Science.gov

Sample records for modeling methane emissions

  1. Coupled land-atmosphere modeling of methane emissions with WRF

    NASA Astrophysics Data System (ADS)

    Taylor, D.

    2013-12-01

    This project aims to couple a soil model for methane transport to an atmospheric model to predict methane emissions and dispersion. Methane is a potent greenhouse gas, 20 times as efficient at trapping heat in the atmosphere as the most prevalent greenhouse gas, carbon dioxide. It has been estimated that 60% of methane emissions in the earth's atmosphere come from anthropogenic sources, 17% of which comes from landfills, making landfills the third largest contributor of human-generated methane. Due to high costs and non-ideal weather conditions, field measurements of methane concentration at landfills are difficult and infrequent, so estimates of annual emissions from landfills are not very accurate. We plan to create a coupled land-atmosphere model that takes production and oxidation of methane into account when calculating methane emissions. This model will give a better understanding of how much methane is emitted annually from a given landfill and assist with monitoring efforts. It will also demonstrate the magnitude of diurnal and seasonal variations in methane emissions, which may identify errors in yearly methane emissions estimates made by extrapolating from a small number of field measurements. As a first step, an existing land-surface model, Noah, is modified to compute the transport of oxygen and methane along a 1-D soil column. Surface emissions are calculated using a gradient flux method with a boundary layer conductance that depends on the wind speed. These modifications to the land-surface model will be added to the Weather Research and Forecasting model to predict atmospheric dispersion of methane emitted by landfills. Comparisons to observations are made at two different landfill sites to validate the coupled model.

  2. Modeling Modern Methane Emissions From Natural Wetlands. 1; Model Description

    NASA Technical Reports Server (NTRS)

    Walter, Bernadette P.; Heimann, Martin; Matthews, Elaine; Hansen, James E. (Technical Monitor)

    2001-01-01

    Methane is an important greenhouse gas which contributes about 22% to the present greenhouse effect. Natural wetlands currently constitute the biggest methane source and were the major one in pre-industrial times. Wetland emissions depend highly on the climate, i.e., on soil temperature and water table. In order to investigate the response of methane emissions from natural wetlands to climate variations, a process-based model that derives methane emissions from natural wetlands as a function of soil temperature, water table, and Net Primary Productivity is used. For its application on the global scale, global data sets for all model parameters are generated. In addition, a simple hydrologic model is developed in order to simulate the position of the water table in wetlands. The hydrologic model is tested against data from different wetland sites, and the sensitivity of the hydrologic model to changes in precipitation is examined. The global methane-hydrology model constitutes a tool to study temporal and spatial variations in methane emissions from natural wetlands.

  3. 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 ...

  4. DEVELOPMENT OF AN EMPIRICAL MODEL OF METHANE EMISSIONS FROM LANDFILLS

    EPA Science Inventory

    The report gives results of a field study of 21 U.S. landfills with gas recovery systems, to gather information that can be used to develop an empirical model of methane (CH4) emissions. Site-specific information includes average CH4 recovery rate, landfill size, tons of refuse (...

  5. DEVELOPMENT OF AN EMPIRICAL MODEL OF METHANE EMISSIONS FROM LANDFILLS

    EPA Science Inventory

    The report gives results of a field study of 21 U.S. landfills with gas recovery systems, to gather information that can be used to develop an empirical model of methane (CH4) emissions. ite-specific information includes average CH4 recovery rate, landfill size, tons of refuse (r...

  6. 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.

  7. 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.

  8. Modeling Modern Methane Emissions from Natural Wetlands. 2; Interannual Variations 1982-1993

    NASA Technical Reports Server (NTRS)

    Walter, Bernadette P.; Heimann, Martin; Mattews, Elaine; Hansen, James E. (Technical Monitor)

    2001-01-01

    A global run of a process-based methane model [Walter et al., this issue] is performed using high-frequency atmospheric forcing fields from ECMWF reanalyses of the period from 1982 to 1993. We calculate global annual methane emissions to be 260 Tg/ yr. 25% of methane emissions originate from wetlands north of 30 deg. N. Only 60% of the produced methane is emitted, while the rest is re-oxidized. A comparison of zonal integrals of simulated global wetland emissions and results obtained by an inverse modeling approach shows good agreement. In a test with data from two wetlands, the seasonality of simulated and observed methane emissions agrees well. The effects of sub-grid scale variations in model parameters and input data are examined. Modeled methane emissions show high regional, seasonal and interannual variability. Seasonal cycles of methane emissions are dominated by temperature in high latitude wetlands, and by changes in the water table in tropical wetlands. Sensitivity tests show that +/- 1 C changes in temperature lead to +/- 20 % changes in methane emissions from wetlands. Uniform changes of +/- 20% in precipitation alter methane emissions by about +/- 18%. Limitations in the model are analyzed. Simulated interannual variations in methane emissions from wetlands are compared to observed atmospheric growth rate anomalies. Our model simulation results suggest that contributions from other sources than wetlands and/or the sinks are more important in the tropics than north-of 30 deg. N. In higher northern latitudes, it seems that a large part, of the observed interannual variations can be explained by variations in wetland emissions. Our results also suggest that reduced wetland emissions played an important role in the observed negative methane growth rate anomaly in 1992.

  9. 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.

  10. Modelling global methane emissions from livestock: Biological and nutritional controls

    NASA Technical Reports Server (NTRS)

    Johnson, Donald E.

    1992-01-01

    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.

  11. Model estimates of global and regional atmospheric methane emissions of wetland ecosystems

    NASA Astrophysics Data System (ADS)

    Denisov, S. N.; Eliseev, A. V.; Mokhov, I. I.; Arzhanov, M. M.

    2015-09-01

    Estimates of the changes of atmospheric methane emissions from wetland ecosystems for different regions and the Earth as a whole are performed. The new version of the model of methane emissions from soil in a global climate model of intermediate complexity developed at the A.M. Obukhov Institute of atmospheric physics is used. Numerical experiments in accordance with the conditions of WETCHIMP (Wetland and Wetland CH4 Inter-comparison of Models Project) have been performed. The model is capable of realistically reproducing global and regional characteristics of methane emissions. The general trend of increases in methane flows from wetland ecosystems into the atmosphere due to global warming is noted. According to the results of calculations, the global natural methane emissions from wetlands have increased in the 20th century by 9 MtCH4/year. The sensitivity of global methane emissions to changes in global near-surface temperature over the land was estimated to be equal to 16 MtCH4/year/K (approximately 10%/K). With continuing warming, we can expect a significant increase in methane emissions, primarily from the high latitudes of the northern hemisphere.

  12. Comparison of model estimates of the effects of aviation emissions on atmospheric ozone and methane

    E-print Network

    Jacobson, Mark

    Comparison of model estimates of the effects of aviation emissions on atmospheric ozone and methane 2013. [1] One of the significant uncertainties in understanding the effects of aviation on climate is the effects of aviation emissions on ozone and atmospheric chemistry. In this study the effects of aviation

  13. Methane Emission by Camelids

    PubMed Central

    Dittmann, Marie T.; Runge, Ullrich; Lang, Richard A.; Moser, Dario; Galeffi, Cordula; Kreuzer, Michael; Clauss, Marcus

    2014-01-01

    Methane emissions from ruminant livestock have been intensively studied in order to reduce contribution to the greenhouse effect. Ruminants were found to produce more enteric methane than other mammalian herbivores. As camelids share some features of their digestive anatomy and physiology with ruminants, it has been proposed that they produce similar amounts of methane per unit of body mass. This is of special relevance for countrywide greenhouse gas budgets of countries that harbor large populations of camelids like Australia. However, hardly any quantitative methane emission measurements have been performed in camelids. In order to fill this gap, we carried out respiration chamber measurements with three camelid species (Vicugna pacos, Lama glama, Camelus bactrianus; n?=?16 in total), all kept on a diet consisting of food produced from alfalfa only. The camelids produced less methane expressed on the basis of body mass (0.32±0.11 L kg?1 d?1) when compared to literature data on domestic ruminants fed on roughage diets (0.58±0.16 L kg?1 d?1). However, there was no significant difference between the two suborders when methane emission was expressed on the basis of digestible neutral detergent fiber intake (92.7±33.9 L kg?1 in camelids vs. 86.2±12.1 L kg?1 in ruminants). This implies that the pathways of methanogenesis forming part of the microbial digestion of fiber in the foregut are similar between the groups, and that the lower methane emission of camelids can be explained by their generally lower relative food intake. Our results suggest that the methane emission of Australia's feral camels corresponds only to 1 to 2% of the methane amount produced by the countries' domestic ruminants and that calculations of greenhouse gas budgets of countries with large camelid populations based on equations developed for ruminants are generally overestimating the actual levels. PMID:24718604

  14. Development of correction factors for landfill gas emission model suiting Indian condition to predict methane emission from landfills.

    PubMed

    Sil, Avick; Kumar, Sunil; Wong, Jonathan W C

    2014-09-01

    Methane emission from landfill gas emission (LandGEM) model was validated through the results of laboratory scale biochemical methane potential assay. Results showed that LandGEM model over estimates methane (CH4) emissions; and the true CH4 potential of waste depends on the level of segregation. Based on these findings, correction factors were developed to estimate CH4 emission using LandGEM model especially where the level of segregation is negligible or does not exist. The correction factors obtained from the study were 0.94, 0.13 and 0.74 for food waste, mixed un-segregated municipal solid waste (MSW) and vegetable wastes, respectively. PMID:24685512

  15. 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.

  16. Methane emissions from MBT landfills

    SciTech Connect

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

    2013-09-15

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

  17. Estimating methane emissions from landfills based on rainfall, ambient temperature, and waste composition: The CLEEN model.

    PubMed

    Karanjekar, Richa V; Bhatt, Arpita; Altouqui, Said; Jangikhatoonabad, Neda; Durai, Vennila; Sattler, Melanie L; Hossain, M D Sahadat; Chen, Victoria

    2015-12-01

    Accurately estimating landfill methane emissions is important for quantifying a landfill's greenhouse gas emissions and power generation potential. Current models, including LandGEM and IPCC, often greatly simplify treatment of factors like rainfall and ambient temperature, which can substantially impact gas production. The newly developed Capturing Landfill Emissions for Energy Needs (CLEEN) model aims to improve landfill methane generation estimates, but still require inputs that are fairly easy to obtain: waste composition, annual rainfall, and ambient temperature. To develop the model, methane generation was measured from 27 laboratory scale landfill reactors, with varying waste compositions (ranging from 0% to 100%); average rainfall rates of 2, 6, and 12mm/day; and temperatures of 20, 30, and 37°C, according to a statistical experimental design. Refuse components considered were the major biodegradable wastes, food, paper, yard/wood, and textile, as well as inert inorganic waste. Based on the data collected, a multiple linear regression equation (R(2)=0.75) was developed to predict first-order methane generation rate constant values k as functions of waste composition, annual rainfall, and temperature. Because, laboratory methane generation rates exceed field rates, a second scale-up regression equation for k was developed using actual gas-recovery data from 11 landfills in high-income countries with conventional operation. The Capturing Landfill Emissions for Energy Needs (CLEEN) model was developed by incorporating both regression equations into the first-order decay based model for estimating methane generation rates from landfills. CLEEN model values were compared to actual field data from 6 US landfills, and to estimates from LandGEM and IPCC. For 4 of the 6 cases, CLEEN model estimates were the closest to actual. PMID:26346020

  18. The Non-LTE Model of IR Emissions of Methane in the Titan's Atmosphere

    NASA Astrophysics Data System (ADS)

    Kutepov, Alexander; Rezac, Ladislav; Rey, Michael; Nikitin, Andrei; Boursier, Corinne

    2014-11-01

    Above about 400-450 km in Titan's atmosphere, the assumption of local thermodynamic equilibrium (LTE) breaks down for molecular vibrational levels of methane and various trace gases. Above this altitude non-LTE significantly impacts the formation of infrared ro-vibrational band emissions of these species observed in the limb viewing geometry. We present detailed model of the non-LTE in methane in the Titan's atmosphere based on a new extended database of the CH4 spectroscopic parameters as well as on the revised system of collisional V-T and V-V exchange rates. We analyze for a number of atmospheric models the vibrational temperatures of various CH4 levels and limb emissions, and compare them with those obtained for the HITRAN-2012 methane spectroscopic parameters. Implications for the non-LTE diagnostics of the Cassini CIRS and VIMS measurements are discussed.

  19. Model Estimate of Pan-Arctic Lakes and Wetlands Methane Emissions and Their Future Climate Response

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Lakes and wetlands are important sources of the greenhouse gas CH4, whose emission rate is sensitive to climate. The northern high latitudes, which are especially susceptible to climate change, contain about 50% of the world's lakes and wetlands. Given predicted changes in the climate of this region over the next century (IPCC AR5 scenarios), there is concern about a possible positive feedback resulting from methane emissions from the region's wetlands and lakes. To study the climate response of emissions from northern high latitude lakes and wetlands, we employed a large-scale hydrology and carbon cycling model (Variable Infiltration Capacity model; VIC) over the Pan-Arctic domain, which was linked to an atmospheric model (Japan's National Institute of Environmental Studies transport model; NIES TM). In particular, the VIC model simulates the land surface hydrology and carbon cycling across a dynamic lake-wetland continuum, while NIES TM models the atmospheric mixing and 3-dimension transport of methane emitted. The VIC model includes a distributed wetland water table scheme, which accounts for microtopography around the lakes 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 at the land surface have been calibrated using extensive in situ observations at West Siberia. Also, the atmospheric methane concentration from this linked model run was verified for the recent 5 years with satellite observations from Aqua's Atmospheric Infrared Sounder (AIRS) and Envisat's Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) instruments. Using RCP4.5 and RCP8.5 future climate scenarios, we examine CH4 emissions from high latitude lakes and wetlands, as well as their net greenhouse warming potential, over the next 3 centuries across the Pan-Arctic domain. We also assess relative uncertainties in emissions from each of the sources.

  20. The landfill methane balance: Model and practical applications

    SciTech Connect

    Bogner, J.; Spokas, K.

    1995-10-01

    A rational mass-balance framework is described for improved quantification of landfill methane processes at a given site. The methane balance model examines the partitioning of methane generated into methane recovered (via extraction systems), methane emitted, methane oxidized, methane migrated, and methane storage. This model encourages use of field-based data to better quantify rates of methane recovery and emissions.

  1. 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

  2. A Simulation Model of Carbon Cycling and Methane Emissions in Amazon Wetlands

    NASA Technical Reports Server (NTRS)

    Potter, Christopher; Melack, John; Hess, Laura; Forsberg, Bruce; Novo, Evlyn Moraes; Klooster, Steven

    2004-01-01

    An integrative carbon study is investigating the hypothesis that measured fluxes of methane from wetlands in the Amazon region can be predicted accurately using a combination of process modeling of ecosystem carbon cycles and remote sensing of regional floodplain dynamics. A new simulation model has been build using the NASA- CASA concept for predicting methane production and emission fluxes in Amazon river and floodplain ecosystems. Numerous innovations area being made to model Amazon wetland ecosystems, including: (1) prediction of wetland net primary production (NPP) as the source for plant litter decomposition and accumulation of sediment organic matter in two major vegetation classes - flooded forests (varzea or igapo) and floating macrophytes, (2) representation of controls on carbon processing and methane evasion at the diffusive boundary layer, through the lake water column, and in wetland sediments as a function of changes in floodplain water level, (3) inclusion of surface emissions controls on wetland methane fluxes, including variations in daily surface temperature and of hydrostatic pressure linked to water level fluctuations. A model design overview and early simulation results are presented.

  3. An Ecosystem Simulation Model for Methane Production and Emission from Wetlands

    NASA Technical Reports Server (NTRS)

    Potter, C. S.; Peterson, David L. (Technical Monitor)

    1997-01-01

    Previous experimental studies suggest that methane emission from wetland is influenced by multiple interactive pathways of gas production and transport through soil and sediment layers to the atmosphere. The objective of this study is to evaluate a new simulation model of methane production and emission in wetland soils that was developed initially to help identify key processes that regulate methanogenesis and net flux of CH4 to the air, but which is designed ultimately for regional simulation using remotely sensed inputs for land cover characteristics. The foundation for these computer simulations is based on a well-documented model (CASA) of ecosystem production and carbon cycling in the terrestrial blaspheme. Modifications to represent flooded wetland soils and anaerobic decomposition include three new sub-models for: (1) layered soil temperature and water table depth (WTD) as a function of daily climate drivers, (2) CH4 production within the anoxic soil layer as a function of WTD and CO2 production under poorly drained conditions, and (3) CH4 gaseous transport pathways (molecular diffusion, ebullition, and plant vascular transport) as a function of WTD and ecosystem type. The model was applied and tested using climate and ecological data to characterize tundra wetland sites near Fairbanks, Alaska studied previously by Whalen and Reeburgh. Comparison of model predictions to measurements of soil temperature and thaw depth, water-table depth, and CH4 emissions over a two year period suggest that inter-site differences in soil physical conditions and methane fluxes could be reproduced accurately for selected periods. Day-to-day comparison of predicted emissions to measured CH4 flux rates reveals good agreement during the early part of the thaw season, but the model tends to underestimate production of CH4 during the months of July and August in both test years. Important seasonal effects, including that of falling WTD during these periods, are apparently overlooked in the model formulation. Nevertheless, reasonably close agreement was achieved between the model's mean daily and seasonal estimates of CH4 flux and observed emission rates for northern wetland ecosystems. Several features of the model are identified as crucial to more accurate prediction of wetland methane emission, including the capacity to incorporate influences of localized topographic and hydrologic features on site-specific soil temperature and WTD dynamics, and mechanistic simulation of methane emission transport pathways from within the soil profile.

  4. The Non-LTE Model of IR Emissions of Methane in the Titan'sAtmosphere

    NASA Astrophysics Data System (ADS)

    Kutepov, Alexander; Rezac, Ladislav; Feofilov, Artem; Rey, Michael; Nikitin, Andrei; Tyuterev, Vladimir

    2015-11-01

    Above about 400-450 km in Titan's atmosphere, the assumption of local thermodynamic equilibrium (LTE) breaks down for molecular vibrational levels of methane and various trace gases. Above this altitude non-LTE significantly impacts the formation of infrared ro-vibrational band emissions of these species observed in the limb viewing geometry. We present detailed model of the non-LTE in methane in the Titan's atmosphere based on a new extended database of the CH4 spectroscopic parameters calculated for this study. We analyze vibrational temperatures of various 12CH4 and 13CH4 levels as well as CH4 limb emissions in the 7.6 and 3.3 um spectral regions. The impact on these emissions of many weak one-quantum and combinational bands, which are missing in current databases, is studied. Implications for the non-LTE diagnostics of the Cassini CIRS and VIMS measurements are discussed.

  5. 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.

  6. Methane emissions from MBT landfills.

    PubMed

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

    2013-09-01

    Within the scope of an investigation for the German Federal Environment Agency ("Umweltbundesamt"), the basics for the estimation of the methane emissions from the landfilling of mechanically and biologically treated waste (MBT) were developed. For this purpose, topical research including monitoring results regarding the gas balance at MBT landfills was evaluated. For waste treated to the required German standards, a methane formation potential of approximately 18-24 m(3)CH(4)/t of total dry solids may be expected. Monitoring results from MBT landfills show that a three-phase model with differentiated half-lives describes the degradation kinetics in the best way. This is due to the fact that during the first years of disposal, the anaerobic degradation processes still proceed relatively intensively. In addition in the long term (decades), a residual gas production at a low level is still to be expected. Most of the soils used in recultivation layer systems at German landfills show a relatively high methane oxidation capacity up to 5 l CH(4)/(m(2)h). However, measurements at MBT disposal sites indicate that the majority of the landfill gas (in particular at non-covered areas), leaves the landfill body via preferred gas emission zones (hot spots) without significant methane oxidation. Therefore, rather low methane oxidation factors are recommended for open and temporarily covered MBT landfills. Higher methane oxidation rates can be achieved when the soil/recultivation layer is adequately designed and operated. Based on the elaborated default values, the First Order Decay (FOD) model of the IPCC Guidelines for National Greenhouse Gas Inventories, 2006, was used to estimate the methane emissions from MBT landfills. Due to the calculation made by the authors emissions in the range of 60,000-135,000 t CO(2-eq.)/a for all German MBT landfills can be expected. This wide range shows the uncertainties when the here used procedure and the limited available data are applied. It is therefore necessary to generate more data in the future in order to calculate more precise methane emission rates from MBT landfills. This is important for the overall calculation of the climate gas production in Germany which is required once a year by the German Government. PMID:23756351

  7. 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.

  8. 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.

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

    USGS Publications Warehouse

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

    2014-01-01

    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.

  10. MODELING THE EMISSIONS OF NITROUS OXIDE (N20) AND METHANE (CH 4) FROM THE

    E-print Network

    wetlands, tropical wetlands and wet tundra. For high latitude wetlands (i.e. northern bogs), the emission and the bog soil tempera- ture, which are then used in an empirical formula to predict methane emissions

  11. Emission of methane from plants

    PubMed Central

    Nisbet, R.E.R.; Fisher, R.; Nimmo, R.H.; Bendall, D.S.; Crill, P.M.; Gallego-Sala, A.V.; Hornibrook, E.R.C.; López-Juez, E.; Lowry, D.; Nisbet, P.B.R.; Shuckburgh, E.F.; Sriskantharajah, S.; Howe, C.J.; Nisbet, E.G.

    2009-01-01

    It has been proposed that plants are capable of producing methane by a novel and unidentified biochemical pathway. Emission of methane with an apparently biological origin was recorded from both whole plants and detached leaves. This was the first report of methanogenesis in an aerobic setting, and was estimated to account for 10–45 per cent of the global methane source. Here, we show that plants do not contain a known biochemical pathway to synthesize methane. However, under high UV stress conditions, there may be spontaneous breakdown of plant material, which releases methane. In addition, plants take up and transpire water containing dissolved methane, leading to the observation that methane is released. Together with a new analysis of global methane levels from satellite retrievals, we conclude that plants are not a major source of the global methane production. PMID:19141418

  12. 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.

  13. A modified version of the Molly rumen model to quantify methane emissions from sheep.

    PubMed

    Vetharaniam, I; Vibart, R E; Hanigan, M D; Janssen, P H; Tavendale, M H; Pacheco, D

    2015-07-01

    We modified the rumen submodel of the Molly dairy cow model to simulate the rumen of a sheep and predict its methane emissions. We introduced a rumen hydrogen (H) pool as a dynamic variable, which (together with the microbial pool in Molly) was used to predict methane production, to facilitate future consideration of thermodynamic control of methanogenesis. The new model corrected a misspecification of the equation of microbial H utilization in Molly95, which could potentially give rise to unrealistic predictions under conditions of low intake rates. The new model included a function to correct biases in the estimation of net H production based on the default stoichiometric relationships in Molly95, with this function specified in terms of level of intake. Model parameters for H and methane production were fitted to experimental data that included fresh temperate forages offered to sheep at a wide range of intake levels and then tested against independent data. The new model provided reasonable estimates relative to the calibration data set, but a different parameterization was needed to improve its predicted ability relative to the validation data set. Our results indicate that, although feedback inhibition on H production and methanogen activity increased with feeding level, other feedback effects that vary with diet composition need to be considered in future work on modeling rumen digestion in Molly. PMID:26440024

  14. A New IPCC Tier 4 Site-Specific Model for Landfill Methane Emissions Inclusive of Seasonal Methane Oxidation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This project was initiated in the U.S. by the California Energy Commission (CEC) in cooperation with the California Integrated Waste Management Board and the California Air Resources Board to develop improved methods for landfill methane emissions for the California greenhouse gas inventory. This 3-...

  15. Model estimates of climate controls on pan-Arctic wetland methane emissions

    NASA Astrophysics Data System (ADS)

    Chen, X.; Bohn, T. J.; Lettenmaier, D. P.

    2015-11-01

    Climate factors including soil temperature and moisture, incident solar radiation, and atmospheric carbon dioxide concentration are important environmental controls on methane (CH4) emissions from northern wetlands. We investigated the spatiotemporal distributions of the influence of these factors on northern high-latitude wetland CH4 emissions using an enhanced version of the Variable Infiltration Capacity (VIC) land surface model. We simulated CH4 emissions from wetlands across the pan-Arctic domain over the period 1948-2006, yielding annual average emissions of 36.1 ± 6.7 Tg CH4 yr-1 for the period 1997-2006. We characterized historical sensitivities of CH4 emissions to air temperature, precipitation, incident long- and shortwave radiation, and atmospheric [CO2] as a function of average summer air temperature and precipitation. Emissions from relatively warm and dry wetlands in the southern (permafrost-free) portion of the domain were positively correlated with precipitation and negatively correlated with air temperature, while emissions from wetter and colder wetlands further north (permafrost) were positively correlated with air temperature. Over the entire period 1948-2006, our reconstructed CH4 emissions increased by 20 %, the majority of which can be attributed to an increasing trend in summer air temperature. We estimated future emissions in response to 21st century warming as predicted by CMIP5 (Coupled Model Intercomparison Project Phase 5) model projections to result in end-of-century CH4 emissions 38-53 % higher than our reconstructed 1997-2006 emissions, accompanied by the northward migration of warmer and drier than optimal conditions for CH4 emissions, implying a reduced role for temperature in driving future increases in emissions.

  16. Future methane emissions from animals

    SciTech Connect

    Anastasi, C.; Simpson, V.J. )

    1993-04-20

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

  17. 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

  18. 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.

  19. Prediction of enteric methane emissions from cattle.

    PubMed

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

    2014-07-01

    Agriculture has a key role in food production worldwide and it is a major component of the gross domestic product of several countries. Livestock production is essential for the generation of high quality protein foods and the delivery of foods in regions where animal products are the main food source. Environmental impacts of livestock production have been examined for decades, but recently emission of methane from enteric fermentation has been targeted as a substantial greenhouse gas source. The quantification of methane emissions from livestock on a global scale relies on prediction models because measurements require specialized equipment and may be expensive. The predictive ability of current methane emission models remains poor. Moreover, the availability of information on livestock production systems has increased substantially over the years enabling the development of more detailed methane prediction models. In this study, we have developed and evaluated prediction models based on a large database of enteric methane emissions from North American dairy and beef cattle. Most probable models of various complexity levels were identified using a Bayesian model selection procedure and were fitted under a hierarchical setting. Energy intake, dietary fiber and lipid proportions, animal body weight and milk fat proportion were identified as key explanatory variables for predicting emissions. Models here developed substantially outperformed models currently used in national greenhouse gas inventories. Additionally, estimates of repeatability of methane emissions were lower than the ones from the literature and multicollinearity diagnostics suggested that prediction models are stable. In this context, we propose various enteric methane prediction models which require different levels of information availability and can be readily implemented in national greenhouse gas inventories of different complexity levels. The utilization of such models may reduce errors associated with prediction of methane and allow a better examination and representation of policies regulating emissions from cattle. PMID:24259373

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

    SciTech Connect

    Di Bella, Gaetano; Di Trapani, Daniele; Viviani, Gaspare

    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.

  1. Modelling the effects of genetic line and feeding system on methane emissions from dairy systems 

    E-print Network

    Bell, Matthew

    2011-06-28

    Dairy cattle make a significant contribution to global methane emissions. Milking cows in the UK make up about a fifth of the total cattle population, with Holstein-Friesian cows being the most common breed. Investigating ...

  2. 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.

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

    SciTech Connect

    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.

    2015-06-03

    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.

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

    DOE PAGESBeta

    Bohn, T. J.; Melton, J. R.; Ito, A.; Kleinen, T.; Spahni, R.; Stocker, B. D.; Zhang, B.; Zhu, X.; Schroeder, R.; Glagolev, M. V.; et al

    2015-06-03

    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.more »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.« less

  5. Mapping pan-Arctic methane emissions at high spatial resolution using an adjoint atmospheric transport and inversion method and process-based wetland and lake biogeochemical models

    NASA Astrophysics Data System (ADS)

    Tan, Z.; Zhuang, Q.; Henze, D. K.; Frankenberg, C.; Dlugokencky, E.; Sweeney, C.; Turner, A. J.

    2015-11-01

    Understanding methane emissions from the Arctic, a fast warming carbon reservoir, is important for projecting changes in the global methane cycle under future climate scenarios. Here we optimize Arctic methane emissions with a nested-grid high-resolution inverse model by assimilating both high-precision surface measurements and column-average SCIAMACHY satellite retrievals of methane mole fraction. For the first time, methane emissions from lakes are integrated into an atmospheric transport and inversion estimate, together with prior wetland emissions estimated by six different biogeochemical models. We find that, the global methane emissions during July 2004-June 2005 ranged from 496.4 to 511.5 Tg yr-1, with wetland methane emissions ranging from 130.0 to 203.3 Tg yr-1. The Arctic methane emissions during July 2004-June 2005 were in the range of 14.6-30.4 Tg yr-1, with wetland and lake emissions ranging from 8.8 to 20.4 Tg yr-1 and from 5.4 to 7.9 Tg yr-1 respectively. Canadian and Siberian lakes contributed most of the estimated lake emissions. Due to insufficient measurements in the region, Arctic methane emissions are less constrained in northern Russia than in Alaska, northern Canada and Scandinavia. Comparison of different inversions indicates that the distribution of global and Arctic methane emissions is sensitive to prior wetland emissions. Evaluation with independent datasets shows that the global and Arctic inversions improve estimates of methane mixing ratios in boundary layer and free troposphere. The high-resolution inversions provide more details about the spatial distribution of methane emissions in the Arctic.

  6. Mapping pan-Arctic methane emissions at high spatial resolution using an adjoint atmospheric transport and inversion method and process-based wetland and lake biogeochemical models

    DOE PAGESBeta

    Tan, Z.; Zhuang, Q.; Henze, D. K.; Frankenberg, C.; Dlugokencky, E.; Sweeney, C.; Turner, A. J.

    2015-11-18

    Understanding methane emissions from the Arctic, a fast warming carbon reservoir, is important for projecting changes in the global methane cycle under future climate scenarios. Here we optimize Arctic methane emissions with a nested-grid high-resolution inverse model by assimilating both high-precision surface measurements and column-average SCIAMACHY satellite retrievals of methane mole fraction. For the first time, methane emissions from lakes are integrated into an atmospheric transport and inversion estimate, together with prior wetland emissions estimated by six different biogeochemical models. We find that, the global methane emissions during July 2004–June 2005 ranged from 496.4 to 511.5 Tg yr?1, with wetlandmore »methane emissions ranging from 130.0 to 203.3 Tg yr?1. The Arctic methane emissions during July 2004–June 2005 were in the range of 14.6–30.4 Tg yr?1, with wetland and lake emissions ranging from 8.8 to 20.4 Tg yr?1 and from 5.4 to 7.9 Tg yr?1 respectively. Canadian and Siberian lakes contributed most of the estimated lake emissions. Due to insufficient measurements in the region, Arctic methane emissions are less constrained in northern Russia than in Alaska, northern Canada and Scandinavia. Comparison of different inversions indicates that the distribution of global and Arctic methane emissions is sensitive to prior wetland emissions. Evaluation with independent datasets shows that the global and Arctic inversions improve estimates of methane mixing ratios in boundary layer and free troposphere. The high-resolution inversions provide more details about the spatial distribution of methane emissions in the Arctic.« less

  7. 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.

  8. 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

  9. 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.

  10. Analyzing carbon dioxide and methane emissions in California using airborne measurements and model simulations

    NASA Astrophysics Data System (ADS)

    Johnson, M. S.; Yates, E. L.; Iraci, L. T.; Jeong, S.; Fischer, M. L.

    2013-12-01

    Greenhouse gas (GHG) concentrations have increased over the past decades and are linked to global temperature increases and climate change. These changes in climate have been suggested to have varying effects, and uncertain consequences, on agriculture, water supply, weather, sea-level rise, the economy, and energy. To counteract the trend of increasing atmospheric concentrations of GHGs, the state of California has passed the California Global Warming Act of 2006 (AB-32). This requires that by the year 2020, GHG (e.g., carbon dioxide (CO2) and methane (CH4)) emissions will be reduced to 1990 levels. To quantify GHG fluxes, emission inventories are routinely compiled for the State of California (e.g., CH4 emissions from the California Greenhouse Gas Emissions Measurement (CALGEM) Project). The major sources of CO2 and CH4 in the state of California are: transportation, electricity production, oil and gas extraction, cement plants, agriculture, landfills/waste, livestock, and wetlands. However, uncertainties remain in these emission inventories because many factors contributing to these processes are poorly quantified. To alleviate these uncertainties, a synergistic approach of applying air-borne measurements and chemical transport modeling (CTM) efforts to provide a method of quantifying local and regional GHG emissions will be performed during this study. Additionally, in order to further understand the temporal and spatial distributions of GHG fluxes in California and the impact these species have on regional climate, CTM simulations of daily variations and seasonality of total column CO2 and CH4 will be analyzed. To assess the magnitude and spatial variation of GHG emissions and to identify local 'hot spots', airborne measurements of CH4 and CO2 were made by the Alpha Jet Atmospheric eXperiment (AJAX) over the San Francisco Bay Area (SFBA) and San Joaquin Valley (SJV) in January and February 2013 during the Discover-AQ-CA study. High mixing ratios of GHGs were observed in-flight with a high degree of spatial variability. To provide an additional method to quantify GHG emissions, and analyze AJAX measurement data, the GEOS-Chem CTM is used to simulate SFBA/SJV GHG measurements. A nested-grid version of GEOS-Chem will be applied and utilizes varying emission inventories and model parameterizations to simulate GHG fluxes/emissions. The model considers CO2 fluxes from fossil fuel use, biomass/biofuel burning, terrestrial and oceanic biosphere exchanges, shipping and aviation, and production from the oxidation of carbon monoxide, CH4, and non-methane volatile organic carbons. The major sources of CH4 simulated in GEOS-Chem are domesticated animals, rice fields, natural gas leakage, natural gas venting/flaring (oil production), coal mining, wetlands, and biomass burning. Preliminary results from the comparison between available observations (e.g., AJAX and CALGEM CH4 emission maps) and GEOS-Chem results will be presented, along with a discussion of CO2 and CH4 source apportionment and the use of the GEOS-Chem-adjoint to perform inverse GHG modeling.

  11. 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 ...

  12. Integral emission factors for methane determined using urban flux measurements and local-scale inverse models

    NASA Astrophysics Data System (ADS)

    Christen, Andreas; Johnson, Mark; Molodovskaya, Marina; Ketler, Rick; Nesic, Zoran; Crawford, Ben; Giometto, Marco; van der Laan, Mike

    2013-04-01

    The most important long-lived greenhouse gas (LLGHG) emitted during combustion of fuels is carbon dioxide (CO2), however also traces of the LLGHGs methane (CH4) and nitrous oxide (N2O) are released, the quantities of which depend largely on the conditions of the combustion process. Emission factors determine the mass of LLGHGs emitted per energy used (or kilometre driven for cars) and are key inputs for bottom-up emission modelling. Emission factors for CH4 are typically determined in the laboratory or on a test stand for a given combustion system using a small number of samples (vehicles, furnaces), yet associated with larger uncertainties when scaled to entire fleets. We propose an alternative, different approach - Can integrated emission factors be independently determined using direct micrometeorological flux measurements over an urban surface? If so, do emission factors determined from flux measurements (top-down) agree with up-scaled emission factors of relevant combustion systems (heating, vehicles) in the source area of the flux measurement? Direct flux measurements of CH4 were carried out between February and May, 2012 over a relatively densely populated, urban surface in Vancouver, Canada by means of eddy covariance (EC). The EC-system consisted of an ultrasonic anemometer (CSAT-3, Campbell Scientific Inc.) and two open-path infrared gas analyzers (Li7500 and Li7700, Licor Inc.) on a tower at 30m above the surface. The source area of the EC system is characterised by a relative homogeneous morphometry (5.3m average building height), but spatially and temporally varying emission sources, including two major intersecting arterial roads (70.000 cars drive through the 50% source area per day) and seasonal heating in predominantly single-family houses (natural gas). An inverse dispersion model (turbulent source area model), validated against large eddy simulations (LES) of the urban roughness sublayer, allows the determination of the spatial area that contributes to each measurement interval (30 min), which varies with wind direction and stability. A detailed geographic information system of the urban surface combined with traffic counts and building energy models makes it possible to statistically relate fluxes to vehicle density (km driven) and buildings (gas heated volume) - and ultimately quantify the contribution of space heating, transport sector and fugitive emissions to the total emitted CH4 from an urban environment. The measured fluxes of CH4 over the selected urban environment averaged to 22.8 mg CH4 m-2 day-1 during the study period. Compared with the simultaneously measured CO2 emissions, the contribution of CH4, however, accounts for only about 3% of the total LLGHG emissions from this particular urban surface. Traffic contributed 8.8 mg CH4 m-2 day-1, equivalent to 39% of the total CH4 flux. The determined emission factor for the typical fleet composition is 0.062 g CH4 per km driven which is higher than upscaled fleet emission factors (EPA) by a factor of two. This discrepancy can be partially explained through the slower city traffic with frequent idling (traffic congestion), fleet composition and cold starts. Emissions of CH4 by domestic space heating (55% of the total CH4 flux or 12.7 mg CH4 m-2 day-1) are also higher than estimated from upscaled emission factors. There is no evidence of substantial unknown sources such as soil processes, combustion of wood, and leakages from gas distribution pipes (residual: 6% or 1.3 mg CH4 m-2 day-1). The presented study is among the first direct measurements of CH4 emissions over an urban surface and demonstrates that flux measurements of greenhouse gases can be used to determine sources and emission factors in complex urban situations.

  13. Development of an empirical model of methane emissions from landfills. Final report Mar-Dec 91

    SciTech Connect

    Peer, R.L.; Epperson, D.L.; Campbell, D.L.; von Brook, P.

    1992-03-01

    The report gives results of a field study of 21 U.S. landfills with gas recovery systems, to gather information that can be used to develop an empirical model of methane (CH4) emissions. Site-specific information includes average CH4 recovery rate, landfill size, tons of refuse (refuse mass), average age of the refuse, and climate. A correlation analysis showed that refuse mass was positively linearly correlated with landfill depth, volume, area, and well depth. Regression of the CH4 recovery rate on depth, refuse mass, and volume was significant, but depth was the best predictive variable (R2 = 0.53). Refuse mass was nearly as good (R2 = 0.50). None of the climate variables (precipitation, average temperature, dewpoint) were correlated with the CH4 recovery rate or with CH4 recovery per metric ton of refuse. Much of the variability in CH4 recovery remains unexplained, and is likely due to between-site differences in landfill construction, operation, and refuse composition. A model for global landfill emissions estimation is proposed.

  14. Modeling the influence of methane emissions from arctic gas hydrates on regional variations in composition of the lower atmosphere

    NASA Astrophysics Data System (ADS)

    Smyshlyaev, S. P.; Mareev, E. A.; Galin, V. Ya.; Blakitnaya, P. A.

    2015-07-01

    Numerical simulation with the use of the global chemistry-climate model of the lower and middle atmosphere has shown that the contribution of methane emissions from Arctic gas hydrates to the global production is most likely underestimated. An increase in methane emission as a result of Arctic warming may lead to a decrease in hydroxyl content and the formation of positive reverse correlation with CH4 content in emission area. The zones of variation in ozone content are distinct from those of the increase in CH4 content; the increase in ozone content with an increase in CH4 content is nonlinear and is retarded at high values of CH4 fluxes. This may be related to the decrease in hydroxyl content at an increase in CH4 emissions and reverse correlations, which compensate the additional ozone production.

  15. Effect of high-sugar grasses on methane emissions simulated using a dynamic model.

    PubMed

    Ellis, J L; Dijkstra, J; France, J; Parsons, A J; Edwards, G R; Rasmussen, S; Kebreab, E; Bannink, A

    2012-01-01

    High-sugar grass varieties have received considerable attention for their potential ability to decrease N excretion in cattle. However, feeding high-sugar grasses alters the pattern of rumen fermentation, and no in vivo studies to date have examined this strategy with respect to another environmental pollutant: methane (CH(4)). Modeling allows us to examine potential outcomes of feeding strategies under controlled conditions, and can provide a useful framework for the development of future experiments. The purpose of the present study was to use a modeling approach to evaluate the effect of high-sugar grasses on simulated CH(4) emissions in dairy cattle. An extant dynamic, mechanistic model of enteric fermentation and intestinal digestion was used for this evaluation. A simulation database was constructed and analysis of model behavior was undertaken to simulate the effect of (1) level of water-soluble carbohydrate (WSC) increase in dietary dry matter, (2) change in crude protein (CP) and neutral detergent fiber (NDF) content of the plant with an increased WSC content, (3) level of N fertilization, and (4) presence or absence of grain feeding. Simulated CH(4) emissions tended to increase with increased WSC content when CH(4) was expressed as megajoules per day or percent of gross energy intake, but when CH(4) was expressed in terms of grams per kilogram of milk, results were much more variable due to the potential increase in milk yield. As a result, under certain conditions, CH(4) (g/kg of milk) decreased. The largest increases in CH(4) emissions (MJ/d or % gross energy intake) were generally seen when WSC increased at the expense of CP in the diet and this can largely be explained by the representation in the model of the type of volatile fatty acid produced. Effects were lower when WSC increased at the expense of NDF, and intermediary when WSC increased at the expense of a mixture of CP and NDF. When WSC increased at the expense of NDF, simulated milk yield increased and, therefore, CH(4) (g/kg of milk) tended to decrease. Diminished increases of CH(4) (% gross energy intake or g/kg of milk) were simulated when DMI was increased with elevated WSC content. Simulation results suggest that high WSC grass, as a strategy to mitigate N emission, may increase CH(4) emissions, but that results depend on the grass composition, DMI, and the units chosen to express CH(4). Overall, this project demonstrates the usefulness of modeling for hypothesis testing in the absence of observed experimental results. PMID:22192207

  16. Observational Constraints on Changing Arctic Methane Emissions

    NASA Astrophysics Data System (ADS)

    Dlugokencky, E. J.; Bruhwiler, L.; Lang, P. M.; Masarie, K.; Crotwell, A. M.; Crotwell, M.; Lowry, D.; Fisher, R. E.; Nisbet, E. G.

    2012-12-01

    Methane (CH4) is the second-most important greenhouse gas influenced by human activities. Its chemistry results in additional indirect climate effects from production of tropospheric O3, which also affects air quality, and stratospheric H2O. Because methane's atmospheric lifetime is relatively short (~9 yr) and ~70% of its emissions are anthropogenic, reductions in its emissions provide a potential cost-effective opportunity to slow the rate of increase of radiative forcing. Some fraction of decreased anthropogenic emissions may be canceled by potentially strong feed-backs to natural emissions. Because natural emissions of CH4 are diffuse, relatively weak, and highly-variable in space and time, quantifying changes for large spatial regions is difficult from small-scale field studies alone. Atmosphere observations at well-chosen sites integrate these emissions over large zonal regions and can be particularly useful for detecting changes in emissions. Paleo-climate studies indicate that CH4 emissions from Arctic wetlands are sensitive to climate and may provide a strong positive feedback as the Arctic warms. Measurements of atmospheric CH4 from the NOAA Global Monitoring Division's, Global Cooperative Air Sampling Network began in 1983. These high-precision observations offer key constraints on changes in Arctic CH4 emissions. During 2007, the CH4 growth rate increased in the Arctic, but was nearly zero during 2008. Use of the data in a chemical transport model suggest anomalous emissions of about 2 Tg CH4 during 2007, but returning to long-term average emissions after that. Another potential source affected by climate is emissions from methane clathrates. Measurements of methane's isotopic composition in the Arctic have been useful in showing that CH4 enhancements in Arctic air result from wetlands, not clathrates. Both potential sources are also constrained by spatial patterns in observed CH4, which indicate that, so far, changes in emissions of Arctic CH4 over the past 2 decades are less than ~2 Tg CH4 yr-1.

  17. Methane Emission from Tropical Rivers

    NASA Astrophysics Data System (ADS)

    Sawakuchi, H. O.; Rasera, M. F. F. L.; Krusche, A. V.; Ballester, M. V. R.

    2012-04-01

    Inland water is already known as an important source of methane to atmosphere. Methane is produced in anaerobic environments usually find in lakes and floodplain bottom sediment. It is the main reason that almost all information regarding methane flux come from this environments. However, while floodplain dries during low water season reducing methanogenesis, rivers keep the capacity to emit methane throughout the year. Here we present preliminary results of CH4 flux measurements done in 6 large tropical rivers within the Amazon basin. We measured 17 areas using floating chamber during dry (low water) season, between September and November of 2011, in Amazon river mainstem, Araguaia, Xingu, Tapajós, Madeira, and Negro Rivers. Measured fluxes of all rivers ranged from 59.3 to 2974.4 mmol m-2 yr-1. Geomorphologic structure of channels is one important factor that contributes to this high heterogeneity due to development of low flow velocity depositional settings allowing formation of anoxic zones in rivers. Hydraulic and sediment barriers in the confluence of river channels promote the generation of natural dams which function as a trap for the suspension load favoring the deposition of organic rich muds. This kind of environment is very different from common river channels and has a stronger potential of methane emission. Average values of our flux measurements for this two river environments show that depositional areas can have much higher fluxes than the main channel, 1089.6 and 163.1 mmol m-2 yr-1, respectively. Hence, CH4 flux from these depositional zones is similar to some tropical floodplain lakes and reservoirs. Although the low flux from channel, the area covered by water is very large resulting in a significant contribution to the regional methane emission to the atmosphere. Moreover, mapping the area of these depositional river zones will give us a better idea of the magnitude of methane flux from tropical rivers.

  18. Integrated Modeling & Development of Emission Scenarios for Methane and Key Indirect Greenhouse Gases

    SciTech Connect

    Jain, Atul K.

    2005-09-30

    This report outlines main accomplishments on the development of Emission inventories and Scenarios for Key Indirect Greenhouse Gases (CO, VOCs, NOx) and methane supported by Office of Science (BER), US Department of Energy. This research produced 3 journal articles, 1 book chapter, and 4 research articles/abstracts in conference proceedings. In addition, this grant supported two PhD students and one undergraduate student at UIUC.

  19. Engineering estimate of the incremental change in methane emissions with increasing throughput in a model natural gas system. Final report, October 1991-March 1994

    SciTech Connect

    Eberle, A.C.

    1994-03-01

    The purpose of this engineering study is to estimate the incremental change in methane emissions with increasing customer demand from a model natural gas system. The model natural gas system has been designed to be representative of the U.S. natural gas grid as a whole. Component and operating changes to the model system were engineered to accomodate increased customer demand and estimates were made of the incremental changes in methane emissions resulting from the changes.

  20. 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.

    2014-07-01

    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 data set than any other model: (1) inclusion of an improved hydrological module, (2) incorporation of a gross primary productivity (GPP) module, and (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; the former is also sensitive to the runoff threshold and open water correction factor, and the latter to the subsurface water evaporation and evapotranspiration correction factors. 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.

  1. 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.

  2. 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.

  3. Climatic and Chemical Controls on Methane Emissions from Wetlands

    NASA Technical Reports Server (NTRS)

    Matthews, Elaine; Gauci, Vincent; Prigent, Catherine; Travis, Larry (Technical Monitor)

    2002-01-01

    Natural wetlands are the largest single source of methane to the atmosphere and the only one dominated by climate. Although interannual variations in methane emissions from short-term climate variations are becoming better understood, major uncertainties remain with respect to the sensitivity of wetlands and their CH4 emissions to climate variability, the sensitivity of suppression of wetland methane missions to changes in low-dose sulfate deposition, and the response of wetland dynamics to climate variations. We present results from modeling, field, and remote sensing research that integrate current understanding of the dynamics of wetlands and their methane emissions.

  4. Estimating Emissions of Ammonia and Methane from an Anaerobic Livestock Lagoon Using Micrometeorological Methods and Inverse Modeling

    NASA Astrophysics Data System (ADS)

    Shonkwiler, K. B.; Ham, J. M.; Williams, C.

    2012-12-01

    Evaluating the impact of increased carbon and nitrogen emissions on local air quality and regional bionetworks due to animal agricultural activity is of great interest to the public, political, economic and ecological welfare of areas within the scope of these practices. Globally, livestock operations account for 64% of annual anthropogenic emissions of ammonia (NH3) [1]. Concerning methane (CH4), anaerobic lagoons from commercial dairy operations contribute the second largest share of CH4 emissions from manure in the United States[1], and additionally are a local source of NH3 as well. Anaerobic lagoons are commonly used in commercial animal agriculture and as significant local sources of greenhouse gases (GHG), there is a strong need to quantify GHG emissions from these systems. In 2012 at a commercial dairy operation in Northern Colorado, USA, measurements of CH4 were made using eddy covariance (EC), while NH3 was estimated using a combination of real-time monitoring (cavity ring-down spectroscopy as well as time-integrated passive samplers). Methane emissions have been measured at this lagoon using EC since 2011, with fluxes ranging from 0.5 mg m-2 s-1 in early summer to >2 mg m-2 s-1 in late summer and early fall. Concentration data of both CH4 and NH3 were used to estimate emissions using a 2-dimensional inverse model based on solving the advection-diffusion equation[2]. In the case of the CH4-EC data, results from the inverse model were compared with the EC-derived flux estimates for enhanced parameterization of surface geometry within the lagoon environment. The model was then applied using measured NH3 concentrations to achieve emissions estimates. While NH3 fluxes from the lagoon tend to be much lower than those of CH4 by comparison, modeling emissions of NH3 from the simple geometry of a lagoon will assist in applying the model to more complex surfaces. [1] FAO, 2006. Livestock's long shadow: Environmental issues and options. Livestock, Environment, and Development Initiative. Food and Agriculture Organization of the United Nations, Rome, Italy. [2] Loubet, B., Génermont, S., Ferrara, R., Bedos, C., Decuq, C., Personne, E., Fanucci, O., Durand, B., Rana, G., Cellier, P., 2010. An inverse model to estimate ammonia emissions from fields. Eur. J. Soil Sci. 61: 793-805. Panorama of a weather station (left) utilizing micrometeorological methods to aid in estimating emissions of methane and ammonia from an anaerobic livestock lagoon (center) at a commercial dairy in Northern Colorado, USA.

  5. Measuring and modeling nitrous oxide and methane emissions from beef cattle feedlot manure management: First assessments under Brazilian condition.

    PubMed

    Costa, Ciniro; Li, Changsheng; Cerri, Carlos E P; Cerri, Carlos C

    2014-01-01

    Intensive beef production has increased during recent decades in Brazil and may substantially increase both methane (CH(4)) and nitrous oxide (N(2)O) emissions from manure management. However, the quantification of these gases and methods for extrapolating them are scarce in Brazil. A case study examines CH(4) and N(2)O emissions from one typical beef cattle feedlot manure management continuum in Brazil and the applicability of Manure-DNDC model in predicting these emissions for better understand fluxes and mitigation options. Measurements track CH(4) and N(2)O emissions from manure excreted in one housing floor holding 21 animals for 78 days, stockpiled for 73 days and field spread (360 kg N ha(-1)). We found total emissions (CH(4) + N(2)O) of 0.19 ± 0.10 kg CO(2)eq per kg of animal live weight gain; mostly coming from field application (73%), followed housing (25%) and storage (2%). The Manure-DNDC simulations were generally within the statistical deviation ranges of the field data, differing in -28% in total emission. Large uncertainties in measurements showed the model was more accurate estimating the magnitude of gases emissions than replicate results at daily basis. Modeled results suggested increasing the frequency of manure removal from housing, splitting the field application and adopting no-tillage system is the most efficient management for reducing emissions from manure (up to about 75%). Since this work consists in the first assessment under Brazilian conditions, more and continuous field measurements are required for decreasing uncertainties and improving model validations. However, this paper reports promising results and scientific perceptions for the design of further integrated work on farm-scale measurements and Manure-DNDC model development for Brazilian conditions. PMID:25035919

  6. 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

  7. 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...

  8. Methane emissions from natural wetlands

    SciTech Connect

    Meyer, J.L.; Burke, R.A. Jr.

    1993-09-01

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

  9. Top-down estimate of methane emissions in California using a mesoscale inverse modeling technique: The South Coast Air Basin

    NASA Astrophysics Data System (ADS)

    Cui, Yu Yan; Brioude, Jerome; McKeen, Stuart A.; Angevine, Wayne M.; Kim, Si-Wan; Frost, Gregory J.; Ahmadov, Ravan; Peischl, Jeff; Bousserez, Nicolas; Liu, Zhen; Ryerson, Thomas B.; Wofsy, Steve C.; Santoni, Gregory W.; Kort, Eric A.; Fischer, Marc L.; Trainer, Michael

    2015-07-01

    Methane (CH4) is the primary component of natural gas and has a larger global warming potential than CO2. Recent top-down studies based on observations showed CH4 emissions in California's South Coast Air Basin (SoCAB) were greater than those expected from population-apportioned bottom-up state inventories. In this study, we quantify CH4 emissions with an advanced mesoscale inverse modeling system at a resolution of 8 km × 8 km, using aircraft measurements in the SoCAB during the 2010 Nexus of Air Quality and Climate Change campaign to constrain the inversion. To simulate atmospheric transport, we use the FLEXible PARTicle-Weather Research and Forecasting (FLEXPART-WRF) Lagrangian particle dispersion model driven by three configurations of the Weather Research and Forecasting (WRF) mesoscale model. We determine surface fluxes of CH4 using a Bayesian least squares method in a four-dimensional inversion. Simulated CH4 concentrations with the posterior emission inventory achieve much better correlations with the measurements (R2 = 0.7) than using the prior inventory (U.S. Environmental Protection Agency's National Emission Inventory 2005, R2 = 0.5). The emission estimates for CH4 in the posterior, 46.3 ± 9.2 Mg CH4/h, are consistent with published observation-based estimates. Changes in the spatial distribution of CH4 emissions in the SoCAB between the prior and posterior inventories are discussed. Missing or underestimated emissions from dairies, the oil/gas system, and landfills in the SoCAB seem to explain the differences between the prior and posterior inventories. We estimate that dairies contributed 5.9 ± 1.7 Mg CH4/h and the two sectors of oil and gas industries (production and downstream) and landfills together contributed 39.6 ± 8.1 Mg CH4/h in the SoCAB.

  10. ESTIMATION OF METHANE EMISSIONS FROM A SURFACE COAL MINE USING OPEN-PATH FTIR SPECTROSCOPY AND MODELING TECHNIQUES

    EPA Science Inventory

    A new measurements methodology has been developed which allows the rapid and efficient measurement of methane (CH4) emissions from surface coal mines. An initial field trial of this methodology has been completed, and results from the field trial revealed that emissions from one ...

  11. Estimation of country-scale methane emissions by airborne and ground-based in situ observations and inverse modeling

    NASA Astrophysics Data System (ADS)

    Brunner, D.; Henne, S.; Oney, B. J.; Leuenberger, M.; Hiller, R.; Bamberger, I.; Eugster, W.; Neininger, B.

    2014-12-01

    Methane (CH4) is the second most important long-lived greenhouse gas from both natural and anthropogenic sources. In Switzerland, CH4 sources are dominated by agricultural activities (>80%) while natural emissions from wetlands and wild animals are thought to represent a minor source (~3 %). Except for leakage from the natural gas distribution network, all relevant emissions in Switzerland are associated with microbial processes which, due to their diffuse nature and sensitivity to ambient conditions, are associated with comparatively large uncertainties. The Swiss National Greenhouse Gas Inventory, for example, assigns an uncertainty of 18% to the country total CH4 emissions as compared to only 3% for CO2. To verify the Swiss national CH4 emission estimate and to reduce its uncertainty, "top-down" methods combining atmospheric observations and regional scale transport simulations can be used. Here, we present two independent analyses of the Swiss CH4 emission budget using inverse modeling. The first is based on airborne observations during more than 20 flights of a motor glider conducted in the framework of the MAIOLICA project. The second is based on near surface measurements from the newly established CarboCount CH measurement network (http://www.carbocount.ch). A Bayesian inversion framework is applied to these observations in combination with source sensitivities (footprints) calculated with the Lagrangian Particle Dispersion Model FLEXPART. To account for the complex terrain and flow in Switzerland, FLEXPART is driven by meteorological fields from the non-hydrostatic numerical weather forecast model COSMO at horizontal resolutions of up to 2 km x 2 km. Due to the critical role of the transport simulations, we first present an analysis of the sensitivity to different model configurations (e.g. resolution, time-averaged winds versus instantaneous fields, ECMWF versus COSMO fields). We then present the inverse modeling results separately for the airborne and the ground-based observations contrasting the numbers to the official National Greenhouse Gas Inventory.

  12. Global methane emissions from pit latrines.

    PubMed

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

    2014-01-01

    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

  13. An ecological perspective on methane emissions from northern wetlands.

    PubMed

    Bubier, J L; Moore, T R

    1994-12-01

    Wetlands are significant sources of atmospheric methane, an important radiatively active 'greenhouse' gas that accounts for an estimated 12% of total greenhouse warming. Since global climate models predict the greatest temperature and precipitation changes at high latitudes, and as the largest areas of wetland (346 × 10(6)ha) are in the boreal and subarctic regions (40-70°N), recent research has focused on Identifying the factors that control methane emission from northern wetlands. Over the past few years, the database has expanded tremendously, and much progress has been made in understanding the environmental controls on methane emission at small spatial and temporal scales. However, we now need to broaden our understanding of regional differences in methane emission, ecological responses of northern wetlands to climate change, and the effect of other perturbations such as drainage and flooding. PMID:21236923

  14. Measurement and prediction of enteric methane emission.

    PubMed

    Sejian, Veerasamy; Lal, Rattan; Lakritz, Jeffrey; Ezeji, Thaddeus

    2011-01-01

    The greenhouse gas (GHG) emissions from the agricultural sector account for about 25.5% of total global anthropogenic emission. While CO(2) receives the most attention as a factor relative to global warming, CH(4), N(2)O and chlorofluorocarbons (CFCs) also cause significant radiative forcing. With the relative global warming potential of 25 compared with CO(2), CH(4) is one of the most important GHGs. This article reviews the prediction models, estimation methodology and strategies for reducing enteric CH(4) emissions. Emission of CH(4) in ruminants differs among developed and developing countries, depending on factors like animal species, breed, pH of rumen fluid, ratio of acetate:propionate, methanogen population, composition of diet and amount of concentrate fed. Among the ruminant animals, cattle contribute the most towards the greenhouse effect through methane emission followed by sheep, goats and buffalos, respectively. The estimated CH(4) emission rate per cattle, buffaloe, sheep and goat in developed countries are 150.7, 137, 21.9 and 13.7 (g/animal/day) respectively. However, the estimated rates in developing countries are significantly lower at 95.9 and 13.7 (g/animal/day) per cattle and sheep, respectively. There exists a strong interest in developing new and improving the existing CH(4) prediction models to identify mitigation strategies for reducing the overall CH(4) emissions. A synthesis of the available literature suggests that the mechanistic models are superior to empirical models in accurately predicting the CH(4) emission from dairy farms. The latest development in prediction model is the integrated farm system model which is a process-based whole-farm simulation technique. Several techniques are used to quantify enteric CH(4) emissions starting from whole animal chambers to sulfur hexafluoride (SF6) tracer techniques. The latest technology developed to estimate CH(4) more accurately is the micrometeorological mass difference technique. Because the conditions under which animals are managed vary greatly by country, CH(4) emissions reduction strategies must be tailored to country-specific circumstances. Strategies that are cost effective, improve productivity, and have limited potential negative effects on livestock production hold a greater chance of being adopted by producers. It is also important to evaluate CH(4) mitigation strategies in terms of the total GHG budget and to consider the economics of various strategies. Although reductions in GHG emissions from livestock industries are seen as high priorities, strategies for reducing emissions should not reduce the economic viability of enterprises. PMID:20809221

  15. Measurement and prediction of enteric methane emission

    NASA Astrophysics Data System (ADS)

    Sejian, Veerasamy; Lal, Rattan; Lakritz, Jeffrey; Ezeji, Thaddeus

    2011-01-01

    The greenhouse gas (GHG) emissions from the agricultural sector account for about 25.5% of total global anthropogenic emission. 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 compared with CO2, CH4 is one of the most important GHGs. This article reviews the prediction models, estimation methodology and strategies for reducing enteric CH4 emissions. Emission of CH4 in ruminants differs among developed and developing countries, depending on factors like animal species, breed, pH of rumen fluid, ratio of acetate:propionate, methanogen population, composition of diet and amount of concentrate fed. Among the ruminant animals, cattle contribute the most towards the greenhouse effect through methane emission followed by sheep, goats and buffalos, respectively. The estimated CH4 emission rate per cattle, buffaloe, sheep and goat in developed countries are 150.7, 137, 21.9 and 13.7 (g/animal/day) respectively. However, the estimated rates in developing countries are significantly lower at 95.9 and 13.7 (g/animal/day) per cattle and sheep, respectively. There exists a strong interest in developing new and improving the existing CH4 prediction models to identify mitigation strategies for reducing the overall CH4 emissions. A synthesis of the available literature suggests that the mechanistic models are superior to empirical models in accurately predicting the CH4 emission from dairy farms. The latest development in prediction model is the integrated farm system model which is a process-based whole-farm simulation technique. Several techniques are used to quantify enteric CH4 emissions starting from whole animal chambers to sulfur hexafluoride (SF6) tracer techniques. The latest technology developed to estimate CH4 more accurately is the micrometeorological mass difference technique. Because the conditions under which animals are managed vary greatly by country, CH4 emissions reduction strategies must be tailored to country-specific circumstances. Strategies that are cost effective, improve productivity, and have limited potential negative effects on livestock production hold a greater chance of being adopted by producers. It is also important to evaluate CH4 mitigation strategies in terms of the total GHG budget and to consider the economics of various strategies. Although reductions in GHG emissions from livestock industries are seen as high priorities, strategies for reducing emissions should not reduce the economic viability of enterprises.

  16. Pasture-scale measurement of methane emissions of grazing cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantifying methane emission of cattle grazing on southern Great Plains pastures using micrometeorology presents several challenges. Cattle are elevated, mobile point sources of methane, so that knowing their location in relation to atmospheric methane concentration measurements becomes critical. St...

  17. 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...

  18. Tree-mediated methane emissions from tropical and temperate peatlands.

    NASA Astrophysics Data System (ADS)

    Pangala, S. R.; Gauci, V.; Hornibrook, E. R. C.; Gowing, D. J.

    2012-04-01

    Methane production and transport processes in peatlands are fairly well understood, but growing evidence for emission of methane through trees has highlighted the need to revisit methane transport processes. In wetland trees, morphological adaptations such as development of hypertrophied lenticels, aerenchyma and adventitious roots in response to soil anoxia mediates gas transport, transporting both oxygen from the atmosphere to oxygen-deprived roots and soil-produced methane from the root-zone to the atmosphere. Although, tree-mediated methane emissions from temperate tree species have been confirmed, methane emissions from tropical tree species and processes that control tree-mediated methane emissions remain unclear. This study explains the role of trees in transporting soil-produced methane to the atmosphere and uncovers the principal mechanisms of tree-mediated methane emissions. Methane emissions from eight tropical tree species and two temperate tree species were studied in situ. The mechanisms and controls on tree-mediated methane emissions were investigated using three year old common alder (Alnus glutinosa; 50 trees) grown under two artificially controlled water-table positions. Methane fluxes from whole mesocosms, the soil surface and tree stems were measured using static closed chambers. Both temperate and tropical tree species released significant quantities of methane, with tropical trees dominating ecosystem level methane fluxes. In temperate peatlands, both the methane gas transport mechanism and quantity of methane emitted from stems is tree-species dependent. In Alnus glutinosa, no correlations were observed between stomatal behaviour and tree-mediated methane emissions, however, stem methane emissions were positively correlated with both stem lenticel density and dissolved soil methane concentration. In Alnus glutinosa, no emissions were observed from leaf surfaces. The results demonstrate that exclusion of tree-mediated methane emissions from flux measurement campaigns in forested peatlands will lead to an underestimation of ecosystem-wide methane emissions.

  19. 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

  20. Geologic emissions of methane to the atmosphere.

    PubMed

    Etiope, Giuseppe; Klusman, Ronald W

    2002-12-01

    The atmospheric methane budget is commonly defined assuming that major sources derive from the biosphere (wetlands, rice paddies, animals, termites) and that fossil, radiocarbon-free CH4 emission is due to and mediated by anthropogenic activity (natural gas production and distribution, and coal mining). However, the amount of radiocarbon-free CH4 in the atmosphere, estimated at approximately 20% of atmospheric CH4, is higher than the estimates from statistical data of CH4 emission from fossil fuel related anthropogenic sources. This work documents that significant amounts of "old" methane, produced within the Earth crust, can be released naturally into the atmosphere through gas permeable faults and fractured rocks. Major geologic emissions of methane are related to hydrocarbon production in sedimentary basins (biogenic and thermogenic methane) and, subordinately, to inorganic reactions (Fischer-Tropsch type) in geothermal systems. Geologic CH4 emissions include diffuse fluxes over wide areas, or microseepage, on the order of 10(0)-10(2) mg m(-2) day(-1), and localised flows and gas vents, on the order of 10(2) t y(-1), both on land and on the seafloor. Mud volcanoes producing flows of up to 10(3) t y(-1) represent the largest visible expression of geologic methane emission. Several studies have indicated that methanotrophic consumption in soil may be insufficient to consume all leaking geologic CH4 and positive fluxes into the atmosphere can take place in dry or seasonally cold environments. Unsaturated soils have generally been considered a major sink for atmospheric methane, and never a continuous, intermittent, or localised source to the atmosphere. Although geologic CH4 sources need to be quantified more accurately, a preliminary global estimate indicates that there are likely more than enough sources to provide the amount of methane required to account for the suspected missing source of fossil CH4. PMID:12430657

  1. Future methane emissions from animals

    NASA Astrophysics Data System (ADS)

    Anastasi, C.; Simpson, V. J.

    1993-04-01

    The future global emission of CH4 from enteric fermentation in animals has been estimated for cattle, sheep, and buffalo, which together contribute approximately 91% of the total CH4 emitted from domesticated animals at present. A simple model has been used to relate livestock levels to the national human populations for each country involved in breeding the three species included in this analysis. United Nations population predictions to 2025 were then included in the model to estimate future CH4 emissions. A variational analysis was carried out to investigate the effect of future changes in both the land available for grazing and the nutritional content of feedstocks. Results suggest that the total emission of CH4 from enteric fermentation in domestic animals will increase from 84 Tg CH4 per year (Tg = 1012 g) in 1990 to 119 (±12) Tg CH4 yr-1 by 2025. These values correspond to an average rate of increase over the next 35 years of 1.0 Tg CH4 yr-1.

  2. 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

  3. 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.

  4. 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 ...

  5. Higher Methane Emissions in Regions of Sea Ice Retreat

    NASA Astrophysics Data System (ADS)

    Parmentier, Frans-Jan W.; Zhang, Wenxin; Mi, Yanjiao; Zhu, Xudong; Miller, Paul A.; van Huissteden, Ko; Hayes, Dan; Zhuang, Qianlai; David. McGuire, A.; Christensen, Torben R.

    2014-05-01

    In recent decades, the Arctic has lost more and more sea ice, which has concurrently led to higher temperatures across the high latitudes (Screen et al., 2012). 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 clear. Recently, however, it has been suggested that methane emissions have increased while sea ice declined (Parmentier et al., 2013). This initial analysis compared average methane emissions for the Arctic Region with anomalies in the average sea ice extent, which evens out regional differences. Year-to-year variations in sea ice extent are different from region to region and would therefore impact methane emissions - through temperature - differently, too. Our goal is therefore to evaluate, with the use of models, whether methane emissions are more strongly correlated to sea ice in areas of high retreat rather than in areas that have seen little variation in sea ice. For this use, the output from three regional methane models (LPJ-GUESS WhyMe, Peatland-VU and TEM6), designed to be applied to the Arctic Region, are compared to sea ice decline. A similar spatial response to sea ice retreat by these models will increase our confidence that methane emissions in the Arctic are indeed spatially linked to sea ice decline. 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 Screen, J. A., Deser, C., & Simmonds, I. (2012). Local and remote controls on observed Arctic warming. Geophysical Research Letters, 39, L10709. doi:10.1029/2012GL051598

  6. 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...

  7. ESTIMATE OF METHANE EMISSIONS FROM U.S. LANDFILLS

    EPA Science Inventory

    The report describes the development of a statistical regression model used for estimating methane (CH4) emissions, which relates landfill gas (LFG) flow rates to waste-in-place data from 105 landfills with LFG recovery projects. (NOTE: CH4 flow rates from landfills with LFG reco...

  8. 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

  9. Timelines for mitigating methane emissions from energy technologies

    E-print Network

    Roy, Mandira; Trancik, Jessika E

    2015-01-01

    Energy technologies emitting differing proportions of methane and carbon dioxide vary in their relative climate impacts over time, due to the different atmospheric lifetimes of the two gases. Standard technology comparisons using the global warming potential (GWP) emissions equivalency metric do not reveal these dynamic impacts, and may not provide the information needed to assess technologies and emissions mitigation opportunities in the context of broader climate policy goals. Here we formulate a portfolio optimization model that incorporates changes in technology impacts as a radiative forcing (RF) stabilization target is approached. An optimal portfolio, maximizing allowed energy consumption while meeting the RF target, is obtained by year-wise minimization of the marginal RF impact in an intended stabilization year. The optimal portfolio calls for using certain higher methane-emitting technologies prior to an optimal switching year, followed by methane-light technologies as the stabilization year approac...

  10. Transcontinental Surface Validation of Satellite Observations of Enhanced Methane Anomalies Associated with Fossil Fuel Industrial Methane Emissions

    NASA Astrophysics Data System (ADS)

    Leifer, I.; Culling, D.; Schneising, O.; Bovensmann, H.; Buchwitz, M.; Burrows, J. P.

    2012-12-01

    A ground-based, transcontinental (Florida to California - i.e., satellite-scale) survey was conducted to understand better the role of fossil fuel industrial (FFI) fugitive emissions of the potent greenhouse gas, methane. Data were collected by flame ion detection gas chromatography (Fall 2010) and by a cavity ring-down sensor (Winter 2012) from a nearly continuously moving recreational vehicle, allowing 24/7 data collection. Nocturnal methane measurements for similar sources tended to be higher compared to daytime values, sometime significantly, due to day/night meteorological differences. Data revealed strong and persistent FFI methane sources associated with refining, a presumed major pipeline leak, and several minor pipeline leaks, a coal loading plant, and areas of active petroleum production. Data showed FFI source emissions were highly transient and heterogeneous; however, integrated over these large-scale facilities, methane signatures overwhelmed that of other sources, creating clearly identifiable plumes that were well elevated above ambient. The highest methane concentration recorded was 39 ppm at an active central valley California production field, while desert values were as low as 1.80 ppm. Surface methane data show similar trends with strong emissions correlated with FFI on large (4° bin) scales and positive methane anomalies centered on the Gulf Coast area of Houston, home to most of US refining capacity. Comparison with SCIAMACHY and GOSAT satellite data show agreement with surface data in the large-scale methane spatial patterns. Positive satellite methane anomalies in the southeast and Mexico largely correlated with methane anthropogenic and wetland inventory models suggests most strong ground methane anomalies in the Gulf of Mexico region were related to dominant FFI input for most seasons. Wind advection played a role, in some cases confounding a clear relationship. Results are consistent with a non-negligible underestimation of the FFI contribution to global methane budgets.; In situ methane concentrations during transcontinental survey Fall 2010.

  11. Impact of Changes in Barometric Pressure on Landfill Methane Emission

    NASA Astrophysics Data System (ADS)

    McDermitt, Dayle; Xu, Liukang; Lin, Xiaomao; Amen, Jim; Welding, Karla

    2013-04-01

    Landfill methane emissions were measured continuously using the eddy covariance method from June to December 2010. The study site was located at the Bluff Road Landfill in Lincoln, Nebraska USA. Methane emissions strongly depended on changes in barometric pressure; rising barometric pressure suppressed the emission, while falling barometric pressure enhanced the emission. Emission rates were systematically higher in December than during the summer period. Higher methane emission rates were associated with changes in barometric pressure that were larger in magnitude and longer in duration in winter than in summer, and with lower mean temperatures, which appeared to reduce methane oxidation rates. Sharp changes in barometric pressure caused up to 35-fold variation in day-to-day methane emissions. Power spectrum and ogive analysis showed that continuous measurements over a period of at least 10 days were needed in order to capture 90% of total variance in the methane emission time series at our site. Our results suggest that point-in-time methane emission rate measurements taken at monthly or even longer time intervals using techniques such as the tracer plume method, the mass balance method, or the closed-chamber method may be subject to large variations because of the strong dependence of methane emissions on changes in barometric pressure. Estimates of long-term integrated methane emissions from landfills based on such measurements will inevitably yield large uncertainties. Our results demonstrate the value of continuous measurements for quantifying total annual methane emission from a landfill.

  12. Quantifying the relative contribution of natural gas fugitive emissions to total methane emissions in Colorado, Utah, and Texas using mobile isotopic methane analysis based on Cavity Ringdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Rella, Chris; Winkler, Renato; Sweeney, Colm; Karion, Anna; Petron, Gabrielle; Crosson, Eric

    2014-05-01

    Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Because methane is more energy-rich than coal per kg of carbon dioxide emitted into the atmosphere, it represents an attractive alternative to coal for electricity generation, provided that the fugitive emissions of methane are kept under control. A key step in assessing these emissions in a given region is partitioning the observed methane emissions between natural gas fugitive emissions and other sources of methane, such as from landfills or agricultural activities. One effective method for assessing the contribution of these different sources is stable isotope analysis, using the isotopic carbon signature to distinguish between natural gas and landfills or ruminants. We present measurements of methane using a mobile spectroscopic stable isotope analyzer based on cavity ringdown spectroscopy, in three intense natural gas producing regions of the United States: the Denver-Julesburg basin in Colorado, the Uintah basin in Utah, and the Barnett Shale in Texas. Performance of the CRDS isotope analyzer is presented, including precision, calibration, stability, and the potential for measurement bias due to other atmospheric constituents. Mobile isotope measurements of individual sources and in the nocturnal boundary layer have been combined to establish the fraction of the observed methane emissions that can be attributed to natural gas activities. The fraction of total methane emissions in the Denver-Julesburg basin attributed to natural gas emissions is 78 +/- 13%. In the Uinta basin, which has no other significant sources of methane, the fraction is 96% +/- 15%. In addition, results from the Barnett shale are presented, which includes a major urban center (Dallas / Ft. Worth). Methane emissions in this region are spatially highly heterogeneous. Spatially-resolved isotope and concentration measurements are interpreted using a simple emissions model to arrive at an overall isotope ratio for the region.

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

    E-print Network

    Turk, Danny Carroll

    1993-01-01

    /grain levels. Criteria in the models included: percent grain in diet, average daily gain, body condition score, frame score and the types of technologies used, (ionophore, growth regulating implant, adequate protein/energy and mineral supplementation), cows...

  14. Revising a process-based biogeochemistry model (DNDC) to simulate methane emission from rice

    E-print Network

    - tions. The revised model simulates rice growth by tracking photosynthesis, respiration, C allocation, tillering, and release of organic C and O2 from roots. For anaerobic soil processes, it quantifies sensitive to the content of reducible soil Fe3 1 , which is the dominant electron acceptor in anaerobic

  15. 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.

    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.

  16. Measurements of the methane relaxation times for application to the infrared emission models of the upper atmospheres of outer planets and Titan

    NASA Technical Reports Server (NTRS)

    Halthore, Rangasayi N.; Caldwell, John J.; Allen, John E., Jr.; Burt, Jim A.; Yang, Kuanghua; Delaney, Paul

    1990-01-01

    The 7.8 micrometer emission from the nu(sub 4) band of methane (CH4) is a regularly observed feature in the stratosphere of all the giant planets and Titan. On Jupiter, enhancements in this emission are associated with the infrared hot spots in the auroral zone. Attempts to model this phenomenon in particular, and to understand the role of methane in general, have been hampered in part by a lack of adequate laboratory measurements of the collisional relaxation times for the nu(sub 3) and nu(sub 4) levels over the appropriate temperature range. To provide this needed data, a series of laboratory experiments were initiated. In the experimental arrangement the nu(sub3) band of methane is pumped at 3.3 micrometers using a pulsed infrared source (Nd:YAG/dye laser system equipped with a wave-length extender). The radiative lifetime of the nu(sub 3) level (approximately 37 ms) is much shorter than the nu(sub 4) lifetime (approximately 390 ms); however, a rapid V-V energy transfer rate ensures that the nu(sub 4) level is substantially populated. The photoacoustic technique is used to acquire relaxation rate information. The experiments are performed using a low-temperature, low-pressure cell. Experimental apparatus and technique are described. In addition some of the experimental difficulties associated with making these measurements are discussed and some preliminary results are presented.

  17. Measurements of the methane relaxation times for application to the infrared emission models of the upper atmospheres of outer planets and Titan

    NASA Astrophysics Data System (ADS)

    Halthore, Rangasayi N.; Caldwell, John J.; Allen, John E., Jr.; Burt, Jim A.; Yang, Kuanghua; Delaney, Paul

    1990-05-01

    The 7.8 micrometer emission from the nu4 band of methane (CH4) is a regularly observed feature in the stratosphere of all the giant planets and Titan. On Jupiter, enhancements in this emission are associated with the infrared hot spots in the auroral zone. Attempts to model this phenomenon in particular, and to understand the role of methane in general, have been hampered in part by a lack of adequate laboratory measurements of the collisional relaxation times for the nu3 and nu4 levels over the appropriate temperature range. To provide this needed data, a series of laboratory experiments were initiated. In the experimental arrangement the nu(sub3) band of methane is pumped at 3.3 micrometers using a pulsed infrared source (Nd:YAG/dye laser system equipped with a wave-length extender). The radiative lifetime of the nu3 level (approximately 37 ms) is much shorter than the nu4 lifetime (approximately 390 ms); however, a rapid V-V energy transfer rate ensures that the nu4 level is substantially populated. The photoacoustic technique is used to acquire relaxation rate information. The experiments are performed using a low-temperature, low-pressure cell. Experimental apparatus and technique are described. In addition some of the experimental difficulties associated with making these measurements are discussed and some preliminary results are presented.

  18. Siberian shelf methane emissions not tied to modern warming

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2011-12-01

    Eight thousand years ago, a rising sea inundated the vast permafrost regions off the northern coast of Siberia. Comprising the modern east Siberian shelf, the region holds enormous quantities of methane hydrates bottled up in remnant subterranean permafrost zones that are, in turn, trapped beneath the ocean waters. Records of seafloor water temperature showing a 2.1°C rise since 1985, coupled with recent observations of methane emissions from the seabed, have led some scientists to speculate that the rising temperatures have thawed some of the subsurface permafrost, liberating the trapped methane. The connection is compelling, but an investigation by Dmitrenko et al. into the sensitivity of permafrost to rising temperatures suggests the two observations are not connected. Using a permafrost model forced with paleoclimate data to analyze changes in the depth of frozen bottom sediments, the authors found that roughly 1 meter of the subsurface permafrost thawed in the past 25 years, adding to the 25 meters of already thawed soil. Forecasting the expected future permafrost thaw, the authors found that even under the most extreme climatic scenario tested this thawed soil growth will not exceed 10 meters by 2100 or 50 meters by the turn of the next millennium. The authors note that the bulk of the methane stores in the east Siberian shelf are trapped roughly 200 meters below the seafloor, indicating that the recent methane emissions observations were likely not connected to the modest modern permafrost thaw. Instead, they suggest that the current methane emissions are the result of the permafrost's still adjusting to its new aquatic conditions, even after 8000 years. (Journal of Geophysical Research-Oceans, doi:10.1029/2011JC007218, 2011)

  19. Offsetting Ongoing Methane Emissions --- An Alternative to Emission Equivalence Metrics

    NASA Astrophysics Data System (ADS)

    Clisby, N.; Enting, I. G.; Lauder, A.; Carter, J.; Cowie, A.; Henry, B.; Raupach, M. R.

    2012-12-01

    The Global Warming Potential (GWP) has been widely adopted as a metric for comparing the climate impact of different greenhouse gases. As has been frequently noted, there are many problems with using GWPs to define emission equivalence in spite of the use of GWPs for this purpose in contexts such as the Kyoto Protocol. We propose that for methane, rather than define emission equivalence, the appropriate comparison is between ongoing emissions of 0.9 to 1.0 kg of CH4 per year and one-off emissions of 1 tonne of carbon. This approach represents an approximate solution to the inverse problem of defining a forcing equivalent index (FEI) that gives exact equivalence of radiative forcing over a range of timescales. In our approach, if ongoing methane emissions are offset by a one-off carbon removal that is built up with 40-year e-folding time, then the result is close to radiatively neutral over periods from years to centuries. In contrast, the GWP provides radiative equivalence (in integrated terms) only at a single time, with large discrepancies at other times. Our approach also follows from consideration of greenhouse gas stabilisation, since stabilising atmospheric CO2 requires an approximate cap on total emissions, while stabilising methane requires stabilisation of ongoing emissions. Our quantitative treatment recognises that, on time scales of centuries, removal of 1 tonne of carbon only lowers the atmospheric carbon content by 0.3 to 0.35 tonnes. We discuss the implications for rangeland grazing systems. In the absence of effective mitigation techniques for methane from rangeland systems, this approach may provide an attractive offset mechanism in spite of requiring that woody vegetation be established and maintained over about 15% of the landscape, or an equivalent amount of carbon storage in soil.

  20. Estimation of methane emissions from a wastewater treatment plant in Valence

    NASA Astrophysics Data System (ADS)

    Ars, Sébastien; Yver Kwok, Camille; Bousquet, Philippe; Broquet, Grégoire; Ciais, Philippe; Wu, Lin

    2014-05-01

    Methane is the second most important anthropogenic greenhouse gas emitted; its 20 year global-warming potential is about 56 to 72 depending on authors. One of its sources is the treatment of wastewaters and more particularly anaerobic digestion processes and sludge treatment. To reduce methane emissions from wastewater treatment plants, it is necessary to precisely quantify the amount emitted globally by the plant but also for each step of the process. Fixing the potential leaks and collecting the methane emitted by the different processes allows to reduce methane emissions and costs as methane can be sold or used on-site as an energy source. Moreover improve methods to estimate flow from atmospheric measurements of methane will reduce uncertainties in the inversion models. Several measurement campaigns have been realized in the wastewater treatment plant of Valence, France. This plant treats up to 2800 m3/h of polluted water through a biological treatment. To quantify methane emissions from this wastewater treatment plant, a dual tracer method had been used. It consists in releasing acetylene collocated with the methane source and in measuring both concentrations in the emitted plumes. In parallel, an atmospheric local scale model was used to compare with the experimental results. The higher concentration of methane's emissions was observed around the wastewater arrival. Plant's emissions are in the same range as estimations from the CITEPA French inventory. Measurements during the campaign are well correlated with the model results.

  1. STRAW MANAGEMENT AFFECTING METHANE EMISSIONS FROM DIFFERENT RICE ECOSYSTEMS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Emissions of the greenhouse gas methane from wetland rice fields are generally enhanced by organic inputs into the soil. This study investigates methane emissions and crop residue management at three sites: Los Banos (Philippines), Hangzhou (China), and Prachinburi (Thailand). In Los Banos, the co...

  2. Diurnal variations in methane emission from rice plants 

    E-print Network

    Laskowski, Nicholas Aaron

    2004-11-15

    was greatly reduced when compared to the intact plant. Results from the vascular transport experiment showed that transpiration is a major factor in methane emission. Emission dependence on soil temperature was examined to test the hypothesis that soil...

  3. Cold season emissions dominate the Arctic tundra methane budget.

    PubMed

    Zona, Donatella; Gioli, Beniamino; Commane, Róisín; Lindaas, Jakob; Wofsy, Steven C; Miller, Charles E; Dinardo, Steven J; Dengel, Sigrid; Sweeney, Colm; Karion, Anna; Chang, Rachel Y-W; Henderson, John M; Murphy, Patrick C; Goodrich, Jordan P; Moreaux, Virginie; Liljedahl, Anna; Watts, Jennifer D; Kimball, John S; Lipson, David A; Oechel, Walter C

    2016-01-01

    Arctic terrestrial ecosystems are major global sources of methane (CH4); hence, it is important to understand the seasonal and climatic controls on CH4 emissions from these systems. Here, we report year-round CH4 emissions from Alaskan Arctic tundra eddy flux sites and regional fluxes derived from aircraft data. We find that emissions during the cold season (September to May) account for ?50% of the annual CH4 flux, with the highest emissions from noninundated upland tundra. A major fraction of cold season emissions occur during the "zero curtain" period, when subsurface soil temperatures are poised near 0 °C. The zero curtain may persist longer than the growing season, and CH4 emissions are enhanced when the duration is extended by a deep thawed layer as can occur with thick snow cover. Regional scale fluxes of CH4 derived from aircraft data demonstrate the large spatial extent of late season CH4 emissions. Scaled to the circumpolar Arctic, cold season fluxes from tundra total 12 ± 5 (95% confidence interval) Tg CH4 y(-1), ?25% of global emissions from extratropical wetlands, or ?6% of total global wetland methane emissions. The dominance of late-season emissions, sensitivity to soil environmental conditions, and importance of dry tundra are not currently simulated in most global climate models. Because Arctic warming disproportionally impacts the cold season, our results suggest that higher cold-season CH4 emissions will result from observed and predicted increases in snow thickness, active layer depth, and soil temperature, representing important positive feedbacks on climate warming. PMID:26699476

  4. 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

  5. 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

  6. 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.

  7. Connecting Climate and Air Quality: Tropospheric Ozone Response to Methane Emission Controls

    NASA Astrophysics Data System (ADS)

    Fiore, A. M.; West, J. J.; Horowitz, L. W.

    2006-12-01

    Methane oxidation in the presence of nitrogen oxides (NOx) contributes to tropospheric ozone, raising baseline levels of ozone pollution in surface air globally. Since methane is also a potent greenhouse gas, controls on methane offer a strategy for jointly addressing air pollution and climate goals. Crafting successful policy will require knowledge of the magnitude, spatial pattern and linearity of the surface ozone and radiative forcing responses to changes in methane emissions. We use the MOZART-2 global model of tropospheric chemistry to characterize these responses with multi-decadal, full-chemistry simulations in which methane concentrations are allowed to adjust to emission changes. We first conduct idealized simulations with global anthropogenic methane emissions reduced by 30%, either: (1) uniformly worldwide, or (2) entirely from Asia. We find that the methane source location has little influence on the tropospheric ozone distribution, but that the ozone response exhibits spatial variability, with a greater decrease in downwelling regions and in locations with NOx-saturated chemistry. Combining our results with those in the published literature, we show that trospospheric ozone responds approximately linearly to changes in methane emissions, and that current anthropogenic methane emissions contribute roughly 50 Tg (~15%) to the tropospheric ozone burden, and 5 ppbv to global surface ozone. To examine how transient methane emission controls would interact with anticipated changes in other ozone precursors, we apply three methane control scenarios for 2005-2030 relative to the "Current Legislation Emissions" (CLE) baseline that was developed for the recent PHOTOCOMP model intercomparison. Under the CLE scenario, anthropogenic methane emissions grow by 29% from 2005 to 2030, contributing to a 20 Tg increase in the tropospheric ozone burden, and a 1.3 ppbv increase in global annual mean surface ozone in our model. In the three methane control scenarios, we apply progressively larger anthropogenic emission reductions each year from 2006 to 2030, ultimately attaining emission decreases of 18, 29 and 42% relative to the 2030 CLE emissions. We will discuss the resulting implications for air quality and climate.

  8. Evaluation of the SF6 tracer technique for estimating methane emission rates with reference to dairy cows using a mechanistic model.

    PubMed

    Berends, H; Gerrits, W J J; France, J; Ellis, J L; van Zijderveld, S M; Dijkstra, J

    2014-07-21

    A dynamic, mechanistic model of the sulfur hexafluoride (SF6) tracer technique, used for estimating methane (CH4) emission rates from ruminants, was constructed to evaluate the accuracy of the technique. The model consists of six state variables and six zero-pools representing the quantities of SF6 and CH4 in rumen and hindgut fluid, in rumen and hindgut headspace, and in blood and collection canister. The model simulates flows of CH4 and SF6 through the body, subsequent eructation and exhalation and accumulation in a collection canister. The model predicts CH4 emission by multiplying the SF6 release rate of a permeation device in the rumen by the ratio of CH4:SF6 in collected air. This prediction is compared with the actual CH4 production rate, assumed to be continuous and used as a driving variable in the model. A sensitivity analysis was conducted to evaluate the effect of changes in several parameters. The predicted CH4 emission appeared sensitive to parameters affected by the difference in CH4:SF6 ratio in exhaled and eructed air respectively, viz., hindgut fractional passage rate and hindgut CH4 production. This is caused by the difference in solubility of CH4 and SF6 and by hindgut CH4 production. In addition, the predicted CH4 emission rate appeared sensitive to factors that affect proportions of exhaled and eructed air sampled, i.e., eructation time fraction, exhalation time fraction, and distance from sampling point to mouth/nostrils. Changes in rumen fractional passage rate, eructation rate, SF6 release rate, background values and air sampling rate did not noticeably affect the predicted CH4 emission. Simulations with (13)CH4 as an alternative tracer show that the differences and sensitivity to parameters greatly disappear. The model is considered a useful tool to evaluate critical points in the SF6 technique. Data from in vivo experiments are needed to further evaluate model simulations. PMID:24625680

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

    SciTech Connect

    Lin Erda; Li Yue; Dong Hongmin; Zhou Wennong

    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.

  10. 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

  11. Modeling the Terrestrial Contribution to the Global Methane Balance

    NASA Astrophysics Data System (ADS)

    Smith, Amy Tetlow

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

  12. 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.

  13. 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.

  14. LANDFILL OPERATION FOR CARBON SEQUESTRATION AND MAXIMUM METHANE EMISSION CONTROL

    SciTech Connect

    Don Augenstein

    1999-01-11

    ''Conventional'' waste landfills emit methane, a potent greenhouse gas, in quantities such that landfill methane is a major factor in global climate change. Controlled landfilling is a novel approach to manage landfills for rapid completion of total gas generation, maximizing gas capture and minimizing emissions of methane to the atmosphere. With controlled landfilling, methane generation is accelerated and brought to much earlier completion by improving conditions for biological processes (principally moisture levels) in the landfill. Gas recovery efficiency approaches 100% through use of surface membrane cover over porous gas recovery layers operated at slight vacuum. A field demonstration project's results at the Yolo County Central Landfill near Davis, California are, to date, highly encouraging. Two major controlled landfilling benefits would be the reduction of landfill methane emissions to minuscule levels, and the recovery of greater amounts of landfill methane energy in much shorter times than with conventional landfill practice. With the large amount of US landfill methane generated, and greenhouse potency of methane, better landfill methane control can play a substantial role in reduction of US greenhouse gas emissions.

  15. 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.

  16. Future methane, hydroxyl, and their uncertainties: key climate and emission parameters for future predictions

    NASA Astrophysics Data System (ADS)

    Holmes, C. D.; Prather, M. J.; Søvde, O. A.; Myhre, G.

    2013-01-01

    Accurate prediction of future methane abundances following a climate scenario requires understanding the lifetime changes driven by anthropogenic emissions, meteorological factors, and chemistry-climate feedbacks. Uncertainty in any of these influences or the underlying processes implies uncertainty in future abundance and radiative forcing. We simulate methane lifetime in three chemical transport models (CTMs) - UCI CTM, GEOS-Chem, and Oslo CTM3 - over the period 1997-2009 and compare the models' year-to-year variability against constraints from global methyl chloroform observations. Using sensitivity tests, we find that temperature, water vapor, stratospheric ozone column, biomass burning and lightning NOx are the dominant sources of interannual changes in methane lifetime in all three models. We also evaluate each model's response to forcings that have impacts on decadal time scales, such as methane feedback, and anthropogenic emissions. In general, these different CTMs show similar sensitivities to the driving variables. We construct a parametric model that reproduces most of the interannual variability of each CTM and use it to predict methane lifetime from 1980 through 2100 following a specified emissions and climate scenario (RCP 8.5). The parametric model propagates uncertainties through all steps and provides a foundation for predicting methane abundances in any climate scenario. Our sensitivity tests also enable a new estimate of the methane global warming potential (GWP), accounting for stratospheric ozone effects, including those mediated by water vapor. We estimate the 100-yr GWP to be 32, which is 25% larger than past assessments.

  17. Impact of changes in barometric pressure on landfill methane emission

    NASA Astrophysics Data System (ADS)

    Xu, Liukang; Lin, Xiaomao; Amen, Jim; Welding, Karla; McDermitt, Dayle

    2014-07-01

    Landfill methane emissions were measured continuously using the eddy covariance method from June to December 2010. The study site was located at the Bluff Road Landfill in Lincoln, Nebraska, USA. Our results show that landfill methane emissions strongly depended on changes in barometric pressure; rising barometric pressure suppressed the emission, while falling barometric pressure enhanced the emission, a phenomenon called barometric pumping. There was up to a 35-fold variation in day-to-day methane emissions due to changes in barometric pressure. Wavelet coherence analysis revealed a strong spectral coherency between variations of barometric pressure and methane emission at periodicities ranging from 1 day to 8 days. Power spectrum and ogive analysis showed that at least 10 days of continuous measurements was needed in order to capture 90% of the total variance in the methane emission time series at our landfill site. From our results, it is clear that point-in-time measurements taken at monthly or longer time intervals using techniques such as the trace plume method, the mass balance method, or the closed-chamber method will be subject to large variations in measured emission rates because of the barometric pumping phenomenon. Estimates of long-term integrated methane emissions from landfills based on such measurements could yield uncertainties, ranging from 28.8% underestimation to 32.3% overestimation. Our results demonstrate a need for continuous measurements to quantify annual total landfill emissions. This conclusion may apply to the study of methane emissions from wetlands, peatlands, lakes, and other environmental contexts where emissions are from porous media or ebullition. Other implications from the present study for hazard gas monitoring programs are also discussed.

  18. Reconciling divergent estimates of oil and gas methane emissions.

    PubMed

    Zavala-Araiza, Daniel; Lyon, David R; Alvarez, Ramón A; Davis, Kenneth J; Harriss, Robert; Herndon, Scott C; Karion, Anna; Kort, Eric Adam; Lamb, Brian K; Lan, Xin; Marchese, Anthony J; Pacala, Stephen W; Robinson, Allen L; Shepson, Paul B; Sweeney, Colm; Talbot, Robert; Townsend-Small, Amy; Yacovitch, Tara I; Zimmerle, Daniel J; Hamburg, Steven P

    2015-12-22

    Published estimates of methane emissions from atmospheric data (top-down approaches) exceed those from source-based inventories (bottom-up approaches), leading to conflicting claims about the climate implications of fuel switching from coal or petroleum to natural gas. Based on data from a coordinated campaign in the Barnett Shale oil and gas-producing region of Texas, we find that top-down and bottom-up estimates of both total and fossil methane emissions agree within statistical confidence intervals (relative differences are 10% for fossil methane and 0.1% for total methane). We reduced uncertainty in top-down estimates by using repeated mass balance measurements, as well as ethane as a fingerprint for source attribution. Similarly, our bottom-up estimate incorporates a more complete count of facilities than past inventories, which omitted a significant number of major sources, and more effectively accounts for the influence of large emission sources using a statistical estimator that integrates observations from multiple ground-based measurement datasets. Two percent of oil and gas facilities in the Barnett accounts for half of methane emissions at any given time, and high-emitting facilities appear to be spatiotemporally variable. Measured oil and gas methane emissions are 90% larger than estimates based on the US Environmental Protection Agency's Greenhouse Gas Inventory and correspond to 1.5% of natural gas production. This rate of methane loss increases the 20-y climate impacts of natural gas consumed in the region by roughly 50%. PMID:26644584

  19. Reconciling divergent estimates of oil and gas methane emissions

    PubMed Central

    Zavala-Araiza, Daniel; Lyon, David R.; Alvarez, Ramón A.; Davis, Kenneth J.; Harriss, Robert; Herndon, Scott C.; Karion, Anna; Kort, Eric Adam; Lamb, Brian K.; Lan, Xin; Marchese, Anthony J.; Pacala, Stephen W.; Robinson, Allen L.; Shepson, Paul B.; Sweeney, Colm; Talbot, Robert; Townsend-Small, Amy; Yacovitch, Tara I.; Zimmerle, Daniel J.; Hamburg, Steven P.

    2015-01-01

    Published estimates of methane emissions from atmospheric data (top-down approaches) exceed those from source-based inventories (bottom-up approaches), leading to conflicting claims about the climate implications of fuel switching from coal or petroleum to natural gas. Based on data from a coordinated campaign in the Barnett Shale oil and gas-producing region of Texas, we find that top-down and bottom-up estimates of both total and fossil methane emissions agree within statistical confidence intervals (relative differences are 10% for fossil methane and 0.1% for total methane). We reduced uncertainty in top-down estimates by using repeated mass balance measurements, as well as ethane as a fingerprint for source attribution. Similarly, our bottom-up estimate incorporates a more complete count of facilities than past inventories, which omitted a significant number of major sources, and more effectively accounts for the influence of large emission sources using a statistical estimator that integrates observations from multiple ground-based measurement datasets. Two percent of oil and gas facilities in the Barnett accounts for half of methane emissions at any given time, and high-emitting facilities appear to be spatiotemporally variable. Measured oil and gas methane emissions are 90% larger than estimates based on the US Environmental Protection Agency’s Greenhouse Gas Inventory and correspond to 1.5% of natural gas production. This rate of methane loss increases the 20-y climate impacts of natural gas consumed in the region by roughly 50%. PMID:26644584

  20. 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.

  1. 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...

  2. Inventory of methane emissions from U.S. cattle

    NASA Astrophysics Data System (ADS)

    Westberg, H.; Lamb, B.; Johnson, K. A.; Huyler, M.

    2001-01-01

    Many countries, including the United States, are in the process of inventorying greenhouse gas emissions as a prerequisite for designing control strategies. We have developed a measurement-based inventory of methane emissions from cattle in the United States. Methane emission factors were established for the major livestock groups using an internal tracer method. The groups studied included cows, replacement heifers, slaughter cattle, calves, and bulls in the beef sector and cows plus replacement heifers in the dairy industry. Since methane emission is dependent on the quality and quantity of feed, diets were chosen that are representative of the feed regimes utilized by producers in the United States. Regional cattle populations, obtained from U.S. Department of Agriculture statistics, were combined with the methane emission factors to yield regional emission estimates. The methane totals from the five regions were then summed to give a U.S. inventory of cattle emissions for 1990, 1992, 1994, 1996, and 1998. Annual releases ranged from 6.50 Tg in 1990 to a high of 6.98 Tg in 1996. On a regional scale the North Central region of the United States had the largest methane emissions from livestock followed by the South Central and the West. The beef cow group released the most methane (˜2.5 Tg yr-1) followed by slaughter cattle (˜1.7 Tg yr-1) and dairy cows at about 1.5 Tg yr-1. Methane released by cattle in the United States contributes about 11% of the global cattle source.

  3. A multitower measurement network estimate of California's methane emissions

    NASA Astrophysics Data System (ADS)

    Jeong, Seongeun; Hsu, Ying-Kuang; Andrews, Arlyn E.; Bianco, Laura; Vaca, Patrick; Wilczak, James M.; Fischer, Marc L.

    2013-10-01

    present an analysis of methane (CH4) emissions using atmospheric observations from five sites in California's Central Valley across different seasons (September 2010 to June 2011). CH4 emissions for spatial regions and source sectors are estimated by comparing measured CH4 mixing ratios with transport model (Weather Research and Forecasting and Stochastic Time-Inverted Lagrangian Transport) predictions based on two 0.1° CH4 (seasonally varying "California-specific" (California Greenhouse Gas Emission Measurements, CALGEM) and a static global (Emission Database for Global Atmospheric Research, release version 42, EDGAR42)) prior emission models. Region-specific Bayesian analyses indicate that for California's Central Valley, the CALGEM- and EDGAR42-based inversions provide consistent annual total CH4 emissions (32.87 ± 2.09 versus 31.60 ± 2.17 Tg CO2eq yr-1; 68% confidence interval (CI), assuming uncorrelated errors between regions). Summing across all regions of California, optimized CH4 emissions are only marginally consistent between CALGEM- and EDGAR42-based inversions (48.35 ± 6.47 versus 64.97 ± 11.85 Tg CO2eq), because emissions from coastal urban regions (where landfill and natural gas emissions are much higher in EDGAR than CALGEM) are not strongly constrained by the measurements. Combining our results with those from a recent study of the South Coast Air Basin narrows the range of estimates to 43-57 Tg CO2eq yr-1 (1.3-1.8 times higher than the current state inventory). These results suggest that the combination of rural and urban measurements will be necessary to verify future changes in California's total CH4 emissions.

  4. A tiered observational system for anthropogenic methane emissions

    NASA Astrophysics Data System (ADS)

    Duren, R. M.; Miller, C. E.; Hulley, G. C.; Hook, S. J.; Sander, S. P.

    2014-12-01

    Improved understanding of anthropogenic methane emissions is required for closing the global carbon budget and addressing priority challenges in climate policy. Several decades of top-down and bottom-up studies show that anthropogenic methane emissions are systematically underestimated in key regions and economic sectors. These uncertainties have been compounded by the dramatic rise of disruptive technologies (e.g., the transformation in the US energy system due to unconventional gas and oil production). Methane flux estimates derived from inverse analyses and aircraft-based mass balance approaches underscore the disagreement in nationally and regionally reported methane emissions as well as the possibility of a long-tail distribution in fugitive emissions spanning the US natural gas supply chain; i.e. a small number of super-emitters may be responsible for most of the observed anomalies. Other studies highlight the challenges of sectoral and spatial attribution of fugitive emissions - including the relative contributions of dairies vs oil and gas production or disentangling the contributions of natural gas transmission, distribution, and consumption or landfill emissions in complex urban environments. Limited observational data remains a foundational barrier to resolving these challenges. We present a tiered observing system strategy for persistent, high-frequency monitoring over large areas to provide remote detection, geolocation and quantification of significant anthropogenic methane emissions across cities, states, basins and continents. We describe how this would both improve confidence in methane emission estimates and expedite resolution of fugitive emissions and leaks. We summarize recent prototype field campaigns that employ multiple vantage points and measurement techniques (including NASA's CARVE and HyTES aircraft and PanFTS instrument on Mt Wilson). We share preliminary results of this tiered observational approach including examples of individual methane point sources associated with oil and gas production and distribution, feedlots, and urban landfills in California.

  5. 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...

  6. Biomass of termites and their emissions of methane and carbon dioxide: A global database

    NASA Astrophysics Data System (ADS)

    Sanderson, M. G.

    1996-12-01

    A global database describing the geographical distribution of the biomass of termites and their emissions of methane and carbon dioxide has been constructed. Termite biomasses were assigned to various ecosystems using published measurements and a recent high-resolution (10' × 10') database of vegetation categories. The assigned biomasses were then combined with literature measurements of fluxes of methane and carbon dioxide from termites and extrapolated to give global emission estimates for each gas. The global emissions of methane and carbon dioxide are 19.7 ± 1.5 and 3500 ± 700 Mt yr-1, respectively (1 Mt = 1012 g). These emissions contribute approximately 4% and 2%, respectively, to the total global fluxes of these gases. This database gives an accurate distribution of the biomasses and gaseous emissions by termites and may be incorporated into global models of the atmosphere.

  7. 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.

  8. 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

  9. 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...

  10. 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...

  11. HIGH METHANE EMISSIONS FROM A MID-LATITUDE AGRICULTURAL RESERVOIR

    EPA Science Inventory

    To assess the magnitude of methane (CH4) emissions from reservoirs in agricultural regions, we measured CH4 emission rates from William H. Harsha Lake, located in southwestern Ohio, USA, over a thirteen month period. The reservoir was a strong source of CH4¬ throughout the year,...

  12. 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 ...

  13. 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

  14. Emissions of organic carbon and methane from petroleum and dairy operations in California's San Joaquin Valley

    NASA Astrophysics Data System (ADS)

    Gentner, D. R.; Ford, T. B.; Guha, A.; Boulanger, K.; Brioude, J.; Angevine, W. M.; de Gouw, J. A.; Warneke, C.; Gilman, J. B.; Ryerson, T. B.; Peischl, J.; Meinardi, S.; Blake, D. R.; Atlas, E.; Lonneman, W. A.; Kleindienst, T. E.; Beaver, M. R.; St. Clair, J. M.; Wennberg, P. O.; VandenBoer, T. C.; Markovic, M. Z.; Murphy, J. G.; Harley, R. A.; Goldstein, A. H.

    2014-05-01

    Petroleum and dairy operations are prominent sources of gas-phase organic compounds in California's San Joaquin Valley. It is essential to understand the emissions and air quality impacts of these relatively understudied sources, especially for oil/gas operations in light of increasing US production. Ground site measurements in Bakersfield and regional aircraft measurements of reactive gas-phase organic compounds and methane were part of the CalNex (California Research at the Nexus of Air Quality and Climate Change) project to determine the sources contributing to regional gas-phase organic carbon emissions. Using a combination of near-source and downwind data, we assess the composition and magnitude of emissions, and provide average source profiles. To examine the spatial distribution of emissions in the San Joaquin Valley, we developed a statistical modeling method using ground-based data and the FLEXPART-WRF transport and meteorological model. We present evidence for large sources of paraffinic hydrocarbons from petroleum operations and oxygenated compounds from dairy (and other cattle) operations. In addition to the small straight-chain alkanes typically associated with petroleum operations, we observed a wide range of branched and cyclic alkanes, most of which have limited previous in situ measurements or characterization in petroleum operation emissions. Observed dairy emissions were dominated by ethanol, methanol, acetic acid, and methane. Dairy operations were responsible for the vast majority of methane emissions in the San Joaquin Valley; observations of methane were well correlated with non-vehicular ethanol, and multiple assessments of the spatial distribution of emissions in the San Joaquin Valley highlight the dominance of dairy operations for methane emissions. The petroleum operations source profile was developed using the composition of non-methane hydrocarbons in unrefined natural gas associated with crude oil. The observed source profile is consistent with fugitive emissions of condensate during storage or processing of associated gas following extraction and methane separation. Aircraft observations of concentration hotspots near oil wells and dairies are consistent with the statistical source footprint determined via our FLEXPART-WRF-based modeling method and ground-based data. We quantitatively compared our observations at Bakersfield to the California Air Resources Board emission inventory and find consistency for relative emission rates of reactive organic gases between the aforementioned sources and motor vehicles in the region. We estimate that petroleum and dairy operations each comprised 22% of anthropogenic non-methane organic carbon at Bakersfield and were each responsible for 8-13% of potential precursors to ozone. Yet, their direct impacts as potential secondary organic aerosol (SOA) precursors were estimated to be minor for the source profiles observed in the San Joaquin Valley.

  15. Rising methane emissions from northern wetlands associated with sea ice decline

    NASA Astrophysics Data System (ADS)

    Parmentier, Frans-Jan W.; Zhang, Wenxin; Mi, Yanjiao; Zhu, Xudong; Huissteden, Jacobus; Hayes, Daniel J.; Zhuang, Qianlai; Christensen, Torben R.; McGuire, A. David

    2015-09-01

    The Arctic is rapidly transitioning toward a seasonal sea ice-free state, perhaps one of the most apparent examples of climate change in the world. This dramatic change has numerous consequences, including a large increase in air temperatures, which in turn may affect terrestrial methane emissions. Nonetheless, terrestrial and marine environments are seldom jointly analyzed. By comparing satellite observations of Arctic sea ice concentrations to methane emissions simulated by three process-based biogeochemical models, this study shows that rising wetland methane emissions are associated with sea ice retreat. Our analyses indicate that simulated high-latitude emissions for 2005-2010 were, on average, 1.7 Tg CH4 yr-1 higher compared to 1981-1990 due to a sea ice-induced, autumn-focused, warming. Since these results suggest a continued rise in methane emissions with future sea ice decline, observation programs need to include measurements during the autumn to further investigate the impact of this spatial connection on terrestrial methane emissions.

  16. Predicting methane emission from bryophyte distribution in northern Canadian peatlands

    SciTech Connect

    Bubier, J.L.; Moore, T.R.; Juggins, S.

    1995-04-01

    A predictive model for bryophyte distribution, water table position, and seasonal mean methane (CH{sub 4}) emission was developed for two areas of northern peatland: the Clay Belt of Ontario and the Labrador Trough of Quebec. Water table position and CH{sub 4} flux were the most important environmental variables in canonical correspondence analyses (CCA) of bryophyte data. Water chemistry constituted a second environmental gradient, independent of hydrology and CH{sub 4} flux. Weighted averaging regression and calibration were used to develop a model for predicting log CH{sub 4} flux from bryophyte distribution. The model showed an increase in log CH{sub 4} flux from hummock to carpet and pool species, corresponding with a decrease in height above the mean water table position. The exceptions were rich-fen pool species, which had low CH{sub 4} flux optima in spite of their moisture status. Tolerances were greatest for mid-hummock species and least for carpet and pool species. No overlap in tolerances occurred between hummock and pool species, suggesting that at either end of the height gradient are the best predictors of CH{sub 4} flux. Error analyses showed that bryophytes are equally as effective as water table position for predicting mean CH{sub 4} flux. Bryophytes are distributed in well-defined zones along microtopographic gradients: they integrate long-term changes in the water table, which fluctuates on a daily and seasonal basis along with CH{sub 4} flux, and may be more easily mapped with remote-sensing techniques. Bryophytes, however, are only useful for predicting CH{sub 4} flux within a region; similar species values cannot be extrapolated to other northern peatlands where different climatic and biogeochemical factors may exist. The model may be used in paleoreconstructions of methane emission and for biological monitoring of climate change. 62 refs., 8 figs., 3 tabs.

  17. Methane emissions measured directly from grazing livestock in New Zealand

    NASA Astrophysics Data System (ADS)

    Lassey, Keith R.; Ulyatt, Marcus J.; Martin, Ross J.; Walker, Carolyn F.; David Shelton, I.

    We report measurements of methane emissions from individual ruminant livestock-both sheep and dairy cows-grazing pasture typical of New Zealand lowlands in the temperate southwest Pacific. These are the first measurements reported from grazing sheep, and among the first from grazing cattle. The measurement technique, developed at Washington State University, enables emission rates to be determined from analyses of "breath" samples collected while grazing. More than 250 measurements of daily methane emission from 50 sheep (8 months old) were made, with flock-mean emission 18.9 ± 0.8 g hd -1 d -1. Although emissions were weakly correlated with feed intake, they represented a 4.6 ± 0.1 % average loss of gross dietary energy. The corresponding mean emission based on 40 measurements of daily emissions from 10 lactating dairy cows was 263 ± 10 g hd -1 d -1, approximately 6.2% of estimated gross energy intake. A notable feature was the large inter-sheep variability in daily methane emission (factor of 1.4 range) that could not be attributed to variable intake. This would appear to suggest an appreciable diversity of methanogenetic response to digestion, and may be significant in the search for strategies to control emissions of this greenhouse gas.

  18. Emissions of organic carbon and methane from petroleum and dairy operations in California's San Joaquin Valley

    NASA Astrophysics Data System (ADS)

    Gentner, D. R.; Ford, T. B.; Guha, A.; Boulanger, K.; Brioude, J.; Angevine, W. M.; de Gouw, J. A.; Warneke, C.; Gilman, J. B.; Ryerson, T. B.; Peischl, J.; Meinardi, S.; Blake, D. R.; Atlas, E.; Lonneman, W. A.; Kleindienst, T. E.; Beaver, M. R.; St. Clair, J. M.; Wennberg, P. O.; VandenBoer, T. C.; Markovic, M. Z.; Murphy, J. G.; Harley, R. A.; Goldstein, A. H.

    2013-10-01

    Petroleum and dairy operations are prominent sources of gas-phase organic compounds in California's San Joaquin Valley. Ground site measurements in Bakersfield and aircraft measurements of reactive gas-phase organic compounds were made in this region as part of the CalNex (California Research at the Nexus of Air Quality and Climate Change) project to determine the sources contributing to regional gas-phase organic carbon emissions. Using a combination of near-source and downwind data, we assess the composition and magnitude of emissions from these prominent sources that are relatively understudied compared to motor vehicles We also developed a statistical modeling method with the FLEXPART-WRF transport and meteorological model using ground-based data to assess the spatial distribution of emissions in the San Joaquin Valley. We present evidence for large sources of paraffinic hydrocarbons from petroleum extraction/processing operations and oxygenated compounds from dairy (and other cattle) operations. In addition to the small straight-chain alkanes typically associated with petroleum operations, we observed a wide range of branched and cyclic alkanes that have limited previous in situ measurements or characterization in emissions from petroleum operations. Observed dairy emissions were dominated by ethanol, methanol, and acetic acid, and methane. Dairy operations were responsible for the vast majority of methane emissions in the San Joaquin Valley; observations of methane were well-correlated with non-vehicular ethanol, and multiple assessments of the spatial distribution of emissions in the San Joaquin Valley highlight the dominance of dairy operations for methane emissions. The good agreement of the observed petroleum operations source profile with the measured composition of non-methane hydrocarbons in unrefined natural gas associated with crude oil suggests a fugitive emissions pathway during petroleum extraction, storage, or processing with negligible coincident methane emissions Aircraft observations of emission hotspots from operations at oil wells and dairies are consistent with the statistical source footprint determined via transport modeling and ground-based data. At Bakersfield, petroleum and dairy operations each comprised 22-23% of anthropogenic non-methane organic carbon and were each responsible for ~12% of potential precursors to ozone, but their direct impacts as potential SOA precursors were estimated to be minor. A comparison with the California Air Resources Board emission inventory supports the current relative emission rates of reactive organic gases from these sources in the region.

  19. 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.

  20. Magnitude and Seasonality of Wetland Methane Emissions from the Hudson Bay Lowlands (Canada)

    NASA Technical Reports Server (NTRS)

    Pickett-Heaps, C. A.; Jacob, D. J.; Wecht, K. J.; Kort, E. A.; Wofsy, S. C.; Diskin, G. S.; Worthy, D. E. J.; Kaplan, J. O.; Bey, I.; Drevet, J.

    2011-01-01

    The Hudson Bay Lowlands (HBL) is the second largest boreal wetland ecosystem in the world and an important natural source of global atmospheric methane. We quantify the HBL methane emissions by using the GEOS-Chem chemical transport model to simulate aircraft measurements over the HBL from the ARCTAS and pre-HIPPO campaigns in May-July 2008, together with continuous 2004-2008 surface observations at Fraserdale (southern edge of HBL) and Alert (Arctic background). The difference in methane concentrations between Fraserdale and Alert is shown to be a good indicator of HBL emissions, and implies a sharp seasonal onset of emissions in late May (consistent with the aircraft data), a peak in July-August, and a seasonal shut-off in September. The model, in which seasonal variation of emission is mainly driven by surface temperature, reproduces well the observations in summer but its seasonal shoulders are too broad. We suggest that this reflects the suppression of emissions by snow cover and greatly improve the model simulation by accounting for this effect. Our resulting best estimate for HBL methane emissions is 2.3 Tg/a, several-fold higher than previous estimates (Roulet et al., 1994; Worthy et al., 2000).

  1. 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.; 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.; Velazco, V. A.; Warneke, T.; Wennberg, P. O.; Wunch, D.

    2015-02-01

    We use 2009-2011 space-borne methane observations from the Greenhouse Gases Observing SATellite (GOSAT) to constrain global and North American inversions of methane emissions with 4° × 5° and up to 50 km × 50 km spatial resolution, respectively. The GOSAT data are first evaluated with atmospheric methane observations from surface networks (NOAA, TCCON) and aircraft (NOAA/DOE, 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. The surface and aircraft data are subsequently used for independent evaluation of the methane source inversions. Our global adjoint-based inversion yields a total methane source of 539 Tg a-1 and points to a large East Asian overestimate in 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 full 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 South-Central US, the Central Valley of California, and Florida wetlands, large isolated point sources such as the US Four Corners also contribute. We attribute 29-44% of US anthropogenic methane emissions to livestock, 22-31% to oil/gas, 20% to landfills/waste water, and 11-15% to coal with an additional 9.0-10.1 Tg a-1 source from wetlands.

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

    DOE PAGESBeta

    Turner, A. J.; Jacob, D. J.; Wecht, K. J.; Maasakkers, J. D.; Biraud, S. C.; Boesch, H.; Bowman, K. W.; Deutscher, N. M.; Dubey, M. K.; Griffith, D. W. T.; et al

    2015-02-18

    We use 2009–2011 space-borne methane observations from the Greenhouse Gases Observing SATellite (GOSAT) to constrain global and North American inversions of methane emissions with 4° × 5° and up to 50 km × 50 km spatial resolution, respectively. The GOSAT data are first evaluated with atmospheric methane observations from surface networks (NOAA, TCCON) and aircraft (NOAA/DOE, 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. The surface and aircraft data are subsequently usedmore »for independent evaluation of the methane source inversions. Our global adjoint-based inversion yields a total methane source of 539 Tg a?1 and points to a large East Asian overestimate in 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 full 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 South-Central US, the Central Valley of California, and Florida wetlands, large isolated point sources such as the US Four Corners also contribute. We attribute 29–44% of US anthropogenic methane emissions to livestock, 22–31% to oil/gas, 20% to landfills/waste water, and 11–15% to coal with an additional 9.0–10.1 Tg a?1 source from wetlands.« less

  3. 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...

  4. Methane emissions from natural gas infrastructure and use in the urban region of Boston, Massachusetts

    PubMed Central

    McKain, Kathryn; Down, Adrian; Raciti, Steve M.; Budney, John; Hutyra, Lucy R.; Floerchinger, Cody; Herndon, Scott C.; Nehrkorn, Thomas; Zahniser, Mark S.; Jackson, Robert B.; Phillips, Nathan; Wofsy, Steven C.

    2015-01-01

    Methane emissions from natural gas delivery and end use must be quantified to evaluate the environmental impacts of natural gas and to develop and assess the efficacy of emission reduction strategies. We report natural gas emission rates for 1 y in the urban region of Boston, using a comprehensive atmospheric measurement and modeling framework. Continuous methane observations from four stations are combined with a high-resolution transport model to quantify the regional average emission flux, 18.5 ± 3.7 (95% confidence interval) g CH4?m?2?y?1. Simultaneous observations of atmospheric ethane, compared with the ethane-to-methane ratio in the pipeline gas delivered to the region, demonstrate that natural gas accounted for ?60–100% of methane emissions, depending on season. Using government statistics and geospatial data on natural gas use, we find the average fractional loss rate to the atmosphere from all downstream components of the natural gas system, including transmission, distribution, and end use, was 2.7 ± 0.6% in the Boston urban region, with little seasonal variability. This fraction is notably higher than the 1.1% implied by the most closely comparable emission inventory. PMID:25617375

  5. Methane emissions from natural gas infrastructure and use in the urban region of Boston, Massachusetts.

    PubMed

    McKain, Kathryn; Down, Adrian; Raciti, Steve M; Budney, John; Hutyra, Lucy R; Floerchinger, Cody; Herndon, Scott C; Nehrkorn, Thomas; Zahniser, Mark S; Jackson, Robert B; Phillips, Nathan; Wofsy, Steven C

    2015-02-17

    Methane emissions from natural gas delivery and end use must be quantified to evaluate the environmental impacts of natural gas and to develop and assess the efficacy of emission reduction strategies. We report natural gas emission rates for 1 y in the urban region of Boston, using a comprehensive atmospheric measurement and modeling framework. Continuous methane observations from four stations are combined with a high-resolution transport model to quantify the regional average emission flux, 18.5 ± 3.7 (95% confidence interval) g CH4 ? m(-2) ? y(-1). Simultaneous observations of atmospheric ethane, compared with the ethane-to-methane ratio in the pipeline gas delivered to the region, demonstrate that natural gas accounted for ? 60-100% of methane emissions, depending on season. Using government statistics and geospatial data on natural gas use, we find the average fractional loss rate to the atmosphere from all downstream components of the natural gas system, including transmission, distribution, and end use, was 2.7 ± 0.6% in the Boston urban region, with little seasonal variability. This fraction is notably higher than the 1.1% implied by the most closely comparable emission inventory. PMID:25617375

  6. LANDFILL OPERATION FOR CARBON SEQUESTRATION AND MAXIMUM METHANE EMISSION CONTROL

    SciTech Connect

    Don Augenstein; Ramin Yazdani; Rick Moore; Michelle Byars; Jeff Kieffer; Professor Morton Barlaz; Rinav Mehta

    2000-02-26

    Controlled landfilling is an approach to manage solid waste landfills, so as to rapidly complete methane generation, while maximizing gas capture and minimizing the usual emissions of methane to the atmosphere. With controlled landfilling, methane generation is accelerated to more rapid and earlier completion to full potential by improving conditions (principally moisture, but also temperature) to optimize biological processes occurring within the landfill. Gas is contained through use of surface membrane cover. Gas is captured via porous layers, under the cover, operated at slight vacuum. A field demonstration project has been ongoing under NETL sponsorship for the past several years near Davis, CA. Results have been extremely encouraging. Two major benefits of the technology are reduction of landfill methane emissions to minuscule levels, and the recovery of greater amounts of landfill methane energy in much shorter times, more predictably, than with conventional landfill practice. With the large amount of US landfill methane generated, and greenhouse potency of methane, better landfill methane control can play a substantial role both in reduction of US greenhouse gas emissions and in US renewable energy. The work described in this report, to demonstrate and advance this technology, has used two demonstration-scale cells of size (8000 metric tons [tonnes]), sufficient to replicate many heat and compaction characteristics of larger ''full-scale'' landfills. An enhanced demonstration cell has received moisture supplementation to field capacity. This is the maximum moisture waste can hold while still limiting liquid drainage rate to minimal and safely manageable levels. The enhanced landfill module was compared to a parallel control landfill module receiving no moisture additions. Gas recovery has continued for a period of over 4 years. It is quite encouraging that the enhanced cell methane recovery has been close to 10-fold that experienced with conventional landfills. This is the highest methane recovery rate per unit waste, and thus progress toward stabilization, documented anywhere for such a large waste mass. This high recovery rate is attributed to moisture, and elevated temperature attained inexpensively during startup. Economic analyses performed under Phase I of this NETL contract indicate ''greenhouse cost effectiveness'' to be excellent. Other benefits include substantial waste volume loss (over 30%) which translates to extended landfill life. Other environmental benefits include rapidly improved quality and stabilization (lowered pollutant levels) in liquid leachate which drains from the waste.

  7. 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.

  8. 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...

  9. 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.

  10. Assessment of nitrous oxide and methane emissions for California agriculture

    NASA Astrophysics Data System (ADS)

    Horwath, W. R.; Burger, M.; Assa, Y.; Wilson, T. J.

    2012-12-01

    The California Global Warming Solutions Act of 2006 (AB 32) mandates comprehensive strategies to reduce nitrous oxide (N2O) and methane (CH4) emissions. In agriculture crop production, sources of N2O are related to nitrogen fertilization while CH4 emission is associated with rice production. More than half the GHG emissions from agriculture are attributed to N2O production. Currently, baseline N2O emission data for most cropping systems in the State is lacking. Estimates of CH4 emission in rice have been established from previous studies, but a lack of information exists for its expansion into the San Joaquin Delta to address subsidence issues. The paucity of N2O emission data has hampered biogeochemical modeling efforts. The objectives of this assessment are to (1) measure annual N2O and CH4 emissions for major California crops (vineyards, almonds, tomato, wheat, alfalfa, lettuce, and rice) under typical management practices, (2) characterize the effects of environmental factors on the temporal profile of N2O and CH4 emissions, and (3) determine N2O emission factors. The growth of rice in Delta peat soils produced highly variable CH4 emissions depending on tillage intensity. In 2010, standard tillage produced 184 kg CH4-C/ha while in 2011 after deep plowing placing rice residue deeper into the soil, only 26 kg CH4-C/ha was observed. In processing tomato systems, an average 2.5 kg N2O-N/ha was emitted with standard fertilization (160 kg N / ha), similar to background emissions and those from a drip irrigated system, while 4.0 to 5.8 kg N2O-N /ha y-1 was emitted at fertilizer rates of 225 and 300 kg N /ha (see Fig. 1 for example of temporal sources of emissions). About half the annual emissions were emitted within 3 d after the first seasonal rainfall event. In other tomato studies, estimated losses of fertilizer N as N2O were 0.38 ± 0.03 kg/ha y-1 in a drip irrigated system and 1.79 ± 0.21 kg/ha y-1 in furrow irrigated system, which was equivalent to 0.19% and 0.73% of the added fertilizer, respectively. In a lettuce production system, annual N2O emissions were about 1 kg N2O-N /ha y-1. In a wheat system, emissions during the growing season in the rainy season were between 1.0 and 1.5 kg N2O-N, with highest emissions occurring after anhydrous ammonium applications. Older alfalfa fields were larger sources of N2O. This two-year dataset will serve as the basis for developing mitigation practices.igure 1. Nitrous oxide emissions in tomato systems in 2009/10 during the rainy season, between starter and sidedress application of fertilizers, during the growing season and after the first rainfall after harvest.

  11. Methodology of Estimation of Methane Emissions from Coal Mines in Poland

    NASA Astrophysics Data System (ADS)

    Paty?ska, Renata

    2014-03-01

    Based on a literature review concerning methane emissions in Poland, it was stated in 2009 that the National Greenhouse Inventory 2007 [13] was published. It was prepared firstly to meet Poland's obligations resulting from point 3.1 Decision no. 280/2004/WE of the European Parliament and of the Council of 11 February 2004, concerning a mechanism for monitoring community greenhouse gas emissions and for implementing the Kyoto Protocol and secondly, for the United Nations Framework Convention on Climate Change (UNFCCC) and Kyoto Protocol. The National Greenhouse Inventory states that there are no detailed data concerning methane emissions in collieries in the Polish mining industry. That is why the methane emission in the methane coal mines of Górno?l?skie Zag??bie W?glowe - GZW (Upper Silesian Coal Basin - USCB) in Poland was meticulously studied and evaluated. The applied methodology for estimating methane emission from the GZW coal mining system was used for the four basic sources of its emission. Methane emission during the mining and post-mining process. Such an approach resulted from the IPCC guidelines of 2006 [10]. Updating the proposed methods (IPCC2006) of estimating the methane emissions of hard coal mines (active and abandoned ones) in Poland, assumes that the methane emission factor (EF) is calculated based on methane coal mine output and actual values of absolute methane content. The result of verifying the method of estimating methane emission during the mining process for Polish coal mines is the equation of methane emission factor EF.

  12. An integrated approach for estimation of methane emissions from wetlands and lakes in high latitude regions

    NASA Astrophysics Data System (ADS)

    Chiu, C.; Bowling, L. C.; Podest, E.; Bohn, T. J.; Lettenmaier, D. P.; Schroeder, R.; McDonald, K. C.

    2009-04-01

    In recent years, there has been increasing evidence of significant alteration in the extent of lakes and wetlands in high latitude regions due in part to thawing permafrost, as well as other changes governing surface and subsurface hydrology. Methane is a 23 times more efficient greenhouse gas than carbon dioxide; changes in surface water extent, and the associated subsurface anaerobic conditions, are important controls on methane emissions in high latitude regions. Methane emissions from wetlands vary substantially in both time and space, and are influenced by plant growth, soil organic matter decomposition, methanogenesis, and methane oxidation controlled by soil temperature, water table level and net primary productivity (NPP). The understanding of spatial and temporal heterogeneity of surface saturation, thermal regime and carbon substrate in northern Eurasian wetlands from point measurements are limited. In order to better estimate the magnitude and variability of methane emissions from northern lakes and wetlands, we present an integrated assessment approach based on remote sensing image classification, land surface modeling and process-based ecosystem modeling. Wetlands classifications based on L-band JERS-1 SAR (100m) and ALOS PALSAR (~30m) are used together with topographic information to parameterize a lake and wetland algorithm in the Variable Infiltration Capacity (VIC) land surface model at 25 km resolution. The enhanced VIC algorithm allows subsurface moisture exchange between surface water and wetlands and includes a sub-grid parameterization of water table position within the wetland area using a generalized topographic index. Average methane emissions are simulated by using the Walter and Heimann methane emission model based on temporally and spatially varying soil temperature, net primary productivity and water table generated from the modified VIC model. Our five preliminary study areas include the Z. Dvina, Upper Volga, Yeloguy, Syum, and Chaya river basins. The temporally-variable inundation extent simulated by the VIC model is compared to 25 km resolution inundation products developed from combined QuikSCAT, AMSR-E and MODIS data sets covering the time period from 2002 onward. The seasonal variation in methane emissions associated with sub-grid variability in water table extent is explored between 1948 and 2006. This work was carried out at Purdue University, at the University of Washington, and at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the NASA.

  13. Methane Emissions from Natural Gas in the Urban Region of Boston, Massachusetts

    NASA Astrophysics Data System (ADS)

    McKain, K.; Down, A.; Raciti, S. M.; Budney, J.; Hutyra, L.; Floerchinger, C. R.; Herndon, S. C.; Zahniser, M. S.; Nehrkorn, T.; Jackson, R. B.; Phillips, N. G.; Wofsy, S. C.

    2014-12-01

    Methane emissions from the natural gas supply chain must be quantified to assess environmental impacts of natural gas and to develop emission reduction strategies. We report natural gas emission rates for one year in the urban region of Boston, MA, using an atmospheric measurement and modeling framework. Continuous methane observations from four stations are combined with a high-resolution transport model to quantify the regional average emission rate, 20.6 ± 1.7 (95 % CI) g CH4 m-2 yr-1. Simultaneous observations of atmospheric ethane, compared with the ethane to methane ratio in pipeline gas, demonstrate that natural gas accounted for 58 - 100 % of methane emissions, depending on season. Using government statistics and geospatial data on energy consumption, we estimate the fractional loss rate to the atmosphere from all downstream components of the natural gas system, including transmission, distribution, and end-use, was 2.9 ± 0.3 % in the Boston urban region, compared to 1.1 % inferred by the Massachusetts greenhouse gas inventory.

  14. Patterns in Wetland Microbial Community Composition and Functional Gene Repertoire Associated with Methane Emissions

    PubMed Central

    He, Shaomei; Malfatti, Stephanie A.; McFarland, Jack W.; Anderson, Frank E.; Pati, Amrita; Huntemann, Marcel; Tremblay, Julien; Glavina del Rio, Tijana; Waldrop, Mark P.; Windham-Myers, Lisamarie

    2015-01-01

    ABSTRACT Wetland restoration on peat islands previously drained for agriculture has potential to reverse land subsidence and sequester atmospheric carbon dioxide as peat accretes. However, the emission of methane could potentially offset the greenhouse gas benefits of captured carbon. As microbial communities play a key role in governing wetland greenhouse gas fluxes, we are interested in how microbial community composition and functions are associated with wetland hydrology, biogeochemistry, and methane emission, which is critical to modeling the microbial component in wetland methane fluxes and to managing restoration projects for maximal carbon sequestration. Here, we couple sequence-based methods with biogeochemical and greenhouse gas measurements to interrogate microbial communities from a pilot-scale restored wetland in the Sacramento-San Joaquin Delta of California, revealing considerable spatial heterogeneity even within this relatively small site. A number of microbial populations and functions showed strong correlations with electron acceptor availability and methane production; some also showed a preference for association with plant roots. Marker gene phylogenies revealed a diversity of major methane-producing and -consuming populations and suggested novel diversity within methanotrophs. Methanogenic archaea were observed in all samples, as were nitrate-, sulfate-, and metal-reducing bacteria, indicating that no single terminal electron acceptor was preferred despite differences in energetic favorability and suggesting spatial microheterogeneity and microniches. Notably, methanogens were negatively correlated with nitrate-, sulfate-, and metal-reducing bacteria and were most abundant at sampling sites with high peat accretion and low electron acceptor availability, where methane production was highest. PMID:25991679

  15. 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.

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

    DOE PAGESBeta

    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.; et al

    2015-06-30

    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 totalmore »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.« less

  17. 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...

  18. 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.

  19. Dark aerobic methane emission associated to leaf factors of two Acacia and five Eucalyptus species

    NASA Astrophysics Data System (ADS)

    Watanabe, Makoto; Watanabe, Yoko; Kim, Yong Suk; Koike, Takayoshi

    2012-07-01

    We sought the biological factors determining variations in the methane emission rates from leaves of different plant species under aerobic conditions. Accordingly, we studied relations between the methane emission rate and leaf traits of two Acacia and five Eucalyptus species. We grew seedlings of each species in a glasshouse and measured the methane emission rate of the detached leaves under dark conditions at 30 °C. At the same time we measured the leaf mass per area (LMA), water content, and concentrations of carbon and nitrogen. There was no correlation between the leaf nitrogen concentration and the methane emission rate. This is consistent with previous findings that enzymatic processes do not influence methane emission. We found a significant negative correlation between LMA and the methane emission rate. Our results suggest that leaf structure is primarily responsible for differences in the rates of aerobic methane emission from leaves of different species.

  20. Ecosystem scale methane emission from a boreal wetland: Annual balances and interannual variability

    NASA Astrophysics Data System (ADS)

    Rinne, J.; Alekseychik, P.; Haapanala, S.; Raivonen, M.; Mammarella, I.; Peltola, O.; Aurela, M.; Pihlatie, M.; Tuittila, E.; Vesala, T.

    2013-12-01

    We have conducted measurements of methane and carbon dioxide exchange between atmosphere and a pristine boreal fen ecosystem, Siikaneva, continuously by eddy covariance technique since 2005. The results show methane emission to be a significant part of the carbon balance of this ecosystem. Methane emission also shows a strong seasonal cycle reflecting the seasonality of the driving variables in boreal regions. Of the environmental parameters, methane emission correlates best with peat temperature, whereas no correlation with water table position is found. The interannual variability of the annual methane emission is relatively low. We will explore the possible drivers of this variability. We also study the contribution of methane to the carbon balance in interannual scale. The effects of methane and carbon dioxide exchange of pristine wetland ecosystems on the radiative forcing will be discussed. Monthly means of ecosystem scale methane emission from Siikaneva fen during 2015-2010, with errorbars indicating standard deviations between years.

  1. Methane emission from mires of the West Siberian taiga

    NASA Astrophysics Data System (ADS)

    Sabrekov, A. F.; Glagolev, M. V.; Kleptsova, I. E.; Machida, T.; Maksyutov, S. S.

    2013-12-01

    In the summer-autumn seasons of 2007-2011, the methane emission from typical mire landscapes of Western Siberia was studied using the static chamber method. The lowest methane flux turned out to be characteristic of the ryams (pine-dwarf shrub-sphagnum associations) and the ridges of the ridge-hollow complexes, as well as of the wetland lakes in the northern and middle taiga (the medians are within the range of 0.1-0.5 mg C-CH4/m2 h). Values that are 10 times higher are typical for the oligotrophic hollows, fens, peat mats, and poor fens in different subzones (the medians are 2 to 7 mg C-CH4/m2 h). The maximal values of the methane flux from the wetland lakes of the southern taiga are 17.98 mg C-CH4/m2 h. Based on the data obtained by the authors, along with the previously published ones, the regional methane fluxes from the taiga mires were calculated: 2.22 Mt C-CH4/m2 per year, or about 80% of the total methane flux from the West Siberian mires. The estimates of the CH4 regional flux obtained by other researchers are discussed; the main source of the estimation uncertainty is analyzed.

  2. Reducing Uncertainty in Methane Emission Estimates from Permafrost Environments

    NASA Astrophysics Data System (ADS)

    Christensen, T. R.; Mastepanov, M.; Lund, M.; Tamstorf, M. P.; Parmentier, F. J. W.; Rysgård, S.; Lilienthal, A. J.

    2014-12-01

    Depending on factors including temperature, snow duration and soil moisture conditions, emissions of the greenhouse gas methane from permafrost wetlands can vary by factors of 2-4 between years. This variability is clear in atmospheric measurements of the gas, but a lack of ground-based data is making it hard to locate the methane sources responsible. Methane monitoring in the Arctic is expensive, requiring sophisticated analysis equipment such as power requiring laser spectrometer analysis made in remote places. This also puts demands on the logistics where infrastructures and field stations that offer line-power in the field are in high demand but very rarely found. Research projects therefore typically focus on one site, and run for a year or two. Longer term monitoring programs, which document climate, hydrology, phenology and population dynamics of birds and mammals, rarely include carbon fluxes since it is technically challenging to measure. One that does is the Greenland Ecosystem Monitoring program that started at the Zackenberg research station, which has recorded substantial methane flux variations for almost a decade in North-east Greenland. Such multi-year studies show that, while there is some connection between the amounts of methane released from one year to the next, accurate forecasting is difficult. They also highlight the importance of extending monitoring beyond the growing period into the frozen season, both in spring and autumn. A spatially distributed network of long-term monitoring stations in the Arctic, with consistency between measurements, is badly needed to improve this situation. Productive methane 'hot spots', many sporadic, have also been identified in recent studies. By ventilating surface waters, storms trigger emissions in the East Siberian Sea Shelf. Shallow lakes formed when permafrost thaws can belch methane from decomposing old organic deposits, of which there are huge amounts in the Arctic. All of these potentially important emissions are of a scale that still is in need of being reconciled with the atmospheric record. This presentation will give an overview of novel approaches including robot techniques ground-, boat- and airborne-based to reduce uncertainty in particular in relation to these 'hot spot' emissions.

  3. High rates of methane emissions from south taiga wetland ponds.

    NASA Astrophysics Data System (ADS)

    Glagolev, M.; Kleptsova, I.; Maksyutov, S.

    2012-04-01

    Since wetland ponds are often assumed to be insignificant sources of methane, there is a limited data about its fluxes. In this study, we found surprisingly high rates of methane emission at several shallow ponds in the south taiga zone of West Siberia. Wetland ponds within the Great Vasyugan Mire ridge-hollow-pool patterned bog system were investigated. 22 and 24 flux measurements from ponds and surrounded mires, respectively, were simultaneously made by a static chamber method in July, 2011. In contrast to previous measurements, fluxes were measured using the small boat with floated chamber to avoid disturbance to the water volume. Since the ebullition is most important emission pathway, minimization of physical disturbance provoking gas bubbling significantly increases the data accuracy. Air temperature varied from 15 to 22° C during the measurements, and pH at different pond depths - from 4.4 to 5. As it was found, background emission from surrounding ridges and hollows was 1.7/2.6/3.3 mgC·m-2·h1 (1st/2nd/3rd quartiles). These rates are in a perfect correspondence with the typical methane emission fluxes from other south taiga bogs. Methane emission from wetland ponds turned out to be by order of magnitude higher (9.3/11.3/15.6 mgC·m-2·h1). Comparing to other measurements in West Siberia, many times higher emissions (70.9/111.6/152.3 mgC·m-2·h1) were found in forest-steppe and subtaiga fen ponds. On the contrary, West Siberian tundra lakes emit methane insignificantly, with the flux rate close to surrounding wetlands (about 0.2-0.3 mgC·m-2·h1). Apparently, there is a naturally determined distribution of ponds with different flux rates over different West Siberia climate-vegetation zones. Further investigations aiming at revelation of the zones with different fluxes would be helpful for total flux revision purposes. With respect to other studies, high emission rates were already detected, for instance, in Baltic ponds (Dzyuban, 2002) and U.K. lakes (Casper et al., 2000). Annual CH4 emission from West Siberia south taiga ponds with area of 0.6·106 Mha was estimated to be 0.26 MtCH4·yr-1.

  4. Methane emission by Nellore cattle subjected to different nutritional plans.

    PubMed

    Cota, Olinta Leone; de Figueiredo, Darcilene Maria; Branco, Renata Helena; Magnani, Elaine; do Nascimento, Cleisy Ferreira; de Oliveira, Luiza Freitas; Mercadante, Maria Eugênia Zerlotti

    2014-10-01

    The objective was to evaluate the emission of enteric methane by Nellore cattle subjected to different nutritional plans, as well as the intake and digestibility of nutrients from the diets supplied. Forty-seven animals in a confinement system (feedlot) were fed a corn silage-based diet for 35 days. Afterwards, these animals were evaluated in a grazing system during the rainy periods, in Urochloa brizantha cv Marandu paddocks, for 44 days. Chromic oxide was used as external marker to estimate the fecal production of animals. Samples of feces, ingredients, and pasture were collected and sampled for subsequent chemical analyses. The SF6 tracer gas technique was adopted to quantify the methane gas emitted by the animals. The experimental design was completely randomized, using procedure GLM of software SAS (9.2), including the fixed effects of sex and nutritional plan and the linear effect of the co-variable weights. Means were analyzed by Tukey's test at 5 % probability. The intakes of total dry matter and organic matter were greater for the animals subjected to the feedlot diet (P?Emission of CH4/day (104.01 g) by the animals fed the feedlot diet (P?methane production (CH4/CEB) and methane emission per dry matter consumed were lower in relation to the grazing treatment (3.75 vs 4.23 % and 11.67 vs 15.71 g/kg). The better quality of the diet in the feedlot promoted lower energy losses as methane. PMID:25224394

  5. Wetlands and methane emission in the XXI century: RCM-based projection for Northern Eurasia

    NASA Astrophysics Data System (ADS)

    Pikaleva, A.

    2012-04-01

    Russia has largest resources of wetlands in the world. Marshes and forested swamps occupy up to 20% of country's territory. The role of wetlands in the natural processes and human society is multifunctional: from providing wildlife habitat and biodiversity to determining water filtration and runoff control. Wetland is an important agent in the global cycling of greenhouse gases. Their exchanges with the atmosphere affects to the regional and global climates thus represent an essential component of environment. In this study the changes in the spatial distributions of wetlands and methane emission are evaluated using the output from MGO GCM/RCM future climate projection. The calculations were performed for the late 20th century (1981-2000) and mid 21st century (2041-2060) under IPCC A2 GHG/aerosols emission scenario. Several characteristics including moisture coefficient and water table have been analysed in order to describe wetland distribution across Eurasia. It has been found that there is a considerable uncertainty in distributions of the analysed characteristics that complicates wetland identification. The water table depth has been adopted to approximate observed distribution of wetlands. As projected by the regional climate model for the mid 21st century the wetland area will expand, notably in May and September and shrink in summer. Evaluated are methane emissions for the late 20th century over wetlands and its possible changes by the mid 21st century. According to RCM projection the methane emission will likely increase in the forthcoming 50 years due to climate warming by approximately 30%. Modeling deficiencies in the wetland distributions and methane emission calculations are discussed. An attention in the analysis is also given to the expected changes in the methane emission potential due to taliks and lakes.

  6. Estimating daily methane production in individual cattle with irregular feed intake patterns from short-term methane emission measurements.

    PubMed

    Cottle, D J; Velazco, J; Hegarty, R S; Mayer, D G

    2015-12-01

    Spot measurements of methane emission rate (n = 18 700) by 24 Angus steers fed mixed rations from GrowSafe feeders were made over 3- to 6-min periods by a GreenFeed emission monitoring (GEM) unit. The data were analysed to estimate daily methane production (DMP; g/day) and derived methane yield (MY; g/kg dry matter intake (DMI)). A one-compartment dose model of spot emission rate v. time since the preceding meal was compared with the models of Wood (1967) and Dijkstra et al. (1997) and the average of spot measures. Fitted values for DMP were calculated from the area under the curves. Two methods of relating methane and feed intakes were then studied: the classical calculation of MY as DMP/DMI (kg/day); and a novel method of estimating DMP from time and size of preceding meals using either the data for only the two meals preceding a spot measurement, or all meals for 3 days prior. Two approaches were also used to estimate DMP from spot measurements: fitting of splines on a 'per-animal per-day' basis and an alternate approach of modelling DMP after each feed event by least squares (using Solver), summing (for each animal) the contributions from each feed event by best-fitting a one-compartment model. Time since the preceding meal was of limited value in estimating DMP. Even when the meal sizes and time intervals between a spot measurement and all feeding events in the previous 72 h were assessed, only 16.9% of the variance in spot emission rate measured by GEM was explained by this feeding information. While using the preceding meal alone gave a biased (underestimate) of DMP, allowing for a longer feed history removed this bias. A power analysis taking into account the sources of variation in DMP indicated that to obtain an estimate of DMP with a 95% confidence interval within 5% of the observed 64 days mean of spot measures would require 40 animals measured over 45 days (two spot measurements per day) or 30 animals measured over 55 days. These numbers suggest that spot measurements could be made in association with feed efficiency tests made over 70 days. Spot measurements of enteric emissions can be used to define DMP but the number of animals and samples are larger than are needed when day-long measures are made. PMID:26301870

  7. Revisiting factors controlling methane emissions from high-arctic tundra

    NASA Astrophysics Data System (ADS)

    Mastepanov, Mikhail; Sigsgaard, Charlotte; Tagesson, Torbern; Strom, Lena; Tamstorf, Mikkel; Lund, Magnus; Christensen, Torben

    2013-04-01

    Among the numerous studies of methane emission from northern wetlands the number of measurements carried on at high latitudes (north of the Arctic Circle) is very limited, and within these there is a bias towards studies of the growing season. Here we present results of five years of automatic chamber measurements at a high-arctic location in Zackenberg, NE Greenland, covering both the growing seasons and two months of the following freeze-in period. The measurements show clear seasonal dynamics in methane emission. In the beginning of the growing season increase in CH4 fluxes was strongly related to the date of snow melt. The greatest variation in fluxes between the study years were observed during the first part of the growing season. Somewhat surprisingly this variability could not be explained by commonly known factors controlling methane emission, i.e. temperature and water table position. Late in the growing season CH4 emissions were found to be very similar between the study years (except the extremely dry 2010) despite large differences in climatic factors (temperature and water table). Late-season bursts of CH4 coinciding with soil freezing in the autumn were observed at least during three out of five years 2006 - 2010. The accumulated emission during the freeze-in CH4 bursts was comparable in size with the growing season emission for the year 2007, and about one third of the growing season emissions for the years 2009 and 2010. In all three cases the CH4 burst was accompanied by a corresponding episodic increase in CO2 emission, which can compose a significant contribution to the annual CO2 flux budget. The most probable mechanism of the late season CH4 and CO2 bursts is physical release of gases, accumulated in the soil during the growing season. In this study we investigate the drivers and links between growing season and late season fluxes. The reported surprising seasonal dynamics of CH4 emissions at this site show that there are important occasions where conventional knowledge on factors controlling methane emissions is overruled by other processes, acting in longer than seasonal time scales. Our findings suggest the importance of multiyear studies with continued focus on shoulder seasons.

  8. A simple model for estimating methane concentration and lifetime variations

    SciTech Connect

    Osborn, T.J.; Wigley, T.M.L.

    1994-01-01

    A simple methane model is presented in which lifetime chances are expressed as a function of CH{sub 4} concentration and emissions of NO{sub x}, CO and NMHCs. The model parameters define the relative sensitivities of lifetime to these determining factors. The parameterized model is fitted to results from five more complex atmospheric chemistry models and to 1990 IPCC concentration projections. The IPCC data and four of the five models are well fitted, implying that the models have similar relative sensitivities. However, overall sensitivities of lifetime to changes in atmospheric composition vary widely from model to model. The parameterized model is used to estimate the history of past methane emissions, lifetime changes and OH variations, with estimates of uncertainties. The pre-industrial lifetime is estimated to be 15-34% lower than today. This implies that 23-55% of past concentration changes are due to lifetime changes. Pre-industrial emissions are found to be much higher (220-330 TgCH{sub 4}/y) than the best estimate of present natural emissions (155 TgCH{sub 4}/{gamma}). The change in emissions since pre-industrial times is estimated to lie in the range 160-260 TgCH{sub 4}/y, compared with the current best values for anthropogenic emissions of 360 TgCH{sub 4}/y. These results imply either that current estimates of anthropogenic emissions are too high and/or that there have been large changes in natural emissions. 1992 IPCC emissions scenarios are used to give projections of future concentration and lifetime changes, together with their uncertainties. For any given emissions scenario, these uncertainties are large. In terms of future radiative forcing and global-mean temperature changes over 1990-2100 they correspond to uncertainties of at least {+-}0.2 Wm{sup -2} and {+-}0.1{degrees}C, respectively. 35 refs., 11 figs., 5 tabs.

  9. Patterns in wetland microbial community composition and functional gene repertoire associated with methane emissions

    DOE PAGESBeta

    He, Shaomei; Malfatti, Stephanie A.; McFarland, Jack W.; Anderson, Frank E.; Pati, Amrita; Huntemann, Marcel; Tremblay, Julien; Glavina del Rio, Tijana; Waldrop, Mark P.; Windham-Myers, Lisamarie; et al

    2015-05-19

    Wetland restoration on peat islands previously drained for agriculture has potential to reverse land subsidence and sequester atmospheric carbon dioxide as peat accretes. However, the emission of methane could potentially offset the greenhouse gas benefits of captured carbon. As microbial communities play a key role in governing wetland greenhouse gas fluxes, we are interested in how microbial community composition and functions are associated with wetland hydrology, biogeochemistry, and methane emission, which is critical to modeling the microbial component in wetland methane fluxes and to managing restoration projects for maximal carbon sequestration. Here, we couple sequence-based methods with biogeochemical and greenhousemore »gas measurements to interrogate microbial communities from a pilot-scale restored wetland in the Sacramento-San Joaquin Delta of California, revealing considerable spatial heterogeneity even within this relatively small site. A number of microbial populations and functions showed strong correlations with electron acceptor availability and methane production; some also showed a preference for association with plant roots. Marker gene phylogenies revealed a diversity of major methane-producing and -consuming populations and suggested novel diversity within methanotrophs. Methanogenic archaea were observed in all samples, as were nitrate-, sulfate-, and metal-reducing bacteria, indicating that no single terminal electron acceptor was preferred despite differences in energetic favorability and suggesting spatial microheterogeneity and microniches. Notably, methanogens were negatively correlated with nitrate-, sulfate-, and metal-reducing bacteria and were most abundant at sampling sites with high peat accretion and low electron acceptor availability, where methane production was highest. Wetlands are the largest nonanthropogenic source of atmospheric methane but also a key global carbon reservoir. Characterizing belowground microbial communities that mediate carbon cycling in wetlands is critical to accurately predicting their responses to changes in land management and climate. Here, we studied a restored wetland and revealed substantial spatial heterogeneity in biogeochemistry, methane production, and microbial communities, largely associated with the wetland hydraulic design. We observed patterns in microbial community composition and functions correlated with biogeochemistry and methane production, including diverse microorganisms involved in methane production and consumption. We found that methanogenesis gene abundance is inversely correlated with genes from pathways exploiting other electron acceptors, yet the ubiquitous presence of genes from all these pathways suggests that diverse electron acceptors contribute to the energetic balance of the ecosystem. These investigations represent an important step toward effective management of wetlands to reduce methane flux to the atmosphere and enhance belowground carbon storage.« less

  10. Patterns in wetland microbial community composition and functional gene repertoire associated with methane emissions

    SciTech Connect

    He, Shaomei; Malfatti, Stephanie A.; McFarland, Jack W.; Anderson, Frank E.; Pati, Amrita; Huntemann, Marcel; Tremblay, Julien; Glavina del Rio, Tijana; Waldrop, Mark P.; Windham-Myers, Lisamarie; Tringe, Susannah G.

    2015-05-19

    Wetland restoration on peat islands previously drained for agriculture has potential to reverse land subsidence and sequester atmospheric carbon dioxide as peat accretes. However, the emission of methane could potentially offset the greenhouse gas benefits of captured carbon. As microbial communities play a key role in governing wetland greenhouse gas fluxes, we are interested in how microbial community composition and functions are associated with wetland hydrology, biogeochemistry, and methane emission, which is critical to modeling the microbial component in wetland methane fluxes and to managing restoration projects for maximal carbon sequestration. Here, we couple sequence-based methods with biogeochemical and greenhouse gas measurements to interrogate microbial communities from a pilot-scale restored wetland in the Sacramento-San Joaquin Delta of California, revealing considerable spatial heterogeneity even within this relatively small site. A number of microbial populations and functions showed strong correlations with electron acceptor availability and methane production; some also showed a preference for association with plant roots. Marker gene phylogenies revealed a diversity of major methane-producing and -consuming populations and suggested novel diversity within methanotrophs. Methanogenic archaea were observed in all samples, as were nitrate-, sulfate-, and metal-reducing bacteria, indicating that no single terminal electron acceptor was preferred despite differences in energetic favorability and suggesting spatial microheterogeneity and microniches. Notably, methanogens were negatively correlated with nitrate-, sulfate-, and metal-reducing bacteria and were most abundant at sampling sites with high peat accretion and low electron acceptor availability, where methane production was highest. Wetlands are the largest nonanthropogenic source of atmospheric methane but also a key global carbon reservoir. Characterizing belowground microbial communities that mediate carbon cycling in wetlands is critical to accurately predicting their responses to changes in land management and climate. Here, we studied a restored wetland and revealed substantial spatial heterogeneity in biogeochemistry, methane production, and microbial communities, largely associated with the wetland hydraulic design. We observed patterns in microbial community composition and functions correlated with biogeochemistry and methane production, including diverse microorganisms involved in methane production and consumption. We found that methanogenesis gene abundance is inversely correlated with genes from pathways exploiting other electron acceptors, yet the ubiquitous presence of genes from all these pathways suggests that diverse electron acceptors contribute to the energetic balance of the ecosystem. These investigations represent an important step toward effective management of wetlands to reduce methane flux to the atmosphere and enhance belowground carbon storage.

  11. Measurements of Methane Emissions and Volatile Organic Compounds from Shale Gas Operations in the Marcellus Shale

    NASA Astrophysics Data System (ADS)

    Omara, M.; Subramanian, R.; Sullivan, M.; Robinson, A. L.; Presto, A. A.

    2014-12-01

    The Marcellus Shale is the most expansive shale gas reserve in play in the United States, representing an estimated 17 to 29 % of the total domestic shale gas reserves. The rapid and extensive development of this shale gas reserve in the past decade has stimulated significant interest and debate over the climate and environmental impacts associated with fugitive releases of methane and other pollutants, including volatile organic compounds. However, the nature and magnitude of these pollutant emissions remain poorly characterized. This study utilizes the tracer release technique to characterize total fugitive methane release rates from natural gas facilities in southwestern Pennsylvania and West Virginia that are at different stages of development, including well completion flowbacks and active production. Real-time downwind concentrations of methane and two tracer gases (acetylene and nitrous oxide) released onsite at known flow rates were measured using a quantum cascade tunable infrared laser differential absorption spectrometer (QC-TILDAS, Aerodyne, Billerica, MA) and a cavity ring down spectrometer (Model G2203, Picarro, Santa Clara, CA). Evacuated Silonite canisters were used to sample ambient air during downwind transects of methane and tracer plumes to assess volatile organic compounds (VOCs). A gas chromatograph with a flame ionization detector was used to quantify VOCs following the EPA Method TO-14A. A preliminary assessment of fugitive emissions from actively producing sites indicated that methane leak rates ranged from approximately 1.8 to 6.2 SCFM, possibly reflecting differences in facility age and installed emissions control technology. A detailed comparison of methane leak rates and VOCs emissions with recent published literature for other US shale gas plays will also be discussed.

  12. 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.

  13. Methane mitigation in cities: how new measurements and partnerships can contribute to emissions reduction strategies

    NASA Astrophysics Data System (ADS)

    Hopkins, F. M.; Bush, S. E.; Ehleringer, J. R.; Lai, C. T.; Rambo, J. P.; Wiggins, E. B.; Miu, J. C. L.; Carranza, V.; Randerson, J. T.

    2014-12-01

    Cities generate a large fraction of anthropogenic methane emissions that are increasing with urbanization and greater reliance on natural gas as fuel. New measurements of methane in cities suggest an as-yet unrealized potential for city-scale methane mitigation. We present high-resolution methane observations from four cities in North America to demonstrate the utility of methane surveys for identifying urban methane sources. We used portable, continuous on-road measurements to determine the spatial distribution of methane in Fairbanks, Los Angeles, Salt Lake City, and San Diego. Across cities, methane tended to be highly concentrated in space, suggesting discrete, point emission sources. Elevated methane levels were found near known emission sources, such as landfills, wastewater treatment facilities, and natural gas-fueled power plants, and revealed the location of fugitive leaks in natural gas infrastructure. The mix of sources and sizes of methane leaks varied among cities, highlighting a need for locally adaptive emissions regulation. Urban methane observations can inform anthropogenic processes in development of methane mitigation strategies. We discuss specific examples of how continuous atmospheric measurements can enhance the design of mitigation strategies in these cities, and potential contributions of these approaches to cross-sectoral efforts to reduce methane emissions at the city level.

  14. Methane emissions from tropical wetlands in LPX: Algorithm development and validation using atmospheric measurements

    NASA Astrophysics Data System (ADS)

    Houweling, S.; Ringeval, B.; Basu, A.; Van Beek, L. P.; Van Bodegom, P.; Spahni, R.; Gatti, L.; Gloor, M.; Roeckmann, T.

    2013-12-01

    Tropical wetlands are an important and highly uncertain term in the global budget of methane. Unlike wetlands in higher latitudes, which are dominated by water logged peatlands, tropical wetlands consist primarily of inundated river floodplains responding seasonally to variations in river discharge. Despite the fact that the hydrology of these systems is obviously very different, process models used for estimating methane emissions from wetlands commonly lack a dedicated parameterization for the tropics. This study is a first attempt to develop such a parameterization for use in the global dynamical vegetation model LPX. The required floodplain extents and water depth are calculated offline using the global hydrological model PCR-GLOBWB, which includes a sophisticated river routing scheme. LPX itself has been extended with a dedicated floodplain land unit and flood tolerant PFTs. The simulated species competition and productivity have been verified using GLC2000 and MODIS, pointing to directions for further model improvement regarding vegetation dynamics and hydrology. LPX simulated methane fluxes have been compared with available in situ measurements from tropical America. Finally, estimates for the Amazon basin have been implemented in the TM5 atmospheric transport model and compared with aircraft measured vertical profiles. The first results that will be presented demonstrate that, despite the limited availability of measurements, useful constraints on the magnitude and seasonality of Amazonian methane emissions can be derived.

  15. Analysis of uncertainties in the estimates of nitrous oxide and methane emissions in the UK's greenhouse gas inventory for agriculture

    NASA Astrophysics Data System (ADS)

    Milne, Alice E.; Glendining, Margaret J.; Bellamy, Pat; Misselbrook, Tom; Gilhespy, Sarah; Rivas Casado, Monica; Hulin, Adele; van Oijen, Marcel; Whitmore, Andrew P.

    2014-01-01

    The UK's greenhouse gas inventory for agriculture uses a model based on the IPCC Tier 1 and Tier 2 methods to estimate the emissions of methane and nitrous oxide from agriculture. The inventory calculations are disaggregated at country level (England, Wales, Scotland and Northern Ireland). Before now, no detailed assessment of the uncertainties in the estimates of emissions had been done. We used Monte Carlo simulation to do such an analysis. We collated information on the uncertainties of each of the model inputs. The uncertainties propagate through the model and result in uncertainties in the estimated emissions. Using a sensitivity analysis, we found that in England and Scotland the uncertainty in the emission factor for emissions from N inputs (EF1) affected uncertainty the most, but that in Wales and Northern Ireland, the emission factor for N leaching and runoff (EF5) had greater influence. We showed that if the uncertainty in any one of these emission factors is reduced by 50%, the uncertainty in emissions of nitrous oxide reduces by 10%. The uncertainty in the estimate for the emissions of methane emission factors for enteric fermentation in cows and sheep most affected the uncertainty in methane emissions. When inventories are disaggregated (as that for the UK is) correlation between separate instances of each emission factor will affect the uncertainty in emissions. As more countries move towards inventory models with disaggregation, it is important that the IPCC give firm guidance on this topic.

  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. Methane emission from a boreal wetland: Annual balances, interannual variability, and effect on radiative forcing

    NASA Astrophysics Data System (ADS)

    Rinne, J.; Haapanala, S.; Mammarella, I.; Peltola, O.; Aurela, M.; Pihlatie, M.; Tuittila, E.; Vesala, T.

    2012-12-01

    We have conducted measurements of methane emission from a pristine boreal fen ecosystem, Siikaneva, continuously by eddy covariance technique since 2005. As already reported after the first year of measurements, methane emission is a significant part of the carbon balance of this ecosystem. Methane emission also shows a strong seasonal cycle reflecting the seasonality of the driving variables in this climatic region. Of the environmental parameters, methane emission correlates best with peat temperature, whereas no correlation with water table position is found. Using the dataset covering several years we explore the interannual variability of the methane emission and the possible drivers of this variability. We also study the contribution of methane to the carbon balance in interannual scale. The proper metric to compare the effects of methane and carbon dioxide exchange of pristine wetland ecosystems on the radiative forcing will be discussed.

  18. Potential Cost-Effective Opportunities for Methane Emission Abatement

    SciTech Connect

    Warner, Ethan; Steinberg, Daniel; Hodson, Elke; Heath, Garvin

    2015-08-01

    The energy sector was responsible for approximately 84% of carbon dioxide equivalent (CO2e) greenhouse gas (GHG) emissions in the U.S. in 2012 (EPA 2014a). Methane is the second most important GHG, contributing 9% of total U.S. CO2e emissions. A large portion of those methane emissions result from energy production and use; the natural gas, coal, and oil industries produce approximately 39% of anthropogenic methane emissions in the U.S. As a result, fossil-fuel systems have been consistently identified as high priority sectors to contribute to U.S. GHG reduction goals (White House 2015). Only two studies have recently attempted to quantify the abatement potential and cost associated with the breadth of opportunities to reduce GHG emissions within natural gas, oil, and coal supply chains in the United States, namely the U.S. Environmental Protection Agency (EPA) (2013a) and ICF (2014). EPA, in its 2013 analysis, estimated the marginal cost of abatement for non-CO2 GHG emissions from the natural gas, oil, and coal supply chains for multiple regions globally, including the United States. Building on this work, ICF International (ICF) (2014) provided an update and re-analysis of the potential opportunities in U.S. natural gas and oil systems. In this report we synthesize these previously published estimates as well as incorporate additional data provided by ICF to provide a comprehensive national analysis of methane abatement opportunities and their associated costs across the natural gas, oil, and coal supply chains. Results are presented as a suite of marginal abatement cost curves (MACCs), which depict the total potential and cost of reducing emissions through different abatement measures. We report results by sector (natural gas, oil, and coal) and by supply chain segment - production, gathering and boosting, processing, transmission and storage, or distribution - to facilitate identification of which sectors and supply chain segments provide the greatest opportunities for low cost abatement.

  19. 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.

  20. Trends and Patterns in a New Time Series of Natural and Anthropogenic Methane Emissions, 1980-2000

    NASA Astrophysics Data System (ADS)

    Matthews, E.; Bruhwiler, L.; Themelis, N. J.

    2007-12-01

    We report on a new time series of methane (CH4) emissions from anthropogenic and natural sources developed for a multi-decadal methane modeling study (see following presentation by Bruhwiler et al.). The emission series extends from 1980 through the early 2000s with annual emissions for all countries has several features distinct from the source histories based on IPCC methods typically employed in modeling the global methane cycle. Fossil fuel emissions rely on 7 fuel-process emission combinations and minimize reliance on highly-uncertain emission factors. Emissions from ruminant animals employ regional profiles of bovine populations that account for the influence of variable age- and size-demographics on emissions and are ~15% lower than other estimates. Waste-related emissions are developed using an approach that avoids using of data-poor emission factors and accounts for impacts of recycling and thermal treatment of waste on diverting material from landfills and CH4 capture at landfill facilities. Emissions from irrigated rice use rice-harvest areas under 3 water-management systems and a new historical data set that analyzes multiple sources for trends in water management since 1980. A time series of emissions from natural wetlands was developed by applying a multiple-regression model derived from full process-based model of Walter with analyzed meteorology from the ERA-40 reanalysis.

  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. 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.

  4. Methane and ammonia emissions from New Mexico dairy lagoons in summer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gaseous emissions of concern from commercial dairy operations include methane and ammonia. Dairy wastewater lagoons are sources of emission for both these gases. We quantified emissions of methane and ammonia from a lagoon system at a commercial open lot dairy in eastern New Mexico using open path l...

  5. Mitigation options for methane emissions from rice fields in the Philippines

    SciTech Connect

    Lantin, R.S.; Buendia, L.V.; Wassmann, R.

    1996-12-31

    The contribution of Philippine rice production to global methane emission and breakthroughs in methane emission studies conducted in the country are presented in this paper. A significant impact in the reduction of GHG emissions from agriculture can be achieved if methane emissions from ricefields can be abated. This study presents the contribution of Philippine rice cultivation to global methane emission and breakthroughs in methane emission studies in the country which address the issue of mitigation. Using the derived emission factors from local measurements, rice cultivation contributes 566.6 Gg of methane emission in the Philippines. This value is 62% of the total methane emitted from the agriculture sector. The emission factors employed which are 78% of the IPCC value for irrigated rice and 95% for rainfed rice were derived from measurements with an automatic system taken during the growth duration in the respective ecosystems. Plots drained for 2 weeks at midtillering and before harvest gave a significant reduction in methane emission as opposed to continuously flooded plots and plots drained before harvest. The cultivar Magat reduced methane emission by 50% as compared to the check variety IR72. The application of ammonium sulfate instead of urea reduced methane emission by 10% to 34%. Addition of 6 t ha{sup {minus}1} phosphogypsum in combination with urea reduced emission by 74% as opposed to plots applied with urea alone. It is also from the results of such measurements that abatement strategies are based as regards to modifying treatments such as water management, fertilization, and choice of rice variety. It is not easy to identify and recommend mitigation strategies that will fit a particular cropping system. However, the identified mitigation options provide focus for the abatement of methane emission from ricefields.

  6. Assessing the Gap Between Top-down and Bottom-up Measured Methane Emissions in Indianapolis, IN.

    NASA Astrophysics Data System (ADS)

    Prasad, K.; Lamb, B. K.; Cambaliza, M. O. L.; Shepson, P. B.; Stirm, B. H.; Salmon, O. E.; Lavoie, T. N.; Lauvaux, T.; Ferrara, T.; Howard, T.; Edburg, S. L.; Whetstone, J. R.

    2014-12-01

    Releases of methane (CH4) from the natural gas supply chain in the United States account for approximately 30% of the total US CH4 emissions. However, there continues to be large questions regarding the accuracy of current emission inventories for methane emissions from natural gas usage. In this paper, we describe results from top-down and bottom-up measurements of methane emissions from the large isolated city of Indianapolis. The top-down results are based on aircraft mass balance and tower based inverse modeling methods, while the bottom-up results are based on direct component sampling at metering and regulating stations, surface enclosure measurements of surveyed pipeline leaks, and tracer/modeling methods for other urban sources. Mobile mapping of methane urban concentrations was also used to identify significant sources and to show an urban-wide low level enhancement of methane levels. The residual difference between top-down and bottom-up measured emissions is large and cannot be fully explained in terms of the uncertainties in top-down and bottom-up emission measurements and estimates. Thus, the residual appears to be, at least partly, attributed to a significant wide-spread diffusive source. Analyses are included to estimate the size and nature of this diffusive source.

  7. 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 ...

  8. Genetic and environmental variation in methane emissions of sheep at pasture.

    PubMed

    Robinson, D L; Goopy, J P; Hegarty, R S; Oddy, V H; Thompson, A N; Toovey, A F; Macleay, C A; Briegal, J R; Woodgate, R T; Donaldson, A J; Vercoe, P E

    2014-10-01

    A total of 2,600 methane (CH4) and 1,847 CO2 measurements of sheep housed for 1 h in portable accumulation chambers (PAC) were recorded at 5 sites from the Australian Sheep CRC Information Nucleus, which was set up to test leading young industry sires for an extensive range of current and novel production traits. The final validated dataset had 2,455 methane records from 2,279 animals, which were the progeny of 187 sires and 1,653 dams with 7,690 animals in the pedigree file. The protocol involved rounding up animals from pasture into a holding paddock before the first measurement on each day and then measuring in groups of up to 16 sheep over the course of the day. Methane emissions declined linearly (with different slopes for each site) with time since the sheep were drafted into the holding area. After log transformation, estimated repeatability (rpt) and heritability (h(2)) of liveweight-adjusted CH4 emissions averaged 25% and 11.7%, respectively, for a single 1-h measurement. Sire × site interactions were small and nonsignificant. Correlations between EBV for methane emissions and Sheep Genetics Australia EBV for production traits were used as approximations to genetic correlations. Apart from small positive correlations with weaning and yearling weights (r = 0.21-0.25, P < 0.05), there were no significant relationships between production trait and methane EBV (calculated from a model adjusting for liveweight by fitting separate slopes for each site). To improve accuracy, future protocols should use the mean of 2 (rpt = 39%, h(2) = 18.6%) or 3 (rpt = 48%, h(2) = 23.2%) PAC measurements. Repeat tests under different pasture conditions and time of year should also be considered, as well as protocols measuring animals directly off pasture instead of rounding them up in the morning. Reducing the time in the PAC from 1 h to 40 min would have a relatively small effect on overall accuracy and partly offset the additional time needed for more tests per animal. Field testing in PAC has the potential to provide accurate comparisons of animal and site methane emissions, with potentially lower cost/increased accuracy compared to alternatives such as SF6 tracers or open path lasers. If similar results are obtained from tests with different protocols/seasonal conditions, use of PAC measurements in a multitrait selection index with production traits could potentially reduce methane emissions from Australian sheep for the same production level. PMID:25149329

  9. Nitrous oxide and methane emissions from cryptogamic covers.

    PubMed

    Lenhart, Katharina; Weber, Bettina; Elbert, Wolfgang; Steinkamp, Jörg; Clough, Tim; Crutzen, Paul; Pöschl, Ulrich; Keppler, Frank

    2015-10-01

    Cryptogamic covers, which comprise some of the oldest forms of terrestrial life on Earth (Lenton & Huntingford, ), have recently been found to fix large amounts of nitrogen and carbon dioxide from the atmosphere (Elbert et al., ). Here we show that they are also greenhouse gas sources with large nitrous oxide (N2 O) and small methane (CH4 ) emissions. Whilst N2 O emission rates varied with temperature, humidity, and N deposition, an almost constant ratio with respect to respiratory CO2 emissions was observed for numerous lichens and bryophytes. We employed this ratio together with respiration data to calculate global and regional N2 O emissions. If our laboratory measurements are typical for lichens and bryophytes living on ground and plant surfaces and scaled on a global basis, we estimate a N2 O source strength of 0.32-0.59 Tg year(-1) for the global N2 O emissions from cryptogamic covers. Thus, our emission estimate might account for 4-9% of the global N2 O budget from natural terrestrial sources. In a wide range of arid and forested regions, cryptogamic covers appear to be the dominant source of N2 O. We suggest that greenhouse gas emissions associated with this source might increase in the course of global change due to higher temperatures and enhanced nitrogen deposition. PMID:26152454

  10. A correction in the CDM methodological tool for estimating methane emissions from solid waste disposal sites.

    PubMed

    Santos, M M O; van Elk, A G P; Romanel, C

    2015-12-01

    Solid waste disposal sites (SWDS) - especially landfills - are a significant source of methane, a greenhouse gas. Although having the potential to be captured and used as a fuel, most of the methane formed in SWDS is emitted to the atmosphere, mainly in developing countries. Methane emissions have to be estimated in national inventories. To help this task the Intergovernmental Panel on Climate Change (IPCC) has published three sets of guidelines. In addition, the Kyoto Protocol established the Clean Development Mechanism (CDM) to assist the developed countries to offset their own greenhouse gas emissions by assisting other countries to achieve sustainable development while reducing emissions. Based on methodologies provided by the IPCC regarding SWDS, the CDM Executive Board has issued a tool to be used by project developers for estimating baseline methane emissions in their project activities - on burning biogas from landfills or on preventing biomass to be landfilled and so avoiding methane emissions. Some inconsistencies in the first two IPCC guidelines have already been pointed out in an Annex of IPCC latest edition, although with hidden details. The CDM tool uses a model for methane estimation that takes on board parameters, factors and assumptions provided in the latest IPCC guidelines, while using in its core equation the one of the second IPCC edition with its shortcoming as well as allowing a misunderstanding of the time variable. Consequences of wrong ex-ante estimation of baseline emissions regarding CDM project activities can be of economical or environmental type. Example of the first type is the overestimation of 18% in an actual project on biogas from landfill in Brazil that harms its developers; of the second type, the overestimation of 35% in a project preventing municipal solid waste from being landfilled in China, which harms the environment, not for the project per se but for the undue generated carbon credits. In a simulated landfill - the same amount of waste for 20 years -, the error would be an overestimation of 25% if the CDM project activity starts from the very first year or an underestimation of 15% if it starts just after the landfill closure. Therefore, a correction in the tool to calculate emissions from landfills as adopted by the CDM Executive Board is needed. Moreover, in countries not using the latest IPCC guidelines, which provides clear formulas to prevent misunderstandings, inventory compilers can also benefit from this paper by having more accurate results in national GHG inventories related to solid waste disposal, especially when increasing amounts of waste are landfilled, which is the case of the developing countries. PMID:26363977

  11. Methane emissions from Alaska arctic tundra in response to climatic change

    SciTech Connect

    Livingston, G.P.; Morrissey, L.A.

    1992-03-01

    In situ observations of methane emissions from the Alaska North Slope in 1987 and 1989 provide insight into the environmental interactions regulating methane emissions and into the local- and regional-scale response of the arctic tundra to interannual environmental variability. Inferences regarding climate change are based on in situ measurements of methane emissions, regional landscape characterizations derived from Landsat Multispectral Scanner satellite data, and projected regional scale emissions based on observed interannual temperature differences and simulated changes in the spatial distribution of methane emissions. Results suggest that biogenic methane emissions from arctic tundra will be significantly perturbed by climatic change, leading to warmer summer soil temperatures and to vertical displacement of the regional water table. The effect of increased soil temperatures on methane emissions resulting from anaerobic decomposition in northern wetlands will be to both increase total emissions and to increase interannual and seasonal variability. The magnitude of these effects will be determined by those factors affecting the areal distribution of methane emission rates through regulation of the regional water table. At local scales, the observed 4.7 C increase in mid-summer soil temperatures between 1987 and 1989 resulted in a 3.2-fold increase in the rate of methane emissions from anaerobic soils.

  12. Modeling of methane release from intact coal

    SciTech Connect

    Odintsev, V.N.

    2005-09-15

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

  13. Comparison of biogenic methane emissions from unmanaged estuaries, lakes, oceans, rivers and wetlands

    NASA Astrophysics Data System (ADS)

    Ortiz-Llorente, M. J.; Alvarez-Cobelas, M.

    2012-11-01

    A literature review of quantitative data was carried out to conduct a cross-system study on methane emissions relating peak emissions (PE) and annual emissions (AE) in five types of non-managed ecosystems: estuaries, lakes, oceans, streams and wetlands. PE spanned eight orders of magnitude (0.015 ?g CH4 m-2 h-1-300 mg CH4 m-2 h-1) while AE spanned seven (0.078-19044 g CH4 m-2 yr-1). PE and AE were strongly related worldwide (r2 = 0.93). There was no relationship between AE and latitude, with highly variable PE across latitudes and climates. The coefficient of variation (CV) was greatest for emissions in oceans and estuaries, while the highest emission rate was recorded in wetlands and lakes. Efflux from coastal areas and estuaries was higher than that from upwelling areas and deep seas. Concerning wetland types, marshes showed the highest PE with the highest wetland emissions occurring in sites dominated by big helophytes. Non-stratifying- and eutrophic lakes displayed more emissions than other lake types, but there was no environmental variable that might predict methane emissions from lakes on a worldwide basis. Generally, most ecosystem types followed a seasonal pattern of emissions, with a maximum in summer, except in estuaries which did not show any distinct pattern. Regarding the importance of hot spots within most ecosystems, more spatial variability of CH4 emissions was observed in lakes than in wetlands and oceans; however, no relationship between emissions and spatial variability was found. A positive relationship, albeit weak, was found between methane flux and either temperature or irradiance in wetlands; a narrow range of both negative and positive values of the water table promoted CH4 emissions. Previously, little was known about the factors controlling efflux from river and marine environments. Our study suggests that local conditions are important in controlling CH4 emissions, because the variability explained by the more commonly studied abiotic factors is low worldwide. This precludes the use of these variables to develop models to predict emissions at regional scales or wider, despite the many attempts made in the past. This makes local assessments of emissions essential, particularly in warm, temperate and tropical areas of the world. Future research aiming to shed light on CH4 fluxes from estuaries, lakes, oceans, rivers and wetlands must: 1) produce more detailed data on controlling factors; 2) increase efforts to fully characterize spatial and temporal heterogeneity; 3) combine bottom-up (measurements) and top-down (modelling) approaches.

  14. Quantifying the relative contribution of natural gas fugitive emissions to total methane emissions in Colorado, Utah, and Texas using mobile ?13CH4 analysis

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Because methane is more energy-rich than coal per kg of CO2 emitted into the atmosphere, it represents an attractive alternative to coal for electricity generation, provided that the fugitive emissions of methane are kept under control. A key step in assessing these emissions in a given region is partitioning the observed methane emissions between natural gas fugitive emissions and other sources of methane, such as from landfills or agricultural activities. One effective method for assessing the contribution of these different sources is stable isotope analysis, using the ?13CH4 signature to distinguish between natural gas and landfills or ruminants. We present measurements of mobile field ?13CH4 using a spectroscopic stable isotope analyzer based on cavity ringdown spectroscopy, in three intense natural gas producing regions of the United States: the Denver-Julesburg basin in Colorado, the Uintah basin in Utah, and the Barnett Shale in Texas. Mobile isotope measurements of individual sources and in the nocturnal boundary layer have been combined to establish the fraction of the observed methane emissions that can be attributed to natural gas activities. The fraction of total methane emissions in the Denver-Julesburg basin attributed to natural gas emissions is 78 +/- 13%. In the Uinta basin, which has no other significant sources of methane, the fraction is 96% +/- 15%. In addition, results from the Barnett shale are presented, which includes a major urban center (Dallas / Ft. Worth). Methane emissions in this region are spatially highly heterogeneous. Spatially-resolved isotope and concentration measurements are interpreted using a simple emissions model to arrive at an overall isotope ratio for the region. (left panel) Distribution of oil and gas well pads (yellow) and landfills (blue) in the Dallas / Ft. Worth area. Mobile nocturnal measurements of methane are shown in red, indicating a strong degree of source heterogeneity. (right panel) Histogram of individual isotopic source signatures, showing distinct signatures for landfills (red) and oil and gas sources (green).

  15. Evaluation of the laser methane detector to estimate methane emissions from ewes and steers.

    PubMed

    Ricci, P; Chagunda, M G G; Rooke, J; M Houdijk, J G; Duthie, C-A; Hyslop, J; Roehe, R; Waterhouse, A

    2014-11-01

    The laser methane detector (LMD) has been proposed as a method to characterize enteric methane (CH4) emissions from animals in a natural environment. To validate LMD use, its CH4 outputs (LMD-CH4), were compared against CH4 measured with respiration chambers (chamber-CH4). The LMD was used to measure CH4 concentration (µL/L) in the exhaled air of 24 lactating ewes and 72 finishing steers. In ewes, LMD was used on 1 d for each ewe, for 2-min periods at 5 hourly observation periods (P1 to P5, respectively) after feeding. In steers fed either low- or high-concentrate diets, LMD was used once daily for a 4-min period for 3 d. The week after LMD-CH4 measurement, ewes or steers entered respiration chambers to quantify daily CH4 output (g/d). The LMD outputs consisted of periodic events of high CH4 concentrations superimposed on a background of oscillating lower CH4 concentrations. The high CH4 events were attributed to eructation and the lower background CH4 to respiration. After fitting a double normal distribution to the data set, a threshold of 99% of probability of the lower distribution was used to separate respiration from eructation events. The correlation between mean LMD-CH4 and chamber-CH4 was not high, and only improved correlations were observed after data were separated in 2 levels. In ewes, a model with LMD and DMI (adjusted R(2) = 0.92) improved the relationship between DMI and chamber-CH4 alone (adjusted R(2) = 0.79) and between LMD and chamber-CH4 alone (adjusted R(2) = 0.86). In both experiments, chamber-CH4 was best explained by models with length of eructation events (time) and maximum values of CH4 concentration during respiration events (µL/L; P < 0.01). Correlation between methods differed between observation periods, indicating the best results of the LMD were observed from 3 to 5 h after feeding. Given the short time and ease of use of LMD, there is potential for its commercial application and field-based studies. Although good indicators of quantity of CH4 were obtained with respiration and eructation CH4, the method needed to separate the data into high and low levels of CH4 was not simple to apply in practice. Further assessment of the LMD should be performed in relation to animal feeding behavior and physiology to validate assumptions of eructation and respiration levels, and other sources of variation should be tested (i.e., micrometeorology) to better investigate its potential application for CH4 testing in outdoor conditions. PMID:25349366

  16. Methane Emissions from United States Natural Gas Gathering and Processing.

    PubMed

    Marchese, Anthony J; Vaughn, Timothy L; Zimmerle, Daniel J; Martinez, David M; Williams, Laurie L; Robinson, Allen L; Mitchell, Austin L; Subramanian, R; Tkacik, Daniel S; Roscioli, Joseph R; Herndon, Scott C

    2015-09-01

    New facility-level methane (CH4) emissions measurements obtained from 114 natural gas gathering facilities and 16 processing plants in 13 U.S. states were combined with facility counts obtained from state and national databases in a Monte Carlo simulation to estimate CH4 emissions from U.S. natural gas gathering and processing operations. Total annual CH4 emissions of 2421 (+245/-237) Gg were estimated for all U.S. gathering and processing operations, which represents a CH4 loss rate of 0.47% (±0.05%) when normalized by 2012 CH4 production. Over 90% of those emissions were attributed to normal operation of gathering facilities (1697 +189/-185 Gg) and processing plants (506 +55/-52 Gg), with the balance attributed to gathering pipelines and processing plant routine maintenance and upsets. The median CH4 emissions estimate for processing plants is a factor of 1.7 lower than the 2012 EPA Greenhouse Gas Inventory (GHGI) estimate, with the difference due largely to fewer reciprocating compressors, and a factor of 3.0 higher than that reported under the EPA Greenhouse Gas Reporting Program. Since gathering operations are currently embedded within the production segment of the EPA GHGI, direct comparison to our results is complicated. However, the study results suggest that CH4 emissions from gathering are substantially higher than the current EPA GHGI estimate and are equivalent to 30% of the total net CH4 emissions in the natural gas systems GHGI. Because CH4 emissions from most gathering facilities are not reported under the current rule and not all source categories are reported for processing plants, the total CH4 emissions from gathering and processing reported under the EPA GHGRP (180 Gg) represents only 14% of that tabulated in the EPA GHGI and 7% of that predicted from this study. PMID:26281719

  17. 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.

  18. 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

  19. 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.

  20. Estimate of global methane emissions from landfills and open dumps. Final report, January 1992-September 1994

    SciTech Connect

    Doorn, M.R.J.; Barlaz, M.A.

    1995-02-01

    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. CH4 produced by the anaerobic decomposition of waste buried in landfills and open dumps is a significant contributor to global CH4 emissions, with estimates ranging from 10 to 70 Tg/yr. Methods of managing solid waste vary widely, ranging from open dumps and open burning to sanitary landfills with leachate collection systems and LFG control.

  1. Tank bromeliad - a natural model ecosystem for methane cycling research

    NASA Astrophysics Data System (ADS)

    Martinson, Guntars; Brandt, Franziska; Conrad, Ralf

    2014-05-01

    Tank bromeliads are common epiphytes throughout neotropical forest ecosystems. They are relatively small discrete habitats for terrestrial and aquatic macro- and microorganisms and naturally replicated. Their tanks effectively collect leaf litter and water and harbor a diverse microbial community. Up to several thousands of these tank bromeliads per hectare of tropical forest create a unique wetland ecosystem responsible for significant methane emissions. In a field study in tropical montane forests of southern Ecuador we sampled tank bromeliads of different species, size and canopy height and found that tank water availability controlled community composition of methanogenic archaea, determined by molecular analysis of the archaeal 16S rRNA genes. We set up a greenhouse experiment to investigate drying and re-wetting effects on microbial community composition and methanogenesis. Additionally, we conducted 13-CH-4 and 13-CO-2 labeling studies to investigate potential interaction of plant and microbial metabolism during methane cycling in tank bromeliads. Drying resulted in rapid change of the microbial community composition. The relative abundance of acetoclastic methanogens increased and that of hydrogenotrophic methanogens decreased with decreasing tank water availability confirming our field observations. Labeling studies showed that carbon was released from the plant into the tank supporting methanogenesis and that tank-produced methane was ventilated through the bromeliad leaf structure into the atmosphere which is analogous to the rhizosphere environment of wetland ecosystems. The bromeliad ecosystem may therefore provide a natural model to study how environmental changes and plant-microbe interactions drive methane cycling in aquatic-terrestrial ecosystems.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methane emission is an important element 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 pur...

  3. Methane Emissions from the Natural Gas Transmission and Storage System in the United States

    E-print Network

    Opsomer, Jean

    Methane Emissions from the Natural Gas Transmission and Storage System in the United States Daniel: The recent growth in production and utilization of natural gas offers potential climate benefits, but those benefits depend on lifecycle emissions of methane, the primary component of natural gas and a potent

  4. 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...

  5. 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...

  6. arXiv:astroph/0003291 Detection of Hff Emission in a Methane (Ttype) Brown Dwarf

    E-print Network

    Brown, Michael E.

    arXiv:astro­ph/0003291 20 Mar 2000 Detection of Hff Emission in a Methane (T­type) Brown Dwarf Adam J. Burgasser 1 , J. Davy Kirkpatrick 2 , I. Neill Reid 3 , James Liebert 4 , John E. Gizis 2 , and Michael E. Brown 5;6 ABSTRACT We report the detection of Hff emission in the T dwarf (methane brown dwarf

  7. 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

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. Variation in enteric methane emissions among cows on commercial dairy farms.

    PubMed

    Bell, M J; Potterton, S L; Craigon, J; Saunders, N; Wilcox, R H; Hunter, M; Goodman, J R; Garnsworthy, P C

    2014-09-01

    Methane (CH4) emissions by dairy cows vary with feed intake and diet composition. Even when fed on the same diet at the same intake, however, variation between cows in CH4 emissions can be substantial. The extent of variation in CH4 emissions among dairy cows on commercial farms is unknown, but developments in methodology now permit quantification of CH4 emissions by individual cows under commercial conditions. The aim of this research was to assess variation among cows in emissions of eructed CH4 during milking on commercial dairy farms. Enteric CH4 emissions from 1964 individual cows across 21 farms were measured for at least 7 days/cow using CH4 analysers at robotic milking stations. Cows were predominantly of Holstein Friesian breed and remained on the same feeding systems during sampling. Effects of explanatory variables on average CH4 emissions per individual cow were assessed by fitting a linear mixed model. Significant effects were found for week of lactation, daily milk yield and farm. The effect of milk yield on CH4 emissions varied among farms. Considerable variation in CH4 emissions was observed among cows after adjusting for fixed and random effects, with the CV ranging from 22% to 67% within farms. This study confirms that enteric CH4 emissions vary among cows on commercial farms, suggesting that there is considerable scope for selecting individual cows and management systems with reduced emissions. PMID:24946166

  13. Natural gas fugitive emissions rates constrained by global atmospheric methane and ethane.

    PubMed

    Schwietzke, Stefan; Griffin, W Michael; Matthews, H Scott; Bruhwiler, Lori M P

    2014-07-15

    The amount of methane emissions released by the natural gas (NG) industry is a critical and uncertain value for various industry and policy decisions, such as for determining the climate implications of using NG over coal. Previous studies have estimated fugitive emissions rates (FER)--the fraction of produced NG (mainly methane and ethane) escaped to the atmosphere--between 1 and 9%. Most of these studies rely on few and outdated measurements, and some may represent only temporal/regional NG industry snapshots. This study estimates NG industry representative FER using global atmospheric methane and ethane measurements over three decades, and literature ranges of (i) tracer gas atmospheric lifetimes, (ii) non-NG source estimates, and (iii) fossil fuel fugitive gas hydrocarbon compositions. The modeling suggests an upper bound global average FER of 5% during 2006-2011, and a most likely FER of 2-4% since 2000, trending downward. These results do not account for highly uncertain natural hydrocarbon seepage, which could lower the FER. Further emissions reductions by the NG industry may be needed to ensure climate benefits over coal during the next few decades. PMID:24945600

  14. Heritability of predicted daily enteric methane emissions from growing Nellore cattle.

    PubMed

    Sobrinho, T L P; Mercadante, M E Z; Canesin, R C; Cyrillo, J N S G; Albuquerque, L G; Branco, R H

    2015-01-01

    The objective of this study was to estimate the heritability of predicted daily enteric methane emissions (PME) from growing Nellore cattle. Dry matter intake (DMI) records of 955 Nellore animals that were born between 2004 and 2013, which were obtained in a postweaning performance test lasting 83 ± 15 days, were used. The PME of each animal, obtained as MJ/day and converted to g/day, was estimated using three equations: PME1 (MJ/day) = 2.29 + 0.647 x DMI (kg/day), PME2 (MJ/day) = 3.96 + 0.561 x DMI (kg/day), and PME3 (MJ/day) = 4.41 + 0.50 x DMI (kg/day). The heritability (h2) of PME obtained using the three equations was identical to the h2 of DMI, regardless of whether the model included the effect of mid-test weight (h2 = 0.32 ± 0.069) or not (h2 = 0.48 ± 0.069). The equations were based exclusively on variations in DMI, and detected variations in this trait without taking into consideration individual differences in enteric methane emission caused by differences in fermentation and digestion capacity. Therefore, prediction equations of enteric methane emission from DMI are not adequate to estimate differences between animals. PMID:26535728

  15. 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.

  16. Open Path Tracer Measurements of Methane Emissions from Free Ranging Cattle

    NASA Astrophysics Data System (ADS)

    Griffith, D. W.; Tonini, M.; Bryant, G. R.; Eckard, R.; Grainger, C.; McGinn, S. M.

    2006-12-01

    This paper addresses the need for more accurate and representative measurements of methane emissions from cattle in their natural environments. Improved measurements are or will be required to quantify methane emissions for national greenhouse gas budgets and future carbon trading schemes, and to assess the effectiveness of proposed mitigation strategies. We describe measurements of methane emissions from free- ranging cattle grazing in their natural outdoor environments in Australia and New Zealand. We employ a novel tracer method in which nitrous oxide is released at a known rate from fenceline tubing or canisters attached to individual cows, and the mixing ratios of methane, nitrous oxide and carbon dioxide are measured continuously and simultaneously downwind by open path FTIR spectroscopy. Correlations between methane, nitrous oxide and carbon dioxide can be used to infer the herd-average methane flux directly. Measurements will be compared with the more conventional SF6 ruminal tracer technique.

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

    SciTech Connect

    Matthews, E.; Fung, I. )

    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.

  18. NO emission characteristics of methane-air double flame

    SciTech Connect

    Nishioka, M.; Nakagawa, S.; Ishikawa, Y.; Takeno, T. . Dept. of Mechanical Engineering)

    1994-07-01

    NO emission characteristics of methane-air Bunsen-type burner flames were studied numerically in terms of counterflow flame. The flames have the well-known double flame structure: the rich premixed flame to produce CO and H[sub 2] as the main intermediate products and the diffusion flame where the intermediate products burn with surrounding air, and the structure can be simulated by using rich counterflow flame with air. The similarity solution was adopted to describe the flow, temperature, and concentration fields and the detailed kinetics calculation was made by using C[sub 2] chemistry with the all mechanisms leading to NO formation, including thermal and prompt NO mechanisms. The calculation was made as well for thermal mechanism alone, so as to distinguish contribution of the respective NO formation mechanisms in total NO production. The emission characteristics were evaluated quantitatively in terms of the emission index, as compared to the normal premixed and pure diffusion flames. The effects of equivalence ratio and the velocity gradient on the emission index of these flames were studied.

  19. Methane emission from single cropping rice paddies amended different manures

    SciTech Connect

    Du Daodeng; Tao Zhan

    1996-12-31

    Methane emission fluxes were determined from single cropping rice paddies amended with different manures through a productively comparative experiment. The average fluxes in the whole growth season ranged from 3.92 to 10.96 mg/m{sup 2}.hr. The compost amended paddies gave the highest emission fluxes of 10.26 mg/m{sup 2}.hr, while the fluxes from the other manure amended paddies ranked as follows: horse dung biogas digester sediment 10.02, chemical fertilizer only 8.81, nightsoil biogas sediment 7.76, chicken dropping biogas digester sediment 4.48 and pig dung biogas digester sediment 3.92 mg/m{sup 2}.hr. The latter 3 sediments gave the significant less ({alpha} < 0.05) fluxes than compost. The highest fluxes peaks of all treated paddies appeared unanimously between the stages of the midtillering and the earing, with a half of total CH{sub 4} emissions were produced in this period which could be chosen as the key period for control of CH{sub 4} emission from the single cropping rice paddies. The positive correlation of the fluxes with the temperatures in 5 cm soil layers and the negative correlation of the fluxes with the rice yields, the soil N and P{sub 2}O{sub 5} contents were also observed.

  20. Methane Emissions from Woody Stems of Tropical and Temperate Wetland Trees

    NASA Astrophysics Data System (ADS)

    Pangala, S. R.; Hornibrook, E. R.; Gowing, D. J.; Bastviken, D.; Enrich-Prast, A.; Gauci, V.

    2013-12-01

    Wetland-adapted trees are known to transport and release soil-produced methane to the atmosphere through woody stem surfaces, yet the magnitude and controls of tree-mediated methane emissions remain unknown for mature forests. Although 60% of global wetlands are forested, and many tropical forests are either permanently or seasonally flooded, the ecosystem level contribution of tree-mediated methane flux relative to other gas transport pathways (e.g., ebullition, pore-water diffusion and via aerenchyma of herbaceous plants) has received limited attention. The role of trees as a conduit for methane export from soil to the atmosphere was assessed in situ in a temperate forested wetland (Flitwick Moor, UK) and tropical forested wetlands in Borneo, Indonesia and Amazonia, Brazil. Mesocosm experiments also were conducted in the temperate region to characterise emission characteristics of Alnus glutinosa saplings subjected to different water-table treatments. Methane emissions from trees were compared to fluxes from the soil surface in both the in situ and mesocosm studies. Temperate and tropical tree species both released significant quantities of methane from stem surfaces. Emission rates for young trees exceeded that of mature trees by several orders of magnitude on a stem surface area basis. Key factors controlling rates of tree-mediated flux were tree physiology (e.g., wood specific density, stem lenticel density), abiotic conditions (e.g., soil temperature) and methane gas transport mechanisms (e.g., passive diffusion, convective transport). Tree-mediated methane emissions contributed 6 to 87% of total ecosystem methane flux with the largest relative contribution from trees occurring in tropical wetlands. Recent data from Amazonian wetlands demonstrate very high rates of tree-mediated methane emission relative to other types of forested wetlands. These results indicate that exclusion of tree-mediated methane fluxes from measurement campaigns conducted in forested wetlands may result in a significant underestimate of total methane flux from such ecosystems.

  1. Analyses of geological and hydrodynamic controls on methane emissions experienced in a Lower Kittanning coal mine

    PubMed Central

    Karacan, C. Özgen; Goodman, Gerrit V.R.

    2015-01-01

    This paper presents a study assessing potential factors and migration paths of methane emissions experienced in a room-and-pillar mine in Lower Kittanning coal, Indiana County, Pennsylvania. Methane emissions were not excessive at idle mining areas, but significant methane was measured during coal mining and loading. Although methane concentrations in the mine did not exceed 1% limit during operation due to the presence of adequate dilution airflow, the source of methane and its migration into the mine was still a concern. In the course of this study, structural and depositional properties of the area were evaluated to assess complexity and sealing capacity of roof rocks. Composition, gas content, and permeability of Lower Kittanning coal, results of flotation tests, and geochemistry of groundwater obtained from observation boreholes were studied to understand the properties of coal and potential effects of old abandoned mines within the same area. These data were combined with the data obtained from exploration boreholes, such as depths, elevations, thicknesses, ash content, and heat value of coal. Univariate statistical and principal component analyses (PCA), as well as geostatistical simulations and co-simulations, were performed on various spatial attributes to reveal interrelationships and to establish area-wide distributions. These studies helped in analyzing groundwater quality and determining gas-in-place (GIP) of the Lower Kittanning seam. Furthermore, groundwater level and head on the Lower Kittanning coal were modeled and flow gradients within the study area were examined. Modeling results were interpreted with the structural geology of the Allegheny Group of formations above the Lower Kittanning coal to understand the potential source of gas and its migration paths. Analyses suggested that the source of methane was likely the overlying seams such as the Middle and Upper Kittanning coals and Freeport seams of the Allegheny Group. Simulated ground-water water elevations, gradients of groundwater flow, and the presence of recharge and discharge locations at very close proximity to the mine indicated that methane likely was carried with groundwater towards the mine entries. Existing fractures within the overlying strata and their orientation due to the geologic conditions of the area, and activation of slickensides between shale and sandstones due to differential compaction during mining, were interpreted as the potential flow paths. PMID:26478644

  2. Ammonia and methane emissions from cattle and dairy feedlots in Colorado

    NASA Astrophysics Data System (ADS)

    Golston, L.; Pan, D.; Stanton, L. G.; Tao, L.; Sun, K.; Zondlo, M. A.

    2014-12-01

    Concentrated animal feeding operations (CAFOs) are recognized as a major contributor of both methane and ammonia to the atmosphere. Ammonia is released by volatilization of urea and nitrogen containing wastes from the feedlot surface and waste management systems, while methane is produced from enteric fermentation and primarily exhaled into the atmosphere. Our objective was to survey plumes downwind of open lot feedyards near Greeley, Colorado and surrounding areas, to quantify the spatial and temporal variability of agricultural emissions in this area. Research was conducted during the month-long NASA DISCOVER-AQ campaign in July-August 2014, with over 4000 km of on-road measurements. Methane and ammonia concentrations were measured using open-path laser spectroscopy, along with water vapor, carbon monoxide, and carbon dioxide on a roof-mounted, mobile platform. The open-path design enables high resolution measurements of ammonia with minimized sampling issues. Concurrent measurements during the campaign by other groups on stationary and aircraft platforms help characterize the meteorological conditions and atmospheric chemistry. We present measurements from 65 of the 67 registered CAFOs in Weld County, which contain up to 660,000 cattle-equivalent animals units. The ammonia to methane enhancement ratio, ?NH3:?CH4, was positively skewed with a median of 0.14 ± 0.04 ppmv/ppmv, consistent with our previous measurements during DISCOVER-AQ California. Due to the much greater variability of ammonia compared to methane, the emissions ratio is used to provide an estimate of feedyard ammonia emissions, with results divided for cattle, dairy, and sheep. Using the most recent emissions estimates of methane, we calculated a total of ?28.8 TgNH3/yr released globally from feedlots alone, nearly as large as the IPCC's estimate of 30.4 Tg/yr from all agriculture sources. This discrepancy suggests feedyard ammonia is underrepresented in current inventories and models, and its environmental effects on air quality and nitrogen deposition are not fully accounted for.

  3. 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.

  4. Modeling micro-topographic controls on boreal peatland hydrology and methane fluxes

    NASA Astrophysics Data System (ADS)

    Cresto Aleina, F.; Runkle, B. R. K.; Kleinen, T.; Kutzbach, L.; Schneider, J.; Brovkin, V.

    2015-07-01

    Small-scale surface heterogeneities can influence land-atmosphere fluxes and therefore carbon, water and energy budgets on larger scale. This effect is of particular relevance for high-latitude ecosystems, because of the great amount of carbon stored in their soils. We introduce a novel micro-topographic model, the Hummock-Hollow (HH) model, which explicitly represents small-scale surface elevation changes. By computing the water table at the small scale, and by coupling the model with a process-based model for soil methane processes, we are able to model effects of micro-topography on hydrology and methane emissions in a typical boreal peatland. In order to assess the effect of micro-topography on water balance and methane emissions of the peatland we compare two versions of the model, one with a representation of micro-topography and a classical single-bucket model version, and show that the temporal variability in the model version with micro-topography performs better if compared with local data. Accounting for micro-topography almost triples the cumulative methane flux over the simulated time-slice. We found that the single-bucket model underestimates methane emissions because of its poor performance in representing hydrological dynamics. The HH model with micro-topography captures the spatial dynamics of water and methane fluxes, being able to identify the hotspots for methane emissions. The model also identifies a critical scale (0.01 km2) which marks the minimal resolution for the explicit representation of micro-topography in larger-scale models.

  5. Modeling micro-topographic controls on boreal peatland hydrology and methane fluxes

    NASA Astrophysics Data System (ADS)

    Cresto Aleina, F.; Runkle, B. R. K.; Kleinen, T.; Kutzbach, L.; Schneider, J.; Brovkin, V.

    2015-10-01

    Small-scale surface heterogeneities can influence land-atmosphere fluxes and therefore carbon, water and energy budgets on a larger scale. This effect is of particular relevance for high-latitude ecosystems, because of the great amount of carbon stored in their soils. We introduce a novel micro-topographic model, the Hummock-Hollow (HH) model, which explicitly represents small-scale surface elevation changes. By computing the water table at the small scale, and by coupling the model with a process-based model for soil methane processes, we are able to model the effects of micro-topography on hydrology and methane emissions in a typical boreal peatland. In order to assess the effect of micro-topography on water the balance and methane emissions of the peatland we compare two versions of the model, one with a representation of micro-topography and a classical single-bucket model version, and show that the temporal variability in the model version with micro-topography performs better if compared with local data. Accounting for micro-topography almost triples the cumulative methane flux over the simulated time-slice. We found that the single-bucket model underestimates methane emissions because of its poor performance in representing hydrological dynamics. The HH model with micro-topography captures the spatial dynamics of water and methane fluxes, being able to identify the hotspots for methane emissions. The model also identifies a critical scale (0.01 km2) which marks the minimal resolution for the explicit representation of micro-topography in larger-scale models.

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

    PubMed

    Scheutz, Charlotte; Pedersen, Rasmus Broe; Petersen, Per Haugsted; Jørgensen, Jørgen Henrik Bjerre; Ucendo, Inmaculada Maria Buendia; Mønster, Jacob G; Samuelsson, Jerker; Kjeldsen, Peter

    2014-07-01

    Methane generated at landfills contributes to global warming and can be mitigated by biocover systems relying on microbial methane oxidation. As part of a closure plan for an old unlined landfill without any gas management measures, an innovative biocover system was established. The system was designed based on a conceptual model of the gas emission patterns established through an initial baseline study. The study included construction of gas collection trenches along the slopes of the landfill where the majority of the methane emissions occurred. Local compost materials were tested as to their usefulness as bioactive methane oxidizing material and a suitable compost mixture was selected. Whole site methane emission quantifications based on combined tracer release and downwind measurements in combination with several local experimental activities (gas composition within biocover layers, flux chamber based emission measurements and logging of compost temperatures) proved that the biocover system had an average mitigation efficiency of approximately 80%. The study showed that the system also had a high efficiency during winter periods with temperatures below freezing. An economic analysis indicated that the mitigation costs of the biocover system were competitive to other existing greenhouse gas mitigation options. PMID:24755356

  7. 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

  8. 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.

  9. Methane emissions from bald cypress tree trunks in a bottomland forest

    NASA Astrophysics Data System (ADS)

    Schile, L. M.; Pitz, S.; Megonigal, P.

    2013-12-01

    Studies on natural methane emissions predominantly have occurred on wetland soils with herbaceous plant species. Less attention, however, has been placed on the role of woody wetland plant species in the methane cycle. Recent studies on methane emissions from tree trunks document that they are a significant source of emissions that previously has been not accounted for. In this study, we examine methane emissions from trunks of mature bald cypress (Taxodium distichum), which is a dominant tree species in bottomland hardwood forests of the Southeastern United States. To date, little is known about soil methane emissions in these systems, and published tree emissions have been limited to a single study conducted on bald cypress knees. In May 2013, we established a plot in a monospecific bald cypress stand planted approximately 70 years ago on the Chesapeake Bay in Maryland and are monitoring methane emissions on 12 tree trunks, soil chambers, and pore-water over the course of a year. Custom-made 30 cm tall open face rectangular tree chambers were constructed out of white acrylic sheets and secured on each tree at a midpoint of 45 cm above the soil surface. Chambers were lined with neoprene along the tree surface and sealed with an epoxy. On three trees that varied in trunk diameter, chambers were placed at average heights of 95, 145, 195, and 345 cm from the soil surface in order to calculate a decay curve of methane emissions. Once a month, chambers were sealed with lids and head-space samples were collected over the course of an hour. Methane flux was calculated and compared to emissions from soil chambers. Average cypress trunk methane fluxes ranged from 17.7 ?mole m-2 hr-1 in May to 49.5 and 116.5 ?mole m-2 hr-1 in June and July, respectively. Soil fluxes averaged 28.5 ?mole m-2 hr-1 in May and June, and decreased to 13.7 ?mole m-2 hr-1 in July. Methane emissions decreased exponentially up the tree trunk, with fluxes of 2 ?mole m-2 hr-1 and less calculated 345 cm above the ground. These results highlight that methane emissions from bald cypress-dominated forests can be a significant source to the atmosphere. Current estimates of methane emissions from forested wetlands likely are underestimated based on these preliminary results, and suggest the increasing importance of tree-mediated methane fluxes to the atmosphere.

  10. 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.

  11. Impact of an abrupt cooling event on interglacial methane emissions in northern peatlands

    NASA Astrophysics Data System (ADS)

    Zürcher, S.; Spahni, R.; Joos, F.; Steinacher, M.; Fischer, H.

    2013-03-01

    Rapid changes in atmospheric methane (CH4), temperature and precipitation are documented by Greenland ice core data both for glacial times (the so called Dansgaard-Oeschger (D-O) events) as well as for a cooling event in the early Holocene (the 8.2 kyr event). The onsets of D-O warm events are paralleled by abrupt increases in CH4 by up to 250 ppb in a few decades. Vice versa, the 8.2 kyr event is accompanied by an intermittent decrease in CH4 of about 80 ppb over 150 yr. The abrupt CH4 changes are thought to mainly originate from source emission variations in tropical and boreal wet ecosystems, but complex process oriented bottom-up model estimates of the changes in these ecosystems during rapid climate changes are still missing. Here we present simulations of CH4 emissions from northern peatlands with the LPJ-Bern dynamic global vegetation model. The model represents CH4 production and oxidation in soils and transport by ebullition, through plant aerenchyma, and by diffusion. Parameters are tuned to represent site emission data as well as inversion-based estimates of northern wetland emissions. The model is forced with climate input data from freshwater hosing experiments using the NCAR CSM1.4 climate model to simulate an abrupt cooling event. A concentration reduction of ~10 ppb is simulated per degree K change of mean northern hemispheric surface temperature in peatlands. Peatland emissions are equally sensitive to both changes in temperature and in precipitation. If simulated changes are taken as an analogy to the 8.2 kyr event, boreal peatland emissions alone could only explain 23% of the 80 ppb decline in atmospheric methane concentration. This points to a significant contribution to source changes from low latitude and tropical wetlands to this event.

  12. Impact of an 8.2-kyr-like event on methane emissions in northern peatlands

    NASA Astrophysics Data System (ADS)

    Zürcher, S.; Spahni, R.; Joos, F.; Steinacher, M.; Fischer, H.

    2012-09-01

    Rapid changes in atmospheric methane (CH4), temperature and precipitation are documented by Greenland ice core data both for glacial times (the so called Dangaard-Oeschger (DO) events) as well as for a cooling event in the early Holocene (the 8.2 kyr event). The onsets of DO warm events are paralleled by abrupt increases in CH4 by up to 250 ppbv in a few decades. Vice versa, the 8.2 kyr event is accompanied by an intermittent decrease in CH4 of about 80 ppbv over 150 yr. The abrupt CH4 changes are thought to mainly originate from source emission variations in tropical and boreal wet ecosystems, but complex process oriented bottom-up model estimates of the changes in these ecosystems during rapid climate changes are still missing. Here we present simulations of CH4 emissions from northern peatlands with the LPJ-Bern dynamic global vegetation model. The model represents CH4 production and oxidation in soils and transport by ebullition, through plant aerenchyma, and by diffusion. Parameters are tuned to represent site emission data as well as inversion-based estimates of northern wetland emissions. The model is forced with climate input data from freshwater hosing experiments using the NCAR CSM1.4 climate model to simulate an abrupt cooling similar to the widespread 8.2 kyr event. As a main result we get a concentration reduction of ~10 ppbv per degree K change of mean northern hemispheric surface temperature in peatlands. This sensitivity comprises effects on peatland emissions of similar size by the temperature itself as well as by the accompanying change in precipitation rate, hence water table. Comparison with the ice core record reveals that a change in boreal peatland emissions alone could not completely account for the 80 ppbv methane decline during the 8.2 kyr event, pointing to a significant contribution from tropical wetlands to this event.

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

    PubMed Central

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

    2014-01-01

    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

  14. Methane emissions from Amazonian Rivers and their contribution to the global methane budget.

    PubMed

    Sawakuchi, Henrique O; Bastviken, David; Sawakuchi, André O; Krusche, Alex V; Ballester, Maria V R; Richey, Jeffrey E

    2014-09-01

    Methane (CH4 ) fluxes from world rivers are still poorly constrained, with measurements restricted mainly to temperate climates. Additional river flux measurements, including spatio-temporal studies, are important to refine extrapolations. Here we assess the spatio-temporal variability of CH4 fluxes from the Amazon and its main tributaries, the Negro, Solimões, Madeira, Tapajós, Xingu, and Pará Rivers, based on direct measurements using floating chambers. Sixteen of 34 sites were measured during low and high water seasons. Significant differences were observed within sites in the same river and among different rivers, types of rivers, and seasons. Ebullition contributed to more than 50% of total emissions for some rivers. Considering only river channels, our data indicate that large rivers in the Amazon Basin release between 0.40 and 0.58 Tg CH4  yr(-1) . Thus, our estimates of CH4 flux from all tropical rivers and rivers globally were, respectively, 19-51% to 31-84% higher than previous estimates, with large rivers of the Amazon accounting for 22-28% of global river CH4 emissions. PMID:24890429

  15. 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

  16. Methane emissions from a New Mexico dairy lagoon system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methane is a greenhouse gas with a global warming potential 25 times that of carbon dioxide. Animal agriculture is recognized as a significant source of methane to the atmosphere. Dairies on the Southern High Plains of New Mexico and Texas are typically open lot, and major sources of methane are the...

  17. 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

  18. Direct Continuous Measurements of Methane Emissions from a Landfill: Method, Station and Latest Results

    NASA Astrophysics Data System (ADS)

    Burba, G. G.; Xu, L.; Lin, X.; Amen, J.; Welding, K.; McDermitt, D. K.

    2014-12-01

    Solar-powered automated flux station was deployed continuously inside the Bluff Road Landfill (Lincoln, NE) for the period of over4 years starting June 2010. Landfill methane emissions were measured using the eddy covariance method, reporting hourly emission rates. The data shown in this presentation are from the period of June to December 2010 when no gas recovery was in operation. The continuous measurements of hourly emission rates allowed a number of important analyses of the key factors affecting landfill methane emissions at different time scales. In particular, the results show that landfill methane emissions strongly depended on changes in barometric pressure. Rising barometric pressure suppressed the emission, while falling barometric pressure enhanced the emission, resulting in up to a 35-fold variation in day-to-day methane emissions. Wavelet coherence analysis revealed a strong spectral coherency between variations of barometric pressure and methane emission at periodicities ranging from 1 day to 8 days. Power spectrum and ogive analysis showed that at least 10 days of continuous measurements was needed in order to capture 90% of the total variance in the methane emission time series at the site.From these results, it is apparent that point-in-time measurements taken at monthly or longer time intervals using techniques such as the trace plume method, the mass balance method, or the closed-chamber method will be subject to large variations in measured emission rates because of the barometric pumping phenomenon. Estimates of long-term integrated methane emissions based on such measurements could yield uncertainties, ranging from 28% underestimation to 32% overestimation.The results demonstrate a need for continuous measurements to quantify annual total landfill emissions. This conclusion may also apply to the wetlands, peatlands, lakes, and other environments where emissions are from porous media or ebullition.

  19. Remote Sensing Based Methane Emission Inventory Vis-A-Vis Rice Cultural Types Of South Asia

    NASA Astrophysics Data System (ADS)

    Manjunath, K. R.; More, R.; Chauhan, P.; Vyas, A.; Panigrahy, S.; Parihar, J. S.

    2014-11-01

    Rice cultivation has been recognized as one of the major anthropogenic source for methane (CH4) emissions which is a microbial mediated anaerobic activity, mainly favoured by the flooded conditions in the rice fields. Information available on CH4 emission is limited, especially in a spatial domain, mainly because of the complexity involved in generating such data. The current approach demonstrates the use of secondary data sources available on the methane emission scaling factors, coupled with the information derived on rice cultural types and crop calendar. Methane emission from each type of rice field was firstly calculated by multiplying the emission factor by the corresponding cultivation area and length of cropping period. The values were then extrapolated over each country with respect to the rice area and crop duration for under each cultural type. The rice cultural type wise methane emission value for South Asia was derived by summation of individual emission values for the respective cultural type within each country. The total methane emission derived for South Asia region is (4.7817 Tg/yr). The mean methane emission estimates derived for each country are viz. India (3.3860 Tg/yr), Bangladesh (0.9136 Tg/yr), Pakistan (0.2675 Tg/yr), Sri Lanka (0.1073 Tg/yr) and Nepal (0.1074 Tg/yr). The derived methane emission estimates could be used to study the regional variations within the country and also to adopt the mitigation strategies to combat the high methane emission values within specific cultural type by means of altering the farming practise or water regime.

  20. Effect of Carex rostrata on seasonal and interannual variability in peatland methane emissions

    NASA Astrophysics Data System (ADS)

    Noyce, Genevieve L.; Varner, Ruth K.; Bubier, Jill L.; Frolking, Steve

    2014-01-01

    are a large natural source of atmospheric methane (CH4), and the sedge Carex rostrata plays a critical role in the production, oxidation, and transport of CH4 in these systems. This 4 year clipping experiment examined the changes in CH4 emissions from a temperate peatland after removing all aboveground C. rostrata biomass. Methane fluxes, dissolved CH4, and environmental variables were measured during spring, summer, and fall from 2008 to 2011. Clipping and removing the C. rostrata leaves and stems caused an immediate decrease in CH4 emissions that persisted over 4 years of this study. There was a strong seasonal trend in CH4 flux, with the largest treatment effects occurring during the fall months when the sedges were senescing. As expected, there was a strong positive correlation between C. rostrata green-leaf area and CH4 flux, implying that the presence of C. rostrata increases CH4 emissions from this peatland. Large interannual variability in vegetation distribution and biomass, water table depth, and temperature was observed in this study, indicating the importance of multiyear studies for understanding the interactions among these factors to determine how they could be incorporated into biogeochemical models to predict CH4 emissions under changing environmental conditions.

  1. Temporal patterns of methane emissions from wetland rice fields treated by different modes of N application

    NASA Astrophysics Data System (ADS)

    Wassmann, R.; Neue, H. U.; Lantin, R. S.; Aduna, J. B.; Alberto, M. C. R.; Andales, M. J.; Tan, M. J.; van der Gon, H. A. C. Denier; Hoffmann, H.; Papen, H.; Rennenberg, H.; Seiler, W.

    1994-08-01

    Methane emission rates from wetland rice fields were determined in Los Baños (Philippines) using an automatic system that allows continuous measurements over time. Methane emission was monitored in an irrigated Aquandic Epiaqualf planted to rice cultivar IR72. Urea fertilizer was applied using four modes: (1) broadcast 10 days after transplanting, (2) broadcast at transplanting, (3) broadcast and incorporated at final harrowing, and (4) deep placement as sulfur-coated granules. The treatments were laid out in a randomized complete block design with four replicates. Measurements were done in the 1991 wet season, 1992 dry season (four treatments), and the 1992 wet season (only treatment 3). Methane emission rates from the experimental plots showed pronounced seasonal and diel variations. The diel pattern of methane emission rates followed a consistent pattern, with highest rates observed in the early afternoon and lowest rates in the early morning. Methane emission rate was generally highest at the ripening stage. The average methane emission rate during the 1992 dry season (190 mg CH4 m-2 d-1) exceeded the average flux rates of the 1992 wet season (79 mg CH4 m-2 d-1) by a factor of 2.4. The total methane emitted from these flooded rice fields amounted to 19 g CH4 m-2 in the dry season with rice yields of 5.2-6.3 t ha-1 and 7 g CH4 m-2 in the wet season with rice yields of 2.4-3.3 t ha-1 regardless of the mode of N application. Significant amounts corresponding to 20% of the methane released under waterlogged conditions were released when the soil was drained after harvest. Emission rates increased sharply when the floodwater receded and macropores started to drain. Emission of methane stopped only when the soil became fully aerated.

  2. 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.

  3. Suppression of rice methane emission by sulfate deposition in simulated acid rain

    E-print Network

    Gauci, Vincent

    Suppression of rice methane emission by sulfate deposition in simulated acid rain Vincent Gauci,1; accepted 20 November 2007; published 30 July 2008. [1] Sulfate in acid rain is known to suppress methane from rice agriculture may be similarly affected by acid rain, a major and increasing pollution problem

  4. 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

  5. USERS MANUAL: LANDFILL GAS EMISSIONS MODEL - VERSION 2.0

    EPA Science Inventory

    The document is a user's guide for a computer model, Version 2.0 of the Landfill Gas Emissions Model (LandGEM), for estimating air pollution emissions from municipal solid waste (MSW) landfills. The model can be used to estimate emission rates for methane, carbon dioxide, nonmet...

  6. Assessing methods to estimate emissions of non-methane organic compounds from landfills.

    PubMed

    Saquing, Jovita M; Chanton, Jeffrey P; Yazdani, Ramin; Barlaz, Morton A; Scheutz, Charlotte; Blake, Don R; Imhoff, Paul T

    2014-11-01

    The non-methane organic compound (NMOC) emission rate is used to assess compliance with landfill gas emission regulations by the United States Environmental Protection Agency (USEPA). A recent USEPA Report (EPA/600/R-11/033) employed a ratio method to estimate speciated NMOC emissions (i.e., individual NMOC emissions): speciated NMOC emissions=measured methane (CH4) emission multiplied by the ratio of individual NMOCs concentration relative to CH4 concentration (C(NMOCs)/C(CH4)) in the landfill header gas. The objectives of this study were to (1) evaluate the efficacy of the ratio method in estimating speciated NMOC flux from landfills; (2) determine for what types of landfills the ratio method may be in error and why, using recent field data to quantify the spatial variation of (C(NMOCs)/C(CH4)) in landfills; and (3) formulate alternative models for estimating NMOC emissions from landfills for cases in which the ratio method results in biased estimates. This study focuses on emissions through landfill covers measured with flux chambers and evaluates the utility of the ratio method for estimating NMOC emission through this pathway. Evaluation of the ratio method was performed using CH4 and speciated NMOC concentration and flux data from 2012/2013 field sampling of four landfills, an unpublished landfill study, and literature data from three landfills. The ratio method worked well for landfills with thin covers (<40 cm), predicting composite NMOC flux (as hexane-C) to within a factor of 10× for 13 out of 15 measurements. However, for thick covers (?40 cm) the ratio method overestimated NMOC emissions by ?10× for 8 out of 10 measurements. Alternative models were explored incorporating other chemical properties into the ratio method. A molecular weight squared (MW)(2)-modified ratio equation was shown to best address the tendency of the current ratio method to overestimate NMOC fluxes for thick covers. While these analyses were only performed using NMOC fluxes through landfill covers measured with flux chambers, results indicate the current USEPA approach for estimating NMOC emissions may overestimate speciated NMOC emission ?10× for many compounds. PMID:25108756

  7. Mitigation of methane and nitrous oxide emissions from drained irrigated rice fields.

    PubMed

    Towprayoon, S; Smakgahn, K; Poonkaew, S

    2005-06-01

    One of the important cultural practices that affect methane and nitrous oxide emissions from tropical rice plantations is the water drainage system. While drainage can reduce methane emissions, it can also increase nitrous oxide emissions, as well as reduce yields. In this experiment, four different water drainage systems were compared in a rice field in central Thailand including: (1) continuous flooding, (2) mid-season drainage, (3) multiple drainage and (4) a local method (drainage was done according to local cultural practice) in order to find a system of drainage that would optimize yields while simultaneously limiting methane and nitrous oxide emissions. Methane and nitrous oxide emission were observed and compared with rice yield and physical changes of rice plants. It was found that drainage during the flowering period could reduce methane emission. Interestingly, nitrous oxide emission was related to number of drain days rather than the frequency of draining. Fewer drain days can help reduce nitrous oxide emission. The mid-season drainage and the multiple drainage, with 6.9% and 11.4% reduction in rice yield, respectively, had an average methane emission per crop 27% and 35% lower when compared to the local method. Draining with fewer drain days during the flowering period was recommended as a compromise between emissions and yield. The field drainage can be used as an option to reduce methane and nitrous oxide emissions from rice fields with acceptable yield reduction. Mid-season drainage during the rice flowering period, with a shortened drainage period (3 days), is suggested as a compromise between the need to reduce global warming and current socio-economic realities. PMID:15894043

  8. Unexpectedly High Methane Emissions through Black Ash Lenticels in Forest Wetlands of Northern Michigan

    NASA Astrophysics Data System (ADS)

    Bolton, N. W.; Van Grinsven, M. J.; Shannon, J.; Davis, J.; Sebestyen, S. D.; Kolka, R. K.; Wagenbrenner, J. W.; Pypker, T. G.

    2014-12-01

    Methane (CH4) emissions from wetlands contribute 20-40% to the global CH4 budget, and most research has focused on diffusive, ebullitive and plant-arenchyma mediated transport pathways in soils. Recent studies have shown considerable amounts of CH4 to be emitted via the lenticel pathway. Forested wetlands cover approximately 9.9 million hectares in North America, and to our knowledge no study has previously compared emissions of CH4 through soil and lenticel pathways in North American forested wetlands. Our objectives were to quantify the fluxes of CH4 emissions via lenticels in black ash (Fraxinus nigra Marsh.) wetlands and evaluate some factors that may affect lenticel CH4 emissions. We measured CH4 emissions from nine black ash trees monthly during the 2014 growing season and compared the fluxes to those from collocated soil chambers in three forested wetlands in the Upper Peninsula of Michigan. During each sampling period, 15-mL samples were collected via syringe every ten minutes for a forty minute period. Water table depth, dissolved oxygen, air temperature, soil temperature, and lenticel density were recorded. Lenticel effluxes were up to 4.5 times greater than the soil effluxes and that water table position was correlated with soil and lenticel gas fluxes. We conclude CH4 emissions from forested wetlands may be considerably underestimated and our findings highlight the need for the inclusion of lenticel gas emissions in global estimates and Earth Systems Models.

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

    PubMed Central

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

    2014-01-01

    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. PMID:25266041

  10. Optimal estimation of North American methane emissions using GOSAT data: A contribution to the NASA Carbon Monitoring System

    NASA Astrophysics Data System (ADS)

    Turner, A. J.; Jacob, D. J.; Wecht, K.; Sulprizio, M.; Payne, V.; Santoni, G.; Wofsy, S. C.; Bowman, K. W.; Parker, R.; Boesch, H.

    2013-12-01

    We use methane observations from the Greenhouse Gases Observing SATellite (GOSAT) to constrain methane emissions from North America in support of the NASA Carbon Monitoring System. We apply two methods: (1) an adjoint-based 4DVAR inversion, and (2) an analytical inversion with an optimally reduced state vector enabling full characterization of the solution. The GOSAT methane retrievals are validated using aircraft data from the HIPPO campaign, and our overall 4DVAR framework is shown to compare successfully to a Lagrangian inversion of CalNex aircraft data over California. The adjoint-based method has high resolution but does not suitably characterize the information content of the data or the error in the optimized emissions. The analytical inversion is based on a Gaussian Mixture Model (GMM) to explore the actual information content of the GOSAT data by optimally reducing the dimensionality of the state vector. The Maximum A Posteriori (MAP) solution from the analytical inversion yields emission constraints consistent with the 4DVAR approach while allowing construction of the full posterior solution, averaging kernel matrix, and posterior covariance matrix in an easily parallelizable framework. We find that methane emissions from the Canadian wetlands are overestimated in current inventories and that the EDGARv4.2 anthropogenic inventory underestimates emissions over the south-central US. We will show preliminary results applying the GMM method over the duration of the GOSAT record. This method can evolve into an operational tool for monitoring of methane emissions from North America using satellite data and including characterization of uncertainties.

  11. 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.

  12. 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.

  13. Effect of methane emission increases in East Asia on atmospheric circulation and ozone

    NASA Astrophysics Data System (ADS)

    Shang, Lin; Liu, Yi; Tian, Wenshou; Zhang, Yuli

    2015-12-01

    We used a fully coupled chemistry-climate model (version 3 of the Whole Atmosphere Community Climate Model, WACCM3) to investigate the effect of methane (CH4) emission increases, especially in East Asia and North America, on atmospheric temperature, circulation and ozone (O3). We show that CH4 emission increases strengthen westerly winds in the Northern Hemisphere midlatitudes, accelerate the Brewer-Dobson (BD) circulation, and cause an increase in the mass flux across the tropopause. However, the BD circulation in the tropics between 10°S and 10°N at 100 hPa weakens as CH4 emissions increase in East Asia and strengthens when CH4 emissions increase in North America. When CH4 emissions are increased by 50% in East Asia and 15% globally, the stratospheric temperature cools by up to 0.15 K, and the stratospheric O3 increases by 45 ppbv and 60 ppbv, respectively. A 50% increase of CH4 emissions in North America (with an amplitude of stratospheric O3 increases by 60 ppbv) has a greater influence on the stratospheric O3 than the same CH4 emissions increase in East Asia. CH4 emission increases in East Asia and North America reduce the concentration of tropospheric hydroxyl radicals (4% and 2%, respectively) and increase the concentration of mid-tropospheric O3 (5% and 4%, respectively) in the Northern Hemisphere midlatitudes. When CH4 emissions increase in East Asia, the increase in the tropospheric O3 concentration is largest in August. When CH4 emissions increase in North America, the increase in the O3 concentration is largest in July in the mid-troposphere, and in April in the upper troposphere.

  14. Inverse modeling of methane sources and sinks using GOSAT and SCIAMACHY retrieved xCH4

    NASA Astrophysics Data System (ADS)

    Monteil, G.; Houweling, S.; Guerlet, S.; Schepers, D.; Aben, I.; Röckmann, T.

    2012-04-01

    Among all the anthropogenic greenhouse gases, methane is one of the most important since it accounts for roughly 25% of the human induced climate forcing. It is also one of the less well known, mainly because of the important, but poorly quantified, variability of its natural emissions. Methane emissions can be estimated using bottom-up inventories and inverse modelling methods, which make use of time series of surface concentration measurements. Unfortunately, the coverage of such ground-based measurements is mostly limited to populated areas (Northern-America, Europe, Eastern-Asia) and polar regions, whereas the observational constraints on fluxes in regions of important methane emissions, such as tropical forests and wetlands, are very limited. To overcome this problem, satellite measurements of total column averaged methane (xCH4) are studied for use in inverse modelling. Currently two satellites are in orbit capable of measuring total column averaged methane (xCH4) with sensitivity to the lower troposphere: The Japanese greenhouse gas observing satellite GOSAT (since early 2009) and the European atmospheric chemistry mission SCIAMACHY onboard ENVISAT (since 2003). Compared to SCIAMACHY, GOSAT offers an improved spectral resolution, which allows to retrieve methane independently from carbon dioxide (Butz et al, 2011). On the other hand, the spatial coverage of GOSAT is lower, which has implications, in particular for regions that experience frequent cloud cover. We evaluated the use of the RemoteC GOSAT retrievals for estimating methane emissions, in comparison with the use of NOAA ground-based measurements and SCIAMACHY, for the period June 2009 to June 2010. All the satellite inversions were able to significantly reduce the flux uncertainties over South-America, Africa and Asia, compared to the NOAA-only inversion. However, comparisons of our results with independent measurements show that GOSAT inversions are more capable of reproducing observed methane seasonal cycle and latitudinal gradients than those based on SCIAMACHY data. The GOSAT inversions also reproduce the vertical gradients of methane more accurately than the NOAA-only inversions. Our results demonstrate that the use of GOSAT retrievals constitutes an important step forward in global methane monitoring. In comparison with SCIAMACHY, the use of GOSAT leads to a significant improvement in consistency between the optimized model and independent data, which makes it a valuable tool for studying source/sink budgets of methane in the coming years.

  15. Impact of gypsum application on the methane emission from a wetland rice field

    SciTech Connect

    Denier van der Gon, H.A.C. ); Neue, H.U. )

    1994-06-01

    Methane is an important greenhouse gas, accounting for about 17% of the greenhouse effect during the 1980's, and playing an important role in atmospheric chemistry. Studies on the atmospheric methane cycle have stressed the need for identification of individual methane sources and their source strength. A next step is to look for possibilities to stabilize or even reduce atmospheric methane mixing rations. This study looks at the impact of sulfur-containing fertizers, specifically gypsum, on methane emissions of rice fields. In hibition studies have demonstrated that sulfate reducers, in the presence of sulfate can outcompete methanogens for substrates. Field experiments with gypsum applications were carried out in a Philippine rice paddy. The importance of different substrate levels was studied with and without organic manure. The results indicate that adding gypsum to a flooded rice field reduced methane emissions by 55-70%. Most likely the reduced emission was due to suppression of methanogens by sulfate-reducing bacteria. However, in hibition of methanogenesis was incomplete and appreciable methane emission still occured. 39 refs., 3 figs., 4 tabs.

  16. Spatial Variability of Soil Properties and Their Effect on Methane Generation, Oxidation, and Emission from Soils Covering Landfills

    NASA Astrophysics Data System (ADS)

    Imhoff, P. T.; Mei, C.; Yazdani, R.; Han, B.; Mostafid, M.

    2013-12-01

    Soils covering landfills mitigate gas emissions from degrading refuse, particularly emissions of methane, a potent greenhouse gas. To enhance the oxidative capacity of these soils, materials with high organic matter are proposed for landfill covers, e.g., compost and aged greenwaste. We report field tests of these materials in pilot-scale test cells. While moisture conditions and gas transport were initially uniform, after one year significant spatial variability of gas flow developed that was associated with spatially variable dry bulk density and volumetric water content. For a test cell with organic matter content of 38%, a single-domain porous medium model was adequate for describing water retention and continuum modeling was capable of describing spatially variable gas flow and methane oxidation. A second test cell with organic matter of 61% was best described as a dual-domain porous medium, and continuum modeling was inadequate for describing spatially variable gas flow. Here, the dual-domain medium resulted in significant subgrid scale variability in moisture conditions that affected gas transport and methane oxidation. The results from these field tests suggest that proposed one-dimensional models of gas transport and methane oxidation in landfill cover soils may be inadequate for soils composed of high organic matter that require dual-domain models for water retention.

  17. 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

  18. 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.

  19. Comparative methane emission by ratites: Differences in food intake and digesta retention level out methane production.

    PubMed

    Frei, Samuel; Hatt, Jean-Michel; Ortmann, Sylvia; Kreuzer, Michael; Clauss, Marcus

    2015-10-01

    Ratites differ in the anatomy of their digestive organs and their digesta excretion patterns. Ostriches (Struthio camelus) have large fermentation chambers and long digesta retention, emus (Dromaius novaehollandiae) have a short gut and short retention times, and rheas (Rhea americana) are intermediate. A recent study showed that ostriches produce as much methane (CH4) as expected for a similar-sized, non-ruminant mammalian herbivore. We hypothesized that emus and rheas produce less CH4 than ostriches. We individually measured, by chamber respirometry, the amount of O2 consumed as well as CO2 and CH4 emitted from six adult rheas (body mass 23.4±8.3 kg) and two adult emus (33.5 and 32.0 kg) during 23-hour periods on a pelleted lucerne diet. In contrast to previous studies, which classified emus as non-producers, we measured CH4 emissions at 7.39 and 6.25 L/day for emus and 2.87±0.82 L/day for rheas, which is close to values expected for similar-sized non-ruminant mammals for both species. O2 consumption was of a similar magnitude as reported previously. Across ratites, CH4 yield (L/kg dry matter intake) was positively correlated with mean retention time of food particles in the gut, similar to findings within ruminant species. In ratites, this relationship leads to similar body mass-specific CH4 production for a high intake/short retention and a low intake/long retention strategy. Therefore, when investigating CH4 production in herbivorous birds, it is advisable to consider various CH4 measures, not only yield or absolute daily amount alone. PMID:26123777

  20. Methane emissions from a coastal lagoon: Vembanad Lake, West Coast, India.

    PubMed

    Verma, Anuradha; Subramanian, V; Ramesh, R

    2002-06-01

    An attempt has been made to estimate methane fluxes from a tropical coastal wetland the Vembanad Lake, a lagoon along the West Coast of India. It has been found that Vembanad Lake contributes significant amount of methane to the atmosphere. Average emissions varied spatially within the lake. Methane emissions were 193.2 +/- 24.5 mg m(-2) h(-1) at Kumaragam (fresh water) as compared to 9.3 +/- 9.6 mgm(-2) h(-1) at Pullot (brackish water) site. Seasonal variation was significant between pre- and post-monsoons. Soil temperature, time of the day, salinity sediment organic carbon, all control the rate of methane emissions from the Vembanad Lake. PMID:12079082

  1. Methane Emission Quantification at the Farm Scale Using Boundary-Layer Volume Budgets

    NASA Astrophysics Data System (ADS)

    Stieger, J.; Eugster, W.; Siegwolf, R. T.; Buchmann, N. C.

    2012-12-01

    Agriculture plays an important role in the global greenhouse gas budget. Especially emissions of CH4 from livestock and manure management are of key importance. In Switzerland, roughly 80% of all national methane emissions originate from the agricultural sector. However, methane emissions in Switzerland so far were not measured but were estimated via emission factors for enteric fermentation of livestock and for manure management. This results in high uncertainties associated with emission estimates (up to 55%). Our study aims at quantifying methane emissions at the farm scale. We explored whether boundary-layer budget quantifications of methane can be used for the validation of emission estimates, and hence for the reduction of associated uncertainties in national inventory reports under the Kyoto Protocol. We will present methane emission budgets based on concentration profiles obtained from tethered balloon measurements from several campaigns carried out over two consecutive years (2011 and 2012). We will show how CH4 emissions at the farm scale (0.5 - 5 km2) were quantified using this boundary-layer budgeting approach. Clear diurnal courses of CH4 fluxes showed, that the temporal and spatial variability of emissions and atmospheric processes played an important role for source strength estimation. As an effect of these processes, budget quantifications differed up to 45% compared to the national inventory estimates. While the major determinants of methane emission budgets are still unclear, we will show that the ?13C ratios in CH4 concentrations did provide additional information about the processes responsible for the CH4 fluxes obtained.

  2. 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.

  3. Methane emissions from lakes and floodplains in Pantanal, Brazil

    NASA Astrophysics Data System (ADS)

    Marani, L.; Alvalá, P. C.

    To evaluate the tropical wetlands contribution to the methane (CH 4) burden better, field campaigns were performed during 2004 and 2005 near the Miranda River, in five sites inside the Brazilian Pantanal region. The CH 4 fluxes were determined using the static chamber technique. Environmental variables that may affect CH 4 emissions, as the water depth, the water and air temperatures were also measured. The overall average of the 320 individual CH 4 flux measurements made between March/2004 and March/2005 was 142±314 mg CH 4 m -2 d -1, which is a value near the ones observed in other tropical flooded regions. About 47% of the fluxes measurements presented nonlinear increases in the chamber concentrations, which were assumed to be linked to CH 4 losses through bubbles. The bubble flux represented about 90% of the total CH 4 losses in the measurements and ranged from 1 to 2187 mg CH 4 m -2 d -1 with an average of 292±410 mg CH 4 m -2 d -1 (median: 153 mg CH 4 m -2 d -1). The diffusive flux ranged from 1 to 124 mg CH 4 m -2 d -1, with an average of 10±17 mg CH 4 m -2 d -1 (median: 5 mg CH 4 m -2 d -1). The fluxes from lakes were smaller than those observed in the floodplains, where the flooding was more dependent on the seasonal cycle. The diffusive flux showed a slight, but not statistically significant seasonal variation, following the seasonal variation of the flooding of the Pantanal region. A rough estimative of the total annual CH 4 emission shows that the contribution of the Pantanal is about 3.3 Tg CH 4 yr -1, which represents about 3.3% of the total CH 4 emissions estimated to be originated in wetlands ecosystems. It may be a conservative estimate, which may present a large interannual variation, since it was obtained during one of the lowest flood of the Pantanal in recent years.

  4. 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.

  5. Methane and nitrous oxide emissions from municipal wastewater treatment - results from a long-term study.

    PubMed

    Daelman, M R J; van Voorthuizen, E M; van Dongen, L G J M; Volcke, E I P; van Loosdrecht, M C M

    2013-01-01

    Methane and nitrous oxide emissions from a fully covered municipal wastewater treatment plant were measured on-line during 16 months. At the plant under study, nitrous oxide contributed three-quarters to the plant's carbon footprint, while the methane emission was slightly larger than the indirect carbon dioxide emission related to the plant's electricity and natural gas consumption. This contrasted with two other wastewater treatment plants, where more than 80% of the carbon footprint came from the indirect carbon dioxide emission. The nitrous oxide emission exhibited a seasonal dynamic, of which the cause remains unclear. Three types of air filter were investigated with regard to their effectiveness to remove methane from the off-gas. PMID:23676409

  6. Methane Emissions in the London Region: Deciphering Regional Sources with Mobile Measurements

    NASA Astrophysics Data System (ADS)

    Zazzeri, G.; Lowry, D.; Fisher, R. E.; France, J. L.; Lanoisellé, M.; Bjorkegren, A.; Nisbet, E. G.

    2014-12-01

    Methane stable isotope analysis, coupled with mole fraction measurement, has been used to link isotopic signature to methane emissions from the leading methane sources in the London region, such as landfills and gas leaks. A mobile Picarro G2301 CRDS analyser was installed in a vehicle, together with an anemometer and a Hemisphere GPS receiver, to measure atmospheric methane mole fractions and their relative location. When methane plumes were located and intercepted, air samples were collected in Tedlar bags, for ?13C-CH4 isotopic analysis by CF-GC-IRMS (Continous Flow-Gas Chromatography-Isotopic Ratio Mass Spectroscopy). This method provides high precision isotopic values, determining ?13C-CH4 to ±0.05 per mil. The bulk signature of the methane plume into the atmosphere from the whole source area was obtained by Keeling plot analysis, and a ?13C-CH4 signature, with the relative uncertainty, allocated to each methane source investigated. The averaged ?13C-CH4 signature for landfill sites around the London region is - 58 ± 3 ‰, whereas the ?13C-CH4 signature for gas leaks is fairly constant at -36 ± 2 ‰, a value characteristic of North Sea supply. The Picarro G2301 analyser was installed also on the roof of King's College London, located in the centre of the city, and connected to an air inlet located 7 meters above roof height. An auto-sampler was connected to the same air inlet and launched remotely when a high nocturnal build up was expected, allowing up to twenty air bags to be collected for methane isotopic analysis over a 24 hour period. The main source contributing to overnight methane build up in central London is fugitive gas, in agreement with inventories. From the isotopic characterisation of urban methane sources and the source mix in London, the contribution to the urban methane budget and the local distribution of the methane sources given in inventories can be validated.

  7. 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

  8. Methane emissions from termites - landscape level estimates and methods of measurement

    NASA Astrophysics Data System (ADS)

    Jamali, Hizbullah; Livesley, Stephen J.; Hutley, Lindsay B.; Arndt, Stefan K.

    2013-04-01

    Termites contribute between <5 and 19% of the global methane emissions. These estimates have large uncertainties because of the limited number of field-based studies and species investgated, as well as issues of diurnal and seasonal variations. We measured methane fluxes from four common mound-building termite species diurnally and seasonally in tropical savannas in the Northern Territory, Australia. Our results showed that there were significant diel and seasonal variations of methane emissions from termite mounds and we observed large species-specific differences. On a diurnal basis, methane fluxes were least at the coolest time of the day and greatest at the warmest for all species for both wet and dry seasons. We observed a strong and significant positive correlation between methane flux and mound temperature for all species. Fluxes in the wet season were 5-26-fold greater than those in the dry season and this was related to population dynamics of the termites. We observed significant relationships between mound methane flux and mound carbon dioxide flux, enabling the prediction of methane flux from measured carbon dioxide flux. However, these relationships were clearly termite species specific. We also determined significant relationships between mound flux and gas concentration inside mound, for both gases, and for all termite species, thereby enabling the prediction of flux from measured mound internal gas concentration. However, these relationships were also termite species specific. Consequently, there was no generic relationship that would enable an easier prediction of methane flux from termite mounds. On a landscape scale we estimated that termites were a methane source of +0.24 kg methane-C ha-1 year-1 whilst savanna soils were a methane sink of 1.14 kg methane-C ha-1 year-1. Termites therefore only offset 21% of methane consumed by savanna soil resulting in net sink strength of -0.90 kg methane-C ha-1 year-1 for these savannas. Assuming a similar contribution of termites in the savannas and tropical rain forests worldwide, termites would globally produce around 27 Tg CO2-e year-1, which is 0.2% of the global methane source budget or an order of magnitude smaller than many of the previous estimates.

  9. 2004 Methane and Nitrous Oxide Emissions from Manure Management in South Africa.

    PubMed

    Moeletsi, Mokhele Edmond; Tongwane, Mphethe Isaac

    2015-01-01

    Manure management in livestock makes a significant contribution towards greenhouse gas emissions in the Agriculture; Forestry and Other Land Use category in South Africa. Methane and nitrous oxide emissions are prevalent in contrasting manure management systems; promoting anaerobic and aerobic conditions respectively. In this paper; both Tier 1 and modified Tier 2 approaches of the IPCC guidelines are utilized to estimate the emissions from South African livestock manure management. Activity data (animal population, animal weights, manure management systems, etc.) were sourced from various resources for estimation of both emissions factors and emissions of methane and nitrous oxide. The results show relatively high methane emissions factors from manure management for mature female dairy cattle (40.98 kg/year/animal), sows (25.23 kg/year/animal) and boars (25.23 kg/year/animal). Hence, contributions for pig farming and dairy cattle are the highest at 54.50 Gg and 32.01 Gg respectively, with total emissions of 134.97 Gg (3104 Gg CO? Equivalent). Total nitrous oxide emissions are estimated at 7.10 Gg (2272 Gg CO? Equivalent) and the three main contributors are commercial beef cattle; poultry and small-scale beef farming at 1.80 Gg; 1.72 Gg and 1.69 Gg respectively. Mitigation options from manure management must be taken with care due to divergent conducive requirements of methane and nitrous oxide emissions requirements. PMID:26479229

  10. A Multi-tower Measurement Network Estimate of California's Methane Emissions

    SciTech Connect

    Jeong, Seongeun; Hsu, Ying-Kuang; Andrews, Arlyn E.; Bianco, Laura; Vaca, Patrick; Wilczak, James M.; Fischer, Marc L.

    2013-12-02

    We present an analysis of methane (CH{sub 4}) emissions using atmospheric observations from five sites in California’s Central Valley across different seasons (September 2010 to June 2011). CH{sub 4} emissions for spatial regions and source sectors are estimated by comparing measured CH{sub 4} mixing ratios with transport model (WRF-STILT) predictions based on two 0.1 degree CH{sub 4} (seasonally varying “California-specific” (CALGEM) and a static global (EDGAR42)) prior emission models. Region-specific Bayesian analyses indicate that for California’s Central Valley the CALGEM- and EDGAR42-based inversions provide consistent annual total CH{sub 4} emissions (32.87±2.09 vs. 31.60±2.17 Tg CO{sub 2}eq yr{sup -1}; 68% C.I., assuming uncorrelated errors between regions). Summing across all regions of California, optimized CH{sub 4} emissions are only marginally consistent between CALGEM- and EDGAR42-based inversions (48.35±6.47 vs. 64.97±11.85 Tg CO{sub 2}eq), because emissions from coastal urban regions (where landfill and natural gas emissions are much higher in EDGAR than CALGEM) are not strongly constrained by the measurements. Combining our results with those from a recent study of the South Coast air basin narrows the range of estimates to 43 – 57 Tg CO{sub 2}eq yr{sup -1} (1.3 - 1.8 times higher than the current state inventory). These results suggest that the combination of rural and urban measurements will be necessary to verify future changes in California’s total CH{sub 4} emissions.

  11. The Application Of Biofilter System For Reduction Of Methane Emissions From Modern Sanitary Landfills

    NASA Astrophysics Data System (ADS)

    Sung, K.; Park, S.

    2007-12-01

    Increased atmospheric concentrations of greenhouse gases (GHG) caused by anthropogenic activities has been related to global climate change. Methane, the second most important GHG after CO2, is 21 times more effective at trapping heat than CO2. Therefore, methane emission control is of utmost importance for global warming reduction. To minimize leachate production and protect groundwater resources, modern sanitary landfills are equipped with composite covers and gas collection systems. Methane from modern sanitary landfills is vented directly to the atmosphere, except for some of the largest landfills where it is recovered as energy and burned at the site. However, the efficiency of energy recovery systems in larger landfills is reduced as the amount of CH4 generated from landfill begins to decrease. In this study, the performance of a lab-scale model biofilter system was investigated to treat CH4 gas emitted from modern sanitary landfills by conducting batch and column experiments using landfill cover soil amended with earthworm cast as the filter bed medium. From the batch experiments to measure the influence of moisture content and temperature of the filter medium on CH4 removal capacity of a biofilter system, the optimum moisture content and temperature were found to be 10-15% by weight and 25-35°C, respectively. The column experiment was conducted to measure the influence of inlet CH4 concentration and CH4 loading rate on CH4 removal capacity of a biofilter system. As the inlet CH4 concentration decreased, the percentage of CH4 oxidized increased. Up to a CH4 loading rate of 2785 g CH4 m3 h- 1 (EBRT = 7.7 min), the CH4 removal efficiency of the biofilter was able to reach 100%. Based on the results of the study, the installation of a properly managed biofilter system should be capable of achieving a reduction in atmospheric CH4 emissions from modern sanitary landfills at low CH4 generation stage.

  12. 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.

  13. Methane (CH4) emission from a tidal marsh in the Min River estuary, southeast China.

    PubMed

    Tong, Chuan; Wang, Wei-Qi; Zeng, Cong-Sheng; Marrs, Rob

    2010-01-01

    The total methane emission to the atmosphere and hydrosphere, and its seasonal variation, were estimated using an enclosed static chamber technique from a tidal marshes dominated by Phragmites australis (common reed) in the Min River estuary, southeast China. Measurements were taken at three tidal stages (before flood, during the flooding and ebbing process, and after ebb). Potential rates of methane production from the marsh sediment layers were also measured using an incubation technique. This P. australis tidal marsh was a net methane source, emitting 32.59 and 6.87 g CH(4) x m(-2) x yr(-1) to the atmosphere and hydrosphere, respectively. There was considerable monthly variation with emissions greater before flood in some months, whereas at other months emission was greater after ebb. The average methane fluxes were 5.13, 5.06 and 4.74 mg CH(4) m(-2) h(-1) before flood, during flooding and ebbing, and after ebb, respectively. Emissions to the tidewater and the atmosphere during the flooding and ebbing process were 2.98 and 2.08 mg CH(4) m(-2) h(-1),respectively. Sediment methane production potential (0-40 cm depth) ranged from 0.028-0.123 micro g CH(4) x g(-1) x d(-1), with the greatest production was in the surface soil. Methane fluxes had a significant correlation with atmospheric, sediment temperature and above ground biomass. The implications of these data for global warming are discussed briefly. PMID:20390897

  14. Reducing Open Cell Landfill Methane Emissions with a Bioactive Alternative Daily

    SciTech Connect

    Helene Hilger; James Oliver; Jean Bogner; David Jones

    2009-03-31

    Methane and carbon dioxide are formed in landfills as wastes degrade. Molecule-for-molecule, methane is about 20 times more potent than carbon dioxide at trapping heat in the earth's atmosphere, and thus, it is the methane emissions from landfills that are scrutinized. For example, if emissions composed of 60% methane and 40% carbon dioxide were changed to a mix that was 40% methane and 60% carbon dioxide, a 30% reduction in the landfill's global warming potential would result. A 10% methane, 90% carbon dioxide ratio will result in a 75% reduction in global warming potential compared to the baseline. Gas collection from a closed landfill can reduce emissions, and it is sometimes combined with a biocover, an engineered system where methane oxidizing bacteria living in a medium such as compost, convert landfill methane to carbon dioxide and water. Although methane oxidizing bacteria merely convert one greenhouse gas (methane) to another (carbon dioxide), this conversion can offer significant reductions in the overall greenhouse gas contribution, or global warming potential, associated with the landfill. What has not been addressed to date is the fact that methane can also escape from a landfill when the active cell is being filled with waste. Federal regulations require that newly deposited solid waste to be covered daily with a 6 in layer of soil or an alternative daily cover (ADC), such as a canvas tarp. The aim of this study was to assess the feasibility of immobilizing methane oxidizing bacteria into a tarp-like matrix that could be used for alternative daily cover at open landfill cells to prevent methane emissions. A unique method of isolating methanotrophs from landfill cover soil was used to create a liquid culture of mixed methanotrophs. A variety of prospective immobilization techniques were used to affix the bacteria in a tarp-like matrix. Both gel encapsulation of methanotrophs and gels with liquid cores containing methanotrophs were readily made but prone to rapid desiccation. Bacterial adsorption onto foam padding, natural sponge, and geotextile was successful. The most important factor for success appeared to be water holding capacity. Prototype biotarps made with geotextiles plus adsorbed methane oxidizing bacteria were tested for their responses to temperature, intermittent starvation, and washing (to simulate rainfall). The prototypes were mesophilic, and methane oxidation activity remained strong after one cycle of starvation but then declined with repeated cycles. Many of the cells detached with vigorous washing, but at least 30% appeared resistant to sloughing. While laboratory landfill simulations showed that four-layer composite biotarps made with two different types of geotextile could remove up to 50% of influent methane introduced at a flux rate of 22 g m{sup -2} d{sup -1}, field experiments did not yield high activity levels. Tests revealed that there were high hour-to-hour flux variations in the field, which, together with frequent rainfall events, confounded the field testing. Overall, the findings suggest that a methanotroph embedded biotarp appears to be a feasible strategy to mitigate methane emission from landfill cells, although the performance of field-tested biotarps was not robust here. Tarps will likely be best suited for spring and summer use, although the methane oxidizer population may be able to shift and adapt to lower temperatures. The starvation cycling of the tarp may require the capacity for intermittent reinoculation of the cells, although it is also possible that a subpopulation will adapt to the cycling and become dominant. Rainfall is not expected to be a major factor, because a baseline biofilm will be present to repopulate the tarp. If strong performance can be achieved and documented, the biotarp concept could be extended to include interception of other compounds beyond methane, such as volatile aromatic hydrocarbons and chlorinated solvents.

  15. 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

    ... Methane Emission Factors for Natural Gas Distribution W Table W Protection of Environment ENVIRONMENTAL... Natural Gas Systems Definitions. Pt. 98, Subpt. W, Table W-7 Table W-7 of Subpart W of Part 98—Default Methane Emission Factors for Natural Gas Distribution Natural gas distribution Emission factor...

  16. 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

    ... Methane Emission Factors for Natural Gas Distribution W Table W Protection of Environment ENVIRONMENTAL... Natural Gas Systems Definitions. Pt. 98, Subpt. W, Table W-7 Table W-7 of Subpart W of Part 98—Default Methane Emission Factors for Natural Gas Distribution Natural gas distribution Emission factor...

  17. 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

  18. Satellite Microwave Detection of Boreal-Arctic Wetland Inundation Changes and Their Impact on Regional Methane Emission Estimates

    NASA Astrophysics Data System (ADS)

    Watts, J. D.; Kimball, J. S.; Bartsch, A.

    2014-12-01

    Surface water inundation strongly regulates land-atmosphere energy and carbon exchange in northern environments. However, the dynamic nature of inundation in boreal-Arctic landscapes, and the impact of changing surface water extent on wetland methane (CH4) emissions, is not well understood. We examine recent (2003-2011) changes and spatiotemporal variability in surface inundation across high latitude wetland regions (> 45 deg. N) using passive microwave remote sensing retrievals of fractional open water extent (Fw) derived from Advanced Microwave Scanning Radiometer for EOS (AMSR-E) 18.7 and 23.8 GHz brightness temperatures. The daily Fw retrievals are sensitive to sub-grid scale (~25-km resolution) open water area (e.g. lakes and emergent vegetation), and are insensitive to solar illumination and atmosphere contamination effects. We also explore the potential implications of surface Fw variability on high latitude methane emissions using a remote sensing data driven model sensitivity analysis. Our results show widespread surface wetting across the Arctic continuous permafrost zone, which increased model simulated high latitude methane emissions by 0.56 Tg CH4 yr-1 relative to the 2003-2011 mean. This increase was largely offset (-0.38 Tg CH4 yr-1) by drying in boreal Alaska, Canada and western Eurasia. We also find that accounting for dynamic Fw variability in model simulations may significantly lower regional methane emission budgets. These findings accentuate the need for frequent satellite remote sensing driven Fw monitoring across the high latitude systems, to better assess regional sensitivities to climate change. An extended Fw record using AMSR2 data and enhanced (3-9 km) resolution L-band active/passive microwave retrievals from the NASA Soil Moisture Active Passive mission, are expected to improve understanding of regional surface water trends and variability, and reduce uncertainty in boreal-Arctic wetland emission estimates.

  19. Methane airborne measurements and comparison to global models during BARCA

    NASA Astrophysics Data System (ADS)

    Beck, Veronika; Chen, Huilin; Gerbig, Christoph; Bergamaschi, Peter; Bruhwiler, Lori; Houweling, Sander; Röckmann, Thomas; Kolle, Olaf; Steinbach, Julia; Koch, Thomas; Sapart, Célia J.; van der Veen, Carina; Frankenberg, Christian; Andreae, Meinrat O.; Artaxo, Paulo; Longo, Karla M.; Wofsy, Steven C.

    2012-08-01

    Tropical regions, especially the Amazon region, account for large emissions of methane (CH4). Here, we present CH4 observations from two airborne campaigns conducted within the BARCA (Balanço Atmosférico Regional de Carbono na Amazônia) project in the Amazon basin in November 2008 (end of the dry season) and May 2009 (end of the wet season). We performed continuous measurements of CH4 onboard an aircraft for the first time in the Amazon region, covering the whole Amazon basin with over 150 vertical profiles between altitudes of 500 m and 4000 m. The observations support the finding of previous ground-based, airborne, and satellite measurements that the Amazon basin is a large source of atmospheric CH4. Isotope analysis verified that the majority of emissions can be attributed to CH4 emissions from wetlands, while urban CH4 emissions could be also traced back to biogenic origin. A comparison of five TM5 based global CH4 inversions with the observations clearly indicates that the inversions using SCIAMACHY observations represent the BARCA observations best. The calculated CH4 flux estimate obtained from the mismatch between observations and TM5-modeled CH4 fields ranges from 36 to 43 mg m-2 d-1 for the Amazon lowland region.

  20. 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.

  1. A model of the methane cycle, permafrost, and hydrology of the Siberian continental margin

    DOE PAGESBeta

    Archer, D.

    2014-06-03

    A two-dimensional model of a passive continental margin was adapted to the simulation of the methane cycle on Siberian continental shelf and slope, attempting to account for the impacts of glacial/interglacial cycles in sea level, alternately exposing the continental shelf to freezing conditions with deep permafrost formation during glacial times, and immersion in the ocean in interglacial times. The model is used to gauge the impact of the glacial cycles, and potential anthropogenic warming in the deep future, on the atmospheric methane emission flux, and the sensitivities of that flux to processes such as permafrost formation and terrestrial organic carbonmore »(Yedoma) deposition. Hydrological forcing drives a freshening and ventilation of pore waters in areas exposed to the atmosphere, which is not quickly reversed by invasion of seawater upon submergence, since there is no analogous saltwater pump. This hydrological pump changes the salinity enough to affect the stability of permafrost and methane hydrates on the shelf. Permafrost formation inhibits bubble transport through the sediment column, by construction in the model. The impact of permafrost on the methane budget is to replace the bubble flux by offshore groundwater flow containing dissolved methane, rather than accumulating methane for catastrophic release when the permafrost seal fails during warming. By far the largest impact of the glacial/interglacial cycles on the atmospheric methane flux is attenuation by dissolution of bubbles in the ocean when sea level is high. Methane emissions are highest during the regression (soil freezing) part of the cycle, rather than during transgression (thawing). The model-predicted methane flux to the atmosphere in response to a warming climate is small, relative to the global methane production rate, because of the ongoing flooding of the continental shelf. A slight increase due to warming could be completely counteracted by sea level rise on geologic time scales, decreasing the efficiency of bubble transit through the water column. The methane cycle on the shelf responds to climate change on a long time constant of thousands of years, because hydrate is excluded thermodynamically from the permafrost zone by water limitation, leaving the hydrate stability zone at least 300 m below the sediment surface.« less

  2. A model of the methane cycle, permafrost, and hydrology of the Siberian continental margin

    NASA Astrophysics Data System (ADS)

    Archer, D.

    2014-06-01

    A two-dimensional model of a passive continental margin was adapted to the simulation of the methane cycle on Siberian continental shelf and slope, attempting to account for the impacts of glacial/interglacial cycles in sea level, alternately exposing the continental shelf to freezing conditions with deep permafrost formation during glacial times, and immersion in the ocean in interglacial times. The model is used to gauge the impact of the glacial cycles, and potential anthropogenic warming in the deep future, on the atmospheric methane emission flux, and the sensitivities of that flux to processes such as permafrost formation and terrestrial organic carbon (Yedoma) deposition. Hydrological forcing drives a freshening and ventilation of pore waters in areas exposed to the atmosphere, which is not quickly reversed by invasion of seawater upon submergence, since there is no analogous saltwater pump. This hydrological pump changes the salinity enough to affect the stability of permafrost and methane hydrates on the shelf. Permafrost formation inhibits bubble transport through the sediment column, by construction in the model. The impact of permafrost on the methane budget is to replace the bubble flux by offshore groundwater flow containing dissolved methane, rather than accumulating methane for catastrophic release when the permafrost seal fails during warming. By far the largest impact of the glacial/interglacial cycles on the atmospheric methane flux is attenuation by dissolution of bubbles in the ocean when sea level is high. Methane emissions are highest during the regression (soil freezing) part of the cycle, rather than during transgression (thawing). The model-predicted methane flux to the atmosphere in response to a warming climate is small, relative to the global methane production rate, because of the ongoing flooding of the continental shelf. A slight increase due to warming could be completely counteracted by sea level rise on geologic time scales, decreasing the efficiency of bubble transit through the water column. The methane cycle on the shelf responds to climate change on a long time constant of thousands of years, because hydrate is excluded thermodynamically from the permafrost zone by water limitation, leaving the hydrate stability zone at least 300 m below the sediment surface.

  3. Seasonal methane accumulation and release from a gas emission site in the central North Sea

    NASA Astrophysics Data System (ADS)

    Mau, S.; Gentz, T.; Körber, J. H.; Torres, M.; Römer, M.; Sahling, H.; Wintersteller, P.; Martinez, R.; Schlüter, M.; Helmke, E.

    2014-12-01

    Hydroacoustic data document the occurrence of 5 flare clusters and several single flares from which bubbles rise through the entire water column from an active seep site at 40 m water depth in the central North Sea. We investigated the difference in dissolved methane distributions along a 6 km transect crossing this seep site during a period of seasonal summer stratification (July 2013) and a period of well mixed winter water column (January 2014). Dissolved methane accumulated below the seasonal thermocline in summer with a median concentration of 390 nM, whereas during winter, methane concentrations were much lower (median concentration of 22 nM) and punctually elevated due to bubble transport. High resolution methane analysis by an underwater mass-spectrometer confirmed our summer results and were used to document prevailing stratification over the tidal cycle. Although sufficient methane was available, microbial methane oxidation was limited during both seasons. Measured and averaged rate constants (k') using Michaelis Menten kinetics were on the order of 0.01 days-1, equivalent to a turnover time of 100 days. Time series measurements indicated an uptake of only 5-6% of the gas after 4 days, and no known methanotrophs and pmoA-genes were detected. Estimated methane fluxes indicate that horizontal eddy transport rapidly disperses dissolved methane, vertical transport becomes dominant during phases of high wind speeds, and relative to these processes, microbial methane oxidation appears to be comparably low. To bridge the discrete field data we developed a 1-D seasonal model using available year-long records of wind speed, surface temperature and thermocline depth. The model simulations show a peak release of methane at the beginning of fall when the water column becomes mixed. Consistent with our field data, inclusion of microbial methane oxidation does not change the model results significantly, thus microbial oxidation appears to be not sufficient to notably reduce methane during summer stratification before the peak release in fall.

  4. Seasonal methane accumulation and release from a gas emission site in the central North Sea

    NASA Astrophysics Data System (ADS)

    Mau, Susan; Gentz, Torben; Körber, Jan-Hendrik; Torres, Marta; Römer, Miriam; Sahling, Heiko; Wintersteller, Paul; Martinez, Roi; Schlüter, Michael; Helmke, Elisabeth

    2015-04-01

    Hydroacoustic data document the occurrence of 5 flare clusters and several single flares from which bubbles rise through the entire water column from an active seep site at 40 m water depth in the central North Sea. We investigated the difference in dissolved methane distributions along a 6 km transect crossing this seep site during a period of seasonal summer stratification (July 2013) and a period of well mixed winter water column (January 2014). Dissolved methane accumulated below the seasonal thermocline in summer with a median concentration of 390 nM, whereas during winter, methane concentrations were much lower (median concentration of 22 nM) and punctually elevated due to bubble transport. High resolution methane analysis by an underwater mass-spectrometer confirmed our summer results and were used to document prevailing stratification over the tidal cycle. Although sufficient methane was available, microbial methane oxidation was limited during both seasons. Measured and averaged rate constants (k') using Michaelis Menten kinetics were on the order of 0.01 d-1, equivalent to a turnover time of 100 d. Time series measurements indicated an uptake of only 5-6% of the gas after 4 d, and no known methanotrophs and pmoA-genes were detected. Estimated methane fluxes indicate that horizontal eddy transport rapidly disperses dissolved methane, vertical transport becomes dominant during phases of high wind speeds, and relative to these processes, microbial methane oxidation appears to be comparably low. To bridge the discrete field data we developed a 1D seasonal model using available year-long records of wind speed, surface temperatures and thermocline depth. The model simulations show a peak release of methane at the beginning of fall when the water column becomes mixed. Consistent with our field data, inclusion of microbial methane oxidation does not change the model results significantly, thus microbial oxidation appears to be not sufficient to notably reduce methane during summer stratification before the peak release in fall.

  5. A quantification of methane emissions from the Bakken shale play region of North Dakota

    NASA Astrophysics Data System (ADS)

    Peischl, J.; Ryerson, T. B.; Karion, A.; Aikin, K. C.; Kort, E. A.; Newberger, T.; Smith, M. L.; Sweeney, C.; Trainer, M.; Wolter, S.

    2014-12-01

    Natural gas extracted from shale formations accounts for 40% of the domestic U.S. natural gas supply. Although natural gas combustion emits less carbon dioxide per energy produced than other fossil fuels, this climate benefit may be offset by the methane emitted to the atmosphere through leaks in the natural gas production and distribution infrastructure. To better understand the climate impacts of the oil and natural gas extracted from the Bakken shale play in North Dakota, we present airborne measurements of methane taken over this region aboard a NOAA Twin Otter aircraft during Spring 2014. Using the mass balance technique, we estimate methane emissions from the region with four flights intended for this purpose in May 2014. We further attribute these methane emissions to the oil and gas industry using measurements of ethane and other hydrocarbons aboard the Twin Otter.

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. Seasonal methane emissions from a beef cattle feedyard on the U.S. southern High Plains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cattle are a significant source of methane (CH4), a potent greenhouse gas that contributes to global warming. As cattle production systems intensify, a better understanding of CH4 emissions from cattle feedyards is needed to build more accurate emission inventories, help develop better predictive mo...

  1. 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...

  2. 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...

  3. AN IMPROVED INVENTORY OF METHANE EMISSIONS FROM COAL MINING IN THE UNITED STATES

    EPA Science Inventory

    Past efforts to estimate methane emissions from underground mines surface mines, and other coal mine operations have been hampered, to different degrees, by a lack of direct emissions data. Direct measurements have been completely unavailable for several important coal mining ope...

  4. 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...

  5. 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...

  6. Assessment of Methane Emissions from Oil and Gas Production using Mobile Measurements

    EPA Science Inventory

    Journal Article Abstract --- "A mobile source inspection approach called OTM 33A was used to quantify short-term methane emission rates from 218 oil and gas production pads in Texas, Colorado, and Wyoming from 2010 to 2013. The emission rates were log-normally distributed ...

  7. Quantifying methane and nitrous oxide emissions from the UK using a dense 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.

    2015-01-01

    The UK is one of several countries around the world that has enacted legislation to reduce its greenhouse gas emissions. Monitoring of emissions has been done through a detailed sectoral level bottom-up inventory (UK National Atmospheric Emissions Inventory, NAEI) from which national totals are submitted yearly to the United Framework Convention on Climate Change. In parallel, the UK government has funded four atmospheric monitoring stations to infer emissions through top-down methods that assimilate atmospheric observations. 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. 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 emissions of 2.08 (1.72-2.47) Tg yr-1 CH4 and 0.105 (0.087-0.127) Tg yr-1 N2O and found our derived estimates to be generally lower than the inventory. We used sectoral distributions from the 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 also found that N2O fertilizer emissions from the NAEI may be overestimated and 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 is possibly to do with sporadic emissions from landfills and offshore gas in the North Sea.

  8. 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.

  9. 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

  10. Emission of methane by Eudrilus eugeniae and other earthworms from Brazil.

    PubMed

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

    2012-04-01

    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

  11. 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.

  12. 2004 Methane and Nitrous Oxide Emissions from Manure Management in South Africa

    PubMed Central

    Moeletsi, Mokhele Edmond; Tongwane, Mphethe Isaac

    2015-01-01

    Simple Summary Livestock manure management is one of the main sources of greenhouse gas (GHG) emissions in South Africa producing mainly methane and nitrous oxide. The emissions from this sub-category are dependent on how manure is stored. Liquid-stored manure predominantly produces methane while dry-based manure enhances mainly production of nitrous oxide. Intergovernmental Panel on Climate Change (IPCC) guidelines were utilized at different tier levels in estimating GHG emissions from manure management. The results show that methane emissions are relatively higher than nitrous oxide emissions with 3104 Gg and 2272 Gg respectively in carbon dioxide global warming equivalent. Abstract Manure management in livestock makes a significant contribution towards greenhouse gas emissions in the Agriculture; Forestry and Other Land Use category in South Africa. Methane and nitrous oxide emissions are prevalent in contrasting manure management systems; promoting anaerobic and aerobic conditions respectively. In this paper; both Tier 1 and modified Tier 2 approaches of the IPCC guidelines are utilized to estimate the emissions from South African livestock manure management. Activity data (animal population, animal weights, manure management systems, etc.) were sourced from various resources for estimation of both emissions factors and emissions of methane and nitrous oxide. The results show relatively high methane emissions factors from manure management for mature female dairy cattle (40.98 kg/year/animal), sows (25.23 kg/year/animal) and boars (25.23 kg/year/animal). Hence, contributions for pig farming and dairy cattle are the highest at 54.50 Gg and 32.01 Gg respectively, with total emissions of 134.97 Gg (3104 Gg CO2 Equivalent). Total nitrous oxide emissions are estimated at 7.10 Gg (2272 Gg CO2 Equivalent) and the three main contributors are commercial beef cattle; poultry and small-scale beef farming at 1.80 Gg; 1.72 Gg and 1.69 Gg respectively. Mitigation options from manure management must be taken with care due to divergent conducive requirements of methane and nitrous oxide emissions requirements. PMID:26479229

  13. Climate-methane cycle feedback in global climate model model simulations forced by RCP scenarios

    NASA Astrophysics Data System (ADS)

    Eliseev, Alexey V.; Denisov, Sergey N.; Arzhanov, Maxim M.; Mokhov, Igor I.

    2013-04-01

    Methane cycle module of the global climate model of intermediate complexity developed at the A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM) is extended by coupling with a detailed module for thermal and hydrological processes in soil (Deep Soil Simulator, (Arzhanov et al., 2008)). This is an important improvement with respect with the earlier IAP RAS CM version (Eliseev et al., 2008) which has employed prescribed soil hydrology to simulate CH4 emissions from soil. Geographical distribution of water inundated soil in the model was also improved by replacing the older Olson's ecosystem data base by the data based on the SCIAMACHY retrievals (Bergamaschi et al., 2007). New version of the IAP RAS CM module for methane emissions from soil is validated by using the simulation protocol adopted in the WETCHIMP (Wetland and Wetland CH4 Inter-comparison of Models Project). In addition, atmospheric part of the IAP RAS CM methane cycle is extended by temperature dependence of the methane life-time in the atmosphere in order to mimic the respective dependence of the atmospheric methane chemistry (Denisov et al., 2012). The IAP RAS CM simulations are performed for the 18th-21st centuries according with the CMIP5 protocol taking into account natural and anthropogenic forcings. The new IAP RAS CM version realistically reproduces pre-industrial and present-day characteristics of the global methane cycle including CH4 concentration qCH4 in the atmosphere and CH4 emissions from soil. The latter amounts 150 - 160 TgCH4-yr for the late 20th century and increases to 170 - 230 TgCH4-yr in the late 21st century. Atmospheric methane concentration equals 3900 ppbv under the most aggressive anthropogenic scenario RCP 8.5 and 1850 - 1980 ppbv under more moderate scenarios RCP 6.0 and RCP 4.5. Under the least aggressive scenario RCP 2.6 qCH4 reaches maximum 1730 ppbv in 2020s and declines afterwards. Climate change impact on the methane emissions from soil enhances build up of the methane stock in the atmosphere by 10 - 25% depending on anthropogenic scenario and time instant. In turn, decrease of methane life-time in the atmosphere suppresses this build up by 5 - 40%. The net effect is uncertain but small in terms of resulting additional greenhouse radiative forcing. This smallness is reflected in small additional (relative to the model version with both methane emissions from soil and methane life-time in the atmosphere fixed at their preindustrial values) near-surface warming which globally is not larger than 1 K, i.e, ˜ 4% of warming exhibited by the model version neglecting climate-methane cycle interaction. References [1] M.M. Arzhanov, P.F. Demchenko, A.V. Eliseev, and I.I. Mokhov. Simulation of characteristics of thermal and hydrologic soil regimes in equilibrium numerical experiments with a climate model of intermediate complexity. Izvestiya, Atmos. Ocean. Phys., 44(5):279-287, 2008. doi: 10.1134/S0001433808050022. [2] P. Bergamaschi, C. Frankenberg, J.F. Meirink, M. Krol, F. Dentener, T. Wagner, U. Platt, J.O. Kaplan, S. Körner, M. Heimann, E.J. Dlugokencky, and A. Goede. Satellite chartography of atmospheric methane from SCIAMACHY on board ENVISAT: 2. Evaluation based on inverse model simulations. J. Geophys. Res., 112(D2):D02304, 2007. doi: 10.1029/2006JD007268. [3] S.N. Denisov, A.V. Eliseev, and I.I. Mokhov. Climate change in the IAP RAS global model with interactive methane cycle under RCP anthropogenic scenarios. Rus. Meteorol. Hydrol., 2012. [submitted]. [4] A.V. Eliseev, I.I. Mokhov, M.M. Arzhanov, P.F. Demchenko, and S.N. Denisov. Interaction of the methane cycle and processes in wetland ecosystems in a climate model of intermediate complexity. Izvestiya, Atmos. Ocean. Phys., 44(2):139-152, 2008. doi: 10.1134/S0001433808020011.

  14. 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.

  15. Does uncus 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.

    2015-10-01

    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 to 100 cm), and in most cases both above and below the groundwater table. During spring, local maxima suggested methanogenesis also 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. However, a significant effect of J. effusus was seen 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 J. effusus 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.

  16. Recent decreases in fossil-fuel emissions of ethane and methane derived from firn air.

    PubMed

    Aydin, Murat; Verhulst, Kristal R; Saltzman, Eric S; Battle, Mark O; Montzka, Stephen A; Blake, Donald R; Tang, Qi; Prather, Michael J

    2011-08-11

    Methane and ethane are the most abundant hydrocarbons in the atmosphere and they affect both atmospheric chemistry and climate. Both gases are emitted from fossil fuels and biomass burning, whereas methane (CH(4)) alone has large sources from wetlands, agriculture, landfills and waste water. Here we use measurements in firn (perennial snowpack) air from Greenland and Antarctica to reconstruct the atmospheric variability of ethane (C(2)H(6)) during the twentieth century. Ethane levels rose from early in the century until the 1980s, when the trend reversed, with a period of decline over the next 20?years. We find that this variability was primarily driven by changes in ethane emissions from fossil fuels; these emissions peaked in the 1960s and 1970s at 14-16 teragrams per year (1?Tg = 10(12)?g) and dropped to 8-10?Tg? yr(-1) by the turn of the century. The reduction in fossil-fuel sources is probably related to changes in light hydrocarbon emissions associated with petroleum production and use. The ethane-based fossil-fuel emission history is strikingly different from bottom-up estimates of methane emissions from fossil-fuel use, and implies that the fossil-fuel source of methane started to decline in the 1980s and probably caused the late twentieth century slow-down in the growth rate of atmospheric methane. PMID:21833087

  17. 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.

  18. Methane emission from animals: A Global High-Resolution Data Base

    NASA Astrophysics Data System (ADS)

    Lerner, Jean; Matthews, Elaine; Fung, Inez

    1988-06-01

    We present a high-resolution global data base of animal population densities and associated methane emission. Statistics on animal populations from the Food and Agriculture Organization and other sources have been compiled. Animals were distributed using a 1° resolution data base of countries of the world and a 1° resolution data base of land use. The animals included are cattle and dairy cows, water buffalo, sheep, goats, camels, pigs, horses and caribou. Published estimates of methane production from each type of animal have been applied to the animal populations to yield a global distribution of annual methane emission by animals. There is large spatial variability in the distribution of animal populations and their methane emissions. Emission rates greater than 5000 kg CH4 km-2 yr-1 are found in small regions such as Bangladesh, the Benelux countries, parts of northern India, and New Zealand. Of the global annual emission of 75.8 Tg CH4 for 1984, about 55% is concentrated between 25°N and 55°N, a significant contribution to the observed north-south gradient of atmospheric methane concentration. A magnetic tape of the global data bases is available from the authors.

  19. 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

  20. Measuring Methane Emissions from Industrial and Waste Processing Sites Using the Dual Tracer Flux Ratio Method

    NASA Astrophysics Data System (ADS)

    Herndon, S.; Floerchinger, C.; Roscioli, J. R.; Yacovitch, T.; Franklin, J. P.; Shorter, J. H.; Kolb, C. E.; Subramanian, R.; Robinson, A. L.; Molina, L. T.; Allen, D.

    2013-12-01

    In order to directly quantify facility scale methane emissions during recent multi-state measurement campaigns we have deployed novel tracer release emission characterization approaches to investigate a wide variety of facility types. The development and application of a dual tracer flux ratio methodology will be discussed. Using known release rates of two (or more) inert tracer species, downwind methane plume measurements can be used to quantify and evaluate the uncertainty in known releases and unknown emissions of methane. Results from experiments designed to challenge the experimental methodology will be presented, which determined that for downwind sampling distances in excess of ~200 m, the dual tracer release method is quite robust (<20% emission rate error) under many atmospheric conditions and landscape variations. At downwind distances less than ~200 m, the assumption of equivalent dispersion between spatially separated release points can break down. For some facilities, this can be used to distinguish and estimate the magnitude of methane emissions taking place at different spatial points within the facility. Measured emissions for selected facilities will be presented and, where possible, the accurate quantification of the episodic releases during specific activities, as well as continuous fugitive emissions are identified and will be discussed . Collaboration with on-site operators allows these measurements to inform the design and implementation of effective mitigation strategies.

  1. The impact of air pollutant and methane emission controls on tropospheric ozone and radiative forcing: CTM calculations for the period 1990-2030

    NASA Astrophysics Data System (ADS)

    Dentener, F.; Stevenson, D.; Cofala, J.; Mechler, R.; Amann, M.; Bergamaschi, P.; Raes, F.; Derwent, R.

    2004-12-01

    To explore the relationship between tropospheric ozone and radiative forcing with changing emissions, we compiled two sets of global scenarios for the emissions of the ozone precursors methane (CH4), carbon monoxide (CO), non-methane volatile organic compounds (NMVOC) and nitrogen oxides (NOx) up to the year 2030 and implemented them in two global Chemistry Transport Models. The "Current Legislation" (CLE) scenario reflects the current perspectives of individual countries on future economic development and takes the anticipated effects of presently decided emission control legislation in the individual countries into account. In addition, we developed a "Maximum technically Feasible Reduction" (MFR) scenario that outlines the scope for emission reductions offered by full implementation of the presently available emission control technologies, while maintaining the projected levels of anthropogenic activities. Whereas the resulting projections of methane emissions lie within the range suggested by other greenhouse gas projections, the recent pollution control legislation of many Asian countries, requiring introduction of catalytic converters for vehicles, leads to significantly lower growth in emissions of the air pollutants NOx, NMVOC and CO than was suggested by the widely used IPCC (Intergovernmental Panel on Climate Change) SRES (Special Report on Emission Scenarios) scenarios (Nakicenovic et al., 2000). With the TM3 and STOCHEM models we performed several long-term integrations (1990-2030) to assess global, hemispheric and regional changes in CH4, CO, hydroxyl radicals, ozone and the radiative climate forcings resulting from these two emission scenarios. Both models reproduce realistically the observed trends in background ozone, CO, and CH4 concentrations from 1990 to 2002. For the "current legislation" case, both models indicate an increase of the annual average ozone levels in the Northern hemisphere by 5 ppbv, and up to 15 ppbv over the Indian sub-continent, comparing the 2020s with the 1990s. The corresponding higher ozone and methane burdens in the atmosphere increase radiative forcing by approximately 0.2 Wm-2. Full application of today's emissions control technologies, however, would bring down ozone below the levels experienced in the 1990s and would reduce the current radiative forcing of ozone and methane by approximately 0.1Wm-2. While methane reductions lead to lower ozone burdens and to less radiative forcing, further reductions of the air pollutants NO4 and NMVOC result in lower ozone, but at the same time increase the lifetime of methane. Control of methane emissions appears an efficient option to reduce tropospheric ozone as well as radiative forcing.

  2. Microbial Methane Oxidation Processes and Technologies for Mitigation of Landfill Gas Emissions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The aim of this paper is to review the present knowledge regarding the microbial methane oxidation in natural or engineered landfill environments with focus on process understanding, engineering experiences and modeling. This review includes seven sections. First, the methane oxidation is put in con...

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

    PubMed

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

    2014-07-01

    Wetlands are the largest natural source of atmospheric methane. Here, we assess controls on methane flux using a database of approximately 19 000 instantaneous measurements from 71 wetland sites located across subtropical, temperate, and northern high latitude regions. Our analyses confirm general controls on wetland methane emissions from soil temperature, water table, and vegetation, but also show that these relationships are modified depending on wetland type (bog, fen, or swamp), region (subarctic to temperate), and disturbance. Fen methane flux was more sensitive to vegetation and less sensitive to temperature than bog or swamp fluxes. The optimal water table for methane flux was consistently below the peat surface in bogs, close to the peat surface in poor fens, and above the peat surface in rich fens. However, the largest flux in bogs occurred when dry 30-day averaged antecedent conditions were followed by wet conditions, while in fens and swamps, the largest flux occurred when both 30-day averaged antecedent and current conditions were wet. Drained wetlands exhibited distinct characteristics, e.g. the absence of large flux following wet and warm conditions, suggesting that the same functional relationships between methane flux and environmental conditions cannot be used across pristine and disturbed wetlands. Together, our results suggest that water table and temperature are dominant controls on methane flux in pristine bogs and swamps, while other processes, such as vascular transport in pristine fens, have the potential to partially override the effect of these controls in other wetland types. Because wetland types vary in methane emissions and have distinct controls, these ecosystems need to be considered separately to yield reliable estimates of global wetland methane release. PMID:24777536

  4. 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.

  5. Assessment of methane emissions from oil and gas production pads using mobile measurements.

    PubMed

    Brantley, Halley L; Thoma, Eben D; Squier, William C; Guven, Birnur B; Lyon, David

    2014-12-16

    A new mobile methane emissions inspection approach, Other Test Method (OTM) 33A, was used to quantify short-term emission rates from 210 oil and gas production pads during eight two-week field studies in Texas, Colorado, and Wyoming from 2010 to 2013. Emission rates were log-normally distributed with geometric means and 95% confidence intervals (CIs) of 0.33 (0.23, 0.48), 0.14 (0.11, 0.19), and 0.59 (0.47, 0.74) g/s in the Barnett, Denver-Julesburg, and Pinedale basins, respectively. This study focused on sites with emission rates above 0.01 g/s and included short-term (i.e., condensate tank flashing) and maintenance-related emissions. The results fell within the upper ranges of the distributions observed in recent onsite direct measurement studies. Considering data across all basins, a multivariate linear regression was used to assess the relationship of methane emissions to well age, gas production, and hydrocarbon liquids (oil or condensate) production. Methane emissions were positively correlated with gas production, but only approximately 10% of the variation in emission rates was explained by variation in production levels. The weak correlation between emission and production rates may indicate that maintenance-related stochastic variables and design of production and control equipment are factors determining emissions. PMID:25375308

  6. 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

  7. Quantification of the methane emission flux from the city of Indianapolis, IN: identification and contribution of sources

    NASA Astrophysics Data System (ADS)

    Cambaliza, M. L.; Shepson, P. B.; Stirm, B. H.; Caulton, D.; Miller, C.; Hendricks, A.; Moser, B.; Lavoie, T. N.; Salmon, O. E.; Karion, A.; Sweeney, C.; Turnbull, J. C.; Davis, K. J.; Lauvaux, T.; Crosson, E.; Prasad, K.; Whetstone, J. R.; Miles, N. L.; Richardson, S.

    2013-12-01

    We report the methane emission flux from the city of Indianapolis, IN, the site of the INFLUX project for developing, testing, and improving top-down and bottom-up methods for quantifying urban greenhouse gas emissions. Using an aircraft-based mass balance approach, we find that the average methane emission flux from Indianapolis is ~150 moles per second from several flight experiments, a factor of ~6 smaller than the total emissions from the Los Angeles Air Basin, CA (with a population that is 7 times greater than Indianapolis) for 2007 - 2010 (Wennberg et al., 2012). We also consistently observed elevated CH4 concentrations at specific coordinates along our horizontal transects downwind of the city. Inflight investigations as well as backtrajectories using measured wind directions showed that the elevated concentrations originate from the southwest side of the city where a landfill and a natural gas transmission regulating station (TRS) are located. Surface mobile measurements supported the results of aircraft-based data, and were used to quantify the relative contributions from the two sources as well as to determine other sources contributing to the citywide flux. We find that the emission from the TRS was negligible relative to the landfill, which was responsible for about a third of the citywide methane emission flux. Surface mobile data further suggests that most of the rest of the emission derive from the natural gas distribution system. Here we discuss the combination of surface mobile observations in concert with aircraft city-wide flux measurements to enable determination of the total flux and apportionment among sources. The latter will enable development of a set of prior emission fluxes useful for inverse modeling.

  8. 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

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

    SciTech Connect

    Song, Changchun; Xu, Xiaofeng; Sun, Xiaoxin; Tian, Hanqin; Sun, Li; Miao, Yuqing; Wang, Xianwei; Guo, Yuedong

    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.

  10. 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

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

    SciTech Connect

    Mugedo, J.Z.A.

    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.

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

    NASA Astrophysics Data System (ADS)

    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

    2014-07-01

    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.

  13. 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.

  14. Emissions of ammonia, methane, carbon dioxide, and nitrous oxide from dairy cattle housing and manure management systems.

    PubMed

    Leytem, April B; Dungan, Robert S; Bjorneberg, David L; Koehn, Anita C

    2011-01-01

    Concentrated animal feeding operations emit trace gases such as ammonia (NH?), methane (CH?), carbon dioxide (CO?), and nitrous oxide (N?O). The implementation of air quality regulations in livestock-producing states increases the need for accurate on-farm determination of emission rates. The objective of this study was to determine the emission rates of NH?, CH?, CO?, and N?O from three source areas (open lots, wastewater pond, compost) on a commercial dairy located in southern Idaho. Gas concentrations and wind statistics were measured each month and used with an inverse dispersion model to calculate emission rates. Average emissions per cow per day from the open lots were 0.13 kg NH?, 0.49 kg CH?, 28.1 kg CO?, and 0.01 kg N?O. Average emissions from the wastewater pond (g m(-2) d(-1)) were 2.0 g NH?, 103 g CH?, 637 g CO?, and 0.49 g N?O. Average emissions from the compost facility (g m(-2) d(-1)) were 1.6 g NH?, 13.5 g CH?, 516 g CO?, and 0.90 g N?O. The combined emissions of NH?, CH?, CO?, and N?O from the lots, wastewater pond and compost averaged 0.15, 1.4, 30.0, and 0.02 kg cow(-1) d(-1), respectively. The open lot areas generated the greatest emissions of NH?, CO?, and N?O, contributing 78, 80, and 57%, respectively, to total farm emissions. Methane emissions were greatest from the lots in the spring (74% of total), after which the wastewater pond became the largest source of emissions (55% of total) for the remainder of the year. Data from this study can be used to develop trace gas emissions factors from open-lot dairies in southern Idaho and potentially other open-lot production systems in similar climatic regions. PMID:21869500

  15. 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 ...

  16. 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.

  17. Seasonal dynamics in methane emissions from the Amazon River floodplain to the troposphere

    SciTech Connect

    Devol, A.H.; Richey, J.E. ); Forsberg, B.R. ); Martinelli, L.A. )

    1990-09-20

    Methane fluxes to the troposphere from the three principal habitats of the floodplain of the Amazon River main stem (open waters, emergent macrophyte beds, and flooded forests) were determined along a 1,700-km reach of the river during the low-water period of the annual flood cycle (November-December 1988). Overall, emissions averaged 68 ({plus minus} 20) mg CH{sub 4} m{sup {minus}2} d{sup {minus}1} and were significantly lower than similar emissions determined previously for the high-water period, 184 ({plus minus} 41) mg CH{sub 4} m{sup {minus}2} d{sup {minus}1} (July-August 1986). This difference was due to significantly lower emissions from floating macrophyte environments. Low-water emissions from open waters and flooded forest areas were not significantly different than at high water. A monthly time series of methane emissions from eight lakes located in the central Amazon basin showed similar results. Average annual emission from the lakes was 125 ({plus minus} 28) mg CH{sub 4} m{sup {minus}2} d{sup {minus}1}. Methane emissions from lakes were significantly higher during the high water period, again primarily due to an increase in emissions from macrophyte habitats. The data were used to calculate a seasonally weighted annual emission to the troposphere from the Amazon River main stem floodplain of 5.1 Tg yr{sup {minus}1}, which indicates the importance of the area in global atmospheric chemistry.

  18. 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.

  19. Seasonal variations in methane emission from Amazon River and tributaries

    NASA Astrophysics Data System (ADS)

    Sawakuchi, H. O.; Krusche, A. V.; Ballester, M. V.; Sawakuchi, A. O.; Richey, J. E.

    2012-12-01

    Inland waters are known as important sources of methane to atmosphere. Methane is produced in anaerobic environments usually found in lake and floodplain bottom sediments, which is the main reason why most of the information regarding methane fluxes come from this environments. However, while floodplains dry during low water season, reducing methanogenesis, rivers keep the capacity to emit methane throughout the year. Here we present results of CH4 flux measurements from 4 large tropical rivers within the Amazon basin obtained with floating chambers in 10 sampling sites during low water (between September and November of 2011) and high water seasons (May, 2012). Sampling sites were located in three main tributaries of Amazon Rivers, Madeira, Xingu and Tapajós, and in the Amazon River mainstem. In the Madeira River high water fluxes ranged from 2.85 to 30.99 mmol m-2 yr-1 while during low water from 77.47 to 183.31 mmol m-2 yr-1. Fluxes for the Amazon and Tapajós were, respectively, 110.99 and 80.01 mmol m-2 yr-1 for the high water season and 169.71 and 193.18 mmol m-2 yr-1 for low water. In the Xingu River two sites had higher fluxes during low water, 314.90 and 571.49 mmol m-2 yr-1 (91.93 and 51.11 mmol m-2 yr-1 in the high water respectively). The two other sites had an opposite pattern with 296.56 and 60.80 mmol m-2 yr-1 in the low water and 846.95 and 360.93 mmol m-2 yr-1 during high water; one site showed equal fluxes for both seasons. Most of the fluxes were higher during low water, with the exception of the three sites at the Xingu River, where fluxes during high water were higher or equal than in low water. These results show a different pattern than described before for these riverine systems, in which higher methane fluxes during high water were expected due to inputs from surrounding anoxic floodplain environments. Instead, our data shows that methane in rivers can be produced within river channels. Lower fluxes during high water could be related to deeper water columns exerting higher pressures and also to increased methane oxidation in the water column.

  20. Atmospheric constraints on the methane emissions from the East Siberian Shelf

    NASA Astrophysics Data System (ADS)

    Berchet, A.; Bousquet, P.; Pison, I.; Locatelli, R.; Chevallier, F.; Paris, J.-D.; Dlugokencky, E. J.; Laurila, T.; Hatakka, J.; Viisanen, Y.; Worthy, D. E. J.; Nisbet, E. G.; Fisher, R. E.; France, J. L.; Lowry, D.; Ivakhov, V.

    2015-09-01

    Sub-sea permafrost and hydrates in the East Siberian Arctic Ocean Continental Shelf (ESAS) constitute a substantial carbon pool, and a potentially large source of methane to the atmosphere. Previous studies based on interpolated oceanographic campaigns estimated atmospheric emissions from this area at 8-17 Tg CH4 y-1. Here, we propose insights based on atmospheric observations to evaluate these estimates. Isotopic observations suggest a biogenic origin (either terrestrial or marine) of the methane in air masses originating from ESAS during summer 2010. The comparison of high-resolution simulations of atmospheric methane mole fractions to continuous methane observations during the entire year 2012 confirms the high variability and heterogeneity of the methane releases from ESAS. Simulated mole fractions including a 8 Tg CH4 y-1 source from ESAS are found largely overestimated compared to the observations in winter, whereas summer signals are more consistent with each other. Based on a comprehensive statistical analysis of the observations and of the simulations, annual methane emissions from ESAS are estimated in a range of 0.5-4.3 Tg CH4 y-1.

  1. Assessing the Complementary Constraints on North American Methane Emissions Estimates Provided by Ground-based and Space-based Observations of Methane

    NASA Astrophysics Data System (ADS)

    Stanevich, I.; Jones, D. B. A.; Strong, K.; Lu, W.; Lin, J. C.; Andrews, A. E.; Worthy, D. E. J.; Wecht, K.; Wennberg, P. O.; Wunch, D.; Roehl, C. M.; Dubey, M. K.

    2014-12-01

    Methane (CH4) is the second most important anthropogenic greenhouse gas. Its global emissions are known to within 15%. However, emissions originating on the regional scale are poorly constrained. Here we present a study focused on assessing the complementarity of the constraints on estimates of North American CH4 emissions provided space-based and ground-based observations of atmospheric CH4. We use data from the Greenhouse gases Observing SATellite (GOSAT) together with discrete air sample measurements from tall towers and ground-based Fourier-Transform InfraRed (FTIR) spectrometers over North America to constrain surface fluxes of CH4. FTIR measurements are made by the Total Carbon Column Observing Network (TCCON) and by the Network for Detection of Atmospheric Composition Change (NDACC), which includes an instrument installed at the University of Toronto Atmospheric Observatory in downtown Toronto. We also employ two inverse modeling approaches. One of them exploits the Stochastic Time-Inverted Lagrangian Transport (STILT) model to link CH4 fluxes with measurements. Updates on emissions are obtained based on simple Bayesian inversion. In the second approach, CH4 emissions are constrained by means of a four-dimensional variational (4D-Var) data assimilation method implemented with the GEOS-Chem global chemical transport model. Comparing the two approaches, we investigate the effect of transport errors and the inversion framework on the inferred CH4 fluxes.

  2. NATURAL EMISSIONS OF NON-METHANE VOLATILE ORGANIC COMPOUNDS, CARBON MONOXIDE, AND OXIDES OF NITROGEN FROM NORTH AMERICA

    EPA Science Inventory

    The magnitudes, distributions, controlling processes and uncertainties associated with North American natural emissions of oxidant precursors are reviewed. Natural emissions are repsonsible for a major portion of the compounds, including non-methane volatile organic compounds (N...

  3. Methane Emissions from Natural Gas Vehicles in Beijing, Baoding, and Shijiazhuang, China during CAREBEIJING Field Campaign

    NASA Astrophysics Data System (ADS)

    Pan, D.; Tao, L.; Sun, K.; Golston, L.; Zhang, Y.; Zhu, T.; Zondlo, M. A.

    2014-12-01

    From 2002-2012, number of Natural Gas Vehicles (NGVs) increased from 36,000 to 1.6 million (44 times) and is projected to reach 4.0 million by 2020. Deploying NGVs is an effective way to relieve Chinese air pollution, since NGVs can reduce emissions of particulate matter (PM) and NOx by 91% and 59% compared to gasoline vehicles (GVs). However, previous studies in US showed that NGVs might emit more methane (CH4) than GVs, which is an important greenhouse gas and a precursor to air pollution. Despite the tremendous growth of NGVs and importance of CH4, CH4 emissions from NGVs in China haven't been carefully studied yet. During CAREBEIJING field campaign in 2013 and 2014, we used a mobile platform to conduct on-road measurement of CH4, carbon monoxide (CO), carbon dioxide (CO2), and NH3 (ammonia) in Beijing, Baoding, and Shijiazhuang, China. We found that the mean on-road CH4:CO2 ratio from NGVs is (0.004±0.0003) g CH4/g CO2, which is 20 times higher than previous report on CH4:CO2 emission ratio from US cars. Although NGVs can reduce 25% CO2 compared to GVs, CH4 emitted from NGVs would diminish this number to 19%. Using this emission ratio, we estimate that NGVs in China emitted 37 Gg CH4 in 2010. CH4 emissions from NGVs would increase to 207 Gg in 2020 (by a factor of 560%) if no regulation of CH4 emissions from NGVs were implemented. Most of these emissions occur in urban areas, requiring analyses of their impacts on air quality in such regions. Therefore, a mass balance model is used to study the proportion of CH4 emissions from NGVs in total urban CH4 emissions for Baoding city. Finally, in order to better inform policy decisions, a life-cycle analysis is made to estimate potential CH4 emissions from NGV related industrials. Overall, NGVs are promising alternative fuel vehicles in China, but more attention should be paid to quantify their CH4 emissions.

  4. 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...

  5. 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...

  6. Methane emissions from process equipment at natural gas production sites in the United States: liquid unloadings.

    PubMed

    Allen, David T; Sullivan, David W; Zavala-Araiza, Daniel; Pacsi, Adam P; Harrison, Matthew; Keen, Kindal; Fraser, Matthew P; Daniel Hill, A; Lamb, Brian K; Sawyer, Robert F; Seinfeld, John H

    2015-01-01

    Methane emissions from liquid unloadings were measured at 107 wells in natural gas production regions throughout the United States. Liquid unloadings clear wells of accumulated liquids to increase production, employing a variety of liquid lifting mechanisms. In this work, wells with and without plunger lifts were sampled. Most wells without plunger lifts unload less than 10 times per year with emissions averaging 21,000-35,000 scf methane (0.4-0.7 Mg) per event (95% confidence limits of 10,000-50,000 scf/event). For wells with plunger lifts, emissions averaged 1000-10,000 scf methane (0.02-0.2 Mg) per event (95% confidence limits of 500-12,000 scf/event). Some wells with plunger lifts are automatically triggered and unload thousands of times per year and these wells account for the majority of the emissions from all wells with liquid unloadings. If the data collected in this work are assumed to be representative of national populations, the data suggest that the central estimate of emissions from unloadings (270 Gg/yr, 95% confidence range of 190-400 Gg) are within a few percent of the emissions estimated in the EPA 2012 Greenhouse Gas National Emission Inventory (released in 2014), with emissions dominated by wells with high frequencies of unloadings. PMID:25488307

  7. Methane Emissions from the Natural Gas Transmission and Storage System in the United States.

    PubMed

    Zimmerle, Daniel J; Williams, Laurie L; Vaughn, Timothy L; Quinn, Casey; Subramanian, R; Duggan, Gerald P; Willson, Bryan; Opsomer, Jean D; Marchese, Anthony J; Martinez, David M; Robinson, Allen L

    2015-08-01

    The recent growth in production and utilization of natural gas offers potential climate benefits, but those benefits depend on lifecycle emissions of methane, the primary component of natural gas and a potent greenhouse gas. This study estimates methane emissions from the transmission and storage (T&S) sector of the United States natural gas industry using new data collected during 2012, including 2,292 onsite measurements, additional emissions data from 677 facilities and activity data from 922 facilities. The largest emission sources were fugitive emissions from certain compressor-related equipment and "super-emitter" facilities. We estimate total methane emissions from the T&S sector at 1,503 [1,220 to 1,950] Gg/yr (95% confidence interval) compared to the 2012 Environmental Protection Agency's Greenhouse Gas Inventory (GHGI) estimate of 2,071 [1,680 to 2,690] Gg/yr. While the overlap in confidence intervals indicates that the difference is not statistically significant, this is the result of several significant, but offsetting, factors. Factors which reduce the study estimate include a lower estimated facility count, a shift away from engines toward lower-emitting turbine and electric compressor drivers, and reductions in the usage of gas-driven pneumatic devices. Factors that increase the study estimate relative to the GHGI include updated emission rates in certain emission categories and explicit treatment of skewed emissions at both component and facility levels. For T&S stations that are required to report to the EPA's Greenhouse Gas Reporting Program (GHGRP), this study estimates total emissions to be 260% [215% to 330%] of the reportable emissions for these stations, primarily due to the inclusion of emission sources that are not reported under the GHGRP rules, updated emission factors, and super-emitter emissions. PMID:26195284

  8. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    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.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. Methane and carbon monoxide emissions from asphalt pavement: Measurements and estimates of their important to global budgets

    SciTech Connect

    Tyler, S.C.; Dlugokencky, E.; Zimmerman, P.R.; Cicerone, R.J. ); Lowe, D.C. )

    1990-08-20

    The authors measured emissions of methane from asphalt surfaces used in pavement for roadways. Maximum emissions were 22 mg/m{sup 2}/hr for 1- to 4-week-old pavement during maximum sunlight intensity. Emissions were much smaller at low sunlight intensity and dropped off to negligible amounts at night. Smaller emissions were observed for asphalt pavement of 2.5 to 3 years approximate age under similar conditions. Comparison measurements of carbon monoxide emissions resulted in maximum emissions of about 2.6 mg/m{sup 2}hr for 1-week-old pavement. These findings indicate that emissions of CH{sub 4} and CO are a function of both sunlight and temperature. Based on these results, methane emissions from asphalt pavement cannot be a significant source of atmospheric methane as compared to other identified methane sources. Therefore, although asphalt methane emissions are a form of fossil fuel methane, they cannot explain the relatively high fraction of {sup 14}C-depleted methane in the atmosphere.

  16. Direct measurements show decreasing methane emissions from natural gas local distribution systems in the United States.

    PubMed

    Lamb, Brian K; Edburg, Steven L; Ferrara, Thomas W; Howard, Touché; Harrison, Matthew R; Kolb, Charles E; Townsend-Small, Amy; Dyck, Wesley; Possolo, Antonio; Whetstone, James R

    2015-04-21

    Fugitive losses from natural gas distribution systems are a significant source of anthropogenic methane. Here, we report on a national sampling program to measure methane emissions from 13 urban distribution systems across the U.S. Emission factors were derived from direct measurements at 230 underground pipeline leaks and 229 metering and regulating facilities using stratified random sampling. When these new emission factors are combined with estimates for customer meters, maintenance, and upsets, and current pipeline miles and numbers of facilities, the total estimate is 393 Gg/yr with a 95% upper confidence limit of 854 Gg/yr (0.10% to 0.22% of the methane delivered nationwide). This fraction includes emissions from city gates to the customer meter, but does not include other urban sources or those downstream of customer meters. The upper confidence limit accounts for the skewed distribution of measurements, where a few large emitters accounted for most of the emissions. This emission estimate is 36% to 70% less than the 2011 EPA inventory, (based largely on 1990s emission data), and reflects significant upgrades at metering and regulating stations, improvements in leak detection and maintenance activities, as well as potential effects from differences in methodologies between the two studies. PMID:25826444

  17. 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...

  18. 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...

  19. Tillage and Fertilizer Effects on Soil Methane and Nitrous Oxide Emissions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural soil is a source of greenhouse gases such as methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2). An experiment was conducted to determine effects of tillage system, fertilizer type, and fertilizer application method on emissions of these three gases. Corn was grown on a silt...

  20. 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...

  1. 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

  2. Mapping of North American methane emissions with high spatial resolution by inversion

    E-print Network

    v4.2 and Environmental Protection Agency (EPA) inventories, respectively. We find that U (U.S.) Environmental Protection Agency (EPA) provides national emission inventories for methane [United States Environmental Protection Agency (EPA), 2013]. However, a number of studies using

  3. 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...

  4. Developing a New Field-Validated Methodology for Landfill Methane Emissions in California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This project was initiated in the US by the California Energy Commission (CEC) in cooperation with the California Integrated Waste Management Board (CIWMB) to develop improved methods for landfill methane emissions for the California greenhouse gas inventory. This 3-year project (2007-2010) is devel...

  5. Methane emissions from Southern High Plains dairy wastewater lagoons in the summer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methane is a greenhouse gas with a global warming potential 25 fold that of CO2, and animal agriculture is recognized as a source of CH4to the atmosphere. Dairy farms on the Southern High Plains of New Mexico and Texas (USA) are typically open lot, and sources of CH4 are enteric emissions from cattl...

  6. Earth'sFuture Remote sensing of fugitive methane emissions from oil and

    E-print Network

    Dickerson, Russell R.

    decade, there has been a massive growth in the horizontal drilling and hydraulic fracturing of shale gasEarth'sFuture Remote sensing of fugitive methane emissions from oil and gas production in North , Michael Buchwitz1 , Maximilian Reuter1 , and Heinrich Bovensmann1 1Institute of Environmental Physics (IUP

  7. 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...

  8. 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...

  9. Voyager 1 imaging and IRIS observations of Jovian methane absorption and thermal emission: Implications for cloud structure

    NASA Technical Reports Server (NTRS)

    West, R. A.; Kupferman, P. N.; Hart, H.

    1984-01-01

    Images from three filters of the Voyager 1 wide angle camera are used to measure the continuum reflectivity and spectral gradient near 6000 A and the 6190 A band methane/continuum ratio for a variety of cloud features in Jupiter's atmosphere. The dark barge features in the North Equatorial Belt have anomalously strong positive continuum spectral gradients suggesting unique composition. Methane absorption is shown at unprecedented spatial scales for the Great Red Spot and its immediate environment, for a dark barge feature in the North Equatorial Belt, and for two hot spot and plume regions in the North Equatorial Belt. Methane absorption and five micrometer emission are correlated in the vicinity of the Great Red Spot but are anticorrelated in one of the plume hot spot regions. Methane absorption and simultaneous maps of five micrometer brightness temperature is quantitatively compared to realistic cloud structure models which include multiple scattering at five micrometer as well as in the visible. Variability in H2 quadrupole lines are also investigated.

  10. 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.

  11. 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 ...

  12. Methane emissions from a gully mire in mid-Wales, U.K. under consecutive summer water table drawdown

    SciTech Connect

    Hughes, S.; Dowrick, D.J.; Freeman, C.; Reynolds, B.; Hudson, J.A.

    1999-01-15

    Wetlands are a major contributor to the global methane (CH{sub 4}) budget. Currently there is a consensus view that drought restrains CH{sub 4} emissions from wetlands. However, a 6-year field experiment investigating the effects of persistent summer water table drawdown on a gully mire in mid-Wales, U.K. demonstrated a 2-year boom and bust cycle of CH{sub 4} emissions followed by a recovery during the third year, when compared with emissions from a control wetland in which the water table remained at or above the peat surface. This cyclical trend was subsequently replicated by the control wetland following natural summer drought. The experimental wetland was affected less by this natural drought following previous water table drawdown. Depth profiles of CH{sub 4} production suggested that consecutive water table drawdown resulted in a translocation of peak methanogen activity lower down the peat profile, where emissions were affected less by subsequent drawdown. These findings suggest that wetland CH{sub 4} flux models need to consider the possibility that methane emission-water table relationships are dependent on the pattern and frequency of drought events.

  13. Detection of H alpha emission in a methane (T type) brown dwarf

    NASA Technical Reports Server (NTRS)

    Burgasser, A.; Kirkpatrick, J.; Reid, I.; Liebert, J.; Gizis, J.; Brown, M.

    2000-01-01

    We report the detection of H alpha emission in the T dwarf (methane brown dwarf) 2MASSW J1237392 + 652615 over three days using the Keek Low esolution Imaging Spectrograph. The measured line flux, log (L-H alpha/L-bol) = -4.3, is roughly consistent with early M dwarf activity levels and inconsistent with decreasing activity trends in late M and L dwarfs. Similar emission is not seen in two other T dwarfs.

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

    SciTech Connect

    Livingston, R.

    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.

  15. Methane emissions to the troposphere from the Amazon floodplain

    NASA Technical Reports Server (NTRS)

    Devol, Allen H.; Richey, Jeffrey E.; Clark, Wayne A.; King, Stagg L.; Martinelli, Luiz A.

    1988-01-01

    The magnitudes of CH4 emissions to the troposphere from the Amazon River floodplain and the mechanism of these emissions were investigated using the data of 94 individual flux measurements made along a 1700-km stretch of the river during July/August 1985. The overall average rate of CH4 emission from wetlands was found to be 390 mg CH4/sq m per day, with the highest emissions (590 mg CH4/sq m per day) attributed to the water surfaces covered by aquatic macrophytes. Ebullition was the dominant mechanism of emission, accounting for 85 percent of the total. Surface-water CH4 concentrations were highly supersaturated, averaging 6.4 micromolar. The annual emission of CH4 from the Amazon Basin to the troposphere, estimated from the area and the known emission rate, is about 10 CH4 Tg/yr, indicating the importance of the area in the global atmospheric CH4 cycle.

  16. Top-down methane emissions estimates for the San Francisco Bay Area from 1990 to 2012

    DOE PAGESBeta

    Fairley, David; Fischer, Marc L.

    2015-01-30

    Methane is a potent greenhouse gas (GHG) that is now included in both California State and San Francisco Bay Area (SFBA) bottom-up emission inventories as part of California's effort to reduce anthropogenic GHG emissions. Here we provide a top-down estimate of methane (CH4) emissions from the SFBA by combining atmospheric measurements with the comparatively better estimated emission inventory for carbon monoxide (CO). Local enhancements of CH4 and CO are estimated using measurements from 14 air quality sites in the SFBA combined together with global background measurements. Mean annual CH4 emissions are estimated from the product of Bay Area Air Qualitymore »Management District (BAAQMD) emission inventory CO and the slope of ambient local CH4 to CO. The resulting top-down estimates of CH4 emissions are found to decrease slightly from 1990 to 2012, with a mean value of 240 ± 60 GgCH4 yr?¹ (at 95% confidence) in the most recent (2009–2012) period, and correspond to reasonably a constant factor of 1.5–2.0 (at 95% confidence) times larger than the BAAQMD CH4 emission inventory. However, we note that uncertainty in these emission estimates is dominated by the variation in CH4:CO enhancement ratios across the observing sites and we expect the estimates could represent a lower-limit on CH4 emissions because BAAQMD monitoring sites focus on urban air quality and may be biased toward CO rather than CH4 sources.« less

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

    PubMed

    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

    2014-04-29

    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-km(2) 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

  18. 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

  19. METHANE: INDUSTRIAL SOURCES

    EPA Science Inventory

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

  20. 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.

  1. Modeling sulfate reduction in methane hydrate-bearing continental margin sediments: Does a sulfate-methane transition require anaerobic oxidation of methane?

    USGS Publications Warehouse

    Malinverno, A.; Pohlman, J.W.

    2011-01-01

    The sulfate-methane transition (SMT), a biogeochemical zone where sulfate and methane are metabolized, is commonly observed at shallow depths (1-30 mbsf) in methane-bearing marine sediments. Two processes consume sulfate at and above the SMT, anaerobic oxidation of methane (AOM) and organoclastic sulfate reduction (OSR). Differentiating the relative contribution of each process is critical to estimate methane flux into the SMT, which, in turn, is necessary to predict deeper occurrences of gas hydrates in continental margin sediments. To evaluate the relative importance of these two sulfate reduction pathways, we developed a diagenetic model to compute the pore water concentrations of sulfate, methane, and dissolved inorganic carbon (DIC). By separately tracking DIC containing 12C and 13C, the model also computes ??13C-DIC values. The model reproduces common observations from methane-rich sediments: a well-defined SMT with no methane above and no sulfate below and a ??13C-DIC minimum at the SMT. The model also highlights the role of upward diffusing 13C-enriched DIC in contributing to the carbon isotope mass balance of DIC. A combination of OSR and AOM, each consuming similar amounts of sulfate, matches observations from Site U1325 (Integrated Ocean Drilling Program Expedition 311, northern Cascadia margin). Without AOM, methane diffuses above the SMT, which contradicts existing field data. The modeling results are generalized with a dimensional analysis to the range of SMT depths and sedimentation rates typical of continental margins. The modeling shows that AOM must be active to establish an SMT wherein methane is quantitatively consumed and the ??13C-DIC minimum occurs. The presence of an SMT generally requires active AOM. Copyright 2011 by the American Geophysical Union.

  2. LANDFILL OPERATION FOR CARBON SEQUESTRATION AND MAXIMUM METHANE EMISSION CONTROL

    SciTech Connect

    Don Augenstein

    2001-02-01

    The work described in this report, to demonstrate and advance this technology, has used two demonstration-scale cells of size (8000 metric tons [tonnes]), sufficient to replicate many heat and compaction characteristics of larger ''full-scale'' landfills. An enhanced demonstration cell has received moisture supplementation to field capacity. This is the maximum moisture waste can hold while still limiting liquid drainage rate to minimal and safely manageable levels. The enhanced landfill module was compared to a parallel control landfill module receiving no moisture additions. Gas recovery has continued for a period of over 4 years. It is quite encouraging that the enhanced cell methane recovery has been close to 10-fold that experienced with conventional landfills. This is the highest methane recovery rate per unit waste, and thus progress toward stabilization, documented anywhere for such a large waste mass. This high recovery rate is attributed to moisture, and elevated temperature attained inexpensively during startup. Economic analyses performed under Phase I of this NETL contract indicate ''greenhouse cost effectiveness'' to be excellent. Other benefits include substantial waste volume loss (over 30%) which translates to extended landfill life. Other environmental benefits include rapidly improved quality and stabilization (lowered pollutant levels) in liquid leachate which drains from the waste.

  3. Assessment of methane emission and oxidation at Air Hitam Landfill site cover soil in wet tropical climate.

    PubMed

    Abushammala, Mohammed F M; Basri, Noor Ezlin Ahmad; Elfithri, Rahmah

    2013-12-01

    Methane (CH?) emissions and oxidation were measured at the Air Hitam sanitary landfill in Malaysia and were modeled using the Intergovernmental Panel on Climate Change waste model to estimate the CH? generation rate constant, k. The emissions were measured at several locations using a fabricated static flux chamber. A combination of gas concentrations in soil profiles and surface CH? and carbon dioxide (CO?) emissions at four monitoring locations were used to estimate the CH? oxidation capacity. The temporal variations in CH? and CO? emissions were also investigated in this study. Geospatial means using point kriging and inverse distance weight (IDW), as well as arithmetic and geometric means, were used to estimate total CH? emissions. The point kriging, IDW, and arithmetic means were almost identical and were two times higher than the geometric mean. The CH? emission geospatial means estimated using the kriging and IDW methods were 30.81 and 30.49 gm(?2) day(?1), respectively. The total CH? emissions from the studied area were 53.8 kg day(?1). The mean of the CH? oxidation capacity was 27.5 %. The estimated value of k is 0.138 year(?1). Special consideration must be given to the CH? oxidation in the wet tropical climate for enhancing CH? emission reduction. PMID:23797636

  4. An inhibitor persistently decreased enteric methane emission from dairy cows with no negative effect on milk production.

    PubMed

    Hristov, Alexander N; Oh, Joonpyo; Giallongo, Fabio; Frederick, Tyler W; Harper, Michael T; Weeks, Holley L; Branco, Antonio F; Moate, Peter J; Deighton, Matthew H; Williams, S Richard O; Kindermann, Maik; Duval, Stephane

    2015-08-25

    A quarter of all anthropogenic methane emissions in the United States are from enteric fermentation, primarily from ruminant livestock. This study was undertaken to test the effect of a methane inhibitor, 3-nitrooxypropanol (3NOP), on enteric methane emission in lactating Holstein cows. An experiment was conducted using 48 cows in a randomized block design with a 2-wk covariate period and a 12-wk data collection period. Feed intake, milk production, and fiber digestibility were not affected by the inhibitor. Milk protein and lactose yields were increased by 3NOP. Rumen methane emission was linearly decreased by 3NOP, averaging about 30% lower than the control. Methane emission per unit of feed dry matter intake or per unit of energy-corrected milk were also about 30% less for the 3NOP-treated cows. On average, the body weight gain of 3NOP-treated cows was 80% greater than control cows during the 12-wk experiment. The experiment demonstrated that the methane inhibitor 3NOP, applied at 40 to 80 mg/kg feed dry matter, decreased methane emissions from high-producing dairy cows by 30% and increased body weight gain without negatively affecting feed intake or milk production and composition. The inhibitory effect persisted over 12 wk of treatment, thus offering an effective methane mitigation practice for the livestock industries. PMID:26229078

  5. An inhibitor persistently decreased enteric methane emission from dairy cows with no negative effect on milk production

    PubMed Central

    Hristov, Alexander N.; Oh, Joonpyo; Giallongo, Fabio; Frederick, Tyler W.; Harper, Michael T.; Weeks, Holley L.; Branco, Antonio F.; Moate, Peter J.; Deighton, Matthew H.; Williams, S. Richard O.; Kindermann, Maik; Duval, Stephane

    2015-01-01

    A quarter of all anthropogenic methane emissions in the United States are from enteric fermentation, primarily from ruminant livestock. This study was undertaken to test the effect of a methane inhibitor, 3-nitrooxypropanol (3NOP), on enteric methane emission in lactating Holstein cows. An experiment was conducted using 48 cows in a randomized block design with a 2-wk covariate period and a 12-wk data collection period. Feed intake, milk production, and fiber digestibility were not affected by the inhibitor. Milk protein and lactose yields were increased by 3NOP. Rumen methane emission was linearly decreased by 3NOP, averaging about 30% lower than the control. Methane emission per unit of feed dry matter intake or per unit of energy-corrected milk were also about 30% less for the 3NOP-treated cows. On average, the body weight gain of 3NOP-treated cows was 80% greater than control cows during the 12-wk experiment. The experiment demonstrated that the methane inhibitor 3NOP, applied at 40 to 80 mg/kg feed dry matter, decreased methane emissions from high-producing dairy cows by 30% and increased body weight gain without negatively affecting feed intake or milk production and composition. The inhibitory effect persisted over 12 wk of treatment, thus offering an effective methane mitigation practice for the livestock industries. PMID:26229078

  6. Methane emissions from a beef cattle feedyard during winter and summer on the southern High Plains of Texas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methane (CH4) emissions from enteric fermentation by livestock account for about 2.1% of U.S. greenhouse gas emissions, with beef and dairy cattle the most significant sources. A better understanding of CH4 emissions from beef cattle feedyards can help build more accurate emission inventories, impro...

  7. Constraints on methane emissions in North America from future geostationary remote sensing measurements

    NASA Astrophysics Data System (ADS)

    Bousserez, N.; Henze, D. K.; Rooney, B.; Perkins, A.; Wecht, K. J.; Turner, A. J.; Natraj, V.; Worden, J. R.

    2015-07-01

    The success of future geostationary (GEO) satellite observation missions depends on our ability to design instruments that address their key scientific objectives. In this study, an Observation System Simulation Experiment (OSSE) is performed to quantify the constraints on methane (CH4) emissions in North America obtained from Short Wave Infrared (SWIR), Thermal Infrared (TIR) and multi-spectral measurements in geostationary orbit compared to existing SWIR low earth (LEO) measurements. A stochastic algorithm is used to compute the information content of a variational inversion at high spatial resolution (0.5° × 0.7°) using the GEOS-Chem chemical transport model and its adjoint. Both the SWIR LEO and TIR GEO configurations generally provide poor constraints on CH4 emissions (error reduction <30 %), with the exception of a few hotspots (e.g., Los Angeles, Toronto urban areas and Appalachian Mountains) where the error reduction is greater than 50 %. On weekly time scales and for a GEO orbit, the degree of freedom for signal (DOFs) of the inversion from multi-spectral observations (500) is a factor of two higher than that obtained from a SWIR instrument (255) due to the increase in measurement sensitivity to boundary layer concentrations in the multi-spectral case. On a monthly time scale and for a GEO orbit, a SWIR instrument would reduce error in emission estimates by more than 70 % for hotspots of CH4 sources (emissions > 4 × 105 kg day-1 grid-1) at model grid scale, while a TIR instrument would provide a relative error reduction of 25-60 % over those areas. While performing similarly for monthly inversions, a multi-spectral instrument would allow for more than 70 % error reduction for these emissions for 7 or 3 day inversions. Sensitivity of the inversions to error in boundary conditions are found to be negligible. Moreover, estimates of the model resolution matrix over significant emitting regions (CH4 emissions > 2 × 105 kg day-1 grid-1) show that for all instrument configurations in GEO orbit the inversion is able to independently constrain CH4 sources at spatial scales smaller than 200 km. These results highlight the importance of using observations sensitive to boundary layer concentrations (i.e., SWIR) to achieve significant improvements in constraining CH4 sources compared to current LEO capabilities.

  8. 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

  9. Cattle methane emission and pasture carbon dioxide balance of a grazed grassland.

    PubMed

    McGinn, S M; Beauchemin, K A; Coates, T; McGeough, E J

    2014-05-01

    Grasslands constitute a major land use globally and are a potential sink of atmospheric carbon dioxide (CO). They are also an important habitat for wildlife and a source of feed that supports ruminant livestock production. However, the presence of ruminants grazing these grasslands is also a source of methane (CH) that contributes to buildup of greenhouse gases in the atmosphere. Our study measured enteric CH from 40 confined heifers in 1-ha paddocks using a dispersion model and CO exchange from an adjacent grassland site using a micrometeorological technique. The study was conducted at a mixed prairie grassland located in southern Alberta, Canada. The mean (standard error) CH emission was 189 (± 6) g animal d over four campaigns (over a 3-yr period). The daily averaged CO exchange from the grassland peaked at +2.2 g m h (sink) in early July and declined to negative values (source) in mid-August. Annually, the grazed grassland was either a net sink for carbon (C) at +40 kg C ha or a small source at -7 kg C ha depending on a cattle stocking density of 0.1 or 0.2 animals ha, respectively. However, in basing the exchange on CO equivalence (CO), both stocking densities resulted in the grazed grassland being a source of greenhouse gas of -9 or -338 kg CO ha y. This study illustrates the need to consider the cattle CH emissions and the stocking density when evaluating the environmental sustainability of grazed grasslands. PMID:25602811

  10. 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

  11. Utilization of stabilized wastes for reducing methane emission from municipal solid waste disposal.

    PubMed

    Chiemchaisri, Wilai; Chiemchaisri, Chart; Boonchaiyuttasak, Jindaruch

    2013-08-01

    Stabilized solid wastes were utilized to mitigate methane emission from the landfill. Loose texture of plastic wastes encouraged air diffusion from the soil surface whereas fine organic fraction has good water holding capacity and nutrients to stimulate methane oxidation reaction. Biological methane oxidation capacity in stabilized waste layer was found to be up to 34.1 g/m(3)d. Microbial activity test revealed methanotrophic activities of plastic and degraded organic wastes were in the same order. The mixture of plastic and fine degraded organic waste matrix provided sufficient porosity for oxygen transfer and supported the growth of methanotrophs throughout 0.8m depth of waste layer. Fluorescent in situ hybridization (FISH) analysis confirmed the presence of methanotrophs and their population was found varied along waste depth. PMID:23562177

  12. Methane and carbon dioxide emissions from constructed wetlands receiving anaerobically pretreated sewage.

    PubMed

    de la Varga, D; Ruiz, I; Álvarez, J A; Soto, M

    2015-12-15

    The aim of this research was to determine methane and carbon dioxide emissions from a hybrid constructed wetland (CW) treating anaerobically pre-treated sewage. The CW was constituted of two horizontal flow (free water surface followed by a subsurface) units. A long-term study was carried out as both CW units were monitored for three campaigns in Period 1 (0.9-1.5years after start-up), and four campaigns in Period 2 (4.5-5.8years after start-up). The closed chamber method with collecting surfaces of 1810cm(2) was used. For this system, variability due to position in the transverse section of CW, plant presence or absence and recommended sampling period was determined. Overall methane emissions ranged from 96 to 966mgCH4m(-2) d(-1), depending on several factors as the operation time, the season of the year and the position in the system. Methane emissions increased from 267±188mgCH4m(-2)d(-1) during the second year of operation to 543±161mgCH4m(-2)d(-1) in the sixth year of operation. Methane emissions were related to the age of the CW and the season of the year, being high in spring and becoming lower from spring to winter. Total CO2 emissions ranged mostly from 3500 to 5800mgCO2m(-2)d(-1) during the sixth year of operation, while nitrous oxide emissions were below the detection limit of the method. PMID:26342902

  13. A new approach to estimate fugitive methane emissions from coal mining in China.

    PubMed

    Ju, Yiwen; Sun, Yue; Sa, Zhanyou; Pan, Jienan; Wang, Jilin; Hou, Quanlin; Li, Qingguang; Yan, Zhifeng; Liu, Jie

    2016-02-01

    Developing a more accurate greenhouse gas (GHG) emissions inventory draws too much attention. Because of its resource endowment and technical status, China has made coal-related GHG emissions a big part of its inventory. Lacking a stoichiometric carbon conversion coefficient and influenced by geological conditions and mining technologies, previous efforts to estimate fugitive methane emissions from coal mining in China has led to disagreeing results. This paper proposes a new calculation methodology to determine fugitive methane emissions from coal mining based on the domestic analysis of gas geology, gas emission features, and the merits and demerits of existing estimation methods. This new approach involves four main parameters: in-situ original gas content, gas remaining post-desorption, raw coal production, and mining influence coefficient. The case studies in Huaibei-Huainan Coalfield and Jincheng Coalfield show that the new method obtains the smallest error, +9.59% and 7.01% respectively compared with other methods, Tier 1 and Tier 2 (with two samples) in this study, which resulted in +140.34%, +138.90%, and -18.67%, in Huaibei-Huainan Coalfield, while +64.36%, +47.07%, and -14.91% in Jincheng Coalfield. Compared with the predominantly used methods, this new one possesses the characteristics of not only being a comparably more simple process and lower uncertainty than the "emission factor method" (IPCC recommended Tier 1 and Tier 2), but also having easier data accessibility, similar uncertainty, and additional post-mining emissions compared to the "absolute gas emission method" (IPCC recommended Tier 3). Therefore, methane emissions dissipated from most of the producing coal mines worldwide could be more accurately and more easily estimated. PMID:26605831

  14. Satellite Based Estimation of Global Biogenic Methane Emissions 

    E-print Network

    Bloom, A. Anthony

    2011-01-01

    Atmospheric CH4 is derived from both natural and anthropogenic sources, and the rapid increase in atmospheric CH4 levels over the past two centuries has predominantly been a result of increased anthropogenic emissions. ...

  15. 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...

  16. 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.

  17. 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.

  18. Application of a methane carbon isotope analyzer for the investigation of ?13C of methane emission measured by the automatic chamber method in an Arctic Tundra

    NASA Astrophysics Data System (ADS)

    Mastepanov, Mikhail; Christensen, Torben

    2014-05-01

    Methane emissions have been monitored by an automatic chamber method in Zackenberg valley, NE Greenland, since 2006 as a part of Greenland Ecosystem Monitoring (GEM) program. During most of the seasons the measurements were carried out from the time of snow melt (June-July) until freezing of the active layer (October-November). Several years of data, obtained by the same method, instrumentation and at exactly the same site, provided a unique opportunity for the analysis of interannual methane flux patterns and factors affecting their temporal variability. The start of the growing season emissions was found to be closely related to a date of snow melt at the site. Despite a large between year variability of this date (sometimes more than a month), methane emission started within a few days after, and was increasing for the next about 30 days. After this peak of emission, it slowly decreased and stayed more or less constant or slightly decreasing during the rest of the growing season (Mastepanov et al., Biogeosciences, 2013). During the soil freezing, a second peak of methane emission was found (Mastepanov et al., Nature, 2008); its amplitude varied a lot between the years, from almost undetectable to comparable with total growing season emissions. Analysis of the multiyear emission patterns (Mastepanov et al., Biogeosciences, 2013) led to hypotheses of different sources for the spring, summer and autumn methane emissions, and multiyear cycles of accumulation and release of these components to the atmosphere. For the further investigation of this it was decided to complement the monitoring system with a methane carbon isotope analyzer (Los Gatos Research, USA). The instrument was installed during 2013 field season and was successfully operating until the end of the measurement campaign (27 October). Detecting both 12C-CH4 and 13C-CH4 concentrations in real time (0.5 Hz) during automatic chamber closure (15 min), the instrument was providing data for determination of ?13C of the emitting methane (by a relation between 12C-CH4 and 13C-CH4 fluxes). Unfortunately, the beginning of the season was missed due to a delay in the instrument shipment; the summer fluxes were lower than any of the 7 previous years due to an exceptional drought; the autumn burst was not detected due to both exceptionally slow soil freezing and a low soil methane content. However, the data obtained from the most productive chambers confirm the feasibility of the chosen method and give good expectations for the following field campaign 2014.

  19. Tropospheric methane emissions from cattails along a latitudinal gradient

    SciTech Connect

    Yavitt, J.B.; Knapp, A.K. Kansas State Univ., Manhattan )

    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.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

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

  2. Train-borne Measurements of Enhanced Wet Season Methane Emissions in Northern Australia - Implications for Australian Tropical Wetland Emissions

    NASA Astrophysics Data System (ADS)

    Deutscher, N. M.; Griffith, D. W.; Paton-Walsh, C.

    2008-12-01

    We present the first transect measurements of CH4, CO2, CO and N2O taken on the Ghan railway travelling on a N-S transect of the Australian continent between Adelaide (34.9°S, 138.6°E) and Darwin (12.5°S, 130.9°E). The Ghan crosses Australia from the mainly agricultural mid-latitude south through the arid interior to the wet-dry tropical savannah south of and around Darwin. In the 2008 wet season (February) we observed a significant latitudinal gradient of CH4 increasing towards the north. The same pattern was observed in the late 2008 wet season (March-April), with a smaller latitudinal gradient. These will be compared with a dry season transect, to be undertaken in September/October 2008. The Air Pollution Model (TAPM), a regional scale prognostic meteorological model, is used to estimate the surface methane source strength required to explain the observed latitudinal gradient in CH4 in the wet season, and investigate the source type. Fluxes from cattle and termites together contribute up to 25% of the enhancements seen, leaving wetlands as the major source of wet season methane in the Australian tropics. Wetlands are the largest natural source of methane to the atmosphere, and tropical wetlands are responsible for the majority of the interannual variation in methane source strength. We attempt to quantify the annual methane flux contributed by anaerobic organic breakdown due to wet- season flooding in tropical Northern Territory.

  3. Seasonal trends and environmental controls of methane emissions in a rice paddy field in Northern Italy

    NASA Astrophysics Data System (ADS)

    Meijide, A.; Manca, G.; Goded, I.; Magliulo, V.; di Tommasi, P.; Seufert, G.; Cescatti, A.

    2011-12-01

    Rice paddy fields are one of the greatest anthropogenic sources of methane (CH4), the third most important greenhouse gas after water vapour and carbon dioxide. In agricultural fields, CH4 is usually measured with the closed chamber technique, resulting in discontinuous series of measurements performed over a limited area, that generally do not provide sufficient information on the short-term variation of the fluxes. On the contrary, aerodynamic techniques have been rarely applied for the measurement of CH4 fluxes in rice paddy fields. The eddy covariance (EC) technique provides integrated continuous measurements over a large area and may increase our understanding of the underlying processes and diurnal and seasonal pattern of CH4 emissions in this ecosystem. For this purpose a Fast Methane Analyzer (Los Gatos Research Ltd.) was installed in a rice paddy field in the Po Valley (Northern Italy). Methane fluxes were measured during the rice growing season with both EC and manually operated closed chambers. Methane fluxes were strongly influenced by the height of the water table, with emissions peaking when it was above 10-12 cm. Soil temperature and the developmental stage of rice plants were also responsible of the seasonal variation on the fluxes. The measured EC fluxes showed a diurnal cycle in the emissions, which was more relevant during the vegetative period, and with CH4 emissions being higher in the late evening, possibly associated with higher water temperature. The comparison between the two measurement techniques shows that greater fluxes are measured with the chambers, especially when higher fluxes are being produced, resulting in 30 % higher seasonal estimations with the chambers than with the EC (41.1 and 31.7 g CH4 m-2 measured with chambers and EC respectively) and even greater differences are found if shorter periods with high chamber sampling frequency are compared. The differences may be a result of the combined effect of overestimation with the chambers and of the possible underestimation by the EC technique.

  4. 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 Protection of Environment...—Default Methane Emission Factors for Liquefied Natural Gas (LNG) Storage LNG storage Emission factor (scf/hour/component) Leaker Emission Factors—LNG Storage Components, LNG Service Valve 1.19 Pump Seal...

  5. 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 Protection of Environment...—Default Methane Emission Factors for Liquefied Natural Gas (LNG) Storage LNG storage Emission factor (scf/hour/component) Leaker Emission Factors—LNG Storage Components, LNG Service Valve 1.19 Pump Seal...

  6. 40 CFR Table W - 6 of Subpart W of Part 98-Default Methane Emission Factors for LNG Import and Export Equipment

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Methane Emission Factors for LNG Import and Export Equipment W Table W Protection of Environment...—Default Methane Emission Factors for LNG Import and Export Equipment LNG import and export equipment Emission factor (scf/hour/component) Leaker Emission Factors—LNG Terminals Components, LNG Service Valve...

  7. 40 CFR Table W - 6 of Subpart W of Part 98-Default Methane Emission Factors for LNG Import and Export Equipment

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Methane Emission Factors for LNG Import and Export Equipment W Table W Protection of Environment...—Default Methane Emission Factors for LNG Import and Export Equipment LNG import and export equipment Emission factor (scf/hour/component) Leaker Emission Factors—LNG Terminals Components, LNG Service Valve...

  8. UNDERSTANDING METHANE EMISSIONS SOURCES AND VIABLE MITIGATION MEASURES IN THE NATURAL GAS TRANSMISSION SYSTEMS: RUSSIAN AND U.S. EXPERIENCE

    SciTech Connect

    Ishkov, A.; Akopova, Gretta; Evans, Meredydd; Yulkin, Grigory; Roshchanka, Volha; Waltzer, Suzie; Romanov, K.; Picard, David; Stepanenko, O.; Neretin, D.

    2011-10-01

    This article will compare the natural gas transmission systems in the U.S. and Russia and review experience with methane mitigation technologies in the two countries. Russia and the United States (U.S.) are the world's largest consumers and producers of natural gas, and consequently, have some of the largest natural gas infrastructure. This paper compares the natural gas transmission systems in Russia and the U.S., their methane emissions and experiences in implementing methane mitigation technologies. Given the scale of the two systems, many international oil and natural gas companies have expressed interest in better understanding the methane emission volumes and trends as well as the methane mitigation options. This paper compares the two transmission systems and documents experiences in Russia and the U.S. in implementing technologies and programs for methane mitigation. The systems are inherently different. For instance, while the U.S. natural gas transmission system is represented by many companies, which operate pipelines with various characteristics, in Russia predominately one company, Gazprom, operates the gas transmission system. However, companies in both countries found that reducing methane emissions can be feasible and profitable. Examples of technologies in use include replacing wet seals with dry seals, implementing Directed Inspection and Maintenance (DI&M) programs, performing pipeline pump-down, applying composite wrap for non-leaking pipeline defects and installing low-bleed pneumatics. The research methodology for this paper involved a review of information on methane emissions trends and mitigation measures, analytical and statistical data collection; accumulation and analysis of operational data on compressor seals and other emission sources; and analysis of technologies used in both countries to mitigate methane emissions in the transmission sector. Operators of natural gas transmission systems have many options to reduce natural gas losses. Depending on the value of gas, simple, low-cost measures, such as adjusting leaking equipment components, or larger-scale measures, such as installing dry seals on compressors, can be applied.

  9. The impact of air pollutant and methane emission controls on tropospheric ozone and radiative forcing: CTM calculations for the period 1990-2030

    NASA Astrophysics Data System (ADS)

    Dentener, F.; Stevenson, D.; Cofala, J.; Mechler, R.; Amann, M.; Bergamaschi, P.; Raes, F.; Derwent, R.

    2005-07-01

    To explore the relationship between tropospheric ozone and radiative forcing with changing emissions, we compiled two sets of global scenarios for the emissions of the ozone precursors methane (CH4), carbon monoxide (CO), non-methane volatile organic compounds (NMVOC) and nitrogen oxides (NOx) up to the year 2030 and implemented them in two global Chemistry Transport Models. The "Current Legislation" (CLE) scenario reflects the current perspectives of individual countries on future economic development and takes the anticipated effects of presently decided emission control legislation in the individual countries into account. In addition, we developed a "Maximum technically Feasible Reduction" (MFR) scenario that outlines the scope for emission reductions offered by full implementation of the presently available emission control technologies, while maintaining the projected levels of anthropogenic activities. Whereas the resulting projections of methane emissions lie within the range suggested by other greenhouse gas projections, the recent pollution control legislation of many Asian countries, requiring introduction of catalytic converters for vehicles, leads to significantly lower growth in emissions of the air pollutants NOx, NMVOC and CO than was suggested by the widely used and more pessimistic IPCC (Intergovernmental Panel on Climate Change) SRES (Special Report on Emission Scenarios) scenarios (Nakicenovic et al., 2000), which made Business-as-Usual assumptions regarding emission control technology. With the TM3 and STOCHEM models we performed several long-term integrations (1990-2030) to assess global, hemispheric and regional changes in CH4, CO, hydroxyl radicals, ozone and the radiative climate forcings resulting from these two emission scenarios. Both models reproduce broadly the observed trends in CO, and CH4 concentrations from 1990 to 2002.

    For the "current legislation" case, both models indicate an increase of the annual average ozone levels in the Northern Hemisphere by 5ppbv, and up to 15ppbv over the Indian sub-continent, comparing the 2020s (2020-2030) with the 1990s (1990-2000). The corresponding higher ozone and methane burdens in the atmosphere increase radiative forcing by approximately 0.2 Wm-2. Full application of today's emissions control technologies, however, would bring down ozone below the levels experienced in the 1990s and would reduce the radiative forcing of ozone and methane to approximately -0.1 Wm-2. This can be compared to the 0.14-0.47 Wm-2 increase of methane and ozone radiative forcings associated with the SRES scenarios. While methane reductions lead to lower ozone burdens and to less radiative forcing, further reductions of the air pollutants NOx and NMVOC result in lower ozone, but at the same time increase the lifetime of methane. Control of methane emissions appears an efficient option to reduce tropospheric ozone as well as radiative forcing.

  10. Seasonal dynamics in methane emissions from the Amazon River floodplain to the troposphere

    NASA Technical Reports Server (NTRS)

    Devol, Allan H.; Richey, Jeffrey E.; Forsberg, Bruce R.; Martinelli, Luiz A.

    1990-01-01

    Methane fluxes to the troposphere from the three principal habitats of the floodplain of the Amazon River main stem (open waters, emergent macrophyte beds, and flooded forests) were determined along a 1700-km reach of the river during the low-water period of the annual flood cycle (November-December 1988). Overall, emissions averaged 68 mg CH4/sq m per day and were significantly lower than similar emissions determined previously for the high-water period, 184 mg CH4/sq m per day (July-August 1986). This difference was due to significantly lower emissions from floating macrophyte environments. Low-water emissions from open waters and flooded forest areas were not significantly different than at high water. A monthly time series of methane emission from eight lakes located in the central Amazon basis showed similar results. The data were used to calculate a seasonally weighted annual emission to the troposphere from the Amazon River main stem floodplain of 5.1 Tg/yr, which indicates the importance of the area in global atmospheric chemistry.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    SciTech Connect

    Delmas, R.A.; Marenco, A. ); Tathy, J.P.; Cros, B. ); Baudet, J.G.R. )

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  14. 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.

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

    SciTech Connect

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

    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.

  16. Methane emissions from process equipment at natural gas production sites in the United States: pneumatic controllers.

    PubMed

    Allen, David T; Pacsi, Adam P; Sullivan, David W; Zavala-Araiza, Daniel; Harrison, Matthew; Keen, Kindal; Fraser, Matthew P; Daniel Hill, A; Sawyer, Robert F; Seinfeld, John H

    2015-01-01

    Emissions from 377 gas actuated (pneumatic) controllers were measured at natural gas production sites and a small number of oil production sites, throughout the United States. A small subset of the devices (19%), with whole gas emission rates in excess of 6 standard cubic feet per hour (scf/h), accounted for 95% of emissions. More than half of the controllers recorded emissions of 0.001 scf/h or less during 15 min of measurement. Pneumatic controllers in level control applications on separators and in compressor applications had higher emission rates than controllers in other types of applications. Regional differences in emissions were observed, with the lowest emissions measured in the Rocky Mountains and the highest emissions in the Gulf Coast. Average methane emissions per controller reported in this work are 17% higher than the average emissions per controller in the 2012 EPA greenhouse gas national emission inventory (2012 GHG NEI, released in 2014); the average of 2.7 controllers per well observed in this work is higher than the 1.0 controllers per well reported in the 2012 GHG NEI. PMID:25488196

  17. Methane emission associated with anatomical and morphophysiological characteristics of rice (Oryza sativa) plant.

    PubMed

    Das, Kaushik; Baruah, Kushal Kumar

    2008-10-01

    Plant-mediated transport is the primary route of methane (CH(4)) emission from the reduced paddy field to the aboveground atmosphere. Experiments were conducted at North Bank Plain Agro-climatic Zone of Assam, India, during monsoon rice-growing season (July to December 2006) to elucidate the influences of anatomical and morphophysiological characteristics of rice (Oryza sativa L.) cultivars on methane emission from submerged agroecosystem. Ten rice cultivars were grown in light-textured loamy soil under rainfed uniform field condition. Among the 10 cultivars, 5 were traditional rice genotypes commonly grown in the agroclimatic zone and the other 5 were improved high-yielding varieties. Wide variation in CH(4) flux was recorded among the rice cultivars, which may be regulated by the difference in anatomical and morphophysiological characteristics of rice plant. Microscopic analysis of stem portion showed that high- and medium-CH(4)-emitting cultivars recorded higher size of the medullary cavity. Leaf area and transpirational rates were also found to be higher in high-CH(4)-emitting varieties. Scanning electron microscopic analysis revealed higher stomatal frequencies in high-methane-emitting cultivars. Data presented in this study suggest that variation in anatomical and morphophysiological characteristics among different rice genotypes may influence CH(4) emission from paddy fields. PMID:18507814

  18. Methane flux from the Amazon River floodplain: Emissions during rising water

    SciTech Connect

    Bartlett, K.B.; Crill, P.M. ); Bonassi, J.A. ); Richey, J.E. ); Harriss, R.C. NASA Langley Research Center, Hampton, VA )

    1990-09-20

    During April and May of 1987, an extensive methane flux data set from Amazonian wetland habitats was collected during the wet season as river water levels were high and rising. This work extends measurements made in the dry season of 1985, when water levels were falling. A total of 284 flux measurements were made in the three primary floodplain environments of open-water lakes and channels, floating grass mats, and flooded forests, along approximately 1,500 km of the central floodplain. Emissions (means and standard errors) were 74 {plus minus} 14 mg CH{sub 4}/m{sup 2}/d (open water), 201 {plus minus} 35 mg CH{sub 4}/m{sup 2}/d (grass mats), and 126 {plus minus} 20 mg CH{sub 4}/m{sup 2}/d (flooded forests). These values were not significantly different from the majority of those from 1985, in part due to the high variability in flux seen at both times. Although ebullition was a significant component of methane emissions at both periods, the frequency of bubbling and its contribution to total flux was lower during the period of rising water than during falling water. A prominent diurnal pattern in atmospheric methane concentrations was observed, with minimum levels of about 1.75 ppm at midday and a maximum of 2.12 ppm at about midnight. Given the relatively small season changes observed in flux at the two stages of the rivers hydrographic curve, earlier estimates of regional methane flux remain largely unchanged. Revision of global estimates of wetland methane sources based on these tropical data and recently published figures for northern peatlands indicated that tropical wetlands may be more important than previously suggested, but that wetland sources overall remain at approximately 110 Tg/yr.

  19. Transcontinental methane measurements: Part 2. Mobile surface investigation of fossil fuel industrial fugitive emissions

    NASA Astrophysics Data System (ADS)

    Leifer, Ira; Culling, Daniel; Schneising, Oliver; Farrell, Paige; Buchwitz, Michael; Burrows, John P.

    2013-08-01

    The potent greenhouse gas, methane, CH4, has a wide variety of anthropogenic and natural sources. Fall, continental-scale (Florida to California) surface CH4 data were collected to investigate the importance of fossil fuel industrial (FFI) emissions in the South US. A total of 6600 measurements along 7020-km of roadways were made by flame ion detection gas chromatography onboard a nearly continuously moving recreational vehicle in 2010. A second, winter survey in Southern California measured CH4 at 2 Hz with a cavity ring-down spectrometer in 2012. Data revealed strong and persistent FFI CH4 sources associated with refining, oil/gas production, a presumed major pipeline leak, and a coal loading plant. Nocturnal CH4 mixing ratios tended to be higher than daytime values for similar sources, sometimes significantly, which was attributed to day/night meteorological differences, primarily changes in the boundary layer height. The highest CH4 mixing ratio (39 ppm) was observed near the Kern River Oil Field, California, which uses steam reinjection. FFI CH4 plume signatures were distinguished as stronger than other sources on local scales. On large (4°) scales, the CH4 trend was better matched spatially with FFI activity than wetland spatial patterns. Qualitative comparison of surface data with SCIAMACHY and GOSAT satellite retrievals showed agreement of the large-scale CH4 spatial patterns. Comparison with inventory models and seasonal winds suggests for some seasons and some portions of the Gulf of Mexico a non-negligible underestimation of FFI emissions. For other seasons and locations, qualitative interpretation is not feasible. Unambiguous quantitative source attribution is more complex, requiring transport modeling.

  20. Trace gas and particle emissions from open burning of three cereal crop residues: Increase in residue moistness enhances emissions of carbon monoxide, methane, and particulate organic carbon

    NASA Astrophysics Data System (ADS)

    Hayashi, Kentaro; Ono, Keisuke; Kajiura, Masako; Sudo, Shigeto; Yonemura, Seiichiro; Fushimi, Akihiro; Saitoh, Katsumi; Fujitani, Yuji; Tanabe, Kiyoshi

    2014-10-01

    We determined emission factors for open burning of straw of rice, wheat, and barley, as well as rice husks, and we incorporated the effects of moisture content on the emission factors for the straw. A closed system that simulated on-site backfiring of residues on the soil surface under moderate wind conditions was used to measure the gas and particle emissions from open burning of the residues on an upland field. Two moisture content conditions were evaluated: a dry condition (air-dried residues, 11-13% by weight) and a moist condition (20%). When a linear regression model with the initial moisture content of the residue as the explanatory variable showed good correlation between the primary emission data of a substance and the moisture content, the regression model was adopted as a function to give the emission factors. Otherwise, the unmodified primary data were used as the emission factors. The magnitudes of the gas and particle emissions differed among the residue types. For example, carbon monoxide (CO) emissions from straw of rice, wheat, and barley and rice husks burned under the dry condition were 27.2 ± 1.7, 41.8 ± 24.2, 46.9 ± 2.1, and 66.1 g kg-1 dry matter, and emissions of methane (CH4) were 0.75 ± 0.01, 2.01 ± 0.93, 1.47 ± 0.06, and 5.81 g kg-1 dry matter, respectively (n = 2 for straw with the standard deviation; n = 1 for husks). Emissions of carbon-containing gases and particles (e.g., CO, CH4, and particulate organic carbon) were higher under the moist condition than under the dry condition, which suggests that emission factors for open burning should incorporate the effects of moisture content except open burning performed in the dry season or arid zones.