Sample records for modeling methane emissions

  1. Modeling methane emissions from boreal peatlands

    NASA Astrophysics Data System (ADS)

    Raivonen, Maarit; Smolander, Sampo; Mäkelä, Jarmo; Tomasic, Marin; Aalto, Tuula; Markkanen, Tiina; Susiluoto, Jouni; Kleinen, Thomas; Brovkin, Victor; Rinne, Janne; Lohila, Annalea; Aurela, Mika; Vesala, Timo

    2014-05-01

    Natural wetlands are a significant source of methane (CH4): they have been estimated to account for about 30% of total global CH4 emissions. At the moment, the emission estimates are highly uncertain. These natural emissions respond to climatic variability, so it is necessary to understand their dynamics, in order to be able to predict how they affect the greenhouse-gas balance in the future. We have developed a model of CH4 production and transport in boreal peatlands. The aim is to make it a part of JSBACH, the land component of the Earth System Model of MPI Hamburg. The soil carbon model of JSBACH simulates peatland carbon processes like peat accumulation and decomposition and our CH4 module simulates production of CH4 as a proportion of the anaerobic peat decomposition, transport of CH4 and oxygen between the soil and the atmosphere, and oxidation of CH4 by methanotrophic microbes. The model has the three main pathways for transport: diffusion in aerenchymatous plants and in peat pores (water and air filled) and CH4 ebullition. The oxidation of CH4 depends on the oxygen concentrations in the peat. The model is largely based on existing models of CH4 production and transport but it includes some modifications that we will present here. We also will present the results of the first validations against observational data. The datasets are from two Finnish peatland sites, Siikaneva (southern) and Lompolojänkkä (northern Finland). Measurements of eddy covariance CH4 and CO2 fluxes and meteorological variables, as well as diverse ecological studies have been carried out on both sites over several years.

  2. Impact of transport model errors on the global and regional methane emissions estimated by inverse modelling

    E-print Network

    Locatelli, R.

    A modelling experiment has been conceived to assess the impact of transport model errors on methane emissions estimated in an atmospheric inversion system. Synthetic methane observations, obtained from 10 different model ...

  3. Methane emission from sewers.

    PubMed

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

    2015-08-15

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

  4. Modeling methane emissions by cattle production systems in Mexico

    NASA Astrophysics Data System (ADS)

    Castelan-Ortega, O. A.; Ku Vera, J.; Molina, L. T.

    2013-12-01

    Methane emissions from livestock is one of the largest sources of methane in Mexico. The purpose of the present paper is to provide a realistic estimate of the national inventory of methane produced by the enteric fermentation of cattle, based on an integrated simulation model, and to provide estimates of CH4 produced by cattle fed typical diets from the tropical and temperate climates of Mexico. The Mexican cattle population of 23.3 million heads was divided in two groups. The first group (7.8 million heads), represents cattle of the tropical climate regions. The second group (15.5 million heads), are the cattle in the temperate climate regions. This approach allows incorporating the effect of diet on CH4 production into the analysis because the quality of forages is lower in the tropics than in temperate regions. Cattle population in every group was subdivided into two categories: cows (COW) and other type of cattle (OTHE), which included calves, heifers, steers and bulls. The daily CH4 production by each category of animal along an average production cycle of 365 days was simulated, instead of using a default emission factor as in Tier 1 approach. Daily milk yield, live weight changes associated with the lactation, and dry matter intake, were simulated for the entire production cycle. The Moe and Tyrrell (1979) model was used to simulate CH4 production for the COW category, the linear model of Mills et al. (2003) for the OTHE category in temperate regions and the Kurihara et al. (1999) model for the OTHE category in the tropical regions as it has been developed for cattle fed tropical diets. All models were integrated with a cow submodel to form an Integrated Simulation Model (ISM). The AFRC (1993) equations and the lactation curve model of Morant and Gnanasakthy (1989) were used to construct the cow submodel. The ISM simulates on a daily basis the CH4 production, milk yield, live weight changes associated with lactation and dry matter intake. The total daily CH4 emission per region was calculated by multiplying the number of heads of cattle in each region by their corresponding simulated emission factor, either COW or OTHE, as predicted by the ISM. The total CH4 emissions from the Mexican cattle population was then calculated by adding up the daily emissions from each region. The predicted total emission of methane produced by the 23.3 million heads of cattle in Mexico is approximately 2.02 Tg/year, from which 1.28 Tg is produced by cattle in temperate regions and the rest by cattle in the tropics. It was concluded that the modeling approach was suitable in producing a better estimate of the national methane inventory for cattle. It is flexible enough to incorporate more cattle groups or classification schemes and productivity levels.

  5. A field-validated model for landfill methane emissions inclusive of seasonal methane oxidation

    NASA Astrophysics Data System (ADS)

    Bogner, J. E.; Spokas, K.; Chanton, J.

    2010-12-01

    In addition to natural wetlands, atmospheric methane (CH4) has multiple anthropogenic sources with high uncertainties, including rice production, ruminant animals, natural gas leakages, biomass burning, and landfills. For an improved IPCC Tier III methodology for landfill CH4 emissions in California, we have developed a new science-based, field-validated inventory model which decouples emissions from a historical reliance on a theoretical first order kinetic model for CH4 generation potential. The model (CALMIM, CAlifornia Landfill Methane Inventory Model) is a freely-available JAVA tool which estimates net CH4 emissions to the atmosphere for any landfill cover soil over a typical annual cycle, including (1) the effect of engineered gas extraction; (2) the physical effects of daily, intermediate, and final cover materials to retard emissions; and (3) seasonal soil moisture and temperature effects on both gaseous transport and methanotrophic CH4 oxidation. Linking site-specific data with existing globally-validated USDA models for annual climate and soil microclimate (Global TempSim; Global RainSim; Solarcalc; STM2), this model relies on 1-D diffusion as the major driver for emissions. Importantly, unlike current inventory methods based on modeled generation, the driving force for emissions (e.g., the CH4 concentration gradient) can be directly compared to field data. Methane oxidation is scaled to maximum rates over the full range of moisture and temperature conditions based on extensive supporting laboratory studies using California landfill cover soils. Field validation included meteorological data, soil moisture/temperature measurements, and seasonal (wet/dry) CH4 emissions & oxidation measurements for daily, intermediate, and final cover soils over two annual cycles at a northern (Monterey County) and southern California (Los Angeles County) landfill. The model accurately predicted soil temperature and moisture trends for individual cover materials with acceptable order-of-magnitude predictability for field emissions within the context of published literature spanning 7 orders of magnitude. In addition to regional defaults for inventory purposes, CALMIM permits user-selectable parameters and boundary conditions for more rigorous site-specific applications where detailed CH4 emissions, meteorological, and soil microclimate data exist.

  6. Impact of transport model errors on the global and regional methane emissions estimated by inverse modelling

    NASA Astrophysics Data System (ADS)

    Locatelli, R.; Bousquet, P.; Chevallier, F.; Fortems-Cheney, A.; Szopa, S.; Saunois, M.; Agusti-Panareda, A.; Bergmann, D.; Bian, H.; Cameron-Smith, P.; Chipperfield, M. P.; Gloor, E.; Houweling, S.; Kawa, S. R.; Krol, M.; Patra, P. K.; Prinn, R. G.; Rigby, M.; Saito, R.; Wilson, C.

    2013-04-01

    A modelling experiment has been conceived to assess the impact of transport model errors on the methane emissions estimated by an atmospheric inversion system. Synthetic methane observations, given by 10 different model outputs from the international TransCom-CH4 model exercise, are combined with a prior scenario of methane emissions and sinks, and integrated into the PYVAR-LMDZ-SACS inverse system to produce 10 different methane emission estimates at the global scale for the year 2005. The same set-up has been used to produce the synthetic observations and to compute flux estimates by inverse modelling, which means that only differences in the modelling of atmospheric transport may cause differences in the estimated fluxes. In our framework, we show that transport model errors lead to a discrepancy of 27 Tg CH4 per year at the global scale, representing 5% of the total methane emissions. At continental and yearly scales, transport model errors have bigger impacts depending on the region, ranging from 36 Tg CH4 in north America to 7 Tg CH4 in Boreal Eurasian (from 23% to 48%). At the model gridbox scale, the spread of inverse estimates can even reach 150% of the prior flux. Thus, transport model errors contribute to significant uncertainties on the methane estimates by inverse modelling, especially when small spatial scales are invoked. Sensitivity tests have been carried out to estimate the impact of the measurement network and the advantage of higher resolution models. The analysis of methane estimated fluxes in these different configurations questions the consistency of transport model errors in current inverse systems. For future methane inversions, an improvement in the modelling of the atmospheric transport would make the estimations more accurate. Likewise, errors of the observation covariance matrix should be more consistently prescribed in future inversions in order to limit the impact of transport model errors on estimated methane fluxes.

  7. A modeling perspective on wetland methane production and emission

    NASA Astrophysics Data System (ADS)

    Xu, X.; Riley, W. J.; Koven, C. D.

    2014-12-01

    Methane (CH4) is the third most important greenhouse gas after H2O and CO2. The effects of global warming on wetland hydrology have a strong impact on wetland CH4 production and emission, via both hydrologic and biogeochemical processes, presenting a challenge to accurate projection of CH4 responses to climate change. We are working on the development of CH4 module—including CH4 production, consumption and transport processes— in the Community Land Model (CLM4.5) in order to estimate CH4 fluxes in a regional and global scale. However, high uncertainties are still present in sensitivity of CH4 production to soil temperature, hydrology, pH and redox potential, rough treatment to vertical soil resolution and fractional inundation, and simplified parameterizing of CH4 transport and emissions. Our research aims to (1) use tower eddy covariance and aircraft measurements of CH4 concentration and surface flux to test the CH4 processes in CLM model; (2) obtain a better understanding and parameterization of the biogeochemical and biogeophysical processes of high latitude wetland CH4 production and emission; (3) assess impact of climate variability on wetland CH4 emission. Our analysis of CLM shows that the modeled predictions of the seasonal cycle of CH4 in high latitude wetlands is very sensitive to active layer hydrological cycle. The abrupt soil water increase in the period of soil thawing and snow melting leads to unrealistically large emissions of CH4 during the spring season. We present improvements required to generate realistic seasonal cycles of high latitude CH4 fluxes in the model.

  8. Impact of transport model errors on the global and regional methane emissions estimated by inverse modelling

    NASA Astrophysics Data System (ADS)

    Locatelli, R.; Bousquet, P.; Chevallier, F.; Fortems-Cheney, A.; Szopa, S.; Saunois, M.; Agusti-Panareda, A.; Bergmann, D.; Bian, H.; Cameron-Smith, P.; Chipperfield, M. P.; Gloor, E.; Houweling, S.; Kawa, S. R.; Krol, M.; Patra, P. K.; Prinn, R. G.; Rigby, M.; Saito, R.; Wilson, C.

    2013-10-01

    A modelling experiment has been conceived to assess the impact of transport model errors on methane emissions estimated in an atmospheric inversion system. Synthetic methane observations, obtained from 10 different model outputs from the international TransCom-CH4 model inter-comparison exercise, are combined with a prior scenario of methane emissions and sinks, and integrated into the three-component PYVAR-LMDZ-SACS (PYthon VARiational-Laboratoire de Météorologie Dynamique model with Zooming capability-Simplified Atmospheric Chemistry System) inversion system to produce 10 different methane emission estimates at the global scale for the year 2005. The same methane sinks, emissions and initial conditions have been applied to produce the 10 synthetic observation datasets. The same inversion set-up (statistical errors, prior emissions, inverse procedure) is then applied to derive flux estimates by inverse modelling. Consequently, only differences in the modelling of atmospheric transport may cause differences in the estimated fluxes. In our framework, we show that transport model errors lead to a discrepancy of 27 Tg yr-1 at the global scale, representing 5% of total methane emissions. At continental and annual scales, transport model errors are proportionally larger than at the global scale, with errors ranging from 36 Tg yr-1 in North America to 7 Tg yr-1 in Boreal Eurasia (from 23 to 48%, respectively). At the model grid-scale, the spread of inverse estimates can reach 150% of the prior flux. Therefore, transport model errors contribute significantly to overall uncertainties in emission estimates by inverse modelling, especially when small spatial scales are examined. Sensitivity tests have been carried out to estimate the impact of the measurement network and the advantage of higher horizontal resolution in transport models. The large differences found between methane flux estimates inferred in these different configurations highly question the consistency of transport model errors in current inverse systems. Future inversions should include more accurately prescribed observation covariances matrices in order to limit the impact of transport model errors on estimated methane fluxes.

  9. The determination of agricultural methane emissions in New Zealand using inverse modelling techniques

    NASA Astrophysics Data System (ADS)

    Gimson, Neil R.; Uliasz, Marek

    A receptor-oriented modelling system, consisting of a mesoscale meteorological model (RAMS) and a Lagrangian particle dispersion model (LPD) is applied to the determination of emissions of methane from livestock in agricultural regions in New Zealand. Aircraft measurements of methane mixing ratio profiles are input to the model, from which influence functions are obtained; these are the footprints of potential contributing emissions. Inversion techniques and statistical analysis enable the determination of confidence intervals for methane emissions. Results are compared with prior emissions data obtained by other methods. For two case studies in the Manawatu region of New Zealand in June 1995 and April 1997, methane emission fluxes of 54±32 and 56±54 mg m -2 d -1 are obtained (95% confidence intervals). These are consistent with independently estimated per-animal emission rates and observed livestock densities. For a field campaign in New Zealand's Waikato region in 1999, where no emissions estimates were available a priori, the average emission fluxes derived using receptor-oriented techniques are 67±46 mg m -2 d -1. The error-bars on the emission fluxes are arguably quite large. This is due to uncertainties in the methane observations and errors in the meteorological simulations, which play a different role in each case study. Improvements in both the experimental and modelling procedures are proposed to reduce uncertainties in the calculated emission fluxes.

  10. Modeling methane emissions from rice fields: variability, uncertainty, and sensitivity analysis of processes involved

    Microsoft Academic Search

    P. M. van Bodegom; P. A. Leffelaar; A. J. M. Stams; R. Wassmann

    2000-01-01

    \\u000a Estimates of global methane (CH4) emissions, to which rice cropping systems contribute significantly, are uncertain. The variability and uncertainty of variables\\u000a governing emission rates and the sensitivity of emissions to these variables determine the accuracy of CH4 emission estimates. A good tool for quantification of sensitivities is a process-based model. This paper describes a model\\u000a that has been validated previously

  11. Process - based modeling of northern wetland methane emissions - what are the limits?

    NASA Astrophysics Data System (ADS)

    van Huissteden, J. Ko; Mi, Yanjiao; Budishchev, Artem; Gallagher, Angela; Belelli-Marchesini, Luca; Dolman, A. J. Han

    2015-04-01

    Modeling of methane emissions in boreal and arctic wetlands is an important instrument for upscaling from plot to global scale emissions. However, the limits of this approach may have been reached with the current generation of models, which are generally based on plot-scale (semi)process based models. The problem starts with model testing; this still largely relies on chamber flux measurements rather than eddy covariance data; testing of plot-scale models using eddy covariance data requires an upscaling step in itself. Existing models often do not capture day-to-day variability in methane fluxes very well. They perform better on seasonal variability, but sometimes only after considerable model tuning. However, parameter uncertainty remains the largest problem. The typical wetland methane model has a high parameter demand, requiring detailed parameteriziation of hydrology, soil heat transfer, vegetation, biogeochemistry and carbon exchange. Improvements of process detail in the models leads to more parameter-hungry models, while improvement of the performance may be marginally only. Boreal and arctic environments are notoriously difficult for obtaining correct values of model parameters and other inputs. Additional complications are the role of soil freezing and snow cover. Typically there is also an extreme spatial variability of soil hydrology due to the presence of periglacial microrelief. Therefore process-based modeling of northern wetland methane emission may have reached its limits. Advances must be sought in decrease of model data requirements, making better use of wetland spatial variability patterns and remote sensing data, rather than implementing more process detail.

  12. Near-Field Characterization of Methane Emission Variability from a Compressor Station Using a Model Aircraft.

    PubMed

    Nathan, Brian J; Golston, Levi M; O'Brien, Anthony S; Ross, Kevin; Harrison, William A; Tao, Lei; Lary, David J; Johnson, Derek R; Covington, April N; Clark, Nigel N; Zondlo, Mark A

    2015-07-01

    A model aircraft equipped with a custom laser-based, open-path methane sensor was deployed around a natural gas compressor station to quantify the methane leak rate and its variability at a compressor station in the Barnett Shale. The open-path, laser-based sensor provides fast (10 Hz) and precise (0.1 ppmv) measurements of methane in a compact package while the remote control aircraft provides nimble and safe operation around a local source. Emission rates were measured from 22 flights over a one-week period. Mean emission rates of 14 ± 8 g CH4 s(-1) (7.4 ± 4.2 g CH4 s(-1) median) from the station were observed or approximately 0.02% of the station throughput. Significant variability in emission rates (0.3-73 g CH4 s(-1) range) was observed on time scales of hours to days, and plumes showed high spatial variability in the horizontal and vertical dimensions. Given the high spatiotemporal variability of emissions, individual measurements taken over short durations and from ground-based platforms should be used with caution when examining compressor station emissions. More generally, our results demonstrate the unique advantages and challenges of platforms like small unmanned aerial vehicles for quantifying local emission sources to the atmosphere. PMID:26011292

  13. Estimating Global Natural Wetland Methane Emissions Using Process Modeling: The Spatiotemporal Patterns and the Contributions to Atmospheric Methane Fluctuations

    NASA Astrophysics Data System (ADS)

    Zhu, Q.; Peng, C.; Liu, J.; Fang, X.; Jiang, H.

    2014-12-01

    Global wetland methane (CH4) emissions and its spatiotemporal patterns were evaluated using a new process-based model called TRIPLEX-GHG. The model was developed based on the Integrated Biosphere Simulator (IBIS), coupled with a new CH4 biogeochemistry module and a water table module to simulate CH4 emission processes in natural wetlands. The model has been validated using a number of field observations successfully. This study reported the initial results of global scale application, including total CH4 emissions, spatiotemporal patterns, and contributions to the atmospheric CH4 fluctuations. Global annual wetland CH4 emission ranged from 150 TgC yr-1 to 174 TgC yr-1 between 1901 and 2012 with the peak occurring in 1991 and 2012. Between 1990 and 2010, global CH4 emission decreased with a rate of approximately 0.38 TgC yr-1. It was largely due to the decrease of CH4 emissions from topical wetlands, which had a decreasing trend with a rate of 0.33 TgC yr-1 since the 1970s. CH4 emissions from tropical, temperate, and high latitude wetlands comprised 63%, 22% and 15% of global CH4 emission, respectively. Tropical wetlands are the primary contributor of the inter-annual variability of global wetland CH4 emissions as well as atmospheric CH4. The stable-to-decreasing wetland CH4 emissions owing to the balance of emissions between tropical and extratropical wetlands was a contributing factor to the slow-down atmospheric CH4 growth rate during 1990s. The rapid drop in tropical wetland CH4 emissions from 2000 onwards is supposed to offset the increases of the anthropogenic CH4 emissions, hence leading to a relatively stable level of atmospheric CH4 during 2000-2006. Increases of wetland CH4 emissions particularly after 2010 can be considered as an important contributor to the resumed growth of atmospheric CH4 since 2007 and for further increasing in the near future.

  14. A non-LTE model for the Jovian methane infrared emissions at high spectral resolution

    NASA Technical Reports Server (NTRS)

    Halthore, Rangasayi N.; Allen, J. E., Jr.; Decola, Philip L.

    1994-01-01

    High resolution spectra of Jupiter in the 3.3 micrometer region have so far failed to reveal either the continuum or the line emissions that can be unambiguously attributed to the nu(sub 3) band of methane (Drossart et al. 1993; Kim et al. 1991). Nu(sub 3) line intensities predicted with the help of two simple non-Local Thermodynamic Equilibrium (LTE) models -- a two-level model and a three-level model, using experimentally determined relaxation coefficients, are shown to be one to three orders of magnitude respectively below the 3-sigma noise level of these observations. Predicted nu(sub 4) emission intensities are consistent with observed values. If the methane mixing ratio below the homopause is assumed as 2 x 10(exp -3), a value of about 300 K is derived as an upper limit to the temperature of the high stratosphere at microbar levels.

  15. Model Estimates of Pan-Arctic Lake and Wetland Methane Emissions

    NASA Astrophysics Data System (ADS)

    Chen, X.; Bohn, T. J.; Glagolev, M.; Maksyutov, S.; Lettenmaier, D. P.

    2012-12-01

    Lakes and wetlands are important sources of the greenhouse gases CO2 and CH4, whose emission rates are sensitive to climate. The northern high latitudes, which are especially susceptible to climate change, contain about 50% of the world's lakes and wetlands. With the predicted changes in the regional climate for this area within the next century, there is concern about a possible positive feedback resulting from greenhouse gas emissions (especially of methane) from the region's wetlands and lakes. To study the climate response to emissions from northern hemisphere lakes and wetlands, we have coupled a large-scale hydrology and carbon cycling model (University of Washington's Variable Infiltration Capacity model; VIC) with the atmospheric chemistry and transport model (CTM) of Japan's National Institute for Environmental Studies and have applied this modelling framework over the Pan-Arctic region. In particular, the VIC model simulates the land surface hydrology and carbon cycling across a dynamic lake-wetland continuum. The model includes a distributed wetland water table that accounts for microtopography and simulates variations in inundated area that are calibrated to match a passive microwave based inundation product. Per-unit-area carbon uptake and methane emissions have been calibrated using extensive in situ observations. In this paper, the atmospheric methane concentrations from a coupled run of VIC and CTM are calibrated and verified for the Pan-Arctic region with satellite observations from Aqua's Atmospheric Infrared Sounder (AIRS) and Envisat's Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) instruments. We examine relative emissions from lakes and wetlands, as well as their net greenhouse warming potential, over the last half-century across the Pan-Arctic domain. We also assess relative uncertainties in emissions from each of the sources.

  16. Modelling methane emissions from natural wetlands: TRIPLEX-GHG model integration, sensitivity analysis, and calibration

    NASA Astrophysics Data System (ADS)

    Zhu, Q.; Liu, J.; Peng, C.; Chen, H.; Fang, X.; Jiang, H.; Yang, G.; Zhu, D.; Wang, W.; Zhou, X.

    2013-11-01

    This paper introduces TRIPLEX-GHG, a new process-based model framework used to quantify terrestrial ecosystem greenhouse gas dynamics by incorporating both ecological drivers and biogeochemical processes. TRIPLEX-GHG was developed from the Integrated Biosphere Simulator (IBIS), a dynamic global vegetation model, coupled with a new methane (CH4) biogeochemistry module (incorporating CH4 production, oxidation, and transportation processes) and a water table module to investigate CH4 emission processes that occur in natural wetlands. Sensitivity analysis indicates that the most sensitive parameters to use to evaluate CH4 emission processes from wetlands are r (defined as the CH4 to CO2 release ratio) and Q10 in CH4 production process. These two parameters were subsequently calibrated to data obtained from 19 sites collected from approximately 35 studies across different wetlands globally. Having a heterogeneous spatial distribution, r and Q10 parameters ranged from 0.1 to 0.55 with a mean value of 0.25 and from 1.6 to 4.5 with a mean value of 2.48, respectively. The model performed well when simulating magnitude and capturing temporal patterns in CH4 emissions from natural wetlands despite failing to capture CH4 emission pulses in certain cases. Results suggest the model can be applied to different wetlands under varying conditions and is also applicable for global scale simulations.

  17. Methane Emissions From Global Paddy Rice Agriculture - a New Estimate Based on DNDC Model Simulations

    NASA Astrophysics Data System (ADS)

    Hagen, S. C.; Li, C.; Salas, W.; Ingraham, P.; Li, J.; Beach, R.; Frolking, S.

    2012-12-01

    Roughly one-quarter of global methane emissions to the atmosphere come from the agricultural sector. Agricultural emissions are dominated by livestock (ruminants) and paddy-rice agriculture. We report on a new estimate of global methane emissions from paddy rice c.2010, based on DNDC model simulations of rice cropping around the world. We first generated a global map of rice cropping at 0.5°-resolution, based on existing global crop maps and various other published data. For each 0.5° grid cell that has rice agriculture, we simulated all rice cropping systems that our mapping indicated to be occurring there - irrigated and/or rainfed; single-rice, double-rice, triple-rice, and/or rice-rotated with other upland crops - under local climate and soil conditions, with assumptions about crop management (e.g., fertilizer type and amount, irrigation, flooding frequency and duration, manure application, tillage, crop residue management). We estimate global paddy rice emissions at 23 Tg CH4/yr from 120 Mha of rice paddies (land area) and 160 Mha of rice cropping (harvested area) for the baseline management scenario. We also report on the spatial distribution of these emissions, and the impacts of various management alternatives (flooding methods, fertilizer types, crop residue incorporation etc.) on yield, soil carbon sequestration and emissions of methane and nitrous oxide. For example, simulations with continuous flooding on all paddies increased simulated global paddy rice emissions to 33 Tg CH4/yr, while simulations where all fertilizer was applied as ammonium sulfate reduced simulated global paddy rice emissions to about 19 Tg CH4/yr. Simulated global paddy rice yield was about 320 Tg C in grain.

  18. How Can We Handle The Spatial Variability Within Peatlands in Lumped Parameter Models for Simulating Methane Emissions?

    NASA Astrophysics Data System (ADS)

    Roulet, N. T.; Lai, D.; Wilson, P.; Shatilla, N. J.; Braschi, L.; Malhotra, A.; Humphreys, E.; Moore, T. R.; Dalva, M.

    2011-12-01

    Northern peatlands are important natural sources of atmospheric methane and with a changing northern climate they could become more so. Baird et al (2009) discuss the issues of simulating methane emissions from northern peatlands caused by the scales of peatland topography and hydrology. Methane emissions can vary as much as 4 orders of magnitude over linear scales of <1 to ~1,000 m. These scales are too fine to be captured in contemporary ecosystem models. However, there are relationships among methane emissions, peatland topography and moisture, and vegetation communities (PFTs) that could be used to capture smaller scale variability. We are exploring these relationships across micro- to mesotopographic scales to see if there are transferable statistical descriptions that could be used to incorporate the spatial non-linearity of methane emissions in coarser scale ecosystem models. We have found statistical relationships among microtopography, water tables, and vegetation community structure that are associated with the variability in methane emissions. These relationships have been derived from very detailed spatial studies of the variability peatland properties and a multi-year continuous record of methane fluxes using autochambers at the Mer Bleue research peatland, a raised, shrub bog, in central Canada. Since these relationships are based on the emergent properties from the feedbacks among peatland form, water, and vegetation we suggest they provide a direction forward to incorporate the variability of methane emissions into models that lump parameters at scales far coarser than the actual processes that governing methane emissions. These relationships appear to be quite robust and potential transferable, but this needs to be tested across a much broader set of northern peatlands.

  19. Modelling methane emissions from natural wetlands by development and application of the TRIPLEX-GHG model

    NASA Astrophysics Data System (ADS)

    Zhu, Q.; Liu, J.; Peng, C.; Chen, H.; Fang, X.; Jiang, H.; Yang, G.; Zhu, D.; Wang, W.; Zhou, X.

    2014-05-01

    A new process-based model TRIPLEX-GHG was developed based on the Integrated Biosphere Simulator (IBIS), coupled with a new methane (CH4) biogeochemistry module (incorporating CH4 production, oxidation, and transportation processes) and a water table module to investigate CH4 emission processes and dynamics that occur in natural wetlands. Sensitivity analysis indicates that the most sensitive parameters to evaluate CH4 emission processes from wetlands are r (defined as the CH4 to CO2 release ratio) and Q10 in the CH4 production process. These two parameters were subsequently calibrated to data obtained from 19 sites collected from approximately 35 studies across different wetlands globally. Being heterogeneously spatially distributed, r ranged from 0.1 to 0.7 with a mean value of 0.23, and the Q10 for CH4 production ranged from 1.6 to 4.5 with a mean value of 2.48. The model performed well when simulating magnitude and capturing temporal patterns in CH4 emissions from natural wetlands. Results suggest that the model is able to be applied to different wetlands under varying conditions and is also applicable for global-scale simulations.

  20. Future methane emissions from animals

    SciTech Connect

    Anastasi, C.; Simpson, V.J. (Univ. of York, Heslington (United Kingdom))

    1993-04-20

    The authors project future methane emissions from animals to the year 2025. They review the present estimated sources of methane from enteric fermentation in animals. Ruminant animals produce the highest concentrations of methane. Methane is a byproduct of anaerobic breakdown of carbohydrates by microbes in the digestive tract of herbatious animals. In general the methane production depends on the variety of animal, the quality of the feed, and the feeding level. Since cattle, sheep, and buffalo account for roughly 91% of all animal methane emission, they only study these animals in detail. Results suggest a rise in methane production of roughly 1% per year averaged through 2025. Increasing levels are found to originate from developed countries even though the feedstock levels are lower.

  1. A Process-based, Climate-Sensitive Model to Derive Methane Emissions from Natural Wetlands: Application to 5 Wetland Sites, Sensitivity to Model Parameters and Climate

    NASA Technical Reports Server (NTRS)

    Walter, Bernadette P.; Heimann, Martin

    1999-01-01

    Methane emissions from natural wetlands constitutes the largest methane source at present and depends highly on the climate. In order to investigate the response of methane emissions from natural wetlands to climate variations, a 1-dimensional process-based climate-sensitive model to derive methane emissions from natural wetlands is developed. In the model the processes leading to methane emission are simulated within a 1-dimensional soil column and the three different transport mechanisms diffusion, plant-mediated transport and ebullition are modeled explicitly. The model forcing consists of daily values of soil temperature, water table and Net Primary Productivity, and at permafrost sites the thaw depth is included. The methane model is tested using observational data obtained at 5 wetland sites located in North America, Europe and Central America, representing a large variety of environmental conditions. It can be shown that in most cases seasonal variations in methane emissions can be explained by the combined effect of changes in soil temperature and the position of the water table. Our results also show that a process-based approach is needed, because there is no simple relationship between these controlling factors and methane emissions that applies to a variety of wetland sites. The sensitivity of the model to the choice of key model parameters is tested and further sensitivity tests are performed to demonstrate how methane emissions from wetlands respond to climate variations.

  2. Modeling ruminant methane emissions from the U.S. beef cattle industry 

    E-print Network

    Turk, Danny Carroll

    1993-01-01

    forage feedstuffs, otherwise useless to non-ruminants, into products that can be digested by ruminants. As a by-product of microbial fermentation, methanogenic bacteria produce methane in the ruminal/reticular area, which escapes into the atmosphere... methanogenic bacteria can convert acetate to methane and carbon dioxide (Baldwin, 1990), Methane emissions from the digestive processes of all animals (ruminants and non-ruminants) have been estimated between 65 and 100 Tg/yr (U. S. /Japan Working Group...

  3. Evaluating dispersion modeling options to estimate methane emissions from grazing beef cattle.

    PubMed

    McGinn, Sean M; Flesch, Thomas K; Coates, Trevor W; Charmley, Ed; Chen, Deli; Bai, Mei; Bishop-Hurley, Greg

    2015-01-01

    Enteric methane (CH) emission from cattle is a source of greenhouse gas and is an energy loss that contributes to production inefficiency for cattle. Direct measurements of enteric CH emissions are useful to quantify the magnitude and variation and to evaluate mitigation of this important greenhouse gas source. The objectives of this study were to evaluate the impact of stocking density of cattle and source configuration (i.e., point source vs. area source and elevation of area source) on CH emissions from grazing beef cattle in Queensland, Australia. This was accomplished using nonintrusive atmospheric measurements and a gas dispersion model. The average measured CH emission for the point and area source was between 240 and 250 g animal d over the entire study. There was no difference ( > 0.05) in emission when using an elevated area source (0.5 m) or a ground area source (0 m). For the point-source configuration, there was a difference in CH emission due to stocking density; likewise, some differences existed for the area-source emissions. This study demonstrates the flexibility of the area-source configuration of the dispersion model to estimate CH emissions even at a low stocking density. PMID:25602324

  4. Inverse Analysis of North American Methane Emissions Using the CarbonTracker-Lagrange Modeling Framework

    NASA Astrophysics Data System (ADS)

    Benmergui, J. S.; Andrews, A. E.; Thoning, K. W.; Trudeau, M.; Michalak, A. M.; Yadav, V.; Miller, S. M.; Dlugokencky, E. J.; Bruhwiler, L.; Masarie, K. A.; Worthy, D. E. J.; Sweeney, C.; Fischer, M. L.; Nehrkorn, T.; Mountain, M. E.; Wofsy, S. C.

    2014-12-01

    Several recent studies have attempted to quantify methane (CH4) emissions in North America, but large uncertainties remain in the magnitude, spatial and temporal distribution, and source sectors responsible. Estimates of biogenic emissions from wetlands, emissions related to animal husbandry, and the continental scale implications of recent shifts in the oil and gas industry are poorly constrained. We estimate North American CH4 emissions from biogenic and anthropogenic sources using the new CarbonTracker-Lagrange inverse modeling framework. A wide array of measurements taken between 2007 and 2012 provide top-down constraints. These include: in-situ and flask measurements made at surface sites, tall towers, and aboard aircraft; and remote sensing observations. Source region sensitivity is provided by the Stochastic Time-Inverted Lagrangian Transport (STILT) model, driven by meteorological fields from the Weather Research and Forecasting (WRF) model. CH4 emissions and background values are optimized simultaneously through Bayesian and geostatistical inversion. A restricted maximum likelihood estimation procedure is used to derive uncertainties in both emissions and the mole fraction field. The wide temporal coverage, dense network of measurements, and varied sources of data allow for an analysis of spatio-temporal trends in emissions that has not previously been accomplished with top-down constraints.

  5. Uncertainties in estimating regional methane emissions from rice paddies due to data scarcity in the modeling approach

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Zhang, Q.; Huang, Y.; Li, T. T.; Bian, J. Y.; Han, P. F.

    2014-06-01

    Rice paddies are a major anthropogenic source of the atmospheric methane. However, because of the high spatial heterogeneity, making accurate estimations of the methane emission from rice paddies is still a big challenge, even with complicated models. Data scarcity is one of the substantial causes of the uncertainties in estimating the methane emissions on regional scales. In the present study, we discussed how data scarcity affected the uncertainties in model estimations of rice paddy methane emissions, from county/provincial scale up to national scale. The uncertainties in methane emissions from the rice paddies of China was calculated with a local-scale model and the Monte Carlo simulation. The data scarcities in five of the most sensitive model variables, field irrigation, organic matter application, soil properties, rice variety and production were included in the analysis. The result showed that in each individual county, the within-cell standard deviation of methane flux, as calculated via Monte Carlo methods, was 13.5-89.3% of the statistical mean. After spatial aggregation, the national total methane emissions were estimated at 6.44-7.32 Tg, depending on the base scale of the modeling and the reliability of the input data. And with the given data availability, the overall aggregated standard deviation was 16.3% of the total emissions, ranging from 18.3-28.0% for early, late and middle rice ecosystems. The 95% confidence interval of the estimation was 4.5-8.7 Tg by assuming a gamma distribution. Improving the data availability of the model input variables is expected to reduce the uncertainties significantly, especially of those factors with high model sensitivities.

  6. Evaluation of methane emissions from Palermo municipal landfill: Comparison between field measurements and models

    SciTech Connect

    Di Bella, Gaetano, E-mail: dibella@idra.unipa.it [Dipartimento di Ingegneria Civile, Ambientale e Aerospaziale, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Di Trapani, Daniele, E-mail: ditrapani@idra.unipa.it [Dipartimento di Ingegneria Civile, Ambientale e Aerospaziale, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Viviani, Gaspare, E-mail: gviv@idra.unipa.it [Dipartimento di Ingegneria Civile, Ambientale e Aerospaziale, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy)

    2011-08-15

    Methane (CH{sub 4}) diffuse emissions from Municipal Solid Waste (MSW) landfills represent one of the most important anthropogenic sources of greenhouse gas. CH{sub 4} is produced by anaerobic biodegradation of organic matter in landfilled MSW and constitutes a major component of landfill gas (LFG). Gas recovery is a suitable method to effectively control CH{sub 4} emissions from landfill sites and the quantification of CH{sub 4} emissions represents a good tool to evaluate the effectiveness of a gas recovery system in reducing LFG emissions. In particular, LFG emissions can indirectly be evaluated from mass balance equations between LFG production, recovery and oxidation in the landfill, as well as by a direct approach based on LFG emission measurements from the landfill surface. However, up to now few direct measurements of landfill CH{sub 4} diffuse emissions have been reported in the technical literature. In the present study, both modeling and direct emission measuring methodologies have been applied to the case study of Bellolampo landfill located in Palermo, Italy. The main aim of the present study was to evaluate CH{sub 4} diffuse emissions, based on direct measurements carried out with the flux accumulation chamber (static, non-stationary) method, as well as to obtain the CH{sub 4} contoured flux map of the landfill. Such emissions were compared with the estimate achieved by means of CH{sub 4} mass balance equations. The results showed that the emissions obtained by applying the flux chamber method are in good agreement with the ones derived by the application of the mass balance equation, and that the evaluated contoured flux maps represent a reliable tool to locate areas with abnormal emissions in order to optimize the gas recovery system efficiency.

  7. WETCHIMP-WSL: Intercomparison of wetland methane emissions models over West Siberia

    NASA Astrophysics Data System (ADS)

    Melton, Joe; Bohn, Theodore

    2015-04-01

    Wetlands are the world's largest natural source of methane, a powerful greenhouse gas. The strong sensitivity of methane emissions to environmental factors such as soil temperature and moisture has led to concerns about potential positive feedbacks to climate change. This risk is particularly relevant at high latitudes, which have experienced pronounced warming and where thawing permafrost could potentially liberate large amounts of labile carbon over the next 100 years. However, global models disagree as to the magnitude and spatial distribution of emissions, due to uncertainties in wetland area and emissions per unit area and a scarcity of in situ observations. Recent intensive field campaigns across the West Siberian Lowland (WSL) make this an ideal region over which to assess the performance of large-scale process-based wetland models in a high-latitude environment. Here we present the results of a follow-up to the Wetland and Wetland CH4 Intercomparison of Models Project (WETCHIMP), focused on the West Siberian Lowland (WETCHIMP-WSL). We assessed 21 models and 5 inversions over this domain in terms of total CH4 emissions, simulated wetland areas, and CH4 fluxes per unit wetland area and compared these results to an intensive in situ CH4 flux dataset, several wetland maps, and two satellite inundation products. We found that: a) despite the large scatter of individual estimates, 12-year mean estimates of annual total emissions over the WSL from forward models (5.34 ±0.54 Tg CH4 y-1), inversions (6.06 ±1.22 Tg CH4 y-1), and in situ observations (3.91 ±1.29 Tg CH4 y-1) largely agreed; b) forward models using inundation products alone to estimate wetland areas suffered from severe biases in CH4 emissions; c) the interannual timeseries of models that lacked either soil thermal physics appropriate to the high latitudes or realistic emissions from unsaturated peatlands tended to be dominated by a single environmental driver (inundation or air temperature), unlike those of inversions and more sophisticated forward models; d) differences in biogeochemical schemes across models had relatively smaller influence over performance; and e) multi-year or multi-decade observational records are crucial for evaluating models' responses to long-term climate change.

  8. WETCHIMP-WSL: intercomparison of wetland methane emissions models over West Siberia

    NASA Astrophysics Data System (ADS)

    Bohn, T. J.; Melton, J. R.; Ito, A.; Kleinen, T.; Spahni, R.; Stocker, B. D.; Zhang, B.; Zhu, X.; Schroeder, R.; Glagolev, M. V.; Maksyutov, S.; Brovkin, V.; Chen, G.; Denisov, S. N.; Eliseev, A. V.; Gallego-Sala, A.; McDonald, K. C.; Rawlins, M. A.; Riley, W. J.; Subin, Z. M.; Tian, H.; Zhuang, Q.; Kaplan, J. O.

    2015-06-01

    Wetlands are the world's largest natural source of methane, a powerful greenhouse gas. The strong sensitivity of methane emissions to environmental factors such as soil temperature and moisture has led to concerns about potential positive feedbacks to climate change. This risk is particularly relevant at high latitudes, which have experienced pronounced warming and where thawing permafrost could potentially liberate large amounts of labile carbon over the next 100 years. However, global models disagree as to the magnitude and spatial distribution of emissions, due to uncertainties in wetland area and emissions per unit area and a scarcity of in situ observations. Recent intensive field campaigns across the West Siberian Lowland (WSL) make this an ideal region over which to assess the performance of large-scale process-based wetland models in a high-latitude environment. Here we present the results of a follow-up to the Wetland and Wetland CH4 Intercomparison of Models Project (WETCHIMP), focused on the West Siberian Lowland (WETCHIMP-WSL). We assessed 21 models and 5 inversions over this domain in terms of total CH4 emissions, simulated wetland areas, and CH4 fluxes per unit wetland area and compared these results to an intensive in situ CH4 flux data set, several wetland maps, and two satellite surface water products. We found that (a) despite the large scatter of individual estimates, 12-year mean estimates of annual total emissions over the WSL from forward models (5.34 ± 0.54 Tg CH4 yr-1), inversions (6.06 ± 1.22 Tg CH4 yr-1), and in situ observations (3.91 ± 1.29 Tg CH4 yr-1) largely agreed; (b) forward models using surface water products alone to estimate wetland areas suffered from severe biases in CH4 emissions; (c) the interannual time series of models that lacked either soil thermal physics appropriate to the high latitudes or realistic emissions from unsaturated peatlands tended to be dominated by a single environmental driver (inundation or air temperature), unlike those of inversions and more sophisticated forward models; (d) differences in biogeochemical schemes across models had relatively smaller influence over performance; and (e) multiyear or multidecade observational records are crucial for evaluating models' responses to long-term climate change.

  9. Methane Emissions from Cattle

    Microsoft Academic Search

    K. A. Johnson; D. E. Johnson

    2010-01-01

    Increasing atmospheric concentra- tions of methane have led scientists to examine its sources of origin. Ruminant livestock can produce 250 to 500 L of methane per day. This level of production results in estimates of the contribution by cattle to global warming that may occur in the next 50 to 100 yr to be a little less than 2%. Many

  10. Using the DayCent Ecosystem Model to Predict Methane Emissions from Wetland Rice Production in Support for Mitigation Efforts

    NASA Astrophysics Data System (ADS)

    Ogle, S. M.; Parton, W. J.; Cheng, K.; Pan, G.

    2014-12-01

    Wetland rice production is a major source of greenhouse gas (GHG) emissions to the atmosphere, and rice production is predicted to increase dramatically in the future due to expected growth in human populations. Mitigating GHG emissions from future rice production is possible with best management practices for water management, residue management and organic amendments. Policy initiatives and programs that promote practices to reduce GHG emissions from rice production will likely need robust methods for quantifying emission reductions. Frameworks based on process-based model provide one alternative for estimating emissions reductions. The advantages of this approach are that the models are relatively inexpensive to apply, incorporate a variety of management and environmental drivers influencing emissions, and can be used to predict future emissions for planning purposes. The disadvantages are that the models can be challenging to parameterize and evaluate, and require a relatively large amount of data. The DayCent ecosystem model simulates plant and soil processes, and is an example of a model that could be used to quantify emission reductions for reporting mitigation activities associated with rice production systems. DayCent estimates methane emissions, which is the major source of GHG emissions from wetland rice, but also estimates nitrous oxide emissions and soil organic C stock changes. DayCent has been evaluated using data from China, explaining 83% of the variation in methane emissions from 72 experimental rice fields. In addition, DayCent has been applied regionally in the United States to estimate methane, nitrous oxide emissions, and soil C stock changes, in compliance with the guidelines for reporting GHG emissions to the UN Framework Convention on Climate Change. Given the cost of alternatives, process-based models such as DayCent may offer the best way forward for estimating GHG emissions from rice production, and with quantification of uncertainty, could provide a robust framework for policy initiatives and programs in the future.

  11. Estimates of future warming-induced methane emissions from hydrate offshore west Svalbard for a range of climate models

    NASA Astrophysics Data System (ADS)

    Marín-Moreno, Héctor; Minshull, Timothy A.; Westbrook, Graham K.; Sinha, Bablu

    2015-05-01

    Methane hydrate close to the hydrate stability limit in seafloor sediment could represent an important source of methane to the oceans and atmosphere as the oceans warm. We investigate the extent to which patterns of past and future ocean-temperature fluctuations influence hydrate stability in a region offshore West Svalbard where active gas venting has been observed. We model the transient behavior of the gas hydrate stability zone at 400-500 m water depth (mwd) in response to past temperature changes inferred from historical measurements and proxy data and we model future changes predicted by seven climate models and two climate-forcing scenarios (Representative Concentration Pathways RCPs 2.6 and 8.5). We show that over the past 2000 year, a combination of annual and decadal temperature fluctuations could have triggered multiple hydrate-sourced methane emissions from seabed shallower than 400 mwd during episodes when the multidecadal average temperature was similar to that over the last century (˜2.6°C). These temperature fluctuations can explain current methane emissions at 400 mwd, but decades to centuries of ocean warming are required to generate emissions in water deeper than 420 m. In the venting area, future methane emissions are relatively insensitive to the choice of climate model and RCP scenario until 2050 year, but are more sensitive to the RCP scenario after 2050 year. By 2100 CE, we estimate an ocean uptake of 97-1050 TgC from marine Arctic hydrate-sourced methane emissions, which is 0.06-0.67% of the ocean uptake from anthropogenic CO2 emissions for the period 1750-2011.

  12. Modeling the effects of vegetation on methane oxidation and emissions through soil landfill final covers across different climates.

    PubMed

    Abichou, Tarek; Kormi, Tarek; Yuan, Lei; Johnson, Terry; Francisco, Escobar

    2015-02-01

    Plant roots are reported to enhance the aeration of soil by creating secondary macropores which improve the diffusion of oxygen into soil as well as the supply of methane to bacteria. Therefore, methane oxidation can be improved considerably by the soil structuring processes of vegetation, along with the increase of organic biomass in the soil associated with plant roots. This study consisted of using a numerical model that combines flow of water and heat with gas transport and oxidation in soils, to simulate methane emission and oxidation through simulated vegetated and non-vegetated landfill covers under different climatic conditions. Different simulations were performed using different methane loading flux (5-200 g m(-2) d(-1)) as the bottom boundary. The lowest modeled surface emissions were always obtained with vegetated soil covers for all simulated climates. The largest differences in simulated surface emissions between the vegetated and non-vegetated scenarios occur during the growing season. Higher average yearly percent oxidation was obtained in simulations with vegetated soil covers as compared to non-vegetated scenario. The modeled effects of vegetation on methane surface emissions and percent oxidation were attributed to two separate mechanisms: (1) increase in methane oxidation associated with the change of the physical properties of the upper vegetative layer and (2) increase in organic matter associated with vegetated soil layers. Finally, correlations between percent oxidation and methane loading into simulated vegetated and non-vegetated covers were proposed to allow decision makers to compare vegetated versus non-vegetated soil landfill covers. These results were obtained using a modeling study with several simplifying assumptions that do not capture the complexities of vegetated soils under field conditions. PMID:25475118

  13. METHANE EMISSIONS FROM INDUSTRIAL SOURCES

    EPA Science Inventory

    The chapter identifies and describes major industrial sources of methane (CH4) emissions. or each source type examined, it identifies CH4 release points and discusses in detail the factors affecting emissions. t also summarizes and discusses available global and country-specific ...

  14. Role of water flow in modeling methane emissions from flooded paddy soils

    NASA Astrophysics Data System (ADS)

    Rizzo, A.; Boano, F.; Revelli, R.; Ridolfi, L.

    2013-02-01

    Methane (CH4) is a potent greenhouse gas that is emitted from paddy fields, and the large CH4 fluxes represent a worldwide issue for the rice production eco-compatibility. In this work a model is proposed to investigate the role of water flows on CH4 emissions from flooded paddy soils. The model is based on a system of partial differential mass balance equations of the chemical species affecting CH4 fate, and water flows are modeled by the Darcy equation. Moreover, in order to properly model the dynamics of CH4, a number of physico-chemical processes and features not included in currently available CH4 emission models are considered: paddy soil stratigraphy; nutrient adsorption and root water uptake; gas transport and respiration within root aerenchyma compartment. The proposed model allows to simulate the spatio-temporal dynamics of chemical compounds within paddy soil as well as to quantify the influence of different processes on nutrient input/output budgets. Simulations without water flow have shown a considerable overestimation of CH4 emissions due to a different spatio-temporal dynamics of dissolved organic matter (DOC - source of energy for CH4 production). In particular, when water fluxes have not been modeled the overestimation can reach 54%, 41% and 67% of daily minimum, daily maximum, and total over the whole growing season CH4 emission, respectively. Moreover, the model results suggest that roots influence CH4 dynamics principally due to their nutrient uptake, while root effect on advective flow plays a minor role. Finally, the analysis of CH4 transport fluxes has shown the limiting effect of upward dispersive transport fluxes on the downward CH4 percolation.

  15. Estimation of Swiss methane emissions by near surface observations and inverse modeling

    NASA Astrophysics Data System (ADS)

    Henne, Stephan; Brian, Oney; Leuenberger, Markus; Bamberger, Ines; Eugster, Werner; Steinbacher, Martin; Meinhardt, Frank; Brunner, Dominik

    2015-04-01

    On a global scale methane (CH4) is the second most important long-lived greenhouse gas. It is released from both natural and anthropogenic processes and its atmospheric burden has more than doubled since preindustrial times. Current CH4 emission estimates are associated with comparatively large uncertainties both globally and regionally. For example, the Swiss national greenhouse gas inventory assigns an uncertainty of 18% to the country total anthropogenic CH4 emissions as compared to only 3% for anthropogenic CO2 emissions. In Switzerland, CH4 is thought to be mainly released by agricultural activities (ruminants and manure management >80%), while natural emissions from wetlands and wild animals represent a minor source (~3 %). The country total and especially the spatial distribution of CH4 emission within Switzerland strongly differs between the national and different European scale inventories. To validate the 'bottom-up' Swiss CH4 emission estimate and to reduce its uncertainty both in total and spatially, 'top-down' methods combining atmospheric CH4 observations and regional scale transport simulations can be used. Here, we analyse continuous, near surface observations of CH4 concentrations as collected within the newly established CarboCountCH measurement network (http://www.carbocount.ch). The network consists of 4 sites situated on the Swiss Plateau, comprising a tall tower site (217 m), two elevated (mountaintop) sites and a small tower site (32 m) in flat terrain. In addition, continuous CH4 observations from the nearby high-altitude site Jungfraujoch (Alps) and the mountaintop site Schauinsland (Germany) were used. Two inversion frameworks were applied to the CH4 observations in combination with source sensitivities (footprints) calculated with the regional scale version of the Lagrangian Particle Dispersion Model FLEXPART. One inversion system was based on a Bayesian framework, while the other utilized an extended Kalman filter approach. The transport model was driven by analysis fields from the non-hydrostatic numerical weather predication model COSMO at horizontal resolutions of up to 7 km x 7 km. As a result spatially resolved, annual mean CH4 fluxes for Switzerland were obtained. In general total Swiss CH4 emission remained close to the 'bottom-up' estimates, while considerable shifts in the regional distribution of the emissions were obtained. Reductions in CH4 emissions, as compared to the prior estimates, were established in regions with large emissions from ruminants, while increases resulted in the Western part of the Swiss Plateau, which is dominated by mixture of large water bodies and crop and vegetable farming. Sensitivity inversions were applied to assess the overall robustness and the uncertainty of the inversion system.

  16. Assessment of emissions prediction capability of RANS based PDF models for lean premixed combustion of methane

    SciTech Connect

    Parsons, D.R.; Nanduri, J.R.; Celik, Ismail; Strakey, P.A.

    2008-01-01

    The high computational cost of Large Eddy Simulation (LES) makes Reynolds Averaged Navier-Stokes (RANS) methods the current standard for turbulent combustion modeling. Empirical models for turbulence, turbulence-combustion interaction and chemical kinetics are, however, a major source of uncertainty in RANS based combustion simulation. While Probability Density Function (PDF) based models overcome some of these issues, most commercial codes do not take full advantage of these models. In this study, lean premixed combustion of methane in a bluff-body combustor is simulated using two different reduced chemical mechanisms (ARM9 and ARM19) combined with the composition PDF transport combustion model in the commercial code FLUENT. Two different turbulence models, namely the RNG k-? model and the Reynolds Stress Model (RSM) are used and the results of the simulations are compared to experimental data. For all the models tested, the prediction of temperature and major species (CH4, O2, CO2, CO, H2, and H2O) was good when compared to experiments. While all of the model predictions for the intermediate species OH showed an order magnitude difference (compared to the experiments) close to the bluff body surface; downstream axial locations showed good quantitative and qualitative agreement with the experiments. In a trend similar to the previous study (Nanduri et al., 2007) using the Eddy Dissipation Concept (EDC) model, predicted values for NO emission radial profiles showed an average difference of ±5 ppm when compared to experimental values. The results were also compared to the results of a velocity-composition joint PDF model developed by researchers at the University of Pittsburgh. In terms of emissions (NO and CO) predictions the relatively expensive composition PDF model in FLUENT did not give significant improvement when compared to the computationally cheaper EDC models. However, the velocity-composition joint PFD model used by researchers at the University of Pittsburgh did show significant improvement over EDC models in the prediction of NO. Both of the PDF models resulted in better qualitative and quantitative agreement in H2 prediction, thus showing the promise of PDF based models in simulating lean premixed combustion of fuel blends like hydrogen enriched natural gas.

  17. Simulations of atmospheric methane for Cape Grim, Tasmania, to constrain South East Australian methane emissions

    NASA Astrophysics Data System (ADS)

    Loh, Z. M.; Law, R. M.; Haynes, K. D.; Krummel, P. B.; Steele, L. P.; Fraser, P. J.; Chambers, S.; Williams, A.

    2014-08-01

    This study uses two climate models and six scenarios of prescribed methane emissions to compare modelled and observed atmospheric methane between 1994 and 2007, for Cape Grim, Australia (40.7° S, 144.7° E). The model simulations follow the TransCom-CH4 protocol and use the Australian Community Climate and Earth System Simulator (ACCESS) and the CSIRO Conformal-Cubic Atmospheric Model (CCAM). Radon is also simulated and used to reduce the impact of transport differences between the models and observations. Comparisons are made for air samples that have traversed the Australian continent. All six emission scenarios give modelled concentrations that are broadly consistent with those observed. There are three notable mismatches, however. Firstly, scenarios that incorporate interannually varying biomass burning emissions produce anomalously high methane concentrations at Cape Grim at times of large fire events in southeastern Australia, most likely due to the fire methane emissions being unrealistically input into the lowest model level. Secondly, scenarios with wetland methane emissions in the austral winter overestimate methane concentrations at Cape Grim during wintertime while scenarios without winter wetland emissions perform better. Finally, all scenarios fail to represent a methane source in austral spring implied by the observations. It is possible that the timing of wetland emissions in the scenarios is incorrect with recent satellite measurements suggesting an austral spring (September-October-November), rather than winter, maximum for wetland emissions.

  18. Simulations of atmospheric methane for Cape Grim, Tasmania, to constrain southeastern Australian methane emissions

    NASA Astrophysics Data System (ADS)

    Loh, Z. M.; Law, R. M.; Haynes, K. D.; Krummel, P. B.; Steele, L. P.; Fraser, P. J.; Chambers, S. D.; Williams, A. G.

    2015-01-01

    This study uses two climate models and six scenarios of prescribed methane emissions to compare modelled and observed atmospheric methane between 1994 and 2007, for Cape Grim, Australia (40.7° S, 144.7° E). The model simulations follow the TransCom-CH4 protocol and use the Australian Community Climate and Earth System Simulator (ACCESS) and the CSIRO Conformal-Cubic Atmospheric Model (CCAM). Radon is also simulated and used to reduce the impact of transport differences between the models and observations. Comparisons are made for air samples that have traversed the Australian continent. All six emission scenarios give modelled concentrations that are broadly consistent with those observed. There are three notable mismatches, however. Firstly, scenarios that incorporate interannually varying biomass burning emissions produce anomalously high methane concentrations at Cape Grim at times of large fire events in southeastern Australia, most likely due to the fire methane emissions being unrealistically input into the lowest model level. Secondly, scenarios with wetland methane emissions in the austral winter overestimate methane concentrations at Cape Grim during wintertime while scenarios without winter wetland emissions perform better. Finally, all scenarios fail to represent a~methane source in austral spring implied by the observations. It is possible that the timing of wetland emissions in the scenarios is incorrect with recent satellite measurements suggesting an austral spring (September-October-November), rather than winter, maximum for wetland emissions.

  19. Improving a plot-scale methane emission model and its performance at a Northeastern Siberian tundra site

    NASA Astrophysics Data System (ADS)

    Mi, Y.; van Huissteden, J.; Parmentier, F. J. W.; Gallagher, A.; Budishchev, A.; Berridge, C. T.; Dolman, A. J.

    2013-12-01

    In order to better address the feedbacks between climate and wetland methane (CH4) emissions, we tested several mechanistic improvements to the wetland CH4 emission model Peatland-VU with a longer Arctic dataset than any other model: (1) inclusion of an improved hydrological module; (2) incorporation of a gross primary productivity (GPP) module; (3) a more realistic soil-freezing scheme. A long time series of field measurements (2003-2010) from a tundra site in Northeastern Siberia is used to validate the model, and the Generalized Likelihood Uncertainty Estimation (GLUE) methodology is used to test the sensitivity of model parameters. Peatland-VU is able to capture both the annual magnitude and seasonal variations of the CH4 flux, water table position and soil thermal properties. However, detailed daily variations are difficult to evaluate due to data limitation. Improvements due to the inclusion of a GPP module are less than anticipated, although this component is likely to become more important at larger spatial scales because the module can accommodate the variations in vegetation traits better than at plot-scale. Sensitivity experiments suggest that the methane production rate factor, the methane plant oxidation parameter, the reference temperature for temperature dependent decomposition, and the methane plant transport rate factor are the most important parameters affecting the data fit, regardless of vegetation type. Both wet and dry vegetation cover are sensitive to the minimum water table level, in addition to the runoff threshold and open water correction factor and the subsurface water evaporation and evapotranspiration correction factors, respectively. These results shed light on model parameterization and future improvement of CH4 modelling. However, high spatial variability of CH4 emissions within similar vegetation/soil units and data quality prove to impose severe limits on model testing and improvement.

  20. Anthropogenic emissions of methane in the United States

    PubMed Central

    Miller, Scot M.; Wofsy, Steven C.; Michalak, Anna M.; Kort, Eric A.; Andrews, Arlyn E.; Biraud, Sebastien C.; Dlugokencky, Edward J.; Eluszkiewicz, Janusz; Fischer, Marc L.; Janssens-Maenhout, Greet; Miller, Ben R.; Miller, John B.; Montzka, Stephen A.; Nehrkorn, Thomas; Sweeney, Colm

    2013-01-01

    This study quantitatively estimates the spatial distribution of anthropogenic methane sources in the United States by combining comprehensive atmospheric methane observations, extensive spatial datasets, and a high-resolution atmospheric transport model. Results show that current inventories from the US Environmental Protection Agency (EPA) and the Emissions Database for Global Atmospheric Research underestimate methane emissions nationally by a factor of ?1.5 and ?1.7, respectively. Our study indicates that emissions due to ruminants and manure are up to twice the magnitude of existing inventories. In addition, the discrepancy in methane source estimates is particularly pronounced in the south-central United States, where we find total emissions are ?2.7 times greater than in most inventories and account for 24 ± 3% of national emissions. The spatial patterns of our emission fluxes and observed methane–propane correlations indicate that fossil fuel extraction and refining are major contributors (45 ± 13%) in the south-central United States. This result suggests that regional methane emissions due to fossil fuel extraction and processing could be 4.9 ± 2.6 times larger than in EDGAR, the most comprehensive global methane inventory. These results cast doubt on the US EPA’s recent decision to downscale its estimate of national natural gas emissions by 25–30%. Overall, we conclude that methane emissions associated with both the animal husbandry and fossil fuel industries have larger greenhouse gas impacts than indicated by existing inventories. PMID:24277804

  1. Using a Crop\\/Soil Simulation Model and GIS Techniques to Assess Methane Emissions from Rice Fields in Asia. IV. Upscaling to National Levels

    Microsoft Academic Search

    R. B. Matthews; R. Wassmann; J. W. Knox; L. V. Buendia

    2000-01-01

    The process-based crop\\/soil model MERES (Methane Emissions from Rice EcoSystems) was used together with daily weather data, spatial soil data, and rice-growing statistics to estimate the annual methane (CH4) emissions from China, India, Indonesia, Philippines, and Thailand under various crop management scenarios. Four crop management scenarios were considered: (a) a 'baseline' scenario assuming no addition of organic amendments or field

  2. Effects of permafrost thaw on northern wetland methane emissions

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  3. Methane emissions (kt of CO2 equivalent)

    NSDL National Science Digital Library

    World Bank

    List of countries with their annual methane emissions. The data are from 2005. The data are given in total annual emissions, thus must be compared with economic activity, geographic and most importantly, population data to be relevant.

  4. Ebullitive methane emissions from oxygenated wetland streams.

    PubMed

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

    2014-11-01

    Stream and river carbon dioxide emissions are an important component of the global carbon cycle. Methane emissions from streams could also contribute to regional or global greenhouse gas cycling, but there are relatively few data regarding stream and river methane emissions. Furthermore, the available data do not typically include the ebullitive (bubble-mediated) pathway, instead focusing on emission of dissolved methane by diffusion or convection. Here, we show the importance of ebullitive methane emissions from small streams in the regional greenhouse gas balance of a lake and wetland-dominated landscape in temperate North America and identify the origin of the methane emitted from these well-oxygenated streams. Stream methane flux densities from this landscape tended to exceed those of nearby wetland diffusive fluxes as well as average global wetland ebullitive fluxes. Total stream ebullitive methane flux at the regional scale (103 Mg C yr(-1) ; over 6400 km(2) ) was of the same magnitude as diffusive methane flux previously documented at the same scale. Organic-rich stream sediments had the highest rates of bubble release and higher enrichment of methane in bubbles, but glacial sand sediments also exhibited high bubble emissions relative to other studied environments. Our results from a database of groundwater chemistry support the hypothesis that methane in bubbles is produced in anoxic near-stream sediment porewaters, and not in deeper, oxygenated groundwaters. Methane interacts with other key elemental cycles such as nitrogen, oxygen, and sulfur, which has implications for ecosystem changes such as drought and increased nutrient loading. Our results support the contention that streams, particularly those draining wetland landscapes of the northern hemisphere, are an important component of the global methane cycle. PMID:24756991

  5. Capturing fugitive methane emissions from natural gas compressor buildings.

    PubMed

    Litto, R; Hayes, R E; Liu, B

    2007-08-01

    Fugitive methane emissions account for about 50% of the greenhouse gas (GHG) emissions from the Canadian conventional oil and gas sector. Sources include leaks in natural gas transmission facilities such as pipelines and compressor stations. There are three sources of methane emissions in a compressor station. The first is emissions resulting from incomplete combustion in the engine; the second is leaks in valves, flanges and other equipment in the building; and the third results from instrument venting. Fugitive methane emissions may be in low concentration relative to air, and thus cannot be destroyed by conventional combustion (below flammability limits of about 5-16%). The present study investigates the feasibility of capturing methane emissions from a compressor station. Computer modelling of the flow patterns of lean methane emissions inside the building is used to show the influence of doors, vents and leak location. Simulations show that for a typical building most fugitive methane exits through the ridge vent provided that the main doors remain closed. When the extraction rate through the ridge vent is controlled, the methane concentration is at acceptable levels for destruction in a catalytic flow reverse reactor, that is, in the range of 0.1-1% by volume. PMID:16891053

  6. The role of endophytic methane-oxidizing bacteria in submerged Sphagnum in determining methane emissions of Northeastern Siberian tundra

    NASA Astrophysics Data System (ADS)

    Parmentier, F. J. W.; van Huissteden, J.; Kip, N.; den Camp, H. J. M. Op; Jetten, M. S. M.; Maximov, T. C.; Dolman, A. J.

    2011-05-01

    The role of the microbial processes governing methane emissions from tundra ecosystems is receiving increasing attention. Recently, cooperation between methanotrophic bacteria and submerged Sphagnum was shown to reduce methane emissions but also to supply CO2 for photosynthesis for the plant. Although this process was shown to be important in the laboratory, the differences that exist in methane emissions from inundated vegetation types with or without Sphagnum in the field have not been linked to these bacteria before. In this study, chamber flux measurements, an incubation study and a process model were used to investigate the drivers and controls on the relative difference in methane emissions between a submerged Sphagnum/sedge vegetation type and an inundated sedge vegetation type without Sphagnum. It was found that methane emissions in the Sphagnum-dominated vegetation type were 50 % lower than in the vegetation type without Sphagnum. A model sensitivity analysis showed that these differences could not sufficiently be explained by differences in methane production and plant transport. The model, combined with an incubation study, indicated that methane oxidation by endophytic bacteria, living in cooperation with submerged Sphagnum, plays a significant role in methane cycling at this site. This result is important for spatial upscaling as oxidation by these bacteria is likely involved in 15 % of the net methane emissions at this tundra site. Our findings support the notion that methane-oxidizing bacteria are an important factor in understanding the processes behind methane emissions in tundra.

  7. Estimation method for national methane emission from solid waste landfills

    NASA Astrophysics Data System (ADS)

    Kumar, Sunil; Gaikwad, S. A.; Shekdar, A. V.; Kshirsagar, P. S.; Singh, R. N.

    In keeping with the global efforts on inventorisation of methane emission, municipal solid waste (MSW) landfills are recognised as one of the major sources of anthropogenic emissions generated from human activities. In India, most of the solid wastes are disposed of by landfilling in low-lying areas located in and around the urban centres resulting in generation of large quantities of biogas containing a sizeable proportion of methane. After a critical review of literature on the methodology for estimation of methane emissions, the default methodology has been used in estimation following the IPCC guidelines 1996. However, as the default methodology assumes that all potential methane is emitted in the year of waste deposition, a triangular model for biogas from landfill has been proposed and the results are compared. The methodology proposed for methane emissions from landfills based on a triangular model is more realistic and can very well be used in estimation on global basis. Methane emissions from MSW landfills for the year AD 1980-1999 have been estimated which could be used in computing national inventories of methane emission.

  8. APPROACH FOR ESTIMATING GLOBAL LANDFILL METHANE EMISSIONS

    EPA Science Inventory

    The report is an overview of available country-specific data and modeling approaches for estimating global landfill methane. Current estimates of global landfill methane indicate that landfills account for between 4 and 15% of the global methane budget. The report describes an ap...

  9. Methane emissions from natural wetlands

    SciTech Connect

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

    1993-09-01

    Analyses of air trapped in polar ice cores in conjunction with recent atmospheric measurements, indicate that the atmospheric methane concentration increased by about 250% during the past two or three hundred years (Rasmussen and Khalil, 1984). Because methane is a potent ``greenhouse`` gas, the increasing concentrations are expected to contribute to global warning (Dickinson and Cicerone, 1986). The timing of the methane increase suggests that it is related to the rapid growth of the human population and associated industrialization and agricultural development. The specific causes of the atmospheric methane concentration increase are not well known, but may relate to either increases in methane sources, decreases in the strengths of the sinks, or both.

  10. Methane oxidation associated with submerged brown mosses reduces methane emissions from Siberian

    E-print Network

    Wehrli, Bernhard

    Methane oxidation associated with submerged brown mosses reduces methane emissions from Siberian (methanotrophy) associated with submerged brown moss species occurs in polygonal tundra environments. Moss-associated methane oxidation is not only promoted by submerged conditions but also by light

  11. Global methane emissions from pit latrines.

    PubMed

    Reid, Matthew C; Guan, Kaiyu; Wagner, Fabian; Mauzerall, Denise L

    2014-08-01

    Pit latrines are an important form of decentralized wastewater management, providing hygienic and low-cost sanitation for approximately one-quarter of the global population. Latrines are also major sources of the greenhouse gas methane (CH4) from the anaerobic decomposition of organic matter in pits. In this study, we develop a spatially explicit approach to account for local hydrological control over the anaerobic condition of latrines and use this analysis to derive a set of country-specific emissions factors and to estimate global pit latrine CH4 emissions. Between 2000 and 2015 we project global emissions to fall from 5.2 to 3.8 Tg y(-1), or from ? 2% to ? 1% of global anthropogenic CH4 emissions, due largely to urbanization in China. Two and a half billion people still lack improved sanitation services, however, and progress toward universal access to improved sanitation will likely drive future growth in pit latrine emissions. We discuss modeling results in the context of sustainable water, sanitation, and hygiene development and consider appropriate technologies to ensure hygienic sanitation while limiting CH4 emissions. We show that low-CH4 on-site alternatives like composting toilets may be price competitive with other CH4 mitigation measures in organic waste sectors, with marginal abatement costs ranging from 57 to 944 $/ton carbon dioxide equivalents (CO2e) in Africa and 46 to 97 $/ton CO2e in Asia. PMID:24999745

  12. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY

    EPA Science Inventory

    The paper discusses a project to quantify methane (CH4) emissions from the U.S. natural gas industry. his study will measure or calculate all gas industry CH4 emissions--from production at the wellhead, through the system, to the customer's meter. missions downstream of the consu...

  13. A quasi-dimensional combustion model for performance and emissions of SI engines running on hydrogen–methane blends

    Microsoft Academic Search

    Federico Perini; Fabrizio Paltrinieri; Enrico Mattarelli

    2010-01-01

    The development of a predictive two-zone, quasi-dimensional model for the simulation of the combustion process in spark ignited engines fueled with hydrogen, methane, or hydrogen–methane blends is presented. The code is based on a general-purpose thermodynamic framework for the simulation of the power cycle of internal combustion engines. Quasi-dimensional modelling describes the flame front development assuming a simplified spherical geometry,

  14. Methane emission by adult ostriches (Struthio camelus).

    PubMed

    Frei, Samuel; Dittmann, Marie T; Reutlinger, Christoph; Ortmann, Sylvia; Hatt, Jean-Michel; Kreuzer, Michael; Clauss, Marcus

    2015-02-01

    Ostriches (Struthio camelus) are herbivorous birds with a digestive physiology that shares several similarities with that of herbivorous mammals. Previous reports, however, claimed a very low methane emission from ostriches, which would be clearly different from mammals. If this could be confirmed, ostrich meat would represent a very attractive alternative to ruminant-and generally mammalian-meat by representing a particularly low-emission agricultural form of production. We individually measured, by chamber respirometry, the amount of oxygen consumed as well as carbon dioxide and methane emitted from six adult ostriches (body mass 108.3±8.3 kg) during a 24-hour period when fed a pelleted lucerne diet. While oxygen consumption was in the range of values previously reported for ostriches, supporting the validity of our experimental setup, methane production was, at 17.5±3.2 L d(-1), much higher than previously reported for this species, and was of the magnitude expected for similar-sized, nonruminant mammalian herbivores. These results suggest that methane emission is similar between ostriches and nonruminant mammalian herbivores and that the environmental burden of these animals is comparable. The findings furthermore indicate that it appears justified to use currently available scaling equations for methane production of nonruminant mammals in paleo-reconstructions of methane production of herbivorous dinosaurs. PMID:25446146

  15. Measurements of Methane Emissions at Natural Gas Production Sites

    E-print Network

    Lightsey, Glenn

    Measurements of Methane Emissions at Natural Gas Production Sites in the United States #12;Why = 21 #12;Need for Study · Estimates of methane emissions from natural gas production , from academic in assumptions in estimating emissions · Measured data for some sources of methane emissions during natural gas

  16. Upscaling methane emissions from rice paddies: Problems and possibilities

    NASA Astrophysics Data System (ADS)

    van Bodegom, P. M.; Verburg, Peter H.; Denier van der Gon, Hugo A. C.

    2002-03-01

    Global methane emission estimates depend highly on the models, techniques, and databases used. Since emissions cannot be measured directly at large scales, it is impossible to judge which estimate is more realistic. In this paper, different aspects of uncertainty in upscaling methane emissions from rice paddies are discussed. These aspects are visualized by a case study on the spatial upscaling of methane emissions from the island of Java, Indonesia. The first aspect concerns process information. An approach to incorporate this information in a simplified but process-based way in predictive models is discussed. Sources of uncertainty include the methane emissions measurements, processes quantification, process simplification, and the use of data transfer functions. Data availability of input parameters, the second aspect, is uncertain because of differences between different data sources, the use of data sources for purposes not originally planned for, and the scale at which data are available. Data interpolation in combination with nonlinear model responses introduces scaling errors, the third aspect. Data accuracy introduced the highest uncertainties in emission estimates but is rarely accounted for in the estimation of global emissions.

  17. Modelling the impacts of climate change and methane emission reductions on rice production: a review

    Microsoft Academic Search

    Robin Matthews; Reiner Wassmann

    2003-01-01

    Rice agriculture is not only affected by climate change, but also contributes to global warming through the release of methane into the atmosphere. In 1989, a major research project was initiated at the International Rice Research Institute in the Philippines to investigate relationships between climate change and rice production. A second project started in 1993 to investigate, in more detail,

  18. Methane emission from rice paddies

    Microsoft Academic Search

    W. Seiler; A. Holzapfel-Pschorn; R. Conrad; D. Scharffe

    1983-01-01

    Methane release rates from rice paddies have been measured in Andalusia, Spain, during almost a complete vegetation period in 1982 using the static box system. The release rates ranged between 2 and 14 mg\\/m2\\/h and exhibited a strong seasonal variation with low values during the tillering stage and shortly before harvest, while maximum values were observed at the end of

  19. MEASUREMENT OF METHANE EMISSIONS FROM UNDERGROUND DISTRIBUTION MAINS AND SERVICES

    EPA Science Inventory

    The paper reports results of measurements of methane emissions from underground distribution mains and services. he losses from the underground distribution network were estimated to be a significant source of methane emissions from the natural gas industry. ata acquired through ...

  20. Modelling global methane emissions from livestock: Biological and nutritional controls. Final Report, 1 July 1989-30 June 1992

    SciTech Connect

    Johnson, D.E.

    1992-10-01

    The available observations of methane production from the literature have been compiled into a ruminant methane data base. This data base includes 400 treatment mean observations of methane losses from cattle and sheep, and minor numbers of measurements from other species. Methane loss varied from 2.0 to 11.6 percent of dietary gross energy. Measurements included describe the many different weights and physiological states of the animals fed and diets ranging from all forage to all concentrate diets or mixtures. An auxiliary spreadsheet lists approximately 1000 individual animal observations. Many important concepts have emerged from our query and analysis of this data set. The majority of the world's cattle, sheep, and goats under normal husbandry circumstances likely produce methane very close to 6 percent of their daily diets gross energy (2 percent of the diet by weight). Although individual animals or losses from specific dietary research circumstances can vary considerably, the average for the vast majority of groups of ruminant livestock are likely to fall between 5.5 to 6.5 percent. We must caution, however, that little experimental data is available for two-thirds of the world's ruminants in developing countries. Available evidence suggests similar percentage of emissions, but this supposition needs confirmation. More importantly, data is skimpy or unavailable to describe diet consumption, animal weight, and class distribution.

  1. Methane emissions from municipal wastewater treatment processes

    SciTech Connect

    Czepiel, P.M.; Crill, P.M.; Harriss, R.C. (Univ. of New Hampshire, Durham, NH (United States))

    1993-11-01

    Methane and carbon dioxide emissions from primary and secondary wastewater treatment processes were measured from mid-winter to summer conditions in Durham, NH. A statistically significant positive relationship between gas flux and wastewater temperature was determined for methane and carbon dioxide in both the aerated and nonaerated areas of the grit tanks. Statistical correlations to temperature measured in a secondary aeration tank were marginal for methane and insignificant for carbon dioxide. Emission factors derived from our measurements were 39 g of CH[sub 4] person[sup [minus]1] year[sup [minus]1] and 35 698 g of CO[sub 2] person[sup [minus]1] year[sup [minus]1] for primary and secondary activated sludge treatment processes. 14 refs., 4 figs., 2 tabs.

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

    Microsoft Academic Search

    Frans-Faco W. A. Van Der Nat; Daniëlle Van Meteren; Annette Wielemakers

    1998-01-01

    In mature Phragmites australis and Scirpus lacustris vegetated sediment methane was emitted almost exclusively by plant-mediated transport, whereas in unvegetated, but otherwise identical sediment, methane was emitted almost exclusively by ebullition. Diel variations in methane emission, with highest emission rates at daytime and emission peaks following sunrise, were demonstrated for Phragmites and Scirpus. The diel difference and magnitude of the

  3. METHANE EMISSIONS FROM ABANDONED UNDERGROUND COAL MINES

    EPA Science Inventory

    The paper summarizes current research on abandoned underground coal mines. t forms an initial basis for developing an inventory of methane emissions from such mines. arly measurements have shown that some abandoned coal mines can liberate large volumes of high quality gas (up to ...

  4. Simulating Methane Emissions from Dairy Farms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As a sector, agriculture is reported to be the third greatest contributor of methane (CH4) in the U.S., emitting one-quarter of total emissions. The primary sources of CH4 on a dairy farm are the animals and manure storage, with smaller contributions from field-applied manure, feces deposited by gra...

  5. Methane emission from Yangtze estuarine wetland, China

    Microsoft Academic Search

    Dongqi Wang; Zhenlou Chen; Shiyuan Xu

    2009-01-01

    Yangtze estuary, lying in the subtropical monsoon region of China, is characterized by a unique environmental setting and endemic wetland plant species (Scirpus mariqueter). Methane (CH4) emission fluxes were measured at the Yangtze estuarine wetland, Chongming Dongtan (CD), by a static closed chamber technique from May 2004 to April 2005. The results showed that CD is the source of atmospheric

  6. Methane emission from Western Siberia derived from the integral methane balance in the troposphere

    NASA Astrophysics Data System (ADS)

    Bogomolov, Vasiliy; Stepanenko, Victor; Okladnikov, Igor

    2013-04-01

    Although a number of estimates of methane emissions from large Earth regions have been proposed, based on either empirical or inverse transport modeling approaches, these emissions still remain highly uncertain motivating the development of new methods of surface flux assessment. In this study a new mathematical formulation for calculation of surface flux of methane, or any other gaseous component of the atmosphere, is developed. In it, the surface flux is retrieved from the integral balance of methane in bounded atmospheric domain. This balance includes the surface flux, the net advective flux through lateral boundaries of the atmospheric domain, methane sink due to oxidation by hydroxyl radical, and the rate of change of total methane amount in the domain. Western Siberia, being on of the most prominent surface methane sources in Northern hemisphere, is used as a test region for the method. The components of methane balance are calculated using methane concentrations and wind speeds from MACC reanalysis at 1.125 deg. grid (http://www.ecmwf.int/research/EU_projects/MACC), and hydroxyl concentrations provided by (Spivakovsky, 2000). The total methane flux from Western Siberia is thus assessed at 6 h resolution for 2001-2011. The time averaged total flux corresponds well to empirical estimates (M Glagolev, 2011) at diurnal and annual timescales. It may be anticipated that the method will be useful in close future when the satellite-retrieved methane concentration profiles will achieve high accuracy. References: Spivakovsky, C. M., et al. (2000), Three-dimensional climatological distribution of tropospheric OH: Update and evaluation, J. Geophys. Res., 105, 8931- 8980. M Glagolev, I Kleptsova, I Filippov, S Maksyutov and T Machida. Regional methane emission from West Siberia mire landscapes. Environ. Res. Lett. 6 (2011) 045214 (7pp). This work is partially supported by the Ministry of education and science of the Russian Federation (contract#8345), SB RAS project VIII.80.2.1, RFBR grant #11-05-01190a, and integrated project SB RAS #131, RFBR grant 11-05-01190-a.

  7. Atmospheric Impact of Large Methane Emission in the Arctic Region

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, S.; Cameron-Smith, P. J.; Bergmann, D.; Reagan, M. T.; Collins, W.; Elliott, S. M.; Maltrud, M. E.

    2011-12-01

    A highly potent greenhouse gas, methane, is locked in the solid phase as ice-like deposits containing a mixture of water and gas (mostly methane) called clathrates, in ocean sediments and underneath permafrost regions. Clathrates are stable under high pressure and low temperatures. Recent estimates suggest that about 1600 - 2000GtC of clathrates are present in oceans and 400GtC in Arctic permafrost (Archer et al.2009) which is about 4000 times that of current annual emissions. In a warming climate, increase in ocean temperatures could alter the geothermal gradient, which in turn could lead to dissociation of the clathrates and release of methane into the ocean and subsequently into the atmosphere as well. This could be of particular importance in the shallow part of the Arctic Ocean where the clathrates are found in depths of only 300m. In this presentation, we shall show results from our ongoing simulation of a scenario of large scale methane outgassing from clathrate dissociation due to warming ocean temperatures in the Arctic based on ocean sediment modeling. To that end we use the CESM (Community Earth System Model) version 1 with fully active coupled atmosphere-ocean-land model together with fast atmospheric chemistry module to simulate the response to increasing methane emissions in the Barents Sea, Canadian Archipelago and the Sea of Okhotsk. The simulation shows the effect these methane emissions could have on global surface methane, surface ozone, surface air temperature and other related indices. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-491764

  8. ESTIMATE OF GLOBAL METHANE EMISSIONS FROM LANDFILLS AND OPEN DUMPS

    EPA Science Inventory

    The report presents an empirical model to estimate global methane (CH4) emissions from landfills and open dumps based on EPA data from landfill gas (LFG) recovery projects. The EPA CH4 estimates for 1990 range between 19 and 40 teragrams (10 to the 12th power) per year (Tg/yr), w...

  9. Evening methane emission pulses from a boreal wetland correspond to convective mixing in hollows

    NASA Astrophysics Data System (ADS)

    Godwin, Casey M.; McNamara, Patrick J.; Markfort, Corey D.

    2013-07-01

    and temporal heterogeneity of methane flux from boreal wetlands makes prediction and up-scaling challenging, both within and among wetland systems. Drivers of methane production and emissions are also highly variable, making empirical model development difficult and leading to uncertainty in methane emissions estimates from wetlands. Previous studies have examined this problem using point-scale (static chamber method) and ecosystem-scale (flux tower methods) measurements, but few studies have investigated whether different processes are observed at these scales. We analyzed methane emissions from a boreal fen, measured by both techniques, using data from the Boreal Ecosystem-Atmosphere Study. We sought to identify driving processes associated with methane emissions at two scales and explain diurnal patterns in emissions measured by the tower. The mean methane emission rates from flux chambers were greater than the daytime, daily mean rates measured by the tower, but the nighttime, daily mean emissions from the tower were often an order of magnitude greater than emissions recorded during the daytime. Thus, daytime measurements from either the tower or chambers would lead to a biased estimate of total methane emissions from the wetland. We found that the timing of nighttime emission events was coincident with the cooling and convective mixing within hollows, which occurred regularly during the growing season. We propose that diurnal thermal stratification in shallow pools traps methane by limiting turbulent transport. This methane stored during daytime heating is later released during evening cooling due to convective turbulent mixing.

  10. Higher Methane Emissions in Regions of Sea Ice Retreat

    NASA Astrophysics Data System (ADS)

    Parmentier, F. J. W.; Zhang, W.; Mi, Y.; Zhu, X.; Miller, P. A.; van Huissteden, K. J.; Hayes, D. J.; Zhuang, Q.; McGuire, A. D.; Christensen, T. R.

    2014-12-01

    Arctic sea ice has seen a tremendous decline in recent decades, concurrently leading to higher temperatures across the high latitudes. Although increasingly strong evidence exists for this link between sea ice and temperature, the extra step of linking sea ice retreat - through these climatic changes - to a change in greenhouse-gas exchange is much less obvious. Recently, however, it has been suggested that methane emissions have increased as sea ice declined (Parmentier et al., 2013), leading to concerns that sea ice decline has led to a perturbation of the terrestrial component of the Arctic greenhouse gas balance. This initial analysis, however, compared average methane emissions of the Arctic Region with anomalies in the average sea ice extent for the entire summer, which evens out regional and temporal differences. The pattern of year-to-year fluctuations in sea ice extent varies from region to region and the impact on methane emissions - through temperature - is therefore expected to vary spatially, too. Our goal is thus to elucidate to what degree a correlation between methane emissions and sea ice exists in areas of high retreat compared to areas that have seen less sea ice decline. In addition, the impact of sea ice retreat on methane emissions is investigated throughout the melt season to identify those periods in which the teleconnection between sea ice and methane emissions is most pronounced. To this purpose, the output from three regional methane models (LPJ-GUESS WhyMe, Peatland-VU and TEM6) has been compared to independent observations of sea ice extent, and subjected to a rigorous spatial and temporal analysis. A similar response to sea ice retreat among these models will increase our confidence that teleconnections between methane emissions and sea ice decline exist within the Arctic. References: Parmentier, F. J. W., Christensen, T. R., Sørensen, L. L., Rysgaard, S., McGuire, A. D., Miller, P. A., & Walker, D. A. (2013). The impact of lower sea-ice extent on Arctic greenhouse-gas exchange. Nature Climate Change, 3, 195-202. doi:10.1038/nclimate1784

  11. Global methane emissions from the world coal industry

    Microsoft Academic Search

    P. C. Thakur; I. J. Graham-Bryce; W. G. Karis; K. M. Sullivan

    1994-01-01

    The Coal Industry Advisory Board (CIAB) of the International Energy Agency (IEA) estimated the total methane emissions from worldwide mining, treatment and storage of coal to be approximately 25 million tonnes\\/year for 1990. Slightly more than one million tonnes of methane are utilized by the industry. Thus, the net annual discharge to the atmosphere is 24 million tonnes. Methane emissions

  12. A COMPARISON OF METHODS FOR ESTIMATING METHANE EMISSIONS

    E-print Network

    Paris-Sud XI, Université de

    the contribution to the greenhouse effect due to methane emitted by municipal solid waste landfills. The objective an inventory of methane emissions covering all municipal solid waste landfills in France. EQUIPMENT AND METHODSA COMPARISON OF METHODS FOR ESTIMATING METHANE EMISSIONS FROM MSW LANDFILLS D. SAVANNE*, P. CASSINI

  13. A dynamic model for calculating methane emissions from digestate based on co-digestion of animal manure and biogas crops in full scale German biogas plants.

    PubMed

    Muha, Ivo; Linke, Bernd; Wittum, Gabriel

    2015-02-01

    The focus of this work is the development of a model for the estimation of methane emissions for storage tanks of biogas plants. Those can be estimated depending on (i) hydraulic retention time in the digester, (ii) an arbitrary removal rate of the digestate from the storage tank and (iii) arbitrary temperature conditions in the storage tank. Furthermore, the model is capable of considering an arbitrary mixture of manure and crops in the input material. The model was validated by data from 21 full scale biogas plants in Germany digesting cow manure and crops. A realistic scenario for the removal rate and temperature conditions in the storage tank was then investigated and special emphasis was given to the effect of hydraulic retention time and proportion of crops in the mixture on the input VS methane yield from the digester and the storage tank. PMID:25239786

  14. Methane in the Baltic and North Seas and a reassessment of the marine emissions of methane

    SciTech Connect

    Bange, H.W.; Bartell, U.H.; Rapsomanikis, S. [Max Planck Institute for Chemistry, Mainz (Germany)] [and others] [Max Planck Institute for Chemistry, Mainz (Germany); and others

    1994-12-01

    During three measurement campaigns on the Baltic and North Seas, atmospheric and dissolved methane was determined with an automated gas chromatographic system. Area-weighted mean saturation values in the sea surface waters were 113{+-}5% and 395{+-}82% and 126{+-}8%. On the bases of our data and a compilation of literature data the global oceanic emissions of methane were reassessed by introducing a concept of regional gas transfer coefficients. Our estimates computed with two different air-sea exchange models lie in the range of 11-18 Tg CH{sub 4} yr{sup -1}. Despite the fact that shelf areas and estuaries only represent a small part of the world`s ocean they contribute about 75% to the global oceanic emissions. We applied a simple, coupled, three-layer model to evaluate the time dependent variation of the oceanic flux to the atmosphere. The model calculations indicate that even with increasing tropospheric methane concentration, the ocean will remain a source of atmospheric methane. 72 refs., 7 figs., 7 tabs.

  15. Extreme Methane Emissions from a Swiss Hydropower Reservoir

    E-print Network

    Wehrli, Bernhard

    Extreme Methane Emissions from a Swiss Hydropower Reservoir: Contribution from Bubbling Sediments and their importance were quantified during a yearlong survey of a temperate hydropower reservoir. Measurements using

  16. Methane emissions in the US and Canada: contributions of various source sectors and evolution of emissions over time

    NASA Astrophysics Data System (ADS)

    Miller, S. M.; Michalak, A. M.; Wofsy, S. C.; Andrews, A. E.; Biraud, S.; Dlugokencky, E. J.; Fischer, M. L.; Janssens-Maenhout, G.; Kort, E. A.; Miller, B. R.; Miller, J. B.; Montzka, S. A.; Worthy, D. E. J.

    2014-12-01

    In this presentation, we quantify several aspects of methane emissions in the US and Canada using concentration data collected in the atmosphere. First, how much methane in total is emitted from the US and Canada? Second, how much methane is emitted from each individual source across these countries? Third, and finally, how have each of these sources changed in magnitude over the past ten to twenty years? To answer these questions, we use a geostatistical model-data fusion framework and spatial data on land use and economic activity. Using this approach, we estimate the contribution of different source types to methane emissions in the US and compare the magnitude of those anthropogenic emissions against natural fluxes from major wetlands like those near Hudson Bay, Canada. Furthermore, we examine the time-evolution of methane concentrations over regions dominated by agriculture and natural gas extraction and investigate what this data indicates about changes in emissions over time.

  17. Methane emission by bubbling from Gatun Lake, Panama

    Microsoft Academic Search

    Michael Keller; Robert F. Stallard

    1994-01-01

    We studied methane emission by bubbling from Gatun Lake, Panama, at water depths of less than 1 m to about 10 m. Gas bubbles were collected in floating traps deployed during 12- to 60-hour observation periods. Comparison of floating traps and floating chambers showed that about 98% of methane emission occurred by bubbling and only 2% occurred by diffusion. Average

  18. Environmental controls on Pan-Arctic wetland methane emissions

    NASA Astrophysics Data System (ADS)

    Chen, Xiaodong; Bohn, Theodore; Lettenmaier, Dennis

    2015-04-01

    Environmental conditions such as soil temperature and moisture, incident solar radiation, and atmospheric carbon dioxide concentration are important environmental controls on methane emissions from northern wetlands. We investigated the spatio-temporal distributions of influence of these factors over northern wetland methane emissions via the Variable Infiltration Capacity (VIC) model. We simulated methane emissions from wetlands across the Pan-Arctic domain over the period 1948-2006, with annual average emissions of 35.1±6.7 TgCH4/year. From control simulations that each held one environmental factor constant, we characterized sensitivities to air temperature, precipitation, incident long- and short-wave radiation, and atmospheric [CO2] as a function of average summer air temperature and precipitation. Trade-offs between air temperature and precipitation caused maximal emissions to occur along a line in precipitation-temperature space with a slope of approximately 13 mm month-1 / K, leading to separation of wetlands into various combinations of water-limited and temperature-limited regimes. Emissions from relatively warm and dry wetlands in the southern (permafrost-free) portion of the domain tended to be positively correlated with precipitation and negatively correlated with air temperature, while emissions from wetter and colder wetlands further north (permafrost) tended to be positively correlated with air temperature. Over the period 1960-2006, emissions increased by 20%, over 90% of which can be attributed to climate change, with summer air temperatures explaining the majority of the variance. We estimated future emissions in response to CMIP5 model projections under the RCP4.5 scenario via two methods: (1) the VIC model and (2) the temperature- and precipitation-dependent sensitivities computed from the historical simulation. The two methods yielded similar projections of emissions, with end-of-century emissions at 142% of present-day levels, accompanied by an expansion of the area of water-limited wetlands. Both the magnitude of the increase in emissions and the widespread drying of wetlands are corroborated by other recent process-based studies.

  19. 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 ?13C 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

  20. Extreme methane emissions from a Swiss hydropower reservoir: contribution from bubbling sediments.

    PubMed

    Delsontro, Tonya; McGinnis, Daniel F; Sobek, Sebastian; Ostrovsky, Ilia; Wehrli, Bernhard

    2010-04-01

    Methane emission pathways and their importance were quantified during a yearlong survey of a temperate hydropower reservoir. Measurements using gas traps indicated very high ebullition rates, but due to the stochastic nature of ebullition a mass balance approach was crucial to deduce system-wide methane sources and losses. Methane diffusion from the sediment was generally low and seasonally stable and did not account for the high concentration of dissolved methane measured in the reservoir discharge. A strong positive correlation between water temperature and the observed dissolved methane concentration enabled us to quantify the dissolved methane addition from bubble dissolution using a system-wide mass balance. Finally, knowing the contribution due to bubble dissolution, we used a bubble model to estimate bubble emission directly to the atmosphere. Our results indicated that the total methane emission from Lake Wohlen was on average >150 mg CH(4) m(-2) d(-1), which is the highest ever documented for a midlatitude reservoir. The substantial temperature-dependent methane emissions discovered in this 90-year-old reservoir indicate that temperate water bodies can be an important but overlooked methane source. PMID:20218543

  1. Methane emissions from Alaska in 2012 from CARVE airborne observations

    PubMed Central

    Chang, Rachel Y.-W.; Miller, Charles E.; Dinardo, Steven J.; Karion, Anna; Sweeney, Colm; Daube, Bruce C.; Henderson, John M.; Mountain, Marikate E.; Eluszkiewicz, Janusz; Miller, John B.; Bruhwiler, Lori M. P.; Wofsy, Steven C.

    2014-01-01

    We determined methane (CH4) emissions from Alaska using airborne measurements from the Carbon Arctic Reservoirs Vulnerability Experiment (CARVE). Atmospheric sampling was conducted between May and September 2012 and analyzed using a customized version of the polar weather research and forecast model linked to a Lagrangian particle dispersion model (stochastic time-inverted Lagrangian transport model). We estimated growing season CH4 fluxes of 8 ± 2 mg CH4?m?2?d?1 averaged over all of Alaska, corresponding to fluxes from wetlands of 56?13+22 mg CH4?m?2?d?1 if we assumed that wetlands are the only source from the land surface (all uncertainties are 95% confidence intervals from a bootstrapping analysis). Fluxes roughly doubled from May to July, then decreased gradually in August and September. Integrated emissions totaled 2.1 ± 0.5 Tg CH4 for Alaska from May to September 2012, close to the average (2.3; a range of 0.7 to 6 Tg CH4) predicted by various land surface models and inversion analyses for the growing season. Methane emissions from boreal Alaska were larger than from the North Slope; the monthly regional flux estimates showed no evidence of enhanced emissions during early spring or late fall, although these bursts may be more localized in time and space than can be detected by our analysis. These results provide an important baseline to which future studies can be compared. PMID:25385648

  2. Methane Emissions from the Arctic Ocean to the Atmosphere

    NASA Astrophysics Data System (ADS)

    Platt, Stephen; Hermansen, Ova; Schmidbauer, Norbert; Pisso, Ignacio; Silyakova, Anna; Ferré, Benedicte; Lowry, Dave; Percival, Carl; Mienert, Jürgen; Myhre, Cathrine Lund

    2015-04-01

    The release of methane (CH4) presently stored in vast hydrate deposits under the seafloor is a potential climate tipping point and a major uncertainty in the global methane budget. Significant methane hydrate deposits are located in shallow waters in the Arctic where they may destabilise, releasing methane to the atmosphere due to ocean warming. To address this issue the Methane Emissions from Arctic Ocean to Atmosphere (MOCA, http://moca.nilu.no/) project was established in cooperation with the CAGE Centre of Excellence (http:cage.uit.no/). State-of-the-art oceanographic and atmospheric measurement techniques were applied over a large area of the Arctic including northern Norway, the Barents Sea, and areas of shallow water around Svalbard during summer 2014. Oceanographic measurements included the deployment of 63 measurement stations (temperature, salinity, density, oxygen, fluorescence, turbidity, etc.), water column sampling (CH4, nitrate, phosphate, silicates), and echo sounding (revealing locations where streams of gas bubbles are vented). Atmospheric on-line measurements were performed aboard the research vessel Helmer Hanssen (CH4, CO2, CO, meteorological parameters) and during a flight campaign (CH4, etc.). Air samples were collected for isotopic analysis (13C, 2H) and quantification of other hydrocarbons (ethane, propane, etc.). Finally, atmospheric measurements are compared with long term data sets from the nearby Zeppelin Mountain monitoring station (Ny Ålesund, Svalbard). Back-trajectory analysis and FLEXPART modelling are used to rule out non-local sources. Here we present an overview of all of these activities and the first results from MOCA in cooperation with CAGE - Centre for Arctic Gas Hydrate, and Climate at UiT, The Arctic University of Norway. We demonstrate that there are hotspots of activity where hydrocarbons are being emitted from the ocean, while in some areas emissions are surprisingly well contained by local biological and hydrological conditions.

  3. 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

    2015-01-01

    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. PMID:26123199

  4. Methane and nitrous oxide emissions of China: Sources from agricultural systems and mitigation options

    SciTech Connect

    Lin Erda; Li Yue; Dong Hongmin; Zhou Wennong [Chinese Academy of Agricultural Sciences, Beijing (China). Agro-meteorology Inst.

    1994-12-31

    This paper reports the estimated results of methane and nitrous oxide emissions from China`s agricultural systems. The results show that the overall methane emissions from paddies and ruminants were 11.335 and 5.796 Tg/y, respectively in 1990. For mitigation options, based on some experiments, a number of options were recommended to reduce methane and nitrous oxide emissions. Several research priority areas were proposed to reduce the uncertainties in estimates they are: (1) improve measurement methods; (2) further identify controlling factors; and (3) develop simulation models.

  5. Methane emissions in India: Sub-regional and sectoral trends

    NASA Astrophysics Data System (ADS)

    Garg, Amit; Kankal, Bhushan; Shukla, P. R.

    2011-09-01

    This paper uses the 2006 IPCC Guidelines and latest country specific emission factors to estimate Indian methane emissions at sectoral and district level for the years 1990, 1995, 2005 and 2008. The estimates show that while methane emissions have increased steadily over past two decades, their share in India's aggregate GHG emissions has declined from 31% in 1985 to 27% in 2008 mainly due to relatively higher growth CO 2 emissions from the fossil fuels. The estimates for the year 2008 show that: i) agriculture sector, which employed two-thirds of India's population and contributed 17% of GDP, accounted for 23% of India's GHG emissions ii) 83% of country's methane emissions are contributed by enteric fermentation, manure use and rice production, and iii) methane emissions from urban solid waste are steadily rising over the past two decades; their share in aggregate methane emissions has reached 8%. Resting on the disaggregated emissions estimates, the paper argues for using geographical and sectoral flexibilities to develop a roadmap for mitigation of methane emissions for India.

  6. Determination of methane emission rates on a biogas plant using data from laser absorption spectrometry.

    PubMed

    Groth, Angela; Maurer, Claudia; Reiser, Martin; Kranert, Martin

    2015-02-01

    The aim of the work was to establish a method for emission control of biogas plants especially the observation of fugitive methane emissions. The used method is in a developmental stage but the topic is crucial to environmental and economic issues. A remote sensing measurement method was adopted to determine methane emission rates of a biogas plant in Rhineland-Palatinate, Germany. An inverse dispersion model was used to deduce emission rates. This technique required one concentration measurement with an open path tunable diode laser absorption spectrometer (TDLAS) downwind and upwind the source and basic wind information, like wind speed and direction. Different operating conditions of the biogas plant occurring on the measuring day (December 2013) could be represented roughly in the results. During undisturbed operational modes the methane emission rate averaged 2.8 g/s, which corresponds to 4% of the methane gas production rate of the biogas plant. PMID:25446786

  7. Methane Emissions from Rice Fields - Final Report

    SciTech Connect

    Khalil, M. Aslam; Rasmussen,Reinhold A.

    2002-12-03

    Methane (Ch4) is a greenhouse gas regarded second only to carbon dioxide in its ability to cause global warming. Methane is important because of its relatively fast increase, and also because it is, per molecule, some 60 times more effective than carbon dioxide in causing global warming. The largest present anthropogenic sources of methane are rice fields, cattle and biomass burning.

  8. Field-scale operation of methane biofiltration systems to mitigate point source methane emissions.

    PubMed

    Hettiarachchi, Vijayamala C; Hettiaratchi, Patrick J; Mehrotra, Anil K; Kumar, Sunil

    2011-06-01

    Methane biofiltration (MBF) is a novel low-cost technique for reducing low volume point source emissions of methane (CH?). MBF uses a granular medium, such as soil or compost, to support the growth of methanotrophic bacteria responsible for converting CH? to carbon dioxide (CO?) and water (H?O). A field research program was undertaken to evaluate the potential to treat low volume point source engineered CH? emissions using an MBF at a natural gas monitoring station. A new comprehensive three-dimensional numerical model was developed incorporating advection-diffusive flow of gas, biological reactions and heat and moisture flow. The one-dimensional version of this model was used as a guiding tool for designing and operating the MBF. The long-term monitoring results of the field MBF are also presented. The field MBF operated with no control of precipitation, evaporation, and temperature, provided more than 80% of CH? oxidation throughout spring, summer, and fall seasons. The numerical model was able to predict the CH? oxidation behavior of the field MBF with high accuracy. The numerical model simulations are presented for estimating CH? oxidation efficiencies under various operating conditions, including different filter bed depths and CH? flux rates. The field observations as well as numerical model simulations indicated that the long-term performance of MBFs is strongly dependent on environmental factors, such as ambient temperature and precipitation. PMID:21414700

  9. Revised methane emissions from the East Siberian Artic Shelf

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  10. Atmospheric Inverse Estimates of Methane Emissions from Central California

    SciTech Connect

    Zhao, Chuanfeng; Andrews, Arlyn E.; Bianco, Laura; Eluszkiewicz, Janusz; Hirsch, Adam; MacDonald, Clinton; Nehrkorn, Thomas; Fischer, Marc L.

    2008-11-21

    Methane mixing ratios measured at a tall-tower are compared to model predictions to estimate surface emissions of CH{sub 4} in Central California for October-December 2007 using an inverse technique. Predicted CH{sub 4} mixing ratios are calculated based on spatially resolved a priori CH{sub 4} emissions and simulated atmospheric trajectories. The atmospheric trajectories, along with surface footprints, are computed using the Weather Research and Forecast (WRF) coupled to the Stochastic Time-Inverted Lagrangian Transport (STILT) model. An uncertainty analysis is performed to provide quantitative uncertainties in estimated CH{sub 4} emissions. Three inverse model estimates of CH{sub 4} emissions are reported. First, linear regressions of modeled and measured CH{sub 4} mixing ratios obtain slopes of 0.73 {+-} 0.11 and 1.09 {+-} 0.14 using California specific and Edgar 3.2 emission maps respectively, suggesting that actual CH{sub 4} emissions were about 37 {+-} 21% higher than California specific inventory estimates. Second, a Bayesian 'source' analysis suggests that livestock emissions are 63 {+-} 22% higher than the a priori estimates. Third, a Bayesian 'region' analysis is carried out for CH{sub 4} emissions from 13 sub-regions, which shows that inventory CH{sub 4} emissions from the Central Valley are underestimated and uncertainties in CH{sub 4} emissions are reduced for sub-regions near the tower site, yielding best estimates of flux from those regions consistent with 'source' analysis results. The uncertainty reductions for regions near the tower indicate that a regional network of measurements will be necessary to provide accurate estimates of surface CH{sub 4} emissions for multiple regions.

  11. Effect of water and heat transport processes on methane emissions from paddy soils: a process-based model analysis

    NASA Astrophysics Data System (ADS)

    Rizzo, Anacleto; Boano, Fulvio; Revelli, Roberto; Ridolfi, Luca

    2013-04-01

    High CH4 fluxes are emitted from paddy fields worldwide and represent a considerable issue for the rice production eco-sustainability. Water and heat transport fluxes are known to strongly influence biogeochemical cycles in wetland environments, and therefore also CH4 emissions from paddy soils. Water percolation affects the dynamics of many compounds (e.g. DOC, O2) influencing CH4 fate. On the other hand, heat fluxes strongly influence CH4 production in submerged rice crops, and lowering ponding water temperature (LPWT) can reduce microbial activities and consequently decrease CH4 emissions. Moreover, as long as the optimal temperature range for rice growth is maintained, LPWT can lower CH4 emissions without rice yield limitation. Hence, a process-based model is proposed and applied to investigate the role of water flow on CH4 emissions, and to analyse the efficiency of LPWT as mitigation strategy for CH4 production and release. The process-based model relies on a system of partial differential mass balance equations to describe the vertical dynamics of the chemical compounds leading to CH4 production. Many physico-chemical processes and features characteristic of paddy soil are included: paddy soil stratigraphy; spatio-temporal variations of plant-root compartment; water and heat transport; SOC decomposition; heterotrophic reactions in both aerobic and anaerobic conditions; root radial oxygen loss; root solute uptake; DOC root exudation; plant-mediated, ebullition, and diffusion gas exchange pathways. LPWT is included as a temperature shift subtracted directly to the ponding water temperature. Model results confirm the importance of water flow on CH4 emission, since simulations that do not include water fluxes show a considerable overestimation of CH4 emissions due to a different DOC spatio-temporal dynamics. Particularly, when water fluxes are not modeled the overestimation can reach 67 % of the total CH4 emission over the whole growing season. Moreover, model results also suggest that roots influence CH4 dynamics principally due to their solute uptake, while root effect on advective flow plays a minor role. In addition, the analysis of CH4 transport fluxes show the limiting effect of upward dispersive transport fluxes on the downward CH4 percolation. Finally, LPWT is confirmed to be a valid mitigation strategy for CH4 emissions from paddy soils, since the reduction of CH4 emission reach about -50 % with a LPWT equal to only 2°C over the whole growing season.

  12. Methane emissions to the atmosphere through aquatic plants

    Microsoft Academic Search

    D. I. Sebacher; R. C. Harriss; K. B. Bartlett

    2009-01-01

    The movement of methane (CHâ) from anaerobic sediments through the leaves, stems, and flowers of aquatic plants and into the atmosphere was found to provide a significant pathway for the emission of CHâ from the aquatic substrates of flooded wetlands. Methane concentrations well above the surrounding ambient air levels were found in the mesophyll of 16 varieties of aquatic plants

  13. Modeling the fate of methane hydrates under global warming

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    Large amounts of methane hydrate locked up within marine sediments are vulnerable to climate change. Changes in bottom water temperatures may lead to their destabilization and the release of methane into the water column or even the atmosphere. In a multimodel approach, the possible impact of destabilizing methane hydrates onto global climate within the next century is evaluated. The focus is set on changing bottom water temperatures to infer the response of the global methane hydrate inventory to future climate change. Present and future bottom water temperatures are evaluated by the combined use of hindcast high-resolution ocean circulation simulations and climate modeling for the next century. The changing global hydrate inventory is computed using the parameterized transfer function recently proposed by Wallmann et al. (2012). We find that the present-day world's total marine methane hydrate inventory is estimated to be 1146 Gt of methane carbon. Within the next 100 years this global inventory may be reduced by ˜0.03% (releasing ˜473 Mt methane from the seafloor). Compared to the present-day annual emissions of anthropogenic methane, the amount of methane released from melting hydrates by 2100 is small and will not have a major impact on the global climate. On a regional scale, ocean bottom warming over the next 100 years will result in a relatively large decrease in the methane hydrate deposits, with the Arctic and Blake Ridge region, offshore South Carolina, being most affected.

  14. Estimates of methane emission from large stationary combustion sources

    SciTech Connect

    Watanabe, Ikuo (National Inst. of Public Health, Tokyo (Japan)); Matsuura, Akiyoshi (Chiba Prefectural Research Inst. for Environmental Pollution (Japan))

    1992-01-01

    The emission factors of methane for nine categories of large stationary sources working continuously with various fuels were estimated from the data published in Japan, on the assumption that the feeding air contained 1.8 {mu}L/L (ppm) of methane. Boilers, heating furnaces, metal furnaces, and glass-melting furnaces were found to have minus emission factors, and as a result, they are regarded as the sinks of atmospheric methane. The maximum removal rate of methane at electric power plants is determined roughly to be ca. 1 Gg/y (10{sup 9} g/y) in Japan and 18 Gg/y in the world. On the other hand, coke ovens and sintering furnaces were considered to be significant industrial sources, and the minimum emission rate is determined roughly to be ca. 20 Gg/y in Japan and ca. 120 Gg/y worldwide. These estimates are based on modernized facilities with efficiently controlled operations. Therefore, the magnitude of the methane emission from large stationary sources is not high if they are operated in similar conditions to those in Japan. Some facilities, however, such as coke ovens or hot-blast furnaces which generate coke-oven gas or blast-furnace gas which contain methane at high concentration, are shown to have a higher potential possibility of methane emission into the air.

  15. 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.

  16. Mitigating enteric methane emissions: Where are the biggest opportunities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many opportunities exist to reduce enteric methane emissions per unit of product from ruminant livestock. These include alterations in feeding management and nutrition, addition of compounds to modify rumen function, genetic improvements to increase animal lifetime productivity (including health and...

  17. MEASUREMENT OF METHANE EMISSIONS FROM UNDERGROUND DISTRIBUTION MAINS AND SERVICES

    EPA Science Inventory

    The paper reports results of measurements of methane emissions from underground distribution mains and services. In the program, leakage from underground distribution systems is estimated by combining leak measurements with historical leak record data and the length of undergroun...

  18. Emissions of Methane and Other Hydrocarbons Due to Wellbore Leaks

    NASA Astrophysics Data System (ADS)

    Lyman, S. N.; Mansfield, M. L.

    2013-12-01

    The explosive growth of oil and gas production in the United States has focused public and regulatory attention on environmental impacts of hydrocarbon extraction, including air quality and climate impacts. However, EPA and others have acknowledged that current air emissions factors and inventories for many oil and gas-related source categories are inadequate or lacking entirely. One potentially important emissions source is leakage of natural gas from wellbores. This phenomenon has long been recognized to occur, but no attempt has been made to quantify emission rates of gas leaked from wellbores to the atmosphere. Soil gas measurements carried out by USGS over the last several years in Utah's oil and gas fields have shown that, while concentrations of methane in soils near many wells are low, soil gas near some wells can contain more than 10% methane, indicating that underground leakage is occurring. In summer 2013 we carried out a campaign to measure the emission rate of methane and other hydrocarbons from soils near wells in two oil and gas fields in Utah. We measured emissions from several locations on some well pads to determine the change in emission rate with distance from well heads, and we measured at non-well sites in the same fields to determine background emission rates. Methane emission rates at some wells exceeded 3 g m-2 h-1, while emission rates at other wells were similar to background levels, and a correlation was observed between soil gas methane concentrations and methane emission rates from the soil. We used these data to estimate total methane and hydrocarbon emission rates from these two fields.

  19. Annual Estimates of Global Anthropogenic Methane Emissions: 1860-1994

    NSDL National Science Digital Library

    Kaufmann, Robert K.

    1998-01-01

    David Stern and Robert Kaufmann, of the Center for Energy and Environmental Studies at Boston University, provide "the first estimates," by year, of human-made methane emissions from seven sources, including gas flaring, coal mining, and biomass burning. Data are available in ASCII or binary spreadsheet formats, and a graph shows the rise in methane emissions from 1860 to 1994. The site explains Stern and Kaufmann's methods, including mathematical equations.

  20. Methane emission by bubbling from Gatun Lake, Panama

    SciTech Connect

    Keller, M. [National Center for Atmospheric Research, Boulder, CO (United States)] [National Center for Atmospheric Research, Boulder, CO (United States); Stallard, R.F. [Geological Survey, Denver, CO (United States)] [Geological Survey, Denver, CO (United States)

    1994-04-20

    We studied methane emission by bubbling from Gatun Lake, Panama, at water depths of less than 1 m to about 10 m. Gas bubbles were collected in floating traps deployed during 12- to 60-hour observation periods. Comparison of floating traps and floating chambers showed that about 98% of methane emission occurred by bubbling and only 2% occurred by diffusion. Average methane concentration of bubbles at our sites varied from 67% to 77%. Methane emission by bubbling occurred episodically, with greatest rates primarily between the hours of 0800 and 1400 LT. Events appear to be triggered by wind. The flux of methane associated with bubbling was strongly anticorrelated with water depth. Seasonal changes in water depth caused seasonal variation of methane emission. Bubble methane fluxes through the lake surface into the atmosphere measured during 24-hour intervals were least (10-200 mg m{sup -2} d{sup -1}) at deeper sites (>7 m) and greatest (300-2000 mg m{sup -2} d{sup -1}) at shallow sites (<2 m). 37 refs., 11 figs., 5 tabs.

  1. Moving Up to the Top of the Landfill: A Field-Validated, Science-Based Methane Emissions Inventory Model for California Landfills

    Technology Transfer Automated Retrieval System (TEKTRAN)

    California is typically at the forefront of innovative planning & regulatory strategies for environmental protection in the U.S. Two years ago, a research project was initiated by the California Energy Commission to develop an improved method for landfill methane emissions for the state greenhouse ...

  2. Sensitivity of detection of fugitive methane emissions from coal seam gas fields

    NASA Astrophysics Data System (ADS)

    Feitz, A. J.; Berko, H.; Wilson, P.; Jenkins, C.; Loh, Z. M.; Etheridge, D.

    2013-12-01

    There is increasing recognition that minimising methane emissions from the oil and gas sector is a key step in reducing global greenhouse gas emissions in the near term. Atmospheric monitoring techniques are likely to play an important future role in measuring the extent of existing emissions and verifying emission reductions. They can be very suitable for monitoring gas fields as they are continuous and integrate emissions from a number of potential point and diffuse sources that may vary in time. Geoscience Australia and CSIRO Marine & Atmospheric Research have collected three years of continuous methane and carbon dioxide measurements at their atmospheric composition monitoring station ('Arcturus') in the Bowen Basin, Australia. Methane signals in the Bowen Basin are likely to be influenced by cattle production, landfill, coal production, and conventional and coal seam gas (CSG) production. Australian CSG is typically 'dry' and is characterised by a mixed thermogenic-biogenic methane source with an absence of C3-C6+ alkanes. The range of ?13C isotopic signatures of the CSG is similar to methane from landfill gas and cattle emissions. The absence of standard in-situ tracers for CSG fugitive emissions suggests that having a comprehensive baseline will be critical for successful measurement of fugitive emissions using atmospheric techniques. In this paper we report on the sensitivity of atmospheric techniques for the detection of fugitive emissions from a simulated new CSG field against a three year baseline signal. Simulation of emissions was performed for a 1-year period using the coupled prognostic meteorological and air pollution model TAPM at different fugitive emission rates (i.e. estimates of <1% to up to 10% of production lost) and distances (i.e. 10 - 50 km) from the station. Emissions from the simulated CSG field are based on well density, production volumes, and field size typical of CSG fields in Australia. The distributions of the perturbed and baseline signals were evaluated and statistically compared to test for the presence of fugitive methane emissions. In addition, a time series model of the methane baseline was developed in order to generate alternative realizations of the baseline signal. These were used to provide measures of both the likelihood of detecting fugitive emissions at various emission levels and of the false alarm rate. Results of the statistical analysis and an indicative minimum fugitive methane emission rate that can be detected using a single monitoring station are presented.

  3. Methane emissions from a temperate agricultural reservoir

    EPA Science Inventory

    Dr. Jake Beaulieu was invited to present at the 2014 Green House Gas Emission Modeling workshop hosted by the International Energy Agency (IEA) Hydropower Implementing Agreement for Hydropower Technologies and Programs (IAHTP). The purpose of this workshop is to assemble an int...

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

    USGS Publications Warehouse

    Isaksen, Ivar S.A.; Gauss, Michael; Myhre, Gunnar; Walter Anthony, Katey M.; Ruppel, Carolyn

    2011-01-01

    The magnitude and feedbacks of future methane release from the Arctic region are unknown. Despite limited documentation of potential future releases associated with thawing permafrost and degassing methane hydrates, the large potential for future methane releases calls for improved understanding of the interaction of a changing climate with processes in the Arctic and chemical feedbacks in the atmosphere. Here we apply a “state of the art” atmospheric chemistry transport model to show that large emissions of CH4 would likely have an unexpectedly large impact on the chemical composition of the atmosphere and on radiative forcing (RF). The indirect contribution to RF of additional methane emission is particularly important. It is shown that if global methane emissions were to increase by factors of 2.5 and 5.2 above current emissions, the indirect contributions to RF would be about 250% and 400%, respectively, of the RF that can be attributed to directly emitted methane alone. Assuming several hypothetical scenarios of CH4 release associated with permafrost thaw, shallow marine hydrate degassing, and submarine landslides, we find a strong positive feedback on RF through atmospheric chemistry. In particular, the impact of CH4 is enhanced through increase of its lifetime, and of atmospheric abundances of ozone, stratospheric water vapor, and CO2 as a result of atmospheric chemical processes. Despite uncertainties in emission scenarios, our results provide a better understanding of the feedbacks in the atmospheric chemistry that would amplify climate warming.

  5. Atmospheric methane emissions along the western Svalbard margin

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  6. An approach for measuring methane emissions from whole farms.

    PubMed

    McGinn, S M; Flesch, T K; Harper, L A; Beauchemin, K A

    2006-01-01

    Estimates of enteric methane (CH4) emissions from ruminants are typically measured by confining animals in large chambers, using head hoods or masks, or by a ratiometric technique involving sampling respired air of the animal. These techniques are not appropriate to evaluate large-scale farm emissions and the variability between farms that may be partly attributed to different farm management. This study describes the application of an inverse-dispersion technique to calculate farm emissions in a controlled tracer-release experiment. Our study was conducted at a commercial dairy farm in southern Alberta, Canada (total of 321 cattle, including 152 lactating dairy cows). Sulfur hexafluoride (SF6) and CH4 were released from 10 outlet locations (barn and open pens) using mass-flow controllers. A Lagrangian stochastic (LS) dispersion model was then used to infer farm emissions from downwind gas concentrations. Concentrations of SF6 and CH4 were measured by gas chromatography analysis and open path lasers, respectively. Wind statistics were measured with a three-dimensional sonic anemometer. Comparing the inferred emissions with the known release rate showed we recovered 86% of the released CH4 and 100% of the released SF6. The location of the concentration observations downwind of the farm was critically important to the success of this technique. PMID:16391273

  7. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY: PRODUCTION AND TRANSMISSION EMISSIONS

    EPA Science Inventory

    The paper discusses a co-funded, Gas Research Institute/EPA project to quantify methane emissions to the atmosphere resulting from operations in the natural gas industry. tudy results will measure or calculate all methane emissions, from production at the well and up to, but not ...

  8. ESTIMATE OF GLOBAL METHANE EMISSIONS FROM COAL MINES

    EPA Science Inventory

    Country-specific emissions of methane (CH4) from underground coal mines, surface coal mines, and coal crushing and transport operations are estimated for 1989. Emissions for individual countries are estimated by using two sets of regression equations (R2 values range from 0.56 to...

  9. Methane emissions from fen, bog and swamp peatlands in Quebec

    Microsoft Academic Search

    T. R. Moore; R. Knowles

    1990-01-01

    A static chamber technique was used weekly from spring thaw to winter freezing to measure methane emissions from 10 sites representing subarctic fens and temperate swamps and bogs. Rates of 4 m-2 d-1 were recorded in subarctic fens: within-site emissions were primarily controlled by the evolution of the peat thermal regime, though significant releases during spring thaw were recorded at

  10. METHANE EMISSIONS FROM THE U.S. PETROLEUM INDUSTRY

    EPA Science Inventory

    The report quantifies methane (CH4) emissions from the U.S. petroleum industry by identifying sources of CH4 from the production, transportation, and refining of oil. Emissions are reported for the base year 1993 and for the years 1986 through 1992, based on adjustments to the ba...

  11. Biofiltration for mitigation of methane emission from animal husbandry.

    PubMed

    Melse, Roland W; Van der Werf, Arjan W

    2005-07-15

    Removal of methane from exhaust air of animal houses and manure storage has a large potential for the reduction of greenhouse gas emissions from animal husbandry. The aim of this study was to design a biofilter for methane removal at a full-scale livestock production facility. Air from the headspace of a covered 6 m3 liquid manure storage (air flow: 0.75-8.5 m3 m(-3) h(-1); CH4: 500-5500 mg m(-3)) was treated in an experimental biofilter (160 L). The filterbed, a mixture of compost and perlite in a 40:60 (v/v) ratio, was inoculated with activated sludge that had shown a good methane oxidation rate as compared to pure cultures in preceding laboratory tests. Methane removal up to 85% could be achieved in the experimental biofilter. The methane removal (g m(-3) h(-1)) appeared to be proportional to the concentration (g m(-3)) with k = 2.5 h(-1). Relatively low methane concentrations and high air flows, as reported for the exhaust air of animal houses, would require very large biofilter sizes. Extrapolation of the results showed that treatment of air from a 1000 m3 liquid manure storage with a methane concentration of 22 g m(-3) would require a 20 m3 biofilter for a desired emission reduction of 50%. The costs for such a biofilter are USD 26 per t of CO2 equiv reduction. PMID:16082981

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

    PubMed

    Qaderi, Mirwais M; Reid, David M

    2014-01-01

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

  13. Methane emissions from an alpine fen in central Switzerland

    Microsoft Academic Search

    Susanne Liebner; Simon P. Schwarzenbach; Josef Zeyer

    Methane emissions and below ground methane pore water concentrations were determined in an alpine fen at 1,915 m a.s.l. in\\u000a central Switzerland. The fen represented an acidic (pH 4.5–4.9), nutrient-poor to mesotrophic habitat dominated by Carex limosa, Carex rostrata, Trichophorum caespitosum and Sphagnum species. From late fall to late spring the fen was snow-covered. Throughout winter the temperatures never dropped below

  14. Coalbed methane modeling: Multicomponent effects

    SciTech Connect

    Whitney, E.M.

    1992-01-01

    Field data from coalbed methane wells indicate a significant variation in composition as a function of flow rate and time. Prediction of gas quality is critical to the economic evaluation of any coalbed methane project. Previous models have forecast only pressure and production profiles, ignoring compositional variations. A multicomponent model that incorporates binary isotherms for methane and carbon dioxide has been developed. An extended Langmuir Isotherm represents adsorption, and a constant relative separation factor describes the phase distribution of the species. This separation factor depends on the surface characteristics of the coal and on the adsorbing species. The model equations were cast in dimensionless form and solved for pressures and compositions. Solution of the equations was accomplished with a public-domain computer package for solution of stiff sets of ordinary differential equations, LSODE. The nonlinear equations were linearized with a three-point central finite difference scheme. Pressure profiles for primary depletion of a single phase gas reservoir are accurately forecast. The model also correctly predicts the qualitative trends of increasing CO[sub 2] concentration in produced gas. Variation of CO[sub 2] concentration in the produced gas is a function of the separation factor, the initial CO[sub 2] concentration in the reservoir, and the pressure depletion range. The model shows that the fraction of CO[sub 2] in the produced gas increases with dimensionless time. Dimensionless time is proportional to gas viscosity, coal porosity and reservoir length squared. A comprehensive sensitivity study was performed to identify the effects of important parameters such as isotherms variables and reservoir characteristics on primary depletion pressure and composition profiles.

  15. Diurnal Thermal De-stratification of Hollows Explains Substantial Nighttime Methane Emission in a Boreal Fen

    NASA Astrophysics Data System (ADS)

    Godwin, C. M.; McNamara, P. J.; Markfort, C. D.

    2012-12-01

    Boreal wetlands are a major source of methane to the atmosphere and are expected to have a net warming effect on global climate. It is well established that methane released from a wetland varies spatially and temporally with parameters such as topography, soil temperature, and soil moisture content. Several studies have compared point-scale measurements (static chamber method) and ecosystem-scale measurements (flux tower methods), but few studies have investigated whether different patterns or processes are observed at these scales. We analyzed methane emissions in a boreal fen, measured by both techniques, using data from the 1996 BOREAS project. The fen is comprised of hummocks and hollows, and the hollows are filled with water. We sought to address the questions (1) Does the flux tower capture temporal variability that is missed using static chambers, and (2) Which driving processes associated with methane emission are evident at these two scales? The mean daytime methane emission rates from chamber measurements were greater than the mean rates measured by the tower (137 - 225%), but the evening methane emission rates were often an order of magnitude greater than emission rates recorded during the daytime (mean 580%, max 13,800%). Thus, the use of only daytime measurements would lead to a substantial underestimation of total methane emissions from the wetland. We evaluated predictive models of methane flux at both scales using variables such as peat temperature, water table depth, and photosynthetic activity, but found poor predictive power using any of these state variables. However, the timing of evening emission events was coincident with the timing of thermal destratification in hollows. The events occurred most evenings during summer season. We propose that diurnal thermal stratification of shallow pools traps methane by limiting turbulent transport. The methane built up during daytime heating is later released due to convective cooling. Evidence of stratification-limited transport is provided by water column temperature gradient measurements. Continuous measurements of methane flux and water temperature profiles, even within small pools, allow for identification of these complex physical processes.

  16. Methane emissions from a dairy feedlot during the fall and winter seasons in Northern China.

    PubMed

    Gao, Zhiling; Yuan, Huijun; Ma, Wenqi; Liu, Xuejun; Desjardins, R L

    2011-05-01

    Accurately determining methane emission factors of dairy herd in China is imperative because of China's large population of dairy cattle. An inverse dispersion technique in conjunction with open-path lasers was used to quantify methane emissions from a dairy feedlot during the fall and winter seasons in 2009-2010. The methane emissions had a significant diurnal pattern during both periods with three emission peaks corresponding to the feeding schedule. A 10% greater emission rate in the fall season was obtained most likely by the higher methane emission from manure during that period. An annual methane emission rate of 109±6.7 kg CH4 yr(-1) characterized with a methane emission intensity of 32.3±1.59 L CH4 L(-1) of milk and a methane conversion factor (Ym) of 7.3±0.38% for mature cattle was obtained, indicating the high methane emission intensity and low milk productivity in Northern China. PMID:21354680

  17. A new approach to estimation of methane emission rates from landfills.

    PubMed

    Zhu, Han; Letzel, Marcus O; Reiser, Martin; Kranert, Martin; Bächlin, Wolfgang; Flassak, Thomas

    2013-12-01

    Methane emission monitoring has become increasingly essential for diffusive area sources, especially for landfills, which contribute to a significant fraction of the total anthropogenic methane emission globally. Statutorily, methane emission rate from landfills in Germany shall be examined on a semiannual basis; however, an appropriate approach has yet to be developed and adopted for general use. In this study, a new method is proposed based on experimental results, which utilizes a TDLAS (Tunable Diode Laser Absorption Spectroscopy) instrument - GasFinder2.0 system and a dispersion model LASAT (Lagrangian Simulation of Aerosol Transport) as the measurement device and calculation model, respectively. Between April 2010 and December 2011, a research project was conducted at a pilot scale landfill in the south of Germany. Drawing on the extensive research into this pilot project, an effective strategy of measurement setup was determined. Methane concentration was measured with GasFinder2.0 system in the upstream and downstream sections of the project site, while wind and turbulence data were measured simultaneously by an ultrasonic anemometer. The average methane emission rate from the source can be calculated by using the results as input data in the dispersion model. With this method, site-specific measurement approaches can be designed for not only landfills, but also different diffusive area sources with less workload and lower cost compared to conventional FID (Flame Ionization Detector) method. PMID:24084101

  18. Quantification of methane and nitrous oxide emissions from various waste treatment facilities by tracer dilution method

    NASA Astrophysics Data System (ADS)

    Mønster, Jacob; Rella, Chris; Jacobson, Gloria; Kjeldsen, Peter; Scheutz, Charlotte

    2013-04-01

    Urban activities generate solid and liquid waste, and the handling and aftercare of the waste results in the emission of various compounds into the surrounding environment. Some of these compounds are emitted as gasses into the atmosphere, including methane and nitrous oxide. Methane and nitrous oxide are strong greenhouse gases and are considered to have 25 and 298 times the greenhouse gas potential of carbon dioxide on a hundred years term (Solomon et al. 2007). Global observations of both gasses have shown increasing concentrations that significantly contribute to the greenhouse gas effect. Methane and nitrous oxide are emitted from both natural and anthropogenic sources and inventories of source specific fugitive emissions from the anthropogenic sources of methane and nitrous oxide of are often estimated on the basis of modeling and mass balance. Though these methods are well-developed, actual measurements for quantification of the emissions is a very useful tool for verifying the modeling and mass balance as well as for validation initiatives done for lowering the emissions of methane and nitrous oxide. One approach to performing such measurements is the tracer dilution method (Galle et al. 2001, Scheutz et al. 2011), where the exact location of the source is located and a tracer gas is released at this source location at a known flow. The ratio of downwind concentrations of the tracer gas and the methane and nitrous oxide gives the emissions rates of the greenhouse gases. This tracer dilution method can be performed using both stationary and mobile measurements and in both cases, real-time measurements of both tracer and quantified gas are required, placing high demands on the analytical detection method. To perform the methane and nitrous oxide measurements, two robust instruments capable of real-time measurements were used, based on cavity ring-down spectroscopy and operating in the near-infrared spectral region. One instrument measured the methane and tracer gas concentrations while another measured the nitrous oxide concentration. We present the performance of these instruments at different waste treatment facilities (waste water treatment plants, composting facilities, sludge mineralization beds, anaerobic digesters and landfills) in Denmark, and discuss the strengths and limitations of the method of the method for quantifying methane and nitrous oxide emissions from the different sources. Furthermore, we have measured the methane emissions from 10 landfills with emission rates ranging from 5 to 135 kg/h depending on the age, state, content and aftercare of the landfill. In addition, we have studied 3 waste water treatment plants, and found nitrous oxide emission of 200 to 700 g/h from the aeration tanks and a total methane emission ranging from 2 to 15 kg/h, with the primary emission coming from the sludge treatment. References Galle, B., Samuelsson, J., Svensson, B.H., and Börjesson, G. (2001). Measurements of methane emissions from landfills using a time correlation tracer method based on FTIR absorption spectroscopy. Environmental Science & Technology 35 (1), 21-25 Scheutz, C., Samuelsson, J., Fredenslund, A. M., and Kjeldsen, P. (2011). Quantification of multiple methane emission sources at landfills using a double tracer technique. Waste Management, 31(5), 1009-17 Solomon, S., D. Qin, M. Manning, R.B. Alley, T. Berntsen, N.L. Bindoff, Z. Chen, A. Chidthaisong, J.M. Gregory, G.C. Hegerl, M. Heimann, B. Hewitson, B.J. Hoskins, F. Joos, J. Jouzel, V. Kattsov, U. Lohmann, T.Matsuno, M. Molina, N. Nicholls, J.Overpeck, G. Raga, V. Ramaswamy, J. Ren, M. Rusticucci, R. Somerville, T.F. Stocker, P. Whetton, R.A.Wood and D. Wratt, 2007: Technical Summary. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

  19. Estimation of methane emission rate changes using age-defined waste in a landfill site.

    PubMed

    Ishii, Kazuei; Furuichi, Toru

    2013-09-01

    Long term methane emissions from landfill sites are often predicted by first-order decay (FOD) models, in which the default coefficients of the methane generation potential and the methane generation rate given by the Intergovernmental Panel on Climate Change (IPCC) are usually used. However, previous studies have demonstrated the large uncertainty in these coefficients because they are derived from a calibration procedure under ideal steady-state conditions, not actual landfill site conditions. In this study, the coefficients in the FOD model were estimated by a new approach to predict more precise long term methane generation by considering region-specific conditions. In the new approach, age-defined waste samples, which had been under the actual landfill site conditions, were collected in Hokkaido, Japan (in cold region), and the time series data on the age-defined waste sample's methane generation potential was used to estimate the coefficients in the FOD model. The degradation coefficients were 0.0501/y and 0.0621/y for paper and food waste, and the methane generation potentials were 214.4 mL/g-wet waste and 126.7 mL/g-wet waste for paper and food waste, respectively. These coefficients were compared with the default coefficients given by the IPCC. Although the degradation coefficient for food waste was smaller than the default value, the other coefficients were within the range of the default coefficients. With these new coefficients to calculate methane generation, the long term methane emissions from the landfill site was estimated at 1.35×10(4)m(3)-CH(4), which corresponds to approximately 2.53% of the total carbon dioxide emissions in the city (5.34×10(5)t-CO(2)/y). PMID:23786989

  20. GAS CHROMATOGRAPH-BASED SYSTEM FOR MEASURING THE METHANE FRACTION OF DIESEL ENGINE HYDROCARBON EMISSIONS

    EPA Science Inventory

    An instrument has been developed (termed the 'methane analytical system') enabling diesel methane emissions to be quatified separately from total unburned hydrocarbon emissions. The instrument employed gas chromatographic principles whereby a molecular sieve column operating isot...

  1. Indian oil company joins efforts to reduce methane emissions

    NASA Astrophysics Data System (ADS)

    Kumar, Mohi

    The Oil and Natural Gas Corp, Ltd. (ONGC), headquartered in Dehradun, India, has joined seven U.S. and Canadian oil and natural gas companies as a partner in a U.S. Environmental Protection Agency program to reduce greenhouse gas emissions. EPA's Natural Gas STAR International Program aims to reduce methane emissions from the oil and natural gas sector while delivering more gas to markets around the world. With this partnership, ONGC agrees to implement emissions reduction practices and to submit annual reports on progress achieved; EPA agrees to assist ONGC with training technicians in new cost-effective technologies that will help achieve target emissions. The Natural Gas STAR International Program is administered under the Methane to Markets Partnership, a group of 20 countries and 600 companies across the globe that since 2004 has volunteered to cut methane emissions. More information on EPA's agreement with ONGC can be found at http://www.epa.gov/gasstar/index.htm; information about the Methane to Markets Partnership can be found at http://www.methanetomarkets.org.

  2. Methane emission by goats consuming different sources of condensed tannins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Twenty-four yearling Boer x Spanish wethers (7/8 Boer; initial body weight [BW] of 37.5 plus/minus 0.91 kg) were used to assess effects of different condensed tannin (CT) sources on methane emission. Diets were Kobe lespedeza (Lespedeza striata; K), K plus quebracho providing CT at 5% of dry matter...

  3. Methane emissions to the atmosphere through aquatic plants

    NASA Technical Reports Server (NTRS)

    Sebacher, D. I.; Harriss, R. C.; Bartlett, K. B.

    1985-01-01

    The movement of methane (CH4) from anaerobic sediments through the leaves, stems, and flowers of aquatic plants and into the atmosphere was found to provide a significant pathway for the emission of CH4 from the aquatic substrates of flooded wetlands. Methane concentrations well above the surrounding ambient air levels were found in the mesophyll of 16 varies of aquatic plants and are attributed to transpiration, diffusion, and pressure-induced flow of gaseous CH4 from the roots when they are embedded in CH4-saturated anaerobic sediments. Methane emissions from the emergent parts of aquatic plants were measured using floating chamber techniques and by enclosing the plants in polyethylene bags of known volume. Concentration changes were monitored in the trapped air using syringes and gas chromatographic techniques. Vertical profiles of dissolved CH4 in sediment pore water surrounding the aquatic plants' rhizomes were obtained using an interstitial sampling technique. Methane emissions from the aquatic plants studied varied from 14.8 mg CH4/d to levels too low to be detectable. Rooted and unrooted freshwater aquatic plants were studied as well as saltwater and brackish water plants. Included in the experiment is detailed set of measurements on CH4 emissions from the common cattail (Typha latifolia). This paper illustrates that aquatic plants play an important gas exchange role in the C cycle between wetlands and the atmosphere.

  4. ESTIMATING METHANE EMISSION AND OXIDATION FROM TWO TEMPORARY

    E-print Network

    Paris-Sud XI, Université de

    ESTIMATING METHANE EMISSION AND OXIDATION FROM TWO TEMPORARY COVERS ON LANDFILLED MBT TREATED WASTE using old municipal solid waste material (Huber-Humer & al, 2007, 2008). Another result of these studies layer waste gas composition were measured on two French MBT plants with aerobic pre-treatment process

  5. Characteristics of methane emission from different vegetations on a wetland

    Microsoft Academic Search

    Atsuko Sugimoto; Noboru Fujita

    1997-01-01

    Methane flux was observed on a floating mat of temperate sphagnum bog, Mizorogaike, Japan, during the period April to October in 1993, to investigate the factors controlling CH4 emission, especially differences in vegetation and variation of water level. Comparing the CH4 flux among reed dominant site, marsh trefoil (a broad-leaved perennial aquatic herb) dominant site and sphagnum dominant site, the

  6. Carbon dioxide and methane emission dynamics in central London (UK)

    NASA Astrophysics Data System (ADS)

    Helfter, Carole; Nemitz, Eiko; Barlow, Janet F.; Wood, Curtis R.

    2013-04-01

    London, with a population of 8.2 million, is the largest city in Europe. It is heavily built-up (typically 8% vegetation cover within the central boroughs) and boasts some of the busiest arteries in Europe despite efforts to reduce traffic in the city centre with the introduction of a congestion charging scheme in 2007. We report on two substantial pollution monitoring efforts in the heart of London between October 2006 and present. Fluxes of carbon dioxide (CO2) and water (H2O) were measured continuously by eddy-covariance in central London from October 2006 until May 2008 from a 190 m telecommunication tower (BT tower; 51° 31' 17.4'' N 0° 8' 20.04'' W). The eddy-covariance system consisted of a Gill R3-50 ultrasonic anemometer operated at 20 Hz and a LI-COR 6262 infrared gas analyser. Air was sampled 0.3 m below the sensor head of the ultrasonic anemometer - which was itself mounted on a 3 m mast to the top of a 15 m lattice tower situated on the roof of the tower (instrument head at 190 m above street level) - and pulled down 45 m of 12.7 mm OD Teflon tubing. In addition, meteorological variables (temperature, relative humidity, pressure, precipitation, wind speed and direction) were also measured with a multi-sensor (Weather Transmitter WXT510, Vaisala). Eddy-covariance measurements at the BT tower location were reinstated in July 2011 and include methane (CH4), CO2 and H2O concentrations measured by a Picarro fast methane analyser (G2301-f). CO2 emissions were found to be mainly controlled by fossil fuel combustion (e.g. traffic, commercial and domestic heating). Diurnal averages of CO2 fluxes were found to be highly correlated to traffic. However changes in heating-related natural gas consumption and, to a lesser extent, photosynthetic activity in two large city centre green spaces (Hyde Park and Regent's Park) explained the seasonal variability. Annual estimates of net exchange of CO2 obtained by eddy-covariance agreed well with up-scaled data from the UK National Atmospheric Emissions Inventory (NAEI) for the flux footprint estimated using a simple Kormann-Meixner model. Methane emissions from central London exhibit diurnal trends both for concentrations and fluxes. The former is consistent with cycles of growth and shrinkage of the urban boundary layer. Methane fluxes are strongly correlated with those of carbon dioxide. Work is ongoing to establish to what extent the diurnal cycles reflect dynamic changes in ground sources (emissions from road traffic, commercial/ domestic heating, variations in flux footprint) and to what extent they are affected by transport efficiency between street level and the top of the tower and storage in between, given the high measurement height.

  7. Estimating global and North American methane emissions with high spatial resolution using GOSAT satellite data

    NASA Astrophysics Data System (ADS)

    Turner, A. J.; Jacob, D. J.; Wecht, K. J.; Maasakkers, J. D.; Lundgren, E.; Andrews, A. E.; Biraud, S. C.; Boesch, H.; Bowman, K. W.; Deutscher, N. M.; Dubey, M. K.; Griffith, D. W. T.; Hase, F.; Kuze, A.; Notholt, J.; Ohyama, H.; Parker, R.; Payne, V. H.; Sussmann, R.; Sweeney, C.; Velazco, V. A.; Warneke, T.; Wennberg, P. O.; Wunch, D.

    2015-06-01

    We use 2009-2011 space-borne methane observations from the Greenhouse Gases Observing SATellite (GOSAT) to estimate global and North American methane emissions with 4° × 5° and up to 50 km × 50 km spatial resolution, respectively. GEOS-Chem and GOSAT data are first evaluated with atmospheric methane observations from surface and tower networks (NOAA/ESRL, TCCON) and aircraft (NOAA/ESRL, HIPPO), using the GEOS-Chem chemical transport model as a platform to facilitate comparison of GOSAT with in situ data. This identifies a high-latitude bias between the GOSAT data and GEOS-Chem that we correct via quadratic regression. Our global adjoint-based inversion yields a total methane source of 539 Tg a-1 with some important regional corrections to the EDGARv4.2 inventory used as a prior. Results serve as dynamic boundary conditions for an analytical inversion of North American methane emissions using radial basis functions to achieve high resolution of large sources and provide error characterization. We infer a US anthropogenic methane source of 40.2-42.7 Tg a-1, as compared to 24.9-27.0 Tg a-1 in the EDGAR and EPA bottom-up inventories, and 30.0-44.5 Tg a-1 in recent inverse studies. Our estimate is supported by independent surface and aircraft data and by previous inverse studies for California. We find that the emissions are highest in the southern-central US, the Central Valley of California, and Florida wetlands; large isolated point sources such as the US Four Corners also contribute. Using prior information on source locations, we attribute 29-44 % of US anthropogenic methane emissions to livestock, 22-31 % to oil/gas, 20 % to landfills/wastewater, and 11-15 % to coal. Wetlands contribute an additional 9.0-10.1 Tg a-1.

  8. Relationship among methane emission, ammonia emission and selected animal performance measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Enteric methane (CH4) emission and subsequent CH4 emission from manure of ruminant livestock are major contributors to anthropogenic greenhouse gases (GHG) emission in many countries. Similarly, livestock manure is an important source of undesirable atmospheric ammonia (NH3). Identifying and quantif...

  9. Quantifying Methane Emissions from Shale Gas Wells in Pennsylvania

    NASA Astrophysics Data System (ADS)

    Caulton, D.; Shepson, P.; Cambaliza, M. L.; Sparks, J. P.; Santoro, R.; Sweeney, C.; Davis, K. J.; Lauvaux, T.; Howarth, R.; Stirm, B.; Sarmiento, D.; Belmecheri, S.

    2012-12-01

    A major question facing assessment of greenhouse gas sources and sinks is the impact of shale gas drilling operations on methane emissions. Estimating fugitive methane emissions is a challenge because of the temporal variability of emissions and because of the inaccessibility of the emission plumes using traditional measurement techniques. In June of 2012 we conducted flights over shale gas wells in the Marcellus Formation near Washington, PA using Purdue University's Airborne Laboratory for Atmospheric Research (ALAR) which is equipped with a 0.5 Hz Picarro CO2/CH4/H2O analyzer and a programmable flask package provided by NOAA. We calculated methane fluxes for two wells, here denoted as Well Delta and Well Tau, via the aircraft-based mass balance technique that has been previously described by Mays et al. (2009). Briefly, horizontal transects perpendicular to the prevailing wind direction were flown at different altitudes up to the top of the convective boundary layer downwind of a source. The data were interpolated to create a complete 2-d snapshot of methane concentrations derived from the source. By multiplying the background subtracted concentration by the perpendicular component of the horizontal winds and integrating over the plume dimensions the flux can be obtained. During the experiment elevated background concentrations were observed in the southwestern corner of Pennsylvania during the morning shown in Figure 1. We mapped the extent of this elevated methane region and used it to obtain an estimate of the regional enhancement of methane. Here we present our preliminary analysis, and results. Well Delta was sampled in three separate experiments; however, it was close to several other active wells. When the signal was too diffuse to obtain separate well specific fluxes, the flux for the entire area was averaged over the number of wells that may have contributed. Well Tau was sampled during one experiment and a nearby relatively large methane emission source was observed during the experiment. In flight investigation revealed the source of this enhancement to be from a coal mine, for which a flux estimate was made.igure 1. CH4 distribution over southwestern Pennsylvania on 6/21/12 between 9:00 and 10:30 EDT plotted in Google Earth.

  10. Global Scale Methane Emissions from On-Site Wastewater Management

    NASA Astrophysics Data System (ADS)

    Reid, M. C.; Guan, K.; Mauzerall, D. L.

    2013-12-01

    Pit latrines and other on-site sanitation methods are important forms of wastewater management at the global scale, providing hygienic and low-cost sanitation for more than 1.7 billion people in developing and middle-income regions. Latrines have also been identified as major sources of the greenhouse gas methane (CH4) from the anaerobic decomposition of organic waste in pits. Understanding the greenhouse gas footprint of different wastewater systems is essential for sustainable water resource development and management. Despite this importance, CH4 emissions from decentralized wastewater treatment have received little attention in the scientific literature, and the rough calculations underlying government inventories and integrated assessment models do not accurately capture variations in emissions within and between countries. In this study, we improve upon earlier efforts and develop the first spatially explicit approach to quantifying latrine CH4 emissions, combining a high-resolution geospatial analysis of population, urbanization, and water table (as an indicator of anaerobic decomposition pathways) with CH4 emissions factors from the 2006 IPCC Guidelines for National Greenhouse Gas Inventories. Country-level health and sanitation surveys were used to determine latrine utilization in 2000 and predict usage in 2015. 18 representative countries in Asia, Africa, and Latin America were selected for this analysis to illustrate regional variations in CH4 emissions and to include the greatest emitting nations. Our analysis confirms that pit latrines are a globally significant anthropogenic CH4 source, emitting 4.7 Tg CH4 yr-1 in the countries considered here. This total is projected to decrease ~25% by 2015, however, driven largely by rapid urbanization in China and decreased reliance on latrines in favor of flush toilets. India has the greatest potential for large growth in emissions in the post-2015 period, since public health campaigns to end open defecation, which is currently practiced by more than 600 million people in India, will rely heavily on latrines. Our results emphasize that decisions regarding water and sanitation can significantly influence anthropogenic CH4 emissions, and that discussions around sustainable water resources policy should give full consideration to the greenhouse gas impacts of decentralized sanitation systems like latrines. We conclude with a brief discussion of household biogas and composting toilets as CH4 mitigation options which also allow for harvesting of renewable energy and/or nutrients from wastewater.

  11. Measurement and prediction of enteric methane emission

    Microsoft Academic Search

    Veerasamy Sejian; Rattan Lal; Jeffrey Lakritz; Thaddeus Ezeji

    2011-01-01

    The greenhouse gas (GHG) emissions from the agricultural sector account for about 25.5% of total global anthropogenic emission.\\u000a While CO2 receives the most attention as a factor relative to global warming, CH4, N2O and chlorofluorocarbons (CFCs) also cause significant radiative forcing. With the relative global warming potential of 25\\u000a compared with CO2, CH4 is one of the most important GHGs.

  12. Estimation of methane and nitrous oxide emissions from Indian livestock.

    PubMed

    Patra, Amlan K

    2012-10-26

    Greenhouse gas (GHG; methane and nitrous oxide) emissions from enteric fermentation and manure management of Indian livestock were estimated from the last two Indian livestock census datasets (2003 and 2007) using IPCC Tier 2 (2006) guidelines. The total annual GHG emissions from Indian livestock increased in 2007 compared to the year 2003 with an annual growth rate of 1.52% over this period. The contributions of GHG by dairy cattle, non-dairy cattle, buffaloes, goats, sheep and other animals (yak, mithun, horse, donkeys, pigs and poultry) were 30.52, 24.0, 37.7, 4.34, 2.09 and 3.52%, respectively, in 2007. Enteric fermentation was the major source of methane, accounting for 89.2% of the total GHG emissions, followed by manure methane (9.49%). Nitrous oxide emissions accounted for 1.34%. GHG emissions (CO(2)-eq. per kg of fat and protein corrected milk (FPCM)) by female animals were considerably lower for crossbred cows (1161 g), followed by buffaloes (1332 g) and goats (2699 g), and were the highest for indigenous cattle (3261 g) in 2007. There was a decreasing trend in GHG emissions (-1.82% annual growth rate) in relation to milk production from 2003 to 2007 (1818 g and 1689 g CO(2)-eq. per kg FPCM in 2003 and 2007, respectively). This study revealed that GHG emissions (total as well as per unit of products) from dairy and other categories of livestock populations could be reduced substantially through proper dairy herd management without compromising animal production. In conclusion, although the total GHG emissions from Indian livestock increased in 2007, there was a decreasing trend in GHG production per kg of milk production or animal products. PMID:22898933

  13. Reconciling Airborne Basin Scale Methane Flux Estimates with Ground Based Quantification of Methane and VOC Emissions from Well Pads.

    NASA Astrophysics Data System (ADS)

    Murphy, S. M.; Field, R. A.; Soltis, J.; Snare, D.; Edie, R.

    2014-12-01

    Data was collected in the Pinedale Anticline and Jonah Fields in Wyoming, both of which are among the top ten wet gas fields in the USA in terms of production. We present an estimate of total methane flux from these two gas fields derived from airborne measurements and relate this flux to ground-based measurements of methane leakage from ~50 individual well pads within the fields. The fraction of basin-wide methane flux that can be accounted for by leaks from individual well pads will be discussed as well as the fraction of methane production that is leaked. We outline the difficulties and strengths of the EPA-developed methodology, referred to as Geospatial Measurement of Air Pollution Remote Emission Quantification, that was used to determined individual well-pad leakage rates using detailed wind measurements without tracers. Often the ratio of VOC:methane concentrations is combined with a known methane flux to determine VOC emission rates. In this study, we measured the flux of volatile organic compounds (VOC) independently of methane by using a proton-transfer-reactor time-of-flight mass-spectrometer and rapid 3-D wind measurements. This allows us to distinguish sources that emit primarily VOC, those that emit a mix of VOC and methane, and those that emit primarily methane. The relationship of VOC and methane fluxes from a number of different oil and gas operations will be discussed.

  14. Methane fugitive emissions quantification using the novel 'plume camera' (spatial correlation) method

    NASA Astrophysics Data System (ADS)

    Crosson, E.; Rella, C.

    2012-12-01

    Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Given that the global warming potential of methane is many times greater than that of carbon dioxide, the importance of quantifying methane emissions becomes clear. The rapidly increasing reliance on shale gas (or other unconventional sources) is only intensifying the interest in fugitive methane releases. Natural gas (which is predominantly methane) is an attractive energy source, as it emits 40% less carbon dioxide per Joule of energy generated than coal. However, if just a small percentage of the natural gas consumed is lost due to fugitive emissions during production, processing, or transport, this global warming benefit is lost (Howarth et al. 2012). It is therefore imperative, as production of natural gas increases, that the fugitive emissions of methane are quantified accurately. Traditional direct measurement techniques often involve physical access of the leak itself to quantify the emissions rate, and are generally require painstaking effort to first find the leak and then quantify the emissions rate. With over half a million natural gas producing wells in the U.S. (U.S. Energy Information Administration), not including the associated processing, storage, and transport facilities, and with each facility having hundreds or even thousands of fittings that can potentially leak, the need is clear to develop methodologies that can provide a rapid and accurate assessment of the total emissions rate on a per-well head basis. In this paper we present a novel method for emissions quantification which uses a 'plume camera' with three 'pixels' to quantify emissions using direct measurements of methane concentration in the downwind plume. By analyzing the spatial correlation between the pixels, the spatial extent of the instantaneous plume can be inferred. This information, when combined with the wind speed through the measurement plane, provides a direct measurement of the emission rate. One example of this method is shown in Fig. 1. This method is simple to deploy, does not require an accurate model of atmospheric transport or knowledge of the distance to the emission source or its spatial distribution. Accurate measurements of the emissions can be made with just a few minutes of data collection. Results of controlled release methane experiments are presented, and the strengths and limitations of the methodology are discussed. REFERENCES R. Howarth, R. Santoro, and A. Ingraffea (2011): "Methane and the greenhouse-gas footprint of natural gas from shale formations," Climatic Change 106, 679 - 690. Fig 1: Spatial correlation analysis for two measurement points (or pixels) distributed vertically (A and B) or horizontally (A and C), for measurements at a distance of 21 meters from a methane point source of 650 sccm. The emission rate recovered from this analysis was 496 ± 160 sccm of CH4. The total measurement time was 30 minutes.

  15. Methane from the Tropospheric Emission Spectrometer (TES)

    NASA Technical Reports Server (NTRS)

    Payne, Vivienne; Worden, John; Kulawik, Susan; Frankenberg, Christian; Bowman, Kevin; Wecht, Kevin

    2012-01-01

    TES V5 CH4 captures latitudinal gradients, regional variability and interannual variation in the free troposphere. V5 joint retrievals offer improved sensitivity to lower troposphere. Time series extends from 2004 to present. V5 reprocessing in progress. Upper tropospheric bias. Mitigated by N2O correction. Appears largely spatially uniform, so can be corrected. How to relate free-tropospheric values to surface emissions.

  16. Retrieval of Methane Source Strengths in Europe Using a Simple Modeling Approach to Assess the Potential of Spaceborne Lidar Observations

    NASA Technical Reports Server (NTRS)

    Weaver, C.; Kiemle, C.; Kawa, S. R.; Aalto, T.; Necki, J.; Steinbacher, M.; Arduini, J.; Apadula, F.; Berkhout, H.; Hatakka, J.

    2014-01-01

    We investigate the sensitivity of future spaceborne lidar measurements to changes in surface methane emissions. We use surface methane observations from nine European ground stations and a Lagrangian transport model to infer surface methane emissions for 2010. Our inversion shows the strongest emissions from the Netherlands, the coal mines in Upper Silesia, Poland, and wetlands in southern Finland. The simulated methane surface concentrations capture at least half of the daily variability in the observations, suggesting that the transport model is correctly simulating the regional transport pathways over Europe. With this tool we can test whether proposed methane lidar instruments will be sensitive to changes in surface emissions. We show that future lidar instruments should be able to detect a 50% reduction in methane emissions from the Netherlands and Germany, at least during summer.

  17. Retrieval of methane source strengths in Europe using a simple modeling approach to assess the potential of spaceborne lidar observations

    NASA Astrophysics Data System (ADS)

    Weaver, C.; Kiemle, C.; Kawa, S. R.; Aalto, T.; Necki, J.; Steinbacher, M.; Arduini, J.; Apadula, F.; Berkhout, H.; Hatakka, J.

    2014-03-01

    We investigate the sensitivity of future spaceborne lidar measurements to changes in surface methane emissions. We use surface methane observations from nine European ground stations and a Lagrangian transport model to infer surface methane emissions for 2010. Our inversion shows the strongest emissions from the Netherlands, the coal mines in Upper Silesia, Poland, and wetlands in southern Finland. The simulated methane surface concentrations capture at least half of the daily variability in the observations, suggesting that the transport model is correctly simulating the regional transport pathways over Europe. With this tool we can test whether proposed methane lidar instruments will be sensitive to changes in surface emissions. We show that future lidar instruments should be able to detect a 50% reduction in methane emissions from the Netherlands and Germany, at least during summer.

  18. Environmental factors controlling methane emissions from peatlands in northern Minnesota

    NASA Technical Reports Server (NTRS)

    Dise, Nancy B.; Gorham, Eville; Verry, Elon S.

    1993-01-01

    The environmental factors affecting the emission of methane from peatlands were investigated by correlating CH4 emission data for two years, obtained from five different peatland ecosystems in northern Minnesota, with peat temperature, water table position, and degree of peat humification. The relationship obtained between the CH4 flux and these factors was compared to results from a field manipulation experiment in which the water table was artificially raised in three experimental plots within the driest peatland. It was found that peat temperature, water table position, and degree of peat humification explained 91 percent of the variance in log CH4 flux, successfully predicted annual CH4 emission from individual wetlands, and predicted the change in flux due to the water table manipulation. Raising the water table in the bog corrals by an average of 6 cm in autumn 1989 and 10 cm in summer 1990 increased CH4 emission by 2.5 and 2.2 times, respectively.

  19. Compositional modeling of enhanced coalbed methane recovery

    NASA Astrophysics Data System (ADS)

    Manik, Julio

    A development and validation of a three-dimensional, two-phase, dual porosity, fully implicit, compositional coalbed simulator is presented. A multicomponent sorption equilibria using a thermodynamically consistent ideal adsorbed solution theory and Peng-Robinson equation of state is implemented to the simulator using a non-equilibrium sorption formulation. The simulator is used to model the nitrogen and carbon dioxide injections in the enhanced coalbed methane recovery which involves gas component and fluid phase appearances and disappearances. The effects of absolute permeability, vertical heterogeneity, lateral heterogeneity, and sorption time constant to the methane recovery performance are studied. The performances of nitrogen and carbon dioxide injections in the enhanced coalbed methane recovery are compared. The roles of the injected gas composition, delayed injection, well spacing, cyclic injection/production, and intermittent gas injection to the methane recovery performance are studied.

  20. Emissions of methane from offshore oil and gas platforms in Southeast Asia

    NASA Astrophysics Data System (ADS)

    Nara, Hideki; Tanimoto, Hiroshi; Tohjima, Yasunori; Mukai, Hitoshi; Nojiri, Yukihiro; Machida, Toshinobu

    2014-09-01

    Methane is a substantial contributor to climate change. It also contributes to maintaining the background levels of tropospheric ozone. Among a variety of CH4 sources, current estimates suggest that CH4 emissions from oil and gas processes account for approximately 20% of worldwide anthropogenic emissions. Here, we report on observational evidence of CH4 emissions from offshore oil and gas platforms in Southeast Asia, detected by a highly time-resolved spectroscopic monitoring technique deployed onboard cargo ships of opportunity. We often encountered CH4 plumes originating from operational flaring/venting and fugitive emissions off the coast of the Malay Peninsula and Borneo. Using night-light imagery from satellites, we discovered more offshore platforms in this region than are accounted for in the emission inventory. Our results demonstrate that current knowledge regarding CH4 emissions from offshore platforms in Southeast Asia has considerable uncertainty and therefore, emission inventories used for modeling and assessment need to be re-examined.

  1. In-Situ Quantification of Microbial Processes Controlling Methane Emissions From Rice Plants

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Methane is an important greenhouse gas contributing to global warming. Among other sources, rice (paddy) soils represent a major nonpoint source of biogenic methane. In flooded paddy soils methane is produced under anaerobic conditions. Conversely, methanotrophic microorganisms oxidize methane to carbon dioxide in the root zone of rice plants, thus reducing overall methane emissions to the atmosphere. We present a novel combination of methods to quantify methanogenesis and methane oxidation in paddy soils and to link methane turnover to net emissions of rice plants. To quantify methane turnover in the presence of high methane background concentrations, small-scale push-pull tests (PPTs) were conducted in paddy soils using stable isotope-labeled substrates. Deuterated acetate and 13-C bicarbonate were employed to discern and quantify acetoclastic and hydrogenotrophic methanogenesis, while 13-C methane was employed to quantify methane oxidation. During 2.5 hr-long PPTs, 140 mL of a test solution containing labeled substrates and nonreactive tracers (Ar, Br-) was injected into paddy soils of potted rice plants. After a short rest period, 480 mL of test solution/pore water mixture was extracted from the same location. Methane turnover was then computed from extraction-phase breakthrough curves of substrates and/or products, and nonreactive tracers. To link methane turnover to net emissions, methane emissions from paddy soils and rice plants were individually determined immediately preceding PPTs using static flux chambers. We will present results of a series of experiments conducted in four different potted rice plants. Preliminary results indicate substantial variability in methane turnover and net emission between different rice plants. The employed combination of methods appears to provide a robust means to quantitatively link methane turnover in paddy soils to net emissions from rice plants.

  2. Geogenic methane emissions in central and eastern Romania

    NASA Astrophysics Data System (ADS)

    Baciu, Calin; Ionescu, Artur; Pop, Cristian; Etiope, Giuseppe

    2015-04-01

    Keywords: methane, greenhouse gases, geogenic emissions, Romania Relatively often, the hydrocarbon reservoirs are not completely sealed, thus permitting the channeling to the surface of various amounts of gas, mainly consisting of methane and homologues. When important volumes of gas are released, features as mud volcanoes and everlasting fires may occur. When the gas amount is low, the degassing can be revealed by instrumental means only. The gas seeps may be useful as indicators in the hydrocarbon exploration, but may be also hazardous when gas is accumulating in closed spaces. Additionally, the geogenic methane degassing represents an important contribution to the atmospheric budget of greenhouse gases. Romania is one of the European important hydrocarbon producers, with oil and gas deposits in different geologic and tectonic contexts. As well, the frequency of gas emitting features and seepage areas is high. Some relevant hydrocarbon-prone areas from Romania, namely the Neogene Transylvanian Basin, the Carpathian Foredeep, and the Moldavian Platform, are comparatively analysed within the current work from the point of view of methane emissions. The Carpathian Foredeep hosts the most impressive mud volcanoes and everlasting fires in Romania, classified among the biggest in Europe. The degassing area also extends in the Carpathian Flysch zone. The Transylvanian Basin hosts numerous gas-bearing structures, mainly of biogenic origin. With some exceptions, the methane-emitting features are small, releasing relatively low amounts of gas. A relatively high number of seeps have been described on the Moldavian Platform, although no commercial hydrocarbon reservoirs have been identified. The seeps are small, and they are releasing low amounts of methane. However, it is important to notice that the investigated zone partly corresponds to an area of interest for shale gas, related to the deep-seated Silurian shales. For all mentioned areas, the main geochemical characteristics of gas, and the total output have been estimated. Based on the results obtained, an interactive database of the known gas seeps in Romania has been built, that is freely available on the Internet: http://hydrocarbonseepage.blogspot.ro. Acknowledgments: The present work was financially supported by a grant of the Romanian National Authority for Scientific Research, CCCDI - UEFISCDI, project number PN-II-ID-PCE-2011-3-0537.

  3. Mars methane emission and transport scenarios using the GEM-Mars GCM

    NASA Astrophysics Data System (ADS)

    Neary, Lori; Daerden, Frank; Kaminski, J. W.; McConnell, J. C.

    2010-05-01

    The observation of methane (Formisano et al., 2004; Krasnopolsky et al., 2004; Mumma et al., 2009) in the Martian atmosphere has raised questions about its source and origin as well as its chemical behaviour. The photochemical lifetime of methane is on the order of several hundred years which would give a well-mixed, uniform distribution but measurements suggest locally enhanced "plumes". The GEM-Mars three-dimensional global chemistry-climate model is used to investigate the possible emission rates and lifetime of methane. The model simulations have a horizontal resolution of 4x4 degrees with 101 vertical levels up to approximately 140 km. References Formisano, V., S. Atreya, T. Encrenaz, N. Ignatiev, and M. Giuranna (2004), Detection of Methane in the Atmosphere of Mars, Science 306, 1758 (2004). Krasnopolsky, V. A., J. P. Maillard, and T. C. Owen (2004), Icarus 172, 537. Mumma, M.J., G.L. Villanueva, R.E. Novak, T. Hewagama, B.P. Bonev, M.A. DiSanti, A.M. Mandell, and M.D. Smith (2009), Strong Release of Methane on Mars in Northern Summer 2003. Science, 2009. 323: p. 1041-1045.

  4. Methane Emissions from Semi-natural, Drained and Re-wetted Peatlands in Germany

    NASA Astrophysics Data System (ADS)

    Tiemeyer, B.; Bechtold, M.; Albiac Borraz, E.; Augustin, J.; Drösler, M.; Beetz, S.; Beyer, C.; Eickenscheidt, T.; Fiedler, S.; Förster, C.; Giebels, M.; Glatzel, S.; Heinichen, J.; Höper, H.; Leiber-Sauheitl, K.; Peichl-Brak, M.; Rosskopf, N.; Sommer, M.; Zeitz, J.; Freibauer, A.

    2014-12-01

    Drained peatlands contribute around 5% to the total German greenhouse gas emissions. While these areas are hotspots for carbon dioxide (CO2) and nitrous oxide (N2O) emissions, some re-wetted peatlands may emit large amounts of methane (CH4). To quantify the GHG emission reductions achieved by the re-wetting of peatlands, the reduced CO2 emissions and the potential CH4fluxes need to be balanced. We synthesized methane flux data from 14 peatlands with 122 sites. At each site, methane fluxes were measured for one to three years with static chambers. The sites comprise arable land, intensive and extensive grassland, forest and peat mining areas as well as semi-natural and re-wetted peatlands on both bog peat, fen peat and other soils rich in organic carbon. Besides the groundwater table we consider further potential drivers for the CH4fluxes such as soil properties (carbon, nitrogen, pH, and physical properties), climatic parameters, land use, and vegetation composition. Annual methane fluxes ranged from low uptake rates (around -1 g CH4-C m² a-1) to very high emissions (> 200 g CH4-C m² a-1). Intensively drained sites showed very low emissions, while for annual mean water levels higher than 5-10 cm below ground, elevated emissions of more than 20 g CH4-C may occur. At some re-wetted sites CH4 emissions of more than 100 g CH4-C m² a-1 were measured, which roughly equal the Global Warming Potential of the CO2-emissions from intensively drained agricultural sites. These high fluxes were probably caused by a combination of nutrient-rich conditions, the dieback of poorly adapted plants and a fast accumulation of organic sediments. However, this was the exception and not the rule even for very wet re-wetted sites. Achieving a model efficiency of 0.72 during cross-validation, a boosted regression tree (BRT) model was well able to describe logarithmic CH4-fluxes. Groundwater level, biotope type, soil nitrogen content, and ponding duration during summer were the most important controls. Combining the BRT model with soil, land use, and groundwater table maps as well as weather data, methane fluxes were upscaled for Germany.

  5. Underlying Ecosystem Methane Emissions Exceed Cattle-Derived Methane from Subtropical Lowland Pastures.

    NASA Astrophysics Data System (ADS)

    Chamberlain, S. D.; Sparks, J. P.

    2014-12-01

    Grazing cattle are a major methane (CH4) source from pasture ecosystems, however the underlying landscape is a potentially significant CH4 source that has received far less attention. Ecosystem surface emissions of CH4 are poorly quantified, vary widely across time and space, and are easily underestimated if emission hotspots or episodic fluxes are overlooked. We used static chambers, eddy covariance, and mobile cavity-ringdown spectrometry surveys to quantify spatially and temporally variable CH4 emissions from subtropical lowland pastures. We conclude emissions from soil and standing water are the dominant CH4 source, and cattle were responsible for only 13% of annual CH4emissions. The ecosystem emit 33.8 ± 2.2 g CH4 m-2 yr-1, however surface CH4 emissions were highly variable in both time and space. Seasonal flooding of pastures and low-lying landforms (canals, ditches, wetlands) drove high magnitude CH4 emissions. We observed large CH4 emissions from wetlands and, to a lesser extent, the entire landscape during the wet season. In contrast, during the dry season there was no appreciable CH4 accumulation in pastures when cattle were not present, and canals, which comprise 1.7% of the total land area, were responsible 97.7 % of dry season emissions. Ecosystem CH4 fluxes, measured by eddy covariance, varied seasonally and positively correlated to soil and air temperature, topsoil water content, and water table depth. Our work is the first to use mobile spectrometers to map biogenic CH4 emissions at the landscape scale, and demonstrates that soils and water are a strong pasture CH4 source that must be considered in addition to cattle emissions.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  7. Comparison of soil acetate concentrations and methane production, transport, and emission in two rice cultivars

    Microsoft Academic Search

    L. K. Sigren; G. T. Byrd; F. M. Fisher; R. L. Sass

    1997-01-01

    The amount of methane emitted from irrigated rice paddies is dependent on the variety of rice grown. In this study we examined two varieties of rice with differing methane emission rates to determine if the primary mechanism for these differences was related to transport processes or the rate of methane production. The cultivars used were Mars and Lemont, with 1994

  8. Production, oxidation, emission and consumption of methane by soils: A review

    Microsoft Academic Search

    Jean Le Mer; Pierre Roger

    2001-01-01

    Methane emission by soils results from antagonistic but correlated microbial activities. Methane is produced in the anaerobic zones of submerged soils by methanogens and is oxidised into CO2 by methanotrophs in the aerobic zones of wetland soils and in upland soils. Methanogens and methanotrophs are ubiquitous in soils where they remain viable under unfavourable conditions. Methane transfer from the soil

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  10. FARM-produced alcohol and methane model

    SciTech Connect

    Broder, J.D.; Waddell, E.L.

    1983-12-01

    TVA has developed a model called FARM that determines the effects of incorporating in alcohol plant and/or an anaerobic digester into farm production systems. The purposes of this model are to calculate an alcohol plant size and digester dimensions, calculate potential alcohol and methane yields, develop livestock rations with and without stillage, and provide yearly energy consumption and production figures.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  12. Measurements of methane emissions from natural gas gathering facilities and processing plants: measurement results.

    PubMed

    Mitchell, Austin L; Tkacik, Daniel S; Roscioli, Joseph R; Herndon, Scott C; Yacovitch, Tara I; Martinez, David M; Vaughn, Timothy L; Williams, Laurie L; Sullivan, Melissa R; Floerchinger, Cody; Omara, Mark; Subramanian, R; Zimmerle, Daniel; Marchese, Anthony J; Robinson, Allen L

    2015-03-01

    Facility-level methane emissions were measured at 114 gathering facilities and 16 processing plants in the United States natural gas system. At gathering facilities, the measured methane emission rates ranged from 0.7 to 700 kg per hour (kg/h) (0.6 to 600 standard cubic feet per minute (scfm)). Normalized emissions (as a % of total methane throughput) were less than 1% for 85 gathering facilities and 19 had normalized emissions less than 0.1%. The range of methane emissions rates for processing plants was 3 to 600 kg/h (3 to 524 scfm), corresponding to normalized methane emissions rates <1% in all cases. The distributions of methane emissions, particularly for gathering facilities, are skewed. For example, 30% of gathering facilities contribute 80% of the total emissions. Normalized emissions rates are negatively correlated with facility throughput. The variation in methane emissions also appears driven by differences between inlet and outlet pressure, as well as venting and leaking equipment. Substantial venting from liquids storage tanks was observed at 20% of gathering facilities. Emissions rates at these facilities were, on average, around four times the rates observed at similar facilities without substantial venting. PMID:25668106

  13. A 3D Microphysical Model of Titan's Methane Clouds

    Microsoft Academic Search

    Jiafang Xiao; C. Newman; A. Inada; M. Richardson

    2006-01-01

    A time-dependent idealized model for Titan's methane clouds is described. We use the newly developed TitanWRF multiscale model, run as a mesoscale model with periodic boundary conditions in the horizontal and with simple microphysics included. It calculates the amount of nitrogen dissolved in liquid methane, and the amount of methane condensed at a particular temperature and pressure based on recent

  14. A micrometeorological technique for detecting small differences in methane emissions from two groups of cattle

    NASA Astrophysics Data System (ADS)

    Laubach, Johannes; Grover, Samantha P. P.; Pinares-Patiño, Cesar S.; Molano, German

    2014-12-01

    Potential approaches for reducing enteric methane (CH4) emissions from cattle will require verification of their efficacy at the paddock scale. We designed a micrometeorological approach to compare emissions from two groups of grazing cattle. The approach consists of measuring line-averaged CH4 mole fractions upwind and downwind of each group and using a backward-Lagrangian stochastic model to compute CH4 emission rates from the observed mole fractions, in combination with turbulence statistics measured by a sonic anemometer. With careful screening for suitable wind conditions, a difference of 10% in group emission rates could be detected. This result was corroborated by simultaneous measurements of daily CH4 emissions from each animal with the sulfur hexafluoride (SF6) tracer-ratio technique.

  15. A GLOBAL METHANE EMISSIONS PROGRAM FOR LANDFILLS, COAL MINES, AND NATURAL GAS SYSTEMS

    EPA Science Inventory

    The paper gives the scope and methodology of EPA/AEERL's methane emissions studies and discloses data accumulated thus far in the program. Anthropogenic methane emissions are a principal focus in AEERL's global climate research program, including three major sources: municipal so...

  16. ESTIMATE OF METHANE EMISSIONS FROM THE U.S. NATURAL GAS INDUSTRY

    EPA Science Inventory

    Global methane from the fossil fuel industries have been poorly quantified and, in many cases, emissions are not well-known even at the country level. Historically, methane emissions from the U.S. gas industry have been based on sparse data, incorrect assumptions, or both. As a r...

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  18. 40 CFR Table W - 5 of Subpart W-Default Methane Emission Factors for Liquefied Natural Gas (LNG) Storage

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Methane Emission Factors for Liquefied Natural Gas (LNG) Storage W Table W...GREENHOUSE GAS REPORTING Petroleum and Natural Gas Systems Definitions. Pt...Methane Emission Factors for Liquefied Natural Gas (LNG) Storage LNG...

  19. 40 CFR Table W - 7 of Subpart W of Part 98-Default Methane Emission Factors for Natural Gas Distribution

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...98-Default Methane Emission Factors for Natural Gas Distribution W Table W Protection...GREENHOUSE GAS REPORTING Petroleum and Natural Gas Systems Definitions. Pt...Default Methane Emission Factors for Natural Gas Distribution Natural gas...

  20. 40 CFR Table W - 7 of Subpart W-Default Methane Emission Factors for Natural Gas Distribution

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...W-Default Methane Emission Factors for Natural Gas Distribution W Table W Protection...GREENHOUSE GAS REPORTING Petroleum and Natural Gas Systems Definitions. Pt...Default Methane Emission Factors for Natural Gas Distribution Natural gas...

  1. 40 CFR Table W - 7 of Subpart W of Part 98-Default Methane Emission Factors for Natural Gas Distribution

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...98-Default Methane Emission Factors for Natural Gas Distribution W Table W Protection...GREENHOUSE GAS REPORTING Petroleum and Natural Gas Systems Definitions. Pt...Default Methane Emission Factors for Natural Gas Distribution Natural gas...

  2. Methane Emissions from Leak and Loss Audits of Natural Gas Compressor Stations and Storage Facilities.

    PubMed

    Johnson, Derek R; Covington, April N; Clark, Nigel N

    2015-07-01

    As part of the Environmental Defense Fund's Barnett Coordinated Campaign, researchers completed leak and loss audits for methane emissions at three natural gas compressor stations and two natural gas storage facilities. Researchers employed microdilution high-volume sampling systems in conjunction with in situ methane analyzers, bag samples, and Fourier transform infrared analyzers for emissions rate quantification. All sites had a combined total methane emissions rate of 94.2 kg/h, yet only 12% of the emissions total resulted from leaks. Methane slip from exhausts represented 44% of the total emissions. Remaining methane emissions were attributed to losses from pneumatic actuators and controls, engine crankcases, compressor packing vents, wet seal vents, and slop tanks. Measured values were compared with those reported in literature. Exhaust methane emissions were lower than emissions factor estimates for engine exhausts, but when combined with crankcase emissions, measured values were 11.4% lower than predicted by AP-42 as applicable to emissions factors for four-stroke, lean-burn engines. Average measured wet seal emissions were 3.5 times higher than GRI values but 14 times lower than those reported by Allen et al. Reciprocating compressor packing vent emissions were 39 times higher than values reported by GRI, but about half of values reported by Allen et al. Though the data set was small, researchers have suggested a method to estimate site-wide emissions factors for those powered by four-stroke, lean-burn engines based on fuel consumption and site throughput. PMID:26148551

  3. Deploying Methane Bubble Traps at Varying Lake Depths to Validate Bubble Dissolution Models

    NASA Astrophysics Data System (ADS)

    Delwiche, K.; Scandella, B.; Juanes, R.; Ruppel, C. D.; Hemond, H.

    2013-12-01

    Methane is a potent greenhouse gas, and understanding environmental methane cycles is critical both to developing accurate estimates of current methane emission rates and to modeling how cycles may respond to climate change. While there are many natural sources of methane, bubbling from lake sediments, or ebullition, is considered an important emission pathway. Ebullition can transport methane directly to the atmosphere, bypassing potential chemical or biological degradation in the water column. Existing bubble models predict some methane dissolution from rising bubbles, though dissolution estimates depend on the particular equations chosen to parameterize bubble rise velocity and gas transfer rates. To test current bubble dissolution models we installed a series of bubble traps at multiple depths in Upper Mystic Lake near Boston, Massachusetts. Traps gathered bubbles continuously during the summer of 2013 and were periodically emptied for gas volume measurements and chemical composition analysis. The gathered trap data demonstrated that surface traps have a significantly reduced bubble volume and methane fraction when compared with lake-bottom traps. This difference allows us to quantify the amount of methane dissolved in the water column due to ebullition. Preliminary data suggest that dissolution from bubbles could account for approximately 5% of the previously observed hypolimnetic methane accumulation in Upper Mystic Lake. Bubble methane contents in surface traps are consistent with average bubble sizes in the 3-6 mm diameter range based on the bubble models of McGinnis et al, 2006, and suggest that on the order of 50% of methane released by ebullition in this lake is dissolved before reaching the atmosphere. Data also indicates that careful corrections may be needed to account for small amounts of potential gas losses associated with dissolution at the gas/water interface within the traps. Using the gathered data to understand bubble size distributions, calculate methane dissolution quantities, and to calibrate simultaneous sonar studies of ebullition (Scandella et al) will help us develop a detailed lake-wide methane budget. In turn, understanding how ebullition impacts lake-wide methane cycling can lead to better predictive models of lake methane emissions under different climate change scenarios.

  4. Infrared radiation models for atmospheric methane

    NASA Technical Reports Server (NTRS)

    Cess, R. D.; Kratz, D. P.; Caldwell, J.; Kim, S. J.

    1986-01-01

    Mutually consistent line-by-line, narrow-band and broad-band infrared radiation models are presented for methane, a potentially important anthropogenic trace gas within the atmosphere. Comparisons of the modeled band absorptances with existing laboratory data produce the best agreement when, within the band models, spurious band intensities are used which are consistent with the respective laboratory data sets, but which are not consistent with current knowledge concerning the intensity of the infrared fundamental band of methane. This emphasizes the need for improved laboratory band absorptance measurements. Since, when applied to atmospheric radiation calculations, the line-by-line model does not require the use of scaling approximations, the mutual consistency of the band models provides a means of appraising the accuracy of scaling procedures. It is shown that Curtis-Godson narrow-band and Chan-Tien broad-band scaling provide accurate means of accounting for atmospheric temperature and pressure variations.

  5. Methane emissions in the Arctic and sub-Arctic from a Bayesian atmospheric inversion

    NASA Astrophysics Data System (ADS)

    Thompson, Rona; Stohl, Andreas; Myhre, Cathrine Lund; Sasakawa, Motoki; Machida, Toshinobu; Aalto, Tuula; Dlugokencky, Edward; Worthy, Douglas

    2015-04-01

    Methane (CH4) is the second most important anthropogenic greenhouse gas after CO2. Globally, atmospheric CH4 concentrations have increased since direct measurements began, in the early 1980s, but then stabilized from the mid 1990s to the mid 2000s. Since 2006, the atmospheric CH4 growth rate has become positive again causing concern that it may be the response to climate feedbacks, especially in the Arctic, where there is a potential for a large release of CH4 to the atmosphere under warmer conditions. Such feedbacks include high latitude wetlands, permafrost and methane hydrates. Conversely, recent studies, suggest that this change is the result of a rise in wetland emissions of CH4 in the tropics and subtropics combined with a rise in fossil fuel emissions. We present CH4 emission estimates for the Arctic and sub-Arctic from 2007 to 2011 using atmospheric mole fraction observations in a Bayesian inversion framework. This framework is based on the Lagrangian Particle Dispersion model, FLEXPART, run with ECMWF meteorological analyses. Emissions were optimized monthly and on a spatial grid of variable resolution (from 1°×1° to 4°×4°). Background mixing ratios were found by coupling FLEXPART to output from the Eulerian chemistry transport model, TM5. We found evidence of a widespread release of CH4 corresponding to the onset of soil freezing. Furthermore, we find higher emissions in Northern Eurasia compared to the prior in both summer and winter.

  6. Methane emission from natural wetlands: Global distribution, area, and environmental characteristics of sources

    SciTech Connect

    Matthews, E.; Fung, I. (New York Goddard Institute for Space Studies, NY (USA))

    1987-03-01

    A global data base of wetlands at 1 degree resolution was developed from the integration of three independent global, digital sources: (1) vegetation, (2) soil properties and (3) fractional inundation in each 1 degree cell. The integration yielded a global distribution of wetland sites identified with in situ ecological and environmental characteristics. The wetland sites were classified into five major groups on the basis of environmental characteristics governing methane emissions. The global wetland area derived in this study is 5.3 trillion sq m, approximately twice the wetland area previously used in methane emission studies. Methane emission was calculated using methane fluxes for the major wetland groups, and simple assumptions about the duration of the methane production season. The annual methane emission from wetlands is about 110 Tg, well within the range of previous estimates. Tropical/subtropical peat-poor swamps from 20 degrees N to 30 degrees S account from 30% of the global wetland area and 25% of the total methane emission. About 60% of the total emission comes from peat-rich bogs concentrated from 50-70 degrees N, suggesting that the highly seasonal emission from these ecosystems is the major contributor to the large annual oscillations observed in atmospheric methane concentrations at these latitudes. 78 refs., 6 figs., 5 tabs.

  7. High-resolution methane emission estimates using surface measurements and the InTEM inversion system.

    NASA Astrophysics Data System (ADS)

    Connors, Sarah; Manning, Alistair; Robinson, Andrew; Riddick, Stuart; Forster, Grant; Oram, Dave; O'Doherty, Simon; Harris, Neil

    2015-04-01

    High quality GHG emission estimates will be required to successfully tackle climate change. There is a growing need for comparisons between emission estimates produced using bottom-up and top-down techniques at high spatial resolution. Here, a top-down inversion approach combining multi-year atmospheric measurements and an inversion model, InTEM, was used to estimate methane emissions for a region in the South East of the UK (~100 x 150 km). We present results covering a 2-year period (July 2012 - July 2014) in which atmospheric methane concentrations were recorded at 1 - 2 minute time-steps at four locations within the region of interest. Precise measurements were obtained using gas chromatography with flame ionisation detection (GC-FID) for all sites except one, which used a PICARRO Cavity Ring-Down Spectrometer (CRDS). These observations, along with the UK Met Office's Lagrangian particle dispersion model, NAME, were used within InTEM to produce the methane emission fields. We present results from both Bayesian and non-prior based inversion analysis at varying spatial resolutions, for annual, seasonal and monthly time frames. These results are compared with the UK National Atmospheric Emissions Inventory (NAEI) which is compiled using bottom-up methods and available at 1x1 km resolution. A thorough assessment of uncertainty is incorporated into this technique which is represented in the results. This project is part of the UK GAUGE campaign which aims to produce robust estimates of the UK GHG budget using new and existing measurement networks (e.g. the UK DECC GHG network) and modelling activities at a range of scales.

  8. Exploring the response of West Siberian wetland methane emissions to potential future changes in climate, vegetation, and soil microbial metabolism

    NASA Astrophysics Data System (ADS)

    Bohn, Theodore; Kaplan, Jed; Lettenmaier, Dennis

    2015-04-01

    Methane emissions from northern peatlands depend strongly on environmental conditions, wetland plant species assemblages (via root zone oxidation and plant-aided transport), and soil microbial behavior (via metabolic pathways). While the responses of wetland methane emissions to potential future climate change have been extensively explored, the effects of future changes in plant species and soil microbial metabolism are not as well studied. We ran the Variable Infiltration Capacity (VIC) land surface model over the West Siberian Lowland (WSL), with methane emissions parameters that vary spatially with dominant plant species, and forced with outputs from 32 CMIP5 models for the RCP4.5 scenario. We compared the effects of changes in climate and vegetation (in terms of both leaf area index and species abundances) on predicted wetland CH4 emissions for the period 2071-2100, relative to the period 1981-2010. We also explored possible acclimatization of soil microbial communities to these changes. We evaluated the effects of climate change, potential northward migration of plant species, and potential microbial acclimatization on end-of-century methane emissions over the WSL, in terms of both total annual emissions and the spatial distribution of emissions. Our results suggest that, while microbial acclimatization mitigates the effects of warmer temperatures, the northward migration of plant species enhances the response to warming (due to plant-aided transport), and additionally shifts the location of maximal emissions northward, where the possible release of ancient carbon with permafrost thaw is a concern. Our work indicates the importance of better constraining the responses of wetland plants and soil microbial communities to changes in climate as they are critical determinants of the region's future methane emissions.

  9. Divergent effects of drought on peatland methane emissions

    NASA Astrophysics Data System (ADS)

    Brown, M.; Humphreys, E.; Roulet, N. T.; Moore, T. R.; Lafleur, P.

    2013-12-01

    When the water table drops in peatlands, methane (CH4) emissions generally decrease though some episodic pulses have been noted. We measured CH4 fluxes using the eddy covariance method at the Mer Bleue bog in 2012 during a severe drought event and during a more normal summer in 2011. As the water table declined from 40 to 55 cm below the surface, large CH4 emissions led to seasonal maximum emissions of 25 to 40 mg CH4-C m-2 day -1, whereas below or above these depths, average fluxes remained at ~10 mg CH4-C m-2 day -1. We hypothesize that as the water table drops through this critical zone, the decrease in the volume of pore water leads to an increase in the partial pressure of CH4, a decrease in hydrostatic pressure and a degassing of stored CH4. Although the total CH4 emitted during the growing season with drought was less than during the previous wetter year, these pulses of CH4 emissions may be important in reducing year to year differences.

  10. Quantification of methane emission rates from coal mine ventilation shafts using airborne remote sensing data

    NASA Astrophysics Data System (ADS)

    Krings, T.; Gerilowski, K.; Buchwitz, M.; Hartmann, J.; Sachs, T.; Erzinger, J.; Burrows, J. P.; Bovensmann, H.

    2013-01-01

    The quantification of emissions of the greenhouse gas methane is essential for attributing the roles of anthropogenic activity and natural phenomena in global climate change. Our current measurement systems and networks, whilst having improved during the last decades, are deficient in many respects. For example, the emissions from localised and point sources such as landfills or fossil fuel exploration sites are not readily assessed. A tool developed to better understand point sources of the greenhouse gases carbon dioxide and methane is the optical remote sensing instrument MAMAP (Methane airborne MAPper), operated from aircraft. After a recent instrument modification, retrievals of the column-averaged dry air mole fractions for methane XCH4 (or for carbon dioxide XCO2) derived from MAMAP data have a precision of about 0.4% or better and thus can be used to infer emission rate estimates using an optimal estimation inverse Gaussian plume model or a simple integral approach. CH4 emissions from two coal mine ventilation shafts in western Germany surveyed during the AIRMETH 2011 measurement campaign are used as examples to demonstrate and assess the value of MAMAP data for quantifying CH4 from point sources. While the knowledge of the wind is an important input parameter in the retrieval of emissions from point sources and is generally extracted from models, additional information from a turbulence probe operated on-board the same aircraft was utilised to enhance the quality of the emission estimates. Although flight patterns were optimised for remote sensing measurements, data from an in situ analyser for CH4 were found to be in good agreement with retrieved dry columns of CH4 from MAMAP and could be used to investigate and refine underlying assumptions for the inversion procedures. With respect to the total emissions of the mine at the time of the overflight, the inferred emission rate of 50.4 kt CH4 yr-1 has a difference of less than 1% compared to officially reported values by the mine operators, while the uncertainty, which reflects variability of the sources and conditions as well as random and systematic errors, is about ±13.5%.

  11. Analysis of the atmospheric transport during MAGICS campaign and constraints on methane emissions from hydrates in Svalbard

    NASA Astrophysics Data System (ADS)

    Pisso, Ignacio; Myhre, Cathrine Lund; Platt, Stephen; Eckhardt, Sabine; Stohl, Andreas

    2015-04-01

    The MAGIC campaign, a collaboration between the MOCA and MAMM projects took place in Lapland and Svalbard during the summer of 2014. An extensive set of measurements was performed including airborne and ship-borne methane concentrations, complemented with the nearby monitoring site at Zeppelin mountain. In order to assess the atmospheric impact of emissions from seabed methane hydrates, a suite of atmospheric transport analysis tools based on the Lagrangian model FLEXPART was developed. We present a characterisation of the local and long range transport during the campaign applied to the estimate of oceanic emissions and discuss the uncertainties associated with the methodology.

  12. Detection of marine methane emissions with AVIRIS band ratios

    NASA Astrophysics Data System (ADS)

    Bradley, Eliza S.; Leifer, Ira; Roberts, Dar A.; Dennison, Philip E.; Washburn, Libe

    2011-05-01

    The relative source contributions of methane (CH4) have high uncertainty, creating a need for local-scale characterization in concert with global satellite measurements. However, efforts towards methane plume imaging have yet to provide convincing results for concentrated sources. Although atmospheric CH4 mapping did not motivate the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) design, recent studies suggest its potential for studying concentrated CH4 sources such as the Coal Oil Point (COP) seep field (˜0.015 Tg CH4 yr-1) offshore Santa Barbara, California. In this study, we developed a band ratio approach on high glint COP AVIRIS data and demonstrate the first successful local-scale remote sensing mapping of natural atmospheric CH4 plumes. Plume origins closely matched surface and sonar-derived seepage distributions, with plume characteristics consistent with wind advection. Imaging spectrometer data may also be useful for high spatial-resolution characterization of concentrated, globally-significant CH4 emissions from offshore platforms and cattle feedlots.

  13. Influence of Different Plant Species on Methane Emissions from Soil in a Restored Swiss Wetland

    PubMed Central

    Bhullar, Gurbir S.; Edwards, Peter J.; Olde Venterink, Harry

    2014-01-01

    Plants are a major factor influencing methane emissions from wetlands, along with environmental parameters such as water table, temperature, pH, nutrients and soil carbon substrate. We conducted a field experiment to study how different plant species influence methane emissions from a wetland in Switzerland. The top 0.5 m of soil at this site had been removed five years earlier, leaving a substrate with very low methanogenic activity. We found a sixfold difference among plant species in their effect on methane emission rates: Molinia caerulea and Lysimachia vulgaris caused low emission rates, whereas Senecio paludosus, Carex flava, Juncus effusus and Typha latifolia caused relatively high rates. Centaurea jacea, Iris sibirica, and Carex davalliana caused intermediate rates. However, we found no effect of either plant biomass or plant functional groups – based on life form or productivity of the habitat – upon methane emission. Emissions were much lower than those usually reported in temperate wetlands, which we attribute to reduced concentrations of labile carbon following topsoil removal. Thus, unlike most wetland sites, methane production in this site was probably fuelled chiefly by root exudation from living plants and from root decay. We conclude that in most wetlands, where concentrations of labile carbon are much higher, these sources account for only a small proportion of the methane emitted. Our study confirms that plant species composition does influence methane emission from wetlands, and should be considered when developing measures to mitigate the greenhouse gas emissions. PMID:24586894

  14. Influence of different plant species on methane emissions from soil in a restored Swiss wetland.

    PubMed

    Bhullar, Gurbir S; Edwards, Peter J; Olde Venterink, Harry

    2014-01-01

    Plants are a major factor influencing methane emissions from wetlands, along with environmental parameters such as water table, temperature, pH, nutrients and soil carbon substrate. We conducted a field experiment to study how different plant species influence methane emissions from a wetland in Switzerland. The top 0.5 m of soil at this site had been removed five years earlier, leaving a substrate with very low methanogenic activity. We found a sixfold difference among plant species in their effect on methane emission rates: Molinia caerulea and Lysimachia vulgaris caused low emission rates, whereas Senecio paludosus, Carex flava, Juncus effusus and Typha latifolia caused relatively high rates. Centaurea jacea, Iris sibirica, and Carex davalliana caused intermediate rates. However, we found no effect of either plant biomass or plant functional groups--based on life form or productivity of the habitat--upon methane emission. Emissions were much lower than those usually reported in temperate wetlands, which we attribute to reduced concentrations of labile carbon following topsoil removal. Thus, unlike most wetland sites, methane production in this site was probably fuelled chiefly by root exudation from living plants and from root decay. We conclude that in most wetlands, where concentrations of labile carbon are much higher, these sources account for only a small proportion of the methane emitted. Our study confirms that plant species composition does influence methane emission from wetlands, and should be considered when developing measures to mitigate the greenhouse gas emissions. PMID:24586894

  15. A comparative study of daytime-based methane emission from two wetlands of Nepal Himalaya

    NASA Astrophysics Data System (ADS)

    Zhu, Dan; Wu, Ning; Bhattarai, Nabin; Oli, Krishna Prasad; Tsering, Kuenzang; Rawat, Gopal Singh; Chen, Huai; Yang, Gang; He, Yinxin; Joshi, Srijana; Rana, Pradyumna; Ismail, Muhammad

    2015-04-01

    Natural wetlands constitute one of the major sources of methane emission to the atmosphere. Data on methane emission from wetlands on southern slopes of the Himalaya (SSH) have not been reported so far. Such data are very valuable for filling the gap and generating the whole emission patterns at regional or even global scale. We selected two wetlands at different altitudinal locations in Nepal, i.e. Beeshazar Lake (286 m a.s.l.) and Dhaap Lake (2089 m a.s.l.), to monitor the daytime methane emissions in monsoon season and dry season separately. Daytime methane emission varied between monsoon and dry seasons and also across different plant communities. The daytime methane emission variations were stronger in dry season than in monsoon season. The source/sink strengths of the two selected plant communities in each wetland were significantly different, presenting the strong spatial variation of methane emission within wetland. The methane emissions recorded in monsoon season were significantly higher (7.74 ± 6.49 mg CH4 m-2 h-1 and 1.00 ± 1.23 mg CH4 m-2 h-1 in low and high altitude wetlands, respectively) than those in dry season (1.84 ± 4.57 mg CH4 m-2 h-1 and 0.27 ± 0.71 mg CH4 m-2 h-1 in low and high altitude wetlands, respectively). Methane emissions from the low altitude wetland were significantly higher than those from the high altitude wetland in both of the seasons. Plant community height, standing water depth and soil temperature correlated to the methane emission from wetlands in this region.

  16. Quantifying Spatial and Temporal Variability of Methane Emissions from a Complex Area Source: Case Study of a Central Indiana Landfill

    NASA Astrophysics Data System (ADS)

    Cambaliza, M. O. L.; Bogner, J. E.; Green, R. B.; Shepson, P. B.; Thoma, E. D.; Foster-wittig, T. A.; Spokas, K.

    2014-12-01

    Atmospheric methane is a powerful greenhouse gas that is responsible for about 17% of the total direct radiative forcing from long-lived greenhouse gases (IPCC 2013). While the global emission of methane is relatively well quantified, the temporal and spatial variability of methane emissions from individual area or point sources are still poorly understood. Using 4 field methods (aircraft-based mass balance, tracer correlation, vertical radial plume mapping, and static chambers) and a new field-validated process-based model (California Landfill Methane Inventory Model, CALMIM 5.4), we investigated both the total emissions from a central Indiana landfill as well as the partitioned emissions inclusive of methanotrophic oxidation for the various cover soils. This landfill is an upwind source for the city of Indianapolis, so the resolution of m2 to km2 scale emissions, as well as understanding the temporal variability for this complex area source, contributes to improved regional inventory calculations. Emissions for the site as a whole were measured using both an aircraft-based mass balance approach as well as a ground-based tracer correlation method, permitting direct comparison of the strengths, limitations, and uncertainties of these two approaches. Because US landfills are highly-engineered and composed of daily, intermediate, and final cover areas with differing thicknesses, composition, and implementation of gas recovery, we also expected different emission signatures and strengths from the various cover areas. Thus we also deployed static chambers and vertical radial plume mapping to quantify the spatial variability of emissions from the thinner daily and intermediate cover areas. Understanding the daily, seasonal and annual emission rates from a landfill is not trivial, and usually requires a combination of measurement and modeling approaches. Thus, our unique data set provides an opportunity to gain an improved understanding of the emissions from a complex area source, an essential requirement for developing improved urban-scale greenhouse gas inventories relevant for addressing mitigation strategies. We report on the results here.

  17. Direct measurements of methane emissions from abandoned oil and gas wells in Pennsylvania.

    PubMed

    Kang, Mary; Kanno, Cynthia M; Reid, Matthew C; Zhang, Xin; Mauzerall, Denise L; Celia, Michael A; Chen, Yuheng; Onstott, Tullis C

    2014-12-23

    Abandoned oil and gas wells provide a potential pathway for subsurface migration and emissions of methane and other fluids to the atmosphere. Little is known about methane fluxes from the millions of abandoned wells that exist in the United States. Here, we report direct measurements of methane fluxes from abandoned oil and gas wells in Pennsylvania, using static flux chambers. A total of 42 and 52 direct measurements were made at wells and at locations near the wells ("controls") in forested, wetland, grassland, and river areas in July, August, October 2013 and January 2014, respectively. The mean methane flow rates at these well locations were 0.27 kg/d/well, and the mean methane flow rate at the control locations was 4.5 × 10(-6) kg/d/location. Three out of the 19 measured wells were high emitters that had methane flow rates that were three orders of magnitude larger than the median flow rate of 1.3 × 10(-3) kg/d/well. Assuming the mean flow rate found here is representative of all abandoned wells in Pennsylvania, we scaled the methane emissions to be 4-7% of estimated total anthropogenic methane emissions in Pennsylvania. The presence of ethane, propane, and n-butane, along with the methane isotopic composition, indicate that the emitted methane is predominantly of thermogenic origin. These measurements show that methane emissions from abandoned oil and gas wells can be significant. The research required to quantify these emissions nationally should be undertaken so they can be accurately described and included in greenhouse gas emissions inventories. PMID:25489074

  18. Methane transport and emissions from soil as affected by water table and vascular plants

    PubMed Central

    2013-01-01

    Background The important greenhouse gas (GHG) methane is produced naturally in anaerobic wetland soils. By affecting the production, oxidation and transport of methane to the atmosphere, plants have a major influence upon the quantities emitted by wetlands. Different species and functional plant groups have been shown to affect these processes differently, but our knowledge about how these effects are influenced by abiotic factors such as water regime and temperature remains limited. Here we present a mesocosm experiment comparing eight plant species for their effects on internal transport and overall emissions of methane under contrasting hydrological conditions. To quantify how much methane was transported internally through plants (the chimney effect), we blocked diffusion from the soil surface with an agar seal. Results We found that graminoids caused higher methane emissions than forbs, although the emissions from mesocosms with different species were either lower than or comparable to those from control mesocosms with no plant (i.e. bare soil). Species with a relatively greater root volume and a larger biomass exhibited a larger chimney effect, though overall methane emissions were negatively related to plant biomass. Emissions were also reduced by lowering the water table. Conclusions We conclude that plant species (and functional groups) vary in the degree to which they transport methane to the atmosphere. However, a plant with a high capacity to transport methane does not necessarily emit more methane, as it may also cause more rhizosphere oxidation of methane. A shift in plant species composition from graminoids to forbs and/or from low to high productive species may lead to reduction of methane emissions. PMID:24010540

  19. Diurnal variations in methane emission from rice plants 

    E-print Network

    Laskowski, Nicholas Aaron

    2004-11-15

    is generated biologically by methanogenic bacteria, a major division of the Archaea kingdom. Environments suitable for methanogenesis are very reduced (methanogens (Chen et al., 1993). Methane transport pathways Methane produced in a flooded rice paddy has three...

  20. Quantifying the Australian methane budget: the importance of wetlands emissions highlighted by surface and train-borne Fourier transform spectrometers

    NASA Astrophysics Data System (ADS)

    Fraser, A. C.; Chan Miller, C.; Palmer, P. I.; Bloom, A. A.; Deutscher, N. M.; Feng, L.; Griffith, D. W.; Jones, N. B.

    2010-12-01

    We quantify the Australian methane budget from 2005 to 2008 using the GEOS-Chem global 3-D model of atmospheric transport, with a focus on the contribution from regional wetlands emissions. The model is evaluated using in situ surface measurements made at Cape Grim (41S, 178E) and Cape Ferguson (19S, 147E); methane dry air column average (XCH4) retrieved from measurements made by ground-based Fourier transform spectrometers (FTSs) at Darwin (12S, 131E) and Wollongong (34S, 151E), installed as part of the Total Carbon Column Observing Network (TCCON); and surface concentrations retrieved from measurements made by an in situ FTS aboard the Ghan train that runs between Adelaide (35S, 139E) and Darwin. We use gravity anomaly data from GRACE (Gravity Recovery and Climate Experiment) to describe the spatial and temporal distribution of wetland emissions and scale it to a prior emission estimate. We find this better describes observed atmospheric methane variability at northern latitudes. We find observed methane columns are influenced by local emissions and intra- and inter-continental transport, as expected. Over tropical sites in the north of Australia (Darwin, Cape Ferguson) there is influence from interhemispheric mixing when the chemical equator lies to the south and these sites are in the chemical northern hemisphere. During the wet season (December - March) wetland emissions are found to contribute up to 40% of the change in the total column at Darwin.

  1. Characterizing Spatiotemporal Dynamics of Methane Emissions from Rice Paddies in Northeast China from 1990 to 2010

    PubMed Central

    Zhang, Yuan; Su, Shiliang; Zhang, Feng; Shi, Runhe; Gao, Wei

    2012-01-01

    Background Rice paddies have been identified as major methane (CH4) source induced by human activities. As a major rice production region in Northern China, the rice paddies in the Three-Rivers Plain (TRP) have experienced large changes in spatial distribution over the recent 20 years (from 1990 to 2010). Consequently, accurate estimation and characterization of spatiotemporal patterns of CH4 emissions from rice paddies has become an pressing issue for assessing the environmental impacts of agroecosystems, and further making GHG mitigation strategies at regional or global levels. Methodology/Principal Findings Integrating remote sensing mapping with a process-based biogeochemistry model, Denitrification and Decomposition (DNDC), was utilized to quantify the regional CH4 emissions from the entire rice paddies in study region. Based on site validation and sensitivity tests, geographic information system (GIS) databases with the spatially differentiated input information were constructed to drive DNDC upscaling for its regional simulations. Results showed that (1) The large change in total methane emission that occurred in 2000 and 2010 compared to 1990 is distributed to the explosive growth in amounts of rice planted; (2) the spatial variations in CH4 fluxes in this study are mainly attributed to the most sensitive factor soil properties, i.e., soil clay fraction and soil organic carbon (SOC) content, and (3) the warming climate could enhance CH4 emission in the cool paddies. Conclusions/Significance The study concluded that the introduction of remote sensing analysis into the DNDC upscaling has a great capability in timely quantifying the methane emissions from cool paddies with fast land use and cover changes. And also, it confirmed that the northern wetland agroecosystems made great contributions to global greenhouse gas inventory. PMID:22235268

  2. Status of worldwide coal mine methane emissions and use

    Microsoft Academic Search

    Carol J Bibler; James S Marshall; Raymond C Pilcher

    1998-01-01

    Underground coal mines worldwide liberate an estimated 29–41×109 m3 of methane annually, of which less than 2.3×109 m3 are used as fuel. The remaining methane is emitted to the atmosphere, representing the loss of a valuable energy resource. Methane is also a major greenhouse gas and is thus detrimental to the environment when vented to the atmosphere. Coal mine methane

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

    PubMed

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

    2014-07-01

    Changes in the budget of dissolved methane measured in a small temperate lake over 1 year indicate that anoxic conditions in the hypolimnion and the autumn overturn period represent key factors for the overall annual methane emissions from lakes. During periods of stable stratification, large amounts of methane accumulate in anoxic deep waters. Approximately 46% of the stored methane was emitted during the autumn overturn, contributing ?80% of the annual diffusive methane emissions to the atmosphere. After the overturn period, the entire water column was oxic, and only 1% of the original quantity of methane remained in the water column. Current estimates of global methane emissions assume that all of the stored methane is released, whereas several studies of individual lakes have suggested that a major fraction of the stored methane is oxidized during overturns. Our results provide evidence that not all of the stored methane is released to the atmosphere during the overturn period. However, the fraction of stored methane emitted to the atmosphere during overturn may be substantially larger and the fraction of stored methane oxidized may be smaller than in the previous studies suggesting high oxidation losses of methane. The development or change in the vertical extent and duration of the anoxic hypolimnion, which can represent the main source of annual methane emissions from small lakes, may be an important aspect to consider for impact assessments of climate warming on the methane emissions from lakes. PMID:24873684

  4. Characterizing Fugitive Methane Emissions in the Barnett Shale Area Using a Mobile Laboratory.

    PubMed

    Lan, Xin; Talbot, Robert; Laine, Patrick; Torres, Azucena

    2015-07-01

    Atmospheric methane (CH4) was measured using a mobile laboratory to quantify fugitive CH4 emissions from Oil and Natural Gas (ONG) operations in the Barnett Shale area. During this Barnett Coordinated Campaign we sampled more than 152 facilities, including well pads, compressor stations, gas processing plants, and landfills. Emission rates from several ONG facilities and landfills were estimated using an Inverse Gaussian Dispersion Model and the Environmental Protection Agency (EPA) Model AERMOD. Model results show that well pads emissions rates had a fat-tailed distribution, with the emissions linearly correlated with gas production. Using this correlation, we estimated a total well pad emission rate of 1.5 × 10(5) kg/h in the Barnett Shale area. It was found that CH4 emissions from compressor stations and gas processing plants were substantially higher, with some "super emitters" having emission rates up to 3447 kg/h, more then 36,000-fold higher than reported by the Environmental Protection Agency (EPA) Greenhouse Gas Reporting Program (GHGRP). Landfills are also a significant source of CH4 in the Barnett Shale area, and they should be accounted for in the regional budget of CH4. PMID:26148552

  5. Quantification of strong emissions of methane in the Arctic using spectral measurements from TANSO-FTS and IASI

    NASA Astrophysics Data System (ADS)

    Bourakkadi, Zakia; Payan, Sébastien; Bureau, Jérôme

    2015-04-01

    Methane is the second most important greenhouse gas after the carbon dioxide but it is 25 times more effective in contributing to the radiative forcing than the carbon dioxide(1). Since the pre-industrial times global methane concentration have more than doubled in the atmosphere. This increase is generally caused by anthropogenic activities like the massif use and extraction of fossil fuel, rice paddy agriculture, emissions from landfills... In recent years, several studies show that climate warming and thawing of permafrost act on the mobilization of old stored carbon in Arctic causing a sustained release of methane to the atmosphere(2),(3),(4). The methane emissions from thawing permafrost and methane hydrates in the northern circumpolar region will become potentially important in the end of the 21st centry because they could increase dramatically due to the rapid climate warming of the Artic and the large carbon pools stored there. The objective of this study is to evaluate and quantify methane strong emissions in this region of the globe using spectral measurements from the Thermal And Near Infrared Sensor for carbon Observations-Fourier Transform Spectrometer (TANSO-FTS) and the Infrared Atmospheric Sounding Interferometer (IASI). We use also the LMDZ-PYVAR model to simulate methane fluxes and to estimate how they could be observed by Infrared Sounders from space. To select spectra with high values of methane we developed a statistical approach based on the singular value decomposition. Using this approach we can identify spectra over the important emission sources of methane and we can by this way reduce the number of spectra to retrieve by an line-by-line radiative transfer model in order to focus on those which contain high amount of methane. In order to estimate the capacity of TANSO-FTS and IASI to detect peaks of methane emission with short duration at quasi-real time, we used data from MACC (Monitoring Atmospheric Composition and Climate) simulations to compute spectra which we are compared to those from TANSO-FTS and IASI. References [1] Intergovernmental Panel on Climate Change (2007), Climate Change 2007: The Physical Sience Basis, edited by S. Solomon et al., Combrige Univ.Press, Cambrige, U.K. [2] N. Shakhova, I. Semiletov, A. Salyuk, V. Yusupov, D. Kosmach, O.Gustafsson.: Extensive Methane venting to the atmosphere from sediments of the East Siberian Arctic shelf, SCIENCE 5 March 2010, Vol 327. [3] K. Negandhi, I. Laurion, M. J. Whiticar, P. E. Galand, X. X. Connie Lovejoy.: Small thaw ponds: An unaccounted source of methane in the canadian high Arctic, PLOS ONE november 2013/ vol 8/issue 11/e78204. [4] J. T. Crawford, R. G. Striegl, K. P. Wickland, M . Dornblaser, and E. Stanley.: Emissions of carbon dioxide and methane from a headwater stream network of interior Alaska, Journal of Giophysical Recherch : Biogeosciences, VOL, 118, 482-494, doi:10.1002/jgrg,20034, 2013.

  6. Methane production and bubble emissions from arctic lakes: Isotopic implications for source pathways and ages

    Microsoft Academic Search

    K. M. Walter; J. P. Chanton; F. S. Chapin; E. A. G. Schuur; S. A. Zimov

    2008-01-01

    This study reports an atmospheric methane (CH4) source term previously uncharacterized regarding strength and isotopic composition. Methane emissions from 14 Siberian lakes and 9 Alaskan lakes were characterized using stable isotopes (13C and D) and radiocarbon (14C) analyses. We classified ebullition (bubbling) into three categories (background, point sources, and hot spots) on the basis of fluxes, major gas concentrations, and

  7. Methane emissions from beef cattle: Effects of fumaric acid, essential oil, and canola oil1

    Microsoft Academic Search

    K. A. Beauchemin; S. M. McGinn

    2010-01-01

    The objective of this study was to iden- tify feed additives that reduce enteric methane emis- sions from cattle. We measured methane emissions, total tract digestibility (using chromic oxide), and rumi- nal fermentation (4 h after feeding) in growing beef cattle fed a diet supplemented with various additives. The experiment was designed as a replicated 4 × 4 Latin square

  8. A 3D Microphysical Model of Titan's Methane Cloud

    Microsoft Academic Search

    J. Xiao; C. Newman; A. Inada; M. Richardson

    2006-01-01

    A time-dependent idealized 3D microphysical model for Titan's methane cloud is described. This new high resolution microphysical model nests in a Titan WRF GCM model. It assumes the vapor-liquid equilibria of methane-nitrogen mixtures which are based on the recent chemical experiments and thermodynamics models. In particular, the methane is condensed at a given temperature and pressure. Meanwhile nitrogen is dissolved

  9. A COMPARISON OF METHODS FOR THE MEASUREMENT OF METHANE EMISSIONS FROM MUNICIPAL SOLID WASTE LANDFILLS FOR THE

    E-print Network

    Paris-Sud XI, Université de

    a z. A COMPARISON OF METHODS FOR THE MEASUREMENT OF METHANE EMISSIONS FROM MUNICIPAL SOLID WASTE the contribution to the greenhouse effect due to methane emitted by municipal solid waste landfills. The objective an inventory of methane emissions covering all municipal solid waste landfills in France. EQUIPMENT AND METHODS

  10. Quantification of methane emission rates from coal mine ventilation shafts using airborne remote sensing data

    NASA Astrophysics Data System (ADS)

    Krings, T.; Gerilowski, K.; Buchwitz, M.; Hartmann, J.; Sachs, T.; Erzinger, J.; Burrows, J. P.; Bovensmann, H.

    2012-10-01

    The quantification of emissions of the greenhouse gas methane is essential for attributing the roles of anthropogenic activity and natural phenomena in global climate change. Our current measurement systems and networks whilst having improved during the last decades, are deficient in many respects. For example, the emissions from localised and point sources such as landfills or fossil fuel exploration sites are not readily assessed. A tool developed to better understand point sources of the greenhouse gases carbon dioxide and methane is the optical remote sensing instrument MAMAP, operated from aircraft. After a recent instrument modification, retrievals of the column averaged dry air mole fractions for methane XCH4 (or for carbon dioxide XCO2) derived from MAMAP data, have a precision of about 0.4% or better and thus can be used to infer emission rate estimates using an optimal estimation inverse Gaussian plume model or a simple integral approach. CH4 emissions from two coal mine ventilation shafts in Western Germany surveyed during the AIRMETH 2011 measurement campaign are used as examples to demonstrate and assess the value of MAMAP data for quantifying CH4 from point sources. While the knowledge of the wind is an important input parameter in the retrieval of emissions from point sources and is generally extracted from models, additional information from a turbulence probe operated on-board the same aircraft was utilised to enhance the quality of the emission estimates. Although flight patterns were optimised for remote sensing measurements, data from an in-situ analyser for CH4 were found to be in good agreement with retrieved dry columns of CH4 from MAMAP and could be used to investigate and refine underlying assumptions for the inversion procedures. With respect to the total emissions of the mine at the time of the overflight, the inferred emission rate of 50.4 kt CH4 yr-1 has a difference of less than 1% compared to officially reported values by the mine operators, while the uncertainty, which reflects variability of the sources and conditions as well as random and systematic errors, is about ±13.5%.

  11. Modeling of simultaneous anaerobic methane and ammonium oxidation in a membrane biofilm reactor.

    PubMed

    Chen, Xueming; Guo, Jianhua; Shi, Ying; Hu, Shihu; Yuan, Zhiguo; Ni, Bing-Jie

    2014-08-19

    Nitrogen removal by using the synergy of denitrifying anaerobic methane oxidation (DAMO) and anaerobic ammonium oxidation (Anammox) microorganisms in a membrane biofilm reactor (MBfR) has previously been demonstrated experimentally. In this work, a mathematical model is developed to describe the simultaneous anaerobic methane and ammonium oxidation by DAMO and Anammox microorganisms in an MBfR for the first time. In this model, DAMO archaea convert nitrate, both externally fed and/or produced by Anammox, to nitrite, with methane as the electron donor. Anammox and DAMO bacteria jointly remove the nitrite fed/produced, with ammonium and methane as the electron donor, respectively. The model is successfully calibrated and validated using the long-term (over 400 days) dynamic experimental data from the MBfR, as well as two independent batch tests at different operational stages of the MBfR. The model satisfactorily describes the methane oxidation and nitrogen conversion data from the system. Modeling results show the concentration gradients of methane and nitrogen would cause stratification of the biofilm, where Anammox bacteria mainly grow in the biofilm layer close to the bulk liquid and DAMO organisms attach close to the membrane surface. The low surface methane loadings result in a low fraction of DAMO microorganisms, but the high surface methane loadings would lead to overgrowth of DAMO bacteria, which would compete with Anammox for nitrite and decrease the fraction of Anammox bacteria. The results suggest an optimal methane supply under the given condition should be applied not only to benefit the nitrogen removal but also to avoid potential methane emissions. PMID:25055054

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One hundred thirteen steers were fed a dry-rolled corn-based ration to determine feed intake and growth over a 64-d period. Thirty–seven steers were selected to determine 6 h methane emissions. Steers that were evaluated had a methane emission of 3.6 ± 0.2 L/h, a BW of 573 ± 12 kg, a DMI of 696 ± ...

  13. Emission and speciation of non-methane volatile organic compounds from anthropogenic sources in China

    NASA Astrophysics Data System (ADS)

    Wei, Wei; Wang, Shuxiao; Chatani, Satoru; Klimont, Zbigniew; Cofala, Janusz; Hao, Jiming

    An emission inventory of non-methane volatile organic compounds (NMVOCs) from anthropogenic sources in China was compiled for the year 2005. The NMVOC emissions were 20.1 Tg, of which industrial and domestic solvent use, road transportation, and bio-fuel combustion contributed 28.6%, 23.4%, and 18.0%, respectively. Emissions were speciated into 40 species according to their atmospheric photochemical reactivity, toxicity, and model applicability. Of the total emissions, alkanes account for 29.8%, followed by aromatics (21.9%), alkenes and alkynes (21.0%), and carbonyls (17.8%). Emissions at the provincial level were spatially allocated onto grids with a resolution of 36 km×36 km, according to population distribution. Furthermore, the provincial and sectoral emissions of nine toxic species, including n-hexane, 1,3-butadiene, styrene, benzene, toluene, xylene, methanol, formaldehyde, and acraldehyde, are also analyzed. Finally, the national total emissions were considered with an uncertainty of [-44%,+109%] in 95% confidence interval, by using the Monte Carlo method.

  14. Mechanisms of Crop Management Impact on Methane Emissions from Rice Fields in Los Baños, Philippines

    Microsoft Academic Search

    R. Wassmann; L. V. Buendia; R. S. Lantin; C. S. Bueno; L. A. Lubigan; A. Umali; N. N. Nocon; A. M. Javellana; H. U. Neue

    2000-01-01

    This article comprises 4 yr of field experiments on methane (CH4) emissions from rice fields conducted at Los Baños, Philippines. The experimental layout allowed automated measurements of CH4 emissions as affected by water regime, soil amendments (mineral and organic), and cultivars. In addition to emission records over 24 h, ebullition and dissolved CH4 in soil solution were recorded in weekly

  15. Methane emission measurements in a cattle grazed pasture: a comparison of four methods

    NASA Astrophysics Data System (ADS)

    Tallec, T.; Klumpp, K.; Hensen, A.; Rochette, Y.; Soussana, J.-F.

    2012-10-01

    Methane (CH4) is considered to be the second main contributor to the global greenhouse gas effect, with major CH4 emissions originating from livestock. Accurate measurements from ruminating herds are required to improve emission coefficients used in national emission inventories, and to evaluate mitigation strategies. Previous measurements of enteric methane emissions from domestic animals have been carried out in artificial conditions such as laboratory chambers, or by fitting individual animals with capillary tubes and using SF6 as a tracer. Here we evaluated the reliability of eddy covariance technique (EC), already used for CO2 fluxes, for continuous CH4 measurements over a grazed field plot. Analyzer accuracy and reliability of eddy covariance technique were tested against field scale measurements with the SF6 tracer technique, Gaussian plume model and emission factors (i.e. IPCC). Results indicate a better agreement between EC and SF6 method when grazing heifers were parked close to the EC setup. However, a systematic underestimation of EC data appeared and even more when the distance between the source (ruminating heifers) and EC setup (mast) was increased. A two-dimensional footprint density function allowed to correct for the dilution effect on measured CH4 and led to a good agreement with results based on the SF6 technique (on average 231 and 252 g CH4 ha-1 over the grazing experiment, respectively). Estimations of the CH4 budgets for the whole grazing season were in line with estimates (i.e. emission factor coefficients) based on feed intake and animal live weight as well as SF6 technique. IPCC method Tier 2, however, led to an overestimation of CH4 fluxes on our site.

  16. Seasonal Production and Emission of Methane from Rice Fields, Final Report

    SciTech Connect

    Khalil, M. Aslam K.; Rasmussen,Reinhold A.

    2002-12-03

    B 139 - Methane (CH4) is a greenhouse gas regarded second only to carbon dioxide in its ability to cause global warming. Methane is important because of its relatively fast increase, and also because it is, per molecule, some 60 times more effective than carbon dioxide in causing global warming. The largest present anthropogenic sources of methane are rice fields, cattle and biomass burning. The global emissions from these sources are still not well known. In the middle 1980s there were few available data on methane emissions from rice fields leading to estimates of a global source between 100-280 Tg/yr. Extensive worldwide research during the last decade has shown that the global emissions from rice fields are more likely to be in the range of 30-80Tg/yr. While this work has led to a substantial reduction in the estimated emissions, the uncertainty is still quite large, and seriously affects our ability to include methane in integrated assessments for future climate change and environmental management.China dominated estimates of methane emissions from rice fields because it was, and is, the largest producer of rice, and major increases in rice production had taken place in the country over the last several decades. This report summarizes the work in Sichuan Province, China, in each of the following areas: the design of the experiment; the main results on methane emissions from rice fields, delineating the factors controlling emissions; production of methane in the soil; a survey of water management practices in sample of counties in Sichuan province; and results of ambient measurements including data from the background continental site. B139

  17. Methane emission from coal and associated strata samples

    Microsoft Academic Search

    G. R. Barker-Read; S. A. Radchenko

    1989-01-01

    Summary This article discusses methods for providing a reliable forecast of the gas-dynamic behaviour of coal seams and adjacent strata. It shows that the ash content of carbonaceous materials determines their sorptive capacity (a universally applicable expression is presented for calculating the methane content of a sample) whilst the rate of methane desorption is a function of the degree of

  18. The effect of clipping on methane emissions from Carex

    Microsoft Academic Search

    DOROTHY KELKER; JEFFREY CHANTON

    1997-01-01

    The purpose of this study was to estimate theresistance to methane release of the above-groundportion of Carex, a wetland sedge, and todetermine the locus of methane release from the plant. Measurements conducted on plants clipped to differentheights above the water level revealed that themethane flux from clipped plants was on the order of97% to 111% of control (unclipped) values. Thegreatest

  19. Methane emission from Russian frozen wetlands under conditions of climate change

    NASA Astrophysics Data System (ADS)

    Reneva, S.

    2009-04-01

    There is growing evidence that the climate change will have significant impact on permafrost, leading to warming, thawing, and disappearance of the frozen ground. Arctic soils contain 14%-30% of all the carbon stored in soils worldwide, many of which is accumulated in the Arctic wetlands (Anisimov & Reneva 2006). Wetlands occupy almost 2 million km2 in the circumpolar region, contain about 50 Gt C, and because of the high groundwater levels favour the production of methane in the anaerobic carbon-rich soil layer (Anisimov et al 2005). Methane has 21-times stronger greenhouse effect than the equal amount of CO2, and there are growing concerns that enhanced CH4 emission may have significant effect on the global radiative forcing. The goal of our study was to estimate the potential increase in the methane emission from Russian frozen wetlands under the projected for the mid-21st century climatic conditions and to evaluate the effect it may have on global radiative forcing. We used digital geographically referenced contours of Russian wetlands from 1:1,000,000-scale topographic maps to calculate the total area (350 000 km2) and the fraction of land they occupy in the nodes of 0.5 by 0.5 degree lat/long regular grid spanning permafrost regions. These data were overlaid with the results from predictive permafrost model (Anisimov & Belolutskaia 2003, Anisimov et al 1999) forced by CCC, HadCM3, GFDL, NCAR climatic projections for 2050 under B1 emission scenario (ref. http://ipcc-ddc.cru.uea.ac.uk/ and http://igloo.atmos.uiuc.edu/IPCC/). Ultimately, we calculated the increase in the amount of organic material that may potentially become available for decomposition due to deeper seasonal thawing of wetlands in the Russian part of Arctic. Following (Christensen et al 2003a, Christensen et al 2003b) we hypothesised that the temperature and substrate availability combined explain almost entirely the variations in mean annual methane emissions. We used the results of numerous calculations with the full-scale carbon model simulating a large variety of soil and temperature conditions to derive a simple parameterization that links the relative changes of methane flux with soil temperature and active layer thickness: J2/J1= exp 0.1(T2 - T1) , where J - methane flux, T - ground temperature, Hd - thaw depth, subscripts 1 and 2 designate the baseline and future climatic conditions current and the future time slices. Our results for the mid-21stcentury indicate that the annual emission of methane from Russian permafrost region may increase by 20% - 40% over most of the area, and by 50% - 80% in the northernmost locations, which corresponds to 6-8 Mt y-1. Given that the average residence time of methane in the atmosphere is 12 years, and assuming that other sinks and sources remain unchanged, by the mid-21st century the additional annual 6-8 Mt source due to thawing of permafrost may increase the overall amount of atmospheric methane by approximately 100 Mt, or 0.04 ppm. The sensitivity of the global temperature to 1 ppm of atmospheric methane is approximately 0.3 oC (Ramaswamy 2001), and thus the additional radiative forcing resulting from such an increase may raise the global mean annual air temperature by 0.012 oC. References Anisimov OA, Belolutskaia MA. 2003. Climate-change impacts on permafrost: predictive modeling and uncertainties. In Problems of ecological modeling and monitoring of ecosystems, ed. Y Izrael, pp. 21-38. S.Petersburg: Hydrometeoizdat Anisimov OA, Lavrov SA, Reneva SA. 2005. Modelling the emission of greenhouse gases from the Arctic wetlands under the conditions of the global warming. In Climatic and environmental changes, ed. GV Menzhulin, pp. 21-39. S.Petersburg: Hydrometeoizdat Anisimov OA, Nelson FE, Pavlov AV. 1999. Predictive scenarios of permafrost development under the conditions of the global climate change in the XXI century. Earth Cryosphere 3: 15-25 Anisimov OA, Reneva SA. 2006. Permafrost and changing climate: the Russian perspective. Ambio 35: 169-75 Christensen TR, Ekberg A, Strom L, Mastepanov M,

  20. Linking Sediment Characteristics to Methane Emission Potential in Subarctic Lakes

    NASA Astrophysics Data System (ADS)

    Logozzo, L. A.; Perry, A. L.; Wik, M.; Thornton, B. F.; Crill, P. M.; Johnson, J. E.; Varner, R. K.

    2014-12-01

    High latitudes are experiencing warmer average annual temperatures, resulting in the thawing of permafrost, and possibly, the increased emission of methane (CH4) from lakes and ponds. One potential impact of permafrost thaw is increased runoff of organic matter into streams, lakes and ponds. Warming can also potentially increase lake sediment temperatures, resulting in a lower methane (CH4) storage capacity and increased CH4 production. We focused our study on six lakes of varying size, location, and characteristics, located in the Stordalen Mire area in northernmost Sweden. We collected sediment cores in each lake and analyzed the dissolved CH4 in the sediment at various depths in the core. The sediment CH4 concentrations were compared to the grain sizes and compositions (total organic carbon (TOC), total sulfur (S), and total nitrogen) of the sediment at the corresponding depths. We also measured dissolved CH4 concentrations in the lake water and compared them to those of the sediment. We found that on average, the CH4 concentration was higher (16.7 ?gCH4 gds-1 ± 16.4) in sediments with more TOC (31.4 wt % ± 10.8). There was also a strong positive correlation between sediment CH4 and total S (r2 = 0.37, p = 0.165), between sediment CH4 and TOC (r2 = 0.53, p = 0.101), and between TOC and total S (r2 = 0.64, p = 0.066). This indicates in situ production of CH4­ in the lake sediment at depths of peak CH4 concentrations in at least two of the lakes. The peak of dissolved CH4 was located deeper in the cores although this depth varied among the lakes. In four lakes, we found high CH4 concentrations in the sediment, as well as high CH4 concentrations in the water, indicating little oxidation in the water column or persistent CH4 production in the sediment. This suggests that at least four of our studied lakes have great potential to release a substantial amount of their produced CH4 to the atmosphere.

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Scandella, Benjamin P.; Varadharajan, Charuleka; Hemond, Harold F.; Ruppel, Carolyn; Juanes, Ruben

    2011-03-01

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

  3. Invading Phragmites australis stimulates methane emissions from North American tidal marshes

    NASA Astrophysics Data System (ADS)

    Mueller, Peter; Meschter, Justin E.; Hager, Rachel N.; Mozdzer, Thomas J.; Jensen, Kai; Langley, J. Adam; Baldwin, Andrew; Megonigal, J. Patrick

    2015-04-01

    Most studies concerned with invasive plant species focus on effects on biodiversity, while only few have investigated how the greenhouse gas balance of an ecosystem or, in particular, how methane emissions are affected by invasion driven shifts in plant species composition. In this study, conducted in brackish marsh sites of the Chesapeake Bay, United States, we investigated the effect of the none-native grass Phragmites australis invading native shortgrass communities on methane emissions. In situ gas flux measurements using static chambers were used to quantify methane emissions along transects of progressive invasion by Phragmites. Methane emissions were several fold higher in Phragmites stands than in adjacent native communities and increased with progressive invasion of Phragmites. Results of a mesocosm experiment support our field observations and show consistently higher methane emissions from mesocoms planted with Phragmites even at different hydrological conditions. Because tidal marshes, as blue carbon ecosystems, sequester soil carbon rapidly and emit methane slowly compared to other wetland ecosystems, they are increasingly recognized as having a high carbon value. Our results indicate that the replacement of native marsh communities by Phragmites may considerably change the green house gas balance of these ecosystems and thus lower their carbon sequestration value.

  4. Emissions of Methane, Nitrous Oxide, and Ammonia from California's San Joaquin Valley

    NASA Astrophysics Data System (ADS)

    Peischl, J.; McKeen, S. A.; Neuman, J.; Nowak, J. B.; Ryerson, T. B.; Trainer, M.; Commane, R.; Daube, B.; Kort, E. A.; Santoni, G. W.; Wofsy, S. C.; Xiang, B.; Parrish, D. D.

    2012-12-01

    Airborne measurements of methane (CH4), nitrous oxide (N2O), and ammonia (NH3) were made aboard the NOAA P-3 during the CalNex (California Research at the Nexus of Air Quality and Climate Change) field campaign based out of Ontario, California in May and June, 2010. From these measurements, we determine emission fluxes of CH4 and N2O by integrating crosswind plume transects from different regions of the San Joaquin Valley, where most anthropogenic emissions of these greenhouse gases occur in California due to extensive agricultural activity. We compare derived emissions of CH4 and N2O to works which use inverse modeling to derive fluxes of CH4 (Santoni et al., 2012) and N2O (Xiang et al., 2012) from this region, as well as the current California Air Resources Board and EDGAR emissions inventories. Finally, we will present derived emissions of NH3 compared to the latest U.S. Environmental Protection Agency National Emissions Inventory from a similar integration analysis by Nowak et al. (2012).

  5. Qualitative assessment of methane emission inventory from municipal solid waste disposal sites: a case study

    NASA Astrophysics Data System (ADS)

    Kumar, Sunil; Mondal, A. N.; Gaikwad, S. A.; Devotta, Sukumar; Singh, R. N.

    2004-09-01

    In developing countries like India, urban solid waste (SW) generation is increasing enormously and most of the SWs are disposed off by land filling in low-lying areas, resulting into generation of large quantities of biogas. Methane, the major constituent gas is known to cause global warming due to green house gas (GHG) effect. There is a need to study the ever-increasing contribution of SW to the global GHG effect. To assess the impacts, estimation of GHG emission is must and to avoid misguidance by these emission-data, qualitative assessment of the estimated GHG is a must. In this paper, methane emission is estimated for a particular landfill site, using default methodology and modified triangular methodology. Total methane generation is same for both theoretical methodologies, but the modified triangular method has an upper hand as it provides a time-dependent emission profile that reflects the true pattern of the degradation process. To check the quality of calculated emission-data, extensive sampling is carried out for different seasons in a year. Field results show a different trend as compared to theoretical results, this compels for logical thinking. Each methane emission-data is backed up by the uncertainty associated with it, this further strengthens the quality check of these data. Uncertainty calculation is done using Monte Carlo simulation technique, recommended in IPCC Guideline. In the due course of qualitative assessment of methane emission-data, many site-specific sensitive parameters are discovered and are briefly discussed in this paper.

  6. A pulse-label experiment to determine the biophysical kinetics of different carbon pools for methane emissions in a Carex aquatilis dominated wetland

    NASA Astrophysics Data System (ADS)

    Dunn, S.; von Fischer, J. C.

    2012-12-01

    Methane is a greenhouse gas that is produced by microbes under anoxic conditions. Previous work has coupled photosynthesis and methane emissions using stable and radio isotopes of Carbon Dioxide. However, a full understanding of the transfer and conversion of fixed carbon from the plant, through the rhizosphere, and to the atmosphere as methane is lacking. The coupling of the methane and belowground carbon cycles within model simulations will allow for a finer understanding of the role of ecosystem production in methane emission and the potential effects of a changing climate. In order to parameterize this model, flux rates and pool half-lives need to be measured in situ. Using 13C-CO2, 13C-Acetate, and 13C-CH4, we conducted a pulse-chase experiment in a high alpine wetland dominated by Carex aquatilis to determine the temporal importance of different pools within the methane cycle on emissions. Using a field-based Methane Carbon Isotope Analyzer we measured the flux and isotopic composition of methane from the labeled plots at a high temporal resolution (~ every 2 hours). Flux of 13C-CH4 from the plots amended with dissolved 13C-CH4 peaked approximately 5 hours after addition and decreased significantly within 24hours. Flux of labeled methane from the plots amended with dissolved 13-Acetate peaked 13 hours after injection and decayed very slowly. Flux of labeled methane from plots amended with 13C-CO2 appeared around 13 hours after addition and was not detectable within another 12 hours. We will present an analysis of how the varying turnover times of these labeled materials reflect differences in pool sizes and biophysical kinetics.

  7. Laboratory measurements and methane photochemistry modeling

    NASA Technical Reports Server (NTRS)

    Romani, P. N.

    1990-01-01

    Methane is photolyzed by the solar UV in the stratosphere of Saturn. Subsequent photochemistry leads to the production of acetylene (C2H2) and diacetylene (C4H2). These species are produced where it is relatively warm (T is greater than or equal to 140 K), but the tropopause temperature of Saturn (approximately 80 K) is low enough that these two species may freeze out to their respective ices. Numerical models which include both photochemistry and condensation loss make predictions about the mixing ratios of these species and haze production rates. These models are dependent upon knowing reaction pathways and their associated kinetic reaction rate constants and vapor pressures. How uncertainties in the chemistry and improvements in the vapor pressures affect model predictions for Saturn are discussed.

  8. Methane Emissions from a Beef Cattle Feedyard during Winter and Summer on the Southern High Plains of Texas.

    PubMed

    Todd, Richard W; Altman, Miriam B; Cole, N Andy; Waldrip, Heidi M

    2014-07-01

    Methane (CH) emissions from enteric fermentation by livestock account for about 2.1% of U.S. greenhouse gas emissions, with beef and dairy cattle being the most significant sources. A better understanding of CH emissions from beef cattle feedyards can help build more accurate emission inventories, improve predictive models, and meet potential regulatory requirements. Our objective was to quantify CH emissions during winter and summer at a typical beef cattle feedyard on the southern High Plains in Texas. Methane emissions were quantified over 32 d in winter and 44 d in summer using open-path lasers and inverse dispersion analysis. Methane per capita emission rate (PCER) ranged from 71 to 118 g animal d in winter and from 70 to 130 g animal d in summer. Mean CH PCER was similar in January, February, and May (average, 85.0 ± 0.95 g animal d) and increased to 93.4 g animal d during the June-July period. This increase coincided with increased dietary fiber. Methane loss ranged from 9.2 to 11.4 g CH kg dry matter intake, with lower values during winter. Gross energy intake (GEI) ranged from 135.2 to 164.5 MJ animal d, and CH energy loss ranged from 4.5 to 4.9 MJ animal d. Fraction of GEI lost as CH (Y) averaged 2.8% in winter, 3.2% in summer, and 3.0% overall. These values confirm the Y value currently recommended by the Intergovernmental Panel on Climate Change for Tier 2 estimates of enteric CH from feedlot fed cattle. PMID:25603061

  9. High-resolution Methane Isotope Data Improves Model of Wetland Methane Dynamics

    NASA Astrophysics Data System (ADS)

    McCalley, C. K.; Li, C.; Deng, J.; Shorter, J. H.; Zahniser, M. S.; Chanton, J.; Crill, P. M.; Saleska, S. R.; Varner, R. K.

    2014-12-01

    Methane flux from wetlands is both a critical component of the global CH4 budget, and highly sensitive to global climate change. Understanding the variability of this CH4 source is essential for improving predictions of biosphere-atmosphere feedbacks to global climate. Gaps in our knowledge of the biological mechanisms that underlie CH4 flux patterns from natural ecosystems limit our ability to scale flux estimates as well as predict future emissions. Process based models, such as the Wetland-Denitrification-Decomposition (DNDC) model used here, are instrumental for testing our understanding of these mechanisms as well as applying them to predict emissions across spatial and temporal scales. Recent incorporation of carbon isotopes into the Wetland-DNDC model has expanded our ability to validate model predictions of the CH4 production, consumption, and transport processes that yield net emissions. To further improve model estimates we quantified the isotopic composition of CH4 emissions from a high latitude wetland underlain by discontinuous permafrost (Stordalen Mire, Sweden) and a temperate wetland (Sallie's Fen, NH). We used quantum cascade laser technology, linked to automated chambers, to measure ?13C-CH4 at a high temporal frequency and partition net CH4 emissions into its component parts, methanogenesis (including both acetoclastic, and hydrogenotrophic pathways) and methanotrophy (which consumes CH4 primarily via aerobic metabolism). Comparison of this multi-year dataset to wetland-DNDC model simulations of CH4 flux and ?13C highlighted spatial and seasonal drivers associated with vegetation, hydrology and temperature, showing higher fluxes dominated by acetoclastic production in wetter, sedge dominated areas and under warmer conditions. Model predictions of both flux and isotopes most closely matched measured values during peak growing season, with much larger divergence from measurements, especially for ?13C-CH4, during the spring and fall. Together these results provide insights into the role of plant and microbial communities and variable environmental conditions in shaping CH4 production and consumption patterns in diverse wetland ecosystems as well as highlight the need to focus investigations on the processes underlying CH4 dynamics during seasonal transitions.

  10. The Australian methane budget: Interpreting surface and train-borne measurements using a chemistry transport model

    NASA Astrophysics Data System (ADS)

    Fraser, Annemarie; Chan Miller, Christopher; Palmer, Paul I.; Deutscher, Nicholas M.; Jones, Nicholas B.; Griffith, David W. T.

    2011-10-01

    We investigate the Australian methane budget from 2005-2008 using the GEOS-Chem 3D chemistry transport model, focusing on the relative contribution of emissions from different sectors and the influence of long-range transport. To evaluate the model, we use in situ surface measurements of methane, methane dry air column average (XCH4) from ground-based Fourier transform spectrometers (FTSs), and train-borne surface concentration measurements from an in situ FTS along the north-south continental transect. We use gravity anomaly data from Gravity Recovery and Climate Experiment to describe the spatial and temporal distribution of wetland emissions and scale it to a prior emission estimate, which better describes observed atmospheric methane variability at tropical latitudes. The clean air sites of Cape Ferguson and Cape Grim are the least affected by local emissions, while Wollongong, located in the populated southeast with regional coal mining, samples the most locally polluted air masses (2.5% of the total air mass versus <1% at other sites). Averaged annually, the largest single source above background of methane at Darwin is long-range transport, mainly from Southeast Asia, accounting for ˜25% of the change in surface concentration above background. At Cape Ferguson and Cape Grim, emissions from ruminant animals are the largest source of methane above background, at approximately 20% and 30%, respectively, of the surface concentration. At Wollongong, emissions from coal mining are the largest source above background representing 60% of the surface concentration. The train data provide an effective way of observing transitions between urban, desert, and tropical landscapes.

  11. Potassium application reduces methane emission from a flooded field planted to rice

    Microsoft Academic Search

    Y. Jagadeesh Babu; D. R. Nayak; T. K. Adhya

    2006-01-01

    In a field study, potassium (K) applied as muriate of potash (MOP) significantly reduced methane (CH4) emission from a flooded alluvial soil planted to rice. Cumulative emission was highest in control plots (125.34 kg CH4 ha?1), while the lowest emission was recorded in field plots receiving 30 kg K ha?1 (63.81 kg CH4 ha?1), with a 49% reduction in CH4 emission. Potassium application

  12. Measurements of methane emissions at natural gas production sites in the United States

    PubMed Central

    Allen, David T.; Torres, Vincent M.; Thomas, James; Sullivan, David W.; Harrison, Matthew; Hendler, Al; Herndon, Scott C.; Kolb, Charles E.; Fraser, Matthew P.; Hill, A. Daniel; Lamb, Brian K.; Miskimins, Jennifer; Sawyer, Robert F.; Seinfeld, John H.

    2013-01-01

    Engineering estimates of methane emissions from natural gas production have led to varied projections of national emissions. This work reports direct measurements of methane emissions at 190 onshore natural gas sites in the United States (150 production sites, 27 well completion flowbacks, 9 well unloadings, and 4 workovers). For well completion flowbacks, which clear fractured wells of liquid to allow gas production, methane emissions ranged from 0.01 Mg to 17 Mg (mean = 1.7 Mg; 95% confidence bounds of 0.67–3.3 Mg), compared with an average of 81 Mg per event in the 2011 EPA national emission inventory from April 2013. Emission factors for pneumatic pumps and controllers as well as equipment leaks were both comparable to and higher than estimates in the national inventory. Overall, if emission factors from this work for completion flowbacks, equipment leaks, and pneumatic pumps and controllers are assumed to be representative of national populations and are used to estimate national emissions, total annual emissions from these source categories are calculated to be 957 Gg of methane (with sampling and measurement uncertainties estimated at ±200 Gg). The estimate for comparable source categories in the EPA national inventory is ?1,200 Gg. Additional measurements of unloadings and workovers are needed to produce national emission estimates for these source categories. The 957 Gg in emissions for completion flowbacks, pneumatics, and equipment leaks, coupled with EPA national inventory estimates for other categories, leads to an estimated 2,300 Gg of methane emissions from natural gas production (0.42% of gross gas production). PMID:24043804

  13. Detection of marine methane emissions with AVIRIS band ratios

    Microsoft Academic Search

    Eliza S. Bradley; Ira Leifer; Dar A. Roberts; Philip E. Dennison; Libe Washburn

    2011-01-01

    The relative source contributions of methane (CH4) have high uncertainty, creating a need for local-scale characterization in concert with global satellite measurements. However, efforts towards methane plume imaging have yet to provide convincing results for concentrated sources. Although atmospheric CH4 mapping did not motivate the Airborne Visible\\/Infrared Imaging Spectrometer (AVIRIS) design, recent studies suggest its potential for studying concentrated CH4

  14. Methane emissions from rice fields: The effects of climatic and agricultural factors. Final report, March 1, 1994--April 30, 1997

    SciTech Connect

    Khalil, M.A.K. [Portland State Univ., OR (United States). Dept. of Physics] [Portland State Univ., OR (United States). Dept. of Physics; Rasmussen, R.A. [Oregon Graduate Institute, Portland, OR (United States). Dept. of Environmental Science and Engineering] [Oregon Graduate Institute, Portland, OR (United States). Dept. of Environmental Science and Engineering

    1997-10-01

    The work reported was performed for the purpose of refining estimates of methane emissions from rice fields. Research performed included methane flux measurements, evaluation of variables affecting emissions, compilation of a data base, and continental background measurements in China. The key findings are briefly described in this report. Total methane emissions, seasonal patterns, and spatial variability were measured for a 7-year periods. Temperature was found to be the most important variable studies affecting methane emissions. The data archives for the research are included in the report. 5 refs., 6 figs.

  15. Methane emission measurements in a cattle grazed pasture: A comparison of four methods

    NASA Astrophysics Data System (ADS)

    Tallec, Tiphaine; Klumpp, Katja; Darsonville, Olivier; Hensen, Adrian; Rochette, Yvanne

    2015-04-01

    Methane (CH4) is considered to be the second main contributor to the global greenhouse gas effect, with major CH4 emissions originating from livestock. Accurate measurements from ruminating herds are required to improve emission coefficients used in national emission inventories, and to evaluate mitigation strategies. Here we evaluated the reliability of eddy covariance technique (EC), for continuous CH4 measurements over a grazed field plot. Analyzer reliability of eddy covariance technique was tested against field scale measurements with the SF6 tracer technique [1], Gaussian plume model [2] and emission factors [3]. Results indicate a good agreement between methods. However, a systematic underestimation of EC data appeared when the distance between the source (ruminating heifers) and EC set-up (mast) was increased. A two-dimensional footprint density function allowed to correct for the dilution effect on measured CH4 and led to a good agreement with results based on the SF6 technique (on average 74 and 78 g CH4 head-1 day-1 (24 h) over the grazing experiment, respectively). Estimations of the CH4 budgets for the whole grazing season were in line with estimates (i.e. emission coefficients) based on feed intake and animal live weight as well as SF6 technique.

  16. METHOD FOR ESTIMATING METHANE EMISSIONS FROM UNDERGROUND COAL MINES: PRELIMINARY FINDINGS

    EPA Science Inventory

    The paper discusses the development of an improved method for estimating global methane (CH4) emissions from underground coal mining. ince emissions data presently not available for surface mines, this method is currently restricted to underground mines. The EPA has embarked on a...

  17. GLOBAL METHANE EMISSIONS FROM MINOR ANTHROPOGENIC SOURCES AND BIOFUEL COMBUSTION IN RESIDENTIAL STOVES (JOURNAL)

    EPA Science Inventory

    Most global methane (CH4) budgets have failed to include emissions from a diverse group of minor anthropogenic sources. Individually, these minor sources emit small quantities of CH4, but collectively, their contributions to the budget may be significant. In this paper, CH4 emiss...

  18. Technical options for the mitigation of direct methane and nitrous oxide emissions from livestock – a review

    Technology Transfer Automated Retrieval System (TEKTRAN)

    While livestock production accounts for a sizeable share of global greenhouse gas emissions, numerous technical options have been identified to mitigate these emissions. In this review, a subset of these options which have proven to be effective are discussed. These include measures to reduce methan...

  19. High methane emissions from a midlatitude reservoir draining an agricultural watershed

    EPA Science Inventory

    To assess the magnitude of methane (CH4) emissions from reservoirs in mid-latitude agricultural regions, we measured CH4 and carbon dioxide (CO2) emission rates from William H. Harsha Lake, an agricultural impacted reservoir located in southwestern Ohio, USA, over a thirteen mont...

  20. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 1: EXECUTIVE SUMMARY

    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...

  1. 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...

  2. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 13: CHEMICAL INJECTION PUMPS

    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...

  3. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 9: UNDERGROUND PIPELINES

    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...

  4. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 6: VENTED & COMBUSTION SOURCE SUMMARY

    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...

  5. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 11: COMPRESSOR DRIVER EXHAUST

    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...

  6. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 3: GENERAL METHODOLOGY

    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...

  7. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 14: GLYCOL DEHYDRATORS

    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...

  8. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 12: PNEUMATIC DEVICES

    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...

  9. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 2: TECHNICAL REPORT

    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...

  10. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 15: GAS-ASSISTED GLYCOL PUMPS

    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...

  11. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 4: STATISTICAL METHODOLOGY

    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...

  12. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 8: EQUIPMENT LEAKS

    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...

  13. 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...

  14. SIMULATION OF METHANE EMISSIONS FROM DAIRY FARMS TO ASSESS GREENHOUSE GAS REDUCTION STRATEGIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As a sector, agriculture is reported to be the third greatest contributor to atmospheric methane (CH**4) in the U.S., emitting one-quarter of total emissions. Primary sources of CH**4 emission on dairy farms are the animals and manure storage, with smaller contributions from field-applied manure, fe...

  15. Crop Management Affecting Methane Emissions from Irrigated and Rainfed Rice in Central Java (Indonesia)

    Microsoft Academic Search

    P. Setyanto; A. K. Makarim; A. M. Fagi; R. Wassmann; L. V. Buendia

    2000-01-01

    Methane (CH4) emissions were determined from 1993 to 1998 using an automated closed chamber technique in irrigated and rainfed rice. In Jakenan (Central Java), the two consecutive crops encompass a gradient from low to heavy rainfall (wet season crop) and from heavy to low rainfall (dry season crop), respectively. Rainfed rice was characterized by very low emission at the onset

  16. Estimation of methane sources and sinks by inverse modelling using GOSAT observations

    NASA Astrophysics Data System (ADS)

    Locatelli, Robin; Bousquet, Philippe; Saunois, Marielle

    2015-04-01

    Since the nineties, inverse modeling by assimilating measurements into a chemical transport model (CTM) has been used to derive sources and sinks of atmospheric trace gases. More recently, the high global warming potential of methane (CH4) caught the attention of several research groups. Indeed, the diversity and the variability of methane sources induce high uncertainty on the present and the future evolution of CH4 budget. Historically, inverse problems have been limited by the lack of observations but, the increasing of available measurement data (satellite data, high frequency measurement, FTIR spectrometry,...) gradually supplements this issue. However, the use of different types of observations is a challenge for current inversions. Do these different datasets derive consistent methane fluxes using inverse modelling ? Moreover, recent studies have highlighted the need for improvements in the accuracy of the atmospheric circulations in chemical transport model: a bad representation of the atmospheric transport may derive wrong methane fluxes. Consequently, we investigate here these two main issues (consistency between inversions using different datasets and transport model errors) by comparing an ensemble of methane inversions using : - different versions of the transport model used in the inverse system - different observation data sets (GOSAT observations and surface measurements) Moreover, these different inversions have been run for recent years, which allow us to investigate the inter-annual variability of methane sources and sinks. In particular, two years of strong methane emissions have been highlighted in 2007 and in 2010. These anomalies have been mainly attributed to anomalies in the Tropics and in China, where major climate events have been observed and where economic development is carrying on with a fast pace, even if emissions reported in inventories are overestimated.

  17. Emission of Methane by Eudrilus eugeniae and Other Earthworms from Brazil

    PubMed Central

    Depkat-Jakob, Peter S.; Hunger, Sindy; Schulz, Kristin; Brown, George G.; Tsai, Siu M.

    2012-01-01

    Earthworms emit denitrification-derived nitrous oxide and fermentation-derived molecular hydrogen. The present study demonstrated that the earthworm Eudrilus eugeniae, obtained in Brazil, emitted methane. Other worms displayed a lesser or no capacity to emit methane. Gene and transcript analyses of mcrA (encoding the alpha subunit of methyl-CoM reductase) in gut contents of E. eugeniae suggested that Methanosarcinaceae, Methanobacteriaceae, and Methanomicrobiaceae might be associated with this emission. PMID:22344639

  18. A three-year study of controls on methane emissions from two Michigan peatlands

    Microsoft Academic Search

    Robert D. Shannon; Jeffrey R. White

    1994-01-01

    We investigate temporal changes in methane emissions over a three-year period from two peatlands in Michigan. Mean daily fluxes ranged from 0.6–68.4 mg CH4 m-2d-1 in plant communities dominated by Chamaedaphne calyculata, an eficaceous shrub, to 11.5–209 mg CH4 m-2d-1 in areas dominated by plants with aerenchymatous tissues, such as Carex oligosperma and Scheuchzeria palustris. Correlations between methane flux and

  19. Urban sources and emissions of nitrous oxide and methane in southern California, USA

    NASA Astrophysics Data System (ADS)

    Townsend-Small, A.; Pataki, D.; Tyler, S. C.; Czimczik, C. I.; Xu, X.; Christensen, L. E.

    2012-12-01

    Anthropogenic activities have resulted in increasing levels of greenhouse gases, including carbon dioxide, methane, and nitrous oxide. While global and regional emissions sources of carbon dioxide are relatively well understood, methane and nitrous oxide are less constrained, particularly at regional scales. Here we present the results of an investigation of sources and emissions of methane and nitrous oxide in Los Angeles, California, USA, one of Earth's largest urban areas. The original goal of the project was to determine whether isotopes are useful tracers of agricultural versus urban nitrous oxide and methane sources. For methane, we found that stable isotopes (carbon-13 and deuterium) and radiocarbon are good tracers of biogenic versus fossil fuel sources. High altitude observations of methane concentration, measured continuously using tunable laser spectroscopy, and isotope ratios, measured on discrete flask samples using mass spectrometry, indicate that the predominant methane source in Los Angeles is from fossil fuels, likely from "fugitive" emissions from geologic formations, natural gas pipelines, oil refining, or power plants. We also measured nitrous oxide emissions and isotope ratios from urban (landscaping and wastewater treatment) and agricultural sources (corn and vegetable fields). There was no difference in nitrous oxide isotope ratios between the different types of sources, although stable isotopes did differ between nitrous oxide produced in oxic and anoxic wastewater treatment tanks. Our nitrous oxide flux data indicate that landscaped turfgrass emits nitrous oxide at rates equivalent to agricultural systems, indicating that ornamental soils should not be disregarded in regional nitrous oxide budgets. However, we also showed that wastewater treatment is a much greater source of nitrous oxide than soils regionally. This work shows that global nitrous oxide and methane budgets are not easily downscaled to regional, urban settings, which has implications for cities and states, such as California, looking to reduce their overall greenhouse gas footprints.

  20. Rice cultivation and methane emission: Documentation of distributed geographic data sets

    NASA Technical Reports Server (NTRS)

    Matthews, Elaine; John, Jasmin; Fung, Inez

    1994-01-01

    High-resolution global data bases on the geographic and seasonal distribution of rice cultivation and associated methane emission, compiled by Matthews et al., were archived for public use. In addition to the primary data sets identifying location, seasonality, and methane emission from rice cultivation, a series of supporting data sets is included, allowing users not only to replicate the work of Matthews et al. but to investigate alternative cultivation and emission scenarios. The suite of databases provided, at 1 latitude by 1 longitude resolution for the globe, includes (1) locations of rice cultivation, (2) monthly arrays of actively growing rice areas, (3) countries and political subdivisions, and (4) monthly arrays of methane emission from rice cultivation. Ancillary data include (1) a listing, by country, of harvested rice areas and seasonal distribution of crop cycles and (2) country names and codes. Summary tables of zonal/monthly distributions of actively growing rice areas and of methane emissions are presented. Users should consult original publications for complete discussion of the data bases. This short paper is designed only to document formats of the distributed information and briefly describe the contents of the data sets and their initial application to evaluating the role of rice cultivation in the methane budget.

  1. Does Juncus effusus enhance methane emissions from grazed pastures on peat?

    NASA Astrophysics Data System (ADS)

    Henneberg, A.; Elsgaard, L.; Sorrell, B. K.; Brix, H.; Petersen, S. O.

    2015-06-01

    Methane (CH4) emissions from drained organic soils are generally low, but internal gas transport in aerenchymatous plants may result in local emission hotspots. In a paired-sample field study at three different sites we measured fluxes of CH4 with static chambers from adjacent sampling quadrats with and without Juncus effusus during four field campaigns. At all three sites, CH4 was observed in the soil at all sampling depths (5-100 cm), and in most cases both above and below the groundwater table. During spring, local maxima suggested methanogenesis took place above the water table at all three sites. We found significant CH4 emissions at all three sites, but emission controls were clearly different. Across the three sites, average emission rates (±1 SE) for sampling quadrats with and without J. effusus were 1.47 ± 0.28 and 1.37 ± 0.33 mg CH4 m-2 h-1 respectively, with no overall effect of J. effusus on CH4 emissions, but a significant effect at one of the three sites. At this site, local CH4 maxima were closer to the soil surface than at the other sites, and the upper soil layers were dryer. This could have affected both root CH4 accessibility and CH4 oxidation respectively, and together with limited gas diffusivity in the soil column, cause elevated CH4 emissions from J. effusus. We conclude that aerenchymatous plants has the potential to act as point sources of CH4 from drained peatlands, but more studies on the specific conditions under which there is an effect, are needed before the results can be used in modelling of CH4 emissions.

  2. Mobile Laboratory Observations of Methane Emissions in the Barnett Shale Region.

    PubMed

    Yacovitch, Tara I; Herndon, Scott C; Pétron, Gabrielle; Kofler, Jonathan; Lyon, David; Zahniser, Mark S; Kolb, Charles E

    2015-07-01

    Results of mobile ground-based atmospheric measurements conducted during the Barnett Shale Coordinated Campaign in spring and fall of 2013 are presented. Methane and ethane are continuously measured downwind of facilities such as natural gas processing plants, compressor stations, and production well pads. Gaussian dispersion simulations of these methane plumes, using an iterative forward plume dispersion algorithm, are used to estimate both the source location and the emission magnitude. The distribution of emitters is peaked in the 0-5 kg/h range, with a significant tail. The ethane/methane molar enhancement ratio for this same distribution is investigated, showing a peak at ?1.5% and a broad distribution between ?4% and ?17%. The regional distributions of source emissions and ethane/methane enhancement ratios are examined: the largest methane emissions appear between Fort Worth and Dallas, while the highest ethane/methane enhancement ratios occur for plumes observed in the northwestern potion of the region. Individual facilities, focusing on large emitters, are further analyzed by constraining the source location. PMID:25751617

  3. Modeling and Measurements of Atmospheric Methane at Four Corners, NM

    NASA Astrophysics Data System (ADS)

    Costigan, K. R.; Lindenmaier, R.; Dubey, M. K.

    2014-12-01

    Methane (CH4) fugitive emissions from fossil energy mining remain highly uncertain and scrutinized with the rapid expansion in domestic production by hydraulic fracturing. Top down observational studies of reported bottom up inventories are limited, but the latter may be biased low. We focus on the Four Corners region of the Southwestern United States, a region with extensive coal bed methane production, to verify its current emissions. At our site we measured methane over a range of scales using ground-based, in-situ instruments and a Fourier Transform Spectrometer (FTS), which is part of the Total Carbon Column Observing Network (TCCON). Measurements of CH4 produced much higher concentrations of methane in this rural area than previously expected. The diurnal variation and wind direction dependence in the CH4 concentrations suggest a source location tied to topographically induced winds and consistent with oil and gas production. This paper presents the results of WRF-Chem simulations that are performed to simulate methane concentrations in this region. Emissions from the Emissions Database for Global Atmospheric Research (EDGAR) indicate large CH4 emissions, associated with the gas production and distribution sector, in one 0.1 x 0.1 degree grid cell within the region and these emissions are employed in the simulations. A series of six simulations are run at two-month intervals during 2012. Each simulates a six-day time series to demonstrate the diurnal and seasonal characteristics of the methane concentrations that would be expected at the FTS location, from the sources reported in the EDGAR data set. The results of these simulations will be presented, along with the implications for interpretation of the FTS measurements. We will also interpret our FTS measurements of ethane (C2H6), which is emitted only from fossil fuel mining, to attribute leaks.

  4. Quantification of methane emissions from 15 Danish landfills using the mobile tracer dispersion method.

    PubMed

    Mønster, Jacob; Samuelsson, Jerker; Kjeldsen, Peter; Scheutz, Charlotte

    2015-01-01

    Whole-site methane emissions from 15 Danish landfills were assessed using a mobile tracer dispersion method with either Fourier transform infrared spectroscopy (FTIR), using nitrous oxide as a tracer gas, or cavity ring-down spectrometry (CRDS), using acetylene as a tracer gas. The landfills were chosen to represent the different stages of the lifetime of a landfill, including open, active, and closed covered landfills, as well as those with and without gas extraction for utilisation or flaring. Measurements also included landfills with biocover for oxidizing any fugitive methane. Methane emission rates ranged from 2.6 to 60.8 kg h(-1), corresponding to 0.7-13.2 g m(-2)d(-1), with the largest emission rates per area coming from landfills with malfunctioning gas extraction systems installed, and the smallest emission rates from landfills closed decades ago and landfills with an engineered biocover installed. Landfills with gas collection and recovery systems had a recovery efficiency of 41-81%. Landfills where shredder waste was deposited showed significant methane emissions, with the largest emission from newly deposited shredder waste. The average methane emission from the landfills was 154 tons y(-1). This average was obtained from a few measurement campaigns conducted at each of the 15 landfills and extrapolating to annual emissions requires more measurements. Assuming that these landfills are representative of the average Danish landfill, the total emission from Danish landfills were calculated at 20,600 tons y(-1), which is significantly lower than the 33,300 tons y(-1) estimated for the national greenhouse gas inventory for 2011. PMID:25442105

  5. Integrating Source Apportionment Tracers into a Bottom-up Inventory of Methane Emissions in the Barnett Shale Hydraulic Fracturing Region.

    PubMed

    Townsend-Small, Amy; Marrero, Josette E; Lyon, David R; Simpson, Isobel J; Meinardi, Simone; Blake, Donald R

    2015-07-01

    A growing dependence on natural gas for energy may exacerbate emissions of the greenhouse gas methane (CH4). Identifying fingerprints of these emissions is critical to our understanding of potential impacts. Here, we compare stable isotopic and alkane ratio tracers of natural gas, agricultural, and urban CH4 sources in the Barnett Shale hydraulic fracturing region near Fort Worth, Texas. Thermogenic and biogenic sources were compositionally distinct, and emissions from oil wells were enriched in alkanes and isotopically depleted relative to natural gas wells. Emissions from natural gas production varied in ?(13)C and alkane ratio composition, with ?D-CH4 representing the most consistent tracer of natural gas sources. We integrated our data into a bottom-up inventory of CH4 for the region, resulting in an inventory of ethane (C2H6) sources for comparison to top-down estimates of CH4 and C2H6 emissions. Methane emissions in the Barnett are a complex mixture of urban, agricultural, and fossil fuel sources, which makes source apportionment challenging. For example, spatial heterogeneity in gas composition and high C2H6/CH4 ratios in emissions from conventional oil production add uncertainty to top-down models of source apportionment. Future top-down studies may benefit from the addition of ?D-CH4 to distinguish thermogenic and biogenic sources. PMID:26148556

  6. Methane emission by termites: Impacts on the self-cleansing mechanisms of the atmosphere

    SciTech Connect

    Mugedo, J.Z.A. [Maseno Univ. College (Kenya)

    1996-12-31

    Termites are reported to emit large quantities of methane, carbon dioxide, carbon monoxide, hydrogen and dimethyl sulfide. The emission of other trace gases, namely C{sub 2} to C{sub 10} hydrocarbons, is also documented. We have carried out, both in the field and in the laboratory, measurements of methane emissions by Macrotermes subhyalinus (Macrotermitinae), Trinervitermes bettonianus (Termitinae), and unidentified Cubitermes and Microcerotermes species. Measured CH{sub 4} field flux rates ranged from 3.66 to 98.25g per m{sup 2} of termite mound per year. Laboratory measurements gave emission rates that ranged from 14.61 to 165.05 mg CH{sub 4} per termite per year. Gaseous production in all species sampled varied both within species and from species to species. Recalculated global emission of methane from termites was found to be 14.0 x 10{sup 12} g CH{sub 4}, per year. From our study, termites contribution to atmospheric methane content is between 1.11% and 4.25% per year. This study discusses the greenhouse effects as well as photochemical disposal of methane in the lower atmosphere in the tropics and the impacts on the chemistry of HO{sub x} systems and CL{sub x} cycles.

  7. Archaeal abundance in post-mortem ruminal digesta may help predict methane emissions from beef cattle.

    PubMed

    Wallace, R John; Rooke, John A; Duthie, Carol-Anne; Hyslop, Jimmy J; Ross, David W; McKain, Nest; de Souza, Shirley Motta; Snelling, Timothy J; Waterhouse, Anthony; Roehe, Rainer

    2014-01-01

    Methane produced from 35 Aberdeen-Angus and 33 Limousin cross steers was measured in respiration chambers. Each group was split to receive either a medium- or high-concentrate diet. Ruminal digesta samples were subsequently removed to investigate correlations between methane emissions and the rumen microbial community, as measured by qPCR of 16S or 18S rRNA genes. Diet had the greatest influence on methane emissions. The high-concentrate diet resulted in lower methane emissions (P < 0.001) than the medium-concentrate diet. Methane was correlated, irrespective of breed, with the abundance of archaea (R = 0.39), bacteria (-0.47), protozoa (0.45), Bacteroidetes (-0.37) and Clostridium Cluster XIVa (-0.35). The archaea:bacteria ratio provided a stronger correlation (0.49). A similar correlation was found with digesta samples taken 2-3 weeks later at slaughter. This finding could help enable greenhouse gas emissions of large animal cohorts to be predicted from samples taken conveniently in the abattoir. PMID:25081098

  8. Large methane emission upon spring thaw from natural wetlands in the northern permafrost region

    SciTech Connect

    Song, Changchun [Chinese Academy of Sciences; Xu, Xiaofeng [ORNL; Sun, Xiaoxin [Chinese Academy of Sciences; Tian, Hanqin [Auburn University, Auburn, Alabama; Sun, Li [Chinese Academy of Sciences; Miao, Yuqing [Chinese Academy of Sciences; Wang, Xianwei [Chinese Academy of Sciences; Guo, Yuedong [Chinese Academy of Sciences

    2012-01-01

    The permafrost carbon climate feedback is one of the major mechanisms in controlling the climate ecosystem interactions in northern high latitudes. Of this feedback, methane (CH4) emission from natural wetlands is critically important due to its high warming potential. The freeze thaw transition has been confirmed to play an important role in annual CH4 budget, yet the magnitude of this effect is uncertain. An intensive field campaign was carried out in the Sanjiang Plain, Northeast China to estimate the CH4 emission in the spring freeze thaw transition period. The observation concluded that a large CH4 source was caused by spring thaw; the maximum hourly emission rate was 48.6 g C m 2 h 1, more than three orders of the regularly observed CH4 emission rate in the growing season. In some sporadically observed 'hot spots', the spring thawing effect contributed to a large CH4 source of 31.3 10.1 g C m 2, which is approximately 80% of the previously calculated annual CH4 emission in the same study area. If our results are typical for natural wetlands in the Northern Hemisphere permafrost region, we estimate a global CH4 source strength of 0.5 1.0 Tg C (1 Tg =1012 g) caused by spring thaw in the Northern Hemisphere permafrost region in the year 2011. Combining with available satellite and flask data, a regional extrapolation reaches a temporal pattern of CH4 emission during 2003 2009 which is consistent with recently observed changes in atmospheric CH4 concentration in the high latitudes. This suggests that the CH4 emission upon spring thaw in the high latitudes might be enhanced by the projected climate warming. These findings indicate that the spring thawing effect is an important mechanism in the permafrost carbon climate feedback and needs to be incorporated in Earth system models.

  9. Effects of vegetation on the emission of methane from submerged paddy soil

    Microsoft Academic Search

    A. Holzapfel-Pschorn; R. Conrad; W. Seiler

    1986-01-01

    Summary  Methane emission rates from rice-vegetated paddy fields followed a seasonal pattern different to that of weed-covered or unvegetated\\u000a fields. Presence of rice plants stimulated the emission of CH4 both in the laboratory and in the field. In unvegetated paddy fields CH4 was emitted almost exclusively by ebullition. By contrast, in rice-vegetated fields more than 90% of the CH4 emission was

  10. The temperature response of methane emission in Arctic wet sedge tundra

    NASA Astrophysics Data System (ADS)

    Lim, Edward; Zona, Donatella

    2015-04-01

    Since the last glacial maximum Arctic tundra soils have acted as an important carbon sink, having accumulated carbon under cold, anaerobic conditions (Zona et al. 2009). Several studies indicate that recent climate warming has altered this balance, with the Arctic tundra now posited to be a significant annual source of atmospheric methane (CH4) (McGuire et al. 2012). Nonetheless, the response of Arctic tundra CH4 fluxes to continued climate warming remains uncertain. Laboratory and field studies indicate that CH4 fluxes are temperature sensitive, thus accurate calculation of the temperature sensitivity is vital for the prediction of future CH4 emission. For this, the increase in reaction rate over a 10°C range (Q10) is frequently used, with single fixed Q10 values (between 2 and 4) commonly incorporated into climate-carbon cycle models. However, the temperature sensitivity of CH4 emission can vary considerably depending on factors such as vegetation composition, water table and season. This promotes the use of spatially and seasonally variable Q10 values for accurate CH4 flux estimation under different future climate change scenarios. This study investigates the temperature sensitivity (Q10) of Arctic tundra methane fluxes, using an extensive number of soil cores (48) extracted from wet sedge polygonal tundra (Barrow Experimental Observatory, Alaska). 'Wet' and 'dry' cores were taken from the centre and raised perimeter of ice-wedge polygons, where the water tables are 0cm and -15cm respectively. Cores were incubated in two controlled environment chambers (University of Sheffield, UK) for 12 weeks under different thaw depth treatments (control and control + 6.8cm), water tables (surface and -15cm), and CO2 concentrations (400ppm and 850ppm) in a multifactorial manner. Chamber temperature was gradually increased from -5°C to 20°C, then gradually decreased to -5°C, with each temperature stage lasting one week. Average CH4 fluxes from 'dry' cores were consistently low and did not change significantly with temperature, indicating that CH4 emission from drier Arctic tundra soils is not particularly temperature sensitive. Average CH4 emission from 'wet' cores increased with increasing temperature between -5°C and 20°C. Interestingly, continued increases in average CH4 emission as chamber temperature decreased (20°C to 0°C) were observed. Importantly, when chamber temperature was increased (-5°C to 20°C), average CH4 emission in the 'wet' cores was consistently lower at the end of each week-long temperature stage compared to at the start. This suggests that the response of CH4 emission to climate warming might acclimate. Overall, this study is critical for refining the temperature sensitivity of Arctic tundra CH4 emission, and thus improving model predictions of the response of CH4 fluxes to climate change. References McGuire, AD; Christensen, TR; Hayes, D. et al. (2012). An assessment of the carbon balance of Arctic tundra: comparisons among observations, process models, and atmospheric inversions. Biogeosciences. Vol.9, p.3185-3204, doi:10.5194/bg-9-3185-2012. Zona, D; Oechel, WC; Kochendorfer, J. et al. (2009). Methane fluxes during the initiation of a large-scale water table manipulation experiment in the Alaskan Arctic tundra. Global Biogeochemical Cycles. Vol.23, GB2013, doi:10.1029/2009GB003487.

  11. Detection and Monitoring of Changing Natural Methane Emissions in the Arctic

    NASA Astrophysics Data System (ADS)

    Bruhwiler, L.; Sweeney, C.; Dlugokencky, E. J.; Miller, J. B.; Karion, A.; Miller, C. E.

    2012-12-01

    Climate models suggest that the future Arctic climate will continue to warm and become wetter as well. This implies increased emissions of CH4 from wetlands, however, the future of Arctic hydrology is uncertain given expected melting of permafrost. In addition, vast stores of organic carbon are thought to be frozen in Arctic soils; as much as 1,700 billion tonnes of carbon, several times the amount emitted by fossil fuel use to date and about equal to known coal reserves. If mobilized to the atmosphere, this carbon would have significant impacts on global climate, especially if emitted as CH4. NOAA ESRL, Environment Canada, and other agencies have collected observations of greenhouse gases in the Arctic and the rest of the world for at least several decades. Analysis of this data does not currently support increased Arctic emissions of CO2 or CH4. However, it is difficult to detect changes in Arctic emissions because of transport from lower latitudes and high inter-annual variability. Arctic surface emissions are also especially difficult to detect from space, and current satellite platforms do not provide useful information about greenhouse gas budgets in the lower Arctic troposphere. Modeling/assimilation systems, such as NOAA's CarbonTracker-CH4 system can help untangle the Arctic budget and trends of greenhouse gases. On the other hand, the CarbonTracker is dependent on assumptions about prior fluxes and wetland distributions and source estimates are highly uncertain. We address the plausibility of monitoring the Arctic greenhouse gas emission trends. How large would Arctic emission trends have to be before they could be identified in network observations? What spatial information could be recovered? How would the spatial density of observations affect our ability to perceive and attribute trends in Arctic emissions? Could emission have already been increasing during the close of the 20th century? Trends in emissions need to be large before they can be discerned in network observations; our calculations show that emissions of methane must increase by at least 5TgCH4/yr to be seen in a 10-year observational record. The current NASA CARVE mission has the potential to improve prior flux estimates by providing information on how small scale emission processes can be translated to regional scales by a combination of ground-based and aircraft platform measurements of atmospheric concentrations and important surface state variables, and we provide an update on lessons learned so far from the CARVE mission.

  12. Measurements of methane emissions from landfills using mobile plume method with trace gas and cavity ring-down spectroscopy

    NASA Astrophysics Data System (ADS)

    Mønster, J.; Kjeldsen, P.; Scheutz, C.

    2012-04-01

    Methane is emitted to the atmosphere from both anthropogenic and natural sources. One of the major anthropogenic sources is methane produced by bacteria in anaerobic environments such as rice pads and landfills. Land filling has for many years been the preferred waste disposal method, resulting in a large methane production with a large contribution to the global increase in atmospheric green house gas concentration. Several steps have been taken to reduce the emission of methane from landfills. In order to validate the effect of these steps, a measurement method is needed to quantify methane emissions with a large spatial variation. One method is to use a highly sensitive and fast analytical method, capable of measuring the atmospheric concentration methane downwind from emission areas. Combined with down-wind measurements of a trace gas, emitted at a controlled mass flow rate, the methane emission can be calculated. This method is called the mobile plume method, as the whole plume is measured by doing several transects. In the current study a methane/acetylene analyzer with cavity ring-down spectroscopy detection (Picarro, G2203) was used to estimate methane from a number of Danish landfills. We measured at both active and closed landfills and investigated the difference in methane emission. At landfills where the emissions could have more than one origin, the source strength of the different emission areas was determined by accurate trace gas positioning and choosing appropriate wind speed and measurement distance. To choose these factors, we addressed the uncertainties and limitations of the method with respect to the configuration of the trace gas bottles and the distance between the emission area and the measurement points. Composting of organic material in large piles was done at several of the investigated landfills and where possible, the methane emission from this partly anaerobic digestion was measured as a separate emission.

  13. Lab-assay for estimating methane emissions from deep-pit swine manure storages.

    PubMed

    Andersen, D S; Van Weelden, M B; Trabue, S L; Pepple, L M

    2015-08-15

    Methane emission is an important tool in the evaluation of manure management systems due to the potential impact it has on global climate change. Field procedures used for estimating methane emission rates require expensive equipment, are time consuming, and highly variable between farms. The purpose of this paper is to report a simple laboratory procedure for estimating methane emission from stored manure. The test developed was termed a methane production rate (MPR) assay as it provides a short-term biogas production measurement. The MPR assay incubation time is short (3d), requires no sample preparation in terms of inoculation or dilution of manure, is incubated at room temperature, and the manure is kept stationary. These conditions allow for high throughput of samples and were chosen to replicate the conditions within deep-pit manure storages. In brief, an unaltered aliquot of manure was incubated at room temperature for a three-days to assay the current rate of methane being generated by the manure. The results from this assay predict an average methane emission factor of 12.2 ± 8.1 kg CH4 head(-1) yr(-1) per year, or about 5.5 ± 3.7 kg CH4 per finished animal, both of which compare well to literature values of 5.5 ± 1.1 kg CH4 per finished pig for deep-pit systems (Liu et al., 2013). The average methane flux across all sites and months was estimated to be 22 ± 17 mg CH4 m(-2)-min(-1), which is within literature values for deep-pit systems ranging from 0.24 to 63 mg CH4 m(-2)-min(-1) (Park et al., 2006) and similar to the 15 mg CH4 m(-2)-min(-1) estimated by (Zahn et al., 2001). PMID:25996623

  14. On the detection of strong emissions of methane in the Arctic using spectral measurements from IASI and GOSAT

    NASA Astrophysics Data System (ADS)

    Bourakkadi, Zakia; Payan, Sébastien; Bureau, Jérôme

    2014-05-01

    Boreal ecosystems store significant quantities of organic carbon (C) for thousands of years. Most are presently sequestered in permafrost. In recent years, several studies highlighted that climate warming and thawing of permafrost in the Arctic acts on the mobilization of old stored carbon (c) and contribute to a sustained release of methane (CH4) to the atmosphere [1],[2],[3]. Because methane is an important greenhouse gas, it is necessary to estimate his sources and sinks in the Arctic. The objective of this study is to evaluate and quantify methane strong emission in this region of the globe using spectral measurements from two satellite instruments: IASI-MetOp and TANSO-FTS. The Infrared Atmospheric Sounding Interferometer (IASI) is a Fourier transform spectrometer coupled with an integrated imaging system that observes and measures infrared radiation emitted by the Earth and the atmosphere in the spectral range 645-2760cm-1, which covered the methane ?4 and ?3 absorption band[4]. IASI provides global Earth's coverage twice a day and delivers about 1 300 000 spectra per day[5]. The second instrument which we will use in this study is the Thermal And Near-infrared Sensor for Carbon Observation-Fourier Transform Spectrometer (TANSO-FTS), it has a wide TIR band (5,5-14,3?m)which contain the methane ?4absorption band.TANSO-FTS completes one revolution in about 100 minutes and it comes back to the same location in 3 days period. Over these 3 days, FTS takes 56 000 measurements covering the entire globe[6]. To have a good estimation of methane emission above the Arctic, we must exploit a vast amount of spectral information from IASI and TANSO-FTS. But it is well known that performing line-by-line radiative transfer model is a time-consuming process. So, if we need to exploit large data we have to look fast method. In this work, we will use a simple approach based on the Singular Value Decomposition (SVD) to identify spectra over large source of methane. A more accurate algorithm will be used next to perform an accurate retrieval of methane vertical column. References [1] N. Shakhova, I. Semiletov, A. Salyuk, V. Yusupov, D. Kosmach, O.Gustafsson.: Extensive Methane venting to the atmosphere from sediments of the East Siberian Arctic shelf, SCIENCE 5 March 2010, Vol 327. [2] K. Negandhi, I. Laurion, M. J. Whiticar, P. E. Galand, X. X. Connie Lovejoy.: Small thaw ponds: An unaccounted source of methane in the canadian high Arctic, PLOS ONE november 2013/ vol 8/issue 11/e78204. [3] J. T. Crawford, R. G. Striegl, K. P. Wickland, M . Dornblaser, and E. Stanley.: Emissions of carbon dioxide and methane from a headwater stream network of interior Alaska, Journal of Giophysical Recherch : Biogeosciences, VOL, 118, 482-494, doi:10.1002/jgrg,20034, 2013. [4] A. Razavi, C. Clerbaux, C. Wespes, L. Clarisse, D. Hurtmans, S. Payan, C. Camy-Peyret and P.F. Coheur.: Characterization of methane retrievals from the IASI space-borne sounder , Atmos. Chem. Phys., 9,7889-7899, 2009. [5] C. Clerbaux, A. Boynard, L. Clarisse, M. George, J. Hadji-Lazaro, H. Herbin, D. Hurtmans, M. Pommier, A. Razavi, S. Turquety, C. Wespes and P.-F. Coheur.: Monitoring of atmospheric composition using the thermal infrared IASI/MetOp sounder, Atmos. Chem. Phys., 9, 6041-6054, 2009. [6] T . Yokota, Y. Yoshida, N. Eguchi, Y. Ota, T. Tanaka, H. Watanabe and S. Makasyutov.: Global concentrations of CO2 and CH4 retrieved from GOSAT : First Preliminary Results, SOLA, 2009, Vol. 5, 160-163, doi:10.2151/sola.2009-041.

  15. Methane emission from mud volcanoes in eastern Azerbaijan

    Microsoft Academic Search

    G. Etiope; A. Feyzullayev; C. L. Baciu; A. V. Milkov

    2004-01-01

    Methane (CH4) flux to the atmosphere was measured from gas vents and, for the first time, from soil microseepage at four quiescent mud volcanoes and one ``everlasting fire'' in eastern Azerbaijan. Mud volcanoes show different activity of venting craters, gryphons, and bubbling pools, with CH4 fluxes ranging from less than one to hundreds of tons per year. Microseepage CH4 flux

  16. Recent findings on methane emissions from vegetation (Invited)

    Microsoft Academic Search

    F. Keppler; T. Roeckmann; I. Vigano; J. T. Hamilton; A. McLeod

    2009-01-01

    Three years ago, Keppler et al. (2006) reported from laboratory experiments that living plants, plant litter and the structural plant component pectin emit methane to the atmosphere under aerobic conditions. These observations caused considerable controversy amongst the scientific community and the general public because of their far-reaching implications for two main reasons. Firstly, it is generally accepted knowledge that the

  17. US Methane Emissions 1990-2020: Inventories, Projections, and Opportunities for Reductions

    NSDL National Science Digital Library

    1999-01-01

    The Environmental Protection Agency has released the 1999 report on national methane emissions, entitled "US Methane Emissions 1990-2020: Inventories, Projections, and Opportunities for Reductions." The report (EPA 430-R-99-013) may be downloaded in .pdf format either as a complete document or in separate sections: Cover, Executive Summary, and Introduction, 361K; Landfills and Appendix II, 130K; Natural Gas Systems and Appendix III, 145K; Coal and Appendix IV, 101K; Livestock Manure and Appendix V, 130K; and Enteric Fermentation and Appendix VI, 80K. Further information is provided on the Reports page.

  18. A model for methane production in sewers.

    PubMed

    Chaosakul, Thitirat; Koottatep, Thammarat; Polprasert, Chongrak

    2014-09-19

    Most sewers in developing countries are combined sewers which receive stormwater and effluent from septic tanks or cesspools of households and buildings. Although the wastewater strength in these sewers is usually lower than those in developed countries, due to improper construction and maintenance, the hydraulic retention time (HRT) could be relatively long and resulting considerable greenhouse gas (GHG) production. This study proposed an empirical model to predict the quantity of methane production in gravity-flow sewers based on relevant parameters such as surface area to volume ratio (A/V) of sewer, hydraulic retention time (HRT) and wastewater temperature. The model was developed from field survey data of gravity-flow sewers located in a peri-urban area, central Thailand and validated with field data of a sewer system of the Gold Coast area, Queensland, Australia. Application of this model to improve construction and maintenance of gravity-flow sewers to minimize GHG production and reduce global warming is presented. PMID:24967565

  19. 40 CFR Table W - 5 of Subpart W of Part 98-Default Methane Emission Factors for Liquefied Natural Gas (LNG) Storage

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Methane Emission Factors for Liquefied Natural Gas (LNG) Storage W Table W...GREENHOUSE GAS REPORTING Petroleum and Natural Gas Systems Definitions. Pt...Methane Emission Factors for Liquefied Natural Gas (LNG) Storage LNG...

  20. 40 CFR Table W - 5 of Subpart W of Part 98-Default Methane Emission Factors for Liquefied Natural Gas (LNG) Storage

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Methane Emission Factors for Liquefied Natural Gas (LNG) Storage W Table W...GREENHOUSE GAS REPORTING Petroleum and Natural Gas Systems Definitions. Pt...Methane Emission Factors for Liquefied Natural Gas (LNG) Storage LNG...

  1. Wetland methane modelling over the Scandinavian Arctic: Performance of current land-surface models

    NASA Astrophysics Data System (ADS)

    Hayman, Garry; Quiquet, Aurélien; Gedney, Nicola; Clark, Douglas; Friend, Andrew; George, Charles; Prigent, Catherine

    2014-05-01

    Wetlands are generally accepted as being the largest, but least well quantified, single natural source of CH4, with global emission estimates ranging from 100-231 Tg yr-1 [1] and for which the Boreal and Arctic regions make a significant contribution [2, 3]. The recent review by Melton et al. [4] has provided a summary of the current state of knowledge on the modelling of wetlands and the outcome of the WETCHIMP model intercomparison exercise. Melton et al. found a large variation in the wetland areas and associated methane emissions from the participating models and varying responses to climate change. In this paper, we report results from offline runs of two land surface models over Scandinavia (JULES, the Joint UK Land Environment Simulator [5, 6] and HYBRID8 [7]), using the same driving meteorological dataset (CRU-NCEP) for the period from January 1980 to December 2010. Although the two land surface models are very different, both models have used a TOPMODEL approach to derive the wetland area and have similar parameterisations of the methane wetland emissions. We find that both models give broadly similar results. They underestimate the wetland areas over Northern Scandinavia, compared to remote sensing and map-based datasets of wetlands [8]. This leads to lower predicted methane emissions compared to those observed on the ground and from aircraft [9]. We will present these findings and identify possible reasons for the underprediction. We will show the sensitivity to using the observed wetland areas to improve the methane emission estimates. References [1] Denman, K., et al.,: Couplings Between Changes in the Climate System and Biogeochemistry, In Climate Change 2007: The Physical Science Basis, Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, United Kingdom, 2007; [2] Smith, L. C., et al.: Siberian peatlands a net carbon sink and global methane source since the early Holocene, Science, 303, 353-356, doi:10.1126/science.1090553, 2004; [3] Zhuang, Q., et al.: CO2 and CH4 exchanges between land ecosystems and the atmosphere in northern high latitudes over the 21st century, Geophysical Research Letters, 33, doi:10.1029/2006gl026972, 2006; [4] Melton, J.R., et al.: Present state of global wetland extent and wetland methane modelling: conclusions from a model inter-comparison project (WETCHIMP), Biogeosciences, 10, 753-788, doi:10.5194/bg-10-753-2013, 2013; [5] Best, M. J., et al.: The Joint UK Land Environment Simulator (JULES), model description - Part 1: Energy and water fluxes, Geoscientific Model Development, 4, 677-699, doi:10.5194/gmd-4-677-2011, 2011; [6] Clark, D.B., et al.: The Joint UK Land Environment Simulator (JULES), Model description - Part 2: Carbon fluxes and vegetation. Geoscientific Model Development, 4, 701-722, doi:10.5194/gmd-4-701-2011, 2011; [7] Friend, A.D., and N.Y. Kiang: Land surface model development for the GISS GCM: Effects of improved canopy physiology on simulated climate. J. Climate, 18, 2883-2902, doi:10.1175/JCLI3425.1, 2005; [8] Prigent, C., et al.: Changes in land surface water dynamics since the 1990s and relation to population pressure, Geophys. Res. Lett., 39, L08403, doi:10.1029/2012GL051276, 2012; [9] O'Shea, S., et al.: Methane and carbon dioxide fluxes from the European Arctic wetlands during the MAMM project, paper in preparation.

  2. Use of multi-transition-metal-ion-exchanged zeolite 13X catalysts in methane emissions abatement

    SciTech Connect

    Hui, K.S.; Chao, C.Y.H.; Kwong, C.W.; Wan, M.P. [Department of Mechanical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)

    2008-04-15

    Methane is a potent greenhouse gas. It has a global warming potential (GWP) 23 times greater than carbon dioxide. Reducing methane emissions would lead to substantial economic and environmental benefits. This study investigated the performance of multi-transition-metal-(Cu, Cr, Ni, and Co)-ion-exchanged zeolite 13X catalysts in methane emissions abatement. The catalytic activity in methane combustion using multi-ion-exchanged catalysts was studied with different parameters including the molar percentage of metal loading, the space velocity, and the inlet methane concentration under atmospheric pressure and at a relatively low reaction temperature of 500 C. The performance of the catalysts was determined in terms of the apparent activation energy, the number of active sites of the catalyst, and the BET surface area of the catalyst. This study showed that multi-ion-exchanged catalysts outperformed single-ion-exchanged and acidified 13X catalysts and that lengthening the residence time led to a higher methane conversion percentage. The enhanced catalytic activity in the multi-ion-exchanged catalysts was attributed to the presence of exchanged transition ions instead of acid sites in the catalyst. The catalytic activity of the catalysts was influenced by the metal loading amount, which played an important role in affecting the apparent activation energy for methane combustion, the active sites, and the BET surface area of the catalyst. Increasing the amount of metal loading in the catalyst decreased the apparent activation energy for methane combustion and also the BET surface area of the catalyst. An optimized metal loading amount at which the highest catalytic activity was observed due to the combined effects of the various factors was determined. (author)

  3. Methane emissions by alpine plant communities in the Qinghai-Tibet Plateau.

    PubMed

    Cao, Guangmin; Xu, Xingliang; Long, Ruijun; Wang, Qilan; Wang, Changting; Du, Yangong; Zhao, Xinquan

    2008-12-23

    For the first time to our knowledge, we report here methane emissions by plant communities in alpine ecosystems in the Qinghai-Tibet Plateau. This has been achieved through long-term field observations from June 2003 to July 2006 using a closed chamber technique. Strong methane emission at the rate of 26.2+/-1.2 and 7.8+/-1.1microg CH4 m-2h-1 was observed for a grass community in a Kobresia humilis meadow and a Potentilla fruticosa meadow, respectively. A shrub community in the Potentilla meadow consumed atmospheric methane at the rate of 5.8+/-1.3microg CH4 m-2h-1 on a regional basis; plants from alpine meadows contribute at least 0.13Tg CH4 yr-1 in the Tibetan Plateau. This finding has important implications with regard to the regional methane budget and species-level difference should be considered when assessing methane emissions by plants. PMID:18755657

  4. Single-well Modeling of Coalbed Methane Production

    E-print Network

    Martynova, Elena

    2014-01-14

    The presented study concerns the unconventional coal bed methane (CBM) fields that imply peculiarity of their evaluation. The theoretical basis of the CBM field development is briefly described, most widely known models of changes in the properties...

  5. Single-well Modeling of Coalbed Methane Production 

    E-print Network

    Martynova, Elena

    2014-01-14

    The presented study concerns the unconventional coal bed methane (CBM) fields that imply peculiarity of their evaluation. The theoretical basis of the CBM field development is briefly described, most widely known models of changes in the properties...

  6. Relative contributions of hypoxia and natural gas extraction to atmospheric methane emissions from Lake Erie

    NASA Astrophysics Data System (ADS)

    Disbennett, D. A.; Townsend-Small, A.; Bourbonniere, R.; Mackay, R.

    2013-12-01

    Reduced oxygen availability in lakes due to summer stratification can create conditions suitable for methanogenic activity, which ultimately contributes to atmospheric methane emissions. Lake Erie has persistent low oxygen conditions in bottom waters during summer, which contributes to methane production through anaerobic organic matter respiration. Lake Erie also has substantial subsurface natural gas deposits that are currently being extracted in Canadian waters. We hypothesized that the lake would be a source of methane to the atmosphere in late summer, prior to fall turnover, and that natural gas wells and pipelines would contribute to additional methane emissions from resource extraction areas in Canadian waters. Initial sampling was conducted at a total of 20 sites in central and western Lake Erie during early September 2012. Sites were selected to collect samples from a wide range of environmental conditions in order to better establish the baseline flux from these areas. We selected an array of sites in the offshore environment, sites from a very shallow bay and sites within the Canadian gas fields. Air samples were gathered using floating flux chambers tethered to the research vessel. Dissolved gas water samples were collected using a Van Dorn bottle. We found a consistent positive flux of methane throughout the lake during late summer, with flux rates adjacent to natural gas pipelines up to an order of magnitude greater than elsewhere. Stable isotope analysis yielded results that were not entirely expected. The ?13C of surface samples from areas of fossil fuel extraction and suspected biogenic sources were very similar, likely due to oxidation of methane in the water column. Additional sampling occurred during 2012 and 2013 concentrating on bottom waters and surface fluxes which should allow us to further constrain sources of CH4 from Lake Erie. This project is an effort to constrain the global warming potential of hypoxia in the Great Lakes, and secondly it is an attempt to constrain fugitive emissions of methane from resource extraction areas within Lake Erie. These two sources of methane may contribute to increased greenhouse gas emission rates regionally. In addition, constraining fugitive methane emissions will be an important part of assessing the climate impacts of the coal-to-gas transition.

  7. Warmer temperature accelerates methane emissions from the Zoige wetland on the Tibetan Plateau without changing methanogenic community composition

    PubMed Central

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

    2015-01-01

    Zoige wetland, locating on the Tibet Plateau, accounts for 6.2% of organic carbon storage in China. However, the fate of the organic carbon storage in the Zoige wetland remains poorly understood despite the Tibetan Plateau is very sensitive to global climate change. As methane is an important greenhouse gas and methanogenesis is the terminal step in the decomposition of organic matter, understanding how methane emissions from the Zoige wetland is fundamental to elucidate the carbon cycle in alpine wetlands responding to global warming. In this study, microcosms were performed to investigate the effects of temperature and vegetation on methane emissions and microbial processes in the Zoige wetland soil. A positive correlation was observed between temperature and methane emissions. However, temperature had no effect on the main methanogenic pathway—acetotrophic methanogenesis. Moreover, methanogenic community composition was not related to temperature, but was associated with vegetation, which was also involved in methane emissions. Taken together, these results indicate temperature increases methane emissions in alpine wetlands, while vegetation contributes significantly to methanogenic community composition and is associated with methane emissions. These findings suggest that in alpine wetlands temperature and vegetation act together to affect methane emissions, which furthers a global warming feedback loop. PMID:26109512

  8. Warmer temperature accelerates methane emissions from the Zoige wetland on the Tibetan Plateau without changing methanogenic community composition.

    PubMed

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

    2015-01-01

    Zoige wetland, locating on the Tibet Plateau, accounts for 6.2% of organic carbon storage in China. However, the fate of the organic carbon storage in the Zoige wetland remains poorly understood despite the Tibetan Plateau is very sensitive to global climate change. As methane is an important greenhouse gas and methanogenesis is the terminal step in the decomposition of organic matter, understanding how methane emissions from the Zoige wetland is fundamental to elucidate the carbon cycle in alpine wetlands responding to global warming. In this study, microcosms were performed to investigate the effects of temperature and vegetation on methane emissions and microbial processes in the Zoige wetland soil. A positive correlation was observed between temperature and methane emissions. However, temperature had no effect on the main methanogenic pathway-acetotrophic methanogenesis. Moreover, methanogenic community composition was not related to temperature, but was associated with vegetation, which was also involved in methane emissions. Taken together, these results indicate temperature increases methane emissions in alpine wetlands, while vegetation contributes significantly to methanogenic community composition and is associated with methane emissions. These findings suggest that in alpine wetlands temperature and vegetation act together to affect methane emissions, which furthers a global warming feedback loop. PMID:26109512

  9. Fugitive methane emissions from natural, urban, agricultural, and energy-production landscapes of eastern Australia

    NASA Astrophysics Data System (ADS)

    Kelly, Bryce F. J.; Iverach, Charlotte P.; Lowry, Dave; Fisher, Rebecca E.; France, James L.; Nisbet, Euan G.

    2015-04-01

    Modern cavity ringdown spectroscopy systems (CRDS) enable the continuous measurement of methane concentration. This allows for improved quantification of greenhouse gas emissions associated with various natural and human landscapes. We present a subset of over 4000 km of continuous methane surveying along the east coast of Australia, made using a Picarro G2301 CRDS, deployed in a utility vehicle with an air inlet above the roof at 2.2 mAGL. Measurements were made every 5 seconds to a precision of <0.5 ppb for CH4. These surveys were undertaken during dry daytime hours and all measurements were moisture corrected. We compare the concentration of methane in the near surface atmosphere adjacent to open-cut coal mines, unconventional gas developments (coal seam gas; CSG), and leaks detected in cities and country towns. In areas of dryland crops the median methane concentration was 1.78 ppm, while in the irrigation districts located on vertisol soils the concentration was as low as 1.76 ppm, which may indicate that these soils are a sink for methane. In the Hunter Valley, New South Wales, open-cut coal mining district we mapped a continuous 50 km interval where the concentration of methane exceeded 1.80 ppm. The median concentration in this interval was 2.02 ppm. Peak readings were beyond the range of the reliable measurement (in excess of 3.00 ppm). This extended plume is an amalgamation of plumes from 17 major pits 1 to 10 km in length. Adjacent to CSG developments in the Surat Basin, southeast Queensland, only small anomalies were detected near the well-heads. Throughout the vast majority of the gas fields the concentration of methane was below 1.80 ppm. The largest source of fugitive methane associated with CSG was off-gassing methane from the co-produced water holding ponds. At one location the down wind plume had a cross section of approximately 1 km where the concentration of methane was above 1.80 ppm. The median concentration within this section was 1.82 ppm, with a peak reading of 2.11 ppm. The ambient air methane concentration was always higher in urban environments compared to the surrounding countryside. Along one major road in Sydney we mapped an interval that extended for 6 km where the concentration was greater than 1.80 ppm. The median concentration in this interval was 1.90 ppm, with a peak reading of 1.97 ppm. This high reading in an urban setting is most likely due to leaks from the domestic gas distribution system. Methane leaks were detected in all country towns. Our measurements show that at the point of resource extraction the methane emission footprint of CSG is smaller than that of open-cut coal mining. However, leaking gas from urban centers must be added to the fugitive emissions of CSG to calculate the total fugitive emission footprint of CSG, which may therefore not be as low as claimed in the national greenhouse gas accounts. Our results highlight the need for additional continuous monitoring of methane emissions from all sectors, and for the full life-cycle of energy resources to be considered.

  10. Trends of non-methane hydrocarbons (NMHC) emissions in Beijing during 2002-2013

    NASA Astrophysics Data System (ADS)

    Wang, M.; Shao, M.; Chen, W.; Lu, S.; Liu, Y.; Yuan, B.; Zhang, Q.; Zhang, Q.; Chang, C.-C.; Wang, B.; Zeng, L.; Hu, M.; Yang, Y.; Li, Y.

    2014-07-01

    Non-methane hydrocarbons (NMHCs) play a critical role in the photochemical production of ozone (O3) and organic aerosols. Obtaining an accurate understanding on NMHC emission trends is essential for predicting air quality changes and evaluating the effectiveness of current control measures. In this study, we evaluated temporal trends in NMHC emissions in Beijing based on ambient measurements during the summer at an urban site in Beijing from 2002 to 2013. In contrast to the results of the most recent inventory (Multi-resolution Emission Inventory for China, MEIC), which reported that total NMHC emissions increased at a rate of ~4% yr-1, mixing ratios of NMHCs measured at this urban site displayed an obvious decrease (~30%) during the last decade. A Positive Matrix Factorization (PMF) model was applied to the NMHC measurements for source apportionment, and the results showed a decrease in the concentrations contributed by transportation-related sources to total NMHC emissions by 66% during 2004-2012, which was comparable to the relative decline of 65% reported by the MEIC inventory. This finding indicates that the implementation of stricter emissions standards and control measures has been effective for reducing transportation-related NMHC emissions. In addition, the PMF results suggested that there were no significant temporal changes in NMHC concentrations from paint and solvent use during 2004-2012, in contrast with the rapid rate of increase (27.5% yr-1) reported by the MEIC inventory. To re-evaluate the NMHC emissions trends for paint and solvent use, annual variations in NMHC / NOx ratios were compared between ambient measurements and the MEIC inventory. In contrast to the significant rise in NMHC / NOx ratios from the inventory, the measured ratios declined by 14% during 2005-2012. However, the inferred NMHC / NOx ratios based on PMF results exhibited a comparable decline of 11% to measurements. These results indicate that the increase rate for NMHC emissions from paint and solvent use in Beijing might be overestimated in the current inventory; therefore, additional research is necessary to verify the NMHC emission trends for this source.

  11. Trends of non-methane hydrocarbons (NMHC) emissions in Beijing during 2002-2013

    NASA Astrophysics Data System (ADS)

    Wang, M.; Shao, M.; Chen, W.; Lu, S.; Liu, Y.; Yuan, B.; Zhang, Q.; Zhang, Q.; Chang, C.-C.; Wang, B.; Zeng, L.; Hu, M.; Yang, Y.; Li, Y.

    2015-02-01

    Non-methane hydrocarbons (NMHCs) play a critical role in the photochemical production of ozone (O3) and organic aerosols. Obtaining an accurate understanding on temporal trends of NMHC emissions is essential for predicting air quality changes and evaluating the effectiveness of current control measures. In this study, we evaluated temporal trends of anthropogenic NMHC emissions during August in Beijing based on ambient measurements during selected summer periods at an urban site in Beijing from 2002 to 2013. In the contrast to the results from the most recent inventory (Multi-resolution Emission Inventory for China, MEIC), which reported that anthropogenic NMHC emissions during August increased by 28% from 2004 to 2012, whereas mixing ratios of NMHCs measured at this urban site decreased by 37% during the same time period. A positive matrix factorization (PMF) model was applied to these NMHC measurements for source apportionment. The results showed that the relative contributions of vehicular exhaust and gasoline evaporation to measured NMHC concentrations decreased by 66% during August from 2004 to 2012, comparable to the relative decline of 67% for transportation-related NMHC emissions reported by the MEIC inventory. This finding indicates that the implementation of stricter emissions standards for new vehicles and specific control measures for in-use vehicles has been effective for reducing transportation-related NMHC emissions. In addition, the PMF results suggested that there were no significant temporal changes in NMHC concentrations from solvent use and industry during August from 2004 to 2012, in contrast with the rapid rate of increase (8.8% yr-1) reported by the MEIC inventory. To re-evaluate the NMHC emissions trends for solvent use and industry, annual variations in NMHC / NOx ratios were compared between ambient measurements at the PKU site and the MEIC inventory. In contrast to the significant rise in NMHC / NOx ratios from the MEIC inventory, the measured NMHC / NOx ratios declined by 14% during August from 2005 to 2012. The inferred NMHC / NOx ratios based on PMF results exhibited a comparable decline of 11% to measured ratios. These results indicate that the increase rate for NMHC emissions from solvent use and industry in Beijing might be overestimated in the current inventory; therefore, additional research is necessary to verify the NMHC emission trends for this source.

  12. Methane emission rates from the Arctic coastal tundra at Barrow are log-normally distributed: Is this a tail that wags climate?

    Microsoft Academic Search

    J. C. von Fischer; R. Rhew

    2008-01-01

    Over the past two growing seasons, we have conducted >200 point measurements of methane emission and ecosystem respiration rates on the Arctic coastal tundra within the Barrow Environmental Observatory. These measures reveal that methane emission rates are log-normally distributed, but ecosystem respiration rates are normally distributed. The contrast in frequency distributions indicates that methane and carbon dioxide emission rates respond

  13. Monitoring methane emission of mud volcanoes by seismic tremor measurements: a pilot study

    NASA Astrophysics Data System (ADS)

    Albarello, D.; Palo, M.; Martinelli, G.

    2012-12-01

    A new approach for estimating methane emission at mud volcanoes is here proposed based on measurements of the seismic tremor on their surface. Data obtained at the Dashgil mud volcano in Azerbaijan reveal the presence of energy bursts characterized by well-determined features (i.e. waveforms, spectra and polarization properties) that can be associated with bubbling at depth. Counting such events provides a possible tool for monitoring gas production in the reservoir, thus minimizing logistic troubles and representing a cheap and effective alternative to more complex approaches. Specifically, we model the energy bursts as the effect of resonant gas bubbles at depth. This modelling allows to estimate the dimension of the bubbles and, consequently, the gas outflow from the main conduit in the assumption that all emissions from depth occur by bubble uprising. The application of this model to seismic events detected at the Dashgil mud volcano during three sessions of measurements carried out in 2006 and 2007 provides gas flux estimates that are in line with those provided by independent measurements at the same structure. This encouraging result suggests that the one here proposed could be considered a new promising, cheap and easy to apply tool for gas flux measurements in bubbling gas seepage areas.

  14. Methane emissions by goats consuming Sericea lespedeza at different feeding frequencies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Twenty-four yearling Boer (50 or 87.5%) × Spanish wethers were used to assess effects of different sources of fresh forage and dry hay on ruminal methane emission. Treatments were a legume (Sericea lespedeza, Lespedeza cuneata) high in condensed tannins (CT; 20 and 15% in fresh forage and hay, resp...

  15. The effect of a condensed tannin-containing forage on methane emission by goats1

    Microsoft Academic Search

    R. Puchala; B. R. Min; A. L. Goetsch; T. Sahlu

    2010-01-01

    The objective of this study was to com- pare methane emission by goats consuming the con- densed tannin-containing forage sericea lespedeza (Les- pedeza cuneata) or a mixture of crabgrass (Digitaria ischaemum) and Kentucky 31 tall fescue (Festuca arun- dinacea). Two groups of 12 Angora does (initial average BW = 41.5 ± 2.7 kg) that previously grazed a pasture of sericea

  16. Methane Emission by Goats Consuming Condensed Tannin-containing Forage at Different Frequencies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Twenty-four yearling Boer and Spanish wethers (33.5 ± 0.36 kg BW) were used in a 32-d experiment to assess effects of frequency of feeding condensed tannin (CT)-containing fresh sericea lespedeza (SL; Lespedeza cuneata) on ruminal methane (CH4) emission. Fresh SL (15.3% CT) was fed free-choice ever...

  17. Regionalization of Methane Emissions in the Amazon Basin with Multi-temporal Microwave Remote Sensing

    Microsoft Academic Search

    J. M. Melack; L. L. Hess; B. R. Forsberg; S. K. Hamilton; E. M. Novo

    2002-01-01

    Remote sensing of the Amazon basin with passive and active microwave techniques were applied to determine the temporally varying extent of inundation and associated vegetation, and used in conjunction with field measurements to calculate regional rates of methane emission from wetlands to the atmosphere. Monthly inundation areas were derived from analysis of the 37-GHz polarization difference observed by the Scanning

  18. Mitigation of methane and nitrous oxide emissions from animal operations: A review of manure management options

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This review analyzes published data on manure management practices used to mitigate methane (CH4) and nitrous oxide (N2O) emissions from animal operations. This is the second in a series of reports commissioned by the Food and Agriculture Organization of the United Nations to evaluate mitigation pra...

  19. TEMPORAL AND SPATIAL PATTERNS OF METHANE EMISSIONS FROM A RESERVOIR DRAINING AN AGRICULTURAL WATERSHED (abstract)

    EPA Science Inventory

    We used multiple approaches to characterize temporal and spatial patterns in methane (CH4) emissions from a mid-latitude reservoir (William H. Harsha Lake, Ohio, USA) draining an agricultural watershed. Weekly to monthly monitoring at six sites in the reservoir during a 13 month...

  20. TEMPORAL AND SPATIAL PATTERNS OF METHANE EMISSIONS FROM A RESERVOIR DRAINING AN AGRICULTURAL WATERSHED

    EPA Science Inventory

    We used multiple approaches to characterize temporal and spatial patterns in methane (CH4) emissions from a mid-latitude reservoir (William H. Harsha Lake, Ohio, USA) draining an agricultural watershed. Weekly to monthly monitoring at six sites in the reservoir during a 13 month...

  1. METHOD 25 - DETERMINATION OF TOTAL GASEOUS NON-METHANE ORGANIC EMISSIONS AS CARBON FROM STATIONARY SOURCES

    EPA Science Inventory

    Section 3.17 describes the procedures and specifications for determining volatile organic compounds as total gaseous non-methane organics from stationary sources. n emission sample is withdrawn from the stack at a constant rate through a heated filter and a chilled condensate tra...

  2. Methane emissions measured at two California landfills by OTM-10 and an acetylene tracer method

    EPA Science Inventory

    Methane emissions were measured at two municipal solid waste landfills in California using static flux chambers, an optical remote sensing approach known as vertical radial plume mapping (VRPM) using a tunable diode laser (TDL) and a novel acetylene tracer method. The tracer meth...

  3. Methane emission by goats consuming diets with different levels of condensed tannins from lespedeza

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Twenty-four yearling Boer x Spanish wethers (7/8 Boer; initial body weight [BW] of 34.1 plus/minus 1.02 kg) were used to determine effects on methane emission of dietary levels of a condensed tannin (CT)-containing forage, Kobe lespedeza (Lespedeza striata; K), and a forage very low in CT, sorghum-s...

  4. Airborne Ethane Observations in the Barnett Shale: Quantification of Ethane Flux and Attribution of Methane Emissions.

    PubMed

    Smith, Mackenzie L; Kort, Eric A; Karion, Anna; Sweeney, Colm; Herndon, Scott C; Yacovitch, Tara I

    2015-07-01

    We present high time resolution airborne ethane (C2H6) and methane (CH4) measurements made in March and October 2013 as part of the Barnett Coordinated Campaign over the Barnett Shale formation in Texas. Ethane fluxes are quantified using a downwind flight strategy, a first demonstration of this approach for C2H6. Additionally, ethane-to-methane emissions ratios (C2H6:CH4) of point sources were observationally determined from simultaneous airborne C2H6 and CH4 measurements during a survey flight over the source region. Distinct C2H6:CH4 × 100% molar ratios of 0.0%, 1.8%, and 9.6%, indicative of microbial, low-C2H6 fossil, and high-C2H6 fossil sources, respectively, emerged in observations over the emissions source region of the Barnett Shale. Ethane-to-methane correlations were used in conjunction with C2H6 and CH4 fluxes to quantify the fraction of CH4 emissions derived from fossil and microbial sources. On the basis of two analyses, we find 71-85% of the observed methane emissions quantified in the Barnett Shale are derived from fossil sources. The average ethane flux observed from the studied region of the Barnett Shale was 6.6 ± 0.2 × 10(3) kg hr(-1) and consistent across six days in spring and fall of 2013. PMID:26148554

  5. Path integrated optical remote sensing technique to estimate ammonia and methane gas emissions from CAFOs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The U.S. EPA recently demonstrated the open-path optical remote sensing technology to identify hot spots and estimate mass flux of fugitive gases from closed landfill. The objective of this research is to validate this technology for estimating ammonia and methane emission from concentrated animal f...

  6. Estimating ammonia and methane emissions from CAFOs using an open-path optical remote sensing technology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The U.S. EPA recently demonstrated the open-path optical remote sensing technology to identify hot spots and estimate mass flux of fugitive gases from closed landfill. The objective of this research is to validate this technology for estimating ammonia and methane emission from concentrated animal f...

  7. Reduction of ruminant methane emissions - a win-win-win opportunity for business, development, and the environment

    SciTech Connect

    Livingston, R. [Appropriate Technology International, Washington, DC (United States)

    1997-12-31

    This paper describes research efforts of The Global Livestock Producers Program (GLPP) in establishing self-sustaining enterprises for cost-effective technologies (i.e., animal nutrition and genetic improvement) and global methane emissions reductions in developing world nations. The US Environmental Protection Agency has funded several studies to examine the possibilities of reducing ruminant methane emissions in India, Tanzania, Bangladesh, and Brazil. The results of the studies showed that: (1) many developing countries` production systems are inefficient, and (2) great potential exists for decreasing global methane emissions through increasing animal productivity. From this effort, the GLPP established livestock development projects in India, Zimbabwe, and Tanzania, and is developing projects for Bangladesh, Nepal, and Brazil. The GLPP has developed a proven methodology for assessing ruminant methane and incorporating methane emissions monitoring into viable projects.

  8. Development of equations for predicting methane emissions from ruminants.

    PubMed

    Ramin, M; Huhtanen, P

    2013-04-01

    Ruminants contribute to global warming by releasing methane (CH4) gas by enteric fermentation. This has increased interest among animal scientists to develop and improve equations predicting CH4 production. The objectives of the current study were to collect a data set from respiration studies and to evaluate the effects of dietary and animal factors on CH4 production from diets that can safely be fed to dairy cows, using a mixed model regression analysis. Therefore, diets containing more than 75% concentrate on a dry matter (DM) basis were excluded from the analysis. The final data set included a total of 298 treatment means from 52 published papers with 207 cattle and 91 sheep diets. Dry matter intake per kilogram of body weight (DMIBW), organic matter digestibility estimated at the maintenance level of feeding (OMDm), and dietary concentrations of neutral detergent fiber (NDF), nonfiber carbohydrates (NFC), and ether extract (EE) were the variables of the best-fit equation predicting CH4 energy (CH4-E) as a proportion of gross energy intake (GE): CH4-E/GE (kJ/MJ)=-0.6 (±12.76) - 0.70 (±0.072) × DMIBW (g/kg) + 0.076 (±0.0118) × OMDm (g/kg) - 0.13 (±0.020) × EE (g/kg of DM) + 0.046 (±0.0097) × NDF (g/kg of DM) + 0.044 (±0.0094) × NFC (g/kg of DM), resulting in the lowest root mean square error adjusted for random study effect (adj. RMSE=3.26 kJ/MJ). Total CH4 production (L/d) in the cattle data set was closely related to DM intake. However, further inclusion of other variables improved the model: CH4 (L/d)=-64.0 (±35.0) + 26.0 (±1.02) × DM intake (kg/d) - 0.61 (±0.132) × DMI(2)(centered) + 0.25 (±0.051) × OMDm (g/kg) - 66.4 (±8.22) × EE intake (kg of DM/d) - 45.0 (±23.50) × NFC/(NDF + NFC), with adj. RMSE of 21.1 L/d. Cross-validation of the CH4-E/GE equation [observed CH4-E/GE=0.96 (±0.103) × predicted CH4-E/GE + 2.3 (±7.05); R(2)=0.85, adj. RMSE=3.38 kJ/MJ] indicated that differences in CH4 production between the diets could be predicted accurately. We conclude that feed intake is the main determinant of total CH4 production and that CH4-E/GE is negatively related to feeding level and dietary fat concentration and positively to diet digestibility, whereas dietary carbohydrate composition has only minor effects. PMID:23403199

  9. Processes involved in formation and emission of methane in rice paddies

    Microsoft Academic Search

    Helmut Schütz; Wolfgang Seiler; Ralf Conrad

    1989-01-01

    The seasonal change of the rates of production and emission of methane were determined under in-situ conditions in an Italian rice paddy in 1985 and 1986. The contribution to total emission of CH4 of plant-mediated transport, ebullition, and diffusion through the flooding water was quantified by cutting the plants and by trapping emerging gas bubbles with funnels. Both production and

  10. Emission and oxidation of methane in Equisetum fluviatile stands growing on organic sediment and sand bottoms

    Microsoft Academic Search

    Paula Kankaala; Irina Bergström

    2004-01-01

    Methane emission and rhizospheric CH4 oxidation were studied in stands of Equisetum fluviatile, a common cryptogam in boreal lakes. The experiment was performed in mesocosms with organic sediment or sand bottoms under natural variation of temperature and light using the light-oxic – dark-anoxic chamber (LO\\/DA) technique. Net CH4 emission from the organic sediment during the growing season varied between 3.4

  11. Methane emissions from newly created marshes in the drawdown area of the Three Gorges Reservoir

    NASA Astrophysics Data System (ADS)

    Chen, Huai; Wu, Yuyuan; Yuan, Xingzhong; Gao, Yongheng; Wu, Ning; Zhu, Dan

    2009-09-01

    The study aimed to understand the methane (CH4) emission and its controlling factors in the Three Gorges Reservoir Region and to explore its implication for large dams. We measured CH4 emissions from four vegetation stands in newly created marshes in the drawdown area of the Three Gorges Reservoir, China, in the summer of 2008. The results showed highly spatial variations of methane emissions among the four stands, with the smallest emission (0.25 ± 0.65 mg CH4 m-2 h-1) in the Juncus amuricus stand, and the greatest (14.9 ± 10.9 mg CH4 m-2 h-1) in the Scirpus triqueter stand. We found that the spatial variations of CH4 emissions are caused by difference in standing water depth and dissolved organic carbon (DOC). Results also showed a special seasonal variation of CH4 emissions in this area, i.e., maximal emissions in early July followed by a low and steady value before the winter flooding. The seasonality of CH4 emissions was found closely related to temperature and standing water depth. Because of the large area of the drawdown zones for global dam reservoirs and a large CH4 emission rate, such newly created marshes should not be neglected when estimating CH4 emissions from reservoirs.

  12. Estimation of waste water treatment plant methane emissions: methodology and results from a short campaign

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    This paper describes different methods to estimate methane emissions at different scales. These methods are applied to a waste water treatment plant (WWTP) located in Valence, France. We show that Fourier Transform Infrared (FTIR) measurements as well as Cavity Ring Down Spectroscopy (CRDS) can be used to measure emissions from the process to the regional scale. To estimate the total emissions, we investigate a tracer release method (using C2H2) and the Radon tracer method (using 222Rn). For process-scale emissions, both tracer release and chamber techniques were used. We show that the tracer release method is suitable to quantify facility- and some process-scale emissions, while the Radon tracer method encompasses not only the treatment station but also a large area around. Thus the Radon tracer method is more representative of the regional emissions around the city. Uncertainties for each method are described. Applying the methods to CH4 emissions, we find that the main source of emissions of the plant was not identified with certainty during this short campaign, although the primary source of emissions is likely to be from solid sludge. Overall, the waste water treatment plant represents a small part (3%) of the methane emissions of the city of Valence and its surroundings,which is in agreement with the national inventories.

  13. Toward a better understanding and quantification of methane emissions from shale gas development

    PubMed Central

    Caulton, Dana R.; Shepson, Paul B.; Santoro, Renee L.; Sparks, Jed P.; Howarth, Robert W.; Ingraffea, Anthony R.; Cambaliza, Maria O. L.; Sweeney, Colm; Karion, Anna; Davis, Kenneth J.; Stirm, Brian H.; Montzka, Stephen A.; Miller, Ben R.

    2014-01-01

    The identification and quantification of methane emissions from natural gas production has become increasingly important owing to the increase in the natural gas component of the energy sector. An instrumented aircraft platform was used to identify large sources of methane and quantify emission rates in southwestern PA in June 2012. A large regional flux, 2.0–14 g CH4 s?1 km?2, was quantified for a ?2,800-km2 area, which did not differ statistically from a bottom-up inventory, 2.3–4.6 g CH4 s?1 km?2. Large emissions averaging 34 g CH4/s per well were observed from seven well pads determined to be in the drilling phase, 2 to 3 orders of magnitude greater than US Environmental Protection Agency estimates for this operational phase. The emissions from these well pads, representing ?1% of the total number of wells, account for 4–30% of the observed regional flux. More work is needed to determine all of the sources of methane emissions from natural gas production, to ascertain why these emissions occur and to evaluate their climate and atmospheric chemistry impacts. PMID:24733927

  14. Methane Fluxes Between Terrestrial Ecosystems and the Atmosphere at Northern High Latitudes During the Past Century: A retrospective analysis with a process-based biogeochemistry model

    E-print Network

    Zhuang, Qianlai.

    We develop and use a new version of the Terrestrial Ecosystem Model (TEM) to study how rates of methane (CH4) emissions and consumption in high-latitude soils of the Northern Hemisphere have changed over the past century ...

  15. A Geochemical Model for the Origin of Methane on Titan

    NASA Astrophysics Data System (ADS)

    Glein, C. R.; Shock, E. L.

    2007-12-01

    The existence of methane in Titan's atmosphere has been a mystery for years [1]. The short photochemical lifetime of methane in the atmosphere suggests that methane is replenished from the interior. Observations by Cassini-Huygens have offered new insights into the origin of methane on Titan. These data have confirmed that Titan's methane is endogenic [2], consistent with geophysical models [3]. Today, an issue is the origin of methane on Titan in general. Why does Titan have methane in the first place? Here, we show that methane formation would have been unavoidable on early Titan. It is likely that Titan accreted materials similar to carbonaceous chondrites and comets, except for extreme volatiles in comets, such as carbon monoxide. Thus, we assume that Titan started with Fe-Ni metals and sulfides, silicates and oxides of the rock-forming elements, organic matter, carbon dioxide, methanol, and ammonia. After accretion, radiogenic heat would have melted ice, facilitating water-rock separation and interaction. Mineral dissolution and precipitation, along with acid-base reactions, would have been facile throughout differentiation, despite the low temperature. In contrast, most redox reactions, notably organic matter decomposition, would have been slow in cold aqueous solution. Eventually, the interior would have segregated into a muddy core, covered by a high-pressure ice layer, overlain by a salty ocean, capped by an ice shell [3]. The primordial muddy core would have been composed of phyllosilicates, organic matter, carbonates, sulfides, and presumably, metals. The early salty ocean would have been rich in sodium chloride and bicarbonate, in addition to methanol and ammonium salts. Methane would not have formed in hydrothermal systems at the ocean floor because the high-pressure ice layer would have inhibited hydrothermal circulation. Instead, we propose that methane is a byproduct of the thermal evolution of the core. Specifically, our core devolatilization hypothesis states that high temperatures driven by radioactive decay [4] changed the chemistry of the core via metamorphism. Preliminary calculations indicate that hydrous minerals recrystallize into anhydrous minerals by releasing water, which oxidizes Fe metal, producing dihydrogen (i.e., reducing conditions). In response, organic matter in the core is broken down into carbon-bearing solids, liquids, and gases, including methane. In time, methane can migrate into the ocean, where it can be trapped in clathrate hydrates and subsequently released into the atmosphere [3]. References: [1] Owen T.C. (2000) P&SS 48, 747-752. [2] Niemann H.B. et al. (2005) Nature 438, 779-784. [3] Tobie G. et al. (2006) Nature 440, 61-64. [4] Grasset O. et al. (2000) P&SS 48, 617-636.

  16. Do aircraft-based atmospheric observations indicate that anthropogenic methane emissions in the United States are larger than reported?

    NASA Astrophysics Data System (ADS)

    Kort, E. A.; Sweeney, C.; Andrews, A. E.; Dlugokencky, E. J.; Tans, P. P.; Hirsch, A.; Eluszkiewicz, J.; Nehrkorn, T.; Michalak, A. M.; Wofsy, S. C.

    2009-12-01

    Methane emissions over the United States are dominated by anthropogenic sources related to three major categories: fossil fuels (e.g. natural gas mining and distribution), landfills, and ruminants. Atmospheric signatures of these sources are evident in aircraft profiles, regularly showing enhancements of 50-100 ppb in the planetary boundary layer. Through a lagrangian particle dispersion model (LPDM), we directly link atmospheric methane measurements from NOAA’s aircraft program in 2004 with prior source fields, focusing on EDGAR32FT2000 and EDGARv4.0 for anthropogenic emissions. The LPDM employed is the Stochastic Time Inverted Lagrangian Transport model (STILT), driven by meteorological output from the Weather Research and Forecasting (WRF) model. Forward model runs indicate EDGAR32FT2000 is more consistent (despite larger point to point noise) with atmospheric data, particularly when assessing the shapes of vertical profiles, than EDGARv4.0. Simple scalar optimizations and inverse analyses suggest that emissions in the new EDGARv4.0 inventory, an inventory consistent with reported US EPA values, are too small.

  17. LOX/Methane Main Engine Igniter Tests and Modeling

    NASA Technical Reports Server (NTRS)

    Breisacher, Kevin J.; Ajmani, Kumund

    2008-01-01

    The LOX/methane propellant combination is being considered for the Lunar Surface Access Module ascent main engine propulsion system. The proposed switch from the hypergolic propellants used in the Apollo lunar ascent engine to LOX/methane propellants requires the development of igniters capable of highly reliable performance in a lunar surface environment. An ignition test program was conducted that used an in-house designed LOX/methane spark torch igniter. The testing occurred in Cell 21 of the Research Combustion Laboratory to utilize its altitude capability to simulate a space vacuum environment. Approximately 750 ignition test were performed to evaluate the effects of methane purity, igniter body temperature, spark energy level and frequency, mixture ratio, flowrate, and igniter geometry on the ability to obtain successful ignitions. Ignitions were obtained down to an igniter body temperature of approximately 260 R with a 10 torr back-pressure. The data obtained is also being used to anchor a CFD based igniter model.

  18. Determining methane emissions from biogas plants - Operational and meteorological aspects.

    PubMed

    Hrad, Marlies; Piringer, Martin; Huber-Humer, Marion

    2015-09-01

    A micrometeorological method, combining an inverse dispersion technique with path-integrated concentration measurements, was applied on an Austrian biogas plant over the period of more than one year to determine emissions of the whole plant. Measurement campaigns were conducted to characterize the emission response to operational activities (e.g. digestate management) and meteorological changes. When digestate storage tanks were filled, an average emission rate of 7.2kg CH4/h (approx. 4% of the calculated CH4 production) was determined, while 5.4kg CH4/h of emissions (approx. 3% of the calculated CH4 production) were quantified after the tanks had been emptied. It could be observed that besides the operation mode (e.g. filling level or agitation of the openly stored digestate, maintenance), the meteorological conditions such as wind speed and solar radiation (e.g. heat flux) can also affect the emission rate. PMID:26000833

  19. Constructing a Spatially Resolved Methane Emission Inventory for the Barnett Shale Region.

    PubMed

    Lyon, David R; Zavala-Araiza, Daniel; Alvarez, Ramón A; Harriss, Robert; Palacios, Virginia; Lan, Xin; Talbot, Robert; Lavoie, Tegan; Shepson, Paul; Yacovitch, Tara I; Herndon, Scott C; Marchese, Anthony J; Zimmerle, Daniel; Robinson, Allen L; Hamburg, Steven P

    2015-07-01

    Methane emissions from the oil and gas industry (O&G) and other sources in the Barnett Shale region were estimated by constructing a spatially resolved emission inventory. Eighteen source categories were estimated using multiple data sets, including new empirical measurements at regional O&G sites and a national study of gathering and processing facilities. Spatially referenced activity data were compiled from federal and state databases and combined with O&G facility emission factors calculated using Monte Carlo simulations that account for high emission sites representing the very upper portion, or fat-tail, in the observed emissions distributions. Total methane emissions in the 25-county Barnett Shale region in October 2013 were estimated to be 72,300 (63,400-82,400) kg CH4 h(-1). O&G emissions were estimated to be 46,200 (40,000-54,100) kg CH4 h(-1) with 19% of emissions from fat-tail sites representing less than 2% of sites. Our estimate of O&G emissions in the Barnett Shale region was higher than alternative inventories based on the United States Environmental Protection Agency (EPA) Greenhouse Gas Inventory, EPA Greenhouse Gas Reporting Program, and Emissions Database for Global Atmospheric Research by factors of 1.5, 2.7, and 4.3, respectively. Gathering compressor stations, which accounted for 40% of O&G emissions in our inventory, had the largest difference from emission estimates based on EPA data sources. Our inventory's higher O&G emission estimate was due primarily to its more comprehensive activity factors and inclusion of emissions from fat-tail sites. PMID:26148553

  20. Methane and carbon dioxide emission from two pig finishing barns.

    PubMed

    Ni, Ji-Qin; Heber, Albert J; Lim, Teng Teeh; Tao, Pei Chun; Schmidt, Amy M

    2008-01-01

    Agricultural activities are an important source of greenhouse gases. However, comprehensive, long-term, and high-quality measurement data of these gases are lacking. This article presents a field study of CH(4) and CO(2) emission from two 1100-head mechanically ventilated pig (Sus scrofa) finishing barns (B1 and B2) with shallow manure flushing systems and propane space heaters from August 2002 to July 2003 in northern Missouri. Barn 2 was treated with soybean oil sprinkling, misting essential oils, and misting essential oils with water to reduce air pollutant emissions. Only days with CDFB (complete-data-full-barn), defined as >80% of valid data during a day with >80% pigs in the barns, were used. The CH(4) average daily mean (ADM) emission rates were 36.2 +/- 2.0 g/d AU (ADM +/- 95% confidence interval; animal unit = 500 kg live mass) from B1 (CDFB days = 134) and 28.8 +/- 1.8 g/d AU from B2 (CDFB days = 131). The CO(2) ADM emission rates were 17.5 +/- 0.8 kg/d AU from B1 (CDFB days = 146) and 14.2 +/- 0.6 kg/d AU from B2 (CDFB days = 137). The treated barn reduced CH(4) emission by 20% (P < 0.01) and CO(2) emission by 19% (P < 0.01). The CH(4) and CO(2) released from the flushing lagoon effluent were equivalent to 9.8 and 4.1% of the CDFB CH(4) and CO(2) emissions, respectively. The emission data were compared with the literature, and the characteristics of CH(4) and CO(2) concentrations and emissions were discussed. PMID:18948452

  1. Methane oxidation behind reflected shock waves: Ignition delay times measured by pressure and flame band emission

    NASA Technical Reports Server (NTRS)

    Brabbs, T. A.; Robertson, T. F.

    1986-01-01

    Ignition delay data were recorded for three methane-oxygen-argon mixtures (phi = 0.5, 1.0, 2.0) for the temperature range 1500 to 1920 K. Quiet pressure trances enabled us to obtain delay times for the start of the experimental pressure rise. These times were in good agreement with those obtained from the flame band emission at 3700 A. The data correlated well with the oxygen and methane dependence of Lifshitz, but showed a much stronger temperature dependence (phi = 0.5 delta E = 51.9, phi = 1.0 delta = 58.8, phi = 2.0 delta E = 58.7 Kcal). The effect of probe location on the delay time measurement was studied. It appears that the probe located 83 mm from the reflecting surface measured delay times which may not be related to the initial temperature and pressure. It was estimated that for a probe located 7 mm from the reflecting surface, the measured delay time would be about 10 microseconds too short, and it was suggested that delay times less than 100 microsecond should not be used. The ignition period was defined as the time interval between start of the experimental pressure rise and 50 percent of the ignition pressure. This time interval was measured for three gas mixtures and found to be similar (40 to 60 micro sec) for phi = 1.0 and 0.5 but much longer (100 to 120) microsecond for phi = 2.0. It was suggested that the ignition period would be very useful to the kinetic modeler in judging the agreement between experimental and calculated delay times.

  2. Mitigation of methane and nitrous oxide emissions from animal operations: III. A review of animal management mitigation options

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The goal of this review was to analyze published data on animal management practices that mitigate enteric methane and nitrous oxide emissions from animal operations. The review is part of a series of reports evaluating methane and nitrous oxide mitigation practices for livestock operations commissi...

  3. Modelling simultaneous anaerobic methane and ammonium removal in a granular sludge reactor.

    PubMed

    Winkler, M-K H; Ettwig, K F; Vannecke, T P W; Stultiens, K; Bogdan, A; Kartal, B; Volcke, E I P

    2015-04-15

    Anaerobic nitrogen removal technologies offer advantages in terms of energy and cost savings over conventional nitrification-denitrification systems. A mathematical model was constructed to evaluate the influence of process operation on the coexistence of nitrite dependent anaerobic methane oxidizing bacteria (n-damo) and anaerobic ammonium oxidizing bacteria (anammox) in a single granule. The nitrite and methane affinity constants of n-damo bacteria were measured experimentally. The biomass yield of n-damo bacteria was derived from experimental data and a thermodynamic state analysis. Through simulations, it was found that the possible survival of n-damo besides anammox bacteria was sensitive to the nitrite/ammonium influent ratio. If ammonium was supplied in excess, n-damo bacteria were outcompeted. At low biomass concentration, n-damo bacteria lost the competition against anammox bacteria. When the biomass loading closely matched the biomass concentration needed for full nutrient removal, strong substrate competition occurred resulting in oscillating removal rates. The simulation results further reveal that smaller granules enabled higher simultaneous ammonium and methane removal efficiencies. The implementation of simultaneous anaerobic methane and ammonium removal will decrease greenhouse gas emissions, but an economic analysis showed that adding anaerobic methane removal to a partial nitritation/anammox process may increase the aeration costs with over 20%. Finally, some considerations were given regarding the practical implementation of the process. PMID:25697694

  4. Methane emissions from abandoned oil and gas wells in Pennsylvania: Data and analysis of seasonal variations

    NASA Astrophysics Data System (ADS)

    Miller, Alana

    2015-04-01

    Abandoned oil and gas (AOG) wells are a potential pathway for the migration of subsurface fluids such as methane to the atmosphere. There is little information on the emissions from these AOG wells, but measurements taken by Kang et al. 2014 show that methane emissions from AOG wells can be significant. Here the variability of direct measurements of methane fluxes from static flux chambers at AOG wells and control locations near the wells are reported. Variability of the methane flow rates (particularly from the high emitting wells) is of great interest to better understand the dynamics and net emissions of the wells. Rounds of measurements were therefore taken in July, August and October of 2013 and January, March, June, and October of 2014 to determine any seasonal variability in the methane flow rates. Additionally at two of the high emitting wells multiple measurements were taken within one day to determine the variability on shorter (hourly) timescales. Overall the high emitting wells (wells with flow rates>1E4 mg/hr of CH4) displayed only a small degree of variability compared to the low emitting wells. The order of magnitude variations for the wells go from 0 to 4 with most between 0 and 2. The order of magnitude variation also seems to have no relation to the number of times the well was sampled. Preliminary results indicate that the seasonal variability for low emitting wells is likely linked to microbial activity while variability for the high emitting wells is likely due to changes in some other pressure source.

  5. Methane emissions in two small shallow neotropical lakes: The role of temperature and trophic level

    NASA Astrophysics Data System (ADS)

    Palma-Silva, Cleber; Marinho, Cláudio Cardoso; Albertoni, Edélti Faria; Giacomini, Iara Bueno; Figueiredo Barros, Marcos Paulo; Furlanetto, Leonardo Marques; Trindade, Claudio Rossano Trindade; Esteves, Francisco de Assis

    2013-12-01

    It is estimated that lakes are responsible for up to 16% of global methane (CH4) emissions. Studying the CH4 concentrations and emissions in these environments is important to estimate the total regional production of CH4 and to understand the main factors related to these emissions. The aim of this study was to measure the CH4 emissions from two shallow polymictic lakes in southern Brazil and to evaluate the roles of temperature and trophic level in increasing these emissions. Temperature was positively correlated with CH4 concentration in the water column, bubble emissions and diffusion. Both lakes exhibited significant seasonal differences in water-column and sediment methane concentrations and diffusion. The eutrophic lake produced more bubble emissions [6868.95 (±7645.97) ?mol m-2 d-1 in winter and 11,251.10 (±10,160.92) ?mol m-2 d-1 in summer]. Water-column and sediment concentrations [19.92 (±11.74) ?mol L-1 and 1727.85 (±1581.19) ?mol g-1, respectively)] and diffusion [27,549.94 (±18,258.15) ?mol m-2 d-1] were also higher in summer than in winter in both lakes. All measured parameters were higher in the eutrophic lake, highlighting the maintenance of aquatic ecosystems in a low trophic state. Based on bubble emissions, the oligo-mesotrophic lake released an estimated 3142.8 g ha-1 yr-1 of CH4, while the eutrophic lake contributed 287,868.6 g ha-1 yr-1. Estimates of diffusive flux were higher: 41,832 g ha-1 yr-1 in summer for the oligo-mesotrophic lake and 1388.52 kg ha-1 yr-1 for the eutrophic lake. Our results show that shallow aquatic subtropical ecosystems are potential sources of atmospheric methane, and their contribution to global warming must be taken into account.

  6. Estimating the biogenic emissions of non-methane volatile organic compounds from the North Western Mediterranean vegetation of Catalonia, Spain.

    PubMed

    Parra, R; Gassó, S; Baldasano, J M

    2004-08-15

    An estimation of the magnitude of non-methane volatile organic compounds (NMVOCs) emitted by vegetation in Catalonia (NE of the Iberian Peninsula, Spain), in addition to their superficial and temporal distribution, is presented for policy and scientific (photochemical modelling) purposes. It was developed for the year 2000, for different time resolutions (hourly, daily, monthly and annual) and using a high-resolution land-use map (1-km2 squared cells). Several meteorological surface stations provided air temperature and solar radiation data. An adjusted mathematical emission model taking account of Catalonia's conditions was built into a geographic information system (GIS) software. This estimation uses the latest information, mainly relating to: (1) emission factors; (2) better knowledge of the composition of Catalonia's forest cover; and (3) better knowledge of the particular emission behaviour of some Mediterranean vegetal species. Results depict an annual cycle with increasing values in the March-April period with the highest emissions in July-August, followed by a decrease in October-November. Annual biogenic NMVOCs emissions reach 46.9 kt, with monoterpenes the most abundant species (24.7 kt), followed by other biogenic volatile organic compounds (e.g. alcohols, aldehydes and acetone) (16.3 kt), and isoprene (5.9 kt). These compounds signify 52%, 35% and 13%, respectively, of total emission estimates. Peak hourly total emission for a winter day could be less than 10% of the corresponding value for a summer day. PMID:15262170

  7. The effects of fire on biogenic emissions of methane and nitric oxide from wetlands

    NASA Technical Reports Server (NTRS)

    Levine, Joel S.; Cofer, Wesley R., III; Sebacher, Daniel I.; Rhinehart, Robert P.; Winstead, Edward L.; Sebacher, Shirley; Hinkle, C. Ross; Schmalzer, Paul A.; Koller, Albert M., Jr.

    1990-01-01

    Enhanced emissions of methane (CH4) and nitric oxide (NO) were measured following three controlled burns in a Florida wetlands in 1987 and 1988. Wetlands are the major global source of methane resulting from metabolic activity of methanogenic bacteria. Methanogens require carbon dioxide, acetate, or formate for their growth and the metabolic production of methane. All three water-soluble compounds are produced in large concentrations during biomass burning. Postfire methane emissions exceeded 0.15 g CH 4/sq m per day. Preburn and postburn measurements of soil nutrients indicate significant postburn increases in soil ammonium, from 8.35 to 13.49 parts per million (ppm) in the upper 5 cm of the Juncus marsh and from 8.83 to 23.75 ppm in the upper 5 cm of the Spartina marsh. Soil nitrate concentrations were found to decrease in both marshes after the fire. These measurements indicate that the combustion products of biomass burning exert an important 'fertilizing' effect on the biosphere and on the biogenic production of environmentally significant atmospheric gases.

  8. A study on characteristics of Methane emission from a periodically irrigated paddy field in Japan

    NASA Astrophysics Data System (ADS)

    Wakikuromaru, N.; Iwata, T.; Yagi, K.

    2014-12-01

    Methane (CH4) is generated by organic matter decomposition in the anaerobic soil. Paddy field is one of the most important eco-system in monsoon Asia. It is said that about 10% of CH4sources is paddy fields (IPCC AR4, 2007). In this study, methane emission from a single-rice crop field was estimated by long-term micrometeorological measurements. Methane emission was calculated by the aerodynamic gradient technique from January 2011 to August 2014. Intermittent water management was carried out during cultivation period at the observational site, HCH, located in Okayama, Japan. 3-days flood and 4-days drained condition were regularly repeated from late-June to early October. Seasonal variations of CH4flux for irrigation term from 2011 to 2013 were shown in Fig.1. Remarkably large fluxes were shown at early stage of irrigation term in 2011.It seemed to be caused by the relatively longer flooded condition that the first flooded period was 20 days. Flux in 2012 was smaller than in other year through the entire irrigation period. Rapid rise in flux for early August and gradual decrease between late August and September were shown in 2013. Fluxes under drained condition showed larger emission than under flooded condition. Cumulative CH4 emissions during cultivated period from 2011 to 2013 were estimated 15.7, 8.6, and 12.9 gC/m2, respectively.

  9. Monte Carlo model for electron degradation in methane gas

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Anil; Mukundan, Vrinda

    2015-06-01

    We present a Monte Carlo model for degradation of 1-10,000 eV electrons in an atmosphere of methane. The electron impact cross sections for CH4 are compiled and analytical representations of these cross sections are used as input to the model."Yield spectra", which provides information about the number of inelastic events that have taken place in each energy bin, is used to calculate the yield (or population) of various inelastic processes. The numerical yield spectra, obtained from the Monte Carlo simulations, is represented analytically, thus generating the Analytical Yield Spectra (AYS). AYS is employed to obtain the mean energy per ion pair and efficiencies of various inelastic processes. Mean energy per ion pair for neutral CH4 is found to be 26 (27.8) eV at 10 (0.1) keV. Efficiency calculation showed that ionization is the dominant process at energies > 50 eV, for which more than 50% of the incident electron energy is used. Above 25 eV, dissociation has an efficiency of ? 27 %. Below 10 eV, vibrational excitation dominates. Contribution of emission is around 1.2% at 10 keV. Efficiency of attachment process is ? 0.1 % at 8 eV and efficiency falls down to negligibly small values at energies greater than 15 eV. The efficiencies can be used to calculate volume production rate in planetary atmospheres by folding with electron production rate and integrating over energy.

  10. Estimation of methane and nitrous oxide emissions from rice field with rice straw management in Cambodia.

    PubMed

    Vibol, S; Towprayoon, S

    2010-02-01

    To estimate the greenhouse gas emissions from paddy fields of Cambodia, the methodology of the Intergovernmental Panel on Climate Change (IPCC) guidelines, IPCC coefficients, and emission factors from the experiment in Thailand and another country were used. Total area under rice cultivation during the years 2005-2006 was 2,048,360 ha in the first crop season and 298,529 ha in the second crop season. The emission of methane from stubble incorporation with manure plus fertilizer application areas in the first crop season was estimated to be 192,783.74 ton higher than stubble with manure, stubble with fertilizer, and stubble without fertilizer areas. The fields with stubble burning emitted the highest emission of methane (75,771.29 ton) followed by stubble burning with manure (22,251.08 ton), stubble burning with fertilizer (13,213.27 ton), and stubble burning with fertilizer application areas (3,222.22 ton). The total emission of methane from rice field in Cambodia for the years 2005-2006 was approximately 342,649.26 ton (342.65 Gg) in the first crop season and 36,838.88 ton (36.84 Gg) in the second crop season. During the first crop season in the years 2005-2006, Battambang province emitted the highest amount of CH(4) (38,764.48 ton) and, in the second crop season during the years 2005-2006, the highest emission (8,262.34 ton) was found in Takeo province (8,262.34 ton). Nitrous oxide emission was between 2.70 and 1,047.92 ton in the first crop season and it ranged from 0 to 244.90 ton in the second crop season. Total nitrous oxide emission from paddy rice field was estimated to be 9,026.28 ton in the first crop season and 1,091.93 ton in the second crop season. Larger area under cultivation is responsible for higher emission of methane and nitrous oxide. Total emission of nitrous oxide by using IPCC default emission coefficient was approximately 2,328.85 ton. The total global warming potential of Cambodian paddy rice soil is 11,723,217.03 ton (11,723 Gg) equivalents of CO(2). PMID:19259777

  11. Microbial fuel cell as mitigation strategy for methane emissions from paddy field

    NASA Astrophysics Data System (ADS)

    Rizzo, Anacleto; Boano, Fulvio; Revelli, Roberto; Ridolfi, Luca

    2013-04-01

    Microbial fuel cells (MFCs) are bioelectrochemical systems able to generate electricity from wetland soils, including paddies, exploiting the microbial decomposition of organic matter. A MFC is composed of an anode buried in the anaerobic submerged soil linked to a cathode placed on the top of the soil in the aerobic ponding water. A biofilm develops on the anode, where bacteria release electrons, oxidizing dissolved organic carbon (DOC) and using oxygen available at the cathode as electron acceptor. MFC technology is now in an early development stage and the efficiency in electricity production is still low. However, MFC can also be applied for secondary aims, among which one of great interest is the reduction of methane (CH4) emissions from paddy fields. Indeed, DOC oxidation at the anode can be seen as an additional DOC sink in paddy soil environment, limiting the DOC availability for methanogens. In this work, a process-based mathematical model is proposed for a preliminary investigation of the efficiency of MFCs in limiting CH4 emissions. The model relies on a system of partial differential mass balance equations to describe the vertical dynamics of the chemical compounds leading to CH4 production. Many physico-chemical processes and features characteristic of paddy soil are included: paddy soil stratigraphy; spatio-temporal variations of plant-root compartment; water and heat transport; SOC decomposition; heterotrophic reactions in both aerobic and anaerobic conditions; root radial oxygen loss; root solute uptake; DOC root exudation; plant-mediated, ebullition, and diffusion gas exchange pathways. MFC is modeled as a DOC sink term, following a zero-order kinetic where the current density is assumed constant for the whole growing season. Different values of current density are tested, in accordance with values reported in literature about efficiency reached in paddy soils. Our results show a reduction of CH4 emissions up to -28.1%, -24.1%, and -26.5% of daily minimum, daily maximum and total over the whole growing season, respectively, confirming the potential validity of MFC as a novel CH4 mitigation strategy. Moreover, it is shown that transport processes limit the mitigation of CH4 emissions at high current density. Finally, in order to maximize the reduction of CH4 emissions, simulation results suggest to place the anode in the middle portion of the superficial layer.

  12. Tropospheric methane emissions from cattails along a latitudinal gradient

    SciTech Connect

    Yavitt, J.B.; Knapp, A.K. (Cornell Univ., Ithaca, NY (United States) Kansas State Univ., Manhattan (United States))

    1993-06-01

    Tropospheric CH[sub 4] emitted from marshes seems to occur primarily through emergent vascular plants. To investigate how plant processes govern emissions, we studied CH[sub 4] release directly from leaves of cattail (Typha latifolia) concurrently with stomatal conductance and net photosynthesis using a field gas-exchange system in sites from New Mexico to Minnesota in July 1992. CH[sub 4] emissions averaged 0.22[mu]mol m[sup [minus]2] [leaf] s[sup [minus]1]. Midday emissions correlated weakly with stomatal conductance, confirming the role of stomatal responses in modulating CH[sub 4] release from cattail leaves. We found a slight trend of decreasing CH[sub 4] emission with increasing latitude, whereas dissolved CH[sub 4] in root-zone solutions and CH[sub 4] in plant air spaces (lacuna) showed a strong trend of increasing concentration with increasing latitude. Changes in whole-plant conductance for CH[sub 4] with plant age may partially account for these latitudinal trends. Our measurements, extrapolated to a ground area basis, averaged 900 mg m[sup [minus]2] d[sup [minus]1]. This estimate is an order of magnitude larger than previous findings for marshes probably because others bave not measured plant-mediated emissions directly.

  13. Measurements of biogenic non-methane organic compound emissions from grasslands

    SciTech Connect

    Fukui, Yoshiko

    1994-12-31

    Non-methane organic compounds (NMOCs) play an important role in the formation of photochemical oxidants in the troposphere. NMOCs originate from both anthropogenic and biogenic sources. Many organic compounds of biogenic origins are more reactive than those of anthropogenic origin because of the presence of internal double bonds within their molecular structure. The objective of this investigation was to examine the seasonal variation of NMOC emissions from grasslands and determine the environmental factors that control the emissions. An enclosure system was chosen as the most appropriate sampling technique for measuring emissions from herbaceous vegetation, and an analysis method using cryogenic preconcentration/high resolution gas chromatography was established. Emission rates were measured at a fixed location in a natural grassland during 1992 and 1993. Measurements were also made at various locations within the same site where the vegetation was harvested after the emission rates were determined. Emission rates of NMOCs for grasslands are not as large as those reported for forests. However the emissions of oxygenated hydrocarbons exceeded the emissions of monoterpenes and have not previously been identified as important forest-type emissions. A framework for parameterizing the NMOC emissions from grasslands based on seasonal and instantaneous variations of the emission rate measurements was developed. Temperature, hypoxia induced by water saturated soil, and frost were key environmental factors affecting both the composition and magnitude of NMOC emissions.

  14. Mapping methane emissions from a marine geological seep source using imaging spectrometry

    Microsoft Academic Search

    Dar A. Roberts; Eliza S. Bradley; Ross Cheung; Ira Leifer; Philip E. Dennison; Jack S. Margolis

    2010-01-01

    Methane (CH4) is an extremely important greenhouse gas that has increased significantly in pre and post-industrial times. Due to CH4's strong absorptions in the shortwave infrared (SWIR), the potential exists to use imaging spectrometers, such as the Airborne Visible Infrared Imaging Spectrometer (AVIRIS), to map CH4 emissions. Here, we present research evaluating the ability of AVIRIS to map CH4 emitted

  15. Methane and nitrous oxide concentration and emission flux of Yangtze Delta plain river net

    Microsoft Academic Search

    DongQi Wang; ZhenLou Chen; WeiWei Sun; BeiBei Hu; ShiYuan Xu

    2009-01-01

    Methane (CH4) and nitrous oxide (N2O) saturation concentration and gas-water interface emission flux in surface water of the Yangtze Delta plain river net were\\u000a investigated in summer at representative sites including the upper reaches of the Huangpu River and the rivers in the Chongming\\u000a Island. The results show that the CH4 concentration in river water ranged from 0.30±0.03 to 6.66±0.14

  16. Sources and sinks of methane in the African savanna. CH sub 4 emissions from biomass burning

    SciTech Connect

    Delmas, R.A.; Marenco, A. (Universite Paul Sabatier, Toulouse (France)); Tathy, J.P.; Cros, B. (Universite Marien Ngouabi, Brazzaville (Congo)); Baudet, J.G.R. (Faculte des Sciences, Abidjan, (Cote d'Ivoire))

    1991-04-20

    Sources and sinks of atmospheric methane are studied in savanna regions of west and central Africa. Flux measured over dry savanna soils, using static chambers, is always negative, the average uptake rate being 2 {times} 10{sup 10} molecules/cm{sup 2}/s. In these regions, sources are linked to biomass burning. Methane and CO{sub 2} emission from combustion of savanna plants and wood is studied by both field experiments and laboratory experiments using a combustion chamber. For savanna plants most of the carbon (85%) contained in the biomaterial is volatilized as CO{sub 2} and 0.1 to 0.25% as methane. For graminaceous plants like loudetia simplex the ratio C-CH{sub 4}/C-CO{sub 2} is 0.11%; it is 0.28% for hyparrhenia the other main type of savanna plants and it attains 1.4% for the combustion of wood. In natural fire plumes this ratio is around 0.26% for savanna fires and 0.56 to 2.22% for forest fires. These results show that methane release is highly dependent on the type of combustion. Methane to CO{sub 2} ratios are also studied in vertical profiles in the troposphere taken during the TROPOZ I campaign, an aerial research expedition carried out over west Africa during the bushfire period. Within polluted layers, the average ratio of CH{sub 4} to CO{sub 2} excess over ambient air concentration is 0.34%. These results show that biomass burning in tropical Africa constitutes an important source of atmospheric methane estimated to about 9.2 {times} 10{sup 6} T (CH{sub 4})/yr.

  17. Regionalization of Methane Emissions in the Amazon Basin with Multi-temporal Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Melack, J. M.; Hess, L. L.; Forsberg, B. R.; Hamilton, S. K.; Novo, E. M.

    2002-12-01

    Remote sensing of the Amazon basin with passive and active microwave techniques were applied to determine the temporally varying extent of inundation and associated vegetation, and used in conjunction with field measurements to calculate regional rates of methane emission from wetlands to the atmosphere. Monthly inundation areas were derived from analysis of the 37-GHz polarization difference observed by the Scanning Multichannel Microwave Radiometer (1979 -87) for the mainstem Amazon floodplain in Brazil, the Llanos de Moxos (Beni and Mamore rivers) in Bolivia, the Bananal Island (Araguaia River) and Roraima savannas. Data from the Japanese Earth Resources Satellite-1, L-band synthetic aperture radar were used to determine inundation and wetland vegetation for Amazon basin less than 500 m above sea level at high water (May-June 1996) and low water (October 1995). Although all the measurements of methane emission from aquatic habitats have been performed in the deeply inundated, central basin in open water, flooded forests or floating macrophytes, our basin-wide remote sensing has revealed large areas of seasonally flooded savannas. Therefore, improvements in basin-wide estimates of methane emission will require field studies in wetlands such as those in Bolivia, Roraima and the Bananal.

  18. Invited review: Enteric methane in dairy cattle production: quantifying the opportunities and impact of reducing emissions.

    PubMed

    Knapp, J R; Laur, G L; Vadas, P A; Weiss, W P; Tricarico, J M

    2014-06-01

    Many opportunities exist to reduce enteric methane (CH4) and other greenhouse gas (GHG) emissions per unit of product from ruminant livestock. Research over the past century in genetics, animal health, microbiology, nutrition, and physiology has led to improvements in dairy production where intensively managed farms have GHG emissions as low as 1 kg of CO2 equivalents (CO2e)/kg of energy-corrected milk (ECM), compared with >7 kg of CO2 e/kg of ECM in extensive systems. The objectives of this review are to evaluate options that have been demonstrated to mitigate enteric CH4 emissions per unit of ECM (CH4/ECM) from dairy cattle on a quantitative basis and in a sustained manner and to integrate approaches in genetics, feeding and nutrition, physiology, and health to emphasize why herd productivity, not individual animal productivity, is important to environmental sustainability. A nutrition model based on carbohydrate digestion was used to evaluate the effect of feeding and nutrition strategies on CH4/ECM, and a meta-analysis was conducted to quantify the effects of lipid supplementation on CH4/ECM. A second model combining herd structure dynamics and production level was used to estimate the effect of genetic and management strategies that increase milk yield and reduce culling on CH4/ECM. Some of these approaches discussed require further research, but many could be implemented now. Past efforts in CH4 mitigation have largely focused on identifying and evaluating CH4 mitigation approaches based on nutrition, feeding, and modifications of rumen function. Nutrition and feeding approaches may be able to reduce CH4/ECM by 2.5 to 15%, whereas rumen modifiers have had very little success in terms of sustained CH4 reductions without compromising milk production. More significant reductions of 15 to 30% CH4/ECM can be achieved by combinations of genetic and management approaches, including improvements in heat abatement, disease and fertility management, performance-enhancing technologies, and facility design to increase feed efficiency and life-time productivity of individual animals and herds. Many of the approaches discussed are only partially additive, and all approaches to reducing enteric CH4 emissions should consider the economic impacts on farm profitability and the relationships between enteric CH4 and other GHG. PMID:24746124

  19. Earth System Modeling of Ozone, Methane, and DMS

    Microsoft Academic Search

    P. J. Cameron-Smith; J. Lamarque; S. M. Elliott; D. J. Bergmann; C. Chuang; D. J. Erickson; M. E. Maltrud; A. A. Mirin; R. L. Jacob; J. Tithof

    2010-01-01

    One of the ways that the various Earth system components (land, atmosphere, ocean, and sea-ice) interact with each other is through chemical species, causing positive and negative feedbacks on the climate system. We will summarize the capabilities we have implemented within the Community Earth System Model (CESM, formerly known as CCSM) to simulate the Earth system interactions of ozone, methane,

  20. Isotopic Ratios in Titan's Methane: Measurements and Modeling

    NASA Technical Reports Server (NTRS)

    Nixon, C. A.; Temelso, B.; Vinatier, S.; Teanby, N. A.; Bezard, B.; Achterberg, R. K.; Mandt, K. E.; Sherrill, C. D.; Irwin, P. G.; Jennings, D. E.; Romani, P. N.; Coustenis, A.; Flasar, F. M.

    2012-01-01

    The existence of methane in Titan's atmosphere (approx. 6% level at the surface) presents a unique enigma, as photochemical models predict that the current inventory will be entirely depleted by photochemistry in a timescale of approx 20 Myr. In this paper, we examine the clues available from isotopic ratios (C-12/C-13 and D/H) in Titan's methane as to the past atmosphere history of this species. We first analyze recent infrared spectra of CH4 collected by the Cassini Composite Infrared Spectrometer, measuring simultaneously for the first time the abundances of all three detected minor isotopologues: (13)CH4, (12)CH3D, and (13)CH3D. From these we compute estimates of C-12/C-13 = 86.5 +/- 8.2 and D/H = (1.59 +/- 0.33) x 10(exp -4) , in agreement with recent results from the Huygens GCMS and Cassini INMS instruments. We also use the transition state theory to estimate the fractionation that occurs in carbon and hydrogen during a critical reaction that plays a key role in the chemical depletion of Titan's methane: CH4 + C2H yields CH3 + C2H2. Using these new measurements and predictions we proceed to model the time evolution of C-12/C-13 and D/H in Titan's methane under several prototypical replenishment scenarios. In our Model 1 (no resupply of CH4), we find that the present-day C-12/C-13 implies that the CH4 entered the atmosphere 60-1600 Myr ago if methane is depleted by chemistry and photolysis alone, but much more recently-most likely less than 10 Myr ago-if hydrodynamic escape is also occurring. On the other hand, if methane has been continuously supplied at the replenishment rate then the isotopic ratios provide no constraints, and likewise for the case where atmospheric methane is increasing, We conclude by discussing how these findings may be combined with other evidence to constrain the overall history of the atmospheric methane.

  1. ISOTOPIC RATIOS IN TITAN's METHANE: MEASUREMENTS AND MODELING

    SciTech Connect

    Nixon, C. A.; Achterberg, R. K. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Temelso, B. [Dean's Office, College of Arts and Sciences, Department of Chemistry, Bucknell University, Lewisburg, PA 17837 (United States); Vinatier, S.; Bezard, B.; Coustenis, A. [LESIA, Observatoire de Paris, CNRS, 5 Place Jules Janssen, 92195 Meudon Cedex (France); Teanby, N. A. [School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ (United Kingdom); Mandt, K. E. [Space Science and Engineering Division, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228 (United States); Sherrill, C. D. [School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, GA 30332-0400 (United States); Irwin, P. G. J. [Atmospheric, Oceanic and Planetary Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU (United Kingdom); Jennings, D. E.; Romani, P. N.; Flasar, F. M. [Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-04-20

    The existence of methane in Titan's atmosphere ({approx}6% level at the surface) presents a unique enigma, as photochemical models predict that the current inventory will be entirely depleted by photochemistry in a timescale of {approx}20 Myr. In this paper, we examine the clues available from isotopic ratios ({sup 12}C/{sup 13}C and D/H) in Titan's methane as to the past atmosphere history of this species. We first analyze recent infrared spectra of CH{sub 4} collected by the Cassini Composite Infrared Spectrometer, measuring simultaneously for the first time the abundances of all three detected minor isotopologues: {sup 13}CH{sub 4}, {sup 12}CH{sub 3}D, and {sup 13}CH{sub 3}D. From these we compute estimates of {sup 12}C/{sup 13}C = 86.5 {+-} 8.2 and D/H = (1.59 {+-} 0.33) Multiplication-Sign 10{sup -4}, in agreement with recent results from the Huygens GCMS and Cassini INMS instruments. We also use the transition state theory to estimate the fractionation that occurs in carbon and hydrogen during a critical reaction that plays a key role in the chemical depletion of Titan's methane: CH{sub 4} + C{sub 2}H {yields} CH{sub 3} + C{sub 2}H{sub 2}. Using these new measurements and predictions we proceed to model the time evolution of {sup 12}C/{sup 13}C and D/H in Titan's methane under several prototypical replenishment scenarios. In our Model 1 (no resupply of CH{sub 4}), we find that the present-day {sup 12}C/{sup 13}C implies that the CH{sub 4} entered the atmosphere 60-1600 Myr ago if methane is depleted by chemistry and photolysis alone, but much more recently-most likely less than 10 Myr ago-if hydrodynamic escape is also occurring. On the other hand, if methane has been continuously supplied at the replenishment rate then the isotopic ratios provide no constraints, and likewise for the case where atmospheric methane is increasing. We conclude by discussing how these findings may be combined with other evidence to constrain the overall history of the atmospheric methane.

  2. Management practices and controls on methane emissions from sub-tropical wetlands

    NASA Astrophysics Data System (ADS)

    DeLucia, Nicholas; Casa-Nova Gomez, Nuri; Bernacchi, Carl

    2015-04-01

    It is well documented that green house gas concentrations have risen at unequivocal rates since the industrial revolution but the disparity between anthropogenic sources and natural sources is uncertain. Wetlands are one example of a natural ecosystem that can be a substantial source or sink for methane (CH4) depending on any combination of climate conditions, natural and anthropogenic disturbances, or ecosystem perturbations. Due to strict anaerobic conditions required for CH4-generating microorganisms, natural wetlands are the main source for biogenic CH4. Although wetlands occupy less than 5% of total land surface area, they contribute approximately 20% of total CH4 emissions to the atmosphere. CH4 is one of the most damaging green house gases with current emission estimates ranging from 55 to 231 Tg CH4 yr-1. The processes regulating CH4 emissions are sensitive to land use and management practices of areas surrounding wetlands. Variation in adjacent vegetation or grazing intensity by livestock can, for example, alter CH4 fluxes from wetland soils by altering nutrient balance, carbon inputs and hydrology. Therefore, understanding how these changes will affect wetland source strength is essential to understand the impact of wetland management practices on the global climate system. In this study we quantify wetland methane fluxes from subtropical wetlands on a working cattle ranch in central Florida near Okeechobee Lake (27o10'52.04"N, 81o21'8.56"W). To determine differences in CH4 fluxes associated with land use and management, a replicated (n = 4) full factorial experiment was designed for wetlands where the surrounding vegetation was (1) grazed or un-grazed and (2) composed of native vegetation or improved pasture. Net exchange of CH4 and CO2 between the land surface and the atmosphere were sampled with a LICOR Li-7700 open path CH4 analyzer and Li-7500A open path CO2/H20 analyzer mounted in a 1-m3 static gas-exchange chamber. Our results showed and verified that CH4 emissions from subtropical wetlands were larger when high soil moisture was coupled with high temperatures. Grazing alone, does not appear to alter net ecosystem CH4 emissions from subtropical semi-native and improved wetlands. Pasture type is a stronger indicator of wetland methane potential. Wetlands embedded in improved pastures exhibited periods of increased methane emission that was particularly noticeable during the wet season (July- Nov). These results help quantify GHG emissions from subtropical wetlands under different management practices while demonstrating the differences in these fluxes based on the surrounding ecosystem.

  3. A global model of natural volatile organic compound emissions

    Microsoft Academic Search

    Alex Guenther; C. Nicholas Hewitt; David Erickson; Ray Fall; Chris Geron; Tom Graedel; Peter Harley; Lee Klinger; Manuel Lerdau; W. A. McKay; Tom Pierce; Bob Scholes; Rainer Steinbrecher; Raja Tallamraju; John Taylor; Pat Zimmerman

    1995-01-01

    Numerical assessments of global air quality and potential changes in atmospheric chemical constituents require estimates of the surface fluxes of a variety of trace gas species. We have developed a global model to estimate emissions of volatile organic compounds from natural sources (NVOC). Methane is not considered here and has been reviewed in detail elsewhere. The model has a highly

  4. Aircraft-Based Measurements of Point Source Methane Emissions in the Barnett Shale Basin.

    PubMed

    Lavoie, Tegan N; Shepson, Paul B; Cambaliza, Maria O L; Stirm, Brian H; Karion, Anna; Sweeney, Colm; Yacovitch, Tara I; Herndon, Scott C; Lan, Xin; Lyon, David

    2015-07-01

    We report measurements of methane (CH4) emission rates observed at eight different high-emitting point sources in the Barnett Shale, Texas, using aircraft-based methods performed as part of the Barnett Coordinated Campaign. We quantified CH4 emission rates from four gas processing plants, one compressor station, and three landfills during five flights conducted in October 2013. Results are compared to other aircraft- and surface-based measurements of the same facilities, and to estimates based on a national study of gathering and processing facilities emissions and 2013 annual average emissions reported to the U.S. EPA Greenhouse Gas Reporting Program (GHGRP). For the eight sources, CH4 emission measurements from the aircraft-based mass balance approach were a factor of 3.2-5.8 greater than the GHGRP-based estimates. Summed emissions totaled 7022 ± 2000 kg hr(-1), roughly 9% of the entire basin-wide CH4 emissions estimated from regional mass balance flights during the campaign. Emission measurements from five natural gas management facilities were 1.2-4.6 times larger than emissions based on the national study. Results from this study were used to represent "super-emitters" in a newly formulated Barnett Shale Inventory, demonstrating the importance of targeted sampling of "super-emitters" that may be missed by random sampling of a subset of the total. PMID:26148549

  5. Using the Global Chemical Transport Model GEOS-Chem to Constrain Australian Methane Sources

    NASA Astrophysics Data System (ADS)

    Chan Miller, C.; Jones, N. B.; Deutscher, N. M.; Griffith, D. W.; Paton-Walsh, C.; Frankenberg, C.; Wennberg, P. O.; Toon, G. C.; Sherlock, V.; Smale, D.; Robinson, J.; Connor, B. J.

    2009-12-01

    There are few existing greenhouse gas measurements over the Australasian region. The methane budget of this area has therefore been subject to large uncertainty. In late February 2008 an in-situ trace gas analyzer was deployed on a train-borne platform, measuring key greenhouse gases along a latitudinal transect through the centre of the continent. The path of this transect ran through areas that previously contained no or very few measurements. Two further measurement campaigns were performed during March and September of that year. During the first two campaigns, a significant methane enhancement in Tropical north Australia was observed that was not apparent in the third campaign. We hypothesize that the coincidence of this enhancement with the tropical monsoon wet season indicates the presence of an important ephemeral wetland source in northern Australia. Here we present the results from a GEOS-Chem simulation from 2005-2008, employing tagged Australian emission categories to estimate the contribution of individual sources to the seasonal northern methane enhancement. In addition, model validation with satellite (SCIAMACHY) and ground based (TCCON) methane column retrievals will be displayed.

  6. CCMR: Simulation of Type I Methane Hydrate Using the Fluctuating Charge Model

    NSDL National Science Digital Library

    Hatch, Harold

    2007-08-29

    The entire natural gas resource base in the United States is less than one percent of the gas trapped inside hydrates on the ocean shelves.1 Methane hydrates are ice-like crystal cages of water molecules with individual methane molecules inside the water cages that form at 276.6 K, just a few degrees above the melting point of ice, and in high pressures excess of 68 bar.2 Unfortunately, mining gas hydrates could result in uncontrollable decomposition and emission of green house gas, and gas hydrate inhibitors, such as methanol, are costly and required to avoid plugs in gas pipelines. Molecular-scale computer simulation can provide insight on these problems by allowing studies of in situ gas hydrate growth and dissolution in short time scales on a molecular level that cannot be obtained experimentally. Unfortunately, while there has been a lot of study on bulk hydrates there have been no studies of hydrate growth and dissolution in confined pores such as would be found in the rocks in which hydrates are found. This forms the motivation for this project. The major goal of this project was to determine the melting point of methane hydrate using an intermolecular potential model for water. A second task was to set up simulations to determine the melting point of a seed crystal of methane hydrate in a liquid hydrate melt.

  7. Ecosystem Modelling for Impact Assessment of Possible Methane Leakage during Methane Hydrate Utilization

    Microsoft Academic Search

    T. Yamazaki; Y. Nakano; D. Monoe; T. Oomi; T. Doi; K. Nakata; T. Fukushima

    2005-01-01

    Natural methane hydrate has been scientifically studied as a carbon reservoir globally. However, in Japan, the potential for energy resource has been industrially highlighted. There is less domestic oil and natural gas resources in Japan, but many potential deposition areas for methane hydrate in ocean around Japan are the reasons. Less CO2 discharge from methane compared with coal, oil and

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

    PubMed

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

    2014-08-01

    Using a dual species methane/acetylene instrument based on cavity ring down spectroscopy (CRDS), the dynamic plume tracer dispersion method for quantifying the emission rate of methane was successfully tested in four measurement campaigns: (1) controlled methane and trace gas release with different trace gas configurations, (2) landfill with unknown emission source locations, (3) landfill with closely located emission sources, and (4) comparing with an Fourier transform infrared spectroscopy (FTIR) instrument using multiple trace gasses for source separation. The new real-time, high precision instrument can measure methane plumes more than 1.2 km away from small sources (about 5 kg h(-1)) in urban areas with a measurement frequency allowing plume crossing at normal driving speed. The method can be used for quantification of total methane emissions from diffuse area sources down to 1 kg per hour and can be used to quantify individual sources with the right choice of wind direction and road distance. The placement of the trace gas is important for obtaining correct quantification and uncertainty of up to 36% can be incurred when the trace gas is not co-located with the methane source. Measurements made at greater distances are less sensitive to errors in trace gas placement and model calculations showed an uncertainty of less than 5% in both urban and open-country for placing the trace gas 100 m from the source, when measurements were done more than 3 km away. Using the ratio of the integrated plume concentrations of tracer gas and methane gives the most reliable results for measurements at various distances to the source, compared to the ratio of the highest concentration in the plume, the direct concentration ratio and using a Gaussian plume model. Under suitable weather and road conditions, the CRDS system can quantify the emission from different sources located close to each other using only one kind of trace gas due to the high time resolution, while the FTIR system can measure multiple trace gasses but with a lower time resolution. PMID:24759753

  9. Quantifying the relative contribution of natural gas fugitive emissions to total methane emissions in Weld County Colorado using ?13CH4 analysis

    NASA Astrophysics Data System (ADS)

    Rella, C.; Jacobson, G. A.; Crosson, E.; Sweeney, C.; Karion, A.; Petron, G.

    2012-12-01

    Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Given that the global warming potential of methane is many times greater than that of carbon dioxide (Forster et al. 2007), the importance of quantifying methane emissions becomes clear. Companion presentations at this meeting describe efforts to quantify the overall methane emissions in two separate gas producing areas in Colorado and Utah during intensive field campaigns undertaken in 2012. A key step in the process of assessing the emissions arising from natural gas production activities is partitioning the observed methane emissions between natural gas fugitive emissions and other sources of methane, such as from landfills or agricultural activities. One method for assessing the contribution of these different sources is stable isotope analysis. In particular, the ?13CH4 signature of natural gas (-37 permil) is significantly different that the signature of other significant sources of methane, such as landfills or ruminants (-50 to -70 permil). In this paper we present measurements of ?13CH4 in Colorado in Weld County, a region of intense natural gas production, using a mobile ?13CH4¬ analyzer capable of high-precision measurements of the stable isotope ratio of methane at ambient levels. This analyzer was used to make stable isotope measurements at a fixed location near the center of the gas producing region, from which an overall isotope ratio for the regional emissions is determined. In addition, mobile measurements in the nocturnal boundary layer have been made, over a total distance of 150 km throughout Weld County, allowing spatially resolved measurements of this isotope signature. Finally, this analyzer was used to quantify the isotopic signature of those individual sources (natural gas fugitive emissions, concentrated animal feeding operations, and landfills) that constitute the majority of methane emissions in this region, by making measurements of the isotope ratio directly in the downwind plume from each source. These data are combined to establish the fraction of the observed methane emissions that can be attributed to natural gas activities in the region. The results are compared to inventories as well as other measurement techniques, and the uncertainty of the measurement is estimated.

  10. Methane emissions by management and treatment of municipal wastewater in Mexico 2010

    NASA Astrophysics Data System (ADS)

    Paredes Figueroa, M. G.; Güereca, L. P.; Noyola, A.; Herndon, S.; Roscioli, J. R.; Yacovitch, T. I.; Fortner, E.; Knighton, W. B.; Molina, L. T.

    2013-12-01

    Management and treatment of wastewater has been identified as a major source of greenhouse gases (GHG). In wastewater treatment (WWT) systems without mechanical ventilation, methanogenic bacteria activate anaerobic decomposition of degradable organics, producing methane (CH4) as a byproduct. Methane produced during the management and treatment of wastewater is estimated to constitute between 8 and 11% to overall CH4 emissions, but a lack of quantitative methane emissions data from specific WWT processes prevents the design of effective mitigation strategies. We are developing a detailed WWT sector CH4 emissions inventory for Mexico. CH4 emissions have been estimated from the 2010 baseline year, using the IPCC Guidelines for National Greenhouse Gas Inventories. These estimates considered WWT plant infrastructures, volumes of waste treated, and the quality of input and output water and temperature. It is important to note that ambient temperature is one of the main factors influencing methane production, which in tropical and subtropical regions is close to optimal for mesophylic methanogenesis (35 °C), resulting in high biological activity and CH4 emissions from anaerobic systems compared to temperate latitudes. Mexico was divided into three regions: north, central and south in order to take into account these temperature variations. In order to evaluate methane emission inventories, direct measurements of WWT facility CH4 emission rates were performed during the SLCF-Mexico project in early 2013. The Aerodyne Mobile Laboratory performed emissions measurements at four wastewater treatment facilities in Mexico. Quantum cascade laser instruments were used to monitor CH4 and N2O, while a proton transfer reaction mass spectrometer monitored organics such as methanethiol. At three facilities, tracer release methods were used to quantify CH4 emission rates from anaerobic digestors. An Aerodyne aerosol mass spectrometer was also used to monitor particulate emissions from CH4 flares associated with the digestors. Measurement results will be presented. In 2010, the number of municipal wastewater treatment plants (MWWTP) in Mexico was 2186, with a total treated flow of 93.6 m3/s, representing just 45% of collected wastewater at the national level. The percentage of treated wastewater varies by region: in northern Mexico, 93% of the collected wastewater is treated, while the central and southern regions have treatment coverages of only 31% and 28%, respectively. As a result, the north has a 51% removal of biochemical oxygen demand (BOD) by WWT, while the central and southern regions remove only 17% and 16% of BOD, respectively. The management and treatment of municipal wastewater in Mexico for the year 2010 generated 600.4 Gigagrams (Gg) of CH4. By region: north 23.5% (141.1 Gg), central 53.4% (320.6 Gg) and south 23.1% (138.7 Gg). These values are directly related to the population of each region and the amount of BOD removed by different WWT systems.

  11. Non-Methane Biogenic Volatile Organic Compound Emissions from a Subarctic Peatland Under Enhanced UV-B Radiation

    Microsoft Academic Search

    Patrick Faubert; Päivi Tiiva; A. Rinnan; J. Rasanen; Jarmo K. Holopainen; Toini Holopainen; E. Kyro; Riikka Rinnan

    2010-01-01

    Boreal and subarctic peatlands have been extensively studied for their major role in the global carbon balance. However, study efforts have so far neglected the contribution of these ecosystems to the non-methane biogenic volatile organic compound (BVOC) emissions, which are important in the atmospheric chemistry and feedbacks on climate change. We aimed at estimating the BVOC emissions from a subarctic

  12. Natural emissions of non-methane volatile organic compounds, carbon monoxide, and oxides of nitrogen from North America

    Microsoft Academic Search

    Alex Guenther; Chris Geron; Tom Pierce; Brian Lamb; Peter Harley; Ray Fall

    2000-01-01

    The magnitudes, distributions, controlling processes and uncertainties associated with North American natural emissions of oxidant precursors are reviewed. Natural emissions are responsible for a major portion of the compounds, including non-methane volatile organic compounds (NMVOC), carbon monoxide (CO) and nitric oxide (NO), that determine tropospheric oxidant concentrations. Natural sources include soil microbes, vegetation, biomass burning, and lightning. These sources are

  13. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 10: METERING AND PRESSURE REGULATING STATIONS IN NATURAL GAS TRANSMISSIONS AND DISTRIBUTION

    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...

  14. Vegetation height and other controls of spatial variability in methane emissions from the Arctic coastal tundra at Barrow, Alaska

    Microsoft Academic Search

    Joseph C. von Fischer; Robert C. Rhew; Gregory M. Ames; Bailey K. Fosdick; Paul E. von Fischer

    2010-01-01

    We conducted measurements of methane (CH4) emission and ecosystem respiration on >200 points across the Arctic coastal tundra near Barrow, Alaska, United States, in July 2007 and August 2008. This site contains broad diversity in tundra microtopography, including polygonal tundra, thaw lakes, and drained lake basins. In 2007, we surveyed CH4 emissions across this landscape, and found that soil water

  15. A methane production feasibility model for central anaerobic digesters

    NASA Astrophysics Data System (ADS)

    Sullivan, J. L.; Peters, N.; Ostrovski, C. M.

    1981-01-01

    A mathematical model was developed for prediction of the practicability of building and operating large centrally located anaerobic digesters for producing methane gas from animal manure. The assumptions were that the manure would be collected from the feedlots and that the product gas would be supplied to an existing pipeline. The model takes account of the farm locations and calculates transportation costs for various numbers of digesters. Digester sizes for each distribution and installation and operating costs are computed. Revenue was then determined on the basis of methane production and fertilizer value recovery. The utility of the model is shown through a study of farms in southwestern Ontario where many small feedlots exist. The results of the study indicate a gas production cost of roughly $0.18/cu m.

  16. Quantifying methane and nitrous oxide emissions from the UK and Ireland using a national-scale monitoring network

    NASA Astrophysics Data System (ADS)

    Ganesan, A. L.; Manning, A. J.; Grant, A.; Young, D.; Oram, D. E.; Sturges, W. T.; Moncrieff, J. B.; O'Doherty, S.

    2015-06-01

    The UK is one of several countries around the world that has enacted legislation to reduce its greenhouse gas emissions. In this study, we present top-down emissions of methane (CH4) and nitrous oxide (N2O) for the UK and Ireland over the period August~2012 to August~2014. These emissions were inferred using measurements from a network of four sites around the two countries. We used a hierarchical Bayesian inverse framework to infer fluxes as well as a set of covariance parameters that describe uncertainties in the system. We inferred average UK total emissions of 2.09 (1.65-2.67) Tg yr-1 CH4 and 0.101 (0.068-0.150) Tg yr-1 N2O and found our derived UK estimates to be generally lower than the a priori emissions, which consisted primarily of anthropogenic sources and with a smaller contribution from natural sources. We used sectoral distributions from the UK National Atmospheric Emissions Inventory (NAEI) to determine whether these discrepancies can be attributed to specific source sectors. Because of the distinct distributions of the two dominant CH4 emissions sectors in the UK, agriculture and waste, we found that the inventory may be overestimated in agricultural CH4 emissions. We found that annual mean N2O emissions were consistent with both the prior and the anthropogenic inventory but we derived a significant seasonal cycle in emissions. This seasonality is likely due to seasonality in fertilizer application and in environmental drivers such as temperature and rainfall, which are not reflected in the annual resolution inventory. Through the hierarchical Bayesian inverse framework, we quantified uncertainty covariance parameters and emphasized their importance for high-resolution emissions estimation. We inferred average model errors of approximately 20 and 0.4 ppb and correlation timescales of 1.0 (0.72-1.43) and 2.6 (1.9-3.9) days for CH4 and N2O, respectively. These errors are a combination of transport model errors as well as errors due to unresolved emissions processes in the inventory. We found the largest CH4 errors at the Tacolneston station in eastern England, which may be due to sporadic emissions from landfills and offshore gas in the North Sea.

  17. A study of the sources and sinks of methane and methyl chloroform using a global three-dimensional Lagrangian tropospheric tracer transport model

    NASA Technical Reports Server (NTRS)

    Taylor, John A.; Brasseur, G. P.; Zimmerman, P. R.; Cicerone, R. J.

    1991-01-01

    Sources and sinks of methane and methyl chloroform are investigated using a global three-dimensional Lagrangian tropospheric tracer transport model with parameterized hydroxyl and temperature fields. Using the hydroxyl radical field calibrated to the methyl chloroform observations, the globally averaged release of methane and its spatial and temporal distribution were investigated. Two source function models of the spatial and temporal distribution of the flux of methane to the atmosphere were developed. The first model was based on the assumption that methane is emitted as a proportion of net primary productivity (NPP). The second model identified source regions for methane from rice paddies, wetlands, enteric fermentation, termites, and biomass burning based on high-resolution land use data. The most significant difference between the two models were predictions of methane fluxes over China and South East Asia, the location of most of the world's rice paddies, indicating that either the assumption that a uniform fraction of NPP is converted to methane is not valid for rice paddies, or that NPP is underestimated for rice paddies, or that present methane emission estimates from rice paddies are too high.

  18. Impact of transport and modelling errors on the estimation of methane sources and sinks by inverse modelling

    NASA Astrophysics Data System (ADS)

    Locatelli, Robin; Bousquet, Philippe; Chevallier, Frédéric

    2013-04-01

    Since the nineties, inverse modelling by assimilating atmospheric measurements into a chemical transport model (CTM) has been used to derive sources and sinks of atmospheric trace gases. More recently, the high global warming potential of methane (CH4) and unexplained variations of its atmospheric mixing ratio caught the attention of several research groups. Indeed, the diversity and the variability of methane sources induce high uncertainty on the present and the future evolution of CH4 budget. With the increase of available measurement data to constrain inversions (satellite data, high frequency surface and tall tower observations, FTIR spectrometry,...), the main limiting factor is about to become the representation of atmospheric transport in CTMs. Indeed, errors in transport modelling directly converts into flux changes when assuming perfect transport in atmospheric inversions. Hence, we propose an inter-model comparison in order to quantify the impact of transport and modelling errors on the CH4 fluxes estimated into a variational inversion framework. Several inversion experiments are conducted using the same set-up (prior emissions, measurement and prior errors, OH field, initial conditions) of the variational system PYVAR, developed at LSCE (Laboratoire des Sciences du Climat et de l'Environnement, France). Nine different models (ACTM, IFS, IMPACT, IMPACT1x1, MOZART, PCTM, TM5, TM51x1 and TOMCAT) used in TRANSCOM-CH4 experiment (Patra el al, 2011) provide synthetic measurements data at up to 280 surface sites to constrain the inversions performed using the PYVAR system. Only the CTM (and the meteorological drivers which drive them) used to create the pseudo-observations vary among inversions. Consequently, the comparisons of the nine inverted methane fluxes obtained for 2005 give a good order of magnitude of the impact of transport and modelling errors on the estimated fluxes with current and future networks. It is shown that transport and modelling errors lead to a discrepancy of 27 TgCH4 per year at global scale, representing 5% of the total methane emissions for 2005. At continental scale, transport and modelling errors have bigger impacts in proportion to the area of the regions, ranging from 36 TgCH4 in North America to 7 TgCH4 in Boreal Eurasian, with a percentage range from 23% to 48%. Thus, contribution of transport and modelling errors to the mismatch between measurements and simulated methane concentrations is large considering the present questions on the methane budget. Moreover, diagnostics of statistics errors included in our inversions have been computed. It shows that errors contained in measurement errors covariance matrix are under-estimated in current inversions, suggesting to include more properly transport and modelling errors in future inversions.

  19. High methane emissions from a midlatitude reservoir draining an agricultural watershed.

    PubMed

    Beaulieu, Jake J; Smolenski, Rebecca L; Nietch, Christopher T; Townsend-Small, Amy; Elovitz, Michael S

    2014-10-01

    Reservoirs are a globally significant source of methane (CH4), although most measurements have been made in tropical and boreal systems draining undeveloped watersheds. To assess the magnitude of CH4 emissions from reservoirs in midlatitude agricultural regions, we measured CH4 and carbon dioxide (CO2) emission rates from William H. Harsha Lake (Ohio, U.S.A.), an agricultural impacted reservoir, over a 13 month period. The reservoir was a strong source of CH4 throughout the year, emitting on average 176 ± 36 mg C m(-2) d(-1), the highest reservoir CH4 emissions profile documented in the United States to date. Contrary to our initial hypothesis, the largest CH4 emissions were during summer stratified conditions, not during fall turnover. The river-reservoir transition zone emitted CH4 at rates an order of magnitude higher than the rest of the reservoir, and total carbon emissions (i.e., CH4 + CO2) were also greater at the transition zone, indicating that the river delta supported greater carbon mineralization rates than elsewhere. Midlatitude agricultural impacted reservoirs may be a larger source of CH4 to the atmosphere than currently recognized, particularly if river deltas are consistent CH4 hot spots. We estimate that CH4 emissions from agricultural reservoirs could be a significant component of anthropogenic CH4 emissions in the U.S.A. PMID:25158047

  20. [Effects of filamentous macroalgae on the methane emission from urban river: a review].

    PubMed

    Zhang, Xiu-Yun; Liang, Xia; He, Chi-Quan

    2013-05-01

    The global warming caused by greenhouse gases emission has raised serious concerns. Recent studies found that the carbon dioxide (CO2) and methane (CH4) emissions from river ecosystem can partly offset the carbon sequestration by terrestrial ecosystem, leading to a rethink of the effects of river ecosystem on the global carbon balance and greenhouse gases emission inventory. As an important primary producer in urban river ecosystem, filamentous macroalgae can deeply affect the carbon cycle process of river system through changing the abiotic and biotic factors in the interface of water-sediment. This paper reviewed the effects of filamentous macroalgae on the CH4 emission from urban river system from the aspects of 1) the effects of urbanization on the river ecosystem and its CH4 emission flux, 2) the effects of filamentous macroalgae on the CH4 generation and emission process in natural river systems, and 3) the effects of filamentous macroalgae on the primary productivity and CH4 emission process in urban river systems. The current problems and future directions in related researches were discussed and prospected. PMID:24015546

  1. Potential methane emission from north-temperate lakes following ice melt

    USGS Publications Warehouse

    Michmerhuizen, C.M.; Striegl, R.G.; McDonald, M.E.

    1996-01-01

    Methane, a radiatively active 'greenhouse' gas, is emitted from lakes to the atmosphere throughout the open-water season. However, annual lake CH4 emissions calculated solely from open-water measurements that exclude the time of spring ice melt may substantially underestimate the lake CH4 source strength. We estimated potential spring CH4 emission at the time of ice melt for 19 lakes in northern Minnesota and Wisconsin. Lakes ranged in area from 2.7 to 57,300 ha and varied in littoral zone sediment type. Regression analyses indicated that lake area explained 38% of the variance in potential CH4 emission for relatively undisturbed lakes; as lake area increases potential CH4 emission per unit area decreases. Inclusion of a second term accounting for the presence or absence of soft organic-rich littoral-zone sediments explained 83% of the variance in potential spring CH4 emission. Total estimated spring CH4 emission for 1993 for all Minnesota lakes north of 45?? with areas ???4 ha was 1.5 x 108 mol CH4 assuming a 1 : 1 ratio of soft littoral sediment to hard littoral sediment lakes. Emission estimates ranged from 5.3 x 107 tool assuming no lakes have soft organic-rich littoral sediments to 4.5 x 108 mol assuming all lakes have soft organic-rich littoral sediments. This spring CH4 pulse may make up as much as 40% of the CH4 annually emitted to the atmosphere by small lakes.

  2. Environmental and physical controls on northern terrestrial methane emissions across permafrost zones

    USGS Publications Warehouse

    Olefeldt, David; Turetsky, Merritt R.; Crill, Patrick M.; McGuire, A. David

    2013-01-01

    Methane (CH4) emissions from the northern high-latitude region represent potentially significant biogeochemical feedbacks to the climate system. We compiled a database of growing-season CH4 emissions from terrestrial ecosystems located across permafrost zones, including 303 sites described in 65 studies. Data on environmental and physical variables, including permafrost conditions, were used to assess controls on CH4 emissions. Water table position, soil temperature, and vegetation composition strongly influenced emissions and had interacting effects. Sites with a dense sedge cover had higher emissions than other sites at comparable water table positions, and this was an effect that was more pronounced at low soil temperatures. Sensitivity analysis suggested that CH4 emissions from ecosystems where the water table on average is at or above the soil surface (wet tundra, fen underlain by permafrost, and littoral ecosystems) are more sensitive to variability in soil temperature than drier ecosystems (palsa dry tundra, bog, and fen), whereas the latter ecosystems conversely are relatively more sensitive to changes of the water table position. Sites with near-surface permafrost had lower CH4 fluxes than sites without permafrost at comparable water table positions, a difference that was explained by lower soil temperatures. Neither the active layer depth nor the organic soil layer depth was related to CH4 emissions. Permafrost thaw in lowland regions is often associated with increased soil moisture, higher soil temperatures, and increased sedge cover. In our database, lowland thermokarst sites generally had higher emissions than adjacent sites with intact permafrost, but emissions from thermokarst sites were not statistically higher than emissions from permafrost-free sites with comparable environmental conditions. Overall, these results suggest that future changes to terrestrial high-latitude CH4 emissions will be more proximately related to changes in moisture, soil temperature, and vegetation composition than to increased availability of organic matter following permafrost thaw.

  3. The effect of a condensed tannin-containing forage on methane emission by goats.

    PubMed

    Puchala, R; Min, B R; Goetsch, A L; Sahlu, T

    2005-01-01

    The objective of this study was to compare methane emission by goats consuming the condensed tannin-containing forage sericea lespedeza (Les-pedeza cuneata) or a mixture of crabgrass (Digitaria ischaemum) and Kentucky 31 tall fescue (Festuca arundinacea). Two groups of 12 Angora does (initial average BW = 41.5 +/- 2.7 kg) that previously grazed a pasture of sericea lespedeza or crabgrass/tall fescue for approximately 4 mo were used. After 1 wk of adaptation to metabolism cages, gas exchange was measured for 24 h in an open-circuit respiration calorimetry system with four head boxes. Forage harvested daily from the previously grazed pastures was consumed ad libitum. Crude protein concentration was 10.3 and 13.0%, IVDMD was 64.5 and 75.3%, and the level of condensed tannins was 17.7 and 0.5% for sericea lespedeza and crabgrass/tall fescue, respectively. Dry matter intake (1.11 vs. 0.67 kg/d) and digestible DMI (estimated from IVDMD; 0.71 vs. 0.51 kg/d) were greater (P < 0.01) for sericea lespedeza than for crabgrass/tall fescue. Ruminal ammonia N (3.7 and 9.9 mg/dL; P < 0.001) and plasma urea-N concentrations (16.7 and 20.9 mg/dL; P = 0.07) were lower for sericea lespedeza than for crabgrass/tall fescue. Concentrations of individual and total VFA and the acetate-to-propionate ratio in ruminal fluid did not differ between treatments (P > 0.19). Despite higher DMI by goats fed sericea lespedeza, daily energy expenditure (409 vs. 431 kJ/kg BW(0.75)), heart rate (70 vs. 73 beats/min), and the ratio of energy expenditure to heart rate (5.82 vs. 5.94) did not differ between sericea lespedeza and crabgrass/tall fescue, respectively (P > 0.13). Methane emission expressed as both quantity per day or relative to DMI was lower (P <0.001) for sericea lespedeza than for crabgrass/tall fescue (7.4 vs. 10.6 g/d and 6.9 vs. 16.2 g/kg DMI). Substantial differences between the forages in condensed tannins concentration and methane emission by Angora goats suggest that condensed tannins decreased methane emission. PMID:15583058

  4. Insight Into West Siberian Gas and Wetland Methane Emissions From ? 13C Studies of Ambient Air

    NASA Astrophysics Data System (ADS)

    Lowry, D.; Fisher, R.; Levin, I.; Privalov, S.; Nisbet, E.

    2004-12-01

    The Ob River region of West Siberia is home to some of the largest known gasfields and wetlands, and a source of around 2.5% of the total global methane emissions. It is also a major source region of CO2 emissions. Carbon isotopes of ambient air and emission sources provide an important tool for understanding these poorly constrained sources. Tank samples of ambient air were collected overnight for ? 13C analysis of methane during the summer (August-September) campaigns of 1999 and 2000, as part of INTAS-funded projects. The main sampling centres were Nadym and Urengoy, with samples collected above the known gas reserves, near pumping stations and by boat on the Nadym River, downstream toward Salekhard. CH4 of up to 900 ppb above background was recorded and ? 13C depletions of up to 3‰ relative to background. West Siberian gas has measured ? 13C values of -51.5 to -49.5‰ based on well samples and supplies in St. Petersburg and Germany. Implications from aircraft flights (Sugawara et al. 1996) and measurements along the Trans-Siberian railroad (Bergamaschi et al., 1998) are that the wetland signature is around -67‰ . The ambient air samples give a range of calculated source inputs from -67.3 to -49.3‰ , the end members corresponding to sampling areas expected to contain only wetland or gas emissions and confirmed by back trajectory analysis for sampling times. Using the end members, the average excess methane from the wetland source was 62 ppb around Nadym and 61 ppb around Urengoy. The average excess from the gasfields was 30 ppb around Nadym but 82 ppb around Urengoy, reflecting the closer proximity to the gasfields. The maximum excess recorded from wetlands was 160 ppb and from gasfields was 710 ppb. Experiments during summer 2004 have focussed on bag sampling on the tower of a super deep well at Korotchaevo, SE of the Urengoy gas field. Samples collected at 20, 30 and 60m heights will be analysed for ? 13C of both CH4 and CO2 and apportioned to gas and wetland sources. Bergamaschi P.et al. Isotope analysis based source identification for atmospheric CH4 and CO sampled across Russia using the Trans-Siberian railroad. J. Geophys. Res., 103 (D), 8227-8235, 1998. Suguwara S. et al. Aircraft measurements of the stable carbon isotopic ratio of atmospheric methane over Siberia. Global Biogeochem. Cycles, 10, 223-231, 1996.

  5. Effect of microrelief and vegetation on methane emission from wet polygonal tundra, Lena Delta, Northern Siberia

    Microsoft Academic Search

    Lars Kutzbach; Dirk Wagner; Eva-Maria Pfeiffer

    2004-01-01

    The effect of microrelief and vegetation on methane (CH4) emission was investigated in a wet polygonal tundra of the Lena Delta, Northern Siberia (72.37N, 126.47E). Total and plant-mediated CH4 fluxes were measured by closed-chamber techniques at two typical sites within a low-centred polygon. During the study period, total CH4 flux averaged 28.0?±?5.4?mg?m-2?d-1 in the depressed polygon centre and only 4.3?±?0.8?mg?m-2?d-1

  6. Exploration strategies based on a coalbed methane producibility model

    SciTech Connect

    Scott, A.R.; Kaiser, W.R.; Hamilton, D.S.; Tyler, R.; Finley, R.J. (Univ. of Texas, Austin, TX (United States))

    1996-01-01

    Knowing geologic and hydrologic characteristics of a basin does not necessarily lead to a determination of its coalbed methane producibility because it is the synergy among key hydrogeologic controls that governs producibility. Detailed studies performed in the San Juan, Piceance, and Sand Wash Basins determined that the key hydrogeologic factors affecting producibility include depositional setting and coal distribution, tectonic and structural setting, coal rank and gas generation, hydrodynamics, permeability, and gas content. The conceptual model based on these factors provides a rationale for exploration and development strategies for unexplored areas or in basins having established or limited production. Exceptionally high productivity requires good permeability; thick, laterally continuous high-rank and high-gas-content coals; dynamic flow of ground water through those coals; generation of secondary biogenic gases; and migration and conventional trapping of thermogenic and biogenic gases. Higher coalbed methane producibility commonly occurs in areas of upward flow associated with permeability barriers (no-flow boundaries). Fluid migration across a large gathering area orthogonal to permeability barriers and/or in situ generation of secondary biogenic gases concentrate the coal gas, resulting in higher gas contents. Low coalbed methane production is typically associated with very low permeability systems; the absence of conventional or hydrodynamic traps; and thin, low-rank coals below the threshold of thermogenic gas generation. Production from relatively low-gas-content coals in highly permeable recharge areas may result in excessive water and limited coalbed methane production. Thus, high permeability can be as detrimental to coalbed methane producibility as is low permeability.

  7. Exploration strategies based on a coalbed methane producibility model

    SciTech Connect

    Scott, A.R.; Kaiser, W.R.; Hamilton, D.S.; Tyler, R.; Finley, R.J. [Univ. of Texas, Austin, TX (United States)

    1996-12-31

    Knowing geologic and hydrologic characteristics of a basin does not necessarily lead to a determination of its coalbed methane producibility because it is the synergy among key hydrogeologic controls that governs producibility. Detailed studies performed in the San Juan, Piceance, and Sand Wash Basins determined that the key hydrogeologic factors affecting producibility include depositional setting and coal distribution, tectonic and structural setting, coal rank and gas generation, hydrodynamics, permeability, and gas content. The conceptual model based on these factors provides a rationale for exploration and development strategies for unexplored areas or in basins having established or limited production. Exceptionally high productivity requires good permeability; thick, laterally continuous high-rank and high-gas-content coals; dynamic flow of ground water through those coals; generation of secondary biogenic gases; and migration and conventional trapping of thermogenic and biogenic gases. Higher coalbed methane producibility commonly occurs in areas of upward flow associated with permeability barriers (no-flow boundaries). Fluid migration across a large gathering area orthogonal to permeability barriers and/or in situ generation of secondary biogenic gases concentrate the coal gas, resulting in higher gas contents. Low coalbed methane production is typically associated with very low permeability systems; the absence of conventional or hydrodynamic traps; and thin, low-rank coals below the threshold of thermogenic gas generation. Production from relatively low-gas-content coals in highly permeable recharge areas may result in excessive water and limited coalbed methane production. Thus, high permeability can be as detrimental to coalbed methane producibility as is low permeability.

  8. Measurements of Point Source Methane Emissions in the Barnett Shale and Eagle Ford Basins

    NASA Astrophysics Data System (ADS)

    Lavoie, T. N.; Shepson, P. B.; Cambaliza, M. O. L.; Karion, A.; Sweeney, C.; Kort, E. A.; Hirst, B.; Wolter, S.; Conley, S. A.; Faloona, I. C.; Lyon, D.; Alvarez, R.

    2014-12-01

    The global average temperature is rising as a result of anthropogenic emissions of greenhouse gases. The two organic carbon gases that contribute most to this warming are carbon dioxide (CO2) and methane (CH4). CH4, however, is 34 times more potent as a greenhouse gas than CO2 on a 100-year timescale, and 86 times more potent on a 20-year timescale. The ~12 year lifetime of CH4 means that measures to control methane emissions on the near-term time scale may have a relatively large climate benefit. The past decade has witnessed a dramatic increase in the reliance on natural gas (NG) to meet the energy needs of the U.S. To enable informed greenhouse gas policy and mitigation efforts, a comprehensive understanding of the nature and magnitude of CH4 emissions for various related NG technologies and engineering practices is required. Here we report results of our recent studies of the CH4 emission rate observed at eight different biogenic and NG point sources in the Barnett shale basin and a dozen well pads in the Eagle Ford shale region of Texas. We compare our field measurements to reported inventory estimates from the Greenhouse Gas Reporting Program (GHGRP). Using an aircraft-based mass balance approach, we found that the summed observed CH4 emission rates for our study sites were a factor of 2.5 to 4.5 greater than the GHGRP-based estimates, for the 8 sources we investigated in the Barnett shale region. The sum of the 5 Barnett NG sources we quantified had on average CH4 emissions 17.5X higher than the GHGRP inventory indicates. The sum of the 3 landfill emission rates were on average 1.5X greater than the inventory values. In the Eagle Ford shale region, high variability was observed in repeated measurements at the same well pads, highlighting the difficulty of assessing the character and statistics of the distribution of emissions from individual pads. These results indicate a need for better methods of emissions monitoring and reporting and highlight the continuing importance of effectively connecting bottom up and top down methods.

  9. Data and model investigation of Martian methane and other trace gases

    NASA Astrophysics Data System (ADS)

    Chizek, Malynda Rebecca

    Derived trace abundances of methane from recent observations of the Mars atmosphere (Krasnopolsky et al. 2004; Krasnopolsky 2012; Formisano et al. 2004; Geminale et al. 2008, 2011; Mumma et al. 2009; Fonti & Marzo 2010) showed that methane gas is unexpectedly variable in both abundance (~0-70 parts per billion) and spatial distribution. Interest has arisen in investigating possible source and removal mechanisms because of implications of current or recent biological or geological activity, but available seasonal and spatial information is sparse. Questions have been raised regarding derived methane abundances (Zahnle et al. 2011), and MSL's first measurements have not confirmed detection of methane (Webster et al., 2013), but the observations include commonalities suggesting they are observing a common species. To increase the temporal coverage of available methane observations, an expansion of the work of Fonti & Marzo (2010) was carried out, increasing the twelve 5 degree L8 interval average maps to all available 10 degree L8 intervals with enough spectra in the 3 Martian years of Mars Global Surveyor Thermal Emission Spectrometer data (L8 103° MY 24 to L8 90° MY 27). A procedure was developed to significantly accelerate the analysis process to allow for this expansion work, and resulting maps have been produced. The NASA Ames Mars Global Circulation Model (GCM) was utilized to investigate possible source locations, sizes and release rates, and destruction timescales required to reproduce the observed methane spatial and temporal distributions of Mumma et al. (2009); Fonti & Marzo (2010) and Geminale et al. (2011). Parameters required to reasonably reproduce the observed variations in each scenario were established and compared to determine whether common source characteristics exist. The different observations do not suggest similar source locations or seasonal behavior, but do share similar peak mixing ratios and destruction lifetimes ~2 orders of magnitude shorter than expected through photochemical removal only. An additional GCM investigation has been conducted to explore temperature dependent fractionation of isotopic CO2 using tools developed in methane simulations and provide predictions for future spatially resolved measurements (Livengood et al. 2013).

  10. Assessment of Microbial Methane Oxidation Above a Petroleum-Contaminated Aquifer Using Gas Push-Pull Tests, Stable Carbon Isotope Fractionation and Profile Modeling

    NASA Astrophysics Data System (ADS)

    Urmann, K.; Gonzalez-Gil, G.; Schroth, M. H.; Zeyer, J.

    2004-12-01

    Microbial methane oxidation is an important process reducing methane emissions from different environments such as landfills, peat bogs and contaminated aquifers. We applied the recently developed gas push-pull test (GPPT) to quantify methanotrophic activity and stable carbon isotope fractionation in-situ above a methanogenic petroleum-contaminated aquifer in Studen, Switzerland. The GPPT consists of the injection of a gas mixture of reactants methane and oxygen and non-reactive tracers neon and argon into the vadose zone followed by its extraction together with soil air from the same location. Rate constants of methane oxidation are then calculated from breakthrough curves of extracted methane and neon. We performed six GPPTs, four at 2.7m depth, directly above the groundwater table and two at 1.1m depth. Methane injection concentrations ranged from 17 ml/L to 195 ml/L. At 2.7m depth, rate constants decreased with increasing injection concentration. This indicated that methane oxidation followed Michaelis-Menten kinetics. Rate constants measured at low or medium methane concentrations in the GPPTs were in good agreement with a rate constant calculated from a previously measured gas profile. During the GPPTs we also quantified stable carbon isotope fractionation in methane. The computed fractionation factor ? ranged from 5.3 ‰ to 29.5 ‰ with stronger fractionation during the tests with higher methane concentrations. The strongest fractionation occurred during the tests at 1.1m depth. At this depth calculated rate constants were more than three times lower than in the zone directly above the aquifer while methane concentrations remained higher throughout the tests. Thus, while GPPTs and gas profile modeling allowed direct quantification of microbial methane oxidation, the use of stable carbon isotope analysis for this purpose may be more complicated due to the observed variability in isotopic fractionation.

  11. Evaluation of non-methane hydrocarbon (NMHC) emissions based on an ambient air measurement in Tokyo area, Japan

    NASA Astrophysics Data System (ADS)

    Matsunaga, Sou N.; Chatani, Satoru; Morikawa, Tazuko; Nakatsuka, Seiji; Suthawaree, Jeeranut; Tajima, Yosuke; Kato, Shungo; Kajii, Yoshizumi; Minoura, Hiroaki

    2010-12-01

    Non-methane hydrocarbons (NMHCs) are known to have an important role on air quality due to their high reactivity. NMHC analysis has been performed on 148 ambient air samples collected at five different sites in the Kanto area (Tokyo metropolitan area and surrounding six prefectures) of Japan in summer and winter of 2008, and fifty NMHCs have been determined and quantified. A field measurement campaign has been conducted at one of the busiest intersections in Tokyo metropolitan area in winter of 2008. NMHC emissions are evaluated through comparison of distributions of individual NMHCs emitted from motor vehicles, which are estimated from the measurements, with those determined from the current emissions inventory. The comparison revealed that the measured distributions of acetylene, ethylene and toluene showed a good agreement with those estimated from the emissions inventory (the values estimated from the measurements are a factor of 1.5, 0.56 and 2.3 larger than the emissions inventory in median, respectively), however, propane and isobutane are found to be significantly underestimated in the emissions inventory (the measured values were a factor of 18 and 5.1 larger than the emissions inventory, respectively). The significant underestimate of propane can be explained by that the current emissions inventory does not consider emissions from liquefied propane gas (LPG) fueled vehicles. However, for isobutane, reasons for the underestimate are still unclear. Another field measurement has been conducted in summer of 2008, where the air samples have been collected at three different sites on the ground and by a helicopter as well. Remarkable high concentrations of 1-butene and cis- and trans-2-butenes have been sporadically observed in the samples collected at Urayasu in the coastal area of Tokyo bay. Calculated propylene equivalent (PE) concentrations of butenes revealed that those have a significantly important role in ozone formation when the air plume is affected by emissions from their emission sources. The PE concentrations of butenes varied from 0.1 to 39 ppbC, and accounted for 1.5-75% of total PE concentrations at Urayasu. Most of the continuous air quality monitoring stations does not record concentrations of individual hydrocarbons, therefore, the importance of reactive and low concentration hydrocarbon such as butenes might be overlooked in the current emissions inventory and/or air quality model. In this paper, the reliability of NMHC emissions is evaluated based on the field measurements. Their possible impacts on air quality in the Kanto area are discussed as well, based on the calculated propylene equivalent concentrations.

  12. Does diverse grazing behavior of suckler cows have an impact on predicted methane emissions?

    PubMed

    Ricci, P; Umstätter, C; Holland, J P; Waterhouse, A

    2014-03-01

    A modeling study based on a dataset from a large-scale grazing study was used to identify the potential impact of grazing behavior and performance of diverse cow genotypes on predicted methane (CH4) emissions. Lactating cows grazing extensive seminatural grassland and heath vegetation were monitored with Global Positioning System collars and activity sensors. The diet selected by cows of 3 different genotypes, Aberdeen Angus cross Limousin (AxL), Charolais (CHA), and Luing (LUI), was simulated by matching their locations during active periods with hill vegetation maps. Measured performance and activity were used to predict energy requirements, DMI, and CH4 output. The cumulative effect of actual performance, diet selection, and actual physical activity on potential CH4 output and yield was estimated. Sensitivity analyses were performed for the digestibility of intake, energy cost of activity, proportion of milk consumed by calves, and reproductive efficiency. Although with a better performance (P < 0.05), LUI required less total energy than the other genotypes (P < 0.001) as the other 2 spent more energy for maintenance (P < 0.001) and activity (P < 0.001). By selecting a better quality diet (P < 0.03), estimated CH4 of CHA cow-calf pairs was lower than AxL (P = 0.001) and slightly lower than LUI (P = 0.08). Energy lost as CH4 was 0.17 and 0.58% lower for LUI than AxL and CHA (P < 0.002). This study suggests for the first time that measured activity has a major impact on estimated CH4 outputs. A 15% difference of the cow-calf pair CH4 was estimated when using different coefficients to convert actual activity into energy. Predicted CH4 was highly sensitive to small changes in diet quality, suggesting the relative importance of diet selection on heterogeneous rangelands. Extending these results to a farm systems scale, CH4 outputs were also highly sensitive to reductions in weaning rates, illustrating the impact on CH4 at the farm-system level of using poorly adapted genotypes on habitats where their performances may be compromised. This paper demonstrates that variations in grazing behavior and grazing choice have a potentially large impact on CH4 emissions, illustrating the importance of including these factors in calculating realistic national and global estimates. PMID:24665106

  13. Methane Emissions and Production Potentials of Forest Swamp Wetlands in the Eastern Great Xing'an Mountains, Northeast China

    NASA Astrophysics Data System (ADS)

    Yu, Bing; Stott, Philip; Yu, Hongxian; Li, Xiaoyu

    2013-11-01

    Measurements of methane flux at a few inundated sites in China have been extrapolated to obtain estimates on a national scale. To enable those national estimates to be refined and to compare flux from geographically separated sites comprising the same wetland types, we used a closed chamber method to measure methane flux in uninundated Betula platyphylla—and Larix gmelinii—dominated peatlands in the Northeast China. Our measurements were taken from both vegetated and bare soil surfaces, and we compared flux with environmental measures including vegetation biomass, soil temperature and soil characteristics. We found that methane flux was low, and that there were no significant differences between wetland types, indicating that environmental influences were dominant. We found that flux was positively correlated to temperature in the surface layers of the soil, the above-ground biomass of the shrub and herb layers, total soil carbon and total soil nitrogen; and we suggest that emissions may be due to anaerobic microcosms in the surface layers. The methane production potentials of the soils were low and similar between both sites but inconsistent with the differences between fluxes, and inconsistent with production potentials and fluxes reported from the same wetland types elsewhere, indicating that there were subtle environmental differences between wetlands classed as being of the same type. Differences between fluxes in vegetated chambers with bare soil chambers were insignificant, indicating that no methane emission through aerenchyma occurred at our sites. We concluded that wetland type was not an accurate predictor of methane flux.

  14. Effect of industrial by-products containing electron acceptors on mitigating methane emission during rice cultivation

    SciTech Connect

    Ali, Muhammad Aslam [Department of Environmental Science, Bangladesh Agricultural University, Mymensingh 2202 (Bangladesh); Lee, Chang Hoon [Functional Cereal Crop Research Division, National Institute of Crop Science, RDA, 1085, Naey-dong, Milyang (Korea, Republic of); Kim, Sang Yoon [Division of Applied Life Science, Graduate School (Brain Korea 21 Program), Gyeongsang National University, Jinju 660-701 (Korea, Republic of); Kim, Pil Joo [Division of Applied Life Science, Graduate School (Brain Korea 21 Program), Gyeongsang National University, Jinju 660-701 (Korea, Republic of); Institute of Agriculture and Life Sciences, Gyeongsang National University, Jinju 660-701 (Korea, Republic of)], E-mail: pjkim@gnu.ac.kr

    2009-10-15

    Three industrial by-products (fly ash, phosphogypsum and blast furnace slag), were evaluated for their potential re-use as soil amendments to reduce methane (CH{sub 4}) emission resulting from rice cultivation. In laboratory incubations, CH{sub 4} production rates from anoxic soil slurries were significantly reduced at amendment levels of 0.5%, 1%, 2% and 5% (wt wt{sup -1}), while observed CO{sub 2} production rates were enhanced. The level of suppression in methane production was the highest for phosphogypsum, followed by blast slag and then fly ash. In the greenhouse experiment, CH{sub 4} emission rates from the rice planted potted soils significantly decreased with the increasing levels (2-20 Mg ha{sup -1}) of the selected amendments applied, while rice yield simultaneously increased compared to the control treatment. At 10 Mg ha{sup -1} application level of the amendments, total seasonal CH{sub 4} emissions were reduced by 20%, 27% and 25%, while rice grain yields were increased by 17%, 15% and 23% over the control with fly ash, phosphogypsum, and blast slag amendments, respectively. The suppression of CH{sub 4} production rates as well as total seasonal CH{sub 4} flux could be due to the increased concentrations of active iron, free iron, manganese oxides, and sulfate in the amended soil, which acted as electron acceptors and controlled methanogens' activity by limiting substrates availability. Among the amendments, blast furnace slag and fly ash contributed mainly to improve the soil nutrients balance and increased the soil pH level towards neutral point, but soil acidity was developed with phosphogypsum application. Conclusively, blast slag among the selected amendments would be a suitable soil amendment for reducing CH{sub 4} emissions as well as sustaining rice productivity.

  15. Effect of industrial by-products containing electron acceptors on mitigating methane emission during rice cultivation.

    PubMed

    Ali, Muhammad Aslam; Lee, Chang Hoon; Kim, Sang Yoon; Kim, Pil Joo

    2009-10-01

    Three industrial by-products (fly ash, phosphogypsum and blast furnace slag), were evaluated for their potential re-use as soil amendments to reduce methane (CH(4)) emission resulting from rice cultivation. In laboratory incubations, CH(4) production rates from anoxic soil slurries were significantly reduced at amendment levels of 0.5%, 1%, 2% and 5% (wt wt(-1)), while observed CO(2) production rates were enhanced. The level of suppression in methane production was the highest for phosphogypsum, followed by blast slag and then fly ash. In the greenhouse experiment, CH(4) emission rates from the rice planted potted soils significantly decreased with the increasing levels (2-20 Mg ha(-1)) of the selected amendments applied, while rice yield simultaneously increased compared to the control treatment. At 10 Mg ha(-1) application level of the amendments, total seasonal CH(4) emissions were reduced by 20%, 27% and 25%, while rice grain yields were increased by 17%, 15% and 23% over the control with fly ash, phosphogypsum, and blast slag amendments, respectively. The suppression of CH(4) production rates as well as total seasonal CH(4) flux could be due to the increased concentrations of active iron, free iron, manganese oxides, and sulfate in the amended soil, which acted as electron acceptors and controlled methanogens' activity by limiting substrates availability. Among the amendments, blast furnace slag and fly ash contributed mainly to improve the soil nutrients balance and increased the soil pH level towards neutral point, but soil acidity was developed with phosphogypsum application. Conclusively, blast slag among the selected amendments would be a suitable soil amendment for reducing CH(4) emissions as well as sustaining rice productivity. PMID:19560334

  16. Three decades of global methane sources and sinks

    NASA Astrophysics Data System (ADS)

    Kirschke, Stefanie; Bousquet, Philippe; Ciais, Philippe; Saunois, Marielle; Canadell, Josep G.; Dlugokencky, Edward J.; Bergamaschi, Peter; Bergmann, Daniel; Blake, Donald R.; Bruhwiler, Lori; Cameron-Smith, Philip; Castaldi, Simona; Chevallier, Frédéric; Feng, Liang; Fraser, Annemarie; Heimann, Martin; Hodson, Elke L.; Houweling, Sander; Josse, Béatrice; Fraser, Paul J.; Krummel, Paul B.; Lamarque, Jean-François; Langenfelds, Ray L.; Le Quéré, Corinne; Naik, Vaishali; O'Doherty, Simon; Palmer, Paul I.; Pison, Isabelle; Plummer, David; Poulter, Benjamin; Prinn, Ronald G.; Rigby, Matt; Ringeval, Bruno; Santini, Monia; Schmidt, Martina; Shindell, Drew T.; Simpson, Isobel J.; Spahni, Renato; Steele, L. Paul; Strode, Sarah A.; Sudo, Kengo; Szopa, Sophie; van der Werf, Guido R.; Voulgarakis, Apostolos; van Weele, Michiel; Weiss, Ray F.; Williams, Jason E.; Zeng, Guang

    2013-10-01

    Methane is an important greenhouse gas, responsible for about 20% of the warming induced by long-lived greenhouse gases since pre-industrial times. By reacting with hydroxyl radicals, methane reduces the oxidizing capacity of the atmosphere and generates ozone in the troposphere. Although most sources and sinks of methane have been identified, their relative contributions to atmospheric methane levels are highly uncertain. As such, the factors responsible for the observed stabilization of atmospheric methane levels in the early 2000s, and the renewed rise after 2006, remain unclear. Here, we construct decadal budgets for methane sources and sinks between 1980 and 2010, using a combination of atmospheric measurements and results from chemical transport models, ecosystem models, climate chemistry models and inventories of anthropogenic emissions. The resultant budgets suggest that data-driven approaches and ecosystem models overestimate total natural emissions. We build three contrasting emission scenarios -- which differ in fossil fuel and microbial emissions -- to explain the decadal variability in atmospheric methane levels detected, here and in previous studies, since 1985. Although uncertainties in emission trends do not allow definitive conclusions to be drawn, we show that the observed stabilization of methane levels between 1999 and 2006 can potentially be explained by decreasing-to-stable fossil fuel emissions, combined with stable-to-increasing microbial emissions. We show that a rise in natural wetland emissions and fossil fuel emissions probably accounts for the renewed increase in global methane levels after 2006, although the relative contribution of these two sources remains uncertain.

  17. Beaver-mediated methane emission: The effects of population growth in Eurasia and the Americas.

    PubMed

    Whitfield, Colin J; Baulch, Helen M; Chun, Kwok P; Westbrook, Cherie J

    2015-02-01

    Globally, greenhouse gas budgets are dominated by natural sources, and aquatic ecosystems are a prominent source of methane (CH4) to the atmosphere. Beaver (Castor canadensis and Castor fiber) populations have experienced human-driven change, and CH4 emissions associated with their habitat remain uncertain. This study reports the effect of near extinction and recovery of beavers globally on aquatic CH4 emissions and habitat. Resurgence of native beaver populations and their introduction in other regions accounts for emission of 0.18-0.80 Tg CH4 year(-1) (year 2000). This flux is approximately 200 times larger than emissions from the same systems (ponds and flowing waters that became ponds) circa 1900. Beaver population recovery was estimated to have led to the creation of 9500-42 000 km(2) of ponded water, and increased riparian interface length of >200 000 km. Continued range expansion and population growth in South America and Europe could further increase CH4 emissions. PMID:25515021

  18. Mitigation of methane emission from Fakse landfill using a biowindow system

    SciTech Connect

    Scheutz, Charlotte, E-mail: chs@env.dtu.dk [Department of Environmental Engineering, Technical University of Denmark, Miljovej - Building 113, 2800 Kongens Lyngby (Denmark); Fredenslund, Anders M., E-mail: amf@env.dtu.dk [Department of Environmental Engineering, Technical University of Denmark, Miljovej - Building 113, 2800 Kongens Lyngby (Denmark); Chanton, Jeffrey, E-mail: jchanton@fsu.edu [Department of Earth, Ocean and Atmospheric Science, 117 N. Woodward Avenue, Florida State University, Tallahassee, Fl 32306-4320 (United States); Pedersen, Gitte Bukh, E-mail: gbp@env.dtu.dk [Department of Environmental Engineering, Technical University of Denmark, Miljovej - Building 113, 2800 Kongens Lyngby (Denmark); Kjeldsen, Peter, E-mail: pk@env.dtu.dk [Department of Environmental Engineering, Technical University of Denmark, Miljovej - Building 113, 2800 Kongens Lyngby (Denmark)

    2011-05-15

    Landfills are significant sources of atmospheric methane (CH{sub 4}) that contributes to climate change, and therefore there is a need to reduce CH{sub 4} emissions from landfills. A promising cost efficient technology is to integrate compost into landfill covers (so-called 'biocovers') to enhance biological oxidation of CH{sub 4}. A full scale biocover system to reduce CH{sub 4} emissions was installed at Fakse landfill, Denmark using composted yard waste as active material supporting CH{sub 4} oxidation. Ten biowindows with a total area of 5000 m{sup 2} were integrated into the existing cover at the 12 ha site. To increase CH{sub 4} load to the biowindows, leachate wells were capped, and clay was added to slopes at the site. Point measurements using flux chambers suggested in most cases that almost all CH{sub 4} was oxidized, but more detailed studies on emissions from the site after installation of the biocover as well as measurements of total CH{sub 4} emissions showed that a significant portion of the emission quantified in the baseline study continued unabated from the site. Total emission measurements suggested a reduction in CH{sub 4} emission of approximately 28% at the end of the one year monitoring period. This was supported by analysis of stable carbon isotopes which showed an increase in oxidation efficiency from 16% to 41%. The project documented that integrating approaches such a whole landfill emission measurements using tracer techniques or stable carbon isotope measurements of ambient air samples are needed to document CH{sub 4} mitigation efficiencies of biocover systems. The study also revealed that there still exist several challenges to better optimize the functionality. The most important challenges are to control gas flow and evenly distribute the gas into the biocovers.

  19. Isotopic Characterisation of Methane Emissions: use of Keeling-plot Methods to Identify Source Signatures in Boreal Wetlands and Other Settings

    NASA Astrophysics Data System (ADS)

    Fisher, R. E.; Lowry, D.; France, J.; Lanoiselle, M.; Zazzeri, G.; Nisbet, E. G.

    2012-12-01

    Different methane sources have different ?13CCH4 and ?DCH4 signatures, which potentially provides a powerful constraint on models of methane emission budgets. However source signatures remain poorly known and need to be studied in more detail if isotopic measurements of ambient air are to be used to constrain regional and global emissions. The Keeling plot method (plotting ?13CCH4 or ?DCH4 against 1/CH4 concentration in samples of ambient air in the close vicinity of known sources) directly assesses the source signature of the methane that is actually emitted to the air. This contrasts with chamber studies, measuring air within a chamber, where local micro-meteorological and microbiological processes are occurring. Keeling plot methods have been applied to a wide variety of settings in this study. The selection of appropriate background measurements for Keeling plot analysis is also considered. The method has been used on a local scale to identify the source signature of summer emissions from subarctic wetlands in Fennoscandia. Samples are collected from low height (0.3-3m) over the wetlands during 24-hour periods, to collect daily emissions maxima (warm late afternoons), inversion maxima (at the coldest time of the 24hr daylight: usually earliest morning), and ambient minima when mixing occurs (often mid afternoon). Some results are comparable to parallel chamber studies, but in other cases there are small but significant shifts between CH4 in chamber air and CH4 that is dispersing in the above-ground air. On a regional to continental scale the isotopic signature of bulk sources of emissions can be identified using Keeling plots. The methodology is very applicable for use in urban and urban-rural settings. For example, the winter SE monsoon sweeps from inland central Asia over China to Hong Kong. Application of back trajectory analysis and Keeling plot methods implied coal emissions may be a significant Chinese source of methane in January, although in other months biological sources dominate. Similarly, in London the method has been used to test the London methane emission inventory.

  20. Methane and other greenhouse gases in the Arctic - Measurements, Process Studies and Modelling (MAMM)

    NASA Astrophysics Data System (ADS)

    Pyle, John; Cain, Michelle; Warwick, Nicola

    2014-05-01

    The Arctic is a major source of atmospheric methane and other greenhouse gases, of both natural and anthropogenic origin. Arctic greenhouse gas sources need to be quantified, by strength, geographic location, character (e.g. wetlands, gas fields, hydrates), and by temporal variation (daily, seasonally and annually), and their vulnerability to change assessed. To this end, the MAMM project was commissioned as part of the NERC Arctic Research Programme. It involves an integrated series of measurement and modelling activities. Analysis of atmospheric gas concentrations, isotopic character, and source fluxes, are being made from both the ground and from the FAAM aircraft. The measurements (historic and new) are being interpreted using a suite of models (trajectory, forward and inverse) to improve the understanding of the local/regional scale, placing the role of Arctic emissions in the context of large-scale global atmospheric change. The first measurement campaign was held in August 2012. Surface flux measurements were made at the Sodankylä research station in Finland, together with in-situ surface and aircraft measurements over a wider area. In addition to flights over the Sodankylä wetlands, the aircraft also flew out to Svalbard to investigate marine sources of methane. Further campaigns are taking place in Sweden in August and September 2013. The initial measurements have been used to infer wetland emission fluxes and confirm that Scandinavian wetlands are a major source of methane in this region. The aircraft also measured a high-CH4 plume over the sea between Norway and Svalbard, which was likely advected from mainland wetland sources. An overview of results from the field campaign will be presented, alongside results from the NAME model (the UK Met Office's Numerical Atmospheric dispersion Modelling Environment) to help understand the air mass histories of the observations.

  1. Initial results of detected methane emissions from landfills in the Los Angeles Basin during the COMEX campaign by the Methane Airborne MAPper (MAMAP) instrument and a greenhouse gas in-situ analyser

    NASA Astrophysics Data System (ADS)

    Krautwurst, Sven; Gerilowski, Konstantin; Kolyer, Richard; Jonsson, Haflidi; Krings, Thomas; Horstjann, Markus; Leifer, Ira; Vigil, Sam; Buchwitz, Michael; Schüttemeyer, Dirk; Fladeland, Matthew M.; Burrows, John P.; Bovensmann, Heinrich

    2015-04-01

    Methane (CH4) is the second most important anthropogenic greenhouse gas beside carbon dioxide (CO2). Significant contributors to the global methane budget are fugitive emissions from landfills. Due to the growing world population, it is expected that the amount of waste and, therefore, waste disposal sites will increase in number and size in parts of the world, often adjacent growing megacities. Besides bottom-up modelling, a variety of ground based methods (e.g., flux chambers, trace gases, radial plume mapping, etc.) have been used to estimate (top-down) these fugitive emissions. Because landfills usually are large, sometimes with significant topographic relief, vary temporally, and leak/emit heterogeneously across their surface area, assessing total emission strength by ground-based techniques is often difficult. In this work, we show how airborne based remote sensing measurements of the column-averaged dry air mole fraction of CH4 can be utilized to estimate fugitive emissions from landfills in an urban environment by a mass balance approach. Subsequently, these emission rates are compared to airborne in-situ horizontal cross section measurements of CH4 taken within the planetary boundary layer (PBL) upwind and downwind of the landfill at different altitudes immediately after the remote sensing measurements were finished. Additional necessary parameters (e.g., wind direction, wind speed, aerosols, dew point temperature, etc.) for the data inversion are provided by a standard instrumentation suite for atmospheric measurements aboard the aircraft, and nearby ground-based weather stations. These measurements were part of the CO2 and Methane EXperiment (COMEX), which was executed during the summer 2014 in California and was co-funded by the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA). The remote sensing measurements were taken by the Methane Airborne MAPper (MAMAP) developed and operated by the University of Bremen and the German Research Center for Geoscience (GFZ) in Potsdam. The in-situ measurements were obtained by a greenhouse gas (GHG) in-situ analyser operated by NASA's Ames Research Center (ARC). Both instruments were installed aboard a DHC-6 Twin Otter aircraft operated by the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS). Initial results - including estimated fugitive emission rates - will be presented for the landfill Olinda Alpha in Brea, Orange County, Los Angeles Basin, California, which was overflown on four different days during the COMEX field campaign in late summer 2014.

  2. Effects of organic nitrification inhibitors on methane and nitrous oxide emission from tropical rice paddy

    NASA Astrophysics Data System (ADS)

    Datta, A.; Adhya, T. K.

    2014-08-01

    We have studied the effects of application of different nitrification inhibitors on methane (CH4) and nitrous oxide (N2O) emissions from rice paddy and associated soil chemical and biological dynamics during wet and dry seasons of rice crop in a tropical climate of eastern India. The experiment consisted of four treatments viz. (i) Prilled urea amended control (ii) urea + Dicyandiamide (DCD), (iii) urea + Nimin and (iv) urea + Karanjin. CH4 emission was significantly higher from the DCD (372.36 kg ha-1) and Karanjin (153.07 kg ha-1) applied plots during the wet and dry season, respectively. N2O emission was significantly inhibited in the Nimin applied plots during both seasons (69% and 85% over control during wet season and dry season respectively). CH4 and N2O emissions per Mg of rice grain yield were lowest from the Nimin applied plots during both seasons. Global warming potential (GWP) of the plot treated with DCD (13.93) was significantly higher during the experimental period. CH4 production potential was significantly higher from the nitrification inhibitor applied plots compared to control. While, CH4 oxidation potential followed the order; urea + Nimin > urea + Karanjin > urea + DCD > control. Application of Nimin significantly increased the methanotrophic bacterial population in the soil during the maximum tillering to flowering stage and may be attributed to low CH4 emission from the plots. Denitrification enzyme activity (DEA) of the soil was significantly low from the Nimin and Karanjin applied plots. Results suggest that apart from being potent nitrification inhibitors, Nimin and Karanjin also have the potential to reduce the denitrification activity in the soil. This in turn, would reduce N2O emission from flooded paddy where both nitrification and denitrification processes causes N2O emission.

  3. Present state of global wetland extent and wetland methane modelling: methodology of a model intercomparison project (WETCHIMP)

    NASA Astrophysics Data System (ADS)

    Wania, R.; Melton, J. R.; Hodson, E. L.; Poulter, B.; Ringeval, B.; Spahni, R.; Bohn, T.; Avis, C. A.; Chen, G.; Eliseev, A. V.; Hopcroft, P. O.; Riley, W. J.; Subin, Z. M.; Tian, H.; Brovkin, V.; van Bodegom, P. M.; Kleinen, T.; Yu, Z. C.; Singarayer, J. S.; Zürcher, S.; Lettenmaier, D. P.; Beerling, D. J.; Denisov, S. N.; Prigent, C.; Papa, F.; Kaplan, J. O.

    2012-12-01

    The Wetland and Wetland CH4 Intercomparison of Models Project (WETCHIMP) was created to evaluate our present ability to simulate large-scale wetland characteristics and corresponding methane (CH4) emissions. A multi-model comparison is essential to evaluate the key uncertainties in the mechanisms and parameters leading to methane emissions. Ten modelling groups joined WETCHIMP to run eight global and two regional models with a common experimental protocol using the same climate and atmospheric carbon dioxide (CO2) forcing datasets. We reported the main conclusions from the intercomparison effort in a companion paper (Melton et al., 2012). Here we provide technical details for the six experiments, which included an equilibrium, a transient, and an optimized run plus three sensitivity experiments (temperature, precipitation, and atmospheric CO2 concentration). The diversity of approaches used by the models is summarized through a series of conceptual figures, and is used to evaluate the wide range of wetland extents and CH4 fluxes predicted by the models in the equilibrium run. We discuss relationships among the various approaches and patterns in consistencies of these model predictions. Within this group of models, there are three broad classes of methods used to estimate wetland extent: prescribed based on wetland distribution maps, prognostic relationships between hydrological states based on satellite observations, and explicit hydrological mass balances. A larger variety of approaches was used to estimate the net CH4 fluxes from wetland systems. Even though modelling of wetland extents and CH4 emissions has progressed significantly over recent decades, large uncertainties still exist when estimating CH4 emissions: there is little consensus on model structure or complexity due to knowledge gaps, different aims of the models, and the range of temporal and spatial resolutions of the models.

  4. Present state of global wetland extent and wetland methane modelling: methodology of a model inter-comparison project (WETCHIMP)

    NASA Astrophysics Data System (ADS)

    Wania, R.; Melton, J. R.; Hodson, E. L.; Poulter, B.; Ringeval, B.; Spahni, R.; Bohn, T.; Avis, C. A.; Chen, G.; Eliseev, A. V.; Hopcroft, P. O.; Riley, W. J.; Subin, Z. M.; Tian, H.; van Bodegom, P. M.; Kleinen, T.; Yu, Z. C.; Singarayer, J. S.; Zürcher, S.; Lettenmaier, D. P.; Beerling, D. J.; Denisov, S. N.; Prigent, C.; Papa, F.; Kaplan, J. O.

    2013-05-01

    The Wetland and Wetland CH4 Intercomparison of Models Project (WETCHIMP) was created to evaluate our present ability to simulate large-scale wetland characteristics and corresponding methane (CH4) emissions. A multi-model comparison is essential to evaluate the key uncertainties in the mechanisms and parameters leading to methane emissions. Ten modelling groups joined WETCHIMP to run eight global and two regional models with a common experimental protocol using the same climate and atmospheric carbon dioxide (CO2) forcing datasets. We reported the main conclusions from the intercomparison effort in a companion paper (Melton et al., 2013). Here we provide technical details for the six experiments, which included an equilibrium, a transient, and an optimized run plus three sensitivity experiments (temperature, precipitation, and atmospheric CO2 concentration). The diversity of approaches used by the models is summarized through a series of conceptual figures, and is used to evaluate the wide range of wetland extent and CH4 fluxes predicted by the models in the equilibrium run. We discuss relationships among the various approaches and patterns in consistencies of these model predictions. Within this group of models, there are three broad classes of methods used to estimate wetland extent: prescribed based on wetland distribution maps, prognostic relationships between hydrological states based on satellite observations, and explicit hydrological mass balances. A larger variety of approaches was used to estimate the net CH4 fluxes from wetland systems. Even though modelling of wetland extent and CH4 emissions has progressed significantly over recent decades, large uncertainties still exist when estimating CH4 emissions: there is little consensus on model structure or complexity due to knowledge gaps, different aims of the models, and the range of temporal and spatial resolutions of the models.

  5. Diurnal cycle of methane flux from a lake, with high emissions during nighttime caused by convection in the water

    NASA Astrophysics Data System (ADS)

    Podgrajsek, E.; Sahlee, E.; Rutgersson, A.

    2012-12-01

    Many studies have stressed the importance of lakes as major contributors of methane to the atmosphere (e.g. Bastviken et al 2011). However there is still a lack of continuous long time flux measurements over lakes as well as poor understanding of the magnitude of methane fluxes through ebullition and vegetation pathways. In this study the Eddy covariance method has been used for measuring methane fluxes from a lake in central Sweden. At several occasions during the long time measuring campaign (autumn 2010-autumn 2012), a diurnal cycle of methane, with high fluxes during night and low during day, has been captured. Some of the high flux events during nighttime were comparable in magnitude to what previously only been measured from vegetation regions in lakes at these latitudes (e.g. Kankaala et al 2004) and from tropical reservoirs (e.g. Bastviken 2009). During these occasions the difference between air and water temperature (?T=Ta-Tw) also displayed an diurnal cycle, with ?T being positive during day and negative during night with the corresponding change in the sensible heat flux i.e. negative during daytime and positive during nighttime. The high nighttime methane fluxes could be explained with this difference in air and water temperature, which will cool the water surface during night, creating convective mixing in the lake, while during daytime the water will be stably stratified. Temperature measurements made at different vertical levels in the lake water confirm this water stratification. The nighttime convective mixing may act to disturb the bottom water, triggering methane ebullition events and bringing methane rich water up to the surface, which can be emitted to the atmosphere. With this study we want to emphasis the necessity of introducing also complex physical processes when estimating air-water exchange fluxes and also measure methane fluxes not only at few occasions during daytime but also during night and for longer measuring periods. References: Bastviken D. (2009) Methane. In Likens G. (Ed.), Encyclopedia of Inland Waters, Oxford, Elsevier, p 783-805. Bastviken D., Tranvik L., Downing J., Crill P. and Enrich-Prast A. (2011) Freshwater Methane Emissions Offset the Continental Carbon Sink. Science, Vol 331:50, 7 January. Kankaala P., Ojala A. and Käki T. (2004) Temporal and spatial variation in methane emissions from a flooded transgression shore of a boreal lake. Biogeochemistry 68: 297-311.

  6. Evidence for a nonmonotonic relationship between ecosystem-scale peatland methane emissions and water table depth

    NASA Astrophysics Data System (ADS)

    Brown, Mathew G.; Humphreys, Elyn R.; Moore, Tim R.; Roulet, Nigel T.; Lafleur, Peter M.

    2014-05-01

    Although temporal and spatial variations in peatland methane (CH4) emissions at broad scales are often related to water table (WT) using a linear relationship, a potentially complex relationship exists between these variables locally and over shorter time scales. To explore this issue, CH4 fluxes were measured using eddy covariance at the Mer Bleue bog over two summer seasons. Peak CH4 emissions (30 to 50 mg CH4-C m-2 d-1) occurred not when the WT was closest to the surface but instead, when it dropped to 40 to 55 cm below the surface. When the WT was below or above this zone, average fluxes were ~14 mg CH4-C m-2 d-1. We speculate this critical zone coincides with the necessary redox potentials and sources of fresh organic material that lead to maximum production of CH4 and/or with conditions that lead to degassing of stored CH4. However, as expected, total summer CH4 emissions were 47% lower during the drier year. This occurred in part because the WT was within the critical zone for fewer days in the drier year but also because after an extended midsummer dry period there was little recovery of CH4 emissions, even a month after rewetting.

  7. Aircraft-Based Estimate of Total Methane Emissions from the Barnett Shale Region.

    PubMed

    Karion, Anna; Sweeney, Colm; Kort, Eric A; Shepson, Paul B; Brewer, Alan; Cambaliza, Maria; Conley, Stephen A; Davis, Ken; Deng, Aijun; Hardesty, Mike; Herndon, Scott C; Lauvaux, Thomas; Lavoie, Tegan; Lyon, David; Newberger, Tim; Pétron, Gabrielle; Rella, Chris; Smith, Mackenzie; Wolter, Sonja; Yacovitch, Tara I; Tans, Pieter

    2015-07-01

    We present estimates of regional methane (CH4) emissions from oil and natural gas operations in the Barnett Shale, Texas, using airborne atmospheric measurements. Using a mass balance approach on eight different flight days in March and October 2013, the total CH4 emissions for the region are estimated to be 76 ± 13 × 10(3) kg hr(-1) (equivalent to 0.66 ± 0.11 Tg CH4 yr(-1); 95% confidence interval (CI)). We estimate that 60 ± 11 × 10(3) kg CH4 hr(-1) (95% CI) are emitted by natural gas and oil operations, including production, processing, and distribution in the urban areas of Dallas and Fort Worth. This estimate agrees with the U.S. Environmental Protection Agency (EPA) estimate for nationwide CH4 emissions from the natural gas sector when scaled by natural gas production, but it is higher than emissions reported by the EDGAR inventory or by industry to EPA's Greenhouse Gas Reporting Program. This study is the first to show consistency between mass balance results on so many different days and in two different seasons, enabling better quantification of the related uncertainty. The Barnett is one of the largest production basins in the United States, with 8% of total U.S. natural gas production, and thus, our results represent a crucial step toward determining the greenhouse gas footprint of U.S. onshore natural gas production. PMID:26148550

  8. A model of the methane cycle, permafrost, and hydrology of the Siberian continental margin

    DOE PAGESBeta

    Archer, D.

    2015-01-01

    A two-dimensional model of a sediment column, with Darcy fluid flow, biological and thermal methane production, and permafrost and methane hydrate formation, is subjected to glacial–interglacial cycles in sea level, alternately exposing the continental shelf to the cold atmosphere during glacial times and immersing it in the ocean in interglacial times. The glacial cycles are followed by a "long-tail" 100 kyr warming due to fossil fuel combustion. The salinity of the sediment column in the interior of the shelf can be decreased by hydrological forcing to depths well below sea level when the sediment is exposed to the atmosphere.more »There is no analogous advective seawater-injecting mechanism upon resubmergence, only slower diffusive mechanisms. This hydrological ratchet is consistent with the existence of freshwater beneath the sea floor on continental shelves around the world, left over from the last glacial period. The salt content of the sediment column affects the relative proportions of the solid and fluid H2O-containing phases, but in the permafrost zone the salinity in the pore fluid brine is a function of temperature only, controlled by equilibrium with ice. Ice can tolerate a higher salinity in the pore fluid than methane hydrate can at low pressure and temperature, excluding methane hydrate from thermodynamic stability in the permafrost zone. The implication is that any methane hydrate existing today will be insulated from anthropogenic climate change by hundreds of meters of sediment, resulting in a response time of thousands of years. The strongest impact of the glacial–interglacial cycles on the atmospheric methane flux is due to bubbles dissolving in the ocean when sea level is high. When sea level is low and the sediment surface is exposed to the atmosphere, the atmospheric flux is sensitive to whether permafrost inhibits bubble migration in the model. If it does, the atmospheric flux is highest during the glaciating, sea level regression (soil-freezing) part of the cycle rather than during deglacial transgression (warming and thawing). The atmospheric flux response to a warming climate is small, relative to the rest of the methane sources to the atmosphere in the global budget, because of the ongoing flooding of the continental shelf. The increased methane flux due to ocean warming could be completely counteracted by a sea level rise of tens of meters on millennial timescales due to the loss of ice sheets, decreasing the efficiency of bubble transit through the water column. The model results give no indication of a mechanism by which methane emissions from the Siberian continental shelf could have a significant impact on the near-term evolution of Earth's climate, but on millennial timescales the release of carbon from hydrate and permafrost could contribute significantly to the fossil fuel carbon burden in the atmosphere–ocean–terrestrial carbon cycle.« less

  9. Methane emissions from beef cattle grazing on semi-natural upland and improved lowland grasslands.

    PubMed

    Richmond, A S; Wylie, A R G; Laidlaw, A S; Lively, F O

    2015-01-01

    In ruminants, methane (CH4) is a by-product of digestion and contributes significantly to the greenhouse gas emissions attributed to agriculture. Grazed grass is a relatively cheap and nutritious feed but herbage species and nutritional quality vary between pastures, with management, land type and season all potentially impacting on animal performance and CH4 production. The objective of this study was to evaluate performance and compare CH4 emissions from cattle of dairy and beef origin grazing two grassland ecosystems: lowland improved grassland (LG) and upland semi-natural grassland (UG). Forty-eight spring-born beef cattle (24 Holstein-Friesian steers, 14 Charolais crossbred steers and 10 Charolais crossbred heifers of 407 (s.d. 29), 469 (s.d. 36) and 422 (s.d. 50) kg BW, respectively), were distributed across two balanced groups that grazed the UG and LG sites from 1 June to 29 September at stocking rates (number of animals per hectare) of 1.4 and 6.7, respectively. Methane emissions and feed dry matter (DM) intake were estimated by the SF6 tracer and n-alkane techniques, respectively, and BW was recorded across three experimental periods that reflected the progression of the grazing season. Overall, cattle grazed on UG had significantly lower (P<0.001) mean daily DM intake (8.68 v. 9.55 kg/day), CH4 emissions (176 v. 202 g/day) and BW gain (BWG; 0.73 v. 1.08 kg/day) than the cattle grazed on LG but there was no difference (P>0.05) in CH4 emissions per unit of feed intake when expressed either on a DM basis (20.7 and 21.6 g CH4 per kg DM intake for UG and LG, respectively) or as a percentage of the gross energy intake (6.0% v. 6.5% for UG and LG, respectively). However, cattle grazing UG had significantly (P<0.001) greater mean daily CH4 emissions than those grazing LG when expressed relative to BWG (261 v. 197 g CH4/kg, respectively). The greater DM intake and BWG of cattle grazing LG than UG reflected the poorer nutritive value of the UG grassland. Although absolute rates of CH4 emissions (g/day) were lower from cattle grazing UG than LG, cattle grazing UG would be expected to take longer to reach an acceptable finishing weight, thereby potentially off-setting this apparent advantage. Methane emissions constitute an adverse environmental impact of grazing by cattle but the contribution of cattle to ecosystem management (i.e. promoting biodiversity) should also be considered when evaluating the usefulness of different breeds for grazing semi-natural or unimproved grassland. PMID:25167210

  10. Methane reforming and its potential effect on the efficiency and pollutant emissions of lean methane–air combustion

    Microsoft Academic Search

    J.-Y. Ren; W. Qin; F. N. Egolfopoulos; H. Mak; T. T. Tsotsis

    2001-01-01

    Results of ongoing studies of methane reforming for power generation applications are discussed. Design calculations are presented for a hybrid process (termed CRGT) involving chemical recuperation for power generation, and combining both reactive separation and combustion. Results are also presented from a parallel investigation, whose goal is to quantify the effect of the operational characteristics of the CRGT process on

  11. Mapping methane sources and emissions over California from direct airborne flux and VOC source tracer measurements

    NASA Astrophysics Data System (ADS)

    Guha, A.; Misztal, P. K.; Peischl, J.; Karl, T.; Jonsson, H. H.; Woods, R. K.; Ryerson, T. B.; Goldstein, A. H.

    2013-12-01

    Quantifying the contributions of methane (CH4) emissions from anthropogenic sources in the Central Valley of California is important for validation of the statewide greenhouse gas (GHG) inventory and subsequent AB32 law implementation. The state GHG inventory is largely based on activity data and emission factor based estimates. The 'bottom-up' emission factors for CH4 have large uncertainties and there is a lack of adequate 'top-down' measurements to characterize emission rates. Emissions from non-CO2 GHG sources display spatial heterogeneity and temporal variability, and are thus, often, poorly characterized. The Central Valley of California is an agricultural and industry intensive region with large concentration of dairies and livestock operations, active oil and gas fields and refining operations, as well as rice cultivation all of which are known CH4 sources. In order to gain a better perspective of the spatial distribution of major CH4 sources in California, airborne measurements were conducted aboard a Twin Otter aircraft for the CABERNET (California Airborne BVOC Emissions Research in Natural Ecosystems Transects) campaign, where the driving research goal was to understand the spatial distribution of biogenic VOC emissions. The campaign took place in June 2011 and encompassed over forty hours of low-altitude and mixed layer airborne CH4 and CO2 measurements alongside coincident VOC measurements. Transects during eight unique flights covered much of the Central Valley and its eastern edge, the Sacramento-San Joaquin delta and the coastal range. We report direct quantification of CH4 fluxes using real-time airborne Eddy Covariance measurements. CH4 and CO2 were measured at 1-Hz data rate using an instrument based on Cavity Ring Down Spectroscopy (CRDS) along with specific VOCs (like isoprene, methanol, acetone etc.) measured at 10-Hz using Proton Transfer Reaction Mass Spectrometer - Eddy Covariance (PTRMS-EC) flux system. Spatially resolved eddy covariance fluxes were obtained using the virtual disjunct eddy covariance method and from Wavelet Analysis along flight tracks flown in the mixed layer. Preliminary analysis of mixing ratio measurements indicate that high concentrations of CH4 occur consistently while flying above the Central Valley that are correlated to large enhancements of methanol which is an important dairy and livestock emissions tracer. The elevated CH4 mixing ratios along the eastern edge of the San Joaquin Valley highlight the contribution of topography and emissions transport to local ambient levels of CH4. Large enhancements of CH4, benzene and toluene are also observed while flying over the oil production facilities in western part of Kern county (state's top oil producing county, 10% of US production) suggesting the likelihood of fugitive emissions in the region. VOC tracer analysis is used to evaluate the source of high CH4 emissions encountered along the eastern edge of the central Sacramento valley where fugitive emissions from natural gas fields and cultivation of rice are likely sources. Plumes from biomass burning, landfills and refineries encountered during different flights are also investigated. Eddy covariance based CH4 flux estimates are derived for various sources and compared with ';bottom-up' inventory estimates to verify/validate the CA methane inventory for major sources.

  12. Ozone effects on Sphagnum mosses, carbon dioxide exchange and methane emission in boreal peatland microcosms.

    PubMed

    Niemi, Riikka; Martikainen, Pertti J; Silvola, Jouko; Holopainen, Toini

    2002-04-22

    Microcosms of a boreal peatland originating from an oligotrophic fen in Eastern Finland were fumigated under four ozone concentrations (0, 50, 100 and 150 ppb O3) in laboratory growth chambers during two separate experiments (autumn and summer) for 4 and 6 weeks, respectively. Ozone effects on Sphagnum mosses and the fluxes of carbon dioxide and methane were evaluated. In both experiments, the three Sphagnum species studied showed only a few significant responses to ozone. In the autumn experiment, membrane permeability of S. angustifolium, measured as conductivity and magnesium leakage, was significantly higher under ozone fumigation (P = 0.005 and < 0.001, respectively), and there was a distinct dose-dependence. S. magellanicum showed no clear responses, either for membrane leakage or pigment content. There were no substantial ozone responses in the gross photosynthesis or net CO2 exchange during the 6-week-long summer experiment, but dark ecosystem respiration was transiently increased by ozone concentration of 100 ppb after 14 days of exposure (P < 0.05). Fumigation with 100 ppb of ozone, however, more than doubled (P < 0.05) methane emission from the peatland monoliths. Our results suggest that increasing tropospheric ozone concentration may cause substantial changes in the carbon gas cycling of boreal peatlands, even though these changes are not closely associated with the changes in Sphagnum vegetation. PMID:12049387

  13. Development of a purpose built landfill system for the control of methane emissions from municipal solid waste

    E-print Network

    Columbia University

    (PBLF) has been proposed for the control of methane emissions from municipal solid waste (MSW Generation of municipal solid waste (MSW) increases with socio-economic development. In developing coun solid waste Sudhakar Yedla*, Jyoti K. Parikh Indira Gandhi Institute of Development Research, Vaidya

  14. The Effect of Dietary Alfalfa Silage to Corn Silage Ratio on Lactating Cow Performance and Methane Emission

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to determine the effect of varying alfalfa silage (AS) to corn silage (CS) ratios in a total mixed ration on performance of lactating cows and methane (CH4) emission. Sixteen multiparous Holstein cows (mean±SD; 77±35 days in milk and 640±84 kg body weight) housed in a...

  15. Bayesian Estimation of Fugitive Methane Point Source Emission Rates from a SingleDownwind High-Frequency Gas Sensor

    EPA Science Inventory

    Bayesian Estimation of Fugitive Methane Point Source Emission Rates from a Single Downwind High-Frequency Gas Sensor With the tremendous advances in onshore oil and gas exploration and production (E&P) capability comes the realization that new tools are needed to support env...

  16. Influences of man-made emissions and climate changes on tropospheric ozone, methane, and sulfate at 2030

    E-print Network

    Influences of man-made emissions and climate changes on tropospheric ozone, methane, and sulfate the International Institute for Applied Systems Analysis. The projections encompass a wide range of possible man, N., D. T. Shindell, D. M. Koch, M. Amann, J. Cofala, and D. G. Streets (2006), Influences of man

  17. METHANE EMISSION BY GOATS CONSUMING DIETS WITH DIFFERENT LEVELS OF CONDENSED TANNIN-CONTAINING LESPEDEZA AND SORGHUM-SUDANGRASS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Boer (7/8) x Spanish wethers (24; BW = 34.1 kg, SE = 1.02) were used to determine effects of dietary levels of a condensed tannin (CT)-containing forage Kobe lespedeza (Lespedeza striata; K) and sorghum-sudangrass (Sorghum bicolor; G) on methane emission. Treatments were K levels (DM basis) of 100,...

  18. Effects of an experimental drought and recovery on soil emissions of carbon dioxide, methane, nitrous oxide, and

    E-print Network

    Saleska, Scott

    and consumption. Keywords: Amazon Basin, Brazil, climate change, CH4, CO2, N2O, nitrogen, NO, soil carbon ReceivedEffects of an experimental drought and recovery on soil emissions of carbon dioxide, methane, Av. Centena´rio, 303 Piracicaba, SP, Brazil, zInstituto de Pesquisa Ambiental da Amazo^nia, Av. Rui

  19. Closed DHS system to prevent dissolved methane emissions as greenhouse gas in anaerobic wastewater treatment by its recovery and biological oxidation.

    PubMed

    Matsuura, N; Hatamoto, M; Sumino, H; Syutsubo, K; Yamaguchi, T; Ohashi, A

    2010-01-01

    Anaerobic wastewater treatment has been focused on its eco-friendly nature in terms of the improved energy conservation and reduction in carbon dioxide emissions. However, the anaerobic process discharges unrecovered methane as dissolved methane. In this study, to prevent the emission of dissolved methane from up-flow anaerobic sludge blanket (UASB) reactors used to treat sewage and to recover it as useful gas, we employed a two-stage down-flow hanging sponge (DHS) reactor as a post-treatment of the UASB reactor. The closed DHS reactor in the first stage was intended for the recovery of dissolved methane from the UASB reactor effluent; the reactor could successfully recover an average of 76.8% of the influent dissolved methane as useful gas (containing methane over 30%) with hydraulic retention time of 2 h. During the experimental period, it was possible to maintain the recovered methane concentrations greater than 30% by adjusting the air supply rate. The remaining dissolved methane after the first stage was treated by the next step. The second closed DHS reactor was operated for oxidation of the residual methane and polishing of the remaining organic carbons. The reactor had a high performance and the influent dissolved methane was mostly eliminated to approximately 0.01 mgCOD L(-1). The dissolved methane from the UASB reactor was completely eliminated--by more than 99%--by the post-treatment after the two-stage closed DHS system. PMID:20418639

  20. Comparison of methods to determine methane emissions from dairy cows in farm conditions.

    PubMed

    Huhtanen, P; Cabezas-Garcia, E H; Utsumi, S; Zimmerman, S

    2015-05-01

    Nutritional and animal-selection strategies to mitigate enteric methane (CH4) depend on accurate, cost-effective methods to determine emissions from a large number of animals. The objective of the present study was to compare 2 spot-sampling methods to determine CH4 emissions from dairy cows, using gas quantification equipment installed in concentrate feeders or automatic milking stalls. In the first method (sniffer method), CH4 and carbon dioxide (CO2) concentrations were measured in close proximity to the muzzle of the animal, and average CH4 concentrations or CH4/CO2 ratio was calculated. In the second method (flux method), measurement of CH4 and CO2 concentration was combined with an active airflow inside the feed troughs for capture of emitted gas and measurements of CH4 and CO2 fluxes. A muzzle sensor was used allowing data to be filtered when the muzzle was not near the sampling inlet. In a laboratory study, a model cow head was built that emitted CO2 at a constant rate. It was found that CO2 concentrations using the sniffer method decreased up to 39% when the distance of the muzzle from the sampling inlet increased to 30cm, but no muzzle-position effects were observed for the flux method. The methods were compared in 2 on-farm studies conducted using 32 (experiment 1) or 59 (experiment 2) cows in a switch-back design of 5 (experiment 1) or 4 (experiment 2) periods for replicated comparisons between methods. Between-cow coefficient of variation (CV) in CH4 was smaller for the flux than the sniffer method (experiment 1, CV=11.0 vs. 17.5%, and experiment 2, 17.6 vs. 28.0%). Repeatability of the measurements from both methods were high (0.72-0.88), but the relationship between the sniffer and flux methods was weak (R(2)=0.09 in both experiments). With the flux method CH4 was found to be correlated to dry matter intake or body weight, but this was not the case with the sniffer method. The CH4/CO2 ratio was more highly correlated between the flux and sniffer methods (R(2)=0.30), and CV was similar (6.4-8.8%). In experiment 2, cow muzzle position was highly repeatable (0.82) and influenced sniffer and flux method results when not filtered for muzzle position. It was concluded that the flux method provides more reliable estimates of CH4 emissions than the sniffer method. The sniffer method appears to be affected by variable air-mixing conditions created by geometry of feed trough, muzzle movement, and muzzle position. PMID:25771050

  1. Simulation, prediction, and genetic analyses of daily methane emissions in dairy cattle.

    PubMed

    Yin, T; Pinent, T; Brügemann, K; Simianer, H; König, S

    2015-08-01

    This study presents an approach combining phenotypes from novel traits, deterministic equations from cattle nutrition, and stochastic simulation techniques from animal breeding to generate test-day methane emissions (MEm) of dairy cows. Data included test-day production traits (milk yield, fat percentage, protein percentage, milk urea nitrogen), conformation traits (wither height, hip width, body condition score), female fertility traits (days open, calving interval, stillbirth), and health traits (clinical mastitis) from 961 first lactation Brown Swiss cows kept on 41 low-input farms in Switzerland. Test-day MEm were predicted based on the traits from the current data set and 2 deterministic prediction equations, resulting in the traits labeled MEm1 and MEm2. Stochastic simulations were used to assign individual concentrate intake in dependency of farm-type specifications (requirement when calculating MEm2). Genetic parameters for MEm1 and MEm2 were estimated using random regression models. Predicted MEm had moderate heritabilities over lactation and ranged from 0.15 to 0.37, with highest heritabilities around DIM 100. Genetic correlations between MEm1 and MEm2 ranged between 0.91 and 0.94. Antagonistic genetic correlations in the range from 0.70 to 0.92 were found for the associations between MEm2 and milk yield. Genetic correlations between MEm with days open and with calving interval increased from 0.10 at the beginning to 0.90 at the end of lactation. Genetic relationships between MEm2 and stillbirth were negative (0 to -0.24) from the beginning to the peak phase of lactation. Positive genetic relationships in the range from 0.02 to 0.49 were found between MEm2 with clinical mastitis. Interpretation of genetic (co)variance components should also consider the limitations when using data generated by prediction equations. Prediction functions only describe that part of MEm which is dependent on the factors and effects included in the function. With high probability, there are more important effects contributing to variations of MEm that are not explained or are independent from these functions. Furthermore, autocorrelations exist between indicator traits and predicted MEm. Nevertheless, this integrative approach, combining information from dairy cattle nutrition with dairy cattle genetics, generated novel traits which are difficult to record on a large scale. The simulated data basis for MEm was used to determine the size of a cow calibration group for genomic selection. A calibration group including 2,581 cows with MEm phenotypes was competitive with conventional breeding strategies. PMID:26026753

  2. Numerical modeling of methane venting from lake sediments

    E-print Network

    Scandella, Benjamin P. (Benjamin Paul)

    2010-01-01

    The dynamics of methane transport in lake sediments control the release of methane into the water column above, and the portion that reaches the atmosphere may contribute significantly to the greenhouse effect. The observed ...

  3. The use of direct-fed microbials for mitigation of ruminant methane emissions: a review.

    PubMed

    Jeyanathan, J; Martin, C; Morgavi, D P

    2014-02-01

    Concerns about the environmental effect and the economic burden of methane (CH4) emissions from ruminants are driving the search for ways to mitigate rumen methanogenesis. The use of direct-fed microbials (DFM) is one possible option to decrease CH4 emission from ruminants. Direct-fed microbials are already used in ruminants mainly to increase productivity and to improve health, and are readily accepted by producers and consumers alike. However, studies on the use of DFM as rumen CH4 mitigants are scarce. A few studies using Saccharomyces cerevisiae have shown a CH4-decreasing effect but, to date, there has not been a systematic exploration of DFM as modulators of rumen methanogenesis. In this review, we explored biochemical pathways competing with methanogenesis that, potentially, could be modulated by the use of DFM. Pathways involving the redirection of H2 away from methanogenesis and pathways producing less H2 during feed fermentation are the preferred options. Propionate formation is an example of the latter option that in addition to decrease CH4 formation increases the retention of energy from the diet. Homoacetogenesis is a pathway using H2 to produce acetate, however up to now no acetogen has been shown to efficiently compete with methanogens in the rumen. Nitrate and sulphate reduction are pathways competing with methanogenesis, but the availability of these substances in the rumen is limited. Although there were studies using nitrate and sulphate as chemical additives, use of DFM for improving these processes and decrease the accumulation of toxic metabolites needs to be explored more. There are some other pathways such as methanotrophy and capnophily or modes of action such as inhibition of methanogens that theoretically could be provided by DFM and affect methanogenesis. We conclude that DFM is a promising alternative for rumen methane mitigation that should be further explored for their practical usage. PMID:24274095

  4. Passive landfill gas emission - Influence of atmospheric pressure and implications for the operation of methane-oxidising biofilters.

    PubMed

    Gebert, Julia; Groengroeft, Alexander

    2006-01-01

    A passively vented landfill site in Northern Germany was monitored for gas emission dynamics through high resolution measurements of landfill gas pressure, flow rate and composition as well as atmospheric pressure and temperature. Landfill gas emission could be directly related to atmospheric pressure changes on all scales as induced by the autooscillation of air, diurnal variations and the passage of pressure highs and lows. Gas flux reversed every 20 h on average, with 50% of emission phases lasting only 10h or less. During gas emission phases, methane loads fed to a connected methane oxidising biofiltration unit varied between near zero and 247 g CH4 h(-1)m(-3) filter material. Emission dynamics not only influenced the amount of methane fed to the biofilter but also the establishment of gas composition profiles within the biofilter, thus being of high relevance for biofilter operation. The duration of the gas emission phase emerged as most significant variable for the distribution of landfill gas components within the biofilter. PMID:16387238

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

    NASA Astrophysics Data System (ADS)

    Marik, Thomas; Levin, Ingeborg

    1996-09-01

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

  6. Comparison of propane and methane performance and emissions in a turbocharged direct injection dual fuel engine

    SciTech Connect

    Gibson, C. M.; Polk, A. C.; Shoemaker, N. T.; Srinivasan, K. K.; Krishnan, S. R.

    2011-04-20

    With increasingly restrictive NO x and particulate matter emissions standards, the recent discovery of new natural gas reserves, and the possibility of producing propane efficiently from biomass sources, dual fueling strategies have become more attractive. This paper presents experimental results from dual fuel operation of a four-cylinder turbocharged direct injection (DI) diesel engine with propane or methane (a natural gas surrogate) as the primary fuel and diesel as the ignition source. Experiments were performed with the stock engine control unit at a constant speed of 1800 rpm, and a wide range of brake mean effective pressures (BMEPs) (2.7-11.6 bars) and percent energy substitutions (PESs) of C 3 H 8 and CH 4. Brake thermal efficiencies (BTEs) and emissions (NO x, smoke, total hydrocarbons (THCs), CO, and CO 2) were measured. Maximum PES levels of about 80-95% with CH 4 and 40-92% with C 3 H 8 were achieved. Maximum PES was limited by poor combustion efficiencies and engine misfire at low loads for both C 3 H 8 and CH 4, and the onset of knock above 9 bar BMEP for C 3 H 8. While dual fuel BTEs were lower than straight diesel BTEs at low loads, they approached diesel BTE values at high loads. For dual fuel operation, NO x and smoke reductions (from diesel values) were as high as 66-68% and 97%, respectively, but CO and THC emissions were significantly higher with increasing PES at all engine loads

  7. Methane and nitrous oxide emissions following anaerobic digestion of sludge in Japanese sewage treatment facilities.

    PubMed

    Oshita, Kazuyuki; Okumura, Takuya; Takaoka, Masaki; Fujimori, Takashi; Appels, Lise; Dewil, Raf

    2014-11-01

    Methane (CH4) and nitrous oxide (N2O) are potent greenhouse gases with global warming potentials (expressed in terms of CO2-equivalents) of 28 and 265, respectively. When emitted to the atmosphere, they significantly contribute to climate change. It was previously suggested that in wastewater treatment facilities that apply anaerobic sludge digestion, CH4 continues to be emitted from digested sludge after leaving the anaerobic digester. This paper studies the CH4 and N2O emissions from anaerobically digested sludge in the subsequent sludge treatment steps. Two full-scale treatment plants were monitored over a 1-year period. Average emissions of CH4 and N2O were 509±72 mg/m(3)-influent (wastewater) and 7.1±2.6 mg/m(3)-influent, respectively. These values accounted for 22.4±3.8% of the indirect reduction in CO2-emissions when electricity was generated using biogas. They are considered to be significant. PMID:25194911

  8. Comparison of methane emissions from wetlands measured from aircraft and towers

    NASA Astrophysics Data System (ADS)

    Conley, S. A.; Faloona, I. C.; Drexler, J. Z.; Anderson, F. E.; Baldocchi, D. D.; Sturtevant, C. S.; Verfaillie, J. G.; Knox, S. H.

    2013-12-01

    The ability to estimate surface fluxes from light, fixed-wing aircraft is investigated during two flights over Twitchell Island, a heavily managed peatland dominated by irrigated crops approximately 6 km x 3 km in the Sacramento Delta. Flux towers provide a continuous measurement at a single point, while airborne fluxes provide a snapshot of a large area at a given time. The ability to integrate the two methods would provide a means to estimate a continuous regional flux from tower measurements. The single engine airplane (Mooney TLS), provided by Scientific Aviation, was flown around the island while concurrent flux measurements (latent & sensible heat, CO2, CH4) were being made from 4 m towers at two locations on the surface. The flux estimate made with the airplane uses horizontal mean wind measured in real-time from the airplane and the methane mixing ratio measured onboard with a Picarro f2301 analyzer. During the flights there was clear periodicity in all scalars measured coincident with the flight time required to circle the island (~6 minutes), indicating a connection between the surface and the observed signal in the airplane. For methane, higher mixing ratios were observed on the downwind side of the island. An internal boundary layer was observed, which we believe resulted from the Montezuma Hills wind farms upwind of Twitchell Island. Scalars were well-mixed throughout the depth of that internal boundary layer (~500m), which is shown to be consistent with a theoretical estimate of the internal boundary layer given the transition from the wind farm to the island vegetation. Surface emissions were estimated using a mass-balance approach where each of the terms in the scalar budget equation are estimated using a least squares minimization of the data while the airplane was within 10 km of the center of the island and the altitude was below 300 meters. Surface emission of methane during the first flight was estimated at 36 × 13 nmol m-2 s-1. During the same time period, the flux measured from the ground stations within the rice fields on the island was estimated at 44 nmol m-2 s-1. The close agreement suggests that this technique has great potential for integrating flux tower measurements over larger areas.

  9. Nitrous oxide and methane emissions and nitrous oxide isotopic composition from waste incineration in Switzerland.

    PubMed

    Harris, Eliza; Zeyer, Kerstin; Kegel, Rainer; Müller, Beat; Emmenegger, Lukas; Mohn, Joachim

    2015-01-01

    Solid waste incineration accounts for a growing proportion of waste disposal in both developed and developing countries, therefore it is important to constrain emissions of greenhouse gases from these facilities. At five Swiss waste incineration facilities with grate firing, emission factors for N2O and CH4 were determined based on measurements of representative flue gas samples, which were collected in Tedlar bags over a one year period (September 2010-August 2011) and analysed with FTIR spectroscopy. All five plants burn a mixture of household and industrial waste, and two of the plants employ NOx removal through selective non-catalytic reduction (SNCR) while three plants use selective catalytic reduction (SCR) for NOx removal. N2O emissions from incineration plants with NOx removal through selective catalytic reduction were 4.3 ± 4.0g N2O tonne(-1) waste (wet) (hereafter abbreviated as t(-1)) (0.4 ± 0.4 g N2O GJ(-1)), ten times lower than from plants with selective non-catalytic reduction (51.5 ± 10.6g N2O t(-1); 4.5 ± 0.9g N2O GJ(-1)). These emission factors, which are much lower than the value of 120g N2O t(-1) (10.4g N2O GJ(-1)) used in the 2013 Swiss national greenhouse gas emission inventory, have been implemented in the most recent Swiss emission inventory. In addition, the isotopic composition of N2O emitted from the two plants with SNCR, which had considerable N2O emissions, was measured using quantum cascade laser spectroscopy. The isotopic site preference of N2O - the enrichment of (14)N(15)NO relative to (15)N(14)NO - was found to be 17.6 ± 0.8‰, with no significant difference between the two plants. Comparison to previous studies suggests SP of 17-19‰ may be characteristic for N2O produced from SNCR. Methane emissions were found to be insignificant, with a maximum emission factor of 2.5 ± 5.6g CH4 t(-1) (0.2 ± 0.5g CH4 GJ(-1)), which is expected due to high incinerator temperatures and efficient combustion. PMID:25458765

  10. Methane/CO{sub 2} sorption modeling for coalbed methane production and CO{sub 2} sequestration

    SciTech Connect

    Satya Harpalani; Basanta K. Prusty; Pratik Dutta [Southern Illinois University-Carbondale, Carbondale, IL (United States). Department of Mining and Mineral Resources Engineering

    2006-08-15

    A thorough study of the sorption behavior of coals to methane and carbon dioxide (CO{sub 2}) is critical for carbon sequestration in coal seams and enhanced coalbed methane recovery. This paper discusses the results of an ad/de-sorption study of methane and CO{sub 2}, in single gas environment, on a set of coal samples taken from the San Juan and Illinois Basins. The results indicate that, under similar temperature and pressure conditions, coals exhibit higher affinity to CO{sub 2} as compared to methane and that the preferential sorption ratio varies between 2:1 and 4:1. Furthermore, the experimental data were modeled using Langmuir, BET, and Dubinin-Polanyi equations. The accuracy of the models in quantifying coal-gas sorption was compared using an error analysis technique. The Dubinin-Radushkevich equation failed to model the coal-gas sorption behavior satisfactorily. For methane, Langmuir, BET, and Dubinin-Astakhov (D-A) equations all performed satisfactorily within comparable accuracy. However, for CO{sub 2}, the performance of the D-A equation was found to be significantly better than the other two. Overall, the D-A equation fitted the experimental sorption data the best, followed by the Langmuir and BET equations. Since the D-A equation is capable of deriving isotherms for any temperature using a single isotherm, thus providing added flexibility to model the temperature variation due to injection/depletion, this is the recommended model to use. 49 refs., 9 figs., 5 tabs.

  11. Magnitude and spatio-temporal variability of methane emissions from a eutrophic freshwater lake

    E-print Network

    Varadharajan, Charuleka, 1980-

    2009-01-01

    Methane is the second most important greenhouse gas after carbon dioxide, and it can significantly impact global climate change. Considerable amounts of methane can be released to the atmosphere from freshwater lakes, ...

  12. Creating rigorous pathways to monetize methane and nitrous oxide emission reductions at small scale rice farms in three states of semi-arid peninsular India

    NASA Astrophysics Data System (ADS)

    Kritee, K.; Tiwari, R.; Nair, D.; Adhya, T. K.; Rudek, J.

    2014-12-01

    As a part of a joint undertaking by Environmental Defense Fund and the Fair Climate Network, we have measured reduction in methane and nitrous oxide emissions due to alternate "low carbon" rice cultivation practices for three ago-ecological zones in India for the past two years. Sampling for nitrous oxide and methane emissions was done on approximately 60-80% of the total number of days in a growing season and was based on modified GRACEnet protocol. In recognition of farmer's economic interest and global food security demands, we also measured the effect of rice cultivation practices on farm economics and yields. Our data from three agro-ecological zones for 2012-2014 suggest that, for semi-arid peninsular India, low-carbon rice cultivation practices offer large range of emission reduction potential (0.5-5 metric tons CO2e/acre/year). The regions with sandy soils (Alfisols) had high rates of nitrous oxide emissions even under baseline "flooded" rice cultivation regimes and, thus, the Tier 1 IPCC emissions factors grossly underestimate both the amount of nitrous oxide emission from conventional rice cultivation practices, and the extent to which it can be reduced through better fertilizer management. Also, the IPCC factors overestimate the methane emission reduction possible due to water management for rice paddies. Therefore, it is crucial to customize N and water management to each region such that yields and net GHG emission reduction are maximized. These practices also have the potential to decrease water use by 10-30% and improve long term soil health by optimizing organic matter and increasing water-holding capacity. In addition, through GPS based demarcation of farmer plots, recording baseline practices through extensive surveys, documenting the parameters required to aggregate and prove implementation of low carbon rice farming practices, and to model the GHG emission reduction over large scales, we have put forward a path for better monetization of GHG emission reductions which will incentivize adoption of such practices. The payoff is a "triple win" including increased long-term food security (through enhanced yields), rural economic development (through improved farm profitability and adaptation), and lower environmental impacts (including lower GHG emissions).

  13. Spatial variability of ammonia and methane dairy emissions in the Central Valley, California with open-path mobile measurements during NASA DISCOVER-AQ 2013

    NASA Astrophysics Data System (ADS)

    Miller, D. J.; Sun, K.; Tao, L.; Zondlo, M. A.

    2013-12-01

    Atmospheric ammonia (NH3) is an important fine aerosol gas-phase precursor, with implications for regional air quality and climate change. Atmospheric methane (CH4) is an important greenhouse gas, with high uncertainties in the partitioning of various emission sources. Ammonia and methane agricultural emissions are highly variable in space and time and are highly uncertain, with a lack of widespread, in-situ measurements. We characterize the spatial variability of dairy livestock emissions by performing high resolution (5 Hz), in-situ, on-road mobile measurements of NH3, CH4, CO2, N2O, CO and H2O simultaneously with open-path sensors mounted on a passenger vehicle. This suite of multiple trace gas measurements allows for emission ratio calculations and separation of agricultural, petrochemical and combustion emission signatures. Mobile measurements were performed in the Tulare County dairy farm region (~120 dairy farms sampled downwind) in the Central Valley, California during NASA DISCOVER-AQ in winter 2013. We calculate the ?NH3/?CH4 and ?NH3/?CO2 emission ratios for each dairy farm sampled downwind. Emission plumes from individual farms are isolated based on known dairy farm locations and high resolution (1 km) surface wind field simulations. Background concentrations are subtracted to calculate the emission ratios. We find high spatial variability of ammonia and methane concentrations, with localized maximums of >1 ppmv NH3 downwind of individual dairy farms. The spatial extent of individual farm emission plumes are evaluated for NH3, CH4 and CO2, which all show well-defined enhancements localized to the dairy farms near the roadside (typical sampling proximity of ? 50 m). The NH3 concentrations are correlated with the distance from each dairy farm. The observed median concentration within 100 m downwind of the dairy farms is 63 ppbv NH3, with the 95th percentile at 417 ppbv NH3 and decreases to background conditions at ~500 m distance downwind. The diurnal variability of NH3 and CH4 background concentrations at the same locations sampled on multiple days is also evaluated; including a case study of a strong morning temperature inversion. Finally, we find the NH3/CH4 ratios at the sub-farm scale vary by at least a factor of two due to spatially heterogeneous farming practices. These results highlight the need for widespread, in-situ spatial and temporal sampling of agricultural regions to further characterize these heterogeneous emissions. Future analyses will inform emission inventories and regional air quality modeling efforts.

  14. 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.

  15. EPA'S NEW EMISSIONS MODELING FRAMEWORK

    EPA Science Inventory

    EPA's Office of Air Quality Planning and Standards is building a new Emissions Modeling Framework that will solve many of the long-standing difficulties of emissions modeling. The goals of the Framework are to (1) prevent bottlenecks and errors caused by emissions modeling activi...

  16. Methane emission rates from the Arctic coastal tundra at Barrow are log-normally distributed: Is this a tail that wags climate?

    NASA Astrophysics Data System (ADS)

    von Fischer, J. C.; Rhew, R.

    2008-12-01

    Over the past two growing seasons, we have conducted >200 point measurements of methane emission and ecosystem respiration rates on the Arctic coastal tundra within the Barrow Environmental Observatory. These measures reveal that methane emission rates are log-normally distributed, but ecosystem respiration rates are normally distributed. The contrast in frequency distributions indicates that methane and carbon dioxide emission rates respond in a qualitatively different way to their environmental drivers: while ecosystem respiration rates rise linearly with increasing temperature and soil moisture, methane emissions increase exponentially. Thus, the long positive tail in methane emission rates does generate positive feedback on climate change that is strongly non-linear. To further evaluate this response, we examined the spatial statistics of our dataset, and conducted additional measures of carbon flux from points on the landscape that typically had the highest rates of methane emission. The spatial analysis showed that neither ecosystem respiration nor methane emission rates have spatial co-correlation beyond that predicted by macroscopic properties of vegetation (e.g., species composition, plant height) and soil (e.g., permafrost depth, temperature, water content), suggesting that our findings can be used to scale up. Our analysis of high-emission points focused on wet and flooded areas where Carex aquatilis growth was greatest. Here, we found variation in methane emission rates to be correlated with Carex aboveground biomass and rates of gross primary production, but not ecosystem respiration. Given the sensitivity of Carex's phenotype to inundation, permafrost depth and soil temperature, we anticipate that the magnitude the climate-methane feedback in the Arctic coastal plain will depend strongly on how permafrost thaw alters the ecology of Carex aquatilis.

  17. Only low methane production and emission in degraded peat extraction sites after rewetting

    NASA Astrophysics Data System (ADS)

    Agethen, Svenja; Waldemer, Carolin; Knorr, Klaus-Holger

    2015-04-01

    In Central Europe rewetting of bogs after peat extraction is a wide spread technique to halt secondary aerobic decomposition and to reestablish plant species such as Sphagnum spp. and Eriophorum spp. that initialize accumulation of organic carbon in peat. Before extraction, such sites are often used for agriculture causing the aerobic degradation of peat and mobilization of phosphorus, ammonia, and dissolved organic matter (DOM). In nutrient poor ecosystems such as bogs, additional supply of P and N does not only trigger the establishment of uncharacteristic vegetation but also the formation of more labile plant litter and DOM that is readily degradable. Therefore, after rewetting and the development of anoxic conditions especially in initial stages high methane (CH4) emissions are reported for these systems compared to pristine bogs. Regarding the potential of methane production and emissions we investigated three common practices to prepare extraction fields for restoration (years since rewetting): i) Filling of drainage ditches, passive rewetting (1 site, Altendorfer Moor, Stade, NW-Germany, ca. 20 yr.), ii) Removal of upper 30 cm peat layer, removed peat used for construction of polder dikes (2 sites, Königsmoor, Leer, NW-Germany, 2 and 3 yr.), iii) Removal upper peat layer down to 50 cm grown peat, not extracted peat used as polder walls (2 sites, Benthullener Moor, Wardenburg, NW-Germany, 3 and 7 yr.). In each site two vegetated replicate mesocosms (diam. 30 cm, depth 40 cm) were sampled and placed in a greenhouse from May-October 2014 to maintain the water table at surface level. Pore water concentrations of ions, fermentation products and DOM, DOM electron acceptor capacity (EAC), soil gas concentrations of CO2, CH4 and H2, gas fluxes as well as element composition and organic matter quality of DOM and SOM were analyzed. We found out that practice i) with least efforts of nutrient removal in the peat produced the highest CH4 emissions (3.5 mmol m-2 d-1) although still within the range of northern pristine bogs. Also practice ii) showed still inputs of external nutrients and labile DOM, but CH4 production was not yet developed (0.23 and 0.07 mmol m-2 d-1). Practice iii) was most effective in nutrient removal, but only in the 7 yr. site little methane (in the 3 yr. site 0.025 vs. 0.41 mmol m-2 d-1in the 7 yr. site) was emitted. The emissions were well in accord with soil gas concentrations, maximum values for CH4 in practice i) were 115 ?mol L-1, 2-5 ?mol L-1 in practice ii) and 0.5 vs. 16 ?mol L-1 in practice iii). Only small concentrations of inorganic electron acceptors such as sulfate imply the importance of organic matter as electron acceptor. The results show that restored bogs on former strongly degraded extraction fields do not necessarily act as exceptionally high CH4 sources. Contrary to other findings in early stages of rewetting CH4 emissions can also be very low until other electron acceptors are exhausted and methanogens become effective competitors for substrates which happens in the order of years.

  18. Challenges in global modeling of wetland extent and wetland methane dynamics

    NASA Astrophysics Data System (ADS)

    Spahni, R.; Melton, J. R.; Wania, R.; Stocker, B. D.; Zürcher, S.; Joos, F.

    2012-12-01

    Global wetlands are known to be climate sensitive, and are the largest natural emitters of methane (CH4). Increased wetland CH4 emissions could act as a positive feedback to future warming. Modelling of global wetland extent and wetland CH4 dynamics remains a challenge. Here we present results from the Wetland and Wetland CH4 Inter-comparison of Models Project (WETCHIMP) that investigated our present ability to simulate large scale wetland characteristics (e.g. wetland type, water table, carbon cycling, gas transport, etc.) and corresponding CH4 emissions. Ten models participated, covering the spectrum from simple to relatively complex, including models tailored either for regional or global simulations. The WETCHIMP experiments showed that while models disagree in spatial and temporal patterns of simulated CH4 emissions and wetland areal extent, they all do agree on a strong positive response to increased carbon dioxide concentrations. WETCHIMP made clear that we currently lack observation data sets that are adequate to evaluate model CH4 soil-atmosphere fluxes at a spatial scale comparable to model grid cells. Thus there are substantial parameter and structural uncertainties in large-scale CH4 emission models. As an illustration of the implications of CH4 emissions on climate we show results of the LPX-Bern model, as one of the models participating in WETCHIMP. LPX-Bern is forced with observed 20th century climate and climate output from an ensemble of five comprehensive climate models for a low and a high emission scenario till 2100 AD. In the high emission scenario increased substrate availability for methanogenesis due to a strong stimulation of net primary productivity, and faster soil turnover leads to an amplification of CH4 emissions with the sharpest increase in peatlands (+180% compared to present). Combined with prescribed anthropogenic CH4 emissions, simulated atmospheric CH4 concentration reaches ~4500 ppbv by 2100 AD, about 800 ppbv more than in standard IPCC scenarios. This represents a significant contribution to radiative forcing of global climate.

  19. The impact of methane thermodynamics on seasonal convection and circulation in a model Titan atmosphere

    E-print Network

    Caballero, Rodrigo

    The impact of methane thermodynamics on seasonal convection and circulation in a model Titan 2009 Available online 12 May 2009 Keywords: Titan Atmospheres, Dynamics a b s t r a c t We identify, axisymmetric model atmosphere of Titan forced by gray radiation and moist (methane) con- vection. The large

  20. Methane emissions from natural gas compressor stations in the transmission and storage sector: measurements and comparisons with the EPA greenhouse gas reporting program protocol.

    PubMed

    Subramanian, R; Williams, Laurie L; Vaughn, Timothy L; Zimmerle, Daniel; Roscioli, Joseph R; Herndon, Scott C; Yacovitch, Tara I; Floerchinger, Cody; Tkacik, Daniel S; Mitchell, Austin L; Sullivan, Melissa R; Dallmann, Timothy R; Robinson, Allen L

    2015-03-01

    Equipment- and site-level methane emissions from 45 compressor stations in the transmission and storage (T&S) sector of the US natural gas system were measured, including 25 sites required to report under the EPA greenhouse gas reporting program (GHGRP). Direct measurements of fugitive and vented sources were combined with AP-42-based exhaust emission factors (for operating reciprocating engines and turbines) to produce a study onsite estimate. Site-level methane emissions were also concurrently measured with downwind-tracer-flux techniques. At most sites, these two independent estimates agreed within experimental uncertainty. Site-level methane emissions varied from 2-880 SCFM. Compressor vents, leaky isolation valves, reciprocating engine exhaust, and equipment leaks were major sources, and substantial emissions were observed at both operating and standby compressor stations. The site-level methane emission rates were highly skewed; the highest emitting 10% of sites (including two superemitters) contributed 50% of the aggregate methane emissions, while the lowest emitting 50% of sites contributed less than 10% of the aggregate emissions. Excluding the two superemitters, study-average methane emissions from compressor housings and noncompressor sources are comparable to or lower than the corresponding effective emission factors used in the EPA greenhouse gas inventory. If the two superemitters are included in the analysis, then the average emission factors based on this study could exceed the EPA greenhouse gas inventory emission factors, which highlights the potentially important contribution of superemitters to national emissions. However, quantification of their influence requires knowledge of the magnitude and frequency of superemitters across the entire T&S sector. Only 38% of the methane emissions measured by the comprehensive onsite measurements were reportable under the new EPA GHGRP because of a combination of inaccurate emission factors for leakers and exhaust methane, and various exclusions. The bias is even larger if one accounts for the superemitters, which were not captured by the onsite measurements. The magnitude of the bias varied from site to site by site type and operating state. Therefore, while the GHGRP is a valuable new source of emissions information, care must be taken when incorporating these data into emission inventories. The value of the GHGRP can be increased by requiring more direct measurements of emissions (as opposed to using counts and emission factors), eliminating exclusions such as rod-packing vents on pressurized reciprocating compressors in standby mode under Subpart-W, and using more appropriate emission factors for exhaust methane from reciprocating engines under Subpart-C. PMID:25668051

  1. Testing a biofilter cover design to mitigate dairy effluent pond methane emissions.

    PubMed

    Pratt, Chris; Deslippe, Julie; Tate, Kevin R

    2013-01-01

    Biofiltration, whereby CH(4) is oxidized by methanotrophic bacteria, is a potentially effective strategy for mitigating CH(4) emissions from anaerobic dairy effluent lagoons/ponds, which typically produce insufficient biogas for energy recovery. This study reports on the effectiveness of a biofilter cover design at oxidizing CH(4) produced by dairy effluent ponds. Three substrates, a volcanic pumice soil, a garden-waste compost, and a mixture of the two, were tested as media for the biofilters. All substrates were suspended as 5 cm covers overlying simulated dairy effluent ponds. Methane fluxes supplied to the filters were commensurate with emission rates from typical dairy effluent ponds. All substrates oxidized more than 95% of the CH(4) influx (13.9 g CH(4) m(-3) h(-1)) after two months and continued to display high oxidation rates for the remaining one month of the trial. The volcanic soil biofilters exhibited the highest oxidation rates (99% removal). When the influx CH(4) dose was doubled for a month, CH(4) removal rates remained >90% for all substrates (maximum = 98%, for the volcanic soil), suggesting that biofilters have a high capacity to respond to increases in CH(4) loads. Nitrous oxide emissions from the biofilters were negligible (maximum = 19.9 mg N(2)O m(-3) h(-1)) compared with CH(4) oxidation rates, particularly from the volcanic soil that had a much lower microbial-N (75 mg kg(-1)) content than the compost-based filters (>240 mg kg(-1)). The high and sustained CH(4) oxidation rates observed in this laboratory study indicate that a biofilter cover design is a potentially efficient method to mitigate CH(4) emissions from dairy effluent ponds. The design should now be tested under field conditions. PMID:23214965

  2. Short communication: measurements of methane emissions from feed samples in filter bags or dispersed in the medium in an in vitro gas production system.

    PubMed

    Ramin, M; Krizsan, S J; Jan?ík, F; Huhtanen, P

    2013-07-01

    The objective of this study was to compare methane (CH4) emissions from different feeds when incubated within filter bags for in vitro analysis or directly dispersed in the medium in an automated gas in vitro system. Four different concentrates and 4 forages were used in this study. Two lactating Swedish Red cows were used for the collection of rumen fluid. Feed samples were milled to pass a 1.0-mm screen. Aliquots (0.5 g) of samples were weighed directly in the bottles or within the F 0285 filter bags that were placed in the bottles. Gas samples were taken during 24 and 48 h of incubation, and CH4 concentration was determined. The data were analyzed using a general linear model. Feeds differed significantly in CH4 emission both at 24 and at 48 h of incubation. The interaction between feed and method on methane emission in vitro was significant, indicating that the ranking of feeds was not consistent between the methods. Generally, greater amounts of CH4 were emitted from samples directly dispersed in the medium compared with those incubated within the filter bags, which could be a result of lower microbial activity within the filter bags. The ratio of CH4 to total gas was greater when the feeds were incubated within bags compared with samples directly dispersed in the medium. Incubating samples in filter bags during 48 h of incubation cannot be recommended for determination of CH4 emission of feeds in vitro. PMID:23628246

  3. CarbonTracker-CH4: an assimilation system for estimating emissions of atmospheric methane

    NASA Astrophysics Data System (ADS)

    Bruhwiler, L. M.; Dlugokencky, E.; Masarie, K.; Ishizawa, M.; Andrews, A.; Miller, J.; Sweeney, C.; Tans, P.; Worthy, D.

    2014-01-01

    We describe an assimilation system for atmospheric methane (CH4), CarbonTracker-CH4, and demonstrate the diagnostic value of global or zonally averaged CH4 abundances for evaluating the results. We show that CarbonTracker-CH4 is able to simulate the observed zonal average mole fractions and capture inter-annual variability in emissions quite well at high northern latitudes (53-90° N). CarbonTracker-CH4 estimates of total fluxes at high northern latitudes are about 81 Tg CH4 yr-1, about 12 Tg CH4 yr-1 (13%) lower than prior estimates, a result that is consistent with other atmospheric inversions. Emissions from European wetlands are decreased by 30%, a result consistent with previous; however, emissions from wetlands in Boreal Eurasia are increased relative to the prior estimate. Although CarbonTracker-CH4 does not estimate increases in emissions from high northern latitudes for 2000 through 2010, significant inter-annual variability in high northern latitude fluxes is recovered. During the exceptionally warm Arctic summer of 2007, estimated emissions were greater than the decadal average by 4.4 Tg CH4 yr-1. In 2008, temperatures returned to more normal values over Arctic North America while they stayed above normal over Arctic Eurasia. CarbonTracker-CH4 estimates were 2.4 Tg CH4 yr-1 higher than the decadal average, and the anomalous emissions occurred over Arctic Eurasia, suggesting that the data allow discrimination between these two source regions. Also, the emission estimates respond to climate variability without having the system constrained by climate parameters. CarbonTracker-CH4 estimates for temperate latitudes are only slightly increased over prior estimates, but about 10 Tg CH4 yr-1 is redistributed from Asia to North America. We used time invariant prior flux estimates, so for the period from 2000 to 2006, when the growth rate of global atmospheric CH4 was very small, the assimilation does not produce increases in natural or anthropogenic emissions in contrast to bottom-up emission datasets. After 2006, when atmospheric CH4 began its recent increases, CarbonTracker-CH4 allocates some of the increases to anthropogenic emissions at temperate latitudes, and some to tropical wetland emissions. For temperate North America the prior flux increases by about 4 Tg CH4 yr-1 during winter when biogenic emissions are small. Examination of the residuals at some North American observation sites suggests that increased gas and oil exploration may play a role since sites near fossil fuel production are particularly hard for the inversion to fit. The tropics are not currently well resolved by CarbonTracker-CH4 due to sparse observational coverage and a short assimilation window. However, there is a small uncertainty reduction and posterior emissions are about 18% higher than prior estimates. Most of this increase is allocated to tropical South America rather than being distributed among the global tropics.

  4. Methane emission rates from the Arctic coastal tundra at Barrow: temporal and spatial variability and response to an experimental carbon addition

    Microsoft Academic Search

    J. C. von Fischer; G. Ames; R. Rhew; W. C. Oechel

    2007-01-01

    We characterized spatial and temporal variability in methane emission rates from the Arctic coastal tundra within the Barrow Environmental Observatory during July 2007. Our chamber-based survey complements ongoing tower-based measurements on the site, and provides baseline data for future upscaling efforts. By taking a Los Gatos methane analyzer into the field, we were able to: 1) conduct an exceptionally large

  5. LANDFILL GAS EMISSIONS MODEL (LANDGEM) VERSION 3.02 USER'S GUIDE

    EPA Science Inventory

    The Landfill Gas Emissions Model (LandGEM) is an automated estimation tool with a Microsoft Excel interface that can be used to estimate emission rates for total landfill gas, methane, carbon dioxide, nonmethane organic compounds, and individual air pollutants from municipal soli...

  6. Photochemistry of Methane in Model Atmospheres of Jupiter and Titan

    NASA Technical Reports Server (NTRS)

    Bersohn, Richard

    2000-01-01

    The two central findings were 1) hydrogen atoms and hydrogen molecules photodissociated from methane are relatively richer in H than in D in other words deuterium atoms have a greater probability of remaining attached to the carbon atom. Titan, a moon of Saturn has an atmosphere which is largely nitrogen but also contains about 3% methane as well as smaller amounts of C2 and C3 hydrocarbons. If all these hydrocarbons are of biological origin, the isotopic scrambling occurring in living organisms would result in equal D atom abundances. On the other hand, if the higher hydrocarbons are derived from methane by photodissociation of methane, they should be richer in D than methane. Precise values for the enrichment were derived from our photochemical data. 2) When methane is dissociated by vuv light, methylene is produced in a singlet state. This explains why the higher hydrocarbons are sparse on Jupiter but relatively rich on Titan.

  7. EMPIRICAL MODEL OF VEHICLE EMISSIONS

    EPA Science Inventory

    An empirical model that characterizes the relationship between equilibrium vehicle emission distributions and malfunction, repair, and replacement rates by splitting vehicles into two emission categories has been developed. ross emitters and clean vehicles are defined by the magn...

  8. Methane emission rates from the Arctic coastal tundra at Barrow: temporal and spatial variability and response to an experimental carbon addition

    NASA Astrophysics Data System (ADS)

    von Fischer, J. C.; Ames, G.; Rhew, R.; Oechel, W. C.

    2007-12-01

    We characterized spatial and temporal variability in methane emission rates from the Arctic coastal tundra within the Barrow Environmental Observatory during July 2007. Our chamber-based survey complements ongoing tower-based measurements on the site, and provides baseline data for future upscaling efforts. By taking a Los Gatos methane analyzer into the field, we were able to: 1) conduct an exceptionally large number of chamber measures over a short period of time, 2) gather high precision temporal data in chamber methane concentrations, and 3) follow-up on unusual field observations. Our survey revealed that methane emission rates were most strongly correlated with soil moisture levels, such that dry sites were only weakly emitting while sites with standing water emitted an average 60 mg CH4-C m-2 d-1. On these wettest sites, methane emission rates were most strongly correlated with Carex aquatilis density, such that changes in density from 0 to 20% coverage led to increase in emission rates from 50 to 75 mg CH4-C m-2 d-1. To evaluate the importance of carbon limitation for methane emission, we conducted an acetate addition experiment to inundated (water table > soil surface) and wet (water table = soil surface) soils. Surprisingly, injections of acetate, equivalent to 1 day of methane flux, did not lead to any significant changes in methane emission rates over 72 hours, indicating a lack of C limitation. We found that sites differed little in day-to-day methane emission rates over the course of two weeks, with average 16% CV. However, one point on dry tundra emitted >1000 mg CH4-C m-2 d-1, with 2 orders of magnitude variation over 10 days, and 3 orders of magnitude range of flux rates within a single square meter.

  9. Modeling the Effects of Matrix Shrinkage and Differential Swelling on Coalbed Methane Recovery and Carbon Sequestration

    Microsoft Academic Search

    L. J. Pekot; S. R. Reeves

    Matrix shri nkage and swelling can cause profound changes in porosity and permeability of coalbed methane reservoirs during depletion or when under injection processes, with associated implications for primary or enhanced methane recovery. Two models that are used to describe these effects are discussed. The first was developed by Advanced Resources International (ARI) and published in 1990 by Sawyer, et

  10. Seasonal Variation of Methane Emissions in California's Urban and Rural Regions Using Multi-site Observations

    NASA Astrophysics Data System (ADS)

    Jeong, S.; Hsu, Y.; Andrews, A. E.; Bianco, L.; Newman, S.; Cui, X.; Bagley, J.; Graven, H. D.; Salameh, P.; Sloop, C.; LaFranchi, B.; Michelsen, H. A.; Bambha, R.; Weiss, R. F.; Keeling, R. F.; Fischer, M. L.

    2014-12-01

    California's commitment (Assembly Bill 32) to reduce total greenhouse gas (GHG) emissions to 1990 levels by 2020 requires quantification of current GHG emissions. We present seasonal variation of California's total CH4 emissions for summer 2013 - spring 2014, using data from a dozen sites covering urban and rural areas of California that include South Coast Air Basin (SoCAB), Central Valley, and San Francisco Bay Area. We apply a Bayesian inverse model to estimate CH4 emissions from discrete regions of California and source sectors by combining atmospheric measurements, upstream background, updated high-resolution prior emission maps developed for California, and predicted atmospheric transport from WRF-STILT. We quantify site-specific model-measurement uncertainties due to transport using simulated and observed meteorology, background estimated from oceanic and aircraft observations, and the prior emissions. In particular, we evaluate predicted transport variables in WRF with networks of surface and upper air observations. Preliminary inversion results during summer of 2013 suggest that state total CH4 emissions are 1.2 - 1.7 times higher than the current CARB inventory. Here, we extend and improve upon earlier analyses to provide a full seasonal cycle of CH4 emissions across all major urban and rural regions in California.

  11. Analyzing Source Apportioned Methane in Northern California During DISCOVER-AQ-CA Using Airborne Measurements and Model Simulations

    NASA Technical Reports Server (NTRS)

    Johnson, Matthew S.

    2014-01-01

    This study analyzes source apportioned methane (CH4) emissions and atmospheric concentrations in northern California during the Discover-AQ-CA field campaign using airborne measurement data and model simulations. Source apportioned CH4 emissions from the Emissions Database for Global Atmospheric Research (EDGAR) version 4.2 were applied in the 3-D chemical transport model GEOS-Chem and analyzed using airborne measurements taken as part of the Alpha Jet Atmospheric eXperiment over the San Francisco Bay Area (SFBA) and northern San Joaquin Valley (SJV). During the time period of the Discover-AQ-CA field campaign EDGAR inventory CH4 emissions were 5.30 Gg/day (Gg 1.0 109 grams) (equating to 1.9 103 Gg/yr) for all of California. According to EDGAR, the SFBA and northern SJV region contributes 30 of total emissions from California. Source apportionment analysis during this study shows that CH4 concentrations over this area of northern California are largely influenced by global emissions from wetlands and local/global emissions from gas and oil production and distribution, waste treatment processes, and livestock management. Model simulations, using EDGAR emissions, suggest that the model under-estimates CH4 concentrations in northern California (average normalized mean bias (NMB) -5 and linear regression slope 0.25). The largest negative biases in the model were calculated on days when hot spots of local emission sources were measured and atmospheric CH4 concentrations reached values 3.0 parts per million (model NMB -10). Sensitivity emission studies conducted during this research suggest that local emissions of CH4 from livestock management processes are likely the primary source of the negative model bias. These results indicate that a variety, and larger quantity, of measurement data needs to be obtained and additional research is necessary to better quantify source apportioned CH4 emissions in California and further the understanding of the physical processes controlling them.

  12. Methane emissions from wetlands in the Midboreal region of northern Ontario, Canada

    SciTech Connect

    Bubier, J.L.; Moore, T.R. (McGill Univ., Quebec (Canada)); Roulet, N.T. (York Univ., Ontario (Canada))

    1993-12-01

    Methane (CH[sub 4]) fluxes were measured by a static chamber technique from May to October 1991 at 19 wetland sites near Cochrane, northern Ontario, representative of the Clay Belt Midboreal region of central Canada. Seasonal average fluxes of CH[sub 4] from the peatlands ranged from 0.4 to 67.5 mg[center dot]m[sup [minus]2][center dot]d[sup [minus]1] (0.06-10.1 g[center dot]m[sup [minus]2][center dot]yr[sup [minus]1]). Beaver ponds showed the highest fluxes of CH[sub 4], from both the open water section (seasonal average 290 mg[center dot]m[sup [minus]2][center dot]d[sup [minus]1], 44 g[center dot]m[sup [minus]2][center dot]yr[sup [minus]1]) and the adjacent marsh areas where the water table rose close to or above the soil surface (91-350 mg[center dot]m[sup [minus]2][center dot]d[sup [minus]1], 13-53 g[center dot]m[sup [minus]2][center dot]yr[sup [minus]1]). Seasonal mean water table position, particularly at the microtopographic scale of hummock and hollow, explained most of the variability in CH[sub 4] emission among wetlands (r[sup 2] = 0.74). Trophic status, such as pore-water Ca, Mg, and pH had little correlation with CH[sub 4] emissions. Broad-scale peatland classifications that do not account for hydrological differences at the microtopographic level are inadequate for predicting CH[sub 4] flux in boreal wetlands, particularly in forested ecosystems where conifer swamps are diverse and comprise the major peatland class. Based on areal estimates of the different wetland types in the Clay Belt, the authors estimate an annual CH[sub 4] flux of 3.4 g[center dot]m[sup [minus]2][center dot]yr[sup [minus]1], generally lower than that used in extrapolations to continental- or global-scale methane budgets. 68 refs., 5 figs., 6 tabs.

  13. Comparison of the HadGEM2 climate-chemistry model against in situ and SCIAMACHY atmospheric methane data

    NASA Astrophysics Data System (ADS)

    Hayman, G. D.; O'Connor, F. M.; Dalvi, M.; Clark, D. B.; Gedney, N.; Huntingford, C.; Prigent, C.; Buchwitz, M.; Schneising, O.; Burrows, J. P.; Wilson, C.; Richards, N.; Chipperfield, M.

    2014-12-01

    Wetlands are a major emission source of methane (CH4) globally. In this study, we evaluate wetland emission estimates derived using the UK community land surface model (JULES, the Joint UK Land Earth Simulator) against atmospheric observations of methane, including, for the first time, total methane columns derived from the SCIAMACHY instrument on board the ENVISAT satellite. Two JULES wetland emission estimates are investigated: (a) from an offline run driven with Climatic Research Unit-National Centers for Environmental Prediction (CRU-NCEP) meteorological data and (b) from the same offline run in which the modelled wetland fractions are replaced with those derived from the Global Inundation Extent from Multi-Satellites (GIEMS) remote sensing product. The mean annual emission assumed for each inventory (181 Tg CH4 per annum over the period 1999-2007) is in line with other recently published estimates. There are regional differences as the unconstrained JULES inventory gives significantly higher emissions in the Amazon (by ~36 Tg CH4 yr-1) and lower emissions in other regions (by up to 10 Tg CH4 yr-1) compared to the JULES estimates constrained with the GIEMS product. Using the UK Hadley Centre's Earth System model with atmospheric chemistry (HadGEM2), we evaluate these JULES wetland emissions against atmospheric observations of methane. We obtain improved agreement with the surface concentration measurements, especially at high northern latitudes, compared to previous HadGEM2 runs using the wetland emission data set of Fung et al. (1991). Although the modelled monthly atmospheric methane columns reproduce the large-scale patterns in the SCIAMACHY observations, they are biased low by 50 part per billion by volume (ppb). Replacing the HadGEM2 modelled concentrations above 300 hPa with HALOE-ACE assimilated TOMCAT output results in a significantly better agreement with the SCIAMACHY observations. The use of the GIEMS product to constrain the JULES-derived wetland fraction improves the representation of the wetland emissions in JULES and gives a good description of the seasonality observed at surface sites influenced by wetlands, especially at high latitudes. We find that the annual cycles observed in the SCIAMACHY measurements and at many of the surface sites influenced by non-wetland sources cannot be reproduced in these HadGEM2 runs. This suggests that the emissions over certain regions (e.g. India and China) are possibly too high and/or the monthly emission patterns for specific sectors are incorrect. The comparisons presented in this paper show that the performance of the JULES wetland scheme is comparable to that of other process-based land surface models. We identify areas for improvement in this and the atmospheric chemistry components of the HadGEM Earth System model. The Earth Observation data sets used here will be of continued value in future evaluations of JULES and the HadGEM family of models.

  14. Comparison of the HadGEM2 climate-chemistry model against in-situ and SCIAMACHY atmospheric methane data

    NASA Astrophysics Data System (ADS)

    Hayman, G. D.; O'Connor, F. M.; Dalvi, M.; Clark, D. B.; Gedney, N.; Huntingford, C.; Prigent, C.; Buchwitz, M.; Schneising, O.; Burrows, J. P.; Wilson, C.; Richards, N.; Chipperfield, M.

    2014-05-01

    Wetlands are a major emission source of methane (CH4) globally. In this study, we have evaluated wetland emission estimates derived using the UK community land surface model (JULES, the Joint UK Land Earth Simulator) against atmospheric observations of methane, including, for the first time, total methane columns derived from the SCIAMACHY instrument on board the ENVISAT satellite. Two JULES wetland emission estimates were investigated: (a) from an offline run driven with CRU-NCEP meteorological data and (b) from the same offline run in which the modelled wetland fractions were replaced with those derived from the Global Inundation Extent from Multi-Satellites (GIEMS) remote sensing product. The mean annual emission assumed for each inventory (181 Tg CH4 per annum over the period 1999-2007) is in line with other recently-published estimates. There are regional differences as the unconstrained JULES inventory gave significantly higher emissions in the Amazon and lower emissions in other regions compared to the JULES estimates constrained with the GIEMS product. Using the UK Hadley Centre's Earth System model with atmospheric chemistry (HadGEM2), we have evaluated these JULES wetland emissions against atmospheric observations of methane. We obtained improved agreement with the surface concentration measurements, especially at northern high latitudes, compared to previous HadGEM2 runs using the wetland emission dataset of Fung (1991). Although the modelled monthly atmospheric methane columns reproduced the large-scale patterns in the SCIAMACHY observations, they were biased low by 50 part per billion by volume (ppb). Replacing the HadGEM2 modelled concentrations above 300 hPa with HALOE-ACE assimilated TOMCAT output resulted in a significantly better agreement with the SCIAMACHY observations. The use of the GIEMS product to constrain JULES-derived wetland fraction improved the description of the wetland emissions in JULES and gave a good description of the seasonality observed at surface sites influenced by wetlands, especially at high latitudes. We found that the annual cycles observed in the SCIAMACHY measurements and at many of the surface sites influenced by non-wetland sources could not be reproduced in these HadGEM2 runs. This suggests that the emissions over certain regions (e.g., India and China) are possibly too high and/or the monthly emission patterns for specific sectors are incorrect. The comparisons presented in this paper have shown that the performance of the JULES wetland scheme is comparable to that of other process-based land surface models. We have identified areas for improvement in this and the atmospheric chemistry components of the HadGEM Earth System model. The Earth Observation datasets used here will be of continued value in future evaluations of JULES and the HadGEM family of models.

  15. The use of atmospheric measurements to constrain Arctic methane emissions and to locate and identify major sources.

    NASA Astrophysics Data System (ADS)

    Nisbet, E. G.; Fisher, R. E.; Lowry, D.; Lanoisellé, M.

    2011-12-01

    Arctic and boreal methane emissions come from various sources, most of which will respond strongly and rapidly both to year-on-year meteorological variations and to sustained climate warming. These sources, which may have played a major role both in modern methane excursions and in past global climatic change, include Arctic submarine hydrates, thermokarsts, Arctic and boreal wetlands, and tundra and forest fires, including peat fires. In addition, there are major industrial sources, with major emissions from some of the world's largest gasfields, and Arctic coalfields. Atmospheric measurements can be used to constrain sources. Mixing ratio measurements, placed in a global context, can be used to identify anomalous Arctic regional changes, while back-trajectory analysis can locate major source regions. Field campaigns in key emission areas, using Keeling plot techniques, show distinctive isotopic differences between sources. For example, Finnish wetlands show relatively constant ?13C(CH4) -68.8 ± 0.8%, while methane from thermokarst lakes in E. Siberia ranges widely, from -83% to -58% (Walter et al. Nature 443, 71, 2006). Fire-sourced methane from boreal forests can have ?13CCH4 around -28 %. Hydrate emissions are variable, according to primary sources of the gas, and the impact of methanotrophy in escaping gas plumes: cores from west of Spitsbergen give ?13CCH4 source signatures of -55 ± 2 % and -46 ± 3 %. Methane from the W. Siberian gasfields varies isotopically. Leaked gas in average ambient air sampled in the production region around Korotchaevo tower in the Ob River region has been measured by our group at around -50%. When isotopic information is coupled with back-trajectory analysis of air masses, regional bulk source inputs can be assessed, and specific sources can be located and characterized (e.g. wetland, fires, or marine emissions). Isotopic analysis of methane in air samples collected in 2008-2010 from Spitsbergen showed that in summer the bulk high Arctic methane increment over N. Atlantic background had a ?13C(CH4) signature of -68%. This indicates a dominantly biogenic summer source, probably dominantly from wetlands, with only small hydrate, gas leaks, or Arctic fire inputs. Plumes of emissions to the water column from the seabed on the Spitsbergen continental slope are demonstrably occurring but the mixing ratio of methane and ?13CCH4 signature in air collected above the plumes indicates that little hydrate-sourced methane currently reaches the atmosphere in this region of the low-longitude Arctic. Spring 2009 samples, when the wetland was frozen, had a more enriched signature, ?13C(CH4) -53%. Trajectory analyses implied a large winter contribution from large onshore gas fields in NW Siberia. Given the likelihood of rapid change in sources (e.g. major tundra fires; warming wetland and permafrost), ongoing isotopic monitoring is needed.

  16. Methane emission to the atmosphere through emergent cattail (Typha latifolia L.) plants

    NASA Astrophysics Data System (ADS)

    Yavitt, J. B.; Knapp, A. K.

    1995-11-01

    Methane (CH4) produced microbially in sediments of marshes is emitted to the atmosphere primarily by flowing through and out of emergent aquatic plants. The magnitude of such emission rates and factors controlling those rates are not well understood. We evaluated CH4 emission from the widely distributed aquatic emergent plant cattail (Typha latifolia L.) in several wetlands in the United States using a field gas-exchange system that concurrently estimated stomatal aperture (i.e., conductance) on the surface of leaves and net photosynthesis. We compared gas exchange among plants of different age and from sites with different soil and atmospheric conditions. The mean rate of CH4 emission was 0.22µ mol m-2[leaf] s-1, which is 940mg CH4 m-2 d-1 on a ground-area basis, with individual rates ranging from 0.01 to 1.49µ mol m-2[leaf] s-1. For individual plants, we found emission rates were (i) highest for the part of the leaf about 1.0 m above the waterline and lower near the leaf tip and close to the leaf base, and (ii) highest near midday and lower soon after sunrise and towards sunset. We also found the ease that CH4 moves in a sediment-plant-atmosphere continuum seems to increase with plant age. We propose that a series of factors influences CH4 emission from Typha latifolia to the atmosphere; stomatal conductance and plant age are as important as the amount of microbially produced CH4 in the wetland sediment.

  17. Analyzing source apportioned methane in northern California during Discover-AQ-CA using airborne measurements and model simulations

    NASA Astrophysics Data System (ADS)

    Johnson, Matthew S.; Yates, Emma L.; Iraci, Laura T.; Loewenstein, Max; Tadi?, Jovan M.; Wecht, Kevin J.; Jeong, Seongeun; Fischer, Marc L.

    2014-12-01

    This study analyzes source apportioned methane (CH4) emissions and atmospheric mixing ratios in northern California during the Discover-AQ-CA field campaign using airborne measurement data and model simulations. Source apportioned CH4 emissions from the Emissions Database for Global Atmospheric Research (EDGAR) version 4.2 were applied in the 3-D chemical transport model GEOS-Chem and analyzed using airborne measurements taken as part of the Alpha Jet Atmospheric eXperiment over the San Francisco Bay Area (SFBA) and northern San Joaquin Valley (SJV). During the time period of the Discover-AQ-CA field campaign EDGAR inventory CH4 emissions were ?5.30 Gg day-1 (Gg = 1.0 × 109 g) (equating to ?1.90 × 103 Gg yr-1) for all of California. According to EDGAR, the SFBA and northern SJV region contributes ?30% of total CH4 emissions from California. Source apportionment analysis during this study shows that CH4 mixing ratios over this area of northern California are largely influenced by global emissions from wetlands and local/global emissions from gas and oil production and distribution, waste treatment processes, and livestock management. Model simulations, using EDGAR emissions, suggest that the model under-estimates CH4 mixing ratios in northern California (average normalized mean bias (NMB) = -5.2% and linear regression slope = 0.20). The largest negative biases in the model were calculated on days when large amounts of CH4 were measured over local emission sources and atmospheric CH4 mixing ratios reached values >2.5 parts per million. Sensitivity emission studies conducted during this research suggest that local emissions of CH4 from livestock management processes are likely the primary source of the negative model bias. These results indicate that a variety, and larger quantity, of measurement data needs to be obtained and additional research is necessary to better quantify source apportioned CH4 emissions in California.

  18. Molecular decomposition of solid methane films and emission of molecular fragments under MeV ion bombardment

    Microsoft Academic Search

    W. L. Brown; L. J. Lanzerotti; J. E. Bower; K. J. Marcantonio

    1987-01-01

    Electronic and collisional excitation of thin films of condensed molecular gases (H2O, O2, N2, CO2, NH3, SO2, CH4, etc.) by MeV and keV ions results in sputtering of the primary molecules. In addition, new solid molecular species, formed from fragments of the original molecules, are also emitted. Solid methane is a particularly interesting case. Hydrogen is a principal emission product

  19. Enteric methane emissions and lactational performance of Holstein cows fed different concentrations of coconut oil.

    PubMed

    Hollmann, M; Powers, W J; Fogiel, A C; Liesman, J S; Bello, N M; Beede, D K

    2012-05-01

    To determine if dietary medium-chain fatty acids (FA; C(8) to C(14)) may mitigate enteric methane emissions, 24 cows were blocked by body size (n=2) and randomly assigned to 1 sequence of dietary treatments. Diets were fed for 35 d each in 2 consecutive periods. Diets differed in concentrations of coconut oil (CNO; ~75% medium-chain FA): 0.0 (control) or 1.3, 2.7, or 3.3% CNO, dry matter basis. The control diet contained 50% forage (74% from corn silage), 16.5% crude protein (60% from rumen-degradable protein), 34% neutral detergent fiber (NDF; 71% from forage), and 28% starch, dry matter basis. Data and sample collections were from d 29 to 35 in environmentally controlled rooms to measure methane (CH(4)) production. Methane emitted was computed from the difference in concentrations of inlet and outlet air and flux as measured 8 times per day. Control cows emitted 464 g of CH(4)/d, consumed 22.9 kg of DM/d, and produced 34.8 kg of solids-corrected milk/d and 1.3 kg of milk fat/d. Treatment with 1.3, 2.7, or 3.3% dietary CNO reduced CH(4) (449, 291, and 253 g/d, respectively), but concomitantly depressed dry matter intake (21.4, 17.9, and 16.2 kg/d, respectively), solids-corrected milk yield (36.3, 28.4, and 26.8 kg/d, respectively), and milk fat yield (1.4, 0.9, and 0.9 kg/d, respectively). The amount of NDF digested in the total tract decreased with increased dietary CNO concentrations; thus, CH(4) emitted per unit of NDF digested rose from 118 to 128, 153, and 166 g/kg across CNO treatments. Dietary CNO did not significantly affect apparent digestibility of CP but increased apparent starch digestibility from 92 to 95%. No FA C(10) or shorter were detected in feces, and apparent digestibility decreased with increasing FA chain length. Coconut oil concentrations of 2.7 or 3.3% decreased yields of milk FA C(14). The highest milk fat concentration (3.69%; 1.3% CNO) was due to the greatest yields of C(12) to C(16) milk FA. Milk FA concentrations of C(18:2 trans-10,cis-12) were related to increased dietary CNO concentrations and presumably to depressed ruminal NDF digestion. Moderate dietary CNO concentrations (e.g., 1.3%) may benefit lactational performance; however, CNO concentrations greater than or equal to 2.7% depressed dry matter intake, milk yield, milk fat yield, and NDF utilization. If mitigation of enteric CH(4) emissions is due to decreased digestion of dietary NDF, then this will lessen a major advantage of ruminants compared with nonruminants in food-production systems. Thus, CNO has limited use for enteric CH(4) mitigation in lactating dairy cows. PMID:22541489

  20. Diel variation in methane emissions from stands of Phragmites australis (Cav.) Trin. ex Steud. and Typha latifolia L. in a boreal lake

    Microsoft Academic Search

    Tiina Käki; Anne Ojala; Paula Kankaala

    2001-01-01

    Methane emission from Phragmites australis and Typha latifolia stands was quantified in Lake Vesijärvi, southern Finland. There were differences in emission rates at different times of the day in all the vegetation zones studies, but a clear pattern was found only occasionally. In the inner reed zone with shallow water (<2cm) the lowest emissions were usually recorded at night when

  1. New Constraints on Methane Emissions from 1978 to 1999 Using ?13C-CH4 and ?D-CH4 From Cape Meares, Oregon Archived Air

    NASA Astrophysics Data System (ADS)

    Roeger, F. H.; Butenhoff, C. L.; Rice, A. L.; Teama, D. G.

    2012-12-01

    Having the second largest radiative forcing of all anthropogenic greenhouse gases, methane (CH4) plays a crucial role in climate change and efforts at mitigation. Recently, the stable carbon and hydrogen isotopic ratios of methane ( ?13C and ?D) have been measured from archived air sampled at a marine Northern Hemisphere mid-latitude site (Cape Meares, Oregon, 45°N, 124°W) spanning the years 1978 to 1999. These new measurements, available at roughly monthly resolution, provide us with a unique new insight into the behavior of atmospheric CH4 during this important period when the growth rate of CH4 began a two-decade long decline for reasons that are not completely certain. Competing theories for the decline include changes in emissions from fossil fuel production, agriculture, and a return to steady state. We use the global 3D Chemistry Transport Model GEOS-Chem to simulate CH4, ?13C-CH4, and ?D-CH4 under different source history scenarios and place new constraints on emissions during the period 1978-1999. We also test the degree to which a widely used history of CH4 emissions (EDGAR4, EDGAR-HYDE) can simultaneously reproduce the measured dual CH4 isotope record during this time.

  2. Towards a Computational Model of a Methane Producing Archaeum

    PubMed Central

    Peterson, Joseph R.; Ellermeier, Jeremy R.; Kohler, Petra R. A.; Ha, Taekjip; Metcalf, William W.; Luthey-Schulten, Zaida

    2014-01-01

    Progress towards a complete model of the methanogenic archaeum Methanosarcina acetivorans is reported. We characterized size distribution of the cells using differential interference contrast microscopy, finding them to be ellipsoidal with mean length and width of 2.9??m and 2.3??m, respectively, when grown on methanol and 30% smaller when grown on acetate. We used the single molecule pull down (SiMPull) technique to measure average copy number of the Mcr complex and ribosomes. A kinetic model for the methanogenesis pathways based on biochemical studies and recent metabolic reconstructions for several related methanogens is presented. In this model, 26 reactions in the methanogenesis pathways are coupled to a cell mass production reaction that updates enzyme concentrations. RNA expression data (RNA-seq) measured for cell cultures grown on acetate and methanol is used to estimate relative protein production per mole of ATP consumed. The model captures the experimentally observed methane production rates for cells growing on methanol and is most sensitive to the number of methyl-coenzyme-M reductase (Mcr) and methyl-tetrahydromethanopterin:coenzyme-M methyltransferase (Mtr) proteins. A draft transcriptional regulation network based on known interactions is proposed which we intend to integrate with the kinetic model to allow dynamic regulation. PMID:24729742

  3. A methane-water model for coarse-grained simulations of solutions and clathrate hydrates.

    PubMed

    Jacobson, Liam C; Molinero, Valeria

    2010-06-01

    Methane is the prototypic hydrophobic molecule; it has an extremely low solubility in liquid water that leads to phase segregation. On the other hand, at moderate pressures and room temperature, water and methane form hydrate clathrate crystals with a methane to water ratio up to a 1000 times higher than the saturated aqueous phase. This apparent dichotomy points to a subtle balance between the strong water-water hydrogen bonding, responsible for the hydrophobic effect, and water-methane attraction. Capturing these nuances with molecular models requires an appropriate balance of intermolecular interactions. Here we present such a coarse-grained molecular model of water and methane that represents each molecule by a single particle interacting through very short-range interaction potentials. The model is based on the monatomic model of water mW [Molinero, V.; Moore, E. B. J. Phys. Chem. B 2009, 113, 4008] and is between 2 and 3 orders of magnitude more computationally efficient than atomistic models with Ewald sums. The coarse-grained model of this study reproduces the solubility and hydration number of methane in liquid water, the surface tension of the water-methane interface and the equilibrium melting temperature of methane hydrate clathrates with structures sI and sII. To the best of our knowledge this is the first force-field, atomistic or coarse-grained, that reproduces these range of properties of liquid and solid phases of water and methane, making it an efficient and accurate model for the study of the mechanisms of nucleation and growth of clathrates. We expect that the results of this work will also be useful for the modeling of the hydrophobic assembly in aqueous solutions and the development of coarse-grained models of biomolecules with explicit solvation. PMID:20462253

  4. Influence of methane emissions and vehicle efficiency on the climate implications of heavy-duty natural gas trucks.

    PubMed

    Camuzeaux, Jonathan R; Alvarez, Ramón A; Brooks, Susanne A; Browne, Joshua B; Sterner, Thomas

    2015-06-01

    While natural gas produces lower carbon dioxide emissions than diesel during combustion, if enough methane is emitted across the fuel cycle, then switching a heavy-duty truck fleet from diesel to natural gas can produce net climate damages (more radiative forcing) for decades. Using the Technology Warming Potential methodology, we assess the climate implications of a diesel to natural gas switch in heavy-duty trucks. We consider spark ignition (SI) and high-pressure direct injection (HPDI) natural gas engines and compressed and liquefied natural gas. Given uncertainty surrounding several key assumptions and the potential for technology to evolve, results are evaluated for a range of inputs for well-to-pump natural gas loss rates, vehicle efficiency, and pump-to-wheels (in-use) methane emissions. Using reference case assumptions reflecting currently available data, we find that converting heavy-duty truck fleets leads to damages to the climate for several decades: around 70-90 years for the SI cases, and 50 years for the more efficient HPDI. Our range of results indicates that these fuel switches have the potential to produce climate benefits on all time frames, but combinations of significant well-to-wheels methane emissions reductions and natural gas vehicle efficiency improvements would be required. PMID:25986359

  5. 3D Geological Modeling of CoalBed Methane (CBM) Resources in the Taldykuduk Block Karaganda Coal Basin, Kazakhstan

    NASA Astrophysics Data System (ADS)

    Sadykov, Raman; Kiponievich Ogay, Evgeniy; Royer, Jean-Jacques; Zhapbasbayev, Uzak; Panfilova, Irina

    2015-04-01

    Coal Bed Methane (CBM) is gas stored in coal layers. It can be extracted from wells after hydraulic fracturing and/or solvent injection, and secondary recovery techniques such as CO2 injection. Karaganda Basin is a very favorable candidate region to develop CBM production for the following reasons: (i) Huge gas potential; (ii) Available technologies for extracting and commercializing the gas produced by CBM methods; (iii) Experience in degassing during underground mining operations for safety reasons; (iv) Local needs in energy for producing electricity for the industrial and domestic market. The objectives of this work are to model the Taldykuduk block coal layers and their properties focusing on Coal Bed Methane production. It is motivated by the availability of large coal bed methane resources in Karaganda coal basin which includes 4 300 Bm3 equivalent 2 billion tons of coal (B = billion = 109) with gas content 15-25 m3/t of coal (for comparison San Juan basin (USA) has < 20 m3/t). The CBM reserves estimations are about: Saransk block, 26.3 Bm3 and Taldykuduk block, 23.5 Bm3. Methane (CH4) can be considered as an environmentally-friendly fuel compared to coal. Actually, the methane extracted during mining is released in the atmosphere, collecting it for recovering energy will reduce CO2 equivalent emissions by 36 Mt, good news regarding climate warming issues. The exploitation method will be based on a EOR technology consisting in injecting CO2 which replaces methane in pores because it has a higher adsorption capacity than CH4; exploiting CBM by CO2 injection provides thus a safe way to sequestrate CO2 in adsorbed form. The 3D geological model was built on Gocad/Skua using the following available data set: 926 wells and large area (7 x 12 km). No seismic data; coal type and chemical components (S, ash, …); unreliable available cross-section & maps due to old acquisition; quality mature coal; complex heterogeneous fractures network reported on geological cross sections; and utilization issues of the water extracted in the early stages of exploitation. The resulting 3D faulted model which includes more than 100 of faults will be further used to simulate the secondary recovery of methane by injecting CO2. The simulation will be carried out on a flow simulator assuming a two phase dimensionless formulation of CBM production in a double porosity model considering two domains: the matrix (m) and the fracture (f) for which the initial and boundary conditions are different. The resulting comprehensive 3D models had helped in better understanding the tectonic structures of the region, especially the relationships between the fault systems.

  6. Nitrous oxide and methane emission in an artificial wetland treating polluted runoff from an agricultural catchment

    NASA Astrophysics Data System (ADS)

    Mander, Ülo; Tournebize, Julien; Soosaar, Kaido; Chaumont, Cedric; Hansen, Raili; Muhel, Mart; Teemusk, Alar; Vincent, Bernard

    2015-04-01

    An artificial wetland built in 2010 to reduce water pollution in a drained agricultural watershed showed real potential for pesticide and nitrate removal. The 1.2 ha off-shore wetland with a depth of from 0.1 to 1 m intercepts drainage water from a 450 ha watershed located near the village of Rampillon (03°03'37.3'' E, 48°32'16.7'' N, 70 km south-east of Paris, France). A sluice gate installed at the inlet makes it possible to close the wetland during the winter months (December - March), when no pesticides are applied and rainfall events are more frequent. The flow entering the wetland fluctuates from 0 to 120 L/s. The wetland is partially covered by Carex spp., Phragmites australis, Juncus conglomeratus, Typha latifolia and philamentous algae. Since 2011, an automatic water quality monitoring system measures water discharge, temperature, dissolved O2, conductivity pH, NO3- and DOC in both inlet and outlet. In May 2014, an automatic weather station and Campbell Irgason system for the measurement of CO2 and H2O fluxes were installed in the middle of the wetland. In May and November 2014 one-week high frequency measurement campaigns were conducted to study N2O and CH4 fluxes using 6 manually operated opaque floating static chambers and 12 floating automatic dynamic chambers. The latter were operated via multiplexer and had an incubation time of 5 minutes, whereas the gas flow was continuously measured using the Aerodyne TILDAS quantum cascade laser system. During the campaign, the reduction of NO3- concentration was measured in nine reactor pipes. Also, water samples were collected for N2O and N2 isotope analysis, and sediments were collected for potential N2 emission measurements. In May, the hydraulic retention time (HRT) was 30 days, and the average NO3- concentration decreased from 24 in the inflow to 0 mg/L in the outflow. Methane flux was relatively high (average 1446, variation 0.2-113990 ?g CH4-C m-2 h-1), while about 2/3 was emitted via ebullition. Nitrous oxide flux was low (average 1.1, variation from -25 to 63 ?g N2O-N m-2 h-1) and showed consumption during the daytime. Similarly to CH4, most of the N2O emission originated from ebullition. The potential N2 flux from sediments was high (990-1920 ?g N m-2 h-1). In November, with HRT at about 3 days, the average NO3- concentration decreased from 45 to 20 mg/L. Methane flux was 2-3 times lower and N2O emission about 2 times higher than in May. This is related to the lower water temperature (20°C in May and 10°C in November) and shorter HRT in November. However, in situ pipe reactors showed a 90% NO3- removal potential in both periods. Offshore artificial wetlands can efficiently remove NO3- without significant N2O emission, although CH4 flux can be high during the first 5 years after establishment.

  7. Vegetation height and other controls of spatial variability in methane emissions from the Arctic coastal tundra at Barrow, Alaska

    NASA Astrophysics Data System (ADS)

    von Fischer, Joseph C.; Rhew, Robert C.; Ames, Gregory M.; Fosdick, Bailey K.; von Fischer, Paul E.

    2010-12-01

    We conducted measurements of methane (CH4) emission and ecosystem respiration on >200 points across the Arctic coastal tundra near Barrow, Alaska, United States, in July 2007 and August 2008. This site contains broad diversity in tundra microtopography, including polygonal tundra, thaw lakes, and drained lake basins. In 2007, we surveyed CH4 emissions across this landscape, and found that soil water content was the strongest control of methane emission rate, such that emission rates rose exponentially with water content. However, there was considerable residual variation in CH4 emission in the wettest soils (>80% volumetric water content) where CH4 emissions were highest. A statistical analysis of possible soil and plant controls on CH4 emission rates from these wet soils revealed that vegetation height (especially of Carex aquatilis) was the best predictor, with ecosystem respiration and permafrost depth as significant copredictors. To evaluate whether plant height served as a proxy for aboveground plant biomass, or gross primary production, we conducted a survey of CH4 emission rates from wet, Carex-dominated sites in 2008, coincidently measuring these candidate predictors. Surprisingly, vegetation height remained the best predictor of CH4 emission rates, with CH4 emissions rising exponentially with vegetation height. We hypothesize that taller plants have more extensive root systems that both stimulate more methanogenesis and conduct more pore water CH4 to the atmosphere. We anticipate that the magnitude of the climate change-CH4 feedback in the Arctic Coastal Plain will strongly depend on how permafrost thaw alters the ecology of Carex aquatilis.

  8. Greenhouse gas emissions from Indian rice fields: calibration and upscaling using the DNDC model

    Microsoft Academic Search

    H. Pathak; C. Li; R. Wassmann

    2005-01-01

    Crop growth simulation models provide a means to quantify the effects of climate, soil and management on crop growth and biogeochemical processes in soil. The Denitrification and Decomposition (DNDC) model was evaluated for its ability to simulate methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) emissions from Indian rice fields with various management practices. The model was calibrated and

  9. A COMPARISON OF METHODS FOR ESTIMATING GLOBAL METHANE EMISSIONS FROM LANDFILLS

    EPA Science Inventory

    Landfills are a significant source of methane, ranking third in anthropogenic sources after rice paddies and ruminants. Estimating the contribution of landfills to global methane flux is hampered by a lack of accurate refuse and landfill data, and therefore depends heavily on the...

  10. Spatial and seasonal variability of measured anthropogenic non-methane hydrocarbons in urban atmospheres: Implication on emission ratios

    NASA Astrophysics Data System (ADS)

    Boynard, Anne; Borbon, Agnès; Leonardis, Thierry; Barletta, Barbara; Meinardi, Simone; Blake, Don R.; Locoge, Nadine

    2014-01-01

    Continuous measurements of a wide range of non-methane hydrocarbons (NMHC) have been performed since 2001 in Paris megacity and three French medium-sized cities (Grenoble, Marseille, and Strasbourg). After a careful verification of the data measured, the ambient concentrations are used to analyze the spatial and seasonal variability of the anthropogenic NMHC and determine the present NMHC emission ratios relative to acetylene, a useful metric to evaluate and constraint emission inventories. We show that NMHC urban composition is consistent between all cities with no industrial influence and characteristic of the urban emission mixtures, which are mostly dominated by vehicle exhaust emissions. In winter, the urban NMHC composition generally shows an enhancement in combustion-derived products (alkenes, acetylene), C2-C3 alkanes and benzene, which presumes seasonal changes in emission ratio values. Present emission ratios of NMHC relative to acetylene are determined in Paris and Strasbourg both in summer and winter. They generally compare within a factor of two except for C7-C9 aromatics in Paris. On a seasonal basis, summertime emission ratios are three times higher than wintertime ones while they stay constant for combustion derived product (alkenes) and benzene. The unburned gasoline fraction (alkanes and C7-C9 aromatics) shows the maximum difference up to a factor of seven. These findings suggest that the emission ratios reflect seasonal changes in emissions and can be a useful metric to constraint temporally resolved emission inventories at different time of the year.

  11. Controls on northern wetland methane emissions: insights from regional synthesis studies and the Alaska Peatland Experiment (APEX)

    NASA Astrophysics Data System (ADS)

    Turetsky, M. R.; Euskirchen, E. S.; Czimczik, C. I.; Waldrop, M. P.; Olefeldt, D.; Fan, Z.; Kane, E. S.; McGuire, A. D.; Harden, J. W.

    2014-12-01

    Wetlands are the largest natural source of atmospheric methane. Static chambers have been used to quantify variation in wetland CH4 flux for many decades. Regional to global scale synthesis studies of static chamber measurements show that relationships between temperature, water availability and CH4 emissions depend on wetland type (bog, fen, swamp), region (tropical, temperate, arctic) and disturbance. For example, while water table position and temperature serve as the dominant controls on bog and swamp CH4 flux, vegetation is an important control on emissions from fens. These studies highlight the fact that wetland types have distinct controls on CH4 emissions; however, it is unlikely that modeling of wetland CH4 flux will improve without a better mechanistic understanding of the processes underlying CH4 production, transport, and oxidation. At the Alaska Peatland Experiment, we are quantifying CH4 emission using static chambers, automated chambers, and towers. Our sites vary in permafrost regime, including groundwater fens without permafrost, forested peat plateaus with intact permafrost, and collapse scar bogs formed through permafrost thaw. Experimental studies that examine plant and microbial responses to altered water table position and soil temperature are complemented by a gradient approach, where we use a space-for-time substitutions to examine the consequences of thaw on time-scales of decades to centuries. Our results thus far have documented the importance of soil rewetting in governing large CH4 fluxes from northern wetland soils. Accounting for CH4, our collapse scar bog significantly contributed to the global warming potential of the landscape. A major objective of our work is to explore the role of permafrost C release in greenhouse gas fluxes from wetland soils, which we are assessing using radiocarbon as a natural tracer. We have shown, for example, that ebullition of CH4 is dominated by recently fixed C, but a significant fraction of CH4 in bubbles is derived from old C released during thaw. The APEX time series datasets are being used in a variety of modeling studies, from small-scale soil pore and microbial controls on gas production and transport to regional scale assessments of how carbon cycle feedbacks to climate vary with wetland type and abundance.

  12. Small-scale methane dispersion modelling for possible plume sources on the surface of Mars

    NASA Astrophysics Data System (ADS)

    Olsen, K. S.; Cloutis, E.; Strong, K.

    2012-10-01

    Intense interest in the characteristics of a methane source on Mars has been spurred by recent observations of a plume structure. The current NASA Mars Science Laboratory and future landers and orbiters will be tasked with understanding the sources of methane. The Canadian Space Agency's Mars Methane Analogue Mission, involving a simulated Mars micro-rover field campaign, was recently able to detect and measure the isotopic composition of methane seeping from boreholes in a serpentine mine in Québec. We aim to determine spatial limits for detecting such a point source above the terrestrial background concentration of methane using gradient transport models. We estimate the source strength to be on the order of 5.3 × -10 kg s-1 and find that this produces detectable enhancements at distances less than 11.6 m from the source if there is no wind. These same models are applied to the Mars surface environment to determine whether an instrument on a rover would be capable of detecting a methane point source when not directly downwind of it. The estimated source strengths on Mars are much greater than at Jeffrey Mine and we find that these would be detectable at distances less than 30 m from the plume axis, which lies along the direction of advective transport. Much of the work done on modelling the Martian atmosphere uses large-scale general circulation models and this work examines the behaviour of methane plumes at very local scales.

  13. Comparison of pooled standard deviation and standardized-t bootstrap methods for estimating uncertainty about average methane emission from rice cultivation

    NASA Astrophysics Data System (ADS)

    Kang, Namgoo; Jung, Min-Ho; Jeong, Hyun-Cheol; Lee, Yung-Seop

    2015-06-01

    The general sample standard deviation and the Monte-Carlo methods as an estimate of confidence interval is frequently being used for estimates of uncertainties with regard to greenhouse gas emission, based on the critical assumption that a given data set follows a normal (Gaussian) or statistically known probability distribution. However, uncertainty estimated using those methods are severely limited in practical applications where it is challenging to assume the probability distribution of a data set or where the real data distribution form appears to deviate significantly from statistically known probability distribution models. In order to solve these issues encountered especially in reasonable estimation of uncertainty about the average of greenhouse gas emission, we present two statistical methods, the pooled standard deviation method (PSDM) and the standardized-t bootstrap method (STBM) based upon statistical theories. We also report interesting results of the uncertainties about the average of a data set of methane (CH4) emission from rice cultivation under the four different irrigation conditions in Korea, measured by gas sampling and subsequent gas analysis. Results from the applications of the PSDM and the STBM to these rice cultivation methane emission data sets clearly demonstrate that the uncertainties estimated by the PSDM were significantly smaller than those by the STBM. We found that the PSDM needs to be adopted in many cases where a data probability distribution form appears to follow an assumed normal distribution with both spatial and temporal variations taken into account. However, the STBM is a more appropriate method widely applicable to practical situations where it is realistically impossible with the given data set to reasonably assume or determine a probability distribution model with a data set showing evidence of fairly asymmetric distribution but severely deviating from known probability distribution models.

  14. Assessment of bubble-borne methane emissions in the East Siberian Arctic Shelf via interpretation of sonar data

    NASA Astrophysics Data System (ADS)

    Chernykh, D.; Leifer, I.; Shakhova, N. E.; Semiletov, I. P.

    2014-12-01

    Arctic warming is proposed to increase methane emissions from submerged permafrost driving a positive feedback. Where emissions are from shallow seas, bubbles transport much of the methane directly, while frequent Arctic storms sparge much of the remaining dissolved methane before microbes can oxidize it. Complexity arises where emissions are small bubbles or from deeper water due to dissolution below the storm-mixed layer. Given that these emissions span a wide geographic area, a promising remote sensing technology that has been used to map and estimate emissions; however, significant uncertainties exist in sonar data interpretation due to a range of parameters affecting sonar return including bubble size distribution and spatial distribution, vertical velocity, and temperature all of which are closely inter-related in a complex and at best poorly understood manner, and change as the bubble plume rises. This process was illustrated in a series of in situ calibration experiments in the East Siberian Arctic Sea (ESAS) where controlled air bubble plumes were created and observed with sonar to quantify the relationship between sonar return and bubble plume flux for a first calibration of in situ sonar bubble plume observations in the ESAS. Results highlight the importance of bubble plume dynamics to sonar return and the absence of a simple relationship between sonar return and bubble flux. Instead sonar return related to height above seabed, even accounting for dissolution and changing hydrostatic pressure, confirming earlier laboratory studies for a deeper water column. Calibrations then were applied to field data of an area of ESAS natural seepage.

  15. Modeling the impediment of methane ebullition bubbles by seasonal lake ice

    DOE PAGESBeta

    Greene, S.; Walter Anthony, K. M.; Archer, D.; Sepulveda-Jauregui, A.; Martinez-Cruz, K.

    2014-01-01

    Microbial methane (CH4) ebullition (bubbling) from anoxic lake sediments comprises a globally significant flux to the atmosphere, but ebullition bubbles in temperate and polar lakes can be trapped by winter ice cover and later released during spring thaw. This "ice-bubble storage" (IBS) constitutes a novel mode of CH4 emission. Before bubbles are encapsulated by downward-growing ice, some of their CH4 dissolves into the lake water, where it may be subject to oxidation. We present field characterization and a model of the annual CH4 cycle in Goldstream Lake, a thermokarst (thaw) lake in interior Alaska. We find that summertime ebullition dominatesmore »annual CH4 emissions to the atmosphere. Eighty percent of CH4 in bubbles trapped by ice dissolves into the lake water column in winter, and about half of that is oxidized. The ice growth rate and the magnitude of the CH4 ebullition flux are important controlling factors of bubble dissolution. Seven percent of annual ebullition CH4 is trapped as IBS and later emitted as ice melts. In a future warmer climate, there will likely be less seasonal ice cover, less IBS, less CH4 dissolution from trapped bubbles, and greater CH4 emissions from northern lakes.« less

  16. Effect of UV radiation and temperature on the emission of methane from plant biomass and structural components

    NASA Astrophysics Data System (ADS)

    Vigano, I.; van Weelden, H.; Holzinger, R.; Keppler, F.; McLeod, A.; Röckmann, T.

    2008-06-01

    The recently reported finding that plant matter and living plants produce significant amounts of the important greenhouse gas methane under aerobic conditions has led to an intense scientific and public controversy. Whereas some studies question the up-scaling method that was used to estimate the global source strength, others have suggested that experimental artifacts could have caused the reported signals, and two studies, one based on isotope labeling, have recently reported the absence of CH4 emissions from plants. Here we show using several independent experimental analysis techniques that dry and detached fresh plant matter, as well as several structural plant components, emit significant amounts of methane upon irradiation with UV light and/or heating. Emissions from UV irradiation are almost instantaneous, indicating a direct photochemical process. Long-time irradiation experiments demonstrate that the size of the CH4 producing reservoir is large, exceeding potential interferences from degassing or desorption processes by several orders of magnitude. A dry leaf of a pure 13C plant produces 13CH4 at a similar rate as dry leaves of non-labeled plants produce non-labeled methane.

  17. A Study on Methane and Nitrous Oxide Emissions Characteristics from Anthracite Circulating Fluidized Bed Power Plant in Korea

    PubMed Central

    Lee, Seehyung; Kim, Jinsu; Lee, Jeongwoo; Jeon, Eui-Chan

    2012-01-01

    In order to tackle climate change effectively, the greenhouse gas emissions produced in Korea should be assessed precisely. To do so, the nation needs to accumulate country-specific data reflecting the specific circumstances surrounding Korea's emissions. This paper analyzed element contents of domestic anthracite, calorific value, and concentration of methane (CH4) and nitrous oxide (N2O) in the exhaust gases from circulating fluidized bed plant. The findings showed the concentration of CH4 and N2O in the flue gas to be 1.85 and 3.25?ppm, respectively, and emission factors were 0.486 and 2.198?kg/TJ, respectively. The CH4 emission factor in this paper was 52% lower than default emission factor presented by the IPCC. The N2O emission factor was estimated to be 46% higher than default emission factor presented by the IPCC. This discrepancy can be attributable to the different methods and conditions of combustion because the default emission factors suggested by IPCC take only fuel characteristics into consideration without combustion technologies. Therefore, Korea needs to facilitate research on a legion of fuel and energy consumption facilities to develop country-specific emission factors so that the nation can have a competitive edge in the international climate change convention in the years to come. PMID:22666126

  18. Methane emission estimates from rice fields using ground truths and GIS/ RS approach for Karnal in Haryana-India

    NASA Astrophysics Data System (ADS)

    Gupta, Prabhat; Gupta, Vandana; Chandna, Parvesh; Kumar, Krishan; Ladha, J. K.

    Methane (CH4 ) is an important atmospheric greenhouse gas and has been estimated to account for 15-20 % of current radiative forcing. Rice cultivation has been identified as one of the important anthropogenic sources of CH4 and the type of water regime has been a major source of uncertainty in CH4 emission estimates and has direct bearing on its emissions. The present study aims to fill the gaps in uncertainty by adopting RS/ GIS based approach for the rice acreage estimation under different water regimes, so as to obtain CH4 emission estimates at the block level for Karnal district in Haryana state of India, using water regime specific methane emission factors (EF) generated from earlier emission data without any organic amendments and for low soil organic carbon. Total rice area was estimated using IRS LISS III - P6 satellite data of kharif season 2006. A survey was done from the rice-growing farmers across the village clusters of 3 blocks (Indri, Karnal and Nilokheri) of Karnal district, to capture the spatial variability of water regimes and its corresponding layer has been generated in GIS using inverse distance weightage (IDW) interpolation. The resulting spatial variability of water regimes was 42, 44 and 14% for MA, SA and CF, respectively. The overlay and intersection of thematic layer of rice crop with the water regime and administrative block boundary layers was done using GIS tools to arrive at the rice area under different water regimes at block level for Karnal. The annual CH4 emission from paddy fields of 3 blocks of Karnal district was estimated, using IPCC-1997 methodology, as the product of the rice area under each water regime of paddy growing ecosystem with the corresponding CH4 emission factors, at block level. The total budget, which is the sum of emissions, from each water regime at block level, was estimated to be 5.14 + 1.7 Gg y-1 .

  19. U.S. Natural Gas System Methane Emissions: State of Knowledge from LCAs, Inventories, and Atmospheric Measurements (Presentation)

    SciTech Connect

    Heath, G.

    2014-04-01

    Natural gas (NG) is a potential "bridge fuel" during transition to a decarbonized energy system: It emits less carbon dioxide during combustion than other fossil fuels and can be used in many industries. However, because of the high global warming potential of methane (CH4, the major component of NG), climate benefits from NG use depend on system leakage rates. Some recent estimates of leakage have challenged the benefits of switching from coal to NG, a large near-term greenhouse gas (GHG) reduction opportunity. During this presentation, Garvin will review evidence from multiple perspectives - life cycle assessments (LCAs), inventories and measurements - about NG leakage in the US. Particular attention will be paid to a recent article in Science magazine which reviewed over 20 years of published measurements to better understand what we know about total methane emissions and those from the oil and gas sectors. Scientific and policy implications of the state of knowledge will be discussed.

  20. Assessing the spatial and temporal variability of diffusive methane and nitrous oxide emissions from subtropical freshwater reservoirs.

    PubMed

    Musenze, Ronald S; Grinham, Alistair; Werner, Ursula; Gale, Deborah; Sturm, Katrin; Udy, James; Yuan, Zhiguo

    2014-12-16

    Surface water-methane (CH4) and nitrous oxide (N2O) concentrations were measured and diffusive fluxes were estimated in three subtropical freshwater reservoirs (Little Nerang Dam (LND), Lake Wivenhoe (LW) and Lake Baroon (LB)) in southeast Queensland, Australia, during four seasons in 2011-2012. All reservoirs were strong sources of CH4 in all seasons. Surface water CH4 varied between 1350 and 524,000% saturation, and was overall highest in spring and summer, and lowest in winter, however, with no clear patterns common to all reservoirs. In contrast, all reservoirs switched from weak N2O sinks in spring to strong N2O sources for the rest of the year. N2O saturation in all reservoirs varied between 70 and 1230%. There were significant differences for CH4 concentrations and fluxes between the reservoirs. Within each reservoir, there was strong spatial CH4 variability but minimal N2O saturation variability. CH4 saturation was higher in inflow zones than in the main body. Area-weighted average fluxes were estimated using six water-air gas transfer velocity estimation models and resulted in fluxes in the range 4.8-20.5, 2.3-5.4, and 2.3-7.5 mg CH4 m(-2) d(-1), while N2O was 0.07-0.41, 0.09-0.22, and 0.03-0.09 mg N2O m(-2) d(-1) for LND, LW, and LB, respectively. Total emissions, in carbon dioxide equivalents, from all measurement campaigns were CH4 dominated (67-86%). The measured degree of CH4 saturation and fluxes are among the highest reported thus far indicating that subtropical freshwater reservoirs could be significant aquatic greenhouse gas sources. This paper provides a comprehensive assessment of the interplay between biogeochemical processes and the physical forcing driving the water-air gaseous emissions. The high variability coupled with the lack of consensus among estimation models calls for concerted efforts to address uncertainty of measurements for reliable emissions accounting. PMID:25409278

  1. Causes of increasing atmospheric methane - Depletion of hydroxyl radicals and the rise of emissions

    NASA Technical Reports Server (NTRS)

    Khalil, M. A. K.; Rasmussen, R. A.

    1985-01-01

    A combination of anthropogenic activities and a possible decline of global concentrations for the hydroxyl radicals that formerly removed methane from the atmosphere are cited as potential causes for the 1.3 percent/year rise of atmospheric methane levels. Calculations are presented which show that much of the methane increase over the last 200 years is probably to be divided among the two main sources in the proportions of 70 percent for anthropogenic generation and 30 percent for hydroxyl radical depletion. It is projected that in 20 years, average tropospheric concentrations of methane may be about 20 percent greater than 1980 levels. The current abundance of hydroxyl radicals may be 20 percent less than two centuries ago.

  2. Significant Emissions of Methane and Nitrous Oxide Following Clear-cutting of a Boreal Forest Stand

    NASA Astrophysics Data System (ADS)

    Vestin, P.; Mölder, M.; Sundqvist, E.; Hellström, M.; Båth, A.; Klemedtsson, L. K.; Lindroth, A.

    2011-12-01

    Clear-cutting and subsequent site preparation is common forest management practice in Sweden. According to the Swedish National Forest Inventory, an average of 196 000 ha were clear-cut annually during the period 2005-2009. The net effects of final fellings on greenhouse gas fluxes are not well understood. Increased substrate availability for decomposers following harvest may result in higher carbon dioxide (CO2) emissions from soils and in increased nitrogen mineralization. This may be further enhanced by increased soil temperatures after site preparation. In addition, removal of trees causes reduced evapotranspiration and subsequently a raised ground water table, which may have consequences for methane (CH4) and nitrous oxide (N2O) fluxes. The net effects of clear-cutting on CH4, N2O, CO2 and H2O fluxes were studied at Norunda forest in central Sweden. Micrometeorological measurements (i.e. flux-gradient and eddy covariance) allowed for quantification of CO2, CH4, N2O and H2O fluxes at two different plots on a new clear-cut. Measurements of CH4, CO2 and H2O fluxes started in May 2010 while N2O flux measurements begun in June 2011. Soil chamber measurements (CO2, CH4 and H2O) were carried out in the adjacent forest stand during the main growing season of 2010 and at the clear-cut during October-November 2010. The clear-cut became waterlogged after harvest (more pronounced at plot 1) and preliminary results indicate a switch from a weak CH4 sink to a significant CH4 source at both plots. Daily average fluxes during the period 20 May through 30 November 2010 were of the order of -6.3 - +142.5 ?mol m-2h-1 (Fig.1) with mean values of 39.0 ?mol m-2h-1 (plot 1) and 16.3 ?mol m-2h-1 (plot 2). The preliminary results also indicate enhanced CO2 emissions and increased soil temperatures at disturbed microsites. Raw N2O data imply N2O fluxes of the order of 1-10 ?mol m-2h-1 during daytime (well-mixed) conditions. Available data, including 2011, will be further analyzed and presented at the conference.

  3. Impacts of Application of Methane Fermentation Digested Liquid on Green House Gas Emissions and Nitrogen Leaching from Upland Field

    NASA Astrophysics Data System (ADS)

    Nakamura, Masato; Fujikawa, Tomonori; Yuyama, Yoshito; Maeda, Morihiro; Yamaoka, Masaru

    Nitrogen uptake by crops, green-house gas emissions and nitrogen leaching were studied by using monolith lysimeters applied with digested liquid or ammonium sulfate to evaluate the environmental impacts of applications of methane fermentation digested liquid on Andosol upland field. A two-year experiment indicated the percentages of nitrogen uptake, leached nitrogen and nitrous oxide (N2O) emissions to each material-derived nitrogen were 27%, 44% and 0.41% in the digested liquid plot and 32%, 46% and 0.11% in the ammonium sulfate plot. The results show that digested liquid is readily release fertilizer like ammonium sulfate, and nitrogen is leached as easily from the digested liquid as from the ammonium sulfate and the N2O emissions from the digested liquid plot are higher than from the ammonium sulfate plot.

  4. Changes in the global methane budget since 2000

    NASA Astrophysics Data System (ADS)

    Bousquet, P.; Saunois, M.; Poulter, B.; Ciais, P.; Canadell, J.; Dlugokencky, E. J.; Peregon, A.

    2014-12-01

    Methane is the second anthropogenic greenhouse gas after carbon dioxide. Atmospheric methane has contributed about 20% of the climate forcing by long-lived greenhouse gases since pre-industrial times but also influences the oxidizing capacity of the atmosphere. With a lifetime of 9-10 years in the atmosphere, methane is an important target for climate change mitigation. Observations of atmospheric methane began in 1978, reached global coverage after 1983, and now include a large variety of in-situ and remote-sensed observations. After the loss of SCIAMACHY (2002-2012), two space missions are currently producing methane weighted-columns, GOSAT (since 2009) and METOP-IASI (since 2007). Although sources and sinks of methane are identified, large uncertainties remain in their spatio-temporal quantification. Here, we present a synthesis of methane emissions and sinks since 2000 using an integrated approach to combine: atmospheric measurements, chemistry-transport models, ecosystem models, emission inventories, and climate-chemistry models. The results of an ensemble of atmospheric inversions (top-down) and of process-based models (bottom-up) are presented and compared in order to propose scenarios for the increase of atmospheric methane since 2007, after almost a decade of stagnation. Global and regional methane budgets and their changes are presented and discussed for the period 2000-2012. Focus is placed in comparing methane inversions constrained by satellite data with those constrained by surface data.

  5. Stimulated Raman scattering in methane-experimental optimization and numerical model

    Microsoft Academic Search

    Amit Kazzaz; Shlomo Ruschin; Itamar Shoshan; Gad Ravnitsky

    1994-01-01

    The stimulated Raman effect in methane was investigated both theoretically and experimentally. An experimental setup was used to optimize the Raman conversion of a 1.06-? laser source into a wavelength of 1.54 ?m in pressurized methane. Efficient conversion (up to 45% efficiency) is accomplished when using a full-resonator configuration for the Stokes wavelength. A numerical model is introduced, describing the

  6. Characterizing Methane Emissions at Local Scales with a 20 Year Total Hydrocarbon Time Series, Imaging Spectrometry, and Web Facilitated Analysis

    NASA Astrophysics Data System (ADS)

    Bradley, Eliza Swan

    Methane is an important greenhouse gas for which uncertainty in local emission strengths necessitates improved source characterizations. Although CH4 plume mapping did not motivate the NASA Airborne Visible InfraRed Imaging Spectrometer (AVIRIS) design and municipal air quality monitoring stations were not intended for studying marine geological seepage, these assets have capabilities that can make them viable for studying concentrated (high flux, highly heterogeneous) CH4 sources, such as the Coal Oil Point (COP) seep field (˜0.015 Tg CH4 yr-1) offshore Santa Barbara, California. Hourly total hydrocarbon (THC) data, spanning 1990 to 2008 from an air pollution station located near COP, were analyzed and showed geologic CH4 emissions as the dominant local source. A band ratio approach was developed and applied to high glint AVIRIS data over COP, resulting in local-scale mapping of natural atmospheric CH4 plumes. A Cluster-Tuned Matched Filter (CTMF) technique was applied to Gulf of Mexico AVIRIS data to detect CH4 venting from offshore platforms. Review of 744 platform-centered CTMF subsets was facilitated through a flexible PHP-based web portal. This dissertation demonstrates the value of investigating municipal air quality data and imaging spectrometry for gathering insight into concentrated methane source emissions and highlights how flexible web-based solutions can help facilitate remote sensing research.

  7. Methane and carbon dioxide emissions from 40 lakes along a north–south latitudinal transect in Alaska

    DOE PAGESBeta

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

    2014-01-01

    Uncertainties in the magnitude and seasonality of various gas emission modes, particularly among different lake types, limit our ability to estimate methane (CH4) and carbon dioxide (CO2) emissions from northern lakes. Here we assessed the relationship between CH4 and CO2 emission modes in 40 lakes along a latitudinal transect in Alaska to physicochemical limnology and geographic characteristics, including permafrost soil type surrounding lakes. Emission modes included Direct Ebullition, Diffusion, Storage flux, and a newly identified Ice-Bubble Storage (IBS) flux. We found that all lakes were net sources of atmospheric CH4 and CO2, but the climate warming impact of lake CH4more »emissions was two times higher than that of CO2. Ebullition and Diffusion were the dominant modes of CH4 and CO2 emissions respectively. IBS, ~ 10% of total annual CH4 emissions, is the release to the atmosphere of seasonally ice-trapped bubbles when lake ice confining bubbles begins to melt in spring. IBS, which has not been explicitly accounted for in regional studies, increased the estimate of springtime emissions from our study lakes by 320%. Geographically, CH4 emissions from stratified, dystrophic interior Alaska thermokarst (thaw) lakes formed in icy, organic-rich yedoma permafrost soils were 6-fold higher than from non-yedoma lakes throughout the rest of Alaska. Total CH4 emission was correlated with concentrations of phosphate and total nitrogen in lake water, Secchi depth and lake area, with yedoma lakes having higher nutrient concentrations, shallower Secchi depth, and smaller lake areas. Our findings suggest that permafrost type plays important roles in determining CH4 emissions from lakes by both supplying organic matter to methanogenesis directly from thawing permafrost and by enhancing nutrient availability to primary production, which can also fuel decomposition and methanogenesis.« less

  8. Modeling CH4 emission from a Siberia tundra site

    NASA Astrophysics Data System (ADS)

    Mi, Y.; van Huissteden, J.

    2012-12-01

    Methane emission from peat soil links strongly to atmosphere methane concentration. Peatland-VU was developed as a process-based model, to simulate CH4 fluxes from peat soils. The model combined primary production, aerobic decomposition of soil organic matter, CH4 formation, oxidation, and transport. The new version model has been enhanced by including 1) a hydrological module to calculate water table, which plays a key role during the processes of methane production, for it determines the extents of anaerobic and aerobic soil zone, 2) a photosynthesis model to simulate net primary production. The soil freezing is also improved with a better calculation of the soil thermal conductivity. We test Peatland-VU on Kytalyk tundra site, an area situated in northeastern Siberia continuous permafrost zone, over a longer period of time (data series of 2003-2010). The results show that the magnitude of the simulated CH4 fluxes agree well with the measured fluxes, the seasonal patterns of the fluxes are correctly modeled as