WorldWideScience

Sample records for episodic methane release

  1. Clathrate hydrates as possible source of episodic methane releases on Mars

    Science.gov (United States)

    Karatekin, Özgür; Gloesener, Elodie; Temel, Orkun

    2017-04-01

    Methane has been shown to vary with location and time in the Martian atmosphere, with abundances of up to tens of parts-per-billion by volume (ppbv). Since methane is short-lived on geological time scales, its presence implies the existence of an active, current source of methane that is yet to be understood. In this study we investigate the destabilization of subsurface reservoirs of clathrate hydrates as a possible geological source of methane. Clathrate hydrates are crystalline compounds constituted by cages of hydrogen-bonded water molecules, inside of which guest gas molecules are trapped. We show the present-day maps of methane clathrate stability zones, in particular in the vicinity of Gale Crater where the Sample Analysis at Mars (SAM) suite on the Curiosity rover has made in situ measurements of atmospheric methane, during more than 3 years. Curiosity has observed spikes of elevated methane levels of 7 ppbv on four sequential observations over a 2-month period. The possibility of episodic releases consistent with curiosity observations from a subsurface clathrate source, is investigated using a gas transport through porous Martian regolith considering different depths of reservoirs. Transport of the released methane spike into the atmosphere is simulated using the PlanetWRF model.

  2. Minimizing methane release

    NARCIS (Netherlands)

    Arendonk, van J.A.M.

    2014-01-01

    "Methane emissions from cows are decreasing, but not at the pace which the agricultural sector and the government agreed. The project, Reduced methane emission of dairy cows (ME001), will provide insights that enable targeted interventions for a 30% reduction of greenhouse gasses in the Netherlands

  3. Pressurized hydrogen and methane releases

    Energy Technology Data Exchange (ETDEWEB)

    Ruffin, E.; Mouilleau, Y.; Chaineaux, J.

    1996-07-01

    This paper reports on an experimental investigation of the concentration field of supercritical jets of methane and hydrogen. The jets were produced by venting a tank containing gas at a pressure of 40 bars (568 psi) to atmosphere through orifices whose diameters ranged from 25 to 150 mm. The investigation was designed with experiments on a scale typical of that encountered in industry during accidental discharges of pressurised gas, a scale much larger that that normally used in a laboratory. The concentration measurements were made in the subsonic zone of the jets using an original technique. This technique employs a sensor using the catalytic oxidation effects and can measure the concentration of combustible gas in highly reactive environments with no risk of ignition. Ignition tests of the flammable atmospheres and measurements of the aerial pressures had also been performed. The results show that concentration fields of supercritical and subsonic jets are equal if they are weighted by a properly chosen equivalent diameter. Explosion tests show that the over pressures produced by the deflagrations are highly dependent of the ignition point. (author). 6 figs.

  4. Mobility and persistence of methane in groundwater in a controlled-release field experiment

    Science.gov (United States)

    Cahill, Aaron G.; Steelman, Colby M.; Forde, Olenka; Kuloyo, Olukayode; Emil Ruff, S.; Mayer, Bernhard; Ulrich Mayer, K.; Strous, Marc; Cathryn Ryan, M.; Cherry, John A.; Parker, Beth L.

    2017-03-01

    Expansion of shale gas extraction has fuelled global concern about the potential impact of fugitive methane on groundwater and climate. Although methane leakage from wells is well documented, the consequences on groundwater remain sparsely studied and are thought by some to be minor. Here we present the results of a 72-day methane gas injection experiment into a shallow, flat-lying sand aquifer. In our experiment, although a significant fraction of methane vented to the atmosphere, an equal portion remained in the groundwater. We find that methane migration in the aquifer was governed by subtle grain-scale bedding that impeded buoyant free-phase gas flow and led to episodic releases of free-phase gas. The result was lateral migration of gas beyond that expected by groundwater advection alone. Methane persisted in the groundwater zone despite active growth of methanotrophic bacteria, although much of the methane that vented into the vadose zone was oxidized. Our findings demonstrate that even small-volume releases of methane gas can cause extensive and persistent free phase and solute plumes emanating from leaks that are detectable only by contaminant hydrogeology monitoring at high resolution.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  7. Role of Bacteria, Archaea and fungi involved in methane release

    Science.gov (United States)

    Beckmann, Sabrina; Krüger, Martin; Engelen, Bert; Cypionka, Heribert

    2010-05-01

    Abandoned coal mines release substantial amounts of methane which is largely biogenic. The aim of this study was to understand the microbial processes involved in mine-gas formation in two abandoned coal mines in Germany. Therefore, untreated coal- and mine timber samples and anaerobic enrichment cultures derived from them were subjected to DGGE analyses and quantitative PCR. The primers used were specific for Bacteria, Archaea, fungi, and the key functional genes for sulfate reduction (dsrA) and methanogenesis (mcrA). Original samples and enrichment cultures harboured a broad spectrum of facultative aerobes, fermenters, nitrate- and sulfate reducers belonging to all five groups (α - ɛ) of the Proteobacteria, as well as the Bacteroidetes, Tenericutes, Actinobacteria, Chlorobi and Chloroflexi. Only two groups of Archaea (representing 0.01% of the bacterial abundance) were detected. Based on specific 16 S-rRNA primer sets Methanosarcinales comprised 34% of these, corresponding to 45% detected with primers specific for the mcrA gene. The second group (55%) were uncultivated Crenarchaeota with an unknown metabolism. The detected Fungi (Ascomycetes and Basidiomycetes) were typical wood degraders. To get a perception ofdevelop a metabolic model for the ongoing processes, we linked the detected phylogenetic groups to possible activities promoting methane release.

  8. Long-term monitoring of methane release and associated oceanographc setting offshore Svalbard

    Science.gov (United States)

    Dølven, Knut Ola; Ferre, Benedicte; Frank, Carsten; Mienert, Jürgen

    2017-04-01

    Large amounts of methane are stored in the Arctic Ocean sediments, both as free gas and in form of methane hydrates. Warming of Arctic Ocean bottom water can destabilize methane hydrates and cause extensive methane release to the ocean, influencing marine environments (Åström et al., 2016). Previous oceanographic studies have shown a significant methane release from seep-sites offshore western Svalbard, mainly based on hydrographic snapshots and/or echosounder data. These studies have shown that the methane release has significant temporal variations, and these variations can only be investigated properly with ocean observatories. Two K-Lander ocean observatories, developed in collaboration between CAGE and Kontgberg Maritime were deployed at two of these seep sites at 90 and 240 meter depth, from July 2015 to May 2016. Time series obtained from these two observatories include ocean current profiles, temperature, salinity, pressure, as well as dissolved methane and CO2 concentration. The oceanographic data show a clear seasonal variation and indicates that the water column can be significantly affected by atmospheric forcing during winter season. At the same time, methane concentration shows significant temporal variations on both relatively short (hours) and long (seasonal) time scales, with values ranging from 90 to 800 nmol/kg. The short term variations indicates a non-mixed benthic boundary layer with respect to dissolved methane, while the long term variations may indicate seasonal changes in the vertical transport of methane in the water column. Acknowledgements This project is funded by CAGE (Centre for Arctic Gas Hydrate, Environment and Climate), Norwegian Research Council grant no. 223259. Reference Åström, E. Carrol, M. L., Ambrose, W., Carrol, J. "Arctic cold seeps in marine methane hydrate environments: impacts on shelf macrobenthic community structure offshore Svalbard". Marine Ecology Progress Series, 2016 (1616-1599) 552 p. 1-18.

  9. Characteristics of atmospheric non-methane hydrocarbons during haze episode in Beijing, China.

    Science.gov (United States)

    Guo, Songjun; Tan, Jihua; Duan, Jingchun; Ma, Yongliang; Yang, Fumo; He, Kebin; Hao, Jimin

    2012-12-01

    This study firstly focused on non-methane hydrocarbons (NMHCs) during three successive days with haze episode (16-18 August 2006) in Beijing. Concentrations of alkanes, alkenes, aromatic hydrocarbons, and ethyne all peaked at traffic rush hour, implying vehicular emission; and alkanes also peaked at non-traffic rush hour in the daytime, implying additional source. Especially, alkanes and aromatics clearly showed higher levels in the nighttime than that in the daytime, implying their active photochemical reactions in the daytime. Correlation coefficients (R (2)) showed that propane, n-butane, i-butane, ethene, propene, and benzene correlated with ethyne (R (2) = 0.61-0.66), suggesting that their main source is vehicular emission; 2-methylpentane and n-hexane correlated with i-pentane (R (2) = 0.61-0.64), suggesting that gasoline evaporation is their main source; and ethylbezene, m-/p-xylene, and o-xylene correlated with toluene (R (2) = 0.60-0.79), suggesting that their main source is similar to that of toluene (e.g., solvent usage). The R (2) of ethyne, i-pentane, and toluene with total NMHCs were 0.58, 0.76, and 0.60, respectively, indicating that ambient hydrocarbons are associated with vehicular emission, gasoline evaporation, and solvent usage. The sources of other hydrocarbons (e.g., ethane) might be natural gas leakage, biogenic emission, or long-range transport of air pollutants. Measured higher mean B/T ratio (0.78 ± 0.27) was caused by the more intensive photochemical activity of toluene than benzene, still indicating the dominant emission from vehicles.

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

    Science.gov (United States)

    Klapstein, Sara J.; Turetsky, Merritt R.; McGuire, A. David; 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    OpenAIRE

    Sommariva, Roberto; Blake, Robert S.; Cuss, Robert J.; Cordell, Rebecca L.; Jon F. Harrington; 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, ...

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

    OpenAIRE

    Klapstein, SJ; Turetsky, MR; McGuire, AD; Harden, JW; Czimczik, CI; Xu, X.; Chanton, JP; Waddington, JM

    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 (CH 4 ) from surface peat as well as deeper, previously frozen, permafrost carbon (C). We used a network of bubble traps, permanently installed 20cm and 60cm 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 a...

  14. Reduction of Methane Released from Palm Oil Mill Lagoon in Malaysia and Its Countermeasures

    Energy Technology Data Exchange (ETDEWEB)

    Shirai, Y.; Wakisaka, M.; Yacob, S. [Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, 808-0196 Kitakyushu-shi (Japan); Hassan, Mohd Ali [Department of Biotechnology, Faculty of Food Science and Biotechnology, University Putra Malaysia, 43400 UPM Serdang Selangor (Malaysia); Suzuki, S. [EX Corporation, 17-22, Takada 2 chome, Toshima-ku, Tokyo 171-0033 (Japan)

    2003-07-01

    Palm oil industry in Malaysia is one of the potential candidates for the CDM project because large amount of methane is emitted from the lagoons and open digesting tank of the wastewater treatment system. Therefore the first objective of the project is to investigate the actual GHG emission from the lagoons and open digesting tank in palm oil mills in order to establish the baseline for CDM project. Results indicated that methane contribution to biogas released from the open digesting tank and lagoon systems were 35% and 45%, respectively. These values are much lower than the reported value of 65% obtained by complete anaerobic condition of lab-scale experiments. Based on actual methane release measurement and information gathered from palm oil mill about wastewater treatment, significant amount of methane emission to the atmosphere can be reduced with the installation of new closed digesting tank system converted from the open digesting tank such as just by covering it with applying CDM. It is estimated that a total of RM2.6 million could be obtained from the selling of electricity generated from biogas generation and Certified Emission Reduction (CER)

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

    Science.gov (United States)

    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.

  16. Tracking Holocene Methane Release from Alaskan Peatlands using H and C isotope ratios of Biomarkers

    Science.gov (United States)

    Nichols, J. E.; Pavia, F. J.; Peteet, D. M.

    2012-12-01

    We track the carbon and hydrological cycles through the Holocene at each of six locations spanning nearly 12 degrees of latitude in the Alaskan Arctic and Subarctic. Both hydroclimate and vegetation assemblage have a strong influence on the amount of carbon stored in peatlands as well as the amount of methane released. To reconstruct the hydrologic balance of peatlands, we use hydrogen isotope ratios of leaf wax biomarkers extracted from peat. To estimate methane release from peatlands, we use our newly developed method which combines measurements of hydrogen and carbon isotope ratios of leaf wax n-alkanes from Sphangum and vascular plant species. We reconstruct plant assemblages using a combination of macrofossil counts and biomarker distributions. Times of increased evaporative water loss from peatlands, correspond with a takeover of the peatlands by sedges, a decrease in carbon sequestration and incease in methane release. Throughout the Holocene, we find concurrent shifts in the paleohydrology, paleoecology and paleocarbon cycles, indicating that these shifts may be driven by changing climate rather than autogenic processes.

  17. Planetary science: Icy Mars lakes warmed by methane

    Science.gov (United States)

    Fairén, Alberto G.

    2017-10-01

    The release of methane trapped in Martian subsurface reservoirs following planetary obliquity shifts may have contributed to episodic climate warming between 3.6 and 3 billion years ago, explaining evidence for ancient ice-covered lakes.

  18. Ocean circulation promotes methane release from gas hydrate outcrops at the NEPTUNE Canada Barkley Canyon node

    Science.gov (United States)

    Thomsen, Laurenz; Barnes, Christopher; Best, Mairi; Chapman, Ross; Pirenne, Benoît; Thomson, Richard; Vogt, Joachim

    2012-08-01

    The NEPTUNE Canada cabled observatory network enables non-destructive, controlled experiments and time-series observations with mobile robots on gas hydrates and benthic community structure on a small plateau of about 1 km2 at a water depth of 870 m in Barkley Canyon, about 100 km offshore Vancouver Island, British Columbia. A mobile Internet operated vehicle was used as an instrument platform to monitor and study up to 2000 m2 of sediment surface in real-time. In 2010 the first mission of the robot was to investigate the importance of oscillatory deep ocean currents on methane release at continental margins. Previously, other experimental studies have indicated that methane release from gas hydrate outcrops is diffusion-controlled and should be much higher than seepage from buried hydrate in semipermeable sediments. Our results show that periods of enhanced bottom currents associated with diurnal shelf waves, internal semidiurnal tides, and also wind-generated near-inertial motions can modulate methane seepage. Flow dependent destruction of gas hydrates within the hydrate stability field is possible from enhanced bottom currents when hydrates are not covered by either seafloor biota or sediments. The calculated seepage varied between 40-400 μmol CH4 m-2 s-1. This is 1-3 orders of magnitude higher than dissolution rates of buried hydrates through permeable sediments and well within the experimentally derived range for exposed gas hydrates under different hydrodynamic boundary conditions. We conclude that submarine canyons which display high hydrodynamic activity can become key areas of enhanced seepage as a result of emerging weather patterns due to climate change.

  19. Numerical model investigation for potential methane explosion and benzene vapor intrusion associated with high-ethanol blend releases.

    Science.gov (United States)

    Ma, Jie; Luo, Hong; Devaull, George E; Rixey, William G; Alvarez, Pedro J J

    2014-01-01

    Ethanol-blended fuel releases usually stimulate methanogenesis in the subsurface, which could pose an explosion risk if methane accumulates in a confined space above the ground where ignitable conditions exist. Ethanol-derived methane may also increase the vapor intrusion potential of toxic fuel hydrocarbons by stimulating the depletion of oxygen by methanotrophs, and thus inhibiting aerobic biodegradation of hydrocarbon vapors. To assess these processes, a three-dimensional numerical vapor intrusion model was used to simulate the degradation, migration, and intrusion pathway of methane and benzene under different site conditions. Simulations show that methane is unlikely to build up to pose an explosion hazard (5% v/v) if diffusion is the only mass transport mechanism through the deeper vadose zone. However, if methanogenic activity near the source zone is sufficiently high to cause advective gas transport, then the methane indoor concentration may exceed the flammable threshold under simulated conditions. During subsurface migration, methane biodegradation could consume soil oxygen that would otherwise be available to support hydrocarbon degradation, and increase the vapor intrusion potential for benzene. Vapor intrusion would also be exacerbated if methanogenic activity results in sufficiently high pressure to cause advective gas transport in the unsaturated zone. Overall, our simulations show that current approaches to manage the vapor intrusion risk for conventional fuel released might need to be modified when dealing with some high ethanol blend fuel (i.e., E20 up to E95) releases.

  20. Quantifying methane emission from fugitive sources by combining tracer release and downwind measurements – A sensitivity analysis based on multiple field surveys

    DEFF Research Database (Denmark)

    Mønster, Jacob; Samuelsson, Jerker; Kjeldsen, Peter

    2014-01-01

    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...

  1. Limited contribution of permafrost carbon to methane release from thawing peatlands

    Science.gov (United States)

    Cooper, Mark D. A.; Estop-Aragonés, Cristian; Fisher, James P.; Thierry, Aaron; Garnett, Mark H.; Charman, Dan J.; Murton, Julian B.; Phoenix, Gareth K.; Treharne, Rachael; Kokelj, Steve V.; Wolfe, Stephen A.; Lewkowicz, Antoni G.; Williams, Mathew; Hartley, Iain P.

    2017-07-01

    Models predict that thaw of permafrost soils at northern high latitudes will release tens of billions of tonnes of carbon (C) to the atmosphere by 2100 (refs ,,). The effect on the Earth’s climate depends strongly on the proportion of this C that is released as the more powerful greenhouse gas methane (CH4), rather than carbon dioxide (CO2) (refs ,); even if CH4 emissions represent just 2% of the C release, they would contribute approximately one-quarter of the climate forcing. In northern peatlands, thaw of ice-rich permafrost causes surface subsidence (thermokarst) and water-logging, exposing substantial stores (tens of kilograms of C per square meter, ref. ) of previously frozen organic matter to anaerobic conditions, and generating ideal conditions for permafrost-derived CH4 release. Here we show that, contrary to expectations, although substantial CH4 fluxes (>20 g CH4 m-2 yr-1) were recorded from thawing peatlands in northern Canada, only a small amount was derived from previously frozen C (emissions from northern peatlands.

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

    Science.gov (United States)

    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.

  3. Snowcover Influences Upon Episodic Release of Nitrous Oxide from Agricultural Soils During Spring Thaw

    Science.gov (United States)

    Helgason, W.; Farrell, R.; Ens, J.; Lemke, R.; David, C.

    2015-12-01

    In regions where agricultural soils seasonally freeze, such as the Canadian prairies, up to 60-70% of the annual nitrous oxide (N2O) emission can occur during the soil thaw period. The conditions responsible for this episodic release of N2O are poorly understood. In order to elucidate the influencing factors a replicated plot study was conducted in Outlook, Saskatchewan, Canada (51.5°N) during the 2014-2015 winter period. The study compared soil thermal conditions and soil gas fluxes (nitrous oxide and carbon dioxide) from plots that had the snow periodically removed and those on which snow was allowed to accumulate. Soil gas fluxes were measured using an automated chamber system (Gasmet DX4030 FTIR analyzer and Licor Li-8100 chamber system) and analyzer. Soil conditions were continuously monitored throughout the winter and thaw periods. Owing to the insulating effect of snow, the snow free plots were colder during the mid-winter period, but thawed 3-4 days earlier than the snow covered treatment. Following thaw, the snow-free plots were 2-3 degrees warmer than the snow-covered plots for 5-7 days before reaching a similar thermal regime. Due to the differences in the timing of soil thaw and the pre- and post-thaw thermal conditions, cumulative and peak N2O emissions were much higher from the plots that had been kept snow-free. These results suggest that agricultural practices which influence snow redistribution may have an effect upon spring soil gas fluxes. This study also highlights the importance of incorporating snowmelt and soil thaw physics into process-based greenhouse gas models.

  4. Design and test of an artificial reference cow to simulate methane release through exhalation

    NARCIS (Netherlands)

    Wu, Liansun; Groot Koerkamp, P.W.G.; Ogink, N.W.M.

    2015-01-01

    To mitigate methane emission from dairy cows, a technique is needed to evaluate individual methane emission from a large number of cows under practical conditions in barns. For developing such a measurement technique, a known reference source that can simulate cow exhalation of methane would be a

  5. The Use of a Unipore Diffusion Model to Describe the Kinetics of Methane Release from Coal Spoil in the Longwall Environment

    Science.gov (United States)

    Wierzbicki, Mirosław; Skoczylas, Norbert; Kudasik, Mateusz

    2017-06-01

    The unipore methane diffusion model based on the solution of the second Fick's law describes effectively the kinetics of methane release from coal grains. The knowledge of the model describing the kinetics of methane release from coal, the coalbed methane content, the sorption isotherm, the effective diffusion coefficient and the coal particle size distribution, enables the calculation of the volume of methane which is released from the coal spoil as a function of time. These assumptions became the basis for building the software that enables the analysis of methane emissions from coal during the longwall mining. Simulations were performed to determine the temporal and spatial methane inflow to the longwall. The share of methane emission from coal grains (taking into account both the emission kinetics and mass participation) of various classes has been analyzed. The results of the analysis showed that the methane from the small grains, in particular less than 0.1 mm in size, prevails. The mass fraction of these grains in the total weight does not exceed 5%. For the typical parameters determining the mining, geological and technological conditions of methane emissions at different moments of time and position of the longwall were determined.

  6. Global modelling of heat release during initiation and propagation of detonation and deflagration waves in methane-air-particle systems

    Science.gov (United States)

    Tunik, Yu. V.

    In the present paper the direct initiation of a self supporting detonation and propagation of a low-speed combustion in methane-air-coal particles mixtures are solved. For particles, a heterogeneous regime of combustion is used, for methane one overall chemical reaction is taken into account: CH 4 + 2O 2 = CO 2 + 2H 2O. The heat release rate is assumed to be defined as a delay time based on the well-known thermal theory of Frank-Kamenetsky (1967). The proposed model allows one to investigate the influence inert particles or coal dust on the explosion limits of methane-air mixtures. It is shown that the addition of a limited quantity of particles leads to detonation stability. In low speed combustion problems this method allows one to get a good correlation between theoretical and experimental velocities of steady flame propagation in carbon-hydrogen gaseous mixtures. Coal dust influence on gasdynamics of a methane-air mixture combustion is investigated in an unsteady problem by using of the global modelling. It is shown that limited coal dust concentration increases the flame wave intensity in lean methane-air mixtures in contrast to inert particles. In stoichiometric gas mixtures, sand and coal dusts decrease a flame velocity. Far from the ignition point flame, the velocity is largely defined by the dust mass concentration and not by the size of particles.

  7. Episodic release of renin from single isolated superfused rat afferent arterioles

    DEFF Research Database (Denmark)

    Skøtt, O

    1986-01-01

    correspond to calculated values for the renin content of single juxtaglomerular cell granules and the release rates in vivo, respectively. Release activity could be stimulated by an acute decrease in the osmolality of the superfusion medium (-20 mOsm sucrose, n = 14) indicating that an osmotic water movement...... is involved in the secretory process. This study provides functional evidence that renin release is exocytotic. In addition it reports what appears to be the first direct measurement of release of secretory material compatible with secretion of single granules from any secretory system....

  8. A new method for long-term monitoring of Arctic methane release systems - Application offshore NW Svalbard

    Science.gov (United States)

    Ferré, Bénédicte; Dølven, Knut Ola; Silyakova, Anna; Frank, Carsten; Meyer, Mathias; Themann, Sören; Mienert, Jürgen

    2017-04-01

    While the Arctic is warming at a rate of almost twice the global average and needs particular attention for climate impacts, it is a challenging place to perform oceanic measurement, especially in regions of seasonal sea ice cover and stormy seasons. The Centre for Arctic Gas Hydrate, Environment and Climate (CAGE) aims at understanding the impact of methane release on the marine environments and climate change, and one of the strategies relies on monitoring Arctic gas hydrate systems to evaluate the variability of methane release and its dependence on oceanographic changes. Two forefront K-lander observatories, emerging from a collaboration between CAGE and Kongsberg, were successfully deployed and retrieved offshore NW Svalbard in known natural gas release fields (240m and 90m depth), providing eleven months of high-resolution multi-sensor data. Multiple data sets include ocean temperature, salinity, oxygen, dissolved methane and CO2, fluorescence, turbidity as well as ocean current and underwater acoustic measurements. Development and implementation of such cross-disciplinary technology and data analysis brings the marine and maritime research technology fields to the forefront of environmental studies to understand global change and its impacts. This project is funded by CAGE (Centre for Arctic Gas Hydrate, Environment and Climate), Norwegian Research Council grant no. 223259.

  9. Temperature-Induced Increase in Methane Release from Peat Bogs: A Mesocosm Experiment

    NARCIS (Netherlands)

    van Winden, J.F.; Reichart, G.J.; McNamara, N.P.; Benthien, A.; Sinninghe Damsté, J.S.

    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

  10. Temperature-induced increase in methane release from peat bogs: A mesocosm experiment

    NARCIS (Netherlands)

    Winden, J.F. van; Reichart, G.-J.; McNamara, N.P.; Benthien, A.; Sinninghe Damsté, J.S.

    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

  11. Coated pellets with delayed-release glucose for prevention of hypoglycemic episodes

    Directory of Open Access Journals (Sweden)

    Sabadková Dana

    2016-06-01

    Full Text Available Patients tend to prevent hypoglycemia by excessive saccharide intake leading to poorer glycemic control with potentially fatal consequences. This problem could be resolved by means of pellets with glucose release delayed by 120–360 min as a compensation of the antidiabetic drug peak effect. No glucose is released before; hence there is no risk of hyperglycemia and secondary complications. The pellets contain glucose in combination with an osmotically active ingredient and are coated with an ethylcellulose dispersion, which forms an insoluble semipermeable membrane and ensures delayed release. The release of glucose was assessed using dissolution and high-performance liquid chromatography. Dissolution profiles indicated the possibility of achieving the requested lag time using a combination of adequate compositions and coating concentrations. Lag times of 60, 240 and 360 min were achieved. The sample containing carboxymethyl starch was found to be most suitable for the intent of this work.

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

    Science.gov (United States)

    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

  13. Large methane releases lead to strong aerosol forcing and reduced cloudiness

    DEFF Research Database (Denmark)

    Kurten, T.; Zhou, L.; Makkonen, R.

    2011-01-01

    contributions from the associated carbon dioxide or ozone increases. Here, we study the effect of strongly elevated methane (CH4) levels on oxidant and aerosol particle concentrations using a combination of chemistry-transport and general circulation models. A 10-fold increase in methane concentrations...... is predicted to significantly decrease hydroxyl radical (OH) concentrations, while moderately increasing ozone (O-3). These changes lead to a 70% increase in the atmospheric lifetime of methane, and an 18% decrease in global mean cloud droplet number concentrations (CDNC). The CDNC change causes a radiative...

  14. LBA-ECO LC-07 Methane Releases from Two Amazon Hydroreservoirs, Brazil: 2000-2001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set reports methane (CH4) fluxes at the water-air interface and concentrations and isotopic signals of CH4 in the bubbles stirred up from the sediment in...

  15. Possible causes of methane release from the East Arctic seas shelf

    Directory of Open Access Journals (Sweden)

    O. A. Anisimov

    2014-01-01

    Full Text Available We analyze data on methane concentration in the water and lower atmosphere over the shelf of the East Siberian Arctic Seas, which were obtained using marine, terrestrial, and satellite observations. Our study is targeted towards attribution of the enhanced concentrations of methane above the latitudinal-mean, which have been detected at selected locations of these seas. We compare two hypothesis, which attribute it to the effect of modern changes of the sub aquatic permafrost, and to geological factors (tectonics, presence of fault zones and paleo river beds in the study region. Our analysis showed that the methane concentration in sea water are directly related to the distance to the nearest fault zone or paleo river bed, where permafrost is absent and bottom sediments are perforated allowing methane to escape from the deep layers containing gas hydrates. This result indicate that the enhanced emission of methane, which was observed at selected locations of the shelf, is not related to the modern climate change. Earlier study, which was based on mathematical modeling, did not find intensive development of taliks as well as other processes that lead to increased gas permeability of the bottom sediments. Taken together, these results reject the hypothesis of methane catastrophe on the East Siberian Arctic Seas shelf over the foreseeable future.

  16. Methane clathrates in the solar system.

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  18. Arctic methane

    NARCIS (Netherlands)

    Dyupina, E.; Amstel, van A.R.

    2013-01-01

    What are the risks of a runaway greenhouse effect from methane release from hydrates in the Arctic? In January 2013, a dramatic increase of methane concentration up to 2000 ppb has been measured over the Arctic north of Norway in the Barents Sea. The global average being 1750 ppb. It has been

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

    Science.gov (United States)

    S.J. Klapstein; M.R. Turetsky; A.D. McGuire; J.W. Harden; C.I. Czimczik; X. Xu; J.P. Chanton; J.M. Waddington

    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...

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

    Science.gov (United States)

    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.

  1. An experimental model of episodic gas release through fracture of fluid confined within a pressurized elastic reservoir

    Science.gov (United States)

    Rocco, Stefano; Woods, Andrew W.; Harrington, Jon; Norris, Simon

    2017-01-01

    We present new experiments that identify a mechanism for episodic release of gas from a pressurized, deformable reservoir confined by a clay seal, as a result of the transition from bulk deformation to channel growth through the clay. Air is injected into the center of a thin cylindrical cell initially filled with a mixture of bentonite clay and water. For sufficiently dry mixtures, the pressure initially increases with little volume change. On reaching the yield stress of the clay-water mixture, the lid of the cell then deforms elastically and an air-filled void forms in the center of the cell as the clay is driven radially outward. With continued supply of air, the pressure continues to increase until reaching the fracture strength of the clay. A fracture-like channel then forms and migrates to the outer edge of the cell, enabling the air to escape. The pressure then falls, and the clay flows back toward the center of the cell and seals the channel so the cycle can repeat. The phenomena may be relevant at mud volcanoes.

  2. Safety assessment for proposed pump mixing operations to mitigate episodic gas releases in tank 241-101-SY: Hanford Site, Richland, Washington

    Energy Technology Data Exchange (ETDEWEB)

    Lentsch, J.W., Westinghouse Hanford

    1996-05-16

    This safety assessment addresses each of the elements required for the proposed action to remove a slurry distributor and to install, operate, and remove a mixing pump in Tank 241-SY-101, which is located within the Hanford Site, Richland, Washington. The proposed action is required as part of an ongoing evaluation of various mitigation concepts developed to eliminate episodic gas releases that result in hydrogen concentrations in the tank dome space that exceed the lower flammability limit.

  3. A safety assessment for proposed pump mixing operations to mitigate episodic gas releases in tank 241-SY-101: Hanford Site,Richland, Washington

    Energy Technology Data Exchange (ETDEWEB)

    Lentsch, J.W.

    1996-07-01

    This safety assessment addresses each of the elements required for the proposed action to remove a slurry distributor and to install, operate, and remove a mixing pump in Tank 241-SY-101,which is located within the Hanford Site, Richland, Washington.The proposed action is required as part of an ongoing evaluation of various mitigation concepts developed to eliminate episodic gas releases that result in hydrogen concentrations in the tank dome space that exceed the lower flammability limit.

  4. Statistical atmospheric inversion of local gas emissions by coupling the tracer release technique and local-scale transport modelling: a test case with controlled methane emissions

    Directory of Open Access Journals (Sweden)

    S. Ars

    2017-12-01

    Full Text Available This study presents a new concept for estimating the pollutant emission rates of a site and its main facilities using a series of atmospheric measurements across the pollutant plumes. This concept combines the tracer release method, local-scale atmospheric transport modelling and a statistical atmospheric inversion approach. The conversion between the controlled emission and the measured atmospheric concentrations of the released tracer across the plume places valuable constraints on the atmospheric transport. This is used to optimise the configuration of the transport model parameters and the model uncertainty statistics in the inversion system. The emission rates of all sources are then inverted to optimise the match between the concentrations simulated with the transport model and the pollutants' measured atmospheric concentrations, accounting for the transport model uncertainty. In principle, by using atmospheric transport modelling, this concept does not strongly rely on the good colocation between the tracer and pollutant sources and can be used to monitor multiple sources within a single site, unlike the classical tracer release technique. The statistical inversion framework and the use of the tracer data for the configuration of the transport and inversion modelling systems should ensure that the transport modelling errors are correctly handled in the source estimation. The potential of this new concept is evaluated with a relatively simple practical implementation based on a Gaussian plume model and a series of inversions of controlled methane point sources using acetylene as a tracer gas. The experimental conditions are chosen so that they are suitable for the use of a Gaussian plume model to simulate the atmospheric transport. In these experiments, different configurations of methane and acetylene point source locations are tested to assess the efficiency of the method in comparison to the classic tracer release technique in coping

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

    Science.gov (United States)

    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

  6. On-farm methane measurements during milking correlate with total methane production by individual dairy cows

    OpenAIRE

    Garnsworthy, P. C.; Craigon, J.; Hernandez-Medrano, J.H.; Saunders, N.

    2012-01-01

    The objective of this study was to investigate whether measurement of methane emissions by individual dairy cows during milking could provide a useful technique for monitoring on-farm methane emissions. To quantify methane emissions from individual cows on farm, we developed a novel technique based on sampling air released by eructation during milking. Eructation frequency and methane released per eructation were used to estimate methane emission rate. For 82 cows, methane emission rate durin...

  7. Methane and Climate Change

    NARCIS (Netherlands)

    Reay, D.; Smith, P.; Amstel, van A.R.

    2010-01-01

    Methane is a powerful greenhouse gas and is estimated to be responsible for approximately one-fifth of man-made global warming. Per kilogram, it is 25 times more powerful than carbon dioxide over a 100-year time horizon -- and global warming is likely to enhance methane release from a number of

  8. Reversing methanogenesis to capture methane for liquid biofuel precursors

    National Research Council Canada - National Science Library

    Soo, Valerie W C; McAnulty, Michael J; Tripathi, Arti; Zhu, Fayin; Zhang, Limin; Hatzakis, Emmanuel; Smith, Philip B; Agrawal, Saumya; Nazem-Bokaee, Hadi; Gopalakrishnan, Saratram; Salis, Howard M; Ferry, James G; Maranas, Costas D; Patterson, Andrew D; Wood, Thomas K

    2016-01-01

    Energy from remote methane reserves is transformative; however, unintended release of this potent greenhouse gas makes it imperative to convert methane efficiently into more readily transported biofuel...

  9. Down the Rabbit Hole: toward appropriate discussion of methane release from gas hydrate systems during the Paleocene-Eocene thermal maximum and other past hyperthermal events

    Directory of Open Access Journals (Sweden)

    G. R. Dickens

    2011-08-01

    Full Text Available Enormous amounts of 13C-depleted carbon rapidly entered the exogenic carbon cycle during the onset of the Paleocene-Eocene thermal maximum (PETM, as attested to by a prominent negative carbon isotope (δ13C excursion and deep-sea carbonate dissolution. A widely cited explanation for this carbon input has been thermal dissociation of gas hydrate on continental slopes, followed by release of CH4 from the seafloor and its subsequent oxidation to CO2 in the ocean or atmosphere. Increasingly, papers have argued against this mechanism, but without fully considering existing ideas and available data. Moreover, other explanations have been presented as plausible alternatives, even though they conflict with geological observations, they raise major conceptual problems, or both. Methane release from gas hydrates remains a congruous explanation for the δ13C excursion across the PETM, although it requires an unconventional framework for global carbon and sulfur cycling, and it lacks proof. These issues are addressed here in the hope that they will prompt appropriate discussions regarding the extraordinary carbon injection at the start of the PETM and during other events in Earth's history.

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

    Science.gov (United States)

    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...

  11. Quetiapine extended release versus aripiprazole in children and adolescents with first-episode psychosis: the multicentre, double-blind, randomised tolerability and efficacy of antipsychotics (TEA) trial.

    Science.gov (United States)

    Pagsberg, Anne Katrine; Jeppesen, Pia; Klauber, Dea Gowers; Jensen, Karsten Gjessing; Rudå, Ditte; Stentebjerg-Olesen, Marie; Jantzen, Peter; Rasmussen, Simone; Saldeen, Eva Ann-Sofie; Lauritsen, Maj-Britt Glenn; Bilenberg, Niels; Stenstrøm, Anne Dorte; Nyvang, Louise; Madsen, Sarah; Werge, Thomas M; Lange, Theis; Gluud, Christian; Skoog, Maria; Winkel, Per; Jepsen, Jens Richardt M; Fagerlund, Birgitte; Correll, Christoph U; Fink-Jensen, Anders

    2017-08-01

    Head-to-head trials to guide antipsychotic treatment choices for paediatric psychosis are urgently needed because extrapolations from adult studies might not be implementable. In this superiority trial with two-sided significance testing, we aimed to compare the efficacy and safety of quetiapine-extended release (quetiapine-ER) versus aripiprazole in children and adolescents with first-episode psychosis, to determine whether differences between the two treatments were sufficient to guide clinicians in their choice of one drug over the other. In this multicentre, double-blind, randomised trial in seven Danish university clinics, we recruited children and adolescents aged 12-17 years with a diagnosis of ICD-10 schizophrenia-spectrum disorder, delusional disorder, or affective-spectrum psychotic disorder, and psychotic symptoms scoring at least 4 on at least one of the following Positive and Negative Syndrome Scale (PANSS) items: P1 (delusions), P2 (conceptual disorganisation), P3 (hallucinations), P5 (grandiosity), P6 (suspiciousness/persecution), and G9 (unusual thought content), and a total PANSS score greater than 60. Patients were randomly assigned (1:1) to 12 weeks of treatment with target doses of 600 mg/day of quetiapine-ER (starting from 50 mg/day) or 20 mg/day of aripiprazole (starting from 2·5 mg/day). The assigned drug was titrated over five levels, with 2 days at each dose, and the final dose achieved on day 9. Randomisation was done using a computer-generated concealed sequence with a block size of 8, and stratified by baseline PANSS positive score (≤20 points or >20 points) and age (12-14 years or 15-17 years). Study drugs were administered in identical capsules, and interventions, assessments, and data analysis were done masked. The primary outcome was PANSS positive score. Key adverse outcomes were bodyweight, homoeostatic model of insulin resistance (HOMA-IR), akathisia, and sedation. Analyses were by intention to treat. This study is registered

  12. Methane Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Methane (CH4) flux is the net rate of methane exchange between an ecosystem and the atmosphere. Data of this variable were generated by the USGS LandCarbon project...

  13. Genomic selection for methane emission

    DEFF Research Database (Denmark)

    de Haas, Yvette; Pryce, Jennie E; Wall, Eileen

    2016-01-01

    Climate change is a growing area of international concern, and it is well established that the release of greenhouse gases (GHG) is a contributing factor. Of the various GHG produced by ruminants, enteric methane (CH4 ) is the most important contributor. One mitigation strategy is to reduce methane...... emission through genetic selection. Our first attempt used beef cattle and a GWAS to identify genes associated with several CH4 traits in Angus beef cattle. The Angus population consisted of 1020 animals with phenotypes on methane production (MeP), dry matter intake (DMI), and weight (WT). Additionally......, two new methane traits: residual genetic methane (RGM) and residual phenotypic methane (RPM) were calculated by adjusting CH4 for DMI and WT. Animals were genotyped using the 800k Illumina Bovine HD Array. Estimated heritabilities were 0.30, 0.19 and 0.15 for MeP, RGM and RPM respectively...

  14. Permafrost thaw: Methane origins

    Science.gov (United States)

    Bridgham, Scott D.

    2017-07-01

    Permafrost soils represent a massive pool of organic carbon that could be released to the atmosphere due to future climate change. A study now shows that previously frozen soil carbon contained in peatlands may make a relatively modest contribution to future methane emissions following permafrost thaw.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kirchman, David L. [Univ. of Delaware, Lewes, DE (United States)

    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

  16. Episodic Social Stress-Escalated Cocaine Self-Administration: Role of Phasic and Tonic Corticotropin Releasing Factor in the Anterior and Posterior Ventral Tegmental Area

    Science.gov (United States)

    Boyson, Christopher O.; Montagud-Romero, Sandra; Stein, Dirson J.; Gobrogge, Kyle L.; DeBold, Joseph F.; Miczek, Klaus A.

    2016-01-01

    Intermittent social defeat stress escalates later cocaine self-administration. Reward and stress both activate ventral tegmental area (VTA) dopamine neurons, increasing downstream extracellular dopamine concentration in the medial prefrontal cortex and nucleus accumbens. The stress neuropeptide corticotropin releasing factor (CRF) and its receptors (CRF-R1, CRF-R2) are located in the VTA and influence dopaminergic activity. These experiments explore how CRF release and the activation of its receptors within the VTA both during and after stress influence later cocaine self-administration in rats. In vivo microdialysis of CRF in the VTA demonstrated that CRF is phasically released in the posterior VTA (pVTA) during acute defeat, but, with repeated defeat, CRF is recruited into the anterior VTA (aVTA) and CRF tone is increased in both subregions. Intra-VTA antagonism of CRF-R1 in the pVTA and CRF-R2 in the aVTA during each social defeat prevented escalated cocaine self-administration in a 24 h “binge.” VTA CRF continues to influence cocaine seeking in stressed animals long after social defeat exposure. Unlike nonstressed controls, previously stressed rats show significant cocaine seeking after 15 d of forced abstinence. Previously stressed rats continue to express elevated CRF tone within the VTA and antagonism of pVTA CRF-R1 or aVTA CRF-R2 reverses cocaine seeking. In conclusion, these experiments demonstrate neuroadaptive changes in tonic and phasic CRF with repeated stress, that CRF release during stress may contribute to later escalated cocaine taking, and that persistently elevated CRF tone in the VTA may drive later cocaine seeking through increased activation of pVTA CRF-R1 and aVTA CRF-R2. SIGNIFICANCE STATEMENT Corticotropin releasing factor (CRF) within the ventral tegmental area (VTA) has emerged as a likely candidate molecule underlying the fundamental link between stress history and escalated drug self-administration. However, the nature of CRF

  17. Combustion of Methane Hydrate

    Science.gov (United States)

    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

  18. Mechanical instability of monocrystalline and polycrystalline methane hydrates

    NARCIS (Netherlands)

    Wu, J.; Ning, F.; Trinh, T.T.; Kjelstrup, S.; Vlugt, T.J.H.; He, J.; Skallerud, B.H.; Zhang, Z.

    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

  19. [Amnestic episodes].

    Science.gov (United States)

    Riedmann, G; Lindner, M; Barolin, G S

    1988-12-31

    Amnesic episodes, by no means infrequent occurrences, are likely to trigger off anxiety in the patient and to evade adequate diagnostic interpretation. They consist of an isolated disturbance of short-term memory, manifesting itself as a permanent memory gap. The clinical features may vary from a conspicuous behaviour with stereotype repetition of questions to a completely inconspicuous picture with flawless execution of even highly differentiated behaviour patterns. The vegetative state may either be completely undisturbed or vary from mild impairment with nausea and vertigo to marked vegetative disorder. We are advocating a classification in 3 groups: a) "Genuine" amnesic states as symptoms of impaired blood flow in the basilar system in the absence of other etiological clues. b) "Symptomatic" amnesic episodes with tangible pathogenic factors, such as injury of the head and cervical spine, epilepsy, intoxication with various agents. The "genuine" amnesic states can also be regarded as transitory ischemic attacks of the basilar system. They show the following criteria: preponderance in females beyond middle age, duration of several hours, relatively high frequency of vascular risk factors and degenerative changes in the cervical spine, often triggered off by stress on the cervical spine, low tendency towards recurrence, general clinical benignity. In consequence, we stress the importance of etiological clarification before the onset of therapy. After the diagnosis of "genuine" amnesic state has been established, treatment has to be in accordance with the principles of basilar stroke therapy with subsequent vascular prophylaxis. Nevertheless, because of possible therapeutic or forensic consequences, the "symptomatic" states have to be kept in mind.

  20. Evidence for Methane Escape from the Free Gas Zone on the Blake Ridge

    Science.gov (United States)

    Holbrook, W. S.; Gorman, A. R.; Hornbach, M. J.; Hackwith, K. L.; Lizarralde, D.; Pecher, I. A.

    2001-12-01

    Methane hydrate, a solid form of methane and water that is widespread in continental margin sediments, comprises a large reservoir organic carbon in the Earth, but its role in global carbon cycles remains uncertain. Hydrate has been linked to several episodes of paleoceanographic and climate change through its signature of isotopically light carbon. Proposed mechanisms of methane release from hydrate reservoirs generally invoke large-scale sediment failure, sea-level changes, or thermal dissociation of hydrate via warming of bottom water. Seismic data acquired on the Blake Ridge in Fall 2000 suggest a new mechanism by which methane gas was expelled directly from the free gas zone, without thermal or mechanical disruption of the overlying hydrate layer. Strong evidence for gas expulsion into the ocean/atmosphere system exists at the Blake Ridge Depression (BRD), which was previously interpreted as a structural collapse and large-scale sediment blow-out. Our new data indicate that the depression is not a structural collapse, but rather a construct of large-scale sediment waves formed entirely by deposition and erosion. At the edge of the BRD, seafloor erosion exposes older, faulted strata, creating permeable pathways connecting free gas beneath the BSR to the seafloor. The disappearance of free gas at these locations strongly suggests that free gas escaped along these pathways. Stratigraphic and sulfate gradient constraints suggest that the gas escaped sometime after 1.5 Ma but is not leaking out at present. The amount of missing methane, 0.6 Gt, is equivalent to approximately 15% of total present-day atmospheric methane. Our results imply that significant amounts of methane gas can bypass the hydrate stability zone and be expelled directly into the ocean/atmosphere system. We suggest that widespread seafloor erosion, for example following changes in thermohaline circulation patterns, may be an important mechanism for allowing methane to escape directly from the free

  1. On-farm methane measurements during milking correlate with total methane production by individual dairy cows.

    Science.gov (United States)

    Garnsworthy, P C; Craigon, J; Hernandez-Medrano, J H; Saunders, N

    2012-06-01

    The objective of this study was to investigate whether measurement of methane emissions by individual dairy cows during milking could provide a useful technique for monitoring on-farm methane emissions. To quantify methane emissions from individual cows on farm, we developed a novel technique based on sampling air released by eructation during milking. Eructation frequency and methane released per eructation were used to estimate methane emission rate. For 82 cows, methane emission rate during milking increased with daily milk yield (r = 0.71), but varied between individuals with the same milk yield and fed the same diet. For 12 cows, methane emission rate recorded during milking on farm showed a linear relationship (R² = 0.79) with daily methane output by the same cows when housed subsequently in respiration chambers. For 42 cows, the methane emission rate during milking was greater on a feeding regimen designed to produce high methane emissions, and the increase compared with a control regimen was similar to that observed for cows in respiration chambers. It was concluded that, with further validation, on-farm monitoring of methane emission rate during milking could provide a low-cost reliable method to estimate daily methane output by individual dairy cows, which could be used to study variation in methane, to identify cows with low emissions, and to test outcomes of mitigation strategies. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  2. Thermal properties of methane gas hydrates

    Science.gov (United States)

    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

  3. Response of the Black Sea methane budget to massive short-term submarine inputs of methane

    Directory of Open Access Journals (Sweden)

    O. Schmale

    2011-04-01

    Full Text Available A steady state box model was developed to estimate the methane input into the Black Sea water column at various water depths. Our model results reveal a total input of methane of 4.7 Tg yr−1. The model predicts that the input of methane is largest at water depths between 600 and 700 m (7% of the total input, suggesting that the dissociation of methane gas hydrates at water depths equivalent to their upper stability limit may represent an important source of methane into the water column. In addition we discuss the effects of massive short-term methane inputs (e.g. through eruptions of deep-water mud volcanoes or submarine landslides at intermediate water depths on the water column methane distribution and the resulting methane emission to the atmosphere. Our non-steady state simulations predict that these inputs will be effectively buffered by intense microbial methane consumption and that the upward flux of methane is strongly hampered by the pronounced density stratification of the Black Sea water column. For instance, an assumed input of methane of 179 Tg CH4 d−1 (equivalent to the amount of methane released by 1000 mud volcano eruptions at a water depth of 700 m will only marginally influence the sea/air methane flux increasing it by only 3%.

  4. Quantification of methane emissions from danish landfills

    DEFF Research Database (Denmark)

    Scheutz, Charlotte; Mønster, Jacob; Kjeldsen, Peter

    2013-01-01

    Whole-landfill methane emission was quantified using a tracer technique that combines controlled tracer gas release from the landfill with time-resolved concentration measurements downwind of the landfill using a mobile high-resolution analytical instrument. Methane emissions from 13 Danish...... landfills varied between 2.6 and 60.8 kg CH4 h–1. The highest methane emission was measured at the largest (in terms of disposed waste amounts) of the 13 landfills, whereas the lowest methane emissions (2.6-6.1 kgCH4 h–1) were measured at the older and smaller landfills. At two of the sites, which had gas...

  5. Landscape-level terrestrial methane flux observed from a very tall tower

    Science.gov (United States)

    Ankur R. Desai; Ke Xu; Hanqin Tian; Peter Weishampel; Jonathan Thom; Dan Baumann; Arlyn E. Andrews; Druce D. Cook; Jennifer Y. King; Randall. Kolka

    2015-01-01

    Simulating the magnitude and variability of terrestrial methane sources and sinks poses a challenge to ecosystem models because the biophysical and biogeochemical processes that lead to methane emissions from terrestrial and freshwater ecosystems are, by their nature, episodic and spatially disjunct. As a consequence, model predictions of regional methane emissions...

  6. Modeling the fate of methane hydrates under global warming

    OpenAIRE

    Kretschmer, Kerstin; Biastoch, Arne; Rüpke, Lars; Burwicz, Ewa

    2015-01-01

    Large amounts of methane hydrate locked up within marine sediments are vulnerable to climate change. Changes in bottom water temperatures may lead to their destabilization and the release of methane into the water column or even the atmosphere. In a multimodel approach, the possible impact of destabilizing methane hydrates onto global climate within the next century is evaluated. The focus is set on changing bottom water temperatures to infer the response of the global methane hydrate invento...

  7. Aquatic herbivores facilitate the emission of methane from wetlands.

    Science.gov (United States)

    Dingemans, Bas J J; Bakker, Elisabeth S; Bodelier, Paul L E

    2011-05-01

    Wetlands are significant sources of atmospheric methane. Methane produced by microbes enters roots and escapes to the atmosphere through the shoots of emergent wetland plants. Herbivorous birds graze on helophytes, but their effect on methane emission remains unknown. We hypothesized that grazing on shoots of wetland plants can modulate methane emission from wetlands. Diffusive methane emission was monitored inside and outside bird exclosures, using static flux chambers placed over whole vegetation and over single shoots. Both methods showed significantly higher methane release from grazed vegetation. Surface-based diffusive methane emission from grazed plots was up to five times higher compared to exclosures. The absence of an effect on methane-cycling microbial processes indicated that this modulating effect acts on the gas transport by the plants. Modulation of methane emission by animal-plant-microbe interactions deserves further attention considering the increasing bird populations and changes in wetland vegetation as a consequence of changing land use and climate change.

  8. Landfill Methane

    Science.gov (United States)

    Landfill methane (CH4) accounts for approximately 1.3% (0.6 Gt) of global anthropogenic greenhouse gas emissions relative to total emissions from all sectors of about 49 Gt CO2-eq yr-1. For countries with a history of controlled landfilling, landfills can be one of the larger national sources of ant...

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

    Directory of Open Access Journals (Sweden)

    Kirsten Oswald

    Full Text Available 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.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  12. Sediment trapping by dams creates methane emission hot spots

    DEFF Research Database (Denmark)

    Maeck, A.; Delsontro, T.; McGinnis, Daniel F.

    2013-01-01

    Inland waters transport and transform substantial amounts of carbon and account for similar to 18% of global methane emissions. Large reservoirs with higher areal methane release rates than natural waters contribute significantly to freshwater emissions. However, there are millions of small dams...... worldwide that receive and trap high loads of organic carbon and can therefore potentially emit significant amounts of methane to the atmosphere. We evaluated the effect of damming on methane emissions in a central European impounded river. Direct comparison of riverine and reservoir reaches, where...... reservoirs or rivers. We show that sediment accumulation correlates with methane production and subsequent ebullitive release rates and may therefore be an excellent proxy for estimating methane emissions from small reservoirs. Our results suggest that sedimentation-driven methane emissions from dammed river...

  13. Coalbed Methane Outreach Program

    Science.gov (United States)

    Coalbed Methane Outreach Program, voluntary program seeking to reduce methane emissions from coal mining activities. CMOP promotes profitable recovery/use of coal mine methane (CMM), addressing barriers to using CMM instead of emitting it to atmosphere.

  14. methanes and di-bis(indolyl)methanes

    African Journals Online (AJOL)

    a

    INDOLYL)METHANES AND DI-BIS(INDOLYL)METHANES. Alireza Hasaninejad1*, Abdolkarim Zare2*, Hashem Sharghi3, Reza Khalifeh3 and Ahmad Reza. Moosavi Zare3. 1Department of Chemistry, Faculty of Sciences, Persian Gulf University ...

  15. Tracking the MSL-SAM methane detection source location Through Mars Regional Atmospheric Modeling System (MRAMS)

    Science.gov (United States)

    Pla-García, Jorge

    2016-04-01

    1. Introduction: The putative in situ detection of methane by Sample Analysis at Mars (SAM) instrument suite on Curiosi-ty at Gale crater has garnered significant attention because of the potential implications for the presence of geological methane sources or indigenous Martian organisms [1, 2]. SAM reported detection of back-ground levels of atmospheric methane of mean value 0.69±0.25 parts per billion by volume (ppbv) at the 95% confidence interval (CI). Additionally, in four sequential measurements spanning a 60-sol period, SAM observed elevated levels of methane of 7.2±2.1 ppbv (95% CI), implying that Mars is episodically producing methane from an additional unknown source. There are many major unresolved questions regard-ing this detection: 1) What are the potential sources of the methane release? 2) What causes the rapid decrease in concentration? and 3) Where is the re-lease location? 4) How spatially extensive is the re-lease? 5) For how long is CH4 released? Regarding the first question, the source of methane, is so far not identified. It could be related with geo-logical process like methane release from clathrates [3], serpentinisation [4] and volcanism [5]; or due to biological activity from methanogenesis [6]. To answer the second question, the rapid decrease in concentration, it is important to note that the photo-chemical lifetime of methane is of order 100 years, much longer than the atmospheric mixing time scale, and thus the gas should tend to be well mixed except near a source or shortly after an episodic release. The observed spike of 7 ppb from the background of explain the observed fast destruction of methane [7]. In an effort to better address the potential mixing and remaining questions, atmospheric circulation studies of Gale Crater were performed with the Mars Re-gional Atmospheric Modeling System (MRAMS). The model was focused on rover locations using nested grids with a spacing of 330 meters on the in-nermost grid that is centered

  16. Assessment of wet explosion as a pretreatment method to enhance methane production from agricultural residues and energy crops

    DEFF Research Database (Denmark)

    Wang, Guangtao; Gavala, Hariklia N.; Skiadas, Ioannis

    2011-01-01

    L of methane per g of TS. Pre-treated straw and miscanthus gave lower methane yield compared to the methane obtained from the raw biomasses, while pre-treated willow yielded approximately 62% more methane than raw willow. Experimental results also showed that increased sugars release after pretreatment does...

  17. Small Molecule Catalysts for Harvesting Methane Gas

    Energy Technology Data Exchange (ETDEWEB)

    Baker, S. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ceron-Hernandez, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Oakdale, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lau, E. Y. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-12-06

    As the average temperature of the earth increases the impact of these changes are becoming apparent. One of the most dramatic changes to the environment is the melting of arctic permafrost. The disappearance of the permafrost has resulted in release of streams of methane that was trapped in remote areas as gas hydrates in ice. Additionally, the use of fracking has also increased emission of methane. Currently, the methane is either lost to the atmosphere or flared. If these streams of methane could be brought to market, this would be an abundant source of revenue. A cheap conversion of gaseous methane to a more convenient form for transport would be necessary to economical. Conversion of methane is a difficult reaction since the C-H bond is very stable (104 kcal/mole). At the industrial scale, the Fischer-Tropsch reaction can be used to convert gaseous methane to liquid methanol but is this method is impractical for these streams that have low pressures and are located in remote areas. Additionally, the Fischer-Tropsch reaction results in over oxidation of the methane leading to many products that would need to be separated.

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

    Science.gov (United States)

    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 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. Methane hydrate stability and anthropogenic climate change

    Directory of Open Access Journals (Sweden)

    D. Archer

    2007-07-01

    Full Text Available Methane frozen into hydrate makes up a large reservoir of potentially volatile carbon below the sea floor and associated with permafrost soils. This reservoir intuitively seems precarious, because hydrate ice floats in water, and melts at Earth surface conditions. The hydrate reservoir is so large that if 10% of the methane were released to the atmosphere within a few years, it would have an impact on the Earth's radiation budget equivalent to a factor of 10 increase in atmospheric CO2.

    Hydrates are releasing methane to the atmosphere today in response to anthropogenic warming, for example along the Arctic coastline of Siberia. However most of the hydrates are located at depths in soils and ocean sediments where anthropogenic warming and any possible methane release will take place over time scales of millennia. Individual catastrophic releases like landslides and pockmark explosions are too small to reach a sizable fraction of the hydrates. The carbon isotopic excursion at the end of the Paleocene has been interpreted as the release of thousands of Gton C, possibly from hydrates, but the time scale of the release appears to have been thousands of years, chronic rather than catastrophic.

    The potential climate impact in the coming century from hydrate methane release is speculative but could be comparable to climate feedbacks from the terrestrial biosphere and from peat, significant but not catastrophic. On geologic timescales, it is conceivable that hydrates could release as much carbon to the atmosphere/ocean system as we do by fossil fuel combustion.

  20. Ductile flow of methane hydrate

    Science.gov (United States)

    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.

  1. Investigating observational constraints on the contemporary methane budget

    NARCIS (Netherlands)

    Monteil, G.A.|info:eu-repo/dai/nl/325811164

    2014-01-01

    Methane (CH4) is an important greenhouse gas, naturally produced by bio-degradation of organic material (mainly in wetlands), by continuous and eruptive releases from mud volcanoes, and by combustion of organic material in forest and peat fires. Large quantities of methane are also emitted by human

  2. Revisiting factors controlling methane emissions from high-Arctic tundra

    DEFF Research Database (Denmark)

    Mastepanov, M.; Sigsgaard, C.; Tagesson, T.

    2013-01-01

    The northern latitudes are experiencing disproportionate warming relative to the mid-latitudes, and there is growing concern about feedbacks between this warming and methane production and release from high-latitude soils. Studies of methane emissions carried out in the Arctic, particularly those...

  3. Predicting methane emission of dairy cows using milk composition

    NARCIS (Netherlands)

    Gastelen, van Sanne

    2017-01-01

    Enteric methane (CH4) is produced as a result of microbial fermentation of feed components in the gastrointestinal tract of ruminant livestock. Methane has no nutritional value for the animal and is predominately released into the environment through eructation and breath.

  4. Methane Hydrate Field Program. Development of a Scientific Plan for a Methane Hydrate-Focused Marine Drilling, Logging and Coring Program

    Energy Technology Data Exchange (ETDEWEB)

    Collett, Tim [U.S. Geological Survey, Boulder, CO (United States); Bahk, Jang-Jun [Korea Inst. of Geoscience and Mineral Resources, Daejeon (Korea); Frye, Matt [U.S. Bureau of Ocean Energy Management, Sterling, VA (United States); Goldberg, Dave [Lamont-Doherty Earth Observatory, Palisades, NY (United States); Husebo, Jarle [Statoil ASA, Stavenger (Norway); Koh, Carolyn [Colorado School of Mines, Golden, CO (United States); Malone, Mitch [Texas A & M Univ., College Station, TX (United States); Shipp, Craig [Shell International Exploration and Production Inc., Anchorage, AK (United States); Torres, Marta [Oregon State Univ., Corvallis, OR (United States); Myers, Greg [Consortium For Ocean Leadership Inc., Washington, DC (United States); Divins, David [Consortium For Ocean Leadership Inc., Washington, DC (United States); Morell, Margo [Consortium For Ocean Leadership Inc., Washington, DC (United States)

    2013-12-31

    This topical report represents a pathway toward better understanding of the impact of marine methane hydrates on safety and seafloor stability and future collection of data that can be used by scientists, engineers, managers and planners to study climate change and to assess the feasibility of marine methane hydrate as a potential future energy resource. Our understanding of the occurrence, distribution and characteristics of marine methane hydrates is incomplete; therefore, research must continue to expand if methane hydrates are to be used as a future energy source. Exploring basins with methane hydrates has been occurring for over 30 years, but these efforts have been episodic in nature. To further our understanding, these efforts must be more regular and employ new techniques to capture more data. This plan identifies incomplete areas of methane hydrate research and offers solutions by systematically reviewing known methane hydrate “Science Challenges” and linking them with “Technical Challenges” and potential field program locations.

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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...

  7. Genetics Home Reference: episodic ataxia

    Science.gov (United States)

    ... Facebook Twitter Home Health Conditions Episodic ataxia Episodic ataxia Printable PDF Open All Close All Enable Javascript to view the expand/collapse boxes. Description Episodic ataxia is a group of related conditions that affect ...

  8. Is methane released from the forest canopy?

    DEFF Research Database (Denmark)

    Mikkelsen, Teis Nørgaard; Bruhn, Dan; Ambus, Per

    2011-01-01

    Laboratory experiments show that rates of CH4 emission from plant material depend exponentially on temperature and linearly on UV irradiance. The UV irradiance shall be spectrally weighted and shorter wavelengths results in higher CH4 emissions. Global upscaling models for estimating aerobic CH4......, based on lab results, have be conducted with varying results, but until now field measurements based on profile and eddy covariance measurements have failed to show CH4 emissions from forest canopies. To detect CH4 production or consumption in the canopy of a beech stand we connected a CH4 analyzer...... indications of periodic CH4 emissions in the canopy, but more data need to be analyzed before the magnitude of the canopy source of CH4 can be established....

  9. Methane emissions from ruminants

    African Journals Online (AJOL)

    user

    2011-02-21

    Feb 21, 2011 ... Livestock account for 35-40% of global anthropogenic emissions of methane, via enteric fermentation and manure, ... on the climate; the global warming potential of methane is. 21-times that of CO2 over 100 years ... cell wall structure from true rumen bacteria (Woese et al.1990). METHANE MITIGATION ...

  10. Methane-Derived Hydrogen in Lipids Produced by Aerobic Methanotrophs

    Science.gov (United States)

    Sessions, A. L.; Jahnke, L. L.; Schimmelmann, A.; Hayes, J. M.

    2001-12-01

    Combined hydrogen- and carbon-isotopic analyses of methane often provide important clues about its origin. Unfortunately, methane is not preserved in the geologic record so these analyses can only examine trapped or actively produced methane. The lipids of microorganisms that consume methane potentially record its isotopic composition, and are accessible throughout most of the geologic record. Those lipids therefore represent a potential means for examining the characteristics of methane released into the oceans over geologic history. We have examined the hydrogen-isotopic relationships between methane and lipids in the aerobic methanotroph Methylococcus capsulatus using cultures in which the D/H ratio of supplied water and methane were controlled independently. Resulting δ D values were measured for a range of fatty acids, sterols, and hopanols using isotope-ratio-monitoring gas chromatography/mass spectrometry. We estimate that 31 +/- 2% of hydrogen in every lipid we examined is derived from methane, regardless of whether cultures were harvested in exponential or stationary phase. The biochemical pathways responsible for the transfer of hydrogen from methane to lipids are not fully understood. Isotope fractionation associated with the utilization of methane (i.e., α lipid/methane) averages 0.986 for fatty acids and 0.789 for isoprenoid lipids. For water, fractionation (α lipid/water) averages 0.938 for fatty acids and 0.831 for isoprenoid lipids. Given typical δ D values for seawater (0%) and thermogenic `dry' methane (-150‰ ), fatty acids from M. capsulatus should have δ D values near -95‰ , and isoprenoids should have δ D values near -215‰ . Using δ Dmethane = -300‰ , a value near the lower limit of those for biogenic methanes, we predict δ D values for methanotroph fatty acids and isoprenoid lipids of -140 and -260‰ , respectively. It appears possible that D/H measurements of lipids from methanotrophic bacteria will provide useful hydrogen

  11. Martian Methane From a Cometary Source: A Hypothesis

    Science.gov (United States)

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

    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.

  12. Methane hydrate stability and anthropogenic climate change

    National Research Council Canada - National Science Library

    Archer, D

    2007-01-01

    .... The hydrate reservoir is so large that if 10% of the methane were released to the atmosphere within a few years, it would have an impact on the Earth's radiation budget equivalent to a factor of 10 increase in atmospheric CO2...

  13. Acoustic Determination of Methane Hydrate Disssociation Pressures

    Science.gov (United States)

    2011-07-01

    The compounds are also known to form as a skin on rising methane bubbles, as reported by Rehder et al. [1], Heeschen et al. [2], and Sauter et al. [3...discrepancy. First, during the experi- ment the video monitor used to measure brine column height became clouded with an oily film which was released from...which would result in 12% to 28% error in bulk modulus measurement. The oily substance released from the hydrate samples is an indicator of a second

  14. Perinatal psychiatric episodes

    DEFF Research Database (Denmark)

    Munk-Olsen, Trine; Maegbaek, M L; Johannsen, B M

    2016-01-01

    and childbirth, which suggests differences in the underlying etiology. We further speculate varying treatment incidence and prevalence in pregnancy vs postpartum may indicate that the current Diagnostic and Statistical Manual of Mental Disorders-5 peripartum specifier not adequately describes at-risk periods......Perinatal psychiatric episodes comprise various disorders and symptom severity, which are diagnosed and treated in multiple treatment settings. To date, no studies have quantified the incidence and prevalence of perinatal psychiatric episodes treated in primary and secondary care, which we aimed...... psychiatric facilities, 2.5 births were followed by an episode treated at outpatient psychiatric facility and 12 births by GP-provided pharmacological treatment. We interpret our results the following way: treated severe and moderate psychiatric disorders have different risk patterns in relation to pregnancy...

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

    Science.gov (United States)

    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.

  16. Episodic foresight and schizophrenia.

    Science.gov (United States)

    Lyons, Amanda D; Henry, Julie D; Rendell, Peter G; Robinson, Gail; Suddendorf, Thomas

    2016-06-01

    People with schizophrenia have difficulty engaging in specific future-directed thoughts and behaviours, such as generating phenomenological characteristics of future events (a component of episodic foresight), and executing directed preparatory behaviours (a component of prospective memory). However, it remains unclear whether they also exhibit difficulties using episodic foresight to appropriately guide future-directed behaviours. People with schizophrenia and non-clinical controls were administered a behavioural measure that met strict criteria for assessing episodic foresight. In keeping with our focus on the functional application of foresight, this measure required participants to identify a problem, self-generate a resolution, and execute the appropriate future-directed intention. Relative to controls, people with schizophrenia were less likely to spontaneously acquire items that would later allow a problem to be solved, and were also less likely to subsequently use these items to solve the problems. There was no interaction between group and task, indicating that these two components of foresight were disrupted to an equivalent degree. In the clinical (but not the control) group, item acquisition and item use were correlated with general cognitive capacity. No significant associations with clinical variables emerged. The capacity to apply episodic foresight in a functionally adaptive way is disrupted in schizophrenia and may at least partially reflect broader cognitive dysfunction. Future work is now needed to clarify the implications of these difficulties in everyday life, as well as how these difficulties might be remediated. People with schizophrenia have known difficulties with episodic foresight, and it now appears that those difficulties extend to the performance of foresightful preparatory behaviours. Because preparatory behaviours are central to routine and adaptive planning, difficulties with episodic foresight may contribute to or be a result of

  17. Low Background Levels of Mars Methane at Gale Crater Indicate Seasonal Cycle: Updated Results from TLS-SAM on Curiosity

    Science.gov (United States)

    Webster, C. R.; Mahaffy, P. R.; Atreya, S. K.

    2016-12-01

    In situ measurements of atmospheric methane have been made over a 3-year period at Gale Crater on Mars using the Tunable Laser Spectrometer (TLS) instrument in the Sample Analysis at Mars (SAM) suite on the Curiosity rover. We have reported two important observations: (i) a background level of 0.5 ppbv that is about five times lower than some model predictions based on generation from UV degradation of micro-meteorites or interplanetary dust delivered to the martian surface; (ii) a "spike" of elevated levels of 7 ppbv that were seen1 on four sequential observations over a 2-month period before dropping to background levels. This spike was attributed to an episodic release from a small local source, probably to the north of Gale crater. While the elevated levels of the spike did not return (repeat) one Mars year later, we have seen what appears to be a seasonal variation to the background levels that are all Curiosity, and discuss the mechanisms that are believed to be contributing to the low background methane signals and their variation. 1 "Mars Methane Detection and Variability at Gale Crater", C. R. Webster et al., Science, 347, 415-417 (2015) and references therein. The research described here was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA).

  18. Uncertainty assessment of the breath methane concentration method to determine methane production of dairy cows.

    Science.gov (United States)

    Wu, Liansun; Koerkamp, Peter W G Groot; Ogink, Nico

    2017-11-15

    The breath methane concentration method uses the methane concentrations in the cow's breath during feed bin visits as a proxy for the methane production rate. The objective of this study was to assess the uncertainty of a breath methane concentration method in a feeder and its capability to measure and rank cows' methane production. A range of controlled methane fluxes from a so-called artificial reference cow were dosed in a feed bin, and its exhaled air was sampled by a tube inside the feeder and analyzed. The artificial reference cow simulates the lungs, respiratory tract, and rumen of a cow and releases a variable methane flux to generate a concentration pattern in the exhaled breath that closely resembles a real cow's pattern. The strength of the relation between the controlled methane release rates of the artificial reference cow and the measured methane concentrations was analyzed by linear regression, using the coefficient of determination (R2) and the residual standard error as performance indicators. The effect of error sources (source-sampling distance, air turbulence, and cow's head movement) on this relation was experimentally investigated, both under laboratory and barn conditions. From the laboratory to the dairy barn at the 30-cm sampling distance, the R2-value decreased from 0.97 to 0.37 and the residual standard error increased from 75 to 86 ppm as a result of barn air turbulence, the latter increasing to a theoretical 94 ppm if modeled variability due to cow's head movement was accounted for as well. In practice, the effect of these random errors can be compensated by sampling strategies including repeated measurements on each cow over time, thus increasing the distinctive power between cows. However, systematic errors that may disturb the relation between concentration and production rate, such as cow variation in air exhalation rate and air flow patterns around sampling locations that differ between barns, cannot be compensated by repeated

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

    Science.gov (United States)

    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. Methane hydrate stability and anthropogenic climate change

    OpenAIRE

    Archer, D.

    2007-01-01

    Methane frozen into hydrate makes up a large reservoir of potentially volatile carbon below the sea floor and associated with permafrost soils. This reservoir intuitively seems precarious, because hydrate ice floats in water, and melts at Earth surface conditions. The hydrate reservoir is so large that if 10% of the methane were released to the atmosphere within a few years, it would have an impact on the Earth's radiation budget equivalent to a factor of 10 increase in atmospheric CO<...

  1. Sediment trapping by dams creates methane emission hot spots.

    Science.gov (United States)

    Maeck, Andreas; Delsontro, Tonya; McGinnis, Daniel F; Fischer, Helmut; Flury, Sabine; Schmidt, Mark; Fietzek, Peer; Lorke, Andreas

    2013-08-06

    Inland waters transport and transform substantial amounts of carbon and account for ∼18% of global methane emissions. Large reservoirs with higher areal methane release rates than natural waters contribute significantly to freshwater emissions. However, there are millions of small dams worldwide that receive and trap high loads of organic carbon and can therefore potentially emit significant amounts of methane to the atmosphere. We evaluated the effect of damming on methane emissions in a central European impounded river. Direct comparison of riverine and reservoir reaches, where sedimentation in the latter is increased due to trapping by dams, revealed that the reservoir reaches are the major source of methane emissions (∼0.23 mmol CH4 m(-2) d(-1) vs ∼19.7 mmol CH4 m(-2) d(-1), respectively) and that areal emission rates far exceed previous estimates for temperate reservoirs or rivers. We show that sediment accumulation correlates with methane production and subsequent ebullitive release rates and may therefore be an excellent proxy for estimating methane emissions from small reservoirs. Our results suggest that sedimentation-driven methane emissions from dammed river hot spot sites can potentially increase global freshwater emissions by up to 7%.

  2. The vertical transport of methane from different potential emission types on Mars

    Science.gov (United States)

    Holmes, J. A.; Patel, M. R.; Lewis, S. R.

    2017-08-01

    The contrasting evolutionary behavior of the vertical profile of methane from three potential release scenarios is analyzed using a global circulation model with assimilated temperature profiles. Understanding the evolving methane distribution is essential for interpretation of future retrievals of the methane vertical profile taken by instruments on the ExoMars Trace Gas Orbiter spacecraft. We show that at methane release rates constrained by previous observations and modeling studies, discriminating whether the methane source is a sustained or instantaneous surface emission requires at least 10 sols of tracking the emission. A methane source must also be observed within 5 to 10 sols of the initial emission to distinguish whether the emission occurs directly at the surface or within the atmosphere via destabilization of metastable clathrates. Assimilation of thermal data is shown to be critical for the most accurate backtracking of an observed methane plume to its origin.

  3. Methane Seepage on Mars: Where to Look and Why.

    Science.gov (United States)

    Oehler, Dorothy Z; Etiope, Giuseppe

    2017-08-03

    Methane on Mars is a topic of special interest because of its potential association with microbial life. The variable detections of methane by the Curiosity rover, orbiters, and terrestrial telescopes, coupled with methane's short lifetime in the martian atmosphere, may imply an active gas source in the planet's subsurface, with migration and surface emission processes similar to those known on Earth as "gas seepage." Here, we review the variety of subsurface processes that could result in methane seepage on Mars. Such methane could originate from abiotic chemical reactions, thermogenic alteration of abiotic or biotic organic matter, and ancient or extant microbial metabolism. These processes can occur over a wide range of temperatures, in both sedimentary and igneous rocks, and together they enhance the possibility that significant amounts of methane could have formed on early Mars. Methane seepage to the surface would occur preferentially along faults and fractures, through focused macro-seeps and/or diffuse microseepage exhalations. Our work highlights the types of features on Mars that could be associated with methane release, including mud-volcano-like mounds in Acidalia or Utopia; proposed ancient springs in Gusev Crater, Arabia Terra, and Valles Marineris; and rims of large impact craters. These could have been locations of past macro-seeps and may still emit methane today. Microseepage could occur through faults along the dichotomy or fractures such as those at Nili Fossae, Cerberus Fossae, the Argyre impact, and those produced in serpentinized rocks. Martian microseepage would be extremely difficult to detect remotely yet could constitute a significant gas source. We emphasize that the most definitive detection of methane seepage from different release candidates would be best provided by measurements performed in the ground or at the ground-atmosphere interface by landers or rovers and that the technology for such detection is currently available. Key

  4. Methane to liquid

    Energy Technology Data Exchange (ETDEWEB)

    Watkins, B.E.; Shock, R.N.; Taylor, R.T.

    1992-06-01

    We are investigating the structure/activity relationships of the bacterial enzyme methane monooxygenase, which catalyzes the the specific oxidation of methane to methanol. We then utilize this information to design and synthesize inorganic coordination complexes that mimic the function of the native enzyme but more robust and have higher catalytic site density. We envision these catalysts to be useful in process catalytic reactors in the conversion of methane in natural gas to liquid methanol.

  5. Methane emission by Camelids

    OpenAIRE

    Marie T Dittmann; 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 pop...

  6. Non-microbial methane formation in oxic soils

    Directory of Open Access Journals (Sweden)

    A. Jugold

    2012-12-01

    Full Text Available Methane plays an important role as a radiatively and chemically active gas in our atmosphere. Until recently, sources of atmospheric methane in the biosphere have been attributed to strictly anaerobic microbial processes during degradation of organic matter. However, a large fraction of methane produced in the anoxic soil layers does not reach the atmosphere due to methanotrophic consumption in the overlaying oxic soil. Although methane fluxes from aerobic soils have been observed, an alternative source other than methanogenesis has not been identified thus far.

    Here we provide evidence for non-microbial methane formation in soils under oxic conditions. We found that soils release methane upon heating and other environmental factors like ultraviolet irradiation, and drying-rewetting cycles. We suggest that chemical formation of methane during degradation of soil organic matter may represent the missing soil source that is needed to fully understand the methane cycle in aerobic soils. Although the emission fluxes are relatively low when compared to those from wetlands, they may be important in warm and wet regions subjected to ultraviolet radiation. We suggest that this methane source is highly sensitive to global change.

  7. Episodes, events, and models

    Directory of Open Access Journals (Sweden)

    Sangeet eKhemlani

    2015-10-01

    Full Text Available We describe a novel computational theory of how individuals segment perceptual information into representations of events. The theory is inspired by recent findings in the cognitive science and cognitive neuroscience of event segmentation. In line with recent theories, it holds that online event segmentation is automatic, and that event segmentation yields mental simulations of events. But it posits two novel principles as well: first, discrete episodic markers track perceptual and conceptual changes, and can be retrieved to construct event models. Second, the process of retrieving and reconstructing those episodic markers is constrained and prioritized. We describe a computational implementation of the theory, as well as a robotic extension of the theory that demonstrates the processes of online event segmentation and event model construction. The theory is the first unified computational account of event segmentation and temporal inference. We conclude by demonstrating now neuroimaging data can constrain and inspire the construction of process-level theories of human reasoning.

  8. Annual Patterns of Atmospheric Pollutions and Episodes over Cairo Egypt

    Directory of Open Access Journals (Sweden)

    Y. Aboel Fetouh

    2013-01-01

    Full Text Available The Nile Delta major cities, particularly Cairo, experienced stagnant air pollution episodes, known as Black Cloud, every year over the past decade during autumn. Low-elevated thermal inversion layers play a crucial role in intensifying pollution impacts. Carbon monoxide, ozone, atmospheric temperature, water vapor, and methane measurements from the tropospheric emission spectrometer (TES on board the Aura have been used to assess the dominant component below the inversion layer. In this study, time series analysis, autocorrelations, and cross correlations are performed to gain a better understanding of the connections between those parameters and their local effect. Satellite-based data were obtained for the years 2005–2010. The parameters mentioned were investigated throughout the whole year in order to study the possible episodes that take place in addition to their change from year to year. Ozone and carbon monoxide were the two major indicators to the most basic episodes that occur over Cairo and the Delta region.

  9. Perspectives on Episodic-like and Episodic Memory

    Directory of Open Access Journals (Sweden)

    Bettina M Pause

    2013-04-01

    Full Text Available Episodic memory refers to the conscious recollection of a personal experience that contains information on what has happened and also where and when it happened. Recollection from episodic memory also implies a kind of first-person subjectivity that has been termed autonoetic consciousness. Episodic memory is extremely sensitive to cerebral aging and neurodegenerative diseases. In Alzheimer’s disease deficits in episodic memory function are among the first cognitive symptoms observed. Furthermore, impaired episodic memory function is also observed in a variety of other neuropsychiatric diseases including dissociative disorders, schizophrenia and Parkinson disease. Unfortunately, it is quite difficult to induce and measure episodic memories in the laboratory and it is even more difficult to measure it in clinical populations. Presently, the tests used to assess episodic memory function do not comply with even down-sized definitions of episodic-like memory as a memory for what happened, where and when. They also require sophisticated verbal competences and are difficult to apply to patient populations. In this review, we will summarize the progress made in defining behavioral criteria of episodic-like memory in animals (and humans as well as the perspectives in developing novel tests of human episodic memory which can also account for phenomenological aspects of episodic memory such as autonoetic awareness. We will also define basic behavioral, procedural and phenomenological criteria which might be helpful for the development of a valid and reliable clinical test of human episodic memory.

  10. Perspectives on episodic-like and episodic memory.

    Science.gov (United States)

    Pause, Bettina M; Zlomuzica, Armin; Kinugawa, Kiyoka; Mariani, Jean; Pietrowsky, Reinhard; Dere, Ekrem

    2013-01-01

    Episodic memory refers to the conscious recollection of a personal experience that contains information on what has happened and also where and when it happened. Recollection from episodic memory also implies a kind of first-person subjectivity that has been termed autonoetic consciousness. Episodic memory is extremely sensitive to cerebral aging and neurodegenerative diseases. In Alzheimer's disease deficits in episodic memory function are among the first cognitive symptoms observed. Furthermore, impaired episodic memory function is also observed in a variety of other neuropsychiatric diseases including dissociative disorders, schizophrenia, and Parkinson disease. Unfortunately, it is quite difficult to induce and measure episodic memories in the laboratory and it is even more difficult to measure it in clinical populations. Presently, the tests used to assess episodic memory function do not comply with even down-sized definitions of episodic-like memory as a memory for what happened, where, and when. They also require sophisticated verbal competences and are difficult to apply to patient populations. In this review, we will summarize the progress made in defining behavioral criteria of episodic-like memory in animals (and humans) as well as the perspectives in developing novel tests of human episodic memory which can also account for phenomenological aspects of episodic memory such as autonoetic awareness. We will also define basic behavioral, procedural, and phenomenological criteria which might be helpful for the development of a valid and reliable clinical test of human episodic memory.

  11. The Role of Episodic and Semantic Memory in Episodic Foresight

    Science.gov (United States)

    Martin-Ordas, Gema; Atance, Cristina M.; Louw, Alyssa

    2012-01-01

    In this paper we describe a special form of future thinking, termed "episodic foresight" and its relation with episodic and semantic memory. We outline the methodologies that have largely been developed in the last five years to assess this capacity in young children and non-human animals. Drawing on Tulving's definition of episodic and semantic…

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

    Science.gov (United States)

    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

  13. Geologic emissions of methane to the atmosphere.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  15. An Aerial ``Sniffer Dog'' for Methane

    Science.gov (United States)

    Nathan, Brian; Schaefer, Dave; Zondlo, Mark; Khan, Amir; Lary, David

    2012-10-01

    The Earth's surface and its atmosphere maintain a ``Radiation Balance.'' Any factor which influences this balance is labeled as a mechanism of ``Radiative Forcing'' (RF). Greenhouse Gas (GHG) concentrations are among the most important forcing mechanisms. Methane, the second-most-abundant noncondensing greenhouse gas, is over 25 times more effective per molecule at radiating heat than the most abundant, Carbon Dioxide. Methane is also the principal component of Natural Gas, and gas leaks can cause explosions. Additionally, massive quantities of methane reside (in the form of natural gas) in underground shale basins. Recent technological advancements--specifically the combination of horizontal drilling and hydraulic fracturing--have allowed drillers access to portions of these ``plays'' which were previously unreachable, leading to an exponential growth in the shale gas industry. Presently, very little is known about the amount of methane which escapes into the global atmosphere from the extraction process. By using remote-controlled robotic helicopters equipped with specially developed trace gas laser sensors, we can get a 3-D profile of where and how methane is being released into the global atmosphere.

  16. The interaction of climate change and methane hydrates

    Science.gov (United States)

    Ruppel, Carolyn D.; Kessler, John D.

    2017-01-01

    Gas hydrate, a frozen, naturally-occurring, and highly-concentrated form of methane, sequesters significant carbon in the global system and is stable only over a range of low-temperature and moderate-pressure conditions. Gas hydrate is widespread in the sediments of marine continental margins and permafrost areas, locations where ocean and atmospheric warming may perturb the hydrate stability field and lead to release of the sequestered methane into the overlying sediments and soils. Methane and methane-derived carbon that escape from sediments and soils and reach the atmosphere could exacerbate greenhouse warming. The synergy between warming climate and gas hydrate dissociation feeds a popular perception that global warming could drive catastrophic methane releases from the contemporary gas hydrate reservoir. Appropriate evaluation of the two sides of the climate-methane hydrate synergy requires assessing direct and indirect observational data related to gas hydrate dissociation phenomena and numerical models that track the interaction of gas hydrates/methane with the ocean and/or atmosphere. Methane hydrate is likely undergoing dissociation now on global upper continental slopes and on continental shelves that ring the Arctic Ocean. Many factors—the depth of the gas hydrates in sediments, strong sediment and water column sinks, and the inability of bubbles emitted at the seafloor to deliver methane to the sea-air interface in most cases—mitigate the impact of gas hydrate dissociation on atmospheric greenhouse gas concentrations though. There is no conclusive proof that hydrate-derived methane is reaching the atmosphere now, but more observational data and improved numerical models will better characterize the climate-hydrate synergy in the future.

  17. The interaction of climate change and methane hydrates

    Science.gov (United States)

    Ruppel, Carolyn D.; Kessler, John D.

    2017-03-01

    Gas hydrate, a frozen, naturally-occurring, and highly-concentrated form of methane, sequesters significant carbon in the global system and is stable only over a range of low-temperature and moderate-pressure conditions. Gas hydrate is widespread in the sediments of marine continental margins and permafrost areas, locations where ocean and atmospheric warming may perturb the hydrate stability field and lead to release of the sequestered methane into the overlying sediments and soils. Methane and methane-derived carbon that escape from sediments and soils and reach the atmosphere could exacerbate greenhouse warming. The synergy between warming climate and gas hydrate dissociation feeds a popular perception that global warming could drive catastrophic methane releases from the contemporary gas hydrate reservoir. Appropriate evaluation of the two sides of the climate-methane hydrate synergy requires assessing direct and indirect observational data related to gas hydrate dissociation phenomena and numerical models that track the interaction of gas hydrates/methane with the ocean and/or atmosphere. Methane hydrate is likely undergoing dissociation now on global upper continental slopes and on continental shelves that ring the Arctic Ocean. Many factors—the depth of the gas hydrates in sediments, strong sediment and water column sinks, and the inability of bubbles emitted at the seafloor to deliver methane to the sea-air interface in most cases—mitigate the impact of gas hydrate dissociation on atmospheric greenhouse gas concentrations though. There is no conclusive proof that hydrate-derived methane is reaching the atmosphere now, but more observational data and improved numerical models will better characterize the climate-hydrate synergy in the future.

  18. Nonequilibrium adiabatic molecular dynamics simulations of methane clathrate hydrate decomposition.

    Science.gov (United States)

    Alavi, Saman; Ripmeester, J A

    2010-04-14

    Nonequilibrium, constant energy, constant volume (NVE) molecular dynamics simulations are used to study the decomposition of methane clathrate hydrate in contact with water. Under adiabatic conditions, the rate of methane clathrate decomposition is affected by heat and mass transfer arising from the breakup of the clathrate hydrate framework and release of the methane gas at the solid-liquid interface and diffusion of methane through water. We observe that temperature gradients are established between the clathrate and solution phases as a result of the endothermic clathrate decomposition process and this factor must be considered when modeling the decomposition process. Additionally we observe that clathrate decomposition does not occur gradually with breakup of individual cages, but rather in a concerted fashion with rows of structure I cages parallel to the interface decomposing simultaneously. Due to the concerted breakup of layers of the hydrate, large amounts of methane gas are released near the surface which can form bubbles that will greatly affect the rate of mass transfer near the surface of the clathrate phase. The effects of these phenomena on the rate of methane hydrate decomposition are determined and implications on hydrate dissociation in natural methane hydrate reservoirs are discussed.

  19. Atmospheric Ozone and Methane in a Changing Climate

    Directory of Open Access Journals (Sweden)

    Ivar S. A. Isaksen

    2014-07-01

    . During thawing of permafrost, parts of the organic material that is deposited could be converted to methane. Furthermore, methane stored in deposits under shallow waters in the Arctic have the potential to be released in a future warmer climate with enhanced climate impact on methane, ozone and stratospheric water vapor. Studies performed by several groups show that the transport sectors have the potential for significant impacts on climate-chemistry interactions. There are large uncertainties connected to ozone and methane changes from the transport sector, and to methane release and climate impact during permafrost thawing.

  20. Methane from the East Siberian Arctic shelf

    DEFF Research Database (Denmark)

    Petrenko...[], Vasilii V.; Etheridge, David M.

    2010-01-01

    In their Report “Extensive methane venting to the atmosphere from sediments of the East Siberian Arctic Shelf” (5 March, p. 1246), N. Shakhova et al. write that methane (CH4) release resulting from thawing Arctic permafrost “is a likely positive feedback to climate warming.” They add...... that the release of Arctic CH4 was implied in previous climate shifts as well as in the recently renewed rise in atmospheric CH4. These claims are not supported by all the literature they cite. Their reference 5 (1) presents measurements of emissions only of carbon dioxide, not CH4. Their reference 8 (2), a study...... the Report and in (6)] add to our understanding of the atmospheric CH4 budget, but they do not show that Arctic warming has produced a positive feedback in radiative forcing by causing these emissions to increase recently. A newly discovered CH4 source is not necessarily a changing source, much less a source...

  1. Martian Atmospheric Methane Plumes from Meteor Shower Infall: A Hypothesis

    Science.gov (United States)

    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.

  2. Methane emission by camelids.

    Science.gov (United States)

    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.

  3. Methane emission by camelids.

    Directory of Open Access Journals (Sweden)

    Marie T Dittmann

    Full Text Available 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.

  4. Methane Emission by Camelids

    Science.gov (United States)

    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. PMID:24718604

  5. A water column study of methane around gas flares located at the West Spitsbergen continental margin

    DEFF Research Database (Denmark)

    Gentz, Torben; Damm, Ellen; von Deimling, Jens Schneider

    2014-01-01

    the fate of the released gas due to dissolution of methane from gas bubbles and subsequent mixing, transport and microbial oxidation. The oceanographic data indicated a salinity-controlled pycnocline situated ∼20 m above the seafloor. A high resolution sampling program at the pycnocline at the active gas...... ebullition flare area revealed that the methane concentration gradient is strongly controlled by the pycnocline. While high methane concentrations of up to 524 nmol L1 were measured below the pycnocline, low methane concentrations of less than 20 nmol L1 were observed in the water column above. Variations...... in the δ13CCH4 values point to a 13C depleted methane source (∼ –60‰ VPDB) being mainly mixed with a background values of the ambient water (∼–37.5‰ VPDB). A gas bubble dissolution model indicates that ∼80% of the methane released from gas bubbles into the ambient water takes place below the pycnocline...

  6. First-episode psychosis

    DEFF Research Database (Denmark)

    Simonsen, Erik

    2011-01-01

    that two-thirds of the patients had a comorbid personality disorder at two-year follow-up, and schizoid, paranoid and avoidant personality disorder were the most frequent. Schizotypal traits were less prevalent, which in relation to the late follow-up is attributed to uncertainty in differentiating....... Patients with first-episode psychosis had significantly high NEO-PI-R scores for neuroticism and agreeableness, and lower scores for conscientiousness and extroversion. The median time for remission in the total sample was three months. Female gender and better premorbid functioning were predictive of less...... negative symptoms and shorter duration of untreated psychosis (DUP) was predictive for shorter time to remission, stable remission, less severe positive psychotic symptoms, and better social functioning. Female gender, better premorbid social functioning and more education also contributed to a better...

  7. Stabilization of methane hydrate by pressurization with He or N2 gas.

    Science.gov (United States)

    Lu, Hailong; Tsuji, Yoshihiro; Ripmeester, John A

    2007-12-27

    The behavior of methane hydrate was investigated after it was pressurized with helium or nitrogen gas in a test system by monitoring the gas compositions. The results obtained indicate that even when the partial pressure of methane gas in such a system is lower than the equilibrium pressure at a certain temperature, the dissociation rate of methane hydrate is greatly depressed by pressurization with helium or nitrogen gas. This phenomenon is only observed when the total pressure of methane and helium (or nitrogen) gas in the system is greater than the equilibrium pressure required to stabilize methane hydrate with just methane gas. The following model has been proposed to explain the observed phenomenon: (1) Gas bubbles develop at the hydrate surface during hydrate dissociation, and there is a pressure balance between the methane gas inside the gas bubbles and the external pressurizing gas (methane and helium or nitrogen), as transmitted through the water film; as a result the methane gas in the gas bubbles stabilizes the hydrate surface covered with bubbles when the total gas pressure is greater than the equilibrium pressure of the methane hydrate at that temperature; this situation persists until the gas in the bubbles becomes sufficiently dilute in methane or until the surface becomes bubble-free. (2) In case of direct contact of methane hydrate with water, the water surrounding the hydrate is supersaturated with methane released upon hydrate dissociation; consequently, methane hydrate is stabilized when the hydrostatic pressure is above the equilibrium pressure of methane hydrate at a certain temperature, again until the dissolved gas at the surface becomes sufficiently dilute in methane. In essence, the phenomenon is due to the presence of a nonequilibrium state where there is a chemical potential gradient from the solid hydrate particles to the bulk solution that exists as long as solid hydrate remains.

  8. Methane monitoring from space

    Science.gov (United States)

    Stephan, C.; Alpers, M.; Millet, B.; Ehret, G.; Flamant, P.

    2017-11-01

    Methane is one of the strongest anthropogenic greenhouse gases. It contributes by its radiative forcing significantly to the global warming. For a better understanding of climate changes, it is necessary to apply precise space-based measurement techniques in order to obtain a global view on the complex processes that control the methane concentration in the atmosphere. The MERLIN mission is a joint French-German cooperation, on a micro satellite mission for space-based measurement of spatial and temporal gradients of atmospheric methane columns on a global scale. MERLIN will be the first Integrated Path Differential Absorption LIDAR for greenhouse gas monitoring from space. In contrast to passive methane missions, the LIDAR instrument allows measurements at alllatitudes, all-seasons and during night.

  9. Enzymatic Oxidation of Methane

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Stable carbon isotopic signature of methane from high-emitting wetland sites in discontinuous permafrost landscape

    Science.gov (United States)

    Marushchak, Maija; Liimatainen, Maarit; Lind, Saara; Biasi, Christina; Martikainen, Pertti

    2017-04-01

    The rising methane concentration in the atmosphere during the past years has been associated with a concurrent change in the carbon isotopic signature: The atmospheric methane is getting more and more depleted in the heavy carbon isotope. The decreasing 13C/12C ratio indicates an increasing contribution of methane from biogenic sources, most importantly wetlands and inland waters, whose global emissions are still poorly constrained. From the climate change perspective, arctic and subarctic wetlands are particularly interesting due to the strong warming and permafrost thaw predicted for these regions that will cause changes in the methane dynamics. Coupling methane flux inventories with determination of the stable isotopic signature can provide useful information about the pathways of methane production, consumption and transport in these ecosystems. Here, we present data on the emissions and carbon isotopic composition of methane from subarctic tundra wetlands at the Seida study site, Northeast European Russia. In this landscape, underlain by discontinuous permafrost, waterlogged fens represent sites of high carbon turnover and high methane release. Despite they cover less than 15% of the region, their methane emissions comprise 98% of the regional mean (± SD) release of 6.7 (± 1.8) g CH4 m-2 y-1 (Marushchak et al. 2016). The methane emission from the studied fens was clearly depleted in 13C compared to the pore water methane. The bulk mean δ13CH4 (± SD) over the growing season was -68.2 (± 2.0) ‰ which is similar to the relatively few values previously reported from tundra wetlands. We explain the depleted methane emissions by the high importance of passive transport via aerenchymous plants, a process that discriminates against the heavier isotopes. This idea is supported by the strong positive correlation observed between the methane emission and the vascular leaf area index (LAI), and the inverse relationship between the δ13CH4 of emitted methane and LAI

  11. Moral judgment in episodic amnesia.

    Science.gov (United States)

    Craver, Carl F; Keven, Nazim; Kwan, Donna; Kurczek, Jake; Duff, Melissa C; Rosenbaum, R Shayna

    2016-08-01

    To investigate the role of episodic thought about the past and future in moral judgment, we administered a well-established moral judgment battery to individuals with hippocampal damage and deficits in episodic thought (insert Greene et al. 2001). Healthy controls select deontological answers in high-conflict moral scenarios more frequently when they vividly imagine themselves in the scenarios than when they imagine scenarios abstractly, at some personal remove. If this bias is mediated by episodic thought, individuals with deficits in episodic thought should not exhibit this effect. We report that individuals with deficits in episodic memory and future thought make moral judgments and exhibit the biasing effect of vivid, personal imaginings on moral judgment. These results strongly suggest that the biasing effect of vivid personal imagining on moral judgment is not due to episodic thought about the past and future. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  12. Tropospheric impact of methane emissions from clathrates in the Arctic Region

    OpenAIRE

    Bhattacharyya, S.; Cameron-Smith, P.; Bergmann, D; Reagan, M; Elliott, S.; Moridis, G.

    2012-01-01

    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 methane into the ocean and subsequently the atmosphere. This is of part...

  13. The interaction of climate change and methane hydrates: Climate-Hydrates Interactions

    OpenAIRE

    Ruppel, Carolyn D.; Kessler, John D.

    2017-01-01

    Gas hydrate, a frozen, naturally-occurring, and highly-concentrated form of methane, sequesters significant carbon in the global system and is stable only over a range of low-temperature and moderate-pressure conditions. Gas hydrate is widespread in the sediments of marine continental margins and permafrost areas, locations where ocean and atmospheric warming may perturb the hydrate stability field and lead to release of the sequestered methane into the overlying sediments and soils. Methane ...

  14. The evolution of episodic memory

    Science.gov (United States)

    Allen, Timothy A.; Fortin, Norbert J.

    2013-01-01

    One prominent view holds that episodic memory emerged recently in humans and lacks a “(neo)Darwinian evolution” [Tulving E (2002) Annu Rev Psychol 53:1–25]. Here, we review evidence supporting the alternative perspective that episodic memory has a long evolutionary history. We show that fundamental features of episodic memory capacity are present in mammals and birds and that the major brain regions responsible for episodic memory in humans have anatomical and functional homologs in other species. We propose that episodic memory capacity depends on a fundamental neural circuit that is similar across mammalian and avian species, suggesting that protoepisodic memory systems exist across amniotes and, possibly, all vertebrates. The implication is that episodic memory in diverse species may primarily be due to a shared underlying neural ancestry, rather than the result of evolutionary convergence. We also discuss potential advantages that episodic memory may offer, as well as species-specific divergences that have developed on top of the fundamental episodic memory architecture. We conclude by identifying possible time points for the emergence of episodic memory in evolution, to help guide further research in this area. PMID:23754432

  15. Timescales of methane seepage on the Norwegian margin following collapse of the Scandinavian Ice Sheet.

    Science.gov (United States)

    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.

  16. Low temperature production and exhalation of methane from serpentinized rocks on Earth: A potential analog for methane production on Mars

    Science.gov (United States)

    Etiope, Giuseppe; Ehlmann, Bethany L.; Schoell, Martin

    2013-06-01

    We evaluate, based on terrestrial analogs, the potential flux, origin and isotopic signature of methane (CH4) from serpentinized or serpentinizing rocks on Mars. The Tekirova ophiolites, in Turkey, have been shown to release, either via focused vents or through diffuse microseepage, substantial amounts of CH4 which could be produced via catalyzed abiotic methanation (Sabatier reaction) at low temperatures (methane production and fractures for release of gas to the atmosphere, similar to those on Earth. A simple, first-order estimation gas-advection model suggests that methane fluxes on the order of several mg m-2 d-1, similar to microseepage observed in terrestrial ophiolites, could occur in martian rocks. High temperature, hydrothermal conditions may not be necessary for abiotic CH4 synthesis on Mars: low temperature (methanation is possible in the presence of catalysts like ruthenium, rhodium or, more commonly, chromium minerals, which occur in terrestrial ophiolites as in martian mantle meteorites. The terrestrial analog environment of abiotic microseepage may thus explain production of methane on Mars in the ancient past or at present. The wide range of martian 12C/13C and D/H ratios and the potential secondary alteration of CH4 by abiotic oxidation, as observed on Earth, could result in large isotope variations of methane on Mars. CH4 isotopic composition alone may not allow definitive determination of biotic vs. abiotic gas origin. Using our terrestrial vs. martian analysis as guide to future Mars exploration we propose that direct methane and ethane gas detection and isotopic measurements on the ground over serpentinized/serpentinizing rocks should be considered in developing future strategies for unraveling the source and origin of methane on Mars.

  17. The Episodic Nature of Episodic-Like Memories

    Science.gov (United States)

    Easton, Alexander; Webster, Lisa A. D.; Eacott, Madeline J.

    2012-01-01

    Studying episodic memory in nonhuman animals has proved difficult because definitions in humans require conscious recollection. Here, we assessed humans' experience of episodic-like recognition memory tasks that have been used with animals. It was found that tasks using contextual information to discriminate events could only be accurately…

  18. Homogeneous Functionalization of Methane.

    Science.gov (United States)

    Gunsalus, Niles Jensen; Koppaka, Anjaneyulu; Park, Sae Hume; Bischof, Steven M; Hashiguchi, Brian G; Periana, Roy A

    2017-07-12

    One of the remaining "grand challenges" in chemistry is the development of a next generation, less expensive, cleaner process that can allow the vast reserves of methane from natural gas to augment or replace oil as the source of fuels and chemicals. Homogeneous (gas/liquid) systems that convert methane to functionalized products with emphasis on reports after 1995 are reviewed. Gas/solid, bioinorganic, biological, and reaction systems that do not specifically involve methane functionalization are excluded. The various reports are grouped under the main element involved in the direct reactions with methane. Central to the review is classification of the various reports into 12 categories based on both practical considerations and the mechanisms of the elementary reactions with methane. Practical considerations are based on whether or not the system reported can directly or indirectly utilize O2 as the only net coreactant based only on thermodynamic potentials. Mechanistic classifications are based on whether the elementary reactions with methane proceed by chain or nonchain reactions and with stoichiometric reagents or catalytic species. The nonchain reactions are further classified as CH activation (CHA) or CH oxidation (CHO). The bases for these various classifications are defined. In particular, CHA reactions are defined as elementary reactions with methane that result in a discrete methyl intermediate where the formal oxidation state (FOS) on the carbon remains unchanged at -IV relative to that in methane. In contrast, CHO reactions are defined as elementary reactions with methane where the carbon atom of the product is oxidized and has a FOS less negative than -IV. This review reveals that the bulk of the work in the field is relatively evenly distributed across most of the various areas classified. However, a few areas are only marginally examined, or not examined at all. This review also shows that, while significant scientific progress has been made

  19. Interactions between methane and the nitrogen cycle in light of climate change

    NARCIS (Netherlands)

    Bodelier, P.L.E.; Steenbergh, A.K.

    2014-01-01

    Next to carbon dioxide, methane is the most important greenhouse gas which predominantly is released from natural wetlands and rice paddies. Climate change predictions indicate enhanced methane emission from global ecosystems under elevated CO2 and temperature. However, the extent of this positive

  20. Episodic Alcohol Consumption by Youths

    OpenAIRE

    Pereverzev, Vladimir Alexeevich

    2015-01-01

    AbstractThis paper presents evidence that even rare episodic alcohol consumption by young people is not harmless. Unsafe rare episodic alcohol consumption by youths (students) was reflected in the reduced attention concentration and lower academic buoyancy, compared to those who completely abstain from alcohol. Key Words: Alcohol, youth, students, attention concentration, academic buoyancy 

  1. Episodic Alcohol Consumption by Youths

    OpenAIRE

    Pereverzev, Vladimir Alexeevich

    2014-01-01

    AbstractThis paper presents evidence that even rare episodic alcohol consumption by young people is not harmless. Unsafe rare episodic alcohol consumption by youths (students) was reflected in the reduced attention concentration and lower academic buoyancy, compared to those who completely abstain from alcohol. Key Words: Alcohol, youth, students, attention concentration, academic buoyancy 

  2. Microbial oxidation as a methane sink beneath the West Antarctic Ice Sheet

    Science.gov (United States)

    Michaud, Alexander B.; Dore, John E.; Achberger, Amanda M.; Christner, Brent C.; Mitchell, Andrew C.; Skidmore, Mark L.; Vick-Majors, Trista J.; Priscu, John C.

    2017-08-01

    Aquatic habitats beneath ice masses contain active microbial ecosystems capable of cycling important greenhouse gases, such as methane (CH4). A large methane reservoir is thought to exist beneath the West Antarctic Ice Sheet, but its quantity, source and ultimate fate are poorly understood. For instance, O2 supplied by basal melting should result in conditions favourable for aerobic methane oxidation. Here we use measurements of methane concentrations and stable isotope compositions along with genomic analyses to assess the sources and cycling of methane in Subglacial Lake Whillans (SLW) in West Antarctica. We show that sub-ice-sheet methane is produced through the biological reduction of CO2 using H2. This methane pool is subsequently consumed by aerobic, bacterial methane oxidation at the SLW sediment-water interface. Bacterial oxidation consumes >99% of the methane and represents a significant methane sink, and source of biomass carbon and metabolic energy to the surficial SLW sediments. We conclude that aerobic methanotrophy may mitigate the release of methane to the atmosphere upon subglacial water drainage to ice sheet margins and during periods of deglaciation.

  3. A novel method for estimating methane emissions from underground coal mines: The Yanma coal mine, China

    Science.gov (United States)

    Ji, Zhong-Min; Chen, Zhi-Jian; Pan, Jie-Nan; Niu, Qing-He

    2017-12-01

    As the world's largest coal producer and consumer, China accounts for a relatively high proportion of methane emissions from coal mines. Several estimation methods had been established for the coal mine methane (CMM) emission. However, with large regional differences, various reservoir formation types of coalbed methane (CBM) and due to the complicated geological conditions in China, these methods may be deficient or unsuitable for all the mining areas (e.g. Jiaozuo mining area). By combing the CMM emission characteristics and considering the actual situation of methane emissions from underground coal mine, we found that the methane pre-drainage is a crucial reason creating inaccurate evaluating results for most estimation methods. What makes it so essential is the extensive pre-drainage quantity and its irrelevance with annual coal production. Accordingly, the methane releases were divided into two categories: methane pre-drainage and methane release during mining. On this basis, a pioneering method for estimating CMM emissions was proposed. Taking the Yanma coal mine in the Jiaozuo mining area as a study case, the evaluation method of the pre-drainage methane quantity was established after the correlation analysis between the pre-drainage rate and time. Thereafter, the mining activity influence factor (MAIF) was first introduced to reflect the methane release from the coal and rock seams around where affected by mining activity, and the buried depth was adopted as the predictor of the estimation for future methane emissions. It was verified in the six coal mines of Jiaozuo coalfield (2011) that the new estimation method has the minimum errors of 12.11%, 9.23%, 5.77%, -5.20%, -8.75% and 4.92% respectively comparing with other methods. This paper gives a further insight and proposes a more accurate evaluation method for the CMM emissions, especially for the coal seams with low permeability and strong tectonic deformation in methane outburst coal mines.

  4. Contribution of oceanic gas hydrate dissociation to the formation of Arctic Ocean methane plumes

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. Imagining the personal past: Episodic counterfactuals compared to episodic memories and episodic future projections.

    Science.gov (United States)

    Özbek, Müge; Bohn, Annette; Berntsen, Dorthe

    2017-04-01

    Episodic counterfactuals are imagined events that could have happened, but did not happen, in a person's past. Such imagined past events are important aspects of mental life, affecting emotions, decisions, and behaviors. However, studies examining their phenomenological characteristics and content have been few. Here we introduced a new method to systematically compare self-generated episodic counterfactuals to self-generated episodic memories and future projections with regard to their phenomenological characteristics (e.g., imagery, emotional valence, and rehearsal) and content (e.g., reference to a cultural life script), and how these were affected by temporal distance (1 month, 1 year, 5+ years). The findings showed that the three types of events differed phenomenologically. First, episodic memories were remembered more easily, with more sensory details, and from a dominantly field perspective, as compared to both future projections and episodic counterfactuals. Second, episodic future projections were more positive, more voluntarily rehearsed, and more central to life story and identity than were both episodic memories and episodic counterfactuals. Third, episodic counterfactuals differed from both episodic memories and future projections by neither having the positivity bias of the future events nor the enhanced sensory details of the past events. Across all three event types, sensory details decreased, whereas importance, reference to a cultural life script, and centrality increased with increasing temporal distance. The findings show that imagined events are phenomenologically different from memories of experienced events, consistent with reality-monitoring theory, and that imagined future events are different from both actual and imagined past events, consistent with some theories of motivation.

  6. Direct Activation Of Methane

    KAUST Repository

    Basset, Jean-Marie

    2013-07-15

    Heteropolyacids (HPAs) can activate methane at ambient temperature (e.g., 20.degree. C.) and atmospheric pressure, and transform methane to acetic acid, in the absence of any noble metal such as Pd). The HPAs can be, for example, those with Keggin structure: H.sub.4SiW.sub.12O.sub.40, H.sub.3PW.sub.12O.sub.40, H.sub.4SiMo.sub.12O.sub.40, or H.sub.3PMo.sub.12O.sub.40, can be when supported on silica.

  7. Studies on renin release in vitro

    DEFF Research Database (Denmark)

    Skøtt, O

    1989-01-01

    1) Measurements of renin secretion from single arterioles at time intervals down to 20 seconds showed that the renin secretion is episodic, the amount of renin released during each episode corresponding to the estimated content of one secretory granule. 2) A decrease in osmolality elicits episodi...

  8. Temporal resilience and dynamics of anaerobic methane-oxidizing microbial communities to short-term changes in methane partial pressures

    Science.gov (United States)

    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

  9. Bio-tarp alternative daily cover prototypes for methane oxidation atop open landfill cells.

    Science.gov (United States)

    Adams, Bryn L; Besnard, Fabien; Bogner, Jean; Hilger, Helene

    2011-05-01

    Final landfill covers are highly engineered to prevent methane release into the atmosphere. However, methane production begins soon after waste placement and is an unaddressed source of emissions. The methane oxidation capacity of methanotrophs embedded in a "bio-tarp" was investigated as a means to mitigate methane release from open landfill cells. The bio-tarp would also serve as an alternative daily cover during routine landfill operation. Evaluations of nine synthetic geotextiles identified two that would likely be suitable bio-tarp components. Pilot tarp prototypes were tested in continuous flow systems simulating landfill gas conditions. Multilayered bio-tarp prototypes consisting of alternating layers of the two geotextiles were found to remove 16% of the methane flowing through the bio-tarp. The addition of landfill cover soil, compost, or shale amendments to the bio-tarp increased the methane removal up to 32%. With evidence of methane removal in a laboratory bioreactor, prototypes were evaluated at a local landfill using flux chambers installed atop intermediate cover at a landfill. The multilayered bio-tarp and amended bio-tarp configurations were all found to decrease landfill methane flux; however, the performance efficacy of bio-tarps was not significantly different from controls without methanotrophs. Because highly variable methane fluxes at the field site likely confounded the test results, repeat field testing is recommended under more controlled flux conditions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Methane emissions from oceans, coasts, and freshwater habitats: New perspectives and feedbacks on climate

    Science.gov (United States)

    Hamdan, Leila J.; Wickland, Kimberly P.

    2016-01-01

    Methane is a powerful greenhouse gas, and atmospheric concentrations have risen 2.5 times since the beginning of the Industrial age. While much of this increase is attributed to anthropogenic sources, natural sources, which contribute between 35% and 50% of global methane emissions, are thought to have a role in the atmospheric methane increase, in part due to human influences. Methane emissions from many natural sources are sensitive to climate, and positive feedbacks from climate change and cultural eutrophication may promote increased emissions to the atmosphere. These natural sources include aquatic environments such as wetlands, freshwater lakes, streams and rivers, and estuarine, coastal, and marine systems. Furthermore, there are significant marine sediment stores of methane in the form of clathrates that are vulnerable to mobilization and release to the atmosphere from climate feedbacks, and subsurface thermogenic gas which in exceptional cases may be released following accidents and disasters (North Sea blowout and Deepwater Horizon Spill respectively). Understanding of natural sources, key processes, and controls on emission is continually evolving as new measurement and modeling capabilities develop, and different sources and processes are revealed. This special issue of Limnology and Oceanography gathers together diverse studies on methane production, consumption, and emissions from freshwater, estuarine, and marine systems, and provides a broad view of the current science on methane dynamics of aquatic ecosystems. Here, we provide a general overview of aquatic methane sources, their contribution to the global methane budget, and key uncertainties. We then briefly summarize the contributions to and highlights of this special issue.

  11. Methane budget of a large gas hydrate province offshore Georgia, Black Sea

    Energy Technology Data Exchange (ETDEWEB)

    Haeckel, M.; Reitz, A.; Klaucke, I. [Leibniz Inst. of Marine Sciences, Kiel (Germany)

    2008-07-01

    Methane is the most common hydrocarbon in marine sediments. As such, all seas and oceans have methane seepage that comprises the flow of gases and natural fluids from rocks and sediments through the seabed into the water column. The main effect of methane seepage on the biosphere is the support of cold seep communities by methane and the production of hydrogen sulfide. Hydrogen sulfide is produced in the subsurface sediments by anaerobic oxidation of methane (AOM) by a consortia of microbes and is then utilized by sulfide-oxidizing microbes. This paper reported on a study that investigated methane turnover in the surface sediments in the Batumi methane seep area in the Black Sea, offshore Georgia. The methane flux budget was determined by connecting the calculated methane sinks and sources to the gas bubble motion through the surface sediments. The calculation of methane sinks included benthic flux, AOM and hydrate formation, while the sources included the gas dissolution rate. Geochemical analyses revealed a microbial origin of the methane and a shallow fluid source. Although anaerobic methane oxidation rapidly consumed the SO4{sup 2-} within the top 5-20 cm, a large upward fluid advection was not observed in the porewater profiles. Therefore, it was determined that the Batumi seep area is dominated by methane gas seepage. 1-D transport-reaction modelling constrains the methane flux needed to support the observed SO4{sup 2-} flux as well as the rate of near-surface hydrate formation. The model results were in good agreement with the hydro-acoustic backscatter intensities observed at the bubble release sites using the sonar of a ROV. 52 refs., 1 tab., 4 figs.

  12. Minimal geological methane emissions during the Younger Dryas-Preboreal abrupt warming event

    Science.gov (United States)

    Petrenko, Vasilii V.; Smith, Andrew M.; Schaefer, Hinrich; Riedel, Katja; Brook, Edward; Baggenstos, Daniel; Harth, Christina; Hua, Quan; Buizert, Christo; Schilt, Adrian; Fain, Xavier; Mitchell, Logan; Bauska, Thomas; Orsi, Anais; Weiss, Ray F.; Severinghaus, Jeffrey P.

    2017-08-01

    Methane (CH4) is a powerful greenhouse gas and plays a key part in global atmospheric chemistry. Natural geological emissions (fossil methane vented naturally from marine and terrestrial seeps and mud volcanoes) are thought to contribute around 52 teragrams of methane per year to the global methane source, about 10 per cent of the total, but both bottom-up methods (measuring emissions) and top-down approaches (measuring atmospheric mole fractions and isotopes) for constraining these geological emissions have been associated with large uncertainties. Here we use ice core measurements to quantify the absolute amount of radiocarbon-containing methane (14CH4) in the past atmosphere and show that geological methane emissions were no higher than 15.4 teragrams per year (95 per cent confidence), averaged over the abrupt warming event that occurred between the Younger Dryas and Preboreal intervals, approximately 11,600 years ago. Assuming that past geological methane emissions were no lower than today, our results indicate that current estimates of today’s natural geological methane emissions (about 52 teragrams per year) are too high and, by extension, that current estimates of anthropogenic fossil methane emissions are too low. Our results also improve on and confirm earlier findings that the rapid increase of about 50 per cent in mole fraction of atmospheric methane at the Younger Dryas-Preboreal event was driven by contemporaneous methane from sources such as wetlands; our findings constrain the contribution from old carbon reservoirs (marine methane hydrates, permafrost and methane trapped under ice) to 19 per cent or less (95 per cent confidence). To the extent that the characteristics of the most recent deglaciation and the Younger Dryas-Preboreal warming are comparable to those of the current anthropogenic warming, our measurements suggest that large future atmospheric releases of methane from old carbon sources are unlikely to occur.

  13. Minimal geological methane emissions during the Younger Dryas-Preboreal abrupt warming event.

    Science.gov (United States)

    Petrenko, Vasilii V; Smith, Andrew M; Schaefer, Hinrich; Riedel, Katja; Brook, Edward; Baggenstos, Daniel; Harth, Christina; Hua, Quan; Buizert, Christo; Schilt, Adrian; Fain, Xavier; Mitchell, Logan; Bauska, Thomas; Orsi, Anais; Weiss, Ray F; Severinghaus, Jeffrey P

    2017-08-23

    Methane (CH 4 ) is a powerful greenhouse gas and plays a key part in global atmospheric chemistry. Natural geological emissions (fossil methane vented naturally from marine and terrestrial seeps and mud volcanoes) are thought to contribute around 52 teragrams of methane per year to the global methane source, about 10 per cent of the total, but both bottom-up methods (measuring emissions) and top-down approaches (measuring atmospheric mole fractions and isotopes) for constraining these geological emissions have been associated with large uncertainties. Here we use ice core measurements to quantify the absolute amount of radiocarbon-containing methane ( 14 CH 4 ) in the past atmosphere and show that geological methane emissions were no higher than 15.4 teragrams per year (95 per cent confidence), averaged over the abrupt warming event that occurred between the Younger Dryas and Preboreal intervals, approximately 11,600 years ago. Assuming that past geological methane emissions were no lower than today, our results indicate that current estimates of today's natural geological methane emissions (about 52 teragrams per year) are too high and, by extension, that current estimates of anthropogenic fossil methane emissions are too low. Our results also improve on and confirm earlier findings that the rapid increase of about 50 per cent in mole fraction of atmospheric methane at the Younger Dryas-Preboreal event was driven by contemporaneous methane from sources such as wetlands; our findings constrain the contribution from old carbon reservoirs (marine methane hydrates, permafrost and methane trapped under ice) to 19 per cent or less (95 per cent confidence). To the extent that the characteristics of the most recent deglaciation and the Younger Dryas-Preboreal warming are comparable to those of the current anthropogenic warming, our measurements suggest that large future atmospheric releases of methane from old carbon sources are unlikely to occur.

  14. Effect of bubble formation on the dissociation of methane hydrate in water: a molecular dynamics study.

    Science.gov (United States)

    Yagasaki, Takuma; Matsumoto, Masakazu; Andoh, Yoshimichi; Okazaki, Susumu; Tanaka, Hideki

    2014-02-20

    We investigate the dissociation of methane hydrate in liquid water using molecular dynamics simulations. As dissociation of the hydrate proceeds, methane molecules are released into the aqueous phase and eventually they form bubbles. It is shown that this bubble formation, which causes change in the methane concentration in the aqueous phase, significantly affects the dissociation kinetics of methane hydrate. A large system size employed in this study makes it possible to analyze the effects of the change in the methane concentration and the formation of bubbles on the dissociation kinetics in detail. It is found that the dissociation rate decreases with time until the bubble formation and then it turns to increase. It is also demonstrated that methane hydrate can exist as a metastable superheated solid if there exists no bubble.

  15. Methane emissions from natural wetlands

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, J.L. [Georgia Univ., Athens, GA (United States); Burke, R.A. Jr. [Environmental Protection Agency, Athens, GA (United States). Environmental Research Lab.

    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.

  16. Methane Clathrate Hydrate Prospecting

    Science.gov (United States)

    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.

  17. Methane emissions from grasslands

    NARCIS (Netherlands)

    Pol - van Dasselaar, van den A.

    1998-01-01

    Introduction

    Methane (CH 4 ) is an important greenhouse gas. The concentration of greenhouse gases in the atmosphere has been increasing since pre-industrial times, mainly due to human activities. This increase gives concern,

  18. Coalbed methane (polemic)

    Energy Technology Data Exchange (ETDEWEB)

    Szczurowski, A. (IPT - Zintegrowane Technologie Procesowe (Poland))

    1994-03-01

    The editorial presents the author's point of view on both extraction and utilization options of CBM and discusses some opinions presented by Mr. Christophersen in the 5th Polish issue of Coalbed Methane Newsletter. Environmental benefits are strongly emphasized.

  19. Formation of methane nano-bubbles during hydrate decomposition and their effect on hydrate growth.

    Science.gov (United States)

    Bagherzadeh, S Alireza; Alavi, Saman; Ripmeester, John; Englezos, Peter

    2015-06-07

    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.

  20. Limited contribution of ancient methane to surface waters of the U.S. Beaufort Sea shelf

    Science.gov (United States)

    Sparrow, Katy J.; Kessler, John D.; Southon, John R.; Garcia-Tigreros, Fenix; Schreiner, Kathryn M.; Ruppel, Carolyn D.; Miller, John B.; Lehman, Scott J.; Xu, Xiaomei

    2018-01-01

    In response to warming climate, methane can be released to Arctic Ocean sediment and waters from thawing subsea permafrost and decomposing methane hydrates. However, it is unknown whether methane derived from this sediment storehouse of frozen ancient carbon reaches the atmosphere. We quantified the fraction of methane derived from ancient sources in shelf waters of the U.S. Beaufort Sea, a region that has both permafrost and methane hydrates and is experiencing significant warming. Although the radiocarbon-methane analyses indicate that ancient carbon is being mobilized and emitted as methane into shelf bottom waters, surprisingly, we find that methane in surface waters is principally derived from modern-aged carbon. We report that at and beyond approximately the 30-m isobath, ancient sources that dominate in deep waters contribute, at most, 10 ± 3% of the surface water methane. These results suggest that even if there is a heightened liberation of ancient carbon–sourced methane as climate change proceeds, oceanic oxidation and dispersion processes can strongly limit its emission to the atmosphere.

  1. Methane Consumption in Marine Waters Impacted by Gas Seepage

    Science.gov (United States)

    Heintz, M. B.; Mau, S.; Valentine, D. L.; Yang, J.; Hallam, S. J.; Reed, J. H.

    2007-12-01

    Microbially mediated methane oxidation in the coastal marine water column is an important sink term in the global methane budget, but remains a relatively uncharacterized process. While oxidation in the water column prevents up to two-thirds of methane released from the sea-floor from transiting to the atmosphere, only a limited number of oxidation rates have been measured, and identities of the microorganisms responsible for methane consumption in this environment remain unknown. To date, there have been no comprehensive studies on the relationship between methane oxidation rates and the microbial population responsible for methane oxidation. As a result of the perennially elevated methane concentrations in the water column at cold seeps, these environments are ideal for investigating the composition and efficacy of pelagic marine methane oxidizing communities. A suite of filter samples were collected, and corresponding methane concentrations and oxidation rates measured, in a series of vertical hydrocasts at seep and background sites in the Santa Barbara and Santa Monica Basins during the SEEPS'07 cruise. Here we present data from samples collected in a grid through the methane plume emanating from the Coal Oil Point (COP) seep field in the Santa Barbara Basin, and from a series of vertical casts above a mud volcano in the Santa Monica Basin. Methane oxidation rate measurements were made using a 3H-CH4 tracer. Preliminary calculations of fractional turnover rates in the water column down- current from the COP seep field indicate a maximum fractional turnover rate of 0.04 day-1 at 50-70 m depth, approximately 25 km from the seep field, along the path of plume advection. In the Santa Monica Basin, fractional turnover rates are highest at the bottom (0.03 day-1 at 800 m), decrease to a minimum (0.002 day-1) at 600 m, and increase from 0.003 day-1 at 300 m to 0.009 day-1 at 25 m. Current molecular work will be presented, and is focused on identifying methanotrophic

  2. [A new assessment for episodic memory. Episodic memory test and caregiver's episodic memory test].

    Science.gov (United States)

    Ojea Ortega, T; González Álvarez de Sotomayor, M M; Pérez González, O; Fernández Fernández, O

    2013-10-01

    The purpose of the episodic memory test and the caregiver's episodic memory test is to evaluate episodic memory according to its definition in a way that is feasible for families and achieves high degrees of sensitivity and specificity. We administered a test consisting of 10 questions about episodic events to 332 subjects, of whom 65 had Alzheimer's disease (AD), 115 had amnestic MCI (aMCI) and 152 showed no cognitive impairment according to Reisberg's global deterioration scale (GDS). We calculated the test's sensitivity and specificity to distinguish AD from episodic aMCI and from normal ageing. The area under the ROC curve for the diagnosis of aMCI was 0.94 and the best cut-off value was 20; for that value, sensitivity was 89% and specificity was 82%. For a diagnosis of AD, the area under the ROC curve was 0.99 and the best cut-off point was 17, with a sensitivity of 98% and a specificity of 91%. A subsequent study using similar methodology yielded similar results when the test was administered directly by the caregiver. The episodic memory test and the caregiver's episodic memory test are useful as brief screening tools for identifying patients with early-stage AD. It is suitable for use by primary care medical staff and in the home, since it can be administered by a caregiver. The test's limitations are that it must be administered by a reliable caregiver and the fact that it measures episodic memory only. Copyright © 2012 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.

  3. Nitrogen oxides and methane treatment by non-thermal plasma

    Science.gov (United States)

    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.

  4. Assessing Biogenic Methane Content in Various Peatland Landforms Using GPR

    Science.gov (United States)

    Parsekian, A.; Comas, X.; Nolan, J.; Glaser, P.; Chanton, J.; Slater, L.

    2008-12-01

    Northern peatlands are known to be a source of biogenic methane, although efforts to accurately quantify their impact on the global carbon budget are ongoing. An important step towards a better understanding of the dynamics of methane releases to the atmosphere is to identify peatland landforms (i.e. raised bog, fen water track, open pools) where gas is accumulating in the subsurface compared to places where there is little subsurface methane. Additionally, it is important to identify areas of the vertical peat profile where high volumes of free-phase methane are present. In this study, we use ground penetrating radar (GPR) to acquire data on where free-phase gas (FPG) methane may be accumulating within the peat strata, and then make comparisons between various peatland landforms. 1-dimensional GPR common mid-point velocity analysis has been coupled with innovative subsurface gas sampling to identify the areas within northern peatlands that have significant gas trapped below confining layers in the subsurface. Gas samples are evaluated for total recovered volume and total methane concentration in order to support the GPR findings. Traditional 2-dimensional radar profiles were used to identify and estimate the depth at which laterally continuous woody confining layers are present, and therefore zones where gas can be expected to be found. By using 1-D, 2-D and direct sampling methods, it is now possible to identify potential areas of gas accumulation with a higher level of confidence.

  5. Methane distribution and transportation in Lake Chaohu: a shallow eutrophic lake in Eastern China

    Science.gov (United States)

    Zhang, L.; Shen, Q.

    2016-12-01

    Global warming and eutrophication are two world widely concerned environmental problems. Methane is the second important greenhouse gas, and lake has been proven as a quite important natural source of methane emission. More methane may emit from eutrophic lake due to the higher organic matter deposition in the lake sediment. Lake Chaohu is a large and shallow eutrophic lake in eastern China (N31°25' 31°43', E117°16' 117°05'), with an area of 770 km2 and a mean depth of 2.7 m. To examine methane distribution and transportation in this eutrophic lake, field study across different seasons was carried out with 20 study sites in the lake. Samples from the different water and sediment depth was collected using headspace bottle, and methane content was measured by gas chromatography using a flame ionization detector. The potential methane production in the sediment was examined by an indoor incubation experiment. Methane flux from sediment to the overlying water was calculated by Fick's law, and methane emission from surface to the air was calculated at the same time. The results indicates that more methane accumulated in the water of northwestern bay in this lake, and higher methane release rates was also found at this area. Methane increases gradually with depth in the top 10 cm in sediment cores, then it almost keeps at constant state in the deeper sediment. In the sediment from northwestern bay, more methane content and the higher potential methane production was found compared to the sediment from the east area of this lake.

  6. Large-scale simulation of methane dissociation along the West Spitzbergen Margin

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Project identification for methane reduction options

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. Factitious psychogenic nonepileptic paroxysmal episodes

    Directory of Open Access Journals (Sweden)

    Alissa Romano

    2014-01-01

    Full Text Available Mistaking psychogenic nonepileptic paroxysmal episodes (PNEPEs for epileptic seizures (ES is potentially dangerous, and certain features should alert physicians to a possible PNEPE diagnosis. Psychogenic nonepileptic paroxysmal episodes due to factitious seizures carry particularly high risks of morbidity or mortality from nonindicated emergency treatment and, often, high costs in wasted medical treatment expenditures. We report a case of a 28-year-old man with PNEPEs that were misdiagnosed as ES. The patient had been on four antiseizure medications (ASMs with therapeutic serum levels and had had multiple intubations in the past for uncontrolled episodes. He had no episodes for two days of continuous video-EEG monitoring. He then disconnected his EEG cables and had an episode of generalized stiffening and cyanosis, followed by jerking and profuse bleeding from the mouth. The manifestations were unusually similar to those of ES, except that he was clearly startled by spraying water on his face, while he was stiff in all extremities and unresponsive. There were indications that he had sucked blood from his central venous catheter to expel through his mouth during his PNEPEs while consciously holding his breath. Normal video-EEG monitoring; the patient's volitional and deceptive acts to fabricate the appearance of illness, despite pain and personal endangerment; and the absence of reward other than remaining in a sick role were all consistent with a diagnosis of factitious disorder.

  9. The Airborne Measurements of Methane Fluxes (AIRMETH) Arctic Campaign (Invited)

    Science.gov (United States)

    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

  10. Terrestrial plant methane production

    DEFF Research Database (Denmark)

    Mikkelsen, Teis Nørgaard; Bruhn, Dan; Møller, Ian M.

    We evaluate all experimental work published on the phenomenon of aerobic methane (CH4) generation in terrestrial plants. We conclude that the phenomenon is true. Four stimulating factors have been observed to induce aerobic plant CH4 production, i.e. cutting injuries, increasing temperature......, ultraviolet radiation and reactive oxygen species. Further, we analyze rates of measured emission of aerobically produced CH4 in pectin and in plant tissues from different studies and argue that pectin is very far from the sole contributing precursor. Hence, scaling up of aerobic CH4 emission needs to take...... the aerobic methane emission in plants. Future work is needed for establishing the relative contribution of several proven potential CH4 precursors in plant material....

  11. Coal Bed Methane Primer

    Energy Technology Data Exchange (ETDEWEB)

    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

  12. Manufacture of methane

    Energy Technology Data Exchange (ETDEWEB)

    Broecker, F.J.; Zirker, G.; Triebskorn, B.; Marosi, L.; Schwarzmann, M.; Dethlefsen, W.; Kaempfer, K.

    1973-11-13

    A process is reported for the manufacture of methane by steam reforming of hydrocarbons of 2 to 30 C atoms or their mixtures on nickel catalysts at superatmospheric pressure, and after-treatment of the resulting cracked gases consisting essentially of carbon monoxide and carbon dioxide, hydrogen, methane, and steam, wherein, in a first process stage, in order to produce gases containing methane, the hydrocarbon vapors or their mixtures together with steam are passed under superatmospheric pressure and at temperatures above 250/sup 0/C through the bed of a practically alkali-free supported nickel catalyst produced from the catalyst precursor Ni/sub 6/Al/sub 2/(OH)/sub 16/.CO/sub 3/.4H/sub 2/O, wherein the catalyst precursor is manufactured by precipitating the compound Ni/sub 6/Al/sub 2/(OH)/sub 16/.CO/sub 3/.4H/sub 2/O from aqueous solution, drying it at a temperature of from 80/sup 0/ to 180/sup 0/C, calcining it at a temperature of from 300/sup 0/ to 550/sup 0/C and subsequently reducing it in a stream of hydrogen, with the proviso that between the drying stage and the calcination stage the temperature is raised at a rate in the range from 1.60/sup 0/ to 3.33/sup 0/C/minute, and the reaction products obtained after passing through the first process stage, in which the catalyst has been kept at temperatures from 300/sup 0/ to 500/sup 0/C by the heat of reaction which was liberated, are cooled, and the gases consisting essentially of methane, hydrogen and carbon monoxide and carbon dioxide are passed, in a further catalytic process stage, under superatmospheric pressure and at temperatures of the gas mixtures from 200/sup 0/ to 300/sup 0/C, through a bed of a low temperature naphtha cracking catalyst containing nickel.

  13. Differentiation of pre-existing trapped methane from thermogenic methane in an igneous-intruded coal by hydrous pyrolysis

    Science.gov (United States)

    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. The Structure of Cognition: Attentional Episodes in Mind and Brain

    Science.gov (United States)

    Duncan, John

    2013-01-01

    Cognition is organized in a structured series of attentional episodes, allowing complex problems to be addressed through solution of simpler subproblems. A “multiple-demand” (MD) system of frontal and parietal cortex is active in many different kinds of tasks, and using data from neuroimaging, electrophysiology, neuropsychology, and cognitive studies of intelligence, I propose a core role for MD regions in assembly of the attentional episode. Monkey and human data show dynamic neural coding of attended information across multiple MD regions, with rapid communication within and between regions. Neuropsychological and imaging data link MD function to fluid intelligence, explaining some but not all “executive” deficits after frontal lobe lesions. Cognitive studies link fluid intelligence to goal neglect, and the problem of dividing complex task requirements into focused parts. Like the innate releasing mechanism of ethology, I suggest that construction of the attentional episode provides a core organizational principle for complex, adaptive cognition. PMID:24094101

  15. Apathy in first episode psychosis patients

    DEFF Research Database (Denmark)

    Evensen, Julie; Røssberg, Jan Ivar; Barder, Helene

    2012-01-01

    Apathy is a common symptom in first episode psychosis (FEP), and is associated with poor functioning. Prevalence and correlates of apathy 10 years after the first psychotic episode remain unexplored.......Apathy is a common symptom in first episode psychosis (FEP), and is associated with poor functioning. Prevalence and correlates of apathy 10 years after the first psychotic episode remain unexplored....

  16. Mass fractionation of noble gases in synthetic methane hydrate: Implications for naturally occurring gas hydrate dissociation

    Science.gov (United States)

    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.

  17. Methane flux from wetlands areas

    OpenAIRE

    BAKER-BLOCKER, ANITA; DONAHUE, THOMAS M.; MANCY, KHALIL H.

    2011-01-01

    Ebullient gases from Michigan wetlands have been collected and analyzed to deduce in situ methane fluxes. Methane flux has been found to be a function of mean air temperature. This relationship has been utilized to extrapolate observed methane fluxes to estimates of fluxes from the Pripet marshes, Sudd, Everglades, and Ugandan swamps. These four wetlands together provide a yearly source of 6.8 × 1013 g of methane to the atmosphere.DOI: 10.1111/j.2153-3490.1977.tb00731.x

  18. Methane hydrate-bearing seeps as a source of aged dissolved organic carbon to the oceans

    Science.gov (United States)

    Pohlman, John; Waite, William F.; Bauer, James E.; Osburn, Christopher L.; Chapman, N. Ross

    2011-01-01

    Marine sediments contain about 500–10,000 Gt of methane carbon1, 2, 3, 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 combined1, 4, but it releases relatively little methane to the ocean and atmosphere5. Sedimentary microbes convert most of the dissolved methane to carbon dioxide6, 7. Here we show that a significant additional product associated with microbial methane consumption is methane-derived dissolved organic carbon. We use Δ14C and δ13C 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 13C, 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 ocean8, and provide reduced organic matter and energy to deep-ocean microbial communities.

  19. High-resolution passive sampling of dissolved methane in the water column of lakes in Greenland

    Science.gov (United States)

    Goldman, A. E.; Cadieux, S. B.; White, J. R.; Pratt, L. M.

    2013-12-01

    Arctic lakes are important participants in the global carbon cycle, releasing methane in a warming climate and contributing to a positive feedback to climate change. In order to yield detailed methane budgets and understand the implications of warming on methane dynamics, high-resolution profiles revealing methane behavior within the water column need to be obtained. Single day sampling using disruptive techniques has the potential to result in biases. In order to obtain high-resolution, undisturbed profiles of methane concentration and isotopic composition, this study evaluates a passive sampling method over a multi-day equilibration period. Selected for this study were two small lakes (Gatos Research Methane Carbon Isotope Analyzer. PDB sampling and pump sampling resulted in statistically similar concentrations (R2=0.89), ranging from 0.85 to 135 uM from PDB and 0.74 to 143 uM from pump sampling. In anoxic waters of the lake, where concentrations were high enough to yield robust isotopic results on the LGR MCIA, δ13C were also similar between the two methods, yielding -73‰ from PDB and -74‰ from pump sampling. Further investigation will produce results for a second lake and methane carbon and hydrogen isotopic composition for both lakes. Preliminary results for this passive sampling method are promising. We envision the use of this technique in future studies of dissolved methane and expect that it will provide a more finely resolved vertical profile, allowing for a more complete understanding of lacustrine methane dynamics.

  20. Imagining the personal past: Episodic counterfactuals compared to episodic memories and episodic future projections

    DEFF Research Database (Denmark)

    Özbek, Müge; Bohn, Annette; Berntsen, Dorthe

    2017-01-01

    Episodic counterfactuals are imagined events that could have happened, but did not happen, in a person’s past. Such imagined past events are important aspects of mental life, affecting emotions, decisions, and behaviors. However, studies examining their phenomenological characteristics and content...... are few. Here we introduced a new method to systematically compare self-generated episodic counterfactuals to self-generated episodic memories and future projections with regard to their phenomenological characteristics (e.g., imagery, emotional valence, rehearsal) and content (e.g., reference to cultural...... distance. The findings show that imagined events are phenomenologically different from memories of experienced events, consistent with reality monitoring theory, and that imagined future events are different from both actual and imagined past events, consistent with some theories of motivation....

  1. Episodic fieldwork, updating, and sociability

    DEFF Research Database (Denmark)

    Whyte, M.

    2013-01-01

    on these relationships. I draw on Simmel's concept of sociability to explore the significance of the recurring updates that are so much a part of long-term and thus episodic fieldwork. Updating suggests participation, positionality, and transformation-as well as play and familiarity. The presumption of familiarity...

  2. Opportunities to reduce methane emissions in the natural gas industry

    Energy Technology Data Exchange (ETDEWEB)

    Cowgill, R.M. [Radian Corporation, Austin, TX (United States)

    1995-12-31

    The U.S. Environmental Protection Agency (EPA) and the Gas Research Institute (GRI) cofunded a project to quantify methane (CH{sub 4}) emissions from the U.S. natural gas industry. Methane, the major constituent of natural gas, is a potent greenhouse gas that is believed to increase the effect of global warming when released to the atmosphere. Reducing emissions from natural gas systems would lessen the greenhouse gas effect attributable to atmospheric CH{sub 4}. Further, mitigation methods to reduce emissions of natural gas, a marketable resource, could save money and increase energy efficiency. This presentation summarizes the major sources and quantity of methane being emitted to the atmosphere for all segments of the U.S. gas industry: production; processing; storage; transmission; and distribution. A description of how those emissions were determined is included here, as well as a discussion of which sources are potential candidates for reducing emissions. (author)

  3. Mechanical instability of monocrystalline and polycrystalline methane hydrates

    Science.gov (United States)

    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

  4. A unique isotopic fingerprint during sulfate-driven anaerobic oxidation of methane

    Science.gov (United States)

    Antler, G.; Turchyn, A. V.; Herut, B.; Sivan, O.

    2014-12-01

    Bacterial sulfate reduction is responsible for the majority of anaerobic methane oxidation in modern marine sediments. This sulfate-driven AOM can often metabolize all the methane produced within marine sediments, preventing any from reaching the overlying ocean. In certain areas, however, methane concentrations are high enough to form bubbles, which can reach the seafloor, only partially metabolized through sulfate-driven AOM; these areas where methane bubbles into the ocean are called cold seeps, or methane seeps. We use the sulfur and oxygen isotopes of sulfate (d34SSO4 and d18OSO4) in locations where sulfate-driven AOM is occurring both in methane seeps as well as lower flux methane transition zones to show that in methane seeps, the d34SSO4 and d18OSO4 data during the coupled sulfate reduction fall into a very narrow range and with a close to linear relationship (slope 0.37± 0.01 (R^2= 0.98, n=52, 95% confidence interval). In the studied environments, considerably different physical properties exist, excluding the possibility that this linear relationship can be attributed to physical processes such as diffusion, advection or mixing of two end-members. This unique isotopic signature emerges during bacterial sulfate reduction by methane in 'cold' seeps and differs when sulfate is reduced by either organic matter oxidation or by a slower, diffusive flux of methane within marine sediments. We show also that this unique isotope fingerprint is preserved in the rock record in authigenic build-ups of carbonates and barite associated with methane seeps, and may serve as a powerful tool for identifying catastrophic methane release in the geological record.

  5. Methane fluxes from tropical coastal lagoons surrounded by mangroves, Yucatán, Mexico

    Science.gov (United States)

    Chuang, P.-C.; Young, M. B.; Dale, A. W.; Miller, L. G.; Herrera-Silveira, J. A.; Paytan, A.

    2017-05-01

    Methane concentrations in the water column and emissions to the atmosphere were determined for three tropical coastal lagoons surrounded by mangrove forests on the Yucatán Peninsula, Mexico. Surface water dissolved methane was sampled at different seasons over a period of 2 years in areas representing a wide range of salinities and anthropogenic impacts. The highest surface water methane concentrations (up to 8378 nM) were measured in a polluted canal associated with Terminos Lagoon. In Chelem Lagoon, methane concentrations were typically lower, except in the polluted harbor area (1796 nM). In the relatively pristine Celestún Lagoon, surface water methane concentrations ranged from 41 to 2551 nM. Methane concentrations were negatively correlated with salinity in Celestún, while in Chelem and Terminos high methane concentrations were associated with areas of known pollution inputs, irrespective of salinity. The diffusive methane flux from surface lagoon water to the atmosphere ranged from 0.0023 to 15 mmol CH4 m-2 d-1. Flux chamber measurements revealed that direct methane release as ebullition was up to 3 orders of magnitude greater than measured diffusive flux. Coastal mangrove lagoons may therefore be an important natural source of methane to the atmosphere despite their relatively high salinity. Pollution inputs are likely to substantially enhance this flux. Additional statistically rigorous data collected globally are needed to better consider methane fluxes from mangrove-surrounded coastal areas in response to sea level changes and anthropogenic pollution in order to refine projections of future atmospheric methane budgets.

  6. Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions

    Science.gov (United States)

    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.

  7. 78 FR 26337 - Methane Hydrate Advisory Committee

    Science.gov (United States)

    2013-05-06

    ... Management's Lower 48 Assessment; Results of Consortium for Ocean Leadership Workshop; Update on International Activity; FY 2013 Methane Hydrate Program Activities and Plans; Draft Interagency Roadmap; Methane...

  8. Methane from wood

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, T. F.; Barreto, L.; Kypreos, S.; Stucki, S

    2005-07-15

    The role of wood-based energy technologies in the Swiss energy system in the long-term is examined using the energy-system Swiss MARKAL model. The Swiss MARKAL model is a 'bottom-up' energy-systems optimization model that allows a detailed representation of energy technologies. The model has been developed as a joint effort between the Energy Economics Group (EEG) at Paul Scherrer Institute PSI) and the University of Geneva and is currently used at PSI-EEG. Using the Swiss MARKAL model, this study examines the conditions under which wood-based energy technologies could play a role in the Swiss energy system, the most attractive pathways for their use and the policy measures that could support them. Given the involvement of PSI in the ECOGAS project, especial emphasis is put on the production of bio-SNG from wood via gasification and methanation of syngas and on hydrothermal gasification of woody biomass. Of specific interest as weIl is the fraction of fuel used in passenger cars that could be produced by locally harvested wood. The report is organized as follows: Section 2 presents a brief description of the MARKAL model. Section 3 describes the results of the base case scenario, which represents a plausible, 'middle-of-the-road' development of the Swiss energy system. Section 4 discusses results illustrating the conditions under which the wood-based methanation technology could become competitive in the Swiss energy market, the role of oil and gas prices, subsidies to methanation technologies and the introduction of a competing technology, namely the wood-based Fischer-Tropsch synthesis. FinaIly, section 5 outlines some conclusions from this analysis. (author)

  9. Methane emission from natural wetlands: interplay between emergent macrophytes and soil microbial processes. A mini-review

    National Research Council Canada - National Science Library

    Hendrikus J. Laanbroek

    2010-01-01

    ... % to the global emission of methane. The range in the estimated percentage of the contribution of these systems to the total release of this greenhouse gas is large due to differences in the nature of the emitting vegetation including...

  10. Imagining the personal past: Episodic counterfactuals compared to episodic memories and episodic future projections

    DEFF Research Database (Denmark)

    Özbek, Müge; Bohn, Annette; Berntsen, Dorthe

    2017-01-01

    Episodic counterfactuals are imagined events that could have happened, but did not happen, in a person’s past. Such imagined past events are important aspects of mental life, affecting emotions, decisions, and behaviors. However, studies examining their phenomenological characteristics and content...

  11. Methane and nitrous oxide in the ice core record.

    Science.gov (United States)

    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.

  12. The strength and rheology of methane clathrate hydrate

    Science.gov (United States)

    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.

  13. Biologically Produced Methane as a Renewable Energy Source.

    Science.gov (United States)

    Holmes, D E; Smith, J A

    2016-01-01

    Methanogens are a unique group of strictly anaerobic archaea that are more metabolically diverse than previously thought. Traditionally, it was thought that methanogens could only generate methane by coupling the oxidation of products formed by fermentative bacteria with the reduction of CO 2 . However, it has recently been observed that many methanogens can also use electrons extruded from metal-respiring bacteria, biocathodes, or insoluble electron shuttles as energy sources. Methanogens are found in both human-made and natural environments and are responsible for the production of ∼71% of the global atmospheric methane. Their habitats range from the human digestive tract to hydrothermal vents. Although biologically produced methane can negatively impact the environment if released into the atmosphere, when captured, it can serve as a potent fuel source. The anaerobic digestion of wastes such as animal manure, human sewage, or food waste produces biogas which is composed of ∼60% methane. Methane from biogas can be cleaned to yield purified methane (biomethane) that can be readily incorporated into natural gas pipelines making it a promising renewable energy source. Conventional anaerobic digestion is limited by long retention times, low organics removal efficiencies, and low biogas production rates. Therefore, many studies are being conducted to improve the anaerobic digestion process. Researchers have found that addition of conductive materials and/or electrically active cathodes to anaerobic digesters can stimulate the digestion process and increase methane content of biogas. It is hoped that optimization of anaerobic digesters will make biogas more readily accessible to the average person. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Small thaw ponds: an unaccounted source of methane in the Canadian high Arctic.

    Science.gov (United States)

    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.

  15. Methane adsorption on activated carbon

    NARCIS (Netherlands)

    Marietta de Rooij; Peter Jansen; Folkert Koopman; Andras Perl; prof. dr. Wim van Gemert

    2014-01-01

    Methane storage in adsorbed form is a promising way to effectively and safely store fuel for vehicular transportation or for any other potential application. In a solid adsorbent, nanometer wide pores can trap methane by van der Waals forces as high density fluid at low pressure and room

  16. Mitigation of methane emission from an old unlined landfill in Klintholm, Denmark using a passive biocover system

    DEFF Research Database (Denmark)

    Scheutz, Charlotte; Pedersen, Rasmus Broen; Petersen, Per Haugsted

    2014-01-01

    Methane generated at landfills contributes to global warming and can be mitigated by biocover systems relying on microbial methane oxidation. As part of a closure plan for an old unlined landfill without any gas management measures, an innovative biocover system was established. The system...... as to their usefulness as bioactive methane oxidizing material and a suitable compost mixture was selected. Whole site methane emission quantifications based on combined tracer release and downwind measurements in combination with several local experimental activities (gas composition within biocover layers, flux...

  17. Reduction of methane emission from landfills using bio-mitigation systems – from lab tests to full scale implementation

    DEFF Research Database (Denmark)

    Kjeldsen, Peter; Scheutz, Charlotte

    Landfills are significant sources of methane, which contributes to climate change. As an alternative to mitigation by gas utilization systems, bio-mitigation systems may be implemented. Such systems are based on microbial methane oxidation in full surface biological covers, so-called biocovers...... due to self-heating processes. Bio-mitigation can be used as a stand-alone technology or combined with active or passive gas collection. When implementing bio-mitigation systems focus should be on additional fugitive methane emissions or the presence of uncontrolled point releases. A protocol...... methane emissions when landfill gas utilization systems cannot be implemented or cease to perform as cost-efficient, sustainable solutions....

  18. Methanation of carbon oxides. History, status quo and future perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Kaltner, W.; Rakoczy, R.A. [Clariant SE, Muenchen (Germany)

    2012-07-01

    With increasing demand in fossil sources and especially crude oil based energy carrier, proven reserves will be diminishing. Besides alternative and sustainable sources the conversion of coal into fuels which can be distributed within the existing infrastructure becomes extremely important in areas of fast growing energy demand. Driver for these technologies is mostly the lack of crude oil and availability of coal like in China or South Africa. The most common way to convert coal into chemicals and fuels is the gasification to yield a gas mixture known as synthesis gas. Synthesis gas can be converted in highly pure methane used as 'substitute natural gas' (SNG) in gas grids of major cities to produce heat at home and industry. All available SNG technologies are characterized by the difficulty to control the extreme heat release of the methanation reaction. This presentation will give an overview on available gasification and methanation technologies from recent point of view. A lot of processes are already described in literature and there are pilot and real plants for methanation and especially SNG built. Moreover, a new process to produce methane from synthesis gas without the need of recycle streams and high temperatures will be introduced. This novel process developed by Foster Wheeler - using catalysts from Clariant - is called 'VESTA Process' in accordance with the Roman goddess of hearth and fire. (orig.)

  19. A modeling study of methane hydrate decomposition in contact with the external surface of zeolites.

    Science.gov (United States)

    Smirnov, Konstantin S

    2017-08-30

    The behavior of methane hydrate (MH) enclosed between the (010) surfaces of the silicalite-1 zeolite was studied by means of molecular dynamics simulations at temperatures of 150 and 250 K. Calculations reveal that the interaction with the hydrophilic surface OH groups destabilizes the clathrate structure of hydrate. While MH mostly conserves the structure in the simulation at the low temperature, thermal motion at the high temperature breaks the fragilized cages of H-bonded water molecules, thus leading to the release of methane. The dissociation proceeds in a layer-by-layer manner starting from the outer parts of the MH slab until complete hydrate decomposition. The released CH 4 molecules are absorbed by the microporous solid, whereas water is retained at the surfaces of hydrophobic silicalite and forms a meniscus in the interlayer space. Methane uptake reaches 70% of the silicalite sorption capacity. The energy necessary for the endothermic MH dissociation is supplied by the exothermic methane absorption by the zeolite.

  20. Motivation and episodic memory performance

    OpenAIRE

    Ngaosuvan, Leonard

    2004-01-01

    In everyday life, motivation and learning are connected like music and dancing. Many educators realize this and work hard to improve their students' motivation. A motivated student may repeat and self-rehearse the content of a chapter more often, which leads to better learning. However, from a cognitive psychology point of view, it is still uncertain if motivation without differences in repetition or attention, affects episodic memory performance. That is, would a motivated student perform be...

  1. Quantifying Urban Natural Gas Leaks from Street-level Methane Mapping: Measurements and Uncertainty

    Science.gov (United States)

    von Fischer, J. C.; Ham, J. M.; Griebenow, C.; Schumacher, R. S.; Salo, J.

    2013-12-01

    Leaks from the natural gas pipeline system are a significant source of anthropogenic methane in urban settings. Detecting and repairing these leaks will reduce the energy and carbon footprints of our cities. Gas leaks can be detected from spikes in street-level methane concentrations measured by analyzers deployed on vehicles. While a spike in methane concentration indicates a leak, an algorithm (e.g., inverse model) must be used to estimate the size of the leak (i.e., flux) from concentration data and supporting meteorological information. Unfortunately, this drive-by approach to leak quantification is confounded by the complexity of urban roughness, changing weather conditions, and other incidental factors (e.g., traffic, vehicle speed, etc.). Furthermore, the vehicle might only pass through the plume one to three times during routine mapping. The objective of this study was to conduct controlled release experiments to better quantify the relationship between mobile methane concentration measurements and the size and location of the emission source (e.g., pipeline leakage) in an urban environment. A portable system was developed that could release methane at known rates between 10 and 40 LPM while maintaining concentrations below the lower explosive limit. A mapping vehicle was configured with fast response methane analyzers, GPS, and meteorological instruments. Portable air-sampling tripods were fabricated that could be deployed at defined distances downwind from the release point and automatically-triggered to collect grab samples. The experimental protocol was as follows: (1) identify an appropriate release point within a city, (2) release methane at a known rate, (3) measure downwind street-level concentrations with the vehicle by making multiple passes through the plume, and (4) collect supporting concentration and meteorological data with the static tripod samplers deployed in the plume. Controlled release studies were performed at multiple locations and

  2. Methane production and methane consumption: a review of processes underlying wetland methane fluxes.

    NARCIS (Netherlands)

    Segers, R.

    1998-01-01

    Potential rates of both methane production and methane consumption vary over three orders of magnitude and their distribution is skew. These rates are weakly correlated with ecosystem type, incubation temperature, in situ aeration, latitude, depth and distance to oxic/anoxic interface. Anaerobic

  3. Estimating Landfill Methane Oxidation Using the Information of CO2/CH4 Fluxes Measured By the Eddy Covariance Method

    Science.gov (United States)

    Xu, L.; McDermitt, D. K.; Li, J.; Green, R. B.

    2016-12-01

    Methane plays a critical role in the radiation balance and chemistry of the atmosphere. Globally, landfill methane emission contributes about 10-19% of the anthropogenic methane burden into the atmosphere. In the United States, 18% of annual anthropogenic methane emissions come from landfills, which represent the third largest source of anthropogenic methane emissions, behind enteric fermentation and natural gas and oil production. One uncertainty in estimating landfill methane emissions is the fraction of methane oxidized when methane produced under anaerobic conditions passes through the cover soil. We developed a simple stoichiometric model to estimate the landfill methane oxidation fraction when the anaerobic CO2/CH4 production ratio is known. The model predicts a linear relationship between CO2 emission rates and CH4 emission rates, where the slope depends on anaerobic CO2/CH4 production ratio and the fraction of methane oxidized, and the intercept depends on non-methane-dependent oxidation processes. The model was tested with eddy covariance CO2 and CH4 emission rates at Bluff Road Landfill in Lincoln Nebraska. It predicted zero oxidation rate in the northern portion of this landfill where a membrane and vents were present. The zero oxidation rate was expected because there would be little opportunity for methane to encounter oxidizing conditions before leaving the vents. We also applied the model at the Turkey Run Landfill in Georgia to estimate the CH4 oxidation rate over a one year period. In contrast to Bluff Road Landfill, the Turkey Run Landfill did not have a membrane or vents. Instead, methane produced in the landfill had to diffuse through a 0.5 m soil cap before release to the atmosphere. We observed evidence for methane oxidation ranging from about 18% to above 60% depending upon the age of deposited waste material. The model will be briefly described, and results from the two contrasting landfills will be discussed in this presentation.

  4. Timescales of methane seepage on the Norwegian margin following collapse of the Scandinavian Ice Sheet

    OpenAIRE

    Cremiere, Antoine; Lepland, Aivo; Chand, Shyam; Sahy, Diana; Daniel J. Condon; Noble, Stephen R.; Martma, Tõnu; Thorsnes, Terje; Sauer, Simone; Brunstad, Harald

    2016-01-01

    Source: doi: 10.1038/ncomms11509 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 thicke...

  5. Catalysis by Atomic-Sized Centers: Methane Activation for Partial Oxidation and Combustion

    Science.gov (United States)

    2015-07-21

    AFRL-OSR-VA-TR-2015-0195 CATALYSIS BY ATOMIC-SIZED CENTERS: METHANE ACTIVATION FOR PARTIAL OXIDATION AND COMBUSTION Horia Metiu UNIVERSITY OF...To) 01-04-2012 to 31-03-2015 4. TITLE AND SUBTITLE CATALYSIS BY ATOMIC-SIZED CENTERS: METHANE ACTIVATION FOR PARTIAL OXIDATION AND COMBUSTION 5a...livelink/llisapi.dll DISTRIBUTION A: Distribution approved for public release. Final Technical Report, FA9550-12-1-0147 “ CATALYSIS BY ATOMIC-SIZED

  6. Economic tools for realization of methane production project on Kuzbass coal deposits

    Science.gov (United States)

    Sharf, I.; Sokolova, M.; Kochetkova, O.; Dmitrieva, N.

    2016-09-01

    Environmental issues and, above all, issues related to the release of greenhouse gases into the atmosphere, such as coal bed methane, actualize the challenge of searching a variety of options for its disposal. The difference in the macroeconomic, industrial, geological and infrastructural features determine the need to choose the most cost-effective option for using of methane emitted from the coal deposits. Various economic ways to improve the profitability of production are viewed on the basis of the analysis of methane production project from Kuzbass coal deposits, Kemerovo region, Russia.

  7. Early detection of first-episode psychosis

    DEFF Research Database (Denmark)

    Larsen, Tor K; Melle, Ingrid; Auestad, Bjørn

    2006-01-01

    Early intervention is assumed to improve outcome in first-episode psychosis, but this has not been proven.......Early intervention is assumed to improve outcome in first-episode psychosis, but this has not been proven....

  8. Global synthesis and simulation of forest harvest impacts on soil methane fluxes

    Science.gov (United States)

    Hayes, D. J.; Chen, G.; Tian, H.

    2016-12-01

    Disturbance is a major driver of biogeochemical cycling and energy flux in forest ecosystems, and clear-cut harvesting is one of primary modes of forest disturbance. Although the impacts of harvest and post-disturbance regeneration on carbon stocks have been well-studied, little is known about the response of methane - a key greenhouse gas for climate warming. Here we describe the results of a meta-data analysis of field observations and experiments that 1) offers new understanding of the mechanisms controlling forest harvest effects on soil methane fluxes and 2) provides necessary data to include these mechanisms in an ecosystem modeling framework. The results indicate that about half of the forest soil methane sink was reduced after harvesting within several years. In addition, soils for some forests were converted from a net methane sink to a net source due to altered soil moisture and nutrient conditions post-disturbance. Based on our synthesis of for methane flux and other associated biogeochemical dynamics, we improved and parameterized a process-based, coupled carbon-nitrogen-water model to simulate methane fluxes due to forest harvest globally. The simulation results indicate that the global methane sink in forests has been greatly reduced because of methane releases in some forests and decreased methane uptake in others. Large spatial variation in the response of methane flux to forest harvest are found, primarily controlled by the differences in climate, soil physical and biogeochemical conditions, and land surface geomorphogical and vegetation characteristics. The effect on soil methane fluxes from forest harvest is also compared with that from global climate and other environmental changes. Our study suggests that the shorter forest rotation due to increasing demands on forest products could greatly result in increasing greenhouse effects.

  9. 78 FR 37536 - Methane Hydrate Advisory Committee

    Science.gov (United States)

    2013-06-21

    ... meeting. SUMMARY: This notice announces a meeting of the Methane Hydrate Advisory Committee. The Federal... of the Methane Hydrate Advisory Committee is to provide advice on potential applications of methane... Department of Energy's Methane Hydrate Research and Development Program. Tentative Agenda: The agenda will...

  10. Methane Hydrates: Chapter 8

    Science.gov (United States)

    Boswell, Ray; Yamamoto, Koji; Lee, Sung-Rock; Collett, Timothy S.; Kumar, Pushpendra; Dallimore, Scott

    2008-01-01

    Gas hydrate is a solid, naturally occurring substance consisting predominantly of methane gas and water. Recent scientific drilling programs in Japan, Canada, the United States, Korea and India have demonstrated that gas hydrate occurs broadly and in a variety of forms in shallow sediments of the outer continental shelves and in Arctic regions. Field, laboratory and numerical modelling studies conducted to date indicate that gas can be extracted from gas hydrates with existing production technologies, particularly for those deposits in which the gas hydrate exists as pore-filling grains at high saturation in sand-rich reservoirs. A series of regional resource assessments indicate that substantial volumes of gas hydrate likely exist in sand-rich deposits. Recent field programs in Japan, Canada and in the United States have demonstrated the technical viability of methane extraction from gas-hydrate-bearing sand reservoirs and have investigated a range of potential production scenarios. At present, basic reservoir depressurisation shows the greatest promise and can be conducted using primarily standard industry equipment and procedures. Depressurisation is expected to be the foundation of future production systems; additional processes, such as thermal stimulation, mechanical stimulation and chemical injection, will likely also be integrated as dictated by local geological and other conditions. An innovative carbon dioxide and methane swapping technology is also being studied as a method to produce gas from select gas hydrate deposits. In addition, substantial additional volumes of gas hydrate have been found in dense arrays of grain-displacing veins and nodules in fine-grained, clay-dominated sediments; however, to date, no field tests, and very limited numerical modelling, have been conducted with regard to the production potential of such accumulations. Work remains to further refine: (1) the marine resource volumes within potential accumulations that can be

  11. Intercomparison of eight state-of-the-art eddy covariance methane gas analysers

    Science.gov (United States)

    Peltola, Olli; Hensen, Arjan; Helfter, Carole; Belelli Marchesini, Luca; Mammarella, Ivan; Haapanala, Sami; Holst, Jutta; Elbers, Jan; Bosveld, Fred; van den Bulk, Pim; Röckmann, Thomas; Lindroth, Anders; Laurila, Tuomas; Vermeulen, Alex; Nemitz, Eiko

    2013-04-01

    During the last decade several gas analysers became available that are capable of measuring methane concentration with high sampling frequency needed for eddy covariance measurements. These new gas analysers require less maintenance compared with the models used in the 1990's and they give more reliable estimates for the ecosystem scale methane fluxes. However, with different instrument types available now, their performance should be crosscompared and validated. A gas analyser intercomparison campaign was held at Cabauw measurement station in the Netherlands between 6th and 27th of June, 2012. The campaign was organized within the InGOS FP7 project. Cabauw is well-established site with a long history in greenhouse gas monitoring and the surrounding landscape is a considerable source of methane. In total eight methane gas analysers manufactured by Picarro Inc., Los Gatos Research, Aerodyne Research Inc. and LI-COR Inc. were used in the experiment. Tentative results show relatively good agreement between the eight methane flux estimates and they also agree with previous studies done at the site. Magnitude and variation of the flux estimates are similar. Cumulative methane emissions calculated from not gapfilled data during a 10 day episode agree within 10 %, values ranging from 190 mg(CH4) m-2 to 210 mg(CH4) m-2. Comparison of random errors of the measured methane fluxes did not reveal any big differences between the instruments. Some of the gas analysers measuring methane were also capable of measuring water vapour at the same time. This is a big asset during data processing, since effect of water vapour on methane concentration measurement can then be easily corrected without need of additional water vapour measurement. The presentation will discuss the intercomparison campaign setup, instrument performance and will provide recommendations for CH4-EC measurements.

  12. Observations of mass fractionation of noble gases in synthetic methane hydrate

    Science.gov (United States)

    Hunt, Andrew G.; Pohlman, John; Stern, Laura A.; Ruppel, Carolyn D.; Moscati, Richard J.; Landis, Gary P.; Pinkston, John C.

    2011-01-01

    As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings are presently dissociating and releasing methane and other gases to the oceanatmosphere system. A key challenge in assessing the susceptibility of gas hydrates to warming climate is the lack of a technique able to distinguish between methane recently released from gas hydrates and methane emitted from leaky thermogenic reservoirs, shallow sublake and subseafloor sediments, coalbeds, and other sources. Carbon and deuterium stable isotopic data provide only a first-order characterization of methane sources, while gas hydrate can sequester any type of methane. Here, we investigate the possibility of exploiting the pattern of noble gas fractionation within the gas hydrate lattice to fingerprint methane released from gas hydrates. Starting with synthetic gas hydrate formed under careful 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.

  13. The Apparent Involvement of ANMEs in Mineral Dependent Methane Oxidation, as an Analog for Possible Martian Methanotrophy

    Directory of Open Access Journals (Sweden)

    Victoria J. Orphan

    2011-11-01

    Full Text Available On Earth, marine anaerobic methane oxidation (AOM can be driven by the microbial reduction of sulfate, iron, and manganese. Here, we have further characterized marine sediment incubations to determine if the mineral dependent methane oxidation involves similar microorganisms to those found for sulfate-dependent methane oxidation. Through FISH and FISH-SIMS analyses using 13C and 15N labeled substrates, we find that the most active cells during manganese dependent AOM are primarily mixed and mixed-cluster aggregates of archaea and bacteria. Overall, our control experiment using sulfate showed two active bacterial clusters, two active shell aggregates, one active mixed aggregate, and an active archaeal sarcina, the last of which appeared to take up methane in the absence of a closely-associated bacterial partner. A single example of a shell aggregate appeared to be active in the manganese incubation, along with three mixed aggregates and an archaeal sarcina. These results suggest that the microorganisms (e.g., ANME-2 found active in the manganese-dependent incubations are likely capable of sulfate-dependent AOM. Similar metabolic flexibility for Martian methanotrophs would mean that the same microbial groups could inhabit a diverse set of Martian mineralogical crustal environments. The recently discovered seasonal Martian plumes of methane outgassing could be coupled to the reduction of abundant surface sulfates and extensive metal oxides, providing a feasible metabolism for present and past Mars. In an optimistic scenario Martian methanotrophy consumes much of the periodic methane released supporting on the order of 10,000 microbial cells per cm2 of Martian surface. Alternatively, most of the methane released each year could be oxidized through an abiotic process requiring biological methane oxidation to be more limited. If under this scenario, 1% of this methane flux were oxidized by biology in surface soils or in subsurface aquifers (prior to

  14. Methane gas seepage - Disregard of significant water column filter processes?

    Science.gov (United States)

    Schneider von Deimling, Jens; Schmale, Oliver

    2016-04-01

    Marine methane seepage represents a potential contributor for greenhouse gas in the atmosphere and is discussed as a driver for climate change. The ultimate question is how much methane is released from the seafloor on a global scale and what fraction may reach the atmosphere? Dissolved fluxes from methane seepage sites on the seabed were found to be very efficiently reduced by benthic microbial oxidation, whereas transport of free gas bubbles from the seabed is considered to bypass the effective benthic methane filter. Numerical models are available today to predict the fate of such methane gas bubble release to the water column in regard to gas exchange with the ambient water column, respective bubble lifetime and rise height. However, the fate of rising gas bubbles and dissolved methane in the water column is not only governed by dissolution, but is also affected by lateral oceanographic currents and vertical bubble-induced upwelling, microbial oxidation, and physico-chemical processes that remain poorly understood so far. According to this gap of knowledge we present data from two study sites - the anthropogenic North Sea 22/4b Blowout and the natural Coal Oil point seeps - to shed light into two new processes gathered with hydro-acoustic multibeam water column imaging and microbial investigations. The newly discovered processes are hereafter termed Spiral Vortex and Bubble Transport Mechanism. Spiral Vortex describes the evolution of a complex vortical fluid motion of a bubble plume in the wake of an intense gas release site (Blowout, North Sea). It appears very likely that it dramatically changes the dissolution kinetics of the seep gas bubbles. Bubble Transport Mechanism prescribes the transport of sediment-hosted bacteria into the water column via rising gas bubbles. Both processes act as filter mechanisms in regard to vertical transport of seep related methane, but have not been considered before. Spiral Vortex and Bubble Transport Mechanism represent the

  15. Anthropogenic methane ebullition and continuous flux measurement

    Science.gov (United States)

    Alshboul, Zeyad

    2017-04-01

    Keywords: Methane, Wastewater, Effluent, Anaerobic treatment. Municipal wastewater treatment plants (WWTPs) have shown to emit significant amount of methane during treatment processes. While most of studies cover only in-plant diffusive methane flux, magnitude and sources of methane ebullition have not well assessed. Moreover, the reported results of methane emissions from WWTPs are based on low spatial and temporal resolution. Using a continuous measurement approach of methane flux rate for effluent system and secondary clarifier treatment process at one WWTP in Southwest Germany, our results show that high percentage of methane is emitted by ebullition during the anaerobic treatment (clarification pond) with high spatial and temporal variability. Our measurements revealed that no ebullition is occur at the effluent system. The observed high contribution of methane ebullition to the total in-plant methane emission, emphasizes the need for considering in-plant methane emission by ebullition as well as the spatial and temporal variability of these emissions.

  16. Recent advances in methane activation

    Energy Technology Data Exchange (ETDEWEB)

    Huuska, M.; Kataja, K. [VTT Chemical Technology, Espoo (Finland)

    1996-12-31

    Considerable work has been done in the research and development of methane conversion technologies. Although some promising conversion processes have been demonstrated, further advances in engineering and also in the chemistry are needed before these technologies become commercial. High-temperature processes, e.g. the oxidative coupling of methane, studied thoroughly during the last 15 years, suffer from severe theoretical yield limits and poor economics. In the long term, the most promising approaches seem to be the organometallic and, especially, the biomimetic activation of methane. (author) (22 refs.)

  17. Mobile mapping of methane emissions and isoscapes

    Science.gov (United States)

    Takriti, Mounir; Ward, Sue; Wynn, Peter; Elias, Dafydd; McNamara, Niall

    2017-04-01

    Methane (CH4) is a potent greenhouse gas emitted from a variety of natural and anthropogenic sources. It is crucial to accurately and efficiently detect CH4 emissions and identify their sources to improve our understanding of changing emission patterns as well as to identify ways to curtail their release into the atmosphere. However, using established methods this can be challenging as well as time and resource intensive due to the temporal and spatial heterogeneity of many sources. To address this problem, we have developed a vehicle mounted mobile system that combines high precision CH4 measurements with isotopic mapping and dual isotope source characterisation. We here present details of the development and testing of a unique system for the detection and isotopic analysis of CH4 plumes built around a Picarro isotopic (13C/12C) gas analyser and a high precision Los Gatos greenhouse gas analyser. Combined with micrometeorological measurements and a mechanism for collecting discrete samples for high precision dual isotope (13C/12C, 2H/1H) analysis the system enables mapping of concentrations as well as directional and isotope based source verification. We then present findings from our mobile methane surveys around the North West of England. This area includes a variety of natural and anthropogenic methane sources within a relatively small geographical area, including livestock farming, urban and industrial gas infrastructure, landfills and waste water treatment facilities, and wetlands. We show that the system was successfully able to locate leaks from natural gas infrastructure and emissions from agricultural activities and to distinguish isotope signatures from these sources.

  18. Methane emission reduction: an application of FUND

    OpenAIRE

    Tol, R.S.J.; Heintz, R.J.; Lammers, P.E.M.

    2003-01-01

    Methane is, after carbon dioxide, the most important anthropogenic greenhouse gas. Governments plan to abate methane emissions. A crude set of estimates of reduction costs is included in FUND, an integrated assessment model of climate change. In a cost-benefit analysis, methane emission reduction is found to be instrumental in controlling the optimal rate of climate change. In a cost-effectiveness analysis, methane emission reduction largely replaces carbon dioxide emission reduction. Methane...

  19. Episodic Excessive Blinking in Children.

    Science.gov (United States)

    Mali, Yasmin Poustchi; Simon, John W; Chaudhri, Imran; Zobal-Ratner, Jitka; Barry, Gerard P

    2016-01-01

    Many children present with excessive blinking. Categorization, associated conditions, and prognosis are controversial. All children with excessive blinking were reviewed, excluding those with known uveitis, glaucoma, or obvious eyelid abnormalities. Parents were telephoned for follow-up. No ocular pathology was identified in 31 of 34 children with excessive blinking (91%). Parents were able to report a specific cause of blinking in 7 (21%). In 24 of 34 (71%), parents reported complete resolution of excessive blinking. No new ophthalmologic diagnoses were uncovered on follow-up. Episodes of excessive blinking rarely indicate neurologic disorders and frequently resolve spontaneously. Copyright 2016, SLACK Incorporated.

  20. Assessment of the methane oxidation capacity of compacted soils intended for use as landfill cover materials.

    Science.gov (United States)

    Rachor, Ingke; Gebert, Julia; Gröngröft, Alexander; Pfeiffer, Eva-Maria

    2011-05-01

    The microbial oxidation of methane in engineered cover soils is considered a potent option for the mitigation of emissions from old landfills or sites containing wastes of low methane generation rates. A laboratory column study was conducted in order to derive design criteria that enable construction of an effective methane oxidising cover from the range of soils that are available to the landfill operator. Therefore, the methane oxidation capacity of different soils was assessed under simulated landfill conditions. Five sandy potential landfill top cover materials with varying contents of silt and clay were investigated with respect to methane oxidation and corresponding soil gas composition over a period of four months. The soils were compacted to 95% of their specific proctor density, resulting in bulk densities of 1.4-1.7 g cm(-3), reflecting considerably unfavourable conditions for methane oxidation due to reduced air-filled porosity. The soil water content was adjusted to field capacity, resulting in water contents ranging from 16.2 to 48.5 vol.%. The investigated inlet fluxes ranged from 25 to about 100g CH(4)m(-2)d(-1), covering the methane load proposed to allow for complete oxidation in landfill covers under Western European climate conditions and hence being suggested as a criterion for release from aftercare. The vertical distribution of gas concentrations, methane flux balances as well as stable carbon isotope studies allowed for clear process identifications. Higher inlet fluxes led to a reduction of the aerated zone, an increase in the absolute methane oxidation rate and a decline of the relative proportion of oxidized methane. For each material, a specific maximum oxidation rate was determined, which varied between 20 and 95 g CH(4)m(-2)d(-1) and which was positively correlated to the air-filled porosity of the soil. Methane oxidation efficiencies and gas profile data imply a strong link between oxidation capacity and diffusive ingress of

  1. [Mixed episode: complex recognition and complicated treatment].

    Science.gov (United States)

    Gargoloff, Pedro Rafael

    2003-01-01

    Mixed Episode is a complex syndrome with difficult in its recognition, the most prolonged duration of bipolar episodes, more frequent psychotic profile than Pure Manic Episode, with high suicidality and poor response to drugs. There are evidences of less efficacy with Lithium and Carbamazepine in Manic Episode than mixed states. Valproate improve both, manic and depressive symptoms, and it is proposed to be first choice. Olanzapine has been widely evaluated, showing robust response in acute Mania as well in depressive symptoms during Mixed episode. In the field of clinical practice, there are many patients receiving more than one drug, usually Valproate plus a second generation antipsychotic.

  2. Methane oxidation in contrasting soil types

    DEFF Research Database (Denmark)

    D'Imperio, Ludovica; Nielsen, Cecilie Skov; Westergaard-Nielsen, Andreas

    2017-01-01

    Arctic ecosystems are characterized by a wide range of soil moisture conditions and thermal regimes and contribute differently to the net methane (CH4) budget. Yet, it is unclear how climate change will affect the capacity of those systems to act as a net source or sink of CH4. Here, we present...... of CH4 tended to increase by 20% with OTCs. Bare and dry tundra ecosystems should be considered in the net CH4 budget of the Arctic due to their potential role in counterbalancing CH4 emissions from wetlands – not the least when taking the future climatic scenarios of the Arctic into account....... subsequently scaled to the entire study area of 0.15 km2, a landscape also consisting of wetlands with a seasonally integrated methane release of 0.10 ± 0.01 g CH4-C m−2 (3.7 ± 1.2 g CO2-eq m−2). The result was a net landscape sink of 12.71 kg CH4-C (0.48 tonne CO2-eq) during the growing season...

  3. Transport of dissolved gas and its ecological impact after a gas release from deepwater.

    Science.gov (United States)

    Wimalaratne, Malinda R; Yapa, Poojitha D; Nakata, Kisaburo; Premathilake, Lakshitha T

    2015-11-15

    Previous models on simulating gas releases in deepwater were not focused on the dissolved component and its impact on water quality. This paper presents a new model developed for simulating the transport/spread of dissolved methane from an underwater release and its impact on dissolved oxygen in ambient water. Methane dissolves into ambient water from gas phase, direct from hydrate phase, and from dissociating hydrates formed earlier. Dissolved methane affects the dissolved oxygen levels in ambient water due to microbial interaction and possible direct absorption of oxygen into methane bubbles. We use new model simulations of Deepspill field experiments to compare with instantaneous profiles which were unpublished until now. The comparisons are very good with a short time lag, but are within the acceptable discrepancy for models for emergency response and contingency planning. Scenario simulations show the effect on dissolved oxygen due to different methane release situations. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Methane Liquid Level Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced Technologies Group, Inc. proposes the development of a Methane Liquid-Level Sensor, (MLS) for In-Space cryogenic storage capable of continuous monitoring of...

  5. Biological hydrogen methanation - A review.

    Science.gov (United States)

    Lecker, Bernhard; Illi, Lukas; Lemmer, Andreas; Oechsner, Hans

    2017-12-01

    Surplus energy out of fluctuating energy sources like wind and solar energy is strongly increasing. Biological hydrogen (H 2 ) methanation (BHM) is a highly promising approach to move the type of energy from electricity to natural gas via electrolysis and the subsequent step of the Sabatier-reaction. This review provides an overview of the numerous studies concerning the topic of BHM. The technical and biological parameters regarding the research results of these studies are compared and analyzed hereafter. A holistic view on how to overcome physical limitations of the fermentation process, such as gas-liquid mass transfer or a rise of the pH value, and on the enhancement of environmental circumstances for the bacterial biomass are delivered within. With regards to ex-situ methanation, the evaluated studies show a distinct connection between methane production and the methane percentage in the off-gas. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Oxygen-Methane Thruster Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Two main innovations will be developed in the Phase II effort that are fundamentally associated with our gaseous oxygen/gaseous methane RCS thruster. The first...

  7. Oxygen-Methane Thruster Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Orion Propulsion, Inc. proposes to develop an Oxygen and Methane RCS Thruster to advance the technology of alternate fuels. A successful Oxygen/CH4 RCS Thruster will...

  8. Miniature Airborne Methane Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — KalScott Engineering, and the subcontractor, Princeton University propose the development and demonstration of compact and robust methane sensor for small Unmanned...

  9. Methane LIDAR Laser Technology Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Fibertek proposes to develop laser technology intended to meet NASA's need for innovative lidar technologies for atmospheric measurements of methane. NASA and the...

  10. Episodic memories in anxiety disorders: Clinical implications

    Directory of Open Access Journals (Sweden)

    Armin eZlomuzica

    2014-04-01

    Full Text Available The aim of this review is to summarize research on the emerging role of episodic memories in the context of anxiety disorders (AD. The available literature on explicit-, autobiographical- and episodic memory function in AD including neuroimaging studies is critically discussed. We describe the methodological diversity of episodic memory research in AD and discuss the need for novel tests to measure episodic memory in a clinical setting. We argue that alterations in episodic memory functions might contribute to the etiology of AD. We further explain why future research on the interplay between episodic memory function and emotional disorders as well as its neuroanatomical foundations offers the promise to increase the effectiveness of modern psychological treatments. We conclude that one major task is to develop methods and training programs that might help patients suffering from AD to better understand, interpret and possibly actively use their episodic memories in a way that would support therapeutic interventions and counteract the occurrence of symptoms.

  11. Episodic Memories in Anxiety Disorders: Clinical Implications

    Science.gov (United States)

    Zlomuzica, Armin; Dere, Dorothea; Machulska, Alla; Adolph, Dirk; Dere, Ekrem; Margraf, Jürgen

    2014-01-01

    The aim of this review is to summarize research on the emerging role of episodic memories in the context of anxiety disorders (AD). The available literature on explicit, autobiographical, and episodic memory function in AD including neuroimaging studies is critically discussed. We describe the methodological diversity of episodic memory research in AD and discuss the need for novel tests to measure episodic memory in a clinical setting. We argue that alterations in episodic memory functions might contribute to the etiology of AD. We further explain why future research on the interplay between episodic memory function and emotional disorders as well as its neuroanatomical foundations offers the promise to increase the effectiveness of modern psychological treatments. We conclude that one major task is to develop methods and training programs that might help patients suffering from AD to better understand, interpret, and possibly actively use their episodic memories in a way that would support therapeutic interventions and counteract the occurrence of symptoms. PMID:24795583

  12. Methane Propulsion Elements for Mars

    Science.gov (United States)

    Percy, Tom; Polsgrove, Tara; Thomas, Dan

    2017-01-01

    Human exploration beyond LEO relies on a suite of propulsive elements to: (1) Launch elements into space, (2) Transport crew and cargo to and from various destinations, (3) Provide access to the surface of Mars, (4) Launch crew from the surface of Mars. Oxygen/Methane propulsion systems meet the unique requirements of Mars surface access. A common Oxygen/Methane propulsion system is being considered to reduce development costs and support a wide range of primary & alternative applications.

  13. Snails promote methane release from a freshwater lake ecosystem

    Directory of Open Access Journals (Sweden)

    Xiao eXu

    2014-05-01

    Full Text Available Benthic fauna, as ecosystem engineers, can strongly affect microbial-driven ecosystem biogeochemical cycling. However, the effects of benthic fauna, especially epifauna, on CH4 cycling remain still elusive. In this study, CH4 effluxes were both measured along a gradient of snail density in a freshwater lake ecosystem in China, and monitored in manipulated laboratory microcosms with and without snails. Field CH4 efflux was significantly increased with snail density. Likewise, the stimulating effects of freshwater snails on CH4 effluxes were evident in the homogenised indoor microcosms. These results show that snails can stimulate CH4 efflux in the freshwater lake ecosystem. Moreover, the average efflux of CH4 emitted from snails’ habitats has reached 15.33 mg CH4-C m-2 d-1. By comparing with those emitted from vegetated coastal marsh and alpine wetland, this data indicates that snails’ habitats are strong sources of CH4 in a freshwater ecosystem. This study suggests identifying and modeling epifauna activity as a function of CH4 cycling could improve the mechanistic understanding of wetland biogeochemical cycling responses to climate change.

  14. Episodic future thinking and episodic counterfactual thinking: intersections between memory and decisions.

    Science.gov (United States)

    Schacter, Daniel L; Benoit, Roland G; De Brigard, Felipe; Szpunar, Karl K

    2015-01-01

    This article considers two recent lines of research concerned with the construction of imagined or simulated events that can provide insight into the relationship between memory and decision making. One line of research concerns episodic future thinking, which involves simulating episodes that might occur in one's personal future, and the other concerns episodic counterfactual thinking, which involves simulating episodes that could have happened in one's personal past. We first review neuroimaging studies that have examined the neural underpinnings of episodic future thinking and episodic counterfactual thinking. We argue that these studies have revealed that the two forms of episodic simulation engage a common core network including medial parietal, prefrontal, and temporal regions that also supports episodic memory. We also note that neuroimaging studies have documented neural differences between episodic future thinking and episodic counterfactual thinking, including differences in hippocampal responses. We next consider behavioral studies that have delineated both similarities and differences between the two kinds of episodic simulation. The evidence indicates that episodic future and counterfactual thinking are characterized by similarly reduced levels of specific detail compared with episodic memory, but that the effects of repeatedly imagining a possible experience have sharply contrasting effects on the perceived plausibility of those events during episodic future thinking versus episodic counterfactual thinking. Finally, we conclude by discussing the functional consequences of future and counterfactual simulations for decisions. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Episodic future thinking and episodic counterfactual thinking: Intersections between memory and decisions

    Science.gov (United States)

    Schacter, Daniel L.; Benoit, Roland G.; De Brigard, Felipe; Szpunar, Karl K.

    2014-01-01

    This article considers two recent lines of research concerned with the construction of imagined or simulated events that can provide insight into the relationship between memory and decision making. One line of research concerns episodic future thinking, which involves simulating episodes that might occur in one’s personal future, and the other concerns episodic counterfactual thinking, which involves simulating episodes that could have happened in one’s personal past. We first review neuroimaging studies that have examined the neural underpinnings of episodic future thinking and episodic counterfactual thinking. We argue that these studies have revealed that the two forms of episodic simulation engage a common core network including medial parietal, prefrontal, and temporal regions that also supports episodic memory. We also note that neuroimaging studies have documented neural differences between episodic future thinking and episodic counterfactual thinking, including differences in hippocampal responses. We next consider behavioral studies that have delineated both similarities and differences between the two kinds of episodic simulation. The evidence indicates that episodic future and counterfactual thinking are characterized by similarly reduced levels of specific detail compared with episodic memory, but that the effects of repeatedly imagining a possible experience have sharply contrasting effects on the perceived plausibility of those events during episodic future thinking versus episodic counterfactual thinking. Finally, we conclude by discussing the functional consequences of future and counterfactual simulations for decisions. PMID:24373942

  16. Ephemerality of discrete methane vents in lake sediments

    Science.gov (United States)

    Scandella, Benjamin P.; Pillsbury, Liam; Weber, Thomas; Ruppel, Carolyn D.; Hemond, Harold F.; Juanes, Ruben

    2016-01-01

    Methane is a potent greenhouse gas whose emission from sediments in inland waters and shallow oceans may both contribute to global warming and be exacerbated by it. The fraction of methane emitted by sediments that bypasses dissolution in the water column and reaches the atmosphere as bubbles depends on the mode and spatiotemporal characteristics of venting from the sediments. Earlier studies have concluded that hot spots—persistent, high-flux vents—dominate the regional ebullitive flux from submerged sediments. Here the spatial structure, persistence, and variability in the intensity of methane venting are analyzed using a high-resolution multibeam sonar record acquired at the bottom of a lake during multiple deployments over a 9 month period. We confirm that ebullition is strongly episodic, with distinct regimes of high flux and low flux largely controlled by changes in hydrostatic pressure. Our analysis shows that the spatial pattern of ebullition becomes homogeneous at the sonar's resolution over time scales of hours (for high-flux periods) or days (for low-flux periods), demonstrating that vents are ephemeral rather than persistent, and suggesting that long-term, lake-wide ebullition dynamics may be modeled without resolving the fine-scale spatial structure of venting.

  17. Is methane a new therapeutic gas?

    Directory of Open Access Journals (Sweden)

    Liu Wenwu

    2012-09-01

    Full Text Available Abstract Background Methane is an attractive fuel. Biologically, methanogens in the colon can use carbon dioxide and hydrogen to produce methane as a by-product. It was previously considered that methane is not utilized by humans. However, in a recent study, results demonstrated that methane could exert anti-inflammatory effects in a dog small intestinal ischemia-reperfusion model. Point of view Actually, the bioactivity of methane has been investigated in gastrointestinal diseases, but the exact mechanism underlying the anti-inflammatory effects is required to be further elucidated. Methane can cross the membrane and is easy to collect due to its abundance in natural gas. Although methane is flammable, saline rich in methane can be prepared for clinical use. These seem to be good news in application of methane as a therapeutic gas. Conclusion Several problems should be resolved before its wide application in clinical practice.

  18. Phase states of methane in fossil coals

    Science.gov (United States)

    Alexeev, A. D.; Vasylenko, T. A.; Ul'yanova, E. V.

    2004-06-01

    NMR measurements have revealed that methane can exist in coal samples in the state of solid solution rather than only adsorbed gas, opening new ways to prevention of gas dynamic accidents in underground coal mines and true estimation of coalbed methane resources. Understanding molecular structure of coal constituents and forms of methane occurrence in coal is the only way of extracting safely either coal or methane. We had studied nuclear magnetic resonance lines in various coals at room or low temperatures and have found that there exist three species of methane molecules differing in molecular mobility. Based on estimated diffusion parameters, these species were attributed to free methane, adsorbed methane, and solid solution of methane in crystalline coal substance. While first two phases are well known and can be analyzed by many different techniques, the last one hardly can be studied by methods other than NMR, resulting in inadequate estimations of methane resources.

  19. WATER LEVEL DRAWDOWN TRIGGERS SYSTEM-WIDE BUBBLE RELEASE FROM RESERVOIR SEDIMENTS

    Science.gov (United States)

    Reservoirs are an important anthropogenic source of methane and ebullition is a key pathway by which methane stored in reservoir sediments can be released to the atmosphere. Changes in hydrostatic pressure during periods of falling water levels can trigger bubbling events, sugge...

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  1. Impact of hydrology on methane flux patterns in a permafrost-affected floodplain in Northeast Siberia

    Science.gov (United States)

    Kwon, Min Jung; Beulig, Felix; Kuesel, Kirsten; Wildner, Marcus; Heimann, Martin; Zimov, Nikita; Zimov, Sergei; Goeckede, Mathias

    2015-04-01

    A large fraction of organic carbon stored in Arctic permafrost soil is at risk to be decomposed and released to the atmosphere under climate change. Thawing of ice-rich permafrost will re-structure the surface topography, with potentially significant effects on hydrology: water table depth (WTD) of depressed areas will increase, while that of the surrounding area will decrease. Changes in hydrology will trigger modifications in soil and vegetation, e.g. soil temperature, vegetation and microbial community structure. All of these secondary effects will alter carbon cycle processes, with the magnitude and even sign of the net effect yet unknown. The objective of this study is to investigate effects of drainage on methane fluxes in a floodplain of the Kolyma River near Cherskii, Northeast Siberia. The study site is separated into two areas, one that has been drained since 2004, and a nearby reference site. Methane flux was measured for ~16 weeks during summer and early winter of 2013, and summer of 2014. In addition, to separate different methane emission pathways, plant-mediated methane transport (through aerenchyma) as well as the proportion of ebullition were measured in 2014. Vegetation and microbial community structures were investigated and compared. After a decade of drainage history that lowered WTD by about 20cm in the drained area, Eriophorum (cotton grass) that previously dominated have to a large part been replaced by Carex (tussock-forming sedge) and shrub species. While WTD primarily influenced the methane flux rate, this vegetation change indirectly altered the flux as well in a way that sites with Eriophorum emitted more methane. Concerning the microbial community structure, the relative abundance of methanogen and ratio of methanotrophs to methanogens were well correlated with methane flux rates, implying that the methane flux is highly influenced by microorganisms. As a consequence of these changes, in the drained area less amount of methane was

  2. Environmental Controls Over Methane Flux from Ecosystems and the Potential for Feedbacks with Climatic Change

    Science.gov (United States)

    Torn, Margaret Susan

    temperature on emissions and uptake, and the fact that net emissions are the balance of production and consumption, predicts three times more change in global ecosystem emissions in response to a 10^ circC warming than does a model that ignores these two features and includes only net methane release. Therefore, the magnitude of the feedback generated between methane flux from ecosystems and climate is probably much greater than would be estimated by traditional methane-cycle models, which ignore these two features.

  3. Geologic seepage of methane and light alkanes in Los Angeles

    Science.gov (United States)

    Doezema, L. A.; Chang, K.; Baril, R.; Nwachuku, I.; Contreras, P.; Marquez, A.; Howard, D.

    2013-12-01

    Natural geologic seepage of methane from underground oil and natural gas reservoirs has been suggested to be an underreported part of the global methane budget. Other light alkanes are also given off in combination with the methane seepage, making it possible that geologic seepage is also a potentially significant global source of these light alkanes. This study reports C1-C5 findings from geologic seepage made in the Los Angeles region. Microseepage, invisible escape of gases, was measured primarily at Kenneth Hahn Regional Park, while macroseepage, the visible release of gases, was measured at the La Brea Tar Pits. Samples were collected using stainless steel canisters and flux chambers and were analyzed using gas chromatography with flame ionization detectors (GC-FID). Average microseepage flux rates of 0.95 μg m-2 h-1 for ethane and 0.51 μg m-2 h-1 were found for propane, while average macroseepage rates for methane, ethane, and propane were 664, 19.8, and 18.1 mg m-2 h-1 respectively. Relationships between microseepage flux rate and location of underground oil and natural deposit and earthquake fault lines are presented. Additionally, the relative importance of findings in context with global budgets and local air quality is discussed.

  4. Enhanced CO2 uptake at a shallow Arctic Ocean seep field overwhelms the positive warming potential of emitted methane

    Science.gov (United States)

    Pohlman, John W.; Greinert, Jens; Ruppel, Carolyn; Silyakova, Anna; Vielstädte, Lisa; Casso, Michael; Mienert, Jürgen; Bünz, Stefan

    2017-05-01

    Continued warming of the Arctic Ocean in coming decades is projected to trigger the release of teragrams (1 Tg = 106 tons) of methane from thawing subsea permafrost on shallow continental shelves and dissociation of methane hydrate on upper continental slopes. On the shallow shelves (biological uptake of carbon dioxide (CO2) has the potential to offset the positive warming potential of emitted methane, a process that has not received detailed consideration for these settings. Continuous sea-air gas flux data collected over a shallow ebullitive methane seep field on the Svalbard margin reveal atmospheric CO2 uptake rates (-33,300 ± 7,900 μmol m-2ṡd-1) twice that of surrounding waters and ˜1,900 times greater than the diffusive sea-air methane efflux (17.3 ± 4.8 μmol m-2ṡd-1). The negative radiative forcing expected from this CO2 uptake is up to 231 times greater than the positive radiative forcing from the methane emissions. Surface water characteristics (e.g., high dissolved oxygen, high pH, and enrichment of 13C in CO2) indicate that upwelling of cold, nutrient-rich water from near the seafloor accompanies methane emissions and stimulates CO2 consumption by photosynthesizing phytoplankton. These findings challenge the widely held perception that areas characterized by shallow-water methane seeps and/or strongly elevated sea-air methane flux always increase the global atmospheric greenhouse gas burden.

  5. Lidar Measurements of Methane and Applications for Aircraft and Spacecraft

    Science.gov (United States)

    Riris, Haris; Numata, Kenji; Abshire, James; Li, Steve; Wu, Stewart; Krainak, Michael; Sun, Xiaoli

    2010-05-01

    Atmospheric methane levels have remained relatively constant over the last decade around 1.78 parts per million (ppm) but observations since 2007 show that levels may be increasing. This trend may be caused by increased fossil fuel production, rice farming, livestock and landfills, but the underlying causes are quite uncertain. One hypothesis is that reservoirs of carbon trapped in the permafrost regions of northern Canada, Europe, and Siberia thaw as global temperatures rise and are releasing increasing amounts of methane. Another hypothesis points to increased production of methane by microbes as the permafrost warms. Currently most observations of greenhouse gases are limited to in-situ (surface and tower sites) and limited airborne in-situ measurements. Space column density measurements are starting to become available from the GOSAT mission. Although methane survives for a shorter time in the atmosphere than CO2, its impact on climate change per molecule is about 23 times than that of CO2. Accurate global observations of several greenhouse gases, including methane, are urgently needed in order to better understand climate change processes and to reduce the uncertainty in the carbon budget. Differential absorption lidar is a well-established technique to measure atmospheric gases, and methane has optical absorption bands near 1.65, 2.2, 3.4 and 7.8 μm. The near infrared overtones lines of CH4 near 1650 nm are relatively free of interference from other species. There are absorption lines near 1651 nm which are both temperature insensitive and have line strengths well suited for lidar measurements. We have developed a laser and demonstrated lidar measurements of CH4 using lines in this band. Our laser uses a narrow linewidth 1064 nm laser pulse passing through a nonlinear crystal. We generate the tunable laser signals near 1651 nm by using the optical parametric amplification (OPA) process. Inside the crystal the 1064 nm beam overlaps with an injection seed

  6. Formation of methane and nitrous oxide in plants

    Science.gov (United States)

    Keppler, Frank; Lenhart, Katharina

    2017-04-01

    and mosses, so called cryptogamic covers, were recently identified to release substantial amounts of nitrous oxide (Lenhart et al. 2015). In this presentation we will give a brief overview of recent observations of aerobic methane formation and nitrous oxide emissions from terrestrial vegetation. Furthermore, we will present new results from laboratory incubation experiments that provide further insights into the formation of methane and nitrous oxide from plants. References: Bruhn, D. et al.: Leaf surface wax is a source of plant methane formation under UV radiation and in the presence of oxygen. Plant Biology 16, 512-516, 2014. Chang, C. et al.: Nitrous Oxide Emission through Plants. Soil Science Society of America Journal 62, 35-38, 1998. Dean, J. V., Harper, J. E.: Nitric oxide and nitrous oxide production by soybean and winged bean during the in vivo nitrate reductase assay. Plant Physiology 82, 718-723, 1986. Keppler, F., Boros, M., Frankenberg, C., Lelieveld, J., McLeod, A., Pirttilä, A. M., Röckmann, T., Schnitzler, J.: Methane formation in aerobic environments, Environmental Chemistry, 6, 459-465, 2009. Lenhart, K. et al.: Nitrous oxide and methane emissions from cryptogamic covers. Global Change Biology 21, 3889-3900, 2015. Pihlatie, M., Ambus, P., Rinne, J., Pilegaard, K., Vesala, T.: Plant-mediated nitrous oxide emissions from beech (Fagus sylvatica) leaves. New Phytologist 168, 93-98, 2005. Wang, Z.-P., Chang, S. X., Chen, H., Han, X.-G.: Widespread non-microbial methane production by organic compounds and the impact of environmental stresses, Earth-Science Reviews, 127, 193-202, 2013.

  7. Lidar Measurements of Methane and Applications for Aircraft and Spacecraft

    Science.gov (United States)

    Riris, Haris; Numata, Kenji; Abshire, James; Li, Steve; Wu, Stewart; Krainak, Michael; Sun, Xiaoli

    2010-01-01

    Atmospheric methane levels have remained relatively constant over the last decade around 1.78 parts per million (ppm) but observations since 2007 show that levels may be increasing. This trend may be caused by increased fossil fuel production, rice farming, livestock and landfills, but the underlying causes are quite uncertain. One hypothesis is that reservoirs of carbon trapped in the permafrost regions of northern Canada, Europe, and Siberia thaw as global temperatures rise and are releasing increasing amounts of methane. Another hypothesis points to increased production of methane by microbes as the permafrost warms. Currently most observations of greenhouse gases are limited to in-situ (surface and tower sites) and limited airborne in-situ measurements. Space column density measurements are starting to become available from the GOSAT mission. Although methane survives for a shorter time in the atmosphere than CO2, its impact on climate change per molecule is about 23 times than that of CO2. Accurate global observations of several greenhouse gases, including methane, are urgently needed in order to better understand climate change processes and to reduce the uncertainty in the carbon budget. Differential absorption lidar is a well-established technique to measure atmospheric gases, and methane has optical absorption bands near 1.65,2.2,3.4 and 7.8 micron. The near infrared overtones lines of CH4 near 1650 nm are relatively free of interference from other species. There are absorption lines near 1651 nm which are both temperature insensitive and have line strengths well suited for lidar measurements. We have developed a laser and demonstrated lidar measurements of CH4 using lines in this band. Our laser uses a narrow linewidth 1064 nm laser pulse passing through a nonlinear crystal. We generate the tunable laser signals near 1651 nm by using the optical parametric amplification (OPA) process. Inside the crystal the 1064 nm beam overlaps with an injection seed

  8. Recovery of methane from anaerobic process effluent using poly-di-methyl-siloxane membrane contactors.

    Science.gov (United States)

    Cookney, J; Cartmell, E; Jefferson, B; McAdam, E J

    2012-01-01

    This paper demonstrates the potential for recovering dissolved methane from low temperature anaerobic processes treating domestic wastewater. In the absence of methane recovery, ca. 45% of the produced methane is released as a fugitive emission which results in a net carbon footprint of -0.47 kg CO(2e) m(-3). A poly-di-methyl-siloxane (PDMS) membrane contactor was applied to support sweep gas desorption of dissolved methane using nitrogen. The dense membrane structure controlled gaseous mass transfer thus recovery was maximised at low liquid velocities. At the lowest liquid velocity, V(L), of 0.0025 m s(-1), 72% of the dissolved methane was recovered. A vacuum was also trialled as an alternative to sweep-gas operation. At vacuum pressures below 30 mbar, reasonable methane recovery was observed at an intermediate V(L) of 0.0056 m s(-1). Results from this study demonstrate that dissolved methane recovery could increase net electrical production from low temperature anaerobic processes by ca. +0.043 kWh(e) m(-3) and reduce the net carbon footprint to +0.01 kg CO(2e) m(-3). However, further experimental work to optimise the gas-side hydrodynamics is required as well as validation of the long-term impacts of biofouling on process performance.

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

    Science.gov (United States)

    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.

  10. Methane concentration inside a submarine mud volcano examined through seismic velocity profiles

    Science.gov (United States)

    Kioka, Arata; Tsuji, Takeshi; Otsuka, Hironori; Ashi, Juichiro

    2017-04-01

    Mud volcanoes are considered to be among largest geological sources releasing hydrocarbon gases into the atmosphere. Numerous studies have revealed their origins and compositions from submarine mud volcanoes. A recent long-term observation at a submarine mud volcano sheds light on that larger volume of methane gas than expected is escaped from deep-water mud volcanoes, suggesting that the global methane flux from the seafloor is likely underestimated. Yet, estimates of the gas amount inside mud volcanoes have been still challenging, because of the difficulty of in-situ measurements. This study provides a new model to bridge methane amounts and seismic velocities in fluidized mud conduits of submarine mud volcanoes. This model is universally applicable and enables estimates of methane concentration in the mud conduits, using the seismic velocity profile derived from reflection/refraction seismic and/or downhole logging data. In this study, (1) we examine our modeled results through deep-drilling data obtained at mud volcanoes in the Olimpi mud field of the central Mediterranean Ridge accretionary margin, to evaluate the difference between in situ methane amounts and those calculated from our model, and (2) apply our model to the seismic velocity profile derived from seicmic data to estimate the methane amount inside the submarine mud volcano in the Nankai accretionary margin. Our scheme may provide an opportunity to re-estimate the total methane flux from submarine mud volcanoes.

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

    Science.gov (United States)

    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.

  12. Improved Mechanistic Understanding of Natural Gas Methane Emissions from Spatially Resolved Aircraft Measurements.

    Science.gov (United States)

    Schwietzke, Stefan; Pétron, Gabrielle; Conley, Stephen; Pickering, Cody; Mielke-Maday, Ingrid; Dlugokencky, Edward J; Tans, Pieter P; Vaughn, Tim; Bell, Clay; Zimmerle, Daniel; Wolter, Sonja; King, Clark W; White, Allen B; Coleman, Timothy; Bianco, Laura; Schnell, Russell C

    2017-06-20

    Divergence in recent oil and gas related methane emission estimates between aircraft studies (basin total for a midday window) and emissions inventories (annualized regional and national statistics) indicate the need for better understanding the experimental design, including temporal and spatial alignment and interpretation of results. Our aircraft-based methane emission estimates in a major U.S. shale gas basin resolved from west to east show (i) similar spatial distributions for 2 days, (ii) strong spatial correlations with reported NG production (R 2 = 0.75) and active gas well pad count (R 2 = 0.81), and (iii) 2× higher emissions in the western half (normalized by gas production) despite relatively homogeneous dry gas and well characteristics. Operator reported hourly activity data show that midday episodic emissions from manual liquid unloadings (a routine operation in this basin and elsewhere) could explain ∼1/3 of the total emissions detected midday by the aircraft and ∼2/3 of the west-east difference in emissions. The 22% emission difference between both days further emphasizes that episodic sources can substantially impact midday methane emissions and that aircraft may detect daily peak emissions rather than daily averages that are generally employed in emissions inventories. While the aircraft approach is valid, quantitative, and independent, our study sheds new light on the interpretation of previous basin scale aircraft studies, and provides an improved mechanistic understanding of oil and gas related methane emissions.

  13. Caregiver psychoeducation for first-episode psychosis.

    LENUS (Irish Health Repository)

    McWilliams, Stephen

    2010-01-01

    International best-practice guidelines for the management of first-episode psychosis have recommended the provision of psychoeducation for multifamily groups. While there is ample evidence of their efficacy in multiepisode psychosis, there is a paucity of evidence supporting this approach specifically for first-episode psychosis. We sought to determine whether a six-week caregiver psychoeducation programme geared specifically at first-episode psychosis improves caregiver knowledge and attitudes.

  14. Gas Hydrates and Perturbed Permafrost: Can Thermokarst Lakes Leak Hydrate-Derived Methane?

    Science.gov (United States)

    Ruppel, C.; Walter, K.; Pohlman, J.; Wooller, M.

    2008-12-01

    Thermokarst lakes are common features in the continuous permafrost of Siberia, the Alaskan North Slope, and the Canadian Arctic and have been intensely studied as the loci of rapid and substantial methane flux to the atmosphere. Previous numerical modeling has constrained the conditions under which deep thermokarst lakes can develop organic-rich thaw bulbs (talik) tens of meters thick, and seismic surveys have imaged thaw bulbs more than 75 m thick beneath some thermokarst lakes. Microbial processes active in talik organic material are likely the predominant source for thermokarst methane emissions, although coalbed methane and methane associated with conventional hydrocarbons may contribute in some geologic settings. Here we evaluate the possibility that another source--methane released from dissociating gas hydrate--could contribute to methane emissions from these lakes. Temperatures within and beneath thermokarst lakes are significantly warmer than those in surrounding permafrost, and these relatively warm conditions can persist to depths several times greater than the thickness of the thaw bulb. For a 95-m-thick thaw bulb and a geothermal gradient consistent with the regional top of gas hydrate stability at ~200 m depth, the warmer temperatures beneath a thermokarst lake could lead to destabilization of up to 75 m of gas hydrate. Arguably, the presence of gas hydrate near the top of the stability zone in permafrost regions has not yet been observed. Nonetheless, the potential dissociation of such relatively shallow gas hydrate and the widespread availability in terrestrial settings of high permeability conduits (e.g., faults, sandy strata) that could facilitate the migration of hydrate-derived methane to the surface render this an important topic for future investigation. The susceptibility of permafrost gas hydrate zones to thermal perturbations is in sharp contrast to the situation in conventional marine hydrate provinces. There, gas hydrate first dissociates

  15. Towards the identification of methanogenic archaeal groups as targets of methane mitigation in livestock animals.

    Directory of Open Access Journals (Sweden)

    Benoit eSt-Pierre

    2015-07-01

    Full Text Available In herbivores, enteric methane is a by-product from the digestion of plant biomass by mutualistic gastrointestinal tract (GIT microbial communities. Methane is a potent greenhouse gas that is not assimilated by the host and is released into the environment where it contributes to climate change. Since enteric methane is exclusively produced by methanogenic archaea, the investigation of mutualistic methanogen communities in the GIT of herbivores has been the subject of ongoing research by a number of research groups. In an effort to uncover trends that would facilitate the development of efficient methane mitigation strategies for livestock species, we have in this review summarized and compared currently available results from published studies on this subject. We also offer our perspectives on the importance of pursuing current research efforts on the sequencing of gut methanogen genomes, as well as investigating their cellular physiology and interactions with other GIT microorganisms.

  16. Increased methane emissions from deep osmotic and buoyant convection beneath submarine seeps as climate warms

    CERN Document Server

    Cardoso, Silvana S S

    2016-01-01

    High speeds have been measured at seep and mud-volcano sites expelling methane-rich fluids from the seabed. Thermal or solute-driven convection alone cannot explain such high velocities in low-permeability sediments. Here, we demonstrate that in addition to buoyancy, osmotic effects generated by the adsorption of methane onto the sediments can create large overpressures, capable of recirculating seawater from the seafloor to depth in the sediment layer, then expelling it upwards at rates of up to a few hundreds of metres per year. In the presence of global warming, such deep recirculation of seawater can accelerate the melting of methane hydrates at depth from timescales of millennia to just decades, and can drastically increase the rate of release of methane into the hydrosphere and perhaps the atmosphere.

  17. Impact of episodic thinking on altruism

    Science.gov (United States)

    Yi, Richard; Pickover, Alison; Stuppy-Sullivan, Allison M.; Baker, Sydney; Landes, Reid D.

    2016-01-01

    Episodic future thinking, which refers to the use of prospective imagery to concretely imagine oneself in future scenarios, has been shown to reduce delay discounting (enhance self-control). A parallel approach, in which prospective imagery is used to concretely imagine other’s scenarios, may similarly reduce social discounting (i.e., enhance altruism). In study 1, participants engaged in episodic thinking about the self or others, in a repeated-measures design, while completing a social discounting task. Reductions in social discounting were observed as a function of episodic thinking about others, though an interaction with order was also observed. Using an independent-measures design in study 2, the effect of episodic thinking about others was replicated. Study 3 addressed a limitation of studies 1 and 2, the possibility that simply thinking about others decreased social discounting. Capitalizing on Construal Level Theory, which specifies that social distance and time in the future are both dimensions of a common psychological distance, we hypothesized that episodic future thinking should also decrease social discounting. Participants engaged in episodic future thinking or episodic present thinking, in a repeated-measures design, while completing a social discounting task. The pattern of results was similar to study 1, providing support for the notion that episodic thinking about psychologically distant outcomes (for others or in the future) reduces social discounting. Application of similar episodic thinking approaches may enhance altruism. PMID:27821875

  18. Impact of episodic thinking on altruism.

    Science.gov (United States)

    Yi, Richard; Pickover, Alison; Stuppy-Sullivan, Allison M; Baker, Sydney; Landes, Reid D

    2016-07-01

    Episodic future thinking, which refers to the use of prospective imagery to concretely imagine oneself in future scenarios, has been shown to reduce delay discounting (enhance self-control). A parallel approach, in which prospective imagery is used to concretely imagine other's scenarios, may similarly reduce social discounting (i.e., enhance altruism). In study 1, participants engaged in episodic thinking about the self or others, in a repeated-measures design, while completing a social discounting task. Reductions in social discounting were observed as a function of episodic thinking about others, though an interaction with order was also observed. Using an independent-measures design in study 2, the effect of episodic thinking about others was replicated. Study 3 addressed a limitation of studies 1 and 2, the possibility that simply thinking about others decreased social discounting. Capitalizing on Construal Level Theory, which specifies that social distance and time in the future are both dimensions of a common psychological distance, we hypothesized that episodic future thinking should also decrease social discounting. Participants engaged in episodic future thinking or episodic present thinking, in a repeated-measures design, while completing a social discounting task. The pattern of results was similar to study 1, providing support for the notion that episodic thinking about psychologically distant outcomes (for others or in the future) reduces social discounting. Application of similar episodic thinking approaches may enhance altruism.

  19. Effects of methane outgassing on the Black Sea atmosphere

    Directory of Open Access Journals (Sweden)

    K. Kourtidis

    2006-01-01

    Full Text Available Methane in air and seawater was measured in the Eastern Black Sea during the 10–18 December 1999 BIGBLACK project cruise. The measurements allowed for the calculation of supersaturation ratios and methane fluxes across the air-sea interface. CH4 mixing ratios in air were generally in the 1.8–2.0 ppmv range, while surface (4 m depth seawater concentrations varied from 4 to 93 ppmv. Above active seep areas, the water was supersaturated to around 500% with respect to the overlying atmosphere. Accordingly, flux densities varied greatly and were up to 3300 umol m−2 day−1. In the Sevastopol harbour, supersaturations up to around 3000%, similar to those at the Danube Delta, were observed, while in the Istanbul harbour supersaturations could not be determined because the very high values of water concentrations led to detector saturation. Simple modelling shows that the observed fluxes do not have any substantial impact on the methane content of the Black Sea atmosphere, as they would only raise its concentrations by less than 50 ppt. On the other hand, calculations performed as part of the CRIMEA project show that mud volcano eruptions could episodically raise the methane concentrations well above their regional background for several tens of kilometres downwind. These calculations, which also apply to mud volcano eruptions elsewhere on the globe, indicate that the spatial extend and the magnitude of the atmospheric perturbation is such that its observation might lie within the capabilities of existing satellite instrumentation such as SCIAMACHY on ENVISAT.

  20. Methane as a climate gas

    Energy Technology Data Exchange (ETDEWEB)

    Karlsdottir, S.

    1996-03-01

    This paper was read at the workshop ``The Norwegian Climate and Ozone Research Programme`` held on 11-12 March 1996. Methane is a key component in the atmosphere where its concentration has increased rapidly since pre-industrial time. About 2/3 of it is caused by human activities. Changes in methane will affect the concentrations of other gases, and a model is a very important tool to study sensitivity due to changes in concentration of gases. The author used a three-dimensional global chemistry transport model to study the effect of changes in methane concentration on other trace gases. The model includes natural and anthropogenic emissions of NOx, CO, CH{sub 4} and non-methane hydrocarbons. Wet and dry deposition are also included. The chemical scheme in the model includes 49 compounds, 101 reactions, and 16 photolytic reactions. The trace gas concentrations are calculated every 30 min, using a quasi steady state approximation. Model calculations of three cases are reported and compared. Enhanced methane concentration will have strongest effect in remote regions. In polluted areas local chemistry will have remarked effect. The feedback was always positive. Average atmospheric lifetime calculated in the model was 7.6 years, which agrees with recent estimates based on observations. 8 refs.

  1. Methane from landfills in Sweden. Final report; Metan fraan avfallsupplag i Sverige. Slutrapport

    Energy Technology Data Exchange (ETDEWEB)

    Samuelsson, Jerker [Chalmers Univ. of Technology, Goeteborg (Sweden); Galle, Bo; Boerjesson, Gunnar [Linkoeping Univ. (Sweden). Dept. of Water and Environmental Studies

    2006-01-15

    Three years of measurements has been conducted at seven Swedish landfills, quantifying methane emission, methane oxidation and methane production. The measurements reveal a large span between the sites in terms of gas recovery efficiency, 29-78% during normal operation. The fraction of the totally produced methane that is eventually leaking out to the atmosphere, was found to vary between 21-68%. Regarding methane oxidation, the study shows that of the methane going from the landfill interior towards the atmosphere, 6-43% is oxidised to CO{sub 2} in the different landfill cover soils. The highest methane oxidation was found in closed landfills during summertime, and the lowest at active landfills during wintertime, due to the strong temperature dependence of the oxidation. The equipment developed for methane emission measurements is based on time resolved concentration measurements with FTIR spectroscopy in combination with tracer gas releases from the surface of the landfill. The method has proven to be able to state the methane emission from the landfills with high accuracy, {+-}18% of the emission estimate (95% confidence interval). This is in line with what has been achieved in the literature for fugitive emission sources. The system has also proven to be useful for on site leak search. The precision for the methane production measurement was demonstrated to be high, down to {+-}4.2%. This enables trend studies and verification of improvement measures taken at the landfill sites. In terms of absolute accuracy for the production estimate, a 95%-confidence interval of down to (-6.0%, +6.2%) has been achieved. At times of strong methane oxidation the uncertainties increase, particularly if the emission is high. The gas production at the landfill site is therefore preferably measured during autumn-winter-spring when the temperature and the methane oxidation are low. The methane oxidation has been measured by carbon isotope technique, utilising the enrichment in

  2. Methane fermentation of regionally accrued wet biomass

    OpenAIRE

    浅野, 憲哉

    2017-01-01

    The methane fermentation of Japanese mushroom ligneous bed waste was conducted for estimate steam explosion as pretreatment. Methane yield was improved to 50-75% by pretreatment of mushroom bed with severity factor 2.1-3.2

  3. A Possible Sink for Methane on Mars

    NARCIS (Netherlands)

    Nørnberg, P.; Jensen, S. J. K.; Skibsted, J.; Jakobsen, H. J.; ten Kate, I. L.; Gunnlaugsson, H. P.; Merrison, J. P.; Finster, K.; Bak, E.; Iversen, J. J.; Kondrup, J. C.

    2014-01-01

    Mechanical simulated wind activation of mineral surfaces act as a trap for Methane through formation of covalent Si-C bonds stable up to temperatures above 250 C. This mechanism is proposed as a Methane sink on Mars.

  4. Electricity from methane by reversing methanogenesis

    Science.gov (United States)

    McAnulty, Michael J.; G. Poosarla, Venkata; Kim, Kyoung-Yeol; Jasso-Chávez, Ricardo; Logan, Bruce E.; Wood, Thomas K.

    2017-05-01

    Given our vast methane reserves and the difficulty in transporting methane without substantial leaks, the conversion of methane directly into electricity would be beneficial. Microbial fuel cells harness electrical power from a wide variety of substrates through biological means; however, the greenhouse gas methane has not been used with much success previously as a substrate in microbial fuel cells to generate electrical current. Here we construct a synthetic consortium consisting of: (i) an engineered archaeal strain to produce methyl-coenzyme M reductase from unculturable anaerobic methanotrophs for capturing methane and secreting acetate; (ii) micro-organisms from methane-acclimated sludge (including Paracoccus denitrificans) to facilitate electron transfer by providing electron shuttles (confirmed by replacing the sludge with humic acids), and (iii) Geobacter sulfurreducens to produce electrons from acetate, to create a microbial fuel cell that converts methane directly into significant electrical current. Notably, this methane microbial fuel cell operates at high Coulombic efficiency.

  5. METHANE INCORPORATION BY PROCARYOTIC PHOTOSYNTHETICMICROORGANISMS

    Energy Technology Data Exchange (ETDEWEB)

    Norton, Charles J.; Kirk, Martha; Calvin, Melvin

    1970-08-01

    The procaryotic photosynthetic microorganisms Anacystis nidulans, Nostoc and Rhodospirillum rubrum have cell walls and membranes that are resistant to the solution of methane in their lipid components and intracellular fluids. But Anacystis nidulans, possesses a limited bioxidant system, a portion of which may be extracellularly secreted, which rapidly oxidizes methane to carbon dioxide. Small C{sup 14} activities derived from CH{sub 4} in excess of experimental error are detected in all the major biochemical fractions of Anacystis nidulans and Nostoc. This limited capacity to metabolize methane appears to be a vestigial potentiality that originated over two billion years ago in the early evolution of photosynthetic bacteria and blue-green algae.

  6. Vertical distribution of Arctic methane

    Science.gov (United States)

    Tukiainen, Simo; Karppinen, Tomi; Hakkarainen, Janne; Kivi, Rigel; Heikkinen, Pauli; Tamminen, Johanna

    2017-04-01

    In this study we show the vertical distribution of atmospheric methane (CH4) measured in Sodankylä, Northern Finland. The CH4 profiles are retrieved from the direct Sun FTS measurements using the dimension reduction retrieval method. In the retrieval method, we have a few degrees of freedom about the profile shape. The data set covers years 2010-2016 (from February to November) and altitudes 0-40 km. The retrieved FTS profiles are validated against ACE satellite measurements and AirCore balloon measurements. The total columns derived from the FTS profiles are compared to the official TCCON XCH4 data. A vertically resolved methane data set can be used, e.g., to study stratospheric methane during the polar vortex.

  7. Consumption of atmospheric methane by tundra soils

    OpenAIRE

    Whalen, SC; Reeburgh, WS

    1990-01-01

    EMISSION of methane from tundra soil contributes about 10% of the global atmospheric methane budget 1 . Moreover, tundra soils contain 15% of global soil carbon 2 , so the response of this large carbon reservoir to projected global warming 3,4 could be important. Coupled biological models 3-6 predict that a warmer climate will increase methane emission through increased rates of methanogenesis. Microbial oxidation of methane is, however, a possible control on emissions that has previously b...

  8. Handbook methane potential; Handbok metanpotential

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, My (AnoxKaldnes AB (Sweden)); Schnurer, Anna (Swedish Univ. of Agricultural Sciences, Uppsala (Sweden))

    2011-07-15

    Before using a organic material for biogas production it is essential to evaluate the methane production potential. The methane potential is one important tool possible to use during planning of new plants but also when new materials are considered for already running biogas plants. The chemical composition of different organic material varies extensively and this will have an impact on both the degradability and the methane potential. Information about the methane potential of a specific material can sometimes be found in the literature or can be calculated after a chemical/ physical or biological characterization. Here, the BMP test (Biochemical Methane Potential) is a commonly used method. Today the BMP test is a commonly used method to determine the methane potential. Many national and international research groups, consultants as well as personal at biogas plants are using this method and there is a lot of data available in the literature from such tests. In addition there are several protocols giving guidelines on how to execute a BMP-test. The BMP-test is performed in many different ways, not always under optimized conditions, and there is a lack of information on how to interpret the obtained data. This report summarizes knowledge from the literature and the experience from a Swedish referee group, consisting of persons being active performers of BMP-tests. The report does not include a standardized protocol as the procedure can be performed in different ways depending on available equipment and on the type of material to be tested. Instead the report discusses different factors of great importance for a successful test giving reliable results. The report also summarizes important information concerning the interpretation and how to present results in order to allow comparison of data from different test.

  9. Episodic plate tectonics on Venus

    Science.gov (United States)

    Turcotte, Donald

    1992-01-01

    Studies of impact craters on Venus from the Magellan images have placed important constraints on surface volcanism. Some 840 impact craters have been identified with diameters ranging from 2 to 280 km. Correlations of this impact flux with craters on the Moon, Earth, and Mars indicate a mean surface age of 0.5 +/- 0.3 Ga. Another important observation is that 52 percent of the craters are slightly fractured and only 4.5 percent are embayed by lava flows. These observations led researchers to hypothesize that a pervasive resurfacing event occurred about 500 m.y. ago and that relatively little surface volcanism has occurred since. Other researchers have pointed out that a global resurfacing event that ceased about 500 MYBP is consistent with the results given by a recent study. These authors carried out a series of numerical calculations of mantle convection in Venus yielding thermal evolution results. Their model considered crustal recycling and gave rapid planetary cooling. They, in fact, suggested that prior to 500 MYBP plate tectonics was active in Venus and since 500 MYBP the lithosphere has stabilized and only hot-spot volcanism has reached the surface. We propose an alternative hypothesis for the inferred cessation of surface volcanism on Venus. We hypothesize that plate tectonics on Venus is episodic. Periods of rapid plate tectonics result in high rates of subduction that cool the interior resulting in more sluggish mantle convection.

  10. Temporal constraints on hydrate-controlled methane seepage off Svalbard.

    Science.gov (United States)

    Berndt, C; Feseker, T; Treude, T; Krastel, S; Liebetrau, V; Niemann, H; Bertics, V J; Dumke, I; Dünnbier, K; Ferré, B; Graves, C; Gross, F; Hissmann, K; Hühnerbach, V; Krause, S; Lieser, K; Schauer, J; Steinle, L

    2014-01-17

    Methane hydrate is an icelike substance that is stable at high pressure and low temperature in continental margin sediments. Since the discovery of a large number of gas flares at the landward termination of the gas hydrate stability zone off Svalbard, there has been concern that warming bottom waters have started to dissociate large amounts of gas hydrate and that the resulting methane release may possibly accelerate global warming. Here, we corroborate that hydrates play a role in the observed seepage of gas, but we present evidence that seepage off Svalbard has been ongoing for at least 3000 years and that seasonal fluctuations of 1° to 2°C in the bottom-water temperature cause periodic gas hydrate formation and dissociation, which focus seepage at the observed sites.

  11. Methane emissions from MBT landfills.

    Science.gov (United States)

    Heyer, K-U; Hupe, K; Stegmann, R

    2013-09-01

    Within the scope of an investigation for the German Federal Environment Agency ("Umweltbundesamt"), the basics for the estimation of the methane emissions from the landfilling of mechanically and biologically treated waste (MBT) were developed. For this purpose, topical research including monitoring results regarding the gas balance at MBT landfills was evaluated. For waste treated to the required German standards, a methane formation potential of approximately 18-24 m(3)CH(4)/t of total dry solids may be expected. Monitoring results from MBT landfills show that a three-phase model with differentiated half-lives describes the degradation kinetics in the best way. This is due to the fact that during the first years of disposal, the anaerobic degradation processes still proceed relatively intensively. In addition in the long term (decades), a residual gas production at a low level is still to be expected. Most of the soils used in recultivation layer systems at German landfills show a relatively high methane oxidation capacity up to 5 l CH(4)/(m(2)h). However, measurements at MBT disposal sites indicate that the majority of the landfill gas (in particular at non-covered areas), leaves the landfill body via preferred gas emission zones (hot spots) without significant methane oxidation. Therefore, rather low methane oxidation factors are recommended for open and temporarily covered MBT landfills. Higher methane oxidation rates can be achieved when the soil/recultivation layer is adequately designed and operated. Based on the elaborated default values, the First Order Decay (FOD) model of the IPCC Guidelines for National Greenhouse Gas Inventories, 2006, was used to estimate the methane emissions from MBT landfills. Due to the calculation made by the authors emissions in the range of 60,000-135,000 t CO(2-eq.)/a for all German MBT landfills can be expected. This wide range shows the uncertainties when the here used procedure and the limited available data are applied

  12. 77 FR 40032 - Methane Hydrate Advisory Committee

    Science.gov (United States)

    2012-07-06

    ... Methane Hydrate Advisory Committee AGENCY: Office of Fossil Energy, Department of Energy. ACTION: Notice of open meeting. SUMMARY: This notice announces a meeting of the Methane Hydrate Advisory Committee.... SUPPLEMENTARY INFORMATION: Purpose of the Committee: The purpose of the Methane Hydrate Advisory Committee is to...

  13. Nitrogen-fixing methane-utilizing bacteria

    NARCIS (Netherlands)

    Bont, de J.A.M.

    1976-01-01

    Methane occurs abundantly in nature. In the presence of oxygen this gas may be metabolized by bacteria that are able to use it as carbon and energy source. Several types of bacteria involved in the oxidation of methane have been described in literature. Methane-utilizing bacteria have in

  14. Methane emission reduction: an application of FUND

    NARCIS (Netherlands)

    Tol, R.S.J.; Heintz, R.J.; Lammers, P.E.M.

    2003-01-01

    Methane is, after carbon dioxide, the most important anthropogenic greenhouse gas. Governments plan to abate methane emissions. A crude set of estimates of reduction costs is included in FUND, an integrated assessment model of climate change. In a cost-benefit analysis, methane emission reduction is

  15. 46 CFR 154.703 - Methane (LNG).

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Methane (LNG). 154.703 Section 154.703 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR... and Temperature Control § 154.703 Methane (LNG). Unless a cargo tank carrying methane (LNG) can...

  16. Gas releases from salt

    Energy Technology Data Exchange (ETDEWEB)

    Ehgartner, B.; Neal, J.; Hinkebein, T.

    1998-06-01

    The occurrence of gas in salt mines and caverns has presented some serious problems to facility operators. Salt mines have long experienced sudden, usually unexpected expulsions of gas and salt from a production face, commonly known as outbursts. Outbursts can release over one million cubic feet of methane and fractured salt, and are responsible for the lives of numerous miners and explosions. Equipment, production time, and even entire mines have been lost due to outbursts. An outburst creates a cornucopian shaped hole that can reach heights of several hundred feet. The potential occurrence of outbursts must be factored into mine design and mining methods. In caverns, the occurrence of outbursts and steady infiltration of gas into stored product can effect the quality of the product, particularly over the long-term, and in some cases renders the product unusable as is or difficult to transport. Gas has also been known to collect in the roof traps of caverns resulting in safety and operational concerns. The intent of this paper is to summarize the existing knowledge on gas releases from salt. The compiled information can provide a better understanding of the phenomena and gain insight into the causative mechanisms that, once established, can help mitigate the variety of problems associated with gas releases from salt. Outbursts, as documented in mines, are discussed first. This is followed by a discussion of the relatively slow gas infiltration into stored crude oil, as observed and modeled in the caverns of the US Strategic Petroleum Reserve. A model that predicts outburst pressure kicks in caverns is also discussed.

  17. Music-related reward responses predict episodic memory performance.

    Science.gov (United States)

    Ferreri, Laura; Rodriguez-Fornells, Antoni

    2017-12-01

    Music represents a special type of reward involving the recruitment of the mesolimbic dopaminergic system. According to recent theories on episodic memory formation, as dopamine strengthens the synaptic potentiation produced by learning, stimuli triggering dopamine release could result in long-term memory improvements. Here, we behaviourally test whether music-related reward responses could modulate episodic memory performance. Thirty participants rated (in terms of arousal, familiarity, emotional valence, and reward) and encoded unfamiliar classical music excerpts. Twenty-four hours later, their episodic memory was tested (old/new recognition and remember/know paradigm). Results revealed an influence of music-related reward responses on memory: excerpts rated as more rewarding were significantly better recognized and remembered. Furthermore, inter-individual differences in the ability to experience musical reward, measured through the Barcelona Music Reward Questionnaire, positively predicted memory performance. Taken together, these findings shed new light on the relationship between music, reward and memory, showing for the first time that music-driven reward responses are directly implicated in higher cognitive functions and can account for individual differences in memory performance.

  18. Methane dynamics in different boreal lake types

    Directory of Open Access Journals (Sweden)

    S. Juutinen

    2009-02-01

    Full Text Available This study explores the variability in concentrations of dissolved CH4 and annual flux estimates in the pelagic zone in a statistically defined sample of 207 lakes in Finland. The lakes were situated in the boreal zone, in an area where the mean annual air temperature ranges from −2.8 to 5.9°C. We examined how lake CH4 dynamics related to regional lake types assessed according to the EU water framework directive. Ten lake types were defined on the basis of water chemistry, color, and size. Lakes were sampled for dissolved CH4 concentrations four times per year, at four different depths at the deepest point of each lake. We found that CH4 concentrations and fluxes to the atmosphere tended to be high in nutrient rich calcareous lakes, and that the shallow lakes had the greatest surface water concentrations. Methane concentration in the hypolimnion was related to oxygen and nutrient concentrations, and to lake depth or lake area. The surface water CH4 concentration was related to the depth or area of lake. Methane concentration close to the bottom can be viewed as proxy of lake status in terms of frequency of anoxia and nutrient levels. The mean pelagic CH4 release from randomly selected lakes was 49 mmol m−2 a−1. The sum CH4 flux (storage and diffusion correlated with lake depth, area and nutrient content, and CH4 release was greatest from the shallow nutrient rich and humic lakes. Our results support earlier lake studies regarding the regulating factors and also the magnitude of global emission estimate. These results propose that in boreal region small lakes have higher CH4 fluxes per unit area than larger lakes, and that the small lakes have a disproportionate significance regarding to the CH4 release.

  19. Anthropogenic Methane Emissions in California's San Joaquin Valley: Characterizing Large Point Source Emitters

    Science.gov (United States)

    Hopkins, F. M.; Duren, R. M.; Miller, C. E.; Aubrey, A. D.; Falk, M.; Holland, L.; Hook, S. J.; Hulley, G. C.; Johnson, W. R.; Kuai, L.; Kuwayama, T.; Lin, J. C.; Thorpe, A. K.; Worden, J. R.; Lauvaux, T.; Jeong, S.; Fischer, M. L.

    2015-12-01

    Methane is an important atmospheric pollutant that contributes to global warming and tropospheric ozone production. Methane mitigation could reduce near term climate change and improve air quality, but is hindered by a lack of knowledge of anthropogenic methane sources. Recent work has shown that methane emissions are not evenly distributed in space, or across emission sources, suggesting that a large fraction of anthropogenic methane comes from a few "super-emitters." We studied the distribution of super-emitters in California's southern San Joaquin Valley, where elevated levels of atmospheric CH4 have also been observed from space. Here, we define super-emitters as methane plumes that could be reliably detected (i.e., plume observed more than once in the same location) under varying wind conditions by airborne thermal infrared remote sensing. The detection limit for this technique was determined to be 4.5 kg CH4 h-1 by a controlled release experiment, corresponding to column methane enhancement at the point of emissions greater than 20% above local background levels. We surveyed a major oil production field, and an area with a high concentration of large dairies using a variety of airborne and ground-based measurements. Repeated airborne surveys (n=4) with the Hyperspectral Thermal Emission Spectrometer revealed 28 persistent methane plumes emanating from oil field infrastructure, including tanks, wells, and processing facilities. The likelihood that a given source type was a super-emitter varied from roughly 1/3 for processing facilities to 1/3000 for oil wells. 11 persistent plumes were detected in the dairy area, and all were associated with wet manure management. The majority (11/14) of manure lagoons in the study area were super-emitters. Comparing to a California methane emissions inventory for the surveyed areas, we estimate that super-emitters comprise a minimum of 9% of inventoried dairy emissions, and 13% of inventoried oil emissions in this region.

  20. A synthesis of methane emissions from 71 northern, temperate, and subtropical wetlands

    Science.gov (United States)

    Turetsky, Merritt R.; Kotowska, Agnieszka; Bubier, Jill; Dise, Nancy B.; Crill, Patrick; Hornibrook, Ed R.C.; Minkkinen, Kari; Moore, Tim R.; Myers-Smith, Isla H.; Nykanen, Hannu; Olefeldt, David; Rinne, Janne; Saarnio, Sanna; Shurpali, Narasinha; Tuittila, Eeva-Stiina; Waddington, J. Michael; White, Jeffrey R.; Wickland, Kimberly P.; Wilmking, Martin

    2014-01-01

    Wetlands are the largest natural source of atmospheric methane. Here, we assess controls on methane flux using a database of approximately 19 000 instantaneous measurements from 71 wetland sites located across subtropical, temperate, and northern high latitude regions. Our analyses confirm general controls on wetland methane emissions from soil temperature, water table, and vegetation, but also show that these relationships are modified depending on wetland type (bog, fen, or swamp), region (subarctic to temperate), and disturbance. Fen methane flux was more sensitive to vegetation and less sensitive to temperature than bog or swamp fluxes. The optimal water table for methane flux was consistently below the peat surface in bogs, close to the peat surface in poor fens, and above the peat surface in rich fens. However, the largest flux in bogs occurred when dry 30-day averaged antecedent conditions were followed by wet conditions, while in fens and swamps, the largest flux occurred when both 30-day averaged antecedent and current conditions were wet. Drained wetlands exhibited distinct characteristics, e.g. the absence of large flux following wet and warm conditions, suggesting that the same functional relationships between methane flux and environmental conditions cannot be used across pristine and disturbed wetlands. Together, our results suggest that water table and temperature are dominant controls on methane flux in pristine bogs and swamps, while other processes, such as vascular transport in pristine fens, have the potential to partially override the effect of these controls in other wetland types. Because wetland types vary in methane emissions and have distinct controls, these ecosystems need to be considered separately to yield reliable estimates of global wetland methane release.

  1. Methane production and energy partition in sheep fed timothy silage- or hay-based diets

    Directory of Open Access Journals (Sweden)

    B Santoso

    2007-03-01

    Full Text Available Methane is produced as a result of anaerobic fermentation of the soluble and structural carbohydrates by methanogens in the rumen of ruminant animals. Removal of methane from rumen represents a loss of approximately 7.22% of gross energy intake. Four ruminally fistulated Cheviot wethers were used in a crossover design to determine methane production and energy partition in sheep fed timothy silage- or hay-based diets. The experimental diets consisted of either timothy silage or timothy hay and a commercial concentrate (85:15, on DM basis. Variables measured were nutrients digestibility, energy balance and methane production. Apparent digestibilities of DM, OM, CP, NDF, ADF, cellulose and hemicellulose were significantly higher (P<0.05 on sheep fed silage-based diet than those fed hay-based diet. Sheep fed silage-based diet had greater (P<0.01 urinary energy loss, methane and heat production, but lower (P<0.05 fecal energy loss. Methane production, either expressed as g kg-1 dry matter intake or g day-1 was markedly lower (P<0.05 in hay-based diet as compared to silage-based diet. There was a strong relationship between methane production (g day-1 and NDF digested (g day-1 (R2 = 88.4%, P<0.001. Methane production expressed as g kg-1 NDF digested in silage-based diet was higher (P<0.05 than in hay-based diet (66.44 vs 62.70. These results indicate that methane release by sheep increased with increasing NDF digested.

  2. Massive blow-out craters formed by hydrate-controlled methane expulsion from the Arctic seafloor.

    Science.gov (United States)

    Andreassen, K; Hubbard, A; Winsborrow, M; Patton, H; Vadakkepuliyambatta, S; Plaza-Faverola, A; Gudlaugsson, E; Serov, P; Deryabin, A; Mattingsdal, R; Mienert, J; Bünz, S

    2017-06-02

    Widespread methane release from thawing Arctic gas hydrates is a major concern, yet the processes, sources, and fluxes involved remain unconstrained. We present geophysical data documenting a cluster of kilometer-wide craters and mounds from the Barents Sea floor associated with large-scale methane expulsion. Combined with ice sheet/gas hydrate modeling, our results indicate that during glaciation, natural gas migrated from underlying hydrocarbon reservoirs and was sequestered extensively as subglacial gas hydrates. Upon ice sheet retreat, methane from this hydrate reservoir concentrated in massive mounds before being abruptly released to form craters. We propose that these processes were likely widespread across past glaciated petroleum provinces and that they also provide an analog for the potential future destabilization of subglacial gas hydrate reservoirs beneath contemporary ice sheets. Copyright © 2017, American Association for the Advancement of Science.

  3. Massive blow-out craters formed by hydrate-controlled methane expulsion from the Arctic seafloor

    Science.gov (United States)

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

    2017-06-01

    Widespread methane release from thawing Arctic gas hydrates is a major concern, yet the processes, sources, and fluxes involved remain unconstrained. We present geophysical data documenting a cluster of kilometer-wide craters and mounds from the Barents Sea floor associated with large-scale methane expulsion. Combined with ice sheet/gas hydrate modeling, our results indicate that during glaciation, natural gas migrated from underlying hydrocarbon reservoirs and was sequestered extensively as subglacial gas hydrates. Upon ice sheet retreat, methane from this hydrate reservoir concentrated in massive mounds before being abruptly released to form craters. We propose that these processes were likely widespread across past glaciated petroleum provinces and that they also provide an analog for the potential future destabilization of subglacial gas hydrate reservoirs beneath contemporary ice sheets.

  4. Episodic accretion on to strongly magnetic stars

    NARCIS (Netherlands)

    D'Angelo, C.R.; Spruit, H.C.

    2010-01-01

    Some accreting neutron stars and young stars show unexplained episodic flares in the form of quasi-periodic oscillations or recurrent outbursts. In a series of two papers, we present new work on an instability that can lead to episodic outbursts when the accretion disc is truncated by the star's

  5. Intrusions in Episodic Memory: Reconsolidation or Interference?

    Science.gov (United States)

    Klingmüller, Angela; Caplan, Jeremy B.; Sommer, Tobias

    2017-01-01

    It would be profoundly important if reconsolidation research in animals and other memory domains generalized to human episodic memory. A 3-d-list-discrimination procedure, based on free recall of objects, with a contextual reminder cue (the testing room), has been thought to demonstrate reconsolidation of human episodic memory (as noted in a…

  6. Episodic memory and the witness trump card.

    Science.gov (United States)

    Henry, Jeremy; Craver, Carl

    2018-01-01

    We accept Mahr & Csibra's (M&C's) causal claim that episodic memory provides humans with the means for evaluating the veracity of reports about non-occurrent events. We reject their evolutionary argument that this is the proper function of episodic memory. We explore three intriguing implications of the causal claim, for cognitive neuropsychology, comparative psychology, and philosophy.

  7. Tracking the Construction of Episodic Future Thoughts

    Science.gov (United States)

    D'Argembeau, Arnaud; Mathy, Arnaud

    2011-01-01

    The ability to mentally simulate possible futures ("episodic future thinking") is of fundamental importance for various aspects of human cognition and behavior, but precisely how humans construct mental representations of future events is still essentially unknown. We suggest that episodic future thoughts consist of transitory patterns…

  8. Enhanced CO2 uptake at a shallow Arctic Ocean seep field overwhelms the positive warming potential of emitted methane

    Science.gov (United States)

    Greinert, Jens; Silyakova, Anna; Vielstädte, Lisa; Casso, Michael; Mienert, Jürgen; Bünz, Stefan

    2017-01-01

    Continued warming of the Arctic Ocean in coming decades is projected to trigger the release of teragrams (1 Tg = 106 tons) of methane from thawing subsea permafrost on shallow continental shelves and dissociation of methane hydrate on upper continental slopes. On the shallow shelves (methane released from the seafloor may reach the atmosphere and potentially amplify global warming. On the other hand, biological uptake of carbon dioxide (CO2) has the potential to offset the positive warming potential of emitted methane, a process that has not received detailed consideration for these settings. Continuous sea−air gas flux data collected over a shallow ebullitive methane seep field on the Svalbard margin reveal atmospheric CO2 uptake rates (−33,300 ± 7,900 μmol m−2⋅d−1) twice that of surrounding waters and ∼1,900 times greater than the diffusive sea−air methane efflux (17.3 ± 4.8 μmol m−2⋅d−1). The negative radiative forcing expected from this CO2 uptake is up to 231 times greater than the positive radiative forcing from the methane emissions. Surface water characteristics (e.g., high dissolved oxygen, high pH, and enrichment of 13C in CO2) indicate that upwelling of cold, nutrient-rich water from near the seafloor accompanies methane emissions and stimulates CO2 consumption by photosynthesizing phytoplankton. These findings challenge the widely held perception that areas characterized by shallow-water methane seeps and/or strongly elevated sea−air methane flux always increase the global atmospheric greenhouse gas burden. PMID:28484018

  9. Divergent thinking and constructing episodic simulations.

    Science.gov (United States)

    Addis, Donna Rose; Pan, Ling; Musicaro, Regina; Schacter, Daniel L

    2016-01-01

    Divergent thinking likely plays an important role in simulating autobiographical events. We investigated whether divergent thinking is differentially associated with the ability to construct detailed imagined future and imagined past events as opposed to recalling past events. We also examined whether age differences in divergent thinking might underlie the reduced episodic detail generated by older adults. The richness of episodic detail comprising autobiographical events in young and older adults was assessed using the Autobiographical Interview. Divergent thinking abilities were measured using the Alternative Uses Task. Divergent thinking was significantly associated with the amount of episodic detail for imagined future events. Moreover, while age was significantly associated with imagined episodic detail, this effect was strongly related to age-related changes in episodic retrieval rather than divergent thinking.

  10. Formation and Dissociation of Methane Hydrates from Seawater in Consolidated Sand: Mimicking Methane Hydrate Dynamics beneath the Seafloor

    Directory of Open Access Journals (Sweden)

    Prasad B. Kerkar

    2013-11-01

    Full Text Available Methane hydrate formation and dissociation kinetics were investigated in seawater-saturated consolidated Ottawa sand-pack under sub-seafloor conditions to study the influence of effective pressure on formation and dissociation kinetics. To simulate a sub-seafloor environment, the pore-pressure was varied relative to confining pressure in successive experiments. Hydrate formation was achieved by methane charging followed by sediment cooling. The formation of hydrates was delayed with increasing degree of consolidation. Hydrate dissociation by step-wise depressurization was instantaneous, emanating preferentially from the interior of the sand-pack. Pressure drops during dissociation and in situ temperature controlled the degree of endothermic cooling within sediments. In a closed system, the post-depressurization dissociation was succeeded by thermally induced dissociation and pressure-temperature conditions followed theoretical methane-seawater equilibrium conditions and exhibited excess pore pressure governed by the pore diameter. These post-depressurization equilibrium values for the methane hydrates in seawater saturated consolidated sand-pack were used to estimate the enthalpy of dissociation of 55.83 ± 1.41 kJ/mol. These values were found to be lower than those reported in earlier literature for bulk hydrates from seawater (58.84 kJ/mol and pure water (62.61 kJ/mol due to excess pore pressure generated within confined sediment system under investigation. However, these observations could be significant in the case of hydrate dissociation in a subseafloor environment where dissociation due to depressurization could result in an instantaneous methane release followed by slow thermally induced dissociation. The excess pore pressure generated during hydrate dissociation could be higher within fine-grained sediments with faults and barriers present in subseafloor settings which could cause shifting in geological layers.

  11. Cryptic Methane Emissions from Upland Forest Ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Megonigal, Patrick [Smithsonian Institution, Washington, DC (United States); Pitz, Scott [Johns Hopkins Univ., Baltimore, MD (United States); Smithsonian Institution, Washington, DC (United States)

    2016-04-19

    This exploratory research on Cryptic Methane Emissions from Upland Forest Ecosystems was motivated by evidence that upland ecosystems emit 36% as much methane to the atmosphere as global wetlands, yet we knew almost nothing about this source. The long-term objective was to refine Earth system models by quantifying methane emissions from upland forests, and elucidate the biogeochemical processes that govern upland methane emissions. The immediate objectives of the grant were to: (i) test the emerging paradigm that upland trees unexpectedly transpire methane, (ii) test the basic biogeochemical assumptions of an existing global model of upland methane emissions, and (iii) develop the suite of biogeochemical approaches that will be needed to advance research on upland methane emissions. We instrumented a temperate forest system in order to explore the processes that govern upland methane emissions. We demonstrated that methane is emitted from the stems of dominant tree species in temperate upland forests. Tree emissions occurred throughout the growing season, while soils adjacent to the trees consumed methane simultaneously, challenging the concept that forests are uniform sinks of methane. High frequency measurements revealed diurnal cycling in the rate of methane emissions, pointing to soils as the methane source and transpiration as the most likely pathway for methane transport. We propose the forests are smaller methane sinks than previously estimated due to stem emissions. Stem emissions may be particularly important in upland tropical forests characterized by high rainfall and transpiration, resolving differences between models and measurements. The methods we used can be effectively implemented in order to determine if the phenomenon is widespread.

  12. Mobile sensing of point-source fugitive methane emissions using Bayesian inference: the determination of the likelihood function

    Science.gov (United States)

    Zhou, X.; Albertson, J. D.

    2016-12-01

    Natural gas is considered as a bridge fuel towards clean energy due to its potential lower greenhouse gas emission comparing with other fossil fuels. Despite numerous efforts, an efficient and cost-effective approach to monitor fugitive methane emissions along the natural gas production-supply chain has not been developed yet. Recently, mobile methane measurement has been introduced which applies a Bayesian approach to probabilistically infer methane emission rates and update estimates recursively when new measurements become available. However, the likelihood function, especially the error term which determines the shape of the estimate uncertainty, is not rigorously defined and evaluated with field data. To address this issue, we performed a series of near-source (methane release experiments using a specialized vehicle mounted with fast response methane analyzers and a GPS unit. Methane concentrations were measured at two different heights along mobile traversals downwind of the sources, and concurrent wind and temperature data are recorded by nearby 3-D sonic anemometers. With known methane release rates, the measurements were used to determine the functional form and the parameterization of the likelihood function in the Bayesian inference scheme under different meteorological conditions.

  13. Methane oxidation linked to chlorite dismutation.

    Directory of Open Access Journals (Sweden)

    Laurence G. Miller

    2014-06-01

    Full Text Available We examined the potential for CH4 oxidation to be coupled with oxygen derived from the dissimilatory reduction of perchlorate, chlorate or via chlorite (ClO2- dismutation. Although dissimilatory reduction of ClO4- and ClO3- 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, ClO2- 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 ClO2-. 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 ClO2-. 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 ClO2- and CH4 consumption was established in soils and cultures, no upstream connection with either ClO4- or ClO3- 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.

  14. Methane oxidation linked to chlorite dismutation

    Science.gov (United States)

    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.

  15. Methane emission from natural wetlands: interplay between emergent macrophytes and soil microbial processes. A mini review

    NARCIS (Netherlands)

    Laanbroek, H.J.

    2010-01-01

    Background: According to the Intergovernmental Panel on Climate Change (IPCC) 2007, natural wetlands contribute 20–39 % to the global emission of methane. The range in the estimated percentage of the contribution of these systems to the total release of this greenhouse gas is large due to

  16. Methane on Triton - Physical state and distribution

    Science.gov (United States)

    Cruikshank, D. P.; Apt, J.

    1984-01-01

    Infrared spectrophotometric measurements of Neptune's satellite Triton obtained between 1980 and 1982 in the spectral range 0.8-2.5 microns show six individual absorption bands attributable to methane. An additional band in the Triton data is not methane. The Triton spectral data conform more closely to a laboratory spectrum of frozen methane than to a synthetic spectrum of methane gas computed for conditions of low temperature expected at the satellite. Additionally, the strength of the bands vary with Triton's orbital position. The data thus suggest that methane in the ice phase is mostly responsible for the bands in Triton's spectrum, and that the ice is distributed nonuniformly around the satellite's surface.

  17. Coal Mine Methane in Russia

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-07-01

    This paper discusses coal mine methane emissions (CMM) in the Russian Federation and the potential for their productive utilisation. It highlights specific opportunities for cost-effective reductions of CMM from oil and natural gas facilities, coal mines and landfills, with the aim of improving knowledge about effective policy approaches.

  18. Potential methane reservoirs beneath Antarctica

    NARCIS (Netherlands)

    Wadham, J.L.; Arndt, S.|info:eu-repo/dai/nl/304835706; Tulaczyk, S.; Stibal, M.; Tranter, M.; Telling, J.; Lis, G.P.; Lawson, E.; Ridgwell, A.; Dubnick, A.; Sharp, M.J.; Anesio, A.M.; Butler, C.E.H.

    2012-01-01

    Once thought to be devoid of life, the ice-covered parts of Antarctica are now known to be a reservoir of metabolically active microbial cells and organic carbon. The potential for methanogenic archaea to support the degradation of organic carbon to methane beneath the ice, however, has not yet been

  19. Methane generation from waste materials

    Science.gov (United States)

    Samani, Zohrab A.; Hanson, Adrian T.; Macias-Corral, Maritza

    2010-03-23

    An organic solid waste digester for producing methane from solid waste, the digester comprising a reactor vessel for holding solid waste, a sprinkler system for distributing water, bacteria, and nutrients over and through the solid waste, and a drainage system for capturing leachate that is then recirculated through the sprinkler system.

  20. Methane Dynamics in Flooded Lands

    Science.gov (United States)

    Methane (CH4) is the second most important anthropogenic greenhouse gas with a heat trapping capacity 34 times greater than that of carbon dioxide on a100 year time scale. Known anthropogenic CH4 sources include livestock production, rice agriculture, landfills, and natural gas m...

  1. The disagreement between BSRS and the base of methane hydrate stability zones, in Shenhu area, north of South China Sea

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; He, L.; Wang, J. [Chinese Academy of Sciences, Beijing (China). Inst. of Geology and Geophysics

    2008-07-01

    Gas hydrate is an ice-like solid material that forms when natural gas is in contact with liquid water or ice under high pressure and low temperature. Gas hydrates occur in oceanic sediments and permafrost regions around the world. Release of methane hydrate into the atmosphere can cause environmental problems and pose a geological hazard. Methane hydrates can also be a potential energy resource. In the South China Sea, successful drilling and recovery of methane hydrate samples have proved that methane hydrate deposits are in existence in the northern South China Sea. The methane hydrate stability zone (HSZ), where the methane hydrate can form or exist stably in the sediments is mainly controlled by the temperature and the pressure conditions. When the temperature and pressure conditions are known, the depth of the base of the methane hydrate stability zone can be obtained. This paper presented a study that compared the bottom simulating reflector (BSR) depth and base of methane hydrate stability zone (BHSZ) in the Shenhu area, north of South China Sea. The paper defined BSRs and BHSZs and provided a comparison between the two. The paper also presented the results and discussion of results including origin of errors. It was concluded that there were greater differences between them than in other places world wide. These differences demonstrated regular spatial distribution and relationship with sedimentation rates and basement topography. The possible reason for the differences in regular spatial distribution was related to the geological setting. 9 refs., 4 figs.

  2. Electroencephalographic slow waves prior to sleepwalking episodes.

    Science.gov (United States)

    Perrault, Rosemarie; Carrier, Julie; Desautels, Alex; Montplaisir, Jacques; Zadra, Antonio

    2014-12-01

    Recent studies have suggested that the onset of sleepwalking episodes may be preceded by fluctuations in slow-wave sleep electroencephalographic characteristics. However, whether or not such fluctuations are specific to sleepwalking episodes or generalized to all sleep-wake transitions in sleepwalkers remains unknown. The goal of this study was to compare spectral power for delta (1-4 Hz) and slow delta (0.5-1 Hz) as well as slow oscillation density before the onset of somnambulistic episodes versus non-behavioral awakenings recorded from the same group of sleepwalkers. A secondary aim was to describe the time course of observed changes in slow-wave activity and slow oscillations during the 3 min immediately preceding the occurrence of somnambulistic episodes. Twelve adult sleepwalkers were investigated polysomnographically during the course of one night. Slow-wave activity and slow oscillation density were significantly greater prior to patients' somnambulistic episodes as compared with non-behavioral awakenings. However, there was no evidence for a gradual increase over the 3 min preceding the episodes. Increased slow-wave activity and slow oscillation density appear to be specific to sleepwalking episodes rather than generalized to all sleep-wake transitions in sleepwalkers. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Response of the Black Sea methane budget to massive short-term submarine inputs of methane

    DEFF Research Database (Denmark)

    Schmale, O.; Haeckel, M.; McGinnis, D. F.

    2011-01-01

    A steady state box model was developed to estimate the methane input into the Black Sea water column at various water depths. Our model results reveal a total input of methane of 4.7 Tg yr(-1). The model predicts that the input of methane is largest at water depths between 600 and 700 m (7......% of the total input), suggesting that the dissociation of methane gas hydrates at water depths equivalent to their upper stability limit may represent an important source of methane into the water column. In addition we discuss the effects of massive short-term methane inputs (e. g. through eruptions of deep......-water mud volcanoes or submarine landslides at intermediate water depths) on the water column methane distribution and the resulting methane emission to the atmosphere. Our non-steady state simulations predict that these inputs will be effectively buffered by intense microbial methane consumption...

  4. Historical methane hydrate project review

    Science.gov (United States)

    Collett, Timothy; Bahk, Jang-Jun; Frye, Matt; Goldberg, Dave; Husebo, Jarle; Koh, Carolyn; Malone, Mitch; Shipp, Craig; Torres, Marta

    2013-01-01

    In 1995, U.S. Geological Survey made the first systematic assessment of the volume of natural gas stored in the hydrate accumulations of the United States. That study, along with numerous other studies, has shown that the amount of gas stored as methane hydrates in the world greatly exceeds the volume of known conventional gas resources. However, gas hydrates represent both a scientific and technical challenge and much remains to be learned about their characteristics and occurrence in nature. Methane hydrate research in recent years has mostly focused on: (1) documenting the geologic parameters that control the occurrence and stability of gas hydrates in nature, (2) assessing the volume of natural gas stored within various gas hydrate accumulations, (3) analyzing the production response and characteristics of methane hydrates, (4) identifying and predicting natural and induced environmental and climate impacts of natural gas hydrates, and (5) analyzing the effects of methane hydrate on drilling safety.Methane hydrates are naturally occurring crystalline substances composed of water and gas, in which a solid water-­‐lattice holds gas molecules in a cage-­‐like structure. The gas and water becomes a solid under specific temperature and pressure conditions within the Earth, called the hydrate stability zone. Other factors that control the presence of methane hydrate in nature include the source of the gas included within the hydrates, the physical and chemical controls on the migration of gas with a sedimentary basin containing methane hydrates, the availability of the water also included in the hydrate structure, and the presence of a suitable host sediment or “reservoir”. The geologic controls on the occurrence of gas hydrates have become collectively known as the “methane hydrate petroleum system”, which has become the focus of numerous hydrate research programs.Recognizing the importance of methane hydrate research and the need for a coordinated

  5. Autobiographical Memory and Episodic Future Thinking

    DEFF Research Database (Denmark)

    Rasmussen, Katrine; Berntsen, Dorthe

    the construction of specific events during episodic future thinking remain largely unexplored. In this study, we examined whether episodic future thoughts depend on executive processes and are affected by cue imageability to the same extent as autobiographical remembering of past events. Results showed...... that autobiographical memory and episodic future thinking were affected similarly by cue imageability, suggesting that retrieval strategy can be manipulated in similar ways for both temporal directions. Furthermore, executive control processes (as measured by verbal fluency) was correlated with fluency and number...... of details in both memories and future thoughts, indicating the involvement of some common component processes in autobiographical memory and future thinking....

  6. Renin release

    DEFF Research Database (Denmark)

    Schweda, Frank; Friis, Ulla; Wagner, Charlotte

    2007-01-01

    The aspartyl-protease renin is the key regulator of the renin-angiotensin-aldosterone system, which is critically involved in salt, volume, and blood pressure homeostasis of the body. Renin is mainly produced and released into circulation by the so-called juxtaglomerular epithelioid cells, located...

  7. Development and evaluation of a new prototype P&T system to determine in-heading gas release rate.

    CSIR Research Space (South Africa)

    Van Zyl, FJ

    2001-11-01

    Full Text Available In order to quantify the potential methane hazard in underground coal mines, it is necessary to determine the in-seam methane content and an expected gas release rate during production. Various methods for estimating this have been proposed, ranging...

  8. Measurement of the Isotopic Signatures of Water on Mars: Implications for Studying Methane

    Science.gov (United States)

    Novak, R. E.; Mumma, M. J.; Villanueva, G. L.

    2010-01-01

    The recent discovery of methane on Mars has led to much discussion concerning its origin. On Earth, the isotopic signatures of methane vary with the nature of its production. Specifically, the ratios among 12CH4, 13CH4, and 12CH3D differ for biotic and abiotic origins. On Mars, measuring these ratios would provide insights into the origins of methane and measurements of water isotopologues co-released with methane would assist in testing their chemical relationship. Since 1997, we have been measuring HDO and H2O in Mars atmosphere and comparing their ratio to that in Earth s oceans. We recently incorporated a line-by-line radiative transfer model (LBLRTM) into our analysis. Here, we present a map for [HDO]/[H2O] along the central meridian (1541W) for Ls 501. From these results, we constructed models to determine the observational conditions needed to quantify the isotopic ratios of methane in Mars atmosphere. Current ground-based instruments lack the spectral resolution and sensitivity needed to make these measurements. Measurements of the isotopologues of methane will likely require in situ sampling.

  9. Attributing Atmospheric Methane to Anthropogenic Emission Sources.

    Science.gov (United States)

    Allen, David

    2016-07-19

    Methane is a greenhouse gas, and increases in atmospheric methane concentration over the past 250 years have driven increased radiative forcing of the atmosphere. Increases in atmospheric methane concentration since 1750 account for approximately 17% of increases in radiative forcing of the atmosphere, and that percentage increases by approximately a factor of 2 if the effects of the greenhouse gases produced by the atmospheric reactions of methane are included in the assessment. Because of the role of methane emissions in radiative forcing of the atmosphere, the identification and quantification of sources of methane emissions is receiving increased scientific attention. Methane emission sources include biogenic, geogenic, and anthropogenic sources; the largest anthropogenic sources are natural gas and petroleum systems, enteric fermentation (livestock), landfills, coal mining, and manure management. While these source categories are well-known, there is significant uncertainty in the relative magnitudes of methane emissions from the various source categories. Further, the overall magnitude of methane emissions from all anthropogenic sources is actively debated, with estimates based on source sampling extrapolated to regional or national scale ("bottom-up analyses") differing from estimates that infer emissions based on ambient data ("top-down analyses") by 50% or more. To address the important problem of attribution of methane to specific sources, a variety of new analytical methods are being employed, including high time resolution and highly sensitive measurements of methane, methane isotopes, and other chemical species frequently associated with methane emissions, such as ethane. This Account describes the use of some of these emerging measurements, in both top-down and bottom-up methane emission studies. In addition, this Account describes how data from these new analytical methods can be used in conjunction with chemical mass balance (CMB) methods for source

  10. [Torsades de pointes: analysis of 105 episodes].

    Science.gov (United States)

    Maia, I G; Sá, R; Alves, P A; Ribeiro, J C; Fernandes, P H; Guarçoni, O; Bassan, R; Dohmann, H F

    1993-02-01

    To analyze episodes of Torsades de Pointes (TP), in search of its electrocardiographic characteristics. We analyzed 105 episodes of TP, in 4 patients using quinidine and diuretics, recorded by 24-hour Holter monitoring. The following parameters were studied; ventricular repolarization out of TP, rhythm disturbances before TP; ECG characteristics of the onset, the bouts and the end of the TP. Ventricular repolarization, out of the TP, was abnormal, with the presence of U-waves at the end of the T-waves, resulting in prolongation of the QT (QU) interval. The U-wave voltage was noted to be cycle-length dependent. Ventricular bigeminy preceded TP in 100 episodes (95%) and the mean interval between both parameters was 18 +/- 16 min. The onset of the TP episodes showed the "short/long/short cycle rule", hereby called "pre-pause cycle", "preparing cycle" and "trigger cycle" respectively. The rotatory QRS-T morphology around the baseline, was seen in 75% of episodes, at the beginning or throughout the bout. Monomorphic ventricular tachycardia pattern was seen in the other 25% of episodes. Termination of bouts was sudden in all cases, and persistent ventricular bigeminy led to another bout in 90 episodes (85%). In TP patients, there is enlargement of QT intervals mostly due to U-waves appearance. The U-waves seen in these cases, probably have an important role in the genesis of TP and are probably related to ventricular after-potentials (triggered activity). Ventricular bigeminy is a premonitory sign of TP in patients using class 1A antiarrhythmic drugs. Persistent ventricular bigeminy post-TP episodes is a strong indicator of another bout of TP. The onset of TP is more important than its morphology for the correct diagnosis of this arrhythmia.

  11. Determinations of Titan's Methane and Haze Variability

    Science.gov (United States)

    Penteado, Paulo F.; Griffith, C.; Tomasko, M.; Engel, S.; See, C.; Doose, L.; VIMS Team

    2009-09-01

    Titan's atmosphere presents a complex and variable meteorology, with a variety of methane clouds detected in ground-based and Cassini near-IR observations. Its thick haze has been observed to vary seasonally, producing a strong variable effect on the radiative balance, dynamics and chemistry of the atmosphere. To understand how the methane cycle and the atmospheric variability, it becomes necessary to measure the methane and haze distribution. In this work, we analyze complementary observations to constrain the variation of the methane and haze: 1) ground-based spectra that resolve the variation of the CH3D band at 1600 nm, obtained with the Near Infrared Spectrograph (NIRSPEC) with adaptive optics at the Keck II telescope, constrain the methane abundance in the lowest 10 kmof the atmosphere. 2) Cassini VIMS (Visual and Infrared Mapping Spectrometer) observations at 400-1600 nm sampleregions of varied methane and haze optical depths, enough to partially constrain the profiles of the haze, and the upper tropospheric (20-50 km altitude) methane. The CH3D observations show no methane variation larger than 20% below 10 km altitude over 32S-32N latitudes. In the VIMS observations there is an ambiguity between the methane and haze abundances. The observations can be reproduced with no methane variation, and a haze density increase of 60% between 20S and 10S. The largest methane variation allowed by the data, derived assuming no haze variation with latitude, is a drop of 60% over latitudes 27S to 19N. To further constrain the range of possible methane and haze profiles, we also present an initial analysis of VIMS limb observations, which resolve the vertical structure of the atmosphere, and thus separate the spectral changes that originate at the troposphere (mostaffected by the methane) from those that originate at the stratosphere (most affected by the haze). Work supported by NASA, CAPES and FAPESP.

  12. Photocatalytic conversion of methane to methanol

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, C.E.; Noceti, R.P.; D`Este, J.R. [Pittsburgh Energy Technology Center, PA (United States)

    1995-12-31

    A long-term goal of our research group is the exploration of novel pathways for the direct oxidation of methane to liquid fuels, chemicals, and intermediates. The use of three relatively abundant and inexpensive reactants, light, water, and methane, to produce methanol is attractive. The products of reaction, methanol and hydrogen, are both commercially desirable, methanol being used as is or converted to a variety of other chemicals, and the hydrogen could be utilized in petroleum and/or chemical manufacturing. Methane is produced as a by-product of coal gasification. Depending upon reactor design and operating conditions, up to 18% of total gasifier product may be methane. In addition, there are vast proven reserves of geologic methane in the world. Unfortunately, a large fraction of these reserves are in regions where there is little local demand for methane and it is not economically feasible to transport it to a market. There is a global research effort under way in academia, industry, and government to find methods to convert methane to useful, more readily transportable and storable materials. Methanol, the initial product of methane oxidation, is a desirable product of conversion because it retains much of the original energy of the methane while satisfying transportation and storage requirements. Investigation of direct conversion of methane to transportation fuels has been an ongoing effort at PETC for over 10 years. One of the current areas of research is the conversion of methane to methanol, under mild conditions, using light, water, and a semiconductor photocatalyst. The use of three relatively abundant and inexpensive reactants, light, water, and methane, to produce methanol, is attractive. Research in the laboratory is directed toward applying the techniques developed for the photocatalytic splitting of the water and the photochemical conversion of methane.

  13. Ancient dissolved methane in inland waters at low concentrations revealed by a new collection method for radiocarbon (^{14}C) analysis

    Science.gov (United States)

    Dean, Joshua F.; Billett, Michael F.; Murray, Callum; Garnett, Mark H.

    2017-04-01

    Methane (CH4) is a powerful greenhouse gas and is released to the atmosphere from freshwater systems in numerous biomes globally. Radiocarbon (14C) analysis of methane can provide unique information about its age, source and rate of cycling in natural environments. Methane is often released from aquatic sediments in bubbles (ebullition), but dissolved methane is also present in lakes and streams at lower concentrations, and may not be of the same age or source. Obtaining sufficient non-ebullitive aquatic methane for 14C analysis remains a major technical challenge. Previous studies have shown that freshwater methane, in both dissolved and ebullitive form, can be significantly older than other forms of aquatic carbon (C), and it is therefore important to characterise this part of the terrestrial C balance. We present a novel method to capture sufficient amounts of dissolved methane from freshwater environments for 14C analysis by circulating water across a hydrophobic, gas-permeable membrane and collecting the methane in a large collapsible vessel. The results of laboratory and field tests show that reliable dissolved δ13CH4 and 14CH4 samples can be readily collected over short time periods (˜4 to 24 hours), at relatively low cost and from a variety of surface water types. The initial results further support previous findings that dissolved methane can be significantly older than other forms of aquatic C, especially in organic-rich catchments, and is currently unaccounted for in many terrestrial C balances and models. This method is suitable for use in remote locations, and could potentially be used to detect the leakage of unique 14CH4 signatures from point sources into waterways, e.g. coal seam gas and landfill gas.

  14. Clinical care management and workflow by episodes.

    Science.gov (United States)

    Claus, P L; Carpenter, P C; Chute, C G; Mohr, D N; Gibbons, P S

    1997-01-01

    This paper describes the implementation of clinically defined episodes of care and the introduction of an episode-based summary list of patient problems across Mayo Clinic Rochester in 1996 and 1997. Although Mayo's traditional paper-based system has always relied on a type of 'episode of care' (called the "registration") for patient and history management, a new, more clinically relevant definition of episode of care was put into practice in November 1996. This was done to improve care management and operational processes and to provide a basic construct for the electronic medical record. Also since November 1996, a computer-generated summary list of patient problems, the "Master Sheet Summary Report," organized by episode, has been placed in all patient histories. In the third quarter of 1997, the ability to view the episode-based problem summary online was made available to the 3000+ EMR-capable workstations deployed across the Mayo Rochester campus. In addition, the clinically oriented problem summarization process produces an improved basic "package" of clinical information expected to lead to improved analytic decision support, outcomes analysis and epidemiological research.

  15. Rapid rates of aerobic methane oxidation at the feather edge of gas hydrate stability in the waters of Hudson Canyon, US Atlantic Margin

    Science.gov (United States)

    Leonte, Mihai; Kessler, John D.; Kellermann, Matthias Y.; Arrington, Eleanor C.; Valentine, David L.; Sylva, Sean P.

    2017-05-01

    Aerobic oxidation is an important methane sink in seawater overlying gas seeps. Recent surveys have identified active methane seeps in the waters of Hudson Canyon, US Atlantic Margin near the updip limit of methane clathrate hydrate stability. The close proximity of these seeps to the upper stability limit of methane hydrates suggests that changing bottom water temperatures may influence the release rate of methane into the overlying water column. In order to assess the significance of aerobic methane oxidation in limiting the atmospheric expression of methane released from Hudson Canyon, the total extent of methane oxidized along with integrated oxidation rates were quantified. These calculations were performed by combining the measurements of the natural levels of methane concentrations, stable carbon isotopes, and water current velocities into kinetic isotope models yielding rates ranging from 22.8 ± 17 to 116 ± 76 nM/day with an average of 62.7 ± 37 nM/day. Furthermore, an average of 63% of methane released into the water column from an average depth of 515 m was oxidized before leaving this relatively small study area (6.5 km2). Results from the kinetic isotope model were compared to previously-published but concurrently-sampled ex situ measurements of oxidation potential performed using 13C-labeled methane. Ex situ rates were substantially lower, ranging from 0.1 to 22.5 nM/day with an average of 5.6 ± 2.3 nM/day, the discrepancy likely due to the inherent differences between these two techniques. Collectively, the results reveal exceptionally-rapid methane oxidation, with turnover times for methane as low as 0.3-3.7 days, indicating that methane released to the water column is removed quantitatively within the greater extent of Hudson Canyon. The red line represents the original Rayleigh model output, Eq. (1), detailed in the text. The red line represents the original Rayleigh model output, Eq. (1), detailed in the text.

  16. On-farm methane measurements during milking correlate with total methane production by individual dairy cows

    National Research Council Canada - National Science Library

    Garnsworthy, P C; Craigon, J; Hernandez-Medrano, J H; Saunders, N

    2012-01-01

    The objective of this study was to investigate whether measurement of methane emissions by individual dairy cows during milking could provide a useful technique for monitoring on-farm methane emissions...

  17. Methane oxidation associated to submerged brown-mosses buffers methane emissions from Siberian polygonal peatlands

    Science.gov (United States)

    Liebner, Susanne; Zeyer, Josef; Knoblauch, Christian

    2010-05-01

    Circumpolar peatlands store roughly 18 % of the globally stored carbon in soils [based on 1, 2]. Also, northern wetlands and tundra are a net source of methane (CH4), an effective greenhouse gas (GHG), with an estimated annual CH4 release of 7.2% [3] or 8.1% [4] of the global total CH4 emission. Although it is definite that Arctic tundra significantly contributes to the global methane emissions in general, regional variations in GHG fluxes are enormous. CH4 fluxes of polygonal tundra within the Siberian Lena Delta, for example, were reported to be low [5, 6], particularly at open water polygonal ponds and small lakes [7] which make up around 10 % of the delta's surface. Low methane emissions from polygonal ponds oppose that Arctic permafrost thaw ponds are generally known to emit large amounts of CH4 [8]. Combining tools of biogeochemistry and molecular microbiology, we identified sinks of CH4 in polygonal ponds from the Lena Delta that were not considered so far in GHG studies from Arctic wetlands. Pore water CH4 profiling in polygonal ponds on Samoylov, a small island in the central part of the Lena Delta, revealed a pronounced zone of CH4 oxidation near the vegetation surface in submerged layers of brown-mosses. Here, potential CH4 oxidation was an order of magnitude higher than in non-submerged mosses and in adjacent bulk soil. We could additionally show that this moss associated methane oxidation (MAMO) is hampered when exposure of light is prevented. Shading of plots with submerged Scorpidium scorpioides inhibited MAMO leading to higher CH4 concentrations and an increase in CH4 fluxes by a factor of ~13. Compared to non-submerged mosses, the submerged mosses also showed significantly lower δ13C values indicating that they use carbon dioxide derived from methane oxidation for photosynthesis. Applying stable isotope probing of DNA, type II methanotrophs were identified to be responsible for the oxidation of CH4 in the submerged Scorpidium scorpioides. Our

  18. Atmospheric methane removal by methane-oxidizing bacteria immobilized on porous building materials

    NARCIS (Netherlands)

    Ganendra, G; De Muynck, W; Ho, A.; Hoefman, S.; De Vos, P.; Boeckx, P.; Boon, N.

    2014-01-01

    Biological treatment using methane-oxidizing bacteria (MOB) immobilized on six porous carrier materials have been used to mitigate methane emission. Experiments were performed with different MOB inoculated in building materials at high (similar to 20 % (v/v)) and low (similar to 100 ppmv) methane

  19. Quantification of the methane concentration using anaerobic oxidation of methane coupled to extracellular electron transfer

    Science.gov (United States)

    A biofilm anode acclimated with acetate, acetate+methane, and methane growth media for over three years produced a steady current density of 1.6-2.3 mA/m^2 in a microbial electrochemical cell (MxC) fed with methane as the sole electron donor. Geobacter was the dominant genus for...

  20. Microchannel Methanation Reactors Using Nanofabricated Catalysts Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Makel Engineering, Inc. (MEI) and the Pennsylvania State University (Penn State) propose to develop and demonstrate a microchannel methanation reactor based on...

  1. Methane emission during municipal wastewater treatment.

    Science.gov (United States)

    Daelman, Matthijs R J; van Voorthuizen, Ellen M; van Dongen, Udo G J M; Volcke, Eveline I P; van Loosdrecht, Mark C M

    2012-07-01

    Municipal wastewater treatment plants emit methane. Since methane is a potent greenhouse gas that contributes to climate change, the abatement of the emission is necessary to achieve a more sustainable urban water management. This requires thorough knowledge of the amount of methane that is emitted from a plant, but also of the possible sources and sinks of methane on the plant. In this study, the methane emission from a full-scale municipal wastewater facility with sludge digestion was evaluated during one year. At this plant the contribution of methane emissions to the greenhouse gas footprint were slightly higher than the CO₂ emissions related to direct and indirect fossil fuel consumption for energy requirements. By setting up mass balances over the different unit processes, it could be established that three quarters of the total methane emission originated from the anaerobic digestion of primary and secondary sludge. This amount exceeded the carbon dioxide emission that was avoided by utilizing the biogas. About 80% of the methane entering the activated sludge reactor was biologically oxidized. This knowledge led to the identification of possible measures for the abatement of the methane emission. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. [Sources of Methane in the Boreal Region

    Science.gov (United States)

    1998-01-01

    In determining the global methane budget the sources of methane must be balanced with the sinks and atmospheric inventory. The approximate contribution of the different methane sources to the budget has been establish showing the major terrestrial inputs as rice, wetlands, bogs, fens, and tundra. Measurements and modeling of production in these sources suggest that temperature, water table height and saturation along with substratum composition are important in controlling methane production and emission. The isotopic budget of 13 C and D/H in methane can be used as a tool to clarify the global budget. This approach has achieved success at constraining the inputs. Studies using the isotopic approach place constraints on global methane production from different sources. Also, the relation between the two biogenic production pathways, acetate fermentation and CO2 reduction, and the effect of substratum composition can be made using isotope measurements shows the relation between the different biogenic, thermogenic and anthropogenic sources of methane as a function of the carbon and hydrogen isotope values for each source and the atmosphere, tropospheric composition. Methane emissions from ponds and fens are a significant source in the methane budget of the boreal region. An initial study in 1993 and 1994 on the isotopic composition of this methane source and the isotopic composition in relation to oxidation of methane at the sediment surface of the ponds or fen was conducted as part of our BOREAS project. The isotopic composition of methane emitted by saturated anoxic sediment is dependent on the sediment composition and geochemistry, but will be influenced by in situ oxidation, in part, a function of rooted plant activity. The influence of oxidation mediated by rooted plant activities on the isotopic composition of methane is not well known and will depend on the plant type, sediment temperature, and numerous other variables. Information on this isotopic composition

  3. Shallow Gas Migration along Hydrocarbon Wells-An Unconsidered, Anthropogenic Source of Biogenic Methane in the North Sea.

    Science.gov (United States)

    Vielstädte, Lisa; Haeckel, Matthias; Karstens, Jens; Linke, Peter; Schmidt, Mark; Steinle, Lea; Wallmann, Klaus

    2017-09-05

    Shallow gas migration along hydrocarbon wells constitutes a potential methane emission pathway that currently is not recognized in any regulatory framework or greenhouse gas inventory. Recently, the first methane emission measurements at three abandoned offshore wells in the Central North Sea (CNS) were conducted showing that considerable amounts of biogenic methane originating from shallow gas accumulations in the overburden of deep reservoirs were released by the boreholes. Here, we identify numerous wells poking through shallow gas pockets in 3-D seismic data of the CNS indicating that about one-third of the wells may leak, potentially releasing a total of 3-17 kt of methane per year into the North Sea. This poses a significant contribution to the North Sea methane budget. A large fraction of this gas (∼42%) may reach the atmosphere via direct bubble transport (0-2 kt yr(-1)) and via diffusive exchange of methane dissolving in the surface mixed layer (1-5 kt yr(-1)), as indicated by numerical modeling. In the North Sea and in other hydrocarbon-prolific provinces of the world shallow gas pockets are frequently observed in the sedimentary overburden and aggregate leakages along the numerous wells drilled in those areas may be significant.

  4. Studying bubble-induced methane emissions from the East Siberian Arctic Shelf: the next step towards a quantitative assessment.

    Science.gov (United States)

    Chernykh, D.; Shakhova, N. E.; Semiletov, I. P.; Yusupov, V.; Salomatin, A.; Leifer, I.

    2015-12-01

    Destabilization of subsea permafrost results in increasing permeability for gaseous methane long preserved in seabed deposits within and beneath permafrost. This process manifests as extensive methane ebullition, driving significantly elevated methane aqueous concentrations - up to three orders higher than atmospheric equilibrium. In places, bubbles release as a vigorous flow that often reach the surface; on echograms, such bubble plums create specific flare-like images. To detect, map, monitor, and analyze bubble-induced methane fluxes, in summer 2011 and 2012, sonar data were gathered over extensive seep fields in the East Siberian Arctic Shelf (ESAS) in frame of International Siberian Shelf Study (ISSS). To measure the bubble screen backscattering strength, the acoustic sensors were calibrated using a target ("ideal" sphere) provided by the manufacturer (SIMRAD). To establish a relationship between the backscattering strength of bubbles releasing from the seafloor and methane flux rate, an in-situ calibration using engineered seeps was performed. To apportion fraction of bubbles reaching the sea surface and assess remaining gaseous content of bubbles, in winter 2011-2013, direct in-situ observations of bubbles, ascending from the seafloor, were performed using high-speed high-resolution video camera. Results of inter-calibration between engineered quantitative in-situ calibrations and qualitative calibration recommended by manufacturer were applied to evaluate bubble-induced methane fluxes observed in the ESAS in summer 2011 and 2012.

  5. Diel methane emission patterns from Scirpus lacustris and Phragmites australis

    NARCIS (Netherlands)

    Van der Nat, J.W.A.; Middelburg, J.J.; Van Meteren, D.; Wielemaker, A.

    1998-01-01

    In mature Phragmites australis and Scirpus lacustris vegetated sediment methane was emitted almost exclusively by plant- mediated transport, whereas in unvegetated, but otherwise identical sediment, methane was emitted almost exclusively by ebullition. Diel variations in methane emission, with

  6. Fluxes of Methane and Carbon Dioxide from a Subarctic Lake

    DEFF Research Database (Denmark)

    Jammet, Mathilde Manon

    important for the lake annual emissions compared to the length of the period, as it turned the lake from a small summer CO2 sink into an annual source. Annual inter-annual variability was notable in the magnitude of the CH4 spring release and needs further investigation. The high temporal resolution......-out and the release of CH4 and CO2 was established. These results underline the crucial importance of shoulder seasons in the annual carbon emissions from seasonally frozen lakes. Overall, the lake was an important annual source of carbon to the atmosphere, partially compensating the higher, annual sink function......Ongoing climate warming is expected to affect the carbon functioning of subarctic ecosystems. Lakes and wetlands, which are common ecosystems of the high northern latitudes, are of utmost interest in this context because they exchange large amounts of the climate-forcing gases methane (CH4...

  7. Preparation of Ti3C2 and Ti2C MXenes by fluoride salts etching and methane adsorptive properties

    Science.gov (United States)

    Liu, Fanfan; Zhou, Aiguo; Chen, Jinfeng; Jia, Jin; Zhou, Weijia; Wang, Libo; Hu, Qianku

    2017-09-01

    Here we reported the preparation of Ti3C2 MXene and Ti2C MXene by etching Ti3AlC2 and Ti2AlC with various fluoride salts in hydrochloric acid (HCl), including lithium fluoride (LiF), sodium fluoride (NaF), potassium fluoride (KF), and ammonium fluoride (NH4F). As-prepared Ti2C was further delaminated by urea, dimethylsulfoxide or ammonium hydroxide. Based on theoretical calculation and XPS results, the type of positive ions (Li+, Na+, K+, or NH4+) in etchant solution affect the surface structure of prepared MXene, which, in turn, affects the methane adsorption properties of MXene. The highest methane adsorption capacity is 8.5 cm3/g for Ti3C2 and 11.6 cm3/g for Ti2C. MXenes made from LiF and NH4F can absorb methane under high pressure and can keep methane under normal pressure, these MXenes may have important application on capturing methane or other hazardous gas molecules. MXenes made from NaF and KF can absorb methane under high pressure and release methane under low pressure. They can have important application in the adsorb storage of nature gas.

  8. Methane excess production in oxygen-rich polar water and a model of cellular conditions for this paradox

    Science.gov (United States)

    Damm, E.; Thoms, S.; Beszczynska-Möller, A.; Nöthig, E. M.; Kattner, G.

    2015-09-01

    Summer sea ice cover in the Arctic Ocean has undergone a reduction in the last decade exposing the sea surface to unforeseen environmental changes. Melting sea ice increases water stratification and induces nutrient limitation, which is also known to play a crucial role in methane formation in oxygenated surface water. We report on an excess of methane in the marginal ice zone in the western Fram Strait. Our study is based on measurements of oxygen, methane, DMSP, nitrate and phosphate concentrations as well as on phytoplankton composition and light transmission, conducted along the 79°N oceanographic transect, in the western part of the Fram Strait and in Northeast Water Polynya region off Greenland. Between the eastern Fram Strait, where Atlantic water enters from the south and the western Fram Strait, where Polar water enters from the north, different nutrient limitations occurred and consequently different bloom conditions were established. Ongoing sea ice melting enhances the environmental differences between both water masses and initiates regenerated production in the western Fram Strait. We show that in this region methane is in situ produced while DMSP (dimethylsulfoniopropionate) released from sea ice may serve as a precursor for the methane formation. The methane production occured despite high oxygen concentrations in this water masses. As the metabolic activity (respiration) of unicellular organisms explains the presence of anaerobic conditions in the cellular environment we present a theoretical model which explains the maintenance of anaerobic conditions for methane formation inside bacterial cells, despite enhanced oxygen concentrations in the environment.

  9. Transition mechanism of sH to filled-ice Ih structure of methane hydrate under fixed pressure condition

    Science.gov (United States)

    Kadobayashi, H.; Hirai, H.; Ohfuji, H.; Kojima, Y.; Ohishi, Y.; Hirao, N.; Ohtake, M.; Yamamoto, Y.

    2017-10-01

    The phase transition mechanism of methane hydrate from sH to filled-ice Ih structure was examined using a combination of time-resolved X-ray diffractometry (XRD) and Raman spectroscopy in conjunction with charge-coupled device (CCD) camera observation under fixed pressure conditions. Prior to time-resolved Raman experiments, the typical C-H vibration modes and their pressure dependence of three methane hydrate structures, fluid methane and solid methane were measured using Raman spectroscopy to distinguish the phase transitions of methane hydrates from decomposition to solid methane and ice VI or VII. Experimental results by XRD, Raman spectroscopy and CCD camera observation revealed that the structural transition of sH to filled-ice Ih occurs through a collapse of the sH framework followed by the release of fluid methane that is then gradually incorporated into the filled-ice Ih to reconstruct its structure. These observations suggest that the phase transition of sH to filled-ice Ih takes place by a typical reconstructive mechanism.

  10. Methane for Power Generation in Muaro Jambi: A Green Prosperity Model Project

    Energy Technology Data Exchange (ETDEWEB)

    Moriarty, K.; Elchinger, M.; Hill, G.; Katz, J.; Barnett, J.

    2014-07-01

    NREL conducted eight model projects for Millennium Challenge Corporation's (MCC) Compact with Indonesia. Green Prosperity, the largest project of the Compact, seeks to address critical constraints to economic growth while supporting the Government of Indonesia's commitment to a more sustainable, less carbon-intensive future. This study evaluates electricity generation from the organic content of wastewater at a palm oil mill in Muaro Jambi, Sumatra. Palm mills use vast amounts of water in the production process resulting in problematic waste water called palm oil mill effluent (POME). The POME releases methane to the atmosphere in open ponds which could be covered to capture the methane to produce renewable electricity for rural villages. The study uses average Indonesia data to determine the economic viability of methane capture at a palm oil mill and also evaluates technology as well as social and environmental impacts of the project.

  11. Rising atmospheric methane: 2007–2014 growth and isotopic shift

    National Research Council Canada - National Science Library

    Nisbet, E. G; Dlugokencky, E. J; Manning, M. R; Lowry, D; Fisher, R. E; France, J. L; Michel, S. E; Miller, J. B; White, J. W. C; Vaughn, B; Bousquet, P; Pyle, J. A; Warwick, N. J; Cain, M; Brownlow, R; Zazzeri, G; Lanoisellé, M; Manning, A. C; Gloor, E; Worthy, D. E. J; Brunke, E.‐G; Labuschagne, C; Wolff, E. W; Ganesan, A. L

    2016-01-01

    .... The isotopic evidence presented here suggests that the methane rise was dominated by significant increases in biogenic methane emissions, particularly in the tropics, for example, from expansion...

  12. Dike intrusions during rifting episodes obey scaling relationships similar to earthquakes

    Science.gov (United States)

    L., Passarelli; E., Rivalta; A., Shuler

    2014-01-01

    As continental rifts evolve towards mid-ocean ridges, strain is accommodated by repeated episodes of faulting and magmatism. Discrete rifting episodes have been observed along two subaerial divergent plate boundaries, the Krafla segment of the Northern Volcanic Rift Zone in Iceland and the Manda-Hararo segment of the Red Sea Rift in Ethiopia. In both cases, the initial and largest dike intrusion was followed by a series of smaller intrusions. By performing a statistical analysis of these rifting episodes, we demonstrate that dike intrusions obey scaling relationships similar to earthquakes. We find that the dimensions of dike intrusions obey a power law analogous to the Gutenberg-Richter relation, and the long-term release of geodetic moment is governed by a relationship consistent with the Omori law. Due to the effects of magma supply, the timing of secondary dike intrusions differs from that of the aftershocks. This work provides evidence of self-similarity in the rifting process. PMID:24469260

  13. Plasma catalytic reforming of methane

    Energy Technology Data Exchange (ETDEWEB)

    Bromberg, L.; Cohn, D.R.; Rabinovich, A. [Massachusetts Inst. of Technology, Cambridge, MA (United States). Plasma Science and Fusion Center; Alexeev, N. [Russian Academy of Sciences, Moscow (Russian Federation). Baikov Inst. of Metallurgy

    1998-08-01

    Thermal plasma technology can be efficiently used in the production of hydrogen and hydrogen-rich gases from methane and a variety of fuels. This paper describes progress in plasma reforming experiments and calculations of high temperature conversion of methane using heterogeneous processes. The thermal plasma is a highly energetic state of matter that is characterized by extremely high temperatures (several thousand degrees Celsius) and high degree of dissociation and substantial degree of ionization. The high temperatures accelerate the reactions involved in the reforming process. Hydrogen-rich gas (50% H{sub 2}, 17% CO and 33% N{sub 2}, for partial oxidation/water shifting) can be efficiently made in compact plasma reformers. Experiments have been carried out in a small device (2--3 kW) and without the use of efficient heat regeneration. For partial oxidation/water shifting, it was determined that the specific energy consumption in the plasma reforming processes is 16 MJ/kg H{sub 2} with high conversion efficiencies. Larger plasmatrons, better reactor thermal insulation, efficient heat regeneration and improved plasma catalysis could also play a major role in specific energy consumption reduction and increasing the methane conversion. A system has been demonstrated for hydrogen production with low CO content ({approximately} 1.5%) with power densities of {approximately} 30 kW (H{sub 2} HHV)/liter of reactor, or {approximately} 10 m{sup 3}/hr H{sub 2} per liter of reactor. Power density should further increase with increased power and improved design.

  14. Practical aspects of methane measurements

    Energy Technology Data Exchange (ETDEWEB)

    Marais, D. (Chamber of Mines of South Africa)

    1989-07-01

    Historically, there has always existed a need in the underground mining environment for detecting the presence of flammable (combustible) gases. The Davy lamp, designed for improved safe illumination by Sir Humphrey Davy, also provided the first practicable means whereby the presence of flammable gas could be detected. These lamps as well as subsequent derivatives, were used in British coal mines from 1815. They also saw use in South African mines until 1987 when they were officially replaced by 'an approved electronic device' (i.e. a methanometer). This paper describes methods and practical aspects of detection and measurement of methane.

  15. Dissociation of methane hydrate granules

    Science.gov (United States)

    Misyura, S. Y.; Donskoy, I. G.; Morozov, V. S.

    2017-09-01

    The methane hydrate dissociation at negative temperatures and under external pressure of 1 bar is studied experimentally. It is shown that the dissociation rate of the gas hydrate depends on the granule diameter and heat transfer. The dissociation curve has an extremum. The dissociation rate initially increases due to the temperature increase and reaches the maximum value and then sharply falls due to the curvature of the granules. When describing dissociation kinetics of the spherical granules, it is important to take into account the granule size and their composition.

  16. Inhibition of methane oxidation by Methylococcus capsulatus with hydrochlorofluorocarbons and fluorinated methanes

    Science.gov (United States)

    Matheson, L.J.; Jahnke, L.L.; Oremland, R.S.

    1997-01-01

    The inhibition of methane oxidation by cell suspensions of Methylococcus capsulatus (Bath) exposed to hydrochlorofluorocarbon 21 (HCFC-21; difluorochloromethane [CHF2Cl]), HCFC-22 (fluorodichloromethane [CHFCl2]), and various fluorinated methanes was investigated. HCFC-21 inhibited methane oxidation to a greater extent than HCFC-22, for both the particulate and soluble methane monooxygenases. Among the fluorinated methanes, both methyl fluoride (CH3F) and difluoromethane (CH2F2) were inhibitory while fluoroform (CHF3) and carbon tetrafluoride (CF4) were not. The inhibition of methane oxidation by HCFC-21 and HCFC-22 was irreversible, while that by methyl fluoride was reversible. The HCFCs also proved inhibitory to methanol dehydrogenase, which suggests that they disrupt other aspects of C1 catabolism in addition to methane monooxygenase activity.

  17. Centennial evolution of the atmospheric methane budget: what do the carbon isotopes tell us?

    Directory of Open Access Journals (Sweden)

    K. R. Lassey

    2007-01-01

    Full Text Available Little is known about how the methane source inventory and sinks have evolved over recent centuries. New and detailed records of methane mixing ratio and isotopic composition (12CH4, 13CH4 and 14CH4 from analyses of air trapped in polar ice and firn can enhance this knowledge. We use existing bottom-up constructions of the source history, including "EDGAR"-based constructions, as inputs to a model of the evolving global budget for methane and for its carbon isotope composition through the 20th century. By matching such budgets to atmospheric data, we examine the constraints imposed by isotope information on those budget evolutions. Reconciling both 12CH4 and 13CH4 budgets with EDGAR-based source histories requires a combination of: a greater proportion of emissions from biomass burning and/or of fossil methane than EDGAR constructions suggest; a greater contribution from natural such emissions than is commonly supposed; and/or a significant role for active chlorine or other highly-fractionating tropospheric sink as has been independently proposed. Examining a companion budget evolution for 14CH4 exposes uncertainties in inferring the fossil-methane source from atmospheric 14CH4 data. Specifically, methane evolution during the nuclear era is sensitive to the cycling dynamics of "bomb 14C" (originating from atmospheric weapons tests through the biosphere. In addition, since ca. 1970, direct production and release of 14CH4 from nuclear-power facilities is influential but poorly quantified. Atmospheric 14CH4 determinations in the nuclear era have the potential to better characterize both biospheric carbon cycling, from photosynthesis to methane synthesis, and the nuclear-power source.

  18. Severity of depressive episodes during the course of depressive disorder

    DEFF Research Database (Denmark)

    Kessing, L.V.

    2008-01-01

    contact. The prevalence of severe depressive episodes increased from 25.5% at the first episode to 50.0% at the 15th episode and the prevalence of psychotic episodes increased from 8.7% at the first episode to 25.0% at the 15th episode. The same pattern was found regardless of gender, age at first contact......Background It is not clear whether the severity of depressive episodes changes during the course of depressive disorder. Aims To investigate whether the severity of depressive episodes increases during the course of illness. Method Using a Danish nationwide case register, all psychiatric inpatients...... and out-patients with a main ICD-10 diagnosis of a single mild, moderate or severe depressive episode at the end of first contact were identified. Patients included in the study were from the period 1994-2003. Results A total of 19 392 patients received a diagnosis of a single depressive episode at first...

  19. Factors controlling headspace pressure in a manual manometric BMP method can be used to produce a methane output comparable to AMPTS.

    Science.gov (United States)

    Himanshu, H; Voelklein, M A; Murphy, J D; Grant, J; O'Kiely, P

    2017-08-01

    The manual manometric biochemical methane potential (mBMP) test uses the increase in pressure to calculate the gas produced. This gas production may be affected by the headspace volume in the incubation bottle and by the overhead pressure measurement and release (OHPMR) frequency. The biogas and methane yields of cellulose, barley, silage and slurry were compared with three incubation bottle headspace volumes (50, 90 and 180ml; constant 70ml total medium) and four OHPMR frequencies (daily, each third day, weekly and solely at the end of experiment). The methane yields of barley, silage and slurry were compared with those from an automated volumetric method (AMPTS). Headspace volume and OHPMR frequency effects on biogas yield were mediated mainly through headspace pressure, with the latter having a negative effect on the biogas yield measured and relatively little effect on methane yield. Two mBMP treatments produced methane yields equivalent to AMPTS. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Methane emission from wetland rice fields

    NARCIS (Netherlands)

    Denier van der Gon, H.A.C.

    1996-01-01


    Methane (CH 4 ) is an important greenhouse gas and plays a key role in tropospheric and stratospheric chemistry. Wetland rice fields are an important source of methane, accounting for approximately 20% of the global anthropogenic

  1. Livestock-environment interactions: Methane emissions from ...

    African Journals Online (AJOL)

    Livestock account for 35-40% of global anthropogenic emissions of methane, via enteric fermentation and manure, which together account for about 80% of the agricultural emissions. Recent estimates indicate that the methane emissions from African cattle, goats, and sheep are likely to increase from their current level of ...

  2. Abiotic production of methane in terrestrial planets.

    Science.gov (United States)

    Guzmán-Marmolejo, Andrés; Segura, Antígona; Escobar-Briones, Elva

    2013-06-01

    On Earth, methane is produced mainly by life, and it has been proposed that, under certain conditions, methane detected in an exoplanetary spectrum may be considered a biosignature. Here, we estimate how much methane may be produced in hydrothermal vent systems by serpentinization, its main geological source, using the kinetic properties of the main reactions involved in methane production by serpentinization. Hydrogen production by serpentinization was calculated as a function of the available FeO in the crust, given the current spreading rates. Carbon dioxide is the limiting reactant for methane formation because it is highly depleted in aqueous form in hydrothermal vent systems. We estimated maximum CH4 surface fluxes of 6.8×10(8) and 1.3×10(9) molecules cm(-2) s(-1) for rocky planets with 1 and 5 M⊕, respectively. Using a 1-D photochemical model, we simulated atmospheres with volume mixing ratios of 0.03 and 0.1 CO2 to calculate atmospheric methane concentrations for the maximum production of this compound by serpentinization. The resulting abundances were 2.5 and 2.1 ppmv for 1 M⊕ planets and 4.1 and 3.7 ppmv for 5 M⊕ planets. Therefore, low atmospheric concentrations of methane may be produced by serpentinization. For habitable planets around Sun-like stars with N2-CO2 atmospheres, methane concentrations larger than 10 ppmv may indicate the presence of life.

  3. Individual methane recordings in dairy cattle

    NARCIS (Netherlands)

    Ogink, N.W.M.; Crump, R.E.; Haas, de Y.; Mosquera Losada, J.; Bannink, A.; Dijkstra, J.

    2012-01-01

    In this study options are explored for individual methane recordings of dairy cows on large scale under practical circumstances. In a simulation study based on respiration research data, accuracies of methane measurements based on different sampling strategies are calculated. Scenarios showed that

  4. Raman Spectroscopic Studies of Methane Gas Hydrates

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Berg, Rolf W.

    2009-01-01

    A brief review of the Raman spectroscopic studies of methane gas hydrates is given, supported by some new measurements done in our laboratory.......A brief review of the Raman spectroscopic studies of methane gas hydrates is given, supported by some new measurements done in our laboratory....

  5. Boreal Inundation Mapping with SMAP Radiometer Data for Methane Studies

    Science.gov (United States)

    Kim, Seungbum; Brisco, Brian; Poncos, Valentin

    2017-04-01

    Inundation and consequent anoxic condition induce methane release, which is one of the most potent greenhouse gases. Boreal regions contain large amounts of organic carbon, which is a potentially major methane emission source under climatic warming conditions. Boreal wetlands in particular are one of the largest sources of uncertainties in global methane budget. Wetland spatial extent together with the gas release rate remains highly unknown. Characterization of the existing inundation database is poor, because of the inundation under clouds and dense vegetation. In this work, the inundation extent is derived using brightness temperature data acquired by the L-band Soil Moisture Active Passive (SMAP) satellite, which offers the L-band capabilities to penetrate clouds and vegetation at 3-day revisit. The fidelity of the SMAP watermask is assessed as a first step in this investigation by comparing with the following data sets: 3-m resolution maps derived using Radarsat synthetic aperture radar (SAR) data in northern Canada and multi-sensor climatology over Siberia. Because Radarsat coverages are limited despite its high spatial resolution, at the time and location where Radarsats are not available, we also compare with 3-km resolution SMAP SAR data that are concurrent with the SMAP radiometer data globally until July 2015. Inundation extents were derived with Radarsat, SMAP SAR, and SMAP radiometer over the 60 km x 60km area at Peace Athabasca Delta (PAD), Canada on 6 days in spring and summer 2015. The SMAP SAR results match the locations of Radarsat waterbodies. However, the SMAP SAR underestimates the water extent, mainly over mixed pixels that have subpixel land presence. The threshold value (-3 dB) applied to the SMAP SAR was determined previously over the global domain. The threshold is dependent on the type of local landcover within a mixed pixel. Further analysis is needed to locally optimize the threshold. The SMAP radiometer water fraction over Peace

  6. Robust IR Remote Sensing Technique of the Total Column of Trace Gases Including Carbon Dioxide and Methane

    Science.gov (United States)

    Georgieva, E. M.; Heaps, W. S.

    2011-01-01

    Progress on the development of a differential radiometer based upon the Fabry-Perot interferometer (FPI) for methane (CH4) and carbon dioxide (C02) detection in the atmosphere is presented. Methane measurements are becoming increasingly important as a component of NASA's programs to understand the global carbon cycle and quantifY the threat of global warming. Methane is the third most important greenhouse gas in the Earth's radiation budget (after water vapor and carbon dioxide) and the second most important anthropogenic contributor to global warming. The importance of global warming and air quality to society caused the National Research Council to recommend that NASA develop the following missions [1]: ASCENDS (Active Sensing of C02 Emissions over Nights, Days, and Seasons), GEOCAPE (Geostationary Coastal and Air Pollution Events), and GACM (Global Atmosphere Composition Mission). Though methane measurements are not specifically called out in these missions, ongoing environmental changes have raised the importance of understanding the methane budget. In the decadal survey is stated that "to close the carbon budget, we would also address methane, but the required technology is not obvious at this time. If appropriate and cost-effective methane technology becomes available, we strongly recommend adding a methane capability". In its 2007 report the International Panel on Climate Change identified methane as a key uncertainty in our understanding saying that the causes of recent changes in the growth rate of atmospheric CH4 are not well understood. What we do know is that methane arises from a number of natural sources including wet lands and the oceans plus man made sources from agriculture, as well as coal and petroleum production and distribution. It has recently been pointed out that large amount of methane are frozen in the permafrost of Canada and Siberia. There is a fear that melting of this permafrost driven by global warming may release large amounts of

  7. Acetogens and Acetoclastic Methanosarcinales Govern Methane Formation in Abandoned Coal Mines▿

    Science.gov (United States)

    Beckmann, Sabrina; Lueders, Tillmann; Krüger, Martin; von Netzer, Frederick; Engelen, Bert; Cypionka, Heribert

    2011-01-01

    In abandoned coal mines, methanogenic archaea are responsible for the production of substantial amounts of methane. The present study aimed to directly unravel the active methanogens mediating methane release as well as active bacteria potentially involved in the trophic network. Therefore, the stable-isotope-labeled precursors of methane, [13C]acetate and H2-13CO2, were fed to liquid cultures from hard coal and mine timber from a coal mine in Germany. Guided by methane production rates, samples for DNA stable-isotope probing (SIP) with subsequent quantitative PCR and denaturing gradient gel electrophoretic (DGGE) analyses were taken over 6 months. Surprisingly, the formation of [13C]methane was linked to acetoclastic methanogenesis in both the [13C]acetate- and the H2-13CO2-amended cultures of coal and timber. H2-13CO2 was used mainly by acetogens related to Pelobacter acetylenicus and Clostridium species. Active methanogens, closely affiliated with Methanosarcina barkeri, utilized the readily available acetate rather than the thermodynamically more favorable hydrogen. Thus, the methanogenic microbial community appears to be highly adapted to the low-H2 conditions found in coal mines. PMID:21460109

  8. Acetogens and acetoclastic methanosarcinales govern methane formation in abandoned coal mines.

    Science.gov (United States)

    Beckmann, Sabrina; Lueders, Tillmann; Krüger, Martin; von Netzer, Frederick; Engelen, Bert; Cypionka, Heribert

    2011-06-01

    In abandoned coal mines, methanogenic archaea are responsible for the production of substantial amounts of methane. The present study aimed to directly unravel the active methanogens mediating methane release as well as active bacteria potentially involved in the trophic network. Therefore, the stable-isotope-labeled precursors of methane, [(13)C]acetate and H(2)-(13)CO(2), were fed to liquid cultures from hard coal and mine timber from a coal mine in Germany. Guided by methane production rates, samples for DNA stable-isotope probing (SIP) with subsequent quantitative PCR and denaturing gradient gel electrophoretic (DGGE) analyses were taken over 6 months. Surprisingly, the formation of [(13)C]methane was linked to acetoclastic methanogenesis in both the [(13)C]acetate- and the H(2)-(13)CO(2)-amended cultures of coal and timber. H(2)-(13)CO(2) was used mainly by acetogens related to Pelobacter acetylenicus and Clostridium species. Active methanogens, closely affiliated with Methanosarcina barkeri, utilized the readily available acetate rather than the thermodynamically more favorable hydrogen. Thus, the methanogenic microbial community appears to be highly adapted to the low-H(2) conditions found in coal mines.

  9. Methane in shallow cold seeps at Mocha Island off central Chile

    Science.gov (United States)

    Jessen, Gerdhard L.; Pantoja, Silvio; Gutiérrez, Marcelo A.; Quiñones, Renato A.; González, Rodrigo R.; Sellanes, Javier; Kellermann, Matthias Y.; Hinrichs, Kai-Uwe

    2011-04-01

    We studied for the first time the intertidal and subtidal gas seepage system in Mocha Island off Central Chile. Four main seepage sites were investigated (of which one site included about 150 bubbling points) that release from 150 to 240 tonnes CH 4 into the atmosphere per year. The total amount of methane emitted into the atmosphere is estimated in the order of 800 tonnes per year. The gases emanated from the seeps contain 70% methane, and the stable carbon isotopic composition of methane, δ 13C-CH 4 averaged -44.4±1.4‰ which indicates a major contribution of thermogenic gas. Adjacent to one of the subtidal seeps, rocky substrates support a diverse community of microbial filaments, macroalgae, and benthic organisms. While stable carbon isotopic compositions of marine benthic organisms indicate a dominant photosynthesis-based food web, those of some hard-substrate invertebrates were in the range -48.8‰ to -36.8‰, suggesting assimilation of methane-derived carbon by some selected taxa. This work highlights the potential subsidy of the trophic web by CH 4-C, and that its emission to the atmosphere justifies the need of evaluating the use of methane to support the energy requirements of the local community.

  10. Methane emissions proportional to permafrost carbon thawed in Arctic lakes since the 1950s

    Science.gov (United States)

    Walter Anthony, Katey; Daanen, Ronald; Anthony, Peter; Schneider von Deimling, Thomas; Ping, Chien-Lu; Chanton, Jeffrey P.; Grosse, Guido

    2016-09-01

    Permafrost thaw exposes previously frozen soil organic matter to microbial decomposition. This process generates methane and carbon dioxide, and thereby fuels a positive feedback process that leads to further warming and thaw. Despite widespread permafrost degradation during the past ~40 years, the degree to which permafrost thaw may be contributing to a feedback between warming and thaw in recent decades is not well understood. Radiocarbon evidence of modern emissions of ancient permafrost carbon is also sparse. Here we combine radiocarbon dating of lake bubble trace-gas methane (113 measurements) and soil organic carbon (289 measurements) for lakes in Alaska, Canada, Sweden and Siberia with numerical modelling of thaw and remote sensing of thermokarst shore expansion. Methane emissions from thermokarst areas of lakes that have expanded over the past 60 years were directly proportional to the mass of soil carbon inputs to the lakes from the erosion of thawing permafrost. Radiocarbon dating indicates that methane age from lakes is nearly identical to the age of permafrost soil carbon thawing around them. Based on this evidence of landscape-scale permafrost carbon feedback, we estimate that 0.2 to 2.5 Pg permafrost carbon was released as methane and carbon dioxide in thermokarst expansion zones of pan-Arctic lakes during the past 60 years.

  11. Nonequilibrium clumped isotope signals in microbial methane

    Science.gov (United States)

    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

    2015-01-01

    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, e.g., 13CH3D, has recently emerged as a proxy for determining methane-formation temperatures; however, the impact 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 13CH3D 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.

  12. On getter action of tungsten for methane

    Energy Technology Data Exchange (ETDEWEB)

    Kyoh, Bunkei; Uchida, Kumao (Kinki Univ., Higashi-Osaka, Osaka (Japan). Faculty of Science and Technology); Imoto, Shosuke

    1990-07-01

    The tungsten filament was electrically heated in methane atmosphere, and its getter action for methane has been investigated. The rapid adsorption of methane occurred during gettering at methane pressures between 10{sup -3} and 10{sup -5} Pa. When compared to the absorbed amount at higher temperature (above 200degC) was about 1/10 smaller than at room temperature. Desorption of methane from W getter film was hardly observed, but hydrogen was desorbed and the amount increased with temperature. About 16% carbon was found in the W film after gettering, of which the crystal structure differed according to the substrate ({beta}-W on glass sub., {alpha}-W on W sub.). (author).

  13. Decarbonisation of fossil energy via methane pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Kreysa, G.; Agar, D.W.; Schultz, I. [Technische Univ. Dortmund (Germany)

    2010-12-30

    Despite the rising consumption of energy over the last few decades, the proven reserves of fossil fuels have steadily increased. Additionally, there are potentially tremendous reserves of methane hydrates available, which remain to be exploited. The use of fossil energy sources is thus increasingly being dictated less by supply than by the environmental concerns raised by climate change. In the context of the decarbonisation of the global energy system that this has stimulated, new means must be explored for using methane as energy source. Noncatalytic thermal pyrolysis of methane is proposed here as a promising concept for utilising methane with low to zero carbon dioxide emissions. Following cracking, only the energy content of the hydrogen is used, while the carbon can be stored safely and retrievably in disused coal mines. The thermodynamics and different process engineering concepts for the technical realisation of such a carbon moratorium technology are discussed. The possible contribution of methane pyrolysis to carbon negative geoengineering is also addressed. (orig.)

  14. Atmospheric Impact of Large Methane Emissions and the Gulf Oil Spill

    Science.gov (United States)

    Bhattacharyya, S.; Cameron-Smith, P. J.; Bergmann, D. J.

    2010-12-01

    A vast quantity of a highly potent greenhouse gas, methane, is locked in the solid phase as methane clathrates in ocean sediments and underneath permafrost regions. Clathrates are ice-like deposits containing a mixture of water and gas (mostly methane) which are stable under high pressure and low temperatures. Current estimates are about 1600 - 2000 GtC present in oceans and about 400GtC in Arctic permafrost (Archer et al. 2009). This is about 4000 times that of current annual emissions. In a warming climate, increase in ocean temperatures could rapidly destabilize the geothermal gradient which in turn could lead to dissociation of the clathrates and release of methane into the ocean and subsequently into the atmosphere as well. This could result in a number of effects including strong greenhouse heating, increased surface ozone, reduced stratospheric ozone, and intensification of the Arctic ozone hole. Many of the effects in the chemistry of the atmosphere are non-linear. In this paper, we present a parametric study of the effect of large scale methane release to the atmosphere. To that end we use the CESM (Community Earth System Model) version 1 with fully active coupled atmosphere-ocean-land model together with super-fast atmospheric chemistry module to simulate the response to increasing CH4 by 2, 3, 10 and 100 times that of the present day. We have also conducted a parametric study of the possible impact of gaseous emissions from the oil spill in the Gulf of Mexico, which is a proxy for future clathrate releases. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  15. Gender differences in first episode psychosis

    DEFF Research Database (Denmark)

    Koster, A.; Lajer, M.; Lindhardt, A.

    2008-01-01

    In the description of 1 episode schizophrenia patients, female gender is associated with better social function and a higher degree of compliance, while males exhibit more negative symptoms and a higher degree of abuse. The question is raised whether gender specific differences exist which should...

  16. Mental health nursing and first episode psychosis

    NARCIS (Netherlands)

    Dusseldorp, L. van; Goossens, P.J.J.; Achterberg, T. van

    2011-01-01

    The purpose of this literature review is to identify mental health nursing's contribution to the care and treatment of patients with a first episode of psychosis; A systematic literature review was undertaken, with 27 articles selected for study. Five domains were identified: development of

  17. Predictors of recovery in first episode psychosis

    DEFF Research Database (Denmark)

    Austin, Stephen; Mors, Ole; Secher, Rikke Gry

    2013-01-01

    Recovery, the optimal goal in treatment, is the attainment of both symptomatic and functional remission over a sustained period of time. Identification of factors that promote recovery can help develop interventions that facilitate good outcomes for people with first episode psychosis....

  18. Attentional control and competition between episodic representations

    NARCIS (Netherlands)

    Akyürek, Elkan G.; Schubö, Anna; Hommel, Bernhard

    The relationship between attentional control and episodic representation was investigated in six experiments that employed a variant of the classic attentional blink paradigm. We introduced a task-irrelevant (unpredictive) color match between the first and second target stimulus in a three-stream

  19. How successful are first episode programs?

    DEFF Research Database (Denmark)

    Nordentoft, Merete; Rasmussen, Jesper Østrup; Melau, Marianne

    2014-01-01

    PURPOSE OF REVIEW: It has been hypothesized that the first 5 years after first episode of psychosis are a critical period with opportunities for ameliorating the course of illness. On the basis of this rationale, specialized assertive early intervention services were developed. We wanted to inves...

  20. A calendar savant with episodic memory impairments.

    Science.gov (United States)

    Olson, Ingrid R; Berryhill, Marian E; Drowos, David B; Brown, Lawrence; Chatterjee, Anjan

    2010-06-01

    Patients with memory disorders have severely restricted learning and memory. For instance, patients with anterograde amnesia can learn motor procedures and retain some restricted ability to learn new words and factual information. However, such learning is inflexible and frequently inaccessible to conscious awareness. Here we present a case of patient AC596, a 25-year-old male with severe episodic memory impairments, presumably due to anoxia during a preterm birth. In contrast to his poor episodic memory, he exhibits savant-like memory for calendar information that can be flexibly accessed by day, month, and year cues. He also has the ability to recollect the exact date of a wide range of personal experiences over the past 20 years. The patient appears to supplement his generally poor episodic memory by using memorized calendar information as a retrieval cue for autobiographical events. These findings indicate that islands of preserved memory functioning, such as a highly developed semantic memory system, can exist in individuals with severely impaired episodic memory systems. In this particular case, our patient's memory for dates far outstripped that of normal individuals and served as a keen retrieval cue, allowing him to access information that was otherwise unavailable.

  1. Acute disseminated encephalomyelitis presenting as depressive episode

    Science.gov (United States)

    Krishnakumar, P.; Jayakrishnan, M. P.; Devarajan, E.

    2011-01-01

    A 9-year-old girl presented to the Child Guidance Clinic with clinical features suggestive of depressive episode of 1 week duration. There was history of short febrile illness 3 weeks prior to the onset of the depressive symptoms. MRI scan of brain showed features of acute disseminated encephalomyelitis. PMID:22303048

  2. The hypothalamus in episodic brain disorders

    NARCIS (Netherlands)

    Overeem, Sebastiaan; van Vliet, Jorine A.; Lammers, Gert J.; Zitman, Frans G.; Swaab, Dick F.; Ferrari, Michel D.

    2002-01-01

    Episodic brain disorders (EBD) form an intriguing group of neurological diseases in which at least some of the symptoms occur in attacks. The hypothalamus integrates many brain functions, including endocrine and autonomic control, and governs various body rhythms. It seems a likely site in which the

  3. Autobiographical thinking interferes with episodic memory consolidation.

    Directory of Open Access Journals (Sweden)

    Michael Craig

    Full Text Available New episodic memories are retained better if learning is followed by a few minutes of wakeful rest than by the encoding of novel external information. Novel encoding is said to interfere with the consolidation of recently acquired episodic memories. Here we report four experiments in which we examined whether autobiographical thinking, i.e. an 'internal' memory activity, also interferes with episodic memory consolidation. Participants were presented with three wordlists consisting of common nouns; one list was followed by wakeful rest, one by novel picture encoding and one by autobiographical retrieval/future imagination, cued by concrete sounds. Both novel encoding and autobiographical retrieval/future imagination lowered wordlist retention significantly. Follow-up experiments demonstrated that the interference by our cued autobiographical retrieval/future imagination delay condition could not be accounted for by the sound cues alone or by executive retrieval processes. Moreover, our results demonstrated evidence of a temporal gradient of interference across experiments. Thus, we propose that rich autobiographical retrieval/future imagination hampers the consolidation of recently acquired episodic memories and that such interference is particularly likely in the presence of external concrete cues.

  4. Biochemically enhanced methane production from coal

    Science.gov (United States)

    Opara, Aleksandra

    For many years, biogas was connected mostly with the organic matter decomposition in shallow sediments (e.g., wetlands, landfill gas, etc.). Recently, it has been realized that biogenic methane production is ongoing in many hydrocarbon reservoirs. This research examined microbial methane and carbon dioxide generation from coal. As original contributions methane production from various coal materials was examined in classical and electro-biochemical bench-scale reactors using unique, developed facultative microbial consortia that generate methane under anaerobic conditions. Facultative methanogenic populations are important as all known methanogens are strict anaerobes and their application outside laboratory would be problematic. Additional testing examined the influence of environmental conditions, such as pH, salinity, and nutrient amendments on methane and carbon dioxide generation. In 44-day ex-situ bench-scale batch bioreactor tests, up to 300,000 and 250,000 ppm methane was generated from bituminous coal and bituminous coal waste respectively, a significant improvement over 20-40 ppm methane generated from control samples. Chemical degradation of complex hydrocarbons using environmentally benign reagents, prior to microbial biodegradation and methanogenesis, resulted in dissolution of up to 5% bituminous coal and bituminous coal waste and up to 25% lignite in samples tested. Research results confirm that coal waste may be a significant underutilized resource that could be converted to useful fuel. Rapid acidification of lignite samples resulted in low pH (below 4.0), regardless of chemical pretreatment applied, and did not generate significant methane amounts. These results confirmed the importance of monitoring and adjusting in situ and ex situ environmental conditions during methane production. A patented Electro-Biochemical Reactor technology was used to supply electrons and electron acceptor environments, but appeared to influence methane generation in a

  5. Methane measurements manual; Handbok metanmaetningar

    Energy Technology Data Exchange (ETDEWEB)

    Holmgren, Magnus Andreas (SP Technical research institute of Sweden, Boraas (Sweden))

    2011-02-15

    Emissions to air in different parts of the system may arise in biogas plants, where there is biological treatment of organic matter by anaerobic degradation, and during upgrading of biogas to vehicle fuel. There are mainly four reasons why these emissions must be minimized. These are safety, greenhouse gas emissions, economy and smell. This manual gathers experience of several years of work with measurement of methane emissions from biogas and upgrading facilities. This work has been done mainly in the context of Swedish Waste Management's system of voluntary commitment. The purpose of this manual is to standardize methods and procedures when methane measurements are carried out so that the results are comparable between different providers. The main target group of the manual is measurement consultants performing such measurements. Calculation template in Excel is part of the manual, which further contributes to the measurements evaluated in a standardized way. The manual contains several examples which have been calculated in the accompanying Excel template. The handbook also contains a chapter mainly intended for facility staff, in which implementation of accurate leak detection is described, and where there are hints of a system of so-called intermediate inspections to detect leaks in time

  6. The direct aromatization of methane

    Energy Technology Data Exchange (ETDEWEB)

    Marcelin, G.; Oukaci, R.; Migone, R.A.; Kazi, A.M. [Altamira Instruments, Pittsburgh, PA (United States)

    1995-12-31

    The thermal decomposition of methane shows significant potential as a process for the production of higher unsaturated and aromatic hydrocarbons when the extent of the reaction is limited. Thermodynamic calculations have shown that when the reaction is limited to the formation of C{sub 2} to C{sub 10} products, yields of aromatics can exceed 40% at temperatures of 1200{degrees}C. Preliminary experiments have shown that when the reaction is limited to the formation of C{sub 2} to C{sub 10} products, yields of aromatics can exceed 40% at temperatures of 1200{degrees}C. Preliminary experiments have shown that cooling the product and reacting gases as the reaction proceeds can significantly reduce or eliminate the formation of solid carbon and heavier (C{sub 10+}) materials. Much work remains to be done in optimizing the quenching process and this is one of the goals of this program. Means to lower the temperature of the reaction are being studied as this result in a more feasible commercial process due to savings realized in energy and material of construction costs. The use of free-radical generators and catalysts will be investigated as a means of lowering the reaction temperature thus allowing faster quenching. It is highly likely that such studies will lead to a successful direct methane to higher hydrocarbon process.

  7. Methane Bubble Size Distributions, Flux, and Dissolution in a Freshwater Lake.

    Science.gov (United States)

    Delwiche, Kyle B; Hemond, Harold F

    2017-12-05

    The majority of methane produced in many anoxic sediments is released via ebullition. These bubbles are subject to dissolution as they rise, and dissolution rates are strongly influenced by bubble size. Current understanding of natural methane bubble size distributions is limited by the difficulty in measuring bubble sizes over wide spatial or temporal scales. Our custom optical bubble size sensors recorded bubble sizes and release timing at 8 locations in Upper Mystic Lake, MA continuously for 3 months. Bubble size distributions were spatially heterogeneous even over relatively small areas experiencing similar flux, suggesting that localized sediment conditions are important to controlling bubble size. There was no change in bubble size distributions over the 3 month sampling period, but mean bubble size was positively correlated with daily ebullition flux. Bubble data was used to verify the performance of a widely used bubble dissolution model, and the model was then used to estimate that bubble dissolution accounts for approximately 10% of methane accumulated in the hypolimnion during summer stratification, and at most 15% of the diffusive air-water-methane flux from the epilimnion.

  8. A new tracer experiment to estimate the methane emissions from a dairy cow shed using sulfur hexafluoride (SF6)

    Science.gov (United States)

    Marik, Thomas; Levin, Ingeborg

    1996-09-01

    Methane emission from livestock and agricultural wastes contribute globally more than 30% to the anthropogenic atmospheric methane source. Estimates of this number have been derived from respiration chamber experiments. We determined methane emission rates from a tracer experiment in a modern cow shed hosting 43 dairy cows in their accustomed environment. During a 24-hour period the concentrations of CH4, CO2, and SF6, a trace gas which has been released at a constant rate into the stable air, have been measured. The ratio between SF6 release rate and measured SF6 concentration was then used to estimate the ventilation rate of the stable air during the course of the experiment. The respective ratio between CH4 or CO2 and SF6 concentration together with the known SF6 release rate allows us to calculate the CH4 (and CO2) emissions in the stable. From our experiment we derive a total daily mean CH4 emission of 441 LSTP per cow (9 cows nonlactating), which is about 15% higher than previous estimates for German cows with comparable milk production obtained during respiration chamber experiments. The higher emission in our stable experiment is attributed to the contribution of CH4 release from about 50 m3 of liquid manure present in the cow shed in underground channels. Also, considering measurements we made directly on a liquid manure tank, we obtained an estimate of the total CH4 production from manure: The normalized contribution of methane from manure amounts to 12-30% of the direct methane release of a dairy cow during rumination. The total CH4 release per dairy cow, including manure, is 521-530 LSTP CH4 per day.

  9. Generating life episodes for the purpose of testing of episodic memory models

    OpenAIRE

    Běhan, Zdeněk

    2012-01-01

    The goal of this work is to create a generator that provides a corpora of input episodes in the specified format, which can be used as an input to test episodic memory models. More specifically, the methods used should ensure the scope to be in years up to a possible lifetime of a typical human agent. It also attempts to verify this on an actual episodic memory model, and test if the generated data has high enough quality to be used for testing psychological paradigms on memory models.

  10. Pharmacological and clinical aspects of immediate release fentanyl preparations: Criteria for selection

    NARCIS (Netherlands)

    D.A. van der Kuip (Deirdre); C.Th. Zandvliet; A.H.J. Mathijssen (Ron); C.C.D. van der Rijt (Carin)

    2012-01-01

    textabstractIn palliative care, pain management is often hampered by episodes of breakthrough pain, characterised by a rapid onset and, on average, duration less than 1 h. Until recently, only immediate release morphine and oxycodon preparations were available for the treatment of these episodes but

  11. Dissociation of Laboratory-Synthesized Methane Hydrate in Coarse-Grained Sediments by Slow Depressurization

    Science.gov (United States)

    Phillips, S. C.; You, K.; Borgfeldt, T.; Meyer, D.; Dong, T.; Flemings, P. B.

    2016-12-01

    We performed four dissociation experiments in which experimentally-formed methane hydrate was dissociated via slow, stepwise depressurization, revealing in situ salinity conditions. Overall, these results suggest the occurrence of local pore water freshening around dissociating hydrate in which bulk equilibrium behavior is limited by salt diffusion. Depressurization was performed at a constant confining temperature over 1 to 3 weeks by releasing small volumes of methane gas from the top of a vertically-oriented sample into an inverted graduated cylinder. We identify three distinct regimes of depressurization based on pressure drop behavior: (1) release of free gas down to initial hydrate dissociation at 3.3 MPa in NaBr or 4.64 MPa in NaCl, (2) dissociation of methane hydrate characterized by a slow, logarithmic increase in pressure after each gas release and (3) residual free gas release. Initial hydrate dissociation in NaCl brine at 4.64 MPa corresponds to the phase boundary for hydrate in 9.6 wt% NaCl. In the NaCl experiment, pressure increases of 0.16 MPa while the sample was shut in over 3 days likely correspond to a recovery in salinity of 0.7 wt. %. Salt ions likely diffuse from brine ahead of the hydrate front, based on a length scale for diffusion of NaCl of 6.3 cm for 3 days. In this experiment dissociation at bulk equilibrium is expected to decline from 4.54 to 4.04 MPa; however actual dissociation during 73 gas releases over 15 days, results in a pressure drop from 4.64 to 3.25 MPa. Hydrate samples were formed by injection of methane gas at 1 ºC and 12.24 MPa within a cylinder packed with medium-grained quartz sand and initially saturated in a 7 wt% NaBr or NaCl solution. In two experiments in which the system was thoroughly leak tested, total methane consumed during formation and recovered during depressurization match within 7% indicating this approach to be relatively accurate for determining total methane in experimental or pressure core samples.

  12. Determining the flux of methane into Hudson Canyon at the edge of methane clathrate hydrate stability

    Science.gov (United States)

    Weinsten, A.; Navarrete, L; Ruppel, Carolyn D.; Weber, T.C.; Leonte, M.; Kellermann, M.; Arrington, E.; Valentine, D.L.; Scranton, M.L; Kessler, John D.

    2016-01-01

    Methane seeps were investigated in Hudson Canyon, the largest shelf-break canyon on the northern US Atlantic Margin. The seeps investigated are located at or updip of the nominal limit of methane clathrate hydrate stability. The acoustic identification of bubble streams was used to guide water column sampling in a 32 km2 region within the canyon's thalweg. By incorporating measurements of dissolved methane concentration with methane oxidation rates and current velocity into a steady-state box model, the total emission of methane to the water column in this region was estimated to be 12 kmol methane per day (range: 6 – 24 kmol methane per day). These analyses suggest this methane is largely retained inside the canyon walls below 300 m water depth, and that it is aerobically oxidized to near completion within the larger extent of Hudson Canyon. Based on estimated methane emissions and measured oxidation rates, the oxidation of this methane to dissolved CO2 is expected to have minimal influences on seawater pH. This article is protected by copyright. All rights reserved.

  13. 30 CFR 75.1324 - Methane concentration and tests.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Methane concentration and tests. 75.1324... Methane concentration and tests. (a) No shot shall be fired in an area that contains 1.0 volume percent or more of methane. (b) Immediately before shots are fired, the methane concentration in a working place...

  14. 30 CFR 75.323 - Actions for excessive methane.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Actions for excessive methane. 75.323 Section... excessive methane. (a) Location of tests. Tests for methane concentrations under this section shall be made.... (1) When 1.0 percent or more methane is present in a working place or an intake air course, including...

  15. Optical parametric technology for methane measurements

    Science.gov (United States)

    Dawsey, Martha; Numata, Kenji; Wu, Stewart; Riris, Haris

    2015-09-01

    Atmospheric methane (CH4) is the second most important anthropogenic greenhouse gas, with approximately 25 times the radiative forcing of carbon dioxide (CO2) per molecule. Yet, lack of understanding of the processes that control CH4 sources and sinks and its potential release from stored carbon reservoirs contributes significant uncertainty to our knowledge of the interaction between carbon cycle and climate change. At Goddard Space Flight Center (GSFC) we have been developing the technology needed to remotely measure CH4 from orbit. Our concept for a CH4 lidar is a nadir viewing instrument that uses the strong laser echoes from the Earth's surface to measure CH4. The instrument uses a tunable, narrow-frequency light source and photon-sensitive detector to make continuous measurements from orbit, in sunlight and darkness, at all latitudes and can be relatively immune to errors introduced by scattering from clouds and aerosols. Our measurement technique uses Integrated Path Differential Absorption (IPDA), which measures the absorption of laser pulses by a trace gas when tuned to a wavelength coincident with an absorption line. We have already demonstrated ground-based and airborne CH4 detection using Optical Parametric Amplifiers (OPA) at 1651 nm using a laser with approximately 10 μJ/pulse at 5kHz with a narrow linewidth. Next, we will upgrade our OPO system to add several more wavelengths in preparation for our September 2015 airborne campaign, and expect that these upgrades will enable CH4 measurements with 1% precision (10-20 ppb).

  16. Optical Parametric Technology for Methane Measurements

    Science.gov (United States)

    Dawsey, Martha; Numata, Kenji; Wu, Stewart; Riris, Haris

    2015-01-01

    Atmospheric methane (CH4) is the second most important anthropogenic greenhouse gas, with approximately 25 times the radiative forcing of carbon dioxide (CO2) per molecule. Yet, lack of understanding of the processes that control CH4 sources and sinks and its potential release from stored carbon reservoirs contributes significant uncertainty to our knowledge of the interaction between carbon cycle and climate change. At Goddard Space Flight Center (GSFC) we have been developing the technology needed to remotely measure CH4 from orbit. Our concept for a CH4 lidar is a nadir viewing instrument that uses the strong laser echoes from the Earth's surface to measure CH4. The instrument uses a tunable, narrow-frequency light source and photon-sensitive detector to make continuous measurements from orbit, in sunlight and darkness, at all latitudes and can be relatively immune to errors introduced by scattering from clouds and aerosols. Our measurement technique uses Integrated Path Differential Absorption (IPDA), which measures the absorption of laser pulses by a trace gas when tuned to a wavelength coincident with an absorption line. We have already demonstrated ground-based and airborne CH4 detection using Optical Parametric Amplifiers (OPA) at 1651 nm using a laser with approximately 10 microJ/pulse at 5kHz with a narrow linewidth. Next, we will upgrade our OPO system to add several more wavelengths in preparation for our September 2015 airborne campaign, and expect that these upgrades will enable CH4 measurements with 1% precision (10-20 ppb).

  17. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Bill Liddell

    2005-03-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Oil-field engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in Arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrates agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is a cost-shared partnership between Maurer Technology, Anadarko Petroleum, Noble Corporation, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to help identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. As part of the project work scope, team members drilled and cored the HOT ICE No. 1 on Anadarko leases beginning in January 2003 and completed in March 2004. Due to scheduling constraints imposed by the Arctic drilling season, operations at the site were suspended between April 21, 2003 and January 30, 2004. An on-site core analysis laboratory was designed, constructed and used for determining physical characteristics of frozen core immediately after it was retrieved from the well. The well was drilled from a new and innovative Anadarko Arctic Platform that has a greatly reduced footprint and environmental impact. Final efforts of the project were to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists for future hydrate operations. Unfortunately, no gas hydrates were encountered in this well; however, a wealth of information was generated

  18. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Buddy King

    2004-06-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is in the final stages of a cost shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. The work scope drilled and cored a well The HOT ICE No.1 on Anadarko leases beginning in FY 2003 and completed in 2004. An on-site core analysis laboratory was built and utilized for determining the physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. The final efforts of the project are to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists developing reservoir models. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained in this report.

  19. Wetland distribution assumptions: consequences for Methane emissions

    Science.gov (United States)

    Kleinen, Thomas; Brovkin, Victor

    2017-04-01

    Wetlands are the largest natural source of methane to the atmosphere. While process models of wetland methane emissions have advanced considerably in recent years, all of these models critically depend on estimates of the methane-emitting area. These estimates are highly uncertain, however. We investigate several approaches for estimating the wetland area and the consequences these assumptions have for the spatial and temporal distributions of wetland methane emissions. For this investigation we use JSBACH, the land surface component of the Max Planck Institute Earth System Model MPI-ESM, extended with modules for the generation and soil transport of methane. We drive the model with an ensemble of simulations of climate over the historical period from the MPI-ESM CMIP5 archive, as well as observed climate from CRU-NCEP. We impose both static and dynamic wetland maps, as well as modelled wetland distributions, and determine the wetland methane emissions resulting from these estimates. Results are compared to methane fluxes from atmospheric inversions to evaluate the consequences of the assumptions on wetland area.

  20. Application of a methane carbon isotope analyzer for the investigation of δ13C of methane emission measured by the automatic chamber method in an Arctic Tundra

    Science.gov (United States)

    Mastepanov, Mikhail; Christensen, Torben

    2014-05-01

    Methane emissions have been monitored by an automatic chamber method in Zackenberg valley, NE Greenland, since 2006 as a part of Greenland Ecosystem Monitoring (GEM) program. During most of the seasons the measurements were carried out from the time of snow melt (June-July) until freezing of the active layer (October-November). Several years of data, obtained by the same method, instrumentation and at exactly the same site, provided a unique opportunity for the analysis of interannual methane flux patterns and factors affecting their temporal variability. The start of the growing season emissions was found to be closely related to a date of snow melt at the site. Despite a large between year variability of this date (sometimes more than a month), methane emission started within a few days after, and was increasing for the next about 30 days. After this peak of emission, it slowly decreased and stayed more or less constant or slightly decreasing during the rest of the growing season (Mastepanov et al., Biogeosciences, 2013). During the soil freezing, a second peak of methane emission was found (Mastepanov et al., Nature, 2008); its amplitude varied a lot between the years, from almost undetectable to comparable with total growing season emissions. Analysis of the multiyear emission patterns (Mastepanov et al., Biogeosciences, 2013) led to hypotheses of different sources for the spring, summer and autumn methane emissions, and multiyear cycles of accumulation and release of these components to the atmosphere. For the further investigation of this it was decided to complement the monitoring system with a methane carbon isotope analyzer (Los Gatos Research, USA). The instrument was installed during 2013 field season and was successfully operating until the end of the measurement campaign (27 October). Detecting both 12C-CH4 and 13C-CH4 concentrations in real time (0.5 Hz) during automatic chamber closure (15 min), the instrument was providing data for determination of

  1. Effect of converting wetland forest to sago palm plantations on methane gas flux and organic carbon dynamics in tropical peat soil

    Science.gov (United States)

    Inubushi, K.; Hadi, A.; Okazaki, M.; Yonebayashi, K.

    1998-10-01

    The effect of changing wetland forest to sago palm plantations on methane gas flux and organic carbon dynamics in tropical peat soil was studied in the field and the laboratory using soil samples from the Peat Research Station, Sarawak, Malaysia. A small amount of methane was released from the soil surface of both the forest and plantation field, with no significant difference between the two sites (1·1+/-0·61 and 1·39+/-0·82 mg CH4 m-2 hr-1, respectively); thus, the amount of methane emission from the total area of tropical peat soil was estimated, preliminarily, as 2·43 Tg yr-1, contributing 0·45% of the total global methane emission and 2·1% of methane emissions from global natural wetland. However, large amounts of methane were accumulated in the deeper soil layers. Sago palm contained much less carbon as biomass, but lost more as the carbon dissolved in groundwater. Laboratory experiments showed that incorporation of rice straw into tropical peat soil increased methane formation significantly. Conversely, ammonium sulfate suppressed methane formation in tropical peat soil.

  2. Mars Methane highs unrelated to comets

    Science.gov (United States)

    Roos-Serote, Maarten; Atreya, Sushil K.; Webster, Chris; Mahaffy, Paul

    2016-10-01

    Until the Curiosity Rover arrived at Mars, all measurements of methane were done by remote sensing, either from Earth or from orbiting spacecraft, using a variety of different instruments and under different observing conditions. The Curiosity Rover's Sample Analysis at Mars (SAM) / Tunable Laser Spectrometer (TLS) has carried out systematic measurements of martian methane from Gale crater for two consecutive martian years (31 - 33, starting in October 2012). Meteoric material interacts with the martian atmosphere when Mars passes through a meteoroid stream left behind by cometary bodies orbiting the Sun. Predictions show that 33 such events are likely to occur during the martian year. It has been suggested that the organics present in this material trigger the formation of methane in the atmosphere, and thus these events could possibly be an explanation for the observed variations in the methane abundance. In a recent paper, Fries et al. [2016] argued that all measurements of high methane concentrations are within 16 days of a predicted meteor shower event, and that as such there is a correlation. We present a new analysis including seven new data points that were not available previously. All these new measurements show low methane values. Some of the new measurements were deliberately taken at the same Ls when high values of methane were measured in the previous martian year, showing that the high methane measurements are likely not seasonal, as would be expected if they were connected to meteor shower events. In our analysis we take into account all the predicted meteor events and search for any correlation drawn between these events and the level of methane in the atmosphere. We conclude that whether we consider individual data points, apply statistical analysis, or consider different time spans between measurements and the occurrence of meteor events, or possible supply of organic material from comets, there is no evidence for such a correlation in the

  3. Coal industry leaders meet to discuss methane issues

    Energy Technology Data Exchange (ETDEWEB)

    Yernberg, W.R.

    2000-07-01

    This paper summarizes the conference on coalbed and coal mine methane which was held in March 2000 in Denver, USA. The conference focussed on the recovery of methane from coal beds as an energy resource and removal and utilization of coal-mine methane (CMM) related to underground coal mining. The conference discussed methane resources around the world, methods of recovery, methane markets, underground coal mining, health and safety issues and environmental issues related to methane. The consensus among the presenters is that the future looks promising for coalbed methane (CBM) and CMM. 1 fig., 1 tab.

  4. Relationship between residual feed intake and daily methane emission in young Nellore bulls

    OpenAIRE

    Ana Paula Melo Caliman; Elaine Magnani; Alexandre Berndt; Rosa Toyoko Shiraishi Frighetto; Renata Helena Branco; Maria Eugênia Zerlotti Mercadante

    2012-01-01

    The cattle production is a sector of agricultural activity that has impact on global warming due to enteric fermentation from digestive process that releases methane (CH4), with energy loss of food and consequent inefficiency of system. Residual feed intake (RFI) is a feed efficiency trait defined as the difference between actual feed intake and the one predicted on the basis of requirements for body weight production and maintenance. There are evidences that more efficient cattle (low RFI) h...

  5. Tapping methane hydrates for unconventional natural gas

    Science.gov (United States)

    Ruppel, Carolyn

    2007-01-01

    Methane hydrate is an icelike form of concentrated methane and water found in the sediments of permafrost regions and marine continental margins at depths far shallower than conventional oil and gas. Despite their relative accessibility and widespread occurrence, methane hydrates have never been tapped to meet increasing global energy demands. With rising natural gas prices, production from these unconventional gas deposits is becoming economically viable, particularly in permafrost areas already being exploited for conventional oil and gas. This article provides an overview of gas hydrate occurrence, resource assessment, exploration, production technologies, renewability, and future challenges.

  6. Whatever happened to coalbed methane?

    Energy Technology Data Exchange (ETDEWEB)

    Stastny, R.P.

    2011-10-15

    Coalbed methane is natural gas from coal (NGC). The term preferred by the industry is CBM. in 2006 about 95% of CBM wells at that time were located at Horseshoe Canyon, where the local inhabitants were not informed of the operation. CBM is not a viable gas target compared to shale gas. The first reason is that the shale resource per well is superior to the CBM. Additionally, the capital and operating costs of CBM are difficult to reduce. The dewatering requirements are also a challenge. The low price of gas price at the time blocked further CBM operations. However, the CBM resource in Alberta would still be of interest to producers if the gas price were higher. Some top producers are still drilling CBM. In 2010, CBM accounted for 8% of Alberta's total marketable gas production. CBM is still a viable proposition as a gas target.

  7. Short-term landfill methane emissions dependency on wind.

    Science.gov (United States)

    Delkash, Madjid; Zhou, Bowen; Han, Byunghyun; Chow, Fotini K; Rella, Chris W; Imhoff, Paul T

    2016-09-01

    Short-term (2-10h) variations of whole-landfill methane emissions have been observed in recent field studies using the tracer dilution method for emissions measurement. To investigate the cause of these variations, the tracer dilution method is applied using 1-min emissions measurements at Sandtown Landfill (Delaware, USA) for a 2-h measurement period. An atmospheric dispersion model is developed for this field test site, which is the first application of such modeling to evaluate atmospheric effects on gas plume transport from landfills. The model is used to examine three possible causes of observed temporal emissions variability: temporal variability of surface wind speed affecting whole landfill emissions, spatial variability of emissions due to local wind speed variations, and misaligned tracer gas release and methane emissions locations. At this site, atmospheric modeling indicates that variation in tracer dilution method emissions measurements may be caused by whole-landfill emissions variation with wind speed. Field data collected over the time period of the atmospheric model simulations corroborate this result: methane emissions are correlated with wind speed on the landfill surface with R(2)=0.51 for data 2.5m above ground, or R(2)=0.55 using data 85m above ground, with emissions increasing by up to a factor of 2 for an approximately 30% increase in wind speed. Although the atmospheric modeling and field test are conducted at a single landfill, the results suggest that wind-induced emissions may affect tracer dilution method emissions measurements at other landfills. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. A human experimental model of episodic pain

    DEFF Research Database (Denmark)

    Petrini, Laura; Hennings, Kristian; Li, Xi

    2014-01-01

    were subjected to 45 min of intense painful cutaneous electrical stimulation (episodic pain session), using a stimulus paradigm that in animals has been shown to induce long-term potentiation. These electrical stimulations produced a verbal pain rating of approximately 85 on a 0-100 verbal rating scale......An experimental model of daily episodic pain was developed to investigate peripheral sensitization and cortical reorganization in healthy individuals. Two experiments (A and B) were conducted. Experiments A and B consisted of one and five consecutive days, respectively, in which the participants...... (VRS). Physiological (blood flow and axon flare reflex), psychophysical (perception threshold and verbal pain ratings) and electrophysiological (128 channels recorded somatosensory evoked potential (SEP)) measurements were recorded. The stimulation evoked a visible axon flare reflex and caused...

  9. Antipsychotic medication for early episode schizophrenia

    Science.gov (United States)

    Bola, John; Kao, Dennis; Soydan, Haluk; Adams, Clive E

    2014-01-01

    Background Long-term treatment with antipsychotic medications in early episode schizophrenia spectrum disorders is common, but both short and long-term effects on the illness are unclear. There have been numerous suggestions that people with early episodes of schizophrenia appear to respond differently than those with multiple prior episodes. The number of episodes may moderate response to drug treatment. Objectives To assess the effects of antipsychotic medication treatment on people with early episode schizophrenia spectrum disorders. Search methods We searched the Cochrane Schizophrenia Group register (July 2007) as well as references of included studies. We contacted authors of studies for further data. Selection criteria Studies with a majority of first and second episode schizophrenia spectrum disorders comparing initial antipsychotic medication treatment with placebo, milieu, or psychosocial treatment. Data collection and analysis Working independently, we critically appraised records from 681 studies, of which five studies met inclusion criteria. We calculated risk ratios (RR) and their 95% confidence intervals (CI) where possible. For continuous data, we calculated mean difference (MD). We calculated numbers needed to treat/harm (NNT/NNH) where appropriate. Main results Five studies (combined total n=998) met inclusion criteria. Four studies (n=724) provided leaving the study early data and results suggested that individuals treated with a typical antipsychotic medication are less likely to leave the study early than those treated with placebo (Chlorpromazine: 3 RCTs n=353, RR 0.4 CI 0.3 to 0.5, NNT 3.2, Fluphenaxine: 1 RCT n=240, RR 0.5 CI 0.3 to 0.8, NNT 5; Thioridazine: 1 RCT n=236, RR 0.44 CI 0.3 to 0.7, NNT 4.3, Trifulperazine: 1 RCT n=94, RR 0.96 CI 0.3 to 3.6). Two studies contributed data to assessment of adverse effects and present a general pattern of more frequent side effects among individuals treated with typical antipsychotic medications

  10. Executive function, episodic memory, and Medicare expenditures.

    Science.gov (United States)

    Bender, Alex C; Austin, Andrea M; Grodstein, Francine; Bynum, Julie P W

    2017-07-01

    We examined the relationship between health care expenditures and cognition, focusing on differences across cognitive systems defined by global cognition, executive function, or episodic memory. We used linear regression models to compare annual health expenditures by cognitive status in 8125 Nurses' Health Study participants who completed a cognitive battery and were enrolled in Medicare parts A and B. Adjusting for demographics and comorbidity, executive impairment was associated with higher total annual expenditures of $1488 per person (P memory impairment was found. Expenditures exhibited a linear relationship with executive function, but not episodic memory ($584 higher for every 1 standard deviation decrement in executive function; P losses in executive function may be effective in reducing costly services. Copyright © 2017 the Alzheimer's Association. Published by Elsevier Inc. All rights reserved.

  11. Methane emission from natural wetlands: interplay between emergent macrophytes and soil microbial processes. A mini-review.

    Science.gov (United States)

    Laanbroek, Hendrikus J

    2010-01-01

    According to the Intergovernmental Panel on Climate Change (IPCC) 2007, natural wetlands contribute 20-39 % to the global emission of methane. The range in the estimated percentage of the contribution of these systems to the total release of this greenhouse gas is large due to differences in the nature of the emitting vegetation including the soil microbiota that interfere with the production and consumption of methane. Methane is a dominant end-product of anaerobic mineralization processes. When all electron acceptors except carbon dioxide are used by the microbial community, methanogenesis is the ultimate pathway to mineralize organic carbon compounds. Emergent wetland plants play an important role in the emission of methane to the atmosphere. They produce the carbon necessary for the production of methane, but also facilitate the release of methane by the possession of a system of interconnected internal gas lacunas. Aquatic macrophytes are commonly adapted to oxygen-limited conditions as they prevail in flooded or waterlogged soils. By this system, oxygen is transported to the underground parts of the plants. Part of the oxygen transported downwards is released in the root zone, where it sustains a number of beneficial oxidation processes. Through the pores from which oxygen escapes from the plant into the root zone, methane can enter the plant aerenchyma system and subsequently be emitted into the atmosphere. Part of the oxygen released into the root zone can be used to oxidize methane before it enters the atmosphere. However, the oxygen can also be used to regenerate alternative electron acceptors. The continuous supply of alternative electron acceptors will diminish the role of methanogenesis in the anaerobic mineralization processes in the root zone and therefore repress the production and emission of methane. The role of alternative element cycles in the inhibition of methanogenesis is discussed. The role of the nitrogen cycle in repression of methane

  12. Inhibition of methane oxidation by Methylococcus capsulatus with hydrochlorofluorocarbons and fluorinated methanes

    Energy Technology Data Exchange (ETDEWEB)

    Matheson, L.J.; Oremland, R.S. [Geological Survey, Menlo Park, CA (United States); Jahnke, L.L. [NASA Ames Research Center, Moffett Field, CA (United States)

    1997-07-01

    Concerns about stratospheric ozone and global warming have focused some inquiries upon the microbial degradation of some atmospheric halocarbons. Little is known about the interaction of hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). This study examines possible interactions, including the inhibition of methane oxidation by chlorinated solvents, whether oxidation products formed may have inhibitory effects of their own, and whether other fluorinated methanes inhibit methane oxidation by whole cells. 33 refs., 4 figs., 1 tab.

  13. Aquatic herbivores facilitate the emission of methane from wetlands

    OpenAIRE

    Dingemans, B.J.J.; Bakker, E.S.; Bodelier, P.L.E.

    2011-01-01

    Wetlands are significant sources of atmospheric methane. Methane produced by microbes enters roots and escapes to the atmosphere through the shoots of emergent wetland plants. Herbivorous birds graze on helophytes, but their effect on methane emission remains unknown. We hypothesized that grazing on shoots of wetland plants can modulate methane emission from wetlands. Diffusive methane emission was monitored inside and outside bird exclosures, using static flux chambers placed over whole vege...

  14. Adult videogame consumption as individualised, episodic progress

    OpenAIRE

    Molesworth, Mike; Watkins, Rebecca

    2014-01-01

    Drawing from phenomenological interviews with 24 adult videogamers, we explore videogame consumption as a source of individualised, episodic progress. We first consider the relationship between play, progress, technology and the market. We then document adults’ accounts of progress through the acquisition of new consoles and software, in the accumulation of in-game resources, and in creative achievements within videogames. Alongside an understanding of technological improvements as representi...

  15. Paroxysmal movement disorders and episodic ataxias.

    Science.gov (United States)

    Fernández-Alvarez, Emilio; Perez-Dueñas, Belén

    2013-01-01

    This chapter summarizes clinical symptoms of some paroxysmal dyskinesias (PDs) of infancy and childhood, as well as episodic ataxias. PDs refer to a complex group of disorders whose main feature is the occurrence of sudden, intermittent attacks of abnormal postures and involuntary movements. PDs can sometimes be symptomatic (secondary PDs), but usually an underlying cerebral lesion is not present (primary PDs). Some of the primary PDs are transient, such as benign paroxysmal torticollis of infancy. Chronic PDs are subdivided into nonkinesigenic (Mount and Reback type), kinesigenic (Kertesz type), and exercise-induced (Lance type) but cases that overlap with these types are on record. They are autosomal dominant inherited conditions. The myofibrillogenesis regulator-1 gene is responsible for nonkinesigenic PDs. To date, the genetic basis of kinesigenic PDs remains unknown. Several clinical entities associated epilepsy with PDs, such as infantile convulsions and choreoathetosis (ICCA). Exercise-induced PD type can be produced by mutations in the SLC2A1 gene that encodes Glut1 (glucose transporter type1). Episodic ataxias are inherited disorders of intermittent ataxia. The attacks are brief and triggered by abrupt exercise and emotional stimulus. Between attacks, palpebral and hand muscle myokymia is often seen in episodic ataxia type 1 (EA1). In episodic ataxia type 2 (EA2) interictal nystagmus is usually present. Some of these latter patients develop progressive ataxia with vermian atrophy. This disorder is associated with mutations in the human Ca channel alfa 1 subunit CACN1A4 gene. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Biogeochemical cycling in an organic-rich coastal marine basin—I. Methane sediment-water exchange processes

    Science.gov (United States)

    Martens, Christopher S.; Val Klump, J.

    1980-03-01

    Methane produced in anoxic organic-rich sediments of Cape Lookout Bight, North Carolina, enters the water column via two seasonally dependent mechanisms: diffusion and bubble ebullition. Diffusive transport measured in situ with benthic chambers averages 49 and 163 μmol · m -2 · hr -1 during November-May and June-October respectively. High summer sediment methane production causes saturation concentrations and formation of bubbles near the sediment-water interface. Subsequent bubble ebullition is triggered by low-tide hydrostatic pressure release. June-October sediment-water gas fluxes at the surface average 411 ml (377 ml STP: 16.8 mmol) · m -2 per low tide. Bubbling maintains open bubble tubes which apparently enhance diffusive transport. When tubes are present, apparent sediment diffusivities are 1.2-3.1-fold higher than theoretical molecular values reaching a peak value of 5.2 × 10 -5 cm 2 · sec -1. Dissolution of 15% of the rising bubble flux containing 86% methane supplies 170μmol · m -2 · hr -1 of methane to the bight water column during summer months; the remainder is lost to the troposphere. Bottom water methane concentration increases observed during bubbling can be predicted using a 5-15 μm stagnant boundary layer dissolution model. Advective transport to surrounding waters is the major dissolved methane sink: aerobic oxidation and diffusive atmospheric evasion losses are minor within the bight.

  17. Mitigation of methane emission from an old unlined landfill in Klintholm, Denmark using a passive biocover system

    Energy Technology Data Exchange (ETDEWEB)

    Scheutz, Charlotte; Pedersen, Rasmus Broe [Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Petersen, Per Haugsted [Ramboll Denmark A/S, DK-5100 Odense C (Denmark); Jørgensen, Jørgen Henrik Bjerre [Klintholm I/S, DK-5874 Hasselager (Denmark); Ucendo, Inmaculada Maria Buendia; Mønster, Jacob G. [Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Samuelsson, Jerker [FluxSense AB/Chalmers University of Technology, SE-412 96 Göteborg (Sweden); Kjeldsen, Peter, E-mail: pekj@env.dtu.dk [Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

    2014-07-15

    Highlights: • An innovative biocover system was constructed on a landfill cell to mitigate the methane emission. • The biocover system had a mitigation efficiently of typically 80%. • The system also worked efficiently at ambient temperatures below freezing. • A whole landfill emission measurement tool was required to document the biocover system efficiency. - Abstract: Methane generated at landfills contributes to global warming and can be mitigated by biocover systems relying on microbial methane oxidation. As part of a closure plan for an old unlined landfill without any gas management measures, an innovative biocover system was established. The system was designed based on a conceptual model of the gas emission patterns established through an initial baseline study. The study included construction of gas collection trenches along the slopes of the landfill where the majority of the methane emissions occurred. Local compost materials were tested as to their usefulness as bioactive methane oxidizing material and a suitable compost mixture was selected. Whole site methane emission quantifications based on combined tracer release and downwind measurements in combination with several local experimental activities (gas composition within biocover layers, flux chamber based emission measurements and logging of compost temperatures) proved that the biocover system had an average mitigation efficiency of approximately 80%. The study showed that the system also had a high efficiency during winter periods with temperatures below freezing. An economic analysis indicated that the mitigation costs of the biocover system were competitive to other existing greenhouse gas mitigation options.

  18. Mechanistic modeling of microbial interactions at pore to profile scale resolve methane emission dynamics from permafrost soil

    Science.gov (United States)

    Ebrahimi, Ali; Or, Dani

    2017-05-01

    The sensitivity of polar regions to raising global temperatures is reflected in rapidly changing hydrological processes associated with pronounced seasonal thawing of permafrost soil and increased biological activity. Of particular concern is the potential release of large amounts of soil carbon and stimulation of other soil-borne greenhouse gas emissions such as methane. Soil methanotrophic and methanogenic microbial communities rapidly adjust their activity and spatial organization in response to permafrost thawing and other environmental factors. Soil structural elements such as aggregates and layering affect oxygen and nutrient diffusion processes thereby contributing to methanogenic activity within temporal anoxic niches (hot spots). We developed a mechanistic individual-based model to quantify microbial activity dynamics in soil pore networks considering transport processes and enzymatic activity associated with methane production in soil. The model was upscaled from single aggregates to the soil profile where freezing/thawing provides macroscopic boundary conditions for microbial activity at different soil depths. The model distinguishes microbial activity in aerate bulk soil from aggregates (or submerged profile) for resolving methane production and oxidation rates. Methane transport pathways by diffusion and ebullition of bubbles vary with hydration dynamics. The model links seasonal thermal and hydrologic dynamics with evolution of microbial community composition and function affecting net methane emissions in good agreement with experimental data. The mechanistic model enables systematic evaluation of key controlling factors in thawing permafrost and microbial response (e.g., nutrient availability and enzyme activity) on long-term methane emissions and carbon decomposition rates in the rapidly changing polar regions.

  19. Deep sea benthic foraminifera as a proxy of methane hydrates from IODP site 890B Cascadia Margin

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A. [Ministry of Petroleum, Noida (India). National Gas Hydrates Program; Gupta, A.K. [Indian Inst. of Technology, Kharagpur (India). Dept of Geology and Geophysics

    2008-07-01

    The release of methane from marine reservoirs of methane hydrates into the atmosphere has been linked to climate change through variations in benthic foraminifera signatures. This paper investigated deep sea benthic foraminifera from 174 samples taken from the north Pacific Ocean near the Cascadia Margin. The aim of the study was to develop a better understanding of benthic foraminiferal distribution in the methane-rich environment of the Cascadia Margin. Benthic foraminifera are good indicators of paleoproductivity in areas where carbon fluxes are high. Factor and cluster analyses were used to identify 6 biofacies. Ecological data from recent deep sea benthic foraminifera were used to characterize the biofacies. A benthic faunal record was used to determine oxygenation, surface productivity, and organic food supplies. Results of the study indicated that benthic assemblages showed a major shift at 2 to 3 K yrs BP and 6 to 10.5 BP coincided with the increasing amplitude of interstadial cycles, in which methane fluxes may have played a significant role. It was concluded that the dissociation of gas hydrates and the release of methane into the atmosphere may have caused an increase in the population of highly reducing environmental species.. 55 refs., 1 tab., 3 figs.

  20. Implementation of methane cycling for deep-time global warming simulations with the DCESS Earth system model (version 1.2)

    Science.gov (United States)

    Shaffer, Gary; Fernández Villanueva, Esteban; Rondanelli, Roberto; Olaf Pepke Pedersen, Jens; Malskær Olsen, Steffen; Huber, Matthew

    2017-11-01

    Geological records reveal a number of ancient, large and rapid negative excursions of the carbon-13 isotope. Such excursions can only be explained by massive injections of depleted carbon to the Earth system over a short duration. These injections may have forced strong global warming events, sometimes accompanied by mass extinctions such as the Triassic-Jurassic and end-Permian extinctions 201 and 252 million years ago, respectively. In many cases, evidence points to methane as the dominant form of injected carbon, whether as thermogenic methane formed by magma intrusions through overlying carbon-rich sediment or from warming-induced dissociation of methane hydrate, a solid compound of methane and water found in ocean sediments. As a consequence of the ubiquity and importance of methane in major Earth events, Earth system models for addressing such events should include a comprehensive treatment of methane cycling but such a treatment has often been lacking. Here we implement methane cycling in the Danish Center for Earth System Science (DCESS) model, a simplified but well-tested Earth system model of intermediate complexity. We use a generic methane input function that allows variation in input type, size, timescale and ocean-atmosphere partition. To be able to treat such massive inputs more correctly, we extend the model to deal with ocean suboxic/anoxic conditions and with radiative forcing and methane lifetimes appropriate for high atmospheric methane concentrations. With this new model version, we carried out an extensive set of simulations for methane inputs of various sizes, timescales and ocean-atmosphere partitions to probe model behavior. We find that larger methane inputs over shorter timescales with more methane dissolving in the ocean lead to ever-increasing ocean anoxia with consequences for ocean life and global carbon cycling. Greater methane input directly to the atmosphere leads to more warming and, for example, greater carbon dioxide release

  1. Implementation of methane cycling for deep-time global warming simulations with the DCESS Earth system model (version 1.2

    Directory of Open Access Journals (Sweden)

    G. Shaffer

    2017-11-01

    , greater carbon dioxide release from land soils. Analysis of synthetic sediment cores from the simulations provides guidelines for the interpretation of real sediment cores spanning the warming events. With this improved DCESS model version and paleo-reconstructions, we are now better armed to gauge the amounts, types, timescales and locations of methane injections driving specific, observed deep-time, global warming events.

  2. Predicting the fate of methane emanating from the seafloor using a marine two-phase gas model in one dimension (M2PG1) - Example from a known Arctic methane seep site offshore Svalbard

    Science.gov (United States)

    Jansson, Pär; Ferré, Benedicte

    2017-04-01

    Transport of methane in seawater occurs by diffusion and advection in the dissolved phase, and/or as free gas in form of bubbles. The fate of methane in bubbles emitted from the seafloor depends on both bubble size and ambient conditions. Larger bubbles can transport methane higher into the water column, potentially reaching the atmosphere and contributing to greenhouse gas concentrations and impacts. Single bubble or plume models have been used to predict the fate of bubble mediated methane gas emissions. Here, we present a new process based two-phase (free and dissolved) gas model in one dimension, which has the capability to dynamically couple water column properties such as temperature, salinity and dissolved gases with the free gas species contained in bubbles. The marine two-phase gas model in one dimension (M2PG1) uses a spectrum of bubbles and an Eulerian formulation, discretized on a finite-volume grid. It employs the most up-to-date equations for solubility and compressibility of the included gases, nitrogen, oxygen, carbon dioxide and methane. M2PG1 is an extension of PROBE (Omstedt, 2011), which facilitates atmospheric coupling and turbulence closures to realistically predict vertical mixing of all properties, including dissolved methane. This work presents the model's first application in an Arctic Ocean environment at the landward limit of the methane-hydrate stability zone west of Svalbard, where we observe substantial methane bubble release over longer time periods. The research is part of the Centre for Arctic Gas Hydrate, Environment and Climate (CAGE) and is supported by the Research Council of Norway through its Centres of Excellence funding scheme grant No. 223259 and UiT. Omstedt, A. (2011). Guide to process based modeling of lakes and coastal seas: Springer.

  3. Methane fluxes from a wet puna ecosystem in the Peruvian Andes

    Science.gov (United States)

    Jones, Sam; Diem, Torsten; Priscila Huaraca Quispe, Lidia; Quispe Ccahuana, Adan Julian; Meir, Patrick; Arn Teh, Yit

    2014-05-01

    Discrepancies exist between top-down and bottom-up estimates of the tropical South American atmospheric methane budget. This suggests that current source-sink inventories fail to adequately characterise the landscapes of the region. This may be particularly true of Andean environments where very few field observations have been made. The high tropical Andes, between tree and permanent snow-lines, is home to diverse grass, shrub and giant rosette dominated ecosystems known variously from Venezuela to northern Chile and Argentina as paramo, jalca and puna. In humid regions these are characterised by wet, organic-rich mineral soils, peat-forming wetlands and shallow lakes. Such conditions are likely to promote methane production and potentially represent a regionally significant source to the atmosphere that should be considered. We report on methane fluxes from a bunch-grass dominated puna habitat at 3500 m above sea level in south-eastern Peru. Mean annual temperature and precipitation are 11 °C and 2500 mm, respectively. Temperature is aseasonal but experiences considerable diurnal variations with overnight frosting common-place. In contrast, rainfall is intensely episodic and has a pronounced wet season between September and March. Sampling encompassed a range of topographic features, such as grassland on freely draining, gently inclined or steep slopes and depressions containing bogs, over a 3 ha ridge to basin transition. Monthly sampling was carried out between January 2011 and June 2013 to investigate seasonal variability in methane fluxes. Intensive sampling campaigns were conducted to investigate spatial and short-term variations on a daily basis in two nine-day campaigns during wet and dry season. The site was a net source of methane to the atmosphere during the period of study. Methane fluxes were dominated by emissions from bogs, whereas, freely draining grassland exhibited weak source or marginal sink activity. Temporal variations were most notable at

  4. High Performance Methane Thrust Chamber (HPMTC) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC proposes to develop a High-Performance Methane Thrust Chamber (HPMRE) to meet the demands of advanced chemical propulsion systems for deep-space mission...

  5. Experimental Study of Methane Hydrates in Coal

    Directory of Open Access Journals (Sweden)

    Smirnov Vyacheslav

    2017-01-01

    Full Text Available The possibility of gas hydrate formation in porous space of coal has been studied. The experiments conducted have proven the possibility of methane gas hydrate formation in moist coal. It has been demonstrated that the decomposition points of methane gas hydrates in coal are near to the phase equilibrium curve for bulk methane hydrate. Only part of water absorbed by coal can be involved in the methane gas hydrate formation. With the increase in gas pressure increases the amount of gas hydrate formed in natural coal. For formation of hydrates at a positive temperature, the pressure in the system has to be at least 2 MPa. At the same time the speed of formation and decomposition of gas hydrates in coal is big enough.

  6. Producing Hydrogen by Plasma Pyrolysis of Methane

    Science.gov (United States)

    Atwater, James; Akse, James; Wheeler, Richard

    2010-01-01

    Plasma pyrolysis of methane has been investigated for utility as a process for producing hydrogen. This process was conceived as a means of recovering hydrogen from methane produced as a byproduct of operation of a life-support system aboard a spacecraft. On Earth, this process, when fully developed, could be a means of producing hydrogen (for use as a fuel) from methane in natural gas. The most closely related prior competing process - catalytic pyrolysis of methane - has several disadvantages: a) The reactor used in the process is highly susceptible to fouling and deactivation of the catalyst by carbon deposits, necessitating frequent regeneration or replacement of the catalyst. b) The reactor is highly susceptible to plugging by deposition of carbon within fixed beds, with consequent channeling of flow, high pressure drops, and severe limitations on mass transfer, all contributing to reductions in reactor efficiency. c) Reaction rates are intrinsically low. d) The energy demand of the process is high.

  7. Methane Tracking and Mitigation Options - EPA CMOP

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset contains the sub-model for EPA's MARKAL model, which tracks methane emissions from the energy system, and limited other sources (landfills and manure...

  8. Oxytocin release in magnocellular nuclei: neurochemical mediators and functional significance during gestation

    OpenAIRE

    Bealer, Steven L.; Armstrong, William E.; Crowley, William R

    2010-01-01

    When released from dendrites within the supraoptic (SON) and paraventricular (PVN) nuclei (intranuclear release) during suckling, oxytocin exerts autocrine and paracrine effects on oxytocin neurons that are necessary for the unique timing and episodic pattern of oxytocin release into the systemic circulation that is characteristic of lactation. Recent reports have shown that stimulation of central noradrenergic and histaminergic receptors are both necessary for intranuclear release of oxytoci...

  9. Gammaproteobacterial methanotrophs dominate cold methane seeps in floodplains of West Siberian rivers.

    Science.gov (United States)

    Oshkin, Igor Y; Wegner, Carl-Eric; Lüke, Claudia; Glagolev, Mikhail V; Filippov, Illiya V; Pimenov, Nikolay V; Liesack, Werner; Dedysh, Svetlana N

    2014-10-01

    A complex system of muddy fluid-discharging and methane (CH4)-releasing seeps was discovered in a valley of the river Mukhrinskaya, one of the small rivers of the Irtysh Basin, West Siberia. CH4 flux from most (90%) of these gas ebullition sites did not exceed 1.45 g CH4 h(-1), while some seeps emitted up to 5.54 g CH4 h(-1). The δ(13)C value of methane released from these seeps varied between -71.1 and -71.3‰, suggesting its biogenic origin. Although the seeps were characterized by low in situ temperatures (3.5 to 5°C), relatively high rates of methane oxidation (15.5 to 15.9 nmol CH4 ml(-1) day(-1)) were measured in mud samples. Fluorescence in situ hybridization detected 10(7) methanotrophic bacteria (MB) per g of mud (dry weight), which accounted for up to 20.5% of total bacterial cell counts. Most (95.8 to 99.3%) methanotroph cells were type I (gammaproteobacterial) MB. The diversity of methanotrophs in this habitat was further assessed by pyrosequencing of pmoA genes, encoding particulate methane monooxygenase. A total of 53,828 pmoA gene sequences of seep-inhabiting methanotrophs were retrieved and analyzed. Nearly all of these sequences affiliated with type I MB, including the Methylobacter-Methylovulum-Methylosoma group, lake cluster 2, and several as-yet-uncharacterized methanotroph clades. Apparently, microbial communities attenuating methane fluxes from these local but strong CH4 sources in floodplains of high-latitude rivers have a large proportion of potentially novel, psychrotolerant methanotrophs, thereby providing a challenge for future isolation studies. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  10. Genes, isotopes, and ecosystem biogeochemistry. Dissecting methane flux at the leading edge of global change

    Energy Technology Data Exchange (ETDEWEB)

    Saleska, Scott [Univ. of Arizona, Tucson, AZ (United States); Rich, Virginia [The Ohio State Univ., Columbus, OH (United States); Tyson, Gene [Univ. of Queensland, St. Lucia (Australia); Chanton, Jeff [Florida State Univ., Tallahassee, FL (United States); Crill, Patrick [Stockholm Univ. (Sweden); Li, Changshen [Univ. of New Hampshire, Durham, NH (United States)

    2016-02-22

    This project integrates across three fields (microbiology, biogeochemistry, and modeling) to understand the mechanisms of methane cycling in thawing permafrost. We have made substantial progress in each area, and in cross-cutting interdisciplinary synthesis. Large releases of CH4 from thawing permafrost to the atmosphere, a strong positive feedback to global warming, are plausible but little is known about the controls on such release. Our project (“IsoGenie”) addresses the key question: What is the interplay of microbial communities and soil organic matter composition in the decomposition of organic C to CH4 across a permafrost thaw gradient?

  11. A biomimetic methane-oxidising catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Dalton, H. [Warwick Univ., Coventry (United Kingdom). Dept. of Biological Sciences

    1996-12-31

    The diminishing resources of petroleum oil has meant that there has been considerable efforts in recent years to find a suitable substitute for gasoline as a transportation fuel. Methanol has been identified as a suitable substitute since it is a readily combustible fuel which can be manufactured from a number of different sources. Methane is commonly used as a starting material for the production of synthesis gas (CO + H{sub 2}) and hence methanol. It is well known that the cleavage of the C-H bond of methane is extremely difficult (bond energy is around 104 kcal/mol) and that fairly drastic conditions are required to convert methane into methanol. Temperatures around 1200 deg C and pressures of up to 100 atmospheres over metal catalysts in a series of reactions are required to effect this process. Efforts have been made to reduce the temperature and the number of steps by using lanthanide ruthenium oxide catalyst but such reactions are still thermodynamically endothermic. An energetically more efficient reaction would be the direct conversion of methane to methanol using oxygen as the oxidant: CH{sub 4} + 1/2O{sub 2} -> CH{sub 3}OH {Delta}H deg = - 30.7 kcal/mol. Such a direct oxidation route is manifest in the bacterially-mediated oxidation of methane by methanotrophic bacteria. These organisms effect the direct oxidation of methane to methanol by the enzyme methane monooxygenase (MMO) as part of the reaction sequences to oxidize methane to carbon dioxide. (14 refs.)

  12. Prediction of enteric methane emissions from cattle.

    Science.gov (United States)

    Moraes, Luis E; Strathe, Anders B; Fadel, James G; Casper, David P; Kebreab, Ermias

    2014-07-01

    Agriculture has a key role in food production worldwide and it is a major component of the gross domestic product of several countries. Livestock production is essential for the generation of high quality protein foods and the delivery of foods in regions where animal products are the main food source. Environmental impacts of livestock production have been examined for decades, but recently emission of methane from enteric fermentation has been targeted as a substantial greenhouse gas source. The quantification of methane emissions from livestock on a global scale relies on prediction models because measurements require specialized equipment and may be expensive. The predictive ability of current methane emission models remains poor. Moreover, the availability of information on livestock production systems has increased substantially over the years enabling the development of more detailed methane prediction models. In this study, we have developed and evaluated prediction models based on a large database of enteric methane emissions from North American dairy and beef cattle. Most probable models of various complexity levels were identified using a Bayesian model selection procedure and were fitted under a hierarchical setting. Energy intake, dietary fiber and lipid proportions, animal body weight and milk fat proportion were identified as key explanatory variables for predicting emissions. Models here developed substantially outperformed models currently used in national greenhouse gas inventories. Additionally, estimates of repeatability of methane emissions were lower than the ones from the literature and multicollinearity diagnostics suggested that prediction models are stable. In this context, we propose various enteric methane prediction models which require different levels of information availability and can be readily implemented in national greenhouse gas inventories of different complexity levels. The utilization of such models may reduce errors

  13. The response of methane and dissolved inorganic carbon biogeochemistry to sediment mass transport processes in the Argentine Basin

    Science.gov (United States)

    Formolo, M.; Riedinger, N.; Henkel, S.; Tomasini, J.; Strasser, M.; Vossmeyer, A.; Kasten, S.

    2010-12-01

    Here we present results from sediments and pore waters collected from the continental margin and slope off of Uruguay and Argentina. Sampling was focused in the western Argentine Basin during Expedition M78/3 (May - July, 2009) aboard the RV Meteor. The Argentine Basin has been well documented as a region susceptible to mass sediment transport processes and high sedimentation rates. These dynamic conditions impact the pore water and dissolved methane geochemistry. Sediment and pore water samples from M78/3 provide a unique opportunity to address the response of methane and dissolved inorganic carbon (DIC) concentrations and isotopic compositions, along with concomitant sulfate, to recent sediment transport processes. Adopting the definitions from Hensen et al. (2003) for pore water profiles from this region we have subdivided the sample locations into 4 categories; linear, concave-up, kink, and s-type. Comparisons among these categories allow us to address how methane and sulfate biogeochemistry responds to sediment movements and variable methane fluxes. Within the Argentine Basin the observed sulfate and methane geochemistry are transitory in nature following mass-flow deposition or variations in methane fluxes. Over time the pore water profiles are constantly returning to a more steady-state situation and information regarding these transient periods can be lost. However, information gained from these intermediate stages, such as concave-up, kink, and s-type, provides valuable insight into the true non-steady state and dynamic biogeochemical processes along the continental margin of southeast South America and other margin environments. These environments may provide a modern analogue for ancient methane release events from sediments subjected to mass-movement events. Incidents of sediment mass-movement may be a source of methane that is often too short-lived to observe in the geologic record but may have a strong impact on sediment geochemistry. Temporally

  14. Long Term Trends and Abrupt Perturbations in the late Quaternary Atmospheric Methane Budget (Invited)

    Science.gov (United States)

    Brook, E.; Blunier, T.; Chappellaz, J. A.; Etheridge, D.; Fischer, H.; Sowers, T. A.; White, J. W.; Wolff, E. W.

    2013-12-01

    , explanations for late Quaternary variations have generally focused on a few terms, including emissions from wetlands, the atmospheric sink (primarily reaction with OH radicals), biomass burning, and release from the methane hydrate reservoir in the ocean or on land. Although it is clear that sink or source variations could change the atmospheric burden, current thinking is that the sink term is relatively insensitive to climate forcing and indirect effects of climate change on the OH field (though this conclusion is model dependent) and the literature focuses primarily on sources. Climate driven changes in methane emissions from wetlands are probably the most common, and quite plausible, explanation for most of the late Quaternary variability, particularly on glacial-interglacial and Dansgaard-Oeschger time scales, for which there is abundant evidence for large changes in tropical and high latitude temperature and hydrology. Hydrogen isotope and radiocarbon evidence do not support a large role for methane hydrates as an explanation for large changes in methane, though more extensive data sets are needed. Stable carbon isotopes are a much more complicated tracer, but do suggest a role for changes in biomass burning, particularly in the Holocene.

  15. Towards Understanding Methane Emissions from Abandoned ...

    Science.gov (United States)

    Reconciliation of large-scale top-down methane measurements and bottom-up inventories requires complete accounting of source types. Methane emissions from abandoned oil and gas wells is an area of uncertainty. This presentation reviews progress to characterize the potential inventory impacts of abandoned wells for the U.S. . Available methane emission rate data for abandoned wells is reviewed and some of the ongoing research to better characterize emissions is discussed. Efforts to compile a database of well drilling activities since the 1870’s for each state and each state’s establishment of well plugging standards for abandoned wells is described. Progress towards an estimate of national methane emissions from abandoned wells and major sources of uncertainty are presented. These emissions are put in to context by comparing to other sources of methane emissions from oil and gas production activities. This is an abstract for a presentation at the Natural GasSTAR Annual Implementation Workshop on November 16-18, 2015 in Pittsburgh, PA. The subject is methane emissions fro abandoned wells. This is a report on interim progress on a effort we have with ERG. OAP is involved in the project and will review slides.

  16. Methane storage in bottle-like nanocapsules

    Science.gov (United States)

    Vakhrushev, A. V.; Suyetin, M. V.

    2009-03-01

    Because the traditional storage of methane in the condensed state in high-pressure vessels is rather dangerous, and to store a large amount of gas using adsorbents is impossible at normal ambient conditions, we have developed a nanocapsule, which combines the advantages of a high-pressure vessel and adsorbents—a large methane mass content and safe-keeping. A nanocapsule is a system of combined nanotubes forming bottle-like pores, the entrance to which is closed by a positively charged endohedral complex (K@C60) with the help of an electric field. In normal ambient conditions, the nanocapsule can retain the amount of methane adsorbed under charging conditions. The processes taking place during the storage of methane and the methane desorption from the nanocapsule are analysed and the value of the electric field intensity necessary for the transfer of the K@C60 in the nanocapsule is determined. The nanocapsule discussed can retain ~17.5 mass% of methane at an internal pressure of 10 MPa and a temperature of 300 K.

  17. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Richard Sigal; Kent Newsham; Thomas Williams; Barry Freifeld; Timothy Kneafsey; Carl Sondergeld; Shandra Rai; Jonathan Kwan; Stephen Kirby; Robert Kleinberg; Doug Griffin

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. The work scope drilled and cored a well The Hot Ice No. 1 on Anadarko leases beginning in FY 2003 and completed in 2004. An on-site core analysis laboratory was built and utilized for determining the physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. The final efforts of the project are to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists developing reservoir models. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained in this report. The Hot Ice No. 1 well was drilled from the surface to a measured depth of 2300 ft. There was almost 100% core recovery from the bottom of surface casing at 107 ft to total depth. Based on the best estimate of the bottom of the methane hydrate stability zone (which used new data obtained from Hot Ice No. 1 and new analysis of data from adjacent wells), core was recovered over its complete range. Approximately 580 ft of porous, mostly frozen, sandstone and 155 of conglomerate were recovered in the Ugnu Formation and approximately 215 ft of porous sandstone were recovered in the West Sak Formation. There were gas shows in the bottom

  18. Methane Fluxes from Subtropical Wetlands

    Science.gov (United States)

    DeLucia, N.; Gomez-Casanovas, N.; Bernacchi, C.

    2013-12-01

    It is well documented that green house gas concentrations have risen at unequivocal rates since the industrial revolution but the disparity between anthropogenic sources and natural sources is uncertain. Wetlands are one example of a natural ecosystem that can be a substantial source or sink for methane (CH4) depending on climate conditions. Due to strict anaerobic conditions required for CH4-generating microorganisms, natural wetlands are one of the main sources for biogenic CH4. Although wetlands occupy less than 5% of total land surface area, they contribute approximately 20% of total CH4 emissions to the atmosphere. The processes regulating CH4 emissions are sensitive to land use and management practices of areas surrounding wetlands. Variation in adjacent vegetation or grazing intensity by livestock can, for example, alter CH4 fluxes from wetland soils by altering nutrient balance, carbon inputs and hydrology. Therefore, understanding how these changes will affect wetland source strength is essential to understand the impact of wetland management practices on the global climate system. In this study we quantify wetland methane fluxes from subtropical wetlands on a working cattle ranch in central Florida near Okeechobee Lake (27o10'52.04'N, 81o21'8.56'W). To determine differences in CH4 fluxes associated with land use and management, a replicated (n = 4) full factorial experiment was designed for wetlands where the surrounding vegetation was (1) grazed or un-grazed and (2) composed of native vegetation or improved pasture. Net exchange of CH4 and CO2 between the land surface and the atmosphere were sampled with a LICOR Li-7700 open path CH4 analyzer and Li-7500A open path CO2/H20 analyzer mounted in a 1-m3 static gas-exchange chamber. Our results showed and verified that CH4 emissions from subtropical wetlands were larger when high soil moisture was coupled with high temperatures. The presence of cattle only amplified these results. These results help quantify

  19. Massive production of abiotic methane during subduction evidenced in metamorphosed ophicarbonates from the Italian Alps.

    Science.gov (United States)

    Vitale Brovarone, Alberto; Martinez, Isabelle; Elmaleh, Agnès; Compagnoni, Roberto; Chaduteau, Carine; Ferraris, Cristiano; Esteve, Imène

    2017-02-22

    Alteration of ultramafic rocks plays a major role in the production of hydrocarbons and organic compounds via abiotic processes on Earth and beyond and contributes to the redistribution of C between solid and fluid reservoirs over geological cycles. Abiotic methanogenesis in ultramafic rocks is well documented at shallow conditions, whereas natural evidence at greater depths is scarce. Here we provide evidence for intense high-pressure abiotic methanogenesis by reduction of subducted ophicarbonates. Protracted (≥0.5-1 Ma), probably episodic infiltration of reduced fluids in the ophicarbonates and methanogenesis occurred from at least ∼40 km depth to ∼15-20 km depth. Textural, petrological and isotopic data indicate that methane reached saturation triggering the precipitation of graphitic C accompanied by dissolution of the precursor antigorite. Continuous infiltration of external reducing fluids caused additional methane production by interaction with the newly formed graphite. Alteration of high-pressure carbonate-bearing ultramafic rocks may represent an important source of abiotic methane, with strong implications for the mobility of deep C reservoirs.

  20. Tree-mediated methane emissions along a tropical peat dome

    Science.gov (United States)

    Pangala, Sunitha; Hoyt, Alison; Cobb, Alex; Harvey, Charles; Gauci, Vincent

    2017-04-01

    Methane production and transport processes in peatlands are fairly well understood, but growing evidence for emission of methane through trees has highlighted the need to revisit methane transport processes. We examined methane emissions from all pathways including stem and leaf emissions in one of the last remaining pristine tropical peatlands in Southeast Asia: Belait peat swamp forests, Brunei Darussalam. Methane emissions along with a range of biotic and abiotic factors were measured within three 20 x 30 m plots along transects from the edge to the center of the peat done which is dominated by Shorea albida. Tree-mediated methane emissions were the dominant means of methane emissions from all three plots, with soil emissions equating to less than 30% of the total ecosystem methane flux. Both tree and soil emissions varied between and within the three plots, with soil emissions decreasing from the edge to the center of the peat dome with increasing peat depth and decreasing water table depths and tree emissions following an opposite trend. Within each plot, tree-mediated methane emissions displayed large variability with fluxes ranging between 0.2 - 9.4 mg m-2 hr-1. Relationships between tree-mediated methane emissions and pore-water methane concentrations point towards the possibility of some of these trees transporting methane produced in the deeper layers of the peat profile to the atmosphere. Taken together, these observations highlight that methane emissions through tree stems play a more central role in methane cycling in tropical peatlands.

  1. News/Press Releases

    Data.gov (United States)

    Office of Personnel Management — A press release, news release, media release, press statement is written communication directed at members of the news media for the purpose of announcing programs...

  2. Vertical structure and horizontal variations in the cycling of methane in the sediment of Lake Onego, Russia

    Science.gov (United States)

    Thomas, Camille; Perga, Marie-Elodie; Frossard, Victor; Pasche, Natacha; Hofmann, Hilmar; Ariztegui, Daniel; Dubois, Nathalie; Belkina, Natalya; Lyautey, Emilie

    2017-04-01

    Lake Onego, the second largest lake in Europe, is a dystrophic, seasonally ice-covered lake in Karelia, Russia. Like most winter-covered lakes, its study has largely been limited to the summer period. However, it is well known that methane production is still ongoing in lake sediments during winter, potentially resulting in accumulation and major release upon thawing. Within the "Life Under The Ice" research project, our objectives were to assess winter contribution to the annual methane flux in Lake Onego, and to understand conditions and factors influencing methane cycling. During two on-ice field campaigns in March 2015 and 2016, sediment cores were retrieved at different sites of Petrozavodsk Bay, located in the north-western part of the lake. DNA and RNA were extracted from these cores to investigate the functional structure of microbial communities. Genes involved in methanogenesis, anaerobic and aerobic methane oxidations were quantified along with the concentrations and isotopic ratio of methane in the sediment pore water. Incubations, fingerprinting and sequencing of mcrA genes were also realized. Vertically, the sediment is structured in a deep anoxic zone (below 10 cm) where mcrA gene and transcript copies increased implying methanogenesis, a transitional zone (5-8 cm) hosting methanotrophic organisms (Cand. Methanoperedens) able to oxidize the diffusing methane anaerobically by coupling nitrate reduction (Haroon et al., 2013), and a shallower oxic zone where methanotrophs were detected (pmoA gene and transcripts) and where methane concentrations drop below detection limit. Sediment cores were also collected at three sites along a transect from the mouth of the river Shuya (the major inflow to the bay) to the open lake. Functional assemblage close to the river mouth had higher diversity and higher potential production rates and consumption of methane than further in the lake. However, the methane produced was almost completely consumed regardless of the

  3. Recovery from Multiple Episodes of Bipolar I Depression

    Science.gov (United States)

    Solomon, David A; Fiedorowicz, Jess G.; Leon, Andrew C.; Coryell, William; Endicott, Jean; Li, Chunshan; Boland, Robert J.; Keller, Martin B.

    2013-01-01

    Objectives To describe the duration of bipolar I major and minor depressive episodes and factors associated with time to recovery. Method 219 participants with bipolar I disorder based on Research Diagnostic Criteria analogs to DSM-IV-TR criteria were recruited from 1978–1981 and followed for up to 25 years. Psychopathology was assessed with the Longitudinal Interval Follow-up Evaluation. The probability of recovery over time from multiple successive depressive episodes was examined with survival analytic techniques, including mixed-effects grouped-time survival models. Results The median duration of major depressive episodes was 14 weeks, and over 70% recovered within 12 months of onset of the episode. The median duration of minor depressive episodes was 8 weeks, and approximately 90% recovered within 6 months of onset of the episode. Aggregated data demonstrated similar durations of the first three major depressive episodes. However, for each participant with multiple episodes of major depression or minor depression, the duration of each episode was not consistent (intraclass correlation coefficient=0.07 and 0.25 for major and minor depression, respectively). The total number of years in episode over follow-up with major plus minor depression prior to onset of a major depressive episode was significantly associated with a decreased probability of recovery from that episode; with each additional year, the likelihood of recovery was reduced by 7% (hazard ratio: 0.93, 95% CI: 0.89–0.98, p=0.002). Conclusions Bipolar I major depression generally lasts longer than minor depression, and the duration of multiple episodes within an individual varies. However, the probability of recovery over time from an episode of major depression appears to decline with each successive episode. PMID:23561241

  4. Shallow-ocean methane leakage and degassing to the atmosphere: Triggered by offshore oil-gas and methane hydrate explorations

    Directory of Open Access Journals (Sweden)

    Yong eZHANG

    2015-05-01

    Full Text Available Both offshore oil-gas exploration and marine methane hydrate recovery can trigger massive CH4 release from seafloor. During upward transportation of CH4 plume through water column, CH4 is subjected to dissolution and microbial consumption despite the protection of hydrate and oil coating on bubbles surface. The ultimate CH4 degassing to the atmosphere appears to be water-depth dependent. In shallow oceans with water depth less than 100 m, the natural or human-induced leakages or both lead to significant sea-to-air CH4 degassing from 3.00 to 1.36 × 105 μmol m-2 d-1. To quantify the human-perturbation induced CH4 degassing, the combination of top-down modeling and bottom-up calculations is essential due to spatial and temporal variability of diffusion and ebullition at water-air interface.

  5. Methane distribution and methane oxidation in the water column of the Elbe estuary, Germany

    Czech Academy of Sciences Publication Activity Database

    Matoušů, Anna; Osudar, R.; Šimek, Karel; Bussmann, I.

    2017-01-01

    Roč. 79, č. 3 (2017), s. 443-458 ISSN 1015-1621 R&D Projects: GA ČR(CZ) GA13-00243S Institutional support: RVO:60077344 Keywords : estuary * methane * methane budget * ethane oxidation * River Elbe Subject RIV: DA - Hydrology ; Limnology Impact factor: 2.821, year: 2016

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

    DEFF Research Database (Denmark)

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

    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 sedimen...... environments if nitrate is available in anoxic zones....

  7. Methane, microbes and models: fundamental understanding of the soil methane cycle for future predictions.

    Science.gov (United States)

    Nazaries, Loïc; Murrell, J Colin; Millard, Pete; Baggs, Liz; Singh, Brajesh K

    2013-09-01

    Methane is an important greenhouse gas and microbes in the environment play major roles in both global methane emissions and terrestrial sinks. However, a full mechanistic understanding of the response of the methane cycle to global change is lacking. Recent studies suggest that a number of biological and environmental processes can influence the net flux of methane from soils to the atmosphere but the magnitude and direction of their impact are still debated. Here, we synthesize recent knowledge on soil microbial and biogeochemical process and the impacts of climate change factors on the soil methane cycle. We focus on (i) identification of the source and magnitude of methane flux and the global factors that may change the flux rate and magnitude in the future, (ii) the microbial communities responsible for methane production and terrestrial sinks, and (iii) how they will respond to future climatic scenarios and the consequences for feedback responses at a global scale. We also identify the research gaps in each of the topics identified above, provide evidence which can be used to demonstrate microbial regulation of methane cycle and suggest that incorporation of microbial data from emerging -omic technologies could be harnessed to increase the predictive power of simulation models. © 2013 John Wiley & Sons Ltd and Society for Applied Microbiology.

  8. Satellite observations of atmospheric methane and their value for quantifying methane emissions

    NARCIS (Netherlands)

    Jacob, Daniel J.; Turner, Alexander J.; Maasakkers, Joannes D.; Sheng, Jianxiong; Sun, Kang; Liu, Xiong; Chance, Kelly; Aben, Ilse; McKeever, Jason; Frankenberg, Christian

    2016-01-01

    Methane is a greenhouse gas emitted by a range of natural and anthropogenic sources. Atmospheric methane has been measured continuously from space since 2003, and new instruments are planned for launch in the near future that will greatly expand the capabilities of space-based observations. We

  9. Anaerobic methane oxidation in low-organic content methane seep sediments

    Science.gov (United States)

    Pohlman, John W.; Riedel, Michael; Bauer, James E.; Canuel, Elizabeth A.; Paull, Charles K.; Lapham, Laura; Grabowski, Kenneth S.; Coffin, Richard B.; Spence, George D.

    2013-01-01

    Sulfate-dependent anaerobic oxidation of methane (AOM) is the key sedimentary microbial process limiting methane emissions from marine sediments and methane seeps. In this study, we investigate how the presence of low-organic content sediment influences the capacity and efficiency of AOM at Bullseye vent, a gas hydrate-bearing cold seep offshore of Vancouver Island, Canada. The upper 8 m of sediment contains 14C. A fossil origin for the DIC precludes remineralization of non-fossil OM present within the sulfate zone as a significant contributor to pore water DIC, suggesting that nearly all sulfate is available for anaerobic oxidation of fossil seep methane. Methane flux from the SMT to the sediment water interface in a diffusion-dominated flux region of Bullseye vent was, on average, 96% less than at an OM-rich seep in the Gulf of Mexico with a similar methane flux regime. Evidence for enhanced methane oxidation capacity within OM-poor sediments has implications for assessing how climate-sensitive reservoirs of sedimentary methane (e.g., gas hydrate) will respond to ocean warming, particularly along glacially-influenced mid and high latitude continental margins.

  10. Quantification of methane oxidation in the rice rhizosphere using 13C-labelled methane

    NARCIS (Netherlands)

    Groot, T.T; van Bodegom, P.M.; Harren, F.J.M.; Meijer, H.A.J.

    In this paper isotope ratio mass spectrometry is used to determine the methane (CH4) oxidation fraction in the rhizosphere of intact rice plant-soil systems. Earlier studies on quantification of the methane oxidation were based on inhibition or incubation procedures which strongly interfered with

  11. Quantification of methane oxidation in the rice rhizosphere using C-13-labelled methane

    NARCIS (Netherlands)

    Groot, T.T.; Bodegom, van P.M.; Harren, F.J.M.; Meijer, H.A.J.

    2003-01-01

    In this paper isotope ratio mass spectrometry is used to determine the methane (CH4) oxidation fraction in the rhizosphere of intact rice plant-soil systems. Earlier studies on quantification of the methane oxidation were based on inhibition or incubation procedures which strongly interfered with

  12. Ocean methane hydrates as a slow tipping point in the global carbon cycle.

    Science.gov (United States)

    Archer, David; Buffett, Bruce; Brovkin, Victor

    2009-12-08

    We present a model of the global methane inventory as hydrate and bubbles below the sea floor. The model predicts the inventory of CH(4) in the ocean today to be approximately 1600-2,000 Pg of C. Most of the hydrate in the model is in the Pacific, in large part because lower oxygen levels enhance the preservation of organic carbon. Because the oxygen concentration today may be different from the long-term average, the sensitivity of the model to O(2) is a source of uncertainty in predicting hydrate inventories. Cold water column temperatures in the high latitudes lead to buildup of hydrates in the Arctic and Antarctic at shallower depths than is possible in low latitudes. A critical bubble volume fraction threshold has been proposed as a critical threshold at which gas migrates all through the sediment column. Our model lacks many factors that lead to heterogeneity in the real hydrate reservoir in the ocean, such as preferential hydrate formation in sandy sediments and subsurface gas migration, and is therefore conservative in its prediction of releasable methane, finding only 35 Pg of C released after 3 degrees C of uniform warming by using a 10% critical bubble volume. If 2.5% bubble volume is taken as critical, then 940 Pg of C might escape in response to 3 degrees C warming. This hydrate model embedded into a global climate model predicts approximately 0.4-0.5 degrees C additional warming from the hydrate response to fossil fuel CO(2) release, initially because of methane, but persisting through the 10-kyr duration of the simulations because of the CO(2) oxidation product of methane.

  13. Ocean methane hydrates as a slow tipping point in the global carbon cycle

    Science.gov (United States)

    Archer, David; Buffett, Bruce; Brovkin, Victor

    2009-01-01

    We present a model of the global methane inventory as hydrate and bubbles below the sea floor. The model predicts the inventory of CH4 in the ocean today to be ≈1600–2,000 Pg of C. Most of the hydrate in the model is in the Pacific, in large part because lower oxygen levels enhance the preservation of organic carbon. Because the oxygen concentration today may be different from the long-term average, the sensitivity of the model to O2 is a source of uncertainty in predicting hydrate inventories. Cold water column temperatures in the high latitudes lead to buildup of hydrates in the Arctic and Antarctic at shallower depths than is possible in low latitudes. A critical bubble volume fraction threshold has been proposed as a critical threshold at which gas migrates all through the sediment column. Our model lacks many factors that lead to heterogeneity in the real hydrate reservoir in the ocean, such as preferential hydrate formation in sandy sediments and subsurface gas migration, and is therefore conservative in its prediction of releasable methane, finding only 35 Pg of C released after 3 °C of uniform warming by using a 10% critical bubble volume. If 2.5% bubble volume is taken as critical, then 940 Pg of C might escape in response to 3 °C warming. This hydrate model embedded into a global climate model predicts ≈0.4–0.5 °C additional warming from the hydrate response to fossil fuel CO2 release, initially because of methane, but persisting through the 10-kyr duration of the simulations because of the CO2 oxidation product of methane. PMID:19017807

  14. Preserved episodic memory in subcortical band heterotopia.

    Science.gov (United States)

    Janzen, Laura; Sherman, Elisabeth; Langfitt, John; Berg, Michel; Connolly, Mary

    2004-05-01

    Neuropsychological profiles of four patients with subcortical band heterotopia (SBH) are presented to delineate further the phenotype of this disorder. Standardized, norm-referenced measures of cognitive functioning, including intelligence, processing speed, attention, language, visuomotor skills, memory, and fine motor ability were administered to four patients with magnetic resonance imaging evidence of SBH. Despite intellectual impairment and other severe cognitive deficits, all four patients displayed relatively intact episodic memory. This selective sparing of memory functions has not been previously reported in individuals with SBH and suggests that doublecortin does not play a role in the development of memory systems in the mesial temporal region, which tend to be spared in SBH.

  15. Gaia's breath - Global methane exhalations

    Science.gov (United States)

    Kvenvolden, K.A.; Rogers, B.W.

    2005-01-01

    Methane (CH4) is the most abundant organic compound in the Earth's atmosphere, where it acts as a greenhouse gas and thus has implications for global climate change. The current atmospheric CH4 budget, however, does not take into account geologically-sourced CH4 seepage. Geological sources of CH4 include natural macro- and micro-seeps, mud volcanoes, and other miscellaneous sources such as gas hydrates, magmatic volcanoes, geothermal regions, and mid-ocean ridges. Macro-seeps contribute ???25 Tg (teragrams) CH4/yr to the atmosphere, whereas, micro-seepage contributes perhaps 7 Tg CH4/yr. Mud volcanoes emit ???5 Tg CH4/yr, and miscellaneous sources emit ???8 Tg CH4/yr to the atmosphere. Thus, the total contribution to the atmosphere from geological sources is estimated to be 45 Tg CH4/yr, which is significant to the atmospheric organic carbon cycle and should be included in any global inventory of atmospheric CH4. We argue that the atmospheric CH4 global inventory of the Interplanetary Panel on Climate Change must be adjusted in order to incorporate geologically-sourced CH4 from naturally occurring seepage.

  16. Understanding the glacial methane cycle

    Science.gov (United States)

    Hopcroft, Peter O.; Valdes, Paul J.; O'Connor, Fiona M.; Kaplan, Jed O.; Beerling, David J.

    2017-02-01

    Atmospheric methane (CH4) varied with climate during the Quaternary, rising from a concentration of 375 p.p.b.v. during the last glacial maximum (LGM) 21,000 years ago, to 680 p.p.b.v. at the beginning of the industrial revolution. However, the causes of this increase remain unclear; proposed hypotheses rely on fluctuations in either the magnitude of CH4 sources or CH4 atmospheric lifetime, or both. Here we use an Earth System model to provide a comprehensive assessment of these competing hypotheses, including estimates of uncertainty. We show that in this model, the global LGM CH4 source was reduced by 28-46%, and the lifetime increased by 2-8%, with a best-estimate LGM CH4 concentration of 463-480 p.p.b.v. Simulating the observed LGM concentration requires a 46-49% reduction in sources, indicating that we cannot reconcile the observed amplitude. This highlights the need for better understanding of the effects of low CO2 and cooler climate on wetlands and other natural CH4 sources.

  17. Porewater methane transport within the gas vesicles of diurnally migrating Chaoborus spp.: An energetic advantage

    Science.gov (United States)

    McGinnis, Daniel F.; Flury, Sabine; Tang, Kam W.; Grossart, Hans-Peter

    2017-03-01

    Diurnally-migrating Chaoborus spp. reach populations of up to 130,000 individuals m-2 in lakes up to 70 meters deep on all continents except Antarctica. Linked to eutrophication, migrating Chaoborus spp. dwell in the anoxic sediment during daytime and feed in the oxic surface layer at night. Our experiments show that by burrowing into the sediment, Chaoborus spp. utilize the high dissolved gas partial pressure of sediment methane to inflate their tracheal sacs. This mechanism provides a significant energetic advantage that allows the larvae to migrate via passive buoyancy rather than more energy-costly swimming. The Chaoborus spp. larvae, in addition to potentially releasing sediment methane bubbles twice a day by entering and leaving the sediment, also transport porewater methane within their gas vesicles into the water column, resulting in a flux of 0.01-2 mol m-2 yr-1 depending on population density and water depth. Chaoborus spp. emerging annually as flies also result in 0.1-6 mol m-2 yr-1 of carbon export from the system. Finding the tipping point in lake eutrophication enabling this methane-powered migration mechanism is crucial for ultimately reconstructing the geographical expansion of Chaoborus spp., and the corresponding shifts in the lake’s biogeochemistry, carbon cycling and food web structure.

  18. Marine methane cycle simulations for the period of early global warming

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, S.; Maltrud, M.; Reagan, M.T.; Moridis, G.J.; Cameron-Smith, P.J.

    2011-01-02

    Geochemical environments, fates, and effects are modeled for methane released into seawater by the decomposition of climate-sensitive clathrates. A contemporary global background cycle is first constructed, within the framework of the Parallel Ocean Program. Input from organics in the upper thermocline is related to oxygen levels, and microbial consumption is parameterized from available rate measurements. Seepage into bottom layers is then superimposed, representing typical seabed fluid flow. The resulting CH{sub 4} distribution is validated against surface saturation ratios, vertical sections, and slope plume studies. Injections of clathrate-derived methane are explored by distributing a small number of point sources around the Arctic continental shelf, where stocks are extensive and susceptible to instability during the first few decades of global warming. Isolated bottom cells are assigned dissolved gas fluxes from porous-media simulation. Given the present bulk removal pattern, methane does not penetrate far from emission sites. Accumulated effects, however, spread to the regional scale following the modeled current system. Both hypoxification and acidification are documented. Sensitivity studies illustrate a potential for material restrictions to broaden the perturbations, since methanotrophic consumers require nutrients and trace metals. When such factors are considered, methane buildup within the Arctic basin is enhanced. However, freshened polar surface waters act as a barrier to atmospheric transfer, diverting products into the deep return flow. Uncertainties in the logic and calculations are enumerated including those inherent in high-latitude clathrate abundance, buoyant effluent rise through the column, representation of the general circulation, and bacterial growth kinetics.

  19. Forest cockchafer larvae as methane production hotspots in soils and their importance for net soil methane fluxes

    Science.gov (United States)

    Görres, Carolyn-Monika; Kammann, Claudia; Murphy, Paul; Müller, Christoph

    2016-04-01

    Certain groups of soil invertebrates, namely scarab beetles and millipedes, are capable of emitting considerable amounts of methane due to methanogens inhabiting their gut system. It was already pointed out in the early 1990's, that these groups of invertebrates may represent a globally important source of methane. However, apart from termites, the importance of invertebrates for the soil methane budget is still unknown. Here, we present preliminary results of a laboratory soil incubation experiment elucidating the influence of forest cockchafer larvae (Melolontha hippocastani FABRICIUS) on soil methane cycling. In January/February 2016, two soils from two different management systems - one from a pine forest (extensive use) and one from a vegetable field (intensive use) - were incubated for 56 days either with or without beetle larvae. Net soil methane fluxes and larvae methane emissions together with their stable carbon isotope signatures were quantified at regular intervals to estimate gross methane production and gross methane oxidation in the soils. The results of this experiment will contribute to testing the hypothesis of whether methane production hotspots can significantly enhance the methane oxidation capacity of soils. Forest cockchafer larvae are only found in well-aerated sandy soils where one would usually not suspect relevant gross methane production. Thus, besides quantifying their contribution to net soil methane fluxes, they are also ideal organisms to study the effect of methane production hotspots on overall soil methane cycling. Funding support: Reintegration grant of the German Academic Exchange Service (DAAD) (#57185798).

  20. Multiparametric methane sensor for environmental monitoring

    Science.gov (United States)

    Borecki, M.; Duk, M.; Kociubiński, A.; Korwin-Pawlowski, M. L.

    2016-12-01

    Today, methane sensors find applications mostly in safety alarm installations, gas parameters detection and air pollution classification. Such sensors and sensors elements exists for industry and home use. Under development area of methane sensors application is dedicated to ground gases monitoring. Proper monitoring of soil gases requires reliable and maintenance-free semi-constant and longtime examination at relatively low cost of equipment. The sensors for soil monitoring have to work on soil probe. Therefore, sensor is exposed to environment conditions, as a wide range of temperatures and a full scale of humidity changes, as well as rain, snow and wind, that are not specified for classical methane sensors. Development of such sensor is presented in this paper. The presented sensor construction consists of five commercial non dispersive infra-red (NDIR) methane sensing units, a set of temperature and humidity sensing units, a gas chamber equipped with a micro-fan, automated gas valves and also a microcontroller that controls the measuring procedure. The electronics part of sensor was installed into customized 3D printed housing equipped with self-developed gas valves. The main development of proposed sensor is on the side of experimental evaluation of construction reliability and results of data processing included safety procedures and function for hardware error correction. Redundant methane sensor units are used providing measurement error correction as well as improved measurement accuracy. The humidity and temperature sensors are used for internal compensation of methane measurements as well as for cutting-off the sensor from the environment when the conditions exceed allowable parameters. Results obtained during environment sensing prove that the gas concentration readings are not sensitive to gas chamber vertical or horizontal position. It is important as vertical sensor installation on soil probe is simpler that horizontal one. Data acquired during six

  1. Spatially explicit methane inventory for Switzerland

    Science.gov (United States)

    Hiller, Rebecca; Bretscher, Daniel; DelSontro, Tonya; Eugster, Werner; Henne, Stephan; Henneberger, Ruth; Künzle, Thomas; Merbold, Lutz; Neininger, Bruno; Schellenberger, Andreas; Schroth, Martin; Buchmann, Nina; Brunner1, Dominik

    2013-04-01

    Spatially explicit greenhouse gas inventories are gaining in importance as a tool for policy makers to plan and control mitigation measures, and are a required input for atmospheric models used to relate atmospheric concentration measurements with upstream sources. In order to represent the high spatial heterogeneity in Switzerland, we compiled the national methane inventory into a 500 m x 500 m cadaster. In addition to the anthropogenic emissions reported to the United Nation Framework Convention on Climate Change (UNFCCC), we also included natural and semi-natural methane fluxes, i.e., emissions from lakes and reservoirs, wetlands, wild animals as well as forest uptake. Methane emissions were disaggregated according to geostatistical information about source location and extent. In Switzerland, highest methane emissions originate from the agricultural sector (152 Gg CH4 yr-1), followed by emissions from waste management (16 Gg CH4 yr-1) with highest contributions from landfills, and the energy sector (13 Gg CH4 yr-1) with highest contributions from the distribution of natural gas. Natural and semi-natural emissions only add a small amount (inventory was evaluated against methane concentrations measured from a small research aircraft (METAIR-DIMO) above the Swiss Plateau on 18 different days from May 2009 to August 2010 over. Source sensitivities of the air measured were determined by backward runs of the Lagrangian particle dispersion model FLEXPART-COSMO. Source sensitivities were multiplied with the methane inventory to derive simulated methane concentration time series. While the pattern of the variations can be reproduced well for some flight days (correlation coefficient up to 0.75), the amplitude of the variations for the simulated time series is underestimated by at least 20% suggesting an underestimation of CH4 emissions by the inventory, which is also concluded from inverse estimation using a Bayesian approach.

  2. Methane Hotspots in the Los Angeles Megacity

    Science.gov (United States)

    Hopkins, F. M.; Randerson, J. T.; Bush, S.; Ehleringer, J. R.; Lai, C.; Kort, E. A.; Blake, D. R.

    2013-12-01

    Airborne observations show that Los Angeles (LA) is a large source of methane to the atmosphere, yet the sources of excess methane from the urban area are poorly constrained. We used a mobile laboratory, a Ford Transit van equipped with cavity ring down spectrometers (Picarro, Inc.), to measure greenhouse gases (CH4, CO2, and CO) mole fractions in LA. On-road surveys across the LA Basin were conducted seasonally to determine patterns of CH4 enrichment in space and over time, with a focus on quantifying methane leaks from known sources. We found fugitive leaks and elevated CH4 concentrations throughout the LA Basin. Some were associated with known sources, such as landfills, wastewater treatment, and oil and gas infrastructure, while others had an unknown origin. Urban CH4 enrichment varied over the course of the year, largely due to seasonal changes in meteorological conditions. Nevertheless, our mobile surveys revealed CH4 hotspots (>200 ppb elevated with respect to background levels) that persisted among seasons. High CH4 concentrations were most easily predicted by proximity to methane sources, particularly near the coast, while elevated CH4 levels were more evenly dispersed in inland areas. CH4 hotspots had a disproportionate impact on excess methane relative to the area they accounted for, typically providing more than a quarter of excess methane measured on a transect. These data improve estimates of the relative roles of specific leaks and emission sectors to LA's excess methane. Depending on the cost of reducing these CH4 leaks, a focus on CH4 emissions may prove an effective way to reduce LA's greenhouse gas emissions in the near term.

  3. On the Development of Episodic Memory: Two Basic Questions

    DEFF Research Database (Denmark)

    Dahl, Jonna Jelsbak; Sonne, Trine; Kingo, Osman Skjold

    2013-01-01

    In this focused review we present and discuss two basic questions related to the early development of episodic memory in children: (1) “What is an episode?”, and (2) “How do preverbal children recall a specific episode of a recurring event?” First, a brief introduction to episodic memory is outli...... and attempt to demonstrate, that pursuing answers to both questions is of crucial importance – both conceptually and methodologically - if we are ever to understand the early development of episodic memory. ......In this focused review we present and discuss two basic questions related to the early development of episodic memory in children: (1) “What is an episode?”, and (2) “How do preverbal children recall a specific episode of a recurring event?” First, a brief introduction to episodic memory...... is outlined. We argue in favor of employing a definition of episodic memory allowing us to investigate the development of episodic memory by purely behavioral measures. Second, research related to each of the two questions are presented and discussed, at first separately, and subsequently together. We argue...

  4. Lifespan trends of autobiographical remembering: episodicity and search for meaning.

    Science.gov (United States)

    Habermas, Tilmann; Diel, Verena; Welzer, Harald

    2013-09-01

    Autobiographical memories of older adults show fewer episodic and more non-episodic elements than those of younger adults. This semantization effect is attributed to a loss of episodic memory ability. However the alternative explanation by an increasing proclivity to search for meaning has not been ruled out to date. To test whether a decrease in episodicity and an increase in meaning-making in autobiographical narratives are related across the lifespan, we used different instructions, one focussing on specific episodes, the other on embedding events in life, in two lifespan samples. A continuous decrease of episodic quality of memory (memory specificity, narrative quality) was confirmed. An increase of search for meaning (interpretation, life story integration) was confirmed only up to middle adulthood. This non-inverse development of episodicity and searching for meaning in older age speaks for an autonomous semantization effect that is not merely due to an increase in interpretative preferences. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. [Brain imaging of first-episode psychosis].

    Science.gov (United States)

    Jardri, R

    2013-09-01

    In the last decades, schizophrenia has intensively been studied using various brain imaging techniques. However, several potential confounding factors limited their interpretation power (e.g. chronicity, the impact of antipsychotic medication). By considering psychosis as a continuum of changes starting from mild cognitive impairments to serious psychotic symptoms, it became possible to provide deeper insight in the neurobiological mechanisms underlying the onset of psychosis by focusing on at-risk individuals and first-episodes. Recent brain imaging meta-analyses of the first episode psychosis (FEP), noteworthy reported conjoint bilateral structural and functional differences at the level of the insula, the superior temporal gyrus and the medial frontal gyrus, encompassing the anterior cingulate cortex. In the present review, we thus provide an update of brain imaging studies of FEP with a particular emphasis on more recent anatomical, functional and molecular explorations. Specifically, we provide 1) a review of the common features observed in individuals with high risk for psychosis and changes characterizing the transition to psychosis, 2) a description of the environmental and drug factors influencing these abnormalities, 3) how these findings in FEP may differ from those observed in chronic individuals with schizophrenia, and 4) a short overview of new classification algorithms able to use MRI findings as valuable biomarkers to guide early detection in the prodromal phase of psychosis. Copyright © 2013 L’Encéphale. Published by Elsevier Masson SAS.. All rights reserved.

  6. Episodic Aging and End States of Comets

    Science.gov (United States)

    Sekanina, Zdenek

    2008-01-01

    It is known that comets are aging very rapidly on cosmic scales, because they rapidly shed mass. The processes involved are (i) normal activity - sublimation of ices and expulsion of dust from discrete emission sources on and/or below the surface of a comet's nucleus, and (ii) nuclear fragmentation. Both modes are episodic in nature, the latter includes major steps in the comet's life cycle. The role and history of dynamical techniques used are described and results on mass losses due to sublimation and dust expulsion are reviewed. Studies of split comets, Holmes-like exploding comets, and cataclysmically fragmenting comets show that masses of 10 to 100 million tons are involved in the fragmentation process. This and other information is used to investigate the nature of comets' episodic aging. Based on recent advances in understanding the surface morphology of cometary nuclei by close-up imaging, a possible mechanism for large-scale fragmentation events is proposed and shown to be consistent with evidence available from observations. Strongly flattened pancake-like shapes appear to be required for comet fragments by conceptual constraints. Possible end states are briefly examined.

  7. [Early episodic memory impairments in Alzheimer's disease].

    Science.gov (United States)

    Ergis, A-M; Eusop-Roussel, E

    2008-05-01

    Patients with Alzheimer's disease (AD) show early episodic memory impairments. Such deficits reflect specific impairments affecting one or several stages of encoding, storage and retrieval processes. However, AD patients not only have great difficulty retrieving memories and information but also suffer from distortions of memory, as intrusions and false recognitions. Intrusions can be defined as the unintentional recall of inappropriate information in a laboratory-learning tasks such as word-list recall and story recall. False recognition refers to the erroneous recognition of information that was not previously presented. The first objective of this review is to present studies from the literature that allowed a better understanding of the nature of episodic memory deficits in AD, and to examine recent research on false memories. The second part of this review is aimed at presenting recent research conducted on prospective memory (PM) in Alzheimer's disease. Prospective memory situations involve forming intentions and then realizing those intentions at some appropriate time in the future. Everyday examples of prospective memory include remembering to buy bread on the way home from work, remembering to give friends a message upon next encountering them, and remembering to take medication. Patients suffering from AD show difficulties in performing prospective tasks in daily life, according to the complaints of their care givers, and these difficulties are massively present at the first stages of the disease. Nevertheless, very few studies have been dedicated to this subject, although the evaluation of PM could be helpful for the early diagnosis of AD.

  8. Erenumab (AMG 334) in episodic migraine

    DEFF Research Database (Denmark)

    Ashina, Messoud; Dodick, David; Goadsby, Peter J.

    2017-01-01

    Objective: To assess long-term safety and efficacy of anti-calcitonin gene-related peptide receptor erenumab in patients with episodic migraine (EM). Methods: Patients enrolled in a 12-week, double-blind, placebo-controlled clinical trial (NCT01952574) who continued in an open-label extension (OL...... reduces long-term MMD and improves headache-related disability and migraine-specific quality of life.......) study will receive erenumab 70 mg every 4 weeks for up to 5 years. This preplanned interim analysis, conducted after all participants had completed the 1-year open-label follow-up, evaluated changes in monthly migraine days (MMD), achievement of ≥50%, ≥75%, and 100% reductions, Headache Impact Test (HIT...... improvements and favorable safety and tolerability profiles, supports further investigation of erenumab as a preventive treatment in patients with EM. Clinicaltrials.gov identifier: NCT01952574. Classification of evidence: This study provides Class IV evidence that for patients with episodic migraine, erenumab...

  9. Cabergoline-induced manic episode: case report.

    Science.gov (United States)

    Yüksel, Rabia Nazik; Elyas Kaya, Zeynep; Dilbaz, Nesrin; Cingi Yirün, Merve

    2016-06-01

    Cabergoline is an orally administered synthetic dopamine agonist that is used for the treatment of hyperprolactinemia, Parkinson's disease and antipsychotic-induced prolactin elevation. One of the main characteristics of cabergoline is its long duration of effect. It is highly effective in suppressing prolactin levels up to 21 days after a single 1 mg oral dose. The prolonged elimination half-life offers an advantage of once-daily dosing, but it might be a handicap in terms of washout of adverse effects such as psychosis. Cabergoline has been associated with adverse reactions consistent with other dopaminergic agonists including cardiovascular, gastrointestinal and neuropsychiatric effects. It is known that dopaminergic treatment is a remarkable risk factor for psychosis. A number of reports implicate dopamine agonists in the development of psychosis, but there is no knowledge in the literature of dopamine agonist-induced mania. In this case, we report the first manic episode occurring after cabergoline use for hyperprolactinemia treatment. In susceptible individuals, cabergoline can cause manic episodes and cabergoline should be used more carefully considering the risk-benefit ratio.

  10. Course of insight in manic episode

    Directory of Open Access Journals (Sweden)

    A Kumar

    2013-01-01

    Full Text Available Background: Insight is an important factor associated with non compliance and poor outcome. Poor level of insight has been described as a characteristic in patients with acute bipolar disorder with more unawareness in social consequences with increasing severity in manic episode. Aim: Main aim of study was to see the baseline and longitudinal relationship between dimensions of insight with improvement in psychopathology. Setting and Design: Forty four patients diagnosed with mania, were selected from an inpatient setting at Institute of Mental Health and Hospital, Agra with mean age of 31.07(±9.00 years. They were assessed at base line and were followed up weekly or psychopathology and insight. Materials and Methods: The Young′s mania rating scale for psychopathology and insight was assessed on three dimensions of SUMD. Results: Twenty five patients eventually completed the study. There was a positive correlation with global insight and with psychopathology consistent in longitudinal follow-up (P<0.05, but not correlating for awareness for achieved effect of medication and social consequences. Linear regression showed a positive relationship at the first and second week of assessment of SUMD and YMRS scores (P=0.001; 0.019. Conclusion: Improvement in insight is graded in a manic episode as compared to psychopathology. There is slower improvement in awareness of social consequences of mental disorder. It means that improvement in psychopathology may not necessarily indicate remission and need further supervision to improve insight and hence monitoring.

  11. A Compact, Low Resource Instrument to Measure Atmospheric Methane and Carbon Dioxide From Orbit

    Science.gov (United States)

    Rafkin, Scot; Davis, Michael; Varner, Ruth; Basu, Sourish; Bruhwiler, Lori; Luspay-Kuti, Adrienn; Mandt, Kathy; Roming, Pete; Soto, Alejandro; Tapley, Mark

    2017-04-01

    Methane is the second most important radiatively active trace gas forcing anthropogenic climate change. Methane has ˜28 times more warming potential than carbon dioxide on a 100-year time horizon, and the background atmospheric concentration of methane has increased by more than 150% compared to pre-industrial levels. The increase in methane abundance is driven by a combination of direct human activity, such as fossil fuel extraction and agriculture, and natural feedback processes that respond to human-induced climate change, such as increased wetland production. Accurate accounting of the exchange between the atmosphere and the natural and anthropogenic methane reservoirs is necessary to predict how methane concentration will increase going forward, how that increase will modulate the natural methane cycle, and how effective policy decisions might be at mitigating methane-induced climate change. Monitoring and quantifying methane source intensity and spatial-temporal variability has proven challenging; there are unresolved and scientifically significant discrepancies between flux estimates based on limited surface measurements (the so-called "bottom-up" method) and the values derived from limited, remotely-sensed estimates from orbit and modeling (the so-called "top-down" method). A major source of the discrepancy between bottom-up and top-down estimates is likely a result of insufficient accuracy and resolution of space-based instrumentation. Methane releases, especially anthropogenic sources, are often at kilometer-scale (or less), whereas past remote sensing instruments have at least an order of magnitude greater footprint areas. Natural sources may be larger in areal extent, but the enhancement over background levels can be just a few percent, which demands high spectral resolution and signal-to-noise ratios from monitoring instrumentation. In response to the need for higher performance space-based methane monitoring, we have developed a novel, compact, low

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

    Science.gov (United States)

    Pohlman, John; Kaneko, Masanori; Heuer, Verena B.; Coffin, Richard B.; Whiticar, Michael

    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 δ13C 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 (εc = 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 δDCH4 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

  13. [Therapeutic strategies in the first psychotic episode].

    Science.gov (United States)

    Douki, S; Taktak, M J; Ben Zineb, S; Cheour, M

    1999-11-01

    A first psychotic episode includes a wide range of disorders with different outcomes: schizophrenia, bipolar disorder, schizophreniform disorder, schizoaffective disorder, drug-induced psychosis, brief reactive psychosis, organic psychoses and delusional disorder. The course and outcome of a first psychotic episode is greatly dependent on its initial management. Major clinical, etiopathogenic and therapeutic advances have been achieved in this field and have allowed specific management strategies to be adopted. The primary task of therapists involved in the management of patients who have experienced a first episode of psychosis is promotion of recovery and prevention of secondary morbidity, relapse and persistent disability. The main guidelines of an early psychosis management are:--to keep in mind that early psychosis is not early schizophrenia. Thus, clinicians and therapists should avoid an early diagnosis of schizophrenia. Diagnosis in early psychosis can be highly unstable. A diagnosis of schizophrenia, with its implications of pessimism, relapse and disability, does not contribute anything positive in terms of guiding treatment. On the contrary, such a diagnosis may damage the patient and family by stigmatizing them and affecting the way they are viewed and managed by healthcare professionals.--To integrate biological, psychological and social interventions: effective medications is useful in reducing the risk of relapse, but is not a guarantee against it. Psychological and social interventions can greatly help promote recovery.--To tailor the various strategies to met the needs of an individual: as an example, it is important to formulate appropriate strategies for the different stages of the illness (prodromal phase, acute phase, early recovery phase and late recovery phase) because patients have different therapeutic needs at each stage.--In the acute treatment, not to concentrate on short-term goals in indicating antipsychotic treatment: prescribing

  14. Sealing rice field boundaries in Bangladesh: a pilot study demonstrating reductions in water use, arsenic loading to field soils, and methane emissions from irrigation water.

    Science.gov (United States)

    Neumann, Rebecca B; Pracht, Lara E; Polizzotto, Matthew L; Badruzzaman, A Borhan M; Ali, M Ashraf

    2014-08-19

    Irrigation of rice fields in Bangladesh with arsenic-contaminated and methane-rich groundwater loads arsenic into field soils and releases methane into the atmosphere. We tested the water-savings potential of sealing field bunds (raised boundaries around field edges) as a way to mitigate these negative outcomes. We found that, on average, bund sealing reduced seasonal water use by 52 ± 17% and decreased arsenic loading to field soils by 15 ± 4%; greater savings in both water use and arsenic loading were achieved in fields with larger perimeter-to-area ratios (i.e., smaller fields). Our study is the first to quantify emission of methane from irrigation water in Bangladesh, a currently unaccounted-for methane source. Irrigation water applied to unsealed fields at our site emits 18 to 31 g of methane per square-meter of field area per season, potentially doubling the atmospheric input of methane from rice cultivation. Bund sealing reduced the emission of methane from irrigation water by 4 to 19 g/m(2). While the studied outcomes of bund sealing are positive and compelling, widespread implementation of the technique should consider other factors, such as effect on yields, financial costs, and impact on the hydrologic system. We provide an initial and preliminary assessment of these implementation factors.

  15. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Ali Kadaster; Bill Liddell; Tommy Thompson; Thomas Williams; Michael Niedermayr

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project was a cost-shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. The work scope included drilling and coring a well (Hot Ice No. 1) on Anadarko leases beginning in FY 2003 and completed in 2004. During the first drilling season, operations were conducted at the site between January 28, 2003 to April 30, 2003. The well was spudded and drilled to a depth of 1403 ft. Due to the onset of warmer weather, work was then suspended for the season. Operations at the site were continued after the tundra was re-opened the following season. Between January 12, 2004 and March 19, 2004, the well was drilled and cored to a final depth of 2300 ft. An on-site core analysis laboratory was built and implemented for determining physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. Final efforts of the project are to correlate geology, geophysics, logs, and drilling and

  16. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Steve Runyon; Mike Globe; Kent Newsham; Robert Kleinberg; Doug Griffin

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project was a cost-shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. The work scope included drilling and coring a well (Hot Ice No. 1) on Anadarko leases beginning in FY 2003 and completed in 2004. During the first drilling season, operations were conducted at the site between January 28, 2003 to April 30, 2003. The well was spudded and drilled to a depth of 1403 ft. Due to the onset of warmer weather, work was then suspended for the season. Operations at the site were continued after the tundra was re-opened the following season. Between January 12, 2004 and March 19, 2004, the well was drilled and cored to a final depth of 2300 ft. An on-site core analysis laboratory was built and utilized for determining the physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. The final efforts of the project are to correlate geology, geophysics, logs, and drilling

  17. Experimental characterization of methane inverse diffusion flame

    KAUST Repository

    Elbaz, Ayman M.

    2014-06-26

    This article presents 10-kHz images of OH-PLIF simultaneously with 2-D PIV measurements in an inverse methane diffusion flame. Under a constant fuel flow rate, the central air jet Re was varied, leading to air to fuel velocity ratio, Vr, to vary from 8.3 to 66.5. Starting from Vr = 20.7, the flame is commonly characterized by three distinct zones. The length of the lower fuel entrainment region is inversely proportional to Vr. The flames investigated resemble a string shear layer confining this zone, and converging into the second distinct region, the flame neck zone. The third region is the rest of the flame, which spreads in a jet-like manner. The inverse diffusion flames exhibit varying degrees of partial premixing, depending upon on the velocity ratio Vr, and this region of partial premixing evolves into a well-mixed reaction zone along the flame centerline. The OH distribution correlated with the changes in the mean characteristics of the flow through reduction in the local Reynolds number due to heat release. The existence of a flame suppresses or laminarizes the turbulence at early axial locations and promotes fluctuations at the flame tip for flames with Vr < 49.8. In addition, the flame jet width can be correlated to the OH distribution. In upstream regions of the flames, the breaks in OH are counterbalanced by flame closures and are governed by edge flame propagation. These local extinctions were found to occur at locations where large flow structures were impinging on the flame and are associated with a locally higher strain rate or correlated to the local high strain rates at the flame hole edges without this flow impinging. Another contributor to re-ignition was found to be growing flame kernels. As the flames approach global blow-off, these kernels become the main mechanism for re-ignition further downstream of the flames. At low Vr, laminarization within the early regions of the flame provides an effective shield, preventing the jet flow from

  18. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Donn McGuire; Steve Runyon; Richard Sigal; Bill Liddell; Thomas Williams; George Moridis

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is in the final stages of a cost-shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. Hot Ice No. 1 was planned to test the Ugnu and West Sak sequences for gas hydrates and a concomitant free gas accumulation on Anadarko's 100% working interest acreage in section 30 of Township 9N, Range 8E of the Harrison Bay quadrangle of the North Slope of Alaska. The Ugnu and West Sak intervals are favorably positioned in the hydrate-stability zone over an area extending from Anadarko's acreage westward to the vicinity of the aforementioned gas-hydrate occurrences. This suggests that a large, north-to-south trending gas-hydrate accumulation may exist in that area. The presence of gas shows in the Ugnu and West Sak reservoirs in wells situated eastward and down dip of the Hot Ice location indicate that a free-gas accumulation may be trapped by gas hydrates. The Hot Ice No. 1 well was designed to core from the surface to the base of the West Sak interval using the

  19. Patterns of methane production in a Burmese (Myanmar) population.

    Science.gov (United States)

    Bolin, T D; Genge, J R; Duncombe, V M; Soe-Aung; Myo-Khin

    1996-01-01

    While up to 50% of Western populations produce methane, this is less than that of rural black Africans and there is no information on methane production in populations from Asian developing countries. Females consistently produce methane more commonly than males, and methane production in children under the age of five years, except in Nigeria, is unusual. Breath methane was sampled in 1426 subjects from Myanmar ranging in age from 1 month to 88 years, with a mean age of 26.2 years. Half (49.8%) of the Myanmar population produced methane, this figure comprising 53% of females and 46% of males sampled. Methane production increases with age and reaches adult levels after 10 years of age. A high prevalence of methane production was found in children under 3 years of age (15.8%). Methane production was absent in 13 solely breast-fed children and increased as other food was introduced into the diet. There was an association of methane production within families and with smoking. The prevalence of methane production increased in male and female smokers, with 75% of smokers producing methane. Methane production was not associated with occupation, education, income, water source, latrine type, previous diarrhoea, antibiotic usage or socio-economic status.

  20. Episodic grammar: a computational model of the interaction between episodic and semantic memory in language processing

    NARCIS (Netherlands)

    Borensztajn, G.; Zuidema, W.; Carlson, L.; Hoelscher, C.; Shipley, T.F.

    2011-01-01

    We present a model of the interaction of semantic and episodic memory in language processing. Our work shows how language processing can be understood in terms of memory retrieval. We point out that the perceived dichotomy between rule-based versus exemplar-based language modelling can be

  1. Effect of thermal, acid, alkaline and alkaline-peroxide pretreatments on the biochemical methane potential and kinetics of the anaerobic digestion of wheat straw and sugarcane bagasse.

    Science.gov (United States)

    Bolado-Rodríguez, Silvia; Toquero, Cristina; Martín-Juárez, Judit; Travaini, Rodolfo; García-Encina, Pedro Antonio

    2016-02-01

    The effect of thermal, acid, alkaline and alkaline-peroxide pretreatments on the methane produced by the anaerobic digestion of wheat straw (WS) and sugarcane bagasse (SCB) was studied, using whole slurry and solid fraction. All the pretreatments released formic and acetic acids and phenolic compounds, while 5-hydroxymetilfurfural (HMF) and furfural were generated only by acid pretreatment. A remarkable inhibition was found in most of the whole slurry experiments, except in thermal pretreatment which improved methane production compared to the raw materials (29% for WS and 11% for SCB). The alkaline pretreatment increased biodegradability (around 30%) and methane production rate of the solid fraction of both pretreated substrates. Methane production results were fitted using first order or modified Gompertz equations, or a novel model combining both equations. The model parameters provided information about substrate availability, controlling step and inhibitory effect of compounds generated by each pretreatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Analysis of Influence of Goaf Sealing from Tailgate On the Methane Concentration at the Outlet from the Longwall

    Science.gov (United States)

    Tutak, Magdalena; Brodny, Jaroslaw

    2017-12-01

    One of the most common and most dangerous gas hazards in underground coal mine is methane hazard. Formation of dangerous, explosive concentrations of methane occurs the most often in the region of crossing of longwall with the ventilation gallery. Particularly it applies to longwalls ventilated in „U from bounds” system. Outflow of gases from the goaf to the tailgate takes place through the boundary surfaces of this sidewalk with goaf. Main cause of this process is a phenomenon of air filtration through the goaf with caving. This filtration is a result of migration of the part of ventilation air stream supplied to the longwall. This air is released into the goaf on the entire longwall length; however, its greater amount gets to the goaf with caving space at the crossing of maingate with exploitation longwall. Albeit, the biggest outflow of air mixture and gases from the goaf occurs in top gate in upper corner of the longwall. This is a result of pressure difference in this region. This phenomenon causes that to the space of heading besides the air also other gases present in the goaf, mainly methane, are released. Methane is an explosive gas. Most often boundaries of explosive mixtures of methane, air and inert gases are described by the so-called Coward triangle explosion. Within the limits of the occurrence of the concentration of explosive methane explosion initials may be endogenous fire, blasting or sparks arising from friction of moving lumps of rock. Therefore, in order to decrease its concertation in this region, by limiting its outflow from the goaf with caving different actions are taken. One of such action is sealing of goaf from top gate side. Analysis of impact of sealing of these goaf on the methane concentration at the outlet of longwall is main aim of studies researches. Model of tested region, together with boundary conditions (including parameters of flowing air and the methane content) was developed on the base of real data from one of the

  3. Hydrogen Recovery by ECR Plasma Pyrolysis of Methane Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Development of a microgravity and hypogravity compatible microwave plasma methane pyrolysis reactor is proposed to recover hydrogen which is lost as methane in the...

  4. Dimensions of aggression: the perception of aggressive episodes.

    Science.gov (United States)

    Forgas, J P; Brown, L B; Menyhart, J

    1980-09-01

    The perception of real-life aggressive episodes was studied, in order to (a) represent the cognitive dimensions used by judges to differentiate between such episodes, (b) to evaluate the perceived differences between different categories of episodes, and (c) to assess the effects of the judges' age, sex and attitudes on their cognitive representation of aggressive episodes. Judgements of 22 aggressive episodes selected from a free-response pilot study were analysed by Carroll & Chang's (1970) INDSCAL procedure, and differences between categories of episodes and groups of judges were evaluated by multiple discriminant analyses. Results indicated that (a) four cognitive dimensions, probability of occurrence, justifiability, emotional provocation, and control, defined the psychological map for aggressive episodes; (b) domestic against public, drunken and non-drunken, criminal against non-criminal episodes were significantly differentiated in this perceptual space; (c) the judges' age, sex and Machiavellism scores were related to their perception of such episodes. The results are discussed in terms of the importance of implicit perceptions of aggression and crime in the criminal justice system. Specifically, it is suggested that similar techniques could be used to (a) gauge popular perceptions of crime as an input to the legislative process, and (b) for the study of perceptions of aggressive episodes by such crucial groups in the criminal justice system as policemen, judges, jury members, victims and offenders.

  5. Process-based modelling of the methane balance in periglacial landscapes (JSBACH-methane)

    Science.gov (United States)

    Kaiser, Sonja; Göckede, Mathias; Castro-Morales, Karel; Knoblauch, Christian; Ekici, Altug; Kleinen, Thomas; Zubrzycki, Sebastian; Sachs, Torsten; Wille, Christian; Beer, Christian

    2017-01-01

    A detailed process-based methane module for a global land surface scheme has been developed which is general enough to be applied in permafrost regions as well as wetlands outside permafrost areas. Methane production, oxidation and transport by ebullition, diffusion and plants are represented. In this model, oxygen has been explicitly incorporated into diffusion, transport by plants and two oxidation processes, of which one uses soil oxygen, while the other uses oxygen that is available via roots. Permafrost and wetland soils show special behaviour, such as variable soil pore space due to freezing and thawing or water table depths due to changing soil water content. This has been integrated directly into the methane-related processes. A detailed application at the Samoylov polygonal tundra site, Lena River Delta, Russia, is used for evaluation purposes. The application at Samoylov also shows differences in the importance of the several transport processes and in the methane dynamics under varying soil moisture, ice and temperature conditions during different seasons and on different microsites. These microsites are the elevated moist polygonal rim and the depressed wet polygonal centre. The evaluation shows sufficiently good agreement with field observations despite the fact that the module has not been specifically calibrated to these data. This methane module is designed such that the advanced land surface scheme is able to model recent and future methane fluxes from periglacial landscapes across scales. In addition, the methane contribution to carbon cycle-climate feedback mechanisms can be quantified when running coupled to an atmospheric model.

  6. Source Attribution of Methane Emissions in Northeastern Colorado Using Ammonia to Methane Emission Ratios

    Science.gov (United States)

    Eilerman, S. J.; Neuman, J. A.; Peischl, J.; Aikin, K. C.; Ryerson, T. B.; Perring, A. E.; Robinson, E. S.; Holloway, M.; Trainer, M.

    2015-12-01

    Due to recent advances in extraction technology, oil and natural gas extraction and processing in the Denver-Julesburg basin has increased substantially in the past decade. Northeastern Colorado is also home to over 250 concentrated animal feeding operations (CAFOs), capable of hosting over 2 million head of ruminant livestock (cattle and sheep). Because of methane's high Global Warming Potential, quantification and attribution of methane emissions from oil and gas development and agricultural activity are important for guiding greenhouse gas emission policy. However, due to the co-location of these different sources, top-down measurements of methane are often unable to attribute emissions to a specific source or sector. In this work, we evaluate the ammonia:methane emission ratio directly downwind of CAFOs using a mobile laboratory. Several CAFOs were chosen for periodic study over a 12-month period to identify diurnal and seasonal variation in the emission ratio as well as differences due to livestock type. Using this knowledge of the agricultural ammonia:methane emission ratio, aircraft measurements of ammonia and methane over oil and gas basins in the western US during the Shale Oil and Natural Gas Nexus (SONGNEX) field campaign in March and April 2015 can be used for source attribution of methane emissions.

  7. Simulations of atmospheric methane for Cape Grim, Tasmania, to constrain southeastern Australian methane emissions

    Directory of Open Access Journals (Sweden)

    Z. M. Loh

    2015-01-01

    Full Text Available This study uses two climate models and six scenarios of prescribed methane emissions to compare modelled and observed atmospheric methane between 1994 and 2007, for Cape Grim, Australia (40.7° S, 144.7° E. The model simulations follow the TransCom-CH4 protocol and use the Australian Community Climate and Earth System Simulator (ACCESS and the CSIRO Conformal-Cubic Atmospheric Model (CCAM. Radon is also simulated and used to reduce the impact of transport differences between the models and observations. Comparisons are made for air samples that have traversed the Australian continent. All six emission scenarios give modelled concentrations that are broadly consistent with those observed. There are three notable mismatches, however. Firstly, scenarios that incorporate interannually varying biomass burning emissions produce anomalously high methane concentrations at Cape Grim at times of large fire events in southeastern Australia, most likely due to the fire methane emissions being unrealistically input into the lowest model level. Secondly, scenarios with wetland methane emissions in the austral winter overestimate methane concentrations at Cape Grim during wintertime while scenarios without winter wetland emissions perform better. Finally, all scenarios fail to represent a~methane source in austral spring implied by the observations. It is possible that the timing of wetland emissions in the scenarios is incorrect with recent satellite measurements suggesting an austral spring (September–October–November, rather than winter, maximum for wetland emissions.

  8. Risk Factors for a Second Episode of Hemoptysis

    Directory of Open Access Journals (Sweden)

    Nobuhiko Seki

    2009-01-01

    Full Text Available Objectives Hemoptysis is an alarming symptom of underlying lung disease. Clinicians are often unsure how to deal with and follow up patients who have had a single episode of hemoptysis, especially if the cause remains unknown despite thorough examination, because a second, more severe episode of hemoptysis might occur despite an apparently stable condition. Investigations were done, using multivariate analyses, to see whether several clinical factors present during an initial episode of hemoptysis could be used to predict a second episode. Subjects and Methods Eighty patients with an initial episode of hemoptysis who underwent both computed tomographic and bronchoscopic examinations from 2003 through 2005 were reviewed. Results The isolation of bacteria from bronchial lavage fluid (odds ratio 13.5, P = 0.001 and the failure to determine the cause of the initial episode of hemoptysis (odds ratio 7.0, P = 0.014 were significant independent predictors of a second episode of hemoptysis. Subset analysis showed that isolation of either Pseudomonas aeruginosa or Haemophilus influenzae increased the likelihood of a second episode of hemoptysis (P = 0.077, even if colonization, representing host-bacterial equilibrium, had occurred. Furthermore, the failure to determine the etiology of an initial episode of hemoptysis was associated with an increased risk of a massive second episode (P = 0.042, regardless of the volume of the initial episode. Conclusions In patients with bacterial colonization of the respiratory tract or an initial episode of hemoptysis of unknown etiology, there is an increased possibility of a second episode of hemoptysis.

  9. Prolonged Eyelid Closure Episodes during Sleep Deprivation in Professional Drivers.

    Science.gov (United States)

    Alvaro, Pasquale K; Jackson, Melinda L; Berlowitz, David J; Swann, Philip; Howard, Mark E

    2016-08-15

    Real life ocular measures of drowsiness use average blink duration, amplitude and velocity of eyelid movements to reflect drowsiness in drivers. However, averaged data may conceal the variability in duration of eyelid closure episodes, and more prolonged episodes that indicate higher levels of drowsiness. The current study aimed to describe the frequency and duration of prolonged eyelid closure episodes during acute sleep deprivation. Twenty male professional drivers (mean age ± standard deviation = 41.9 ± 8.3 years) were recruited from the Transport Workers Union newsletter and newspaper advertisements in Melbourne, Australia. Each participant underwent 24 hours of sleep deprivation and completed a simulated driving task (AusEd), the Psychomotor Vigilance Task, and the Karolinska Sleepiness Scale. Eyelid closure episodes during the driving task were recorded and analyzed manually from digital video recordings. Eyelid closure episodes increased in frequency and duration with a median of zero s/h of eyelid closure after 3 h increasing to 34 s/h after 23 h awake. Eyelid closure episodes were short and infrequent from 3 to 14 h of wakefulness. After 17 h of sleep deprivation, longer and more frequent eyelid closure episodes began to occur. Episodes lasting from 7 seconds up to 18 seconds developed after 20 h of wakefulness. Length of eyelid closure episodes was moderately to highly correlated with the standard deviation of lateral lane position, braking reaction time, crashes, impaired vigilance, and subjective sleepiness. The frequency and duration of episodes of prolonged eyelid closure increases during acute sleep deprivation, with very prolonged episodes after 17 hours awake. Automated devices that assess drowsiness using averaged measures of eyelid closure episodes need to be able to detect prolonged eyelid closure episodes that occur during more severe sleep deprivation. © 2016 American Academy of Sleep Medicine.

  10. Methane hydrates in nature - Current knowledge and challenges

    Science.gov (United States)

    Collett, Timothy S.

    2014-01-01

    Recognizing the importance of methane hydrate research and the need for a coordinated effort, the United States Congress enacted the Methane Hydrate Research and Development Act of 2000. At the same time, the Ministry of International Trade and Industry in Japan launched a research program to develop plans for a methane hydrate exploratory drilling project in the Nankai Trough. India, China, the Republic of Korea, and other nations also have established large methane hydrate research and development programs. Government-funded scientific research drilling expeditions and production test studies have provided a wealth of information on the occurrence of methane hydrates in nature. Numerous studies have shown that the amount of gas stored as methane hydrates in the world may exceed the volume of known organic carbon sources. However, methane hydrates represent both a scientific and technical challenge, and much remains to be learned about their characteristics and occurrence in nature. Methane hydrate research in recent years has mostly focused on: (1) documenting the geologic parameters that control the occurrence and stability of methane hydrates in nature, (2) assessing the volume of natural gas stored within various methane hydrate accumulations, (3) analyzing the production response and characteristics of methane hydrates, (4) identifying and predicting natural and induced environmental and climate impacts of natural methane hydrates, (5) analyzing the methane hydrate role as a geohazard, (6) establishing the means to detect and characterize methane hydrate accumulations using geologic and geophysical data, and (7) establishing the thermodynamic phase equilibrium properties of methane hydrates as a function of temperature, pressure, and gas composition. The U.S. Department of Energy (DOE) and the Consortium for Ocean Leadership (COL) combined their efforts in 2012 to assess the contributions that scientific drilling has made and could continue to make to advance

  11. Year-round methane emissions from permafrost in a North-east Siberian region

    Science.gov (United States)

    Castro-Morales, Karel; Kaiser, Sonja; Kleinen, Thomas; Kwon, Min Jung; Kittler, Fanny; Zaehle, Sönke; Beer, Christian; Göckede, Mathias

    2017-04-01

    In recent decades, permafrost regions in northern latitudes are thawing as a response of climate warming. Soils in permafrost areas contain vast amounts of organic material that is released into the environment after thaw, providing new labile material for bacterial decomposition. As a result, higher production of methane in the anoxic soil layers and within anaerobic wetlands is anticipated, and this will be further released to the atmosphere. In order to assess the current large-scale methane emissions from a wetland permafrost-thaw affected area, we present results of year-round simulated methane emissions at regional scale for a section at the Russian far Northeast in Siberia, located in the low Arctic tundra and characterized by continuous permafrost. For this we use a newly developed process-based methane model built in the framework of the land surface model JSBACH. The model contains explicit permafrost processes and an improved representation of the horizontal extent of wetlands with a hydrological model (TOPMODEL). Model simulated distribution and horizontal extent of wetlands is evaluated against high-resolution remote sensing data. Total and individual regional methane emissions by ebullition, molecular diffusion, plant-mediated and emissions through snow are presented for 2014 and 2015. The model shows a reasonable seasonal transition between the individual methane emission paths. Most of the methane emissions to the atmosphere occur in summer (July, August, September), with the peak of the emissions during August. In this month, plant-mediated transport is the dominant emission path with about 15 mg CH4 m-2 d-1 in 2014, followed by ebullition (7 mg CH4 m-2 d-1) accounting for about half of the emissions thorough plants. Molecular diffusion is a minor contributor with only 0.006 mg CH4 m-2 d-1 at the peak of the summer emissions. Methane emissions through snow occur only during spring, fall and winter months, with higher emissions in spring and autumn

  12. Direct use of methane in coal liquefaction

    Science.gov (United States)

    Sundaram, M.S.; Steinberg, M.

    1985-06-19

    This invention relates to a process for converting solid carbonaceous material, such as coal, to liquid and gaseous hydrocarbons utilizing methane, generally at a residence time of about 20 to 120 minutes at a temperature of 250 to 750/sup 0/C, preferably 350 to 450/sup 0/C, pressurized up to 6000 psi, and preferably in the 1000 to 2500 psi range, preferably directly utilizing methane 50 to 100% by volume in a mix of methane and hydrogen. A hydrogen donor solvent or liquid vehicle such as tetralin, tetrahydroquinoline, piperidine, and pyrolidine may be used in a slurry mix where the solvent feed is 0 to 100% by weight of the coal or carbonaceous feed. Carbonaceous feed material can either be natural, such as coal, wood, oil shale, petroleum, tar sands, etc., or man-made residual oils, tars, and heavy hydrocarbon residues from other processing systems. 1 fig.

  13. High-pressure oxidation of methane

    DEFF Research Database (Denmark)

    Hashemi, Hamid; Christensen, Jakob Munkholt; Gersen, Sander

    2016-01-01

    Methane oxidation at high pressures and intermediate temperatures was investigated in a laminar flow reactor and in a rapid compression machine (RCM). The flow-reactor experiments were conducted at 700–900 K and 100 bar for fuel-air equivalence ratios (Φ) ranging from 0.06 to 19.7, all highly...... diluted in nitrogen. It was found that under the investigated conditions, the onset temperature for methane oxidation ranged from 723 K under reducing conditions to 750 K under stoichiometric and oxidizing conditions. The RCM experiments were carried out at pressures of 15–80 bar and temperatures of 800......–1250 K under stoichiometric and fuel-lean (Φ=0.5) conditions. Ignition delays, in the range of 1–100 ms, decreased monotonically with increasing pressure and temperature. A chemical kinetic model for high-pressure methane oxidation was established, with particular emphasis on the peroxide chemistry...

  14. Biogas and Methane Yield from Rye Grass

    Directory of Open Access Journals (Sweden)

    Tomáš Vítěz

    2015-01-01

    Full Text Available Biogas production in the Czech Republic has expanded substantially, including marginal regions for maize cultivation. Therefore, there are increasingly sought materials that could partially replace maize silage, as a basic feedstock, while secure both biogas production and its quality.Two samples of rye grass (Lolium multiflorum var. westerwoldicum silage with different solids content 21% and 15% were measured for biogas and methane yield. Rye grass silage with solid content of 15% reached an average specific biogas yield 0.431 m3·kg−1 of organic dry matter and an average specific methane yield 0.249 m3·kg−1 of organic dry matter. Rye grass silage with solid content 21% reached an average specific biogas yield 0.654 m3·kg−1 of organic dry matter and an average specific methane yield 0.399 m3·kg−1 of organic dry matter.

  15. Chemical release module facility

    Science.gov (United States)

    Reasoner, D. L.

    1980-01-01

    The chemical release module provides the capability to conduct: (1) thermite based metal vapor releases; (2) pressurized gas releases; (3) dispersed liquid releases; (4) shaped charge releases from ejected submodules; and (5) diagnostic measurements with pi supplied instruments. It also provides a basic R-F and electrical system for: (1) receiving and executing commands; (2) telemetering housekeeping data; (3) tracking; (4) monitoring housekeeping and control units; and (5) ultrasafe disarming and control monitoring.

  16. Impact of an historic underground gas well blowout on the current methane chemistry in a shallow groundwater system.

    Science.gov (United States)

    Schout, Gilian; Hartog, Niels; Hassanizadeh, S Majid; Griffioen, Jasper

    2018-01-09

    Blowouts present a small but genuine risk when drilling into the deep subsurface and can have an immediate and significant impact on the surrounding environment. Nevertheless, studies that document their long-term impact are scarce. In 1965, a catastrophic underground blowout occurred during the drilling of a gas well in The Netherlands, which led to the uncontrolled release of large amounts of natural gas from the reservoir to the surface. In this study, the remaining impact on methane chemistry in the overlying aquifers was investigated. Methane concentrations higher than 10 mg/L ( n = 12) were all found to have δ 13 C-CH 4 values larger than -30‰, typical of a thermogenic origin. Both δ 13 C-CH 4 and δD-CH 4 correspond to the isotopic composition of the gas reservoir. Based on analysis of local groundwater flow conditions, this methane is not a remnant but most likely the result of ongoing leakage from the reservoir as a result of the blowout. Progressive enrichment of both δ 13 C-CH 4 and δD-CH 4 is observed with increasing distance and decreasing methane concentrations. The calculated isotopic fractionation factors of ε C = 3 and ε D = 54 suggest anaerobic methane oxidation is partly responsible for the observed decrease in concentrations. Elevated dissolved iron and manganese concentrations at the fringe of the methane plume show that oxidation is primarily mediated by the reduction of iron and manganese oxides. Combined, the data reveal the long-term impact that underground gas well blowouts may have on groundwater chemistry, as well as the important role of anaerobic oxidation in controlling the fate of dissolved methane. Copyright © 2018 the Author(s). Published by PNAS.

  17. Depressive symptoms in first-episode psychosis

    DEFF Research Database (Denmark)

    Sönmez, Nasrettin; Røssberg, Jan Ivar; Evensen, Julie

    2016-01-01

    AIMS: The present study examined if any patient characteristics at baseline predicted depressive symptoms at 10 years and whether patients prone to depressive symptoms in the first year of treatment had a different prognosis in the following years. METHOD: A total of 299 first-episode psychosis...... (FEP) patients with schizophrenia spectrum disorders were assessed for depressive symptoms with PANSS depression item (g6) at baseline, and 1, 2, 5 and 10 years of follow up. At 10 years, depressive symptoms were also assessed with Calgary Depression Scale for Schizophrenia (CDSS). A PANSS g6 ≥ 4......: Depressive symptoms are frequent among FEP patients at baseline but decrease after treatment because their general symptoms have been initiated. Patients with poor social functioning in childhood and alcohol use at baseline are more prone to have depressive symptoms at 10 years of follow up. Patients...

  18. Certain number-theoretic episodes in algebra

    CERN Document Server

    Sivaramakrishnan, R

    2006-01-01

    Many basic ideas of algebra and number theory intertwine, making it ideal to explore both at the same time. Certain Number-Theoretic Episodes in Algebra focuses on some important aspects of interconnections between number theory and commutative algebra. Using a pedagogical approach, the author presents the conceptual foundations of commutative algebra arising from number theory. Self-contained, the book examines situations where explicit algebraic analogues of theorems of number theory are available. Coverage is divided into four parts, beginning with elements of number theory and algebra such as theorems of Euler, Fermat, and Lagrange, Euclidean domains, and finite groups. In the second part, the book details ordered fields, fields with valuation, and other algebraic structures. This is followed by a review of fundamentals of algebraic number theory in the third part. The final part explores links with ring theory, finite dimensional algebras, and the Goldbach problem.

  19. Episodic acidification of Adirondack lakes during snowmelt

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, D.A.; Driscoll, C.T.; Van Dreason, R.; Yatsko, C.P.

    1990-07-01

    Maximum values of acid neutralizing capacity (ANC) in Adirondack, New York lake outlets generally occur during summer and autumn. During spring snowmelt, transport of acidic water through acid-sensitive watersheds causes depression of upper lake water ANC. In some systems lake outlet ANC reaches negative values. The authors examined outlet water chemistry from II Adirondack lakes during 1986 and 1987 snowmelts. In these lakes, SO concentrations were diluted during snowmelt and did not depress ANC. For lakes with high baseline ANC values, springtime ANC depressions were primarily accompanied by basic cation dilution. For lakes with low baseline ANC, No increases dominated ANC depressions. Lakes with intermediate baseline ANC were affected by both processes and exhibited larger ANC depressions. Ammonium dilution only affected wetland systems. A model predicting a linear relationship between outlet water ANC minima and autumn ANC was inappropriate. To assess watershed response to episodic acidification, hydrologic flow paths must be considered. (Copyright (c) 1990 by the American Geophysical Union.)

  20. Personality disorders in first-episode psychosis

    DEFF Research Database (Denmark)

    Simonsen, Erik; Haahr, Ulrik; Mortensen, Erik Lykke

    2008-01-01

    The aim of the study was to determine the prevalence of personality disorders in the early course of fi rst-episode psychosis and their likely presence in the premorbid period. Fifty-fi ve patients were enrolled at baseline and premorbid function was evaluated by the Premorbid Adjustment Scale....... Thirty-three of these of the patients were assessed at two-year follow-up for comorbid personality disorders by the Structured Clinical Interview for DSM-IV Personality Disorders and by the self-report instrument Millon Clinical Multiaxial Inventory-II. Half of the patients met the criteria of two...... or more personality disorders, while one-third of the patients did not fulfi l the criteria for any personality disorder. The schizoid and the avoidant were the most frequent per- sonality disorders and both were associated with social withdrawal during childhood and adolescence. The limitation...

  1. Personality disorders in first-episode psychosis

    DEFF Research Database (Denmark)

    Simonsen, Erik; Haahr, Ulrik; Mortensen, Erik Lykke

    2008-01-01

    The aim of the study was to determine the prevalence of personality disorders in the early course of first-episode psychosis and their likely presence in the premorbid period. Fifty-five patients were enrolled at baseline and premorbid function was evaluated by the Premorbid Adjustment Scale....... Thirty-three of these of the patients were assessed at two-year follow-up for comorbid personality disorders by the Structured Clinical Interview for DSM-IV Personality Disorders and by the self-report instrument Millon Clinical Multiaxial Inventory-II. Half of the patients met the criteria of two...... or more personality disorders, while one-third of the patients did not fulfil the criteria for any personality disorder. The schizoid and the avoidant were the most frequent personality disorders and both were associated with social withdrawal during childhood and adolescence. The limitation of the study...

  2. Emerging Directions in Emotional Episodic Memory

    Science.gov (United States)

    Dolcos, Florin; Katsumi, Yuta; Weymar, Mathias; Moore, Matthew; Tsukiura, Takashi; Dolcos, Sanda

    2017-01-01

    Building upon the existing literature on emotional memory, the present review examines emerging evidence from brain imaging investigations regarding four research directions: (1) Social Emotional Memory, (2) The Role of Emotion Regulation in the Impact of Emotion on Memory, (3) The Impact of Emotion on Associative or Relational Memory, and (4) The Role of Individual Differences in Emotional Memory. Across these four domains, available evidence demonstrates that emotion- and memory-related medial temporal lobe brain regions (amygdala and hippocampus, respectively), together with prefrontal cortical regions, play a pivotal role during both encoding and retrieval of emotional episodic memories. This evidence sheds light on the neural mechanisms of emotional memories in healthy functioning, and has important implications for understanding clinical conditions that are associated with negative affective biases in encoding and retrieving emotional memories. PMID:29255432

  3. Greenhouse Gas Emissions: Quantifying Methane Emissions from Livestock

    OpenAIRE

    Rafiu O. Yusuf; Zainura Z. Noor; Ahmad H. Abba; Mohd Ariffin Abu Hassan; Mohd Fadhil Mohd Din

    2012-01-01

    Problem statement: The rearing of animals for domestic consumption and export invariably lead to the production of methane as a product of digestion. This study investigated the emission of methane from Malaysian livestock between 1980 and 2008. Approach: Seven categories of animals identified were camel, buffalo, sheep, goats, horse, pigs and poultry. The estimation of methane was based on the IPCC Tier 1 and Tier 2 methods. Methane emission from cattle rose by 44% within the period from 45....

  4. Ground and Airborne Methane Measurements with an Optical Parametric Amplifier

    Science.gov (United States)

    Numata, Kenji

    2012-01-01

    We report on ground and airborne atmospheric methane measurements with a differential absorption lidar using an optical parametric amplifier (OPA). Methane is a strong greenhouse gas on Earth and its accurate global mapping is urgently needed to understand climate change. We are developing a nanosecond-pulsed OPA for remote measurements of methane from an Earth-orbiting satellite. We have successfully demonstrated the detection of methane on the ground and from an airplane at approximately 11-km altitude.

  5. Mitigation of methane emission from an old unlined landfill in Klintholm, Denmark using a passive biocover system.

    Science.gov (United States)

    Scheutz, Charlotte; Pedersen, Rasmus Broe; Petersen, Per Haugsted; Jørgensen, Jørgen Henrik Bjerre; Ucendo, Inmaculada Maria Buendia; Mønster, Jacob G; Samuelsson, Jerker; Kjeldsen, Peter

    2014-07-01

    Methane generated at landfills contributes to global warming and can be mitigated by biocover systems relying on microbial methane oxidation. As part of a closure plan for an old unlined landfill without any gas management measures, an innovative biocover system was established. The system was designed based on a conceptual model of the gas emission patterns established through an initial baseline study. The study included construction of gas collection trenches along the slopes of the landfill where the majority of the methane emissions occurred. Local compost materials were tested as to their usefulness as bioactive methane oxidizing material and a suitable compost mixture was selected. Whole site methane emission quantifications based on combined tracer release and downwind measurements in combination with several local experimental activities (gas composition within biocover layers, flux chamber based emission measurements and logging of compost temperatures) proved that the biocover system had an average mitigation efficiency of approximately 80%. The study showed that the system also had a high efficiency during winter periods with temperatures below freezing. An economic analysis indicated that the mitigation costs of the biocover system were competitive to other existing greenhouse gas mitigation options. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Interaction of Paddy Varieties and Compost with Flux of Methane in Tidal Swampland

    Directory of Open Access Journals (Sweden)

    Andin Muhammad Abduh

    2016-09-01

    Full Text Available Paddy variety and organic material have a very important role on the flux of methane (CH4 in rice cultivation, especially in a swamp land. The purpose of this study was to determine the amount of methane emissions released from rice cultivation in acid sulphate soils with the use of different rice straw varieties and composts. This study used a 2 × 2 factorial in a Completely Randomized Design with six replicates. The first factor was rice varieties and the second factor was rice straw compost. The results showed that the smallest emision rate of CH4 occurred when using Inpara 3 variety without rice straw compost of 0.030 mg.m 2. day-1, while the largest occured when using Inpari 30 variety with 5 Mg rice straw compost ha-1 that was equal to 0.571 mg m-2 day-1.

  7. Quantification of the Potential Gross Economic Impacts of Five Methane Reduction Scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Keyser, David [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Warner, Ethan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Curley, Christina [Colorado State Univ., Fort Collins, CO (United States)

    2015-04-23

    Methane (CH4) is a potent greenhouse gas that is released from the natural gas supply chain into the atmosphere as a result of fugitive emissions1 and venting2 . We assess five potential CH4 reduction scenarios from transmission, storage, and distribution (TS&D) using published literature on the costs and the estimated quantity of CH4 reduced. We utilize cost and methane inventory data from ICF (2014) and Warner et al. (forthcoming) as well as data from Barrett and McCulloch (2014) and the American Gas Association (AGA) (2013) to estimate that the implementation of these measures could support approximately 85,000 jobs annually from 2015 to 2019 and reduce CH4 emissions from natural gas TS&D by over 40%. Based on standard input/output analysis methodology, measures are estimated to support over $8 billion in GDP annually over the same time period and allow producers to recover approximately $912 million annually in captured gas.

  8. Methane recovery from landfill in China

    Energy Technology Data Exchange (ETDEWEB)

    Gaolai, L.

    1996-12-31

    GEF has approved a special project for a demonstration project for Methane Recovery from the Urban Refuse Land Fill. This paper will introduce the possibility of GHG reduction from the landfill in China, describe the activities of the GEF project, and the priorities for international cooperation in this field. The Global Environment Facility (GEF) approved the project, China Promoting Methane Recovery and Unlization from Mixed Municipal Refuse, at its Council meeting in last April. This project is the first one supported by international organization in this field.

  9. Morphology of methane hydrate host sediments

    Science.gov (United States)

    Jones, K.W.; Feng, H.; Tomov, S.; Winters, W.J.; Eaton, M.; Mahajan, D.

    2005-01-01

    The morphological features including porosity and grains of methane hydrate host sediments were investigated using synchrotron computed microtomography (CMT) technique. The sediment sample was obtained during Ocean Drilling Program Leg 164 on the Blake Ridge at water depth of 2278.5 m. The CMT experiment was performed at the Brookhaven National Synchrotron Light Source facility. The analysis gave ample porosity, specific surface area, mean particle size, and tortuosity. The method was found to be highly effective for the study of methane hydrate host sediments.

  10. Enteric methane emissions from German dairy cows

    DEFF Research Database (Denmark)

    Dammgen, U; Rosemann, C; Haenel, H D

    2012-01-01

    provided in the IPCC guidelines. The two existing guidelines propose two different constant rates (IPCC, 1996: 6.0 % or 60 kJ MJ(-1), and IPCC, 2006: 6.5 % or 65 kJ MJ(-1), of the gross energy intake, respectively). Both constants do not reflect that the rates should be dependent on feed properties......, as stated by IPCC. A methane emission model was selected here that is based on German feed data. It was combined with the hitherto applied model describing energy requirements. The emission rates thus calculated deviate from those previously obtained. In the new model, the methane conversion rate is back...

  11. Enteric methane emissions from German pigs

    DEFF Research Database (Denmark)

    Dämmgen, Ulrich; Schulz, Joachim; Klausing, Heinrich Kleine

    2012-01-01

    . Meanwhile numerous experimental data on methane emissions from enteric fermentation is available in Germany and abroad; the results are compiled in this work. These results also allow for a description of transformation processes in the hind gut and a subsequent establishment of models that relate emissions...... to feed and performance data. The model by Kirchgeßner et al. (1995) is based on German experimental data and reflects typical national diet compositions. It is used to quantify typical emissions and methane conversion ratios. The results agree with other experimental findings at home and abroad...

  12. The emission of methane from UK wetlands

    OpenAIRE

    K. J. Hargreaves; Fowler, D

    1992-01-01

    Sets of peat monoliths have been installed in open-top chambers at ITE and investigations into the factors controlling emission fluxes of methane are being investigated. Emission fluxes in the range 0 to 400 ng m-2 s-1 have been observed. The magnitude of the emission flux is a function of peat temperature in the surface layer and height of the water table. Data from an automatic weather station will permit the modelling of potential changes in methane emux due to changes in climate. ...

  13. A review of oxygen removal from oxygen-bearing coal-mine methane.

    Science.gov (United States)

    Zhao, Peiyu; Zhang, Guojie; Sun, Yinghui; Xu, Ying

    2017-06-01

    In this article, a comparison will be made concerning the advantages and disadvantages of five kinds of coal mine methane (CMM) deoxygenation method, including pressure swing adsorption, combustion, membrane separation, non-metallic reduction, and cryogenic distillation. Pressure swing adsorption has a wide range of application and strong production capacity. To achieve this goal, adsorbent must have high selectivity, adsorption capacity, and adequate adsorption/desorption kinetics, remain stable after several adsorption/desorption cycles, and possess good thermal and mechanical stabilities. Catalytic combustion deoxygenation is a high-temperature exothermic redox chemical reaction, which releases large amounts of thermal energy. So, the stable and accurate control of the temperature is not easy. Meanwhile partial methane is lost. The key of catalytic combustion deoxygenation lies in the development of high-efficiency catalyst. Membrane separation has advantages of high separation efficiency and low energy consumption. However, there are many obstacles, including higher costs. Membrane materials have the requirements of both high permeability and high selectivity. The development of new membrane materials is a key for membrane separation. Cryogenic distillation has many excellence advantages, such as high purity production and high recovery. However, the energy consumption increases with decreasing CH4 concentrations in feed gas. Moreover, there are many types of operational security problems. And that several kinds of deoxygenation techniques mentioned above have an economic value just for oxygen-bearing CMM with methane content above 30%. Moreover, all the above methods are not applicable to deoxygenation of low concentration CMM. Non-metallic reduction method cannot only realize cyclic utilization of deoxidizer but also have no impurity gases generation. It also has a relatively low cost and low loss rate of methane, and the oxygen is removed thoroughly. In

  14. The Methanizer : A Small Scale Biogas Reactor for a Restaurant

    NARCIS (Netherlands)

    Vasudevan, R.; Karlsson, O.; Dhejne, K.; Derewonko, P.; Brezet, J.C.

    2010-01-01

    The purpose of this study is to determine the technical and economic feasibility of a smallscale bioreactor called the Methanizer for a restaurant. The bioreactor converts organic waste produced by the restaurant into methane. This methane can be used to power the restaurant’s cooking stoves. The

  15. Approaches to methane monitoring problem in Ukrainian coal mines

    Energy Technology Data Exchange (ETDEWEB)

    Medvedev, V.N.; Belyaeva, Y.V. [Makeyevka State Safety in Mines Research Institute, Makeyevka (Ukraine)

    1999-07-01

    Methane behaviour in underground workings has been demonstrated, the gas situation at job sites have been classified, and the weakness of existing methane monitoring practice are described. Methods to improve monitoring techniques and practical findings to enhance methane monitoring in coal mines are discussed. 5 refs., 4 figs.

  16. Multiple origins of methane at the Lost City Hydrothermal Field

    Science.gov (United States)

    Bradley, Alexander S.; Summons, Roger E.

    2010-08-01

    The high concentrations of methane in the vent fluids of the Lost City Hydrothermal Field represent the sum of abiotic and biological sources and sinks. Stable isotopes of carbon are of limited value in discriminating between the various sources of methane because the isotope effects associated with the multiple processes forming and consuming methane are each poorly constrained, and the products of these processes are pooled. Furthermore, reservoir effects complicate interpretation: the near quantitative reduction of inorganic carbon to methane under highly reducing conditions limits the isotope effects associated with methanogenesis. However, the carbon isotope compositions of lipids derived from anaerobic methanotrophs suggest that more than one isotopically distinct pool of methane exists at Lost City. In this analysis we integrate multiple lines of evidence to constrain the relative contribution of various processes at Lost City. The processes that we consider here include i) Fischer-Tropsch-type (FTT) abiotic synthesis of methane and other hydrocarbons, ii) the Sabatier process for the abiotic synthesis of methane alone, iii) biological methane production by Methanosarcinales, and iv) biological methane consumption by anaerobic and aerobic methanotrophs. This analysis suggests that abiotic processes, particularly the Sabatier reaction, are likely to be the dominant source of methane at Lost City. Biological methane is present in the vent fluids, but does not compose a high fraction of the total methane pool. These observations imply that ultramafic systems could have supplied abundant reduced carbon to the early Earth, even without biological catalysis.

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

    Science.gov (United States)

    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.

  18. Methane production by sheep and cattle in Australia

    Science.gov (United States)

    Minson, D. J.

    1993-02-01

    Using methane production rates from Australian feeds and local estimates of the quantity of feed eaten by different classes of animal, it was estimated that sheep and cattle in Australia produce 2.66 Tg methane in 1990. This value is 43% higher than previous estimates and indicates a need to reassess the methane production of ruminants in other countries.

  19. Eddy covariance based methane flux in Sundarbans mangroves, India

    Indian Academy of Sciences (India)

    Eddy covariance based methane flux in Sundarbans mangroves, India ... Eddy covariance; mangrove forests; methane flux; Sundarbans. ... In order to quantify the methane flux in mangroves, an eddy covariance flux tower was recently erected in the largest unpolluted and undisturbed mangrove ecosystem in Sundarbans ...

  20. Aquatic herbivores facilitate the emission of methane from wetlands

    NARCIS (Netherlands)

    Dingemans, B.J.J.; Bakker, E.S.; Bodelier, P.L.E.

    2011-01-01

    Wetlands are significant sources of atmospheric methane. Methane produced by microbes enters roots and escapes to the atmosphere through the shoots of emergent wetland plants. Herbivorous birds graze on helophytes, but their effect on methane emission remains unknown. We hypothesized that grazing on