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PubMed2005

Impact of post-methanation distillery effluent irrigation on groundwater quality.

Molasses-based distilleries generate large quantities of effluent, which is used for irrigation in many countries including India. The effluent is rich in organic and inorganic ions, which may leach down and pollute the groundwater. An on-farm experiment was conducted to assess the impact of long-term irrigation with post-methanation distillery effluent (PMDE) on nitrate, sulphate, chloride, sodium, potassium, and magnesium contents in the groundwater of two sites in northwest India. Electrical conductivity (EC), pH, total dissolved solids (TDS), sodium adsorption ratio (SAR) and colour were also determined to assess the chemical load in the groundwater. Nitrate content in the groundwater samples ranged from 16.95 mg L(-1) in the unamended fields to 59.81 mg L(-1) in the PMDE-amended fields during the 2-year study (2001-2002). Concentrations of TDS in water samples from tubewell of the amended field was higher by 40.4% over the tubewell water of the unamended field. Colour of the water samples of the amended fields was also darker than that of the unamended fields. The study indicated that the organic and inorganic ions added through the effluent could pose a serious threat to the groundwater quality if applied without proper monitoring.

Agriculture↗
PubMed2006

Invasive species and coal bed methane development in the Powder River Basin, Wyoming.

One of the fastest growing areas of natural gas production is coal bed methane (CBM) due to the large monetary returns and increased demand for energy from consumers. The Powder River Basin, Wyoming is one of the most rapidly expanding areas of CBM development with projections of the establishment of up to 50,000 wells. CBM disturbances may make the native ecosystem more susceptible to invasion by non-native species, but there are few studies that have been conducted on the environmental impacts of this type of resource extraction. To evaluate the potential effects of CBM development on native plant species distribution and patterns of non-native plant invasion, 36 modified Forest Inventory and Analysis plots (each comprised of four 168-m2 subplots) were established in the Powder River Basin, Wyoming. There were 73 168-m2 subplots on control sites; 42 subplots on secondary disturbances; 14 on major surface disturbances; eight on well pads; and seven on sites downslope of CBM wells water discharge points. Native plant species cover ranged from 39.5 +/- 2.7% (mean +/- 1 SE) in the secondary disturbance subplots to 17.7 +/- 7.5% in the pad subplots. Non-native plant species cover ranged from 31.0 +/- 8.4% in the discharge areas to 14.7 +/- 8.9% in the pad subplots. The control subplots had significantly less non-native species richness than the combined disturbance types. The combined disturbance subplots had significantly greater soil salinity than the control sites. These results suggest that CBM development and associated disturbances may facilitate the establishment of non-native plants. Future research and management decisions should consider the accumulative landscape-scale effects of CBM development on preserving native plant diversity.

Coal Mining↗
PubMed1985

Amperometric responses to acetylene, ethylene, and methane by a Clark-type oxygen electrode.

Hydrogen-conditioned Clark electrodes exposed to successive acetylene samples displayed a decreasing curvilinear response. Slight electrode responses are also effected by saturated ethylene solutions. Thus, amperometric measurements of hydrogen or carbon monoxide in the aqueous environment by these electrodes are perturbated by the presence of acetylene and to a much lesser extent by ethylene. Methane-saturated solutions induced no electrode response.

Acetylene↗
PubMed1987

On the role of N-7-mercaptoheptanoyl-O-phospho-L-threonine (component B) in the enzymatic reduction of methyl-coenzyme M to methane.

The reduction of methyl-coenzyme M (CH3SCoM) to methane in methanogenic bacteria is dependent on component B (N-7-mercaptoheptanoyl-O-phospho-L-threonine, HSHTP). We report here that S-methyl-component B (N-7-(methylthio)heptanoyl-O-phospho-L-threonine, CH3SHTP) can substitute for neither CH3SCoM nor HSHTP in the methyl-CoM reductase reaction. Rather, CH3SHTP proved to be an inhibitor competitive with HSHTP (apparent Ki = 6 microM) and noncompetitive with CH3SCoM. These results make it very unlikely that HSHTP functions as a methyl group carrier. A role for HSHTP as direct electron donor for CH3SCoM reduction to CH4 is proposed.

Chromatography, Gas↗
PubMed1987

7-Mercaptoheptanoylthreonine phosphate functions as component B in ATP-independent methane formation from methyl-CoM with reduced cobalamin as electron donor.

Purified methyl-CoM reductase of Methanobacterium thermoautotrophicum (strain Marburg) catalyzed the reduction of methyl-CoM to methane with reduced cobalamin, when either synthetic 7-mercaptoheptanoylthreonine phosphate (HS-HTP) or naturally occurring component B was present. With both compounds the same maximal specific activity was obtained and ATP was neither required nor stimulatory. These findings indicate that HS-HTP functions as component B and do not support the idea that HS-HT is only active in an adenosine monophosphorylated form.

Adenosine Triphosphate↗
PubMed1990

Ferredoxin-dependent methane formation from acetate in cell extracts of Methanosarcina barkeri (strain MS).

Cell extracts of Methanosarcina barkeri grown on acetate catalyzed the conversion of acetyl-CoA to CO2 and CH4 at a specific rate of 50 nmol min-1 mg-1. When ferredoxin was removed from the extracts by DEAE-Sephacel anion exchange chromatography, the extracts were inactive but full activity was restored upon addition of purified ferredoxin from M. barkeri or from Clostridium pasteurianum. The apparent Km for ferredoxin from M. barkeri was determined to be 2.5 M. A ferredoxin dependence was also found for the formation of CO2, H2 and methylcoenzyme M from acetyl-CoA, when methane formation was inhibited by bromoethanesulfonate. Reduction of methyl-coenzyme M with H2 did not require ferredoxin. These and other data indicate that ferredoxin is involved as electron carrier in methanogenesis from acetate. Methanogenesis from acetyl-CoA in cell extracts was not dependent on the membrane fraction, which contains the cytochromes.

Acetates↗
PubMed1989

Methylation of thymine and uracil with free methyl cations formed due to beta-decay of tritiated methane: possible implication in mutagenesis and carcinogenesis.

Exposure of solid thymine and uracil at room temperature to free methyl cations, produced due to beta-decay of tritiated methane, resulted in formation of their 1-, O2-, 3-, O4-, and 6-methyl derivatives. In addition, uracil formed a 5-methyl derivative (thymine); tritium-containing thymine and uracil were also detected. Both thymine and uracil formed predominantly unidentified products which resulted presumably from their oligomerization. Incubation at -195 degrees C did not markedly change the pattern of reaction products. Aqueous-ammonia solutions of these pyrimidines formed methylated derivatives and considerable amounts of methanol and tritiated water. The possible implication of these reactions in mutagenic and carcinogenic effects of tritium-substituted hydrocarbons is discussed.

Alkylating Agents↗
PubMed1988

Modeling the tissue solubilities and metabolic rate constant (Vmax) of halogenated methanes, ethanes, and ethylenes.

Experimental solvent:air and tissue:air partition coefficients for 25 halogenated methanes, ethanes, and ethylenes in saline solution; olive oil; and rat blood, muscle, liver, and fat tissues have been examined using theoretical molecular modeling techniques. The metabolic rate constant, Vmax, was also investigated by these techniques for 19 chlorinated compounds in this group. Two graph theoretical approaches (the distance method of Wiener and the connectivity index method of Randic, Kier, and Hall) and an approach utilizing ad hoc molecular descriptors were employed. Satisfactory regression models for solubility were obtained with both the Randic-Kier-Hall approach and the ad hoc descriptors approach. Fluorine substituents decrease tissue solubilities, whereas both clorine and bromine substituents increase tissue solubilities, with the relative influence being Cl less than Br. Tissue solubilities can also be represented conveniently in terms of contributions from oil and saline solubilities, a procedure reinforced by factor analysis of the data. Equations derived by these methods adequately estimated the solubilities for eight additional compounds. No approach could successfully model Vmax for all 19 compounds, but a subset of 16 compounds was modeled using the connectivity indices. The equation is limited in its use but indicated future modeling directions for Vmax.

Adipose Tissue↗
PubMed1988

Studies on asphyxia: on the changes of the alveolar walls of rats in the hypoxic state. II. The hypoxic state produced by carbon dioxide and methane gases.

Experimental studies were presented here concerning death by asphyxia due to the inhalation of carbon dioxide and methane gases. The morphological changes were almost the same as those demonstrated in our previous report. The authors concluded that the morphological changes in the lung tissue were not attributable to the chemical specificity of gases used in the experiment but to the decrease of oxygen.

Animals↗
PubMed2006

Production of hydrogen and methane from organic solid wastes by phase-separation of anaerobic process.

Phase-separated two-stage anaerobic process was examined and evaluated using artificial organic solid waste in laboratory scale. Acidogenic process, which was combined with subsequent methanogenic process using packed-bed reactor, was operated emphasizing on either hydrogen production, or solublizing efficiency of solid materials. In either effluent from hydrogenogenic, or solublizing operation, maximum allowable OLR achieved at methanogenesis was higher than the single methanogenic process. Hydrogenogenic operation was more suitable to combine methanogenic process than solublizing operation, since retention time of hydrogenogenic operation was much shorter than the solublizing operation, obtaining almost the same levels of overall removal efficiency in both COD and VSS. The combination of hydrogenogenic operation in acidogenic process and methanogenic process produced approximately 442mmoll-reactor(1)days(-1) of methane and 199mmoll-reactor(1)days(-1) of hydrogen at 25h of total retention time indicating 82% of COD removal with 96% of VSS decomposition.

Anaerobiosis↗
PubMed2005

Photochemical production of methane in natural waters: implications for its present and past oceanic source.

We conducted irradiation experiments with riverine, estuarine, and marine water samples to investigate the possibility of photochemical methane (CH4) formation. CH4 photoproduction was undetectable under oxic conditions or in the absence of methyl radical precursors indicating that its photochemical formation is negligible in the present ocean. Significant photochemical CH4 production was observed in the presence of a methyl radical precursor such as acetone under strictly anoxic conditions. Our results indicate an indirect formation mechanism with coloured dissolved organic matter acting as photosensitizer. We suggest that photochemical CH4 formation might have occurred in the anoxic ocean surface layer of the Archean prior to the onset of O2 accumulation in the atmosphere at around 2300 million years ago. Oceanic CH4 photoproduction via methyl radical (CH3) precursors and its subsequent release to the atmosphere may have contributed to high CH4 mixing ratios in the Archean atmosphere.

Archaea↗
PubMed2005

Mitigating nitrous oxide and methane emissions from soil in rice-wheat system of the Indo-Gangetic plain with nitrification and urease inhibitors.

Mitigation of methane (CH4) and nitrous oxide (N2O) emissions from soil is important to reduce the global warming. Efficacy of five nitrification inhibitors, i.e. neem (Azadirachta melia) cake, thiosulphate, coated calcium carbide, neem oil coated urea and dicyandiamide (DCD) and one urease inhibitor, hydroquinone, in mitigating N2O and CH4 emissions from fertilized soil was tested in rice-wheat system in the Indo-Gangetic plains. The closed chamber technique was used for the collection of gas samples, which were analyzed using gas chromatography. Reduction in N2O emission on the application of nitrification/urease inhibitors along with urea ranged from 5% with hydroquinone to 31% with thiosulphate in rice and 7% with hydroquinone to 29% with DCD in wheat crop. The inhibitors also influenced the emission of CH4. While application of neem coated urea, coated calcium carbide, neem oil and DCD reduced the emission of CH4; hydroquinone and thiosulphate increased the emission when compared to urea alone. However, the global warming potential was lower with the inhibitors (except hydroquinone) as compared to urea alone, suggesting that these substances could be used for mitigating greenhouse gas emission from the rice-wheat systems.

Acetylene↗
PubMed2005

Oxidation of methane over palladium catalysts: effect of the support.

This work is focused on the deep catalytic oxidation of methane over supported palladium catalysts. The influences of the metal loading, oxidation state of palladium, nature of supports, presence of promoters in the supports (for zirconia-based supports), and thermal stability have been studied experimentally. Catalysts were prepared by incipient wetness of commercially available supports with aqueous solutions of palladium nitrate. For gamma-alumina support, it was observed that the optimal amount of palladium is between 0.5% and 2%, with higher amounts leading to a loss in specific activity. Concerning the oxidation state of the catalyst, it is concluded that for all the supports tested in the present work, a reduction of the catalyst is not needed, yielding the same conversion at steady state catalysts reduced and oxidised. The thermal stability of various supported catalysts were also studied, zirconia supports being the most active. These supports, specially Y-modified zirconia support, do not suffer appreciable deactivation below 500 degrees C.

Air Pollution↗
PubMed2004

Application of micrometeorological approaches to measure methane exchange in a dry paddy field in the western coast of Korea.

The exchange processes of CH4 were investigated in a paddy field in the Hari area of Kang Hwa Island over an 8 day period in late April 2002. The quantification of CH4 fluxes was made under dry field condition of early spring by concurrently measuring its concentrations (at the two heights of 1 and 5 m) and the relevant micrometeorological parameters. To help elucidate the factors determining the mobilization characteristics of CH4, the results of our measurement data were examined using a number of approaches. The results of the trajectory analysis indicated that its concentration changed very sensitively with the influence of different source types, as seen from the air mass movement patterns. The concentrations and fluxes of methane, when examined over this short-term scale, showed moderately strong patterns across 24h period in which higher values tend to occur during morning or evening. The overall results of our field measurements suggest that CH4 exchange processes in the paddy area proceeded in a fairly complicated manner. The study area behaved as a net source of CH4 to the atmosphere with a net daily emission rate of 3.6 mgm(-2) despite the fact that downward deposition was observed more frequently than upward emission.

Air Pollutants↗
PubMed2005

Methane fluxes from tundra soils and snowpack in the maritime Antarctic.

Methane fluxes were measured from three exposed tundra sites and four snowpack sites on the Fildes Peninsula in the maritime Antarctic in the summertime of 2002. The average fluxes at two normal tundra sites were -15.3 microgm(-2)h(-1) and -14.3 microgm(-2)h(-1), respectively. The fluxes from tundra site with fresh penguin dropping addition showed positive values with the average of 36.1 microgm(-2)h(-1), suggesting that the deposition of fresh droppings greatly enhanced CH4 emissions from the poor Antarctic tundra during penguin breeding periods. The summertime variation in CH4 flux was correlated with surface ground temperature and the precipitation. The correlation between the flux and PT0, which is the product of the precipitation and surface ground temperature, was quite strong. The diurnal cycle of CH4 flux from the tundra soils was not obtained due to local fluky weather conditions. The fluxes through four snowpack sites were also obtained by the vertical CH4 concentration gradient and their average fluxes were -46.5 microgm(-2)h(-1), -28.2 microgm(-2)h(-1), -46.4 microgm(-2)h(-1) and -17.9 microgm(-2)h(-1), respectively, indicating that tundra soils under snowpack also consume atmospheric CH4 in the maritime Antarctic; therefore these fluxes could constitute an important part of the annual CH4 budget for Antarctic tundra ecosystem.

Animals↗
PubMed2006

Ammonia removal from pretreated methane fermentation effluent through a soil trench system: a column experiment.

In order to find the optimal running conditions and mechanisms of ammonia removal through a soil trench system that is designed for treating pretreated methane fermentation effluent, a soil column whose structure was similar to the soil trench system was prepared, and irrigated with wastewater below 30 degrees C. At the beginning, ammonia was mainly adsorbed by the soils, and the ammonia adsorption capacity of soils gradually saturated. After the 12th day, nitrification began in the soil column; the ammonia in the soil column decreased sharply, and the nitrite and nitrate peak appeared sequentially as the wastewater application rate decreased from 0.74 to 0.37 l h(-1). When the nitrification in the soil column reached a steady-state, 98% of all the ammonia in the influent was transformed into nitrate. By changing the running conditions such as temperature, aeration, and wastewater application rate, it was found that the ammonia removal efficiency can be improved by aeration and impeded by low temperature. In these three variables, wastewater application rate has much greater affect on the ammonia removal efficiency; a lower wastewater application rate can increase the ammonia removal efficiency substantially because of the longer travel time.

Adsorption↗
PubMed2005

Efficiency for unretained solutes in packed column supercritical fluid chromatography II. Experimental results for elution of methane using large pressure drops.

At near-critical temperatures and pressures, experimental results for elution of methane with neat carbon dioxide on a 150 mm x 2.0 mm I.D. column packed with 5 microm porous silica with a bonded octylsilica stationary phase show much greater efficiency losses than predicted by theory if isothermal conditions are assumed. Experiments with insulated, air- and water-thermostatted columns demonstrate that significant axial and radial temperature gradients are produced by Joule-Thomson cooling of the mobile phase, and that radial temperature gradients can be a major cause of band spreading at low temperatures and pressures. The use of thermal insulation on the column can greatly improve efficiency under these conditions.

Carbon Dioxide↗
PubMed2006

Evaluation of solid adsorbent materials for cryogen-free trapping-gas chromatographic analysis of atmospheric C2-C6 non-methane hydrocarbons.

Nine commercial solid adsorbent materials (in order of decreasing surface area: Carboxen 1000, Carbosieve S III, molecular sieve 5A, molecular sieve 4A, silica gel, Carboxen 563, activated alumina, Carbotrap and Carboxen 1016) were investigated for their ability to trap and release C2-C6 non-methane hydrocarbons (NMHCs) in atmospheric samples for subsequent thermal desorption gas chromatography-flame ionization detection analysis (GC-FID). Recovery rates for 23 NMHCs and methyl chloride (CH3Cl) were determined. A microtrap filled with the three adsorbents Carbosieve S III, Carboxen 563 and Carboxen 1016 was found to allow for the analysis of the widest range of target analytes. A detection limit of approximately 3pptC [parts per trillion (carbon)] in a 1l air sample and a linear response over a wide range of volatilities and sample volumes was determined for this configuration. Water vapor in the sample air was found to causes interference in trapping and subsequent chromatographic analysis of light NMHCs. A Peltier-cooled, regenerable water trap inserted into the sample flow path was found to mitigate these problems and to allow quantitative and reproducible results for all analytes at all tested humidity conditions.

Adsorption↗