of CCl4 and removal of methane (CH4) were compared to explore whether the two processes were linked. Removal of both gases was halted in laboratory samples that were autoclaved, dry heated, or incubated in the presence of mercuric chloride (HgCl2). In marl soils, treatment with antibiotics such as tetracycline and streptomycin caused partial inhibition of CCl4 (50%) and CH4 (76%) removal, but removal was not affected in soils treated with nystatin or myxothiazol. These data indicated that bacteria contributed to the soil removal of CCl4 and that microeukaryotes may not have played a significant role. Amendments of methanol, acetate, and succinate to soil samples enhanced CCl4 removal by 59%, 293%, and 72%, respectively. Additions of a variety of inhibitors and substrates indicated that nitrification, methanogenesis, or biological reduction of nitrate, nitrous oxide, or sulfate (e.g., occurring in possible anoxic microzones) did not play a significant role in the removal of CCl4. Methyl fluoride inhibited removal of CH4 but not CCl4, indicating that CH4 and CCl4 removals were not directly linked. Furthermore, CCl4 removal was not affected in soils amended with copper sulfate or methane, supporting the results with MeF and suggesting that the observed CCl4 removal was not significantly mediated by methanotrophs. PMID:21724884

  4. Microbial removal of atmospheric carbon tetrachloride in bulk aerobic soils.

    PubMed

    Mendoza, Y; Goodwin, K D; Happell, J D

    2011-09-01

    Atmospheric concentrations of carbon tetrachloride (CCl(4)) were removed by bulk aerobic soils from tropical, subtropical, and boreal environments. Removal was observed in all tested soil types, indicating that the process was widespread. The flux measured in field chamber experiments was 0.24 ± 0.10 nmol CCl(4) (m(2) day)(-1) (average ± standard deviation [SD]; n = 282). Removal of CCl(4) and removal of methane (CH(4)) were compared to explore whether the two processes were linked. Removal of both gases was halted in laboratory samples that were autoclaved, dry heated, or incubated in the presence of mercuric chloride (HgCl(2)). In marl soils, treatment with antibiotics such as tetracycline and streptomycin caused partial inhibition of CCl(4) (50%) and CH(4) (76%) removal, but removal was not affected in soils treated with nystatin or myxothiazol. These data indicated that bacteria contributed to the soil removal of CCl(4) and that microeukaryotes may not have played a significant role. Amendments of methanol, acetate, and succinate to soil samples enhanced CCl(4) removal by 59%, 293%, and 72%, respectively. Additions of a variety of inhibitors and substrates indicated that nitrification, methanogenesis, or biological reduction of nitrate, nitrous oxide, or sulfate (e.g., occurring in possible anoxic microzones) did not play a significant role in the removal of CCl(4). Methyl fluoride inhibited removal of CH(4) but not CCl(4), indicating that CH(4) and CCl(4) removals were not directly linked. Furthermore, CCl(4) removal was not affected in soils amended with copper sulfate or methane, supporting the results with MeF and suggesting that the observed CCl(4) removal was not significantly mediated by methanotrophs.

  5. Methane cycling. Nonequilibrium clumped isotope signals in microbial methane.

    PubMed

    Wang, David T; Gruen, Danielle S; Lollar, Barbara Sherwood; Hinrichs, Kai-Uwe; Stewart, Lucy C; Holden, James F; Hristov, Alexander N; Pohlman, John W; Morrill, Penny L; Könneke, Martin; Delwiche, Kyle B; Reeves, Eoghan P; Sutcliffe, Chelsea N; Ritter, Daniel J; Seewald, Jeffrey S; McIntosh, Jennifer C; Hemond, Harold F; Kubo, Michael D; Cardace, Dawn; Hoehler, Tori M; Ono, Shuhei

    2015-04-24

    Methane is a key component in the global carbon cycle, with a wide range of anthropogenic and natural sources. Although isotopic compositions of methane have traditionally aided source identification, the abundance of its multiply substituted "clumped" isotopologues (for example, (13)CH3D) has recently emerged as a proxy for determining methane-formation temperatures. However, the effect of biological processes on methane's clumped isotopologue signature is poorly constrained. We show that methanogenesis proceeding at relatively high rates in cattle, surface environments, and laboratory cultures exerts kinetic control on (13)CH3D abundances and results in anomalously elevated formation-temperature estimates. We demonstrate quantitatively that H2 availability accounts for this effect. Clumped methane thermometry can therefore provide constraints on the generation of methane in diverse settings, including continental serpentinization sites and ancient, deep groundwaters. PMID:25745067

  6. The Airborne Measurements of Methane Fluxes (AIRMETH) Arctic Campaign (Invited)

    NASA Astrophysics Data System (ADS)

    Serafimovich, A.; Metzger, S.; Hartmann, J.; Kohnert, K.; Sachs, T.

    2013-12-01

    One of the most pressing questions with regard to climate feedback processes in a warming Arctic is the regional-scale methane release from Arctic permafrost areas. The Airborne Measurements of Methane Fluxes (AIRMETH) campaign is designed to quantitatively and spatially explicitly address this question. Ground-based eddy covariance (EC) measurements provide continuous in-situ observations of the surface-atmosphere exchange of methane. However, these observations are rare in the Arctic permafrost zone and site selection is bound by logistical constraints among others. Consequently, these observations cover only small areas that are not necessarily representative of the region of interest. Airborne measurements can overcome this limitation by covering distances of hundreds of kilometers over time periods of a few hours. Here, we present the potential of environmental response functions (ERFs) for quantitatively linking methane flux observations in the atmospheric surface layer to meteorological and biophysical drivers in the flux footprints. For this purpose thousands of kilometers of AIRMETH data across the Alaskan North Slope are utilized, with the aim to extrapolate the airborne EC methane flux observations to the entire North Slope. The data were collected aboard the research aircraft POLAR 5, using its turbulence nose boom and fast response methane and meteorological sensors. After thorough data pre-processing, Reynolds averaging is used to derive spatially integrated fluxes. To increase spatial resolution and to derive ERFs, we then use wavelet transforms of the original high-frequency data. This enables much improved spatial discretization of the flux observations, and the quantification of continuous and biophysically relevant land cover properties in the flux footprint of each observation. A machine learning technique is then employed to extract and quantify the functional relationships between the methane flux observations and the meteorological and

  7. Capacity for biodegradation of CFCs and HCFCs in a methane oxidative counter-gradient laboratory system simulating landfill soil covers.

    PubMed

    Scheutz, Charlotte; Kjeldsen, Peter

    2003-11-15

    The attenuation of methane and four chlorofluorocarbons was investigated in a dynamic methane and oxygen counter-gradient system simulating a landfill soil cover. Soil was sampled at Skellingsted Landfill, Denmark. The soil columns showed a high capacity of methane oxidation with oxidation rates of 210 g m(-2) d(-1) corresponding to a removal efficiency of 81%. CFC-11 and to a lesser extent also CFC-12 were degraded in the active soil columns. The average removal efficiency was 90% and 30% for CFC-11 and CFC-12, respectively. Soil gas concentration profiles indicated that the removal was due to anaerobic degradation, which was verified in anaerobic batch experiments where CFC-11 was rapidly degraded. HCFC-21 and HCFC-22 were also degraded in active soil columns (61% and 41%, respectively), but compared to the CFCs, the degradation was located in the upper oxic part of the column with overlapping gradients of methane and oxygen. High oxidation rates of methane and HCFCs were obtained in soil microcosms incubated with methane. When increasing the column inlet flow, the oxidation zone was moved upward in the column, and the removal efficiency of methane and HCFCs decreased. The removal of CFCs was, however, less affected since the anaerobic zone expanded with increasing inlet flow rates. This study demonstrates the complexity of landfill soil cover systems and shows that both anaerobic and aerobic bacteria may play a very important role in reducing the emission of not only methane but also trace components into the atmosphere. PMID:14655700

  8. Project identification for methane reduction options

    SciTech Connect

    Kerr, T.

    1996-12-31

    This paper discusses efforts directed at reduction in emission of methane to the atmosphere. Methane is a potent greenhouse gas, which on a 20 year timeframe may present a similar problem to carbon dioxide. In addition, methane causes additional problems in the form of smog and its longer atmospheric lifetime. The author discusses strategies for reducing methane emission from several major sources. This includes landfill methane recovery, coalbed methane recovery, livestock methane reduction - in the form of ruminant methane reduction and manure methane recovery. The author presents examples of projects which have implemented these ideas, the economics of the projects, and additional gains which come from the projects.

  9. Role of microorganisms for cycling of atmospheric constituents, emphasizing the greenhouse gas methane (Invited)

    NASA Astrophysics Data System (ADS)

    Conrad, R.

    2013-12-01

    Microorganisms have contributed significantly to the formation of the atmosphere and the habitability of Earth. Microbial methanogenesis probably helped overcoming the faint sun problem on young Earth. Later on, cyanobacterial photosynthesis produced oxygen and thus restricted the life zone of methanogenic microbial communities, which nowadays contribute only about 1% to total carbon cycle. Nevertheless, methanogenesis still dominates the budget of atmospheric methane and contributes significantly to the greenhouse effect. There are numerous habitats, which exchange methane with the atmosphere, and even more in which methane is intensively cycled albeit little emitted. Methane can be a byproduct of chemical reactions in plant leaves, or of aerobic methyl phosphonate consumption in ocean water. Most commonly, however, methane is a stoichiometric catabolic product in the degradation of organic matter by anaerobic microorganisms. The degradation is achieved by a complex microbial community consisting of various species of hydrolytic and fermentative Bacteria that produce hydrogen, carbon dioxide and acetate as major end products, and of methanogenic Archaea that eventually convert these compounds to methane and carbon dioxide. The composition of such methanogenic microbial communities, the rates and paths of methane formation, and the isotopic composition of the produced methane all exhibit quite some variability across the different habitats in which methane is produced from organic matter decomposition, such as flooded soils, lake sediments, peatlands, animal gut systems. The structure of the microbial communities often strongly affects their function. It is a challenging task to understand the environmental and biochemical basis of the interactions of abiotic factors and microorganisms shaping the structure and function of the microbial communities in the different methanogenic habitats.

  10. Methane from acetate.

    PubMed

    Ferry, J G

    1992-09-01

    The general features are known for the pathway by which most methane is produced in nature. All acetate-utilizing methanogenic microorganisms contain CODH which catalyzes the cleavage of acetyl-CoA; however, the pathway differs from all other acetate-utilizing anaerobes in that the methyl group is reduced to methane with electrons derived from oxidation of the carbonyl group of acetyl-CoA to CO2. The current understanding of the methanogenic fermentation of acetate provides impressions of nature's novel solutions to problems of methyl transfer, electron transport, and energy conservation. The pathway is now at a level of understanding that will permit productive investigations of these and other interesting questions in the near future. PMID:1512186

  11. Separation of swine wastewater into different concentration fractions and its contribution to combined anaerobic-aerobic process.

    PubMed

    Yang, Di; Deng, Liangwei; Zheng, Dan; Wang, Lan; Liu, Yi

    2016-03-01

    There are two problems associated with treatment of swine wastewater, low efficiency of anaerobic digestion during winter and poor performance for aerobic treatment of digested effluent. A strategy employing unbalanced distributions of the pollutant mass and wastewater volumes in anaerobic and aerobic units was proposed. To accomplish this, swine wastewater was separated into high content liquid (HCL) and low content liquid (LCL). Three separation ratios of HCL to LCL (v/v), 1:9 (S1), 2:8 (S2), and 3:7 (S3), were evaluated. Anaerobically digestion of the HCL accounted for only 10%, 20% and 30% of the total volume of raw wastewater, but produced 63.38%, 73.79% and 76.61% of the total methane output for S1, S2 and S3, respectively. The mixed liquid of digested effluents of HCL and LCL were treated aerobically using sequencing batch reactors. S2 generated the best performance, with removal efficiencies of 96.98% for COD, 98.95% for NH3-N, 91.69% for TN and 74.71% for TP. The results obtained for S1 were not as good as those for S2, but were better than those for S3. Based on methane output from the anaerobic unit and pollutants removal in the aerobic unit, S2 was the most suitable system for the treatment of swine wastewater. Additionally, the anaerobic digestion efficiency of S2 was 282% higher than that of previous techniques employing balanced distribution. Taken together, these findings indicate that unbalanced distribution could improve the efficiency of the anaerobic unit remarkably, while ensuring good performance of the aerobic unit.

  12. Coal Bed Methane Primer

    SciTech Connect

    Dan Arthur; Bruce Langhus; Jon Seekins

    2005-05-25

    During the second half of the 1990's Coal Bed Methane (CBM) production increased dramatically nationwide to represent a significant new source of income and natural gas for many independent and established producers. Matching these soaring production rates during this period was a heightened public awareness of environmental concerns. These concerns left unexplained and under-addressed have created a significant growth in public involvement generating literally thousands of unfocused project comments for various regional NEPA efforts resulting in the delayed development of public and fee lands. The accelerating interest in CBM development coupled to the growth in public involvement has prompted the conceptualization of this project for the development of a CBM Primer. The Primer is designed to serve as a summary document, which introduces and encapsulates information pertinent to the development of Coal Bed Methane (CBM), including focused discussions of coal deposits, methane as a natural formed gas, split mineral estates, development techniques, operational issues, producing methods, applicable regulatory frameworks, land and resource management, mitigation measures, preparation of project plans, data availability, Indian Trust issues and relevant environmental technologies. An important aspect of gaining access to federal, state, tribal, or fee lands involves education of a broad array of stakeholders, including land and mineral owners, regulators, conservationists, tribal governments, special interest groups, and numerous others that could be impacted by the development of coal bed methane. Perhaps the most crucial aspect of successfully developing CBM resources is stakeholder education. Currently, an inconsistent picture of CBM exists. There is a significant lack of understanding on the parts of nearly all stakeholders, including industry, government, special interest groups, and land owners. It is envisioned the Primer would being used by a variety of

  13. Differentiation of pre-existing trapped methane from thermogenic methane in an igneous-intruded coal by hydrous pyrolysis

    USGS Publications Warehouse

    Dias, Robert F.; Lewan, Michael D.; Birdwell, Justin E.; Kotarba, Maciej J.

    2014-01-01

    So as to better understand how the gas generation potential of coal changes with increasing rank, same-seam samples of bituminous coal from the Illinois Basin that were naturally matured to varying degrees by the intrusion of an igneous dike were subjected to hydrous pyrolysis (HP) conditions of 360 °C for 72 h. The accumulated methane in the reactor headspace was analyzed for δ13C and δ2H, and mol percent composition. Maximum methane production (9.7 mg/g TOC) occurred in the most immature samples (0.5 %Ro), waning to minimal methane values at 2.44 %Ro (0.67 mg/g TOC), and rebounding to 3.6 mg/g TOC methane in the most mature sample (6.76 %Ro). Methane from coal with the highest initial thermal maturity (6.76 %Ro) shows no isotopic dependence on the reactor water and has a microbial δ13C value of −61‰. However, methane from coal of minimal initial thermal maturity (0.5 %Ro) shows hydrogen isotopic dependence on the reaction water and has a δ13C value of −37‰. The gas released from coals under hydrous pyrolysis conditions represents a quantifiable mixture of ancient (270 Ma) methane (likely microbial) that was generated in situ and trapped within the rock during the rapid heating by the dike, and modern (laboratory) thermogenic methane that was generated from the indigenous organic matter due to thermal maturation induced by hydrous pyrolysis conditions. These findings provide an analytical framework for better assessment of natural gas sources and for differentiating generated gas from pre-existing trapped gas in coals of various ranks.

  14. Aerobic degradation of sulfanilic acid using activated sludge.

    PubMed

    Chen, Gang; Cheng, Ka Yu; Ginige, Maneesha P; Kaksonen, Anna H

    2012-01-01

    This paper evaluates the aerobic degradation of sulfanilic acid (SA) by an acclimatized activated sludge. The sludge was enriched for over three months with SA (>500 mg/L) as the sole carbon and energy source and dissolved oxygen (DO, >5mg/L) as the primary electron acceptor. Effects of aeration rate (0-1.74 L/min), DO concentration (0-7 mg/L) and initial SA concentration (104-1085 mg/L) on SA biodegradation were quantified. A modified Haldane substrate inhibition model was used to obtain kinetic parameters of SA biodegradation and oxygen uptake rate (OUR). Positive linear correlations were obtained between OUR and SA degradation rate (R(2)≥ 0.91). Over time, the culture consumed more oxygen per SA degraded, signifying a gradual improvement in SA mineralization (mass ratio of O(2): SA at day 30, 60 and 120 were 0.44, 0.51 and 0.78, respectively). The concomitant release of near stoichiometric quantity of sulphate (3.2 mmol SO(4)(2-) released from 3.3 mmol SA) and the high chemical oxygen demand (COD) removal efficacy (97.1%) indicated that the enriched microbial consortia could drive the overall SA oxidation close to a complete mineralization. In contrast to other pure-culture systems, the ammonium released from the SA oxidation was predominately converted into nitrate, revealing the presence of ammonium-oxidizing bacteria (AOB) in the mixed culture. No apparent inhibitory effect of SA on the nitrification was noted. This work also indicates that aerobic SA biodegradation could be monitored by real-time DO measurement.

  15. Tropospheric impact of methane emissions from clathrates in the Arctic Region

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, S.; Cameron-Smith, P. J.; Bergmann, D.; Reagan, M. T.; Elliott, S. M.; Moridis, G. J.

    2012-12-01

    A highly potent greenhouse gas, methane, is locked in the solid phase as ice-like deposits containing a mixture of water and gas (mostly methane) called clathrates in both ocean sediments and underneath permafrost regions. Clathrates are stable under high pressures and low temperatures. In a warming climate, increases in ocean temperatures could lead to dissociation of the clathrates and release of methane into the ocean and subsequently into the atmosphere. This is of particular importance in the shallow part of the Arctic Ocean, where clathrates are expected to start outgassing abruptly at depths of around 300m. Here we present a comparison of simulations from the Community Earth System Model (CESM1) for present-day conditions with and without additional methane emissions from a plausible clathrate release scenario based on a state-of-the-art ocean sediment model. The model includes a fully interactive physical ocean and a fast atmospheric chemistry mechanism that represents methane as a fully interactive tracer (with emissions rather than concentration boundary conditions), along with the main chemical reactions for methane, ozone, and nitrous oxide. The results show that such clathrate emissions increase methane concentrations spatially non-uniformly, and that increases in surface ozone concentrations are greatest in polluted regions. We also find that the interannual variability in surface methane and ozone increases. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-570979

  16. Methane ocean on Titan?

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    There was an impressive list of names on a recent scientific communication that argues for the existence on Titan of an ocean of liquid methane (CH4) perhaps several hundred meters deep. C. Sagan and S. Dermott with helpful comments by S. Oter, S. Ostro, S. Peale, C. Yoder, W. Thompson, S. Squyres, G. Pettengill, P. Gierasch, and B. Khare speculate that such a methanic ocean, with its Saturnian tides and its tholinian floor, should exist all over Titan's surface; it should unless, they conclude, there is the ‘distracting coincidence [that] … the position of the surface of Titan [is] … near the liquidus in the CH4phase diagram [and, consequently, there is] …almost no methane ocean at all’ (Nature, 300, 731, 1982).We know very little about Titan and its surface; the way of checking into Sagan and Dermott's ideas appears to rest on the interpretation of radar reflectivity data. Preliminary attempts to obtain radar data were made in 1979 with the 305-m Arecibo telescope, but only broad limits resulted. The next opportunity for a measurement at Arecibo comes in the 1990's. Of course, the ideal circumstance would be to send spacecraft equipped with a radar reflectometer for a Titan flyby.

  17. Biodegradability of biodegradable/degradable plastic materials under aerobic and anaerobic conditions.

    PubMed

    Mohee, R; Unmar, G D; Mudhoo, A; Khadoo, P

    2008-01-01

    A study was conducted on two types of plastic materials, Mater-Bi Novamont (MB) and Environmental Product Inc. (EPI), to assess their biodegradability under aerobic and anaerobic conditions. For aerobic conditions, organic fractions of municipal solid wastes were composted. For the anaerobic process, anaerobic inoculum from a wastewater treatment plant was used. Cellulose filter papers (CFP) were used as a positive control for both mediums. The composting process was monitored in terms of temperature, moisture and volatile solids and the biodegradation of the samples were monitored in terms of mass loss. Monitoring results showed a biodegradation of 27.1% on a dry basis for MB plastic within a period of 72 days of composting. Biodegradability under an anaerobic environment was monitored in terms of biogas production. A cumulative methane gas production of 245 ml was obtained for MB, which showed good degradation as compared to CFP (246.8 ml). However, EPI plastic showed a cumulative methane value of 7.6 ml for a period of 32 days, which was close to the blank (4.0 ml). The EPI plastic did not biodegrade under either condition. The cumulative carbon dioxide evolution after 32 days was as follows: CFP 4.406 cm3, MB 2.198 cm3 and EPI 1.328 cm3. The cumulative level of CO2 varying with time fitted sigmoid type curves with R2 values of 0.996, 0.996 and 0.995 for CFP, MB and EPI, respectively.

  18. Mass fractionation of noble gases in synthetic methane hydrate: Implications for naturally occurring gas hydrate dissociation

    USGS Publications Warehouse

    Hunt, Andrew G.; Stern, Laura; Pohlman, John W.; Ruppel, Carolyn; Moscati, Richard J.; Landis, Gary P.

    2013-01-01

    As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings may presently be dissociating and releasing methane and other gases to the ocean-atmosphere system. A key challenge in assessing the impact of dissociating gas hydrates on global atmospheric methane is the lack of a technique able to distinguish between methane recently released from gas hydrates and methane emitted from leaky thermogenic reservoirs, shallow sediments (some newly thawed), coal beds, and other sources. Carbon and deuterium stable isotopic fractionation during methane formation provides a first-order constraint on the processes (microbial or thermogenic) of methane generation. However, because gas hydrate formation and dissociation do not cause significant isotopic fractionation, a stable isotope-based hydrate-source determination is not possible. Here, we investigate patterns of mass-dependent noble gas fractionation within the gas hydrate lattice to fingerprint methane released from gas hydrates. Starting with synthetic gas hydrate formed under laboratory conditions, we document complex noble gas fractionation patterns in the gases liberated during dissociation and explore the effects of aging and storage (e.g., in liquid nitrogen), as well as sampling and preservation procedures. The laboratory results confirm a unique noble gas fractionation pattern for gas hydrates, one that shows promise in evaluating modern natural gas seeps for a signature associated with gas hydrate dissociation.

  19. Methane/nitrogen separation process

    DOEpatents

    Baker, R.W.; Lokhandwala, K.A.; Pinnau, I.; Segelke, S.

    1997-09-23

    A membrane separation process is described for treating a gas stream containing methane and nitrogen, for example, natural gas. The separation process works by preferentially permeating methane and rejecting nitrogen. The authors have found that the process is able to meet natural gas pipeline specifications for nitrogen, with acceptably small methane loss, so long as the membrane can exhibit a methane/nitrogen selectivity of about 4, 5 or more. This selectivity can be achieved with some rubbery and super-glassy membranes at low temperatures. The process can also be used for separating ethylene from nitrogen. 11 figs.

  20. Methane/nitrogen separation process

    DOEpatents

    Baker, Richard W.; Lokhandwala, Kaaeid A.; Pinnau, Ingo; Segelke, Scott

    1997-01-01

    A membrane separation process for treating a gas stream containing methane and nitrogen, for example, natural gas. The separation process works by preferentially permeating methane and rejecting nitrogen. We have found that the process is able to meet natural gas pipeline specifications for nitrogen, with acceptably small methane loss, so long as the membrane can exhibit a methane/nitrogen selectivity of about 4, 5 or more. This selectivity can be achieved with some rubbery and super-glassy membranes at low temperatures. The process can also be used for separating ethylene from nitrogen.

  1. On methane pyrolysis special applications

    NASA Astrophysics Data System (ADS)

    Toncu, D. C.; Toncu, G.; Soleimani, S.

    2015-11-01

    Methane pyrolysis represents one of the most important processes in industrial use, with applications rising from the chemical and petrochemical industry, combustion, materials and protective coatings. Despite the intense research, experimental data lack kinetic aspects, and the thermodynamics involved often leads to inaccurate results when applied to various systems. Carrying out a comparative analysis of several available data on methane pyrolysis, the paper aims to study the phenomenon of methane pyrolysis under different environments (combustion and plasma), concluding on the most possible reaction pathways involved in many of its applications. Computer simulation using different database underlines the conclusion, helping to the understanding of methane pyrolysis importance in future technologies.

  2. Estimation of methane emissions from a wastewater treatment plant in Valence

    NASA Astrophysics Data System (ADS)

    Ars, Sébastien; Yver Kwok, Camille; Bousquet, Philippe; Broquet, Grégoire; Ciais, Philippe; Wu, Lin

    2014-05-01

    Methane is the second most important anthropogenic greenhouse gas emitted; its 20 year global-warming potential is about 56 to 72 depending on authors. One of its sources is the treatment of wastewaters and more particularly anaerobic digestion processes and sludge treatment. To reduce methane emissions from wastewater treatment plants, it is necessary to precisely quantify the amount emitted globally by the plant but also for each step of the process. Fixing the potential leaks and collecting the methane emitted by the different processes allows to reduce methane emissions and costs as methane can be sold or used on-site as an energy source. Moreover improve methods to estimate flow from atmospheric measurements of methane will reduce uncertainties in the inversion models. Several measurement campaigns have been realized in the wastewater treatment plant of Valence, France. This plant treats up to 2800 m3/h of polluted water through a biological treatment. To quantify methane emissions from this wastewater treatment plant, a dual tracer method had been used. It consists in releasing acetylene collocated with the methane source and in measuring both concentrations in the emitted plumes. In parallel, an atmospheric local scale model was used to compare with the experimental results. The higher concentration of methane's emissions was observed around the wastewater arrival. Plant's emissions are in the same range as estimations from the CITEPA French inventory. Measurements during the campaign are well correlated with the model results.

  3. Geologic methane seeps along boundaries of Arctic permafrost thaw and melting glaciers

    NASA Astrophysics Data System (ADS)

    Walter Anthony, Katey M.; Anthony, Peter; Grosse, Guido; Chanton, Jeffrey

    2012-06-01

    Methane, a potent greenhouse gas, accumulates in subsurface hydrocarbon reservoirs, such as coal beds and natural gas deposits. In the Arctic, permafrost and glaciers form a `cryosphere cap' that traps gas leaking from these reservoirs, restricting flow to the atmosphere. With a carbon store of over 1,200Pg, the Arctic geologic methane reservoir is large when compared with the global atmospheric methane pool of around 5Pg. As such, the Earth's climate is sensitive to the escape of even a small fraction of this methane. Here, we document the release of 14C-depleted methane to the atmosphere from abundant gas seeps concentrated along boundaries of permafrost thaw and receding glaciers in Alaska and Greenland, using aerial and ground surface survey data and in situ measurements of methane isotopes and flux. We mapped over 150,000 seeps, which we identified as bubble-induced open holes in lake ice. These seeps were characterized by anomalously high methane fluxes, and in Alaska by ancient radiocarbon ages and stable isotope values that matched those of coal bed and thermogenic methane accumulations. Younger seeps in Greenland were associated with zones of ice-sheet retreat since the Little Ice Age. Our findings imply that in a warming climate, disintegration of permafrost, glaciers and parts of the polar ice sheets could facilitate the transient expulsion of 14C-depleted methane trapped by the cryosphere cap.

  4. Methane production and digestibility measurements in the grey kangaroo and sheep.

    PubMed

    Kempton, T J; Murray, R M; Leng, R A

    1976-07-01

    Three grey knagaroos and three sheep were given a diet of lucerne chaff and measurements were made of feed intake, digestibility coefficients, methane production rate and volatile fatty acid content of the "stomach" and caecum for each animal. The kangaroos had lower intakes of digestible dry matter and organic matter than the sheep; this was related to lower intakes of dry matter and lower apparent digestibility coefficients particularly of the crude fibre fraction. Methane production in the sheep (collected in respired air through a mask) was 0-81 litre/h; no methane was collected in the respired air from kangaroos. Anal release of methane in sheep and kangaroos indicated that some methane was produced in the hind gut of kangaroos and that all of this methane was lost via the anus. This finding was different to the sheep which apparently excreted 80-90% of the hind gut methane via the lungs. Thus in both sites of apparent high microbial growth in the gut of kangaroos methane production is negligible or lower than in the same sites in sheep. Possible explanations for the absence of measurable methane production in the kangaroo fore-stomachs are discussed. PMID:985222

  5. Methane hydrate-bearing seeps as a source of aged dissolved organic carbon to the oceans

    USGS Publications Warehouse

    Pohlman, J.W.; Bauer, J.E.; Waite, W.F.; Osburn, C.L.; Chapman, N.R.

    2011-01-01

    Marine sediments contain about 500-10,000 Gt of methane carbon, primarily in gas hydrate. This reservoir is comparable in size to the amount of organic carbon in land biota, terrestrial soils, the atmosphere and sea water combined, but it releases relatively little methane to the ocean and atmosphere. Sedimentary microbes convert most of the dissolved methane to carbon dioxide. Here we show that a significant additional product associated with microbial methane consumption is methane-derived dissolved organic carbon. We use ??14 C and ??13 C measurements and isotopic mass-balance calculations to evaluate the contribution of methane-derived carbon to seawater dissolved organic carbon overlying gas hydrate-bearing seeps in the northeastern Pacific Ocean. We show that carbon derived from fossil methane accounts for up to 28% of the dissolved organic carbon. This methane-derived material is much older, and more depleted in 13 C, than background dissolved organic carbon. We suggest that fossil methane-derived carbon may contribute significantly to the estimated 4,000-6,000 year age of dissolved organic carbon in the deep ocean, and provide reduced organic matter and energy to deep-ocean microbial communities. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  6. Metal enzymes in "impossible" microorganisms catalyzing the anaerobic oxidation of ammonium and methane.

    PubMed

    Reimann, Joachim; Jetten, Mike S M; Keltjens, Jan T

    2015-01-01

    Ammonium and methane are inert molecules and dedicated enzymes are required to break up the N-H and C-H bonds. Until recently, only aerobic microorganisms were known to grow by the oxidation of ammonium or methane. Apart from respiration, oxygen was specifically utilized to activate the inert substrates. The presumed obligatory need for oxygen may have resisted the search for microorganisms that are capable of the anaerobic oxidation of ammonium and of methane. However extremely slowly growing, these "impossible" organisms exist and they found other means to tackle ammonium and methane. Anaerobic ammonium-oxidizing (anammox) bacteria use the oxidative power of nitric oxide (NO) by forging this molecule to ammonium, thereby making hydrazine (N2H4). Nitrite-dependent anaerobic methane oxidizers (N-DAMO) again take advantage of NO, but now apparently disproportionating the compound into dinitrogen and dioxygen gas. This intracellularly produced dioxygen enables N-DAMO bacteria to adopt an aerobic mechanism for methane oxidation.Although our understanding is only emerging how hydrazine synthase and the NO dismutase act, it seems clear that reactions fully rely on metal-based catalyses known from other enzymes. Metal-dependent conversions not only hold for these key enzymes, but for most other reactions in the central catabolic pathways, again supported by well-studied enzymes from model organisms, but adapted to own specific needs. Remarkably, those accessory catabolic enzymes are not unique for anammox bacteria and N-DAMO. Close homologs are found in protein databases where those homologs derive from (partly) known, but in most cases unknown species that together comprise an only poorly comprehended microbial world. PMID:25707470

  7. Metal enzymes in "impossible" microorganisms catalyzing the anaerobic oxidation of ammonium and methane.

    PubMed

    Reimann, Joachim; Jetten, Mike S M; Keltjens, Jan T

    2015-01-01

    Ammonium and methane are inert molecules and dedicated enzymes are required to break up the N-H and C-H bonds. Until recently, only aerobic microorganisms were known to grow by the oxidation of ammonium or methane. Apart from respiration, oxygen was specifically utilized to activate the inert substrates. The presumed obligatory need for oxygen may have resisted the search for microorganisms that are capable of the anaerobic oxidation of ammonium and of methane. However extremely slowly growing, these "impossible" organisms exist and they found other means to tackle ammonium and methane. Anaerobic ammonium-oxidizing (anammox) bacteria use the oxidative power of nitric oxide (NO) by forging this molecule to ammonium, thereby making hydrazine (N2H4). Nitrite-dependent anaerobic methane oxidizers (N-DAMO) again take advantage of NO, but now apparently disproportionating the compound into dinitrogen and dioxygen gas. This intracellularly produced dioxygen enables N-DAMO bacteria to adopt an aerobic mechanism for methane oxidation.Although our understanding is only emerging how hydrazine synthase and the NO dismutase act, it seems clear that reactions fully rely on metal-based catalyses known from other enzymes. Metal-dependent conversions not only hold for these key enzymes, but for most other reactions in the central catabolic pathways, again supported by well-studied enzymes from model organisms, but adapted to own specific needs. Remarkably, those accessory catabolic enzymes are not unique for anammox bacteria and N-DAMO. Close homologs are found in protein databases where those homologs derive from (partly) known, but in most cases unknown species that together comprise an only poorly comprehended microbial world.

  8. Polluting a microbial methane sink. [Effect of nitrogen in acid rain on reducing removal of methane from the atmosphere by soil bacteria

    SciTech Connect

    Not Available

    1990-03-01

    Excess nitrogen, whether from fertilization or from acid rain, seems to reduce the amount of methane that soil organisms can remove from the atmosphere. Methane, an important greenhouse gas, contributes to global warming by acting as an atmospheric blanket. The gas has been increasing approximately 1% a year for the past decade, due either to increases in global sources or decrease in biological sinks. The largest such sinks are the microorganisms in aerobic soils. Recent research by P.A. Steudler, R.D. Bowden, and J.M. Melillo of the Marine Biological Laboratory, Woods Hole, Massachusetts, and J.D. Aber of the University of New Hampshire, Durham, has shown that added nitrogen significantly decreases the rates at which temperate forest soils can take up methane. Laboratory studies with soil microorganisms support the field observations, suggesting that high nitrogen suppresses methane uptake. The researchers say further measurements in agroecosystems, pastures, and other high-nitrogen systems are needed to clarify the nitrogen-methane interaction before extrapolation to a global basis.

  9. Aerobic Excercise and Research Opportunities to Benefit Impaired Children. (Project AEROBIC). Final Report.

    ERIC Educational Resources Information Center

    Idaho Univ., Moscow.

    The final report summarizes accomplishments of Project AEROBIC (Aerobic Exercise and Research Opportunities to Benefit Impaired Children), which provided a physical education exercise program for severely, profoundly, and multiply handicapped children aged 10-21. Activities are outlined for the 3 year period and include modification of exercise…

  10. Carbothermal Processing of Lunar Regolith Using Methane

    NASA Technical Reports Server (NTRS)

    Balasubramaniam, R.; Hegde, U.; Gokoglu, S.

    2008-01-01

    The processing of lunar regolith for the production of oxygen is a key component of the In-Situ Resource Utilization plans currently being developed by NASA. Among various candidate processes, the modeling of oxygen production by hydrogen reduction, molten salt electrolysis, and carbothermal processing are presently being pursued. In the carbothermal process, a portion of the surface of the regolith in a container is heated by exposure to a heat source such as a laser beam or a concentrated solar heat flux, so that a small zone of molten regolith is established. The molten zone is surrounded by solid regolith particles that are poor conductors of heat. A continuous flow of methane is maintained over the molten regolith zone. Our model is based on a mechanism where methane pyrolyzes when it comes in contact with the surface of the hot molten regolith to form solid carbon and hydrogen gas. Carbon is deposited on the surface of the melt, and hydrogen is released into the gas stream above the melt surface. We assume that the deposited carbon mixes in the molten regolith and reacts with metal oxides in a reduction reaction by which gaseous carbon monoxide is liberated. Carbon monoxide bubbles through the melt and is released into the gas stream. Oxygen is produced subsequently by (catalytically) processing the carbon monoxide downstream. In this paper, we discuss the development of a chemical conversion model of the carbothermal process to predict the rate of production of carbon monoxide.

  11. Carbothermal Processing of Lunar Regolith Using Methane

    NASA Technical Reports Server (NTRS)

    Balasubramaniam, R.; Hegde, U.; Gokoglu, S.

    2009-01-01

    The processing of lunar regolith for the production of oxygen is a key component of the In-Situ Resource Utilization plans currently being developed by NASA. Among various candidate processes, the modeling of oxygen production by hydrogen reduction, molten salt electrolysis, and carbothermal processing are presently being pursued. In the carbothermal process, a portion of the surface of the regolith in a container is heated by exposure to a heat source such as a laser beam or a concentrated solar heat flux, so that a small zone of molten regolith is established. The molten zone is surrounded by solid regolith particles that are poor conductors of heat. A continuous flow of methane is maintained over the molten regolith zone. Our model is based on a mechanism where methane pyrolyzes when it comes in contact with the surface of the hot molten regolith to form solid carbon and hydrogen gas. Carbon is deposited on the surface of the melt, and hydrogen is released into the gas stream above the melt surface. We assume that the deposited carbon mixes in the molten regolith and reacts with metal oxides in a reduction reaction by which gaseous carbon monoxide is liberated. Carbon monoxide bubbles through the melt and is released into the gas stream. Oxygen is produced subsequently by (catalytically) processing the carbon monoxide downstream. In this paper, we discuss the development of a chemical conversion model of the carbothermal process to predict the rate of production of carbon monoxide.

  12. Evaluation of a combined anaerobic and aerobic system for the treatment of slaughterhouse wastewater.

    PubMed

    López-López, A; Vallejo-Rodríguez, R; Méndez-Romero, D C

    2010-03-01

    A laboratory scale anaerobic/aerobic (An/Ar) system, comprising an anaerobic filter (AF) coupled to an aerobic sequential batch reactor (SBR), was developed to treat wastewater from a slaughterhouse. The AF operated with organic loadings (OL) from 3.7 to 16.5 kg m(-3) d(-1) and a hydraulic retention time (HRT) ranging from 16 to 72 h. The efficiency of chemical oxygen demand (COD) removal was between 50 and 81% and was shown to be related inversely to the value of the OL. The production rate of methane was in the region of 411 mL per g of COD removed. On the other hand, the degradation of organic matter (OM) by an aerobic pathway in the SBR followed first-order kinetics with regard to OM concentration; 85% of the remaining OM from the AF was eliminated within 6 h of aeration, and over 95% of total OM was eliminated as COD within 9 h. The optimal treatment conditions in this system were found at OL = 11.0 kg m-3 d(-1) and HRT = 24 h in the AF, whereas the SBR was most efficient at 9 h of aeration. PMID:20426273

  13. Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions

    USGS Publications Warehouse

    Isaksen, Ivar S.A.; Gauss, Michael; Myhre, Gunnar; Walter Anthony, Katey M.; Ruppel, Carolyn

    2011-01-01

    The magnitude and feedbacks of future methane release from the Arctic region are unknown. Despite limited documentation of potential future releases associated with thawing permafrost and degassing methane hydrates, the large potential for future methane releases calls for improved understanding of the interaction of a changing climate with processes in the Arctic and chemical feedbacks in the atmosphere. Here we apply a “state of the art” atmospheric chemistry transport model to show that large emissions of CH4 would likely have an unexpectedly large impact on the chemical composition of the atmosphere and on radiative forcing (RF). The indirect contribution to RF of additional methane emission is particularly important. It is shown that if global methane emissions were to increase by factors of 2.5 and 5.2 above current emissions, the indirect contributions to RF would be about 250% and 400%, respectively, of the RF that can be attributed to directly emitted methane alone. Assuming several hypothetical scenarios of CH4 release associated with permafrost thaw, shallow marine hydrate degassing, and submarine landslides, we find a strong positive feedback on RF through atmospheric chemistry. In particular, the impact of CH4 is enhanced through increase of its lifetime, and of atmospheric abundances of ozone, stratospheric water vapor, and CO2 as a result of atmospheric chemical processes. Despite uncertainties in emission scenarios, our results provide a better understanding of the feedbacks in the atmospheric chemistry that would amplify climate warming.

  14. On Aerobic Exercise and Behavioral and Neural Plasticity

    PubMed Central

    Swain, Rodney A.; Berggren, Kiersten L.; Kerr, Abigail L.; Patel, Ami; Peplinski, Caitlin; Sikorski, Angela M.

    2012-01-01

    Aerobic exercise promotes rapid and profound alterations in the brain. Depending upon the pattern and duration of exercise, these changes in the brain may extend beyond traditional motor areas to regions and structures normally linked to learning, cognition, and emotion. Exercise-induced alterations may include changes in blood flow, hormone and growth factor release, receptor expression, angiogenesis, apoptosis, neurogenesis, and synaptogenesis. Together, we believe that these changes underlie elevations of mood and prompt the heightened behavioral plasticity commonly observed following adoption of a chronic exercise regimen. In the following paper, we will explore both the psychological and psychobiological literatures relating to exercise effects on brain in both human and non-human animals and will attempt to link plastic changes in these neural structures to modifications in learned behavior and emotional expression. In addition, we will explore the therapeutic potential of exercise given recent reports that aerobic exercise may serve as a neuroprotectant and can also slow cognitive decline during normal and pathological aging. PMID:24961267

  15. Carbon isotopic evidence for methane hydrate instability during quaternary interstadials

    PubMed

    Kennett; Cannariato; Hendy; Behl

    2000-04-01

    Large (about 5 per mil) millennial-scale benthic foraminiferal carbon isotopic oscillations in the Santa Barbara Basin during the last 60,000 years reflect widespread shoaling of sedimentary methane gradients and increased outgassing from gas hydrate dissociation during interstadials. Furthermore, several large, brief, negative excursions (up to -6 per mil) coinciding with smaller shifts (up to -3 per mil) in depth-stratified planktonic foraminiferal species indicate massive releases of methane from basin sediments. Gas hydrate stability was modulated by intermediate-water temperature changes induced by switches in thermohaline circulation. These oscillations were likely widespread along the California margin and elsewhere, affecting gas hydrate instability and contributing to millennial-scale atmospheric methane oscillations.

  16. Mechanical instability of monocrystalline and polycrystalline methane hydrates

    PubMed Central

    Wu, Jianyang; Ning, Fulong; Trinh, Thuat T.; Kjelstrup, Signe; Vlugt, Thijs J. H.; He, Jianying; Skallerud, Bjørn H.; Zhang, Zhiliang

    2015-01-01

    Despite observations of massive methane release and geohazards associated with gas hydrate instability in nature, as well as ductile flow accompanying hydrate dissociation in artificial polycrystalline methane hydrates in the laboratory, the destabilising mechanisms of gas hydrates under deformation and their grain-boundary structures have not yet been elucidated at the molecular level. Here we report direct molecular dynamics simulations of the material instability of monocrystalline and polycrystalline methane hydrates under mechanical loading. The results show dislocation-free brittle failure in monocrystalline hydrates and an unexpected crossover from strengthening to weakening in polycrystals. Upon uniaxial depressurisation, strain-induced hydrate dissociation accompanied by grain-boundary decohesion and sliding destabilises the polycrystals. In contrast, upon compression, appreciable solid-state structural transformation dominates the response. These findings provide molecular insight not only into the metastable structures of grain boundaries, but also into unusual ductile flow with hydrate dissociation as observed during macroscopic compression experiments. PMID:26522051

  17. Mechanical instability of monocrystalline and polycrystalline methane hydrates.

    PubMed

    Wu, Jianyang; Ning, Fulong; Trinh, Thuat T; Kjelstrup, Signe; Vlugt, Thijs J H; He, Jianying; Skallerud, Bjørn H; Zhang, Zhiliang

    2015-01-01

    Despite observations of massive methane release and geohazards associated with gas hydrate instability in nature, as well as ductile flow accompanying hydrate dissociation in artificial polycrystalline methane hydrates in the laboratory, the destabilising mechanisms of gas hydrates under deformation and their grain-boundary structures have not yet been elucidated at the molecular level. Here we report direct molecular dynamics simulations of the material instability of monocrystalline and polycrystalline methane hydrates under mechanical loading. The results show dislocation-free brittle failure in monocrystalline hydrates and an unexpected crossover from strengthening to weakening in polycrystals. Upon uniaxial depressurisation, strain-induced hydrate dissociation accompanied by grain-boundary decohesion and sliding destabilises the polycrystals. In contrast, upon compression, appreciable solid-state structural transformation dominates the response. These findings provide molecular insight not only into the metastable structures of grain boundaries, but also into unusual ductile flow with hydrate dissociation as observed during macroscopic compression experiments. PMID:26522051

  18. Carbon isotopic evidence for methane hydrate instability during quaternary interstadials

    PubMed

    Kennett; Cannariato; Hendy; Behl

    2000-04-01

    Large (about 5 per mil) millennial-scale benthic foraminiferal carbon isotopic oscillations in the Santa Barbara Basin during the last 60,000 years reflect widespread shoaling of sedimentary methane gradients and increased outgassing from gas hydrate dissociation during interstadials. Furthermore, several large, brief, negative excursions (up to -6 per mil) coinciding with smaller shifts (up to -3 per mil) in depth-stratified planktonic foraminiferal species indicate massive releases of methane from basin sediments. Gas hydrate stability was modulated by intermediate-water temperature changes induced by switches in thermohaline circulation. These oscillations were likely widespread along the California margin and elsewhere, affecting gas hydrate instability and contributing to millennial-scale atmospheric methane oscillations. PMID:10753115

  19. Consumption of atmospheric methane by tundra soils

    NASA Technical Reports Server (NTRS)

    Whalen, S. C.; Reeburgh, W. S.

    1990-01-01

    The results of field and laboratory experiments on methane consumption by tundra soils are reported. For methane concentrations ranging from below to well above ambient, moist soils are found to consume methane rapidly; in nonwaterlogged soils, equilibration with atmospheric methane is fast relative to microbial oxidation. It is concluded that lowering of the water table in tundra as a resulting from a warmer, drier climate will decrease methane fluxes and could cause these areas to provide negative feedback for atmospheric methane.

  20. Methane hydrate - A major reservoir of carbon in the shallow geosphere?

    USGS Publications Warehouse

    Kvenvolden, K.A.

    1988-01-01

    Methane hydrates are solids composed of rigid cages of water molecules that enclose methane. Sediment containing methane hydrates is found within specific pressure-temperature conditions that occur in regions of permafrost and beneath the sea in outer continental margins. Because methane hydrates are globally widespread and concentrate methane within the gas-hydrate structure, the potential amount of methane present in the shallow geosphere at subsurface depths of < ???2000 m is very large. However, estimates of the amount are speculative and range over about three orders of magnitude, from 2 ?? 103 to 4 ?? 106 Gt (gigatons = 1015 g) of carbon, depending on the assumptions made. The estimate I favor is ??? 1 ?? 104 Gt of carbon. The estimated amount of organic carbon in the methane-hydrate reservoir greatly exceeds that in many other reservoirs of the global carbon cycle - for example, the atmosphere (3.6 Gt); terrestrial biota (830 Gt); terrestrial soil, detritus and peat (1960 Gt); marine biota (3 Gt); and marine dissolved materials (980 Gt). In fact, the amount of carbon may exceed that in all fossil fuel deposits (5 ?? 103 Gt). Because methane hydrates contain so much methane and occur in the shallow geosphere, they are of interest as a potential resource of natural gas and as a possible source of atmospheric methane released by global warming. As a potential resource, methane hydrates pose both engineering and production problems. As a contributor to a changing global climate, destabilized methane hydrates, particularly those in shallow, nearshore regions of the Arctic Ocean, may have some effect, but this effect will probably be minimal, at least during the next 100 years. ?? 1988.

  1. Summer methane fluxes from a boreal bog in northern Quebec, Canada, using eddy covariance measurements

    NASA Astrophysics Data System (ADS)

    Nadeau, Daniel F.; Rousseau, Alain N.; Coursolle, Carole; Margolis, Hank A.; Parlange, Marc B.

    2013-12-01

    A boreal bog located in the James Bay lowlands, Canada, was instrumented with an open-path gas analyzer to monitor the turbulent fluxes of methane throughout the summer of 2012. The mostly continuous eddy covariance measurements permitted the study of methane dynamics at the hourly, daily and seasonal scales. To exclude data segments for which the biological methane fluxes were underestimated due to inefficient atmospheric transport under stable stratification, we applied a novel approach based on both the atmospheric stability parameter ζ = z/L and the friction velocity u∗, where z is the measurement height and L the Obukhov length. The field measurements revealed the existence of at least one sustained ebullition event, triggered by low barometric pressures, a declining water table and increasing mechanical turbulence - suggesting that large-scale release of methane bubbles can be an important transport mechanism of methane in boreal bogs. The validity of similarity scaling for atmospheric methane under convective conditions was also assessed and the normalized standard deviations of methane concentrations did not scale well with ζ, highlighting the heterogeneity in natural methane production and release across the bog. Overall the hourly emissions ranged between -2.0 and 32.1 mg CH4 m-2 h-1, with a summertime mean of 2.4 mg CH4 m-2 h-1. At the daily scale, the two main controls on methane emissions were found to be the water table position and the peat temperature at 0.3 m under the surface. Contrary to other studies, seasonal methane emissions peaked when the water table was at its maximum distance from the surface, around mid-August. No clear diurnal pattern could be found in methane emissions, indicating that methane was produced quite deep within the peat. The seasonal emissions were estimated at 4.4 g CH4 m-2, and compared well with other observations over similar landscapes using different measurement techniques. Given that methane releases and

  2. Methane emissions from canopy wetlands

    NASA Astrophysics Data System (ADS)

    Martinson, G. O.; Conrad, R.

    2012-12-01

    Ground wetlands are the main natural source of methane but they fail to explain the observed amounts of methane over tropical forests. Bromeliad tanks are discrete habitats for aquatic organisms and up to several thousand of bromeliad individuals per hectare of tropical forest create a unique canopy wetland ecosystem in neotropical forests. Recently, we have discovered that canopy wetlands inhabit methanogenic archaea, emit substantial amounts of methane and may help to explain the high amounts of methane over neotropical forests. However, the pathway of methane formation and potential methane production in canopy wetlands of different tropical forest ecosystems have not yet been studied. In this study, we investigated the stable carbon isotope fractionation, methanogenic pathway and potential methane production of bromeliad tanks along an elevation gradient in neotropical forests for the first time. We sampled the bromeliad tank-substrate of 3 tank bromeliads per functional type and elevation (1000 m, 2000 m and 3000 m above the sea level). We distinguished three functional types of tank bromeliads, based on plant architecture and ecological niche preference. Functional type I-tank bromeliads are concentrated in the understory and on the ground. Functional type II and type III are concentrated in the mid and overstory. We conducted tank-substrate incubation experiments and measured CH4, CO2, 13CH4 and 13CO2 at regular time intervals during the incubation period. The methane production potential of bromeliad tanks correlated positively with tank-substrate carbon concentration and decreased with increasing canopy height and increasing elevation. The dominant pathway of methane formation in bromeliad tanks was hydrogenotrophic methanogenesis (>50%) and this dominance increased with increasing canopy height and increasing elevation. Our results provide novel insights into the pathway of methane formation in neotropical canopy wetlands and suggest that canopy height is

  3. Aerobic Microbial Respiration in Oceanic Oxygen Minimum Zones

    NASA Astrophysics Data System (ADS)

    Kalvelage, Tim; Lavik, Gaute; Jensen, Marlene M.; Revsbech, Niels Peter; Schunck, Harald; Loescher, Carolin; Desai, Dhwani K.; LaRoche, Julie; Schmitz-Streit, Ruth; Kuypers, Marcel M. M.

    2014-05-01

    In the oxygen minimum zones (OMZs) of the tropical oceans, sluggish ventilation combined with strong microbial respiration of sinking organic matter results in the depletion of oxygen (O2). When O2 concentrations drop below ~5 µmol/L, organic matter is generally assumed to be respired with nitrate, ultimately leading to the loss of fixed inorganic nitrogen via anammox and denitrification. However, direct measurements of microbial O2 consumption at low O2 levels are - apart from a single experiment conducted in the OMZ off Peru - so far lacking. At the same time, consistently observed active aerobic ammonium and nitrite oxidation at non-detectable O2 concentrations (<1 µmol/L) in all major OMZs, suggests aerobic microorganisms, likely including heterotrophs, to be well adapted to near-anoxic conditions. Consequently, microaerobic (≤5 µmol/L) remineralization of organic matter, and thus release of ammonium, in low- O2 environments might be significantly underestimated at present. Here we present extensive measurements of microbial O2 consumption in OMZ waters, combined with highly sensitive O2 (STOX) measurements and meta-omic functional gene analyses. Short-term incubation experiments with labelled O2 (18-18O2) carried out in the Namibian and Peruvian OMZ, revealed persistent aerobic microbial activity at depths with non-detectable concentrations of O2 (≤50 nmol/L). In accordance, examination of metagenomes and metatranscriptomes from Chilean and Peruvian OMZ waters identified genes encoding for terminal respiratory oxidases with high O2 affinities as well as their expression by diverse microbial communities. Oxygen consumption was particularly enhanced near the upper OMZ boundaries and could mostly (~80%) be assigned to heterotrophic microbial activity. Compared to previously identified anaerobic microbial processes, microaerobic organic matter respiration was the dominant remineralization pathway and source of ammonium (~90%) in the upper Namibian and

  4. Sources of atmospheric methane - Measurements in rice paddies and a discussion

    NASA Technical Reports Server (NTRS)

    Cicerone, R. J.; Shetter, J. D.

    1981-01-01

    Field measurements of methane fluxes from rice paddies, fresh water lakes, and saltwater marshes have been made to infer estimates of the size of these sources of atmospheric methane. The rice-paddy measurements, the first of their kind, show that the principal means of methane escape is through the plants themselves as opposed to transport across the water-air interface via bubbles or molecular diffusion. Nitrogen-fertilized plants release much more methane than unfertilized plants but even these measured rates are only one fourth as large as those inferred earlier by Koyama (1963, 1964) and on which all global extrapolations have been based to date. Measured methane fluxes from lakes and marshes are also compared to similar earlier data and it is found that extant data and flux-measurement methods are insufficient for reliable global extrapolations.

  5. Methane Gas Concentration in Soils and Ground Water, Carbon and Emery Counties, Utah, 1995-2003

    USGS Publications Warehouse

    Stolp, B.J.; Burr, A.L.; Johnson, K.K.

    2006-01-01

    The release of methane gas from coal beds creates the potential for it to move into near-surface environments through natural and human-made pathways. To help ensure the safety of communities and determine the potential effects of development of coal-bed resources, methane gas concentrations in soils and ground water in Carbon and Emery Counties, Utah, were monitored from 1995 to 2003. A total of 420 samples were collected, which contained an average methane concentration of 2,740 parts per million by volume (ppmv) and a median concentration of less than 10 ppmv. On the basis of spatial and temporal methane concentration data collected during the monitoring period, there does not appear to be an obvious, widespread, or consistent migration of methane gas to the near-surface environment.

  6. Monitoring for Methane Gas in Carbon and Emery Counties, Utah, 1995-2003

    USGS Publications Warehouse

    Burr, Andrew L.; Stolp, Bernard J.; Johnson, Kevin K.; Hunt, Gilbert L.

    2006-01-01

    The release of methane gas from coal beds creates the potential for it to move into near-surface environments through natural and human-made pathways. To help ensure the safety of communities and determine the potential effects of development of coal-bed resources, methane gas concentrations in soils and ground water in Carbon and Emery Counties, Utah, were monitored from 1995 to 2003. A total of 420 samples were collected, which contained an average methane concentration of 2,740 parts per million by volume (ppmv) and a median concentration of less than 10 ppmv. On the basis of spatial and temporal methane concentration data collected during the monitoring period, there does not appear to be an obvious, widespread, or consistent migration of methane gas to the near-surface environment.

  7. Small thaw ponds: an unaccounted source of methane in the Canadian high Arctic.

    PubMed

    Negandhi, Karita; Laurion, Isabelle; Whiticar, Michael J; Galand, Pierre E; Xu, Xiaomei; Lovejoy, Connie

    2013-01-01

    Thawing permafrost in the Canadian Arctic tundra leads to peat erosion and slumping in narrow and shallow runnel ponds that surround more commonly studied polygonal ponds. Here we compared the methane production between runnel and polygonal ponds using stable isotope ratios, ¹⁴C signatures, and investigated potential methanogenic communities through high-throughput sequencing archaeal 16S rRNA genes. We found that runnel ponds had significantly higher methane and carbon dioxide emissions, produced from a slightly larger fraction of old carbon, compared to polygonal ponds. The methane stable isotopic signature indicated production through acetoclastic methanogenesis, but gene signatures from acetoclastic and hydrogenotrophic methanogenic Archaea were detected in both polygonal and runnel ponds. We conclude that runnel ponds represent a source of methane from potentially older C, and that they contain methanogenic communities able to use diverse sources of carbon, increasing the risk of augmented methane release under a warmer climate.

  8. Small Thaw Ponds: An Unaccounted Source of Methane in the Canadian High Arctic

    PubMed Central

    Negandhi, Karita; Laurion, Isabelle; Whiticar, Michael J.; Galand, Pierre E.; Xu, Xiaomei; Lovejoy, Connie

    2013-01-01

    Thawing permafrost in the Canadian Arctic tundra leads to peat erosion and slumping in narrow and shallow runnel ponds that surround more commonly studied polygonal ponds. Here we compared the methane production between runnel and polygonal ponds using stable isotope ratios, 14C signatures, and investigated potential methanogenic communities through high-throughput sequencing archaeal 16S rRNA genes. We found that runnel ponds had significantly higher methane and carbon dioxide emissions, produced from a slightly larger fraction of old carbon, compared to polygonal ponds. The methane stable isotopic signature indicated production through acetoclastic methanogenesis, but gene signatures from acetoclastic and hydrogenotrophic methanogenic Archaea were detected in both polygonal and runnel ponds. We conclude that runnel ponds represent a source of methane from potentially older C, and that they contain methanogenic communities able to use diverse sources of carbon, increasing the risk of augmented methane release under a warmer climate. PMID:24236014

  9. Methane and nitrous oxide in the ice core record.

    PubMed

    Wolff, Eric; Spahni, Renato

    2007-07-15

    Polar ice cores contain, in trapped air bubbles, an archive of the concentrations of stable atmospheric gases. Of the major non-CO2 greenhouse gases, methane is measured quite routinely, while nitrous oxide is more challenging, with some artefacts occurring in the ice and so far limited interpretation. In the recent past, the ice cores provide the only direct measure of the changes that have occurred during the industrial period; they show that the current concentration of methane in the atmosphere is far outside the range experienced in the last 650,000 years; nitrous oxide is also elevated above its natural levels. There is controversy about whether changes in the pre-industrial Holocene are natural or anthropogenic in origin. Changes in wetland emissions are generally cited as the main cause of the large glacial-interglacial change in methane. However, changing sinks must also be considered, and the impact of possible newly described sources evaluated. Recent isotopic data appear to finally rule out any major impact of clathrate releases on methane at these time-scales. Any explanation must take into account that, at the rapid Dansgaard-Oeschger warmings of the last glacial period, methane rose by around half its glacial-interglacial range in only a few decades. The recent EPICA Dome C (Antarctica) record shows that methane tracked climate over the last 650,000 years, with lower methane concentrations in glacials than interglacials, and lower concentrations in cooler interglacials than in warmer ones. Nitrous oxide also shows Dansgaard-Oeschger and glacial-interglacial periodicity, but the pattern is less clear.

  10. The strength and rheology of methane clathrate hydrate

    USGS Publications Warehouse

    Durham, W.B.; Kirby, S.H.; Stern, L.A.; Zhang, W.

    2003-01-01

    Methane clathrate hydrate (structure I) is found to be very strong, based on laboratory triaxial deformation experiments we have carried out on samples of synthetic, high-purity, polycrystalline material. Samples were deformed in compressional creep tests (i.e., constant applied stress, ??), at conditions of confining pressure P = 50 and 100 MPa, strain rate 4.5 ?? 10-8 ??? ?? ??? 4.3 ?? 10-4 s-1, temperature 260 ??? T ??? 287 K, and internal methane pressure 10 ??? PCH4 ??? 15 MPa. At steady state, typically reached in a few percent strain, methane hydrate exhibited strength that was far higher than expected on the basis of published work. In terms of the standard high-temperature creep law, ?? = A??ne-(E*+PV*)/RT the rheology is described by the constants A = 108.55 MPa-n s-1, n = 2.2, E* = 90,000 J mol-1, and V* = 19 cm3 mol-1. For comparison at temperatures just below the ice point, methane hydrate at a given strain rate is over 20 times stronger than ice, and the contrast increases at lower temperatures. The possible occurrence of syntectonic dissociation of methane hydrate to methane plus free water in these experiments suggests that the high strength measured here may be only a lower bound. On Earth, high strength in hydrate-bearing formations implies higher energy release upon decomposition and subsequent failure. In the outer solar system, if Titan has a 100-km-thick near-surface layer of high-strength, low-thermal conductivity methane hydrate as has been suggested, its interior is likely to be considerably warmer than previously expected.

  11. Atmospheric Impact of Large Methane Emission in the Arctic Region

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, S.; Cameron-Smith, P. J.; Bergmann, D.; Reagan, M. T.; Collins, W.; Elliott, S. M.; Maltrud, M. E.

    2011-12-01

    A highly potent greenhouse gas, methane, is locked in the solid phase as ice-like deposits containing a mixture of water and gas (mostly methane) called clathrates, in ocean sediments and unde