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Sample records for activate methane starting

  1. Enceladus: Starting Hydrothermal Activity

    NASA Technical Reports Server (NTRS)

    Matson, D. L.; Castillo-Rogez, J. C.; Johnson, T. V.; Lunine, J. I.; Davies, A. G.

    2011-01-01

    We describe a process for starting the hydrothermal activity in Enceladus' South Polar Region. The process takes advantage of fissures that reach the water table, about 1 kilometer below the surface. Filling these fissures with fresh ocean water initiates a flow of water up from an ocean that can be self-sustaining. In this hypothesis the heat to sustain the thermal anomalies and the plumes comes from a slightly warm ocean at depth. The heat is brought to the surface by water that circulates up, through the crust and then returns to the ocean.

  2. Methane activation on supported transition metal catalysts

    NASA Astrophysics Data System (ADS)

    Carstens, Jason Ned

    At present, there is considerable interest in utilizing methane more efficiently as both a fuel source and as a starting material for the production of other, more valuable products. However, methane is a very stable molecule with strong C-H bonds that are difficult to break. This makes methane combustion or the formation of carbon-carbon bonds quite difficult. The present work focuses on the use of supported transition metal catalysts as a means of activating methane (i.e. breaking C-H bonds) at low temperatures to produce valuable products or energy. The conversion of methane into higher hydrocarbons. A low temperature (<750 K), direct process to effectively convert methane into higher hydrocarbons would be quite desirable. Such a process is thermodynamically feasible if the reaction is broken up into two separate steps. The first step is the adsorption of methane onto a transition metal catalyst at temperatures above about 600 K to produce a surface carbon species. The second step is a low temperature (<373 K) hydrogenation to convert the carbon species into higher hydrocarbons. T. Koerts et al. have pursued this approach by dissociatively absorbing methane onto silica supported transition metal catalysts at temperatures ranging between 573 K and 773 K. The result was a surface carbonaceous species and hydrogen. In the second step, the carbonaceous intermediates produced small alkanes upon hydrogenation around 373 K. A maximum yield to higher hydrocarbons of 13% was obtained on a ruthenium catalyst. The present study was conducted to further investigate the nature of the carbonaceous species reported by Koerts. Methane combustion. This investigation was conducted in an effort to better understand the mechanism of methane combustion on Pd catalysts. In the first part of this study, temperature programmed reduction (TPR) was used to investigate the oxidation and reduction dynamics of a 10 wt% Pd/ZrOsb2 catalyst used for methane combustion. TPR experiments indicate

  3. Fast start-up reactor for partial oxidation of methane with electrically-heated metallic monolith catalyst

    NASA Astrophysics Data System (ADS)

    Jung, Heon; Yoon, Wang Lai; Lee, Hotae; Park, Jong Soo; Shin, Jang Sik; La, Howon; Lee, Jong Dae

    A palladium-washcoated metallic monolith catalyst is applied to the partial oxidation of methane to syngas. This catalyst is highly active at a gas hourly space velocity (GHSV) of 100,000 h -1. The compact partial oxidation (POX) reactor equipped with both 96 cc of the metallic monolith catalyst and an electrically-heated catalyst (EHC) has a start-up time of less than 1.5 min and a syngas generation capacity of 9.5 Nm 3 h -1. The POX reaction is sustained without the need for an external heater. With the stand-alone POX reactor, the methane conversion can be increased either by preheating the reactant mixture heat-exchanged with the product gas, or by supplying a larger amount of oxygen than is necessary for the reaction stoichiometry.

  4. Activated carbon monoliths for methane storage

    NASA Astrophysics Data System (ADS)

    Chada, Nagaraju; Romanos, Jimmy; Hilton, Ramsey; Suppes, Galen; Burress, Jacob; Pfeifer, Peter

    2012-02-01

    The use of adsorbent storage media for natural gas (methane) vehicles allows for the use of non-cylindrical tanks due to the decreased pressure at which the natural gas is stored. The use of carbon powder as a storage material allows for a high mass of methane stored for mass of sample, but at the cost of the tank volume. Densified carbon monoliths, however, allow for the mass of methane for volume of tank to be optimized. In this work, different activated carbon monoliths have been produced using a polymeric binder, with various synthesis parameters. The methane storage was studied using a home-built, dosing-type instrument. A monolith with optimal parameters has been fabricated. The gravimetric excess adsorption for the optimized monolith was found to be 161 g methane for kg carbon.

  5. Synchronous rapid start-up of the methanation and anammox processes in two-stage ASBRs

    NASA Astrophysics Data System (ADS)

    Duan, Y.; Li, W. R.; Zhao, Y.

    2017-01-01

    The “methanation + anaerobic ammonia oxidation autotrophic denitrification” method was adopted by using anaerobic sequencing batch reactors (ASBRs) and realized a satisfactory synchronous removal of chemical oxygen demand (COD) and ammonia-nitrogen (NH4 +-N) in wastewater after 75 days operation. 90% of COD was removed at a COD load of 1.2 kg/(m3•d) and 90% of TN was removed at a TN load of 0.14 kg/(m3•d). The anammox reaction ratio was estimated to be 1: 1.32: 0.26. The results showed that synchronous rapid start-up of the methanation and anaerobic ammonia oxidation processes in two-stage ASBRs was feasible.

  6. Methane activation and oxidation in sulfuric acid.

    PubMed

    Goeppert, Alain; Dinér, Peter; Ahlberg, Per; Sommer, Jean

    2002-07-15

    The H/D exchange observed when methane is contacted with D(2)SO(4) at 270-330 degrees C shows that the alkane behaves as a sigma base and undergoes rapid and reversible protonation at this temperature. DFT studies of the hydrogen exchange between a monomer and a dimer of sulfuric acid and methane show that the transition states involved in the exchange are bifunctional, that is one hydrogen atom is transferred from a hydroxy group in sulfuric acid to methane, while one hydrogen atom is abstracted from methane by a non-hydroxy oxygen atom in sulfuric acid. All the transition states include a CH(5) moiety, which shows similarities to the methanium ion CH(5) (+). The calculated potential activation energy of the hydrogen exchange for the monomer is 174 kJ mol(-1), which is close to the experimental value (176 kJ mol(-1)). Solvation of the monomer and the transition state of the monomer with an extra sulfuric acid molecule, decrease the potential activation energy by 6 kJ mol(-1). The acid-base process is in competition, however, with an oxidative process involving methane and sulfuric acid which leads to CO(2), SO(2), and water, and thus to a decrease of acidity and loss of reactivity of the medium.

  7. Activation of methane by transition metal-substituted aluminophosphate molecular sieves

    DOEpatents

    Iton, Lennox E.; Maroni, Victor A.

    1991-01-01

    Aluminophosphate molecular sieves substituted with cobalt, manganese or iron and having the AlPO.sub.4 -34 or AlPO.sub.4 -5, or related AlPO.sub.4 structure activate methane starting at approximately 350.degree. C. Between 400.degree. and 500.degree. C. and at methane pressures .ltoreq.1 atmosphere the rate of methane conversion increases steadily with typical conversion efficiencies at 500.degree. C. approaching 50% and selectivity to the production of C.sub.2+ hydrocarbons approaching 100%. The activation mechanism is based on reduction of the transition metal(III) form of the molecular sieve to the transition metal(II) form with accompanying oxidative dehydrogenation of the methane. Reoxidation of the - transition metal(II) form to the transition metal(III) form can be done either chemically (e.g., using O.sub.2) or electrochemically.

  8. Rethinking biological activation of methane and conversion to liquid fuels.

    PubMed

    Haynes, Chad A; Gonzalez, Ramon

    2014-05-01

    If methane, the main component of natural gas, can be efficiently converted to liquid fuels, world reserves of methane could satisfy the demand for transportation fuels in addition to use in other sectors. However, the direct activation of strong C-H bonds in methane and conversion to desired products remains a difficult technological challenge. This perspective reveals an opportunity to rethink the logic of biological methane activation and conversion to liquid fuels. We formulate a vision for a new foundation for methane bioconversion and suggest paths to develop technologies for the production of liquid transportation fuels from methane at high carbon yield and high energy efficiency and with low CO2 emissions. These technologies could support natural gas bioconversion facilities with a low capital cost and at small scales, which in turn could monetize the use of natural gas resources that are frequently flared, vented or emitted.

  9. Biological methane oxidation: regulation, biochemistry, and active site structure of particulate methane monooxygenase.

    PubMed

    Lieberman, Raquel L; Rosenzweig, Amy C

    2004-01-01

    Particulate methane monooxygenase (pMMO) is a three-subunit integral membrane enzyme that catalyzes the oxidation of methane to methanol. Although pMMO is the predominant methane oxidation catalyst in nature, it has proved difficult to isolate, and most questions regarding its molecular structure, active site composition, chemical mechanism, and genetic regulation remain unanswered. Copper ions are believed to play a key role in both pMMO regulation and catalysis, and there is some evidence that the enzyme contains iron as well. A number of research groups have solubilized and purified or partially purified pMMO. These preparations have been characterized by biochemical and biophysical methods. In addition, aspects of methane monooxygenase gene regulation and copper accumulation in methanotrophs have been studied. This review summarizes for the first time the often controversial pMMO literature, focusing on recent progress and highlighting unresolved issues.

  10. African American Preschool Children's Physical Activity Levels in Head Start

    ERIC Educational Resources Information Center

    Shen, Bo; Reinhart-Lee, Tamara; Janisse, Heather; Brogan, Kathryn; Danford, Cynthia; Jen, K-L. C.

    2012-01-01

    The purpose of this study was to describe the physical activity levels of urban inner city preschoolers while attending Head Start, the federally funded preschool program for children from low-income families. Participants were 158 African American children. Their physical activity during Head Start days was measured using programmed RT-3…

  11. Links between methane flux and transcriptional activities of methanogens and methane oxidizers in a blanket peat bog.

    PubMed

    Freitag, Thomas E; Toet, Sylvia; Ineson, Phil; Prosser, James I

    2010-07-01

    The relationship between biogeochemical process rates and microbial functional activity was investigated by analysis of the transcriptional dynamics of the key functional genes for methanogenesis (methyl coenzyme M reductase; mcrA) and methane oxidation (particulate methane monooxygenase; pmoA) and in situ methane flux at two peat soil field sites with contrasting net methane-emitting and -oxidizing characteristics. qPCR was used to quantify the abundances of mcrA and pmoA genes and transcripts at two soil depths. Total methanogen and methanotroph transcriptional dynamics, calculated from mcrA and pmoA gene : transcript abundance ratios, were similar at both sites and depths. However, a linear relationship was demonstrated between surface mcrA and pmoA transcript dynamics and surface flux rates at the methane-emitting and methane-oxidizing sites, respectively. Results indicate that methanotroph activity was at least partially substrate-limited at the methane-emitting site and by other factors at the methane-oxidizing site. Soil depth also contributed to the control of surface methane fluxes, but to a lesser extent. Small differences in the soil water content may have contributed to differences in methanogen and methanotroph activities. This study therefore provides a first insight into the regulation of in situ, field-level surface CH(4) flux at the molecular level by an accurate reflection of gene : transcript abundance ratios for the key genes in methane generation and consumption.

  12. Activation energy of methyl radical decay in methane hydrate.

    PubMed

    Takeya, Kei; Nango, Kouhei; Sugahara, Takeshi; Ohgaki, Kazunari; Tani, Atsushi

    2005-11-10

    The thermal stability of gamma-ray-induced methyl radicals in methane hydrate was studied using the ESR method at atmospheric pressure and 210-260 K. The methyl radical decay proceeded with the second-order reaction, and ethane molecules were generated from the dimerization process. The methyl radical decay proceeds by two different temperature-dependent processes, that is, the respective activation energies of these processes are 20.0 +/- 1.6 kJ/mol for the lower temperature region of 210-230 K and 54.8 +/- 5.7 kJ/mol for the higher temperature region of 235-260 K. The former agrees well with the enthalpy change of methane hydrate dissociation into ice and gaseous methane, while the latter agrees well with the enthalpy change into liquid water and gaseous methane. The present findings reveal that methane hydrates dissociate into liquid (supercooled) water and gaseous methane in the temperature range of 235-260 K.

  13. Methane-induced Activation Mechanism of Fused Ferric Oxide-Alumina Catalysts during Methane Decomposition.

    PubMed

    Reddy Enakonda, Linga; Zhou, Lu; Saih, Youssef; Ould-Chikh, Samy; Lopatin, Sergei; Gary, Daniel; Del-Gallo, Pascal; Basset, Jean-Marie

    2016-08-09

    Activation of Fe2 O3 -Al2 O3 with CH4 (instead of H2 ) is a meaningful method to achieve catalytic methane decomposition (CMD). This reaction of CMD is more economic and simple against commercial methane steam reforming (MSR) as it produces COx -free H2 . In this study, for the first time, structure changes of the catalyst were screened during CH4 reduction with time on stream. The aim was to optimize the pretreatment conditions through understanding the activation mechanism. Based on results from various characterization techniques, reduction of Fe2 O3 by CH4 proceeds in three steps: Fe2 O3 →Fe3 O4 →FeO→Fe0. Once Fe0 is formed, it decomposes CH4 with formation of Fe3 C, which is the crucial initiation step in the CMD process to initiate formation of multiwall carbon nanotubes.

  14. Start-Up of an Anaerobic Dynamic Membrane Digester for Waste Activated Sludge Digestion: Temporal Variations in Microbial Communities

    PubMed Central

    Yu, Hongguang; Wang, Qiaoying; Wang, Zhiwei; Sahinkaya, Erkan; Li, Yongli; Ma, Jinxing; Wu, Zhichao

    2014-01-01

    An anaerobic dynamic membrane digester (ADMD) was developed to digest waste sludge, and pyrosequencing was used to analyze the variations of the bacterial and archaeal communities during the start-up. Results showed that bacterial community richness decreased and then increased over time, while bacterial diversity remained almost the same during the start-up. Proteobacteria and Bacteroidetes were the major phyla. At the class level, Betaproteobacteria was the most abundant at the end of start-up, followed by Sphingobacteria. In the archaeal community, richness and diversity peaked at the end of the start-up stage. Principle component and cluster analyses demonstrated that archaeal consortia experienced a distinct shift and became stable after day 38. Methanomicrobiales and Methanosarcinales were the two predominant orders. Further investigations indicated that Methanolinea and Methanosaeta were responsible for methane production in the ADMD system. Hydrogenotrophic pathways might prevail over acetoclastic means for methanogenesis during the start-up, supported by specific methanogenic activity tests. PMID:24695488

  15. Methane, benzene and alkyl benzene cold start emission data of gasoline-driven passenger cars representing the vehicle technology of the last two decades

    NASA Astrophysics Data System (ADS)

    Heeb, Norbert V.; Forss, Anna-Maria; Saxer, Christian J.; Wilhelm, Patrick

    The US urban driving cycle (FTP-75) is widely used to estimate both the emissions under hot engine conditions as well as those associated with the cold start. Applying fast analysis techniques such as chemical ionization mass spectrometry (CI-MS) the warm-up behavior of individual vehicles can be monitored at a time resolution of 1 s. CI-MS has been used to investigate the emissions of methane, benzene and the alkyl benzene class of compounds. The amount of the emissions at cold start influence was deduced from the time-resolved emission data of four gasoline-driven vehicle classes representing the vehicle technology of the last two decades. Overall, the emissions of five EURO-0, 20 EURO-1, 18 EURO-2 and so far of six EURO-3 passenger cars were recorded. The test vehicles were selected from the currently operating Swiss car fleet based on the car sales statistics. The average methane, benzene and alkyl benzene cold start emissions are reported using both, the traditional bag method as well as the regression model. At room temperature a clear reduction of 94%, 81% and 85% was found for the methane, benzene and alkyl benzene cold start emissions from EURO-0 to EURO-3 technology, respectively.

  16. Zero Valent Iron Significantly Enhances Methane Production from Waste Activated Sludge by Improving Biochemical Methane Potential Rather Than Hydrolysis Rate

    NASA Astrophysics Data System (ADS)

    Liu, Yiwen; Wang, Qilin; Zhang, Yaobin; Ni, Bing-Jie

    2015-02-01

    Anaerobic digestion has been widely applied for waste activated sludge (WAS) treatment. However, methane production from anaerobic digestion of WAS is usually limited by the slow hydrolysis rate and/or poor biochemical methane potential of WAS. This work systematically studied the effects of three different types of zero valent iron (i.e., iron powder, clean scrap and rusty scrap) on methane production from WAS in anaerobic digestion, by using both experimental and mathematical approaches. The results demonstrated that both the clean and the rusty iron scrap were more effective than the iron powder for improving methane production from WAS. Model-based analysis showed that ZVI addition significantly enhanced methane production from WAS through improving the biochemical methane potential of WAS rather than its hydrolysis rate. Economic analysis indicated that the ZVI-based technology for enhancing methane production from WAS is economically attractive, particularly considering that iron scrap can be freely acquired from industrial waste. Based on these results, the ZVI-based anaerobic digestion process of this work could be easily integrated with the conventional chemical phosphorus removal process in wastewater treatment plant to form a cost-effective and environment-friendly approach, enabling maximum resource recovery/reuse while achieving enhanced methane production in wastewater treatment system.

  17. Polyhydroxyalkanoates in waste activated sludge enhances anaerobic methane production through improving biochemical methane potential instead of hydrolysis rate

    NASA Astrophysics Data System (ADS)

    Wang, Qilin; Sun, Jing; Zhang, Chang; Xie, Guo-Jun; Zhou, Xu; Qian, Jin; Yang, Guojing; Zeng, Guangming; Liu, Yiqi; Wang, Dongbo

    2016-01-01

    Anaerobic sludge digestion is the main technology for sludge reduction and stabilization prior to sludge disposal. Nevertheless, methane production from anaerobic digestion of waste activated sludge (WAS) is often restricted by the poor biochemical methane potential and slow hydrolysis rate of WAS. This work systematically investigated the effect of PHA levels of WAS on anaerobic methane production, using both experimental and mathematical modeling approaches. Biochemical methane potential tests showed that methane production increased with increased PHA levels in WAS. Model-based analysis suggested that the PHA-based method enhanced methane production by improving biochemical methane potential of WAS, with the highest enhancement being around 40% (from 192 to 274 L CH4/kg VS added; VS: volatile solid) when the PHA levels increased from 21 to 143 mg/g VS. In contrast, the hydrolysis rate (approximately 0.10 d‑1) was not significantly affected by the PHA levels. Economic analysis suggested that the PHA-based method could save $1.2/PE/y (PE: population equivalent) in a typical wastewater treatment plant (WWTP). The PHA-based method can be easily integrated into the current WWTP to enhance methane production, thereby providing a strong support to the on-going paradigm shift in wastewater management from pollutant removal to resource recovery.

  18. Zero Valent Iron Significantly Enhances Methane Production from Waste Activated Sludge by Improving Biochemical Methane Potential Rather Than Hydrolysis Rate

    PubMed Central

    Liu, Yiwen; Wang, Qilin; Zhang, Yaobin; Ni, Bing-Jie

    2015-01-01

    Anaerobic digestion has been widely applied for waste activated sludge (WAS) treatment. However, methane production from anaerobic digestion of WAS is usually limited by the slow hydrolysis rate and/or poor biochemical methane potential of WAS. This work systematically studied the effects of three different types of zero valent iron (i.e., iron powder, clean scrap and rusty scrap) on methane production from WAS in anaerobic digestion, by using both experimental and mathematical approaches. The results demonstrated that both the clean and the rusty iron scrap were more effective than the iron powder for improving methane production from WAS. Model-based analysis showed that ZVI addition significantly enhanced methane production from WAS through improving the biochemical methane potential of WAS rather than its hydrolysis rate. Economic analysis indicated that the ZVI-based technology for enhancing methane production from WAS is economically attractive, particularly considering that iron scrap can be freely acquired from industrial waste. Based on these results, the ZVI-based anaerobic digestion process of this work could be easily integrated with the conventional chemical phosphorus removal process in wastewater treatment plant to form a cost-effective and environment-friendly approach, enabling maximum resource recovery/reuse while achieving enhanced methane production in wastewater treatment system. PMID:25652244

  19. Polyhydroxyalkanoates in waste activated sludge enhances anaerobic methane production through improving biochemical methane potential instead of hydrolysis rate.

    PubMed

    Wang, Qilin; Sun, Jing; Zhang, Chang; Xie, Guo-Jun; Zhou, Xu; Qian, Jin; Yang, Guojing; Zeng, Guangming; Liu, Yiqi; Wang, Dongbo

    2016-01-21

    Anaerobic sludge digestion is the main technology for sludge reduction and stabilization prior to sludge disposal. Nevertheless, methane production from anaerobic digestion of waste activated sludge (WAS) is often restricted by the poor biochemical methane potential and slow hydrolysis rate of WAS. This work systematically investigated the effect of PHA levels of WAS on anaerobic methane production, using both experimental and mathematical modeling approaches. Biochemical methane potential tests showed that methane production increased with increased PHA levels in WAS. Model-based analysis suggested that the PHA-based method enhanced methane production by improving biochemical methane potential of WAS, with the highest enhancement being around 40% (from 192 to 274 L CH4/kg VS added; VS: volatile solid) when the PHA levels increased from 21 to 143 mg/g VS. In contrast, the hydrolysis rate (approximately 0.10 d(-1)) was not significantly affected by the PHA levels. Economic analysis suggested that the PHA-based method could save $1.2/PE/y (PE: population equivalent) in a typical wastewater treatment plant (WWTP). The PHA-based method can be easily integrated into the current WWTP to enhance methane production, thereby providing a strong support to the on-going paradigm shift in wastewater management from pollutant removal to resource recovery.

  20. Polyhydroxyalkanoates in waste activated sludge enhances anaerobic methane production through improving biochemical methane potential instead of hydrolysis rate

    PubMed Central

    Wang, Qilin; Sun, Jing; Zhang, Chang; Xie, Guo-Jun; Zhou, Xu; Qian, Jin; Yang, Guojing; Zeng, Guangming; Liu, Yiqi; Wang, Dongbo

    2016-01-01

    Anaerobic sludge digestion is the main technology for sludge reduction and stabilization prior to sludge disposal. Nevertheless, methane production from anaerobic digestion of waste activated sludge (WAS) is often restricted by the poor biochemical methane potential and slow hydrolysis rate of WAS. This work systematically investigated the effect of PHA levels of WAS on anaerobic methane production, using both experimental and mathematical modeling approaches. Biochemical methane potential tests showed that methane production increased with increased PHA levels in WAS. Model-based analysis suggested that the PHA-based method enhanced methane production by improving biochemical methane potential of WAS, with the highest enhancement being around 40% (from 192 to 274 L CH4/kg VS added; VS: volatile solid) when the PHA levels increased from 21 to 143 mg/g VS. In contrast, the hydrolysis rate (approximately 0.10 d−1) was not significantly affected by the PHA levels. Economic analysis suggested that the PHA-based method could save $1.2/PE/y (PE: population equivalent) in a typical wastewater treatment plant (WWTP). The PHA-based method can be easily integrated into the current WWTP to enhance methane production, thereby providing a strong support to the on-going paradigm shift in wastewater management from pollutant removal to resource recovery. PMID:26791952

  1. Zero valent iron significantly enhances methane production from waste activated sludge by improving biochemical methane potential rather than hydrolysis rate.

    PubMed

    Liu, Yiwen; Wang, Qilin; Zhang, Yaobin; Ni, Bing-Jie

    2015-02-05

    Anaerobic digestion has been widely applied for waste activated sludge (WAS) treatment. However, methane production from anaerobic digestion of WAS is usually limited by the slow hydrolysis rate and/or poor biochemical methane potential of WAS. This work systematically studied the effects of three different types of zero valent iron (i.e., iron powder, clean scrap and rusty scrap) on methane production from WAS in anaerobic digestion, by using both experimental and mathematical approaches. The results demonstrated that both the clean and the rusty iron scrap were more effective than the iron powder for improving methane production from WAS. Model-based analysis showed that ZVI addition significantly enhanced methane production from WAS through improving the biochemical methane potential of WAS rather than its hydrolysis rate. Economic analysis indicated that the ZVI-based technology for enhancing methane production from WAS is economically attractive, particularly considering that iron scrap can be freely acquired from industrial waste. Based on these results, the ZVI-based anaerobic digestion process of this work could be easily integrated with the conventional chemical phosphorus removal process in wastewater treatment plant to form a cost-effective and environment-friendly approach, enabling maximum resource recovery/reuse while achieving enhanced methane production in wastewater treatment system.

  2. The mechanism of methane and dioxygen activation in the catalytic cycle of methane monooxygenase.

    PubMed

    Shteinman, A A

    1995-03-27

    The binuclear structure of the active center of methane monooxygenase plays a determining role in dioxygen activation and in selectivity and specificity of alkane oxidation with this enzyme. A new mechanism is suggested for binding and activation of O2, which involves side-on binding of O2-(2) to iron atoms followed by its conversion to the bis-mu-oxo complex considered as an alternative of ferryl in CH4 activation. This mechanism results in the sequence of the cleavage of the O-O bond of peroxide O/O2-instead of the opposite sequence O2-/O, which takes place in the case of heme monooxygenase cytochrome P-450. Therefore, in this case there is no necessity of the charge relay system [N.B. Gerber and S.G. Sligar, J. Am. Chem. Soc. 114 (1992) 8742] for the transformation of O2 to an active intermediate. The experiment for checking this hypothesis is suggested.

  3. Activities That Reduce Global Anthropogenic Methane Emissions Grant - Closed Announcement FY 2012

    EPA Pesticide Factsheets

    Grant to fund eligible projects for activities that advance near-term, cost-effective methane abatement or recovery and use as a clean energy source, and support the goals of of theGlobal Methane Initiative.

  4. Start-up procedures and analysis of heavy metals inhibition on methanogenic activity in EGSB reactor.

    PubMed

    Colussi, I; Cortesi, A; Della Vedova, L; Gallo, V; Robles, F K Cano

    2009-12-01

    The effectiveness of operating an industrial UASB reactor, treating wastewater from the beer industry, with flows containing heavy metals was evaluated. A pilot-scale UASB reactor, already used to simulate the industrial reactor, was unsuccessfully employed. An easy start-up was obtained arranging it as an EGSB reactor. Considerations about this modification are reported. The effects of Cu(II), Ni(II) and Cr(III) ions on the anaerobic activity were analyzed by measurements of methane production rate and COD removal. The employed biomass was the sludge of the industrial UASB reactor, while a solution of ethanol and sodium acetate with COD of 3000 mg/L and a heavy metal concentration of 50 mg/L were continuously fed. Experimental results proved higher biomass sensitivity for copper and much slighter for nickel and chromium. Moreover, copper inhibition has been demonstrated to be less significant if a metal-free feed was provided to the system before copper addition.

  5. H2S mediated thermal and photochemical methane activation

    PubMed Central

    Baltrusaitis, Jonas; de Graaf, Coen; Broer, Ria; Patterson, Eric

    2013-01-01

    Sustainable, low temperature methods of natural gas activation are critical in addressing current and foreseeable energy and hydrocarbon feedstock needs. Large portions of natural gas resources are still too expensive to process due to their high content of hydrogen sulfide gas (H2S) in mixture with methane, CH4, altogether deemed as sub-quality or “sour” gas. We propose a unique method for activating this “sour” gas to form a mixture of sulfur-containing hydrocarbon intermediates, CH3SH and CH3SCH3, and an energy carrier, such as H2. For this purpose, we computationally investigated H2S mediated methane activation to form a reactive CH3SH species via direct photolysis of sub-quality natural gas. Photoexcitation of hydrogen sulfide in the CH4+H2S complex results in a barrier-less relaxation via a conical intersection to form a ground state CH3SH+H2 complex. The resulting CH3SH can further be heterogeneously coupled over acidic catalysts to form higher hydrocarbons while the H2 can be used as a fuel. This process is very different from a conventional thermal or radical-based processes and can be driven photolytically at low temperatures, with enhanced controllability over the process conditions currently used in industrial oxidative natural gas activation. Finally, the proposed process is CO2 neutral, as opposed to the currently industrially used methane steam reforming (SMR). PMID:24150813

  6. H2S-mediated thermal and photochemical methane activation.

    PubMed

    Baltrusaitis, Jonas; de Graaf, Coen; Broer, Ria; Patterson, Eric V

    2013-12-02

    Sustainable, low-temperature methods for natural gas activation are critical in addressing current and foreseeable energy and hydrocarbon feedstock needs. Large portions of natural gas resources are still too expensive to process due to their high content of hydrogen sulfide gas (H2S) mixed with methane, deemed altogether as sub-quality or "sour" gas. We propose a unique method of activation to form a mixture of sulfur-containing hydrocarbon intermediates, CH3SH and CH3SCH3 , and an energy carrier such as H2. For this purpose, we investigated the H2S-mediated methane activation to form a reactive CH3SH species by means of direct photolysis of sub-quality natural gas. Photoexcitation of hydrogen sulfide in the CH4 + H2S complex resulted in a barrierless relaxation by a conical intersection to form a ground-state CH3SH + H2 complex. The resulting CH3SH could further be coupled over acidic catalysts to form higher hydrocarbons, and the resulting H2 used as a fuel. This process is very different from conventional thermal or radical-based processes and can be driven photolytically at low temperatures, with enhanced control over the conditions currently used in industrial oxidative natural gas activation. Finally, the proposed process is CO2 neutral, as opposed to the current industrial steam methane reforming (SMR).

  7. Methane activation using Kr and Xe in a dielectric barrier discharge reactor

    SciTech Connect

    Jo, Sungkwon; Lee, Dae Hoon Kim, Kwan-Tae; Kang, Woo Seok; Song, Young-Hoon

    2014-10-15

    Methane has interested many researchers as a possible new energy source, but the high stability of methane causes a bottleneck in methane activation, limiting its practical utilization. To determine how to effectively activate methane using non-thermal plasma, the conversion of methane is measured in a planar-type dielectric barrier discharge reactor using three different noble gases—Ar, Kr, and Xe—as additives. In addition to the methane conversion results at various applied voltages, the discharge characteristics such as electron temperature and electron density were calculated through zero-dimensional calculations. Moreover, the threshold energies of excitation and ionization were used to distinguish the dominant particle for activating methane between electrons, excited atoms, and ionized atoms. From the experiments and calculations, the selection of the additive noble gas is found to affect not only the conversion of methane but also the selectivity of product gases even under similar electron temperature and electron density conditions.

  8. Methane recovery from water hyacinth through anaerobic activated sludge process

    SciTech Connect

    Savaswat, N.; Khana, P.

    1986-02-01

    The concepts of phase separation, anaerobic activated sludge process, and alkali pretreatment have been incorporated in this investigation with the objective of developing rational and cost-effective designs of diphasic anaerobic activated sludge systems, with and without alkali treatment, for methane recovery from water hyacinth (WH). Evaluation of process kinetics and optimization analyses of laboratory data reveal that a diphasic system with alkali treatment could be designed with an alkali pretreatment step (3.6% Na/sub 2/CO/sub 3/ + 2.5% Ca(OH)/sub 2/ (w/w) of WH, 24 h duration) followed by an open acid phase (2.1 days HRT) and closed methane reactor with sludge recycle (5.7 days HRT, 7.7 days MCRT) for gas yield of 50 L/kg WH/d at 35-37/sup 0/C. Likewise, a diphasic system without alkali treatment could be designed with an open acid phase (2 days HRT) followed by closed methane reactor with sludge recycle (3.2 days HRT, 6 days MCRT) for gas yield of 32.5 L/kg WH/d at 35-37/sup 0/C. Detailed economic analyses bring forth greater cost-efficacy of the diphasic system without alkali treatment and reveal that the advantage accrued in terms of higher gas yield is overshadowed by the cost of chemicals in the diphasic system with alkali treatment.

  9. Methane recovery from water hyacinth through anaerobic activated sludge process

    SciTech Connect

    Saraswat, N.; Khanna, P.

    1986-02-01

    The concepts of phase separation, anaerobic activated sludge process, and alkali pretreatment have been incorporated in this investigation with the objective of developing rational and cost-effective designs of diphasic anaerobic activated sludge systems, with and without alkali treatment, for methane recovery from water hyacinth (WH). Evaluation of process kinetics and optimization analyses of laboratory data reveal that a diphasic system with alkali treatment could be designed with an alkali pretreatment step (3.6% Na/sub 2/CO/sub 3/ + 2.5% Ca(OH)/sub 2/ (w/w) of WH, 24 h duration) followed by an open acid phase (2.1 days HRT) and closed methane reactor with sludge recycle (5.7 days HRT, 7.7 days MCRT) for gas yield of 50 l/kg WH/d at 35-37/sup 0/C. Likewise, a diphasic system without alkali treatment could be designed with an open acid phase (2 days HRT) followed by close methane reactor with sludge recycle (3.2 days HRT, 6 days MCRT) for gas yield of 32.5 l.kg WH/d at 35-37/sup 0/C. Detailed economic analyses bring forth greater cost-efficacy of the diphasic system without alkali treatment and reveal that the advantage accrued in terms of higher gas yield is overshadowed by the cost of chemicals in the diphasic system with alkali treatment.

  10. Pt +-mediated activation of methane: theory and experiment

    NASA Astrophysics Data System (ADS)

    Heinemann, Christoph; Wesendrup, Ralf; Schwarz, Helmut

    1995-06-01

    A combined theoretical and experimental study on the Pt +-mediated activation of methane is presented. Dehydrogenation of CH 4 by thermalized Pt + cations (Pt + + CH 4 ← PtCH 2+ + H 2) proceeds along a doublet ground state potential energy surface and is found to be reversible under the conditions of Fourier transform ion-cyclotron resonance mass spectrometry. The recently reported oxidation of the cationic platinum carbene PtCH 2+ by O 2 produces electronically excited Pt + cations, which are detected in the 4F9/2 state by means of charge-transfer bracketing experiments.

  11. Methane activation using noble gases in a dielectric barrier discharge reactor

    SciTech Connect

    Jo, Sungkwon; Hoon Lee, Dae; Seok Kang, Woo; Song, Young-Hoon

    2013-08-15

    The conversion of methane is measured in a planar-type dielectric barrier discharge reactor using three different noble gases—He, Ne, and Ar—as additives. The empirical results obtained clearly indicate that methane activation is considerably affected by thy type of noble gas used. Through 0-D calculations, the discharge parameters inside the reactor, i.e., electron temperature and electron density, are estimated using experiment results. A comparison of the discharge characteristics and experimental results shows that the electron temperature is an important factor in achieving high methane activation and the mixture with Ar gas shows the highest methane conversion. These results are constructed using the mechanisms of energy and charge transfer from excited and ionized noble gas atoms to methane molecules, considering the number density of active atoms of noble gases. Finally, electron temperatures obtained for gas mixtures having different reactant compositions and concentrations are analyzed to estimate methane activation.

  12. Effects of Zinc on Particulate Methane Monooxygenase Activity and Structure*

    PubMed Central

    Sirajuddin, Sarah; Barupala, Dulmini; Helling, Stefan; Marcus, Katrin; Stemmler, Timothy L.; Rosenzweig, Amy C.

    2014-01-01

    Particulate methane monooxygenase (pMMO) is a membrane-bound metalloenzyme that oxidizes methane to methanol in methanotrophic bacteria. Zinc is a known inhibitor of pMMO, but the details of zinc binding and the mechanism of inhibition are not understood. Metal binding and activity assays on membrane-bound pMMO from Methylococcus capsulatus (Bath) reveal that zinc inhibits pMMO at two sites that are distinct from the copper active site. The 2.6 Å resolution crystal structure of Methylocystis species strain Rockwell pMMO reveals two previously undetected bound lipids, and metal soaking experiments identify likely locations for the two zinc inhibition sites. The first is the crystallographic zinc site in the pmoC subunit, and zinc binding here leads to the ordering of 10 previously unobserved residues. A second zinc site is present on the cytoplasmic side of the pmoC subunit. Parallels between these results and zinc inhibition studies of several respiratory complexes suggest that zinc might inhibit proton transfer in pMMO. PMID:24942740

  13. Differences in the Nature of Active Sites for Methane Dry Reforming and Methane Steam Reforming over Nickel Aluminate Catalysts

    DOE PAGES

    Rogers, Jessica L.; Mangarella, Michael C.; D’Amico, Andrew D.; ...

    2016-07-20

    In this paper, the Pechini synthesis was used to prepare nickel aluminate catalysts with the compositions NiAl4O7, NiAl2O4, and Ni2Al2O5. The samples have been characterized by N2 physisorption, temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and X-ray absorption spectroscopy (XAS). Characterization results indicate unique structural properties and excellent regeneration potential of nickel aluminates. Prepared samples were tested when unreduced and reduced prior to reaction for methane dry reforming and methane steam reforming reactivity. NiAl2O4 in the reduced and unreduced state as well as NiAl4O7 in the reduced state are activemore » and stable for methane dry reforming due to the presence of 4-fold coordinated oxidized nickel. The limited amount of metallic nickel in these samples minimizes carbon deposition. Finally, on the other hand, the presence of metallic nickel is required for methane steam reforming. Ni2Al2O5 in the reduced and unreduced states and NiAl2O4 in the reduced state are found to be active for methane steam reforming due to the presence of sufficiently small nickel nanoparticles that catalyze the reaction without accumulating carbonaceous deposits.« less

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  15. Activation of Methane by the Pyridine Radical Cation and its Substituted Forms in the Gas Phase

    NASA Astrophysics Data System (ADS)

    Wu, Guohua; Stewart, Hamish; Liu, Zeyu; Wang, Yongcheng; Stace, Anthony J.

    2015-08-01

    We present an experimental study of methane activation by pyridine cation and its substituents in the gas phase. Mass spectrometric experiments in an ion trap demonstrate that pyridine cation and some of its substituent cations are able to react with methane. The deuterated methane experiment has confirmed that the hydrogen atom in the ionic product of reaction does come from methane. The collected information about kinetic isotope effects has been used to distinguish the nature of the bond activation as a hydrogen abstraction. Furthermore, experimental results demonstrated that the substituent groups on the pyridine ring can crucially influence their reactivity in methane bond activation processes. Density functional calculation (DFT) was employed to study the electronic structures of the complex and reaction mechanism of CH4+C5H5N+. The calculations confirmed the hypothesis from the experimental observation, namely, the reaction is rapid with no energy barrier.

  16. Differences in the Nature of Active Sites for Methane Dry Reforming and Methane Steam Reforming over Nickel Aluminate Catalysts

    SciTech Connect

    Rogers, Jessica L.; Mangarella, Michael C.; D’Amico, Andrew D.; Gallagher, James R.; Dutzer, Michael R.; Stavitski, Eli; Miller, Jeffrey T.; Sievers, Carsten

    2016-07-20

    In this paper, the Pechini synthesis was used to prepare nickel aluminate catalysts with the compositions NiAl4O7, NiAl2O4, and Ni2Al2O5. The samples have been characterized by N2 physisorption, temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and X-ray absorption spectroscopy (XAS). Characterization results indicate unique structural properties and excellent regeneration potential of nickel aluminates. Prepared samples were tested when unreduced and reduced prior to reaction for methane dry reforming and methane steam reforming reactivity. NiAl2O4 in the reduced and unreduced state as well as NiAl4O7 in the reduced state are active and stable for methane dry reforming due to the presence of 4-fold coordinated oxidized nickel. The limited amount of metallic nickel in these samples minimizes carbon deposition. Finally, on the other hand, the presence of metallic nickel is required for methane steam reforming. Ni2Al2O5 in the reduced and unreduced states and NiAl2O4 in the reduced state are found to be active for methane steam reforming due to the presence of sufficiently small nickel nanoparticles that catalyze the reaction without accumulating carbonaceous deposits.

  17. Identification, visualization, and sorting of translationally active microbial consortia from deep-sea methane seeps

    NASA Astrophysics Data System (ADS)

    Hatzenpichler, R.; Connon, S. A.; Goudeau, D.; Malmstrom, R.; Woyke, T.; Orphan, V. J.

    2015-12-01

    Within the past few years, great progress has been made in tapping the genomes of individual cells separated from environmental samples. Unfortunately, however, most often these efforts have been target blind, as they did not pre-select for taxa of interest or focus on metabolically active cells that could be considered key species of the system at the time. This problem is particularly pronounced in low-turnover systems such as deep sea sediments. In an effort to tap the genetic potential hidden within functionally active cells, we have recently developed an approach for the in situ fluorescent tracking of protein synthesis in uncultured cells via bioorthogonal non-canonical amino acid-tagging (BONCAT). This technique depends on the incorporation of synthetic amino acids that carry chemically modifiable tags into newly made proteins, which later can be visualized via click chemistry-mediated fluorescence-labeling. BONCAT is thus able to specifically target proteins that have been expressed in reaction to an experimental condition. We are particularly interested in using BONCAT to understand the functional potential of slow-growing syntrophic consortia of anaerobic methanotrophic archaea and sulfate-reducing bacteria which together catalyze the anaerobic oxidation of methane (AOM) in marine methane seeps. In order to specifically target consortia that are active under varying environmental regimes, we are studying different subpopulations of these inter-domain consortia via a combination of BONCAT with rRNA-targeted FISH. We then couple the BONCAT-enabled staining of active consortia with their separation from inactive members of the community via fluorescence-activated cell-sorting (FACS) and metagenomic sequencing of individual consortia. Using this approach, we were able to identify previously unrecognized AOM-partnerships. By comparing the mini-metagenomes obtained from individual consortia with each other we are starting to gain a more hollistic understanding

  18. Analysis of methane monooxygenase genes in mono lake suggests that increased methane oxidation activity may correlate with a change in methanotroph community structure.

    PubMed

    Lin, Ju-Ling; Joye, Samantha B; Scholten, Johannes C M; Schäfer, Hendrik; McDonald, Ian R; Murrell, J Colin

    2005-10-01

    Mono Lake is an alkaline hypersaline lake that supports high methane oxidation rates. Retrieved pmoA sequences showed a broad diversity of aerobic methane oxidizers including the type I methanotrophs Methylobacter (the dominant genus), Methylomicrobium, and Methylothermus, and the type II methanotroph Methylocystis. Stratification of Mono Lake resulted in variation of aerobic methane oxidation rates with depth. Methanotroph diversity as determined by analysis of pmoA using new denaturing gradient gel electrophoresis primers suggested that variations in methane oxidation activity may correlate with changes in methanotroph community composition.

  19. An active atmospheric methane sink in high Arctic mineral cryosols

    PubMed Central

    Lau, M C Y; Stackhouse, B T; Layton, A C; Chauhan, A; Vishnivetskaya, T A; Chourey, K; Ronholm, J; Mykytczuk, N C S; Bennett, P C; Lamarche-Gagnon, G; Burton, N; Pollard, W H; Omelon, C R; Medvigy, D M; Hettich, R L; Pfiffner, S M; Whyte, L G; Onstott, T C

    2015-01-01

    Methane (CH4) emission by carbon-rich cryosols at the high latitudes in Northern Hemisphere has been studied extensively. In contrast, data on the CH4 emission potential of carbon-poor cryosols is limited, despite their spatial predominance. This work employs CH4 flux measurements in the field and under laboratory conditions to show that the mineral cryosols at Axel Heiberg Island in the Canadian high Arctic consistently consume atmospheric CH4. Omics analyses present the first molecular evidence of active atmospheric CH4-oxidizing bacteria (atmMOB) in permafrost-affected cryosols, with the prevalent atmMOB genotype in our acidic mineral cryosols being closely related to Upland Soil Cluster α. The atmospheric (atm) CH4 uptake at the study site increases with ground temperature between 0 °C and 18 °C. Consequently, the atm CH4 sink strength is predicted to increase by a factor of 5–30 as the Arctic warms by 5–15 °C over a century. We demonstrate that acidic mineral cryosols are a previously unrecognized potential of CH4 sink that requires further investigation to determine its potential impact on larger scales. This study also calls attention to the poleward distribution of atmMOB, as well as to the potential influence of microbial atm CH4 oxidation, in the context of regional CH4 flux models and global warming. PMID:25871932

  20. An active atmospheric methane sink in high Arctic mineral cryosols.

    PubMed

    Lau, M C Y; Stackhouse, B T; Layton, A C; Chauhan, A; Vishnivetskaya, T A; Chourey, K; Ronholm, J; Mykytczuk, N C S; Bennett, P C; Lamarche-Gagnon, G; Burton, N; Pollard, W H; Omelon, C R; Medvigy, D M; Hettich, R L; Pfiffner, S M; Whyte, L G; Onstott, T C

    2015-08-01

    Methane (CH4) emission by carbon-rich cryosols at the high latitudes in Northern Hemisphere has been studied extensively. In contrast, data on the CH4 emission potential of carbon-poor cryosols is limited, despite their spatial predominance. This work employs CH4 flux measurements in the field and under laboratory conditions to show that the mineral cryosols at Axel Heiberg Island in the Canadian high Arctic consistently consume atmospheric CH4. Omics analyses present the first molecular evidence of active atmospheric CH4-oxidizing bacteria (atmMOB) in permafrost-affected cryosols, with the prevalent atmMOB genotype in our acidic mineral cryosols being closely related to Upland Soil Cluster α. The atmospheric (atm) CH4 uptake at the study site increases with ground temperature between 0 °C and 18 °C. Consequently, the atm CH4 sink strength is predicted to increase by a factor of 5-30 as the Arctic warms by 5-15 °C over a century. We demonstrate that acidic mineral cryosols are a previously unrecognized potential of CH4 sink that requires further investigation to determine its potential impact on larger scales. This study also calls attention to the poleward distribution of atmMOB, as well as to the potential influence of microbial atm CH4 oxidation, in the context of regional CH4 flux models and global warming.

  1. Dioxygen activation in methane monooxygenase: a theoretical study.

    PubMed

    Gherman, Benjamin F; Baik, Mu-Hyun; Lippard, Stephen J; Friesner, Richard A

    2004-03-10

    Using broken-symmetry unrestricted Density Functional Theory, the mechanism of enzymatic dioxygen activation by the hydroxylase component of soluble methane monooxygenase (MMOH) is determined to atomic detail. After a thorough examination of mechanistic alternatives, an optimal pathway was identified. The diiron(II) state H(red) reacts with dioxygen to give a ferromagnetically coupled diiron(II,III) H(superoxo) structure, which undergoes intersystem crossing to the antiferromagnetic surface and affords H(peroxo), a symmetric diiron(III) unit with a nonplanar mu-eta(2):eta(2)-O(2)(2)(-) binding mode. Homolytic cleavage of the O-O bond yields the catalytically competent intermediate Q, which has a di (mu-oxo)diiron(IV) core. A carboxylate shift involving Glu243 is essential to the formation of the symmetric H(peroxo) and Q structures. Both thermodynamic and kinetic features agree well with experimental data, and computed spin-exchange coupling constants are in accord with spectroscopic values. Evidence is presented for pH-independent decay of H(red) and H(peroxo). Key electron-transfer steps that occur in the course of generating Q from H(red) are also detailed and interpreted. In contrast to prior theoretical studies, a requisite large model has been employed, electron spins and couplings have been treated in a quantitative manner, potential energy surfaces have been extensively explored, and quantitative total energies have been determined along the reaction pathway.

  2. Getting Started: Materials and Equipment for Active Learning Preschools.

    ERIC Educational Resources Information Center

    Vogel, Nancy

    This book provides information to guide the development of an active learning early childhood program by assisting in the selection of materials and equipment to support children's cognitive, physical and social development. The guide considers the arrangement of classroom areas, and elements of the daily routine. The following classroom interest…

  3. Monocopper active site for partial methane oxidation in Cu-exchanged 8MR zeolites

    SciTech Connect

    Kulkarni, Ambarish R.; Zhao, Zhi -Jian; Siahrostami, Samira; Nørskov, Jens K.; Studt, Felix

    2016-08-17

    Direct conversion of methane to methanol using oxygen is experiencing renewed interest owing to the availability of new natural gas resources. Copper-exchanged zeolites such as mordenite and ZSM-5 have shown encouraging results, and di- and tri-copper species have been suggested as active sites. Recently, small eight-membered ring (8MR) zeolites including SSZ-13, -16, and -39 have been shown to be active for methane oxidation, but the active sites and reaction mechanisms in these 8MR zeolites are not known. In this work, we use density functional theory (DFT) calculations to systematically evaluate monocopper species as active sites for the partial methane oxidation reaction in Cu-exchanged SSZ-13. On the basis of kinetic and thermodynamic arguments, we suggest that [CuIIOH]+ species in the 8MR are responsible for the experimentally observed activity. Furthermore, our results successfully explain the available spectroscopic data and experimental observations including (i) the necessity of water for methanol extraction and (ii) the effect of Si/Al ratio on the catalyst activity. Monocopper species have not yet been suggested as an active site for the partial methane oxidation reaction, and our results suggest that [CuIIOH]+ active site may provide complementary routes for methane activation in zeolites in addition to the known [Cu–O–Cu]2+ and Cu3O3 motifs.

  4. Monocopper active site for partial methane oxidation in Cu-exchanged 8MR zeolites

    DOE PAGES

    Kulkarni, Ambarish R.; Zhao, Zhi -Jian; Siahrostami, Samira; ...

    2016-08-17

    Direct conversion of methane to methanol using oxygen is experiencing renewed interest owing to the availability of new natural gas resources. Copper-exchanged zeolites such as mordenite and ZSM-5 have shown encouraging results, and di- and tri-copper species have been suggested as active sites. Recently, small eight-membered ring (8MR) zeolites including SSZ-13, -16, and -39 have been shown to be active for methane oxidation, but the active sites and reaction mechanisms in these 8MR zeolites are not known. In this work, we use density functional theory (DFT) calculations to systematically evaluate monocopper species as active sites for the partial methane oxidationmore » reaction in Cu-exchanged SSZ-13. On the basis of kinetic and thermodynamic arguments, we suggest that [CuIIOH]+ species in the 8MR are responsible for the experimentally observed activity. Furthermore, our results successfully explain the available spectroscopic data and experimental observations including (i) the necessity of water for methanol extraction and (ii) the effect of Si/Al ratio on the catalyst activity. Monocopper species have not yet been suggested as an active site for the partial methane oxidation reaction, and our results suggest that [CuIIOH]+ active site may provide complementary routes for methane activation in zeolites in addition to the known [Cu–O–Cu]2+ and Cu3O3 motifs.« less

  5. Coalbed Methane Outreach Program

    EPA Pesticide Factsheets

    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.

  6. Cancer Prehabilitation for Patients Starting from Active Treatment to Surveillance

    PubMed Central

    Shun, Shiow-Ching

    2016-01-01

    The purpose of this brief summary is to introduce the concept of cancer prehabilitation and the role of oncology nurses in prehabilitation care. Cancer prehabilitation has been defined by Sliver and Baima (2013) as “a process on the cancer continuum of care that occurs between the time of cancer diagnosis and the beginning of acute treatment.” The evidence supports the notion that prehabilitation programs can improve physical and psychological health outcomes and decrease overall health care costs. The care model for cancer prehabilitation should include timely and efficient assessment throughout the care continuum with a focus on improving outcomes in cancer at every stage. During the cancer journey, three types of assessment with different aims are included: (1) prehabilitation assessment pretreatment, (2) rehabilitation assessment at early post treatment, and (3) health promotion assessment at the end of treatment. Specific prehabilitation assessment and interventions for treatment-related complications or major side-effects should be considered. Teaching, counseling, discharge planning, and coordination should also be part of an oncology nurse's role in cancer prehabilitation. It is suggested that cancer care managers or navigators be trained in the assessment of their patients’ physical and psychological status once the cancer diagnosis has been identified and the patient has decided to receive active treatment, especially for those waiting for surgery at home. Oncology nurses could increase their competence with prehabilitation care by gaining knowledge about cancer-related treatments and their outcomes for specific cancers and by strengthening the ability to assess the functional status and psychological distress of their patients. PMID:27981135

  7. Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study.

    PubMed

    Paytan, Adina; Lecher, Alanna L; Dimova, Natasha; Sparrow, Katy J; Kodovska, Fenix Garcia-Tigreros; Murray, Joseph; Tulaczyk, Slawomir; Kessler, John D

    2015-03-24

    Methane emissions in the Arctic are important, and may be contributing to global warming. While methane emission rates from Arctic lakes are well documented, methods are needed to quantify the relative contribution of active layer groundwater to the overall lake methane budget. Here we report measurements of natural tracers of soil/groundwater, radon, and radium, along with methane concentration in Toolik Lake, Alaska, to evaluate the role active layer water plays as an exogenous source for lake methane. Average concentrations of methane, radium, and radon were all elevated in the active layer compared with lake water (1.6 × 10(4) nM, 61.6 dpm⋅m(-3), and 4.5 × 10(5) dpm⋅m(-3) compared with 1.3 × 10(2) nM, 5.7 dpm⋅m(-3), and 4.4 × 10(3) dpm⋅m(-3), respectively). Methane transport from the active layer to Toolik Lake based on the geochemical tracer radon (up to 2.9 g⋅m(-2)⋅y(-1)) can account for a large fraction of methane emissions from this lake. Strong but spatially and temporally variable correlations between radon activity and methane concentrations (r(2) > 0.69) in lake water suggest that the parameters that control methane discharge from the active layer also vary. Warming in the Arctic may expand the active layer and increase the discharge, thereby increasing the methane flux to lakes and from lakes to the atmosphere, exacerbating global warming. More work is needed to quantify and elucidate the processes that control methane fluxes from the active layer to predict how this flux might change in the future and to evaluate the regional and global contribution of active layer water associated methane inputs.

  8. Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

    PubMed Central

    Paytan, Adina; Lecher, Alanna L.; Dimova, Natasha; Sparrow, Katy J.; Kodovska, Fenix Garcia-Tigreros; Murray, Joseph; Tulaczyk, Slawomir; Kessler, John D.

    2015-01-01

    Methane emissions in the Arctic are important, and may be contributing to global warming. While methane emission rates from Arctic lakes are well documented, methods are needed to quantify the relative contribution of active layer groundwater to the overall lake methane budget. Here we report measurements of natural tracers of soil/groundwater, radon, and radium, along with methane concentration in Toolik Lake, Alaska, to evaluate the role active layer water plays as an exogenous source for lake methane. Average concentrations of methane, radium, and radon were all elevated in the active layer compared with lake water (1.6 × 104 nM, 61.6 dpm⋅m−3, and 4.5 × 105 dpm⋅m−3 compared with 1.3 × 102 nM, 5.7 dpm⋅m−3, and 4.4 × 103 dpm⋅m−3, respectively). Methane transport from the active layer to Toolik Lake based on the geochemical tracer radon (up to 2.9 g⋅m−2⋅y−1) can account for a large fraction of methane emissions from this lake. Strong but spatially and temporally variable correlations between radon activity and methane concentrations (r2 > 0.69) in lake water suggest that the parameters that control methane discharge from the active layer also vary. Warming in the Arctic may expand the active layer and increase the discharge, thereby increasing the methane flux to lakes and from lakes to the atmosphere, exacerbating global warming. More work is needed to quantify and elucidate the processes that control methane fluxes from the active layer to predict how this flux might change in the future and to evaluate the regional and global contribution of active layer water associated methane inputs. PMID:25775530

  9. Neuromuscular Activity of Upper and Lower Limbs during two Backstroke Swimming Start Variants

    PubMed Central

    De Jesus, Karla; De Jesus, Kelly; Medeiros, Alexandre I. A.; Gonçalves, Pedro; Figueiredo, Pedro; Fernandes, Ricardo J.; Vilas-Boas, João Paulo

    2015-01-01

    A proficient start is decisive in sprint competitive swimming events and requires swimmers’ to exert maximal forces in a short period to complete the task successfully. The aim of this study was to compare the electromyographic (EMG) activity in-between the backstroke start with feet positioned parallel and partially emerged performed with the hands on the highest horizontal and on the vertical handgrip at hands-off, take-off, flight and entry start phases. EMG comparisons between starting variants were supported by upper and lower limb joint angles at starting position and 15 m start time data. Following a four-week start training to familiarize participants with each start variant, 10 male competitive backstroke swimmers performed randomly six 15 m maximal trials, being three of each start variant. Surface EMG of Biceps Brachii, Triceps Brachii, Rectus Femoris, Biceps Femoris, Gastrocnemius Medialis and Tibialis Anterior was recorded and processed using the time integral EMG (iEMG). Eight video cameras (four surface and four underwater) were used to determine backstroke start phases and joint angles at starting position. EMG, joint angles and temporal parameters have not evidenced changes due to the different handgrips. Nevertheless, clear differences were observed in both variants for upper and lower limb muscles activity among starting phases (e.g. Biceps Brachii at take-off vs. flight phase, 15.17% ± 2.76% and 22.38% ± 4.25%; 14.24% ± 7.11% and 25.90% ± 8.65%, for variant with hands horizontal and vertically positioned, respectively). It was concluded that different handgrips did not affect EMG, kinematics and temporal profile in backstroke start. Despite coaches might plan similar strength training for both start variants, further attention should be given on the selection of proper exercises to maximize the contribution of relevant muscles at different starting phases. Key points An effective swim start component (from the starting signal until the

  10. Gas-phase activation of methane by ligated transition-metal cations

    PubMed Central

    Schröder, Detlef; Schwarz, Helmut

    2008-01-01

    Motivated by the search for ways of a more efficient usage of the large, unexploited resources of methane, recent progress in the gas-phase activation of methane by ligated transition-metal ions is discussed. Mass spectrometric experiments demonstrate that the ligands can crucially influence both reactivity and selectivity of transition-metal cations in bond-activation processes, and the most reactive species derive from combinations of transition metals with the electronegative elements fluorine, oxygen, and chlorine. Furthermore, the collected knowledge about intramolecular kinetic isotope effects associated with the activation of C–H(D) bonds of methane can be used to distinguish the nature of the bond activation as a mere hydrogen-abstraction, a metal-assisted mechanism or more complex reactions such as formation of insertion intermediates or σ-bond metathesis. PMID:18955709

  11. Circle Time: An Exploratory Study of Activities and Challenging Behavior in Head Start Classrooms

    ERIC Educational Resources Information Center

    Zaghlawan, Hasan Y.; Ostrosky, Michaelene M.

    2011-01-01

    The purpose of this descriptive study was to examine circle time activities in eight Head Start classrooms. A total of 7 h of observations occurred in eight classrooms. Songs and academic activities were the most frequently occurring activities. Challenging behavior during circle time also was examined. The three activities with the highest…

  12. Enhancing methane production from waste activated sludge using a novel indigenous iron activated peroxidation pre-treatment process.

    PubMed

    Zhou, Xu; Wang, Qilin; Jiang, Guangming

    2015-04-01

    Methane production from anaerobic digestion of waste activated sludge (WAS) is limited by the slow hydrolysis rate and/or poor methane potential of WAS. This study presents a novel pre-treatment strategy based on indigenous iron (in WAS) activated peroxidation to enhance methane production from WAS. Pre-treatment of WAS for 30 min at 50mg H2O2/g total solids (dry weight) and pH 2.0 (iron concentration in WAS was 7 mg/g TS) substantially enhanced WAS solubilization. Biochemical methane potential tests demonstrated that methane production was improved by 10% at a digestion time of 16d after incorporating the indigenous iron activated peroxidation pre-treatment. Model-based analysis indicated that indigenous iron activated peroxidation pre-treatment improved the methane potential by 13%, whereas the hydrolysis rate was not significantly affected. The economic analysis showed that the proposed pre-treatment method can save the cost by $112,000 per year in a treatment plant with a population equivalent of 300,000.

  13. Tracking Dissolved Methane Concentrations near Active Seeps and Gas Hydrates: Sea of Japan.

    NASA Astrophysics Data System (ADS)

    Snyder, G. T.; Aoki, S.; Matsumoto, R.; Tomaru, H.; Owari, S.; Nakajima, R.; Doolittle, D. F.; Brant, B.

    2015-12-01

    A number of regions in the Sea of Japan are known for active gas venting and for gas hydrate exposures on the sea floor. In this investigation we employed several gas sensors mounted on a ROV in order to determine the concentrations of dissolved methane in the water near these sites. Methane concentrations were determined during two-second intervals throughout each ROV deployment during the cruise. The methane sensor deployments were coupled with seawater sampling using Niskin bottles. Dissolved gas concentrations were later measured using gas chromatography in order to compare with the sensor results taken at the same time. The observed maximum dissolved methane concentrations were much lower than saturation values, even when the ROV manipulators were in contact with gas hydrate. Nonetheless, dissolved concentrations did reach several thousands of nmol/L near gas hydrate exposures and gas bubbles, more than two orders of magnitude over the instrumental detection limits. Most of the sensors tested were able to detect dissolved methane concentrations as low as 10 nmol/L which permitted detection when the ROV approached methane plume sites, even from several tens of meters above the sea floor. Despite the low detection limits, the methane sensors showed variable response times when returning to low-background seawater (~5nM). For some of the sensors, the response time necessary to return to background values occurred in a matter of minutes, while for others it took several hours. Response time, as well as detection limit, should be an important consideration when selecting methane sensors for ROV or AUV investigations. This research was made possible, in part, through funding provided by the Japanese Ministry of Economy, Trade and Industry (METI).

  14. Methane-derived carbonates as archives of past seepage activity along the Norwegian margin

    NASA Astrophysics Data System (ADS)

    Crémière, Antoine; Lepland, Aivo; Sahy, Diana; Noble, Stephen R.; Condon, Daniel J.; Chand, Shyam; Stoddart, Daniel; Halvard Pedersen, Jon; Sauer, Simone; Brunstad, Harald; Birger Pedersen, Rolf; Thornes, Terje

    2014-05-01

    Assessment of timing and flux rates of past methane discharges is in part hindered by the lack of robust age constraints. Authigenic carbonate crusts forming in shallow sediments due to the oxidation of methane are recorders of seepage that can be dated by using U-daughter decay affording the unique opportunity to constrain the absolute timing of methane release events. Methane-derived carbonate crusts exhibiting characteristic 13C-depleted isotopic signatures were collected from several seepage sites on the Norwegian continental shelf, including sites in the North Sea, the Norwegian Sea and the Barents Sea. The U-Th dating results constrain the main episode of carbonate crust formation in the Barents and Norwegian seas during the time interval between 14 and 7 ka. Such ages suggest that the methane seepage along the northern Norwegian margin was most active after the collapse of the Scandinavian ice sheet and deglaciation of the area that took place at about 15 ka. The methane flux for the carbonate crust formation was likely provided by the dissociation of methane hydrates that extensively formed in underlying sediments during the last glacial period, but became unstable due to depressuring effects of retreating ice sheet. The precipitation of studied North Sea carbonate crusts occurred more recently, from 6 to 1 ka, suggesting that their formation is unrelated to the glacial history of the area and gas hydrate stability. Carbonate crust formation in the North Sea is likely related to the methane seepage from the hydrocarbon reservoir and the dating results allow an assessment of the seepage history within individual conduits.

  15. Pore size distribution analysis of activated carbons prepared from coconut shell using methane adsorption data

    NASA Astrophysics Data System (ADS)

    Ahmadpour, A.; Okhovat, A.; Darabi Mahboub, M. J.

    2013-06-01

    The application of Stoeckli theory to determine pore size distribution (PSD) of activated carbons using high pressure methane adsorption data is explored. Coconut shell was used as a raw material for the preparation of 16 different activated carbon samples. Four samples with higher methane adsorption were selected and nitrogen adsorption on these adsorbents was also investigated. Some differences are found between the PSD obtained from the analysis of nitrogen adsorption isotherms and their PSD resulting from the same analysis using methane adsorption data. It is suggested that these differences may arise from the specific interactions between nitrogen molecules and activated carbon surfaces; therefore caution is required in the interpretation of PSD obtained from the nitrogen isotherm data.

  16. Tracing the Origin of Methane and Water on Mars: Active Regions and their Seasonal Variability

    NASA Astrophysics Data System (ADS)

    Villanueva, Geronimo; Mumma, M. J.; Novak, R. E.

    2009-09-01

    We have detected methane on Mars [1,2], and measured it simultaneously with water using powerful ground-based telescopes. Its presence in such a strongly oxidized atmosphere (CO2, 95.3%) requires recent release; the ultimate origin of this methane is uncertain, but it could either be abiotic or biotic. In this paper, we present the spatial distributions of methane and water-vapor on Mars extracted from our complete spectral database now spanning seven years, and we compare these with other geological parameters. Both gases are depleted at vernal equinox but are enhanced in warm seasons (spring/summer), though often with dissimilar spatial distributions. In Northern Summer we observe a polar outburst of water but no methane, while in Southern Spring we observe release of abundant methane but little water. Regions of methane release appear mainly over ancient terrain (Noachian/Hesperian, older than 3 billion years) known to have a rich hydration history. There is ample evidence that ancient Mars was wet and likely hosted habitable conditions. Moreover, the presence of extensive volcanism probably gave rise to widespread hydrothermal activity and the formation of rich aqueous subsurface reservoirs. Methane produced by geological processes (e.g., serpentinization) or by living organisms at that time could have been incorporated into hydrates. If such processes remain active on Mars below the permafrost, the byproduct gases (i.e. CH4 and H2S) may be trapped as hydrates at the base of the cryosphere. [1] Mumma et al. (2009) Science, 323, 1041. [2] Villanueva et al. (2009), submitted. This work was funded by NASA grants 08-PAST08-0034 (Planetary Astronomy) and 08-PATM080-0031 (Planetary Atmospheres) and grants from the NSF RUI Program (AST-0505765 and AST-0805540). We acknowledge the NASA-IRTF and Keck-2 telescopes for observing time.

  17. Electrostatic and Charge-Induced Methane Activation by a Concerted Double C-H Bond Insertion.

    PubMed

    Geng, Caiyun; Li, Jilai; Weiske, Thomas; Schlangen, Maria; Shaik, Sason; Schwarz, Helmut

    2017-02-01

    A mechanistically unique, simultaneous activation of two C-H bonds of methane has been identified during the course of its reaction with the cationic copper carbide, [Cu-C](+). Detailed high-level quantum chemical calculations support the experimental findings obtained in the highly diluted gas phase using FT-ICR mass spectrometry. The behavior of [Cu-C](+)/CH4 contrasts that of [Au-C](+)/CH4, for which a stepwise bond-activation scenario prevails. An explanation for the distinct mechanistic differences of the two coinage metal complexes is given. It is demonstrated that the coupling of [Cu-C](+) with methane to form ethylene and Cu(+) is modeled very well by the reaction of a carbon atom with methane mediated by an oriented external electric field of a positive point charge.

  18. Perovskite-supported palladium for methane oxidation - structure-activity relationships.

    PubMed

    Eyssler, Arnim; Lu, Ye; Matam, Santhosh Kumar; Weidenkaff, Anke; Ferri, Davide

    2012-01-01

    Palladium is the precious metal of choice for methane oxidation and perovskite-type oxides offer the possibility to stabilize it as PdO, considered crucial for catalytic activity. Pd can adopt different oxidation and coordination states when associated with perovskite-type oxides. Here, we review our work on the effect of perovskite composition on the oxidation and coordination states of Pd and its influence on catalytic activity for methane oxidation in the case of typical Mn, Fe and Co perovskite-based oxidation catalysts. Especially X-ray absorption near edge structure (XANES) spectroscopy is shown to be crucial to fingerprint the different coordination states of Pd. Pd substitutes Fe and Co in the octahedral sites but without modifying catalytic activity with respect to the Pd-free perovskite. On LaMnO(3) palladium is predominantly exposed at the surface thus bestowing catalytic activity for methane oxidation. However, the occupancy of B-cation sites of the perovskite structure by Pd can be exploited to cyclically activate Pd and to protect it from particle growth. This is explicitly demonstrated for La(Fe, Pd)O(3), where catalytic activity for methane oxidation is enhanced under oscillating redox conditions at 500 °C, therefore paving the way to the practical application in three-way catalysts for stoichiometric natural gas engines.

  19. Methane related changes in prokaryotic activity along geochemical profiles in sediments of Lake Kinneret (Israel)

    NASA Astrophysics Data System (ADS)

    Bar Or, I.; Ben-Dov, E.; Kushmaro, A.; Eckert, W.; Sivan, O.

    2014-06-01

    Microbial methane oxidation process (methanotrophy) is the primary control on the emission of the greenhouse gas methane (CH4) to the atmosphere. In terrestrial environments, aerobic methanotrophic bacteria are mainly responsible for oxidizing the methane. In marine sediments the coupling of the anaerobic oxidation of methane (AOM) with sulfate reduction, often by a consortium of anaerobic methanotrophic archaea (ANME) and sulfate reducing bacteria, was found to consume almost all the upward diffusing methane. Recently, we showed geochemical evidence for AOM driven by iron reduction in Lake Kinneret (LK) (Israel) deep sediments and suggested that this process can be an important global methane sink. The goal of the present study was to link the geochemical gradients found in the porewater (chemical and isotope profiles) with possible changes in microbial community structure. Specifically, we examined the possible shift in the microbial community in the deep iron-driven AOM zone and its similarity to known sulfate driven AOM populations. Screening of archaeal 16S rRNA gene sequences revealed Thaumarchaeota and Euryarchaeota as the dominant phyla in the sediment. Thaumarchaeota, which belongs to the family of copper containing membrane-bound monooxgenases, increased with depth while Euryarchaeota decreased. This may indicate the involvement of Thaumarchaeota, which were discovered to be ammonia oxidizers but whose activity could also be linked to methane, in AOM in the deep sediment. ANMEs sequences were not found in the clone libraries, suggesting that iron-driven AOM is not through sulfate. Bacterial 16S rRNA sequences displayed shifts in community diversity with depth. Proteobacteria and Chloroflexi increased with depth, which could be connected with their different dissimilatory anaerobic processes. The observed changes in microbial community structure suggest possible direct and indirect mechanisms for iron-driven AOM in deep sediments.

  20. In vitro Screening of Essential Oil Active Compounds for Manipulation of Rumen Fermentation and Methane Mitigation

    PubMed Central

    Joch, M.; Cermak, L.; Hakl, J.; Hucko, B.; Duskova, D.; Marounek, M.

    2016-01-01

    The objective of this study was to investigate the effects of 11 active compounds of essential oils (ACEO) on rumen fermentation characteristics and methane production. Two trials were conducted. In trial 1, ACEO (eugenol, carvacrol, citral, limonene, 1,4-cineole, p-cymene, linalool, bornyl acetate, α-pinene, and β-pinene) at a dose of 1,000 μL/L were incubated for 24 h in diluted rumen fluid with a 70:30 forage:concentrate substrate (16.2% crude protein; 36.6% neutral detergent fiber). Three fistulated Holstein cows were used as donors of rumen fluid. The reduction in methane production was observed with nine ACEO (up to 86% reduction) compared with the control (p<0.05). Among these, only limonene, 1,4-cineole, bornyl acetate, and α-pinene did not inhibit volatile fatty acid (VFA) production, and only bornyl acetate produced less methane per mol of VFA compared with the control (p<0.05). In a subsequent trial, the effects on rumen fermentation and methane production of two concentrations (500 and 2,000 μL/L) of bornyl acetate, the most promising ACEO from the first trial, were evaluated using the same in vitro incubation method that was used in the first trial. In trial 2, monensin was used as a positive control. Both doses of bornyl acetate decreased (p<0.05) methane production and did not inhibit VFA production. Positive effects of bornyl acetate on methane and VFA production were more pronounced than the effects of monensin. These results confirm the ability of bornyl acetate to decrease methane production, which may help to improve the efficiency of energy use in the rumen. PMID:26954157

  1. An active atmospheric methane sink in high Arctic mineral cryosols

    DOE PAGES

    Lau, Maggie C.Y.; Stackhouse, B.; Layton, Alice C.; ...

    2015-01-01

    The transition of Arctic carbon-rich cryosols into methane (CH₄)-emitting wetlands due to global warming is a rising concern. However, the spatially predominant mineral cryosols and their CH₄ emission potential are poorly understood. Fluxes measured in situ and estimated under laboratory conditions coupled with -omics analysis indicate (1) mineral cryosols in the Canadian high Arctic contain atmospheric CH₄-oxidizing bacteria; (2) the atmospheric CH⁺ uptake flux increases with ground temperature; and, as a result, (3) the atmospheric CH₄ sink strength will increase by a factor of 5-30 as the Arctic warms by 5-15 °C over a century. We demonstrated that acidic mineralmore » cryosols have previously unrecognized potential of negative CH₄ feedback.« less

  2. An active atmospheric methane sink in high Arctic mineral cryosols

    SciTech Connect

    Lau, Maggie C.Y.; Stackhouse, B.; Layton, Alice C.; Chauhan, Archana; Vishnivetskaya, T. A.; Chourey, Karuna; Mykytczuk, N. C.S.; Bennett, Phil C.; Lamarche-Gagnon, G.; Burton, N.; Renholm, J.; Hettich, R. L.; Pollard, W. H.; Omelon, C. R.; Medvigy, David M.; Pffifner, Susan M.; Whyte, L. G.; Onstott, T. C.

    2015-01-01

    The transition of Arctic carbon-rich cryosols into methane (CH₄)-emitting wetlands due to global warming is a rising concern. However, the spatially predominant mineral cryosols and their CH₄ emission potential are poorly understood. Fluxes measured in situ and estimated under laboratory conditions coupled with -omics analysis indicate (1) mineral cryosols in the Canadian high Arctic contain atmospheric CH₄-oxidizing bacteria; (2) the atmospheric CH⁺ uptake flux increases with ground temperature; and, as a result, (3) the atmospheric CH₄ sink strength will increase by a factor of 5-30 as the Arctic warms by 5-15 °C over a century. We demonstrated that acidic mineral cryosols have previously unrecognized potential of negative CH₄ feedback.

  3. Do Sedentary Older Adults Benefit from Community-Based Exercise? Results from the Active Start Program

    ERIC Educational Resources Information Center

    Yan, Tingjian; Wilber, Kathleen H.; Aguirre, Rosa; Trejo, Laura

    2009-01-01

    Purpose: This study assessed the effectiveness of Active Start, a community-based behavior change and fitness program, designed to promote physical activity among sedentary community-dwelling older adults. Design and Methods: A quasi-experimental design was used. Data were analyzed using a within-group pretest-post-test design to calculate changes…

  4. Diversity and methane oxidation of active epibiotic methanotrophs on live Shinkaia crosnieri

    PubMed Central

    Watsuji, Tomo-o; Yamamoto, Asami; Takaki, Yoshihiro; Ueda, Kenji; Kawagucci, Shinsuke; Takai, Ken

    2014-01-01

    Shinkaia crosnieri is a galatheid crab that predominantly dwells in deep-sea hydrothermal systems in the Okinawa Trough, Japan. In this study, the phylogenetic diversity of active methanotrophs in the epibiotic microbial community on the setae of S. crosnieri was characterized by reverse transcription-polymerase chain reaction (RT-PCR) of a functional gene (pmoA) encoding a subunit of particulate methane monooxygenase. Phylogenetic analysis of pmoA transcript sequences revealed that the active epibiotic methanotrophs on S. crosnieri setae consisted of gammaproteobacterial type Ia and Ib methanotrophs. The effect of different RNA stabilization procedures on the abundance of pmoA and 16S rRNA transcripts in the epibiotic community was estimated by quantitative RT-PCR. Our novel RNA fixation method performed immediately after sampling effectively preserved cellular RNA assemblages, particularly labile mRNA populations, including pmoA mRNA. Methane consumption in live S. crosnieri was also estimated by continuous-flow incubation under atmospheric and in situ hydrostatic pressures, and provided a clear evidence of methane oxidation activity of the epibiotic microbial community, which was not significantly affected by hydrostatic pressure. Our study revealed the significant ecological function and nutritional contribution of epibiotic methanotrophs to the predominant S. crosnieri populations in the Okinawa Trough deep-sea hydrothermal systems. In conclusion, our study gave clear facts about diversity and methane oxidation of active methanotrophs in the epibiotic community associated with invertebrates. PMID:24401859

  5. MERLIN : a Franco-German active space mission dedicated to atmospheric methane

    NASA Astrophysics Data System (ADS)

    Bousquet, P.; Marshall, J.; Pierangelo, C.; Ehret, G.; Bacour, C.; Chevallier, F.; Gibert, F.; Crevoisier, C. D.; Edouart, D.; Esteve, F.; Chinaud, J.; Armante, R.; Berthier, S.; Alpers, M.; Millet, B.

    2015-12-01

    The Methane Remote Sensing Lidar Mission (MERLIN), currently in phase B, is a joint cooperation between France and Germany on the development, launch and operation of a space LIDAR dedicated to the retrieval of total methane (CH4) atmospheric columns. Atmospheric methane is the second most anthropogenic gas, contributing 20% to climate radiative forcing but also plying an important role in atmospheric chemistry as a precursor of tropospheric ozone and low-stratosphere water vapour. For the first time, measurements of atmospheric composition will be performed from space thanks to an IPDA (Integrated Path Differential Absorption) LIDAR (Light Detecting And Ranging), with a precision (target 20 ppb for a 50km aggregation along the trace) and accuracy (target 3 ppb) sufficient to improve the constraints on methane fluxes compared to current observation networks. The very low systematic error target is ambitious compared to current methane space mission, but achievable because of the differential active measurements of MERLIN, which guarantees almost no contamination by aerosols or water vapour cross-sensitivity. As an active mission, MERLIN will deliver data for all seasons and all altitudes, day and night. Here, we present the MERLIN mission and its objectives in terms of reduction of uncertainties on methane surface emissions. To do so, we propose an OSSE analysis (observing system simulation experiment) to estimate the uncertainty reduction brought by MERLIN. The originality of our system is to transfer both random and systematic errors from the observation space to the flux space, thus providing more realistic error reductions than currently provided in OSSE only using the random part of errors. To do so, a precise analysis of causes of errors has been done for the MERLIN mission and is also presented.

  6. MERLIN : a Franco-German active space mission dedicated to atmospheric methane

    NASA Astrophysics Data System (ADS)

    Bousquet, Philippe; Gibert, Fabien; Marshall, Julia; Pierangelo, Clémence; Ehret, Gerhard; Bacour, Cédric; Chevallier, Frédéric; Crevoisier, Cyril; Edouart, Dimitri; Esteve, Frédéric; Chinaud, Jordi; Armante, Raymond; Kiemle, Christoph; Alpers, Matthias; Tinto, Fransesc; Millet, Bruno

    2016-04-01

    The Methane Remote Sensing Lidar Mission (MERLIN), currently in phase B, is a joint cooperation between France and Germany on the development, launch and operation of a space LIDAR dedicated to the retrieval of total methane (CH4) atmospheric columns. Atmospheric methane is the second most anthropogenic gas, contributing 20% to climate radiative forcing but also plying an important role in atmospheric chemistry as a precursor of tropospheric ozone and low-stratosphere water vapour. For the first time, measurements of atmospheric composition will be performed from space thanks to an IPDA (Integrated Path Differential Absorption) LIDAR (Light Detecting And Ranging), with a precision (target 20 ppb for a 50km aggregation along the trace) and accuracy (target 3 ppb) sufficient to improve the constraints on methane fluxes compared to current observation networks. The very low systematic error target is ambitious compared to current methane space mission, but achievable because of the differential active measurements of MERLIN, which guarantees almost no contamination by aerosols or water vapour cross-sensitivity. As an active mission, MERLIN will deliver data for all seasons and all altitudes, day and night. Here, we present the MERLIN mission and its objectives in terms of reduction of uncertainties on methane surface emissions. To do so, we propose an OSSE analysis (observing system simulation experiment) to estimate the uncertainty reduction brought by MERLIN. An analysis of causes of errors has been done for the MERLIN mission and is presented. The originality of our system is to transfer both random and systematic errors from the observation space to the flux space, thus providing more realistic error reductions than currently provided in OSSE only using the random part of errors. Error reductions are presented using two different atmospheric transport models, TM3 and LMDZ, and compared with error reductions achieved with the GOSAT passive mission.

  7. Start-up of the Anammox process from the conventional activated sludge in a membrane bioreactor.

    PubMed

    Wang, Tao; Zhang, Hanmin; Yang, Fenglin; Liu, Sitong; Fu, Zhimin; Chen, Huihui

    2009-05-01

    A lab-scale membrane bioreactor (MBR) was used to start-up the anaerobic ammonium oxidation (Anammox) process from the conventional activated sludge for 2 months. Results indicated the MBR could be a novel and suitable system for start-up of the Anammox process. The Anammox activity appeared after 16 days operation, and the average removal efficiencies of ammonia and nitrite were both over 90% in the end. A final specific Anammox activity of 0.35 g NH(4)(+)-N+NO(2)(-)-N (gVSS *d)(-1) was obtained. Fluorescence in situ hybridization (FISH) analysis confirmed the existence of Anammox bacteria and aerobic ammonia oxidizing bacteria. On the basis of results on MBR performance and FISH analysis, it was proposed that the start-up process was essentially a microbial community succession under man-made disturbance, and a climax community with Anammox bacteria as the dominant population was finally established.

  8. Comparison between MBR and SBR on Anammox start-up process from the conventional activated sludge.

    PubMed

    Wang, Tao; Zhang, Hanmin; Gao, Dawen; Yang, Fenglin; Zhang, Guangyi

    2012-10-01

    Anammox start-up performances from the conventional activated sludge were compared between a MBR and SBR. Both the reactors successfully started up Anammox process. The start-up period in the MBR (59 days) was notably shorter than that in the SBR (101 days), and the max nitrogen (NH(4)(+)+NO(2)(-)) removal capacity of 345.2 mg N L(-1) d(-1) in the MBR was also higher than that of 292.0 mg N L(-1) d(-1) in the SBR. FISH analysis showed that Anammox bacteria predominated in both reactors. Phylogenetic analysis further disclosed that the MBR had the better biodiversity of Anammox bacteria and gained a higher ecological stability. Generally, the results showed that MBR exhibited a more excellent performance for Anammox start-up.

  9. Growth and activity of ANME clades with different sulfate and sulfide concentrations in the presence of methane

    PubMed Central

    Timmers, Peer H. A.; Widjaja-Greefkes, H. C. A.; Ramiro-Garcia, Javier; Plugge, Caroline M.; Stams, Alfons J. M.

    2015-01-01

    Extensive geochemical data showed that significant methane oxidation activity exists in marine sediments. The organisms responsible for this activity are anaerobic methane-oxidizing archaea (ANME) that occur in consortia with sulfate-reducing bacteria. A distinct zonation of different clades of ANME (ANME-1, ANME-2a/b, and ANME-2c) exists in marine sediments, which could be related to the localized concentrations of methane, sulfate, and sulfide. In order to test this hypothesis we performed long-term incubation of marine sediments under defined conditions with methane as a headspace gas: low or high sulfate (±4 and ±21 mM, respectively) in combination with low or high sulfide (±0.1 and ±4 mM, respectively) concentrations. Control incubations were also performed, with only methane, high sulfate, or high sulfide. Methane oxidation was monitored and growth of subtypes ANME-1, ANME-2a/b, and ANME-2c assessed using qPCR analysis. A preliminary archaeal community analysis was performed to gain insight into the ecological and taxonomic diversity. Almost all of the incubations with methane had methane oxidation activity, with the exception of the incubations with combined low sulfate and high sulfide concentrations. Sulfide inhibition occurred only with low sulfate concentrations, which could be due to the lower Gibbs free energy available as well as sulfide toxicity. ANME-2a/b appears to mainly grow in incubations which had high sulfate levels and methane oxidation activity, whereas ANME-1 did not show this distinction. ANME-2c only grew in incubations with only sulfate addition. These findings are consistent with previously published in situ profiling analysis of ANME subclusters in different marine sediments. Interestingly, since all ANME subtypes also grew in incubations with only methane or sulfate addition, ANME may also be able to perform anaerobic methane oxidation under substrate limited conditions or alternatively perform additional metabolic processes. PMID

  10. [Surface characteristics of alkali modified activated carbon and the adsorption capacity of methane].

    PubMed

    Zhang, Meng-Zhu; Li, Lin; Liu, Jun-Xin; Sun, Yong-Jun; Li, Guo-Bin

    2013-01-01

    Coconut shell based activated carbon was modified by alkali with different concentrations. The surface structures of tested carbons were observed and analyzed by SEM and BET methods. Boehm's titration and SEM/EDS methods were applied to assay the functional groups and elements on the carbon surface. The adsorption of methane on tested carbons was investigated and adsorption behavior was described by the adsorption isotherms. Results showed that surface area and pore volume of modified carbon increased and surface oxygen groups decreased as the concentration of the alkali used increased, with no obvious change in pore size. When concentration of alkali was higher than 3.3 mol x L(-1), the specific surface area and pore volume of modified carbon was larger than that of original carbon. Methane adsorption capacity of alkali modified carbon increased 24%. Enlargement of surface area and pore volume, reduction of surface oxygen groups will benefit to enhance the methane adsorption ability on activated carbon. Adsorption behavior of methane followed the Langmuir isotherm and the adsorption coefficient was 163.7 m3 x mg(-1).

  11. Impacts of inoculum pre-treatments on enzyme activity and biochemical methane potential.

    PubMed

    Wang, Bing; Strömberg, Sten; Nges, Ivo Achu; Nistor, Mihaela; Liu, Jing

    2016-05-01

    Biochemical methane potential (BMP) tests were carried out to investigate the influence of inoculum pre-treatments (filtration and pre-incubation) on methane production from cellulose and wheat straw. First-order model and Monod model were used to evaluate the kinetic constants of the BMP assays. The results demonstrated that fresh inoculum was the best option to perform BMP tests. This was evidenced by highest enzyme activity (0.11 U/mL) and highest methane yields for cellulose (356 NmL CH4/gVS) as well as wheat straw (261 NmL CH4/gVS). Besides, high biodegradability (85.8% for cellulose and 61.3% for wheat straw) was also obtained when the fresh inoculum was used. Moreover, a kinetic evaluation showed that inoculum pre-incubation at 37°C or storage at 4°C introduced a lag-time whereas the effects on hydrolysis rate were less consequent. In summary, pre-treatments affected the enzyme activity of the inoculum, and further on, significantly influenced the methane production and the degradation kinetics of the investigated substrates. It is recommended that filtration of inoculum should be avoided unless in case too large particles therein.

  12. Supporting Head Start Parents: Impact of a Text Message Intervention on Parent-Child Activity Engagement

    ERIC Educational Resources Information Center

    Hurwitz, Lisa B.; Lauricella, Alexis R.; Hanson, Ann; Raden, Anthony; Wartella, Ellen

    2015-01-01

    Head Start emphasises parent engagement as a critical strategy in promoting children's long-term learning. Parents can support children's positive development by engaging them in stimulating activities. The following study assessed whether a service that delivered parenting tips via text message could prompt parents of children enrolled in Head…

  13. Bringout Out Head Start Talents (BOHST). Talent Activities for the Home.

    ERIC Educational Resources Information Center

    Berg, Linda; Patten, Margaret

    Designed for use by parents of preschoolers participating in the Bringing Out Head Start Talents (BOHST) project, nine booklets present home activities intended to fit into the parent's and child's normal routines. Each booklet addresses a separate talent area: intellectual, creativity, leadership, art, music, reading, math, science, and…

  14. Effect of altering starting length and activation timing of muscle on fiber strain and muscle damage.

    PubMed

    Butterfield, Timothy A; Herzog, Walter

    2006-05-01

    Muscle strain injuries are some of the most frequent injuries in sports and command a great deal of attention in an effort to understand their etiology. These injuries may be the culmination of a series of subcellular events accumulated through repetitive lengthening (eccentric) contractions during exercise, and they may be influenced by a variety of variables including fiber strain magnitude, peak joint torque, and starting muscle length. To assess the influence of these variables on muscle injury magnitude in vivo, we measured fiber dynamics and joint torque production during repeated stretch-shortening cycles in the rabbit tibialis anterior muscle, at short and long muscle lengths, while varying the timing of activation before muscle stretch. We found that a muscle subjected to repeated stretch-shortening cycles of constant muscle-tendon unit excursion exhibits significantly different joint torque and fiber strains when the timing of activation or starting muscle length is changed. In particular, measures of fiber strain and muscle injury were significantly increased by altering activation timing and increasing the starting length of the muscle. However, we observed differential effects on peak joint torque during the cyclic stretch-shortening exercise, as increasing the starting length of the muscle did not increase torque production. We conclude that altering activation timing and muscle length before stretch may influence muscle injury by significantly increasing fiber strain magnitude and that fiber dynamics is a more important variable than muscle-tendon unit dynamics and torque production in influencing the magnitude of muscle injury.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  16. Seasons on Saturn. II. Influence of solar activity on variation of methane absorption

    NASA Astrophysics Data System (ADS)

    Vidmachenko, A. P.

    2015-10-01

    Methane and ammonia in the atmosphere of Saturn are in the form of impurities at the level of less than tenths of a percentage. They take part in photochemical processes, the main products of which are hydrocarbons and ammonia NH3. Polyacetylenes absorb sunlight almost to 400 nm, and hydrocarbons <180 nm. Therefore, the solar activity cycle, the slope of the equator to the plane of the orbit, the orbital motion and the presence of the rings induce change in composition of the upper atmosphere. Radiation constants in the atmosphere depend on the physical and chemical conditions, decreasing from ~10 years at the visible clouds level, to months in tropopause, and days in stratosphere. The observed seasonal effects may be associated also with condensation and convection, and the dynamic time scale may be only tens of hours. The data analysis on the methane absorption distribution over the disk of Saturn for 1964-2012 showed a significant seasonal changes in the levels of visible clouds and above clouds haze. Changes of methane absorption along the meridian in the equinox 1966 and 1995, had the opposite course to the results in equinox 1980. But the expected differences in the change of methane absorption at the equinox 2009, similar to 1980, did not happen. Although all the physical and orbital characteristics of Saturn at equinoxes in these moments repeated, but the response to them were received various. A few years before the equinox in 1966, 1980 and 1995, the number of R, characterizing solar activity, varied from 40 to 180. Before equinox 2009 the Sun has minimal activity and the R value was practically zero. According to observations at the time of equinox 2009, convection in the Saturn's atmosphere stayed at a minimal level. After exiting of rings shadows in winter northern hemisphere deep cloud layer was "frozen" at the same low level at absence of active processes on the Sun. This allowed easily to register a thick layer of methane and ammonia gas. So how

  17. Enhanced methane storage of chemically and physically activated carbide-derived carbon

    NASA Astrophysics Data System (ADS)

    Yeon, Sun-Hwa; Osswald, Sebastian; Gogotsi, Yury; Singer, Jonathan P.; Simmons, Jason M.; Fischer, John E.; Lillo-Ródenas, María A.; Linares-Solano, Ángel

    Carbide-derived carbons (CDCs) produced by chlorination of carbides offer great potential for precise pore size control at the atomic level, making them attractive candidates for energy storage media. CDCs activated with CO 2 or KOH possess distinct improvements in porosity, displaying specific surface areas above 3000 m 2 g -1 and pore volumes above 1.3 cm 3 g -1. These correspond to gravimetric methane uptake of 16 wt% at 35 bar and 25 °C, close to the currently best reported material PCN-14, a metal-organic framework (MOF), at 35 bar and 17 °C or KOH activated anthracite at 35 bar and 25 °C. The best excess gravimetric methane uptake is obtained with a TiC-derived CDC activated with CO 2 at 975 °C for 2 h, namely a very large surface area of 3360 m 2 g -1 resulting in 18.5 wt% at 25 °C and 60 bar. To obtain realistic volumetric methane capacity, the packing density of completely dried CDC was measured, from which we obtain excess capacity of 145 v(STP) v -1 from CDC activated with CO 2 at 875 °C for 8 h, 81% of the DOE target (180 v(STP) v -1) at 35 bar and 25 °C. From small-angle X-ray scattering (SAXS) measurements, pore radii of gyration (R g) between 0.5 nm and 1 nm are determined. Temperature-dependent methane isotherms show that the isosteric heat of adsorption reaches 24 kJ mol -1 at the initial stage of low loading.

  18. Differential methane oxidation activity and microbial community composition at cold seeps in the Arctic off western Svalbard

    NASA Astrophysics Data System (ADS)

    Gründger, Friederike; Svenning, Mette M.; Niemann, Helge; Silyakova, Anna; Serov, Pavel; Li Hong, Wei; Wegener, Gunter; Panieri, Giuliana; Carroll, JoLynn

    2016-04-01

    Most models considering climate change related bottom water warming suggest that gas hydrates may become destabilized, leading to the mobilization of methane into seabed and water column ecosystems, and, eventually, into the atmosphere. However, the capacity of methanotrophic microbes retaining methane in sediments and the hydrosphere is not well constrained. Here, we investigate the microbial utilization of methane in sediments and the water column, focusing on cold seeps discovered at the arctic continental margin of western Svalbard. We measured ex situ rates of methane oxidation and sulfate reduction in two active gas flare sites with different geological settings at the Vestnesa Ridge (1204 m water depth) and within a pingolike feature area southwest off Svalbard (PLF; 380 m water depth). Our results show contrarily situations at our two sampling sites: At Vestnesa Ridge we find high methane oxidation rates with values up to 2055 nmol cm-3 d-1 at the sediment surface where the sediments are oversaturated with methane. Whereas, methane concentration and oxidation rates are low in the overlying water column (2 pmol cm-3 d-1). In contrast, at the sediment surface at PLF methane concentration and oxidation rates are considerably lower (up to 1.8 nmol cm-3 d-1). While the overlying bottom water contains high concentration of methane and shows oxidation rates with values of up to 3.8 nmol cm-3 d-1. The data on methane oxidation and sulfate reduction activity are compared to the sediment geochemistry and to data from metagenomic analysis identifying the methanotrophic community composition. These results provide unique insight into the dynamic responses of the seabed biological filter at cold seeps in the Arctic off western Svalbard. This study is part of the Centre for Arctic Gas Hydrate, Environment and Climate and was supported by the Research Council of Norway through its Centres of Excellence funding scheme grant No. 223259.

  19. Activity and interactions of methane seep microorganisms assessed by parallel transcription and FISH-NanoSIMS analyses

    PubMed Central

    Dekas, Anne E; Connon, Stephanie A; Chadwick, Grayson L; Trembath-Reichert, Elizabeth; Orphan, Victoria J

    2016-01-01

    To characterize the activity and interactions of methanotrophic archaea (ANME) and Deltaproteobacteria at a methane-seeping mud volcano, we used two complimentary measures of microbial activity: a community-level analysis of the transcription of four genes (16S rRNA, methyl coenzyme M reductase A (mcrA), adenosine-5′-phosphosulfate reductase α-subunit (aprA), dinitrogenase reductase (nifH)), and a single-cell-level analysis of anabolic activity using fluorescence in situ hybridization coupled to nanoscale secondary ion mass spectrometry (FISH-NanoSIMS). Transcript analysis revealed that members of the deltaproteobacterial groups Desulfosarcina/Desulfococcus (DSS) and Desulfobulbaceae (DSB) exhibit increased rRNA expression in incubations with methane, suggestive of ANME-coupled activity. Direct analysis of anabolic activity in DSS cells in consortia with ANME by FISH-NanoSIMS confirmed their dependence on methanotrophy, with no 15NH4+ assimilation detected without methane. In contrast, DSS and DSB cells found physically independent of ANME (i.e., single cells) were anabolically active in incubations both with and without methane. These single cells therefore comprise an active ‘free-living' population, and are not dependent on methane or ANME activity. We investigated the possibility of N2 fixation by seep Deltaproteobacteria and detected nifH transcripts closely related to those of cultured diazotrophic Deltaproteobacteria. However, nifH expression was methane-dependent. 15N2 incorporation was not observed in single DSS cells, but was detected in single DSB cells. Interestingly, 15N2 incorporation in single DSB cells was methane-dependent, raising the possibility that DSB cells acquired reduced 15N products from diazotrophic ANME while spatially coupled, and then subsequently dissociated. With this combined data set we address several outstanding questions in methane seep microbial ecosystems and highlight the benefit of measuring microbial activity in the

  20. Activity and interactions of methane seep microorganisms assessed by parallel transcription and FISH-NanoSIMS analyses.

    PubMed

    Dekas, Anne E; Connon, Stephanie A; Chadwick, Grayson L; Trembath-Reichert, Elizabeth; Orphan, Victoria J

    2016-03-01

    To characterize the activity and interactions of methanotrophic archaea (ANME) and Deltaproteobacteria at a methane-seeping mud volcano, we used two complimentary measures of microbial activity: a community-level analysis of the transcription of four genes (16S rRNA, methyl coenzyme M reductase A (mcrA), adenosine-5'-phosphosulfate reductase α-subunit (aprA), dinitrogenase reductase (nifH)), and a single-cell-level analysis of anabolic activity using fluorescence in situ hybridization coupled to nanoscale secondary ion mass spectrometry (FISH-NanoSIMS). Transcript analysis revealed that members of the deltaproteobacterial groups Desulfosarcina/Desulfococcus (DSS) and Desulfobulbaceae (DSB) exhibit increased rRNA expression in incubations with methane, suggestive of ANME-coupled activity. Direct analysis of anabolic activity in DSS cells in consortia with ANME by FISH-NanoSIMS confirmed their dependence on methanotrophy, with no (15)NH4(+) assimilation detected without methane. In contrast, DSS and DSB cells found physically independent of ANME (i.e., single cells) were anabolically active in incubations both with and without methane. These single cells therefore comprise an active 'free-living' population, and are not dependent on methane or ANME activity. We investigated the possibility of N2 fixation by seep Deltaproteobacteria and detected nifH transcripts closely related to those of cultured diazotrophic Deltaproteobacteria. However, nifH expression was methane-dependent. (15)N2 incorporation was not observed in single DSS cells, but was detected in single DSB cells. Interestingly, (15)N2 incorporation in single DSB cells was methane-dependent, raising the possibility that DSB cells acquired reduced (15)N products from diazotrophic ANME while spatially coupled, and then subsequently dissociated. With this combined data set we address several outstanding questions in methane seep microbial ecosystems and highlight the benefit of measuring microbial activity in

  1. Design, synthesis, cytotoxicities and DNA cleavage activities of dibenzoxepine and isoquinoline derivatives starting from dehydroabietylamine.

    PubMed

    Liu, Chao-Xiang; Lin, Zhong-Xiang; Zhou, Ai-Min

    2016-12-01

    A series of novel hexahydrodibenzoxepine and quinazoline derivatives were designed and synthesized starting from dehydroabietylamine. The cytotoxicities of the compounds against L02 and HepG2 cell lines were investigated. Meanwhile, the plasmid DNA (Escherichia coli) cleavage of several heterocyclic derivatives was studied. These compounds exhibit remarkable activities on plasmid DNA pBR322. Our study provides useful information for developing new and more potent antitumor agents.

  2. Enzymatic and metabolic activities of four anaerobic sludges and their impact on methane production from ensiled sorghum forage.

    PubMed

    Sambusiti, C; Rollini, M; Ficara, E; Musatti, A; Manzoni, M; Malpei, F

    2014-03-01

    Biochemical methane potential (BMP) tests were run on ensiled sorghum forage using four inocula (urban, agricultural, mixture of agricultural and urban, granular) and differences on their metabolic and enzymatic activities were also discussed. Results indicate that no significant differences were observed in terms of BMP values (258±14NmLCH4g(-1)VS) with a slightly higher value when agricultural sludge was used as inoculum. Significant differences can be observed among different inocula, in terms of methane production rate. In particular the fastest biomethanization occurred when using the urban sludge (hydrolytic kinetic constant kh=0.146d(-1)) while the slowest one was obtained from the agricultural sludge (kh=0.049d(-1)). Interestingly, positive correlations between the overall enzymatic activities and methane production rates were observed for all sludges, showing that a high enzymatic activity may favour the hydrolysis of complex substrate and accelerate the methanization process of sorghum.

  3. Methane activation by platinum: critical role of edge and corner sites of metal nanoparticles.

    PubMed

    Viñes, Francesc; Lykhach, Yaroslava; Staudt, Thorsten; Lorenz, Michael P A; Papp, Christian; Steinrück, Hans-Peter; Libuda, Jörg; Neyman, Konstantin M; Görling, Andreas

    2010-06-11

    Complete dehydrogenation of methane is studied on model Pt catalysts by means of state-of-the-art DFT methods and by a combination of supersonic molecular beams with high-resolution photoelectron spectroscopy. The DFT results predict that intermediate species like CH(3) and CH(2) are specially stabilized at sites located at particles edges and corners by an amount of 50-80 kJ mol(-1). This stabilization is caused by an enhanced activity of low-coordinated sites accompanied by their special flexibility to accommodate adsorbates. The kinetics of the complete dehydrogenation of methane is substantially modified according to the reaction energy profiles when switching from Pt(111) extended surfaces to Pt nanoparticles. The CH(3) and CH(2) formation steps are endothermic on Pt(111) but markedly exothermic on Pt(79). An important decrease of the reaction barriers is observed in the latter case with values of approximately 60 kJ mol(-1) for first C-H bond scission and 40 kJ mol(-1) for methyl decomposition. DFT predictions are experimentally confirmed by methane decomposition on Pt nanoparticles supported on an ordered CeO(2) film on Cu(111). It is shown that CH(3) generated on the Pt nanoparticles undergoes spontaneous dehydrogenation at 100 K. This is in sharp contrast to previous results on Pt single-crystal surfaces in which CH(3) was stable up to much higher temperatures. This result underlines the critical role of particle edge sites in methane activation and dehydrogenation.

  4. Enrichment of specific electro-active microorganisms and enhancement of methane production by adding granular activated carbon in anaerobic reactors.

    PubMed

    Lee, Jung-Yeol; Lee, Sang-Hoon; Park, Hee-Deung

    2016-04-01

    Direct interspecies electron transfer (DIET) via conductive materials can provide significant benefits to anaerobic methane formation in terms of production amount and rate. Although granular activated carbon (GAC) demonstrated its applicability in facilitating DIET in methanogenesis, DIET in continuous flow anaerobic reactors has not been verified. Here, evidences of DIET via GAC were explored. The reactor supplemented with GAC showed 1.8-fold higher methane production rate than that without GAC (35.7 versus 20.1±7.1mL-CH4/d). Around 34% of methane formation was attributed to the biomass attached to GAC. Pyrosequencing of 16S rRNA gene demonstrated the enrichment of exoelectrogens (e.g. Geobacter) and hydrogenotrophic methanogens (e.g. Methanospirillum and Methanolinea) from the biomass attached to GAC. Furthermore, anodic and cathodic currents generation was observed in an electrochemical cell containing GAC biomass. Taken together, GAC supplementation created an environment for enriching the microorganisms involved in DIET, which increased the methane production rate.

  5. Kinetics and activation thermodynamics of methane monooxygenase compound Q formation and reaction with substrates.

    PubMed

    Brazeau, B J; Lipscomb, J D

    2000-11-07

    The transient kinetics of formation and decay of the reaction cycle intermediates of the Methylosinus trichosporium OB3b methane monooxygenase (MMO) catalytic cycle are studied as a function of temperature and substrate type and deuteration. Kinetic evidence is presented for the existence of three intermediates termed compounds O, P, and P forming after the addition of O(2) to diferrous MMO hydroxylase (H(r)) and before the formation of the reactive intermediate compound Q. The Arrhenius plots for these reactions are linear and independent of substrate concentration and type, showing that substrate does not participate directly in the oxygen activation phase of the catalytic cycle. Analysis of the transient kinetic data revealed only small changes relative to the weak optical spectrum of H(r) for any of these intermediates. In contrast, large changes in the 430 nm spectral region are associated with the formation of Q. The decay reaction of Q exhibits an apparent first-order concentration dependence for all substrates tested, and the observed rate constant depends on the substrate type. The kinetics of the decay reaction of Q yield a nonlinear Arrhenius plot when methane is the substrate, and the rates in both segments of the plot increase linearly with methane concentration. Together these observations suggest that at least two reactions with a methane concentration dependence, and perhaps two methane molecules, are involved in the decay process. When CD(4) is used as the substrate, a large isotope effect and a linear Arrhenius plot are observed. Analogous plots for all other MMO substrates tested (e.g., ethane) are linear, and no isotope effect for deuterated analogues is observed. This demonstrates that a step other than C-H bond breaking is rate limiting for alternative MMO substrates. A two step Q decay mechanism is proposed that provides an explanation for the lack of an isotope effect for alternative MMO substrates and the fact that rate of oxidation of

  6. Simultaneous enhancement of methane production and methane content in biogas from waste activated sludge and perennial ryegrass anaerobic co-digestion: The effects of pH and C/N ratio.

    PubMed

    Dai, Xiaohu; Li, Xiaoshuai; Zhang, Dong; Chen, Yinguang; Dai, Lingling

    2016-09-01

    It is necessary to find an appropriate strategy to simultaneously enhance the methane production and methane content in biogas from waste activated sludge (WAS) and grass co-digestion. In this study an efficient strategy, i.e., adjusting the initial pH 12 and C/N ratio 17/1, for simultaneous enhancement of methane production and methane content in biogas from WAS and perennial ryegrass co-digestion was reported. Experimental results indicated that the maximal methane production was 310mL/gVSadd at the optimum conditions after 30-d anaerobic digestion, which was, respectively, about 1.5- and 3.8-fold of the sole WAS and sole perennial ryegrass anaerobic digestion. Meanwhile, the methane content in biogas was about 74%, which was much higher than that of sole WAS (64%) or sole perennial ryegrass (54%) anaerobic digestion.

  7. Organic geochemical signatures controlling methane outgassing at active mud volcanoes in the Canadian Beaufort Sea

    NASA Astrophysics Data System (ADS)

    DongHun, Lee; YoungKeun, Jin; JungHyun, Kim; Heldge, Niemann; JongKu, Gal; BoHyung, Choi

    2016-04-01

    Based on the water column acoustic anomalies related to active methane (CH4) venting, numerous active Mud Volcanoes (MVs) were recently identified at ~282, ~420, and ~740 m water depths on the continental slope of the Canadian Beaufort Sea (Paull et al., 2015). While geophysical aspects such as the multibeam bathymetric mapping are thoroughly investigated, biogeochemical processes controlling outgassing CH4 at the active MVs are not well constrained. Here, we investigated three sediment cores from the active MVs and one sediment core from a non-methane influenced reference site recovered during the ARA-05C expedition with the R/V ARAON in 2014. We analyzed lipid biomarkers and their stable carbon isotopic values (δ13C) in order to determine key biogeochemical processes involved in CH4 cycling in the MV sediments. Downcore CH4 and sulphate (SO42-) concentration measurements revealed a distinct sulfate-methane transition zone (SMTZ) at the shallow sections of the cores (15 - 45 cm below seafloor (cm bsf) at 282 m MV, 420 m MV, and 740 m MV). The most abundant diagnostic lipid biomarkers in the SMTZ were sn-2-hydroxyarchaeol (-94‰) and archaeol (-66‰) with the sn-2-hydroxyarchaeol: archaeol ratio of 1.1 to 5, indicating the presence of ANME-2 or -3. However, we also found substantial amounts of monocyclic biphytane-1 (BP-1, -118‰), which is rather indicative for ANME-1. Nevertheless, the concentration of sn-2-hydroxyarchaeol was 2-fold higher than any other archaeal lipids, suggesting a predominant ANME-2 or -3 rather than ANME-1 as a driving force for the anaerobic methane oxidation (AOM) in these systems. We will further investigate the microbial community at the active MVs using nucleic acid (RNA and DNA) sequence analyses in near future. Our study provides first biogeochemical data set of the active MVs in the Canadian Beaufort Sea, which helps to better understand CH4 cycling mediated in these systems. Reference Paull, C.K., et al. (2015), Active mud

  8. Evaluating Active Methane Hydrate Dissociation Along the Washington Margin in Response to Bottom Water Warming

    NASA Astrophysics Data System (ADS)

    Whorley, T. L.; Solomon, E. A.; Torres, M. E.; Johnson, H. P.; Berg, R. D.; Philip, B. T.

    2015-12-01

    Water column temperature data acquired on the upper continental slope (UCS) of the Washington (WA) section of the Cascadia margin shows gradual warming of bottom water at the upper limit of the methane hydrate stability zone (MHSZ) over the last 4 decades. Thermal models based on these records predict downslope retreat of the MHSZ by ~1-2 km (~40 m in depth), potentially destabilizing methane hydrate and releasing CH4into the sediment and water column. To test for contemporaneous methane hydrate dissociation along the UCS of the WA margin, we conducted a comprehensive geophysical and geochemical survey of active seep sites at the upper limit of the MHSZ from 48° to 46°N on the R/V Thompson in October 2014. We identified 9 active seep sites within this corridor and imaged 22 bubble plumes that commonly rise to ~300 m water depth with some reaching to near the sea surface. Some seep sites appear to be controlled by local margin structure, mainly extensional faults and ridges. We collected 22 gravity cores and 20 CTD/hydrocasts from the 9 seeps and processed ~350 sediment samples for pore water chemistry. Hydrocarbons heavier than CH4were not detected in bottom water samples, suggesting any gas hydrate present is Structure I. Preliminary pore water data show decreasing salinity downcore at each site with measured values as low as 10 psu and the sulfate-methane transition zone occurs between 50-80 cm below the sea floor. Pore water solute, noble gas, and isotope ratio data indicate freshening from at least one site is not the result of hydrate dissociation, but rather is due to clay dehydration at depths where temperatures exceed 60°C. Very few of the sites show pore water profiles that are in steady state, suggesting a dynamic biogeochemical system at the UCS along the entire WA margin. Further analyses and modeling are underway to constrain the nature and timing of these transient profiles and whether they are the result of recent methane hydrate dissociation.

  9. Mechanistic Variants in Gas-Phase Metal-Oxide Mediated Activation of Methane at Ambient Conditions.

    PubMed

    Li, Jilai; Zhou, Shaodong; Zhang, Jun; Schlangen, Maria; Usharani, Dandamudi; Shaik, Sason; Schwarz, Helmut

    2016-09-07

    The C-H bond activation of methane mediated by a prototypical heteronuclear metal-oxide cluster, [Al2Mg2O5](•+), was investigated by using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) in conjunction with high-level quantum mechanical calculations. Experimentally, hydrogen-atom abstraction from methane by the cluster ion [Al2Mg2O5](•+) takes place at ambient conditions. As to the mechanism, according to our computational findings, both the proton-coupled electron transfer (PCET) and the conventional hydrogen-atom transfer (HAT) are feasible and compete with each other. This is in distinct contrast to the [XYO2](+) (X, Y = Mg, Al, Si) cluster oxide ions which activate methane exclusively via the PCET route (Li, J.; Zhou, S.; Zhang, J.; Schlangen, M.; Weiske, T.; Usharani, D.; Shaik, S.; Schwarz, H. J. Am. Chem. Soc. 2016, 138, 7973-7981). The electronic origins of the mechanistically rather complex reactivity scenarios of the [Al2Mg2O5](•+)/CH4 couple were elucidated. For the PCET mechanism, in which the Lewis acid-base pair [Al(+)-O(-)] of the cluster acts as the active site, a clear correlation has been established between the nature of the transition state, the corresponding barrier height, the Lewis acidity-basicity of the [M(+)-O(-)] unit, as well as the bond order of the M(+)-O(-) bond. Also addressed is the role of the spin and charge distributions of a terminal oxygen radical site in the direct HAT route. The knowledge of the factors that control the reactivity of PCET and HAT pathways not only deepens our mechanistic understanding of metal-oxide mediated C-H bond activation but may also provide guidance for the rational design of catalysts.

  10. Activated carbon derived from waste coffee grounds for stable methane storage.

    PubMed

    Kemp, K Christian; Baek, Seung Bin; Lee, Wang-Geun; Meyyappan, M; Kim, Kwang S

    2015-09-25

    An activated carbon material derived from waste coffee grounds is shown to be an effective and stable medium for methane storage. The sample activated at 900 °C displays a surface area of 1040.3 m(2) g(-1) and a micropore volume of 0.574 cm(3) g(-1) and exhibits a stable CH4 adsorption capacity of ∼4.2 mmol g(-1) at 3.0 MPa and a temperature range of 298 ± 10 K. The same material exhibits an impressive hydrogen storage capacity of 1.75 wt% as well at 77 K and 100 kPa. Here, we also propose a mechanism for the formation of activated carbon from spent coffee grounds. At low temperatures, the material has two distinct types with low and high surface areas; however, activation at elevated temperatures drives off the low surface area carbon, leaving behind the porous high surface area activated carbon.

  11. Methane production and consumption in an active volcanic environment of Southern Italy.

    PubMed

    Castaldi, Simona; Tedesco, Dario

    2005-01-01

    Methane fluxes were measured, using closed chambers, in the Crater of Solfatara volcano, Campi Flegrei (Southern Italy), along eight transects covering areas of the crater presenting different landscape physiognomies. These included open bare areas, presenting high geothermal fluxes, and areas covered by vegetation, which developed along a gradient from the central open area outwards, in the form of maquis, grassland and woodland. Methane fluxes decreased logarithmically (from 150 to -4.5 mg CH4 m(-2)day(-1)) going from the central part of the crater (fangaia) to the forested edges, similarly to the CO2 fluxes (from 1500 g CO2 m(-2)day(-1) in the centre of the crater to almost zero flux in the woodlands). In areas characterized by high emissions, soil presented elevated temperature (up to 70 degrees C at 0-10 cm depth) and extremely low pH (down to 1.8). Conversely, in woodland areas pH was higher (between 3.7 and 5.1) and soil temperature close to air values. Soil (0-10 cm) was sampled, in two different occasions, along the eight transects, and was tested for methane oxidation capacity in laboratory. Areas covered by vegetation mostly consumed CH4 in the following order woodland>macchia>grassland. Methanotrophic activity was also measured in soil from the open bare area. Oxidation rates were comparable to those measured in the plant covered areas and were significantly correlated with field CH4 emissions. The biological mechanism of uptake was demonstrated by the absence of activity in autoclaved replicates. Thus results suggest the existence of a population of micro-organisms adapted to this extreme environment, which are able to oxidize CH4 and whose activity could be stimulated and supported by elevated concentrations of CH4.

  12. Start Young!

    ERIC Educational Resources Information Center

    Rubin, Penni

    2002-01-01

    Discusses the importance of early interest in science and how effective it is on career choice in adult stages of life. Recommends starting mathematics and science activities in preschool and kindergarten. Describes how to create a career-oriented learning center in the classroom with examples of kitchen chemistry, nutrition/botany, zoology,…

  13. Bypass-activation of the complement system starting with C3

    PubMed Central

    Bitter-Suermann, D.; Dierich, M.; König, W.; Hadding, U.

    1972-01-01

    Antibody independent activation of the complement system starting with C3 can be achieved by means of a purified factor from cobra venom (VF), which interacts with a purified serum factor (SF). The latter is a normal constituent of guinea-pig and human serum (C3-proactivator). The interaction between VF and SF is Mg+ + dependent and leads to the formation of a complex. Immunological analysis reveals that both VF- and SF-antigens are contained in the complex. The VF—SF complex activates enzymatically isolated C3, which in the presence of the subsequent components yields all effects of the normal complement sequence. Purified C5 is not affected by the complex. Its activation is mediated by activated C3. The VF—SF system represents a model for direct activation of C3 to C9 independent of antibody, C1, C4 and C2. An analogous pathway of alternate complement activation might be used by other substances, e.g. endotoxin, guinea-pig γ1-immune aggregates and zymosan. The corresponding serum factors are under investigation. ImagesFIG. 5FIG. 6 PMID:4214761

  14. Redox dynamics in the active layer of an Arctic headwater catchment; examining the potential for transfer of dissolved methane from soils to stream water

    NASA Astrophysics Data System (ADS)

    Street, Lorna E.; Dean, Joshua F.; Billett, Michael F.; Baxter, Robert; Dinsmore, Kerry J.; Lessels, Jason S.; Subke, Jens-Arne; Tetzlaff, Doerthe; Wookey, Philip A.

    2016-11-01

    The linkages between methane production, transport, and release from terrestrial and aquatic systems are not well understood, complicating the task of predicting methane emissions. We present novel data examining the potential for the saturated zone of active layer soils to act as a source of dissolved methane to the aquatic system, via soil water discharge, within a headwater catchment of the continuous permafrost zone in Northern Canada. We monitored redox conditions and soil methane concentrations across a transect of soil profiles from midstream to hillslope and compare temporal patterns in methane concentrations in soils to those in the stream. We show that redox conditions in active layer soils become more negative as the thaw season progresses, providing conditions suitable for net methanogenesis and that redox conditions are sensitive to increased precipitation during a storm event—but only in shallower surface soil layers. While we demonstrate that methane concentrations at depth in the hillslope soils increase over the course of the growing season as reducing conditions develop, we find no evidence that this has an influence on stream water methane concentrations. Sediments directly beneath the stream bed, however, remain strongly reducing at depth throughout the thaw season and contain methane at concentrations 5 orders of magnitude greater than those in hillslope soils. The extent of substreambed methane sources, and the rates of methane transport from these zones, may therefore be important factors determining headwater stream methane concentrations under changing Arctic hydrologic regimes.

  15. Methane-Powered Vehicles

    NASA Technical Reports Server (NTRS)

    1982-01-01

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

  16. First evidence of widespread active methane seepage in the Southern Ocean, off the sub-Antarctic island of South Georgia

    NASA Astrophysics Data System (ADS)

    Römer, M.; Torres, M.; Kasten, S.; Kuhn, G.; Graham, A. G. C.; Mau, S.; Little, C. T. S.; Linse, K.; Pape, T.; Geprägs, P.; Fischer, D.; Wintersteller, P.; Marcon, Y.; Rethemeyer, J.; Bohrmann, G.

    2014-10-01

    An extensive submarine cold-seep area was discovered on the northern shelf of South Georgia during R/V Polarstern cruise ANT-XXIX/4 in spring 2013. Hydroacoustic surveys documented the presence of 133 gas bubble emissions, which were restricted to glacially-formed fjords and troughs. Video-based sea floor observations confirmed the sea floor origin of the gas emissions and spatially related microbial mats. Effective methane transport from these emissions into the hydrosphere was proven by relative enrichments of dissolved methane in near-bottom waters. Stable carbon isotopic signatures pointed to a predominant microbial methane formation, presumably based on high organic matter sedimentation in this region. Although known from many continental margins in the world's oceans, this is the first report of an active area of methane seepage in the Southern Ocean. Our finding of substantial methane emission related to a trough and fjord system, a topographical setting that exists commonly in glacially-affected areas, opens up the possibility that methane seepage is a more widespread phenomenon in polar and sub-polar regions than previously thought.

  17. Hydrogen production by thermo-catalytic decomposition of methane: Regeneration of active carbons using CO 2

    NASA Astrophysics Data System (ADS)

    Pinilla, J. L.; Suelves, I.; Utrilla, R.; Gálvez, M. E.; Lázaro, M. J.; Moliner, R.

    Thermo-catalytic decomposition of methane using carbons as catalyst is a very attractive process for free CO 2-hydrogen production. One of the main drawbacks for the sustainability of the process is catalyst deactivation. In this work, regeneration of a deactivated active-carbon catalyst has been studied using CO 2 as activating agent under different regeneration conditions. It has been stated that during the regeneration stage, a compromise between the regeneration of the initial properties of the catalyst and the burn-off is needed in order to keep the sustainability of the process. Three deactivation-regeneration cycles have been performed for two sets of regeneration conditions. A progressive decreasing in the burn-off, surface area and surface oxygenated groups after each decomposition/regeneration cycle is observed. It can be explained considering that the carbon removed during the regeneration steps is not the carbon deposited from methane but the remaining initial catalyst, which is less resistant to gasification. The implication is that after three cycles of decomposition/regeneration, most of the carbon sample consists of carbon formed during the process since the initial catalyst has been gasified.

  18. Effects of Flavonoids on Rumen Fermentation Activity, Methane Production, and Microbial Population

    PubMed Central

    Abdullah, Norhani; Oskoueian, Armin

    2013-01-01

    This research was carried out to evaluate the effects of flavone, myricetin, naringin, catechin, rutin, quercetin, and kaempferol at the concentration of 4.5% of the substrate (dry matter basis) on the rumen microbial activity in vitro. Mixture of guinea grass and concentrate (60 : 40) was used as the substrate. The results showed that all the flavonoids except naringin and quercetin significantly (P < 0.05) decreased the dry matter degradability. The gas production significantly (P < 0.05) decreased by flavone, myricetin, and kaempferol, whereas naringin, rutin, and quercetin significantly (P < 0.05) increased the gas production. The flavonoids suppressed methane production significantly (P < 0.05). The total VFA concentration significantly (P < 0.05) decreased in the presence of flavone, myricetin, and kaempferol. All flavonoids except naringin and quercetin significantly (P < 0.05) reduced the carboxymethyl cellulase, filter paperase, xylanase, and β-glucosidase activities, purine content, and the efficiency of microbial protein synthesis. Flavone, myricetin, catechin, rutin, and kaempferol significantly (P < 0.05) reduced the population of rumen microbes. Total populations of protozoa and methanogens were significantly (P < 0.05) suppressed by naringin and quercetin. The results of this research demonstrated that naringin and quercetin at the concentration of 4.5% of the substrate (dry matter basis) were potential metabolites to suppress methane production without any negative effects on rumen microbial fermentation. PMID:24175289

  19. Resistivity image beneath an area of active methane seeps in the west Svalbard continental slope

    NASA Astrophysics Data System (ADS)

    Goswami, Bedanta K.; Weitemeyer, Karen A.; Minshull, Timothy A.; Sinha, Martin C.; Westbrook, Graham K.; Marín-Moreno, Héctor

    2016-11-01

    The Arctic continental margin contains large amounts of methane in the form of methane hydrates. The west Svalbard continental slope is an area where active methane seeps have been reported near the landward limit of the hydrate stability zone. The presence of bottom simulating reflectors (BSRs) on seismic reflection data in water depths greater than 600 m suggests the presence of free gas beneath gas hydrates in the area. Resistivity obtained from marine controlled source electromagnetic (CSEM) data provides a useful complement to seismic methods for detecting shallow hydrate and gas as they are more resistive than surrounding water saturated sediments. We acquired two CSEM lines in the west Svalbard continental slope, extending from the edge of the continental shelf (250 m water depth) to water depths of around 800 m. High resistivities (5-12 Ωm) observed above the BSR support the presence of gas hydrate in water depths greater than 600 m. High resistivities (3-4 Ωm) at 390-600 m water depth also suggest possible hydrate occurrence within the gas hydrate stability zone (GHSZ) of the continental slope. In addition, high resistivities (4-8 Ωm) landward of the GHSZ are coincident with high-amplitude reflectors and low velocities reported in seismic data that indicate the likely presence of free gas. Pore space saturation estimates using a connectivity equation suggest 20-50 per cent hydrate within the lower slope sediments and less than 12 per cent within the upper slope sediments. A free gas zone beneath the GHSZ (10-20 per cent gas saturation) is connected to the high free gas saturated (10-45 per cent) area at the edge of the continental shelf, where most of the seeps are observed. This evidence supports the presence of lateral free gas migration beneath the GHSZ towards the continental shelf.

  20. The active site of low-temperature methane hydroxylation in iron-containing zeolites

    NASA Astrophysics Data System (ADS)

    Snyder, Benjamin E. R.; Vanelderen, Pieter; Bols, Max L.; Hallaert, Simon D.; Böttger, Lars H.; Ungur, Liviu; Pierloot, Kristine; Schoonheydt, Robert A.; Sels, Bert F.; Solomon, Edward I.

    2016-08-01

    An efficient catalytic process for converting methane into methanol could have far-reaching economic implications. Iron-containing zeolites (microporous aluminosilicate minerals) are noteworthy in this regard, having an outstanding ability to hydroxylate methane rapidly at room temperature to form methanol. Reactivity occurs at an extra-lattice active site called α-Fe(II), which is activated by nitrous oxide to form the reactive intermediate α-O; however, despite nearly three decades of research, the nature of the active site and the factors determining its exceptional reactivity are unclear. The main difficulty is that the reactive species—α-Fe(II) and α-O—are challenging to probe spectroscopically: data from bulk techniques such as X-ray absorption spectroscopy and magnetic susceptibility are complicated by contributions from inactive ‘spectator’ iron. Here we show that a site-selective spectroscopic method regularly used in bioinorganic chemistry can overcome this problem. Magnetic circular dichroism reveals α-Fe(II) to be a mononuclear, high-spin, square planar Fe(II) site, while the reactive intermediate, α-O, is a mononuclear, high-spin Fe(IV)=O species, whose exceptional reactivity derives from a constrained coordination geometry enforced by the zeolite lattice. These findings illustrate the value of our approach to exploring active sites in heterogeneous systems. The results also suggest that using matrix constraints to activate metal sites for function—producing what is known in the context of metalloenzymes as an ‘entatic’ state—might be a useful way to tune the activity of heterogeneous catalysts.

  1. New Isotopic Constraints on the Sources of Methane at Sites of Active Continental Serpentinization

    NASA Astrophysics Data System (ADS)

    Wang, D. T.; Gruen, D.; Morrill, P. L.; Rietze, A.; Nealson, K. H.; Kubo, M. D.; Cardace, D.; Schrenk, M. O.; Hoehler, T. M.; McCollom, T. M.; Etiope, G.; Hosgormez, H.; Schoell, M.; Ono, S.

    2014-12-01

    of methane, and the flow of energy and carbon, in areas of active continental serpentinization. [1] Ono et al. (2014) Anal. Chem. 86, 6487. [2] Morrill et al. (2013) Geochim. Cosmochim. Acta 109, 222. [3] Cardace et al. (2013) Sci. Dril. 16, 45. [4] Etiope et al. (2011) Earth Planet. Sci. Lett. 310, 96.

  2. Identifying active methane-oxidizers in thawed Arctic permafrost by proteomics

    NASA Astrophysics Data System (ADS)

    Lau, C. M.; Stackhouse, B. T.; Chourey, K.; Hettich, R. L.; Vishnivetskaya, T. A.; Pfiffner, S. M.; Layton, A. C.; Mykytczuk, N. C.; Whyte, L.; Onstott, T. C.

    2012-12-01

    The rate of CH4 release from thawing permafrost in the Arctic has been regarded as one of the determining factors on future global climate. It is uncertain how indigenous microorganisms would interact with such changing environmental conditions and hence their impact on the fate of carbon compounds that are sequestered in the cryosol. Multitudinous studies of pristine surface cryosol (top 5 cm) and microcosm experiments have provided growing evidence of effective methanotrophy. Cryosol samples corresponding to active layer were sampled from a sparsely vegetated, ice-wedge polygon at the McGill Arctic Research Station at Axel Heiberg Island, Nunavut, Canada (N79°24, W90°45) before the onset of annual thaw. Pyrosequencing of 16S rRNA gene indicated the occurrence of methanotroph-containing bacterial families as minor components (~5%) in pristine cryosol including Bradyrhizobiaceae, Methylobacteriaceae and Methylocystaceae within alpha-Proteobacteria, and Methylacidiphilaceae within Verrucomicrobia. The potential of methanotrophy is supported by preliminary analysis of metagenome data, which indicated putative methane monooxygenase gene sequences relating to Bradyrhizobium sp. and Pseudonocardia sp. are present. Proteome profiling in general yielded minute traces of proteins, which likely hints at dormant nature of the soil microbial consortia. The lack of specific protein database for permafrost posted additional challenge to protein identification. Only 35 proteins could be identified in the pristine cryosol and of which 60% belonged to Shewanella sp. Most of the identified proteins are known to be involved in energy metabolism or post-translational modification of proteins. Microcosms amended with sodium acetate exhibited a net methane consumption of ~65 ngC-CH4 per gram (fresh weight) of soil over 16 days of aerobic incubation at room temperature. The pH in microcosm materials remained acidic (decreased from initial 4.7 to 4.5). Protein extraction and

  3. Active Thermochemical Tables: Sequential Bond Dissociation Enthalpies of Methane, Ethane, and Methanol and the Related Thermochemistry.

    PubMed

    Ruscic, Branko

    2015-07-16

    Active Thermochemical Tables (ATcT) thermochemistry for the sequential bond dissociations of methane, ethane, and methanol systems were obtained by analyzing and solving a very large thermochemical network (TN). Values for all possible C-H, C-C, C-O, and O-H bond dissociation enthalpies at 298.15 K (BDE298) and bond dissociation energies at 0 K (D0) are presented. The corresponding ATcT standard gas-phase enthalpies of formation of the resulting CHn, n = 4-0 species (methane, methyl, methylene, methylidyne, and carbon atom), C2Hn, n = 6-0 species (ethane, ethyl, ethylene, ethylidene, vinyl, ethylidyne, acetylene, vinylidene, ethynyl, and ethynylene), and COHn, n = 4-0 species (methanol, hydroxymethyl, methoxy, formaldehyde, hydroxymethylene, formyl, isoformyl, and carbon monoxide) are also presented. The ATcT thermochemistry of carbon dioxide, water, hydroxyl, and carbon, oxygen, and hydrogen atoms is also included, together with the sequential BDEs of CO2 and H2O. The provenances of the ATcT enthalpies of formation, which are quite distributed and involve a large number of relevant determinations, are analyzed by variance decomposition and discussed in terms of principal contributions. The underlying reasons for periodic appearances of remarkably low and/or unusually high BDEs, alternating along the dissociation sequences, are analyzed and quantitatively rationalized. The present ATcT results are the most accurate thermochemical values currently available for these species.

  4. Equilibrium isotherms of methane onto activated carbons using a static volumetric method.

    PubMed

    Kavitha, T; Kaliappan, S

    2009-07-01

    The aim of this research is to develop a technology for the storage of biogas. The present work pertains to the measurement of the adsorption capacity of methane onto activated carbons at room temperature at pressure range varying from 1 atm to 10 atm. The results were obtained with a static volumetric method. Adsorption isotherms for methane on Sorbonorit 4, Norit SX Plus, Sorbonorit B3, Norit PAC 200 XC were plotted. The equilibrium pressure data were analysed using Langmuir, Dubinin-Astakhov's (DA) and Dubinin-Radushkevich (DR) equations. The DA equation described the isotherm behavior better with the exponent n equals to 1.0 for Sorbonorit 4, Sorbonorit B3, Norit PAC 200 XC and 1.7 for Norit SX Plus than the other equations. The order of the adsorption capacity is as follows: Sorbonorit 4 (4.6 mmol/g) > Norit PAC 200 XC (3.81 mmol/g) > Sorbonorit B3 (3.52 mmol/g) > Norit SX Plus (3.51 mmol/g).

  5. Synthesis and anticancer activity of di(3-thienyl)methanol and di(3-thienyl)methane.

    PubMed

    Kaushik, Nagendra Kumar; Kim, Hong Seon; Chae, Young June; Lee, Young Nam; Kwon, Gi-Chung; Choi, Eun Ha; Kim, In Tae

    2012-09-27

    Di(3-thienyl)methanol (2) and di(3-thienyl)methane (3) have been synthesized and screened against the T98G (brain cancer) cell line. Treatment induced cell death (MTT and macro-colony assay), growth inhibition, cytogenetic damage (micronuclei formation), were studied as cellular response parameters. Treatment with the compounds enhanced growth inhibition and cell death in a concentration dependent manner in both T98G and HEK (normal) cell lines. At higher concentrations (>20 µg/mL) the cytotoxic effects of the compounds were highly significant. The effect on clonogenic capacity and micronuclei formation observed after treatment of cells. Amongst the compounds, compound 2 exhibited potent activity against T98G brain cancer cells. Despite potent in vitro activity, both compounds exhibited less cytotoxicity against normal human HEK cells at all effective concentrations.

  6. Spectroscopic and XRD characterisation of zeolite catalysts active for the oxidative methylation of benzene with methane.

    PubMed

    Adebajo, Moses O; Long, Mervyn A; Frost, Ray L

    2004-03-01

    The benzene methylation with methane over zeolite catalysts was previously shown in our laboratory to require the presence of oxygen. Thus, a two-step mechanism involving the intermediate formation of methanol by partial oxidation of methane followed by the methylation of benzene with methanol in the second step, was postulated. This paper now reports the results of the characterisation of the zeolite catalysts used for the oxidative benzene methylation reaction in order to provide some information about their composition, structure, properties and their behaviour before and after the reaction. The catalysts were characterised by X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray fluorescence (XRF), FT-IR and solid state NMR. XRD results indicate that the crystalline structures of all the ZSM-5 and H-beta catalysts remained unchanged after batch reaction of benzene with methane over the catalysts in agreement with the observation that the catalysts recovered from the reactor could be reused without loss of activity. Elemental analyses and FT-IR data show that as the level of metal ion exchange increases, the Brönsted acid concentration decreases but this metal ion exchange does not totally remove Brönsted acidity. FT-IR results further show that only a small amount of acid sites is actually necessary for a catalyst to be active since used catalysts containing highly reduced Brönsted acidity are found to be reusable without any loss of their activity. 29Si and 27Al magic angle spinning (MAS) NMR together with FT-IR spectra also show that all the active zeolites catalysts contain some extra-framework octahedral aluminium in addition to the normal tetrahedral framework aluminium. The presence of this extra-lattice aluminium does not, however, have any adverse effect on the crystallinity of the catalysts both before and after oxidative benzene methylation reaction. There appears also to be no significant dealumination

  7. Spectroscopic and XRD characterisation of zeolite catalysts active for the oxidative methylation of benzene with methane

    NASA Astrophysics Data System (ADS)

    Adebajo, Moses O.; Long, Mervyn A.; Frost, Ray L.

    2004-03-01

    The benzene methylation with methane over zeolite catalysts was previously shown in our laboratory to require the presence of oxygen. Thus, a two-step mechanism involving the intermediate formation of methanol by partial oxidation of methane followed by the methylation of benzene with methanol in the second step, was postulated. This paper now reports the results of the characterisation of the zeolite catalysts used for the oxidative benzene methylation reaction in order to provide some information about their composition, structure, properties and their behaviour before and after the reaction. The catalysts were characterised by X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray fluorescence (XRF), FT-IR and solid state NMR. XRD results indicate that the crystalline structures of all the ZSM-5 and H-beta catalysts remained unchanged after batch reaction of benzene with methane over the catalysts in agreement with the observation that the catalysts recovered from the reactor could be reused without loss of activity. Elemental analyses and FT-IR data show that as the level of metal ion exchange increases, the Brönsted acid concentration decreases but this metal ion exchange does not totally remove Brönsted acidity. FT-IR results further show that only a small amount of acid sites is actually necessary for a catalyst to be active since used catalysts containing highly reduced Brönsted acidity are found to be reusable without any loss of their activity. 29Si and 27Al magic angle spinning (MAS) NMR together with FT-IR spectra also show that all the active zeolites catalysts contain some extra-framework octahedral aluminium in addition to the normal tetrahedral framework aluminium. The presence of this extra-lattice aluminium does not, however, have any adverse effect on the crystallinity of the catalysts both before and after oxidative benzene methylation reaction. There appears also to be no significant dealumination

  8. Physical Activity in Pregnancy and Neonatal Body Composition: The Healthy Start Study

    PubMed Central

    Harrod, Curtis S; Chasan-Taber, Lisa; Reynolds, Regina M; Fingerlin, Tasha E; Glueck, Deborah H; Brinton, John T; Dabelea, Dana

    2014-01-01

    Objective To examine associations between pregnancy physical activity and neonatal fat mass and fat-free mass, birth weight and small for gestational age (SGA). Methods We analyzed 826 mother-neonate pairs (term births) participating in the longitudinal Healthy Start study. The Pregnancy Physical Activity Questionnaire was used to assess total energy expenditure and meeting American College of Obstetricians and Gynecologists (the College) guidelines for physical activity during early pregnancy, mid-pregnancy and late pregnancy. Models were adjusted for maternal and neonatal characteristics. Results Neonates had mean fat mass of 292.9 grams, fat-free mass of 2,849.8 g, and birth weight of 3,290.7 g. We observed 107 (12.9%) SGA and 30 (3.6%) large-for-gestational age (LGA) births. A significant inverse linear trend between total energy expenditure during late pregnancy and neonatal fat mass (Ptrend = 0.04) was detected. Neonates of mothers in the highest compared to lowest quartile of total energy expenditure during late pregnancy had 41.1 g less fat mass (249.4 vs. 290.5 g; P = 0.03). No significant trend was found with total energy expenditure and neonatal fat-free mass or birth weight. Early-pregnancy and mid-pregnancy total energy expenditure were not associated with neonatal outcomes. No significant trend was observed between late-pregnancy total energy expenditure and SGA (Ptrend = 0.07), but neonates of mothers in the highest compared to the lowest quartile had a 3.0 (95% CI 1.4–6.7) higher likelihood of SGA. Meeting the College’s physical activity guidelines during pregnancy was not associated with differences in neonatal outcomes. Conclusions Increasing levels of late-pregnancy total energy expenditure are associated with decreased neonatal adiposity without significantly reduced neonatal fat-free mass. PMID:25004346

  9. Start small, dream big: Experiences of physical activity in public spaces in Colombia.

    PubMed

    Díaz Del Castillo, Adriana; González, Silvia Alejandra; Ríos, Ana Paola; Páez, Diana C; Torres, Andrea; Díaz, María Paula; Pratt, Michael; Sarmiento, Olga L

    2016-08-26

    Multi-sectoral strategies to promote active recreation and physical activity in public spaces are crucial to building a "culture of health". However, studies on the sustainability and scalability of these strategies are limited. This paper identifies the factors related to the sustainability and scaling up of two community-based programs offering physical activity classes in public spaces in Colombia: Bogotá's Recreovía and Colombia's "Healthy Habits and Lifestyles Program-HEVS". Both programs have been sustained for more than 10years, and have benefited 1455 communities. We used a mixed-methods approach including semi-structured interviews, document review and an analysis of data regarding the programs' history, characteristics, funding, capacity building and challenges. Interviews were conducted between May-October 2015. Based on the sustainability frameworks of Shediac-Rizkallah and Bone and Scheirer, we developed categories to independently code each interview. All information was independently analyzed by four of the authors and cross-compared between programs. Findings showed that these programs underwent adaptation processes to address the challenges that threatened their continuation and growth. The primary strategies included flexibility/adaptability, investing in the working conditions and training of instructors, allocating public funds and requesting accountability, diversifying resources, having community support and champions at different levels and positions, and carrying out continuous advocacy to include physical activity in public policies. Recreovía and HEVS illustrate sustainability as an incremental, multi-level process at different levels. Lessons learned for similar initiatives include the importance of individual actions and small events, a willingness to start small while dreaming big, being flexible, and prioritizing the human factor.

  10. A gaseous measurement system for carbon-14 dioxide and carbon-14 methane: An analytical methodology to be applied in the evaluation of the carbon-14 dioxide and carbon-14 methane produced via microbial activity in volcanic tuff

    SciTech Connect

    Dolan, M.M.

    1987-05-06

    The objectives of this study were to develop a gaseous measurement system for the carbon-14 dioxide and carbon-14 methane produced via microbial activity or geochemical action on leachate in tuff; to determine the trapping efficiency of the system for carbon-14 dioxide; to determine the trapping efficiency of the system for carbon-14 methane; to apply the experimentally determined factors regarding the system's trapping efficiency for carbon-14 dioxide and carbon-14 methane to a trapping algorithm to determine the activity of the carbon-14 dioxide and carbon-14 methane in a mixed sample; to determine the minimum detectable activity of the measurement process in picocuries per liter; and to determine the lower limit or detection of the measurement process in counts per minute.

  11. Circadian Variability in Methane Oxidation Activity in the Root Zone of Rice Plants

    NASA Astrophysics Data System (ADS)

    Schroth, M. H.; Cho, R.; Zeyer, J.

    2009-12-01

    Methane is an important greenhouse gas with a warming potential about 20 times stronger than that of carbon dioxide. A main source of biogenic methane are rice-paddy soils. Methane is produced in flooded rice fields under anaerobic conditions. Conversely, methanotrophic microorganisms oxidize methane to carbon dioxide in the root zone of rice plants in the presence of molecular oxygen supplied to the roots through the plants’ aerenchyma, thus reducing overall methane emissions to the atmosphere. To quantify methane oxidation we adapted push-pull tests (PPTs), a technique originally developed for aquifer testing, in combination with a suitable microbial inhibitor for application in the root zone of rice plants. During a PPT, 70 ml of a test solution containing dissolved substrates (methane, oxygen), nonreactive tracers (argon, chloride) and the methanogenesis inhibitor 2-Bromoethane sulfonate was injected into the plant’s root zone, and after a rest period of two hours extracted from the same location. Reaction rate constants were calculated from extraction-phase breakthrough curves of substrates and tracers. We conducted a set of three different laboratory PPTs to quantify methane oxidation at day time, directly after dawn, and at night in the root zone of four different potted rice plants each. High diurnal methane oxidation rate constants (up to 23 h-1) were obtained for all rice plants. Methane oxidation potential decreased soon after nightfall. At night, rate constants were usually below 1 h-1. Methane oxidation rates were apparently independent of additional oxygen supplied via the injected test solutions, but strongly dependent on photosynthetically produced oxygen transported to the roots through the plants’ aerenchyma. Additional PPTs utilizing 13C-labeled methane are currently being conducted to corroborate these findings. Ultimately, this novel tool shall support efforts to quantitatively understand the controlling mechanisms of methane turnover in

  12. A new process for efficiently producing methane from waste activated sludge: alkaline pretreatment of sludge followed by treatment of fermentation liquid in an EGSB reactor.

    PubMed

    Zhang, Dong; Chen, Yinguang; Zhao, Yuxiao; Ye, Zhengxiang

    2011-01-15

    In the literature the production of methane from waste activated sludge (WAS) was usually conducted in a continuous stirred tank reactor (CSTR) after sludge was pretreated. It was reported in our previous publication that compared with other pretreatment methods the methane production in CSTR could be significantly enhanced when sludge was pretreated by NaOH at pH 10 for 8 days. In order to further improve methane production, this study reported a new process for efficiently producing methane from sludge, that is, sludge was fermented at pH 10 for 8 days, which was adjusted by Ca(OH)(2), and then the fermentation liquid was treated in an expanded granular sludge bed (EGSB) for methane generation. First, for comparing the methane production observed in this study with that reported in the literature, the conventional operational model was applied to produce methane from the pH 10 pretreated sludge, that is, directly using the pH 10 pretreated sludge to produce methane in a CSTR. It was observed that the maximal methane production was only 0.61 m(3)CH(4)/m(3)-reactor/day. Then, the use of fermentation liquid of pH 10 pretreated sludge to produce methane in the reactors of up-flow anaerobic sludge bed (UASB), anaerobic sequencing batch reactor (ASBR) and EGSB was compared. The maximal methane production in UASB, ASBR, and EGSB reached 1.41, 3.01, and 12.43 m(3)CH(4)/m(3)-reactor/day, respectively. Finally, the mechanisms for EGSB exhibiting remarkably higher methane production were investigated by enzyme, adenosine-triphosphate (ATP), scanning electron microscope (SEM) and fluorescence in situ hybridization (FISH) analyses. It was found that the granular sludge in EGSB had the highest conversion efficiency of acetic acid to methane, and the greatest activity of hydrolysis and acidification enzymes and general physiology with much more Methanosarcinaceae.

  13. Methane Activation by 5 d Transition Metals: Energetics, Mechanisms, and Periodic Trends.

    PubMed

    Armentrout, Peter B

    2017-01-01

    Although it has been known for almost three decades that several 5d transition-metal cations will activate methane at room temperature, a more detailed examination of these reactions across the periodic table has only recently been completed. In this Minireview, we compare and contrast studies of the kinetic energy dependence of these reactions as studied using guided-ion-beam tandem mass spectrometry. Thermochemistry for the various products observed (MH(+) , MH2(+) , MC(+) , MCH(+) , MCH2(+) , and MCH3(+) ) are collected and periodic trends evaluated and discussed. The mechanisms for the reactions as elucidated by synergistic quantum chemical calculations are also reviewed. Recent spectroscopic evidence for the structures of the MCH2(+) dehydrogenation products are discussed as well.

  14. Differentiating biotic from abiotic methane genesis in hydrothermally active planetary surfaces

    PubMed Central

    Oze, Christopher; Jones, L. Camille; Goldsmith, Jonas I.; Rosenbauer, Robert J.

    2012-01-01

    Molecular hydrogen (H2) is derived from the hydrothermal alteration of olivine-rich planetary crust. Abiotic and biotic processes consume H2 to produce methane (CH4); however, the extent of either process is unknown. Here, we assess the temporal dependence and limit of abiotic CH4 related to the presence and formation of mineral catalysts during olivine hydrolysis (i.e., serpentinization) at 200 °C and 0.03 gigapascal. Results indicate that the rate of CH4 production increases to a maximum value related to magnetite catalyzation. By identifying the dynamics of CH4 production, we kinetically model how the H2 to CH4 ratio may be used to assess the origin of CH4 in deep subsurface serpentinization systems on Earth and Mars. Based on our model and available field data, low H2/CH4 ratios (less than approximately 40) indicate that life is likely present and active. PMID:22679287

  15. Identifying transcription start sites and active enhancer elements using BruUV-seq.

    PubMed

    Magnuson, Brian; Veloso, Artur; Kirkconnell, Killeen S; de Andrade Lima, Leonardo Carmo; Paulsen, Michelle T; Ljungman, Emily A; Bedi, Karan; Prasad, Jayendra; Wilson, Thomas E; Ljungman, Mats

    2015-12-11

    BruUV-seq utilizes UV light to introduce transcription-blocking DNA lesions randomly in the genome prior to bromouridine-labeling and deep sequencing of nascent RNA. By inhibiting transcription elongation, but not initiation, pre-treatment with UV light leads to a redistribution of transcription reads resulting in the enhancement of nascent RNA signal towards the 5'-end of genes promoting the identification of transcription start sites (TSSs). Furthermore, transcripts associated with arrested RNA polymerases are protected from 3'-5' degradation and thus, unstable transcripts such as putative enhancer RNA (eRNA) are dramatically increased. Validation of BruUV-seq against GRO-cap that identifies capped run-on transcripts showed that most BruUV-seq peaks overlapped with GRO-cap signal over both TSSs and enhancer elements. Finally, BruUV-seq identified putative enhancer elements induced by tumor necrosis factor (TNF) treatment concomitant with expression of nearby TNF-induced genes. Taken together, BruUV-seq is a powerful new approach for identifying TSSs and active enhancer elements genome-wide in intact cells.

  16. Identifying transcription start sites and active enhancer elements using BruUV-seq

    PubMed Central

    Magnuson, Brian; Veloso, Artur; Kirkconnell, Killeen S.; Lima, Leonardo Carmo de Andrade; Paulsen, Michelle T.; Ljungman, Emily A.; Bedi, Karan; Prasad, Jayendra; Wilson, Thomas E.; Ljungman, Mats

    2015-01-01

    BruUV-seq utilizes UV light to introduce transcription-blocking DNA lesions randomly in the genome prior to bromouridine-labeling and deep sequencing of nascent RNA. By inhibiting transcription elongation, but not initiation, pre-treatment with UV light leads to a redistribution of transcription reads resulting in the enhancement of nascent RNA signal towards the 5′-end of genes promoting the identification of transcription start sites (TSSs). Furthermore, transcripts associated with arrested RNA polymerases are protected from 3′–5′ degradation and thus, unstable transcripts such as putative enhancer RNA (eRNA) are dramatically increased. Validation of BruUV-seq against GRO-cap that identifies capped run-on transcripts showed that most BruUV-seq peaks overlapped with GRO-cap signal over both TSSs and enhancer elements. Finally, BruUV-seq identified putative enhancer elements induced by tumor necrosis factor (TNF) treatment concomitant with expression of nearby TNF-induced genes. Taken together, BruUV-seq is a powerful new approach for identifying TSSs and active enhancer elements genome-wide in intact cells. PMID:26656874

  17. C-H bond activation of methane in aqueous solution: a hybrid quantum mechanical/effective fragment potential study.

    PubMed

    Da Silva, Júlio C S; Rocha, Willian R

    2011-12-01

    In this study, we investigated the C-H bond activation of methane catalyzed by the complex [PtCl(4)](2-), using the hybrid quantum mechanical/effective fragment potential (EFP) approach. We analyzed the structures, energetic properties, and reaction mechanism involved in the elementary steps that compose the catalytic cycle of the Shilov reaction. Our B3LYP/SBKJC/cc-pVDZ/EFP results show that the methane activation may proceed through two pathways: (i) electrophilic addition or (ii) direct oxidative addition of the C-H bond of the alkane. The electrophilic addition pathway proceeds in two steps with formation of a σ-methane complex, with a Gibbs free energy barrier of 24.6 kcal mol(-1), followed by the cleavage of the C-H bond, with an energy barrier of 4.3 kcal mol(-1) . The activation Gibbs free energy, calculated for the methane uptake step was 24.6 kcal mol(-1), which is in good agreement with experimental value of 23.1 kcal mol(-1) obtained for a related system. The results shows that the activation of the C-H bond promoted by the [PtCl(4)](2-) catalyst in aqueous solution occurs through a direct oxidative addition of the C-H bond, in a single step, with an activation free energy of 25.2 kcal mol(-1), as the electrophilic addition pathway leads to the formation of a σ-methane intermediate that rapidly undergoes decomposition. The inclusion of long-range solvent effects with polarizable continuum model does not change the activation energies computed at the B3LYP/SBKJC/cc-pVDZ/EFP level of theory significantly, indicating that the large EFP water cluster used, obtained from Monte Carlo simulations and analysis of the center-of-mass radial pair distribution function, captures the most important solvent effects.

  18. Improved methane production from waste activated sludge with low organic content by alkaline pretreatment at pH 10.

    PubMed

    Feng, L Y; Yang, L Q; Zhang, L X; Chen, H L; Chen, J

    2013-01-01

    Sludge with low organic content always results in an unsatisfactory performance, even failure of anaerobic digestion. The alkaline pretreatment effect on anaerobic digestion of sludge with low organic content has seldom been studied although it gives many benefits for sludge with high organic content. In this study the influence of alkaline pretreatment (pH 10, an effective alkaline pH) on the solubilization and methane production from waste activated sludge (WAS) with low organic content was investigated. Results from biochemical methane potential (BMP) experiments showed that anaerobic biodegradability of WAS was greatly improved by alkaline pretreatment at pH 10. Methane production from the current WAS under conditions of pretreatment time 4 h and digestion time 15 d was 139.6 mL/g VS (volatile solids), much higher than that from the unpretreated WAS with digestion time of 20 d (75.2 mL/g VS). Also, the solubilization of WAS was significantly accelerated by alkaline pretreatment. Mechanism exploration indicated that the general activities of anaerobic microorganisms, specific activities of key enzymes and the amounts of methanogens were enhanced by alkaline pretreatment at pH 10, showing good agreement with methane production.

  19. Alpha- and Gammaproteobacterial Methanotrophs Codominate the Active Methane-Oxidizing Communities in an Acidic Boreal Peat Bog

    PubMed Central

    Esson, Kaitlin C.; Lin, Xueju; Kumaresan, Deepak; Chanton, Jeffrey P.; Murrell, J. Colin

    2016-01-01

    The objective of this study was to characterize metabolically active, aerobic methanotrophs in an ombrotrophic peatland in the Marcell Experimental Forest, in Minnesota. Methanotrophs were investigated in the field and in laboratory incubations using DNA-stable isotope probing (SIP), expression studies on particulate methane monooxygenase (pmoA) genes, and amplicon sequencing of 16S rRNA genes. Potential rates of oxidation ranged from 14 to 17 μmol of CH4 g dry weight soil−1 day−1. Within DNA-SIP incubations, the relative abundance of methanotrophs increased from 4% in situ to 25 to 36% after 8 to 14 days. Phylogenetic analysis of the 13C-enriched DNA fractions revealed that the active methanotrophs were dominated by the genera Methylocystis (type II; Alphaproteobacteria), Methylomonas, and Methylovulum (both, type I; Gammaproteobacteria). In field samples, a transcript-to-gene ratio of 1 to 2 was observed for pmoA in surface peat layers, which attenuated rapidly with depth, indicating that the highest methane consumption was associated with a depth of 0 to 10 cm. Metagenomes and sequencing of cDNA pmoA amplicons from field samples confirmed that the dominant active methanotrophs were Methylocystis and Methylomonas. Although type II methanotrophs have long been shown to mediate methane consumption in peatlands, our results indicate that members of the genera Methylomonas and Methylovulum (type I) can significantly contribute to aerobic methane oxidation in these ecosystems. PMID:26873322

  20. Impact of different antibiotics on methane production using waste-activated sludge: mechanisms and microbial community dynamics.

    PubMed

    Mustapha, Nurul Asyifah; Sakai, Kenji; Shirai, Yoshihito; Maeda, Toshinari

    2016-11-01

    Anaerobic digestion is an effective method for reducing the by-product of waste-activated sludge (WAS) from wastewater treatment plants and for producing bioenergy from WAS. However, only a limited number of studies have attempted to improve anaerobic digestion by targeting the microbial interactions in WAS. In this study, we examined whether different antibiotics positively, negatively, or neutrally influence methane fermentation by evaluating changes in the microbial community and functions in WAS. Addition of azithromycin promoted the microbial communities related to the acidogenic and acetogenic stages, and a high concentration of soluble proteins and a high activity of methanogens were detected. Chloramphenicol inhibited methane production but did not affect the bacteria that contribute to the hydrolysis, acidogenesis, and acetogenesis digestion stages. The addition of kanamycin, which exhibits the same methane productivity as a control (antibiotic-free WAS), did not affect all of the microbial communities during anaerobic digestion. This study demonstrates the simultaneous functions and interactions of diverse bacteria and methanogenic Archaea in different stages of the anaerobic digestion of WAS. The ratio of Caldilinea, Methanosarcina, and Clostridium may correspond closely to the trend of methane production in each antibiotic. The changes in microbial activities and function by antibiotics facilitate a better understanding of bioenergy production.

  1. Alpha- and Gammaproteobacterial Methanotrophs Codominate the Active Methane-Oxidizing Communities in an Acidic Boreal Peat Bog.

    PubMed

    Esson, Kaitlin C; Lin, Xueju; Kumaresan, Deepak; Chanton, Jeffrey P; Murrell, J Colin; Kostka, Joel E

    2016-04-01

    The objective of this study was to characterize metabolically active, aerobic methanotrophs in an ombrotrophic peatland in the Marcell Experimental Forest, in Minnesota. Methanotrophs were investigated in the field and in laboratory incubations using DNA-stable isotope probing (SIP), expression studies on particulate methane monooxygenase (pmoA) genes, and amplicon sequencing of 16S rRNA genes. Potential rates of oxidation ranged from 14 to 17 μmol of CH4g dry weight soil(-1)day(-1) Within DNA-SIP incubations, the relative abundance of methanotrophs increased from 4% in situ to 25 to 36% after 8 to 14 days. Phylogenetic analysis of the(13)C-enriched DNA fractions revealed that the active methanotrophs were dominated by the genera Methylocystis(type II;Alphaproteobacteria),Methylomonas, and Methylovulum(both, type I;Gammaproteobacteria). In field samples, a transcript-to-gene ratio of 1 to 2 was observed for pmoA in surface peat layers, which attenuated rapidly with depth, indicating that the highest methane consumption was associated with a depth of 0 to 10 cm. Metagenomes and sequencing of cDNA pmoA amplicons from field samples confirmed that the dominant active methanotrophs were Methylocystis and Methylomonas Although type II methanotrophs have long been shown to mediate methane consumption in peatlands, our results indicate that members of the genera Methylomonas and Methylovulum(type I) can significantly contribute to aerobic methane oxidation in these ecosystems.

  2. Gating effects of component B on oxygen activation by the methane monooxygenase hydroxylase component.

    PubMed

    Liu, Y; Nesheim, J C; Lee, S K; Lipscomb, J D

    1995-10-20

    Component B (MMOB) of the soluble methane monooxygenase (MMO) system accelerates the initial velocity of methane oxidation by up to 150-fold by an unknown mechanism. The active site of MMO contains a diferric, hydroxo-bridged diiron cluster located on the hydroxylase component (MMOH). This cluster is reduced by the NAD(P)H-coupled reductase component to the diferrous state, which then reacts with O2 to yield two reaction cycle intermediates sequentially termed compounds P and Q. The rate of compound P formation is shown here to be independent of O2 concentration, suggesting that an MMOH-O2 complex (compound O) is (congruent to irreversibly) formed before compound P. Compound Q is capable of reacting with hydrocarbons to yield the MMOH-product complex, compound T. It is shown here that MMOB accelerates catalysis by increasing congruent to 1000-fold the rate of O2 association and reaction with diferrous MMOH leading to compound P. Modeling of the single turnover reaction in the presence of substoichiometric MMOB suggests that MMOB also accelerates the compound P to Q conversion by congruent to 40-fold. Due to this O2-gating effect of MMOB, either compound Q or T becomes the dominant species during turnover, depending upon the substrate concentration and type. Because these are the species that either react with substrate (Q) or release product (T), their buildup maximizes the turnover rate. This is the first direct role in catalysis to be recognized for MMOB and represents a novel method for oxygenase regulation.

  3. Highly active Ni/Y-doped ZrO2 catalysts for CO2 methanation

    NASA Astrophysics Data System (ADS)

    Takano, H.; Kirihata, Y.; Izumiya, K.; Kumagai, N.; Habazaki, H.; Hashimoto, K.

    2016-12-01

    The catalytic methanation of CO2 was carried out on Ni catalysts supported on Y-doped ZrO2 with various Y3+ concentrations and Ni/(Zr + Y) molar ratio = 1. The catalysts were characterized by X-ray diffraction, scanning transmission electron microscopy, specific surface area, temperature-programmed desorption of CO2, and temperature-programmed reaction. In addition, operando diffuse-reflectance infrared Fourier-transform spectroscopy (DRIFT) was used to identify the adsorbed reaction intermediate. Catalysts supported on Y-doped ZrO2 show higher catalytic activity than the catalyst on Y-free ZrO2 with a monoclinic ZrO2 phase. The catalytic activity is also dependent upon the Y3+ concentration, and the highest activity was obtained for the catalyst with a Y/(Zr + Y) molar ratio of 0.333, which consists mainly of fcc Ni and cubic ZrO2 phase. Y3+ doping into ZrO2 introduces oxygen vacancies, which play an important role in enhancing the catalytic activity. The operando DRIFT study reveals that a CO adsorption intermediate is absent, and bidentate carbonate is an important intermediate for CH4 formation.

  4. Activation of methane and ethane and their selective oxidation to the alcohols in protic media

    SciTech Connect

    Sen, A.; Benvenuto, M.A.; Lin, M.; Hutson, A.C.; Basickes, N. )

    1994-02-09

    The selective oxidation of methane and ethane to the alcohols in solvents ranging from strong acids to neutral aqueous medium has been studied. In 98% sulfuric acid, methane is oxidized to CH[sub 3]OSO[sub 3]H by a variety of 1e[sup [minus

  5. Methane emission from sewers.

    PubMed

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

    2015-08-15

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

  6. Activity, distribution, and abundance of methane-oxidizing bacteria in the near surface soils of onshore oil and gas fields.

    PubMed

    Xu, Kewei; Tang, Yuping; Ren, Chun; Zhao, Kebin; Wang, Wanmeng; Sun, Yongge

    2013-09-01

    Methane-oxidizing bacteria (MOB) have long been used as an important biological indicator for oil and gas prospecting, but the ecological characteristics of MOB in hydrocarbon microseep systems are still poorly understood. In this study, the activity, distribution, and abundance of aerobic methanotrophic communities in the surface soils underlying an oil and gas field were investigated using biogeochemical and molecular ecological techniques. Measurements of potential methane oxidation rates and pmoA gene copy numbers showed that soils inside an oil and gas field are hot spots of methane oxidation and MOB abundance. Correspondingly, terminal restriction fragment length polymorphism analyses in combination with cloning and sequencing of pmoA genes also revealed considerable differences in the methanotrophic community composition between oil and gas fields and the surrounding soils. Principal component analysis ordination furthermore indicated a coincidence between elevated CH4 oxidation activity and the methanotrophic community structure with type I methanotrophic Methylococcus and Methylobacter, in particular, as indicator species of oil and gas fields. Collectively, our results show that trace methane migrated from oil and gas reservoirs can considerably influence not only the quantity but also the structure of the methanotrophic community.

  7. Nanoporous and highly active silicon carbide supported CeO₂-catalysts for the methane oxidation reaction.

    PubMed

    Hoffmann, Claudia; Biemelt, Tim; Lohe, Martin R; Rümmeli, Mark H; Kaskel, Stefan

    2014-01-29

    CeOx @SiO2 nanoparticles are used for the first time for the generation of porous SiC materials with tailored pore diameter in the mesopore range containing encapsulated and catalytically active CeO2 nanoparticles. The nanocasting approach with a preceramic polymer and subsequent pyrolysis is performed at 1300 °C, selective leaching of the siliceous part results in CeOx /SiC catalysts with remarkable characteristics like monodisperse, spherical pores and specific surface areas of up to 438 m(2) ·g(-1) . Porous SiC materials are promising supports for high temperature applications. The catalysts show excellent activities in the oxidation of methane with onset temperatures of the reaction 270 K below the onset of the homogeneous reaction. The synthesis scheme using core-shell particles is suited to functionalize silicon carbide with a high degree of stabilization of the active nanoparticles against sintering in the core of the template even at pyrolysis temperatures of 1300 °C rendering the novel synthesis principle as an attractive approach for a wide range of catalytic reactions.

  8. Stability and activity of molybdenum carbide catalysts for the oxidative reforming of methane

    NASA Astrophysics Data System (ADS)

    Lamont, David Charles

    Molybdenum carbide catalysts have been studied for oxidative reforming, in particular, the effect on reforming activity of the method by which they were synthesized, their stability under conditions of varying mass transfer, and the measurement of their inherent reaction kinetics. These catalysts show promise as possible alternatives to both conventional supported nickel catalysts, as well as to the rare and expensive noble metal catalysts. Samples of Mo 2C were synthesized in house and compared to a commercial sample of Mo2C for the CO2 (dry) reforming of methane. It was found that high surface areas, previously thought to be important for activity, were not a property of the Mo2C, but instead were attributable to large amounts of excess carbon. This carbon had a detrimental effect on catalyst stability under dry reforming conditions, because it enhanced deposition of refractory carbon via methane cracking. The commercial sample of Mo 2C, while of low surface area and containing no excess carbon, behaved more stably over time. In another investigation, Mo2C was studied for its stability under varying mass transfer conditions, because of evidence showing that the Mo2C can undergo redox chemistry at reforming conditions. Under dry reforming conditions, it was found that some feed mixtures are net oxidizing, but that oxidation in the presence of such feed mixtures could be prevented by operating under mass transfer limited conditions, which resulted in sufficiently high partial pressures of CO and H2 in the catalyst boundary layer. Similar stability was achieved by co-feeding CO to the catalyst bed, which allowed for stable operation under conditions that were not mass transfer limited. Using this approach, measurements of the intrinsic reaction kinetics of Mo2C for dry reforming were successfully achieved. These results pointed to a strong dependence of dry reforming rate on both CH4 and CO2 partial pressures, as well as evidence for a reaction mechanism unique from

  9. Fusion activity of African henipavirus F proteins with a naturally occurring start codon directly upstream of the signal peptide.

    PubMed

    Weis, Michael; Behner, Laura; Binger, Tabea; Drexler, Jan Felix; Drosten, Christian; Maisner, Andrea

    2015-04-02

    Compared to the fusion proteins of pathogenic Nipah and Hendra viruses, the F protein of prototype African henipavirus GH-M74a displays a drastically reduced surface expression and fusion activity. A probable reason for limited F expression is the unusually long sequence located between the gene start and the signal peptide (SP) not present in other henipaviruses. Such a long pre-SP extension can prevent efficient ER translocation or protein maturation and processing. As its truncation can therefore enhance surface expression, the recent identification of a second in-frame start codon directly upstream of the SP in another African henipavirus F gene (GH-UP28) raised the question if such a naturally occurring minor sequence variation can lead to the synthesis of a pre-SP truncated translation product, thereby increasing the production of mature F proteins. To test this, we analyzed surface expression and biological activity of F genes carrying the second SP-proximal start codon of GH-UP28. Though we observed minor differences in the expression levels, introduction of the additional start codon did not result in an increased fusion activity, even if combined with further mutations in the pre-SP region. Thus, limited bioactivity of African henipavirus F protein is maintained even after sequence changes that alter the gene start allowing the production of F proteins without an unusually long pre-SP.

  10. How Does Poly(hydroxyalkanoate) Affect Methane Production from the Anaerobic Digestion of Waste-Activated Sludge?

    PubMed

    Wang, Dongbo; Zhao, Jianwei; Zeng, Guangming; Chen, Yinguang; Bond, Philip L; Li, Xiaoming

    2015-10-20

    Recent studies demonstrate that, besides being used for production of biodegradable plastics, poly(hydroxyalkanoate) (PHA) that is accumulated in heterotrophic microorganisms during wastewater treatment has another novel application direction, i.e., being utilized for enhancing methane yield during the anaerobic digestion of waste-activated sludge (WAS). To date, however, the underlying mechanism of how PHA affects methane production remains largely unknown, and this limits optimization and application of the strategy. This study therefore aims to fill this knowledge gap. Experimental results showed that with the increase of sludge PHA levels from 21 to 184 mg/g of volatile suspended solids (VSS) the methane yield linearly increased from 168.0 to 246.1 mL/g of VSS (R(2) = 0.9834). Compared with protein and carbohydrate (the main components of a cell), PHA exhibited a higher biochemical methane potential on a unit VSS basis. It was also found that the increased PHA not only enhanced cell disruption of PHA cells but also benefited the soluble protein conversion of both PHA- and non-PHA cells. Moreover, the reactor fed with higher PHA sludge showed greater sludge hydrolysis and acidification than those fed with the lower PHA sludges. Further investigations using fluorescence in situ hybridization and enzyme analysis revealed that the increased PHA enhanced the abundance of methanogenic Archaea and increased the activities of protease, acetate kinase, and coenzyme F420, which were consistent with the observed methane yield. This work provides insights into PHA-involved WAS digestion systems and may have important implications for future operation of wastewater treatment plants.

  11. Characterization of methane production and microbial community shifts during waste activated sludge degradation in microbial electrolysis cells.

    PubMed

    Sun, Rui; Zhou, Aijuan; Jia, Jianna; Liang, Qing; Liu, Qian; Xing, Defeng; Ren, Nanqi

    2015-01-01

    Microbial electrolysis cell (MECs) were investigated as a promising technology to manage waste activated sludge (WAS) reduction and bio-methane generation. The effect of WAS concentration on the MECs performance was discussed. At the optimal concentration of 15gCOD/L, maximum methane yield of MECs fed with alkaline pretreated WAS (A-WAS) were achieved with the value of 77.13±2.52LCH4/kg-COD on Day 3, which had been improved by 1.5-fold compared with MECs fed with raw WAS (R-WAS), while that was negligible in open circuit controls. Efficient sludge reduction was also obtained in terms of TCOD, total protein, TSS and VSS removal. Pyrosequencing revealed the dominance of exoelectrogen Geobacter and hydrogen-producing bacteria Petrimonas in MECs fed with WAS. Methanocorpusculum with the capacity of methane generation using CO2 and H2 also showed overwhelming dominance (96.01%). The large proportions of Petrimonas and Methanocorpusculum indicated the occurrence of hydrogenotrophic methanogenesis in our methane-producing MECs.

  12. Effects of granular activated carbon on methane removal performance and methanotrophic community of a lab-scale bioreactor.

    PubMed

    Lee, Eun-Hee; Choi, Sun-Ah; Yi, Taewoo; Kim, Tae Gwan; Lee, Sang-Don; Cho, Kyung-Suk

    2015-01-01

    Two identical lab-scale bioreactor systems were operated to examine the effects of granular activated carbon (GAC) on methane removal performance and methanotrophic community. Both bioreactor systems removed methane completely at a CH4 loading rate of 71.2 g-CH4·d(-1) for 17 days. However, the methane removal efficiency declined to 88% in the bioreactor without GAC, while the bioreactor amended with GAC showed greater methane removal efficiency of 97% at a CH4 loading rate of 107.5 g-CH4·d(-1). Although quantitative real-time PCR showed that methanotrophic populations were similar levels of 5-10 × 10(8) pmoA gene copy number·VSS(-1) in both systems, GAC addition changed the methanotrophic community composition of the bioreactor systems. Microarray assay revealed that GAC enhanced the type I methanotrophic genera including Methylobacter, Methylomicrobium, and Methylomonas of the system, which suggests that GAC probably provided a favorable environment for type I methanotrophs. These results indicated that GAC is a promising support material in bioreactor systems for CH4 mitigation.

  13. Read Alouds and Beyond: The Effects of Read Aloud Extension Activities on Vocabulary in Head Start Classrooms

    ERIC Educational Resources Information Center

    Silverman, Rebecca; Crandell, Jennifer DiBara; Carlis, Lydia

    2013-01-01

    A study was conducted in 26 Head Start classrooms with 264 children to compare the effect of a read aloud plus extension activities intervention over a control group to the effect of a read aloud only intervention over a control group on preschool children's vocabulary. Children were assessed before and after the intervention on target vocabulary…

  14. Life Science Start-up Activities at the Universities of Applied Sciences (UAS).

    PubMed

    Huber, Gerda

    2014-12-01

    The universities of applied sciences (UAS) provide several values for the society and economy of a country. Besides education of high level professionals, transfer of knowledge from research to applications in industry or as new start-up companies is an important task. This is done in different ways in the various disciplines. In Life Sciences, a key industry branch in Switzerland, innovation is a competitive success factor and research findings from UAS/Life Sciences contribute to the valorization of new technologies to products, services and to business performance. In order to foster awareness for the innovation need of industry, UAS install processes and support for transfer of research and technology results to marketable applications. Furthermore they may facilitate contacts of researchers and students with entrepreneurs in order to animate start-up founding as a true alternative to being employed. Access to coaching and entrepreneurial training completes the essential basis.

  15. Enhancing methane production from waste activated sludge using combined free nitrous acid and heat pre-treatment.

    PubMed

    Wang, Qilin; Jiang, Guangming; Ye, Liu; Yuan, Zhiguo

    2014-10-15

    Methane production from anaerobic digestion of waste activated sludge (WAS) is often limited by the slow degradation and poor substrate availability of WAS. Our previous study revealed that WAS pre-treatment using free nitrous acid (FNA, i.e. HNO2) is an economically feasible and environmentally friendly method for promoting methane production. In order to further improve methane production from WAS, this study presents a novel strategy based on combined FNA and heat pre-treatment. WAS from a full-scale plant was treated for 24 h with FNA alone (0.52-1.43 mg N/L at 25 °C), heat alone (35, 55 and 70 °C), and FNA (0.52-1.11 mg N/L) combined with heat (35, 55 and 70 °C). The pre-treated WAS was then used for biochemical methane potential tests. Compared to the control (no FNA or heat pre-treatment of WAS), biochemical methane potential of the pre-treated WAS was increased by 12-16%, 0-6%, 17-26%, respectively; hydrolysis rate was improved by 15-25%, 10-25%, 20-25%, respectively, for the three types of pre-treatment. Heat pre-treatment at 55 and 70 °C, independent of the presence or absence of FNA, achieved approximately 4.5 log inactivation of pathogens (in comparison to ∼1 log inactivation with FNA treatment alone), thus capable of producing Class A biosolids. The combined FNA and heat pre-treatment is an economically and environmentally attractive technology for the pre-treatment of WAS prior to anaerobic digestion, particularly considering that both FNA and heat can be produced as by-products of anaerobic sludge digestion.

  16. Observations of Seafloor Deformation and Methane Venting within an Active Fault Zone Offshore Southern California

    NASA Astrophysics Data System (ADS)

    Anderson, K.; Lundsten, E. M.; Paull, C. K.; Caress, D. W.; Thomas, H. J.; Brewer, P. G.; Vrijenhoek, R.; Lundsten, L.

    2013-12-01

    Detailed mapping surveys of the floor and flanks of the Santa Monica Basin, San Pedro Basin, and San Diego Trough were conducted during the past seven years using an Autonomous Underwater Vehicle (AUV) built and operated by MBARI specifically for seafloor mapping. The AUV collected data provide up to 1 m resolution multibeam bathymetric grids with a vertical precision of 0.15 m. Along with high-resolution multibeam, the AUV also collects chirp seismic reflection profiles. Structures within the uppermost 10-20 m of the seafloor, which in the surveys presented here is composed of recent sediment drape, can typically be resolved in the sub-bottom reflectors. Remotely operated vehicle (ROV) dives allowed for ground-truth observations and sampling within the surveyed areas. The objectives of these dives included finding evidence of recent seafloor deformation and locating areas where chemosynthetic biological communities are supported by fluid venting. Distinctive seafloor features within an active fault zone are revealed in unprecedented detail in the AUV generated maps and seismic reflection profiles. Evidence for recent fault displacements include linear scarps which can be as small as 20 cm high but traceable for several km, right lateral offsets within submarine channels and topographic ridges, and abrupt discontinuities in sub-bottom reflectors, which in places appear to displace seafloor sediments. Several topographic highs that occur within the fault zone appear to be anticlines related to step-overs in these faults. These topographic highs are, in places, topped with circular mounds that are up to 15 m high and have ~30° sloping sides. The crests of the topographic highs and the mounds both have distinctive rough morphologies produced by broken pavements of irregular blocks of methane-derived authigenic carbonates, and by topographic depressions, commonly more than 2 m deep. These areas of distinctive rough topography are commonly associated with living

  17. Low-temperature conversion of methane to methanol on CeOx/Cu2O catalysts: Water controlled activation of the C–H Bond

    DOE PAGES

    Zuo, Zhijun; Ramírez, Pedro J.; Senanayake, Sanjaya D.; ...

    2016-10-10

    Here, an inverse CeO2/Cu2O/Cu(111) catalyst is able to activate methane at room temperature producing C, CHx fragments and COx species on the oxide surface. The addition of water to the system leads to a drastic change in the selectivity of methane activation yielding only adsorbed CHx fragments. At a temperature of 450 K, in the presence of water, a CH4 → CH3OH catalytic transformation occurs with a high selectivity. OH groups formed by the dissociation of water saturate the catalyst surface, removing sites that could decompose CHx fragments, and generating centers on which methane can directly interact to yield methanol.

  18. The Saccharomyces cerevisiae start mutant carrying the cdc25 mutation is defective in activation of plasma membrane ATPase by glucose.

    PubMed Central

    Portillo, F; Mazón, M J

    1986-01-01

    Activation of plasma membrane ATPase by the addition of glucose was examined in several cell division cycle mutants of Saccharomyces cerevisiae. The start mutant carrying the cdc25 mutation was shown to be defective in ATPase activation at the restrictive temperature. Genetic analysis showed that lack of growth and defective activation of ATPase at the restrictive temperature were caused by the same mutation. It was also found that CDC25 does not map at the same locus as the structural gene of plasma membrane ATPase (PMA1). We conclude that the product of CDC25 controls the activation of ATPase. PMID:2877973

  19. Pretreatment of lignocellulosic biomass by cattle rumen fluid for methane production: Bacterial flora and enzyme activity analysis.

    PubMed

    Baba, Yasunori; Matsuki, Yu; Mori, Yumi; Suyama, Yoshihisa; Tada, Chika; Fukuda, Yasuhiro; Saito, Masanori; Nakai, Yutaka

    2017-01-29

    We attempted to develop a pretreatment method for methane fermentation of lignocellulosic biomass using cattle rumen fluid, treated as slaughterhouse waste. When rapeseed (Brassica napus L.) was added to the methane fermentation after being solubilized with rumen fluid, 1.5 times more methane was produced compared with untreated rapeseed. Analysis of the bacterial flora during rumen fluid treatment using the MiSeq next-generation sequencer showed that the predominant phylum shifted from Bacteroidetes, composed of amylolytic Prevotella spp., to Firmicutes, composed of cellulolytic and xylanolytic Ruminococcus spp., in only 6 h. In total, 7 cellulolytic, 25 cello-oligosaccharolytic, and 11 xylanolytic bacteria were detected after investigating the most abundant sequences of detected taxa. The relative abundance of two Ruminococcus species (Ruminococcus albus and R. flavefaciens), known as cellulolytic, cello-oligosaccharolytic, and xylanolytic bacteria, increased with increasing cellulose and hemicellulose degradation rates, and, finally, comprised 48% of all operational taxonomic units. The chronological observation of enzyme activities showed that cellulolytic and xylanolytic activities increased 6 h later, and that oligosaccharolytic activity increased 24 h later. This study detected six bacteria that participate in the degradation of aromatics derived from lignin, which have rarely been reported in rumen fluid. The constitution of the detected bacteria suggests that the aromatics were converted into acetate via benzoate. The list of microbes that cover all lignocellulose-degrading candidates will provide fundamental knowledge for future studies focusing on rumen microbes.

  20. Investigating Microbial Activity in Diazotrophic Methane Seep Sediment via Transcript Analysis and Single-Cell FISH-NanoSIMS

    NASA Astrophysics Data System (ADS)

    Dekas, A. E.; Connon, S. A.; Chadwick, G.; Orphan, V. J.

    2012-12-01

    Methane seep microbial ecosystems are phylogenetically diverse and physiologically complex, and require culture-independent techniques to accurately investigate metabolic activity. In the present study we combine an RNA analysis of four key microbial genes with FISH-NanoSIMS analysis of single cells to determine the diversity of nitrogen fixing microorganisms (diazotrophs) present at a deep-sea methane-seeping site, as well as investigate the methane-dependency of a variety of community members. Recently, methane-dependent nitrogen fixation was observed in Mound 12 Costa Rica sediments, and was spatially correlated with the abundance of aggregates of anaerobic methanotrophic archaea (ANME) and sulfate reducing bacterial symbionts (SRB). Combined with the detection of 15N uptake from 15N2 in these aggregates, this suggested that the ANME-SRB aggregates are the primary diazotrophs in seep sediment. However, the diversity of dinitrogenase reductase (nifH) sequences recovered from several deep-sea locales, including Mound 12, suggests a greater diversity of diazotrophs in marine sediment. To investigate the activity of these potential diazotrophs in Mound 12 sediment, we investigated a suite of RNA transcripts in 15N2 incubations in both the presence and absence of methane: nifH, bacterial 16S rRNA, methyl coenzyme M reductase A (mcrA), and adenosine-5'-phosposulfate reductase alpha subunit (aprA). No nifH transcripts were recovered in incubations without methane, consistent with previous measurements lacking 15N2 uptake in the same sediments. The activity of the bacterial community in general, assessed by variable transcription, was also greatly affected by the presence or absence of methane. Single-cell fluorescence in situ hybridization coupled to nanoscale secondary ion mass spectrometry (FISH-NanoSIMS) was employed to confirm diazotrophic activity (15N2 uptake) and protein synthesis (15NH4+ uptake) of particular species implicated as ecologically important by the

  1. Stable isotopes as tracers of methane dynamics in Everglades marshes with and without active populations of methane oxidizing bacteria

    NASA Technical Reports Server (NTRS)

    Happell, James D.; Chanton, Jeffrey P.; Whiting, Gary J.; Showers, William J.

    1993-01-01

    The stable carbon isotopic composition of CH4 is used to study the processes that affect it during transport through plants from sediment to the atmosphere. The enhancement of CH4 flux from Cladium and Eleocharis over the flux from open water or clipped sites indicated that these plants served as gas conduits between the sediments and the atmosphere. Lowering of the water table below the sediment surface caused an Everglades sawgrass marsh to shift from emission of CH4 to consumption of atmospheric CH4. Cladium transported gases passively mainly via molecular diffusion and/or effusion instead of actively via bulk flow. Stable isotropic data gave no evidence that CH4 oxidation was occurring in the rhizosphere of Cladium. Both CH4 stable carbon isotope and flux data indicated a lack of CH4 oxidation at the sediment-water interface in Everglades marl soils and its presence in peat soils where 40 to 92 percent of the flux across the sediment-water interface was oxidized.

  2. Catalytic combustion of methane over alumina-supported palladium: Relationships between the oxidation state, particle size, morphology and activity

    NASA Astrophysics Data System (ADS)

    Lyubovsky, Maxim R.

    Supported palladium was studied as a catalyst for combustion of natural gas. The influence of variations in temperature and oxygen concentration, of addition of CO and water and of in situ hydrogen reduction on catalyst activity was studied experimentally. The activation energy for methane oxidation over crystalline PdO is about 17.5 kcal/mole and over metallic Pd - 40--45 kcal/mole. The difference in the activation energy is compensated by the preexponential coefficient that is 5--6 orders of magnitude higher for Pd than for PdO. In this work the activity variations under the different reaction conditions were correlated with the corresponding changes in the catalyst oxidation state, particle size and morphology. Formation of metallic hexagonal crystallites 100--200 nm in size was observed by TEM after PdO reduction, which resulted in an increase in the catalyst activity. Redispersion of these metallic crystallites into PdO clusters of 3--5 nm in size occurred during the Pd reoxidation, which resulted in a reversible increase of the catalyst activity on the cooling cycle, known as "negative activation." Activation of the methane molecule is the limiting step of the reaction over both the Pd and the PdO states. We propose that on the Pd surface the reaction occurs through the Langmuir-Hinshelwood mechanism. Under conditions of catalytic combustion the surface is completely covered with oxygen and competitive dissociative adsorption of methane is the limiting step of the process. The high heat of oxygen adsorption explains the high activation energy for the overall process. On the PdO surface the reaction occurs through a redox mechanism. A methane molecule interacts with a surface Pd-O dimer resulting in adsorbed CH3 and OH species. The activation energy of this interaction is about 15 kcal/mole and the probability is low due to the different multiplicity of the initial and final states of the transition complex. Oscillations in the reaction rate under fuel

  3. Effects of Metal Nanoparticles on Methane Production from Waste-Activated Sludge and Microorganism Community Shift in Anaerobic Granular Sludge.

    PubMed

    Wang, Tao; Zhang, Dong; Dai, Lingling; Chen, Yinguang; Dai, Xiaohu

    2016-05-11

    Extensive use of nanoparticles (NPs) in consumer and industrial products has led to concerns about their potential environmental impacts; however, the influences of different NPs (e.g., nZVI (nano zero-valent iron), Ag NPs, Fe2O3 NPs and MgO NPs) on the anaerobic digestion of sludge have not yet been studied in depth. Additionally, a new guideline or the use of different NPs in the anaerobic digestion of sludge should be established to improve the anaerobic digestion of sludge and avoid inhibitory effects. This study investigated the effects of four representative NPs (i.e., nZVI, Ag NPs, Fe2O3 NPs and MgO NPs) on methane production during the anaerobic digestion of waste activated sludge (WAS). The presence of 10 mg/g total suspended solids (TSS) nZVI and 100 mg/g TSS Fe2O3 NPs increased methane production to 120% and 117% of the control, respectively, whereas 500 mg/g TSS Ag NPs and 500 mg/g TSS MgO NPs generated lower levels of methane production (73.52% and 1.08% that of the control, respectively). These results showed that low concentrations of nZVI and Fe2O3 NPs promoted the amount of microbes (Bacteria and Archaea) and activities of key enzymes but that higher concentrations of Ag NPs and MgO NPs inhibited them.

  4. Effects of Metal Nanoparticles on Methane Production from Waste-Activated Sludge and Microorganism Community Shift in Anaerobic Granular Sludge

    PubMed Central

    Wang, Tao; Zhang, Dong; Dai, Lingling; Chen, Yinguang; Dai, Xiaohu

    2016-01-01

    Extensive use of nanoparticles (NPs) in consumer and industrial products has led to concerns about their potential environmental impacts; however, the influences of different NPs (e.g., nZVI (nano zero-valent iron), Ag NPs, Fe2O3 NPs and MgO NPs) on the anaerobic digestion of sludge have not yet been studied in depth. Additionally, a new guideline or the use of different NPs in the anaerobic digestion of sludge should be established to improve the anaerobic digestion of sludge and avoid inhibitory effects. This study investigated the effects of four representative NPs (i.e., nZVI, Ag NPs, Fe2O3 NPs and MgO NPs) on methane production during the anaerobic digestion of waste activated sludge (WAS). The presence of 10 mg/g total suspended solids (TSS) nZVI and 100 mg/g TSS Fe2O3 NPs increased methane production to 120% and 117% of the control, respectively, whereas 500 mg/g TSS Ag NPs and 500 mg/g TSS MgO NPs generated lower levels of methane production (73.52% and 1.08% that of the control, respectively). These results showed that low concentrations of nZVI and Fe2O3 NPs promoted the amount of microbes (Bacteria and Archaea) and activities of key enzymes but that higher concentrations of Ag NPs and MgO NPs inhibited them. PMID:27166174

  5. Effects of Metal Nanoparticles on Methane Production from Waste-Activated Sludge and Microorganism Community Shift in Anaerobic Granular Sludge

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Zhang, Dong; Dai, Lingling; Chen, Yinguang; Dai, Xiaohu

    2016-05-01

    Extensive use of nanoparticles (NPs) in consumer and industrial products has led to concerns about their potential environmental impacts; however, the influences of different NPs (e.g., nZVI (nano zero-valent iron), Ag NPs, Fe2O3 NPs and MgO NPs) on the anaerobic digestion of sludge have not yet been studied in depth. Additionally, a new guideline or the use of different NPs in the anaerobic digestion of sludge should be established to improve the anaerobic digestion of sludge and avoid inhibitory effects. This study investigated the effects of four representative NPs (i.e., nZVI, Ag NPs, Fe2O3 NPs and MgO NPs) on methane production during the anaerobic digestion of waste activated sludge (WAS). The presence of 10 mg/g total suspended solids (TSS) nZVI and 100 mg/g TSS Fe2O3 NPs increased methane production to 120% and 117% of the control, respectively, whereas 500 mg/g TSS Ag NPs and 500 mg/g TSS MgO NPs generated lower levels of methane production (73.52% and 1.08% that of the control, respectively). These results showed that low concentrations of nZVI and Fe2O3 NPs promoted the amount of microbes (Bacteria and Archaea) and activities of key enzymes but that higher concentrations of Ag NPs and MgO NPs inhibited them.

  6. Spin-Selective Thermal Activation of Methane by Closed-Shell [TaO3 ](.).

    PubMed

    Zhou, Shaodong; Li, Jilai; Schlangen, Maria; Schwarz, Helmut

    2016-06-13

    Thermal reactions of the closed-shell metal-oxide cluster [TaO3 ](+) with methane were investigated by using FTICR mass spectrometry complemented by high-level quantum chemical calculations. While the generation of methanol and formaldehyde is somewhat expected, [TaO3 ](+) remarkably also has the ability to abstract two hydrogen atoms from methane with the elimination of CH2 . Mechanistically, the generation of CH2 O and CH3 OH occurs on the singlet-ground-state surface, while for the liberation of (3) CH2 , a two-state reactivity scenario prevails.

  7. Effect of palladium on the reducibility of Mn based materials: correlation with methane oxidation activity.

    PubMed

    Baylet, A; Royer, S; Labrugère, C; Valencia, H; Marécot, P; Tatibouët, J M; Duprez, D

    2008-10-21

    Mn-based oxide supports were synthesized using different procedures: (i) carbonate co-precipitation method, leading to the formation of a hexaaluminate crystallized solid (La(0.2)Sr(0.3)Ba(0.5)MnAl(11)O(19)) and (ii) solid-solid diffusion method, leading to the formation of a doped theta-Al(2)O(3) crystallized solid (nominal composition: 60 wt% La(0.2)Sr(0.3)Ba(0.5)MnAl(11)O(19) + 40 wt% Al(2)O(3)). Impregnation of 1.0 wt%Pd was carried out on both oxides. The solids were tested for the catalytic methane combustion up to 700 degrees C. It was observed that adding palladium resulted in an important increase in the catalytic activity. The combined use of H(2)-TPR and XPS techniques reveals that only Mn(3+)/Mn(2+) redox "couple" is present in the solids, whatever the synthesis procedure used. The fraction Mn(3+)/Mn is proportional to the total Mn content in the solid support, whatever the sample structure (hexaaluminate or doped theta-Al(2)O(3)) and its morphology (large crystals or aggregates of small particles, respectively). Pd impregnation and further calcination at 650 degrees C has no significant effect on the Mn(3+)/Mn fraction. However, some changes in Mn(3+) reduction profile are observed, depending on the solid structure. Indeed, palladium addition strongly affects the manganese reducibility with an important shift of the reduction process to lower temperatures (approximately 100 degrees C). On the basis of redox properties observed for the different catalysts, a Mars-van-Krevelen redox mechanism, with oxygen transfer from support oxides to palladium particles, is proposed to explain the difference in terms of catalytic conversion and stability with respect to a 1.0 wt%Pd/Al(2)O(3) reference sample.

  8. Stratified Microbial Structure and Activity in Sulfide- and Methane-Producing Anaerobic Sewer Biofilms

    PubMed Central

    Sun, Jing; Hu, Shihu; Sharma, Keshab Raj; Ni, Bing-Jie

    2014-01-01

    Simultaneous production of sulfide and methane by anaerobic sewer biofilms has recently been observed, suggesting that sulfate-reducing bacteria (SRB) and methanogenic archaea (MA), microorganisms known to compete for the same substrates, can coexist in this environment. This study investigated the community structures and activities of SRB and MA in anaerobic sewer biofilms (average thickness of 800 μm) using a combination of microelectrode measurements, molecular techniques, and mathematical modeling. It was seen that sulfide was mainly produced in the outer layer of the biofilm, between the depths of 0 and 300 μm, which is in good agreement with the distribution of SRB population as revealed by cryosection-fluorescence in situ hybridization (FISH). SRB had a higher relative abundance of 20% on the surface layer, which decreased gradually to below 3% at a depth of 400 μm. In contrast, MA mainly inhabited the inner layer of the biofilm. Their relative abundances increased from 10% to 75% at depths of 200 μm and 700 μm, respectively, from the biofilm surface layer. High-throughput pyrosequencing of 16S rRNA amplicons showed that SRB in the biofilm were mainly affiliated with five genera, Desulfobulbus, Desulfomicrobium, Desulfovibrio, Desulfatiferula, and Desulforegula, while about 90% of the MA population belonged to the genus Methanosaeta. The spatial organizations of SRB and MA revealed by pyrosequencing were consistent with the FISH results. A biofilm model was constructed to simulate the SRB and MA distributions in the anaerobic sewer biofilm. The good fit between model predictions and the experimental data indicate that the coexistence and spatial structure of SRB and MA in the biofilm resulted from the microbial types and their metabolic transformations and interactions with substrates. PMID:25192994

  9. Getting Youth Started Tracking and Stalking: Sample Activities for Ages 6 to 17.

    ERIC Educational Resources Information Center

    Rain, Dan

    2002-01-01

    Presents activities on tracking and stalking wildlife that can be incorporated into the elementary secondary education curriculum. Includes activities such as Tracking and Questioning, Trail Detectives, Magic Tracking Stick, Trailing, Cast Collecting, Animal Forms Relay, Firekeeper, Bat and Moth, Grazing Deer, and Sneaking. (YDS)

  10. Methane enhancement through oxidative cleavage and alkali solubilization pre-treatments for corn stover with anaerobic activated sludge.

    PubMed

    Hassan, Muhammad; Ding, Weimin; Bi, Jinhua; Mehryar, Esmaeil; Talha, Zahir Ahmed Ali; Huang, Hongying

    2016-01-01

    In the present study, thermo-chemical pre-treatment was adopted to evaluate methane production potential from corn stover by co-digesting it with anaerobic activated sludge. Three chemicals H2O2, Ca(OH)2 and NaOH were selected with two levels of concentration. All thermo-chemical pre-treatments were found significant (P<0.05) to enhance lignocellulosic digestibility and methane production. The results indicated that the methane yield by H2O2-1, H2O2-2, and NaOH-2 treated corn stover were 293.52, 310.50 and 279.42ml/g.VS which were 57.18%, 66.27% and 49.63% higher than the untreated corn stover respectively. In the previous studies pre-treatment time was reported in days but our method had reduced it to about one hour. H2O2-2 and NaOH-2 treatments remained prominent to increase lignocellulosic degradation vigorously up to 45% and 42% respectively. Process biochemistry during the anaerobic digestion process was taken into consideration to optimize the most feasible thermo-chemical pre-treatment for corn stover.

  11. It All Starts with a Sandwich: Identification of Sialidases with Trans-Glycosylation Activity

    PubMed Central

    Nordvang, Rune T.; Nyffenegger, Christian; Holck, Jesper; Jers, Carsten; Sundekilde, Ulrik K.; Meyer, Anne S.; Mikkelsen, Jørn D.

    2016-01-01

    Sialidases (3.2.1.18) may exhibit trans-sialidase activity to catalyze sialylation of lactose if the active site topology is congruent with that of the Trypanosoma cruzi trans-sialidase (EC 2.4.1.-). The present work was undertaken to test the hypothesis that a particular aromatic sandwich structure of two amino acids proximal to the active site of the T. cruzi trans-sialidase infers trans-sialidase activity. On this basis, four enzymes with putative trans-sialidase activity were identified through an iterative alignment from 2909 native sialidases available in GenBank, which were cloned and expressed in Escherichia coli. Of these, one enzyme, SialH, derived from Haemophilus parasuis had an aromatic sandwich structure on the protein surface facing the end of the catalytic site (Phe168; Trp366), and was indeed found to exhibit trans-sialidase activity. SialH catalyzed production of the human milk oligosaccharide 3’-sialyllactose as well as the novel trans-sialylation product 3-sialyllactose using casein glycomacropeptide as sialyl donor and lactose as acceptor. The findings corroborated that Tyr119 and Trp312 in the T. cruzi trans-sialidase are part of an aromatic sandwich structure that confers trans-sialylation activity for lactose sialylation. The in silico identification of trans-glycosidase activity by rational active site topology alignment thus proved to be a quick tool for selecting putative trans-sialidases amongst a large group of glycosyl hydrolases. The approach moreover provided data that help understand structure-function relations of trans-sialidases. PMID:27367145

  12. A new process to improve short-chain fatty acids and bio-methane generation from waste activated sludge.

    PubMed

    Dong, Bin; Gao, Peng; Zhang, Dong; Chen, Yinguang; Dai, Lingling; Dai, Xiaohu

    2016-05-01

    As an important intermediate product, short-chain fatty acids (SCFAs) can be generated after hydrolysis and acidification from waste activated sludge, and then can be transformed to methane during anaerobic digestion process. In order to obtain more SCFA and methane, most studies in literatures were centered on enhancing the hydrolysis of sludge anaerobic digestion which was proved as un-efficient. Though the alkaline pretreatment in our previous study increased both the hydrolysis and acidification processes, it had a vast chemical cost which was considered uneconomical. In this paper, a low energy consumption pretreatment method, i.e. enhanced the whole three stages of the anaerobic fermentation processes at the same time, was reported, by which hydrolysis and acidification were both enhanced, and the SCFA and methane generation can be significantly improved with a small quantity of chemical input. Firstly, the effect of different pretreated temperatures and pretreatment time on sludge hydrolyzation was compared. It was found that sludge pretreated at 100°C for 60min can achieve the maximal hydrolyzation. Further, effects of different initial pHs on acidification of the thermal pretreated sludge were investigated and the highest SCFA was observed at initial pH9.0 with fermentation time of 6d, the production of which was 348.63mg COD/gVSS (6.8 times higher than the blank test) and the acetic acid was dominant acid. Then, the mechanisms for this new pretreatment significantly improving SCFA production were discussed. Finally, the effect of this low energy consumption pretreatment on methane generation was investigated.

  13. Field-scale tracking of active methane-oxidizing communities in a landfill cover soil reveals spatial and seasonal variability.

    PubMed

    Henneberger, Ruth; Chiri, Eleonora; Bodelier, Paul E L; Frenzel, Peter; Lüke, Claudia; Schroth, Martin H

    2015-05-01

    Aerobic methane-oxidizing bacteria (MOB) in soils mitigate methane (CH4 ) emissions. We assessed spatial and seasonal differences in active MOB communities in a landfill cover soil characterized by highly variable environmental conditions. Field-based measurements of CH4 oxidation activity and stable-isotope probing of polar lipid-derived fatty acids (PLFA-SIP) were complemented by microarray analysis of pmoA genes and transcripts, linking diversity and function at the field scale. In situ CH4 oxidation rates varied between sites and were generally one order of magnitude lower in winter compared with summer. Results from PLFA-SIP and pmoA transcripts were largely congruent, revealing distinct spatial and seasonal clustering. Overall, active MOB communities were highly diverse. Type Ia MOB, specifically Methylomonas and Methylobacter, were key drivers for CH4 oxidation, particularly at a high-activity site. Type II MOB were mainly active at a site showing substantial fluctuations in CH4 loading and soil moisture content. Notably, Upland Soil Cluster-gamma-related pmoA transcripts were also detected, indicating concurrent oxidation of atmospheric CH4 . Spatial separation was less distinct in winter, with Methylobacter and uncultured MOB mediating CH4 oxidation. We propose that high diversity of active MOB communities in this soil is promoted by high variability in environmental conditions, facilitating substantial removal of CH4 generated in the waste body.

  14. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 5: ACTIVITY FACTORS

    EPA Science Inventory

    The 15-volume report summarizes the results of a comprehensive program to quantify methane (CH4) emissions from the U.S. natural gas industry for the base year. The objective was to determine CH4 emissions from the wellhead and ending downstream at the customer's meter. The accur...

  15. Understanding Methane Emission from Natural Gas Activities Using Inverse Modeling Techniques

    NASA Astrophysics Data System (ADS)

    Abdioskouei, M.; Carmichael, G. R.

    2015-12-01

    Natural gas (NG) has been promoted as a bridge fuel that can smooth the transition from fossil fuels to zero carbon energy sources by having lower carbon dioxide emission and lower global warming impacts in comparison to other fossil fuels. However, the uncertainty around the estimations of methane emissions from NG systems can lead to underestimation of climate and environmental impacts of using NG as a replacement for coal. Accurate estimates of methane emissions from NG operations is crucial for evaluation of environmental impacts of NG extraction and at larger scale, adoption of NG as transitional fuel. However there is a great inconsistency within the current estimates. Forward simulation of methane from oil and gas operation sites for the US is carried out based on NEI-2011 using the WRF-Chem model. Simulated values are compared against measurements of observations from different platforms such as airborne (FRAPPÉ field campaign) and ground-based measurements (NOAA Earth System Research Laboratory). A novel inverse modeling technique is used in this work to improve the model fit to the observation values and to constrain methane emission from oil and gas extraction sites.

  16. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 7: BLOW AND PURGE ACTIVITIES

    EPA Science Inventory

    The 15-volume report summarizes the results of a comprehensive program to quantify methane (CH4) emissions from the U.S. natural gas industry for the base year. The objective was to determine CH4 emissions from the wellhead and ending downstream at the customer's meter. The accur...

  17. The Start of Head Start

    ERIC Educational Resources Information Center

    Neugebauer, Roger

    2010-01-01

    The creation of the Head Start program occurred at break-neck speed with many dramatic turns and many colorful players. No one tells the story better than Edward Zigler in "Head Start: The Inside Story of America's Most Successful Educational Experiment"--a detailed and personal, behind the scenes look at the program's inception. From this…

  18. Fate and Transport of Methane Formed in the Active Layer of Alaskan Permafrost

    NASA Astrophysics Data System (ADS)

    Conrad, M. E.; Curtis, J. B.; Smith, L. J.; Bill, M.; Torn, M. S.

    2015-12-01

    Over the past 2 years a series of tracer tests designed to estimate rates of methane formation via acetoclastic methanogenesis in the active layer of permafrost soils were conducted at the Barrow Environmental Observatory (BEO) in northernmost Alaska. The tracer tests consisted of extracting 0.5 to 1.0 liters of soil water in gas-tight bags from different features of polygons at the BEO, followed by addition of a tracer cocktail including acetate with a 13C-labeled methyl group and D2O (as a conservative tracer) into the soil water and injection of the mixture back into the original extraction site. Samples were then taken at depths of 30 cm (just above the bottom of the active layer), 20 cm, 10 cm and surface flux to determine the fate of the 13C-labeled acetate. During 2014 (2015 results are pending) water, soil gas, and flux gas were sampled for 60 days following injection of the tracer solution. Those samples were analyzed for concentrations and isotopic compositions of CH4, DIC/CO2 and water. At one site (the trough of a low-centered polygon) the 13C acetate was completely converted to 13CH4 within the first 2 days. The signal persisted for throughout the entire monitoring period at the injection depth with little evidence of transport or oxidation in any of the other sampling depths. In the saturated center of the same polygon, the acetate was also rapidly converted to 13CH4, but water turnover caused the signal to rapidly dissipate. High δ13C CO2 in flux samples from the polygon center indicate oxidation of the 13CH4 in near-surface waters. Conversely, CH4 production in the center of an unsaturated, flat-centered polygon was relatively small 13CH4 and dissipated rapidly without any evidence of either 13CH4 transport to shallower levels or oxidation. At another site in the edge of that polygon no 13CH4 was produced, but significant 13CO2/DIC was observed indicating direct aerobic oxidation of the acetate was occurring at this site. These results suggest that

  19. Dry reforming of methane on a highly-active Ni-CeO2 catalyst: Effects of metal-support interactions on C–H bond breaking

    DOE PAGES

    Liu, Zongyuan; Grinter, David C.; Lustemberg, Pablo G.; ...

    2016-05-04

    Ni-CeO2 is a highly efficient, stable and non-expensive catalyst for methane dry reforming at relative low temperatures (700 K). The active phase of the catalyst consists of small nanoparticles of nickel dispersed on partially reduced ceria. Experiments of ambient pressure XPS indicate that methane dissociates on Ni/CeO2 at temperatures as low as 300 K, generating CHx and COx species on the surface of the catalyst. Strong metal–support interactions activate Ni for the dissociation of methane. The results of density-functional calculations show a drop in the effective barrier for methane activation from 0.9 eV on Ni(111) to only 0.15 eV onmore » Ni/CeO2–x(111). At 700 K, under methane dry reforming conditions, no signals for adsorbed CHx or C species are detected in the C1s XPS region. As a result, the reforming of methane proceeds in a clean and efficient way.« less

  20. Dry Reforming of Methane on a Highly-Active Ni-CeO2 Catalyst: Effects of Metal-Support Interactions on C-H Bond Breaking.

    PubMed

    Liu, Zongyuan; Grinter, David C; Lustemberg, Pablo G; Nguyen-Phan, Thuy-Duong; Zhou, Yinghui; Luo, Si; Waluyo, Iradwikanari; Crumlin, Ethan J; Stacchiola, Dario J; Zhou, Jing; Carrasco, Javier; Busnengo, H Fabio; Ganduglia-Pirovano, M Verónica; Senanayake, Sanjaya D; Rodriguez, José A

    2016-06-20

    Ni-CeO2 is a highly efficient, stable and non-expensive catalyst for methane dry reforming at relative low temperatures (700 K). The active phase of the catalyst consists of small nanoparticles of nickel dispersed on partially reduced ceria. Experiments of ambient pressure XPS indicate that methane dissociates on Ni/CeO2 at temperatures as low as 300 K, generating CHx and COx species on the surface of the catalyst. Strong metal-support interactions activate Ni for the dissociation of methane. The results of density-functional calculations show a drop in the effective barrier for methane activation from 0.9 eV on Ni(111) to only 0.15 eV on Ni/CeO2-x (111). At 700 K, under methane dry reforming conditions, no signals for adsorbed CHx or C species are detected in the C 1s XPS region. The reforming of methane proceeds in a clean and efficient way.

  1. METHANE AND WATER ON MARS: MAPS OF ACTIVE REGIONS AND THEIR SEASONAL VARIABILITY

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    We have detected methane on Mars, and measured it simultaneously with water using powerful ground-based telescopes [1, 2]. Its presence in such a strongly oxidized atmosphere (CO2: 95.3%) requires recent release; the ultimate origin of this methane is uncertain, but it could either be abiotic or biotic. On Earth, methane is produced primarily by biology, with a small fraction produced by abiotic means. The sources and sinks of hydrogen-bearing species (e.g., H2O and CH4) on Mars are still poorly known. In particular, the roles of the regolith and the sub-surface hydrogen reservoirs in the Martian water cycle have been broadly studied, but have not been conclusively quantified. If water is being released from the sub-surface or shares a common source with other H-bearing species, we might see correlations among them. Previous searches for such correlations have been precluded because of the lack of simultaneity of the measurements and the intrinsic variability of water on Mars, which is a condensable whose total local abundance is partitioned among several competing phases controlled largely by temperature (ensuring its variability on a variety of time scales, from diurnal to seasonal to epochal). We sampled multiple spectral lines of methane and water vapor on Mars in a campaign spanning seven years (three Mars years; 1999-2006) and sampling three seasons on Mars. Data were ac-quired using long-slit infrared spectrometers: CSHELL (Cryogenic Echelle Spectrograph) at NASA-IRTF (Infrared Telescope Facility) and NIRSPEC (Near Infrared Spectrograph) at Keck 2. These instruments offer spatially-resolved spectra with the high spectral resolving power (λ/δλ ~ 40,000) needed to reduce confusion among telluric, Martian, and Fraunhofer lines (in reflected solar radiation). Since 2005, we greatly improved our data processing algorithms and increased the sensitivity of our measurements by an order of magnitude. Using these new techniques, we detected multiple lines of

  2. Hydrogen production using thermocatalytic decomposition of methane on Ni30/activated carbon and Ni30/carbon black.

    PubMed

    Srilatha, K; Viditha, V; Srinivasulu, D; Ramakrishna, S U B; Himabindu, V

    2016-05-01

    Hydrogen is an energy carrier of the future need. It could be produced from different sources and used for power generation or as a transport fuel which mainly in association with fuel cells. The primary challenge for hydrogen production is reducing the cost of production technologies to make the resulting hydrogen cost competitive with conventional fuels. Thermocatalytic decomposition (TCD) of methane is one of the most advantageous processes, which will meet the future demand, hence an attractive route for COx free environment. The present study deals with the production of hydrogen with 30 wt% of Ni impregnated in commercially available activated carbon and carbon black catalysts (samples coded as Ni30/AC and Ni30/CB, respectively). These combined catalysts were not attempted by previous studies. Pure form of hydrogen is produced at 850 °C and volume hourly space velocity (VHSV) of 1.62 L/h g on the activity of both the catalysts. The analysis (X-ray diffraction (XRD)) of the catalysts reveals moderately crystalline peaks of Ni, which might be responsible for the increase in catalytic life along with formation of carbon fibers. The activity of carbon black is sustainable for a longer time compared to that of activated carbon which has been confirmed by life time studies (850 °C and 54 sccm of methane).

  3. Spatial and Temporal Variability in Atmospheric-Methane-Oxidizing Bacterial Community Structure and Activity in an Alpine Glacier Forefield

    NASA Astrophysics Data System (ADS)

    Chiri, E.; Nauer, P. A.; Rainer, E. M.; Zeyer, J. A.; Schroth, M. H.

    2015-12-01

    High-affinity methane-oxidizing bacteria (MOB) play a crucial role in regulating the sink strength for atmospheric methane (CH4) in upland soils. Community structure and activity of MOB have been extensively studied in developed soils. However, little is known about their ecosystem service in young, developing soils. Examples of developing soils are found in Alpine glacier forefields, which progressively expand due to glacial retreat. Glacier forefields exhibit diverse geomorphological landforms, which may differ in biogeochemical properties. Also, glacier forefields are subject to seasonal variability in environmental parameters such as soil temperature and water content, which may affect MOB community structure and activity. We recently showed that glacier-forefield soils are a sink for atmospheric CH4, but a comprehensive understanding of crucial factors affecting MOB community structure and activity is still missing. In this study we assessed soil-atmosphere CH4 flux and MOB community structure in three different glacier-forefield landforms (sandhills, floodplains, terraces) throughout a snow-free sampling season. Specifically, we quantified CH4 flux using the soil-gas-profile method and static flux chambers. The MOB community structure was assessed using next-generation sequencing technology (Illumina-MiSeqTM) targeting the functional gene pmoA. We observed substantial differences in CH4 flux between soils of different landforms, with largest fluxes observed in well-drained sandhills (up to -2.2 mg CH4 m-2 d-1) and considerably smaller fluxes in other landforms. Methane flux showed a prominent seasonal variability, which was attenuated in older forefield soils. High-diversity MOB communities and a remarkable number of landform-specific operational taxonomic units were found in sandhills, whereas a lower diversity was observed in other landforms. Our phylogenetic analysis suggests the presence of a potentially new group of MOB inhabiting glacier-forefield soils.

  4. Views of Growing Methane Emissions near Oil and Natural Gas Activity: Satellite, Aircraft, and Ground

    NASA Astrophysics Data System (ADS)

    Kollonige, D. E.; Thompson, A. M.; Diskin, G. S.; Hannigan, J. W.; Nussbaumer, E.

    2015-12-01

    To better understand the discrepancies between current top-down and bottom-up estimates, additional methane (CH4) measurements are necessary for regions surrounding growing oil and natural gas (ONG) development. We have evaluated satellite measurements of CH4 in US regions with ONG operations for their application as "top-down" constraints (part of the NASA Air Quality Applied Sciences Team (AQAST) project). For validation of the satellite instruments' sensitivities to emitted gases, we focus on regions where the DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) campaign deployed ground and aircraft measurements in Maryland (2011), California and Texas (2013), and Colorado (2014). The largest CH4 signals were observed in the Greater Green River and Powder River Basins using Tropospheric Emission Spectrometer (TES) Representative Tropospheric Volume Mixing Ratio (RTVMR) measurements. A long-term comparison between a ground remote-sensing Fourier Transform Spectrometer (FTS) at Boulder and TES for 2010-2013 shows good correlation and differences ranging 2.5-5% for their yearly distribution of total column CH4. To determine any correlation between lower/mid-tropospheric CH4 (where a thermal IR sensor, such as TES, is most sensitive) and near-surface/boundary CH4 (where sources emit), we analyze the variability of DISCOVER-AQ aircraft profiles using principal component analysis and assess the correlation between near-surface (0-2 km) and mid-tropospheric (>2 km) CH4 concentrations. Using these relationships, we estimate near-surface CH4 using mid-tropospheric satellite measurements based on the partial column amounts within vertical layers with a linear regression. From this analysis, we will demonstrate whether the uncertainties of satellite-estimated near-surface CH4 are comparable to observed variability near ONG activity. These results will assist validation of satellite instrument

  5. Enzymatic Oxidation of Methane

    SciTech Connect

    Sirajuddin, S; Rosenzweig, AC

    2015-04-14

    Methane monooxygenases (MMOs) are enzymes that catalyze the oxidation of methane to methanol in methanotrophic bacteria. As potential targets for new gas-to-liquid methane bioconversion processes, MMOs have attracted intense attention in recent years. There are two distinct types of MMO, a soluble, cytoplasmic MMO (sMMO) and a membrane-bound, particulate MMO (pMMO). Both oxidize methane at metal centers within a complex, multisubunit scaffold, but the structures, active sites, and chemical mechanisms are completely different. This Current Topic review article focuses on the overall architectures, active site structures, substrate reactivities, proteinprotein interactions, and chemical mechanisms of both MMOs, with an emphasis on fundamental aspects. In addition, recent advances, including new details of interactions between the sMMO components, characterization of sMMO intermediates, and progress toward understanding the pMMO metal centers are highlighted. The work summarized here provides a guide for those interested in exploiting MMOs for biotechnological applications.

  6. Family Background, School-Age Trajectories of Activity Participation, and Academic Achievement at the Start of High School

    PubMed Central

    Crosnoe, Robert; Smith, Chelsea; Leventhal, Tama

    2014-01-01

    Applying latent class and regression techniques to data from the NICHD Study of Early Child Care and Youth Development (n = 997), this study explored the potential academic advantages of time spent in out-of-school activities. Of particular interest was how these potential advantages played out in relation to the timing and duration of activity participation and the family contexts in which it occurred. Participation closer to the start of high school—including consistent participants and latecomers—was associated with higher grades at the transition into high school, especially for youth from low-income families. Sensitivity analyses indicated that this link between school-age activity participation and adolescent academic progress was unlikely to be solely a function of selection. It also tended to be more pronounced among youth from lower-income families, although without varying by other aspects of family status or process. PMID:26279615

  7. Antiprotozoal Activity Profiling of Approved Drugs: A Starting Point toward Drug Repositioning

    PubMed Central

    Kaiser, Marcel; Mäser, Pascal; Tadoori, Leela Pavan; Ioset, Jean-Robert; Brun, Reto

    2015-01-01

    Neglected tropical diseases cause significant morbidity and mortality and are a source of poverty in endemic countries. Only a few drugs are available to treat diseases such as leishmaniasis, Chagas’ disease, human African trypanosomiasis and malaria. Since drug development is lengthy and expensive, a drug repurposing strategy offers an attractive fast-track approach to speed up the process. A set of 100 registered drugs with drug repositioning potential for neglected diseases was assembled and tested in vitro against four protozoan parasites associated with the aforementioned diseases. Several drugs and drug classes showed in vitro activity in those screening assays. The results are critically reviewed and discussed in the perspective of a follow-up drug repositioning strategy where R&D has to be addressed with limited resources. PMID:26270335

  8. Antiprotozoal Activity Profiling of Approved Drugs: A Starting Point toward Drug Repositioning.

    PubMed

    Kaiser, Marcel; Mäser, Pascal; Tadoori, Leela Pavan; Ioset, Jean-Robert; Brun, Reto

    2015-01-01

    Neglected tropical diseases cause significant morbidity and mortality and are a source of poverty in endemic countries. Only a few drugs are available to treat diseases such as leishmaniasis, Chagas' disease, human African trypanosomiasis and malaria. Since drug development is lengthy and expensive, a drug repurposing strategy offers an attractive fast-track approach to speed up the process. A set of 100 registered drugs with drug repositioning potential for neglected diseases was assembled and tested in vitro against four protozoan parasites associated with the aforementioned diseases. Several drugs and drug classes showed in vitro activity in those screening assays. The results are critically reviewed and discussed in the perspective of a follow-up drug repositioning strategy where R&D has to be addressed with limited resources.

  9. Unhealthy Alcohol Use is Associated with Monocyte Activation Prior to Starting Anti-Retroviral Therapy

    PubMed Central

    Carrico, Adam W.; Hunt, Peter W.; Emenyonu, Nneka I.; Muyindike, Winnie; Ngabirano, Christine; Cheng, Debbie M.; Winter, Michael R.; Samet, Jeffrey H.; Hahn, Judith A.

    2015-01-01

    Background Alcohol use may accelerate HIV disease progression, but the plausible biological mechanisms have not been clearly elucidated. Methods HIV-positive persons who were not on anti-retroviral therapy (ART) completed the baseline assessment for a longitudinal study examining the association of alcohol use with HIV disease markers. Oversampling drinkers, baseline samples were tested for markers of monocyte activation (sCD14), inflammation (IL-6), and coagulation (D-dimer). We defined “unhealthy alcohol use” as testing positive using the Alcohol Use Disorders Identification Test – Consumption (AUDIT-C; ≥ 3 for women and ≥ 4 for men) in the past 3 months or testing positive using a biomarker of heavy drinking, phophatidylethanol (PEth; ≥ 50 ng/ml). Multiple linear regression was used to examine the associations of unhealthy alcohol use with sCD14, Log10 IL-6, and D-dimer. Results Compared to those who were abstinent from alcohol, unhealthy drinkers had significantly higher sCD14 levels (mean = 1,676 vs. 1,387 ng/ml; mean difference (95% CI) = 289 (83, 495), p < 0.01). In analyses adjusted for demographic factors, current cigarette smoking, and HIV disease markers, unhealthy drinkers continued to display significantly higher sCD14 levels compared to those who were abstinent from alcohol (adjusted mean = 1,670 vs. 1,406 ng/ml; adjusted mean difference (95% CI) = 264 (47, 480), p = 0.02). Unhealthy alcohol use was not significantly associated with IL-6 or D-dimer levels. Conclusions unhealthy alcohol use was independently associated with a marker of monocyte activation (i.e., higher sCD14) that predicts mortality in treated HIV infection. Longitudinal research should examine if unhealthy alcohol use predicts changes in sCD14 prior to and following ART initiation. PMID:26509359

  10. Effect of nitrogen-containing impurities on the activity of perovskitic catalysts for the catalytic combustion of methane.

    PubMed

    Buchneva, Olga; Gallo, Alessandro; Rossetti, Ilenia

    2012-11-05

    LaMnO(3), either pure or doped with 10 mol % Sr, has been prepared by flame pyrolysis in nanostructured form. Such catalysts have been tested for the catalytic flameless combustion of methane, achieving very high catalytic activity. The resistance toward poisoning by some model N-containing impurities has been checked in order to assess the possibility of operating the flameless catalytic combustion with biogas, possibly contaminated by S- or N-based compounds. This would be a significant improvement from the environmental point of view because the application of catalytic combustion to gas turbines would couple improved energy conversion efficiency and negligible noxious emissions, while the use of biogas would open the way to energy production from a renewable source by means of very efficient technologies. A different behavior has been observed for the two catalysts; namely, the undoped sample was more or less heavily poisoned, whereas the Sr-doped sample showed slightly increasing activity upon dosage of N-containing compounds. A possible reaction mechanism has been suggested, based on the initial oxidation of the organic backbone, with the formation of NO. The latter may adsorb more or less strongly depending on the availability of surface oxygen vacancies (i.e., depending on doping). Decomposition of NO may leave additional activated oxygen species on the surface, available for low-temperature methane oxidation and so improving the catalytic performance.

  11. Smog Chamber Investigation on the Iron-Catalyzed Activation of Chloride from Seasalt for a Depletion of Tropospheric Methane

    NASA Astrophysics Data System (ADS)

    Zetzsch, C.; Bleicher, S.; Wittmer, J.

    2013-12-01

    Investigations on NaCl saltpans in an environmental simulation chamber under artificial sunlight yield high concentrations of chlorine atoms in the gas phase if FeCl3 is added to the salt mixture. The impact of chlorine atoms led in a direct experiment to a methane reduction of 8% within 24 h. This corresponds to a methane lifetime of only 12 days in a constantly illuminated chamber (or a half-life of 8 days). In quantitative measurements almost 1E6 Cl atoms per cm3 were observed as peak concentrations in the chamber above mixtures of NaCl and 0.5% FeCl3. This would decrease the lifetime of methane under atmospheric conditions of usually 8-10 years down to a hundredth of it. Typical values ranged from 105 to 106 Cl atoms per cm3. The direct Cl measurements allowed us to calculate the Cl2 source strength to reach a maximum of 8E11 Cl2 molecules per cm3 within the first hour of the experiment, corresponding to a Cl2 mixing ratio of 30 ppbv at standard pressure. The salt samples consisted of 100 g total mass with various mixing ratios of NaCl and FeCl3, NaBr, catechol, oxalate, sulfate and MgCl2. The additions of catechol, Na-oxalate and Na-sulfate led to a distinct reduction of the chloride activation by a complexation of the iron ions. Samples with added NaBr showed very high concentrations of Br atoms above 1E10 atoms per cm3, though only low Cl values. Whether the activation of chloride still occurs under addition of other iron species like Fe2O3 remained unresolved. Pending questions are moreover a possible formation of organochlorine compounds and the absolute surface of the saltpan samples.

  12. State selective vibrational (2ν3) activation of the chemisorption of methane on Pt (111)

    NASA Astrophysics Data System (ADS)

    Higgins, J.; Conjusteau, A.; Scoles, G.; Bernasek, S. L.

    2001-03-01

    The state-selective dissociative sticking coefficient on Pt(111) surfaces for CH4 in the 2ν3 J=1,2 ro-vibrational levels has been measured using thermal energy atomic scattering. Continuous wave laser excitation of a molecular beam of CH4 seeded in He with a 1.5 μm color center laser, tunable around 6000 cm-1 and coupled to the beam by means of a resonant build-up cavity, allows pumping of up to 11% of the molecules to the excited ro-vibrational state. The laser/molecular beam combination allows precise control over the translational energy as well as the vibrational state of the methane that impinges on the clean Pt(111) surface. The intensity of the specular reflection of the incident helium beam is used to quantitatively monitor the coverage of chemisorbed methane on the platinum surface as a function of time (exposure). The sticking coefficient (S0) of CH4 with 5.4 kJ/mol normal translational energy is found to increase from 6.2×10-6 to 1.8×10-4 upon 2ν3 excitation (the overtone of the asymmetric stretch of methane). This represents a ˜30 fold enhancement in reactivity of the methane with the Pt(111) surface upon vibrational excitation. We also measured the changes of S0 obtained by varying the nozzle temperature and methane concentration over a tenfold range of energy. We find that 72 kJ/mol of vibrational energy in the excited CH4 is approximately equivalent to at least 30 kJ/mol of normal translational energy. This corresponds to a utilization efficiency of the 2ν3 vibrational energy of greater than 40%. In the only other measurement of this kind published in the literature, [L. B. F. Juurlink, P. R. McCabe, R. R. Smith, C. L. DiCologero, and A. L. Utz, Phys. Rev Lett. 83, 868 (1999)] for the fundamental (v=1) excitation of ν3 of CH4 on Ni(100) surfaces, a comparable value for the vibrational energy utilization efficiency was found (59%). Further work is necessary to determine if this result is general and if and how it may change by changing the

  13. Experimental and computational active site mapping as a starting point to fragment-based lead discovery.

    PubMed

    Behnen, Jürgen; Köster, Helene; Neudert, Gerd; Craan, Tobias; Heine, Andreas; Klebe, Gerhard

    2012-02-06

    Small highly soluble probe molecules such as aniline, urea, N-methylurea, 2-bromoacetate, 1,2-propanediol, nitrous oxide, benzamidine, and phenol were soaked into crystals of various proteins to map their binding pockets and to detect hot spots of binding with respect to hydrophobic and hydrophilic properties. The selected probe molecules were first tested at the zinc protease thermolysin. They were then applied to a wider range of proteins such as protein kinase A, D-xylose isomerase, 4-diphosphocytidyl-2C-methyl-D-erythritol synthase, endothiapepsin, and secreted aspartic protease 2. The crystal structures obtained clearly show that the probe molecules populate the protein binding pockets in an ordered fashion. The thus characterized, experimentally observed hot spots of binding were subjected to computational active site mapping using HotspotsX. This approach uses knowledge-based pair potentials to detect favorable binding positions for various atom types. Good agreement between the in silico hot spot predictions and the experimentally observed positions of the polar hydrogen bond forming functional groups and hydrophobic portions was obtained. Finally, we compared the observed poses of the small-molecule probes with those of much larger structurally related ligands. They coincide remarkably well with the larger ligands, considering their spatial orientation and the experienced interaction patterns. This observation confirms the fundamental hypothesis of fragment-based lead discovery: that binding poses, even of very small molecular probes, do not significantly deviate or move once a ligand is grown further into the binding site. This underscores the fact that these probes populate given hot spots and can be regarded as relevant seeds for further design.

  14. Methane reforming in a temperature-controlled DBD reactor

    NASA Astrophysics Data System (ADS)

    Levko, Dmitry; Raja, Laxminarayan

    2015-09-01

    Methane and carbon dioxide are among the main products of human activity. Therefore, they are considered among greenhouse gases, which may cause the global warming. On the other hand, methane is widely used in everyday life as an energy source and in industry for the synthesis of different chemicals. In order to utilize greenhouse gases or to generate chemicals from methane, one needs first to dissociate it. Then, this gas converts into desired products such as methanol, gasoline, syn-gas etc. Nowadays, there are several methods for CH4 conversion. Steam reforming, partial oxidation, thermal and non-thermal plasmas are among them. During the last decades, the use of non-thermal plasma for methane reforming attracts more and more attention. This is caused by the possibility to control the process of methane conversion as well as the gas component content at the reactor outlet. In addition, the use of non-thermal plasma facilitates the control of reactor start up. The goal of the present work is the deep understanding of the plasma chemical processes accompanying the methane-air conversion in a temperature-controlled DBD reactor. To do this, we have developed the kinetic mechanism of CH4/N2/O2 conversion for the gas temperature range 300-800 K and applied it to the global model.

  15. Activated expression of an Arabidopsis HD-START protein confers drought tolerance with improved root system and reduced stomatal density.

    PubMed

    Yu, Hong; Chen, Xi; Hong, Yuan-Yuan; Wang, Yao; Xu, Ping; Ke, Sheng-Dong; Liu, Hai-Yan; Zhu, Jian-Kang; Oliver, David J; Xiang, Cheng-Bin

    2008-04-01

    Drought is one of the most important environmental constraints limiting plant growth and agricultural productivity. To understand the underlying mechanism of drought tolerance and to identify genes for improving this important trait, we conducted a gain-of-function genetic screen for improved drought tolerance in Arabidopsis thaliana. One mutant with improved drought tolerance was isolated and designated as enhanced drought tolerance1. The mutant has a more extensive root system than the wild type, with deeper roots and more lateral roots, and shows a reduced leaf stomatal density. The mutant had higher levels of abscisic acid and Pro than the wild type and demonstrated an increased resistance to oxidative stress and high levels of superoxide dismutase. Molecular genetic analysis and recapitulation experiments showed that the enhanced drought tolerance is caused by the activated expression of a T-DNA tagged gene that encodes a putative homeodomain-START transcription factor. Moreover, overexpressing the cDNA of the transcription factor in transgenic tobacco also conferred drought tolerance associated with improved root architecture and reduced leaf stomatal density. Therefore, we have revealed functions of the homeodomain-START factor that were gained upon altering its expression pattern by activation tagging and provide a key regulator that may be used to improve drought tolerance in plants.

  16. Nucleosome positioning and kinetics near transcription-start-site barriers are controlled by interplay between active remodeling and DNA sequence.

    PubMed

    Parmar, Jyotsana J; Marko, John F; Padinhateeri, Ranjith

    2014-01-01

    We investigate how DNA sequence, ATP-dependent chromatin remodeling and nucleosome-depleted 'barriers' co-operate to determine the kinetics of nucleosome organization, in a stochastic model of nucleosome positioning and dynamics. We find that 'statistical' positioning of nucleosomes against 'barriers', hypothesized to control chromatin structure near transcription start sites, requires active remodeling and therefore cannot be described using equilibrium statistical mechanics. We show that, unlike steady-state occupancy, DNA site exposure kinetics near a barrier is dominated by DNA sequence rather than by proximity to the barrier itself. The timescale for formation of positioning patterns near barriers is proportional to the timescale for active nucleosome eviction. We also show that there are strong gene-to-gene variations in nucleosome positioning near barriers, which are eliminated by averaging over many genes. Our results suggest that measurement of nucleosome kinetics can reveal information about sequence-dependent regulation that is not apparent in steady-state nucleosome occupancy.

  17. Biological and biochemical methane reactions

    NASA Astrophysics Data System (ADS)

    Dalton, H.; Pienkos, P. T.; Stirling, D. I.

    1989-04-01

    The purpose of the project was to characterize the nature of the active site involved in methane activation by enzymes from well characterized and newly isolated methane-oxidizing bacteria. Kinetic and structural studies provided an initial picture of how the soluble methane monooxygenase (MMO) enzyme is structured and operates to selectively oxidize methane to methanol under ambient conditions. Cloning and sequencing of gene coding for some of the sMMO proteins were completed, and 72 strains of methanotrophs were isolated from extreme environments.

  18. Longitudinal Distribution of Solar Magnetic Fields and Activity During the Ending and Starting Periods of Activity Cycles

    NASA Astrophysics Data System (ADS)

    Bumba, V.; Garcia, A.; Klvaňa, M.

    2000-10-01

    Studying the appearance of active regions during periods of solar activity minima, we observed that the magnetic fields of active regions belonging to the old and new cycle were mutually related. This was the reason we decided to investigate the relation of the old and new cycle activity during the two last minima in more detail. We examined the distribution of both activities in heliographic longitude, because the patterns of such distribution change substantially during the time of the minimum, and we studied their relation to the distribution and development of the global (background) magnetic field. We observed that the active regions of the old and new cycles tended to concentrate in the same active longitudes. The sources of their magnetic fluxes seem to have the same heliographic longitude. The beginning of the new cycle activity, occurring at the very beginning to a very weak degree in the equatorial zone, and then proceeding to higher latitudes, occurs in the magnetic field remnants of the old cycle activity. During the transition phase, a relatively large number of small active regions is produced by both cycles.

  19. Pay Me Now or Pay Me More Later: Start the Development of Active Orbital Debris Removal Now

    NASA Astrophysics Data System (ADS)

    McKnight, D.

    2010-09-01

    The objective of this paper is to examine when the aerospace community should proceed to develop and deploy active debris removal solutions. A two-prong approach is taken to examine both (1) operational hazard thresholds and (2) economic triggers. Research in the paper reinforces work by previous investigators that show accurately determining a hazard metric, and an appropriate threshold for that metric that triggers an imperative to implement active debris removal options, is difficult to formulate. A new operational hazard threshold defined by the doubling of the “lethal” debris environment coupled with the threshold that would affect insurance premiums is disclosed for the first time. The doubling of the lethal hazard at 850km and the annual probability of collision in the 650-1000km region may both occur as early as 2035. A simple static (i.e. no temporal dimension) economic threshold is derived that provides the clearest indicator that active debris removal solutions development and deployment should start immediately. This straightforward observation is based on the fact that it will always be at least an order of magnitude less expensive, quicker to execute, and operationally beneficial to remove mass from orbit as one large (several thousand kilograms) object rather than as the result of tens of thousands of fragments that would be produced from a catastrophic collision. Additionally, the ratio of lethal fragments to trackable objects is only ~1,000x yet there is a need for the collection efficiency to be ~10,000x so “sweeping” of lethal fragments is not viable. The practicality of the large object removal is tempered by the observation that one may have to remove ~10-50x derelict objects to prevent a single collision. This fact forces the imperative that removal needs to start now due to the delays that will be necessary not only to perfect/deploy approaches to debris removal and establish supporting policies/regulations but also because of the

  20. Press Start

    NASA Astrophysics Data System (ADS)

    Harteveld, Casper

    This level sets the stage for the design philosophy called “Triadic Game Design” (TGD). This design philosophy can be summarized with the following sentence: it takes two to tango, but it takes three to design a meaningful game or a game with a purpose. Before the philosophy is further explained, this level will first delve into what is meant by a meaningful game or a game with a purpose. Many terms and definitions have seen the light and in this book I will specifically orient at digital games that aim to have an effect beyond the context of the game itself. Subsequently, a historical overview is given of the usage of games with a serious purpose which starts from the moment we human beings started to walk on our feet till our contemporary society. It turns out that we have been using games for all kinds of non-entertainment purposes for already quite a long time. With this introductory material in the back of our minds, I will explain the concept of TGD by means of a puzzle. After that, the protagonist of this book, the game Levee Patroller, is introduced. Based on the development of this game, the idea of TGD, which stresses to balance three different worlds, the worlds of Reality, Meaning, and Play, came into being. Interested? Then I suggest to quickly “press start!”

  1. Changes in methane oxidation activity and methanotrophic community composition in saline alkaline soils.

    PubMed

    Serrano-Silva, Nancy; Valenzuela-Encinas, César; Marsch, Rodolfo; Dendooven, Luc; Alcántara-Hernández, Rocio J

    2014-05-01

    The soil of the former Lake Texcoco is a saline alkaline environment where anthropogenic drainage in some areas has reduced salt content and pH. Potential methane (CH4) consumption rates were measured in three soils of the former Lake Texcoco with different electrolytic conductivity (EC) and pH, i.e. Tex-S1 a >18 years drained soil (EC 0.7 dS m(-1), pH 8.5), Tex-S2 drained for ~10 years (EC 9.0 dS m(-1), pH 10.3) and the undrained Tex-S3 (EC 84.8 dS m(-1), pH 10.3). An arable soil from Alcholoya (EC 0.7 dS m(-1), pH 6.7), located nearby Lake Texcoco was used as control. Methane oxidation in the soil Tex-S1 (lowest EC and pH) was similar to that in the arable soil from Alcholoya (32.5 and 34.7 mg CH4 kg(-1) dry soil day(-1), respectively). Meanwhile, in soils Tex-S2 and Tex-S3, the potential CH4 oxidation rates were only 15.0 and 12.8 mg CH4 kg(-1) dry soil day(-1), respectively. Differences in CH4 oxidation were also related to changes in the methane-oxidizing communities in these soils. Sequence analysis of pmoA gene showed that soils differed in the identity and number of methanotrophic phylotypes. The Alcholoya soil and Tex-S1 contained phylotypes grouped within the upland soil cluster gamma and the Jasper Ridge, California JR-2 clade. In soil Tex-S3, a phylotype related to Methylomicrobium alcaliphilum was detected.

  2. Hydrogen and methane production by co-digestion of waste activated sludge and food waste in the two-stage fermentation process: substrate conversion and energy yield.

    PubMed

    Liu, Xinyuan; Li, Ruying; Ji, Min; Han, Li

    2013-10-01

    Batch experiments were conducted to produce hydrogen and methane from waste activated sludge and food waste by two-stage mesophilic fermentation. Hydrogen and methane production, energy yield, soluble organic matters, volatile solid removal efficiency and carbon footprint were investigated during two-stage digestion at various food waste proportions. The highest energy yield reached 14.0 kJ/g-VS at the food waste proportion of 85%, with hydrogen and methane yields of 106.4 ml-H2/g-VS and 353.5 ml-CH4/g-VS respectively. The dominant VFA composition was butyrate for co-digestion and sole food waste fermentation, whereas acetate was dominate in VFA for sole waste activated sludge fermentation. The VS removal efficiencies of co-digestion were 10-77% higher than that of waste activated sludge fermentation. Only 0.1-3.2% of the COD in feedstock was converted into hydrogen, and 14.1-40.9% to methane, with the highest value of 40.9% in methane achieved at food waste proportion of 85%.

  3. Methane-cycling communities in a permafrost-affected soil on Herschel Island, Western Canadian Arctic: active layer profiling of mcrA and pmoA genes.

    PubMed

    Barbier, Béatrice A; Dziduch, Isabel; Liebner, Susanne; Ganzert, Lars; Lantuit, Hugues; Pollard, Wayne; Wagner, Dirk

    2012-11-01

    In Arctic wet tundra, microbial controls on organic matter decomposition are likely to be altered as a result of climatic disruption. Here, we present a study on the activity, diversity and vertical distribution of methane-cycling microbial communities in the active layer of wet polygonal tundra on Herschel Island. We recorded potential methane production rates from 5 to 40 nmol h(-1) g(-1) wet soil at 10 °C and significantly higher methane oxidation rates reaching values of 6-10 μmol h(-1) g(-1) wet soil. Terminal restriction fragment length polymorphism (T-RFLP) and cloning analyses of mcrA and pmoA genes demonstrated that both communities were stratified along the active layer vertical profile. Similar to other wet Arctic tundra, the methanogenic community hosted hydrogenotrophic (Methanobacterium) as well as acetoclastic (Methanosarcina and Methanosaeta) members. A pronounced shift toward a dominance of acetoclastic methanogens was observed in deeper soil layers. In contrast to related circum-Arctic studies, the methane-oxidizing (methanotrophic) community on Herschel Island was dominated by members of the type II group (Methylocystis, Methylosinus, and a cluster related to Methylocapsa). The present study represents the first on methane-cycling communities in the Canadian Western Arctic, thus advancing our understanding of these communities in a changing Arctic.

  4. Tobermolite effects on methane removal activity and microbial community of a lab-scale soil biocover.

    PubMed

    Moon, Kyung-Eun; Lee, Eun-Hee; Kim, Tae Gwan; Cho, Kyung-Suk

    2014-07-01

    Three identical lab-scale biocovers were packed with an engineered soil (BC 1), tobermolite only (BC 2), and a mixture of the soil and tobermolite (BC 3), and were operated at an inlet load of 338-400 g-CH4 m(-2) d(-1) and a space velocity of 0.12 h(-1). The methane removal capacity was 293 ± 47 g-CH4 m(-2) d(-1) in steady state in the BC 3, which was significantly higher than those in the BC 1 and BC 2 (106 ± 24 and 114 ± 48 g-CH4 m(-2) d(-1), respectively). Quantitative PCR indicated that bacterial and methanotrophic densities (6.62-6.78 × 10(7) 16S rDNA gene copy number g-dry sample(-1) and 1.37-2.23 × 10(7) pmoA gene copy number g-dry sample(-1) in the BC 1 and BC 3, respectively) were significantly higher than those in the BC 2. Ribosomal tag pyrosequencing showed that methanotrophs comprised approximately 60 % of the bacterial community in the BC 2 and BC 3, while they only comprised 43 % in the BC 1. The engineered soil favored the growth of total bacteria including methanotrophs, while the presence of tobermolite enhanced the relative abundance of methanotrophs, resulting in an improved habitat for methanotrophs as well as greater methane mitigation performance in the mixture. Moreover, a batch experiment indicated that the soil and tobermolite mixture could display a stable methane oxidation level over wide temperature (20-40 °C, at least 38 μmol g-dry sample(-1) h(-1)) and pH (5-8, at least 61 μmol g-dry sample(-1) h(-1)) ranges. In conclusion, the soil and tobermolite mixture is promising for methane mitigation.

  5. Spastin subcellular localization is regulated through usage of different translation start sites and active export from the nucleus

    SciTech Connect

    Claudiani, Pamela; Riano, Elena; Errico, Alessia; Andolfi, Gennaro; Rugarli, Elena I. . E-mail: rugarli@tigem.it

    2005-10-01

    Most cases of autosomal-dominant hereditary spastic paraplegia are linked to mutations in SPG4 encoding spastin, a protein involved in microtubule dynamics and membrane trafficking. In pyramidal neurons of the motor cortex and in immortalized motor neurons, spastin is localized to the synaptic terminals and growth cones. However, in other neurons and in proliferating cells spastin is prevalently nuclear. The mechanisms that determine targeting of spastin to the nucleus or the cytoplasm are unknown. We show here that the SPG4 mRNA is able to direct synthesis of two spastin isoforms, 68 and 60 kDa, respectively, through usage of two different translational start sites. Both isoforms are imported into the nucleus, but the 68-kDa isoform contains two nuclear export signals that efficiently drive export to the cytoplasm. Nuclear export is leptomycin-B sensitive. The cytoplasmic 68-kDa spastin isoform is more abundant in the brain and the spinal cord than in other tissues. Our data indicate that spastin function is modulated through usage of alternative translational start sites and active nuclear import and export, and open new perspectives for the pathogenesis of hereditary spastic paraplegia.

  6. High reactivity of nanosized niobium oxide cluster cations in methane activation: A comparison with vanadium oxides

    SciTech Connect

    Ding, Xun-Lei E-mail: chemzyx@iccas.ac.cn; Wang, Dan; Wu, Xiao-Nan; Li, Zi-Yu; Zhao, Yan-Xia E-mail: chemzyx@iccas.ac.cn; He, Sheng-Gui

    2015-09-28

    The reactions between methane and niobium oxide cluster cations were studied and compared to those employing vanadium oxides. Hydrogen atom abstraction (HAA) reactions were identified over stoichiometric (Nb{sub 2}O{sub 5}){sub N}{sup +} clusters for N as large as 14 with a time-of-flight mass spectrometer. The reactivity of (Nb{sub 2}O{sub 5}){sub N}{sup +} clusters decreases as the N increases, and it is higher than that of (V {sub 2}O{sub 5}){sub N}{sup +} for N ≥ 4. Theoretical studies were conducted on (Nb{sub 2}O{sub 5}){sub N}{sup +} (N = 2–6) by density functional calculations. HAA reactions on these clusters are all favorable thermodynamically and kinetically. The difference of the reactivity with respect to the cluster size and metal type (Nb vs V) was attributed to thermodynamics, kinetics, the electron capture ability, and the distribution of the unpaired spin density. Nanosized Nb oxide clusters show higher HAA reactivity than V oxides, indicating that niobia may serve as promising catalysts for practical methane conversion.

  7. A theoretical approach to the photochemical activation of matrix isolated aluminum atoms and their reaction with methane

    SciTech Connect

    Pacheco-Blas, M. A.; Novaro, O. A.; Pacheco-Sanchez, J. H.

    2010-11-07

    The photochemical activation of Al atoms in cryogenic matrices to induce their reaction with methane has been experimentally studied before. Here, a theoretical study of the nonadiabatic transition probabilities for the ground ({sup 2}P:3s{sup 2}3p{sup 1}) and the lowest excited states ({sup 2}S:3s{sup 2}4s{sup 1} and {sup 2}D:3s{sup 2}3d{sup 1}) of an aluminum atom interacting with a methane molecule (CH{sub 4}) was carried out through ab initio Hartree-Fock self-consistent field calculations. This was followed by a multiconfigurational study of the correlation energy obtained by extensive variational and perturbational configuration interaction analyses using the CIPSI program. The {sup 2}D state is readily inserted into a C-H bond, this being a prelude to a sequence of avoided crossings with the initially repulsive (to CH{sub 4}) lower lying states {sup 2}P and {sup 2}S. We then use a direct extension of the Landau-Zener theory to obtain transition probabilities at each avoided crossing, allowing the formation of an HAlCH{sub 3} intermediate that eventually leads to the final pair of products H+AlCH{sub 3} and HAl+CH{sub 3}.

  8. Enhanced microbial coalbed methane generation: A review of research, commercial activity, and remaining challenges

    USGS Publications Warehouse

    Ritter, Daniel J.; Vinson, David S.; Barnhart, Elliott P.; Akob, Denise M.; Fields, Matthew W.; Cunningham, Al B.; Orem, William H.; McIntosh, Jennifer C.

    2015-01-01

    Coalbed methane (CBM) makes up a significant portion of the world’s natural gas resources. The discovery that approximately 20% of natural gas is microbial in origin has led to interest in microbially enhanced CBM (MECoM), which involves stimulating microorganisms to produce additional CBM from existing production wells. This paper reviews current laboratory and field research on understanding processes and reservoir conditions which are essential for microbial CBM generation, the progress of efforts to stimulate microbial methane generation in coal beds, and key remaining knowledge gaps. Research has been primarily focused on identifying microbial communities present in areas of CBM generation and attempting to determine their function, in-situ reservoir conditions that are most favorable for microbial CBM generation, and geochemical indicators of metabolic pathways of methanogenesis (i.e., acetoclastic or hydrogenotrophic methanogenesis). Meanwhile, researchers at universities, government agencies, and companies have focused on four primary MECoM strategies: 1) microbial stimulation (i.e., addition of nutrients to stimulate native microbes); 2) microbial augmentation (i.e., addition of microbes not native to or abundant in the reservoir of interest); 3) physically increasing microbial access to coal and distribution of amendments; and 4) chemically increasing the bioavailability of coal organics. Most companies interested in MECoM have pursued microbial stimulation: Luca Technologies, Inc., successfully completed a pilot scale field test of their stimulation strategy, while two others, Ciris Energy and Next Fuel, Inc., have undertaken smaller scale field tests. Several key knowledge gaps remain that need to be addressed before MECoM strategies can be implemented commercially. Little is known about the bacterial community responsible for coal biodegradation and how these microorganisms may be stimulated to enhance microbial methanogenesis. In addition, research

  9. Starting motor

    SciTech Connect

    Tanaka, T.; Hamano, I

    1989-05-23

    This patent describes a starting motor having a housing, planetary reduction gears including an internal gear in the housing. The improvement consists of an elastic member having a first annular portion mounted in engagement with a fixed annular member of the housing and a plurality of protruding axially extending elastic portions providing a corrugated surface pressed into engagement with an end portion of the internal gear, the elastic member being sandwiched between the internal gear and the housing member, the protruding axially extending elastic portions providing resilient means which flex and incline circumferentially under turning force from the internal gear and exert reactive thrust on the internal gear elastically so that the frictional force at the abutting surfaces of the protruding portions holds the internal gear in resilient engagement with the elastic member and the resilient means acts as a buffer to absorb rotary impact force developing in the planetary reduction gears.

  10. Direct catalytic conversion of methane and light hydrocarbon gases. Quarterly report No. 5, November 16, 1987--January 15, 1988

    SciTech Connect

    Wilson, R.B. Jr.; Chan Yee Wai

    1988-02-05

    The goal of this research is to develop catalysts that directly convert methane and light hydrocarbons to intermediates that later can be converted to either liquid fuels or value-added chemicals, as economics dictate. During this reporting period, we have synthesized and tested several novel catalysts for methane reforming (Tasks 1 and 2) and for partial oxidation of methane (Tasks 3 and 4). We started to test a mixed metal system, an FeRu{sub 3} cluster. This catalyst was supported both on zeolite and on magnesium oxide and the systems were tested for methane reforming at various reaction temperatures. We also prepared and tested a monomeric ruthenium catalyst supported on magnesium oxide. We found that methane is activated at a lower temperature with the basic magnesium oxide support than with acidic supports such as zeolite or alumina. Methane conversions increased with temperature, but the production of coke also increased. We prepared a sterically hindered ruthenium porphyrin encapsulated in a zeolite supercage for catalysis of methane oxidation. The results showed that only carbon dioxide was produced. Addition of axial base to this catalyst gave similar results. Another type of catalyst, cobalt Schiff base complexes, was also prepared and tested for methane oxidation. In this case, no methane conversion was observed at temperatures ranging from 200 to 450{degrees}C. These complexes do not appear to be stable under the reaction conditions.

  11. Linking activity, composition and seasonal dynamics of atmospheric methane oxidizers in a meadow soil

    PubMed Central

    Shrestha, Pravin Malla; Kammann, Claudia; Lenhart, Katharina; Dam, Bomba; Liesack, Werner

    2012-01-01

    Microbial oxidation is the only biological sink for atmospheric methane. We assessed seasonal changes in atmospheric methane oxidation and the underlying methanotrophic communities in grassland near Giessen (Germany), along a soil moisture gradient. Soil samples were taken from the surface layer (0–10 cm) of three sites in August 2007, November 2007, February 2008 and May 2008. The sites showed seasonal differences in hydrological parameters. Net uptake rates varied seasonally between 0 and 70 μg CH4 m−2 h−1. Greatest uptake rates coincided with lowest soil moisture in spring and summer. Over all sites and seasons, the methanotrophic communities were dominated by uncultivated methanotrophs. These formed a monophyletic cluster defined by the RA14, MHP and JR1 clades, referred to as upland soil cluster alphaproteobacteria (USCα)-like group. The copy numbers of pmoA genes ranged between 3.8 × 105–1.9 × 106 copies g−1 of soil. Temperature was positively correlated with CH4 uptake rates (P<0.001), but had no effect on methanotrophic population dynamics. The soil moisture was negatively correlated with CH4 uptake rates (P<0.001), but showed a positive correlation with changes in USCα-like diversity (P<0.001) and pmoA gene abundance (P<0.05). These were greatest at low net CH4 uptake rates during winter times and coincided with an overall increase in bacterial 16S rRNA gene abundances (P<0.05). Taken together, soil moisture had a significant but opposed effect on CH4 uptake rates and methanotrophic population dynamics, the latter being increasingly stimulated by soil moisture contents >50 vol% and primarily related to members of the MHP clade. PMID:22189499

  12. Breaking methane

    PubMed Central

    Rosenzweig, Amy C.

    2015-01-01

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

  13. Harnessing methane

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

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

  14. Activation of C-H bond in methane by Pd atom from the bonding evolution theory perspective.

    PubMed

    Nizovtsev, Anton S

    2013-08-15

    We report detailed study focused on the electron density redistribution during the simple oxidative addition reaction being the crucial stage of various catalytic processes. The bonding evolution theory based on the electron localization function and Thom's catastrophe theory shows that activation of methane's C-H bond by Pd atom consist of six elementary steps. The important feature revealed is the pronounced reorganization of Pd's outer core maxima corresponding to N-shell electrons of metal. Electronic rearrangements identified in this model reaction are likely to be the case in the more complex reactions of the same type involving transition metal compounds and, in principle, can be observed by modern ultrafast spectroscopy and diffraction techniques.

  15. The Hansenula polymorpha MOX gene presents two alternative transcription start points differentially utilized and sensitive to respiratory activity.

    PubMed

    Genu, Victor; Gödecke, Stefanie; Hollenberg, Cornelis P; Pereira, Gonçalo G

    2003-06-01

    The peroxisomal methanol metabolism of Hansenula polymorpha depends on a group of genes that are coordinately regulated. Methanol oxidase (Mox) plays a key role in this pathway and its synthesis has been shown to be regulated at the transcriptional level. MOX expression is strongly repressed on glucose and activated on glycerol or methanol. In this study we have identified two MOX transcripts that are differentially expressed along MOX derepression. The first one, named l-MOX (for longer MOX), starts at position -425, is only weakly and transiently transcribed and is not translated into the Mox protein. The other is the true MOX mRNA, which initiates around position -25. Using a strain bearing multiple copies of MOX(Q1N) and a reporter gene fused to the MOX promoter, regulation of the two transcripts was investigated. Initiation of the true MOX correlates with repression of l-MOX and conditions that are repressive for MOX transcription, such as the inhibition of mitochondrial activity, lead to higher levels of l-MOX expression. This effect was first observed in a mox mutant (Q1N-M8) unable to grow on nonfermentable carbon sources. No function was detected for l-MOX, but its regulation follows a pattern similar to that of catalase, which is essential for methanol metabolism. This suggests that, l-MOX, although precisely regulated, seems to be a remnant of the evolution of the methanol metabolism network.

  16. Methanobactin from Methylocystis sp. strain SB2 affects gene expression and methane monooxygenase activity in Methylosinus trichosporium OB3b.

    PubMed

    Farhan Ul-Haque, Muhammad; Kalidass, Bhagyalakshmi; Vorobev, Alexey; Baral, Bipin S; DiSpirito, Alan A; Semrau, Jeremy D

    2015-04-01

    Methanotrophs can express a cytoplasmic (soluble) methane monooxygenase (sMMO) or membrane-bound (particulate) methane monooxygenase (pMMO). Expression of these MMOs is strongly regulated by the availability of copper. Many methanotrophs have been found to synthesize a novel compound, methanobactin (Mb), that is responsible for the uptake of copper, and methanobactin produced by Methylosinus trichosporium OB3b plays a key role in controlling expression of MMO genes in this strain. As all known forms of methanobactin are structurally similar, it was hypothesized that methanobactin from one methanotroph may alter gene expression in another. When Methylosinus trichosporium OB3b was grown in the presence of 1 μM CuCl2, expression of mmoX, encoding a subunit of the hydroxylase component of sMMO, was very low. mmoX expression increased, however, when methanobactin from Methylocystis sp. strain SB2 (SB2-Mb) was added, as did whole-cell sMMO activity, but there was no significant change in the amount of copper associated with M. trichosporium OB3b. If M. trichosporium OB3b was grown in the absence of CuCl2, the mmoX expression level was high but decreased by several orders of magnitude if copper prebound to SB2-Mb (Cu-SB2-Mb) was added, and biomass-associated copper was increased. Exposure of Methylosinus trichosporium OB3b to SB2-Mb had no effect on expression of mbnA, encoding the polypeptide precursor of methanobactin in either the presence or absence of CuCl2. mbnA expression, however, was reduced when Cu-SB2-Mb was added in both the absence and presence of CuCl2. These data suggest that methanobactin acts as a general signaling molecule in methanotrophs and that methanobactin "piracy" may be commonplace.

  17. Estimation of past intermittent methane seep activity using radiocarbon dating of Calyptogena shells in the eastern Nankai subduction zone

    NASA Astrophysics Data System (ADS)

    Yagasaki, K.; Ashi, J.; Yokoyama, Y.; Miyairi, Y.; Kuramoto, S.

    2013-12-01

    Radioisotope carbon dating samples from the deep ocean has always been a difficult phenomenon due to the carbon offset present. This research presents a way of utilizing such method to date shell samples in order to study past fault activities. The research presented will be based on the preliminary data collected thus far. The Nankai and the Tokai regions are common areas for cold seeps, where seepage of hydrogen sulfide and methane rich fluid occurs. These various substances encourage the growth of Calyptogena colonies to flourish at these sites. Cold seeps generally occur at tectonically active continental margins and are mostly ephemeral. This suggests that the cold seep events are possibly influenced by the tectonic activity during the plate divergence. In 1997, a submersible dive by Shinkai 2000 discovered an unusually large Calyptogena colony ranging over 200 m2 off Daini Tenryu Knoll. Majority of the shells were fossilized with few live shells remaining. It is assumed that past tectonic events in the region may have caused a high flux of methane fluid or gas to be released, making it possible to support such a vast scale colony to survive until their eventual death. Previous attempt to reconstruct the cold seep activity history through amino acid racemisation dating revealed two different age grouped shells. Further data using a different method is required to prove its reliability, as acid racemization dating technique can easily be affected by seawater temperature changes and microbial activity. This consequently alters the protein structure of the sample and its overall age. As 14C radioisotope dating is not affected by temperature change, it will provide additional information to the accuracy of the acid racemisation dating of the shell. However, the possibility of contamination is likely due to the shells incorporating older carbon from the sediments during their early stages of growth. The old carbon value can be calculated by subtracting the formerly

  18. Mothers’ perceptions of the UK physical activity and sedentary behaviour guidelines for the early years (Start Active, Stay Active): a qualitative study

    PubMed Central

    Bentley, Georgina F; Jago, Russell; Turner, Katrina M

    2015-01-01

    Objectives Higher levels of physical activity (PA) during early childhood have been associated with improved health outcomes, whereas sedentary behaviour (SB) has been associated with poorer health outcomes in children. In 2011, the UK produced guidelines for PA and SB in children under 5 years. Mothers have been identified as key influences in young children's PA and SB. The aim of this study was to use in-depth interviews with mothers of preschool children to examine attitudes to the guidance. Design Qualitative study using one-to-one, semistructured interviews; Data were analysed thematically using a framework approach. Setting Mothers were recruited from preschools, nurseries, and mother and toddler groups located in four areas of varying socioeconomic status within Bristol, UK. Participants 24 mothers who were considered the main or joint carer for a preschool child who was at least 2 years of age but had not yet started formal schooling. Results Mothers are not aware of the UK PA and SB guidelines for the early years. They believe that their child achieves the guideline targets for PA and SB and therefore, they do not believe these quidelines are relevant to them. Mothers feel that an increase in PA and reduction in SB (especially screen-viewing) would cause stress for mothers. Mothers found defining and quantifying PA and SB in their preschool child problematic. Conclusions As mothers do not identify with the need to increase PA or reduce SB in their child, awareness of the guidelines alone is unlikely to initiate behaviour change. Information on how mothers can make a more accurate assessment of their preschool child's PA and SB levels, and information about the benefits of increased PA and reduced SB should be provided alongside the guideline targets. Clear messages need to be developed that reframe the guidelines into pragmatic and usable targets. PMID:26351186

  19. The anti-tumor drug bleomycin preferentially cleaves at the transcription start sites of actively transcribed genes in human cells.

    PubMed

    Murray, Vincent; Chen, Jon K; Galea, Anne M

    2014-04-01

    The genome-wide pattern of DNA cleavage at transcription start sites (TSSs) for the anti-tumor drug bleomycin was examined in human HeLa cells using next-generation DNA sequencing. It was found that actively transcribed genes were preferentially cleaved compared with non-transcribed genes. The 143,600 identified human TSSs were split into non-transcribed genes (82,596) and transcribed genes (61,004) for HeLa cells. These transcribed genes were further split into quintiles of 12,201 genes comprising the top 20, 20-40, 40-60, 60-80, and 80-100 % of expressed genes. The bleomycin cleavage pattern at highly transcribed gene TSSs was greatly enhanced compared with purified DNA and non-transcribed gene TSSs. The top 20 and 20-40 % quintiles had a very similar enhanced cleavage pattern, the 40-60 % quintile was intermediate, while the 60-80 and 80-100 % quintiles were close to the non-transcribed and purified DNA profiles. The pattern of bleomycin enhanced cleavage had peaks that were approximately 200 bp apart, and this indicated that bleomycin was identifying the presence of phased nucleosomes at TSSs. Hence bleomycin can be utilized to detect chromatin structures that are present at actively transcribed genes. In this study, for the first time, the pattern of DNA damage by a clinically utilized cancer chemotherapeutic agent was performed on a human genome-wide scale at the nucleotide level.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  1. Effects of the Start For Life treatment on physical activity in primarily African American preschool children of ages 3-5 years.

    PubMed

    Annesi, James J; Smith, Alice E; Tennant, Gisèle A

    2013-01-01

    In U.S. children of ages 2-5 years, combined overweight and obesity has increased to 21%, with African American children of this age range highest at 26%. Lack of physical activity is highly predictive of overweight and obesity in children. Preschools may be a useful point for intervention. An innovative preschool physical activity treatment (Start For Life) was developed based on principles of social cognitive and self-efficacy theory. It incorporated 30 minutes daily of highly structured physical activity with behavioral and self-regulatory skills training (e.g. goal setting, self-monitoring, productive self-talk) interspersed. Data obtained from accelerometry was used to contrast physical activity outputs during the preschool day in the Start For Life condition (n = 202) with a usual-care control condition (n = 136). After controlling for age and sex of the primarily African American participants (M age = 4.7 years), changes over eight weeks in moderate-to-vigorous and vigorous physical activity were significant, and significantly more favorable in the Start For Life group; F(1, 344) = 4.98, p = .026 and F(1, 344) = 3.60, p = .058, respectively. Start For Life was associated with a weekly increase in moderate-to-vigorous physical activity of approximately 40 minutes. After sufficient replications that better account for different sample types, parental effects and physical activity outside of the school day, and long-term effects, widespread dissemination may be considered.

  2. Assessing the role of spatial structure on cell-specific activity and interactions within uncultured methane-oxidizing syntrophic consortia (Invited)

    NASA Astrophysics Data System (ADS)

    Orphan, V. J.; McGlynn, S.; Chadwick, G.; Dekas, A.; Green-Saxena, A.

    2013-12-01

    Sulfate-coupled anaerobic oxidation of methane is catalysed through symbiotic associations between archaea and sulphate-reducing bacteria and represents the dominant sink for methane in the oceans. These methane-oxidizing symbiotic consortia form well-structured multi-celled aggregations in marine methane seeps, where close spatial proximity is believed to be essential for efficient exchange of substrates between syntrophic partners. The nature of this interspecies metabolic relationship is still unknown however there are a number of hypotheses regarding the electron carrying intermediate and ecophysiology of the partners, each of which should be affected by, and influence, the spatial arrangement of archaeal and bacterial cells within aggregates. To advance our understanding of the role of spatial structure within naturally occurring environmental consortia, we are using spatial statistical methods combined with fluorescence in situ hybridization and high-resolution nanoscale secondary ion mass spectrometry (FISH-nanoSIMS) to quantify the effect of spatial organization and intra- and inter-species interactions on cell-specific microbial activity within these diverse archaeal-bacterial partnerships.

  3. Co-digestion of molasses or kitchen waste with high-rate activated sludge results in a diverse microbial community with stable methane production.

    PubMed

    De Vrieze, Jo; Plovie, Kristof; Verstraete, Willy; Boon, Nico

    2015-04-01

    Kitchen waste and molasses are organic waste streams with high organic content, and therefore are interesting substrates for renewable energy production by means of anaerobic digestion. Both substrates, however, often cause inhibition of the anaerobic digestion process, when treated separately, hence, co-digestion with other substrates is required to ensure stable methane production. In this research, A-sludge (sludge harvested from a high rate activated sludge system) was used to stabilize co-digestion with kitchen waste or molasses. Lab-scale digesters were fed with A-sludge and kitchen waste or molasses for a total period of 105 days. Increased methane production values revealed a stabilizing effect of concentrated A-sludge on kitchen waste digestion. Co-digestion of molasses with A-sludge also resulted in a higher methane production. Volumetric methane production rates up to 1.53 L L(-1) d(-1) for kitchen waste and 1.01 L L(-1) d(-1) for molasses were obtained by co-digestion with A-sludge. The stabilizing effect of A-sludge was attributed to its capacity to supplement various nutrients. Microbial community results demonstrated that both reactor conditions and substrate composition determined the nature of the bacterial community, although there was no direct influence of micro-organisms in the substrate itself, while the methanogenic community profile remained constant as long as optimal conditions were maintained.

  4. Landfill Methane

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  5. Hudson Canyon Offshore New York and New Jersey: Active Circular Depressions, Fans, Ravines, Methane Discharge and Water Masses

    NASA Astrophysics Data System (ADS)

    Rona, P. A.; Guida, V.; Scranton, M. I.; Gong, D.; Haag, S.; Macelloni, L.; Simonetti, A.; James, J.; Diercks, A.; Asper, V. L.

    2009-12-01

    We investigated Hudson Canyon from where it begins at the seaward edge of the continental shelf (water depth 100 m) to ~30 km seaward (100-700 m) using high-resolution bathymetry (AUV Eagle Ray; ISE Explorer; EM2000 sonar) and standard oceanographic methods. We find features and processes that create varied distinctive habitats in submarine canyons on passive continental margins, as follows: 1)Sediment conduit: The initial 10 km- long section of the canyon head connects with cross-shelf sediment transport and is smoothed by sediment accumulation indicating that it is presently inactive as a sediment conduit, in contrast to its active role during prior intervals of lowered sea level. 2)Circular depressions: A population of circular depressions with diameters from 50 to 400 m, rim-to-floor relief up to 20 m increasing directly with diameter, flat rough floors and steep walls (15-25 degrees) occur in sediment near the base of both walls of the canyon. The number of circular depressions increases with water depth with one at 325 m in the initial 10 km-long NW-SE section of the canyon, two at 350 m in the next 10 km N-S section, and nineteen at 300 to 500 m at the SW wall of the next 10 km NW-SE section. The sharp shape of the depressions suggests that they are actively forming. Larger circular depressions (diameter <800 m) exhibit different characteristics. 3)Methane chemistry: A methane anomaly (50 nmol) ten times background was measured in August 2008 in the near-bottom water column adjacent to one of the two circular depressions in the middle canyon section. In August 2009 water samples were recovered at other circular depressions and are being analyzed to test for methane discharge. We suggest that the circular depressions are gas release-collapse features possibly produced by dissociation of underlying gas hydrates. 4)Fans and ravines: Sediment fans with intervening ravines about 1 km apart extend orthogonal to the canyon axis down the two walls of the canyon in

  6. A pathway in the yeast cell division cycle linking protein kinase C (Pkc1) to activation of Cdc28 at START.

    PubMed Central

    Marini, N J; Meldrum, E; Buehrer, B; Hubberstey, A V; Stone, D E; Traynor-Kaplan, A; Reed, S I

    1996-01-01

    In an effort to study further the mechanism of Cdc28 function and cell cycle commitment, we describe here a genetic approach to identify components of pathways downstream of the Cdc28 kinase at START by screening for mutations that decrease the effectiveness of signaling by Cdc28. The first locus to be characterized in detail using this approach was PKC1 which encodes a homolog of the Ca(2+)-dependent isozymes of the mammalian protein kinase C (PKC) superfamily (Levin et al., 1990). By several genetic criteria, we show a functional interaction between CDC28 and PKC1 with PKC1 apparently functioning with respect to bud emergence downstream of START. Consistent with this, activity of the MAP kinase homolog Mpk1 (a putative Pkc1 effector) is stimulated by activation of Cdc28. Furthermore, we demonstrate a cell cycle-dependent hydrolysis of phosphatidylcholine to diacylglycerol (a PKC activator) and choline phosphate at START. Diacylglycerol production is stimulated by Cdc28 in cycling cells and is closely associated with Cdc28 activation at START. These results imply that the activation of Pkc1, which is known to be necessary during bud morphogenesis, is mediated via the CDC28-dependent stimulation of PC-PLC activity in a novel cell cycle-regulated signaling pathway. Images PMID:8670805

  7. Hydroxylation of methane through component interactions in soluble methane monooxygenases.

    PubMed

    Lee, Seung Jae

    2016-04-01

    Methane hydroxylation through methane monooxygenases (MMOs) is a key aspect due to their control of the carbon cycle in the ecology system and recent applications of methane gas in the field of bioenergy and bioremediation. Methanotropic bacteria perform a specific microbial conversion from methane, one of the most stable carbon compounds, to methanol through elaborate mechanisms. MMOs express particulate methane monooxygenase (pMMO) in most strains and soluble methane monooxygenase (sMMO) under copper-limited conditions. The mechanisms of MMO have been widely studied from sMMO belonging to the bacterial multicomponent monooxygenase (BMM) superfamily. This enzyme has diiron active sites where different types of hydrocarbons are oxidized through orchestrated hydroxylase, regulatory and reductase components for precise control of hydrocarbons, oxygen, protons, and electrons. Recent advances in biophysical studies, including structural and enzymatic achievements for sMMO, have explained component interactions, substrate pathways, and intermediates of sMMO. In this account, oxidation of methane in sMMO is discussed with recent progress that is critical for understanding the microbial applications of C-H activation in one-carbon substrates.

  8. Ruminant methane reduction through livestock development in Tanzania. Final report for US Department of Energy and US Initiative on Joint Implementation--Activities Implemented Jointly

    SciTech Connect

    Livingston, Roderick

    1999-07-01

    This project was designed to help develop the US Initiative on Joint Implementation activities in Eastern Africa. It has been communicated in meetings with representatives from the Ministry of Environment of Tanzania and the consultant group that developed Tanzania's National Climate Change Action Plan, the Centre for Energy, Environment, Science and Technology, that this project fits very well with the developmental and environmental goals of the Government of Tanzania. The goal of the Activities Implemented Jointly ruminant livestock project is to reduce ruminant methane emissions in Eastern Africa. The project plans a sustainable cattle multiplication unit (CMU) at Mabuki Ranch in the Mwanza Region of Tanzania. This CMU will focus on raising genetically improved animals to be purchased by farmers, developmental organizations, and other CMUs in Tanzania. Through the purchase of these animals farmers will raise their income generation potential and reduce ruminant methane emissions.

  9. Progress in Synthesis of Highly Active and Stable Nickel-Based Catalysts for Carbon Dioxide Reforming of Methane.

    PubMed

    Kawi, Sibudjing; Kathiraser, Yasotha; Ni, Jun; Oemar, Usman; Li, Ziwei; Saw, Eng Toon

    2015-11-01

    In recent decades, rising anthropogenic greenhouse gas emissions (mainly CO2 and CH4 ) have increased alarm due to escalating effects of global warming. The dry carbon dioxide reforming of methane (DRM) reaction is a sustainable way to utilize these notorious greenhouse gases. This paper presents a review of recent progress in the development of nickel-based catalysts for the DRM reaction. The enviable low cost and wide availability of nickel compared with noble metals is the main reason for persistent research efforts in optimizing the synthesis of nickel-based catalysts. Important catalyst features for the rational design of a coke-resistant nickel-based nanocatalyst for the DRM reaction are also discussed. In addition, several innovative developments based on salient features for the stabilization of nickel nanocatalysts through various means (which include functionalization with precursors, synthesis by plasma treatment, stabilization/confinement on mesoporous/microporous/carbon supports, and the formation of metal oxides) are highlighted. The final part of this review covers major issues and proposed improvement strategies pertaining to the rational design of nickel-based catalysts with high activity and stability for the DRM reaction.

  10. Anticancer activity of synthetic bis(indolyl)methane-ortho-biaryls against human cervical cancer (HeLa) cells.

    PubMed

    Jamsheena, Vellekkatt; Shilpa, Ganesan; Saranya, Jayaram; Harry, Nissy Ann; Lankalapalli, Ravi Shankar; Priya, Sulochana

    2016-03-05

    Bis(indolyl)methane appended biaryls were designed, synthesized and evaluated in human cervical cancer cell lines (HeLa) for their anticancer activities and compared against normal rat cardiac myoblasts (H9C2) cells. Compounds 1-12 were synthesized, with variations in one of the phenyl unit, in a single step by condensation of biaryl-2-carbaldehydes with indole in the presence of para-toluenesulfonic acid. Compound 1 exhibited a GI50 value of 11.00 ± 0.707 μM and the derivatives, compounds 4 and 11 showed a GI50 value of 8.33 ± 0.416 μM and 9.13 ± 0.177 μM respectively in HeLa cells and was found to be non-toxic to H9C2 cells up to 20 μM. Furthermore, compounds 1, 4 and 11 induced caspase dependent cellular apoptosis in a concentration-dependent manner, reduced mitochondrial membrane potential, inhibited the cell migration and downregulated the production of MMP-2 and MMP-9 in HeLa cells.

  11. Behavior Problems in Learning Activities and Social Interactions in Head Start Classrooms and Early Reading, Mathematics, and Approaches to Learning

    ERIC Educational Resources Information Center

    Bulotsky-Shearer, Rebecca J.; Fernandez, Veronica; Dominguez, Ximena; Rouse, Heather L.

    2011-01-01

    Relations between early problem behavior in preschool classrooms and a comprehensive set of school readiness outcomes were examined for a stratified random sample (N = 256) of 4-year-old children enrolled in a large, urban school district Head Start program. A series of multilevel models examined the unique contribution of early problem behavior…

  12. Barriers and Facilitators to Healthy Eating and Activity in Head Start Staff: An Opportunity for Worksite Wellness

    ERIC Educational Resources Information Center

    Hibbs-Shipp, Sarah K.; Milholland, Michelle; Bellows, Laura

    2015-01-01

    Background: Head Start (HS) staff are ideally positioned to promote healthy behaviors to over one million low-income children each year, however little is understood about their own health. Purpose: To conduct a needs assessment with HS staff to: 1) understand perceptions, barriers and motivators to healthful behaviors; and 2) ascertain interest…

  13. Examining the Content of Head Start Teachers' Literacy Instruction within Two Activity Contexts during Large-Group Circle Time

    ERIC Educational Resources Information Center

    Zhang, Chenyi; Diamond, Karen E.; Powell, Douglas R.

    2015-01-01

    Large-group circle time is an important component of many preschool classrooms' daily schedules. This study scrutinized the teaching content of Head Start teachers' literacy instruction (i.e., the types of literacy concept embedded within the instruction, lexical characteristics of teachers' talk, and elaborations on literacy knowledge) in two…

  14. Home Start Curriculum Guide.

    ERIC Educational Resources Information Center

    Roggman, Lori; And Others

    This curriculum guide contains monthly work plans and weekly activity units for a Home Start Program. Emphasis is placed on the importance of the home, the family unit, and the education and development of young children by their own parents. Yearly goals include concern for the following: physical and dental health, nutrition, mental health and…

  15. Exploring Daily Physical Activity and Nutrition Patterns in Early Learning Settings: Snapshots of Young Children in Head Start, Primary, and After-School Settings

    ERIC Educational Resources Information Center

    Stegelin, Dolores A.; Anderson, Denise; Kemper, Karen; Wagner, Jennifer; Evans, Katharine

    2014-01-01

    The purpose of this research project was to gain a greater understanding of daily routines of 4-7 year olds regarding physical activity and nutrition practices in typical early learning environments. The settings selected for this observational study included Head Start, primary, and after-school learning environments in a city in the southeast.…

  16. Methane Uptake in Forest Soils is Driven by Diffusivity and Methane Oxidizer Community Size

    NASA Astrophysics Data System (ADS)

    Sullivan, B. W.; Hart, S. C.; Kolb, T. E.

    2008-12-01

    Upland forest soils are the only known terrestrial biological sink of methane, but the mechanisms controlling methane uptake are poorly understood. Methane uptake is the result of bacterial and archaeal 'methane oxidizer' activity. Temperature, water content, and substrate availability have all been described as potential mechanisms governing methane uptake in soils. We measured methane uptake in soil across two ecological different gradients in an attempt to determine controls on methane uptake in semi-arid soils. We measured the uptake of atmospheric methane in situ across a gradient of northern Arizona, USA ponderosa pine forest disturbance. This gradient included an unthinned, unburned forest, a mechanically thinned forest, and a former forest site that completely burned 10 years prior to measurements. In laboratory incubations, we measured potential methane uptake across a soil chronosequence of basalt-cinder derived soils from 0.001 to 3 million years old by exposing soils to 10x ambient levels of methane. This chronosequence has a gradient of soil texture, which will influence the air filled pore space, and consequently methane diffusion. Both gradients experience distinct dry and wet seasons during the growing season. Our field measurements suggest that methane uptake is greatest when the forest floor is thinnest and the soil is most dry. Our laboratory incubations suggest that, during the dry season, potential methane uptake is driven by diffusion, but that during the wet season potential methane uptake is a function of methane oxidizer community size. Methane uptake patterns across both gradients demonstrates the importance of diffusion and methane oxidizer community size as codominant controlling factors.

  17. Studies of the Active Sites for Methane Dehydroaromatization Using Ultrahigh-Field Solid-State Mo95 NMR Spectroscopy

    SciTech Connect

    Hu, Jian Z.; Kwak, Ja Hun; Wang, Yong; Peden, Charles HF; Zheng, Heng; Ma, Ding; Bao, Xinhe

    2009-01-26

    Abstract It is found that the spin-lattice relaxation time, T1, corresponding to the surface exchanged molybdenum species in Mo/HZSM-5 catalysts is short, i.e., less than about 100ms at 21.1 T while the value of T1 for the crystallite MoO3 molecules is longer, i.e., about 30 s. Such a difference, more than two orders in magnitude, is utilized to differentiate the exchanged Mo species from the agglomerate MoO3 in Mo/HZSM-5 catalyst. An approximately linear correlation between the amount of exchanged species and the aromatics formation rate is obtained. This result significantly strengthens our prior conclusion that the exchanged Mo species are the active centers for the methane dehydroaromatization reaction on Mo/HZSM-5 catalysts (J. Am. Chem. Soc. 2008, 130, 3722-3723). Our results also suggest that one exchanged Mo atom anchors on two ion exchange sites and the exchanged Mo species on catalysts are possibly monomeric. Analyzing the linshapes obtained from both the 95Mo MAS and the static spectra indicates that the exchanged sites are heterogeneous, resulting in a significantly broadened MAS spectrum and essentially a featureless but nearly symmetric static lineshape for the exchanged Mo species. Furthermore, for crystallite MoO3 powder sample, the parameters related to the electric-field-gradient (EFG) tensor, the chemical shift anisotropy (CSA) and the three Euler angles required to align the CSA principal axis system with the quadrupolar principal axis system are determined by analyzing both the 95Mo MAS and the static spectra obtained at ultra-high field of 21.1 T. The new results obtained from this study on crystallite MoO3 powders should help to clarify some of the contradictions in prior literature reports from other groups. Key words: 95Mo NMR, MAS, relaxation, surface exchanged species, HZSM-5, electric-field-gradient (EFG), chemical shift anisotropy (CSA), active centers.

  18. Mars Express confirms methane in the Martian atmosphere

    NASA Astrophysics Data System (ADS)

    2004-03-01

    From the time of its arrival at Mars, the Mars Express spacecraft started producing stunning results. One of the aims of the mission is analysing in detail the chemical composition of the Martian atmosphere, known to consist of 95% percent carbon dioxide plus 5% of minor constituents. It is also from these minor constituents, which scientists expect to be oxygen, water, carbon monoxide, formaldehyde and methane, that we may get important information on the evolution of the planet and possible implications for the presence of past or present life. The presence of methane has been confirmed thanks to the observations of the Planetary Fourier Spectrometer (PFS) on board Mars Express during the past few weeks. This instrument is able to detect the presence of particular molecules by analysing their 'spectral fingerprints' - the specific way each molecule absorbs the sunlight it receives. The measurements confirm so far that the amount of methane is very small - about 10 parts in a thousand million, so its production process is probably small. However, the exciting question remains: "Where does this methane come from?" Methane, unless it is continuously produced by a source, only survives in the Martian atmosphere for a few hundreds of years because it quickly oxidises to form water and carbon dioxide, both present in the Martian atmosphere. So, there must be a mechanism that refills the atmosphere with methane. “The first thing to understand is how exactly the methane is distributed in the Martian atmosphere,” says Vittorio Formisano, Principal Investigator for the PFS instrument. “Since the methane presence is so small, we need to take more measurements. Only then will we have enough data to make a statistical analysis and understand whether there are regions of the atmosphere where methane is more concentrated.” Once this is done, scientists will try to establish a link between the planet-wide distribution of methane and possible atmospheric or surface

  19. Catalytic activity of mono and bimetallic Zn/Cu/MWCNTs catalysts for the thermocatalyzed conversion of methane to hydrogen

    NASA Astrophysics Data System (ADS)

    Erdelyi, B.; Oriňak, A.; Oriňaková, R.; Lorinčík, J.; Jerigová, M.; Velič, D.; Mičušík, M.; Omastová, M.; Smith, R. M.; Girman, V.

    2017-02-01

    Mono and bimetallic multiwalled carbon nanotubes (MWCNTs) fortified with Cu and Zn metal particles were studied to improve the efficiency of the thermocatalytic conversion of methane to hydrogen. The surface of the catalyst and the dispersion of the metal particles were studied by scanning electron microscopy (SEM), secondary ion mass spectrometry (SIMS) and with energy-dispersive X-ray spectroscopy (EDS). It was confirmed that the metal particles were successfully dispersed on the MWCNT surface and XPS analysis showed that the Zn was oxidised to ZnO at high temperatures. The conversion of methane to hydrogen during the catalytic pyrolysis was studied by pyrolysis gas chromatography using different amounts of catalyst. The best yields of hydrogen were obtained using pyrolysis conditions of 900 °C and 1.2 mg of Zn/Cu/MWCNT catalyst for 1.5 mL of methane.The initial conversion of methane to hydrogen obtained with Zn/Cu/MWCNTs was 49%, which represent a good conversion rate of methane to hydrogen for a non-noble metal catalyst.

  20. Influence of the presence of ruthenium on the activity and stability of Co-Mg-Al-based catalysts in CO2 reforming of methane for syngas production.

    PubMed

    Gennequin, Cédric; Hany, Sara; Tidahy, Haingomalala Lucette; Aouad, Samer; Estephane, Jane; Aboukaïs, Antoine; Abi-Aad, Edmond

    2016-11-01

    Hydrogen production by methane dry reforming is an important yet challenging process. A performing catalyst will favor the thermodynamic equilibrium while ensuring good hydrogen selectivity. We hereby report the synthesis of Co x Mg6-x Al2 (with x = 2 and 6) mixed oxide catalysts synthesized via hydrotalcite precursors and the synthesis of a ruthenium-based catalyst on a cobalt, magnesium, and aluminum mixed oxide supports Ru/Co x Mg6-x Al2 (with x = 2 and 6). The impregnation of ruthenium on the hydrotalcites was performed in two ways: by impregnation on the dried hydrotalcite and by memory effect on hydrotalcite calcined at 500 °C. The deposition of ruthenium by memory effect of the magnesium and cobalt support allows the generation of both metallic and basic sites which provides an active and stable catalyst for the dry reforming reaction of methane.

  1. METHANE: INDUSTRIAL SOURCES

    EPA Science Inventory

    The chapter provides qualitative information on the magnitude of industrial sources of methane and, where possible, provides information to allow the reader to quantify methane emissions. One difficulty in quantifying methane emissions from industry is the inconsistent treatment ...

  2. A [Cu2O]2+ core in Cu-ZSM-5, the active site in the oxidation of methane to methanol

    PubMed Central

    Woertink, Julia S.; Smeets, Pieter J.; Groothaert, Marijke H.; Vance, Michael A.; Sels, Bert F.; Schoonheydt, Robert A.; Solomon, Edward I.

    2009-01-01

    Driven by the depletion of crude oil, the direct oxidation of methane to methanol has been of considerable interest. Promising low-temperature activity of an oxygen-activated zeolite, Cu-ZSM-5, has recently been reported in this selective oxidation and the active site in this reaction correlates with an absorption feature at 22,700 cm−1. In the present study, this absorption band is used to selectively resonance enhance Raman vibrations of this active site. 18O2 labeling experiments allow definitive assignment of the observed vibrations and exclude all previously characterized copper-oxygen species for the active site. In combination with DFT and normal coordinate analysis calculations, the oxygen activated Cu core is uniquely defined as a bent mono-(μ-oxo)dicupric site. Spectroscopically validated electronic structure calculations show polarization of the low-lying singly-occupied molecular orbital of the [Cu2O]2+ core, which is directed into the zeolite channel, upon approach of CH4. This induces significant oxyl character into the bridging O atom leading to a low transition state energy consistent with experiment and explains why the bent mono-(μ-oxo)dicupric core is highly activated for H atom abstraction from CH4. The oxygen intermediate of Cu-ZSM-5 is now the most well defined species active in the methane monooxygenase reaction. PMID:19864626

  3. [Copper in methane oxidation: a review].

    PubMed

    Su, Yao; Kong, Jiao-Yan; Zhang, Xuan; Xia, Fang-Fang; He, Ruo

    2014-04-01

    Methane bio-oxidation plays an important role in the global methane balance and warming mitigation, while copper has a crucial function in methane bio-oxidation. On one side, copper is known to be a key factor in regulating the expression of the genes encoding the two forms of methane monooxygenases (MMOs) and is the essential metal element of the particulate methane monooxygenase (pMMO). On the other side, the content and fractionation of copper in the environment have great effects on the distribution of methanotrophs and their metabolic capability of methane and non-methane organic compounds, as well as on the copper-specific uptake systems in methanotrophs. Thus, it is meaningful to know the role of copper in methane bio-oxidation for comprehensive understanding of this process and is valuable for guiding the application of methanotrophs in greenhouse gas removal and pollution remediation. In this paper, the roles of copper in methane oxidation were reviewed, including the effect of copper on methanotrophic community structure and activity, the expression and activity of MMOs as well as the copper uptake systems in methanotrophs. The future studies of copper and methane oxidation were also discussed.

  4. Rapid start-up of the anammox process: Effects of five different sludge extracellular polymeric substances on the activity of anammox bacteria.

    PubMed

    Guo, Jianbo; Wang, Sihui; Lian, Jing; Ngo, Huu Hao; Guo, Wenshan; Liu, Yunman; Song, Yuanyuan

    2016-11-01

    This study investigated the rapid start-up of the anaerobic ammonium oxidation (anammox) strategy by inoculating different biomass ratios of denitrifying granular sludge and anammox bacteria. The results demonstrated that two reactors (R1 and R2) were rapidly and successfully started-up on days 25 and 28, respectively, with nitrogen removal rates (NRRs) of 0.70kg/(m(3)·d) and 0.72kg/(m(3)·d) at biomass ratios of 10:1 (R1) and 50:1 (R2). The explanation for rapid start-up was found by examining the effect of five different sludge extracellular polymeric substances (EPS) on the activity of anammox bacteria in the batch experiments. Batch experiments results first demonstrated that the denitrification sludge EPS (DS-EPS) enhanced the anammox bacteria activity the most, and NO2(-)-N, NH4(+)-N removal rates were 1.88- and 1.53-fold higher than the control with optimal DS-EPS volume of 10mL. The rapid start-up strategy makes possible the application of anammox to practical engineering.

  5. Methane enhancement through co-digestion of chicken manure and thermo-oxidative cleaved wheat straw with waste activated sludge: A C/N optimization case.

    PubMed

    Hassan, Muhammad; Ding, Weimin; Shi, Zhendan; Zhao, Sanqin

    2016-07-01

    The present study emphasized the co-digestion of the thermal-H2O2 pretreated wheat straw (WS) and chicken manure (CM) with the waste activated sludge at four levels of C/N (35:1, 30:1, 25:1 and 20:1). All C/N compositions were found significant (P<0.05) to enhance methane generation and process stability during the anaerobic co-digestion of WS and CM. The experimental results revealed that the composition having C/N value of 20:1 was proved as optimum treatment with the methane enhancing capability of 85.11%, CODs removal efficiency of 48.55% and 66.83% VS removal as compared with the untreated WS. The other compositions having C/N of 25:1, 30:1 and 35:1 provided 75.85%, 63.04% and 59.96% enhanced methane respectively as compared with the control. Pretreatment of the WS reduced its C/N value up to 65%. Moreover, to optimize the most suitable C/N composition, the process stability of the co-digestion of WS and CM was deeply monitored.

  6. Evidence for methane in Martian meteorites

    PubMed Central

    Blamey, Nigel J. F.; Parnell, John; McMahon, Sean; Mark, Darren F.; Tomkinson, Tim; Lee, Martin; Shivak, Jared; Izawa, Matthew R. M.; Banerjee, Neil R.; Flemming, Roberta L.

    2015-01-01

    The putative occurrence of methane in the Martian atmosphere has had a major influence on the exploration of Mars, especially by the implication of active biology. The occurrence has not been borne out by measurements of atmosphere by the MSL rover Curiosity but, as on Earth, methane on Mars is most likely in the subsurface of the crust. Serpentinization of olivine-bearing rocks, to yield hydrogen that may further react with carbon-bearing species, has been widely invoked as a source of methane on Mars, but this possibility has not hitherto been tested. Here we show that some Martian meteorites, representing basic igneous rocks, liberate a methane-rich volatile component on crushing. The occurrence of methane in Martian rock samples adds strong weight to models whereby any life on Mars is/was likely to be resident in a subsurface habitat, where methane could be a source of energy and carbon for microbial activity. PMID:26079798

  7. Evidence for methane in Martian meteorites

    NASA Astrophysics Data System (ADS)

    Blamey, Nigel J. F.; Parnell, John; McMahon, Sean; Mark, Darren F.; Tomkinson, Tim; Lee, Martin; Shivak, Jared; Izawa, Matthew R. M.; Banerjee, Neil R.; Flemming, Roberta L.

    2015-06-01

    The putative occurrence of methane in the Martian atmosphere has had a major influence on the exploration of Mars, especially by the implication of active biology. The occurrence has not been borne out by measurements of atmosphere by the MSL rover Curiosity but, as on Earth, methane on Mars is most likely in the subsurface of the crust. Serpentinization of olivine-bearing rocks, to yield hydrogen that may further react with carbon-bearing species, has been widely invoked as a source of methane on Mars, but this possibility has not hitherto been tested. Here we show that some Martian meteorites, representing basic igneous rocks, liberate a methane-rich volatile component on crushing. The occurrence of methane in Martian rock samples adds strong weight to models whereby any life on Mars is/was likely to be resident in a subsurface habitat, where methane could be a source of energy and carbon for microbial activity.

  8. Evidence for methane in Martian meteorites.

    PubMed

    Blamey, Nigel J F; Parnell, John; McMahon, Sean; Mark, Darren F; Tomkinson, Tim; Lee, Martin; Shivak, Jared; Izawa, Matthew R M; Banerjee, Neil R; Flemming, Roberta L

    2015-06-16

    The putative occurrence of methane in the Martian atmosphere has had a major influence on the exploration of Mars, especially by the implication of active biology. The occurrence has not been borne out by measurements of atmosphere by the MSL rover Curiosity but, as on Earth, methane on Mars is most likely in the subsurface of the crust. Serpentinization of olivine-bearing rocks, to yield hydrogen that may further react with carbon-bearing species, has been widely invoked as a source of methane on Mars, but this possibility has not hitherto been tested. Here we show that some Martian meteorites, representing basic igneous rocks, liberate a methane-rich volatile component on crushing. The occurrence of methane in Martian rock samples adds strong weight to models whereby any life on Mars is/was likely to be resident in a subsurface habitat, where methane could be a source of energy and carbon for microbial activity.

  9. Tracing The Origin Of Methane And Water On Mars: Mapping Regions Of Active Release At Ultra-high Spatial Resolution Using Keck And VLT Under AO Control.

    NASA Astrophysics Data System (ADS)

    Mumma, Michael J.; Villanueva, G. L.; Campbell, R.; Lyke, J.; Conrad, A.; Encrenaz, T.; Hartogh, P.; Kauefl, U.; Novak, R. E.; Tokunaga, A.

    2009-09-01

    Strong release of methane from active regions on Mars has been reported in northern summer (1) and southern spring (2). The spatial resolution of these measurements was about 500 km, sufficient to reveal discrete active regions. Regions of methane release appear mainly over ancient terrain (Noachian/Hesperian) known to have a rich hydration history, and often marked by fossae or other scarps. However, higher resolution is needed to test whether methane release is confined to a small number of narrowly defined vents or is widely distributed over the 500 km footprint. If narrowly confined, the plume should have correspondingly higher local density, enhancing spectral searches for water, methane, their isotopologues, and other trace gases that could reveal aspects of methane generation and depth of release. Ground-based telescopes equipped with both adaptive optics (AO) and high dispersion infrared spectrometers have delivered much higher spatial resolution on planetary bodies, but until now have not been applied to Mars. We acquired images and spectra of Mars under AO control at infrared wavelengths, using Keck-2 and ESO-VLT. In June 2009, we acquired test images with NIRC2/Keck-2 using AO in the natural guide star mode and achieved 0.12” FWHM resolution at 3.0 µm wavelength (Mars diameter was 4.7"). Diffraction-limited performance (0.06” at 3 µm) is expected during follow-up observations in September 2009. We observed Mars with UT1 under AO control (MACAO) in August and September 2009, and acquired spectra with CRIRES. We expect to achieve spatial resolution approaching 40 km in November-December 2009, representing a reduction in area by nearly a factor of 100 compared with earlier non-AO searches. Preliminary results will be presented. This work was funded by NASA grants 08-PAST08-0034 (Planetary Astronomy) and 08-PATM080-0031 (Planetary Atmospheres). 1. Mumma, Villanueva, Novak et al., Science 323, 1041 (2009) 2. Villanueva, Mumma, Novak, (in prep) 2009.

  10. Interaction of the Transcription Start Site Core Region and Transcription Factor YY1 Determine Ascorbate Transporter SVCT2 Exon 1a Promoter Activity

    PubMed Central

    Qiao, Huan; May, James M.

    2012-01-01

    Transcription of the ascorbate transporter, SVCT2, is driven by two distinct promoters in exon 1 of the transporter sequence. The exon 1a promoter lacks a classical transcription start site and little is known about regulation of promoter activity in the transcription start site core (TSSC) region. Here we present evidence that the TSSC binds the multifunctional initiator-binding protein YY1. Electrophoresis shift assays using YY1 antibody showed that YY1 is present as one of two major complexes that specifically bind to the TSSC. The other complex contains the transcription factor NF-Y. Mutations in the TSSC that decreased YY1 binding also impaired the exon 1a promoter activity despite the presence of an upstream activating NF-Y/USF complex, suggesting that YY1 is involved in the regulation of the exon 1a transcription. Furthermore, YY1 interaction with NF-Y and/or USF synergistically enhanced the exon 1a promoter activity in transient transfections and co-activator p300 enhanced their synergistic activation. We propose that the TSSC plays a vital role in the exon 1a transcription and that this function is partially carried out by the transcription factor YY1. Moreover, co-activator p300 might be able to synergistically enhance the TSSC function via a “bridge” mechanism with upstream sequences. PMID:22532872

  11. Dry reforming of methane on a highly-active Ni-CeO2 catalyst: Effects of metal-support interactions on C–H bond breaking

    SciTech Connect

    Liu, Zongyuan; Grinter, David C.; Lustemberg, Pablo G.; Nguyen-Phan, Thuy -Duong; Zhou, Yinghui; Luo, B. Sc. Si; Waluyo, Iradwikanari; Crumlin, Ethan J.; Stacchiola, Dario J.; Zhou, Jing; Carrasco, Javier; Busnengo, H. Fabio; Ganduglia-Pirovano, M. Verónica; Senanayake, Sanjaya D.; Rodriguez, Jose A.

    2016-05-04

    Ni-CeO2 is a highly efficient, stable and non-expensive catalyst for methane dry reforming at relative low temperatures (700 K). The active phase of the catalyst consists of small nanoparticles of nickel dispersed on partially reduced ceria. Experiments of ambient pressure XPS indicate that methane dissociates on Ni/CeO2 at temperatures as low as 300 K, generating CHx and COx species on the surface of the catalyst. Strong metal–support interactions activate Ni for the dissociation of methane. The results of density-functional calculations show a drop in the effective barrier for methane activation from 0.9 eV on Ni(111) to only 0.15 eV on Ni/CeO2–x(111). At 700 K, under methane dry reforming conditions, no signals for adsorbed CHx or C species are detected in the C1s XPS region. As a result, the reforming of methane proceeds in a clean and efficient way.

  12. Arctic Methane: the View from Space

    NASA Astrophysics Data System (ADS)

    Leifer, I.; Yurganov, L.; Xiong, X.

    2014-12-01

    Global increase of methane that started in 2007-2008 after a decade of stability requires investigation and explanation. Recent Arctic warming has stimulated speculation about dissociation of Arctic Ocean methane hydrates providing a potentially important new climatic positive feedback. Satellite thermal infrared (TIR) data do not require sunlight, providing key advantages for Arctic data collection compared to shortwave infrared spectroscopy. The US Atmospheric IR Sounder (AIRS) has been delivering CH4 tropospheric data since 2002; NOAA CH4 retrievals from the European Infrared Atmospheric Sounding Interferometer (IASI) radiation data are available since 2008 and analyzed here since 2009. Accuracy of TIR satellite retrievals, especially for the lower troposphere, diminishes for a cold, underlying surface. In this analysis the dependence is parameterized using the Thermal Contrast (a difference between surface temperature and air temperature at the altitude of 4 km, defined THC). A correction function was applied to CH4 data based on a data-derived relationship between THC and retrieved CH4 for areas with positive THC (in other words, without temperature inversions). The seasonal cycles of the adjusted low tropospheric data are in agreement with the surface in situ measurements. Instantaneous IASI retrievals exhibit less variability than AIRS v6 data. Maximum positive deviation of methane concentration measured by IASI for the study period was found for Baffin Bay in November-December, 2013 (Figure). It was concluded that the methane anomaly could indicate both coastal and off-shore emissions. Off-shore data were spatially consistent with a hydrate dissociation mechanisms, active for water depths below the hydrate stability zone top at ~300 m. These are hypothesized to dissociate during seasonal temperature maximum in the bottom layer of the ocean, which occurs in fall. IASI data may be considered as a reliable source of information about Arctic CH4 for conditions

  13. Regulation of methane genes and genome expression

    SciTech Connect

    John N. Reeve

    2009-09-09

    At the start of this project, it was known that methanogens were Archaeabacteria (now Archaea) and were therefore predicted to have gene expression and regulatory systems different from Bacteria, but few of the molecular biology details were established. The goals were then to establish the structures and organizations of genes in methanogens, and to develop the genetic technologies needed to investigate and dissect methanogen gene expression and regulation in vivo. By cloning and sequencing, we established the gene and operon structures of all of the “methane” genes that encode the enzymes that catalyze methane biosynthesis from carbon dioxide and hydrogen. This work identified unique sequences in the methane gene that we designated mcrA, that encodes the largest subunit of methyl-coenzyme M reductase, that could be used to identify methanogen DNA and establish methanogen phylogenetic relationships. McrA sequences are now the accepted standard and used extensively as hybridization probes to identify and quantify methanogens in environmental research. With the methane genes in hand, we used northern blot and then later whole-genome microarray hybridization analyses to establish how growth phase and substrate availability regulated methane gene expression in Methanobacterium thermautotrophicus ΔH (now Methanothermobacter thermautotrophicus). Isoenzymes or pairs of functionally equivalent enzymes catalyze several steps in the hydrogen-dependent reduction of carbon dioxide to methane. We established that hydrogen availability determine which of these pairs of methane genes is expressed and therefore which of the alternative enzymes is employed to catalyze methane biosynthesis under different environmental conditions. As were unable to establish a reliable genetic system for M. thermautotrophicus, we developed in vitro transcription as an alternative system to investigate methanogen gene expression and regulation. This led to the discovery that an archaeal protein

  14. Effect on swimming start performance of two types of activation protocols: lunge and YoYo squat.

    PubMed

    Cuenca-Fernández, Francisco; López-Contreras, Gracia; Arellano, Raúl

    2015-03-01

    The purpose of this study was to compare the effects of 2 protocols of postactivation potentiation (PAP) on swimming start perfomance (SS). Fourteen trained swimmers (10 men and 4 women) volunteered for this study. An intragroup design of randomized repetitive measurements was applied. A previous SS trial, performed after a standard warm-up (SWU), served as a reference. Two methods of PAP, performed after 1 hour of rest, were randomly added to the SWU: (a) 3 lunges at 85% of 1 repetition maximum (LWU) and (b) 4 repetitions on the flywheel device YoYo squat (YWU). Swimmers were tested in an SS 8 minutes after the PAP warm-ups. Kinematic variables were collected using 3 underwater digital video cameras fixed poolside and operating at 25 Hz, and 1 high-speed camera focused on the block and operating at 300 Hz. Data obtained from the video analysis were processed using a repeated measures analysis of the variance. The mean horizontal velocity of the swimmer's flight improved after both PAP methods, with the greatest improvement after YWU (F2,12 = 47.042, p < 0.001; SWU = 3.63 ± 0.11; LWU = 4.15 ± 0.122; YWU = 4.89 ± 0.12 m·s). After YWU, it took the subjects less time to cover a distance of 5 m (F2,12 = 24.453, p < 0.001) and 15 m (F2,12 = 4.262, p < 0.04). Subjects also achieved a higher mean angular velocity of the knee extension (F2,12 = 23.286, p < 0.001) and a reduction of the time on the block (F2,12 = 6.595, p ≤ 0.05). These results demonstrate that muscle performance in the execution of an SS is enhanced after a warm-up with specific PAP protocols. YWU leads to the greatest improvement in the performance of the swimmer's start and, therefore, may be especially beneficial in short events.

  15. Imaging Active and Relict Seafloor Methane Seep Sites: a Comparison of Seafloor 3D Seismic Reflectivity and Multibeam Sonar Backscatter Intensity at Omakere Ridge, Hikurangi Margin, New Zealand

    NASA Astrophysics Data System (ADS)

    Golding, T. V.; Pecher, I. A.; Crutchley, G. J.; Klaeschen, D.; Papenberg, C. A.; Bialas, J.; Greinert, J.; Townend, J.; SO214 Shipboard Scientific Party

    2011-12-01

    Omakere Ridge is an anticlinal thrust ridge in water depths of 1100-1700 m on the Hikurangi Margin, east of the North Island of New Zealand, and an area of active seafloor methane seepage associated with an extensive gas hydrate province. Methane seep sites on the Hikurangi Margin are characterised by localised build-ups of hard authigenic carbonate and chemosynthetic seep fauna that exist on a seafloor otherwise characterised by soft, muddy sediments. Previous studies have shown that these seep sites appear as areas of high backscatter in sonar images, but backscatter data alone do not provide detailed information on the present level of activity of a seep site, or the thickness of the carbonate build-up. Here we present a comparison of seafloor seismic reflectivity and multibeam sonar backscatter intensity data collected from active and relict methane seep sites on Omakere Ridge. High-resolution P-Cable 3D seismic reflection data and 12 kHz EM120 multibeam sonar data were collected in March 2011 during the RV Sonne cruise SO214. Seafloor seismic amplitude maps have been derived from the shipboard post-stack migrated data cube. A pronounced acquisition artifact is manifest in the seafloor horizon slice as high and low amplitude stripes that alternate periodically in the crossline direction. We have removed this artifact from the seafloor horizon slice using Kx-Ky filtering, followed by direct sampling and deterministic removal of the very-low-frequency components in the spatial domain. The seismic amplitude map has then been transformed into a calibrated seafloor reflection coefficient map. Sonar backscatter mosaics have been created after correcting for instrument response, angular variation in backscatter and bathymetry. Several backscatter mosaics were incorporated into a stacked mosaic over the study area to attenuate random noise. The high sonar backscatter response at the seep sites is generally accompanied by high seismic reflectivity. However, the

  16. Record of methane emissions from the Arctic during the last Deglaciation

    NASA Astrophysics Data System (ADS)

    Panieri, Giuliana; Consolaro, Chiara; James, Rachael; Westbrook, Graham; Rasmussen, Tine; Mienert, Jürgen

    2014-05-01

    The methane hydrates of the Arctic represent potentially significant carbon resources that are sensitive to climate change. Methane hydrate provinces are widespread in the Arctic, but their stability and longevity through time, and the significance of their contribution to the global carbon budget, is still poorly understood. It is, therefore, critical to resolve the frequency of methane (CH4) seafloor emissions through time, in relation to past climate change with a special focus on periods of climate warming. The values of δ13C in benthic foraminifera have been measured in two cores, one collected from an area of active methane venting and one from an inactive area on the Vestnesa Ridge (NW Svalbard continental margin), in order to reconstruct the local history of methane emissions over the past 16,000 years BP. The chronostratigraphic framework of the cores has been derived from biostratigraphic analysis and AMS 14C dates. While foraminifera from some intervals have δ13C within the normal marine range (0 to -1), several intervals are characterized by much lower δ13C, as low as -17.4o in the active core and as low as -4.37o in the inactive core. These intervals are interpreted to record the incorporation of 13C-depleted carbon in the presence of methane emissions at the seafloor during biomineralization of the carbonate foraminiferal tests and subsequent secondary mineralization. The longest of these 'methane emission events' (MEE) coincides with the start of the warm Bølling-Allerød Interstadial (GI-1 in the Greenland ice core record). The lack of correlation between the values of δ13C and δ18O, however, appears to preclude warming of bottom waters as the principal control on methane release. Rather, it seems likely that methane release is related to changes in gas migration pathways, or other geological processes still under debate. Details on the CAGE research plan and organization can be found on www.cage.uit.no to foster opportunities for cross

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

    SciTech Connect

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

    1988-09-01

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

  18. Attributing Atmospheric Methane to Anthropogenic Emission Sources.

    PubMed

    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

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

    USGS Publications Warehouse

    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.

  20. High rates of anaerobic methane oxidation in freshwater wetlands reduce potential atmospheric methane emissions.

    PubMed

    Segarra, K E A; Schubotz, F; Samarkin, V; Yoshinaga, M Y; Hinrichs, K-U; Joye, S B

    2015-06-30

    The role of anaerobic oxidation of methane (AOM) in wetlands, the largest natural source of atmospheric methane, is poorly constrained. Here we report rates of microbially mediated AOM (average rate=20 nmol cm(-3) per day) in three freshwater wetlands that span multiple biogeographical provinces. The observed AOM rates rival those in marine environments. Most AOM activity may have been coupled to sulphate reduction, but other electron acceptors remain feasible. Lipid biomarkers typically associated with anaerobic methane-oxidizing archaea were more enriched in (13)C than those characteristic of marine systems, potentially due to distinct microbial metabolic pathways or dilution with heterotrophic isotope signals. On the basis of this extensive data set, AOM in freshwater wetlands may consume 200 Tg methane per year, reducing their potential methane emissions by over 50%. These findings challenge precepts surrounding wetland carbon cycling and demonstrate the environmental relevance of an anaerobic methane sink in ecosystems traditionally considered strong methane sources.

  1. Effect of ultrasound, low-temperature thermal and alkali pre-treatments on waste activated sludge rheology, hygienization and methane potential.

    PubMed

    Ruiz-Hernando, M; Martín-Díaz, J; Labanda, J; Mata-Alvarez, J; Llorens, J; Lucena, F; Astals, S

    2014-09-15

    Waste activated sludge is slower to biodegrade under anaerobic conditions than is primary sludge due to the glycan strands present in microbial cell walls. The use of pre-treatments may help to disrupt cell membranes and improve waste activated sludge biodegradability. In the present study, the effect of ultrasound, low-temperature thermal and alkali pre-treatments on the rheology, hygienization and biodegradability of waste activated sludge was evaluated. The optimum condition of each pre-treatment was selected based on rheological criteria (reduction of steady state viscosity) and hygienization levels (reduction of Escherichia coli, somatic coliphages and spores of sulfite-reducing clostridia). The three pre-treatments were able to reduce the viscosity of the sludge, and this reduction was greater with increasing treatment intensity. However, only the alkali and thermal conditioning allowed the hygienization of the sludge, whereas the ultrasonication did not exhibit any notorious effect on microbial indicators populations. The selected optimum conditions were as follows: 27,000 kJ/kg TS for the ultrasound, 80 °C during 15 min for the thermal and 157 g NaOH/kg TS for the alkali. Afterward, the specific methane production was evaluated through biomethane potential tests at the specified optimum conditions. The alkali pre-treatment exhibited the greatest methane production increase (34%) followed by the ultrasonication (13%), whereas the thermal pre-treatment presented a methane potential similar to the untreated sludge. Finally, an assessment of the different treatment scenarios was conducted considering the results together with an energy balance, which revealed that the ultrasound and alkali treatments entailed higher costs.

  2. Who receives contraception counseling when starting new lupus medications? The potential roles of race, ethnicity, disease activity, and quality of communication

    PubMed Central

    Ferguson, Sancia; Trupin, Laura; Yazdany, Jinoos; Yeli, Ed; Barton, Jennifer; Katz, Patti

    2015-01-01

    Objective Family planning discussions are an important aspect of medical care for women with systemic lupus erythematosus (SLE) as active disease is a risk factory for poor pregnancy outcomes, and the medications used for treatment can be harmful to the fetus when used during conception and pregnancy. Our objective was to examine the impact of patient perception of quality and type of communication on receiving contraception counseling. Methods Data were derived from patients enrolled in the University of California, San Francisco Lupus Outcomes Study. Subjects participate in yearly structured telephone interview, which included assessment of contraception counseling when starting new medications, and measures of communication and decision-making. Logistic regression was performed to identify predictors of not receiving contraception counseling. Results Of the 68 women included in this analysis, one third did not receive contraception counseling when starting new medications. Older age, white race, depressive symptoms, and higher SLE disease activity were independently associated with not receiving contraception counseling. Participants who did not receive contraception counseling rated their physicians lower in shared decision making communication. Conclusions This study demonstrates a gap in family planning counseling among women with SLE starting new medications. Future studies to address these potential areas of intervention, including education about the need for contraception through menopause, and mechanisms to engage in SDM surrounding contraception are needed to improve quality of care for women with lupus. PMID:26190169

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

    PubMed Central

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

    2015-01-01

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

  4. (Methane digester). Final report

    SciTech Connect

    Waybright, R.C.

    1981-01-01

    The purpose of the grant was to construct and operate a methane digester for dairy manure involving the latest state-of-the-art technics. The first step taken was to empty out the existing digester to evaluate its performance and to gain ideas of how to build the next digester so it would operate more efficiently. Next, the design criteria was set up in order to eliminate some problems involved with the first digester and also new ideas as to how to build the next one without a protective building and testing simplified construction technics. After this the digester construction was started with the completion date in late January. The digester was then filled and operated at different temperatures attempting to achieve the optimum operating range.

  5. The role of rotational excitation in the activated dissociative chemisorption of vibrationally excited methane on Ni(100).

    PubMed

    Juurlink, L B; Smith, R R; Utz, A L

    2000-01-01

    We have measured the sticking probability of methane excited to v = 1 of the v3 antisymmetric C-H stretching vibration on a clean Ni(100) surface as a function of rotational state (J = 0, 1, 2 and 3) and have investigated the effect of Coriolis-mixing on reactivity. The data span a wide range of kinetic energies (9-49 kJ mol-1) and indicate that rotational excitation does not alter reactivity by more than a factor of two, even at low molecular speeds that allow for considerable rotation of the molecule during the interaction with the surface. In addition, rotation-induced Coriolis-splitting of the v3 mode into F+, F0 and F- states does not significantly affect the reactivity for J = 1 at 49 kJ mol-1 translational energy, even though the nuclear motions of these states differ. The lack of a pronounced rotational energy effect in methane dissociation on Ni(100) suggests that our previous results for (v = 1, v3, J = 2) are representative of all rovibrational sublevels of this vibrational mode. These experiments shed light on the relative importance of rotational hindering and dynamical steering mechanisms in the dissociative chemisorption on Ni(100) and guide future attempts to accurately model methane dissociation on nickel surfaces.

  6. Effects of sludge inoculum and organic feedstock on active microbial communities and methane yield during anaerobic digestion

    PubMed Central

    Wilkins, David; Rao, Subramanya; Lu, Xiaoying; Lee, Patrick K. H.

    2015-01-01

    Anaerobic digestion (AD) is a widespread microbial technology used to treat organic waste and recover energy in the form of methane (“biogas”). While most AD systems have been designed to treat a single input, mixtures of digester sludge and solid organic waste are emerging as a means to improve efficiency and methane yield. We examined laboratory anaerobic cultures of AD sludge from two sources amended with food waste, xylose, and xylan at mesophilic temperatures, and with cellulose at meso- and thermophilic temperatures, to determine whether and how the inoculum and substrate affect biogas yield and community composition. All substrate and inoculum combinations yielded methane, with food waste most productive by mass. Pyrosequencing of transcribed bacterial and archaeal 16S rRNA showed that community composition varied across substrates and inocula, with differing ratios of hydrogenotrophic/acetoclastic methanogenic archaea associated with syntrophic partners. While communities did not cluster by either inoculum or substrate, additional sequencing of the bacterial 16S rRNA gene in the source sludge revealed that the bacterial communities were influenced by their inoculum. These results suggest that complete and efficient AD systems could potentially be assembled from different microbial inocula and consist of taxonomically diverse communities that nevertheless perform similar functions. PMID:26528262

  7. Water-Gas Shift and Methane Reactivity on Reducible Perovskite-Type Oxides.

    PubMed

    Thalinger, Ramona; Opitz, Alexander K; Kogler, Sandra; Heggen, Marc; Stroppa, Daniel; Schmidmair, Daniela; Tappert, Ralf; Fleig, Jürgen; Klötzer, Bernhard; Penner, Simon

    2015-05-28

    Comparative (electro)catalytic, structural, and spectroscopic studies in hydrogen electro-oxidation, the (inverse) water-gas shift reaction, and methane conversion on two representative mixed ionic-electronic conducting perovskite-type materials La0.6Sr0.4FeO3-δ (LSF) and SrTi0.7Fe0.3O3-δ (STF) were performed with the aim of eventually correlating (electro)catalytic activity and associated structural changes and to highlight intrinsic reactivity characteristics as a function of the reduction state. Starting from a strongly prereduced (vacancy-rich) initial state, only (inverse) water-gas shift activity has been observed on both materials beyond ca. 450 °C but no catalytic methane reforming or methane decomposition reactivity up to 600 °C. In contrast, when starting from the fully oxidized state, total methane oxidation to CO2 was observed on both materials. The catalytic performance of both perovskite-type oxides is thus strongly dependent on the degree/depth of reduction, on the associated reactivity of the remaining lattice oxygen, and on the reduction-induced oxygen vacancies. The latter are clearly more reactive toward water on LSF, and this higher reactivity is linked to the superior electrocatalytic performance of LSF in hydrogen oxidation. Combined electron microscopy, X-ray diffraction, and Raman measurements in turn also revealed altered surface and bulk structures and reactivities.

  8. Water-Gas Shift and Methane Reactivity on Reducible Perovskite-Type Oxides

    PubMed Central

    2015-01-01

    Comparative (electro)catalytic, structural, and spectroscopic studies in hydrogen electro-oxidation, the (inverse) water-gas shift reaction, and methane conversion on two representative mixed ionic–electronic conducting perovskite-type materials La0.6Sr0.4FeO3−δ (LSF) and SrTi0.7Fe0.3O3−δ (STF) were performed with the aim of eventually correlating (electro)catalytic activity and associated structural changes and to highlight intrinsic reactivity characteristics as a function of the reduction state. Starting from a strongly prereduced (vacancy-rich) initial state, only (inverse) water-gas shift activity has been observed on both materials beyond ca. 450 °C but no catalytic methane reforming or methane decomposition reactivity up to 600 °C. In contrast, when starting from the fully oxidized state, total methane oxidation to CO2 was observed on both materials. The catalytic performance of both perovskite-type oxides is thus strongly dependent on the degree/depth of reduction, on the associated reactivity of the remaining lattice oxygen, and on the reduction-induced oxygen vacancies. The latter are clearly more reactive toward water on LSF, and this higher reactivity is linked to the superior electrocatalytic performance of LSF in hydrogen oxidation. Combined electron microscopy, X-ray diffraction, and Raman measurements in turn also revealed altered surface and bulk structures and reactivities. PMID:26045733

  9. Combined anaerobic ammonium and methane oxidation for nitrogen and methane removal.

    PubMed

    Zhu, Baoli; Sánchez, Jaime; van Alen, Theo A; Sanabria, Janeth; Jetten, Mike S M; Ettwig, Katharina F; Kartal, Boran

    2011-12-01

    Anammox (anaerobic ammonium oxidation) is an environment-friendly and cost-efficient nitrogen-removal process currently applied to high-ammonium-loaded wastewaters such as anaerobic digester effluents. In these wastewaters, dissolved methane is also present and should be removed to prevent greenhouse gas emissions into the environment. Potentially, another recently discovered microbial pathway, n-damo (nitrite-dependent anaerobic methane oxidation) could be used for this purpose. In the present paper, we explore the feasibility of simultaneously removing methane and ammonium anaerobically, starting with granules from a full-scale anammox bioreactor. We describe the development of a co-culture of anammox and n-damo bacteria using a medium containing methane, ammonium and nitrite. The results are discussed in the context of other recent studies on the application of anaerobic methane- and ammonia-oxidizing bacteria for wastewater treatment.

  10. Optimal placement of actuators for active vibration control of seismic excited tall buildings using a multiple start guided neighbourhood search (MSGNS) algorithm

    NASA Astrophysics Data System (ADS)

    Rama Mohan Rao, A.; Sivasubramanian, K.

    2008-03-01

    Active control devices can be implemented on seismically excited high rise buildings using appropriate active control theory, to reduce structural responses to a desired level. Certain locations of the structure are advantageous for placement of actuators in the sense that these locations effectively reduce the structural responses. Hence, optimal placement of actuators at discrete locations is an important problem that will have significant impact on control of civil structures like high rise buildings, bridges, etc. This optimal placement problem leads to a combinatorial optimisation and is difficult to solve. This paper presents a multi-start meta-heuristic algorithm called multiple start guided neighbourhood search (MSGNS) algorithm, which makes use of the good features of guided local searches like simulated annealing (SA) and tabu search (TS). Four distinct design criteria which influence the active control design are considered in this paper to study the optimal actuator placement problem. The sensitivities of the four optimisation criteria with respect to different earthquake records are explored. Further, in this paper, we deviate from the usual practice of using shear building models (or simple lumped mass model) in active control research for finding optimal actuator locations. Instead, we use detailed finite element models and demonstrate through numerical examples their effectiveness in arriving at the optimal actuator locations. Finally, the superior performance of the proposed MSGNS algorithm over popular meta-heuristic algorithms like GA, SA and TS is demonstrated through numerical experiments.

  11. Differing effects of 2 active dried yeast (Saccharomyces cerevisiae) strains on ruminal acidosis and methane production in nonlactating dairy cows.

    PubMed

    Chung, Y-H; Walker, N D; McGinn, S M; Beauchemin, K A

    2011-05-01

    Fifteen ruminally cannulated, nonlactating Holstein cows were used to measure the effects of 2 strains of Saccharomyces cerevisiae, fed as active dried yeasts, on ruminal pH and fermentation and enteric methane (CH(4)) emissions. Nonlactating cows were blocked by total duration (h) that their ruminal pH was below 5.8 during a 6-d pre-experimental period. Within each block, cows were randomly assigned to control (no yeast), yeast strain 1 (Levucell SC), or yeast strain 2 (a novel strain selected for enhanced in vitro fiber degradation), with both strains (Lallemand Animal Nutrition, Montréal, QC, Canada) providing 1 × 10(10) cfu/head per day. Cows were fed once daily a total mixed ration consisting of a 50:50 forage to concentrate ratio (dry matter basis). The yeast strains were dosed via the rumen cannula daily at the time of feeding. During the 35-d experiment, ruminal pH was measured continuously for 7 d (d 22 to 28) by using an indwelling system, and CH(4) gas was measured for 4 d (d 32 to 35) using the sulfur hexafluoride tracer gas technique (with halters and yokes). Rumen contents were sampled on 2 d (d 22 and 26) at 0, 3, and 6h after feeding. Dry matter intake, body weight, and apparent total-tract digestibility of nutrients were not affected by yeast feeding. Strain 2 decreased the average daily minimum (5.35 vs. 5.65 or 5.66), mean (5.98 vs. 6.24 or 6.34), and maximum ruminal pH (6.71 vs. 6.86 or 6.86), and prolonged the time that ruminal pH was below 5.8 (7.5 vs. 3.3 or 1.0 h/d) compared with the control or strain 1, respectively. The molar percentage of acetate was lower and that of propionate was greater in the ruminal fluid of cows receiving strain 2 compared with cows receiving no yeast or strain 1. Enteric CH(4) production adjusted for intake of dry matter or gross energy, however, did not differ between either yeast strain compared with the control but it tended to be reduced by 10% when strain 2 was compared with strain 1. The study shows that

  12. [Sources of Methane in the Boreal Region

    NASA Technical Reports Server (NTRS)

    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

  13. Nature of radio feature formed by re-started jet activity in 3C 84 and its relation with γ-ray emissions

    NASA Astrophysics Data System (ADS)

    Nagai, H.; Chida, H.; Kino, M.; Orienti, M.; D'Ammando, F.; Giovannini, G.; Hiura, K.

    2016-02-01

    Re-started jet activity occurred in the bright nearby radio source 3C 84 in about 2005. The re-started jet is forming a prominent component (namely C3) at the tip of jet. The component has showed an increase in radio flux density for more than 7 years while the radio spectrum remains optically thin. This suggests that the component is the head of a radio lobe including a hotspot where the particle acceleration occurs. Thus, 3C 84 is a unique laboratory to study the physical properties at the very early stage of radio source evolution. Another important aspect is that high energy and very high energy γ-ray emissions are detected from this source. The quest for the site of γ-ray emission is quite important to obtain a better understanding of γ-ray emission mechanisms in radio galaxies. In this paper, we review the observational results from very long baseline interferometry (VLBI) monitoring of 3C 84 reported in series of our previous papers. We argue the nature of re-started jet/radio lobe and its relation with high-energy emission.

  14. Controlling tunnelling in methane loss from acetone ions by deuteration.

    PubMed

    Bodi, Andras; Baer, Tomas; Wells, Nancy K; Fakhoury, Daniel; Klecyngier, David; Kercher, James P

    2015-11-21

    Energetic acetone cations decay by methane or methyl radical loss. Although the methane-loss barrier to form the ketene cation is higher and the activation entropy is lower, it has a significant branching ratio at low energies thanks to quantum tunnelling. H-atom tunnelling can be selectively quenched and the methane-loss channel suppressed quantitatively by deuteration.

  15. GRI methane chemistry program review meeting

    SciTech Connect

    Dignon, J.; Grant, K.; Grossman, A.; Wuebles, D.; Brasseur, G.; Madronich, S.; Huang, T.; Chang, J.; Lott, B.

    1997-02-01

    Methane is an important greenhouse gas which affects the atmosphere directly by the absorption and re-emission of infrared radiation as well as indirectly, through chemical interactions. Emissions of several important greenhouse gases (GHGS) including methane are increasing, mainly due to human activity. Higher concentrations of these gases in the atmosphere are projected to cause a decrease in the amount of infrared radiation escaping to space, and a subsequent warming of global climate. It is therefore vital to understand not only the causes of increased production of methane and other GHGS, but the effect of higher GHG concentrations on climate, and the possibilities for reductions of these emissions. In GRI-UIUC methane project, the role of methane in climate change and greenhouse gas abatement strategies is being studied using several distinct approaches. First, a detailed treatment of the mechanisms controlling each important methane source and sink, and hence the atmospheric concentration of methane, is being developed for use with the UIUC Integrated Science Assessment Model. The focus of this study is to resolve the factors which determine methane emissions and removal, including human population, land use, energy demand, global temperature, and regional concentrations of the hydroxyl radical, carbon monoxide, nitrous oxides, non-methane hydrocarbons, water vapor, tropospheric and stratospheric ozone.

  16. Methane emission during municipal wastewater treatment.

    PubMed

    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.

  17. The significance of methane ebullition

    NASA Astrophysics Data System (ADS)

    Walter, K.; Draluk, D. A.; Zimov, S. A.; Chapin, T.

    2003-12-01

    lakes differ from most lakes in Alaska and Canada because they are surrounded by ice-rich (50-90% ice) permafrost that facilitates intense thermokarst erosion along lake margins. In turn, organic-rich (~2%) mineral soil subsides into anaerobic lake bottoms, providing a fresh, labile substrate for methanogenesis. Increased thermokarst erosion with climate warming would provide a positive feedback to methane production and emission from lakes. Although thermokarst activity likely results in higher emissions of methane via ebullition from North Siberian lakes than from other northern lakes, results from this study suggest ebullition may be a more important pathway of methane emission than what has been reported to date.

  18. Room-temperature activation of methane and dry re-forming with CO2 on Ni-CeO2 (111) surfaces: Effect of Ce3+ sites and metal–support interactions on C–H bond cleavage

    DOE PAGES

    Lustemberg, Pablo G.; Ramírez, Pedro J.; Liu, Zongyuan; ...

    2016-10-27

    The results of core-level photoemission indicate that Ni-CeO2(111) surfaces with small or medium coverages of nickel are able to activate methane at 300 K, producing adsorbed CHx and COx (x = 2, 3) groups. Calculations based on density functional theory predict a relatively low activation energy of 0.6–0.7 eV for the cleavage of the first C–H bond in the adsorbed methane molecule. Ni and O centers of ceria work in a cooperative way in the dissociation of the C–H bond at room temperature, where a low Ni loading is crucial for the catalyst activity and stability. The strong electronic perturbationsmore » in the Ni nanoparticles produced by the ceria supports of varying natures, such as stoichiometric and reduced, result in a drastic change in their chemical properties toward methane adsorption and dissociation as well as the dry reforming of methane reaction. Lastly, the coverage of Ni has a drastic effect on the ability of the system to dissociate methane and catalyze the dry re-forming process.« less

  19. Reduction of Quartz to Silicon Monoxide by Methane-Hydrogen Mixtures

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Zhang, Guangqing; Tronstad, Ragnar; Ostrovski, Oleg

    2016-08-01

    The reduction of quartz was studied isothermally in a fluidized bed reactor using continuously flowing methane-hydrogen gas mixture in the temperature range from 1623 K to 1773 K (1350 °C to 1500 °C). The CO content in the off-gas was measured online using an infrared gas analyzer. The main phases of the reduced samples identified by XRD analysis were quartz and cristobalite. Significant weight loss in the reduction process indicated that the reduction products were SiO and CO. Reduction of SiO2 to SiO by methane starts with adsorption and dissociation of CH4 on the silica surface. The high carbon activity in the CH4-H2 gas mixture provided a strongly reducing condition. At 1623 K (1350 °C), the reduction was very slow. The rate and extent of reduction increased with the increasing temperature to 1723 K (1450 °C). A further increase in temperature to 1773 K (1500 °C) resulted in a decrease in the rate and extent of reduction. An increase in the gas flow rate from 0.4 to 0.8 NL/min and an increase in the methane content in the CH4-H2 gas mixture from 0 to 5 vol pct facilitated the reduction. Methane content in the gas mixture should be maintained at less than 5 vol pct in order to suppress methane cracking.

  20. Human holocarboxylase synthetase with a start site at methionine-58 is the predominant nuclear variant of this protein and has catalytic activity

    SciTech Connect

    Bao, Baolong; Wijeratne, Subhashinee S.K.; Rodriguez-Melendez, Rocio; Zempleni, Janos

    2011-08-19

    Highlights: {yields} Unambiguous evidence is provided that methionine-58 serves as an in-frame alternative translation site for holocarboxylase synthetase (HLCS58). {yields} Full-length HLCS and HLCS58 enter the nucleus, but HLCS58 is the predominant variant. {yields} HLCS58 has biological activity as biotin protein ligase. -- Abstract: Holocarboxylase synthetase (HLCS) catalyzes the covalent binding of biotin to both carboxylases in extranuclear structures and histones in cell nuclei, thereby mediating important roles in intermediary metabolism, gene regulation, and genome stability. HLCS has three putative translational start sites (methionine-1, -7, and -58), but lacks a strong nuclear localization sequence that would explain its participation in epigenetic events in the cell nucleus. Recent evidence suggests that small quantities of HLCS with a start site in methionine-58 (HLCS58) might be able to enter the nuclear compartment. We generated the following novel insights into HLCS biology. First, we generated a novel HLCS fusion protein vector to demonstrate that methionine-58 is a functional translation start site in human cells. Second, we used confocal microscopy and western blots to demonstrate that HLCS58 enters the cell nucleus in meaningful quantities, and that full-length HLCS localizes predominantly in the cytoplasm but may also enter the nucleus. Third, we produced recombinant HLCS58 to demonstrate its biological activity toward catalyzing the biotinylation of both carboxylases and histones. Collectively, these observations are consistent with roles of HLCS58 and full-length HLCS in nuclear events. We conclude this report by proposing a novel role for HLCS in epigenetic events, mediated by physical interactions between HLCS and other chromatin proteins as part of a larger multiprotein complex that mediates gene repression.

  1. Analysis of past recurrent methane seep activity using radiocarbon dating of Calyptogena spp. shells in the eastern Nankai subduction zone, Japan

    NASA Astrophysics Data System (ADS)

    Yagasaki, Kazuhiro; Ashi, Juichiro; Yokoyama, Yusuke; Miyairi, Yosuke; Kuramoto, Shin'ichi

    2016-04-01

    Fault activity around subduction zones have been widely studied and monitored through drilling of oceanic plates, studying piston cores, use of monitoring equipment or through visual analysis using submersible vehicles. Yet the understanding of how small scale faults near shallow regions of the seabed behave in relation to cold seep vent activity is still vague, especially determining when they were active in the past. In tectonically active margins such as the Nankai and Tokai regions off Japan, dense methane hydrate reservoirs have been identified. Cold seeps releasing methane rich hydrocarbon fluids are common here, supporting a wide variety of biological species that hold a symbiotic relationship with the chemosynthetic bacteria. In 1998 a large dead Calyptogena spp. bivalve colony (over 400m2 in size) was discovered off Tokai, Japan. It is unusual for a bivalve colony this size to mostly be dead, raising questions as to what caused their death. In this study we document the radiocarbon 14C age of these bivalve shells to attempt analysing the possible methane seep bahaviour in the past. The measured 14C age ranged in three age groups of 1396±36-1448±34, 1912±31-1938±35 and 5975±34. The 14C age of shells that were alive upon collection and the dissolved inorganic carbon (DIC) in seawater show little difference (˜100 14C age) indicating that shells are not heavily affected by the dead carbon effect from cold seeps that is of biogenic or thermogenic origin, which can make the age to become considerably older than the actual age. Thus the novel calibration model used was based on the seawater DIC collected above the Calyptogena spp. colony site (1133±31), which resulted in the dead shells to be clustered around 1900 Cal AD. This proves to be interesting as the predicted epicenter of the Ansei-Tokai earthquake (M 8.4) in 1854 is extremely close to the bibalve colony site. Using geological data obtained using visual analysis and sub-seafloor structural

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

    USGS Publications Warehouse

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

    1993-01-01

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

  3. Identification of Methanogens and Controls on Methane Production in Incubations of Natural Methane Seep Sediments

    NASA Astrophysics Data System (ADS)

    Kevorkian, R.; Lloyd, K. G.

    2014-12-01

    Methane, the most abundant hydrocarbon in Earth's atmosphere, is produced in large quantities in sediments underlying the world's oceans. Very little of this methane makes it to surface sediments as it is consumed by Anaerobic Methanotrophs (ANME's) in consortia with Sulfate Reducing Bacteria (SRB). Less is known about which organisms are responsible for methane production in marine sediments, and whether that production is under thermodynamic control based on hydrogen concentrations. Although ANMEs have been found to be active in methanogenic sediments and incubations, it is currently unknown whether they are able to grow in methanogenic conditions. We demonstrated with bottle incubations of methane seep sediment taken from Cape Lookout Bight, NC, that hydrogen controls methane production. While sulfate was present the hydrogen concentration was maintained at below 2 nM. Only after the depletion of sulfate allowed hydrogen concentrations to rise above 5 nM did we see production of methane. The same sediments when spiked with methane gas demonstrated its complete removal while sulfate reduction occurred. Quantitative PCR shows that ANME-2 and ANME-1 increase in 16S copy number as methane increases. Total direct cell counts demonstrate a decline in cells with the decrease of sulfate until a recovery corresponding with production of methane. Our results strongly suggest that hydrogen concentrations influence what metabolic processes can occur in marine sediments, and that ANME-1 and ANME-2 are able to grow on the energy provided from methane production.

  4. 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

    NASA Astrophysics Data System (ADS)

    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

  5. Thermo-alkaline pretreatment of waste activated sludge at low-temperatures: effects on sludge disintegration, methane production, and methanogen community structure.

    PubMed

    Kim, Jaai; Yu, Youngseob; Lee, Changsoo

    2013-09-01

    Low-temperature thermo-alkaline pretreatment of waste activated sludge (WAS) was studied, within the region of 0-0.2 M NaOH and 60-90°C, for the effects of NaOH concentration and temperature on sludge degradability in anaerobic digestion (AD). Significant disintegration of sludge solids (up to 75.6%) and an increase in methane production (up to 70.6%) were observed in the pretreatment trials. Two quadratic models were successfully generated by response surface analysis (R(2)>0.9, p<0.05) to approximate how the degree of sludge disintegration (SD) and methane production (MP) respond to changes in the pretreatment conditions. The maximum responses of SD (77.8%) and MP (73.9% increase over the control) were shown at [0.16 M NaOH, 90°C] and [0.10 M NaOH, 73.7°C], respectively. NaOH addition showed a significant influence on the evolution of methanogen community structure during AD, whereas temperature did not. Aceticlastic Methanosaeta and Methanosarcina speceies were likely the major methanogens.

  6. Up with methane

    SciTech Connect

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

    1986-12-01

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

  7. Methane Plumes on Mars

    NASA Video Gallery

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

  8. Mars Methane highs unrelated to comets

    NASA Astrophysics Data System (ADS)

    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

  9. Root-Associated Methane Oxidation and Methanogenesis: Key Determinants of Wetland Methane Emissions

    NASA Technical Reports Server (NTRS)

    King, G. M.

    1997-01-01

    During the award period, we have assessed the extent and controls of methane oxidation in north temperate wetlands. It is evident that wetlands have been a major global source of atmospheric methane in the past, and are so at present. It is also evident that microbial methane oxidation consumes a variable fraction of total wetland methane production, perhaps 10%-90%. Methane oxidation is thus a potentially important control of wetland methane emission. Our efforts have been designed to determine the extent of the process, its controls, and possible relationships to changes that might be expected in wetlands as a consequence of anthropogenic or climate-related disturbances. Current work, has emphasized controls of methane oxidation associated with rooted aquatic plants. As for the sediment-water interface, we have observed that oxygen availability is a primary limiting factor. Our conclusion is based on several different lines of evidence obtained from in vitro and in situ analyses. First, we have measured the kinetics of methane oxidation by intact plant roots harboring methane-oxidizing bacteria, as well as the kinetics of the methanotrophs themselves. Values for the half-saturation constant (apparent K(sub m)) are approximately 5 microns. These values are roughly equivalent to, or much less than porewater methane concentrations, indicating that uptake is likely saturated with respect to methane, and that some other parameter must limit activity. Methane concentrations in the lacunar spaces at the base of plant stems are also comparable to the half-saturation constants (when expressed as equivalent dissolved concentrations), providing further support for limitation of uptake by parameters other than methane.

  10. Low-temperature conversion of methane to methanol on CeOx/Cu2O catalysts: Water controlled activation of the C–H Bond

    SciTech Connect

    Zuo, Zhijun; Ramírez, Pedro J.; Senanayake, Sanjaya D.; Liu, Ping; Rodriguez, Jose A.

    2016-10-10

    Here, an inverse CeO2/Cu2O/Cu(111) catalyst is able to activate methane at room temperature producing C, CHx fragments and COx species on the oxide surface. The addition of water to the system leads to a drastic change in the selectivity of methane activation yielding only adsorbed CHx fragments. At a temperature of 450 K, in the presence of water, a CH4 → CH3OH catalytic transformation occurs with a high selectivity. OH groups formed by the dissociation of water saturate the catalyst surface, removing sites that could decompose CHx fragments, and generating centers on which methane can directly interact to yield methanol.

  11. Effect of nitrogen fertilization on the activity and diversity of methane oxidising bacteria in the littoral zone of a boreal lake

    NASA Astrophysics Data System (ADS)

    Saari, A.; Siljanen, H. M. P.; Hämäläinen, S.; Bodrossy, L.; Martikainen, P. J.

    2009-04-01

    Freshwater lakes are generally net sources of CH4 and in boreal lakes a major part of the CH4 emissions originates from the littoral zone during the ice-free season. Aerobic CH4 oxidising bacteria, methanotrophs, significantly limit the flux of CH4 to the atmosphere from sediments. Increased N load causes eutrophication and subsequent anoxia, which probably enhances CH4 production. In addition, inorganic nitrogen (ammonium and nitrate) can inhibit CH4 oxidation. Our study belongs to the research consortium METHECO (Eurodiversity programme of European Science Foundation), where the activity and diversity of methane oxidising bacteria are studied in various European ecosystems. We studied with in situ manipulation the effects of eutrophication (added nitrogen) on the activity and diversity of methanotrophs in a littoral wetland of a small and shallow hyper-eutrophic lake in east-central Finland. We established in the area growing sedges (7-10 m from the shore line) three sampling plots (1.2 m x 1.2 m), which were irrigated four times (from 4th July to 9th August) with ammonium nitrate solution giving 10 g N m-2for the total additional nitrogen load during the growing season. Three control plots were irrigated with equivalent amount of distilled water. The amount of added ammonium nitrate solution or water did not exceed 10% of the long-term (30 years) average rainfall in the area during the growing season. Sediment samples were taken from the depths of 0-2 cm, 2-10cm, 10-20 cm and 20-30 cm before, during and after the N treatment. Methane oxidation potential was studied in 550-ml flasks with sediment slurries and initial headspace CH4 concentration of 0.1%. The diversity of methanotrophs was studied with pmoA-microarray. Methane oxidation was most active in the organic surface sediment layer of 0-10 cm and the activity decreased with depth. Nitrogen addition in situ did not affect significantly the potential CH4 oxidation rates, although nitrate inhibited CH4

  12. Transcriptional activities of methanogens and methanotrophs vary with methane emission flux in rice soils under chronic nutrient constraints of phosphorus and potassium

    NASA Astrophysics Data System (ADS)

    Sheng, Rong; Chen, Anlei; Zhang, Miaomiao; Whiteley, Andrew S.; Kumaresan, Deepak; Wei, Wenxue

    2016-12-01

    Nutrient status in soil is crucial for the growth and development of plants which indirectly or directly affect the ecophysiological functions of resident soil microorganisms. Soil methanogens and methanotrophs can be affected by soil nutrient availabilities and plant growth, which in turn modulate methane (CH4) emissions. Here, we assessed whether deficits in soil-available phosphorus (P) and potassium (K) modulated the activities of methanogens and methanotrophs in a long-term (20 year) experimental system involving limitation in either one or both nutrients. Results showed that a large amount of CH4 was emitted from paddy soil at rice tillering stage (flooding) while CH4 flux was minimum at ripening stage (drying). Compared to soils amended with NPK fertiliser treatment, the soils without P input significantly reduced methane flux rates, whereas those without K input did not. Under P limitation, methanotroph transcript copy number significantly increased in tandem with a decrease in methanogen transcript abundance, suggesting that P-deficiency-induced changes in soil physio-chemical properties, in tandem with rice plant growth, might constrain the activity of methanogens, whereas the methanotrophs might be adaptive to this soil environment. In contrast, lower transcript abundance of both methanogen and methanotrophs were observed in K-deficient soils. Assessments of community structures based upon transcripts indicated that soils deficient in P induced greater shifts in the active methanotrophic community than K-deficient soils, while similar community structures of active methanogens were observed in both treatments. These results suggested that the population dynamics of methanogens and methanotrophs could vary along with the changes in plant growth states and soil properties induced by nutrient deficiency.

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

    PubMed

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

    2015-09-01

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

  14. Methane oxidation coupled to oxygenic photosynthesis in anoxic waters

    PubMed Central

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

    2015-01-01

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

  15. Heat pipe methanator

    DOEpatents

    Ranken, William A.; Kemme, Joseph E.

    1976-07-27

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

  16. Understanding the Recent Methane Budget

    NASA Astrophysics Data System (ADS)

    Bruhwiler, L.; Dlugokencky, E. J.; Masarie, K.

    2010-12-01

    Anthropogenic sources are thought to account for roughly 2/3 of the global atmospheric methane budget, with natural sources making up the other 1/3. Emissions from wetlands are the largest contribution from natural sources while agriculture (rice and ruminants) and waste dominate anthropogenic emissions. Fugitive emissions from fossil fuel extraction are thought to make up about 20% of the global atmospheric methane budget. It is generally recognized that observed inter-annual variability in global network observations can be attributed to natural sources such as wetlands and biomass burning, while longer-term trends likely indicate changes in anthropogenic sources. Exceptions include an abrupt decrease in fossil fuel emissions in the early 1990s associated with political changes in the Former Soviet Union, and long-term trends in emissions from the Arctic due to a warming climate. The growth rate of global average atmospheric methane since the 1980s shows a steady decline until recent years when it started to increase again. Superimposed on these trends are episodes of higher growth rates. The cause of the recent increase is not currently well-understood, although climate-driven increases in wetland emissions likely played an important role, especially in the tropics. Recent increases in anthropogenic emissions, especially from rapidly expanding Asian economies cannot be ruled out. In addition, trends in the photochemical lifetime of methane must also be considered. In this paper we use both traditional data analysis of observations of methane and related species, and a state-of-the-art ensemble data assimilation system (CarbonTracker-CH4) to attribute methane variability and trends to anthropogenic and natural source processes. We pay particular attention to the Arctic, where some recent years have been the warmest on record, and to the tropics and the potential role of ENSO in driving variability of wetland emissions. Finally, we explore whether a signal in

  17. Weight loss and achievement of minimal disease activity in patients with psoriatic arthritis starting treatment with tumour necrosis factor α blockers

    PubMed Central

    Di Minno, Matteo Nicola Dario; Peluso, Rosario; Iervolino, Salvatore; Russolillo, Anna; Lupoli, Roberta; Scarpa, Raffaele

    2014-01-01

    Objectives To evaluate prospectively the effect of weight loss on the achievement of minimal disease activity (MDA) in overweight/obese patients with psoriatic arthritis (PsA) starting treatment with tumour necrosis factor α (TNFα) blockers. Methods Among subjects with PsA starting treatment with TNFα blockers, 138 overweight/obese patients received a concomitant dietary intervention (69 a hypocaloric diet (HD) and 69 a free-managed diet (FD)). Changes in metabolic variables were measured and a complete clinical rheumatological evaluation was made in all patients at baseline and after a 6-month follow-up to define the achievement of MDA. Results 126 subjects completed the study. MDA was more often achieved by HD than by FD subjects (HR=1.85, 95% CI 1.019 to 3.345, p=0.043). A diet was successful (≥5% weight loss) in 74 (58.7%) patients. Regardless of the type of diet, after 6 months of treatment with TNFα blockers, ≥5% of weight loss was a predictor of the achievement of MDA (OR=4.20, 95% CI 1.82 to 9.66, p<0.001). For increasing weight-loss categories (<5%, 5–10%, >10%), MDA was achieved by 23.1%, 44.8% and 59.5%, respectively. A higher rate of MDA achievement was found in subjects with 5–10% (OR=3.75, 95% CI 1.36 to 10.36, p=0.011) and in those with >10% (OR=6.67, 95% CI 2.41 to 18.41, p<0.001) weight loss in comparison with those with <5% weight loss. Conclusions Regardless of the type of diet, a successful weight loss (≥5% from baseline values) is associated with a higher rate of achievement of MDA in overweight/obese patients with PsA who start treatment with TNFα blockers. PMID:23771989

  18. Highly Active and Stable MgAl2O4 Supported Rh and Ir Catalysts for Methane Steam Reforming: A Combined Experimental and Theoretical Study

    SciTech Connect

    Mei, Donghai; Glezakou, Vassiliki Alexandra; Lebarbier, Vanessa MC; Kovarik, Libor; Wan, Haiying; Albrecht, Karl O.; Gerber, Mark A.; Rousseau, Roger J.; Dagle, Robert A.

    2014-07-01

    In this work we present a combined experimental and theoretical investigation of stable MgAl2O4 spinel-supported Rh and Ir catalysts for the steam methane reforming (SMR) reaction. Firstly, catalytic performance for a series of noble metal catalysts supported on MgAl2O4 spinel was evaluated for SMR at 600-850°C. Turnover rate at 850°C follows the order: Pd > Pt > Ir > Rh > Ru > Ni. However, Rh and Ir were found to have the best combination of activity and stability for methane steam reforming in the presence of simulated biomass-derived syngas. It was found that highly dispersed ~2 nm Rh and ~1 nm Ir clusters were formed on the MgAl2O4 spinel support. Scanning Transition Electron Microscopy (STEM) images show that excellent dispersion was maintained even under challenging high temperature conditions (e.g. at 850°C in the presence of steam) while Ir and Rh catalysts supported on Al2O3 were observed to sinter at increased rates under the same conditions. These observations were further confirmed by ab initio molecular dynamics (AIMD) simulations which find that ~1 nm Rh and Ir particles (50-atom cluster) bind strongly to the MgAl2O4 surfaces via a redox process leading to a strong metal-support interaction, thus helping anchor the metal clusters and reduce the tendency to sinter. Density functional theory (DFT) calculations suggest that these supported smaller Rh and Ir particles have a lower work function than larger more bulk-like ones, which enables them to activate both water and methane more effectively than larger particles, yet have a minimal influence on the relative stability of coke precursors. In addition, theoretical mechanistic studies were used to probe the relationship between structure and reactivity. Consistent with the experimental observations, our theoretical modeling results also suggest that the small spinel-supported Ir particle catalyst is more active than the counterpart of Rh catalyst for SMR. This work was financially supported by the

  19. The Head Start Debates

    ERIC Educational Resources Information Center

    Zigler, Edward, Ed.; Styfco, Sally J., Ed.

    2004-01-01

    The future of Head Start depends on how well people learn from and apply the lessons from its past. That's why everyone involved in early education needs this timely, forward-thinking book from the leader of Head Start. The first book to capture the Head Start debates in all their complexity and diversity, this landmark volume brings together the…

  20. Head Start Automation Manual.

    ERIC Educational Resources Information Center

    Maryland Univ., College Park. Univ. Coll.

    The task for the National Data Management Project is to share technological capabilities with the Head Start Community in order to implement improved services for children and families involved in Head Start. Many Head Start programs have incorporated technology into their programs, including word processing, database management systems,…

  1. Head Start Parent Involvement Activities: Measuring the Effect of School Based Parent Involvement Activities on Parent Efficacy in Early Childhood Learning

    ERIC Educational Resources Information Center

    Quadri, Khadijat O.

    2012-01-01

    Purpose: The purpose of this position paper was to examine the impact of school based parent involvement activities on parent efficacy. Methodology: The paper explores research studies into school based activities on long term parent efficacy. Conclusions: Most schools are involving parents in school-based activities in a variety of ways but the…

  2. Homicide by methane gas.

    PubMed

    De-Giorgio, Fabio; Grassi, Vincenzo M; Vetrugno, Giuseppe; Rossi, Riccardo; Fucci, Nadia; d'Aloja, Ernesto; Pascali, Vincenzo L

    2012-09-10

    Methane is a suffocating gas, and "methane deaths" are largely the result of suffocation by gas-air displacement after accidental or deliberate exposure. Neither methane gas nor other suffocating gases are a common means of homicide, with the potential exception of the use of gas in chemical weapons or gas chambers. Here, we report the case of a 53-year-old woman who was killed by her husband with methane gas. The man had given his wife a dose of Lorazepam before setting up a hose that conveyed methane from the kitchen into the apartment's bedroom. The man subsequently faked his own suicide, which was later discovered.

  3. Ultrasound-assisted polyol method for the preparation of SBA-15-supported ruthenium nanoparticles and the study of their catalytic activity on the partial oxidation of methane.

    PubMed

    Li, Hongliang; Wang, Renzhang; Hong, Qi; Chen, Luwei; Zhong, Ziyi; Koltypin, Yuri; Calderon-Moreno, J; Gedanken, Aharon

    2004-09-14

    Metallic Ru nanoparticles have been successfully produced and incorporated into the pores of SBA-15 in situ employing a simple ultrasound-assisted polyol method. The product has been confirmed by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy, where ultrasound provides both the energy for the reduction of the Ru(III) ion and the driving force for the loading of the Ru(0) nanoparticles into the SBA-15 pores. An ultrasound-assisted insertion mechanism has been proposed based on the microjets and shake-wave effect of the collapsed bubbles. The catalytic properties of the SBA-15-supported Ru nanoparticles have been tested by the partial oxidization of methane and show very high activity and high CO selectivity.

  4. Potential methane reservoirs beneath Antarctica.

    PubMed

    Wadham, J L; Arndt, S; 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

    2012-08-30

    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 evaluated. Large sedimentary basins containing marine sequences up to 14 kilometres thick and an estimated 21,000 petagrams (1 Pg equals 10(15) g) of organic carbon are buried beneath the Antarctic Ice Sheet. No data exist for rates of methanogenesis in sub-Antarctic marine sediments. Here we present experimental data from other subglacial environments that demonstrate the potential for overridden organic matter beneath glacial systems to produce methane. We also numerically simulate the accumulation of methane in Antarctic sedimentary basins using an established one-dimensional hydrate model and show that pressure/temperature conditions favour methane hydrate formation down to sediment depths of about 300 metres in West Antarctica and 700 metres in East Antarctica. Our results demonstrate the potential for methane hydrate accumulation in Antarctic sedimentary basins, where the total inventory depends on rates of organic carbon degradation and conditions at the ice-sheet bed. We calculate that the sub-Antarctic hydrate inventory could be of the same order of magnitude as that of recent estimates made for Arctic permafrost. Our findings suggest that the Antarctic Ice Sheet may be a neglected but important component of the global methane budget, with the potential to act as a positive feedback on climate warming during ice-sheet wastage.

  5. Methane photochemistry and methane production on Neptune

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  6. Methane photochemistry and methane production on Neptune

    SciTech Connect

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

    1988-06-01

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

  7. Methane photochemistry and methane production on Neptune

    NASA Astrophysics Data System (ADS)

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

    1988-06-01

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

  8. Clumped Methane Isotopologue Temperatures of Microbial Methane

    NASA Astrophysics Data System (ADS)

    Ono, S.; Wang, D. T.; Gruen, D.; Delwiche, K.; Hemond, H.; Pohlman, J.

    2014-12-01

    We will report the abundance of 13CH3D, a clumped isotopologue of methane, in microbial methane sampled from natural environments. They yield some expected and some unexpected results reflecting both equilibrium and kinetic isotope effects controlling the abundance of 13CH3D in low temperature environments. The four isotopologues of methane (12CH4, 13CH4, 12CH3D and 13CH3D) were measured by a tunable infrared spectroscopy method at a precision of 0.2‰ and accuracy of 0.5‰ (Ono et al., 2014). Similar to carbonate clumped isotope thermometry, clumped isotopologues of methane become more stable at lower temperatures. The equilibrium constant for the isotope exchange reaction 13CH4 + 12CH3D ⇌ 13CH3D + 12CH4 deviates from unity by +6.3 to +3.5 ‰ for methane equilibrated between 4 and 121 °C, a range expected for microbial methanogenesis. This would be measurably-distinct from a thermogenic methane signal, which typically have apparent 13CH3D-based temperatures ranging from 150 to 220 °C (+3.0 to +2.2 ‰ clumped isotope effect; Ono et al., 2014; Stolper et al. 2014). Marine samples, such as methane clathrates and porewater methane from the Cascadia margin, have 13CH3D-based temperatures that appear to be consistent with isotopic equilibration at in situ temperatures that are reasonable for deep sedimentary environments. In contrast, methane from freshwater environments, such as a lake and a swamp, yield apparent temperatures that are much higher than the known or inferred environmental temperature. Mixing of two or more distinct sources of methane could potentially generate this high temperature bias. We suggest, however, that this high-temperature bias likely reflects a kinetic isotope fractionation intrinsic to methanogenesis in fresh water environments. In contrast, the low-temperature signals from marine methane could be related to the slow metabolic rates and reversibility of microbial methanogenesis and methanotrophy in marine sedimentary environments

  9. Energy from anaerobic methane production. [Sweden

    SciTech Connect

    Not Available

    1982-02-01

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

  10. Method for removal of methane from coalbeds

    DOEpatents

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

    1976-01-01

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

  11. Theoretical consideration of methane emission from sediments.

    PubMed

    Bazhin, N M

    2003-01-01

    A stationary theory of gas emission from sedimentary (active) layers of wetlands is developed. The theory takes into account methane generation in a sedimentary layer (W1) and its depth dependence, (W1(z)), the solubility, determined by Henry's constant (K1), and the mobility of methane molecules set by the methane diffusion coefficient (D1). The exponential dependence of methane generation rate decay with depth is considered in more detail. The penetration of atmospheric nitrogen into the active layer is also taken into consideration. It is shown that the value of diffusion methane flux from sedimentary layers is proportional to square root(K1D1P0W10) where P0 characterizes the atmospheric pressure and W10 characterizes the maximum generation rate. Coefficients relating the diffusion methane flux to the square root(K1D1P0W10) value are calculated for the different depth dependencies of methane generation rate. The values of these coefficients are not much different from unity for most real cases.

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

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  13. Effect of the Children’s Health Activity Motor Program on Motor Skills and Self-Regulation in Head Start Preschoolers: An Efficacy Trial

    PubMed Central

    Robinson, Leah E.; Palmer, Kara K.; Bub, Kristen L.

    2016-01-01

    Self-regulatory skills are broadly defined as the ability to manage emotions, focus attention, and inhibit some behaviors while activating others in accordance with social expectations and are an established indicator of academic success. Growing evidence links motor skills and physical activity to self-regulation. This study examined the efficacy of a motor skills intervention (i.e., the Children’s Health Activity Motor Program, CHAMP) that is theoretically grounded in Achievement Goal Theory on motor skill performance and self-regulation in Head Start preschoolers. A sample of 113 Head Start preschoolers (Mage = 51.91 ± 6.5 months; 49.5% males) were randomly assigned to a treatment (n = 68) or control (n = 45) program. CHAMP participants engaged in 15, 40-min sessions of a mastery climate intervention that focused on the development of motor skills over 5 weeks while control participants engaged in their normal outdoor recess period. The Delay of Gratification Snack Task was used to measure self-regulation and the Test of Gross Motor Development-2nd Edition was used to assess motor skills. All measures were assessed prior to and following the intervention. Linear mixed models were fit for both self-regulation and motor skills. Results revealed a significant time × treatment interaction (p < 0.001). In regard to motor skills, post hoc comparisons found that all children improved their motor skills (p < 0.05), but the CHAMP group improved significantly more than the control group (p < 0.001). Children in CHAMP maintained their self-regulation scores across time, while children in the control group scored significantly lower than the CHAMP group at the posttest (p < 0.05). CHAMP is a mastery climate movement program that enhance skills associated with healthy development in children (i.e., motor skills and self-regulation). This efficacy trial provided evidence that CHAMP helped maintain delay of gratification in preschool

  14. Effect of the Children's Health Activity Motor Program on Motor Skills and Self-Regulation in Head Start Preschoolers: An Efficacy Trial.

    PubMed

    Robinson, Leah E; Palmer, Kara K; Bub, Kristen L

    2016-01-01

    Self-regulatory skills are broadly defined as the ability to manage emotions, focus attention, and inhibit some behaviors while activating others in accordance with social expectations and are an established indicator of academic success. Growing evidence links motor skills and physical activity to self-regulation. This study examined the efficacy of a motor skills intervention (i.e., the Children's Health Activity Motor Program, CHAMP) that is theoretically grounded in Achievement Goal Theory on motor skill performance and self-regulation in Head Start preschoolers. A sample of 113 Head Start preschoolers (Mage = 51.91 ± 6.5 months; 49.5% males) were randomly assigned to a treatment (n = 68) or control (n = 45) program. CHAMP participants engaged in 15, 40-min sessions of a mastery climate intervention that focused on the development of motor skills over 5 weeks while control participants engaged in their normal outdoor recess period. The Delay of Gratification Snack Task was used to measure self-regulation and the Test of Gross Motor Development-2nd Edition was used to assess motor skills. All measures were assessed prior to and following the intervention. Linear mixed models were fit for both self-regulation and motor skills. Results revealed a significant time × treatment interaction (p < 0.001). In regard to motor skills, post hoc comparisons found that all children improved their motor skills (p < 0.05), but the CHAMP group improved significantly more than the control group (p < 0.001). Children in CHAMP maintained their self-regulation scores across time, while children in the control group scored significantly lower than the CHAMP group at the posttest (p < 0.05). CHAMP is a mastery climate movement program that enhance skills associated with healthy development in children (i.e., motor skills and self-regulation). This efficacy trial provided evidence that CHAMP helped maintain delay of gratification in preschool

  15. Methane monooxygenase from Methylosinus trichosporium OB3b. Purification and properties of a three-component system with high specific activity from a type II methanotroph.

    PubMed

    Fox, B G; Froland, W A; Dege, J E; Lipscomb, J D

    1989-06-15

    Methane monooxygenase has been purified from the Type II methanotroph Methylosinus trichosporium OB3b. As observed for methane monooxygenase isolated from Type I methanotrophs, three protein components are required: a 39.7-kDa NADH reductase containing 1 mol each of FAD and a [2Fe-2S] cluster, a 15.8-kDa protein factor termed component B that contains no metals or cofactors, and a 245-kDa hydroxylase which appears to contain an oxo- or hydroxo-bridged binuclear iron cluster. Through the use of stabilizing reagents, the hydroxylase is obtained in high yield and exhibits a specific activity 8-25-fold greater than reported for previous preparations. The component B and reductase exhibit 1.5- and 4-fold greater specific activity, respectively. Quantitation of the hydroxylase oxo-bridged cluster using EPR and Mössbauer spectroscopies reveals that the highest specific activity preparations (approximately 1700 nmol/min/mg) contain approximately 2 clusters/mol. In contrast, hydroxylase preparations exhibiting a wide range of specific activities below 500 nmol/min/mg contain approximately 1 cluster/mol on average. Efficient turnover coupled to NADH oxidation requires all three protein components. However, both alkanes and alkenes are hydroxylated by the chemically reduced hydroxylase under single turnover conditions in the absence of component B and the reductase. Neither of these components catalyzes hydroxylation individually nor do they significantly affect the yield of hydroxylated product from the chemically reduced hydroxylase. Hydroxylase reduced only to the mixed valent [Fe(II).Fe(III)] state is unreactive toward O2 and yields little hydroxylated product on single turnover. This suggests that the catalytically active species is the fully reduced form. The data presented here provide the first evidence based on catalysis that the site of the monooxygenation reaction is located on the hydroxylase. It thus appears likely that the oxo-bridged iron cluster is capable of

  16. One millimetre makes the difference: high-resolution analysis of methane-oxidizing bacteria and their specific activity at the oxic-anoxic interface in a flooded paddy soil.

    PubMed

    Reim, Andreas; Lüke, Claudia; Krause, Sascha; Pratscher, Jennifer; Frenzel, Peter

    2012-11-01

    Aerobic methane-oxidizing bacteria (MOB) use a restricted substrate range, yet >30 species-equivalent operational taxonomical units (OTUs) are found in one paddy soil. How these OTUs physically share their microhabitat is unknown. Here we highly resolved the vertical distribution of MOB and their activity. Using microcosms and cryosectioning, we sub-sampled the top 3-mm of a water-saturated soil at near in situ conditions in 100-μm steps. We assessed the community structure and activity using the particulate methane monooxygenase gene pmoA as a functional and phylogenetic marker by terminal restriction fragment length polymorphism (t-RFLP), a pmoA-specific diagnostic microarray, and cloning and sequencing. pmoA genes and transcripts were quantified using competitive reverse transcriptase PCR combined with t-RFLP. Only a subset of the methanotroph community was active. Oxygen microprofiles showed that 89% of total respiration was confined to a 0.67-mm-thick zone immediately above the oxic-anoxic interface, most probably driven by methane oxidation. In this zone, a Methylobacter-affiliated OTU was highly active with up to 18 pmoA transcripts per cell and seemed to be adapted to oxygen and methane concentrations in the micromolar range. Analysis of transcripts with a pmoA-specific microarray found a Methylosarcina-affiliated OTU associated with the surface zone. High oxygen but only nanomolar methane concentrations at the surface suggested an adaptation of this OTU to oligotrophic conditions. No transcripts of type II methanotrophs (Methylosinus, Methylocystis) were found, which indicated that this group was represented by resting stages only. Hence, different OTUs within a single guild shared the same microenvironment and exploited different niches.

  17. What Happens at the Lesson Start?

    ERIC Educational Resources Information Center

    Saloviita, Timo

    2016-01-01

    Transitional periods, such as lesson starts, are necessary steps from one activity to another, but they also compete with time for actual learning. The aim of the present study was to replicate a previous pilot study on lesson starts and explore possible disturbances. In total, 130 lesson starts in Finnish basic education in grades 1-9 were…

  18. Mars methane engine

    NASA Technical Reports Server (NTRS)

    Bui, Hung; Coletta, Chris; Debois, Alain

    1994-01-01

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

  19. The relationship between methane migration and shale-gas well operations near Dimock, Pennsylvania, USA

    NASA Astrophysics Data System (ADS)

    Hammond, Patrick A.

    2016-03-01

    Migration of stray methane gas near the town of Dimock, Pennsylvania, has been at the center of the debate on the safety of shale gas drilling and hydraulic fracturing in the United States. The presented study relates temporal variations in molecular concentrations and stable isotope compositions of methane and ethane to shale-gas well activity (i.e., vertical/horizontal drilling, hydraulic fracturing and remedial actions). This was accomplished by analyzing data collected, between 2008 and 2012, by state and federal agencies and the gas well operator. In some cases, methane migration started prior to hydraulic fracturing. Methane levels of contaminated water wells sampled were one to several orders of magnitude greater than the concentrations due to natural variation in water wells of the local area. Isotope analyses indicate that all samples had a thermogenic origin at varying maturity levels, but from formations above the hydraulically fractured Marcellus Shale. The results from the initial water well samples were similar to annular gas values, but not those of production gases. This indicates that leakage by casing cement seals most likely caused the impacts, not breaks in the production casing walls. Remediation by squeeze cementing was partially effective in mitigating impacts of gas migration. In several cases where remediation caused a substantial reduction in methane levels, there were also substantial changes in the isotope values, providing evidence of two sources, one natural and the other man-induced. Sampling water wells while venting gas wells appears to be a cost-effective method for determining if methane migration has occurred.

  20. Starting up microbial enhanced oil recovery.

    PubMed

    Siegert, Michael; Sitte, Jana; Galushko, Alexander; Krüger, Martin

    2014-01-01

    This chapter gives the reader a practical introduction into microbial enhanced oil recovery (MEOR) including the microbial production of natural gas from oil. Decision makers who consider the use of one of these technologies are provided with the required scientific background as well as with practical advice for upgrading an existing laboratory in order to conduct microbiological experiments. We believe that the conversion of residual oil into natural gas (methane) and the in situ production of biosurfactants are the most promising approaches for MEOR and therefore focus on these topics. Moreover, we give an introduction to the microbiology of oilfields and demonstrate that in situ microorganisms as well as injected cultures can help displace unrecoverable oil in place (OIP). After an initial research phase, the enhanced oil recovery (EOR) manager must decide whether MEOR would be economical. MEOR generally improves oil production but the increment may not justify the investment. Therefore, we provide a brief economical assessment at the end of this chapter. We describe the necessary state-of-the-art scientific equipment to guide EOR managers towards an appropriate MEOR strategy. Because it is inevitable to characterize the microbial community of an oilfield that should be treated using MEOR techniques, we describe three complementary start-up approaches. These are: (i) culturing methods, (ii) the characterization of microbial communities and possible bio-geochemical pathways by using molecular biology methods, and (iii) interfacial tension measurements. In conclusion, we hope that this chapter will facilitate a decision on whether to launch MEOR activities. We also provide an update on relevant literature for experienced MEOR researchers and oilfield operators. Microbiologists will learn about basic principles of interface physics needed to study the impact of microorganisms living on oil droplets. Last but not least, students and technicians trying to understand

  1. Head Start. Fact Sheet.

    ERIC Educational Resources Information Center

    Administration for Children, Youth, and Families (DHHS), Washington, DC.

    Head Start is a national program that provides comprehensive developmental services for preschool children (ages 3 to 5) from low-income families and social services for their families. Approximately 1,400 community-based nonprofit organizations and school systems develop programs to meet specific needs. Head Start began in 1965 in the Office of…

  2. Start at the End ...

    ERIC Educational Resources Information Center

    Goldsworthy, Anne

    2005-01-01

    Start at the end; that's the way to improve children's plans for investigations. Strange as it may seem, there are times when beginning at the beginning of an investigation is not the best way to start things off. To give children the opportunity to ask questions and plan what to do, sometimes it is best to get them first to consider others' data…

  3. Starting School in August

    ERIC Educational Resources Information Center

    Chmelynski, Carol

    2006-01-01

    In this article, the author discusses the controversial decision of the school board from the Broward County, Florida to start the school year on August 9. School boards across the country that are grappling with the idea of starting school earlier in the year are increasingly running up against strong opposition from parents. In many districts,…

  4. Detecting Methane Leaks

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  5. Methane on Mars: Measurements and Possible Origins

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  6. Transcriptomic evidence for net methane oxidation and net methane production in putative ANaerobic MEthanotrophic (ANME) archaea

    NASA Astrophysics Data System (ADS)

    Lloyd, K. G.; Alperin, M. J.; Teske, A.

    2010-12-01

    Anaerobic methane oxidation regulates methane emissions in marine sediments and is thought to be mediated by uncultured methanogen-like archaea collectively labeled ANME (for ANaerobic MEthanotrophs). ANME archaea are often assumed to be obligate methanotrophs that are incapable of net methanogenesis, and are therefore used as proxies for anaerobic methane oxidation in many environments in spite of uncertainty regarding their metabolic capabilities. We tested this assumption by detecting and quantifying methanogenic gene transcription of ANME archaea across clearly differentiated zones of methane oxidation vs. methane production in sediments from the White Oak River estuary, NC. ANME-1 archaea (a group of putative obligate methanotrophs) consistently transcribe 16S rRNA and mRNA of methyl coenzyme M reductase (mcrA) the key gene for methanogenesis, up to 45 cm into methanogenic sediments. CARD-FISH shows that ANME-1 archaea exist as single rod-shaped cells or pairs of cells, and in very low numbers. Integrating normalized depth-distributions of 16S rDNA and rRNA (measured with qPCR and RT-qPCR, respectively) shows that 26-77 % of the rDNA proxy for ANME-1 cell numbers, and 18-74 % of the rRNA proxy for ANME-1 activity occurs within methane-producing sediments. mRNA transcripts of dissimilatory sulfite reductase (dsrAB) from sulfate reducing bacteria, the putative syntrophic partners of sulfate-dependent methane oxidation, were amplified consistently from methane-oxidizing sediments, and inconsistently from methane-producing sediments. These results change the perspective from ANME-1 archaea as obligate methane oxidizers to methanogens that are also capable of methane oxidation.

  7. START II and beyond

    SciTech Connect

    Mendelsohn, J.

    1996-10-01

    The second Strategic Arms Reduction Treaty (START II), signed by President George Bush and Russian President Boris yeltsin in January 1993, was ratified by the US Senate in January 1996 by and overwhelming vote of 87-4. The treaty, which will slash the strategic arsenals of the United States and Russia to 3,000-3,500 warheads each, is now before the two houses of the Russian Parliament (the Duma and the Federation Council) awaiting ratification amidst confusion and criticism. The Yeltsin administration supports START II and spoke in favor of Russian ratification after the Senate acted on the treaty. The Russian foreign minister and the Russian military believed that START II should be ratified as soon as possible. During the recent presidential campaign and his subsequent illness, President Yeltsin has been virtually silent on the subject of START II and nuclear force reductions. Without a push from the Yeltsin administration, the tone among Duma members, has been sharply critical of START II. Voices across the Russian political spectrum have questioned the treaty and linked it to constraints on highly capable theater missile defense (TMD) systems and the continued viability of the ABM Treaty. And urged that START II ratification be held hostage until NATO abandons its plans to expand eastward. Although the START I and START II accords have generated the momentum, opportunity and expectation-both domestic and international-for additional nuclear arms reductions, the current impasse over ratification in the Duma has cast a shadow over the future of START II and raised questions about the chances for any follow-on (START III) agreement.

  8. dKDM5/LID regulates H3K4me3 dynamics at the transcription-start site (TSS) of actively transcribed developmental genes.

    PubMed

    Lloret-Llinares, Marta; Pérez-Lluch, Sílvia; Rossell, David; Morán, Tomás; Ponsa-Cobas, Joan; Auer, Herbert; Corominas, Montserrat; Azorín, Fernando

    2012-10-01

    H3K4me3 is a histone modification that accumulates at the transcription-start site (TSS) of active genes and is known to be important for transcription activation. The way in which H3K4me3 is regulated at TSS and the actual molecular basis of its contribution to transcription remain largely unanswered. To address these questions, we have analyzed the contribution of dKDM5/LID, the main H3K4me3 demethylase in Drosophila, to the regulation of the pattern of H3K4me3. ChIP-seq results show that, at developmental genes, dKDM5/LID localizes at TSS and regulates H3K4me3. dKDM5/LID target genes are highly transcribed and enriched in active RNApol II and H3K36me3, suggesting a positive contribution to transcription. Expression-profiling show that, though weakly, dKDM5/LID target genes are significantly downregulated upon dKDM5/LID depletion. Furthermore, dKDM5/LID depletion results in decreased RNApol II occupancy, particularly by the promoter-proximal Pol llo(ser5) form. Our results also show that ASH2, an evolutionarily conserved factor that locates at TSS and is required for H3K4me3, binds and positively regulates dKDM5/LID target genes. However, dKDM5/LID and ASH2 do not bind simultaneously and recognize different chromatin states, enriched in H3K4me3 and not, respectively. These results indicate that, at developmental genes, dKDM5/LID and ASH2 coordinately regulate H3K4me3 at TSS and that this dynamic regulation contributes to transcription.

  9. Starting physiology: bioelectrogenesis.

    PubMed

    Baptista, Vander

    2015-12-01

    From a Cartesian perspective of rational analysis, the electric potential difference across the cell membrane is one of the fundamental concepts for the study of physiology. Unfortunately, undergraduate students often struggle to understand the genesis of this energy gradient, which makes the teaching activity a hard task for the instructor. The topic of bioelectrogenesis encompasses multidisciplinary concepts, involves several mechanisms, and is a dynamic process, i.e., it never turns off during the lifetime of the cell. Therefore, to improve the transmission and acquisition of knowledge in this field, I present an alternative didactic model. The design of the model assumes that it is possible to build, in a series of sequential steps, an assembly of proteins within the membrane of an isolated cell in a simulated electrophysiology experiment. Initially, no proteins are inserted in the membrane and the cell is at a baseline energy state; the extracellular and intracellular fluids are at thermodynamic equilibrium. Students are guided through a sequence of four steps that add key membrane transport proteins to the model cell. The model is simple at the start and becomes progressively more complex, finally producing transmembrane chemical and electrical gradients. I believe that this didactic approach helps instructors with a more efficient tool for the teaching of the mechanisms of resting membrane potential while helping students avoid common difficulties that may be encountered when learning this topic.

  10. Authigenic carbonate mounds from active methane seeps on the southern Aquitaine Shelf (Bay of Biscay, France): Evidence for anaerobic oxidation of biogenic methane and submarine groundwater discharge during formation

    NASA Astrophysics Data System (ADS)

    Pierre, Catherine; Demange, Jérome; Blanc-Valleron, Marie-Madeleine; Dupré, Stéphanie

    2017-02-01

    The widespread methane emissions that were discovered in 2013 on the Aquitaine Shelf at water depth between 140 and 220 m are associated with authigenic carbonate crusts that cover meter-high subcircular reliefs of 10-100 m in diameter. These authigenic carbonates are primarily aragonite plus calcite and dolomite, which cement the fine- to medium-grained sandy sediment. The carbonate cement is often pierced by numerous circular cavities of 5-10 μm in diameter that are considered to be moulds of gas bubbles. Conversely, micron-sized cavities in the aragonite crystals are attributed to dissolution features, in relation to the production of CO2 during the aerobic oxidation of methane. The oxygen isotopic compositions of bulk carbonate (+1.7 to +3.7‰) and aragonite cements obtained from microsampling (-0.1 to +1.4‰) indicate that these carbonates were precipitated in mixtures of seawater and freshwater, i.e., in the context of submarine groundwater discharge at the seafloor. The carbon isotopic compositions of authigenic carbonates (-51.9 to -38.1‰) and of aragonite cements (-49.9 to -29.3‰) show that the dissolved inorganic carbon of pore fluids was mostly produced by the anaerobic oxidation of biogenic methane and also partly from the groundwater system.

  11. Characterization of Metabolically Active Bacterial Populations in Subseafloor Nankai Trough Sediments above, within, and below the Sulfate–Methane Transition Zone

    PubMed Central

    Mills, Heath J.; Reese, Brandi Kiel; Shepard, Alicia K.; Riedinger, Natascha; Dowd, Scot E.; Morono, Yuki; Inagaki, Fumio

    2012-01-01

    A remarkable number of microbial cells have been enumerated within subseafloor sediments, suggesting a biological impact on geochemical processes in the subseafloor habitat. However, the metabolically active fraction of these populations is largely uncharacterized. In this study, an RNA-based molecular approach was used to determine the diversity and community structure of metabolically active bacterial populations in the upper sedimentary formation of the Nankai Trough seismogenic zone. Samples used in this study were collected from the slope apron sediment overlying the accretionary prism at Site C0004 during the Integrated Ocean Drilling Program Expedition 316. The sediments represented microbial habitats above, within, and below the sulfate–methane transition zone (SMTZ), which was observed approximately 20 m below the seafloor (mbsf). Small subunit ribosomal RNA were extracted, quantified, amplified, and sequenced using high-throughput 454 pyrosequencing, indicating the occurrence of metabolically active bacterial populations to a depth of 57 mbsf. Transcript abundance and bacterial diversity decreased with increasing depth. The two communities below the SMTZ were similar at the phylum level, however only a 24% overlap was observed at the genus level. Active bacterial community composition was not confined to geochemically predicted redox stratification despite the deepest sample being more than 50 m below the oxic/anoxic interface. Genus-level classification suggested that the metabolically active subseafloor bacterial populations had similarities to previously cultured organisms. This allowed predictions of physiological potential, expanding understanding of the subseafloor microbial ecosystem. Unique community structures suggest very diverse active populations compared to previous DNA-based diversity estimates, providing more support for enhancing community characterizations using more advanced sequencing techniques. PMID:22485111

  12. Detection of Abiotic Methane in Terrestrial Continental Hydrothermal Systems: Implications for Methane on Mars

    NASA Technical Reports Server (NTRS)

    Socki, Richard A.; Niles, Paul B.; Gibson, Everett K., Jr.; Romanek, Christopher S.; Zhang, Chuanlun L.; Bissada, Kadry K.

    2008-01-01

    The recent detection of methane in the Martian atmosphere and the possibility that its origin could be attributed to biological activity, have highlighted the importance of understanding the mechanisms of methane formation and its usefulness as a biomarker. Much debate has centered on the source of the methane in hydrothermal fluids, whether it is formed biologically by microorganisms, diagenetically through the decomposition of sedimentary organic matter, or inorganically via reduction of CO2 at high temperatures. Ongoing research has now shown that much of the methane present in sea-floor hydrothermal systems is probably formed through inorganic CO2 reduction processes at very high temperatures (greater than 400 C). Experimental results have indicated that methane might form inorganically at temperatures lower still, however these results remain controversial. Currently, methane in continental hydrothermal systems is thought to be formed mainly through the breakdown of sedimentary organic matter and carbon isotope equilibrium between CO2 and CH4 is thought to be rarely present if at all. Based on isotopic measurements of CO2 and CH4 in two continental hydrothermal systems, we suggest that carbon isotope equilibration exists at temperatures as low as 155 C. This would indicate that methane is forming through abiotic CO2 reduction at lower temperatures than previously thought and could bolster arguments for an abiotic origin of the methane detected in the martian atmosphere.

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

    PubMed

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

    2015-01-01

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

  14. The future of methane

    SciTech Connect

    Howell, D.G.

    1995-12-31

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

  15. Methanation assembly using multiple reactors

    DOEpatents

    Jahnke, Fred C.; Parab, Sanjay C.

    2007-07-24

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

  16. Enhanced Electrode Activity of Ni/(CeO2)1-x(TiO2)x Anode in Electrochemical Oxidation of Methane

    NASA Astrophysics Data System (ADS)

    Kanjanaboonmalert, Tanawat; Tzu, Teoh Wah; Sato, Kazunori

    2011-03-01

    The electrode activity of a newly developed Ni/(CeO2)1-x(TiO2)x cermet anode has been investigated at intermediate temperatures. (CeO2)1-x(TiO2)x mixed oxide powders were synthesized by the sol-gel method. A single cell, Ni/(CeO2)1-x(TiO2)x|Sm0.2Ce0.8O3|Sm0.5Sr0.5CoO3, was fabricated using a samarium-doped ceria disk. The effect of incorporating TiO2 into the CeO2 matrix was studied with the goal of improving the anode micro structure. The modified micro structure of the new Ni/(CeO2)0.8(TiO2)0.2 cermet anode, which consists of fine Ni particles distributed on (CeO2)0.8(TiO2)0.2 mixed oxide particles, enhances the electrode activity in methane oxidation.

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

    NASA Astrophysics Data System (ADS)

    Viscardy, Sébastien; Daerden, Frank; Neary, Lori

    2016-10-01

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

  18. The mechanism of the partial oxidation of methane

    NASA Astrophysics Data System (ADS)

    Sinev, Mikhail Yu; Korshak, V. N.; Krylov, Oleg V.

    1989-01-01

    The principal characteristics of the homogeneous and heterogeneous-catalytic conversion of methane into condensation products (C2 and C3 hydrocarbons) and partial oxidation products (methanol and formaldehyde) are considered. Data are presented concerning the most effective catalysts and data relating to the mechanism of the activation of methane on oxide and oxide halide catalysts, the nature of the active centres, and the kinetics of the partial oxidation of methane are analysed. It is shown that the oxidative condensation of methane in the presence of the catalysts considered is a heterogeneous-homogeneous process, which imposes special requirements in its practical realisation. The bibliography includes 118 references.

  19. Methane metabolism in a temperate swamp

    SciTech Connect

    Amaral, J.A.; Knowles, R.

    1994-11-01

    Methane production has received much attention due not only to its importance as a terminal step in anaerobic organic matter degradation but also to its potentially significant role in climatic change and atmospheric chemistry. Wetlands are an important source and potential reservoir of methane, but the factors controlling its production and emission are not fully understood. This study examined in situ availability of substrates and the distribution of electron acceptors in a temperate peat swamp to determine how the chemistry and microbiology of the site affects methane production. Measurements were obtained in summer, fall and spring at two sites. Laboratory incubations with slurried peat soil were carried out. From the results, the authors speculate that along with differences in hydrology and chemical characteristics, heterogeneity in microbial activity may also contribute to the spatial variability of methane production and emission in wetlands. 45 refs., 6 figs., 4 tabs.

  20. Psychiatric Advance Directives: Getting Started

    MedlinePlus

    ... More... Home Getting Started National Resource Center on Psychiatric Advance Directives - Getting Started Getting Started Psychiatric advance directives (PADs) are relatively new legal instruments ...

  1. Hypersonic Methane Probed by CRDS

    NASA Astrophysics Data System (ADS)

    Louviot, M.; Boudon, V.; Suas-David, N.; Georges, R.; Kassi, S.; Rey, M.

    2014-06-01

    A new cavity ring-down spectroscopy device, designed to study hypersonic gas jets, started to yield encouraging results at the Institut de Physique de Rennes (IPR). In this experiment, two mixtures have been used: first, a mixture of argon and carbon monoxide and second, a mixture of argon and methane. Mixtures were contained at high pressure in a reservoir (˜ 1000 Torr) and heated at very high temperature (˜ 2000 K), thanks to the high enthalpy source developed at IPR1. A hypersonic gas expansion was produced in a low-pressure chamber (˜ 0.09 Torr) connected to the reservoir. High-resolution spectra of methane have thus been investigated in the [59206030] cm-1 spectral range, which corresponds to the Tetradecad region of methane. The CRD spectrometer, developed by the LAME group from the LIPhy laboratory in Grenoble, has been placed perpendicularly to the axis of the jet to record these spectra. The precise analysis of the CO lines helped to determine the different parameters of the jet: translational, rotational and vibrational temperatures, concentrations of the hot and cold gas. One of the most noteworthy results is the evidence of a strong thermodynamic disequilibrium of CO, with a rotational temperature of 7 K and a vibrational temperature of 2000 K. This confirms the weak vibrational relaxation of the molecules in the jet. Then, the parameters determined for CO gave a starting point for the simulation of the spectrum of methane. Thereupon, they were fitted in order to make the simulation match the experimental results for CH4. The simulation for CH4 was obtained from the HITRAN 2012 linelist2, for the cold bands (Tetradecad-GS), and from a variational calculation from the GSMA laboratory in Reims3, for the hot bands (Icosad-Dyad). The vibrational temperature is finally about 750 K and the rotational temperature, about 13 K. This rotational simplification is particularly useful for the identification of hot band lines, that is very more difficult in a

  2. Geoengineering treatment of methane

    NASA Astrophysics Data System (ADS)

    Lockley, Andrew; Gardian, Alan

    2010-05-01

    Methane is a significant GHG, and substantial reservoirs are vulnerable to instability due to AGW. Excursions, from permafrost and clathrates especially, act a positive feedback to AGW. Existing concentrations of well-mixed atmospheric methane substantially exceed pre-industrial levels. Various geoengineering methods are herein proposed for containment of methane, and/or accelerated oxidation to CO2 (a gas with a lower GWP over all timescales). A basic qualitative analysis of each technique is undertaken, to direct further study. Consideration is also given to the potential capacity of each technique to treat the total likely excursions of methane expected as a result of AGW. Proposed techniques: Section 0 SRM (comparison option) Section 1 Pre-emptive treatment of methane reservoirs Soil heating (polytunnels, heat pumps); Soil aeration; Mining of clathrates; Burning of clathrates Section 2 Remediation of aquatic methane excursions Lake sealing; Mixing of aquatic strata; Bubble capture; Lake aeration; Biological oxidation in aquatic environments Section 3 Remediation of concentrated atmospheric methane Regenerative thermal oxidation; Electrical ignition; Thermal ignition; Using incendiary munitions Section 4 Remediation of diffuse atmospheric methane Thermal oxidation by concentrated solar power; Compression ignition; Chemical degradation Assessment criteria: Infrastructure/implementation cost; Energy cost; Expected efficacy; Complexity/development path; Environmental impacts; Potential for CCS

  3. Methane as raw material in synthetic chemistry: the final frontier.

    PubMed

    Caballero, Ana; Pérez, Pedro J

    2013-12-07

    In spite of its large availability in natural or shale gas deposits, the use of methane in the chemical industry as feedstock from a synthetic point of view yet constitutes a challenge in modern chemistry. Only the production of the so-called syngas, a mixture of CO and H2 derived from the complete cleavage of the methane molecule, operates at the industrial level. The relevance of methane in the current industry, mainly toward methanol production, is described in this Tutorial. The methanol economy has been already proposed as an alternative to current fuel sources. Methanol synthesis directly from methane would imply the activation of the latter. Toward this end, the different methodologies reported to activate methane with transition metal complexes as well as the few examples of the catalytic functionalization of methane are presented.

  4. Towards Understanding Methane Emissions from Abandoned ...

    EPA Pesticide Factsheets

    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.

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

    NASA Astrophysics Data System (ADS)

    Conrad, Ralf

    2016-04-01

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

  6. Radiocarbon Evidence for Active Turnover of Pore-Water Dissolved Organic Carbon in the Methanogenic and Sulfate-Methane-Transition Zones of Santa Barbara Basin Sediments

    NASA Astrophysics Data System (ADS)

    Komada, T.; Li, H. L.; Cada, A. K.; Burdige, D.; Magen, C.; Chanton, J.; Grose, A. M.

    2014-12-01

    Diverse metabolic activities have been documented in the deep biosphere. However, how these activities affect carbon cycling in the subsurface, and how they in turn affect the marine and global cycles of carbon are still unclear. Here we present natural-abundance 14C and 13C data from the uppermost 4.5 m of the sediments of the Santa Barbara Basin, California Borderland, showing active turnover of dissolved organic carbon (DOC) within, and immediately below, the sulfate-methane transition zone (SMTZ; ~1.25 m). DOC concentrations increased with depth throughout the core, indicating net production within the sediment column. Enhanced DOC production was observed near the sediment-water interface, and also at ~30 cm below the SMTZ (~1.55 m). ∆14C values of DOC increased across the sediment-water interface, then decreased with depth, consistent with net production of modern DOC near the sediment-water interface, and input of 14C-depleted DOC from deeper horizons. An isotope mixing plot constructed with these data shows that the DOC diffusing upward at the base of the core is devoid of 14C, yet the DOC diffusing into and out of the SMTZ is relatively enriched (-460‰ and -300‰, respectively). This difference in 14C content of the DOC flux can only be reconciled if the following two are occurring within, and immediately below, the SMTZ: (1) >90% of the 14C-dead basal DOC flux is removed from the pore water (by, e.g., oxidation, fermentation, methanogenesis, precipitation), and (2) this DOC is replaced by material produced in this region at a rate that exceeds the upward basal flux. The 14C and 13C signatures suggest sedimentary organic matter to be the dominant source of DOC in process (2). Our data provide a unique insight into the active transformation of DOC and sedimentary organic matter in the subsurface.

  7. Strategy to eliminate catalyst hot-spots in the partial oxidation of methane: enhancing its activity for direct hydrogen production by reducing the reactivity of lattice oxygen.

    PubMed

    Wen, Cun; Liu, Yi; Guo, Yun; Wang, Yanqin; Lu, Guanzhong

    2010-02-14

    Hydrogen can be produced over Er(2)O(3) in methane oxidation (oxygen/methane = 26). The reactivity of lattice oxygen in the catalyst plays a main role in the conversion of surface hydroxyl species to hydrogen or water. Adding a rare earth element into a catalyst can reduce the reactivity of lattice oxygen, resulting in increased hydrogen production, to eliminate catalyst hot-spots.

  8. Detection of methane in the atmosphere of Mars.

    PubMed

    Formisano, Vittorio; Atreya, Sushil; Encrenaz, Thérèse; Ignatiev, Nikolai; Giuranna, Marco

    2004-12-03

    We report a detection of methane in the martian atmosphere by the Planetary Fourier Spectrometer onboard the Mars Express spacecraft. The global average methane mixing ratio is found to be 10 +/- 5 parts per billion by volume (ppbv). However, the mixing ratio varies between 0 and 30 ppbv over the planet. The source of methane could be either biogenic or nonbiogenic, including past or present subsurface microorganisms, hydrothermal activity, or cometary impacts.

  9. Enhanced DNA repair of bleomycin-induced 3'-phosphoglycolate termini at the transcription start sites of actively transcribed genes in human cells.

    PubMed

    Murray, Vincent; Chen, Jon K; Galea, Anne M

    2014-11-01

    The anti-tumour agent, bleomycin, cleaves DNA to give 3'-phosphoglycolate and 5'-phosphate termini. The removal of 3'-phosphoglycolate to give 3'-OH ends is a very important step in the DNA repair of these lesions. In this study, next-generation DNA sequencing was utilised to investigate the repair of these 3'-phosphoglycolate termini at the transcription start sites (TSSs) of genes in HeLa cells. The 143,600 identified human TSSs in HeLa cells comprised 82,596 non-transcribed genes and 61,004 transcribed genes; and the transcribed genes were divided into quintiles of 12,201 genes comprising the top 20%, 20-40%, 40-60%, 60-80%, 80-100% of expressed genes. Repair of bleomycin-induced 3'-phosphoglycolate termini was enhanced at actively transcribed genes. The top 20% and 20-40% quintiles had a very similar level of enhanced repair, the 40-60% quintile was intermediate, while the 60-80% and 80-100% quintiles were close to the low level of enhancement found in non-transcribed genes. There were also interesting differences regarding bleomycin repair on the sense and antisense strands of DNA at TSSs. The sense strand had highly enhanced repair between 0 and 250bp relative to the TSS, while for the antisense strand highly enhanced repair was between 150 and 450bp. Repair of DNA damage is a major mechanism of resistance to anti-tumour drugs and this study provides an insight into this process in human tumour cells.

  10. Long-term Outcomes of the FRESH START Trial: Exploring the Role of Self-efficacy in Cancer Survivors’ Maintenance of Dietary Practices and Physical Activity

    PubMed Central

    Mosher, Catherine E.; Lipkus, Isaac; Sloane, Richard; Snyder, Denise C.; Lobach, David F.; Demark-Wahnefried, Wendy

    2012-01-01

    Objective This study examined whether changes in self-efficacy explain the effects of a mailed print intervention on long-term dietary practices of breast and prostate cancer survivors. The relationship between change in self-efficacy and long-term physical activity (PA) also was examined. Methods Breast and prostate cancer survivors (N=543) from 39 U.S. states and two Canadian provinces participated in the FRESH START intervention trial. Participants were randomly assigned to receive a 10-month program of mailed print materials on diet and PA available in the public domain or a 10-month program of tailored materials designed to increase fruit and vegetable (F&V) intake, decrease fat intake, and/or increase PA. Changes in self-efficacy for F&V intake and fat restriction were analyzed as potential mediators of the intervention’s effects on diet at 2-year follow-up. Because we previously found that change in self-efficacy for PA did not vary by group assignment, the relationship between change in self-efficacy and PA at 2-year follow-up was examined across study conditions. Results Results suggest that change in self-efficacy for fat restriction partially explained the intervention’s effect on fat intake (mean indirect effect=-.28), and change in self-efficacy for F&V consumption partially explained the intervention’s effect on daily F&V intake (mean indirect effect=.11). Change in self-efficacy for fat restriction partially accounted for the intervention’s impact on overall diet quality among men only (mean indirect effect=.60). Finally, change in self-efficacy for PA predicted PA at 2-year follow-up. Conclusions Findings suggest that self-efficacy may influence long-term maintenance of healthy lifestyle practices among cancer survivors. PMID:22544562

  11. The Impact of Methane Clathrate Emissions on the Earth System

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Methane is locked in ice-like deposits called clathrates in ocean sediments and underneath permafrost regions. Clathrates are stable under high pressures and low temperatures, so 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, where methane is both an important greenhouse gas and a key species in atmospheric chemistry. Clathrates in the shallower parts of the Arctic Ocean (around 300m depth) are predicted to be particularly important since clathrates at that depth are expected to start outgassing abruptly in the next few decades. We will present the atmospheric impact of such methane emissions using multi-century steady-state simulations with a version of the Community Earth System Model (CESM) that includes atmospheric chemistry. Our simulations include a plausible release from clathrates in the Arctic that increases global methane emissions above present-day conditions by 22%, as well as a scenario with 10 times those clathrate emissions. The CESM model includes a fully interactive physical ocean, to which we added a fast atmospheric chemistry mechanism that represents methane as a fully interactive tracer (with emissions rather than concentration boundary conditions). The results indicate that such Arctic clathrate emissions (1) increase global methane concentrations by an average of 38%, non-uniformly; (2) increase surface ozone concentrations by around 10% globally, and even more in polluted regions; (3) increase methane lifetime by 13%; (4) increase the interannual variability in surface methane, surface ozone, and methane lifetime, and (5) show modest differences in surface temperature and methane lifetime compared to simulations in which the clathrate emissions are distributed uniformly. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  12. Biomimetic oxidation studies. 9. Mechanistic aspects of the oxidation of alcohols with functional,active site methane monooxygenase enzyme models in aqueous solution

    SciTech Connect

    Rabion, A. ||; Chen, S.; Wang, J.; Buchanan, R.M.; Seris, J.L.; Fish, R.H. |

    1995-12-13

    The syntheses of biomimetic complexes that mimic the major structural features of the hydroxylase component of methane monooxygenase enzyme (MMO) and, more importantly, that provide similar alkane functionalization activity, in the presence of an oxidant, have been of great interest to the discipline of bioinorganic chemistry. In this communication, we will demonstrate the feasibility of conducting biomimetic oxidation studies in H{sub 2}O with soluble substrates, i.e., alcohols (cyclohexanol, benzyl alcohol), using H{sub 2}O-stable MMO mimics at pH 4.2, and the oxidant, tert-butyl hydroperoxide (TBHP). Both the Mitusunobu procedure and the mesylate displacement reaction proceeded with complete inversion of the stereo-center and provided optically pure penultimate intermediate (>99.9% ee). The synthesis was completed by reduction of the nitro group under standard conditions to deliver LY300164 in 87%. In summary, we have developed an efficient and environmentally benign synthesis of the 5H-2,3-benzodiazepine LY300164 that provides the optically pure compound in 51% overall yield. Intramolecular hydrazone alkylation led to a remarkably facile and selective formation of the benzodiazepine. Furthermore, the application of resins to whole-cell-based biotransformations should find general utility for similar reactions that are complicated by component inhibition and product isolation. 11 refs., 1 fig.

  13. A correction in the CDM methodological tool for estimating methane emissions from solid waste disposal sites.

    PubMed

    Santos, M M O; van Elk, A G P; Romanel, C

    2015-12-01

    Solid waste disposal sites (SWDS) - especially landfills - are a significant source of methane, a greenhouse gas. Although having the potential to be captured and used as a fuel, most of the methane formed in SWDS is emitted to the atmosphere, mainly in developing countries. Methane emissions have to be estimated in national inventories. To help this task the Intergovernmental Panel on Climate Change (IPCC) has published three sets of guidelines. In addition, the Kyoto Protocol established the Clean Development Mechanism (CDM) to assist the developed countries to offset their own greenhouse gas emissions by assisting other countries to achieve sustainable development while reducing emissions. Based on methodologies provided by the IPCC regarding SWDS, the CDM Executive Board has issued a tool to be used by project developers for estimating baseline methane emissions in their project activities - on burning biogas from landfills or on preventing biomass to be landfilled and so avoiding methane emissions. Some inconsistencies in the first two IPCC guidelines have already been pointed out in an Annex of IPCC latest edition, although with hidden details. The CDM tool uses a model for methane estimation that takes on board parameters, factors and assumptions provided in the latest IPCC guidelines, while using in its core equation the one of the second IPCC edition with its shortcoming as well as allowing a misunderstanding of the time variable. Consequences of wrong ex-ante estimation of baseline emissions regarding CDM project activities can be of economical or environmental type. Example of the first type is the overestimation of 18% in an actual project on biogas from landfill in Brazil that harms its developers; of the second type, the overestimation of 35% in a project preventing municipal solid waste from being landfilled in China, which harms the environment, not for the project per se but for the undue generated carbon credits. In a simulated landfill - the same

  14. Martian zeolites as a source of atmospheric methane

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  16. Climate reconstruction from a methane influenced environment

    NASA Astrophysics Data System (ADS)

    Sztybor, K.; Rasmussen, T. L.; Mienert, J.; Bunz, S.; Consolaro, C.

    2013-12-01

    Sediment cores have been collected from Vestnesa Ridge, western Svalbard margin, from within and outside an active pockmark with methane gas flares. The lithological log, X-ray, magnetic susceptibility and numerous AMS dates were used to constrain the age model and for high-resolution inter-core correlation. Other proxies used in order to reconstruct the dynamics of changes of bottom water properties as well as North Atlantic hydrography were oxygen and carbon isotopes of benthic and planktonic foraminifera and assemblage counts. The main purpose of the study is to resolve the frequency of CH4 emissions from the seafloor through time in relation to past climate change. The magnetic susceptibility record from the pockmark core shows very low and constant values without the pattern typical for the western Svalbard. The seeping of methane clearly destroyed the signal. Benthic foraminifera within several intervals are depleted in δ13C, indicating increased methane flux from the seafloor. Carbon isotope values measured in planktonic foraminifera shells are also extremely low (<-10 ‰), which can be caused by coating of AOM (Anaerobic oxidation of methane)-derived carbonates (authigenic overgrowth). Moreover methane seepage affects the outcomes of AMS dating. Our results suggest that radiocarbon dates measured in bivalve shells are approximately 3000 cal years too old. In a methane influenced environment a multiproxy approach is necessary for more accurate paleoclimate reconstructions.

  17. Biogenic Methane from Coal: The Oxidation Factor

    NASA Astrophysics Data System (ADS)

    Gallagher, L. K.; Glossner, A. W.; Landkamer, L.; Figueroa, L. A.; Mandernack, K. W.; Munakata Marr, J.

    2011-12-01

    Vast reserves of coal represent an untapped resource that can be used to produce methane gas, a cleaner energy alternative compared to standard fossil fuels. Microorganisms have demonstrated the ability to utilize coal as a carbon source, producing biogenic methane. With increasing demand for cleaner energy resources, understanding and enhancing biogenic methane production has become an area of active research. The conversion of coal to methane by microorganisms has been demonstrated experimentally by a number of research groups, but the state of the coal used as a substrate has not always been reported and may impact biogenic methane production. Microcosm experiments were designed in order to assess how the oxidation state of coal might influence methane production (e.g. as in a dewatered coal-bed natural gas system). Oxidized and un-oxidized coal samples from the Powder River Basin were incubated in microcosms inoculated with an enrichment culture that was derived from coal. Microcosms were characterized by headspace gas analysis, organic acid production, functional gene abundance (qPCR), and pyrosequencing of the 16S rRNA gene. Although the microbial consortium demonstrated the ability to utilize both oxidized and un-oxidized coal as a sole carbon source to generate methane, it was produced in higher quantities from the un-oxidized coal. This microbial community was dominated by Methanobacteriaceae (45%), epsilon-Proteobacteria (32%) and delta-Proteobacteria (13%). The results of this study provide a basis to develop strategies to enhance biogenic methane production from coal, as well as demonstrate the need for careful substrate preparation for inter-study comparisons.

  18. Methane Emission by Camelids

    PubMed Central

    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

  19. Methane emission by camelids.

    PubMed

    Dittmann, Marie T; Runge, Ullrich; Lang, Richard A; Moser, Dario; Galeffi, Cordula; Kreuzer, Michael; Clauss, Marcus

    2014-01-01

    Methane emissions from ruminant livestock have been intensively studied in order to reduce contribution to the greenhouse effect. Ruminants were found to produce more enteric methane than other mammalian herbivores. As camelids share some features of their digestive anatomy and physiology with ruminants, it has been proposed that they produce similar amounts of methane per unit of body mass. This is of special relevance for countrywide greenhouse gas budgets of countries that harbor large populations of camelids like Australia. However, hardly any quantitative methane emission measurements have been performed in camelids. In order to fill this gap, we carried out respiration chamber measurements with three camelid species (Vicugna pacos, Lama glama, Camelus bactrianus; n = 16 in total), all kept on a diet consisting of food produced from alfalfa only. The camelids produced less methane expressed on the basis of body mass (0.32±0.11 L kg⁻¹ d⁻¹) when compared to literature data on domestic ruminants fed on roughage diets (0.58±0.16 L kg⁻¹ d⁻¹). However, there was no significant difference between the two suborders when methane emission was expressed on the basis of digestible neutral detergent fiber intake (92.7±33.9 L kg⁻¹ in camelids vs. 86.2±12.1 L kg⁻¹ in ruminants). This implies that the pathways of methanogenesis forming part of the microbial digestion of fiber in the foregut are similar between the groups, and that the lower methane emission of camelids can be explained by their generally lower relative food intake. Our results suggest that the methane emission of Australia's feral camels corresponds only to 1 to 2% of the methane amount produced by the countries' domestic ruminants and that calculations of greenhouse gas budgets of countries with large camelid populations based on equations developed for ruminants are generally overestimating the actual levels.

  20. Impact of seabird activity on nitrous oxide and methane fluxes from High Arctic tundra in Svalbard, Norway

    NASA Astrophysics Data System (ADS)

    Zhu, Renbin; Chen, Qingqing; Ding, Wei; Xu, Hua

    2012-12-01

    In this study, tundra N2O and CH4 fluxes were measured from one seabird sanctuary (SBT) and two non-seabird colonies (NST-I and NST-II) in Ny-Ålesund (79°55'N, 11°56'E), Svalbard during the summers of 2008 and 2009. N2O and CH4 fluxes from SBT showed large temporal and spatial variations depending on the intensity of seabird activity. High seabird activity sites showed large N2O and CH4 emissions while low N2O and CH4 emissions, even CH4 uptake occurred at medium and low seabird activity sites. Overall the mean fluxes were 18.3 ± 3.6 μg N2O m-2 h-1 and 53.5 ± 20.3 μg CH4 m-2 h-1 from tundra SBT whereas tundra NST-I and NST-II represented a relatively weak N2O source (8.3 ± 13.2 μg N2O m-2 h-1) and strong CH4 sink (-82.8 ± 22.3 μg CH4 m-2 h-1). Seabird activity was the strongest control of N2O and CH4 fluxes compared with soil temperature and moisture, and high N2O and CH4 emissions were created by soil physical and chemical processes (the sufficient supply of nutrients NH4+-N, NO3--N, total nitrogen, total phosphorus and total carbon from seabird guano, seabird tramp and appropriate water content) related to the seabird activity. Our work suggests that tundra ecosystems impacted by seabird activity are the potential "hotspots" for N2O and CH4 emissions although these sources have been largely neglected at present. Furthermore the combination of seabird activity and warming climate will likely further enhance N2O and CH4 emissions from the High Arctic tundra.

  1. Martian Methane From a Cometary Source: A Hypothesis

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

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

  2. Electrical properties of polycrystalline methane hydrate

    USGS Publications Warehouse

    Du Frane, W. L.; Stern, L.A.; Weitemeyer, K.A.; Constable, S.; Pinkston, J.C.; Roberts, J.J.

    2011-01-01

    Electromagnetic (EM) remote-sensing techniques are demonstrated to be sensitive to gas hydrate concentration and distribution and complement other resource assessment techniques, particularly seismic methods. To fully utilize EM results requires knowledge of the electrical properties of individual phases and mixing relations, yet little is known about the electrical properties of gas hydrates. We developed a pressure cell to synthesize gas hydrate while simultaneously measuring in situ frequency-dependent electrical conductivity (σ). Synthesis of methane (CH4) hydrate was verified by thermal monitoring and by post run cryogenic scanning electron microscope imaging. Impedance spectra (20 Hz to 2 MHz) were collected before and after synthesis of polycrystalline CH4 hydrate from polycrystalline ice and used to calculate σ. We determined the σ of CH4 hydrate to be 5 × 10−5 S/m at 0°C with activation energy (Ea) of 30.6 kJ/mol (−15 to 15°C). After dissociation back into ice, σ measurements of samples increased by a factor of ~4 and Ea increased by ~50%, similar to the starting ice samples.

  3. TARCOG Home Start Program.

    ERIC Educational Resources Information Center

    Top of Alabama Regional Council of Governments, Huntsville. Human Resources Program.

    This report describes the Top of Alabama Regional Council of Governments (TARCOG) Home Start Program. Five aspects of the program are presented. (1) The nutrition component is aimed at helping parents make the best use of food resources through good planning, buying, and cooking. (2) The health program involves provision of medical and dental…

  4. Starting in School

    ERIC Educational Resources Information Center

    Albertine, Susan

    2012-01-01

    Through its signature initiative, Liberal Education and America's Promise (LEAP), the Association of American Colleges and Universities (AAC&U) is promoting a vision for learning that begins in school: Starting in School . . . Rigorous and rich curriculum focused on the essential learning outcomes; comprehensive, individualized, and…

  5. Is Head Start Dying?

    ERIC Educational Resources Information Center

    Sherman, Ann; And Others

    1971-01-01

    Analysis of problems faced by Head Start and its present status includes a review of its transfer from O.E.O. to H.E.W., its extensions, the Westinghouse Report, and other studies and articles. Decline in public interest and support is noted. (KW)

  6. Blogs: Getting Started

    ERIC Educational Resources Information Center

    Dyrud, Marilyn A.; Worley, Rebecca B.; Schultz, Benjamin

    2005-01-01

    Blogs are communication tools, they serve as vehicles to transmit messages. Before deciding to blog, one needs to devise a strategy on how this medium will fit in with his or her communication needs. This will also help later in deciding which features one will need to include in his or her blog. This article discusses ways on how to start and…

  7. Smart Start Evaluation Plan.

    ERIC Educational Resources Information Center

    Bryant, Donna; Burchinal, Margaret; Buysse, Virginia; Kotch, Jonathan; Maxwell, Kelly; Neenan, Peter; Noblit, George; Orthner, Dennis; Peisner-Feinberg, Ellen; Telfair, Joseph

    Smart Start is North Carolina's partnership between state government and local leaders, service providers, and families to better serve children under 6 years of age and their families. This report describes the comprehensive plan to evaluate the state and local goals and objectives of the program, focusing on the components addressing the…

  8. Home Start Evaluation Study.

    ERIC Educational Resources Information Center

    High/Scope Educational Research Foundation, Ypsilanti, MI.

    Case studies of eight Home Start programs are given as the third section of an evaluation study. Communities involved are Binghamton, New York; Franklin, North Carolina; Cleveland, Ohio; Harrogate, Tennessee; Houston, Texas; Weslaco, Texas; Millville, Utah; Parkersburg, West Virginia. Although each study varies in format, each describes in detail…

  9. The Application of Methane Clumped Isotope Measurements to Determine the Source of Large Methane Seeps in Alaskan Lakes

    NASA Astrophysics Data System (ADS)

    Douglas, P. M.; Stolper, D. A.; Eiler, J. M.; Sessions, A. L.; Walter Anthony, K. M.

    2014-12-01

    Natural methane emissions from the Arctic present an important potential feedback to global warming. Arctic methane emissions may come from either active microbial sources or from deep fossil reservoirs released by the thawing of permafrost and melting of glaciers. It is often difficult to distinguish between and quantify contributions from these methane sources based on stable isotope data. Analyses of methane clumped isotopes (isotopologues with two or more rare isotopes such as 13CH3D) can complement traditional stable isotope-based classifications of methane sources. This is because clumped isotope abundances (for isotopically equilibrated systems) are a function of temperature and can be used to identify pathways of methane generation. Additionally, distinctive effects of mixing on clumped isotope abundances make this analysis valuable for determining the origins of mixed gasses. We find large variability in clumped isotope compositions of methane from seeps in several lakes, including thermokarst lakes, across Alaska. At Lake Sukok in northern Alaska we observe the emission of dominantly thermogenic methane, with a formation temperature of at least 100° C. At several other lakes we find evidence for mixing between thermogenic methane and biogenic methane that forms in low-temperature isotopic equilibrium. For example, at Eyak Lake in southeastern Alaska, analysis of three methane samples results in a distinctive isotopic mixing line between a high-temperature end-member that formed between 100-170° C, and a biogenic end-member that formed in isotopic equilibrium between 0-20° C. In this respect, biogenic methane in these lakes resembles observations from marine gas seeps, oil degradation, and sub-surface aquifers. Interestingly, at Goldstream Lake in interior Alaska, methane with strongly depleted clumped-isotope abundances, indicative of disequilibrium gas formation, is found, similar to observations from methanogen culture experiments.

  10. Source Attribution of Methane Emissions in Northeastern Colorado Using Ammonia to Methane Emission Ratios

    NASA Astrophysics Data System (ADS)

    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.

  11. Effects of animal activity and air temperature on methane and ammonia emissions from a naturally ventilated building for dairy cows

    NASA Astrophysics Data System (ADS)

    Ngwabie, N. M.; Jeppsson, K.-H.; Gustafsson, G.; Nimmermark, S.

    2011-12-01

    Knowledge of how different factors affect gas emissions from animal buildings can be useful for emission prediction purposes and for the improvement of emission abatement techniques. In this study, the effects of dairy cow activity and indoor air temperature on gas emissions were examined. The concentrations of CH 4, NH 3, CO 2 and N 2O inside and outside a dairy cow building were measured continuously between February and May together with animal activity and air temperature. The building was naturally ventilated and had a solid concrete floor which sloped towards a central urine gutter. Manure was scraped from the floor once every hour in the daytime and once every second hour at night into a partly covered indoor pit which was emptied daily at 6 a.m. and at 5 p.m. Gas emissions were calculated from the measured gas concentrations and ventilation rates estimated by the CO 2 balance method. The animal activity and emission rates of CH 4 and NH 3 showed significant diurnal variations with two peaks which were probably related to the feeding routine. On an average day, CH 4 emissions ranged from 7 to 15 g LU -1 h -1 and NH 3 emissions ranged from 0.4 to 1.5 g LU -1 h -1 (1 LU = 500 kg animal weight). Mean emissions of CH 4 and NH 3 were 10.8 g LU -1 h -1 and 0.81 g LU -1 h -1, respectively. The NH 3 emissions were comparable to emissions from tied stall buildings and represented a 4% loss in manure nitrogen. At moderate levels, temperature seems to affect the behaviour of dairy cows and in this study where the daily indoor air temperature ranged from about 5 up to about 20 °C, the daily activity of the cows decreased with increasing indoor air temperature ( r = -0.78). Results suggest that enteric fermentation is the main source of CH 4 emissions from systems of the type in this study, while NH 3 is mainly emitted from the manure. Daily CH 4 emissions increased significantly with the activity of the cows ( r = 0.61) while daily NH 3 emissions increased

  12. Revealing archaeal diversity patterns and methane fluxes in Admiralty Bay, King George Island, and their association to Brazilian Antarctic Station activities

    NASA Astrophysics Data System (ADS)

    Nakayama, C. R.; Kuhn, E.; Araújo, A. C. V.; Alvalá, P. C.; Ferreira, W. J.; Vazoller, R. F.; Pellizari, V. H.

    2011-03-01

    The study of Antarctic archaeal communities adds information on the biogeography of this group and helps understanding the dynamics of biogenic methane production in such extreme habitats. Molecular methods were combined to methane flux determinations in Martel Inlet, Admiralty Bay, to assess archaeal diversity, to obtain information about contribution of the area to atmospheric methane budget and to detect possible interferences of the Antarctic Brazilian Station Comandante Ferraz (EACF) wastewater discharge on local archaeal communities and methane emissions. Methane fluxes in Martel Inlet ranged from 3.2 to 117.9 μmol CH 4 m -2 d -1, with an average of 51.3±8.5 μmol CH 4 m -2 d -1 and a median of 57.6 μmol CH 4 m -2d -1. However, three negative fluxes averaging -11.3 μmol CH 4 m -2 d -1 were detected in MacKellar Inlet, indicating that Admiralty Bay can be either a source or sink of atmospheric methane. Denaturing gradient gel electrophoresis (DGGE) showed that archaeal communities at EACF varied with depth and formed a group separated from the reference sites. Granulometric analysis indicated that differences observed may be mostly related to sediment type. However, an influence of wastewater input could not be discarded, since higher methane fluxes were found at CF site, suggesting stimulation of local methanogenesis. DGGE profile of the wastewater sample grouped separated from all other samples, suggesting that methanogenesis stimulation may be due to changes in environmental conditions rather than to the input of allochtonous species from the wastewater. 16S ribosomal DNA clone libraries analysis showed that all wastewater sequences were related to known methanogenic groups belonging to the hydrogenotrophic genera Methanobacterium and Methanobrevibacter and the aceticlastic genus Methanosaeta. EACF and Botany Point sediment clone libraries retrieved only groups of uncultivated Archaea, with predominance of Crenarchaeota representatives (MCG, MG1, MBG

  13. Methane heat transfer investigation

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Future high chamber pressure LOX/hydrocarbon booster engines require copper base alloy main combustion chamber coolant channels similar to the SSME to provide adequate cooling and reusable engine life. Therefore, it is of vital importance to evaluate the heat transfer characteristics and coking thresholds for LNG (94% methane) cooling, with a copper base alloy material adjacent to he fuel coolant. High pressure methane cooling and coking characteristics recently evaluated at Rocketdyne using stainless steel heated tubes at methane bulk temperatures and coolant wall temperatures typical of advanced engine operation except at lower heat fluxes as limited by the tube material. As expected, there was no coking observed. However, coking evaluations need be conducted with a copper base surface exposed to the methane coolant at higher heat fluxes approaching those of future high chamber pressure engines.

  14. Methane heat transfer investigation

    NASA Technical Reports Server (NTRS)

    Cook, R. T.

    1984-01-01

    Future high chamber pressure LOX/hydrocarbon booster engines require copper-base alloy main combustion chamber coolant channels similar to the SSME to provide adequate cooling and resuable engine life. Therefore, it is of vital importance to evaluate the heat transfer characteristics and coking thresholds for LNG (94% methane) cooling, with a copper-base alloy material adjacent to the fuel coolant. High-pressure methane cooling and coking characteristics were recently evaluated using stainless-steel heated tubes at methane bulk temperatures and coolant wall temperatures typical of advanced engine operation except at lower heat fluxes as limited by the tube material. As expected, there was no coking observed. However, coking evaluations need be conducted with a copper-base surface exposed to the methane coolant at higher heat fluxes approaching those of future high chamber pressure engines.

  15. Laser beam methane detector

    NASA Technical Reports Server (NTRS)

    Hinkley, E. D., Jr.

    1981-01-01

    Instrument uses infrared absorption to determine methane concentration in liquid natural gas vapor. Two sensors measure intensity of 3.39 mm laser beam after it passes through gas; absorption is proportional to concentration of methane. Instrument is used in modeling spread of LNG clouds and as leak detector on LNG carriers and installations. Unit includes wheels for mobility and is both vertically and horizontally operable.

  16. Electrochemical methane sensor

    DOEpatents

    Zaromb, S.; Otagawa, T.; Stetter, J.R.

    1984-08-27

    A method and instrument including an electrochemical cell for the detection and measurement of methane in a gas by the oxidation of methane electrochemically at a working electrode in a nonaqueous electrolyte at a voltage about 1.4 volts vs R.H.E. (the reversible hydrogen electrode potential in the same electrolyte), and the measurement of the electrical signal resulting from the electrochemical oxidation.

  17. Elimination of methane in exhaust gas from biogas upgrading process by immobilized methane-oxidizing bacteria.

    PubMed

    Wu, Ya-Min; Yang, Jing; Fan, Xiao-Lei; Fu, Shan-Fei; Sun, Meng-Ting; Guo, Rong-Bo

    2017-01-13

    Biogas upgrading is essential for the comprehensive utilization of biogas as substitute of natural gas. However, the methane in the biogas can be fully recovered during the upgrading process of biogas, and the exhaust gas produced during biogas upgrading may contain a very low concentration of methane. If the exhaust gas with low concentration methane releases to atmosphere, it will be harmful to environment. In addition, the utilization of large amounts of digestate produced from biogas plant is another important issue for the development of biogas industry. In this study, solid digestate was used to produce active carbon, which was subsequently used as immobilized material for methane-oxidizing bacteria (MOB) in biofilter. Biofilter with MOB immobilized on active carbon was used to eliminate the methane in exhaust gas from biogas upgrading process. Results showed porous active carbon was successfully made from solid digestate. The final methane elimination capacity of immobilized MOB reached about 13molh(-1)m(-3), which was more 4 times higher than that of MOB without immobilization.

  18. Printable enzyme-embedded materials for methane to methanol conversion

    SciTech Connect

    Blanchette, Craig D.; Knipe, Jennifer M.; Stolaroff, Joshuah K.; DeOtte, Joshua R.; Oakdale, James S.; Maiti, Amitesh; Lenhardt, Jeremy M.; Sirajuddin, Sarah; Rosenzweig, Amy C.; Baker, Sarah E.

    2016-06-15

    An industrial process for the selective activation of methane under mild conditions would be highly valuable for controlling emissions to the environment and for utilizing vast new sources of natural gas. The only selective catalysts for methane activation and conversion to methanol under mild conditions are methane monooxygenases (MMOs) found in methanotrophic bacteria; however, these enzymes are not amenable to standard enzyme immobilization approaches. Using particulate methane monooxygenase (pMMO), we create a biocatalytic polymer material that converts methane to methanol. We demonstrate embedding the material within a silicone lattice to create mechanically robust, gas-permeable membranes, and direct printing of micron-scale structures with controlled geometry. Remarkably, the enzymes retain up to 100% activity in the polymer construct. The printed enzyme-embedded polymer motif is highly flexible for future development and should be useful in a wide range of applications, especially those involving gas–liquid reactions.

  19. Printable enzyme-embedded materials for methane to methanol conversion

    PubMed Central

    Blanchette, Craig D.; Knipe, Jennifer M.; Stolaroff, Joshuah K.; DeOtte, Joshua R.; Oakdale, James S.; Maiti, Amitesh; Lenhardt, Jeremy M.; Sirajuddin, Sarah; Rosenzweig, Amy C.; Baker, Sarah E.

    2016-01-01

    An industrial process for the selective activation of methane under mild conditions would be highly valuable for controlling emissions to the environment and for utilizing vast new sources of natural gas. The only selective catalysts for methane activation and conversion to methanol under mild conditions are methane monooxygenases (MMOs) found in methanotrophic bacteria; however, these enzymes are not amenable to standard enzyme immobilization approaches. Using particulate methane monooxygenase (pMMO), we create a biocatalytic polymer material that converts methane to methanol. We demonstrate embedding the material within a silicone lattice to create mechanically robust, gas-permeable membranes, and direct printing of micron-scale structures with controlled geometry. Remarkably, the enzymes retain up to 100% activity in the polymer construct. The printed enzyme-embedded polymer motif is highly flexible for future development and should be useful in a wide range of applications, especially those involving gas–liquid reactions. PMID:27301270

  20. Printable enzyme-embedded materials for methane to methanol conversion

    DOE PAGES

    Blanchette, Craig D.; Knipe, Jennifer M.; Stolaroff, Joshuah K.; ...

    2016-06-15

    An industrial process for the selective activation of methane under mild conditions would be highly valuable for controlling emissions to the environment and for utilizing vast new sources of natural gas. The only selective catalysts for methane activation and conversion to methanol under mild conditions are methane monooxygenases (MMOs) found in methanotrophic bacteria; however, these enzymes are not amenable to standard enzyme immobilization approaches. Using particulate methane monooxygenase (pMMO), we create a biocatalytic polymer material that converts methane to methanol. We demonstrate embedding the material within a silicone lattice to create mechanically robust, gas-permeable membranes, and direct printing of micron-scalemore » structures with controlled geometry. Remarkably, the enzymes retain up to 100% activity in the polymer construct. The printed enzyme-embedded polymer motif is highly flexible for future development and should be useful in a wide range of applications, especially those involving gas–liquid reactions.« less

  1. Comparison of Two Preparation Methods on Catalytic Activity and Selectivity of Ru-Mo/HZSM5 for Methane Dehydroaromatization

    DOE PAGES

    Petkovic, Lucia M.; Ginosar, Daniel M.

    2014-01-01

    Catalytic performance of Mo/HZSM5 and Ru-Mo/HZSM5 catalysts prepared by vaporization-deposition of molybdenum trioxide and impregnation with ammonium heptamolybdate was analyzed in terms of catalyst activity and selectivity, nitrogen physisorption analyses, temperature-programmed oxidation of carbonaceous residues, and temperature-programmed reduction. Vaporization-deposition rendered the catalyst more selective to ethylene and coke than the catalyst prepared by impregnation. This result was assigned to lower interaction of molybdenum carbide with the zeolite acidic sites.

  2. Methane carbon stable isotope signatures in waters and sediments of the Laptev Sea Shelf

    NASA Astrophysics Data System (ADS)

    Samarkin, V.; Semiletov, I. P.; Finke, N.; Shakhova, N. E.; Joye, S. B.

    2012-12-01

    There are a number of areas characterized high water column methane concentrations and active seafloor methane seepage zones along the shelf of the Laptev Sea. Degrading subsea permafrost, which is rich in organic carbon and possibly containing metastable methane gas hydrates, is considered a potent source of methane in this area. To better understand possible methane sources generating high methane areas of the Laptev Sea, carbon stable isotope signatures of water column methane and in surface and deep drill core sediment samples were obtained during summer 2011 and spring 2012 field campaigns. The δ13C values of methane dissolved in seawater at the drill site varied from -37.8 to -75.7 ‰. The range of δ13C values of methane in the surface sediments was from -51.3 to -58.2 ‰ and in drill core samples (up to 26.5 m depth) values ranged from -77.8 to -100 ‰. Methane carbon isotope signatures in seawater reflect various sources of methane and the influence of active aerobic methane oxidation in seawater and surface sediments. Significant depletion of methane from drill core with δ13C (to -100‰) is characteristic of hydrogenotrophic methanogenesis at cold near 0°C in situ temperatures, which was confirmed with δ14C-radiotracer rate incubations.

  3. Desulfuromonas carbonis sp. nov., an Fe(III)-, S0- and Mn(IV)-reducing bacterium isolated from an active coalbed methane gas well.

    PubMed

    An, Thuy T; Picardal, Flynn W

    2015-05-01

    A novel, mesophilic, obligately anaerobic, acetate-oxidizing, dissimilatory iron-, sulfur-, and manganese-reducing bacterium, designated strain ICBM(T), was obtained from an active, coalbed methane gas well in Indiana, USA. Strain ICBM(T) was a Gram-stain-negative, non-spore-forming, rod-shaped, non-motile bacterium that was rich in c-type cytochromes and formed red colonies in solid medium. Strain ICBM(T) conserved energy to support growth from the oxidation of acetate, propionate, pyruvate, malate, fumarate, succinate and dl-lactate, concomitant with dissimilatory iron reduction. Strain ICBM(T) fermented fumarate yielding succinate and acetate. Strain ICBM(T) was able to grow in the temperature range of 10 °C to 37 °C, NaCl concentration range of 0 to 1.2 M, and pH range of 6.5 to 8.0. The physiological characteristics of strain ICBM(T) indicated that it belongs to the Desulfuromonas cluster. The G+C content of its genomic DNA was 61.2 mol%. The predominant cellular fatty acids were C16 : 0 (39.3%), C16 : 1ω7c and/or iso-C15 : 0 2-OH (36.6%). The closest cultured phylogenetic relative of strain ICBM(T) was Desulfuromonas michiganensis BB1(T) with only 95% 16S rRNA gene sequence similarity. This confirmed that strain ICBM(T) is affiliated with the genus Desulfuromonas . On the basis of phenotypic and genotypic differences between strain ICBM(T) and other taxa of the genus Desulfuromonas , strain ICBM(T) represents a novel species for which the name Desulfuromonas carbonis sp. nov. is proposed (type strain ICBM(T) = DSM 29759(T) = JCM 30471(T)). Strain ICBM(T) is the first Fe(III)-, S(0)-, and Mn(IV)-reducing bacterium that was isolated from a coal bed.

  4. Microbial methane consumption in the oligotrophic surface waters of the East Siberian Arctic Shelf

    NASA Astrophysics Data System (ADS)

    Joye, S. B.

    2011-12-01

    The East Siberian Arctic Shelf (ESAS) accounts for ten percent of the world ocean shelf area and is the shallowest shelf (average depth < 50m). This area is home to a tremendous stock of hydrocarbons, mostly as methane associated with shallow, permafrost-associated hydrates. Thus, the ESAS represents an enormous potential atmospheric methane source that could result from global warming-triggered permafrost destabilization; such a massive methane infusion to the atmosphere from the Arctic could exacerbate and/or accelerate global warming. Increased methane fluxes could occur as numerous weak seeps or strong bubble plumes over large areas. Due to the shallow, well-mixed nature of the ESAS and its oligotrophic waters, the majority of methane entering ESAS water may avoids microbial oxidation and escape to the atmosphere. As part of an international research effort that aims to describe the patterns and controls methane dynamics within the ESAS, we documented methane concentrations and methane oxidation rates and examined environmental and microbiological factors that could regulate methane oxidation activity. Methane concentrations varied spatially and temporally and surface water concentrations were substantially super-saturated at most sites. The highest methane concentrations observed were hundreds of nanomolar. Despite the relatively methane concentrations, methane oxidation rates, determined with tritium-labeled methane tracer, were low, ranging from 10's of picomoles per liter per day to 3 nanomoles per liter per day. By and large, the turnover time for the methane pool was hundreds to thousands of days, which means that methane would be vented to the atmosphere before it was microbially oxidized. The exception to this pattern was in fresh water near the mouth of a river, where methane oxidation rates were high such that the pool turnover time was roughly 4 days. Available data suggest that nutrient availability limits accumulation of methanotroph biomass and

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    PubMed

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

    2014-12-01

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

  7. Non-microbial methane formation in oxic soils

    NASA Astrophysics Data System (ADS)

    Jugold, A.; Althoff, F.; Hurkuck, M.; Greule, M.; Lelieveld, J.; Keppler, F.

    2012-09-01

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

  8. Non-microbial methane formation in oxic soils

    NASA Astrophysics Data System (ADS)

    Jugold, A.; Althoff, F.; Hurkuck, M.; Greule, M.; Lenhart, K.; Lelieveld, J.; Keppler, F.

    2012-12-01

    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.

  9. Influence of headspace flushing on methane production in Biochemical Methane Potential (BMP) tests.

    PubMed

    Koch, Konrad; Fernández, Yadira Bajón; Drewes, Jörg E

    2015-06-01

    The influence of headspace flushing on the specific methane (CH4) production of blank samples with just inoculum in Biochemical Methane Potential (BMP) tests was studied. The three most common ways were applied: flushing with nitrogen (N2) gas, flushing with a mixture of N2 and CO2 (80/20 v/v), and no flushing. The results revealed that removing the oxygen is crucial to avoid aerobic respiration, which caused both hindered activity of methanogens and loss of methane potential. Furthermore it was demonstrated that 20% of CO2 in the flush gas increased significantly the methane production by over 20% compared to the flushing with pure N2. In order to mimic the same headspace conditions as in full-scale treatment plants, using a flush gas with a similar CO2 concentration as the expected biogas is suggested.

  10. Methane Emissions from Upland Forests

    NASA Astrophysics Data System (ADS)

    Megonigal, Patrick; Pitz, Scott; Wang, Zhi-Ping

    2016-04-01

    Global budgets ascribe 4-10% of atmospheric methane sinks to upland soils and assume that soils are the sole surface for methane exchange between upland forests and the atmosphere. The dogma that upland forests are uniformly atmospheric methane sinks was challenged a decade ago by the discovery of abiotic methane production from plant tissue. Subsequently a variety of relatively cryptic microbial and non-microbial methane sources have been proposed that have the potential to emit methane in upland forests. Despite the accumulating evidence of potential methane sources, there are few data demonstrating actual emissions of methane from a plant surface in an upland forest. We report direct observations of methane emissions from upland tree stems in two temperate forests. Stem methane emissions were observed from several tree species that dominate a forest located on the mid-Atlantic coast of North America (Maryland, USA). Stem emissions occurred throughout the growing season while soils adjacent to the trees simultaneously consumed methane. Scaling fluxes by stem surface area suggested the forest was a net methane source during a wet period in June, and that stem emissions offset 5% of the soil methane sink on an annual basis. High frequency measurements revealed diurnal cycles in stem methane emission rates, pointing to soils as the methane source and transpiration as the most likely pathway for gas transport. Similar observations were made in an upland forest in Beijing, China. However, in this case the evidence suggested the methane was not produced in soils, but in the heartwood by microbial or non-microbial processes. These data challenge the concept that forests are uniform sinks of methane, and suggest that upland forests are smaller methane sinks than previously estimated due to stem emissions. Tree emissions may be particularly important in upland tropical forests characterized by high rainfall and transpiration.

  11. Development of Sand Production Evaluation Apparatus for Methane Hydrate Development

    NASA Astrophysics Data System (ADS)

    Kakumoto, M.; Yoneda, J.; Tenma, N.; Katagiri, J.; Noda, S.

    2015-12-01

    As a part of a Japanese National hydrate research program (MH21, funded by METI), we performed a study on sand production mechanism during methane gas production. In 2013, the first methane hydrate offshore production test was conducted in Japan, and it was recognized in the production of about 20000m3/day of methane gas from methane hydrate bearing sand sediment in deep marine sediment. In methane hydrate development, depressurization method has been proposed for gas extraction. This method is a method to reduce the bottom hole pressure by submersible pump lowering water level in the production well, and gas and water is recovered by methane hydrate dissociation at the in situ. At that time, a phenomenon that sand flows into the wells is feared. In actually, sand production phenomenon occurred after 6 days from production start in offshore production test. A mechanism of sand production has not yet been resolved in case of methane hydrate development. Therefore, we developed large scale laboratory test apparatus for the purpose of elucidation of the mechanism of sand production phenomenon. In this presentation, we introduce basic performance of this apparatus, and usefulness is made mention by representative test results.

  12. Anaerobic oxidation of methane in the Concepción Methane Seep Area, Chilean continental margin

    NASA Astrophysics Data System (ADS)

    Steeb, P.; Linke, P.; Scholz, F.; Schmidt, M.; Liebetrau, V.; Treude, T.

    2012-04-01

    Within subduction zones of active continental margins, large amounts of methane can be mobilized by dewatering processes and transported to the seafloor along migration pathways. A recently discovered seep area located off Concepción (Chile) at water depth between 600 to 1100 mbsl is characterized by active methane vent sites as well as massive carbonates boulders and plates which probably are related to methane seepage in the past. During the SO210 research expedition "Chiflux" (Sept-Oct 2010), sediment from the Concepción Methane Seep Area (CSMA) at the fore arc of the Chilean margin was sampled to study microbial activity related to methane seepage. We sampled surface sediments (0-30cm) from sulfur bacteria mats, as well as clam, pogonophoran, and tubeworm fields with push cores and a TV-guided multicorer system. Anaerobic oxidation of methane (AOM) and sulfate reduction rates were determined using ex-situ radioisotope tracer techniques. Additionally, porewater chemistry of retrieved cores as well as isotopic composition and age record of surrounding authigenic carbonates were analyzed. The shallowest sulfate-methane-transition zone (SMTZ) was identified at 4 cm sediment depth hinting to locally strong fluid fluxes. However, a lack of Cl- anomalies in porewater profiles indicates a shallow source of these fluids, which is supported by the biogenic origin of the methane (δ13C -70‰ PDB). Sulfide and alkalinity was relatively high (up to 20 mM and 40 mEq, respectively). Rates of AOM and sulfate reduction within this area reached magnitudes typical for seeps with variation between different habitat types, indicating a diverse methane supply, which is affecting the depths of the SMTZ. Rates were highest at sulfur a bacteria mats (20 mmol m-2 d-1) followed by a large field of dead clams, a pogonophoran field, a black sediment spot, and a carbonate rich clam field. Lowest rates (0.2 mmol m-2 d-1) were measured in close vicinity to these hot spots. Abundant massive

  13. Investigations of Methane Production in Hypersaline Environments

    NASA Technical Reports Server (NTRS)

    Bebout, Brad M.

    2015-01-01

    The recent reports of methane in the atmosphere of Mars, as well as the findings of hypersaline paleo-environments on that planet, have underscored the need to evaluate the importance of biological (as opposed to geological) trace gas production and consumption. Methane in the atmosphere of Mars may be an indication of life but might also be a consequence of geologic activity and/or the thermal alteration of ancient organic matter. Hypersaline environments have now been reported to be extremely likely in several locations in our solar system, including: Mars, Europa, and Enceladus. Modern hypersaline microbial mat communities, (thought to be analogous to those present on the early Earth at a period of time when Mars was experiencing very similar environmental conditions), have been shown to produce methane. However, very little is known about the physical and/or biological controls imposed upon the rates at which methane, and other important trace gases, are produced and consumed in these environments. We describe here the results of our investigations of methane production in hypersaline environments, including field sites in Chile, Baja California Mexico, California, USA and the United Arab Emirates. We have measured high concentrations of methane in bubbles of gas produced both in the sediments underlying microbial mats, as well as in areas not colonized by microbial mats in the Guerrero Negro hypersaline ecosystem, Baja California Mexico, in Chile, and in salt ponds on the San Francisco Bay. The carbon isotopic (d13C) composition of the methane in the bubbles exhibited an extremely wide range of values, (ca. -75 per mille ca. -25 per mille). The hydrogen isotopic composition of the methane (d2H) ranged from -60 to -30per mille and -450 to -350per mille. These isotopic values are outside of the range of values normally considered to be biogenic, however incubations of the sediments in contact with these gas bubbles reveals that the methane is indeed being

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

    PubMed Central

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

    2012-01-01

    Peat bogs are primarily situated at mid to high latitudes and future climatic change projections indicate that these areas may become increasingly wetter and warmer. Methane emissions from peat bogs are reduced by symbiotic methane oxidizing bacteria (methanotrophs). Higher temperatures and increasing water levels will enhance methane production, but also methane oxidation. To unravel the temperature effect on methane and carbon cycling, a set of mesocosm experiments were executed, where intact peat cores containing actively growing Sphagnum were incubated at 5, 10, 15, 20, and 25°C. After two months of incubation, methane flux measurements indicated that, at increasing temperatures, methanotrophs are not able to fully compensate for the increasing methane production by methanogens. Net methane fluxes showed a strong temperature-dependence, with higher methane fluxes at higher temperatures. After removal of Sphagnum, methane fluxes were higher, increasing with increasing temperature. This indicates that the methanotrophs associated with Sphagnum plants play an important role in limiting the net methane flux from peat. Methanotrophs appear to consume almost all methane transported through diffusion between 5 and 15°C. Still, even though methane consumption increased with increasing temperature, the higher fluxes from the methane producing microbes could not be balanced by methanotrophic activity. The efficiency of the Sphagnum-methanotroph consortium as a filter for methane escape thus decreases with increasing temperature. Whereas 98% of the produced methane is retained at 5°C, this drops to approximately 50% at 25°C. This implies that warming at the mid to high latitudes may be enhanced through increased methane release from peat bogs. PMID:22768100

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

    PubMed

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

    2012-01-01

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

  16. When to Start Antiretroviral Therapy

    MedlinePlus

    ... away. What conditions increase the urgency to start ART? The following conditions increase the urgency to start ... risk of HIV transmission. Once a person starts ART, why is medication adherence important? ART is a ...

  17. Vapor-liquid activity coefficients for methanol and ethanol from heat of solution data: application to steam-methane reforming.

    PubMed

    Kunz, R G; Baade, W F

    2001-11-16

    This paper presents equations and curves to calculate vapor-liquid phase equilibria for methanol and ethanol in dilute aqueous solution as a function of temperature, using activity coefficients at infinite dilution. These thermodynamic functions were originally derived to assess the distribution of by-product contaminants in the process condensate and the steam-system deaerator of a hydrogen plant [Paper ENV-00-171 presented at the NPRA 2000 Environmental Conference, San Antonio, TX, 10-12 September 2000], but have general applicability to other systems as well. The functions and calculation method described here are a necessary piece of an overall prediction technique to estimate atmospheric emissions from the deaerator-vent when the process condensate is recycled as boiler feed water (BFW) make-up. Having such an estimation technique is of particular significance at this time because deaerator-vent emissions are already coming under regulatory scrutiny in California [Emissions from Hydrogen Plant Process Vents, Adopted 21 January 2000] followed closely elsewhere in the US, and eventually worldwide. The overall technique will enable a permit applicant to estimate environmental emissions to comply with upcoming regulations, and a regulatory agency to evaluate those estimates. It may also be useful to process engineers as a tool to estimate contaminant concentrations and flow rates in internal process streams such as the steam-generating system. Metallurgists and corrosion engineers might be able to use the results for materials selection.

  18. Eagle Fort Shale Play Methane Source and Fate Assessment

    NASA Astrophysics Data System (ADS)

    hampton, C. L.; Coffin, R. B.; Rose, P. S.; Boyd, T. J.; Murgulet, D.

    2013-12-01

    Shale gas is a new and important energy source in the United States. Methane in elevated concentrations has been observed in aquifers overlying active horizontal drilling sites in the Marcellus Shale operation area. In South Texas, horizontal fracturing is being applied to petroleum exploration in the Eagle Ford Shale play. Horizontal drilling and hydraulic fracturing can enhance methane transport to deep aquifers, soil, and the vadose zone. There is little information available regarding the presence and origin of methane in Texas groundwaters and the influence of horizontal fracking. The objective of this study is to assess the extent, severity, and sources of methane contamination in South Texas groundwaters. The ultimate goal of this research is to understand potential environmental impacts of hydraulic fracking on groundwater supplies. For this purpose, 35 groundwater samples were collected from active and non-active drilling areas at depths ranging between 50 and 1,300 meters. Stable carbon isotopes in methane (δ13CCH4) and carbon stable isotope ratios in dissolved incorganic carbon (δ13CDIC) analysis were measured to determine the range of signatures for shale petroleum-sourced methane and to differentiate between methane sources (i.e. microbial versus thermogenic). The preliminary δ13CCH4 data set suggests the presence of multiple sources of methane in the aquifers sampled. Stable isotope signatures of CH4 and DIC will help differentiate between sources.

  19. Properties of "started" earthquakes

    NASA Astrophysics Data System (ADS)

    Babeshko, V. A.; Evdokimova, O. V.; Babeshko, O. M.

    2016-04-01

    The properties of earthquakes called "started" in [1] are studied. The problems associated with the method of revealing them, the expected behavior of the event, and the determination of its place, time, and intensity are discussed. Certain characteristic properties of real earthquakes are compared with the modeled ones. It is emphasized that there are no data on earthquakes of a similar type in scientific publications. The method of using high-efficiency calculations is proposed by imbedding the investigations in topological spaces having a wider spectrum of properties than the functional ones.

  20. Geologic emissions of methane to the atmosphere.

    PubMed

    Etiope, Giuseppe; Klusman, Ronald W

    2002-12-01

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

  1. Combined free nitrous acid and hydrogen peroxide pre-treatment of waste activated sludge enhances methane production via organic molecule breakdown

    PubMed Central

    Zhang, Tingting; Wang, Qilin; Ye, Liu; Batstone, Damien; Yuan, Zhiguo

    2015-01-01

    This study presents a novel pre-treatment strategy using combined free nitrous acid (FNA i.e. HNO2) and hydrogen peroxide (H2O2) to enhance methane production from WAS, with the mechanisms investigated bio-molecularly. WAS from a full-scale plant was treated with FNA alone (1.54 mg N/L), H2O2 alone (10–80 mg/g TS), and their combinations followed by biochemical methane potential tests. Combined FNA and H2O2 pre-treatment substantially enhanced methane potential of WAS by 59–83%, compared to 13–23% and 56% with H2O2 pre-treatment alone and FNA pre-treatment alone respectively. Model-based analysis indicated the increased methane potential was mainly associated with up to 163% increase in rapidly biodegradable fraction with combined pre-treatment. The molecular weight distribution and chemical structure analyses revealed the breakdown of soluble macromolecules with the combined pre-treatment caused by the deamination and oxidation of the typical functional groups in proteins, polysaccharides and phosphodiesters. These changes likely improved the biodegradability of WAS. PMID:26565653

  2. Combined free nitrous acid and hydrogen peroxide pre-treatment of waste activated sludge enhances methane production via organic molecule breakdown

    NASA Astrophysics Data System (ADS)

    Zhang, Tingting; Wang, Qilin; Ye, Liu; Batstone, Damien; Yuan, Zhiguo

    2015-11-01

    This study presents a novel pre-treatment strategy using combined free nitrous acid (FNA i.e. HNO2) and hydrogen peroxide (H2O2) to enhance methane production from WAS, with the mechanisms investigated bio-molecularly. WAS from a full-scale plant was treated with FNA alone (1.54 mg N/L), H2O2 alone (10-80 mg/g TS), and their combinations followed by biochemical methane potential tests. Combined FNA and H2O2 pre-treatment substantially enhanced methane potential of WAS by 59-83%, compared to 13-23% and 56% with H2O2 pre-treatment alone and FNA pre-treatment alone respectively. Model-based analysis indicated the increased methane potential was mainly associated with up to 163% increase in rapidly biodegradable fraction with combined pre-treatment. The molecular weight distribution and chemical structure analyses revealed the breakdown of soluble macromolecules with the combined pre-treatment caused by the deamination and oxidation of the typical functional groups in proteins, polysaccharides and phosphodiesters. These changes likely improved the biodegradability of WAS.

  3. Combined free nitrous acid and hydrogen peroxide pre-treatment of waste activated sludge enhances methane production via organic molecule breakdown.

    PubMed

    Zhang, Tingting; Wang, Qilin; Ye, Liu; Batstone, Damien; Yuan, Zhiguo

    2015-11-13

    This study presents a novel pre-treatment strategy using combined free nitrous acid (FNA i.e. HNO2) and hydrogen peroxide (H2O2) to enhance methane production from WAS, with the mechanisms investigated bio-molecularly. WAS from a full-scale plant was treated with FNA alone (1.54 mg N/L), H2O2 alone (10-80 mg/g TS), and their combinations followed by biochemical methane potential tests. Combined FNA and H2O2 pre-treatment substantially enhanced methane potential of WAS by 59-83%, compared to 13-23% and 56% with H2O2 pre-treatment alone and FNA pre-treatment alone respectively. Model-based analysis indicated the increased methane potential was mainly associated with up to 163% increase in rapidly biodegradable fraction with combined pre-treatment. The molecular weight distribution and chemical structure analyses revealed the breakdown of soluble macromolecules with the combined pre-treatment caused by the deamination and oxidation of the typical functional groups in proteins, polysaccharides and phosphodiesters. These changes likely improved the biodegradability of WAS.

  4. Striking Doping Effects on Thermal Methane Activation Mediated by the Heteronuclear Metal Oxides [XAlO4 ](.+) (X=V, Nb, and Ta).

    PubMed

    Wu, Xiao-Nan; Li, Jilai; Schlangen, Maria; Zhou, Shaodong; González-Navarrete, Patricio; Schwarz, Helmut

    2017-01-18

    The thermal reactivity of the heteronuclear metal-oxide cluster cations [XAlO4 ](.+) (X=V, Nb, and Ta) towards methane has been studied by using mass spectrometry in conjunction with quantum mechanical calculations. Experimentally, a hydrogen-atom transfer (HAT) from methane is mediated by all the three oxide clusters at ambient conditions. However, [VAlO4 ](.+) is unique in that this cluster directly transforms methane into formaldehyde. The absence of this reaction for the Nb and Ta analogues demonstrates a striking doping effect on the chemoselectivity in the conversion of methane. Mechanistic aspects of the two reactions have been elucidated by quantum-chemical calculations. The HAT reactivity can be attributed to the significant spin density localized at the terminal oxygen atom (Ot(.-) ) of the cluster ions, while the ionic/covalent character of the Lewis acid-base unit [X-Ob ] plays a crucial role for the generation of formaldehyde. The mechanistic insight derived from this combined experimental/computational investigation may provide guidance for a more rational design of catalysts.

  5. Exploiting coalbed methane and protecting the global environment

    SciTech Connect

    Yuheng, Gao

    1996-12-31

    The global climate change caused by greenhouse gases (GHGs) emission has received wide attention from all countries in the world. Global environmental protection as a common problem has confronted the human being. As a main component of coalbed methane, methane is an important factor influencing the production safety of coal mine and threatens the lives of miners. The recent research on environment science shows that methane is a very harmful GHG. Although methane gas has very little proportion in the GHGs emission and its stayed period is also very short, it has very obvious impact on the climate change. From the estimation, methane emission in the coal-mining process is only 10% of the total emission from human`s activities. As a clean energy, Methane has mature recovery technique before, during and after the process of mining. Thus, coalbed methane is the sole GHG generated in the human`s activities and being possible to be reclaimed and utilized. Compared with the global greenhouse effect of other GHGs emission abatement, coalbed methane emission abatement can be done in very low cost with many other benefits: (1) to protect global environment; (2) to improve obviously the safety of coal mine; and (3) to obtain a new kind of clean energy. Coal is the main energy in China, and coalbed contains very rich methane. According to the exploration result in recent years, about 30000{approximately}35000 billion m{sup 2} methane is contained in the coalbed below 2000 m in depth. China has formed a good development base in the field of reclamation and utilization of coalbed methane. The author hopes that wider international technical exchange and cooperation in the field will be carried out.

  6. Modeling sulfate reduction in methane hydrate-bearing continental margin sediments: Does a sulfate-methane transition require anaerobic oxidation of methane?

    USGS Publications Warehouse

    Malinverno, A.; Pohlman, J.W.

    2011-01-01

    The sulfate-methane transition (SMT), a biogeochemical zone where sulfate and methane are metabolized, is commonly observed at shallow depths (1-30 mbsf) in methane-bearing marine sediments. Two processes consume sulfate at and above the SMT, anaerobic oxidation of methane (AOM) and organoclastic sulfate reduction (OSR). Differentiating the relative contribution of each process is critical to estimate methane flux into the SMT, which, in turn, is necessary to predict deeper occurrences of gas hydrates in continental margin sediments. To evaluate the relative importance of these two sulfate reduction pathways, we developed a diagenetic model to compute the pore water concentrations of sulfate, methane, and dissolved inorganic carbon (DIC). By separately tracking DIC containing 12C and 13C, the model also computes ??13C-DIC values. The model reproduces common observations from methane-rich sediments: a well-defined SMT with no methane above and no sulfate below and a ??13C-DIC minimum at the SMT. The model also highlights the role of upward diffusing 13C-enriched DIC in contributing to the carbon isotope mass balance of DIC. A combination of OSR and AOM, each consuming similar amounts of sulfate, matches observations from Site U1325 (Integrated Ocean Drilling Program Expedition 311, northern Cascadia margin). Without AOM, methane diffuses above the SMT, which contradicts existing field data. The modeling results are generalized with a dimensional analysis to the range of SMT depths and sedimentation rates typical of continental margins. The modeling shows that AOM must be active to establish an SMT wherein methane is quantitatively consumed and the ??13C-DIC minimum occurs. The presence of an SMT generally requires active AOM. Copyright 2011 by the American Geophysical Union.

  7. Oxygen and sulfur isotope fractionation during methane dependent sulfate reduction in high pressure continuous incubation studies

    NASA Astrophysics Data System (ADS)

    Deusner, C.; Brunner, B.; Holler, T.; Widdel, F.; Ferdelman, T. G.

    2009-12-01

    The anaerobic oxidation of methane (AOM) coupled to sulfate reduction in marine sediments is an important sink in the global methane budget. However, many aspects of methane dependent sulfate reduction are not fully understood. We developed a novel high pressure biotechnical system to simulate marine conditions with high concentrations of dissolved gases, e.g. at gas seeps and gas hydrate systems. The system allows for batch, fed-batch and continuous gas-phase free incubation. We employ this system to study the kinetics and isotope fractionation during AOM at varying methane partial pressures up to 10 MPa. We present the results of long-term continuous and fed-batch incubations with highly active naturally enriched biomass from microbial mats from the Black Sea. During these experiments the methane partial pressure was increased stepwise from 0.1 to 10 MPa. The methane dependent sulfate reduction rate increased from 0.1 mmol/l/d to 3.5 mmol/l/d resulting from the increase in methane concentration and microbial growth. Sulfate reduction was negligible in the absence of methane. The sulfur and oxygen isotope fractionation during sulfate reduction was strongly influenced by the concentration of dissolved methane. Sulfur isotope fractionation was highest at low methane concentrations, and lowest at high methane concentrations. Relative to sulfate reduction rates, oxygen isotope exchange between sulfate and water was highest at low methane concentrations, and lowest at high methane concentrations.

  8. Nickel-doped zinc aluminate oxides: starch-assisted synthesis, structural, optical properties, and their catalytic activity in oxidative coupling of methane

    NASA Astrophysics Data System (ADS)

    Visinescu, Diana; Papa, Florica; Ianculescu, Adelina C.; Balint, Ioan; Carp, Oana

    2013-03-01

    Nanosized nickel-substituted zinc aluminate oxides were obtained by the gradual insertion of nickel cations within the zinc aluminate lattice, using starch as active ingredient. The obtained (Ni x Zn1- x Al2)-starch ( x = 0.1, 0.2, 0.4, 0.6, 0.8, 1) gel precursors were characterized through infrared spectroscopy and thermal analysis. The thermal behavior of the precursors are influenced by the nickel content, the DTA curves for the richer nickel samples revealing stronger, faster and overlapping exothermic reactions, that can be completed at lower temperatures. The corresponding spinelic oxides were obtained after calcination treatments at 800 °C and analyzed by means of NIR-UV-Vis spectroscopy, XRD measurements, SEM, TEM, and HRTEM investigations. The spinelic structure for all oxide samples is confirmed by XRD analysis, although small amounts of NiO cannot be neglected. TEM/HRTEM analysis revealed mesopores embedded in plate-like large (68.8 nm) particles of Ni0.2Zn0.8Al2O4 sample and smaller (15.7 nm) uniform equiaxial particles, with a more pronounced tendency of agglomeration for Ni0.8Zn0.2Al2O4 oxide. A formation mechanism for Ni0.2Zn0.8Al2O4 oxides was proposed based on DTA/TG, XRD, and SEM analyses. NIR-UV-Vis spectra for Ni x Zn1- x Al2O4 showed a significant presence of tetrahedral nickel cations that augments with nickel concentration increase. CIE- L * a * b * color parameters shown a variation of the lightness and also of the green and blue color components with x, the best color characteristics being obtained for x = 0.6. The oxides with a substitution degree x = 0.2 and 0.8 tested in the oxidative coupled of methane reaction (OCM) showed positive catalytic activity and selectivity due to an interesting synergetic effect of Zn(II) and Ni(II) ions.

  9. Flu Cases Starting to Spread: CDC

    MedlinePlus

    ... fullstory_163159.html Flu Cases Starting to Spread: CDC Illness now being reported in middle sections of ... potential benefit from the vaccine," Lynnette Brammer, a CDC epidemiologist, said Friday. She said flu activity is " ...

  10. Combustion of Methane Hydrate

    NASA Astrophysics Data System (ADS)

    Roshandell, Melika

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

  11. Methane formation and methane oxidation by methanogenic bacteria.

    PubMed Central

    Zehnder, A J; Brock, T D

    1979-01-01

    Methanogenic bacteria were found to form and oxidize methane at the same time. As compared to the quantity of methane formed, the amount of methane simultaneously oxidized varied between 0.3 and 0.001%, depending on the strain used. All the nine tested strains of methane producers (Methanobacterium ruminantium, Methanobacterium strain M.o.H., M. formicicum, M. thermoautotrophicum, M. arbophilicum, Methanobacterium strain AZ, Methanosarcina barkeri, Methanospirillum hungatii, and the "acetate organism") reoxidized methane to carbon dioxide. In addition, they assimilated a small part of the methane supplied into cell material. Methanol and acetate also occurred as oxidation products in M. barkeri cultures. Acetate was also formed by the "acetate organism," a methane bacterium unable to use methanogenic substrates other than acetate. Methane was the precursor of the methyl group of the acetate synthesized in the course of methane oxidation. Methane formation and its oxidation were inhibited equally by 2-bromoethanesulfonic acid. Short-term labeling experiments with M. thermoautotrophicum and M. hungatii clearly suggest that the pathway of methane oxidation is not identical with a simple back reaction of the methane formation process. Images PMID:762019

  12. Methane storms on Saturn's moon Titan.

    PubMed

    Hueso, R; Sánchez-Lavega, A

    2006-07-27

    The presence of dry fluvial river channels and the intense cloud activity in the south pole of Titan over the past few years suggest the presence of methane rain. The nitrogen atmosphere of Titan therefore appears to support a methane meteorological cycle that sculptures the surface and controls its properties. Titan and Earth are the only worlds in the Solar System where rain reaches the surface, although the atmospheric cycles of water and methane are expected to be very different. Here we report three-dimensional dynamical calculations showing that severe methane convective storms accompanied by intense precipitation may occur in Titan under the right environmental conditions. The strongest storms grow when the methane relative humidity in the middle troposphere is above 80 per cent, producing updrafts with maximum velocities of 20 m s(-1), able to reach altitudes of 30 km before dissipating in 5-8 h. Raindrops of 1-5 mm in radius produce precipitation rainfalls on the surface as high as 110 kg m(-2) and are comparable to flash flood events on Earth.

  13. Upward revision of global fossil fuel methane emissions based on isotope database.

    PubMed

    Schwietzke, Stefan; Sherwood, Owen A; Bruhwiler, Lori M P; Miller, John B; Etiope, Giuseppe; Dlugokencky, Edward J; Michel, Sylvia Englund; Arling, Victoria A; Vaughn, Bruce H; White, James W C; Tans, Pieter P

    2016-10-06

    Methane has the second-largest global radiative forcing impact of anthropogenic greenhouse gases after carbon dioxide, but our understanding of the global atmospheric methane budget is incomplete. The global fossil fuel industry (production and usage of natural gas, oil and coal) is thought to contribute 15 to 22 per cent of methane emissions to the total atmospheric methane budget. However, questions remain regarding methane emission trends as a result of fossil fuel industrial activity and the contribution to total methane emissions of sources from the fossil fuel industry and from natural geological seepage, which are often co-located. Here we re-evaluate the global methane budget and the contribution of the fossil fuel industry to methane emissions based on long-term global methane and methane carbon isotope records. We compile the largest isotopic methane source signature database so far, including fossil fuel, microbial and biomass-burning methane emission sources. We find that total fossil fuel methane emissions (fossil fuel industry plus natural geological seepage) are not increasing over time, but are 60 to 110 per cent greater than current estimates owing to large revisions in isotope source signatures. We show that this is consistent with the observed global latitudinal methane gradient. After accounting for natural geological methane seepage, we find that methane emissions from natural gas, oil and coal production and their usage are 20 to 60 per cent greater than inventories. Our findings imply a greater potential for the fossil fuel industry to mitigate anthropogenic climate forcing, but we also find that methane emissions from natural gas as a fraction of production have declined from approximately 8 per cent to approximately 2 per cent over the past three decades.

  14. Upward revision of global fossil fuel methane emissions based on isotope database

    NASA Astrophysics Data System (ADS)

    Schwietzke, Stefan; Sherwood, Owen A.; Bruhwiler, Lori M. P.; Miller, John B.; Etiope, Giuseppe; Dlugokencky, Edward J.; Michel, Sylvia Englund; Arling, Victoria A.; Vaughn, Bruce H.; White, James W. C.; Tans, Pieter P.

    2016-10-01

    Methane has the second-largest global radiative forcing impact of anthropogenic greenhouse gases after carbon dioxide, but our understanding of the global atmospheric methane budget is incomplete. The global fossil fuel industry (production and usage of natural gas, oil and coal) is thought to contribute 15 to 22 per cent of methane emissions to the total atmospheric methane budget. However, questions remain regarding methane emission trends as a result of fossil fuel industrial activity and the contribution to total methane emissions of sources from the fossil fuel industry and from natural geological seepage, which are often co-located. Here we re-evaluate the global methane budget and the contribution of the fossil fuel industry to methane emissions based on long-term global methane and methane carbon isotope records. We compile the largest isotopic methane source signature database so far, including fossil fuel, microbial and biomass-burning methane emission sources. We find that total fossil fuel methane emissions (fossil fuel industry plus natural geological seepage) are not increasing over time, but are 60 to 110 per cent greater than current estimates owing to large revisions in isotope source signatures. We show that this is consistent with the observed global latitudinal methane gradient. After accounting for natural geological methane seepage, we find that methane emissions from natural gas, oil and coal production and their usage are 20 to 60 per cent greater than inventories. Our findings imply a greater potential for the fossil fuel industry to mitigate anthropogenic climate forcing, but we also find that methane emissions from natural gas as a fraction of production have declined from approximately 8 per cent to approximately 2 per cent over the past three decades.

  15. Leaking methane reservoirs offshore Svalbard

    NASA Astrophysics Data System (ADS)

    Minshull, T. A.; Westbrook, G. K.; Weitemeyer, K. A.; Sinha, M. C.; Goswami, B. K.; Marsset, B.

    2012-10-01

    Methane hydrate—a solid substance in which methane is trapped within ice-like crystals—is stable at low temperatures and high pressures and may be destabilized by ocean warming on both geological and human time scales. Methane is a powerful greenhouse gas, and methane released from hydrate provides a potential positive feedback mechanism in global climate change [e.g., Archer and Buffett, 2005]—in theory, the more methane is released by the hydrates, the warmer the climate gets, causing the ocean to warm and release more methane. However, methane escaping from the seabed is oxidized and dissolved in the ocean, and insufficient methane may reach the atmosphere to affect the climate significantly. Its importance for climate change therefore depends on whether the flux from the seabed is great enough to overcome solution in the ocean and perturb atmospheric concentrations over sufficiently long time scales.

  16. The basics of coalbed methane

    SciTech Connect

    2006-12-15

    The report is an overview of coalbed methane (CBM), also known as coal seam gas. It provides an overview of what coalbed methane is and the current status of global coalbed methane exploration and production. Topics covered in the report include: An analysis of the natural gas industry, including current and future production, consumption, and reserves; A detailed description of coalbed methane, its characteristics, and future potential; An analysis of the key business factors that are driving the increased interest in coalbed methane; An analysis of the barriers that are hindering the development of coalbed methane; An overview of the technologies used for coalbed methane production and water treatment; and Profiles of key coalbed methane producing countries. 25 figs., 5 tabs., 1 app.

  17. Snowball Earth termination by destabilization of equatorial permafrost methane clathrate.

    PubMed

    Kennedy, Martin; Mrofka, David; von der Borch, Chris

    2008-05-29

    The start of the Ediacaran period is defined by one of the most severe climate change events recorded in Earth history--the recovery from the Marinoan 'snowball' ice age, approximately 635 Myr ago (ref. 1). Marinoan glacial-marine deposits occur at equatorial palaeolatitudes, and are sharply overlain by a thin interval of carbonate that preserves marine carbon and sulphur isotopic excursions of about -5 and +15 parts per thousand, respectively; these deposits are thought to record widespread oceanic carbonate precipitation during postglacial sea level rise. This abrupt transition records a climate system in profound disequilibrium and contrasts sharply with the cyclical stratigraphic signal imparted by the balanced feedbacks modulating Phanerozoic deglaciation. Hypotheses accounting for the abruptness of deglaciation include ice albedo feedback, deep-ocean out-gassing during post-glacial oceanic overturn or methane hydrate destabilization. Here we report the broadest range of oxygen isotope values yet measured in marine sediments (-25 per thousand to +12 per thousand) in methane seeps in Marinoan deglacial sediments underlying the cap carbonate. This range of values is likely to be the result of mixing between ice-sheet-derived meteoric waters and clathrate-derived fluids during the flushing and destabilization of a clathrate field by glacial meltwater. The equatorial palaeolatitude implies a highly volatile shelf permafrost pool that is an order of magnitude larger than that of the present day. A pool of this size could have provided a massive biogeochemical feedback capable of triggering deglaciation and accounting for the global postglacial marine carbon and sulphur isotopic excursions, abrupt unidirectional warming, cap carbonate deposition, and a marine oxygen crisis. Our findings suggest that methane released from low-latitude permafrost clathrates therefore acted as a trigger and/or strong positive feedback for deglaciation and warming. Methane hydrate

  18. Methane recovery from landfill in China

    SciTech Connect

    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.

  19. Missouri: Early Head Start Initiative

    ERIC Educational Resources Information Center

    Center for Law and Social Policy, Inc. (CLASP), 2012

    2012-01-01

    Missouri's Early Head Start/Child Care Partnership Project expands access to Early Head Start (EHS) services for children birth to age 3 by developing partnerships between federal Head Start, EHS contractors, and child care providers. Head Start and EHS contractors that participate in the initiative provide services through community child care…

  20. Minnesota: Early Head Start Initiatiive

    ERIC Educational Resources Information Center

    Center for Law and Social Policy, Inc. (CLASP), 2012

    2012-01-01

    Minnesota provides supplemental state funding to existing federal Head Start and Early Head Start (EHS) grantees to increase their capacity to serve additional infants, toddlers, and pregnant women. The initiative was started in 1997 when the state legislature earmarked $1 million of the general state Head Start supplemental funds for children…

  1. Transformations in methane hydrates

    USGS Publications Warehouse

    Chou, I.-Ming; Sharma, A.; Burruss, R.C.; Shu, J.; Mao, Ho-kwang; Hemley, R.J.; Goncharov, A.F.; Stern, L.A.; Kirby, S.H.

    2000-01-01

    Detailed study of pure methane hydrate in a diamond cell with in situ optical, Raman, and x-ray microprobe techniques reveals two previously unknown structures, structure II and structure H, at high pressures. The structure II methane hydrate at 250 MPa has a cubic unit cell of a = 17.158(2) A?? and volume V = 5051.3(13) A??3; structure H at 600 MPa has a hexagonal unit cell of a = 11.980(2) A??, c = 9.992(3) A??, and V = 1241.9(5) A??3. The compositions of these two investigated phases are still not known. With the effects of pressure and the presence of other gases in the structure, the structure II phase is likely to dominate over the known structure I methane hydrate within deep hydrate-bearing sediments underlying continental margins.

  2. A laboratory study of anaerobic oxidation of methane in the presence of methane hydrate

    NASA Astrophysics Data System (ADS)

    Solem, R.; Bartlett, D.; Kastner, M.; Valentine, D.

    2003-12-01

    In order to mimic and study the process of anaerobic methane oxidation in methane hydrate regions we developed four high-pressure anaerobic bioreactors, designed to incubate environmental sediment samples, and enrich for populations of microbes associated with anaerobic methane oxidation (AMO). We obtained sediment inocula from a bacterial mat at the southern Hydrate Ridge, Cascadia, having cell counts approaching 1010 cells/cc. Ultimately, our goal is to produce an enriched culture of these microbes for characterization of the biochemical processes and chemical fluxes involved, as well as the unique adaptations required for, AMO. Molecular phylogenetic information along with results from fluorescent in situ hybridization indicate that consortia of Archaea and Bacteria are present which are related to those previously described for marine sediment AMO environments. Using a medium of enriched seawater and sediment in a 3:1 ratio, the system was incubated at 4° C under 43 atm of methane pressure; the temperature and pressure were kept constant. We have followed the reactions for seven months, particularly the vigorous consumption rates of dissolved sulfate and alkalinity production, as well as increases in HS-, and decreases in Ca concentrations. We also monitored the dissolved inorganic C (DIC) δ 13C values. The data were reproduced, and indicated that the process is extremely sensitive to changes in methane pressure. The rates of decrease in sulfate and increase in alkalinity concentrations were complimentary and showed considerable linearity with time. When the pressure in the reactor was decreased below the methane hydrate stability field, following the methane hydrate dissociation, sulfate reduction abruptly decreased. When the pressure was restored all the reactions returned to their previous rates. Much of the methane oxidation activity in the reactor is believed to occur in association with the methane hydrate. Upon the completion of one of the experiments

  3. Using stable isotopes to unravel the role of sea-ice in the methane cycle

    NASA Astrophysics Data System (ADS)

    Sapart, Célia Julia; Zhou, Jiayun; Carnat, Gauthier; Delille, Bruno; Niemann, Helge; Röckmann, Thomas; van der Veen, Carina; Tison, Jean-Louis

    2015-04-01

    Methane plays an important role in the Earth's climate system. The atmospheric methane concentration has increased in concert with the industrialization, but since the mid 80's the methane growth rate decreased to reach a near-zero level in 2000 and started to increase again from 2007 on. However, the underlying variations in sources and/or sinks that cause these variations are to date not well understood. To predict future climate, it is essential to unravel the processes controlling the methane cycle, especially in the Arctic regions, which are highly vulnerable to climate change and contain large methane reservoirs. Recently, an unexpected methane excess has been reported above Arctic sea-ice showing that sea-ice might play a significant role in the methane cycle. Nonetheless, the nature of the process leading to methane production in or nearby sea-ice has not yet been identified. We applied a new multi-proxy approach merging atmospheric chemistry, glaciology and biogeochemistry to understand and quantify the processes responsible for the methane excess above sea-ice. We performed methane isotope (δ13C and δD) analyses on sea-ice samples, as well as geochemical measurements, to determine the possible pathways involved in methane production and removal in or nearby sea-ice. We will present results from sea-ice samples drilled above the shallow-shelf in Barrow (Alaska) from January to June 2009 as well as above deep Southern Ocean locations in 2013. It has long been thought that methane present in sea-water would oxidize in or under the sea ice, but our first stable isotope sea ice profiles show no significant oxidation pattern. On the other hand, we show that landfast sea ice from both the shallow-shelf of Barrow and our deeper Southern Ocean site is supersaturated in methane and that under specific conditions methane is likely formed in the ice.

  4. Modeling the Terrestrial Contribution to the Global Methane Balance

    NASA Astrophysics Data System (ADS)

    Smith, Amy Tetlow

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

  5. C-H Bond Activation of Methane by PtII-N-Heterocyclic Carbene Complexes. The Importance of Having the Ligands in the Right Place at the Right Time

    SciTech Connect

    Prince, Bruce M.; Cundari, Thomas R

    2012-02-13

    A DFT study of methane C–H activation barriers for neutral NHC–PtII–methoxy complexes yielded 22.8 and 26.1 kcal/mol for oxidative addition (OA) and oxidative hydrogen migration (OHM), respectively. Interestingly, this is unlike the case for cationic NHC–PtII–methoxy complexes, whereby OHM entails a calculated barrier of 26.9 kcal/mol but the OA barrier is only 14.4 kcal/mol. Comparing transition state (TS) and ground state (GS) geometries implies an ~10 kcal/mol “penalty” to the barriers arising from positioning the NHC and OMe ligands into a relative orientation that is preferred in the GS to the orientation that is favored in the TS. The results thus imply an intrinsic barrier arising from C–H scission of ~15 ± 2 kcal/mol for NHC–PtII–methoxy complexes. Calculations show the importance of designing C–H activation catalysts where the GS active species is already structurally “prepared” and which either does not need to undergo any geometric perturbations to access the methane C–H activation TS or is not energetically prohibited from such perturbations.

  6. Methane gas generation from waste water extraction process of crude palm oil in experimental digesters

    NASA Astrophysics Data System (ADS)

    Dillon, A.; Penafiel, R.; Garzón, P. V.; Ochoa, V.

    2015-12-01

    Industrial processes to extract crude palm oil, generates large amounts of waste water. High concentrations of COD, ST, SV, NH4 + and low solubility of O2, make the treatment of these effluents starts with anaerobic processes. The anaerobic digestion process has several advantages over aerobic degradation: lower operating costs (not aeration), low sludge production, methane gas generation. The 4 stages of anaerobic digestion are: hydrolysis, acidogenic, acetogenesis and methanogenesis. Through the action of enzymes synthesized by microbial consortia are met. The products of each step to serve as reagents is conducted as follows. The organic load times and cell hydraulic retention, solids content, nutrient availability, pH and temperature are factors that influence directly in biodigesters. The objectives of this presentation is to; characterize the microbial inoculum and water (from palm oil wasted water) to be used in biodigestores, make specific methanogenic activity in bioassays, acclimatize the microorganisms to produce methane gas using basal mineral medium with acetate for the input power, and to determine the production of methane gas digesters high organic load.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  8. Enhanced Microbial Pathways for Methane Production from Oil Shale

    SciTech Connect

    Paul Fallgren

    2009-02-15

    Methane from oil shale can potentially provide a significant contribution to natural gas industry, and it may be possible to increase and continue methane production by artificially enhancing methanogenic activity through the addition of various substrate and nutrient treatments. Western Research Institute in conjunction with Pick & Shovel Inc. and the U.S. Department of Energy conducted microcosm and scaled-up reactor studies to investigate the feasibility and optimization of biogenic methane production from oil shale. The microcosm study involving crushed oil shale showed the highest yield of methane was produced from oil shale pretreated with a basic solution and treated with nutrients. Incubation at 30 C, which is the estimated temperature in the subsurface where the oil shale originated, caused and increase in methane production. The methane production eventually decreased when pH of the system was above 9.00. In the scaled-up reactor study, pretreatment of the oil shale with a basic solution, nutrient enhancements, incubation at 30 C, and maintaining pH at circumneutral levels yielded the highest rate of biogenic methane production. From this study, the annual biogenic methane production rate was determined to be as high as 6042 cu. ft/ton oil shale.

  9. An underestimated methane sink in Arctic mineral soils

    NASA Astrophysics Data System (ADS)

    Oh, Y.; Medvigy, D.; Stackhouse, B. T.; Lau, M.; Onstott, T. C.; Jørgensen, C. J.; Elberling, B.; Emmerton, C. A.; St Louis, V. L.; Moch, J.

    2015-12-01

    Atmospheric methane has more than doubled since the industrial revolution, yet the sources and sinks are still poorly constrained. Though soil methane oxidation is the largest terrestrial methane sink, it is inadequately represented in current models. We have conducted laboratory analysis of mineral cryosol soils from Axel Heiberg Island in the Canadian high arctic. Microcosm experiments were carried out under varying environmental conditions and used to parameterize methane oxidation models. One-meter long intact soil cores were also obtained from Axel Heiberg Island and analyzed in the laboratory. A controlled core thawing experiment was carried out, and observed methane fluxes were compared to modeled methane fluxes. We find that accurate model simulation of methane fluxes needs to satisfy two requirements:(1) microbial biomass needs to be dynamically simulated, and (2) high-affinity methanotrophs need to be represented. With these 2 features, our model is able to reproduce observed temperature and soil moisture sensitivities of high affinity methanotrophs, which are twice as sensitive to temperature than the low affinity methanotrophs and are active under saturated moisture conditions. The model is also able to accurately reproduce the time rate of change of microbial oxidation of atmospheric methane. Finally, we discuss the remaining biases and uncertainties in the model, and the challenges of extending models from the laboratory scale to the landscape scale.

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

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

    Methane plumes in the martian atmosphere have been detected using Earth-based spectroscopy, the Planetary Fourier Spectrometer on the ESA Mars Express mission, and the NASA Mars Science Laboratory. The methane's origin remains a mystery, with proposed sources including volcanism, exogenous sources like impacts and interplanetary dust, aqueous alteration of olivine in the presence of carbonaceous material, release from ancient deposits of methane clathrates, and/or biological activity. To date, none of these phenomena have been found to reliably correlate with the detection of methane plumes. An additional source exists, however: meteor showers could generate martian methane via UV pyrolysis of carbon-rich infall material. We find a correlation between the dates of Mars/cometary orbit encounters and detections of methane on Mars. We hypothesize that cometary debris falls onto Mars during these interactions, depositing freshly disaggregated meteor shower material in a regional concentration. The material generates methane via UV photolysis, resulting in a localized "plume" of short-lived methane.

  11. Eddy covariance based methane flux in Sundarbans mangroves, India

    NASA Astrophysics Data System (ADS)

    Jha, Chandra Shekhar; Rodda, Suraj Reddy; Thumaty, Kiran Chand; Raha, A. K.; Dadhwal, V. K.

    2014-06-01

    We report the initial results of the methane flux measured using eddy covariance method during summer months from the world's largest mangrove ecosystem, Sundarbans of India. Mangrove ecosystems are known sources for methane (CH4) having very high global warming potential. 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 (India). The tower is equipped with eddy covariance flux tower instruments to continuously measure methane fluxes besides the mass and energy fluxes. This paper presents the preliminary results of methane flux variations during summer months (i.e., April and May 2012) in Sundarbans mangrove ecosystem. The mean concentrations of CH4 emission over the study period was 1682 ± 956 ppb. The measured CH4 fluxes computed from eddy covariance technique showed that the study area acts as a net source for CH4 with daily mean flux of 150.22 ± 248.87 mg m-2 day-1. The methane emission as well as its flux showed very high variability diurnally. Though the environmental conditions controlling methane emission is not yet fully understood, an attempt has been made in the present study to analyse the relationships of methane efflux with tidal activity. This present study is part of Indian Space Research Organisation-Geosphere Biosphere Program (ISRO-GBP) initiative under `National Carbon Project'.

  12. Methane Recovery from Gaseous Mixtures Using Carbonaceous Adsorbents

    NASA Astrophysics Data System (ADS)

    Buczek, Bronisław

    2016-06-01

    Methane recovery from gaseous mixtures has both economical and ecological aspect. Methane from different waste gases like mine gases, nitrogenated natural gases and biogases can be treated as local source for production electric and heat energy. Also occurs the problem of atmosphere pollution with methane that shows over 20 times more harmful environmental effect in comparison to carbon dioxide. One of the ways utilisation such gases is enrichment of methane in the PSA technique, which requires appropriate adsorbents. Active carbons and carbon molecular sieve produced by industry and obtained in laboratory scale were examined as adsorbent for methane recuperation. Porous structure of adsorbents was investigated using densimetry measurements and adsorption of argon at 77.5K. On the basis of adsorption data, the Dubinin-Radushkevich equation parameters, micropore volume (Wo) and characteristics of energy adsorption (Eo) as well as area micropores (Smi) and BET area (SBET) were determined. The usability of adsorbents in enrichment of the methane was evaluated in the test, which simulate the basic stages of PSA process: a) adsorbent degassing, b) pressure raise in column by feed gas, c) cocurrent desorption with analysis of out flowing gas. The composition of gas phase was accepted as the criterion of the suitability of adsorbent for methane separation from gaseous mixtures. The relationship between methane recovery from gas mixture and texture parameters of adsorbents was found.

  13. The thermal decomposition of methane in a tubular reactor

    SciTech Connect

    Kobayashi, Atsushi; Steinberg, M.

    1992-01-01

    The reaction rate of methane decomposition using a tubular reactor having a 1 inch inside diameter with an 8 foot long heated zone was investigated in the temperature range of 700 to 900 C with pressures ranging from 28.2 to 56.1 atm. Representing the rate by a conventional model, {minus}dC{sub CH4}/dt= k1 C{sub CH4} {minus}k2 C{sub H2}{sup 2}, the rate constant k1 for methane decomposition was determined. The activation energy, 31.3 kcal/mol, calculated by an Arrhenius Plot was lower than for previously published results for methane decomposition. This result indicates that submicron particles found in the reactor adhere to the inside of the reactor and these submicron high surface area carbon particles tend to catalyze the methane decomposition. The rate constant has been found to be approximately constant at 900 C with pressure range cited above. The rate of methane decomposition increases with methane partial pressure in first-order. The rate of the methane decomposition is favored by higher temperatures and pressures while the thermochemical equilibrium of methane decomposition is favored by lower pressures. 8 refs., 7 figs., 2 tabs.

  14. Methane oxidation by Nitrosococcus oceanus and Nitrosomonas europaea

    SciTech Connect

    Jones, R.D.; Morita, R.Y.

    1983-02-01

    Chemolithotrophic ammonium-oxidizing bacteria were examined as to their ability to oxidize methane in the absence of ammonium or nitrite. The addition of ammonium stimulated both CO/sub 2/ production and cellular incorporation of methane-carbon by N. oceanus and N. europaea. Less than 0.1 mM CH/sub 4/ in solution inhibited the oxidation of ammonium by N. oceanus by 87% but had no inhibitory effects on N. europaea. In the absence of NH/sub 4/-N, N. oceanus achieved a maximum methane oxidation rate of 2.20 x 10/sup -2/ ..mu..mol of CH/sub 4/ h/sup -1/ mg (dry weight) of cells/sup -1/, which remained constant as the methane concentration was increased. In the presence of NH/sub 4/-N (10 ppm (10 ..mu..g/ml)), its maximum rate was 26.4 x 10/sup -2/ ..mu..mol of CH/sub 4/ h/sup -1/ mg (dry weight) of cells/sup -1/ at a methane concentration of 1.19 x 10/sup -1/ mM. Increasing the methane concentrations above this level decreased CO/sub 2/ production, whereas cellular incorporation of methane-carbon continued to increase. N. europaea showed a linear response throughout the test range, with an activity of 196.0 x 10/sup -2/ ..mu..mol of CH/sub 4/ h/sup -1/ mg (dry weight) of cells/sup -1/ at a methane concentration of 1.38 x 10/sup -1/ mM. Both nitrite and nitrate stimulated the oxidation of methane. The pH range was similar to that for ammonium oxidation, but the points of maximum activity were at lower values for the oxidation of methane. (JMT)

  15. Removal of atmospheric methane in shallow subterranean environments

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  16. Methane emissions from natural wetlands

    SciTech Connect

    Meyer, J.L.; Burke, R.A. Jr.

    1993-09-01

    Analyses of air trapped in polar ice cores in conjunction with recent atmospheric measurements, indicate that the atmospheric methane concentration increased by about 250% during the past two or three hundred years (Rasmussen and Khalil, 1984). Because methane is a potent ``greenhouse`` gas, the increasing concentrations are expected to contribute to global warning (Dickinson and Cicerone, 1986). The timing of the methane increase suggests that it is related to the rapid growth of the human population and associated industrialization and agricultural development. The specific causes of the atmospheric methane concentration increase are not well known, but may relate to either increases in methane sources, decreases in the strengths of the sinks, or both.

  17. Methane Clathrate Hydrate Prospecting

    NASA Technical Reports Server (NTRS)

    Duxbury, N.; Romanovsky, V.

    2003-01-01

    A method of prospecting for methane has been devised. The impetus for this method lies in the abundance of CH4 and the growing shortages of other fuels. The method is intended especially to enable identification of subpermafrost locations where significant amounts of methane are trapped in the form of methane gas hydrate (CH4(raised dot)6H2O). It has been estimated by the U.S. Geological Survey that the total CH4 resource in CH4(raised dot) 6H2O exceeds the energy content of all other fossil fuels (oil, coal, and natural gas from non-hydrate sources). Also, CH4(raised dot)6H2O is among the cleanest-burning fuels, and CH4 is the most efficient fuel because the carbon in CH4 is in its most reduced state. The method involves looking for a proxy for methane gas hydrate, by means of the combination of a thermal-analysis submethod and a field submethod that does not involve drilling. The absence of drilling makes this method easier and less expensive, in comparison with prior methods of prospecting for oil and natural gas. The proposed method would include thermoprospecting in combination with one more of the other non-drilling measurement techniques, which could include magneto-telluric sounding and/or a subsurface-electrical-resistivity technique. The method would exploit the fact that the electrical conductivity in the underlying thawed region is greater than that in the overlying permafrost.

  18. Starting Right: Using "Biophilia," Organism Cards, & Key Themes in Biology to Introduce Student-Centered Active-Learning Strategies at the Beginning of a Course

    ERIC Educational Resources Information Center

    Metzger, Kelsey

    2013-01-01

    To create rich learning experiences, it is important to engage students from the very beginning of a course and lay the foundation for constructing a community of active learners. The activities described here using "organism cards" connect students' previous knowledge to course goals and address key themes in biology while initiating…

  19. Methane isotope records from Antarctic firn air

    NASA Astrophysics Data System (ADS)

    Sowers, T. A.; Battle, M.

    2007-12-01

    The earth's climate is directly influenced by changes in the atmospheric loading of trace "greenhouse" gases. Methane is an important greenhouse gas whose atmospheric concentration has doubled over the last century as a result of various anthropogenic activities. Understanding the methane cycle in the recent past is a compelling scientific problem because increasing methane levels in the modern atmosphere will contribute to predicted future warming. The only source of air that allows us to study the long-term cycles of these gases is found in the trapped gases in ice cores and the interstitial pore spaces in firn from the central portions of Greenland and Antarctica. Firn air samples, retrieved from the South Pole in 1995 and 2001, were analyzed for δ13CH4. In December of 2005, another suite of firn air samples was recovered from the new US deep coring site located along the west Antarctic divide (WAIS D) which were analyzed for both δ13C and δ D of CH4. In general, replicate flasks were sampled from each depth from two separate drillings each year. The precision of the δ13C and δ D analyses is generally better than ± 0.2‰ and 2‰, respectively, with surface values in good agreement with NOAA (INSTAAR) biweekly flask measurements from South Pole. In all cases, δ13C and δD values decrease gradually with depth below the convective zone. However, these isotopes and CH4 mixing ratios decline sharply below the "lock-in" depth. The measured firn air profiles are primarily the result of three factors. First, tropospheric changes drive compositional changes in the near-surface convective layer that are subsequently mixed downward due to bulk air-movement within the shallow firn. Secondly, gases are mixed below the convective zone solely by molecular diffusion, leading to the gradual downward propagation of the compositional changes in the convective layer. Finally, differential gravitational settling causes the heavier atmospheric constituents (both elemental

  20. From Head Start to Sure Start: Reflections on Policy Transfer

    ERIC Educational Resources Information Center

    Welshman, John

    2010-01-01

    This article uses the history of debates over the US Head Start programme (1965), Early Head Start (1994) and the UK Sure Start initiative (1998), as a window on to policy transfer. In all the three, the aim was that early intervention could offer a means of boosting children's educational attainment and of countering the wider effects of poverty…

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  2. Generation of methane from paddy fields and cattle in India, and its reduction at source

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, T. K.; Goyal, P.; Singh, M. P.

    Methane (CH4) is a saturated organic gas. About 500 Tg yr -1 methane is generated globally. It is evident that 70% of the total emission have anthropogenic sources. The paddy fields contribute a significant portion of the total methane generated. About 20% of the total methane is generated from the paddy fields. In India, methane efflux rate is negative to 49 mg m -2 hr -1. The mean CH4 flux from Indian paddy fields is calculated to be 4.0 Tgyr -1. Livestock, and in particular ruminants are one of the important sources of methane emission on a global scale. There are two sources of methane emission from live stock: (1) from digestive process of ruminants, (2) from animal wastes. The estimated value of methane emission from digestive process of ruminants in India accounts for 6.47 Tgyr -1, and animal wastes accounts for 1.60 Tgyr -1. Total generation of methane from animals in India is about 8.0 Tg yr -1 . In paddy fields the key of controlling methane emission lies in the control of irrigation water. The methane emission can be decreased drastically if the field is under dry conditions for a few days at the end of tillering. In the case of livestock, reduction of methane emission can be done by (1) increasing the intake of the animal, (2) modifying the composition of the diet, (3) eliminating protozoa in rumen, (4) improving fibre digestion efficiency and (5) inhibiting activity of methanogenic bacteria.

  3. Sulfide and methane production in sewer sediments.

    PubMed

    Liu, Yiwen; Ni, Bing-Jie; Ganigué, Ramon; Werner, Ursula; Sharma, Keshab R; Yuan, Zhiguo

    2015-03-01

    Recent studies have demonstrated significant sulfide and methane production by sewer biofilms, particularly in rising mains. Sewer sediments in gravity sewers are also biologically active; however, their contribution to biological transformations in sewers is poorly understood at present. In this study, sediments collected from a gravity sewer were cultivated in a laboratory reactor fed with real wastewater for more than one year to obtain intact sediments. Batch test results show significant sulfide production with an average rate of 9.20 ± 0.39 g S/m(2)·d from the sediments, which is significantly higher than the areal rate of sewer biofilms. In contrast, the average methane production rate is 1.56 ± 0.14 g CH4/m(2)·d at 20 °C, which is comparable to the areal rate of sewer biofilms. These results clearly show that the contributions of sewer sediments to sulfide and methane production cannot be ignored when evaluating sewer emissions. Microsensor and pore water measurements of sulfide, sulfate and methane in the sediments, microbial profiling along the depth of the sediments and mathematical modelling reveal that sulfide production takes place near the sediment surface due to the limited penetration of sulfate. In comparison, methane production occurs in a much deeper zone below the surface likely due to the better penetration of soluble organic carbon. Modelling results illustrate the dependency of sulfide and methane productions on the bulk sulfate and soluble organic carbon concentrations can be well described with half-order kinetics.

  4. Liquid Oxygen/Liquid Methane Ascent Main Engine Technology Development

    NASA Technical Reports Server (NTRS)

    Robinson, Joel W.; Stephenson, David D.

    2008-01-01

    The National Aeronautics & Space Administration (NASA) has identified Liquid Oxygen (LO2)/Liquid Methane (LCH4) as a potential propellant combination for future space vehicles based upon the Exploration Systems Architecture Study (ESAS). The technology is estimated to have higher performance and lower overall systems mass compared to existing hypergolic propulsion systems. The current application considering this technology is the lunar ascent main engine (AME). AME is anticipated to be an expendable, pressure-fed engine to provide ascent from the moon at the completion of a 210 day lunar stay. The engine is expected to produce 5,500 lbf (24,465 N) thrust with variable inlet temperatures due to the cryogenic nature of the fuel and oxidizer. The primary technology risks include establishing reliable and robust ignition in vacuum conditions, maximizing specific impulse, developing rapid start capability for the descent abort, providing the capability for two starts and producing a total engine bum time over 500 seconds. This paper will highlight the efforts of the Marshall Space Flight Center (MSFC) in addressing risk reduction activities for this technology.

  5. Flu Season Starting to Peak

    MedlinePlus

    ... page: https://medlineplus.gov/news/fullstory_162917.html Flu Season Starting to Peak More severe strain of ... 6, 2017 FRIDAY, Jan. 6, 2017 (HealthDay News) -- Flu season is in full swing and it's starting ...

  6. The Future Starts Now

    ERIC Educational Resources Information Center

    Walton, Mark

    2008-01-01

    Reading "Learning for the Future," 15 years since it was first published, it is instructive to see what has changed and what has remained more or less the same. The years following the Rio Earth Summit saw the proliferation of a great deal of local debate and community-level activity to promote sustainable development, often under the…

  7. Starting Physiology: Bioelectrogenesis

    ERIC Educational Resources Information Center

    Baptista, Vander

    2015-01-01

    From a Cartesian perspective of rational analysis, the electric potential difference across the cell membrane is one of the fundamental concepts for the study of physiology. Unfortunately, undergraduate students often struggle to understand the genesis of this energy gradient, which makes the teaching activity a hard task for the instructor. The…

  8. Is long-term virological response related to CCR5 Δ32 deletion in HIV-1-infected patients started on highly active antiretroviral therapy?

    PubMed Central

    Laurichesse, Jean-Jacques; Taieb, Audrey; Capoulade-Metay, Corinne; Katlama, Christine; Villes, Virginie; Drobacheff-Thiebaud, Marie-Christine; Raffi, François; Chêne, Genevieve; Theodorou, Ioannis; Leport, Catherine

    2010-01-01

    Objective To examine whether CCR5 Δ32 deletion is associated with long-term response to combination antiretroviral treatment (cART) in HIV-1 infected patients. Methods The genetic sub-study of ANRS CO8 APROCO-COPILOTE cohort included 609 patients who started a protease inhibitor-containing cART in 1997–99. Patients were considered to have a sustained virological response if all plasma HIV-RNA measurements between month 4 and years 3–5 were <500 copies/ml, allowing for a single blip. Virological response was compared between patients heterozygous for CCR5 Δ32 (Δ32/wt) and wild-type patients (wt/wt) from month 4 to year 3 and month 4 to year 5. Logistic regression analysis was used to adjust for baseline demographical data, HIV-RNA, CD4 cell counts, antiretroviral naive status, time spent on antiretroviral therapy at year 3 and 5 and adherence to treatment (month 4 to year 3 and 5). Results Sustained virological response was better in Δ32/wt than in wt/wt patients: 66% versus 52% up to year 3 (p=0.02), nearly significant after adjustment to potential cofounders (p=0.07). Δ32/wt patients had a better virological response, up to year 5, 48% versus 35% (p=0.01), and remained significantly better, after adjustment, associated with a better virological response up to 5 years post initiation of cART (p=0.04). There was no association with CD4 response. Conclusion Δ32/wt deletion is associated with a beneficial virological response to cART on the long-term. Whether this association can be a direct effect of Δ32/wt deletion remains questionable and needs confirmation in other observational studies. PMID:20050936

  9. Examination of center of pressure displacement and muscle activity of the hip girdle muscles on lateral movement in the sitting position, focusing on kinematic features before and after the start of exercise

    PubMed Central

    Ikeda, Kouji; Suehiro, Kenji; Kizu, Akito; Kunieda, Hideki; Takasaki, Hirokazu; Suzuki, Toshiaki

    2017-01-01

    [Purpose] This study aimed to evaluate the kinematic characteristics at the start of lateral movement in the sitting position, for application in physical therapy. [Subjects and Methods] Eleven healthy male subjects (mean age, 24.8 ± 3.7 years) were included in the study after they provided informed consent. The electromyographic activities of the tensor fascia lata, gluteus medius, and rectus femoris, and the center of pressure (COP) displacement during lateral reach in the sitting position were measured. The task was recorded on video for analysis. [Results] In almost all subjects, before the beginning of the task, the electromyographic activity in the opposite side of each studied muscle was recorded, and the opposite and anterior displacement of the COP was observed. The video analysis revealed that all subjects showed lateral displacement of the thoracic part of the trunk after the start of the task. However, the lumbar region and pelvis maintained their starting positions. [Conclusion] COP displacement occurred in the reverse reaction before the task, and this involved the hip girdle muscles of the opposite side. A reverse reaction displaced the pelvis to the opposite side to ensure instability of posture through side tilting of the trunk at the beginning of the task. PMID:28356627

  10. Methane Absorption Coefficients for the Jovian Planets and Titan

    NASA Astrophysics Data System (ADS)

    Karkoschka, Erich; Tomasko, M. G.

    2009-09-01

    We combined 11 data sets of methane transmission measurements within 0.4-5.5 micrometer wavelength in order to better understand the variation of methane absorption with temperature and pressure for conditions in the atmospheres of the Jovian planets and Titan. Eight data sets are based on published laboratory measurements. Another two data sets come from two spectrometers onboard the Huygens probe that measured methane absorption inside Titan's atmosphere (Tomasko et al. 2008, PSS 56, 624). We present the data with a refined analysis. The last data set consists of Hubble Space Telescope images of Jupiter taken in 2005 and 2007 as Ganymede started to be occulted by Jupiter. Using Ganymede as a light source, we probed Jupiter's stratosphere with large methane pathlengths. Below 1000 nm wavelength, we find methane absorption coefficients generally similar to those by Karkoschka (1998, Icarus 133, 134). We added descriptions of temperature and pressure dependence, which are typically small in this wavelength range. Data in this wavelength range are consistent with each other, except between 882 and 902 nm wavelength where laboratory data predict larger absorptions in the Jovian atmospheres than observed. We present possible explanations. Above 1000 nm, our analysis of the Huygens data confirms methane absorption coefficients by Irwin et al. (2006, Icarus 181, 309) at their laboratory temperatures. Huygens data are consistent with Irwin's model of the pressure dependence of methane absorption. However, when large extrapolations were needed, such as from laboratory data above 200 K to Titan's temperatures near 80 K, Irwin's model of temperature dependence predicts absorption coefficients up to 100 times lower than measured by Huygens. We combined Irwin's and Huygens' data to obtain more reliable methane absorption coefficients for the temperatures in the atmospheres of the Jovian planets and Titan. This research was supported by NASA grants NAG5-12014 and NNX08AE74G.

  11. Yes, Head Start Improves Reading!

    ERIC Educational Resources Information Center

    Larsen, Janet J.

    This study evaluated the effect of a Head Start program on children's intelligence and reading achievement test scores over a three year period. Each of 25 Head Start children was paired with a non-Head Start child of the same reace, sex, age, socioeconomic status, date of school entrance, kindergarten experience, promotion record, and type of…

  12. Production of Methane and Water from Crew Plastic Waste

    NASA Technical Reports Server (NTRS)

    Captain, Janine; Santiago, Eddie; Parrish, Clyde; Strayer, Richard F.; Garland, Jay L.

    2008-01-01

    Recycling is a technology that will be key to creating a self sustaining lunar outpost. The plastics used for food packaging provide a source of material that could be recycled to produce water and methane. The recycling of these plastics will require some additional resources that will affect the initial estimate of starting materials that will have to be transported from earth, mainly oxygen, energy and mass. These requirements will vary depending on the recycling conditions. The degredation products of these plastics will vary under different atmospheric conditions. An estimate of the the production rate of methane and water using typical ISRU processes along with the plastic recycling will be presented.

  13. Training Head Start Coordinators for Workplace Preparedness. NCCU Head Start Monograph, October 1995.

    ERIC Educational Resources Information Center

    North Carolina Central Univ., Durham.

    This monograph summarizes results from academic capstone activities of graduate students and faculty advisors regarding issues consistent with Head Start national priorities and practice needs. The following theses are summarized: (1) "Multicultural Education in Head Start Programs in North Carolina" (S.K. Gant); (2) "The Impact of…

  14. Ground and Airborne Methane Measurements Using Optical Parametric Amplifiers

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  15. Electronic Origins of the Variable Efficiency of Room-Temperature Methane Activation by Homo- and Heteronuclear Cluster Oxide Cations [XYO2](+) (X, Y = Al, Si, Mg): Competition between Proton-Coupled Electron Transfer and Hydrogen-Atom Transfer.

    PubMed

    Li, Jilai; Zhou, Shaodong; Zhang, Jun; Schlangen, Maria; Weiske, Thomas; Usharani, Dandamudi; Shaik, Sason; Schwarz, Helmut

    2016-06-29

    The reactivity of the homo- and heteronuclear oxide clusters [XYO2](+) (X, Y = Al, Si, Mg) toward methane was studied using Fourier transform ion cyclotron resonance mass spectrometry, in conjunction with high-level quantum mechanical calculations. The most reactive cluster by both experiment and theory is [Al2O2](•+). In its favorable pathway, this cluster abstracts a hydrogen atom by means of proton-coupled electron transfer (PCET) instead of following the conventional hydrogen-atom transfer (HAT) route. This mechanistic choice originates in the strong Lewis acidity of the aluminum site of [Al2O2](•+), which cleaves the C-H bond heterolytically to form an Al-CH3 entity, while the proton is transferred to the bridging oxygen atom of the cluster ion. In addition, a comparison of the reactivity of heteronuclear and homonuclear oxide clusters [XYO2](+) (X, Y = Al, Si, Mg) reveals a striking doping effect by aluminum. Thus, the vacant s-p hybrid orbital on Al acts as an acceptor of the electron pair from methyl anion (CH3(-)) and is therefore eminently important for bringing about thermal methane activation by PCET. For the Al-doped cluster ions, the spin density at an oxygen atom, which is crucial for the HAT mechanism, acts here as a spectator during the course of the PCET mediated C-H bond cleavage. A diagnostic plot of the deformation energy vis-à-vis the barrier shows the different HAT/PCET reactivity map for the entire series. This is a strong connection to the recently discussed mechanism of oxidative coupling of methane on magnesium oxide surfaces proceeding through Grignard-type intermediates.

  16. Toxic effects of butyl elastomers on aerobic methane oxidation

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  17. Enhanced carbon monoxide utilization in methanation process

    DOEpatents

    Elek, Louis F.; Frost, Albert C.

    1984-01-01

    Carbon monoxide - containing gas streams are passed over a catalyst to deposit a surface layer of active surface carbon thereon essentially without the formation of inactive coke. The active carbon is subsequently reacted with steam or hydrogen to form methane. Surprisingly, hydrogen and water vapor present in the feed gas do not adversely affect CO utilization significantly, and such hydrogen actually results in a significant increase in CO utilization.

  18. Stop Thinking and Start Doing: Switching from Cognitive Therapy to Behavioral Activation in a Case of Chronic Treatment-Resistant Depression

    ERIC Educational Resources Information Center

    Bottonari, Kathryn A.; Roberts, John E.; Thomas, Sherilyn N.; Read, Jennifer P.

    2008-01-01

    Several recent investigations have demonstrated that Cognitive Therapy (CT) and Behavioral Activation (BA) are both efficacious treatments for depression (Butler, Chapman, Forman, & Beck, 2006; Dimidjian et al., 2006; Dobson, 1989; Gloaguen, Cottraux, Cucherat, & Blackburn, 1998; Hollon, Thase, & Markowitz, 2002; Jacobson et al., 1996). This…

  19. Being Healthy and Safe with McGruff and Scruff: Activity Book for Preschool, Head Start, and Other Child Care Programs.

    ERIC Educational Resources Information Center

    National Crime Prevention Council, Washington, DC.

    This activity booklet is designed to help preschool teachers and caregivers prepare preschoolers to deal with issues of self-esteem, problem solving, health and safety awareness, and crime, drug, and violence prevention on developmentally appropriate levels. It provides background information on drug and violence prevention for 4- and 5-year-olds,…

  20. Methane cycling. Nonequilibrium clumped isotope signals in microbial methane.

    PubMed

    Wang, David T; Gruen, Danielle S; Lollar, Barbara Sherwood; Hinrichs, Kai-Uwe; Stewart, Lucy C; Holden, James F; Hristov, Alexander N; Pohlman, John W; Morrill, Penny L; Könneke, Martin; Delwiche, Kyle B; Reeves, Eoghan P; Sutcliffe, Chelsea N; Ritter, Daniel J; Seewald, Jeffrey S; McIntosh, Jennifer C; Hemond, Harold F; Kubo, Michael D; Cardace, Dawn; Hoehler, Tori M; Ono, Shuhei

    2015-04-24

    Methane is a key component in the global carbon cycle, with a wide range of anthropogenic and natural sources. Although isotopic compositions of methane have traditionally aided source identification, the abundance of its multiply substituted "clumped" isotopologues (for example, (13)CH3D) has recently emerged as a proxy for determining methane-formation temperatures. However, the effect of biological processes on methane's clumped isotopologue signature is poorly constrained. We show that methanogenesis proceeding at relatively high rates in cattle, surface environments, and laboratory cultures exerts kinetic control on (13)CH3D abundances and results in anomalously elevated formation-temperature estimates. We demonstrate quantitatively that H2 availability accounts for this effect. Clumped methane thermometry can therefore provide constraints on the generation of methane in diverse settings, including continental serpentinization sites and ancient, deep groundwaters.

  1. Revisiting the mechanism of dioxygen activation in soluble methane monooxygenase from M. capsulatus (Bath): evidence for a multi-step, proton-dependent reaction pathway.

    PubMed

    Tinberg, Christine E; Lippard, Stephen J

    2009-12-29

    Stopped-flow kinetic investigations of soluble methane monooxygenase (sMMO) from M. capsulatus (Bath) have clarified discrepancies that exist in the literature regarding several aspects of catalysis by this enzyme. The development of thorough kinetic analytical techniques has led to the discovery of two novel oxygenated iron species that accumulate in addition to the well-established intermediates H(peroxo) and Q. The first intermediate, P*, is a precursor to H(peroxo) and was identified when the reaction of reduced MMOH and MMOB with O(2) was carried out in the presence of >or=540 microM methane to suppress the dominating absorbance signal due to Q. The optical properties of P* are similar to those of H(peroxo), with epsilon(420) = 3500 M(-1) cm(-1) and epsilon(720) = 1250 M(-1) cm(-1). These values are suggestive of a peroxo-to-iron(III) charge-transfer transition and resemble those of peroxodiiron(III) intermediates characterized in other carboxylate-bridged diiron proteins and synthetic model complexes. The second identified intermediate, Q*, forms on the pathway of Q decay when reactions are performed in the absence of hydrocarbon substrate. Q* does not react with methane, forms independently of buffer composition, and displays a unique shoulder at 455 nm in its optical spectrum. Studies conducted at different pH values reveal that rate constants corresponding to P* decay/H(peroxo) formation and H(peroxo) decay/Q formation are both significantly retarded at high pH and indicate that both events require proton transfer. The processes exhibit normal kinetic solvent isotope effects (KSIEs) of 2.0 and 1.8, respectively, when the reactions are performed in D(2)O. Mechanisms are proposed to account for the observations of these novel intermediates and the proton dependencies of P* to H(peroxo) and H(peroxo) to Q conversion.

  2. Project identification for methane reduction options

    SciTech Connect

    Kerr, T.

    1996-12-31

    This paper discusses efforts directed at reduction in emission of methane to the atmosphere. Methane is a potent greenhouse gas, which on a 20 year timeframe may present a similar problem to carbon dioxide. In addition, methane causes additional problems in the form of smog and its longer atmospheric lifetime. The author discusses strategies for reducing methane emission from several major sources. This includes landfill methane recovery, coalbed methane recovery, livestock methane reduction - in the form of ruminant methane reduction and manure methane recovery. The author presents examples of projects which have implemented these ideas, the economics of the projects, and additional gains which come from the projects.

  3. Room-temperature activation of methane and dry re-forming with CO2 on Ni-CeO2 (111) surfaces: Effect of Ce3+ sites and metal–support interactions on C–H bond cleavage

    SciTech Connect

    Lustemberg, Pablo G.; Ramírez, Pedro J.; Liu, Zongyuan; Gutierrez, Ramon A.; Grinter, David G.; Carrasco, Javier; Senanayake, Sanjaya D.; Rodriguez, Jose A.; Ganduglia-Pirovano, M. Veronica

    2016-10-27

    The results of core-level photoemission indicate that Ni-CeO2(111) surfaces with small or medium coverages of nickel are able to activate methane at 300 K, producing adsorbed CHx and COx (x = 2, 3) groups. Calculations based on density functional theory predict a relatively low activation energy of 0.6–0.7 eV for the cleavage of the first C–H bond in the adsorbed methane molecule. Ni and O centers of ceria work in a cooperative way in the dissociation of the C–H bond at room temperature, where a low Ni loading is crucial for the catalyst activity and stability. The strong electronic perturbations in the Ni nanoparticles produced by the ceria supports of varying natures, such as stoichiometric and reduced, result in a drastic change in their chemical properties toward methane adsorption and dissociation as well as the dry reforming of methane reaction. Lastly, the coverage of Ni has a drastic effect on the ability of the system to dissociate methane and catalyze the dry re-forming process.

  4. Preferential CO oxidation on Ru/Al 2O 3 catalyst: An investigation by considering the simultaneously involved methanation

    NASA Astrophysics Data System (ADS)

    Xu, Guangwen; Zhang, Zhan-Guo

    The CO removal with preferential CO oxidation (PROX) over an industrial 0.5% Ru/Al 2O 3 catalyst from simulated reformates was examined and evaluated through considering its simultaneously involved oxidation and methanation reactions. It was found that the CO removal was fully due to the preferential oxidation of CO until 383 K. Over this temperature, the simultaneous CO methanation was started to make a contribution, which compensated for the decrease in the removal due to the decreased selectivity of PROX at higher temperatures. This consequently kept the effluent CO content as well as the overall selectivity estimated as the ratio of the removed CO amount over the sum of the consumed O 2 and formed CH 4 amounts from apparently increasing with raising reaction temperature from 383 to 443 K when the CO 2 methanation was yet not fully started. At these temperatures the tested catalyst enabled the initial CO content of up to 1.0 vol.% to be removed to several tens of ppm at an overall selectivity of about 0.4 from simulated reformates containing 70 vol.% H 2, 30 vol.% CO 2 and with steam of up to 0.45 (volume) of dry gas. Varying space velocity in less than 9000 h -1 did not much change the stated overall selectivity. From the viewpoint of CO removal the article thus concluded that the methanation activity of the tested Ru/Al 2O 3 greatly extended its working temperatures for PROX, demonstrating actually a feasible way to formulate PROX catalysts that enable broad windows of suitable working temperatures.

  5. Aeronautics. An Educator's Guide with Activities in Science, Mathematics, and Technology Education: What Pilot, Astronaut, or Aeronautical Engineer didn't Start out with a Toy Glider?

    NASA Technical Reports Server (NTRS)

    Biggs, Pat (Editor); Huetter, Ted (Editor)

    1998-01-01

    Welcome to the exciting world of aeronautics. The term aeronautics originated in France, and was derived from the Greek words for "air" and "to sail." It is the study of flight and the operation of aircraft. This educator guide explains basic aeronautical concepts, provides a background in the history of aviation, and sets them within the context of the flight environment (atmosphere, airports, and navigation). The activities in this guide are designed to be uncomplicated and fun. They have been developed by NASA Aerospace Education Services Program specialists, who have successfully used them in countless workshops and student programs around the United States. The activities encourage students to explore the nature of flight, and experience some real-life applications of mathematics, science, and technology. The subject of flight has a wonderful power to inspire learning.

  6. Identification of the srtC1 Transcription Start Site and Catalytically Essential Residues Required for Actinomyces oris T14V SrtC1 Activity

    DTIC Science & Technology

    2011-07-27

    al., 1999, 2002; Frankel et al., 2007), Cys 193 in SrtC1 from Streptococcus pneumoniae (Manzano et al., 2008) and Cys 219 in SrtC1 from Group B...Sortase mediated pilus fiber biogenesis in Streptococcus pneumoniae . Structure 16: 1838 1848. Manzano C, Izore T, Job V, Di Guilmi AM & Dessen A... Streptococcus (Cozzi et al., 2011) are critical for each of their corresponding sortase activities. When two other residues (Leu263 and Thr265) in this

  7. Overweight and obese adolescent girls: the importance of promoting sensible eating and activity behaviors from the start of the adolescent period.

    PubMed

    Todd, Alwyn S; Street, Steven J; Ziviani, Jenny; Byrne, Nuala M; Hills, Andrew P

    2015-02-17

    The adolescent period is associated with changes in eating and activity behaviors in girls. Less reliance on parental provision and choice of food, coupled with a decrease in participation in physical activity and sport, can create an energy imbalance, predisposing to weight gain. Physiological alterations to body composition, reduction in insulin sensitivity, and psychological adjustments may further amplify the risk of becoming overweight and maintaining an unhealthy level of body fat into childbearing years. During pregnancy excess body fat is a risk factor for poor pregnancy outcomes and may predispose an infant to a lifelong heightened risk of being overweight and developing chronic disease. Interventions aimed at preventing the accumulation of body fat in adolescent girls and young women may have far reaching impact and be critically important in reducing intergenerational weight gain. Lifestyle interventions in adolescence have the potential to modify adult obesity risk by switching at-risk individuals from a high to lower obesity risk trajectory. This paper discusses multiple approaches to assist at-risk individuals reduce obesity risk. A key focus is placed on engagement in food preparation and choice, and opportunities for physical activity and sport. Support, education, and opportunity at home and at school, are often associated with the success of lifestyle interventions, and may enable adolescents to make positive choices, and engage in health promoting behaviors during adolescence and childbearing years.

  8. Overweight and Obese Adolescent Girls: The Importance of Promoting Sensible Eating and Activity Behaviors from the Start of the Adolescent Period

    PubMed Central

    Todd, Alwyn S.; Street, Steven J.; Ziviani, Jenny; Byrne, Nuala M.; Hills, Andrew P.

    2015-01-01

    The adolescent period is associated with changes in eating and activity behaviors in girls. Less reliance on parental provision and choice of food, coupled with a decrease in participation in physical activity and sport, can create an energy imbalance, predisposing to weight gain. Physiological alterations to body composition, reduction in insulin sensitivity, and psychological adjustments may further amplify the risk of becoming overweight and maintaining an unhealthy level of body fat into childbearing years. During pregnancy excess body fat is a risk factor for poor pregnancy outcomes and may predispose an infant to a lifelong heightened risk of being overweight and developing chronic disease. Interventions aimed at preventing the accumulation of body fat in adolescent girls and young women may have far reaching impact and be critically important in reducing intergenerational weight gain. Lifestyle interventions in adolescence have the potential to modify adult obesity risk by switching at-risk individuals from a high to lower obesity risk trajectory. This paper discusses multiple approaches to assist at-risk individuals reduce obesity risk. A key focus is placed on engagement in food preparation and choice, and opportunities for physical activity and sport. Support, education, and opportunity at home and at school, are often associated with the success of lifestyle interventions, and may enable adolescents to make positive choices, and engage in health promoting behaviors during adolescence and childbearing years. PMID:25690003

  9. Global tropospheric methane: An indication of atmosphere-biosphere-climate interactions?

    NASA Technical Reports Server (NTRS)

    Harriss, Robert C.; Sebacher, Daniel I.; Bartlett, Karen B.

    1985-01-01

    Methane is an important atmospheric gas with potentially critical roles in both photochemical and radiation transfer processes. A major natural source of atmospheric methane involves anaerobic fermentation of organic materials in wetland soils and sediments. A data base of field measurements of atmospheric methane was used in the development of a global methane emissions inventory. Calculations support the following hypotheses: (1) Human activities currently produce methane at a rate approximately equal to natural resources (these rapidly increasing anthropogenic sources can explain most of the recent increase observed in tropospheric methane); and (2) Prior to 200 B.P. (before the present), the influence of climate on wetland extent and distribution was probably a dominant factor controlling global biogenic methane emissions to the atmosphere.

  10. Coal Bed Methane Primer

    SciTech Connect

    Dan Arthur; Bruce Langhus; Jon Seekins

    2005-05-25

    During the second half of the 1990's Coal Bed Methane (CBM) production increased dramatically nationwide to represent a significant new source of income and natural gas for many independent and established producers. Matching these soaring production rates during this period was a heightened public awareness of environmental concerns. These concerns left unexplained and under-addressed have created a significant growth in public involvement generating literally thousands of unfocused project comments for various regional NEPA efforts resulting in the delayed development of public and fee lands. The accelerating interest in CBM development coupled to the growth in public involvement has prompted the conceptualization of this project for the development of a CBM Primer. The Primer is designed to serve as a summary document, which introduces and encapsulates information pertinent to the development of Coal Bed Methane (CBM), including focused discussions of coal deposits, methane as a natural formed gas, split mineral estates, development techniques, operational issues, producing methods, applicable regulatory frameworks, land and resource management, mitigation measures, preparation of project plans, data availability, Indian Trust issues and relevant environmental technologies. An important aspect of gaining access to federal, state, tribal, or fee lands involves education of a broad array of stakeholders, including land and mineral owners, regulators, conservationists, tribal governments, special interest groups, and numerous others that could be impacted by the development of coal bed methane. Perhaps the most crucial aspect of successfully developing CBM resources is stakeholder education. Currently, an inconsistent picture of CBM exists. There is a significant lack of understanding on the parts of nearly all stakeholders, including industry, government, special interest groups, and land owners. It is envisioned the Primer would being used by a variety of

  11. How photons start vision.

    PubMed Central

    Baylor, D

    1996-01-01

    Recent studies have elucidated how the absorption of a photon in a rod or cone cell leads to the generation of the amplified neural signal that is transmitted to higher-order visual neurons. Photoexcited visual pigment activates the GTP-binding protein transducin, which in turn stimulates cGMP phosphodiesterase. This enzyme hydrolyzes cGMP, allowing cGMP-gated cationic channels in the surface membrane to close, hyperpolarize the cell, and modulate transmitter release at the synaptic terminal. The kinetics of reactions in the cGMP cascade limit the temporal resolution of the visual system as a whole, while statistical fluctuations in the reactions limit the reliability of detection of dim light. Much interest now focuses on the processes that terminate the light response and dynamically regulate amplification in the cascade, causing the single photon response to be reproducible and allowing the cell to adapt in background light. A light-induced fall in the internal free Ca2+ concentration coordinates negative feedback control of amplification. The fall in Ca2+ stimulates resynthesis of cGMP, antagonizes rhodopsin's catalytic activity, and increases the affinity of the light-regulated cationic channel for cGMP. We are using physiological methods to study the molecular mechanisms that terminate the flash response and mediate adaptation. One approach is to observe transduction in truncated, dialyzed photoreceptor cells whose internal Ca2+ and nucleotide concentrations are under experimental control and to which exogenous proteins can be added. Another approach is to observe transduction in transgenic mouse rods in which specific proteins within the cascade are altered or deleted. PMID:8570595

  12. Atmospheric Methane Contributions From Fractured Bedrock Aquifers

    NASA Astrophysics Data System (ADS)

    Marrin, D. L.

    2013-05-01

    Groundwater is not normally considered as an important contributor of atmospheric methane because the organic carbon content of aquifers is too low to sustain significant methanogenesis. Also, groundwater-generated methane partitions into the gas phase of the overlying soil, where it either dissolves in the pore water or is oxidized to carbon dioxide by methanotrophs. There are, however, localized conditions (related to human activities and hydrogeologic conditions) under which atmospheric contributions of groundwater-generated methane occur at the ground surface. Storing and transporting liquid petroleum products in the subsurface has resulted in the local introduction of high concentrations of degradable organic carbon and the creation of redox conditions that favor methanogenesis over more oxidative biodegradation pathways. Groundwater overlain by fractured bedrock, rather than by unconsolidated porous media, creates a situation where CH4 migrates through discrete fractures, thus limiting the soil volume and the surface area available for methanotrophic activity. The spatial distribution of methane in thin surface soils overlying bedrock suggests that CH4 migrates via fracture networks and that CH4 oxidation is a factor of about 50 less than that measured in typical unconsolidated soils. Atmospheric flux rates associated with contaminated bedrock aquifers were on the order of several grams of carbon (as CH4) per square meter, which is less than that reported for well documented sources (e.g., rice paddies) and probably represents a minor worldwide contribution. Nonetheless, these aquifers can represent an important localized source, can shift soils from a sink to a source of methane, and can permit petroleum products to load carbon (as biogenic CH4 and CO2) to the atmosphere without ever being combusted.

  13. A tale of two methane monooxygenases

    PubMed Central

    Ross, Matthew O.

    2017-01-01

    Methane monooxygenase (MMO) enzymes activate O2 for oxidation of methane. Two distinct MMOs exist in nature, a soluble form that uses a diiron active site (sMMO) and a membrane-bound form with a catalytic copper center (pMMO). Understanding the reaction mechanisms of these enzymes is of fundamental importance to biologists and chemists, and is also relevant to the development of new biocatalysts. The sMMO catalytic cycle has been elucidated in detail, including O2 activation intermediates and the nature of the methane-oxidizing species. By contrast, many aspects of pMMO catalysis remain unclear, most notably the nuclearity and molecular details of the copper active site. Here, we review the current state of knowledge for both enzymes, and consider pMMO O2 activation intermediates suggested by computational and synthetic studies in the context of existing biochemical data. Further work is needed on all fronts, with the ultimate goal of understanding how these two remarkable enzymes catalyze a reaction not readily achieved by any other metalloenzyme or biomimetic compound. PMID:27878395

  14. Low upper limit to methane abundance on Mars.

    PubMed

    Webster, Christopher R; Mahaffy, Paul R; Atreya, Sushil K; Flesch, Gregory J; Farley, Kenneth A

    2013-10-18

    By analogy with Earth, methane in the Martian atmosphere is a potential signature of ongoing or past biological activity. During the past decade, Earth-based telescopic observations reported "plumes" of methane of tens of parts per billion by volume (ppbv), and those from Mars orbit showed localized patches, prompting speculation of sources from subsurface bacteria or nonbiological sources. From in situ measurements made with the Tunable Laser Spectrometer (TLS) on Curiosity using a distinctive spectral pattern specific to methane, we report no detection of atmospheric methane with a measured value of 0.18 ± 0.67 ppbv corresponding to an upper limit of only 1.3 ppbv (95% confidence level), which reduces the probability of current methanogenic microbial activity on Mars and limits the recent contribution from extraplanetary and geologic sources.

  15. Using Methane 14C to Determine the Origin of the Rapid Methane Rise at the End of the Younger Dryas 11,600 Years Ago: Increased Wetland Production or Methane Hydrates? A Progress Report.

    NASA Astrophysics Data System (ADS)

    Petrenko, V. V.; Severinghaus, J.; Brook, E.; Reeh, N.

    2002-12-01

    The atmospheric methane concentration rose from about 500 parts per billion (ppb) to about 750 ppb over a period of just 150 years at the termination of the Younger Dryas cold period 11,600 years ago, as indicated by Greenland ice core records. The start of this rapid methane increase was synchronous with an even more rapid climate warming -- Greenland ice core nitrogen and argon isotope records indicate that temperatures rose 5 - 10 ?C over just a few decades. There has been considerable debate about the source of this methane rise. Currently, the two main hypotheses attribute the methane rise either to increased bacterial methane production in wetlands, or to the dissociation of large quantities of methane hydrates on the ocean floor. Here we describe the progress of a project whose aim is to determine the origin of this methane rise. Our approach involves using 14C of ancient methane (derived from air bubbles in glacial ice) to determine its source. Methane hydrates are hundreds of thousands to millions of years old, and should contain virtually no 14C, whereas wetland-derived methane will have 14C content identical to that of atmospheric CO2 at the time of production. Obtaining enough ancient methane for a 14C measurement requires very large samples -- about 2 cubic meters. We have been able to locate a site on the western margin of the Greenland ice sheet where large amounts of uncontaminated ancient ice are available at the surface. Furthermore, our measurements of oxygen isotopes in the ice, as well as measurements of methane and oxygen and nitrogen isotopes in the air trapped in this ice have allowed us to date the ice and precisely locate the ice that contains the end-of-Younger-Dryas methane increase signal. Our data also demonstrate that the methane record in this ice is uncontaminated and suitable for methane 14C analysis. During the past year, we also constructed and are testing a device for melting and extracting air from large volumes of glacial ice.

  16. Observed variations of methane on Mars unexplained by known atmospheric chemistry and physics.

    PubMed

    Lefèvre, Franck; Forget, François

    2009-08-06

    The detection of methane on Mars has revived the possibility of past or extant life on this planet, despite the fact that an abiogenic origin is thought to be equally plausible. An intriguing aspect of the recent observations of methane on Mars is that methane concentrations appear to be locally enhanced and change with the seasons. However, methane has a photochemical lifetime of several centuries, and is therefore expected to have a spatially uniform distribution on the planet. Here we use a global climate model of Mars with coupled chemistry to examine the implications of the recently observed variations of Martian methane for our understanding of the chemistry of methane. We find that photochemistry as currently understood does not produce measurable variations in methane concentrations, even in the case of a current, local and episodic methane release. In contrast, we find that the condensation-sublimation cycle of Mars' carbon dioxide atmosphere can generate large-scale methane variations differing from those observed. In order to reproduce local methane enhancements similar to those recently reported, we show that an atmospheric lifetime of less than 200 days is necessary, even if a local source of methane is only active around the time of the observation itself. This implies an unidentified methane loss process that is 600 times faster than predicted by standard photochemistry. The existence of such a fast loss in the Martian atmosphere is difficult to reconcile with the observed distribution of other trace gas species. In the case of a destruction mechanism only active at the surface of Mars, destruction of methane must occur with an even shorter timescale of the order of approximately 1 hour to explain the observations. If recent observations of spatial and temporal variations of methane are confirmed, this would suggest an extraordinarily harsh environment for the survival of organics on the planet.

  17. Study of the performance of a thermophilic biological methanation system.

    PubMed

    Guneratnam, Amita Jacob; Ahern, Eoin; FitzGerald, Jamie A; Jackson, Stephen A; Xia, Ao; Dobson, Alan D W; Murphy, Jerry D

    2017-02-01

    This study investigated the operation of ex-situ biological methanation at two thermophilic temperatures (55°C and 65°C). Methane composition of 85-88% was obtained and volumetric productivities of 0.45 and 0.4LCH4/Lreactor were observed at 55°C and 65°C after 24h respectively. It is postulated that at 55°C the process operated as a mixed culture as the residual organic substrates in the starting inoculum were still available. These were consumed prior to the assessment at 65°C; thus the methanogens were now dependent on gaseous substrates CO2 and H2. The experiment was repeated at 65°C with fresh inoculum (a mixed culture); methane composition and volumetric productivity of 92% and 0.46LCH4/Lreactor were achieved in 24h. Methanothermobacter species represent likely and resilient candidates for thermophilic biogas upgrading.

  18. Biologically Produced Methane as a Renewable Energy Source.

    PubMed

    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 CO2. 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.

  19. Autotrophy as a predominant mode of carbon fixation in anaerobic methane-oxidizing microbial communities.

    PubMed

    Kellermann, Matthias Y; Wegener, Gunter; Elvert, Marcus; Yoshinaga, Marcos Yukio; Lin, Yu-Shih; Holler, Thomas; Mollar, Xavier Prieto; Knittel, Katrin; Hinrichs, Kai-Uwe

    2012-11-20

    The methane-rich, hydrothermally heated sediments of the Guaymas Basin are inhabited by thermophilic microorganisms, including anaerobic methane-oxidizing archaea (mainly ANME-1) and sulfate-reducing bacteria (e.g., HotSeep-1 cluster). We studied the microbial carbon flow in ANME-1/ HotSeep-1 enrichments in stable-isotope-probing experiments with and without methane. The relative incorporation of (13)C from either dissolved inorganic carbon or methane into lipids revealed that methane-oxidizing archaea assimilated primarily inorganic carbon. This assimilation is strongly accelerated in the presence of methane. Experiments with simultaneous amendments of both (13)C-labeled dissolved inorganic carbon and deuterated water provided further insights into production rates of individual lipids derived from members of the methane-oxidizing community as well as their carbon sources used for lipid biosynthesis. In the presence of methane, all prominent lipids carried a dual isotopic signal indicative of their origin from primarily autotrophic microbes. In the absence of methane, archaeal lipid production ceased and bacterial lipid production dropped by 90%; the lipids produced by the residual fraction of the metabolically active bacterial community predominantly carried a heterotrophic signal. Collectively our results strongly suggest that the studied ANME-1 archaea oxidize methane but assimilate inorganic carbon and should thus be classified as methane-oxidizing chemoorganoautotrophs.

  20. Methane/nitrogen separation process

    DOEpatents

    Baker, Richard W.; Lokhandwala, Kaaeid A.; Pinnau, Ingo; Segelke, Scott

    1997-01-01

    A membrane separation process for treating a gas stream containing methane and nitrogen, for example, natural gas. The separation process works by preferentially permeating methane and rejecting nitrogen. We have found that the process is able to meet natural gas pipeline specifications for nitrogen, with acceptably small methane loss, so long as the membrane can exhibit a methane/nitrogen selectivity of about 4, 5 or more. This selectivity can be achieved with some rubbery and super-glassy membranes at low temperatures. The process can also be used for separating ethylene from nitrogen.

  1. Methane/nitrogen separation process

    DOEpatents

    Baker, R.W.; Lokhandwala, K.A.; Pinnau, I.; Segelke, S.

    1997-09-23

    A membrane separation process is described for treating a gas stream containing methane and nitrogen, for example, natural gas. The separation process works by preferentially permeating methane and rejecting nitrogen. The authors have found that the process is able to meet natural gas pipeline specifications for nitrogen, with acceptably small methane loss, so long as the membrane can exhibit a methane/nitrogen selectivity of about 4, 5 or more. This selectivity can be achieved with some rubbery and super-glassy membranes at low temperatures. The process can also be used for separating ethylene from nitrogen. 11 figs.

  2. On methane pyrolysis special applications

    NASA Astrophysics Data System (ADS)

    Toncu, D. C.; Toncu, G.; Soleimani, S.

    2015-11-01

    Methane pyrolysis represents one of the most important processes in industrial use, with applications rising from the chemical and petrochemical industry, combustion, materials and protective coatings. Despite the intense research, experimental data lack kinetic aspects, and the thermodynamics involved often leads to inaccurate results when applied to various systems. Carrying out a comparative analysis of several available data on methane pyrolysis, the paper aims to study the phenomenon of methane pyrolysis under different environments (combustion and plasma), concluding on the most possible reaction pathways involved in many of its applications. Computer simulation using different database underlines the conclusion, helping to the understanding of methane pyrolysis importance in future technologies.

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

    NASA Astrophysics Data System (ADS)

    Klasek, S.; Tiantian, Y.; Torres, M. E.; Colwell, F. S.; Wang, F.; Liang, L.

    2015-12-01

    Marine sediments produce tens to hundreds of teragrams of methane annually, which is released from the seabed at thousands of cold seeps distributed globally along continental margins. Around 80-90% of this methane is consumed in shallower sediment layers before reaching the hydrosphere, in a microbially-mediated process known as anaerobic oxidation of methane (AOM) However, cold seeps appear to exhibit temporal variation in gas flux intensity, and AOM filter efficiency at cold seeps generally decreases with fluid flow rate. To our knowledge, the degree to which temporal heterogeneity in subsurface methane flux stimulates AOM community growth and adaptation to increased methane concentrations has not been investigated. Static high-pressure bioreactors were used to incubate sulfate-methane transition zone (SMTZ) and methanogenic zone sediments underlying a Mediterranean mud volcano gas flare under in situ temperature and pressure at 8 MPa methane. Sulfide production rates of 0.4 μmol/cm3/day in both sediment regimes after 4 months of incubation suggested the resilience of the marine subsurface methane filter may extend well below the SMTZ (40 cm). Similar incubations of SMTZ samples from below a gas flare off Svalbard at saturating (3.8 MPa) and 0.2 MPa methane are being sampled after 1 week, 4 weeks, and 4 months; sulfide production rates of 8-18 nmol/cm3/day were first observed after 4 weeks of incubation. Sediment samples at all specified time points for both sets of incubations were collected for nucleic acid extraction and cell fixation. Anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB) are expected dominant taxa in enriched and non-enriched communities. 16S rDNA community analysis is expected to reveal additional microbial players involved in the short-term adaptation to higher methane partial pressures in the marine subsurface. Increased AOM community activity (RNA/DNA ratio) and copy numbers of methane cycling transcripts (mcr

  4. Studying methane migration mechanisms at Walker Ridge, Gulf of Mexico, via 3D methane hydrate reservoir modeling

    SciTech Connect

    Nole, Michael; Daigle, Hugh; Mohanty, Kishore; Cook, Ann; Hillman, Jess

    2015-12-15

    . Therefore, it is likely that additional mechanisms are at play, notably bound water activity reduction in clays. Three-dimensionality allows for inclusion of lithologic heterogeneities, which focus fluid flow and subsequently allow for heterogeneity in the methane migration mechanisms that dominate in marine sediments at a local scale. Incorporating recently acquired 3D seismic data from Walker Ridge to inform the lithologic structure of our modeled reservoir, we show that even with deep adjective sourcing of methane along highly permeable pathways, local hydrate accumulations can be sourced either by diffusive or advective methane flux; advectively-sourced hydrates accumulate evenly in highly permeable strata, while diffusively-sourced hydrates are characterized by thin strata-bound intervals with high clay-sand pore size contrasts.

  5. Environmental control on aerobic methane oxidation in coastal waters

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  6. Consumption of atmospheric methane by tundra soils

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    The results of field and laboratory experiments on methane consumption by tundra soils are reported. For methane concentrations ranging from below to well above ambient, moist soils are found to consume methane rapidly; in nonwaterlogged soils, equilibration with atmospheric methane is fast relative to microbial oxidation. It is concluded that lowering of the water table in tundra as a resulting from a warmer, drier climate will decrease methane fluxes and could cause these areas to provide negative feedback for atmospheric methane.

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

    SciTech Connect

    None, None

    2014-02-01

    This final report document summarizes the activities undertaken and the output from three primary deliverables generated during this project. This fifteen month effort comprised numerous key steps including the creation of an international methane hydrate science team, determining and reporting the current state of marine methane hydrate research, convening an international workshop to collect the ideas needed to write a comprehensive Marine Methane Hydrate Field Research Plan and the development and publication of that plan. The following documents represent the primary deliverables of this project and are discussed in summary level detail in this final report: Historical Methane Hydrate Project Review Report; Methane Hydrate Workshop Report; Topical Report: Marine Methane Hydrate Field Research Plan; and Final Scientific/Technical Report.

  8. Methane-Stimulated Benthic Marine Nitrogen Fixation at Deep-Sea Methane Seeps

    NASA Astrophysics Data System (ADS)

    Dekas, A. E.; Orphan, V.

    2011-12-01

    Biological nitrogen fixation (the conversion of N2 to NH3) is a critical process in the oceans, counteracting the production of N2 gas by dissimilatory bacterial metabolisms and providing a source of bioavailable nitrogen to many nitrogen-limited ecosystems. Although current measurements of N2 production and consumption in the oceans indicate that the nitrogen cycle is not balanced, recent findings on the limits of nitrogen fixation suggest that the perceived imbalance is an artifact of an incomplete assessment of marine diazotrophy. One currently poorly studied and potentially underappreciated habitat for diazotrophic organisms is the sediments of the deep-sea. In the present study we investigate the distribution and magnitude of benthic marine diazotrophy at several active deep-sea methane seeps (Mound 12, Costa Rica; Eel River Basin, CA, USA; Hydrate Ridge, OR, USA; and Monterey Canyon, CA, USA). Using 15N2 and 15NH4 sediment incubation experiments followed by single-cell (FISH-NanoSIMS) and bulk isotopic analysis (EA-IRMS), we observed total protein synthesis (15N uptake from 15NH4) and nitrogen fixation (15N update from 15N2). The highest rates of nitrogen fixation observed in the methane seep sediment incubation experiments were over an order of magnitude greater than those previously published from non-seep deep-sea sediments (Hartwig and Stanley, Deep-Sea Research, 1978, 25:411-417). However, methane seep diazotrophy appears to be highly spatially variable, with sediments exhibiting no nitrogen fixation originating only centimeters away from sediments actively incorporating 15N from 15N2. The greatest spatial variability in diazotrophy was observed with depth in the sediment, and corresponded to steep gradients in sulfate and methane. The maximum rates of nitrogen fixation were observed within the methane-sulfate transition zone, where organisms mediating the anaerobic oxidation of methane are typically in high abundance. Additionally, incubation

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  10. Bioassay for estimating the biogenic methane-generating potential of coal samples

    USGS Publications Warehouse

    Jones, E.J.P.; Voytek, M.A.; Warwick, P.D.; Corum, M.D.; Cohn, A.; Bunnell, J.E.; Clark, A.C.; Orem, W.H.

    2008-01-01

    Generation of secondary biogenic methane in coal beds is likely controlled by a combination of factors such as the bioavailability of coal carbon, the presence of a microbial community to