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1

Methane emissions estimated from atmospheric observations of methane and its carbon isotopes: MOZART - 2 modeling study  

NASA Astrophysics Data System (ADS)

Methane is an important contributor to global warming with atmospheric concentrations nearly three times higher than the pre-industrial levels. Successful verifications of emission reductions from countries around the world depend on accurate modeling of atmospheric methane. Global model simulations of tropospheric methane, using the Model for Ozone and Related Chemical Tracers (MOZART-2), are presented. The magnitude of methane sources in the model is determined based on the a priori estimates of the source strengths, and the observed spatial distribution of atmospheric methane and its carbon isotopes. The results call for increased global emissions relative to the bottom-up source estimates. The significant increase in emissions in the Southern Hemisphere is required to match the observations. The proposed new set of methane emissions for MOZART-2 is consistent with the long-term global measurements of CH4 and 13C/12C.

Biberic, A.; Khalil, A.; Butenhoff, C.

2008-12-01

2

Validation of a methane emission model using eddy covariance observations and footprint modeling.  

NASA Astrophysics Data System (ADS)

Several methane emission models were developed recently to quantify methane emissions. However, calibration of these models is currently performed using chamber flux methane measurements, which have a number of limitations, such as small footprint area and low temporal resolution. Furthermore, chamber measurements are unsuitable to register ebullition events, which can have a significant influence on observed fluxes. Eddy covariance measurements on the other hand provide high frequency (5 to 20 Hz) data and cover larger areas, while being a non-intrusive way to measure fluxes and account for ebullition. In this study, we present a validation of methane emission model using eddy covariance data, collected in summer periods at the Indigirka lowland site in Eastern Siberia. A flux footprint model was used together with a high resolution vegetation map of the area to retrieve vegetation distribution inside the footprint. Subsequently, this data with eddy covariance data is used to calibrate a methane emission model.

Budishchev, A.; Mi, Y.; Gallagher, A.; van Huissteden, J.; Schaepman-Strub, G.; Dolman, A. J.; Maximov, T. C.

2012-04-01

3

Process-based model to derive methane emissions from natural wetlands.  

National Technical Information Service (NTIS)

A process-based model has been developed in order to calculate methane emissions from natural wetlands as a function of the hydrologic and thermal conditions in the soil. Processes considered in the model are methane production, methane consumption, and t...

B. P. Walter M. Heimann R. D. Shannon J. R. White

1996-01-01

4

Formation and emission of methane in rice soils: Experimental determination and modeling analysis. Final report  

SciTech Connect

Rice paddy soils have been identified as a major source of methane emissions contributing to the observed atmospheric increase in methane. This points to the need for a method of quantifying and predicting methane emissions for the widely varying conditions used in rice agriculture throughout the world. In the present work, a mathematical model for estimating the emission of methane from rice paddy soils is developed and refined. Kinetic parameters for methanogenesis in a Louisiana rice soil are determined from laboratory data on methane production from acetic acid substrate. Use of a stirred reactor allows simultaneous measurement of acetate consumption and methane production while minimizing mass transfer limitations. An existing model for rice plant growth is utilized to provide data on the availability of root exudates as a carbon source for the methanogens. The final methane model includes the kinetic parameters, plant data, and estimated transport parameters. With adjustments in these parameters, it provides an acceptable match to field data.

Law, V.J.; Bhattacharya, S.K.

1993-08-31

5

A process-based model to derive methane emissions from natural wetlands  

SciTech Connect

A process-based model has been developed in order to calculate methane emissions from natural wetlands as a function of the hydrologic and thermal conditions in the soil. The considered processes in the model are methane production, methane consumption and transport of methane by diffusion, ebullition and through plants. The model has been tested against data from a three-year field study from a Michigan peatland. The interannual and seasonal variations of the modelled methane emissions and methane concentration profiles are in good agreement with the observations. During the growing season the main emission pathway proceeds through plants. Ebullition occurs whenever the water table is above the soil surface, while diffusion is only significant in the first 15 days after a drop of the water table below the peat surface. {copyright} American Geophysical Union 1996

Walter, B.P.; Heimann, M. [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Shannon, R.D. [Department of Agricultural and Biological Engineering, Pennsylvania State University, University Park, Pennsylvania (United States); White, J.R. [Department of Geological Sciences, Indiana University, Bloomington, Indiana (United States)

1996-12-01

6

Evaluation of methane emissions from Taiwanese paddies  

Microsoft Academic Search

The main greenhouse gases are carbon dioxide, methane and nitrous oxide. Methane is the most important because the warming effect of methane is 21 times greater than that of carbon dioxide. Methane emitted from rice paddy fields is a major source of atmospheric methane. In this work, a methane emission model (MEM), which integrates climate change, plant growth and degradation

Chen-Wuing Liu; Chung-Yi Wu

2004-01-01

7

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

8

[A backward trajectory inversion model for methane emission over Beijing area].  

PubMed

A Backward trajectory inversion model was established for estimating methane emission over Beijing area, with in situ data of methane measurement. The model was systematically tested for its ability on reflecting diffusion processes in atmospheric boundary layers. In specific condition, the model acted excellently on calculating emission strength and distribution over an area of 100 km scale. By applying to Beijing area with 9 days real methane data and practice meteorological data, the model showed source patches in this area with emission rate 0.0066-0.026 mg/(m2.s), which was correspond well to rice fields emission, the major methane source, in this region. Model results of source patches also showed certain spatial correlation with rice fields distribution. PMID:12533920

Cai, Xuhui; Shao, Min; Su, Fang

2002-09-01

9

Modeling methane emission from rice paddies with various agricultural practices  

Microsoft Academic Search

Several models have been developed over the past decade to estimate CH4 emission from rice paddies. However, few models have been validated against field measurements with various parameters of soil, climate and agricultural practice. Thus reliability of the model's performance remains questionable particularly when extrapolating the model from site microscale to regional scale. In this paper, modification to the original

Yao Huang; Wen Zhang; Xunhua Zheng; Jin Li; Yongqiang Yu

2004-01-01

10

Modeling methane emissions from the Alaskan Yukon River basin, 1986-2005, by coupling a large-scale hydrological model and a process-based methane model  

NASA Astrophysics Data System (ADS)

Much progress has been made in methane modeling for the Arctic. However, there is still large uncertainty in emissions estimates due to the spatial variability in water table depth resulting from complex topographic gradients, and due to variations in methane production and oxidation due to complex freezing and thawing processes. Here we extended an extant methane emission module within a biogeochemistry model, the Terrestrial Ecosystem Model (TEM), to include a large-scale hydrology model, the variable infiltration capacity (VIC) model. The VIC model provides the required inputs, including freezing and thawing fronts, soil temperature and moisture, to the methane module. The effect of topography on the redistribution of soil moisture and water table depth was explicitly modeled using the TOPMODEL approach. The coupled modeling framework was applied to the Yukon River basin at a spatial resolution of 1 km from 1986 to 2005. The simulations show that the average annual net emissions of CH4 from the region are 4.01 Tg CH4 yr-1. El Niño phenomena usually lead to positive emission anomalies, while decreases in net CH4 emissions may be associated with strong La Niña events. Precipitation was found to be more closely related to CH4 dynamics than to soil temperature and active layer depth during the study period. This study suggests that the effects of soil freezing and thawing processes and the effects of microtopography on hydrology should be considered in the quantification of CH4 emissions.

Lu, Xiaoliang; Zhuang, Qianlai

2012-06-01

11

Analysis of predicted changes in methane emissions from wetlands using an integrated climate change effects model  

NASA Astrophysics Data System (ADS)

Methane is the second largest contributer to the present day greenhouse effect (IPCC, 2001), with wetlands being the single largest source. However there is considerable uncertainty in the magnitude of these biogenic emissions. Present day estimates vary from 115 (Fung et al., 1991) to 237 Tg CH4 yr-1 (Hein et al., 1997). Moreover it is anticipated that this source is likely to increase considerably under anthropogenic climate change through enhanced anaerobic decomposition of soil organic matter. A simple wetland model is developed for use in the UK Met Office climate model HadCM3 within the land surface scheme MOSES II. This scheme predicts both the extent of wetland area and the CH4 emissions from these inundated regions. The wetland model parameters are constrained by optimising the scheme's ability to predict the inter-annual variability in atmospheric methane concentration between 1984-1999. An integrated climate change effects model "IMOGEN" is used to simulate the potential feedbacks between biogenic methane emissions and climate. IMOGEN takes geographical patterns of surface climate anomalies from a HadCM3 transient climate change simulation and scales their magnitude according to greenhouse gas concentrations. These fields are used to drive the land surface model. Any predicted changes in natural methane emission can thereby feedback onto the climate. A number of IMOGEN runs are carried out from present day to 2100. The wetlands model is modified in each run such that the bounds of uncertainty in present day biogenic methane emissions are covered. The relative importance of changes in temperature and precipitation on the predicted geographical patterns of methane emissions are analysed. The significance of the total wetland emission feedback relative to likely anthropogenic climate change by 2100 is assessed.

Gedney, N.; Cox, P.

2003-04-01

12

Quantifying wetland methane emissions with process-based models of different complexities  

NASA Astrophysics Data System (ADS)

Bubbling is an important pathway of methane emissions from wetland ecosystems. However the concentration-based threshold function approach in current biogeochemistry models of methane is not sufficient to represent the complex ebullition process. Here we revise an extant process-based biogeochemistry model, the Terrestrial Ecosystem Model into a multi-substance model (CH4, O2, CO2 and N2) to simulate methane production, oxidation, and transport (particularly ebullition) with different model complexities. When ebullition is modeled with a concentration-based threshold function and if the inhibition effect of oxygen on methane production and the competition for oxygen between methanotrophy and heterotrophic respiration are retained, the model becomes a two-substance system. Ignoring the role of oxygen, while still modeling ebullition with a concentration-based threshold function, reduces the model to a one-substance system. These models were tested through a group of sensitivity analyses using data from two temperate peatland sites in Michigan. We demonstrate that only the four-substance model with a pressure-based ebullition algorithm is able to capture the episodic emissions induced by a sudden decrease in atmospheric pressure or by a sudden drop in water table. All models captured the retardation effect on methane efflux from an increase in surface standing water which results from the inhibition of diffusion and the increase in rhizospheric oxidation. We conclude that to more accurately account for the effects of atmospheric pressure dynamics and standing water on methane effluxes, the multi-substance model with a pressure-based ebullition algorithm should be used in the future to quantify global wetland CH4 emissions. Further, to more accurately simulate the pore water gas concentrations and different pathways of methane transport, an exponential root distribution function should be used and the phase-related parameters should be treated as temperature dependent.

Tang, J.; Zhuang, Q.; Shannon, R. D.; White, J. R.

2010-11-01

13

Quantifying wetland methane emissions with process-based models of different complexities  

NASA Astrophysics Data System (ADS)

Bubbling is an important pathway of methane emissions from wetland ecosystems; however the concentration-based threshold function approach in current biogeochemistry models of methane is not sufficient to represent the complex ebullition process. Here we revise an extant process-based biogeochemistry model, the Terrestrial Ecosystem Model into a multi-substance model (CH4, O2, CO2 and N2) to simulate methane production, oxidation, and transport (particularly ebullition) with different model complexities. When ebullition is modeled with a concentration-based threshold function and if the inhibition effect of oxygen on methane production and the competition for oxygen between methanotrophy and heterotrophic respiration are retained, the model is a two-substance system. Ignoring the role of oxygen, while still modeling ebullition with a concentration-based threshold function, reduces the model to a one-substance system. These models were tested through a group of sensitivity analyses at two temperate peatland sites in Michigan. We demonstrate that only the four-substance model with a pressure-based ebullition algorithm is able to capture the episodic emissions induced by a sudden decrease in atmospheric pressure. All models captured the retardation effect on methane efflux from an increase in surface standing water which results from the inhibition of diffusion and the increase in rhizospheric oxidation. We conclude that to more accurately account for the effects of atmospheric pressure dynamics and standing water on methane effluxes, the multi-substance model with a pressure-based ebullition algorithm should be used in the future to quantify global wetland CH4 emissions. Further, to more accurately simulate the pore water gas concentrations and different pathways of methane transport, an exponential root distribution function should be used and the phase-related parameters should be treated as temperature dependent.

Tang, J.; Zhuang, Q.; Shannon, R. D.; White, J. R.

2010-08-01

14

Model for estimating enteric methane emissions from United States dairy and feedlot cattle.  

PubMed

Methane production from enteric fermentation in cattle is one of the major sources of anthropogenic greenhouse gas emission in the United States and worldwide. National estimates of methane emissions rely on mathematical models such as the one recommended by the Intergovernmental Panel for Climate Change (IPCC). Models used for prediction of methane emissions from cattle range from empirical to mechanistic with varying input requirements. Two empirical and 2 mechanistic models (COWPOLL and MOLLY) were evaluated for their prediction ability using individual cattle measurements. Model selection was based on mean square prediction error (MSPE), concordance correlation coefficient, and residuals vs. predicted values analyses. In dairy cattle, COWPOLL had the lowest root MSPE and greatest accuracy and precision of predicting methane emissions (correlation coefficient estimate = 0.75). The model simulated differences in diet more accurately than the other models, and the residuals vs. predicted value analysis showed no mean bias (P = 0.71). In feedlot cattle, MOLLY had the lowest root MSPE with almost all errors from random sources (correlation coefficient estimate = 0.69). The IPCC model also had good agreement with observed values, and no significant mean (P = 0.74) or linear bias (P = 0.11) was detected when residuals were plotted against predicted values. A fixed methane conversion factor (Ym) might be an easier alternative to diet-dependent variable Ym. Based on the results, the 2 mechanistic models were used to simulate methane emissions from representative US diets and were compared with the IPCC model. The average Ym in dairy cows was 5.63% of GE (range 3.78 to 7.43%) compared with 6.5% +/- 1% recommended by IPCC. In feedlot cattle, the average Ym was 3.88% (range 3.36 to 4.56%) compared with 3% +/- 1% recommended by IPCC. Based on our simulations, using IPCC values can result in an overestimate of about 12.5% and underestimate of emissions by about 9.8% for dairy and feedlot cattle, respectively. In addition to providing improved estimates of emissions based on diets, mechanistic models can be used to assess mitigation options such as changing source of carbohydrate or addition of fat to decrease methane, which is not possible with empirical models. We recommend national inventories use diet-specific Ym values predicted by mechanistic models to estimate methane emissions from cattle. PMID:18539822

Kebreab, E; Johnson, K A; Archibeque, S L; Pape, D; Wirth, T

2008-06-06

15

Northern Eurasian Wetlands and the Carbon Cycle: Model Estimates of Carbon Storage and Methane Emissions  

NASA Astrophysics Data System (ADS)

The Eurasian Arctic drainage constitutes over ten percent of the global land area, and stores a substantial fraction of the terrestrial carbon pool in its soils and boreal forests. Specifically, boreal forests in this region constitute an estimated carbon sink of 0.5 Pg/y. However, assessments of carbon storage and fluxes in this region, and their role in climate change, vary considerably due to large uncertainties in the extent of wetlands, which both store carbon as peat and emit carbon as methane. Accurate estimates of wetland extent have been confounded by insufficient resolution of satellite imagery and poor coverage of in situ observations. In this study we refine these estimates of wetland extent, carbon storage, and methane emissions using a system of linked large-scale models of hydrology, terrestrial carbon dynamics, and methane emissions. Large-scale hydrology comes from the Variable Infiltration Capacity (VIC) hydrological model, which includes an updated lake/wetland parameterization that estimates the water table depth as a function of both lake level and wetland soil moisture. Fast ecosystem processes such as photosynthesis and respiration are simulated via the Biosphere Energy-Transfer Hydrology (BETHY) terrestrial carbon model. Methane emissions in areas of open water or saturated soil are simulated with the Walter-Heimann methane model. We validate this modeling system with respect to in situ observations of soil moisture and temperature, evaporation, and fluxes of CO2 and methane at flux towers at Fyodorovskoje, Hakasia, and Cherskii, Russia, over the period 1998- 2004. Sensitivity to calibration parameters such as the rooting depth and the proportionality between methane production rate and NPP are also explored.

Bohn, T. J.; Lettenmaier, D. P.; Sathulur, K.; Bowling, L. C.; McDonald, K. C.

2006-12-01

16

Modeling methane emissions from Alaskan Yukon River Basin from 1986 to 2005 by coupling a large-scale hydrological model and a process-based methane model  

NASA Astrophysics Data System (ADS)

Much progress has been made in methane modeling for the Arctic, there is still a large uncertainty in the emission estimate due to spatial variability of water table depth resulting from complex topographic gradient and variations in methane production and oxidation due to complex freezing and thawing processes. Here we extended an extant emission module within a biogeochemistry model, the Terrestrial Ecosystem Model (TEM) to including a large-scale hydrology model, the variable infiltration capacity (VIC) model. The VIC model provides required inputs including freezing and thawing fronts, soil temperature and moisture, to the methane simulation module. The effect of topography on the soil moisture redistribution is explicitly considered by using the TOPMODEL approach. The methane production, oxidation and transport are calculated in the soil profile at each 1 centimeter depth step and 1-hour time step. The coupled modeling framework is applied to the Yukon River Basin at a spatial resolution of 1km from 1986-2005. The simulations show that the average annual net emissions of CH4 from the region are 4.01 Tg CH4 yr-1. There is a large interannual variability in CH4 emissions during the study period and it is closely related to climate changes. El Nino phenomena usually lead to positive emission anomalies, while decreases in net CH4 emissions may be associated with strong La Niña events. The precipitation was found more closely related to the CH4 dynamics than soil temperature and active layer depth during the 1986-2005. The study highlights the importance of the effects of soil freezing and thawing process and the microtopography information in quantifying the dynamics of CH4 emissions from the complex landscape in the region.

Lu, X.; Zhuang, Q.

2011-12-01

17

Evaluating Contributions of Wetland and Lake Emissions of Methane to Atmospheric Methane Concentrations with models of Biogeochemistry and Atmospheric Chemistry Transport in Northern High Latitudes  

NASA Astrophysics Data System (ADS)

Northern high latitudes (north of 45oN) contain vast areas of wet tundra, wetlands, and water bodies (lakes and ponds), that are emitting a large amount of methane to the atmosphere each year. To date, the magnitudes and the inter-annual variations of these emissions are uncertain. The seasonal variations of these emissions due to changes of inundation of wetlands, the effects of spring thaw and winter freezing, and the effects of permafrost degradation in lands and lakes are also uncertain. In addition, how these emission dynamics affect the temporal and spatial distributions of atmospheric methane concentrations is not yet well understood. Here we use a process-based biogeochemistry model called TEM (the Terrestrial Ecosystem Model) to quantify these emissions with three different datasets for wetland and lake distributions. The effects of spring thaw and winter freezing on methane emissions are also incorporated into the TEM simulations. These estimated emissions together with wildfire emissions are then incorporated into a 3-D atmospheric chemistry transport model (GEOS-Chem) to simulate atmospheric methane concentration profiles. The satellite retrieval data of AIRS are then compared with the simulated methane concentration profiles for the region. We find that the current regional land and lake methane emissions range from 65 to 150 Tg per year. Seasonal changes of emissions of land and lakes due to spring thaw and winter freezing, together with fire emissions, play a significant role in determining the seasonal atmospheric methane concentration profiles simulated with GEOS-Chem. Comparison between multiple GEOS-Chem simulations driven with different seasonal dynamics of land, lake, and wildfire emissions and AIRS retrievals, suggests that accurately simulating the timing of these emissions as affected by spring thaw and winter freezing and wildfires, is critical for GEOS-Chem to capture the atmospheric concentration profiles over the region.

Zhuang, Q.; Tang, J.; Lu, Y.; Xiong, X.; Melillo, J. M.; Prinn, R. G.; McGuire, A. D.

2009-12-01

18

Modelling the impacts of abrupt AMOC changes on terrestrial methane emissions  

NASA Astrophysics Data System (ADS)

Greenland ice-core records indicate that the climate of the last glacial period was extremely unstable, with evidence for a series of rapid warming (Dansgaard-Oeschger, D-O) events. Ice-core records of atmospheric methane also show a number of abrupt rises which parallel D-O events, with amplitudes of up to half the glacial-interglacial difference, implying that D-O events were not confined to Greenland, but also had an effect on areas of natural wetlands. The methane record can therefore place additional constraints on D-O variability, which remains poorly understood. Although there is no generally accepted physical explanation of D-O events, a rapid change in the Atlantic meridional overturning circulation and associated heat transport to the Northern Hemisphere is generally favoured. We present results from a modelling approach, in which a coupled ocean-atmosphere GCM FAMOUS (a low resolution version of HadCM3) and models of global vegetation and wetlands are used in order to quantitatively assess this mechanism. Each GCM simulation uses a last glacial maximum background state with 21k orbital parameters, trace gas concentrations and ICE-5G ice sheet distribution, whilst an idealised, transient freshwater forcing is used to perturb the modelled meridional overturning circulation. The resulting climate series are used to drive the dynamic vegetation and methane emission models in a transient setup. The results show a consistent, strong reduction in wetland methane emissions in response to freshwater hosing events, with smaller emissions increases during the warming phase. Further experiments with differing background climatic states show methane emission sensitivity only during the hosing (cool) stage, and in most cases the overall magnitude of change appears too small when compared to the ice-core data. We will discuss possibilities for reconciliation of these results with these records and the resulting implications for understanding of D-O behaviour.

Hopcroft, P. O.; Valdes, P. J.; Beerling, D. J.

2010-12-01

19

The landfill methane balance: Model and practical applications  

SciTech Connect

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.

Bogner, J.; Spokas, K.

1995-10-01

20

Response of methane emission from arctic tundra to climatic change: results from a model simulation  

Microsoft Academic Search

Methane is an important greenhouse gas contributing approximately 15% to the present greenhouse warming. Tundra ecosystems between 50°N and 70°N are estimated to contain 14% of the global soil carbon and account for between 20 and 25% of the natural methane emissions. Consequently, enhanced anaerobic decomposition of tundra soil carbon and the associated increase in methane production could provide a

T. R. Christensen; P. Cox

1995-01-01

21

Dissolved methane in rising main sewer systems: field measurements and simple model development for estimating greenhouse gas emissions.  

PubMed

At present, the potential generation of methane in wastewater collection systems is ignored under international greenhouse gas (GHG) accounting protocols, despite recent reports of substantial dissolved methane formation in sewers. This suggests that the current national GHG inventories for wastewater handling systems are likely to be underestimated for some situations. This study presents a new catalogue of field data on methane formation in rising main sewerage systems and proposes an empirically-fitted, theoretical model to predict dissolved methane concentrations, based upon the independent variables of pipeline geometry (i.e. surface area to volume ratio, A/V) and hydraulic retention time (HRT). Systems with longer HRT and/or larger A/V ratios are shown to have higher dissolved methane concentrations. This simple predictive model provides a means for water authorities to estimate the methane emissions from other pressurised sewerage systems of similar characteristics. PMID:19934518

Foley, Jeff; Yuan, Zhiguo; Lant, Paul

2009-01-01

22

Global carbon exchange and methane emissions from natural wetlands: Application of a process-based model  

NASA Astrophysics Data System (ADS)

Wetlands are one of the most important sources of atmospheric methane (CH4), but the strength of this source is still highly uncertain. To improve estimates of CH4 emission at the regional and global scales and predict future variation requires a process-based model integrating the controls of climatic and edaphic factors and complex biological processes over CH4 flux rates. This study used a methane emission model based on the hypothesis that plant primary production and soil organic matter decomposition act to control the supply of substrate needed by methanogens; the rate of substrate supply and environmental factors, in turn, control the rate of CH4 production, and the balance between CH4 production and methanotrophic oxidation determines the rate of CH4 emission into the atmosphere. Coupled to data sets for climate, vegetation, soil, and wetland distribution, the model was used to calculate spatial and seasonal distributions of CH4 emissions at a resolution of 1° latitude × 1° longitude. The calculated net primary production (NPP) of wetlands ranged from 45 g C m-2 yr-1 for northern bogs to 820 g C m-2 yr-1 for tropical swamps. CH4 emission rates from individual gridcells ranged from 0.0 to 661 mg CH4 m-2 d-1, with a mean of 40 mg CH4 m-2 d-1 for northern wetland, 150 mg CH4 m-2 d-1 for temperate wetland, and 199 mg CH4 m-2 d-1 for tropical wetland. Total CH4 emission was 92 Tg yr-1. Sensitivity analysis showed that the response of CH4 emission to climate change depends upon the combined effects of soil carbon storage, rate of decomposition, soil moisture and activity of methanogens.

Cao, Mingkui; Marshall, Stewart; Gregson, Keith

1996-06-01

23

Emission of methane from plants  

PubMed Central

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.

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

2009-01-01

24

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-...

25

Methane emissions from wetlands: biogeochemical, microbial, and modeling perspectives from local to global scales.  

PubMed

Understanding the dynamics of methane (CH4 ) emissions is of paramount importance because CH4 has 25 times the global warming potential of carbon dioxide (CO2 ) and is currently the second most important anthropogenic greenhouse gas. Wetlands are the single largest natural CH4 source with median emissions from published studies of 164 Tg yr(-1) , which is about a third of total global emissions. We provide a perspective on important new frontiers in obtaining a better understanding of CH4 dynamics in natural systems, with a focus on wetlands. One of the most exciting recent developments in this field is the attempt to integrate the different methodologies and spatial scales of biogeochemistry, molecular microbiology, and modeling, and thus this is a major focus of this review. Our specific objectives are to provide an up-to-date synthesis of estimates of global CH4 emissions from wetlands and other freshwater aquatic ecosystems, briefly summarize major biogeophysical controls over CH4 emissions from wetlands, suggest new frontiers in CH4 biogeochemistry, examine relationships between methanogen community structure and CH4 dynamics in situ, and to review the current generation of CH4 models. We highlight throughout some of the most pressing issues concerning global change and feedbacks on CH4 emissions from natural ecosystems. Major uncertainties in estimating current and future CH4 emissions from natural ecosystems include the following: (i) A number of important controls over CH4 production, consumption, and transport have not been, or are inadequately, incorporated into existing CH4 biogeochemistry models. (ii) Significant errors in regional and global emission estimates are derived from large spatial-scale extrapolations from highly heterogeneous and often poorly mapped wetland complexes. (iii) The limited number of observations of CH4 fluxes and their associated environmental variables loosely constrains the parameterization of process-based biogeochemistry models. PMID:23505021

Bridgham, Scott D; Cadillo-Quiroz, Hinsby; Keller, Jason K; Zhuang, Qianlai

2013-02-11

26

High methane emission from Siberian river floodplains  

NASA Astrophysics Data System (ADS)

Methane contributes significantly to global warming. Methane emission is essentially the net result of a balance between CH4 production by methanogenic bacteria in anaerobic soil zones, and CH4 oxidation by methanotrophic bacteria in aerated soil zones and plants. Arctic and sub-arctic permafrost holds a large amount of climate vulnerable carbon. In particular river floodplains are carbon-rich soils. River floodplains in this area are periodically or permanently submerged. The occurrence of flooding decreases soil oxygen availability, providing an ideal anaerobic environment for methane generation. Here we compare the chamber measurements of the methane flux from tundra and floodplain of the Kytalyk site in Northeast Siberia. Model experiments on this site have also been carried out in order to better explain spatial and temporal variations in methane emissions from northern permafrost. This serves as a basis for further model development including modeling of the flooding regime on the floodplain.

Mi, Yanjiao; van Huissteden, Ko; Dolman, Han

2013-04-01

27

Validation of revised DNDC model for methane emissions from irrigated rice fields in Thailand and sensitivity analysis of key factors  

Microsoft Academic Search

The original Denitrification–Decomposition (DNDC) model and a revised version were tested against data from field observations of methane (CH4) emissions from irrigated rice fields in Thailand. The revised DNDC model, which was modified for use in Japanese rice fields by revising the crop growth and soil biogeochemical submodels, yielded better simulation results than the original model. In most cases, daily

Kruamas Smakgahn; Tamon Fumoto; Kazuyuki Yagi

2009-01-01

28

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

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

29

Analysis of predicted changes in methane emissions from wetlands using an integrated climate change effects model  

Microsoft Academic Search

Methane is the second largest contributer to the present day greenhouse effect (IPCC, 2001), with wetlands being the single largest source. However there is considerable uncertainty in the magnitude of these biogenic emissions. Present day estimates vary from 115 (Fung et al., 1991) to 237 Tg CH4 yr-1 (Hein et al., 1997). Moreover it is anticipated that this source is

N. Gedney; P. Cox

2003-01-01

30

Methane emission from Arctic tundra  

Microsoft Academic Search

Concerns about a possible feedback effect on global warming following possible increased emissions of methane from tundra\\u000a environments have lead to series of methane flux studies of northern wetland\\/tundra environments. Most of these studies have\\u000a been carried out in boreal sub-Arctic regions using different techniques and means of assessing representativeness of the\\u000a tundra. Here are reported a time series of

Torben R. Christensen

1993-01-01

31

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

SciTech Connect

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.

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

1992-03-01

32

Modelling the methane emissions from wetlands during the last interglacial period: potential impact on the atmospheric concentrations  

NASA Astrophysics Data System (ADS)

Present-day atmospheric methane concentrations have reached unprecedented levels over the whole 800,000 years recorded in the Antarctic ice core. Due to its high global warming potential, it is crucial to understand its sources and sinks. Whereas the present-day high anomaly is attributable to an increase in anthropogenic emissions, a large natural variability has been observed during the glacial-interglacial cycles, from ~360 ppbv for the cold glacials to ~700 ppbv for the warm interglacials. The origin of this natural variability of methane has been widely debated, suggesting a more plausible source driven variability (i.e. wetlands, representing 20 - 40% of global sources) while the oxidation capacity of the atmosphere (sinks) has remained roughly constant over the ice ages. Nevertheless, most previous studies rely on the use of simplified models of methane surface emissions (non-process based) and/or simplified models of atmospheric chemistry, with simple parametrisation of important processes, such as vegetation dynamics or isoprene chemistry in the atmosphere. We address this issue with state-of-the-art models, both for surface processes and for atmospheric chemistry. Ice core records provide insights of the past state of the atmosphere. From Antarctica's ice core studies, we believe that during the Last Interglacial (LIG), the atmospheric methane concentrations were similar to pre-industrial ones. However, due to strongly different orbital forcings than present-day, the climate at this time is suspected to have been largely different. For example, there is evidence of a +4 to +5°C warming in summer at high northern latitudes compared to pre-industrial (CAPE members, 2006). This could lead to considerable changes in wetland dynamics, however this is not evident in ice core records. The LIG period is used here as a case study for the models, to understand the mechanisms behind the natural variability of the methane atmospheric concentrations. To do so, we recently implemented a sophisticated process-based model of methane emissions (Walter and Heimann, 2000) into a Dynamic Global Vegetation Model (DGVM, Hybrid8). In order to move from surface emissions to atmospheric concentrations, we used a complex atmospheric chemistry model (Met Office UM - UKCA). We report an important sensitivity of the amplitude, seasonality and geographical pattern of the simulated emissions during the LIG. These sensitivities could explain the similar atmospheric methane concentrations between the LIG and the pre-industrial with a drastically different climate.

Quiquet, Aurélien; Friend, Andrew D.; Archibald, Alexander T.; Prentice, I. Colin; Pyle, John A.

2013-04-01

33

Effect of Hydrogen Addition on Methane HCCI Engine Ignition Timing and Emissions Using a Multi-zone Model  

NASA Astrophysics Data System (ADS)

Ignition timing control is of great importance in homogeneous charge compression ignition engines. The effect of hydrogen addition on methane combustion was investigated using a CHEMKIN multi-zone model. Results show that hydrogen addition advances ignition timing and enhances peak pressure and temperature. A brief analysis of chemical kinetics of methane blending hydrogen is also performed in order to investigate the scope of its application, and the analysis suggests that OH radical plays an important role in the oxidation. Hydrogen addition increases NOx while decreasing HC and CO emissions. Exhaust gas recirculation (EGR) also advances ignition timing; however, its effects on emissions are generally the opposite. By adjusting the hydrogen addition and EGR rate, the ignition timing can be regulated with a low emission level. Investigation into zones suggests that NOx is mostly formed in core zones while HC and CO mostly originate in the crevice and the quench layer.

Wang, Zi-han; Wang, Chun-mei; Tang, Hua-xin; Zuo, Cheng-ji; Xu, Hong-ming

2009-06-01

34

Estimating national landfill methane emissions: an application of the 2006 Intergovernmental Panel on Climate Change Waste Model in Panama.  

PubMed

This paper estimates national methane emissions from solid waste disposal sites in Panama over the time period 1990-2020 using both the 2006 Intergovernmental Panel on Climate Change (IPCC) Waste Model spreadsheet and the default emissions estimate approach presented in the 1996 IPCC Good Practice Guidelines. The IPCC Waste Model has the ability to calculate emissions from a variety of solid waste disposal site types, taking into account country- or region-specific waste composition and climate information, and can be used with a limited amount of data. Countries with detailed data can also run the model with country-specific values. The paper discusses methane emissions from solid waste disposal; explains the differences between the two methodologies in terms of data needs, assumptions, and results; describes solid waste disposal circumstances in Panama; and presents the results of this analysis. It also demonstrates the Waste Model's ability to incorporate landfill gas recovery data and to make projections. The former default method methane emissions estimates are 25 Gg in 1994, and range from 23.1 Gg in 1990 to a projected 37.5 Gg in 2020. The Waste Model estimates are 26.7 Gg in 1994, ranging from 24.6 Gg in 1990 to 41.6 Gg in 2020. Emissions estimates for Panama produced by the new model were, on average, 8% higher than estimates produced by the former default methodology. The increased estimate can be attributed to the inclusion of all solid waste disposal in Panama (as opposed to only disposal in managed landfills), but the increase was offset somewhat by the different default factors and regional waste values between the 1996 and 2006 IPCC guidelines, and the use of the first-order decay model with a time delay for waste degradation in the IPCC Waste Model. PMID:18512440

Weitz, Melissa; Coburn, Jeffrey B; Salinas, Edgar

2008-05-01

35

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

SciTech Connect

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.

Jain, Atul K.

2005-09-30

36

Methane and nitrous oxide emissions: an introduction  

Microsoft Academic Search

Methane and nitrous oxide are important greenhouse gases. They contribute to global warming. To a large extent, emissions of methane and nitrous oxide are connected with the intensification of food production. Therefore, feeding a growing world population and at the same time controlling these emissions is a great challenge. Important anthropogenic sources of biogenic methane are wet rice fields, cattle,

A. R. van Amstel; R. J. Swart

1994-01-01

37

Approach for Estimating Global Landfill Methane Emissions.  

National Technical Information Service (NTIS)

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. T...

R. L. Peer A. E. Leininger B. B. Emmel S. K. Lynch

1991-01-01

38

Methane emissions from the West Siberian wetlands  

NASA Astrophysics Data System (ADS)

Methane is an important greenhouse gas contributing as much as 20% of the anthropogenic radiative forcing in the contemporary atmosphere. Therefore estimation of the relative contribution of different methane sources to the atmosphere is a crucial task in addressing the problem of global warming. Mires are the main natural source of methane. West Siberia gains the especial importance in this respect as one of the most paludified region in the world with the mire area of 68.5 Mha or 27% of this region area. Since the previously published estimations of the regional flux varied widely from 2 to 22 MtCH4y-1, long-term and large-scale investigations of CH4 emission were organized in this study. More than 1500 methane flux measurements were made during the summer-autumn of 2007-2010. All variety of wetland types was reduced to 8 microlandscape types: palsas, ryams (dwarf pine-shrub-sphagnum communities), ridges, eutrophic, mesotrophic and oligotrophic hollows, peat mats and wetland ponds. Mire micro-landscapes of 30 key sites distributed in 7 zones (tundra, forest-tundra, north, middle and south taiga, sub-taiga and forest-steppe) of West Siberia were observed. Methane fluxes were measured by the static chamber method. Emission data were generalized into spatial emission model. The model is based upon a fractional area coverage map of mire micro-landscapes, methane emission periods for each zone and methane flux probability density distributions for each microlandscape type in these zones. The methane emission map with the resolution 0.5°×0.5° was created. It was confirmed that palsas, ryams and ridges had the lowest methane fluxes (1st/2nd/3rd quartiles are -0.04/0/0.04 mgCH4m-2h-1 for palsas, 0/0.04/0.28 mgCH4m-2h-1 for ryams, 0/0.09/0.37 mgCH4m-2h-1 for ridges) while the peat mats, poor fens and fens had the highest fluxes (2.74/4.65/6.11 mgCH4m-2h-1 for peat mats, 1.15/3.35/6.21 mgCH4m-2h-1 for fens combined with poor fens). Highest methane fluxes, reaching hundreds of mgCH4m-2h-1, were observed in shallow ponds. Oligotrophic hollows of middle and south taiga as well as south taiga eutrophic hollows and ponds appeared as the most significant regional methane sources accounting for about 50% of the annual methane flux from West Siberia mires. The latest version of emission model estimates the total flux from all Western Siberia mires at 3.21 MtCH4y-1.

Maksyutov, S.; Glagolev, M.; Kleptsova, I.; Sabrekov, A.; Peregon, A.; Machida, T.

2010-12-01

39

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

Microsoft Academic Search

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 (CH4). Modeling allows us to examine potential outcomes of feeding strategies under controlled conditions, and

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

2012-01-01

40

Methane emissions from a small wind shielded lake determined by eddy covariance, flux chambers, anchored funnels, and boundary model calculations: a comparison.  

PubMed

Lakes are large sources of methane, held to be responsible for 18% of the radiative forcing, to the atmosphere. Periods of lake overturn (during fall/winter) are short and therefore difficult to capture with field campaigns but potentially one of the most important periods for methane emissions. We studied methane emissions using four different methods, including eddy covariance measurements, floating chambers, anchored funnels, and boundary model calculations. Whereas the first three methods agreed rather well, boundary model estimates were 5-30 times lower leading to a strong underestimation of methane fluxes from aquatic systems. These results show the importance of ebullition as the most important flux pathway and the need for continuous measurements with a large footprint covering also shallow parts of lakes. Although fluxes were high, on average 4 mmol m(-2) d(-1) during the overturn period, water column microbial methane oxidation removed 75% of the methane and only 25% of potential emissions were released to the atmosphere. Hence, this study illustrates second the importance of considering methane oxidation when estimating the flux of methane from lakes during overturn periods. PMID:22436104

Schubert, Carsten J; Diem, Torsten; Eugster, Werner

2012-04-04

41

Bracketing the range of lake and wetland methane emissions rates in West Siberia using models, in situ observations, and remote sensing  

NASA Astrophysics Data System (ADS)

Large uncertainties exist in estimates of global lake and wetland methane emission rates, due in part to their large spatial and temporal heterogeneity and also due to the sparseness of in situ observations. This is especially true of lakes and inundated wetlands, for which ebullition is a major methane pathway. Here we use a large-scale coupled land-atmosphere model and remote sensing observations to bracket the range of possible emissions rates from lakes and wetlands in West Siberia. Our modeling framework consists of a large-scale hydrology model (Variable Infiltration Capacity; VIC), extended to handle carbon cycling and methane emissions, coupled to an atmospheric tracer-transport model (NIES Chemical Tracer Model; CTM) driven by NCAR/NCEP reanalysis fields. In the model, "permanent" lake areas are prescribed by the Global Lake and Wetland Database, bias-corrected to account for small lakes. Seasonal inundation of wetlands is dynamic and has been calibrated to match an inundation dataset derived from remote sensing (AMSR-E and Qscat). We calibrated the model's wetland methane emissions to match in situ observations from a large dataset collected in West Siberia between 2006 and 2010. Lake emission rates are prescribed in several scenarios that span the range of observed rates reported in the literature. We explore the relative sizes of various sources of uncertainty in simulated methane emissions: uncertainty in inundated area, parameter uncertainty in the methane emissions model, and the range of possible lake emissions rates. Using values from different ends of the spectrum of these uncertainty sources leads to markedly different spatial patterns of methane emissions across West Siberia. These emissions are ingested by the atmospheric tracer model to produce maps of atmospheric methane concentrations. We compare the resulting spatial patterns of methane concentrations with remotely-sensed observations from the AIRS and GOSAT satellite sensors and explore the implied likelihoods of the different lake and wetland emissions rates. Portions of this work were carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration.

Bohn, T.; Maksyutov, S.; Kim, H.-S.; Glagolev, M.; Schroeder, R.; McDonald, K.; Podest, E.; Chen, X.; Livneh, B.; Lettenmaier, D.

2012-04-01

42

Comparing satellite-retrieved atmospheric methane with a 3-D chemical transport model driven by bottom-up emission estimates.  

NASA Astrophysics Data System (ADS)

Global methane accounts for approximately 20% of the total direct radiative forcing by long-lived greenhouse gases (0.5Wm-2), making it the second largest contributor after carbon dioxide. Variations in CH4 emissions are likely to be rapidly observable in the atmospheric composition due to its relatively short lifetime (approximately 9 years). As a result emission values can be estimated using atmospheric retrievals. By comparing satellite retrievals (GOSAT) with various emission inventories put through a chemical transport model (TOMCAT) a better understanding can be made as to the accuracy of the input fluxes. Previous model experiments show that a large uncertainty in bottom-up CH4 fluxes occurs over wetland regions. The aim of this study is to investigate which inventory performs best over wetlands when compared with satellite retrievals. The comparison will help to identify model errors, which will allow for the development of model parameters. Improving modelled CH4 emissions will improve understanding of regional CH4 sources and increase the accuracy of climate change predictions. We have used the TOMCAT off-line chemical transport model (CTM) to perform simulations over the period 2002 to 2010. The model is forced by ECMWF ERA-Interim reanalyses and run at a horizontal resolution of 2.8o x 2.8o with 60 levels from the surface to ~60km. The model simulates atmospheric CH4 based on surface emissions and atmospheric loss rates based on specified OH and O(1D) fields. A number of CH4 tracers have been included in the simulation based on different emission scenarios. These include scenarios provided for the recent Transcom-CH4 study and bottom-up emissions provided by the UK JULES land surface model. The quality of the different emission scenarios has been assessed by comparing with atmospheric observations. In addition to GOSAT retrievals, results have been compared with surface in-situ data and NDACC/TCCON ground-based column observations.

McNorton, Joe; Chipperfield, Martyn; Wilson, Chris; Gloor, Emanuel; Parker, Rob; Hayman, Garry

2013-04-01

43

Methane emission from bogs in the subtaiga of Western Siberia: The development of standard model  

NASA Astrophysics Data System (ADS)

The methane emission from typical bog landscapes of the West Siberian subtaiga was studied in the summer-autumn of 2007-2010. The lowest specific fluxes (the median value is 0.08 mg C-CH4/m2 per h) were recorded from ryams (raised bogs with dwarf shrub-sphagnum associations). From the ridges of the ridge-pool complexes, the fluxes were estimated at 0.49 mg C-CH4/m2 per h; from the oligotrophic hollows, eutrophic bogs, floating lake mats, and mesotrophic quaking bogs, they were estimated at 2.68, 3.36, 4.53, and 4.98 mg C-CH4/m2 per h, respectively. The maximal flux was determined from the lakes (the median is 17.98 mg C-CH4/m2 per h). The regional assessment of the methane flux from the bogs of Western Siberia (2.93 Tg C-CH4/yr) was obtained on the basis of the authors' and literature data.

Glagolev, M. V.; Sabrekov, A. F.; Kleptsova, I. E.; Filippov, I. V.; Lapshina, E. D.; Machida, T.; Maksyutov, Sh. Sh.

2012-10-01

44

Coalbed methane modeling analysis  

Microsoft Academic Search

Systems analyses or the Department of Energy's (DOE) Coalbed Methane Project (CMP) were performed at the Morgantown Energy Technology Center (METC). In the analyses, both reservoir and stimulation models were evaluated using data from US Steel's Oak Grove Coal Degasification Field. In the first part of the study two reservoir models designed for predicting methane and water production from coalbeds,

G. L. Covatch; A. W. Layne; S. P. Salamy

1985-01-01

45

Methane emissions from grazing cattle using point-source dispersion.  

PubMed

The ability to accurately measure greenhouse gas (GHG) emissions is essential to gauge our ability to reduce these emissions. Enteric methane from ruminants is an important but often difficult source to quantify since it depends on the amount and type of feed intake. Unfortunately, many of the available measurement techniques for estimating enteric methane emissions can impose a change in feed intake. Our study evaluates a nonintrusive technique that uses a novel approach (point-source dispersion with multiple open-path concentrations) to calculate enteric methane emissions from grazing cattle, reported as the major source of GHG in many countries, particularly Australia. A scanner with a mounted open-path laser was used to measure methane concentration across five paths above a paddock containing 18 grazing cattle over 16 d. These data were used along with wind statistics in a dispersion model (WindTrax) to estimate an average herd methane emission rate over 10-mm intervals. Enteric methane emissions from the herd grazing a combination of Rhodes grass (Chlotis gayana Kunth) and Leucaena [Leucaena leucocephala (Lam.)] averaged (+/- SD) 141 (+/- 147) g animal(-1) d(-1). In a release-recovery experiment, the technique accounted for 77% of the released methane at a single point. Our study shows the technique generates more reliable methane emissions during daytime (unstable stratification). PMID:21488489

McGinn, S M; Turner, D; Tomkins, N; Charmley, E; Bishop-Hurley, G; Chen, D

46

Quantifying methane emissions from rice paddies in Northeast China by integrating remote sensing mapping with a biogeochemical model  

NASA Astrophysics Data System (ADS)

The Sanjiang Plain located in Northeastern China is one of the major rice producing regions in the country. However, differing from the majority rice regions in Southern China, the Sanjinag Plain possesses a much cooler weather. Could the rice paddies in this domain be an important source of global methane? To answer this question, we calculated methane (CH4) emissions from the region by integrating remote sensing mapping with a process-based biogeochemistry model, Denitrification and Decomposition or DNDC. To quantify regional CH4 emissions from the plain, we first tested the model against a two-year dataset of CH4 fluxes measured at a typical rice field within the domian. A sensitivity test was conducted to find out the most sensitive factors affecting CH4 emissions in the region. Based on the understanding gained from the validation and sensitivity tests, a geographic information system (GIS) database was constructed to hold the spatially differentiated input information to drive DNDC for its regional simulations. The GIS database included a rice map derived from the Landsat TM images, which provided crucial information about the spatial distribution of the rice fields within the domain of 10.93 million hectares. The modeled results showed that the total 1.44 million ha of rice paddies in the plain emitted 0.43-0.58 Tg CH4-C per year with spatially differentiated annual emission rates ranging between 100-800 kg CH4-C/ha, which are comparable with that observed in Southern China. The modeled data indicated that the high SOC contents, long crop season and high rice biomass enhanced CH4 production in the cool paddies. The modeled results proved that the northern wetland agroecosystems could make important contributions to global greenhouse gas inventory.

Zhang, Y.; Wang, Y. Y.; Su, S. L.; Li, C. S.

2011-01-01

47

Sensitivity analysis of a wetland methane emission model based on temperate and Arctic wetland sites  

NASA Astrophysics Data System (ADS)

Modelling of wetland CH4 fluxes using wetland soil emission models is used to determine the size of this natural source of CH4 emission on local to global scale. Most process models of CH4 formation and soil-atmosphere CH4 transport processes operate on a plot scale. For large scale emission modelling (regional to global scale) upscaling of this type of model requires thorough analysis of the sensitivity of these models to parameter uncertainty. We applied the GLUE (Generalized Likelihood Uncertainty Analysis) methodology to a well-known CH4 emission model, the Walter-Heimann model, as implemented in the PEATLAND-VU model. The model is tested using data from two temperate wetland sites and one arctic site. The tests include experiments with different objective functions, which quantify the fit of the model results to the data. The results indicate that the model 1) in most cases is capable of estimating CH4 fluxes better than an estimate based on the data avarage, but does not clearly outcompete a regression model based on local data; 2) is capable of reproducing larger scale (seasonal) temporal variability in the data, but not the small-scale (daily) temporal variability; 3) is not strongly sensitive to soil parameters, 4) is sensitive to parameters determining CH4 transport and oxidation in vegetation, and the temperature sensitivity of the microbial population. The GLUE method also allowed testing of several smaller modifications of the original model. We conclude that upscaling of this plot-based wetland CH4 emission model is feasible, but considerable improvements of wetland CH4 modelling will result from improvement of wetland vegetation data.

van Huissteden, J.; Petrescu, A. M. R.; Hendriks, D. M. D.; Rebel, K. T.

2009-09-01

48

Sensitivity analysis of a wetland methane emission model based on temperate and arctic wetland sites  

NASA Astrophysics Data System (ADS)

Modelling of wetland CH4 fluxes using wetland soil emission models is used to determine the size of this natural source of CH4 emission on local to global scale. Most process models of CH4 formation and soil-atmosphere CH4 transport processes operate on a plot scale. For large scale emission modelling (regional to global scale) upscaling of this type of model requires thorough analysis of the sensitivity of these models to parameter uncertainty. We applied the GLUE (Generalized Likelihood Uncertainty Analysis) methodology to a well-known CH4 emission model, the Walter-Heimann model, as implemented in the PEATLAND-VU model. The model is tested using data from two temperate wetland sites and one arctic site. The tests include experiments with different objective functions, which quantify the fit of the model results to the data. The results indicate that the model 1) in most cases is capable of estimating CH4 fluxes better than an estimate based on the data avarage, but does not clearly outcompete a regression model based on local data; 2) is capable of reproducing larger scale (seasonal) temporal variability in the data, but not the small-scale (daily) temporal variability; 3) is not strongly sensitive to soil parameters, 4) is sensitive to parameters determining CH4 transport and oxidation in vegetation, and the temperature sensitivity of the microbial population. The GLUE method also allowed testing of several smaller modifications of the original model. We conclude that upscaling of this plot-based wetland CH4 emission model is feasible, but considerable improvements of wetland CH4 modelling will result from improvement of wetland vegetation data.

van Huissteden, J.; Petrescu, A. M. R.; Hendriks, D. M. D.; Rebel, K. T.

2009-12-01

49

Capturing fugitive methane emissions from natural gas compressor buildings.  

PubMed

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

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

2006-08-07

50

Applying guidance for methane emission estimation for landfills.  

PubMed

Quantification of methane emission from landfills is important to evaluate measures for reduction of greenhouse gas emissions. Both the United Nations and the European Union have adopted protocols to ensure quantification of methane emission from individual landfills. The purpose of these protocols is to disclose emission data to regulators and the general public. Criteria such as timeliness, completeness, certainty, comparability, consistency and transparency are set for inclusion of emission data in a publicly accessible database. All methods given as guidance to landfill operators to estimate landfill methane emissions are based on models. In this paper the consequences of applying six different models for estimates of three landfills are explored. It is not the intention of this paper to criticise or validate models. The modelling results are compared with whole site methane emission measurements. A huge difference in results is observed. This raises doubts about the accuracy of the models. It also indicates that at least some of the criteria previously mentioned are not met for the tools currently available to estimate methane emissions from individual landfills. This will inevitably lead to compiling and comparing data with an incomparable origin. Harmonization of models is recommended. This may not necessarily reduce uncertainty, but it will at least result in comparable, consistent and transparent data. PMID:16442791

Scharff, Heijo; Jacobs, Joeri

2006-01-26

51

Applying guidance for methane emission estimation for landfills  

SciTech Connect

Quantification of methane emission from landfills is important to evaluate measures for reduction of greenhouse gas emissions. Both the United Nations and the European Union have adopted protocols to ensure quantification of methane emission from individual landfills. The purpose of these protocols is to disclose emission data to regulators and the general public. Criteria such as timeliness, completeness, certainty, comparability, consistency and transparency are set for inclusion of emission data in a publicly accessible database. All methods given as guidance to landfill operators to estimate landfill methane emissions are based on models. In this paper the consequences of applying six different models for estimates of three landfills are explored. It is not the intention of this paper to criticise or validate models. The modelling results are compared with whole site methane emission measurements. A huge difference in results is observed. This raises doubts about the accuracy of the models. It also indicates that at least some of the criteria previously mentioned are not met for the tools currently available to estimate methane emissions from individual landfills. This will inevitably lead to compiling and comparing data with an incomparable origin. Harmonisation of models is recommended. This may not necessarily reduce uncertainty, but it will at least result in comparable, consistent and transparent data.

Scharff, Heijo [NV Afvalzorg, Postbus 2, 1566 ZG Assendelft (Netherlands)]. E-mail: h.scharff@afvalzorg.nl; Jacobs, Joeri [NV Afvalzorg, Postbus 2, 1566 ZG Assendelft (Netherlands)]. E-mail: j.jacobs@afvalzorg.nl

2006-07-01

52

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

53

Systematic biases in large-scale estimates of wetland methane emissions arising from water table formulations  

Microsoft Academic Search

Most earth system models that simulate wetland methane emissions ignore spatial variability of water table depth. We compared methane emissions estimated using two commonly-used water table approximations (wet-dry and uniform) to a scheme that accounts for spatial variability, for several combinations of methane model parameter values and a range of water table depth spatial variability (?zwt). The approximations' biases were

Theodore J. Bohn; Dennis P. Lettenmaier

2010-01-01

54

Regional methane emission from West Siberia mire landscapes  

NASA Astrophysics Data System (ADS)

Methane emissions from mires in all climate-vegetation zones of West Siberia (forest steppe, subtaiga, south taiga, middle taiga, north taiga, forest tundra and tundra) were measured using a static chamber method. The observed fluxes varied considerably from small negative values in forested bogs and palsa to hundreds of mgC m - 2 h - 1 in ponds and wet hollows. Observed data were consolidated in the form of the empirical model of methane emissions designated as the 'standard model'. The model is based on medians of CH4 flux distributions of eight different micro-landscape types depending on their location and estimated duration of methane emission period within the climate-vegetation zone. The current version (Bc8) of the 'standard model' estimates methane flux from West Siberia mires at 2.93 ± 0.97 TgC CH4 yr - 1 that accounts for about 2.4% of the total methane emission from all mires or 0.7% of global methane emission from all sources.

Glagolev, M.; Kleptsova, I.; Filippov, I.; Maksyutov, S.; Machida, T.

2011-10-01

55

Global methane emissions from terrestrial plants.  

PubMed

Recent measurements suggest that the terrestrial plant community may be an important source of methane with global contributions between 62 and 236 Tg CH4 y(-1). If true, terrestrial plants could rival wetlands as being the largest global source of methane forcing us to rethink the methane budget. While further measurements are needed to confirm the methane release rates from this source and their dependencies, in this work we use the preliminary measurements to assess the potential impact of the methane release from this source globally. Using novel techniques we extrapolate the initially reported chamber measurements to the global scale and calculate the global methane emissions from the terrestrial plant community to be in the range 20 to 69 Tg CH4 y(-1). The spread in emissions is largely due to the sensitivity of the global flux to the prescribed temperature dependence of the plant emission rate, which is largely unknown. The spread of calculated emissions is in good agreement with the upper limit imposed on the source during the late pre-industrial period, which we estimate to range from 25 to 54 Tg CH4 y(-1) during the years 0 to 1700 A.D. using the published atmospheric delta13CH4 record. In addition, if we assume that plant emissions have been constant at the mean value of 45 Tg CH4 y(-1), we find that the methane release from wildfires and biomass burning during the pre-industrial span 0-1000 A.D. must be near 12 Tg CH4 y(-1), which would be in better agreement with previous estimates of the pyrogenic source during this time than a methane budget missing the plant source. We conclude that methane release from the terrestrial plant community as presently understood does not require major innovations to the global methane budget. PMID:17612186

Butenhoff, Christopher L; Khalil, M Aslam Khan

2007-06-01

56

Methane emissions from natural wetlands  

Microsoft Academic Search

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

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

1993-01-01

57

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

Microsoft Academic Search

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

Robin Matthews; Reiner Wassmann

2003-01-01

58

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...

59

Landfill operation for carbon sequestration and maximum methane emission control.  

National Technical Information Service (NTIS)

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 generat...

D. Augenstein R. Yazdani R. Moore M. Byars J. Kieffer M. Barlaz R. Mehta

2000-01-01

60

Tree-mediated methane emissions from tropical and temperate peatlands.  

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

61

Geologic emissions of methane to the atmosphere.  

PubMed

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

Etiope, Giuseppe; Klusman, Ronald W

2002-12-01

62

Coalbed methane modeling: Multicomponent effects  

Microsoft Academic Search

Field data from coalbed methane wells indicate a significant variation in composition as a function of flow rate and time. Prediction of gas quality is critical to the economic evaluation of any coalbed methane project. Previous models have forecast only pressure and production profiles, ignoring compositional variations. A multicomponent model that incorporates binary isotherms for methane and carbon dioxide has

1992-01-01

63

Methane emission from rice paddies  

Microsoft Academic Search

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

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

1983-01-01

64

MEASUREMENT OF METHANE EMISSIONS FROM UNDERGROUND DISTRIBUTION MAINS AND SERVICES  

EPA Science Inventory

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

65

A robust method for estimating landfill methane emissions.  

PubMed

Because municipal solid waste (MSW) landfills emit significant amounts of methane, a potent greenhouse gas, there is considerable interest in quantifying surficial methane emissions from landfills. The authors present a method to estimate methane emissions, using ambient air volatile organic compound (VOC) measurements taken above the surface of the landfill. Using a hand-held monitor, hundreds of VOC concentrations can be taken easily in a day, and simple meteorological data can be recorded at the same time. The standard Gaussian dispersion equations are inverted and solved by matrix methods to determine the methane emission rates at hundreds of point locations throughout a MSW landfill. These point emission rates are then summed to give the total landfill emission rate. This method is tested on a central Florida MSW landfill using data from 3 different days, taken 6 and 12 months apart. A sensitivity study is conducted, and the emission estimates are most sensitive to the input meteorological parameters of wind speed and stability class. Because of the many measurements that are used, the results are robust. When the emission estimates were used as inputs into a dispersion model, a reasonable scatterplot fit of the individual concentration measurement data resulted. PMID:19728486

Figueroa, Veronica K; Mackie, Kevin R; Guarriello, Nick; Cooper, C David

2009-08-01

66

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 ...

67

Biotic systems to mitigate landfill methane emissions.  

PubMed

Landfill gases produced during biological degradation of buried organic wastes include methane, which when released to the atmosphere, can contribute to global climate change. Increasing use of gas collection systems has reduced the risk of escaping methane emissions entering the atmosphere, but gas capture is not 100% efficient, and further, there are still many instances when gas collection systems are not used. Biotic methane mitigation systems exploit the propensity of some naturally occurring bacteria to oxidize methane. By providing optimum conditions for microbial habitation and efficiently routing landfill gases to where they are cultivated, a number of bio-based systems, such as interim or long-term biocovers, passively or actively vented biofilters, biowindows and daily-used biotarps, have been developed that can alone, or with gas collection, mitigate landfill methane emissions. This paper reviews the science that guides bio-based designs; summarizes experiences with the diverse natural or engineered substrates used in such systems; describes some of the studies and field trials being used to evaluate them; and discusses how they can be used for better landfill operation, capping, and aftercare. PMID:18338700

Huber-Humer, Marion; Gebert, Julia; Hilger, Helene

2008-02-01

68

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...

69

Building a better methane generation model: Validating models with methane recovery rates from 35 Canadian landfills  

Microsoft Academic Search

The German EPER, TNO, Belgium, LandGEM, and Scholl Canyon models for estimating methane production were compared to methane recovery rates for 35 Canadian landfills, assuming that 20% of emissions were not recovered. Two different fractions of degradable organic carbon (DOCf) were applied in all models. Most models performed better when the DOCf was 0.5 compared to 0.77. The Belgium, Scholl

Shirley Thompson; Jennifer Sawyer; Rathan Bonam; J. E. Valdivia

2009-01-01

70

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

NASA Astrophysics Data System (ADS)

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

Bogomolov, Vasiliy; Stepanenko, Victor; Okladnikov, Igor

2013-04-01

71

METHANE EMISSIONS FROM WETLAND RICE AREAS OF ASIA  

EPA Science Inventory

Kahlil and Rasmussen (1990) reviewed eleven global methane budgets published between 1978 and 1988. hey found methane emissions from rice paddies ranged from 18 to 280 Tg year-1 which correspond to between 10 and 70% of the total anthropogenic methane emissions. or this paper, we...

72

Zero methane emission bogs: extreme rhizosphere oxygenation by cushion plants in Patagonia.  

PubMed

• Vascular wetland plants may substantially increase methane emissions by producing root exudates and easily degradable litter, and by providing a low-resistance diffusion pathway via their aerenchyma. However, model studies have indicated that vascular plants can reduce methane emission when soil oxygen demand is exceeded by oxygen released from roots. Here, we tested whether these conditions occur in bogs dominated by cushion plants. • Root-methane interactions were studied by comparing methane emissions, stock and oxygen availability in depth profiles below lawns of either cushion plants or Sphagnum mosses in Patagonia. • Cushion plants, Astelia pumila and Donatia fascicularis, formed extensive root systems up to 120 cm in depth. The cold soil (< 10°C) and highly decomposed peat resulted in low microbial activity and oxygen consumption. In cushion plant lawns, high soil oxygen coincided with high root densities, but methane emissions were absent. In Sphagnum lawns, methane emissions were substantial. High methane concentrations were only found in soils without cushion plant roots. • This first methane study in Patagonian bog vegetation reveals lower emissions than expected. We conclude that cushion plants are capable of reducing methane emission on an ecosystem scale by thorough soil and methane oxidation. PMID:21232058

Fritz, Christian; Pancotto, Veronica A; Elzenga, Josephus T M; Visser, Eric J W; Grootjans, Ab P; Pol, Arjan; Iturraspe, Rodolfo; Roelofs, Jan G M; Smolders, Alfons J P

2011-01-14

73

News about methane emission from plant matter  

NASA Astrophysics Data System (ADS)

Almost two years ago, Keppler et al. [2006] published results from laboratory experiments indicating that living plants, plant litter and the structural plant component pectin emit methane to the atmosphere under aerobic conditions. These findings contradict the accepted view that methane can be formed under oxygen-free conditions only, and in fact we still lack a fundamental understanding of the production process. They also have far-reaching implications since they imply a new and possibly important plant-climate feedback, since the global source strength estimated from those laboratory measurements was large. The scientific debate first concentrated on the up-scaling approach, and several other approaches have been suggested. However, since no up-scaling rule has been identified, also other up-scaling methods lack a solid scientific basis and the fundamental question at this stage is whether aerobic CH4 emissions from the biosphere do actually exist. Several possible experimental artifacts in the experiments of Keppler et al. have been suggested, and in fact one recent study has reported the absence of CH4 emissions from vegetation [Dueck, et al., 2007], but the discrepancy to the measurements of Keppler et al. could not be explained. In our follow up research we have aimed at proving that an aerobic CH4 production mechanism does indeed exist. Our new results - obtained with different analytical techniques - show that dry and fresh plant matter, as well as several structural plant components, emit significant amounts of methane upon irradiation with UV light and heating. Emissions from UV irradiation are almost instantaneous, indicating a direct photochemical process. The size of the methane-forming reservoir exceeds the size of suggested contamination sources by several orders of magnitude. A dry leaf of a pure 13C plant also produces 13CH¬4. References Dueck, T. A., R. de Visser, H. Poorter, S. Persijn, A. Gorissen, W. de Visser, A. Schapendonk, J. Verhagen, J. Snel, F. J. M. Harren, A. K. Y. Ngai, F. Verstappen, H. Bouwmeester, L. A. C. J. Voesenek, and A. van der Werf, No evidence for substantial aerobic methane emission by terrestrial plants: a 13C-labelling approach New Phytologist, doi : 10.1111/j.1469-8137.2007.02103.x, 2007. Keppler, F., J. T. G. Hamilton, M. Brass, and T. Röckmann, Methane emissions from terrestrial plants under aerobic conditions, Nature, 439, 187-191, doi:110.1038/nature04420, 2006.

Röckmann, T.; Vigano, I.; Holzinger, R.; van Weelden, H.; Keppler, F.

2007-12-01

74

Siberian shelf methane emissions not tied to modern warming  

NASA Astrophysics Data System (ADS)

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)

Schultz, Colin

2011-12-01

75

SEASONAL AND DIURNAL METHANE EMISSIONS FROM A LANDFILL AND THEIR REGULATION BY METHANE OXIDATION  

Microsoft Academic Search

Rates of methane emission from a Swedish landfill, measured by chamber technique and permanent frames, ranged between 0.034 and 20 mmol CH4m?2. h?1on average. The emissions followed a seasonal pattern, with the highest fluxes occurring between September and May. Methane concentrations in soil also followed a seasonal pattern, with a marked decrease during summers. Using the means of methane emission

Gunnar Börjesson; Bo H. Svensson

1997-01-01

76

Variability in Methane Emissions from a Temperate Poor Fen  

NASA Astrophysics Data System (ADS)

Methane is the most abundant organic compound in Earth's atmosphere, where it is an efficient infrared radiation absorber. Methane influences the global climate by contributing approximately 25% to the radiative forcing of greenhouse gases. Total annual emissions of methane range from 500 to 600 Tg. Methane emissions from wetlands are the most important natural source but also one that is highly uncertain. Recent estimates vary by a factor of ca. 2.5. There is much uncertainty in our present understanding of methane dynamics. Without such knowledge, we cannot understand how the natural contribution to the global methane balance is likely to change under different climate scenarios in the future. Long term datasets are important in evaluating the responses of natural systems to climatic forcing. Methane exchange has been measured in Sallie's Fen in New Hampshire USA since 1989 using the same static chamber methodology at the same sites linked to consistent analytical standards from CMDL. Individual surface fluxes are highly variable on a daily to seasonal temporal scale indicating they are controlled by weather. The 16 year dataset shows that annual fluxes have varied by a factor of 3 (ca. 40-120 gC-CH4 m-2) with differing seasonal distributions of the flux. On average most of the flux is in the summer and about 4% in the winter with the spring and fall emissions dependent on weather. CH4 emissions have been lower (ca. 40 g C m-2) since 2000 compared to the previous decade (ca. 75 g C m-2) probably because of a shift in nutrient status as peat accumulates and the fen grows to be more similar to a nutrient poor bog. Interpolation of a C balance model suggest that Sallie's Fen has been a sink of atmospheric CO2 from the atmosphere in with most (52 - 91 gC- CO2 m-2) fixed in the summer and a consistent loss of 12-19 gC- CO2 m-2 in the winter. However, when CH4 emissions (48-122 gC-CH4 m-2) and DOC export (ca. 3 gC m-2) are added to the total, Sallie's Fen lost C in 1994 and was only a weak sink of C in 1995-1997 demonstrating that CH4 emissions can have a significant impact on the C balance of a natural wetland. Longer term decadal patterns in flux are controlled by the growth of the peatland and the surface hydrology or moisture regime which will be determined by climate.

Crill, P. M.

2004-12-01

77

Livestock methane emission: From the individual grazing animal through national inventories to the global methane cycle  

Microsoft Academic Search

Methane is a potent greenhouse gas whose atmospheric abundance has grown 2.5-fold over three centuries, due in large part to agricultural expansion. The farming of ruminant livestock, which generate and emit methane during digestion (‘enteric fermentation’), is a leading contributor to this growth. This paper overviews the measurement or estimation of enteric methane emissions at a range of spatial scales.

Keith R. Lassey

2007-01-01

78

Approach for estimating global landfill-methane emissions. Final report, April-September 1990  

SciTech Connect

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 approach for using country-specific and field test data to develop a less uncertain estimate of global landfill methane. Development of enhanced emissions factors for landfills and other major sources of methane will improve the understanding of atmospheric chemistry and feedback effects, will target mitigation opportunities, and will ensure cost-effective mitigation strategies.

Peer, R.L.; Leininger, A.E.; Emmel, B.B.; Lynch, S.K.

1991-01-01

79

Methane Emissions From Western Siberian Wetlands: Heterogeneity and Sensitivity to Climate Change  

NASA Astrophysics Data System (ADS)

Prediction of methane emissions from high-latitude wetlands is important given concerns about their sensitivity to a warming climate. As a basis for prediction of wetland methane emissions at regional scales, we have coupled the Variable Infiltration Capacity macroscale hydrological model (VIC) with the Biosphere-Energy-Transfer- Hydrology terrestrial ecosystem model (BETHY) and a wetland methane emissions model to make large-scale estimates of methane emissions as a function of soil temperature, water table depth, and net primary productivity (NPP), with a parameterization of the sub-grid heterogeneity of the water table depth based on topographic wetness index. Using landcover classifications derived from L-band satellite synthetic aperture radar imagery, we simulated methane emissions for the Chaya River basin in western Siberia, an area that includes the Bakchar Bog, for a retrospective baseline period of 1980-1999, and evaluated their sensitivity to increases in temperature of 0-5 °C and increases in precipitation of 0-15%. The interactions of temperature and precipitation, through their effects on the water table depth, play an important role in determining methane emissions from these wetlands. The balance between these effects varies spatially, and their net effect depends in part on sub- grid topographic heterogeneity. Higher temperatures alone increase methane production in saturated areas, but cause those saturated areas to shrink in extent, resulting in a net reduction in methane emissions. Higher precipitation alone raises water tables and expands the saturated area, resulting in a net increase in methane emissions. Combining a temperature increase of 3 °C and an increase of 10% in precipitation, to represent the climate conditions likely in western Siberia at the end of this century, results in roughly a doubling of annual methane emissions. This work was carried out at the University of Washington, at Purdue University, and at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

Bohn, T. J.; Lettenmaier, D. P.; Podest, E.; McDonald, K. C.; Sathulur, K.; Bowling, L. C.; Friborg, T.

2007-12-01

80

Indian methane and nitrous oxide emissions and mitigation flexibility  

NASA Astrophysics Data System (ADS)

Methane (CH 4) and nitrous oxide (N 2O) contributed 27% and 7%, respectively, to India's CO 2 equivalent greenhouse gas (GHG) emissions in 2000, the remaining being the carbon dioxide (CO 2) emissions. Presently, agriculture and livestock related emissions contribute above 65% of Indian CH 4 emissions and above 90% of N 2O emissions. Since these activities are widely dispersed, with a considerable portion being sub-sustenance activities, emission mitigation requires considerable efforts. We use geographical information system (GIS) interfaced Asia-Pacific Integrated Model (AIM/Enduse), which employs technology share projections, for estimating future CH 4 and N 2O emissions. The future emissions and mitigation flexibility are analyzed for a reference scenario and two mitigation scenarios (medium and strong). Future CH 4 emissions in 2030 are projected to reach 24.4 Tg (reference scenario), 21.3 Tg (medium mitigation scenario) and 17.6 Tg (strong mitigation scenario). Future CH 4 emission scenarios indicate rising shares of municipal solid waste (MSW) and coal bed methane, where mitigation technologies have good penetration potential. Improved cattle feed and digesters, and better rice paddy cultivation practices that are adopted for higher yields and improved irrigation coverage also offer CH 4 mitigation as ancillary benefits. Future N 2O emissions in 2030 are projected to reach 0.81 Tg (reference scenario), 0.69 Tg (medium mitigation scenario) and 0.6 Tg (strong mitigation scenario). Better utilization of nitrogen fertilizer and increased use of organic fertilizers, partly produced from MSW, offer interesting mitigation opportunities for N 2O emissions. Some of these technology initiatives are already visible in India at different stages of development and appropriate policy thrust may strengthen them in future.

Garg, Amit; Shukla, P. R.; Kapshe, Manmohan; Menon, Deepa

81

Global anthropogenic methane emissions 2005-2030: technical mitigation potentials and costs  

NASA Astrophysics Data System (ADS)

This paper presents estimates of current and future global anthropogenic methane emissions, their technical mitigation potential and associated costs for the period 2005 to 2030. The analysis uses the GAINS model framework to estimate emissions, mitigation potentials and costs for all major sources of anthropogenic methane for 83 countries/regions, which are aggregated to produce global estimates. Global emissions are estimated at 323 Mt methane in 2005, with an expected increase to 414 Mt methane in 2030. The technical mitigation potential is estimated at 195 Mt methane in 2030, whereof about 80 percent is found attainable at a marginal cost less than 20 Euro t-1 CO2eq when using a social planner cost perspective. With a private investor cost perspective, the corresponding fraction is only 30 percent. Major uncertainty sources in emission estimates are identified and discussed.

Höglund-Isaksson, L.

2012-10-01

82

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...

83

Methane emissions from western Siberian wetlands: heterogeneity and sensitivity to climate change  

NASA Astrophysics Data System (ADS)

The prediction of methane emissions from high-latitude wetlands is important given concerns about their sensitivity to a warming climate. As a basis for the prediction of wetland methane emissions at regional scales, we coupled the variable infiltration capacity macroscale hydrological model (VIC) with the biosphere energy-transfer hydrology terrestrial ecosystem model (BETHY) and a wetland methane emissions model to make large-scale estimates of methane emissions as a function of soil temperature, water table depth, and net primary productivity (NPP), with a parameterization of the sub-grid heterogeneity of the water table depth based on TOPMODEL. We simulated the methane emissions from a 100 km × 100 km region of western Siberia surrounding the Bakchar Bog, for a retrospective baseline period of 1980 1999 and have evaluated their sensitivity to increases in temperature of 0 5 °C and increases in precipitation of 0 15%. The interactions of temperature and precipitation, through their effects on the water table depth, played an important role in determining methane emissions from these wetlands. The balance between these effects varied spatially, and their net effect depended in part on sub-grid topographic heterogeneity. Higher temperatures alone increased methane production in saturated areas, but caused those saturated areas to shrink in extent, resulting in a net reduction in methane emissions. Higher precipitation alone raised water tables and expanded the saturated area, resulting in a net increase in methane emissions. Combining a temperature increase of 3 °C and an increase of 10% in precipitation to represent climate conditions that may pertain in western Siberia at the end of this century resulted in roughly a doubling in annual emissions.

Bohn, T. J.; Lettenmaier, D. P.; Sathulur, K.; Bowling, L. C.; Podest, E.; McDonald, K. C.; Friborg, T.

2007-10-01

84

Response of methane emissions from wetlands to the Last Glacial Maximum and an idealized Dansgaard-Oeschger climate event: insights from two models of different complexity  

NASA Astrophysics Data System (ADS)

The role of different sources and sinks of CH4 in changes in atmospheric methane ([CH4]) concentration during the last 100 000 yr is still not fully understood. In particular, the magnitude of the change in wetland CH4 emissions at the last glacial maximum (LGM) relative to the pre-industrial period (PI) as well as during abrupt climatic warmings or Dansgaard-Oeschger events of the last glacial period, is largely unconstrained. In the present study, we aim to understand the uncertainties related to the parameterization of the wetland CH4 emissions models relevant to these time periods by using two wetland models of different complexity (SDGVM and ORCHIDEE). These models have been forced by identical climate fields from low resolution coupled atmosphere-ocean general circulation model (FAMOUS) simulations of these time periods. Both emissions models simulate a large decrease in emissions during LGM in comparison to PI consistent with ice core observations and previous modeling studies. The global reduction is much larger in ORCHIDEE than in SDGVM (respectively -67 and -46%), and whilst the differences can be partially explained by different model sensitivities to temperature (i.e. Q10 values), the major reason for spatial differences between the models, is the inclusion of freezing of soil water in ORCHIDEE and the resultant impact on methanogenesis substrate availability in boreal regions. Besides, a sensitivity test performed with ORCHIDEE in which the methanogenesis substrate sensitivity to the precipitations is modified to be more realistic gives a LGM reduction of -36%. The range of the global LGM decrease is still prone to uncertainty and here, we underline its sensitivity to different process parameterizations. Over the course of an idealized D-O warming, the magnitude of the change in wetland CH4 emissions simulated by the two models at global scale is very similar at around 15 Tg yr-1, but this is only around 25% of the ice-core measured changes in [CH4]. The two models do show regional differences in emissions sensitivity to climate with much larger magnitudes of Northern and Southern tropical anomalies in ORCHIDEE. However, the simulated Northern and Southern tropical anomalies partially compensate each other in both models limiting the net flux change. Future work may need to consider the inclusion of more detailed wetland processes (e.g. linked to permafrost or tropical floodplains), other non-wetland CH4 sources or different patterns of D-O climate change in order to be able to reconcile emissions estimates with the ice-core data for rapid CH4 events.

Ringeval, B.; Hopcroft, P. O.; Valdes, P. J.; Ciais, P.; Ramstein, G.; Dolman, A. J.; Kageyama, M.

2012-08-01

85

Response of methane emissions from wetlands to the Last Glacial Maximum and an idealized Dansgaard-Oeschger climate event: insights from two models of different complexity  

NASA Astrophysics Data System (ADS)

The role of different sources and sinks of CH4 in changes in atmospheric methane ([CH4]) concentration during the last 100 000 yr is still not fully understood. In particular, the magnitude of the change in wetland CH4 emissions at the Last Glacial Maximum (LGM) relative to the pre-industrial period (PI), as well as during abrupt climatic warming or Dansgaard-Oeschger (D-O) events of the last glacial period, is largely unconstrained. In the present study, we aim to understand the uncertainties related to the parameterization of the wetland CH4 emission models relevant to these time periods by using two wetland models of different complexity (SDGVM and ORCHIDEE). These models have been forced by identical climate fields from low-resolution coupled atmosphere-ocean general circulation model (FAMOUS) simulations of these time periods. Both emission models simulate a large decrease in emissions during LGM in comparison to PI consistent with ice core observations and previous modelling studies. The global reduction is much larger in ORCHIDEE than in SDGVM (respectively -67 and -46%), and whilst the differences can be partially explained by different model sensitivities to temperature, the major reason for spatial differences between the models is the inclusion of freezing of soil water in ORCHIDEE and the resultant impact on methanogenesis substrate availability in boreal regions. Besides, a sensitivity test performed with ORCHIDEE in which the methanogenesis substrate sensitivity to the precipitations is modified to be more realistic gives a LGM reduction of -36%. The range of the global LGM decrease is still prone to uncertainty, and here we underline its sensitivity to different process parameterizations. Over the course of an idealized D-O warming, the magnitude of the change in wetland CH4 emissions simulated by the two models at global scale is very similar at around 15 Tg yr-1, but this is only around 25% of the ice-core measured changes in [CH4]. The two models do show regional differences in emission sensitivity to climate with much larger magnitudes of northern and southern tropical anomalies in ORCHIDEE. However, the simulated northern and southern tropical anomalies partially compensate each other in both models limiting the net flux change. Future work may need to consider the inclusion of more detailed wetland processes (e.g. linked to permafrost or tropical floodplains), other non-wetland CH4 sources or different patterns of D-O climate change in order to be able to reconcile emission estimates with the ice-core data for rapid CH4 events.

Ringeval, B.; Hopcroft, P. O.; Valdes, P. J.; Ciais, P.; Ramstein, G.; Dolman, A. J.; Kageyama, M.

2013-01-01

86

Methane emissions in India: Sub-regional and sectoral trends  

NASA Astrophysics Data System (ADS)

This paper uses the 2006 IPCC Guidelines and latest country specific emission factors to estimate Indian methane emissions at sectoral and district level for the years 1990, 1995, 2005 and 2008. The estimates show that while methane emissions have increased steadily over past two decades, their share in India’s aggregate GHG emissions has declined from 31% in 1985 to 27% in 2008 mainly due to relatively higher growth CO2 emissions from the fossil fuels. The estimates for the year 2008 show that: i) agriculture sector, which employed two-thirds of India’s population and contributed 17% of GDP, accounted for 23% of India’s GHG emissions ii) 83% of country’s methane emissions are contributed by enteric fermentation, manure use and rice production, and iii) methane emissions from urban solid waste are steadily rising over the past two decades; their share in aggregate methane emissions has reached 8%. Resting on the disaggregated emissions estimates, the paper argues for using geographical and sectoral flexibilities to develop a roadmap for mitigation of methane emissions for India.

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

2011-09-01

87

Atmospheric Inverse Estimates of Methane Emissions from Central California  

SciTech Connect

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.

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

2008-11-21

88

Global Health Benefits from Reductions in Background Tropospheric Ozone due to Methane Emission Controls  

NASA Astrophysics Data System (ADS)

Increases in background ozone throughout the troposphere are partially attributed to rising anthropogenic methane concentrations, which are projected to continue to increase in the future. Because methane is long-lived and affects background ozone, controls on methane emissions would reduce surface ozone concentrations fairly uniformly around the globe. Epidemiological research indicates that exposure to ozone increases incidence of respiratory ailments and premature mortality. In addition, exposure to ozone reduces agricultural yields and damages natural ecosystems. We use the MOZART-2 global atmospheric chemistry and transport model to estimate the effects on global surface ozone of perturbations in methane emissions. We consider a baseline scenario for 2000 and the 2030 A2 scenario (emissions from the IPCC AR-4 2030 atmospheric chemistry experiments), and examine the impact on ozone of decreasing anthropogenic methane emissions relative to this baseline by 20%. Using the simulated spatially-distributed decreases in surface ozone concentrations resulting from these reductions in methane emissions, we estimate the global benefits to human health in the methane emission reduction scenario. We focus on human mortality, and consider the sensitivity of our estimates to different assumptions of health effect thresholds at low ozone concentrations.

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

2005-05-01

89

Modeling the Terrestrial Contribution to the Global Methane Balance  

NASA Astrophysics Data System (ADS)

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.

Smith, Amy Tetlow

90

LANDFILL OPERATION FOR CARBON SEQUESTRATION AND MAXIMUM METHANE EMISSION CONTROL  

SciTech Connect

''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.

Don Augenstein

1999-01-11

91

Three-dimensional model synthesis of the global methane cycle  

NASA Astrophysics Data System (ADS)

A synthesis of the global methane cycle is presented to attempt to generate an accurate global methane budget. Methane-flux measurements, energy data, and agricultural statistics are merged with databases of land-surface characteristics and anthropogenic activities. The sources and sinks of methane are estimated based on atmospheric methane composition and variations, and a global 3D transport model simulates the corresponding atmospheric responses. The geographic and seasonal variations of candidate budgets are compared with observational data, and the available observations are used to constrain the plausible methane budgets. The preferred budget includes annual destruction rates and annual emissions for various sources. The lack of direct flux measurements in the regions of many of these fluxes makes the unique determination of each term impossible. OH oxidation is found to be the largest single term, although more measurements of this and other terms are recommended.

Fung, I.; Prather, M.; John, J.; Lerner, J.; Matthews, E.

1991-07-01

92

Quantitative Evaluation of the Factors Controlling Methane and Nitrous Oxide Emissions From Rice Fields in China.  

NASA Astrophysics Data System (ADS)

Experiments have shown that a few factors control the emissions of methane from rice fields. Among the most significant factors are intermittent vs continuous flooding of the fields and the use of organic vs. nitrogen fertilizers. Continuous flooding and organic fertilizers result in the highest emissions of methane while intermittent flooding and use of nitrogen fertilizers produce very little methane emissions. Use of nitrogen fertilizers produces nitrous oxide which is also measured in the present experiments. Until now no systematic experiments have been carried out to determine the quantitative relationship between these variables and the emissions of methane, the interactions between these variables or the relationship between methane and nitrous oxide emissions. In our present research we have adopted classical factorial experimental design and a unique set of experiments under controlled greenhouse conditions with a mirror experiment in the field near Nanjing, China. We will report the progress of the experiment after the first year of experimental results. The experiments are designed using a model of the processes governing methane emissions from rice fields. The results therefore, will be used to obtain a more accurate estimate of emissions from rice fields in China and the rest of the world. This research was supported by the Office of Science (BER), US Department of Energy, Grant No. DE-FG02-04ER63913.

Xiong, Z.; Khalil, M. K.; Shearer, M. J.; Butenhoff, C. L.; Rasmussen, R. A.; Xu, L.

2005-12-01

93

Methane emissions from Earth’s degassing: Implications for Mars  

NASA Astrophysics Data System (ADS)

The presence of methane on Mars is of great interest, since one possibility for its origin is that it derives from living microbes. However, CH 4 in the martian atmosphere also could be attributable to geologic emissions released through pathways similar to those occurring on Earth. Using recent data on methane degassing of the Earth, we have estimated the relative terrestrial contributions of fossil geologic methane vs. modern methane from living methanogens, and have examined the significance that various geologic sources might have for Mars. Geologic degassing includes microbial methane (produced by ancient methanogens), thermogenic methane (from maturation of sedimentary organic matter), and subordinately geothermal and volcanic methane (mainly produced abiogenically). Our analysis suggests that ˜80% of the "natural" emission to the terrestrial atmosphere originates from modern microbial activity and ˜20% originates from geologic degassing, for a total CH 4 emission of ˜28.0×10 7 tonnes year -1. Estimates of methane emission on Mars range from 12.6×10 1 to 57.0×10 4 tonnes year -1 and are 3-6 orders of magnitude lower than that estimated for Earth. Nevertheless, the recently detected martian, Northern-Summer-2003 CH 4 plume could be compared with methane expulsion from large mud volcanoes or from the integrated emission of a few hundred gas seeps, such as many of those located in Europe, USA, Mid-East or Asia. Methane could also be released by diffuse microseepage from martian soil, even if macro-seeps or mud volcanoes were lacking or inactive. We calculated that a weak microseepage spread over a few tens of km 2, as frequently occurs on Earth, may be sufficient to generate the lower estimate of methane emission in the martian atmosphere. At least 65% of Earth's degassing is provided by kerogen thermogenesis. A similar process may exist on Mars, where kerogen might include abiogenic organics (delivered by meteorites and comets) and remnants of possible, past martian life. The remainder of terrestrial degassed methane is attributed to fossil microbial gas (˜25%) and geothermal-volcanic emissions (˜10%). Global abiogenic emissions from serpentinization are negligible on Earth, but, on Mars, individual seeps from serpentinization could be significant. Gas discharge from clathrate-permafrost destabilization should also be considered. Finally, we have shown examples of potential degassing pathways on Mars, including mud volcano-like structures, fault and fracture systems, and major volcanic edifices. All these types of structures could provide avenues for extensive gas expulsion, as on Earth. Future investigations of martian methane should be focused on such potential pathways.

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

2011-02-01

94

Annual Estimates of Global Anthropogenic Methane Emissions: 1860-1994  

NSDL National Science Digital Library

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

Stern, David I.; Kaufmann, Robert K.

1998-01-01

95

Development of atmospheric tracer methods to measure methane emissions from natural gas facilities and urban areas  

Microsoft Academic Search

A new, integrated methodology to locate and measure methane emissions from natural gas systems has been developed. Atmospheric methane sources are identified by elevated ambient CHâ concentrations meaured with a mobile laser-based methane analyzer. The total methane emission rate from a source is obtained by simulating the source with a sulfur hexafluoride (SFâ) tracer gas release and by measuring methane

Brian Lamb; E. Allwine; R. Siverson; H. Westberg; J. B. McManus; C. B. Kolb; J. H. Shorter; B. Mosher; D. Blaha; R. C. Harris; Robert Lott; Hal Westburg; Pat Zimmerman

1995-01-01

96

Indian methane and nitrous oxide emissions and mitigation flexibility  

Microsoft Academic Search

Methane (CH4) and nitrous oxide (N2O) contributed 27% and 7%, respectively, to India's CO2 equivalent greenhouse gas (GHG) emissions in 2000, the remaining being the carbon dioxide (CO2) emissions. Presently, agriculture and livestock related emissions contribute above 65% of Indian CH4 emissions and above 90% of N2O emissions. Since these activities are widely dispersed, with a considerable portion being sub-sustenance

Amit Garg; P. R. Shukla; Manmohan Kapshe; Deepa Menon

2004-01-01

97

Environmental factors controlling methane emissions for peatlands in Northern Minnesota  

SciTech Connect

Controls on methane emission from peatlands in northern Minnesota were investigated by correlation to environmental variables and by field manipulations. From September 1988 through September 1990, methane flux measurements were made at weekly to monthly intervals at six sites in the Marcell Experimental Forest, northern Minnesota (two open bog sites, two forested bog sites, a poor fen, and a fen lagg). Flux was related to water table position and peat temperature with simple correlations at individual sites and multiple regression on all sites together. The effect of water table was also investigated experimentally in {open_quotes}bog corrals{close_quotes} (open-ended metal enclosures set in the peat) in which water table was artificially raised to the surface in the driest peatland. Temperature largely controlled variation in flux within individual ecosystems at Marcell, but hydrology distinguished between-site variation. Water table position, peat temperature, and degree of peat humification explained 91% of the variance in log CH{sub 4} flux, predicted annual methane emission from individual wetlands successfully, 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 emission by 2.5x and 2.2x, respectively. Just as expanding the scale of investigation from a single habitat in a wetland to several wetlands necessitates incorporation of additional variables to explain flux (water table, peat characteristics), modeling flux from several wetland regions, if possible, will require the addition of climate parameters. 30 refs., 8 figs., 21 tabs.

Dise, N.B.; Gorham, E. [Univ. of Minnesota, Minneapolis, MN (United States); Verry, E.S. [Forest Service, Grand Rapids, MN (United States)

1993-06-20

98

Interannual variation of methane emissions in a boreal peatland - cross-evaluation of chamber measurements (7 years) and model results (LPJ-WHyMe)  

NASA Astrophysics Data System (ADS)

Boreal peatlands are a major natural source of methane (CH4). Due to a lack of longterm measurements, the interannual variability of CH4 emission is still uncertain. To fill this gap, a combination of measurements and models is necessary. Here, we present chamber measurements of 7 years from a boreal mire in Finland and compare them with the output of a methane model that is integrated into a dynamic global vegetation model (LPJ-WHyMe: Wania et al. 2010). The mire is characterized by three microsite types which vary in vegetation cover and hydrology (hummocks, lawns, flarks). Chamber measurements have been conducted on all three microsite types in 1993 (Saarnio et al. 1997) and 2005-2007 (Becker et al. 2008, Schäfer 2007, Forbrich et al., in prep.), while in 1996-1998 they have been conducted exclusively on lawns (Saarnio et al. 2000). When all microsite types were measured, we upscale these measurements using classified high-aerial photographs (Becker et al. 2008). Additionally, we analyze the time series of measurements on lawns, which represent the most dominant CH4 source in the peatland (contributing on average 80% to the ecosystem flux: Forbrich et al., in prep.). LPJ-WHyMe has been applied for the grid cell containing the peatland for the years 1988-2008 using the settings of Wania et al. (2010). The upscaled chamber measurements (ecosystem flux estimate) for 1993 and 2005-2007 are generally lower than the model estimates (7-52%). Reasons for the mismatch can be both caused by the measurements and the model: Chamber measurements do miss ebullition fluxes (contributing 68.2% to the modelled annual emission: Wania et al. 2010) and/or the linear flux calculation underestimates the actual flux (Forbrich et al. 2010) while LPJ-WHyMe tends to overestimate the available carbon pool (Wania et al. 2009). Absolute values of observations of lawns in 1993 are well matched by model results (Wania et al. 2010). However, for the other years the model output is substantially larger than the measured fluxes (54-89%). This mismatch is decreasing when ebullition fluxes are neglected. To analyze this mismatch we will conduct an uncertainty analysis of the upscaling procedure of measurements and test different parameter settings. The interannual variability of measured CH4 fluxes can best be explained by the varying hydrology (Schäfer 2007): When the water table is low during the growing season, the measured fluxes decrease while they follow a seasonal curve when the water table is relatively stable over time. This is not exactly matched by LPJ-WHyMe, although generally the modelled mean water table matches very well the measured mean water table of lawns. Only the modelled diffusion fluxes seem to be affected by the water table position, while modelled emissions due to plant-mediated transport stay relatively stable for the investigated years. Modelled ebullition fluxes show a high variability: The amount of days when ebullition fluxes are modelled to take place range from 89 (2006) to 141 (2005 and 2007). References: Becker et al. 2008, Biogeosciences, 5:1387-1393 Forbrich et al., 2010, Soil Biology and Biochemistry, in press Saarnio et al. 1997, Oecologia, 110:414-422 Saarnio et al. 2000, Global Change Biology, 6: 137-144 Schäfer 2007, diploma thesis, University of Greifswald Wania et al. 2009, Global Biogeochemical Cycles, 23, 3, doi:10.1029/2008GB003413 Wania et al. 2010, Geoscientific Model Development Discussions, 3:1-59

Forbrich, Inke; Wania, Rita; Saarnio, Sanna; Schäfer, Carolyn; Kutzbach, Lars; Wilmking, Martin

2010-05-01

99

Measured and modelled estimates of nitrous oxide emission and methane consumption from a sheep-grazed pasture  

Microsoft Academic Search

Sheep grazing, one of the major land-uses in New Zealand occupies 7.1 million hectares and provides forage for about 40 million sheep. Spatially and temporally explicit data on nitrous oxide (N2O) and methane (CH4) fluxes from soils under this land use are needed at farm-scale to better estimate regional and national greenhouse gas inventories. In this study, we measured N2O

S. Saggar; C. B. Hedley; D. L. Giltrap; S. M. Lambie

2007-01-01

100

An Assessment of the Use of Inventories in Determining Global Anthropogenic Methane and Nitrous Oxide Emissions  

Microsoft Academic Search

According to the IPCC's Special Report on Emission Scenarios (SRES), methane and nitrous oxide are estimated to represent 26% of global greenhouse gas emissions. This estimate was determined using top down models from six scientific groups and standardizing the results. Global estimates may also be determined using bottom-up methods, including the compilation of country specific inventories. This paper compares the

E. A. Scheehle; W. N. Irving; D. Kruger

101

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

NASA Astrophysics Data System (ADS)

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.

Sanderson, M. G.

1996-12-01

102

Methane emissions from the Orinoco River floodplain, Venezuela  

Microsoft Academic Search

Methane emissions were measured over a 17-month interval at 21 locations on the Orinoco fringing floodplain and upper delta (total area, 14,000 km 2). Emissions totaled 0.17 Tg yr 1, or 7.1 mmol d 1 (114 mg d 1; standard deviation,18%) per m2 of water surface. Ebullition accounted for 65% of emissions. Emission rates were about five times as high

LESLEY K. SMITH; WILLIAM M. LEWIS; JEFFREY P. CHANTON; GREG CRONIN; STEPHEN K. HAMILTON

2000-01-01

103

Quantification of methane emission from bacterial mat sites at Quepos Slide offshore Costa Rica  

NASA Astrophysics Data System (ADS)

Seafloor methane emission from the Quepos Slide on the submarine segment of the Costa Rica fore-arc margin was estimated by extrapolating flux measurements from individual seeps to the total area covered by bacterial mats. This approach is based on the combination of detailed mapping to determine the abundance of seeps and the application of a numerical model to estimate the amount of benthic methane fluxes. Model results suggest that the majority of the studied seeps transport rather limited amount of methane (on average: ~177 ?mol cm-2 a-1) into the water column due to moderate upward advection, allowing for intense anaerobic oxidation of methane (AOM; on average: 53 % of the methane flux is consumed). Depth-integrated AOM rates (56-1,538 ?mol CH4 cm-2 a-1) are comparable with values reported from other active seep sites. The overall amount of dissolved methane released into the water column from the entire area covered by bacterial mats on the Quepos Slide is estimated to be about 0.28 × 106 mol a-1. This conservative estimate which relies on rather accurate determinations of seafloor methane fluxes emphasizes the potential importance of submarine slides as sites of natural methane seepage; however, at present the global extent of methane seepage from submarine slides is largely unknown.

Karaca, Deniz; Schleicher, Tina; Hensen, Christian; Linke, Peter; Wallmann, Klaus

2012-12-01

104

Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions  

USGS Publications Warehouse

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.

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

2011-01-01

105

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 ...

106

Methane emissions from fen, bog and swamp peatlands in Quebec  

Microsoft Academic Search

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

T. R. Moore; R. Knowles

1990-01-01

107

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...

108

Methane emissions measured directly from grazing livestock in New Zealand  

Microsoft Academic Search

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

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

1997-01-01

109

Biofiltration for Mitigation of Methane Emission from Animal Husbandry  

Microsoft Academic Search

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

Roland W. Melse; Werf van der A. W

2005-01-01

110

Quantification of Methane Source Locations and Emissions in AN Urban Setting  

NASA Astrophysics Data System (ADS)

The regulation of methane emissions from urban sources such as landfills and waste-water treatment facilities is currently a highly debated topic in the US and in Europe. This interest is fueled, in part, by recent measurements indicating that urban emissions are a significant source of Methane (CH4) and in fact may be substantially higher than current inventory estimates(1). As a result, developing methods for locating and quantifying emissions from urban methane sources is of great interest to industries such as landfill and wastewater treatment facility owners, watchdog groups, and the governmental agencies seeking to evaluate or enforce regulations. In an attempt to identify major methane source locations and emissions in Boston, Indianapolis, and the Bay Area, systematic measurements of CH4 concentrations and meteorology data were made at street level using a vehicle mounted cavity ringdown analyzer. A number of discrete sources were detected at concentration levels in excess of 15 times background levels. Using Gaussian plume models as well as tomographic techniques, methane source locations and emission rates will be presented. In addition, flux chamber measurements of discrete sources such as those found in natural gas leaks will also be presented. (1) Wunch, D., P.O. Wennberg, G.C. Toon, G. Keppel-Aleks, and Y.G. Yavin, Emissions of Greenhouse Gases from a North American Megacity, Geophysical Research Letters, Vol. 36, L15810, doi:10.1029/2009GL)39825, 2009.

Crosson, E.; Richardson, S.; Tan, S. M.; Whetstone, J.; Bova, T.; Prasad, K. R.; Davis, K. J.; Phillips, N. G.; Turnbull, J. C.; Shepson, P. B.; Cambaliza, M. L.

2011-12-01

111

The influence of atmospheric pressure on landfill methane emissions  

SciTech Connect

Landfills are the largest source of anthropogenic methane (CH{sub 4}) emissions to the atmosphere in the United States. However, few measurements of whole landfill CH{sub 4} emissions have been reported. Here, we present the results of a multi-season study of whole landfill CH{sub 4} emissions using atmospheric tracer methods at the Nashua, New Hampshire Municipal landfill in the northeastern United States. The measurement data include 12 individual emission tests, each test consisting of 5-8 plume measurements. Measured emissions were negatively correlated with surface atmospheric pressure and ranged from 7.3 to 26.5 m{sup 3} CH{sub 4} min{sup -1}. A simple regression model of our results was used to calculate an annual emission rate of 8.4x10{sup 6} m{sup 3} CH{sub 4} year{sup -1}. These data, along with CH{sub 4} oxidation estimates based on emitted landfill gas isotopic characteristics and gas collection data, were used to estimate annual CH{sub 4} generation at this landfill. A reported gas collection rate of 7.1x10{sup 6} m{sup 3} CH{sub 4} year{sup -1} and an estimated annual rate of CH{sub 4} oxidation by cover soils of 1.2x10{sup 6} m{sup 3} CH{sub 4} year{sup -1} resulted in a calculated annual CH{sub 4} generation rate of 16.7x10{sup 6} m{sup 3} CH{sub 4} year{sup -1}. These results underscore the necessity of understanding a landfill's dynamic environment before assessing long-term emissions potential.

Czepiel, P.M.; Shorter, J.H.; Mosher, B.; Allwine, E.; McManus, J.B.; Harriss, R.C.; Kolb, C.E.; Lamb, B.K

2003-07-01

112

Estimate of methane emissions from the U.S. natural gas industry  

Microsoft Academic Search

Global methane emissions 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 result, the estimate of the contribution these emissions make to the global methane inventory could

David A. Kirchgessner; Robert A. Lott; R. Michael Cowgill; Matthew R. Harrison; Theresa M. Shires

1997-01-01

113

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

Microsoft Academic Search

An emission inventory of non-methane volatile organic compounds (NMVOCs) from anthropogenic sources in China was compiled for the year 2005. The NMVOC emissions were 20.1Tg, of which industrial and domestic solvent use, road transportation, and bio-fuel combustion contributed 28.6%, 23.4%, and 18.0%, respectively. Emissions were speciated into 40 species according to their atmospheric photochemical reactivity, toxicity, and model applicability. Of

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

2008-01-01

114

Methane emissions from lakes: Dependence of lake characteristics, two regional assessments, and a global estimate  

Microsoft Academic Search

Lake sediments are “hot spots” of methane production in the landscape. However, regional and global lake methane emissions, contributing to the greenhouse effect, are poorly known. We developed predictions of methane emissions from easily measured lake characteristics based on measurements for 11 North American and 13 Swedish lakes, and literature values from 49 lakes. Results suggest that open water methane

David Bastviken; Jonathan Cole; Michael Pace; Lars Tranvik

2004-01-01

115

Methane emissions from lakes: Dependence of lake characteristics, two regional assessments, and a global estimate  

Microsoft Academic Search

Lake sediments are ``hot spots'' of methane production in the landscape. However, regional and global lake methane emissions, contributing to the greenhouse effect, are poorly known. We developed predictions of methane emissions from easily measured lake characteristics based on measurements for 11 North American and 13 Swedish lakes, and literature values from 49 lakes. Results suggest that open water methane

David Bastviken; Jonathan Cole; Michael Pace; Lars Tranvik

2004-01-01

116

Reducing Open Cell Landfill Methane Emissions with a Bioactive Alternative Daily  

Microsoft Academic Search

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

Helene Hilger; James Oliver; Jean Bogner; David Jones

2009-01-01

117

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

NASA Astrophysics Data System (ADS)

Circumpolar peatlands store roughly 18 % of the globally stored carbon in soils [based on 1, 2]. Also, northern wetlands and tundra are a net source of methane (CH4), an effective greenhouse gas (GHG), with an estimated annual CH4 release of 7.2% [3] or 8.1% [4] of the global total CH4 emission. Although it is definite that Arctic tundra significantly contributes to the global methane emissions in general, regional variations in GHG fluxes are enormous. CH4 fluxes of polygonal tundra within the Siberian Lena Delta, for example, were reported to be low [5, 6], particularly at open water polygonal ponds and small lakes [7] which make up around 10 % of the delta's surface. Low methane emissions from polygonal ponds oppose that Arctic permafrost thaw ponds are generally known to emit large amounts of CH4 [8]. Combining tools of biogeochemistry and molecular microbiology, we identified sinks of CH4 in polygonal ponds from the Lena Delta that were not considered so far in GHG studies from Arctic wetlands. Pore water CH4 profiling in polygonal ponds on Samoylov, a small island in the central part of the Lena Delta, revealed a pronounced zone of CH4 oxidation near the vegetation surface in submerged layers of brown-mosses. Here, potential CH4 oxidation was an order of magnitude higher than in non-submerged mosses and in adjacent bulk soil. We could additionally show that this moss associated methane oxidation (MAMO) is hampered when exposure of light is prevented. Shading of plots with submerged Scorpidium scorpioides inhibited MAMO leading to higher CH4 concentrations and an increase in CH4 fluxes by a factor of ~13. Compared to non-submerged mosses, the submerged mosses also showed significantly lower ?13C values indicating that they use carbon dioxide derived from methane oxidation for photosynthesis. Applying stable isotope probing of DNA, type II methanotrophs were identified to be responsible for the oxidation of CH4 in the submerged Scorpidium scorpioides. Our study gives first evidence for MAMO in submerged brown-mosses and in the oligotrophic polygonal peatlands of the Lena Delta. It shows that MAMO might effectively reduce methane fluxes to the atmosphere also in Arctic GHG emission hot spots. References: [1] Zhang, T., Barry, R.G., Knowles, K., Heginbottom, J.A., and Brown, J. (1999) Statistics and characteristics of permafrost and ground-ice distribution in the Northern Hemisphere. Polar Geography 23(2): 132-154 [2] Schuur, E.A.G., Bockheim, J., Candell, J.G., Euskirchen, E., Field, C.B., Goryachkin, S.V., Hagemann, S., Kuhry, P., Lafleur, P.M., Lee, H., Mazhitova, G., Nelson, F.E., Rinke, A., Romanovsky, V., Shiklomanov, N., Tarnocai, C., Venevsky, S., Vogel, J., and Zimov, S. (2008) Vulnerability of Permafrost Carbon to Climate Change: Implications for the Global Carbon Cycle. BioScience 58 (8): 701-714 [3] Denman, K.L., Brasseur G., Chidthaisong A., Ciais, P., Cox, P.M., Dickinson, R.E., Hauglustaine, D., Heinze, C., Holland, E., Jacob, D., Lohmann, U., Ramachandran, S., da Silva Dias, P.L., Wofsy, S.C., and Zhang, X. (2007) 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 [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA [4] Wuebbles, J., and Hayhoe, K. (2002) Atmospheric methane and global change. Earth-Science Reviews 57: 177-210 [5] Sachs, T., Wille, C., Boike, J., and Kutzbach, L. (2008) Environmental controls on ecosystem-scale CH4 emission from polygonal tundra in the Lena River Delta, Siberia. Journal of Geophysical Research 113: G00A03 [6] Wille, C., Kutzbach, L., Sachs, T., Wagner, D., and Pfeiffer, E.M. (2008) Methane emissions from Siberian arctic polygonal tundra: Eddy covariance measurements and modeling. Global Change Biology 14: 1395-1408 [7] Schneider, J., Grosse, G., and Wagner, D. (2009

Liebner, Susanne; Zeyer, Josef; Knoblauch, Christian

2010-05-01

118

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

PubMed

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

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

2013-09-29

119

Carbon dioxide and methane emissions from the Yukon River system  

NASA Astrophysics Data System (ADS)

Carbon dioxide (CO2) and methane (CH4) emissions are important, but poorly quantified, components of riverine carbon (C) budgets. This is largely because the data needed for gas flux calculations are sparse and are spatially and temporally variable. Additionally, the importance of C gas emissions relative to lateral C exports is not well known because gaseous and aqueous fluxes are not commonly measured on the same rivers. We couple measurements of aqueous CO2 and CH4 partial pressures (pCO2, pCH4) and flux across the water-air interface with gas transfer models to calculate subbasin distributions of gas flux density. We then combine those flux densities with remote and direct observations of stream and river water surface area and ice duration, to calculate C gas emissions from flowing waters throughout the Yukon River basin. CO2 emissions were 7.68 Tg C yr-1 (95% CI: 5.84 -10.46), averaging 750 g C m-2 yr-1 normalized to water surface area, and 9.0 g C m-2 yr-1 normalized to river basin area. River CH4 emissions totaled 55 Gg C yr-1 or 0.7% of the total mass of C emitted as CO2 plus CH4 and ˜6.4% of their combined radiative forcing. When combined with lateral inorganic plus organic C exports to below head of tide, C gas emissions comprised 50% of total C exported by the Yukon River and its tributaries. River CO2 and CH4 derive from multiple sources, including groundwater, surface water runoff, carbonate equilibrium reactions, and benthic and water column microbial processing of organic C. The exact role of each of these processes is not yet quantified in the overall river C budget.

Striegl, Robert G.; Dornblaser, M. M.; McDonald, C. P.; Rover, J. R.; Stets, E. G.

2012-12-01

120

Assessment of coal methane emission in Kuzbas  

Microsoft Academic Search

The paper gives an environmental-economic measures of the efficiency in extraction and utilization of coal methane of the Kuznetsk basin with consideration of basic notions underlying the Kyoto protocol and the Marrakesh treaty. The efficiency is estimated in three directions: for replacement of the natural gas exported to the EC and APR countries; for production of electric and thermal power

N. M. Zhuravel

2005-01-01

121

Effect of climatic variability from 1980 to 1997 on simulated methane emission from a boreal mixed mire in northern Sweden  

NASA Astrophysics Data System (ADS)

The objective of this study was to evaluate the interannual variation during 1981-1997 in methane emission from an oligotrophic lawn plant community in a boreal mire. Daily mean air temperatures and daily accumulated precipitation figures were used as forcing variables for a mechanistic soil physical model, to generate estimates for the depths of snow, soil frost, and water table, together with soil temperature profiles. Methane emissions were then simulated with a mechanistic mixed mire methane model, described in this paper. The methane model simulated total methane emission rates separated into diffusion, ebullition, and plant-mediated transport. The climate record for 1981-1997 represented almost the total range in growing season temperature sums in northern Sweden during the twentieth century. The average temperature sum for 1980-1997 was 735 (range 553-981) degree days. The average accumulated annual precipitation during the same period was 283 (range 140-397) mm. The integrated simulated annual methane emission during 1981-1997 varied almost threefold among years, with a mean of 17.4 ±1.1 (SE) and a range of 11 to 27 g m-2. The simulated annual emissions for the three calibration years 1995-1997 were 18, 14, and 22 g m-2, respectively, slightly higher than the integrated measured emissions over the growing season (May-September), which were 16, 13, and 18 g m-2 y-1, respectively. Given the model formulation and parameterization, the single most important climatic predictor of simulated annual methane emission was mean water table position (r2 = 0.58). Adding annual soil temperature sum at 26 cm in a multiple regression solution significantly increased the explained variance (R2 = 0.85). The study emphasizes that interannual variability in methane emission may be large, and therefore extrapolations of annual methane emissions must be based on time series that adequately span the interannual variability in the local climate.

Granberg, Gunnar; Ottosson-LöFvenius, Mikaell; Grip, Harald; Sundh, Ingvar; Nilsson, Mats

2001-12-01

122

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

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

123

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...

124

Methane Emissions from Alaska Arctic Tundra in Response to Climatic Change.  

National Technical Information Service (NTIS)

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 env...

G. P. Livingston L. A. Morrissey

1992-01-01

125

Global Methane Emissions Program for Landfills, Coal Mines, and Natural Gas Systems.  

National Technical Information Service (NTIS)

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 ma...

L. L. Beck

1993-01-01

126

Indian oil company joins efforts to reduce methane emissions  

NASA Astrophysics Data System (ADS)

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

Kumar, Mohi

127

Methane emissions from a high arctic valley: findings and challenges  

NASA Astrophysics Data System (ADS)

Wet tundra ecosystems are well-known to be a significant source of atmospheric methane. With the predicted stronger effect of global climate change on arctic terrestrial ecosystems compared to lower-latitudes, there is a special obligation to study the natural diversity and the range of possible feedback effects on global climate that could arise from Arctic tundra ecosystems. One of the prime candidates for such a feedback mechanism is a potential change in the emissions of methane. Long-term datasets on methane emissions from high arctic sites are almost non-existing but badly needed for analyses of controls on interannual and seasonal variations in emissions. To help fill this gap we initiated a measurement program in a productive high arctic fen in the Zackenberg valley, NE Greenland. Methane flux measurements have been carried out at the same location since 1997. Compared with the manual chamber measurements from the late 1990s, however, an automatic chambers system with laser off- axis integrated-cavity output spectroscopy analyzer, in place since 2005, dramatically increased the time resolution of more recent data. The latest data brought up some intriguing findings on seasonal variations in methane fluxes which will be presented and discussed.

Mastepanov, M.; Sigsgaard, C.; Ström, L.; Tagesson, T.; Tamstorf, M.; Christensen, T. R.

2008-12-01

128

Effect of chemical treatments on methane emission by the hindgut microbiota in the termite Zootermopsis angusticollis  

Microsoft Academic Search

Selective removal of symbiotic hindgut microorganisms by chemical treatments reduced methane emission by the termiteZootermopsis angusticollis. Methane emission from untreated termites incubated in 25% H2 increased 123%, from 10.3 nmol\\/termite\\/hour (U) to 22.9 U. Though linear with time, methane emission was not correlated with termite mass. Hyperbaric oxygen treatments reduced methane emission to unquantifiable levels and eliminated all but the

Adam Catton Messer; Monica J. Lee

1989-01-01

129

Methane emissions from feedlot cattle fed barley or corn diets.  

PubMed

Methane emitted from the livestock sector contributes to greenhouse gas emissions worldwide. Understanding the variability in enteric methane production related to diet is essential to decreasing uncertainty in greenhouse gas emission inventories and to identifying viable greenhouse gas reduction strategies. Our study focused on measuring methane in growing beef cattle fed corn- or barley-based diets typical of those fed to cattle in North American feedlots. The experiment was designed as a randomized complete block (group) design with two treatments, barley and corn. Angus heifer calves (initial BW = 328 kg) were allocated to two groups (eight per group), with four cattle in each group fed a corn or barley diet. The experiment was conducted over a 42-d backgrounding phase, a 35-d transition phase and a 32-d finishing phase. Backgrounding diets consisted of 70% barley silage or corn silage and 30% concentrate containing steam-rolled barley or dry-rolled corn (DM basis). Finishing diets consisted of 9% barley silage and 91% concentrate containing barley or corn (DM basis). All diets contained monensin (33 mg/kg of DM). Cattle were placed into four large environmental chambers (two heifers per chamber) during each phase to measure enteric methane production for 3 d. During the backgrounding phase, DMI was greater by cattle fed corn than for those fed barley (10.2 vs. 7.6 kg/d, P < 0.01), but during the finishing phase, DMI was similar for both diets (8.3 kg/d). The DMI was decreased to 6.3 kg/d with no effect of diet or phase while the cattle were in the chambers; thus, methane emissions (g/d) reported may underestimate those of the feedlot industry. Methane emissions per kilogram of DMI and as a percentage of GE intake were not affected by grain source during the backgrounding phase (24.6 g/kg of DMI; 7.42% of GE), but were less (P < 0.05) for corn than for barley during the finishing phase (9.2 vs. 13.1 g/kg of DMI; 2.81 vs. 4.03% of GE). The results indicate the need to implement dietary strategies to decrease methane emissions of cattle fed high-forage backgrounding diets and barley-based finishing diets. Mitigating methane losses from cattle will have long-term environmental benefits by decreasing agriculture's contribution to greenhouse gas emissions. PMID:15705762

Beauchemin, K A; McGinn, S M

2005-03-01

130

Effect of water management on methane emission from a Japanese rice paddy field: Automated methane monitoring  

Microsoft Academic Search

The effect of differing water management schemes on the emission of methane (CH4) from rice paddies to the atmosphere was studied in a Japanese paddy field. Using an automated sampling and analyzing system, the test site was divided into two plots: a continuously flooded plot which was maintained flooded by constant irrigation from May to August, and an intermittently drained

Kazuyuki Yagi; Haruo Tsuruta; Ken-ichi Kanda; Katsuyuki Minami

1996-01-01

131

Environmental impact of coal mine methane emissions and responding strategies in China  

Microsoft Academic Search

The impact on global climate change from coal mine methane emissions in China has been drawing attention as coal production has powered its economic development. Data on coal mine methane emissions from the State Administration of Coal Mine Safety of China has been analyzed. It is estimated that the methane emission from coal mining in China reached 20 billions of

Yuan-Ping Cheng; Lei Wang; Xiao-Lei Zhang

2011-01-01

132

Open Path Tracer Measurements of Methane Emissions from Free Ranging Cattle  

Microsoft Academic Search

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

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

2006-01-01

133

LANDFILL OPERATION FOR CARBON SEQUESTRATION AND MAXIMUM METHANE EMISSION CONTROL  

SciTech Connect

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.

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

2000-02-26

134

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

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

135

Energetic and Methane Emission Reduction Potentials from an Unsanitary Landfill  

Microsoft Academic Search

Al Akeeder is the largest landfill site in northern Jordan. The site operation started in 1981 by open dumping and combusting then converted to unsanitary landfilling (without biogas and leachate management). The objective of this article is to estimate the energy and methane emission reduction potentials of the landfill. The amount and composition of the landfill gas were estimated by

H. A. Abu Qdais; A. M. Maqableh; L. M. Al Nawayseh; N. M. Al Jamal

2011-01-01

136

Seasonal Cycles of Wetland Methane Emissions: Inferences from the Temperature and Saturation Dependencies of Methanogens and Methanotrophs  

NASA Astrophysics Data System (ADS)

A model predicting wetland extent has been developed for the Simple Biosphere Model, improving model estimates of heat fluxes at a site in northern Wisconsin compared to observations. The model also provides a framework for estimation of methane emissions at the site. Inspection of the regional climatology and the equations commonly used to represent microbial respiration, Arrhenius-type equations and Michaelis-Menten kinetics, implies a seasonal cycle of methane production during the summertime/wet-season and methane uptake during the spring and fall. This pattern is seen in modeled emissions and may be observed in local measurements. Thus a simple framework may be useful in understanding the transition between methane emission and consumption in a temperate/boreal wetland forest.

Kraus, P. M.; Denning, A.

2011-12-01

137

Global Methane Emissions From Wetlands, Rice Paddies, and Lakes  

NASA Astrophysics Data System (ADS)

The current concentration of atmospheric methane is 1774+/-1.8 parts per billion, and it accounts for 18% of total greenhouse gas radiative forcing [Forster et al., 2007]. Atmospheric methane is 22 times more effective, on a per-unit-mass basis, than carbon dioxide in absorbing long-wave radiation on a 100-year time horizon, and it plays an important role in atmospheric ozone chemistry (e.g., in the presence of nitrous oxides, tropospheric methane oxidation will lead to the formation of ozone). Wetlands are a large source of atmospheric methane, Arctic lakes have recently been recognized as a major source [e.g., Walter et al., 2006], and anthropogenic activities-such as rice agriculture-also make a considerable contribution. However, the quantification of methane emissions still has large uncertainties. In this article, we identify some causes for the uncertainty; illustrate the challenges of reducing the uncertainty; and highlight opportunities for research from the global perspective and also from the perspective of three principal sources of methane: the Arctic, the Amazon basin, and rice paddies.

Zhuang, Qianlai; Melack, John M.; Zimov, Sergey; Walter, Katey M.; Butenhoff, Christopher L.; Khalil, M. Aslam K.

2009-02-01

138

Implementation and evaluation of a new methane model within a dynamic global vegetation model: LPJ-WHyMe v1.3  

NASA Astrophysics Data System (ADS)

For the first time, a model that simulates methane emissions from northern peatlands is incorporated directly into a dynamic global vegetation model. The model, LPJ-WHyMe (LPJ-Wetland Hydrology and Methane), was previously modified in order to simulate peatland hydrology, permafrost dynamics and peatland vegetation. LPJ-WHyMe simulates methane emissions using a mechanistic approach, although the use of some empirical relationships and parameters is unavoidable. The model simulates methane production, three pathways of methane transport (diffusion, plant-mediated transport and ebullition) and methane oxidation. Two sensitivity tests were conducted, first to identify the most important factors influencing methane emissions and secondly to justify the choice of parameters. A comparison of model results to observations from seven sites revealed in general good agreement but also highlighted some problems. Circumpolar methane emissions for the period 1961-1990 were estimated to be between 40.8 and 73.7 Tg CH4 a-1.

Wania, R.; Ross, I.; Prentice, I. C.

2010-01-01

139

Measurement and prediction of enteric methane emission  

Microsoft Academic Search

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

Veerasamy Sejian; Rattan Lal; Jeffrey Lakritz; Thaddeus Ezeji

2011-01-01

140

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

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

141

Landfill methane emissions measured by enclosure and atmospheric tracer methods  

NASA Astrophysics Data System (ADS)

Methane (CH4) emissions were measured from the Nashua, New Hampshire municipal landfill using static enclosure and atmospheric tracer methods. The spatial variability of emissions was also examined using geostatistical methods. One hundred and thirty nine enclosure measurements were performed on a regular grid pattern over the emitting surface of the landfill resulting in an estimate of whole landfill emissions of 15,800 L CH4 min-1. Omnidirectional variograms displayed spatial correlation among CH4 fluxes below a separation distance of 7 m. Eleven tracer tests, using sulfur hexafluoride (SF6) as a tracer gas, resulted in a mean emissions estimate of 17,750 L CH4 min-1. The favorable agreement between the emission estimates was further refined using the observed relationship between atmospheric pressure and CH4 flux. This resulted in a pressure-corrected tracer flux estimate of whole landfill emissions of 16,740 L CH4 min-1.

Czepiel, P. M.; Mosher, B.; Harriss, R. C.; Shorter, J. H.; McManus, J. B.; Kolb, C. E.; Allwine, E.; Lamb, B. K.

1996-07-01

142

Recent findings on methane emissions from vegetation (Invited)  

NASA Astrophysics Data System (ADS)

Three years ago, Keppler et al. (2006) reported from laboratory experiments that living plants, plant litter and the structural plant component pectin emit methane to the atmosphere under aerobic conditions. These observations caused considerable controversy amongst the scientific community and the general public because of their far-reaching implications for two main reasons. Firstly, it is generally accepted knowledge that the reduced compound methane can only be produced naturally from organic matter by methanogens in the absence of oxygen, or at high temperatures, e.g. in biomass burning. The fact that no mechanism for ‘aerobic’ production of methane had been identified at the molecular level in plants added to the consternation. Secondly, the first extrapolations from laboratory measurements to the global scale indicated that these emissions could constitute a substantial fraction of the total global emissions of methane. After publication of the findings of Keppler et al. (2006), their extrapolation procedure employed was severely criticised, and other up-scaling calculations suggested much lower methane emissions. However, it became clear, that without further insight into the mechanism of the ‘aerobic’ production of methane, any up-scaling approach would have considerable uncertainties and thus be of questionable value. Whilst several subsequent studies (e.g. Dueck et al., 2007, Nisbet et al., 2009) could not confirm the original findings of Keppler et al. (2006) others (e.g. McLeod et al., 2008) including stable isotope studies (e.g. Vigano et al., 2009) verified methane formation from both dead plant tissues and living intact plants (Brüggemann et al. 2009).Therefore, the principle scientific questions are now: if, by how much, and by what mechanisms is methane emitted from dead plant matter and living vegetation. An overview of the current state of knowledge and the most recent findings will be presented. References: Brüggemann N, et al. (2009) New Phytologist, 23, 912-918. Dueck TA, et al. (2007). New Phytologist, 175, 29-35. Keppler F, et al. (2006). Nature 439, 187-191. McLeod AR, et al. (2008). New Phytologist, 180, 124-132. Nisbet RER, et al. (2009). Proc. R. Soc. B, 276, 1347-1354. Vigano I, et al. (2009). Atmospheric Environment, in press.

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

2009-12-01

143

Estimation of methane and nitrous oxide emissions from Indian livestock.  

PubMed

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

Patra, Amlan K

2012-08-17

144

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

NASA Astrophysics Data System (ADS)

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.

Pikaleva, A.

2012-04-01

145

Determination of Methane Emissions by Region and Generating Process Using Inverse Methods  

NASA Astrophysics Data System (ADS)

Methane is a chemically and radiatively important trace gas with a wide range of geographically and temporally varying biogenic and anthropogenic sources and sinks. A powerful method for determining the net methane fluxes due to these sources and sinks involves solution of an inverse problem in which the observed concentrations are effectively lagrangian line integrals and the unknown fluxes are contained in the integrands. The general method calculates optimal estimates in the Bayesian sense using an eulerian or lagrangian atmospheric transport model and global atmospheric methane measurements. We review the results of previous studies of regional and global methane fluxes using these methods. We also present the results of a recently completed study using a Kalman filter and the global 3D Model for Atmospheric Transport and Chemistry (MATCH) driven by NCEP analysed observed meteorology at T62 (1.8o x 1.8o) resolution. Monthly fluxes are optimally estimated for three large wetland/bog regions, rice agriculture (globally aggregated), and three large biomass burning regions. The study uses AGAGE, CMDL and other methane observations for 1996-2001 and also estimates average annual emissions from coal, gas, animals and waste sites. Deduced seasonal cycles for the biogenic sources (including rice) are qualitatively similar to prior estimates from site measurements but show differences in peak amplitudes and phases and significant year-to-year variability. Emissions from rice-growing regions are greater than prior estimates, while emissions from fossil sources are less. Enhanced emissions from northern wetland/bog regions are inferred to be the dominant contributor to the large 1998 increases in methane.

Prinn, P. G.

2004-12-01

146

Revisiting factors controlling methane emissions from high-arctic tundra  

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

147

The singular value decomposition method applied to the deduction of the emissions and the isotopic composition of atmospheric methane  

NASA Astrophysics Data System (ADS)

The determination of the methane emissions distribution from observations of the surface concentration and isotopic composition of atmospheric methane is studied using geophysical inverse methods and a chemical transport model of the atmosphere. First, the latitudinal and temporal distribution of methane emissions is estimated using the observations of the atmospheric concentration of methane at the Earth's surface and the truncated singular value decomposition (TSVD) as a solution technique. The singular value decomposition (SVD) analysis of this inverse methane source problem identifies the spatial and temporal components of the methane emissions distribution resolvable by the observations, quantifies the sensitivity of each component to errors in the observations, and predicts how many components must be retained to produce a modeled surface concentration consistent with the observations. A latitudinal and temporal distribution of the methane emissions distribution is estimated using the truncated singular value decomposition as a solution technique. The sensitivity of this emissions estimate to perturbations in the model parameters is investigated. The SVD analysis is then applied to the deduction of the 13CH4/12CH4 isotopic ratio of the methane emissions from observations of this ratio at the Earth's surface. This analysis identifies the spatial and temporal components of the isotopic ratio of the methane emissions distribution resolvable by the observations, quantifies the sensitivity of each component to errors in the observations, and predicts how many components must be retained to produce a modeled isotopic composition of atmospheric methane consistent with observations. The results show that the solution is sensitive to errors in the observations, with this sensitivity being dominated by errors in the observed atmospheric concentration rather than errors in the observed isotopic ratio. The minimum uncertainty obtainable in the estimate of the 13CH4/12CH4 isotopic ratio of methane emissions within a region is found to be too large to effectively constrain the relative fluxes of the individual methane sources. The feasibility of improving this uncertainty by increasing the spatial density of the 13CH4/12CH4 observational network is investigated.

Brown, Margaret

1995-06-01

148

Seasonal variation in methane emission from stored slurry and solid manures  

Microsoft Academic Search

Methane (CHâ) is an important greenhouse gas and recent inventories have suggested that livestock manure makes a significant contribution to global CHâ emissions. The emission of CHâ from stored pig slurry, cattle slurry, pig solid manure, and cattle solid manure was followed during a 1-yr period. Methane emission was determined by dynamic chambers. Emission rates followed a ln-normal distribution for

Søren Husted

1994-01-01

149

Methane emissions from 2000 to 2011 wildfires in Northeast Eurasia estimated with MODIS burned area data  

NASA Astrophysics Data System (ADS)

Estimates of methane wildfire emissions from Northeast Eurasia for years 2000-2011 are reported on the basis of satellite burned area data from the Moderate Resolution Imaging Spectroradiometer (MODIS MCD45 data product) and ecosystem-dependent fire emission parameters. Average (with standard deviations) emissions are 1.0 ± 0.2 Tg CH4 year-1, with interannual variations of 0.4-2.3 Tg CH4 year-1. Most of the emissions are located within 48-55°N, in the southern part of the boreal forest zone, mostly in Siberia and Far East. The largest discrepancies among independent present-day estimates are found in the sub-polar regions of West Siberia and Far East (60-65°N). Compared to the methane wetland emissions reported in literature, the wildfire emissions in the south add about 5-20% to their estimated average annual values and are compared with the magnitudes of their interannual variability. Average seasonal cycle peaks in April-May and July-August, which partially overlaps the summertime peak in wetland emissions. The independent estimates from version 3 of Global Fire Emissions Database (GFED3) are by 50% higher (compared to this study) for average annual emissions over the decade (which is quite good regarding the uncertainties) and showed larger differences for individual years. Possible applications of the results are considered for climate research and inverse modeling studies, as well as for assessment of the uncertainties in the present-day wildfire emission estimates.

Vasileva, Anastasia; Moiseenko, Konstantin

2013-06-01

150

Comparison of Aura TES Methane Profiles to Model Estimates Constrained by SCIAMACHY Total Column Measurements  

NASA Astrophysics Data System (ADS)

Recent increases in tropospheric methane between 2004 to the present have yet to be robustly explained by either increases in tropical emissions, high latitude wetlands, anthropogenic emissions, or changes in the global methane sink. New TES methane profiles, with spatial coverage over the whole globe, and with vertical profiling capability from 800 hPa to 200 hPa have the capability to place constraints on the temporal variability of methane emissions from these different sources and their subsequent transport. Here we present a comparison between these new TES data to model estimates that have been constrained by total column measurements of methane from the SCIAMACHY instrument for the year 2005. A subsequent analysis will relate observed differences to uncertainties in the emission strengths or transport.

Worden, J.; Kulawik, S.; Frankenberg, C.; Bergamaschi, P. M.; Bowman, K. W.; Payne, V.

2011-12-01

151

Revisiting factors controlling methane emissions from high-Arctic tundra  

NASA Astrophysics Data System (ADS)

The northern latitudes are experiencing disproportionate warming relative to the mid-latitudes, and there is growing concern about feedbacks between this warming and methane production and release from high-latitude soils. Studies of methane emissions carried out in the Arctic, particularly those with measurements made outside the growing season, are underrepresented in the literature. Here we present results of 5 yr (2006-2010) 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 periods. The measurements show clear seasonal dynamics in methane emission. The start of the growing season and the increase in CH4 fluxes were strongly related to the date of snowmelt. Within each particular growing season, CH4 fluxes were highly correlated with the soil temperature (R2 > 0.75), which is probably explained by high seasonality of both variables, and weakly correlated with the water table. The greatest variability in fluxes between the study years was 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 during at least three years. The cumulative 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 discuss possible links between growing season and autumn fluxes. Multiannual dynamics of the subsurface CH4 storage pool are hypothesized to be such a link and an important driver of intearannual variations in the fluxes, capable of overruling the conventionally known short-term control factors (temperature and water table). Our findings suggest the importance of multiyear studies with a continued focus on shoulder seasons in Arctic ecosystems.

Mastepanov, M.; Sigsgaard, C.; Tagesson, T.; Ström, L.; Tamstorf, M. P.; Lund, M.; Christensen, T. R.

2013-07-01

152

Effects of nutritional strategies on simulated nitrogen excretion and methane emission in dairy cattle  

Microsoft Academic Search

\\u000a To assess the relation between emission of methane (CH4) and faecal and urinary losses of nitrogen (N) in dairy cattle, various dietary strategies were evaluated using a mechanistic\\u000a model of fermentation and digestion processes. To simulate faecal and urinary composition, an extant dynamic, mechanistic\\u000a model of rumen function and post-absorptive nutrient supply was extended with static equations that describe intestinal

J. Dijkstra; J. L. Ellis; E. Kebreab; S. López; J. W. Reijs; A. Bannink

2011-01-01

153

Developing a Prognostic Methane Biogeochemistry Model in the CCSM: Model Evaluation and Regional Predictions  

NASA Astrophysics Data System (ADS)

Methane emissions from inundated organic soils and thermokarst lakes have the potential to form strong positive feedbacks with the atmosphere. As participants in the U.S. Department of Energy IMPACTS Project, we are investigating the potential for abrupt arctic climatic change resulting from feedbacks associated with increasing active layers and developing thermokarst lakes. Here we report on the development of a global methane biogeochemistry model in CLM4 (the land-surface model in the latest version of the CCSM), model testing against several observational datasets, and analysis of potential future methane exchanges with the atmosphere. Within a particular soil column, the methane biogeochemistry model operates separately in the saturated and unsaturated fractions. Mechanisms include methane production, ebullition, aerenchyma transport, oxidation, diffusion, and exchange with either the canopy air space or overlying atmosphere. Methane production is linked to soil C predictions as simulated in the CN portion of the code. Where possible, analytical solutions to the reactive transport equations were performed and compared with predictions. Model predictions compared very well with five multi-year observational datasets from North America. The biogeochemistry model has also been integrated with columns representing lakes (including changing thermokarst lakes). For this component of the model, we are using a new and substantially improved lake model (see poster by Subin et al.) that has been tested at a number of lakes with depths ranging from 2 to 50 m. Methane production estimates for the arctic lakes are based on sediment organic carbon content, temperature, and a sparse set of observations. After describing model structure and testing, we apply a set of future climate forcing datasets in an offline mode to investigate expected methane emissions over the 21st century, and how these emissions may result in feedbacks to enhance climate change.

Riley, W. J.; Subin, Z. M.; Torn, M. S.; Lawrence, D. M.

2009-12-01

154

Compositional modeling of enhanced coalbed methane recovery  

NASA Astrophysics Data System (ADS)

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

Manik, Julio

155

Design and evaluation of a porous burner for the mitigation of anthropogenic methane emissions.  

PubMed

Methane constitutes 15% of total global anthropogenic greenhouse gas emissions. The mitigation of these emissions could have a significant near-term effect on slowing global warming, and recovering and burning the methane would allow a wasted energy resource to be exploited. The typically low and fluctuating energy content of the emission streams makes combustion difficult; however porous burners-an advanced combustion technology capable of burning low-calorific value fuels below the conventional flammability limit-are one possible mitigation solution. Here we discuss a pilot-scale porous burner designed for this purpose. The burner comprises a cylindrical combustion chamber filled with a porous bed of alumina saddles, combined with an arrangement of heat exchanger tubes for preheating the incoming emission stream. A computational fluid dynamics model was developed to aid in the design process. Results illustrating the burner's stable operating range and behavior are presented: stable ultralean combustion is demonstrated at natural gas concentrations as low as 2.3 vol%, with transient combustion at concentrations down to 1.1 vol%; the system is comparatively stable to perturbations in the operating conditions, and emissions of both carbon monoxide and unburned hydrocarbons are negligible. Based on this pilot-scale demonstration, porous burners show potential as a methane mitigation technology. PMID:20000525

Wood, Susie; Fletcher, David F; Joseph, Stephen D; Dawson, Adrian; Harris, Andrew T

2009-12-15

156

Climate versus emission drivers of methane lifetime from 1860-2100  

NASA Astrophysics Data System (ADS)

With a more-than-doubling in the atmospheric abundance of the potent greenhouse gas methane (CH4) since preindustrial times, and indications of renewed growth following a leveling off in recent years, questions arise as to future trends and resulting climate and public health impacts from continued growth without mitigation. Changes in atmospheric methane lifetime are determined by factors which regulate the abundance of OH, the primary methane removal mechanism, including changes in CH4 itself. We investigate the role of emissions of short-lived species and climate in determining the evolution of tropospheric methane lifetime in a suite of historical (1860-2005) and Representative Concentration Pathway (RCP) simulations (2006-2100), conducted with the Geophysical Fluid Dynamics Laboratory (GFDL) fully coupled chemistry-climate model (CM3). From preindustrial to present, CM3 simulates an overall 5% increase in CH4 lifetime due to a doubling of the methane burden which offsets coincident increases in nitrogen oxide (NOx) emissions. Over the last two decades, however, the methane lifetime declines steadily, coinciding with the most rapid climate warming and observed slow-down in CH4 growth rates, reflecting a possible negative feedback through the CH4 sink. The aerosol indirect effect plays a significant role in the CM3 climate and thus in the future evolution of the methane lifetime, due to the rapid projected decline of aerosols under all four RCPs. In all scenarios, the methane lifetime decreases (by 5-13%) except for the most extreme warming case (RCP8.5), where it increases by 4% due to the near-doubling of the CH4 abundance, reflecting a positive feedback on the climate system. In the RCP4.5 scenario changes in short-lived climate forcing agents reinforce climate warming and enhance OH, leading to a more-than-doubling of the decrease in methane lifetime from 2006 to 2100 relative to a simulation in which only well-mixed greenhouse gases are allowed to change along the RCP4.5 scenario (13% vs. 5%) Future work should include process-based studies to better understand and elucidate the individual mechanisms controlling methane lifetime.

John, J. G.; Fiore, A. M.; Naik, V.; Horowitz, L. W.; Dunne, J. P.

2012-07-01

157

Quantifying the effect of oxidation on landfill methane emissions  

Microsoft Academic Search

Field, laboratory, and computer modeling methods were utilized to quantitatively assess the capability of aerobic microorganisms to oxidize landfill-derived methane (CH4) in cover soils. The investigated municipal landfill, located in Nashua, New Hampshire, was operating without gas controls of any type at the time of sample collection. Soil samples from locations of CH 4 flux to the atmosphere were returned

P. M. Czepiel; B. Mosher; P. M. Crill; R. C. Harriss

1996-01-01

158

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

159

[Simulation of methane emissions from rice fields in the Taihu Lake region, China by using different unit of soil database with the DNDC model].  

PubMed

Application of a biogeochemical model, DeNitrification and DeComposition or DNDC, was discussed to assess the impact of CH4 emissions on different soil database from rice fields in Taihu Lake region of China. The results showed that CH4 emissions of the polygon-based soil database of 1:50000, which contained 52034 polygons of paddy soils representing 1107 paddy soil profiles extracted from the latest national soil map (1:50000), were located within the ranges produced by the county-based soil database of 1:50000. However, total emissions of the whole area differed by about 1680 Gg CH4-C. Moreover, CH4 emissions of the polygon-based soil database of 1:50000 and the county-based soil database of 14,000,000, which was the most popular data source when DNDC model was applied in China, have a big estimation discrepancy among each county-based unit in spite of total emissions of the whole area by a difference of 180 Gg CH4-C. This indicated that the more precise soil database was necessary to better simulate CH4 emissions from rice fields in Taihu Lake region using the DNDC model. PMID:19799272

Zhang, Li-ming; Yu, Dong-sheng; Shi, Xue-zheng; Zhao, Li-min; Ding, Wei-xin; Wang, Hong-jie; Pan, Jian-jun

2009-08-15

160

Cross-correlation analysis of the dynamics of methane emissions from a boreal peatland  

NASA Astrophysics Data System (ADS)

The effects of temperature, water table, and precipitation on the methane fluxes from a boreal low-sedge Sphagnum papillosum pine fen were analyzed with statistical cross correlations of daily data. The six measurement sites represented different vegetation surfaces of the mire (hummocks, lawns, and flarks) with increasing moisture. The dynamics were analyzed separately for the early summer (May-July) and the late summer (August-October) periods in addition to the whole summer (May-October) period. Methane emissions increased with increasing peat temperature. During the late summer period, changes in peat temperatures at depths of 20 and 50 cm were reflected in methane emissions within 2 days. The persistently high water tables during the measurement period probably did not reveal the dynamics between water table fluctuations and methane emissions very clearly. Methane emission levels correlated negatively with depths of the water tables, that is, high methane emissions were associated with low water tables and vice versa. The suppression of methane emissions by filling the unsaturated gas space during precipitation and the increased release rate caused by a declining water table could explain the result. Methane emissions correlated positively with changes in water tables, that is, a rise in water table increased methane emissions during the early and whole summer periods. Precipitation increased emissions with a lag from zero to several days throughout the summer. Generally, the estimated responses of methane fluxes to precipitation and changes in water table indicated similar time lags. Methane flux from the flark surfaces seemed to respond rapidly to rainfall and changes in water table with a lag of zero or 1 day. In the lawn-low hummock, the lawn and one hummock site, methane flux showed a slow response with several days lag. This study strongly indicates that temperature, water table, and precipitation affect methane emissions with complex interactions.

Kettunen, Ann; Kaitala, Veijo; Alm, Jukka; Silvola, Jouko; NykäNen, Hannu; Martikainen, Pertti J.

1996-09-01

161

Natural emissions of methane from geological seepage in Europe  

NASA Astrophysics Data System (ADS)

Recent studies have shown that geological emissions of methane are an important greenhouse-gas source. Remarkable amounts of methane, estimated in the order of 40-60 Tg yr -1, are naturally released into the atmosphere from the Earth's crust through faults and fractured rocks. The main source is natural gas, both microbial and thermogenic, produced in hydrocarbon-prone sedimentary basins and injected into the atmosphere through macro-seeps (onshore and offshore mud volcanoes and other seeps) and microseepage, an invisible but pervasive flux from the soil. This source is now evaluated for Europe on the basis of a literature survey, new field measurements and derived emission factors. The up-scaling criteria recommended by the EMEP/CORINAIR guidelines are applied to the local point and area source data. In Europe, 25 countries host oil and/or natural gas reservoirs and potentially, or actually, emit geological methane. Flux data, however, are available only from 10 countries: the onshore or offshore petroliferous sectors of Denmark, Italy, Greece, Romania, Spain, Switzerland, United Kingdom and Black Sea countries (Bulgaria, Ukraine, Georgia). Azerbaijan, whose emissions due to mud volcanism are known to be relevant, is included in the estimate. The sum of emissions, regional estimates and local measurements, related to macro-seeps leads to a conservative total value of about 2.2 Tg yr -1. Together with the potential microseepage fluxes from the petroliferous basins, estimated on the basis of the Total Petroleum System concept (around 0.8 Tg yr -1), the total European seepage is projected to 3 Tg yr -1. This preliminary figure would represent, in terms of magnitude, the second natural methane source for Europe after wetlands. The estimate will have to be refined by increasing the number of seepage measurements both on lands, where there is high potential for microseepage (e.g., Germany, Hungary, Romania, Ukraine, Belarus, Russia, Georgia) and in coastal marine areas (the North Sea, the Black Sea, offshore Greece and Italy) where emission factors and the extent of the underwater seeping area are not completely known.

Etiope, Giuseppe

162

Methane emission from sub-sea permafrost in the East Siberian Arctic shelf: model-based evaluation of potential impact on global climate  

NASA Astrophysics Data System (ADS)

Several recent publications suggest that the observed high concentration of methane over the East Siberian Shelf (ESS) may be attributed to thawing and increased gas permeability (through taliks) of the sub-sea permafrost. Methane is released from unstable gas hydrates and propagates through newly formed taliks in the bottom sediments to the water and further to the atmosphere. Under sustained warming in the following decades it may have potentially dramatic effect on global climate. In this study we examine this hypothesis using comprehensive modelling approach. Direct observations indicate that since the mid-1980s bottom waters over the ESS warmed by ca. 2.1°C. We used the model to examine whether such changes may have caused substantial degradation of methane bearing sub-sea permafrost and CH4 supersaturation of the ESS sea waters. The model is based on the heat transfer equation and explicitly accounts for the effect of salt diffusion in the bottom sediments by coupling the thermal and mass fluxes. We forced the model by the prescribed seasonal bottom water temperature and salinity to calculate changes in the thermal state of permafrost after the inundation of the ESS, and to predict the changes in the following 1000 years. We used a climate scenario suggesting that at the time of inundation (ca 8 Ky BP) the top sediment layer warmed by ca. 12 °C from -13.5 °C (mean annual air temperature) to -1.5 °C (bottom water temperature). Afterwards temperature remained unchanged until 1985. Since then in accord with modern observations we imposed 0.09°C/year trend until 2100, and prescribed temperature to constant value of 11.5 °C afterwards. The rate of temperature change in the 21st century in this highly schematic scenario by far exceeds all IPCC projections. We did it intentionally to explore the most extreme pathway for potential sub-see permafrost degradation underneath the ESS. Model results indicated ca 1 m deepening of the upper sub-sea permafrost boundary in the period 1985-2009 and subsequent deepening by 5 m after 50 years, ~9 m after 100 years, and ~48 m after 1000 years. Over the same time periods, the control runs without BLT trends show a deepening of the permafrost table by 0.1 m, 0.2 m, and 2 m, respectively. These results do not support the hypothesis of recent increase in permafrost permeability due to formation of taliks. The high CH4 concentration over the ESS is more likely to be attributed to the long lasting degradation of subsea permafrost initiated 8 KY ago. Our estimates based on the analysis of the greenhouse gas potential indicated that if the current conditions with ca. 7.9 Tg/y CH4 flux from ESS area to the atmosphere persist for the following decades, it may increase the atmospheric concentration of methane by ca. 0.04 ppm. The associated radiative forcing will lead to less than 0.015 °C global temperature rise, which is insignificant compared to the effect of other factors governing the modern climate change.

Anisimov, O. A.; Lavrov, S. A.; Borzenkova, I. I.

2011-12-01

163

Estimate of methane emissions from US landfills. Final report, December 1992-January 1994  

SciTech Connect

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. The model has three linear segments, each of which applies to a distinct landfill size class. Assumptions were required to account for the recovery efficiency of LFG projects and for the probable oxidation of CH4 in the top soil cover of the landfill. The report details uncertainties which limit the quality of the above estimates. The report concludes with a discussion of trends which will affect future LFG emissions, as well as LFG utilization.

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

1994-09-01

164

Estimating regional methane emissions from agriculture using aircraft measurements of concentration profiles  

Microsoft Academic Search

This paper describes a “top-down” approach for estimating regional surface fluxes of methane, and its application to a pastoral farming region in New Zealand. The approach is based on air sampling from aircraft and interpretation by mesoscale dispersion modelling. The goal is an independent cross-check for an agricultural region of “bottom-up” emission estimation methods like those used for inventory reporting

D. S. Wratt; N. R. Gimson; G. W. Brailsford; K. R. Lassey; A. M. Bromley; M. J. Bell

2001-01-01

165

Global Health Benefits from Reductions in Background Tropospheric Ozone due to Methane Emission Controls  

Microsoft Academic Search

Increases in background ozone throughout the troposphere are partially attributed to rising anthropogenic methane concentrations, which are projected to continue to increase in the future. Because methane is long-lived and affects background ozone, controls on methane emissions would reduce surface ozone concentrations fairly uniformly around the globe. Epidemiological research indicates that exposure to ozone increases incidence of respiratory ailments and

J. J. West; D. L. Mauzerall; A. M. Fiore; L. W. Horowitz

2005-01-01

166

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

167

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

National Technical Information Service (NTIS)

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 ar...

D. Jones H. Hilger J. Bogner J. Oliver

2009-01-01

168

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

Microsoft Academic Search

On April 20, a violent methane discharge severed the Deepwater Horizon rig from its well and oil and gas began spilling into the deep Gulf of Mexico at depths of ca. 1.5 km simulating a natural, rapid, and short-term methane release in deepwater. Given the estimated rates of emission of total material as well as the fraction methane by weight,

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

2010-01-01

169

Spatial and temporal dynamics of methane emissions from agricultural sources in China  

Microsoft Academic Search

Agricultural activities contribute significantly to the global methane budget. Agricultural sources of methane are influenced by land-use change, including changes in agricultural area, livestock keeping and agricultural management practices. A spa- tially explicit inventory of methane emissions from agriculture is made for China tak- ing the interconnections between the different agricultural sources into account. The influence of land-use change on

PETER H. V ERBURG

2001-01-01

170

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

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

171

Quantifying methane emissions from rice fields in the Taihu Lake region, China by coupling a detailed soil database with biogeochemical model  

NASA Astrophysics Data System (ADS)

As China has approximately 22% of the world's rice paddies, the regional quantification of CH4 emissions from these paddies is important in determining their contribution to the global greenhouse gas effect. This paper reports the use of a biogeochemical model (DeNitrification and DeComposition or DNDC) for quantifying CH4 emissions from rice fields in the Taihu Lake region of China. For this application, the DNDC model was linked to a 1:50 000 soil database derived from 1107 paddy soil profiles compiled during the Second National Soil Survey of China in the 1980s-1990s. The simulated results showed that the 2.3 Mha of paddy rice fields in the Taihu Lake region emitted the equivalent of 5.7 Tg C from 1982-2000, with the average CH4 flux ranging from 114 to 138 kg C ha-1 y-1. As for soil subgroups, the highest emission rate (660 kg C ha-1 y-1) was linked to gleyed paddy soils accounting for about 4.4% of the total area of paddy soils. The lowest emission rate (91 kg C ha-1 y-1) was associated with degleyed paddy soils accounting for about 18% of the total area of paddy soils. The most common soil in the area was hydromorphic paddy soils, which accounted for about 53% of the total area of paddy soils with a CH4 flux of 106 kg C ha-1 y-1. On a regional basis, the annual averaged CH4 flux in the Taihu Lake plain soil region and alluvial plain soil region were higher than that in the low mountainous and hilly soil region and the polder soil region. The model simulation was conducted with two databases using polygons or counties as the basic units. The county-based database contained soil information coarser than the polygon system built based on the 1:50 000 soil database. The modeled results with the two databases found similar spatial patterns of CH4 emissions in the Taihu Lake region. However, discrepancies exist between the results from the two methods. The total CH4 emissions generated from the polygon-based database is 2.6 times the minimum CH4 emissions generated from the county-based database, and is 0.98 times the maximum CH4 emissions generated from the county-based database. The average value of the relative deviation ranged from -20% to 98% for most counties, which indicates that a more precise soil database is necessary to better simulate CH4 emissions from rice fields in the Taihu Lake region using the DNDC model.

Zhang, L.; Yu, D.; Shi, X.; Weindorf, D.; Zhao, L.; Ding, W.; Wang, H.; Pan, J.; Li, C.

2009-05-01

172

A model of methane production in soils  

SciTech Connect

We have developed a simple model for methane production for flooded soils. Labile substrate supply is simulated as a proportion of the carbon decomposed and is controlled by temperature, moisture, and liter quality (lignin:N). The proportion of labile substrate converted to methane (rather than CO[sub 2]) is controlled by redox, temperature, pH, substrate supply and quality. The model parameterization are based on a series of laboratory experiment which examine the CH[sub 4] response to ethanol, litter, and root amendments, temperature and pH manipulations in anaerobic slurries. Preliminary comparisons demonstrate that the model is able to effectively simulate CH[sub 4] production for a range of environmental conditions and that methane production is sensitive to both the amount and quality of incoming carbon.

Holland, E.A.; Coxwell, C.; Schimel, D.S. (National Center for Atmospheric Research, Boulder, CO (United States)); Valentine, D. (Colorado State Univ., Ft. Collins (United States))

1993-06-01

173

Towards an inventory of methane emissions from manure management that is responsive to changes on Canadian farms  

NASA Astrophysics Data System (ADS)

Methane emissions from manure management represent an important mitigation opportunity, yet emission quantification methods remain crude and do not contain adequate detail to capture changes in agricultural practices that may influence emissions. Using the Canadian emission inventory methodology as an example, this letter explores three key aspects for improving emission quantification: (i) obtaining emission measurements to improve and validate emission model estimates, (ii) obtaining more useful activity data, and (iii) developing a methane emission model that uses the available farm management activity data. In Canada, national surveys to collect manure management data have been inconsistent and not designed to provide quantitative data. Thus, the inventory has not been able to accurately capture changes in management systems even between manure stored as solid versus liquid. To address this, we re-analyzed four farm management surveys from the past decade and quantified the significant change in manure management which can be linked to the annual agricultural survey to create a continuous time series. In the dairy industry of one province, for example, the percentage of manure stored as liquid increased by 300% between 1991 and 2006, which greatly affects the methane emission estimates. Methane emissions are greatest from liquid manure, but vary by an order of magnitude depending on how the liquid manure is managed. Even if more complete activity data are collected on manure storage systems, default Intergovernmental Panel on Climate Change (IPCC) guidance does not adequately capture the impacts of management decisions to reflect variation among farms and regions in inventory calculations. We propose a model that stays within the IPCC framework but would be more responsive to farm management by generating a matrix of methane conversion factors (MCFs) that account for key factors known to affect methane emissions: temperature, retention time and inoculum. This MCF matrix would be populated using a mechanistic emission model verified with on-farm emission measurements. Implementation of these MCF values will require re-analysis of farm surveys to quantify liquid manure emptying frequency and timing, and will rely on the continued collection of this activity data in the future. For model development and validation, emission measurement campaigns will be needed on representative farms over at least one full year, or manure management cycle (whichever is longer). The proposed approach described in this letter is long-term, but is required to establish baseline data for emissions from manure management systems. With these improvements, the manure management emission inventory will become more responsive to the changing practices on Canadian livestock farms.

VanderZaag, A. C.; MacDonald, J. D.; Evans, L.; Vergé, X. P. C.; Desjardins, R. L.

2013-09-01

174

Methane emissions from Alaska arctic tundra in response to climatic change  

SciTech Connect

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.

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

1992-03-01

175

FARM-produced alcohol and methane model  

SciTech Connect

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

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

1983-12-01

176

National estimate of methane emissions from compressors in the US natural gas industry. Report for April 1992September 1993  

Microsoft Academic Search

The paper discusses a cofunded Gas Research Institute\\/EPA program to evaluate methane emissions from the natural gas industry in the U.S. The program consists of an emission testing program and an engineering assessment program for the major methane emission sources within the natural gas industry. One methane emission source is reciprocating engines and turbines that are used to drive compressors

D. L. Jones; L. M. Campbell; C. E. Burklin; M. Gundappa; R. A. Lott

1996-01-01

177

Three-dimensional model synthesis of the global methane cycle  

Microsoft Academic Search

A synthesis of the global methane cycle is presented to attempt to generate an accurate global methane budget. Methane-flux measurements, energy data, and agricultural statistics are merged with databases of land-surface characteristics and anthropogenic activities. The sources and sinks of methane are estimated based on atmospheric methane composition and variations, and a global 3D transport model simulates the corresponding atmospheric

I. Fung; M. Prather; J. John; J. Lerner; E. Matthews; L. P. Steele; P. J. Fraser

1991-01-01

178

Mapping methane emission sources over California based on airborne measurements  

NASA Astrophysics Data System (ADS)

The California Global Warming Solutions Act of 2006 (AB 32) has created a need to accurately characterize the emission sources of various greenhouse gases (GHGs) and verify the existing state GHG inventory. Methane (CH4) is a major GHG with a global warming potential of 20 times that of CO2 and currently constitutes about 6% of the total statewide GHG emissions on a CO2 equivalent basis. Some of the major methane sources in the state are area sources where methane is biologically produced (e.g. dairies, landfills and waste treatment plants) making bottom-up estimation of emissions a complex process. Other potential sources include fugitive emissions from oil extraction processes and natural gas distribution network, emissions from which are not well-quantified. The lack of adequate field measurement data to verify the inventory and provide independently generated estimates further contributes to the overall uncertainty in the CH4 inventory. In order to gain a better perspective of spatial distribution of major CH4 sources in California, a real-time measurement instrument based on Cavity Ring Down Spectroscopy (CRDS) was installed in a Twin Otter aircraft for the CABERNET (California Airborne BVOC Emissions Research in Natural Ecosystems Transects) campaign, where the driving research goal was to understand the spatial distribution of biogenic VOC emissions. The campaign took place in June 2011 and encompassed over forty hours of airborne CH4 and CO2 measurements during eight unique flights which covered much of the Central Valley and its eastern edge, the Sacramento-San Joaquin delta and the coastal range. The coincident VOC measurements, obtained through a high frequency proton transfer reaction mass spectrometer (PTRMS), aid in CH4 source identification. High mixing ratios of CH4 (> 2000 ppb) are observed consistently in all the flight transects above the Central Valley. These high levels of CH4 are accompanied by high levels of methanol which is an important dairy tracer. The elevated CH4 mixing ratios, along the eastern edge of the San Joaquin valley, highlight the contribution of local meteorology, topography and emissions transport to local ambient levels of CH4. High mixing ratios of CH4, along with high levels of benzene and toluene, are observed while flying along the western edge of Kern County which is home to some of the largest active oil fields in the state. The scale of these operations and their contribution of < 3% to the state CH4 inventory suggest there is a likelihood of under-estimation of fugitive emissions from oil and gas extraction processes. VOC tracer analysis is used to evaluate the source of high CH4 emissions encountered along the eastern edge of the central Sacramento valley where fugitive emissions from natural gas fields and cultivation of rice are likely sources. Enhancement ratios of CH4 to CO2 and other VOC tracers are compared to existing emission factors from ground based measurements, dairy chamber studies, previous airplane measurements and inventory data.

Karl, T.; Guha, A.; Peischl, J.; Misztal, P. K.; Jonsson, H.; Goldstein, A. H.; Ryerson, T. B.

2011-12-01

179

Characterizing the tropospheric ozone response to methane emission controls and the benefits to climate and air quality  

Microsoft Academic Search

Reducing methane (CH4) emissions is an attractive option for jointly addressing climate and ozone (O3) air quality goals. With multidecadal full-chemistry transient simulations in the MOZART-2 tropospheric chemistry model, we show that tropospheric O3 responds approximately linearly to changes in CH4 emissions over a range of anthropogenic emissions from 0–430 Tg CH4 a?1 (0.11–0.16 Tg tropospheric O3 or ?11–15 ppt

Arlene M. Fiore; J. Jason West; Larry W. Horowitz; Vaishali Naik; M. Daniel Schwarzkopf

2008-01-01

180

Atmospheric Modeling of Mars Methane Plumes  

NASA Astrophysics Data System (ADS)

We present two complementary methods for isolating and modeling surface source releases of methane in the martian atmosphere. From recent observations, there is strong evidence that periodic releases of methane occur from discrete surface locations, although the exact location and mechanism of release is still unknown. Numerical model simulations with the Mars Weather Research and Forecasting (MarsWRF) general circulation model (GCM) have been applied to the ground-based observations of atmospheric methane by Mumma et al., (2009). MarsWRF simulations reproduce the natural behavior of trace gas plumes in the martian atmosphere, and reveal the development of the plume over time. These results provide constraints on the timing and location of release of the methane plume. Additional detections of methane have been accumulated by the Planetary Fourier Spectrometer (PFS) on board Mars Express. For orbital observations, which generally have higher frequency and resolution, an alternate approach to source isolation has been developed. Drawing from the concept of natural selection within biology, we apply an evolutionary computational model to this problem of isolating source locations. Using genetic algorithms that `reward’ best-fit matches between observations and GCM plume simulations (also from MarsWRF) over many generations, we find that we can potentially isolate source locations to within tens of km, which is within the roving capabilities of future Mars rovers. Together, these methods present viable numerical approaches to restricting the timing, duration and size of methane release events, and can be used for other trace gas plumes on Mars as well as elsewhere in the solar system.

Mischna, Michael A.; Allen, M.; Lee, S.

2010-10-01

181

Effects of methane on giant planet's UV emissions and implications for the auroral characteristics  

NASA Astrophysics Data System (ADS)

This study reviews methods used to determine important characteristics of giant planet's UV aurora (brightness, energy of the precipitating particles, altitude of the emission peak,…), based on the absorbing properties of methane and other hydrocarbons. Ultraviolet aurorae on giant planets are mostly caused by inelastic collisions between energetic magnetospheric electrons and the ambient atmospheric H2 molecules. The auroral emission is situated close to a hydrocarbon layer and may be attenuated by methane (CH4), ethane (C2H6) and acetylene (C2H2) at selected wavelengths. As methane is the most abundant hydrocarbon, it is the main UV absorber and attenuates the auroral emission shorward of 1350 Å. The level of absorption is used to situate the altitude/pressure level of the aurora, hence the energy of the precipitated electrons, whose penetration depth is directly related to their mean energy. Several techniques are used to determine these characteristics, from the color ratio method which measures the level of absorption from the ratio between an absorbed and an unabsorbed portion of the observed auroral spectrum, to more realistic methods which combine theoretical distributions of the precipitating electrons with altitude dependent atmospheric models. The latter models are coupled with synthetic or laboratory H2 spectra and the simulated emergent spectra are compared to observations to determine the best auroral characteristics.

Gustin, J.; Gérard, J.-C.; Grodent, D.; Gladstone, G. R.; Clarke, J. T.; Pryor, W. R.; Dols, V.; Bonfond, B.; Radioti, A.; Lamy, L.; Ajello, J. M.

2013-09-01

182

Aerobic methane emission from plants in the Inner Mongolia steppe.  

PubMed

Traditionally, methane (CH4) emission from terrestrial plants is thought to originate from belowground microbial metabolism under anaerobic conditions, with subsequent transport to the atmosphere through stems. However, a recent study reported aerobic CH4 emission from plants by an unrecognized process, a result that has since been questioned. We investigated CH4 emissions under aerobic conditions from aboveground tissues of 44 species indigenous to the temperate Inner Mongolia steppe. Ten herbaceous hydrophytes (wetland-adapted plants) were examined, two of which--Glyceria spiculosa and Scirpus yagara--emitted CH4 from stems but not from detached leaves. Of 34 xerophytes (arid-adapted plants) examined, 7 out of 9 shrub species emitted CH4 from detached leaves but not stems, whereas none of 25 herbaceous xerophytes emitted CH4. The herbaceous hydrophyte, S. yagara, emitted highly 13C-depleted CH4, suggesting a microbial origin. Achillea frigida exhibited the highest CH4 emission rates among the shrubs and continuously emitted relatively 13C-enriched CH4 from detached leaves, indicating that CH4 was derived directly from plant tissues under aerobic conditions. Because woody species are relatively rare in the Inner Mongolia steppe, aerobic, plant-derived CH4 emission is probably negligible in this region. Our results may imply a larger role for aerobic CH4 production in upland ecosystems dominated by woody species or in ecosystems where woody encroachment is occurring as a result of global change. PMID:18350876

Wang, Zhi-Ping; Han, Xing-Guo; Wang, G Geoff; Song, Yang; Gulledge, Jay

2008-01-01

183

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

SciTech Connect

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.

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

1995-02-01

184

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...

185

Methane emissions from a freshwater marsh in response to experimentally simulated global warming and nitrogen enrichment  

Microsoft Academic Search

We determined methane (CH4) emissions in a field enclosure experiment in a littoral freshwater marsh under the influence of experimentally simulated warming and enhanced nitrogen deposition. Methane emissions by ebullition from the marsh composed of Phragmites australis were measured with funnel traps deployed in a series of enclosures for two 3 week periods. Diffusive fluxes were estimated on the basis

Sabine Flury; Daniel F. McGinnis; Mark O. Gessner

2010-01-01

186

METHANE EMISSION FROM GRAZING DAIRY CATTLE IN TROPICAL BRAZIL: MITIGATION BY IMPROVING PRODUCTION  

Microsoft Academic Search

Experiments were carried out on tropical grass pasture, in summer 2002, to find out possible mitigation options to reduce methane emission using different categories of grazing dairy cattle breeds. Methane emission was measured using the SF6 tracer technique. Experimental design was a block distribution in tim e, along four consecutive weeks, five days a week, at 12 -hour intervals, employing

Brazil Frighetto; M. A. Lima

187

Integrated rice–fish production and methane emission under greenhouse conditions  

Microsoft Academic Search

A greenhouse experiment was carried out including the treatments: (1) rice combined with common carp, Cyprinus carpio, (2) rice combined with a mixed culture of common carp and Nile tilapia, Oreochromis niloticus, and (3) rice-only. Methane emission and some related water and soil characteristics were determined at regular interval. Generally, methane emissions were quite high and reached a maximum of

M. Frei; K. Becker

2005-01-01

188

Emission factors for methane and nitrous oxide from manure management and mitigation options  

Microsoft Academic Search

Under the United Nations Framework Convention on Climate Change (UNFCCC), the Kyoto-protocol is aimed at reducing the emission of greenhouse gases. Therefore, members report their greenhouse gas (GHG) emissions every year in a National Inventory Report (NIR). For agriculture the Netherlands identify three sources of GHG: enteric fermentation (methane), manure management (methane and nitrous oxide) and agricultural soils (nitrous oxide).

Karin Groenestein; Julio Mosquera; Sietske Van der Sluis

2012-01-01

189

Emission factors for methane and nitrous oxide from manure management and mitigation options (Online first)  

Microsoft Academic Search

Under the United Nations Framework Convention on Climate Change (UNFCCC), the Kyoto-protocol is aimed at reducing the emission of greenhouse gases. Therefore, members report their greenhouse gas (GHG) emissions every year in a National Inventory Report (NIR). For agriculture the Netherlands identify three sources of GHG: enteric fermentation (methane), manure management (methane and nitrous oxide) and agricultural soils (nitrous oxide).

C. M. Groenestein; J. Mosquera Losada; Sluis van der S

2012-01-01

190

Methane emissions from rice fields amended with biogas slurry and farm yard manure  

Microsoft Academic Search

In an experiment on methane-emission measurements from rice fields amended with urea, biogas spent slurry (BSS) + urea, and farm yard manure (FYM) + urea, three distinctive peaks in the methane emissions were observed at 15, 46, and 69 days after transplanting (DAT) due to the availability of readily degradable C-sources. In all cases, the highest peak was at 69

Goutam Debnath; M. C. Jain; Sushil Kumar; K. Sarkar; Suresh K. Sinha

1996-01-01

191

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...

192

Modeling of methane release from intact coal  

SciTech Connect

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.

Odintsev, V.N. [Russian Academy of Science, Moscow (Russian Federation)

2005-09-15

193

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

...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...

2013-07-01

194

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

National Technical Information Service (NTIS)

The work reported was performed for the purpose of refining estimates of methane emissions from rice fields. Research performed included methane flux measurements, evaluation of variables affecting emissions, compilation of a data base, and continental ba...

M. A. K. Khalil R. A. Rasmussen

1997-01-01

195

Methane emissions from the surface of the Three Gorges Reservoir  

NASA Astrophysics Data System (ADS)

After our previous study about methane (CH4) emissions from littoral marshes of the Three Gorges Reservoir (TGR), Chinese dams have raised a world-wide concern. Through measurements from the surface of the TGR, a CH4 emission rate was recorded as 0.26 ± 0.38 mg CH4 m-2 h-1 (Mean ± SD), relatively low compared with those from other hydropower reservoirs. We also recorded CH4 emission rate from the surface of downstream water, which was also relatively low (0.24 ± 0.37 mg CH4 m-2 h-1). Such result may indicate that TGR is not a great CH4 emitter (not "CH4 menace"). One possible reason for such a low emission rate is that measures to maintain water quality and protect environment and ecosystem decrease the input of organic materials (for methanogenesis), which in turn limits the CH4 production in the sediment of the TGR. We also found that CH4 emission from the flooding drawdown area (0.29 ± 0.37 mg CH4 m-2 h-1) was higher than other permanently flooded sites (0.23 ± 0.38 mg CH4 m-2 h-1). Because of annual vegetation re-growth, the drawdown zone is the especially important carbon source for methanogenesis in flooding season. Interestingly, we also observed that mean CH4 emission was significantly higher in winter than in spring and summer. This was partly due to seasonal dynamics of hydrology. In order to estimate the net CH4 emissions caused by the reservoir and reservoir operation, the best approach would be Life Cycle Analysis.

Chen, Huai; Yuan, Xingzhong; Chen, Zhongli; Wu, Yuyuan; Liu, Xianshu; Zhu, Dan; Wu, Ning; Zhu, Qiu'an; Peng, Changhui; Li, Weizhong

2011-11-01

196

Efficiency of the benthic filter: Biological control of the emission of dissolved methane from sediments containing shallow gas hydrates at Hydrate Ridge  

Microsoft Academic Search

In marine sedimentary environments, microbial methanotrophy represents an important sink for methane before it leaves the seafloor and enters the water column. Using benthic observatories in conjunction with numerical modeling of pore water gradients, we investigated seabed methane emission rates at cold seep sites with underlying gas hydrates at Hydrate Ridge, Cascadia margin. Measurements were conducted at three characteristic sites

S. Sommer; O. Pfannkuche; P. Linke; R. Luff; J. Greinert; M. Drews; S. Gubsch; M. Pieper; M. Poser; T. Viergutz

2006-01-01

197

Methane emissions from West Siberian mud volcanoes: observations near Khanty-Mansiysk  

NASA Astrophysics Data System (ADS)

Recent studies have shown that mud volcanoes are important methane sources. We found mud volcanoes with high methane emissions in the floodplains of West Siberia middle taiga zone (25-40 km from Khanty-Mansiysk city). Despite of the minor area in comparison with surrounding methane-emitting wetlands, their methane emission rate reach 0.2 kg.m2h-1 that appears to be 1000 to 100000 times higher than that for wetlands. Probability density distribution of the observed methane emission rates is close to log-normal. Methanotrophic communities oxidizing emitted methane were found around seepages. Molecular identification of bacteria community composition using pmoA gen detects both type II and type I of methanotrophic bacteria (Gammaproteobacteria and Alphaproteobacteria classes, respectively) with type I dominating. Microorganisms similar to the authentic psychrophile Methylobacter psychrophiles (previously detected only in tundra soils) were also found among the later as well as a number of unidentified methanotrophs belonging to unknown taxon.

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

2011-12-01

198

Methane emissions from lakes in West Siberian wetlands  

NASA Astrophysics Data System (ADS)

Wetland lakes are less studied component in the methane emission inventories. We investigated methane fluxes in lakes situated in wetlands in most eco-regions of West Siberia including taiga (16 sites overall in sub-taiga, southern taiga, middle taiga, northern taiga), forest-steppe (1 site), forested tundra (1 site) and tundra (5 sites). Flux measurements were made during summer and autumn of 2007 and summer of 2008 and 2009. We used static chambers with base size of 40x40 cm and height of 30 cm and 40 cm floated on water surface. Each observation included collecting 4 samples in a 7-10 minute time step. Methane concentrations in samples were determined with the GC-FID. Concentration trend during exposure and fluxes were calculated with linear regression of concentration versus time. Environmental factors (pH, EC and temperature profile) were measured at each site. Mean fluxes by eco-region and corresponding statistics were obtained. In the following list, numbers in parenthesis are in the given order: 1st quartile/median/3rd quartile: forest-steppe - 98.0/125.6/146.0; sub-taiga - 62.0/84.6/170.3; southern taiga - 2.4/3.8/12.5; middle taiga - 0.1/0.4/1.4; northern taiga - 0.01/0.1/1.2; forested tundra - 0.3/0.6/1.4; tundra - 0.3/0.6/1.1 mgC-CH4m-2h-1. Interestingly, tundra fluxes are same as in the forested tundra to the south, and forest-steppe fluxes are much higher than on the other areas. Observed emission rates vary along with a combination of two factors: eco-region and pH. Probably, eco-region type connects with temperature, and pH connects with conditions of mineral supply. Emission rate dependence on pH has maximum around with pH = 5.2-5.4. Fluxes of CH4 from the lakes in the forest-steppe and sub-taiga are higher than in surrounding wetlands, while lake fluxes in other climate regions of West Siberia are comparable with those from the corresponding wetlands. Our data concur with previous report by (Repo et al, 2007), who observed fluxes at two sites in middle taiga and forested tundra. References: Repo M.E., et al, Release of CO2 and CH4 from small wetland lakes in western Siberia, Tellus, DOI: 10.1111/j.1600-0889.2007.00301, 2007.

Kazantsev, Vladimir; Glagolev, Mihail; Golubyatnikov, Leonid; Maksutov, Shamil

2010-05-01

199

Trends and seasonal cycle of the tropospheric methane observed and modeled over Siberia  

NASA Astrophysics Data System (ADS)

We analyzed 12 years of atmospheric methane data observed over West Siberia and compared with models of atmospheric transport and chemistry. The observational data were obtained by flask sampling and laboratory analysis. The samples were taken at the altitude range of 0.5 to 7 km once a month near Surgut and Novosibirsk. The purpose of this study was to compare simulated concentration time series with observed ones is order to evaluate existing surface methane emission estimates for the region. We conducted model simulations with three different chemical tracer transport models using seasonally varying methane emissions (without inter-annual variability). In the lower troposphere, seasonal cycle and trends are obscured by large synoptic scale variability, exceeding seasonal cycle amplitude and inter-annual variability. To reduce the effect of the variability we use multi-year average seasonal cycle in the comparison between models and observations. Observations and models suggest the methane concentration in lower troposphere is significantly different from the free troposphere in response to regional emissions. There is an indication of the large emissions in late summer in the observed seasonal cycle over Surgut. To improve a seasonal cycle fit we need improved surface methane flux models, properly accounting for amplitude and seasonality of emissions.

Maksyutov, S.; Machida, T.; Kim, H.; Patra, P.; Takigawa, M.; Tarasova, O.; Houweling, S.

2008-12-01

200

Detection of marine methane emissions with AVIRIS band ratios  

NASA Astrophysics Data System (ADS)

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.

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

2011-05-01

201

Preliminary results from measurement of methane at Gosan, Jeju Island, Korea for understanding emissions in East Asia  

NASA Astrophysics Data System (ADS)

Importance of methane (CH4) to the global biogeochemical cycle and climate change has been well documented, and while the total global methane emissions are relatively well known, the strength of each source component and their trends are not, due to the varied biological and anthropogenic sources of emissions. This is especially true in East Asia, where strong expected emissions of CH4 from fossil fuel mining and burning as well as rice agriculture remain less understood. In this study, we present atmospheric measurements of methane and preliminary analysis of the results. Measurement site for this study is at Gosan, a remote background site located on Jeju Island, Korea. Due to its central location in East Asia, monitoring of both background and pollution from the surrounding regions is possible, thus ideal for monitoring methane emissions in East Asia. To facilitate high-quality continuous measurements, an automated measurement system with a GC-FID has been created and tested at Seoul National University. Identification of the dominant CH4 emission sources could be better understood by analyzing correlation with other anthropogenically and biogenically emitted compounds such as CO (important indicator for fossil fuel burning) and chlorinated compounds (emitted from biomass burning and the use of coal). Advanced air mass transport modeling will also be used to analyze different emission patterns by region.

Lee, E.; Kim, J.; Ahn, K.; Park, M.; Kim, K.

2010-12-01

202

Atmospheric observations of Arctic Ocean methane emissions up to 82° north  

NASA Astrophysics Data System (ADS)

Uncertainty in the future atmospheric burden of methane, a potent greenhouse gas, represents an important challenge to the development of realistic climate projections. The Arctic is home to large reservoirs of methane, in the form of permafrost soils and methane hydrates, which are vulnerable to destabilization in a warming climate. Furthermore, methane is produced in the surface ocean and the surface waters of the Arctic Ocean are supersaturated with respect to methane. However, the fate of this oceanic methane is uncertain. Here, we use airborne observations of methane to assess methane efflux from the remote Arctic Ocean, up to latitudes of 82°north. We report layers of increased methane concentrations near the surface ocean, with little or no enhancement in carbon monoxide levels, indicative of a non-combustion source. We further show that high methane concentrations are restricted to areas over open leads and regions with fractional sea-ice cover. Based on the observed gradients in methane concentration, we estimate that sea-air fluxes amount to around 2 mg d-1 m-2, comparable to emissions seen on the Siberian shelf. We suggest that the surface waters of the Arctic Ocean represent a potentially important source of methane, which could prove sensitive to changes in sea-ice cover.

Kort, E. A.; Wofsy, S. C.; Daube, B. C.; Diao, M.; Elkins, J. W.; Gao, R. S.; Hintsa, E. J.; Hurst, D. F.; Jimenez, R.; Moore, F. L.; Spackman, J. R.; Zondlo, M. A.

2012-05-01

203

Landfill operation for carbon sequestration and maximum methane emission control.  

National Technical Information Service (NTIS)

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 gener...

D. Augenstein

1999-01-01

204

Status of worldwide coal mine methane emissions and use  

Microsoft Academic Search

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

Carol J Bibler; James S Marshall; Raymond C Pilcher

1998-01-01

205

Annual cycle of methane emission from a subarctic peatland  

NASA Astrophysics Data System (ADS)

Although much attention in recent years has been devoted to methane (CH4) emissions from northern wetlands, measurement based data sets providing full annual budgets are still limited in number. This study was designed to help fill the gap of year-round measurements of CH4 emissions from subarctic mires. We report continuous eddy correlation CH4 flux measurements made during 2006 and 2007 over the Stordalen mire in subarctic Sweden (68°20'N, 19°03'E, altitude 351 m) using a cryocooled tunable diode laser. The landscape-scale CH4 fluxes originated mainly from the permafrost free wet parts of the mire dominated by tall graminoid vegetation. The midseason average CH4 emission mean was 6.2 ± 2.6 mg m-2 h-1. A detailed footprint analysis indicates an additional strong influence on the flux by the nearby shallow Lake Villasjön (0.17 km2, maximum depth 1.3 m). A stable bimodal distribution of wind flow from either the east or the west allowed separating the lake and mire vegetation signals. The midseason lake emission rates were as high as 12.3 ± 3.3 mg m-2 h-1. Documented CH4 fluxes are similar to results obtained by automatic chamber technique and higher than manual chamber measurements made in the wet minerotrophic section dominated by Eriophorum angustifolium. The high fluxes observed from this vegetation type are significant because the areal distribution of this source in the mire is expanding due to ongoing thawing of the permafrost. A simple peat temperature relationship with CH4 emissions was used to fill data gaps to construct a complete annual budget of CH4 fluxes over the studied area. The calculated annual CH4 emissions in 2006 and 2007 equaled 24.5 and 29.5 g CH4 m-2 yr-1, respectively. The summer season CH4 emissions dominated (65%) the annual flux, with the shoulder seasons of spring and autumn significant (25%) and a minor flux from the winter (10%).

Jackowicz-Korczy?Ski, Marcin; Christensen, Torben R.; BäCkstrand, Kristina; Crill, Patrick; Friborg, Thomas; Mastepanov, Mikhail; StröM, Lena

2010-06-01

206

Comparison of first-order-decay modeled and actual field measured municipal solid waste landfill methane data.  

PubMed

The first-order decay (FOD) model is widely used to estimate landfill gas generation for emissions inventories, life cycle assessments, and regulation. The FOD model has inherent uncertainty due to underlying uncertainty in model parameters and a lack of opportunities to validate it with complete field-scale landfill data sets. The objectives of this paper were to estimate methane generation, fugitive methane emissions, and aggregated collection efficiency for landfills through a mass balance approach using the FOD model for gas generation coupled with literature values for cover-specific collection efficiency and methane oxidation. This study is unique and valuable because actual field data were used in comparison with modeled data. The magnitude and variation of emissions were estimated for three landfills using site-specific model parameters and gas collection data, and compared to vertical radial plume mapping emissions measurements. For the three landfills, the modeling approach slightly under-predicted measured emissions and over-estimated aggregated collection efficiency, but the two approaches yielded statistically equivalent uncertainties expressed as coefficients of variation. Sources of uncertainty include challenges in large-scale field measurement of emissions and spatial and temporal fluctuations in methane flow balance components (generated, collected, oxidized, and emitted methane). Additional publication of sets of field-scale measurement data and methane flow balance components will reduce the uncertainty in future estimates of fugitive emissions. PMID:23988298

Amini, Hamid R; Reinhart, Debra R; Niskanen, Antti

2013-08-26

207

Investigation of methane emission sources from Indianapolis using an aircraft-based platform  

NASA Astrophysics Data System (ADS)

Quantification of the magnitude and uncertainties of greenhouse gas emissions is important for establishing scientifically sound policies for mitigating fossil fuel emissions in urban environments. Recent studies have shown that urban city centers are significant sources of anthropogenic methane. However, urban CH4 fluxes do not correlate with emissions from combustion sources. While the emission inventory for carbon dioxide is relatively well understood, the sources of methane are less defined because of the diverse range of sources and relatively limited observational studies of this potent greenhouse gas. Using cavity ring-down spectroscopy, flask samples, and a mass balance approach, we present initial results of our measurements of methane emissions over the city of Indianapolis using an aircraft-based platform. This investigation, which is part of the Indianapolis Flux Project (INFLUX), will help gain insight into the nature of the uncharacterized sources of methane from this urban center.

Cambaliza, M. L.; Shepson, P. B.; Davis, K. J.; Gurney, K. R.; Lauvaux, T.; Miles, N. L.; Richardson, S.; Sweeney, C.; Turnbull, J. C.; Karion, A.; Mays, K.

2010-12-01

208

Woody stem methane emission in mature wetland alder trees  

NASA Astrophysics Data System (ADS)

Methane (CH 4) is an important greenhouse gas that is predominantly emitted to the atmosphere from anoxic wetland ecosystems. Understanding the sources and emissions of CH 4 is crucially important for climate change predictions; however, there are significant discrepancies between CH 4 source estimates derived via so-called bottom-up and top-down methods. Here we report CH 4 emission from the stems of mature wetland alder ( Alnus glutinosa) trees in the UK, a common tree of northern hemisphere floodplains and wetlands. The alder stems most likely behave as conduits for soil-produced CH 4 either in the gaseous or aqueous phase, and may, therefore, help to reconcile methodological differences in the way the wetland CH 4 source is estimated. Alder tree stems emitted average peak CH 4 fluxes of 101 ?g CH 4 m -2 h -1 (on a stem area basis) in early October, a rate that is similar to that obtained from mature Japanese ash ( Fraxinus mandshurica var. japonica) in Japan and amounting to approximately 20% of the measured CH 4 flux from the soil surface. The finding suggests that trees, which occupy 60% of Earth's wetlands and are normally excluded from the measurement programmes that form the basis for bottom-up estimates of the global wetland source, could be important contributors to overall terrestrial ecosystem CH 4 flux.

Gauci, Vincent; Gowing, David J. G.; Hornibrook, Edward R. C.; Davis, Joanna M.; Dise, Nancy B.

2010-06-01

209

Methane emission from rice fields in relation to management of irrigation water.  

PubMed

A field experiment was conducted for two years to find out best water management practice to mitigate methane emission from the rice-fields. Continuously flooded conditions yielded two major flushes of methane emission and on an average resulted in relatively higher rate of methane emission (2.20 and 1.30 mg m(-2) hr(-1), respectively in 2005 and 2006) during the kharif season. The methane flux was reduced to half (1.02 and 0.47 mg m(-2) hr(-1), respectively in 2005 and 2006) when rice fields were irrigated 2-3 days after infiltration of flood water into the soil. Irrigating the field at 0.15 bar matric potential reduced seasonal methane flux by 60% (0.99 and 0.41 mg m(-2) hr(-1), respectively in 2005 and 2006) as compared to completely flooded conditions, without any decline in grain yield (60 q ha(-1)). PMID:21882650

Khosa, Maninder Kaur; Sidhu, B S; Benbi, D K

2011-03-01

210

Development of atmospheric tracer methods to measure methane emissions from natural gas facilities and urban areas  

SciTech Connect

A new, integrated methodology to locate and measure methane emissions from natural gas systems has been developed. Atmospheric methane sources are identified by elevated ambient CH{sub 4} concentrations meaured with a mobile laser-based methane analyzer. The total methane emission rate from a source is obtained by simulating the source with a sulfur hexafluoride (SF{sub 6}) tracer gas release and by measuring methane and tracer concentrations along downwind sampling paths using mobile, real-time analyzers. Combustion sources of methane are distinguished from noncombustion sources by concurrent ambient carbon dioxide measurements. Three variations on the tracer ratio method are described for application to (1) small underground vaults, (2) above-ground natural gas facilities, and (3) diffuse methane emissions from an entire town. Results from controlled releases and from replicate tests demonstrate that the tracer ratio approach can yield total emission rates to within approximately {+-}15%. The estimated accuracy of emission estimates for urban areas with a variety of diffuse emissions is {+-}50%. 21 refs., 5 figs., 6 tabs.

Lamb, B.K.; Allwine, E.; Siverson, R.; Westberg, H. [Washington State Univ., Pullman, WA (United States); McManus, J.B.; Kolb, C.B.; Shorter, J.H. [Aerodyne Research, Inc., Billerica, MA (United States); Mosher, B.; Blaha, D.; Harris, R.C. [Univ. of New Hampshire, Durham, NH (United States)] [and others

1995-06-01

211

Development of methane emission factors for Indian paddy fields and estimation of national methane budget.  

PubMed

A state-wise assessment of methane (CH(4)) budget for Indian paddies, based on a decadal measurement data across India is presented for the calendar year (CY) 1994, the base year for India's Initial National Communication (NATCOM) to the United Nations Framework Convention on Climate Change (UNFCCC), along with national trend from CY 1979 to 2006. The NATCOM CH(4) emission factors (EFs) for Indian paddy cultivation areas, generally having less than 0.7% of soil organic carbon (SOC), have been estimated as 17.48+/-4 g m(-2) for irrigated continuously flooded (IR-CF), 6.95+/-1.86 g m(-2) for rain-fed drought prone (RF-DP), 19+/-6 g m(-2) for rain-fed flood prone (RF-FP) and deep-water (DW), 6.62+/-1.89 g m(-2) for irrigated intermittently flooded single aeration (IR-IF-SA) and 2.01+/-1.49 g m(-2) for IR-IF multiple aeration (MA) paddy water regimes. The state-wise study for 1994 has indicated national CH(4) budget estimate of 4.09+/-1.19 Tg y(-1) and the trend from 1979 to 2006 was in the range of 3.62+/-1 to 4.09+/-1.19 Tg y(-1). Four higher emitting or "hot spot" states (West Bengal, Bihar, Madhya Pradesh and Uttar Pradesh) have accounted for 53.9% of total CH(4) emission with RF-FP paddy water regime as the major contributor. CH(4) emissions were enhanced by factors such as SOC ( approximately 1.5 times due to increase in SOC by approximately 1.8 times), paddy cultivars (approximately 1.5 times), age of seedlings (approximately 1.4 times), and seasons (approximately 1.8 times in Kharif or monsoon than in Rabi or winter season). PMID:18996564

Gupta, Prabhat K; Gupta, Vandana; Sharma, C; Das, S N; Purkait, N; Adhya, T K; Pathak, H; Ramesh, R; Baruah, K K; Venkatratnam, L; Singh, Gulab; Iyer, C S P

2008-11-08

212

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

Microsoft Academic Search

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

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

2008-01-01

213

The Top-Down View of Natural Global Methane Emissions  

NASA Astrophysics Data System (ADS)

Recent assessments of natural emissions of CH4 are in the range of 145-260 TgCH4/yr globally (25-50% of the total global CH4 emissions); a large range in uncertainty. Natural emissions of CH4 depend on the local environment through soil moisture, carbon content and temperature, and the type of vegetation present. All of these parameters are sensitive to climate variability, and given potency of CH4 as a greenhouse gas, long-term trends in natural emissions may be important climate feedbacks. Top-down inverse approaches can potentially allow quantification of CH4 emissions at continental and even regional scales. They are, however, significantly limited by current sparse spatial coverage of observations. Detection of trends in emissions is especially problematic since lack of spatial redundancy in observational networks makes inverse flux estimates sensitive to network changes. At present, satellite observations have not significantly improved top-down methods even though they potentially offer dense data coverage. As a result, inverse flux estimates are very dependent on prior flux estimates based on field measurements or process models of wetland ecosystems. The distributions of estimated fluxes are strongly constrained by the distribution of prior emissions. In the case of wetland ecosystems, the distribution of wetlands is usually fixed and this poses an additional challenge for the deduction of emission trends. It is interesting to note that some process models have predicted increases in natural emissions related to temperature increases over the past decades, however, it is difficult to find this signal in global network observations. In addition, it is difficult to reconcile increases in natural emissions and bottom-up estimates of increased anthropogenic emissions with what is known about the photochemical loss of CH4 and observed global trends. CarbonTracker-CH4 was recently developed as a companion information product to the NOAA Earth System Research Laboratory's CarbonTracker (CO2). Although spatial resolution of sources is limited in the tropics, the recent increases in tropical wetland sources are represented, though not necessarily distinct from rice emissions. On the other hand, at high-northern latitudes, where observational coverage is better, the inversion is apparently able to discriminate between wetland emissions from Eastern Siberia and Alaska. It is notable that when constant anthropogenic emissions were used as prior flux estimates, the inversions did not produce a trend as suggested by bottom-up inventories.

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

2011-12-01

214

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

NASA Astrophysics Data System (ADS)

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

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

215

Methane emissions at nine landfill sites in the northeastern United States  

SciTech Connect

Methane emissions were measured at nine US landfill sites using chamber and/or tracer flux techniques. These flux measurement methodologies were compared at two sites, and excellent agreement was observed. Total methane emissions ranged from 540 to 30 100 L min[sup [minus]1]. Expressed on an area basis, methane fluxes ranged from a low of 9.1 g of CH[sub 4] m[sup [minus]2] d[sup [minus]1] at a closed 20-ha site with active gas recovery to 130 g of CH[sub 4] m[sup [minus]2] d[sup [minus]1] at a 23-ha active site with no gas recovery. Methane emission factors were calculated for seven of the nine sites. The two sites with no active gas recovery exhibited the highest emission factors of 4.8 and 5.1. Values were significantly lower at three sites with partial gas recovery, ranging from 1.6 to 3.7. At the two closed sites with active gas recovery, emission factors were much lower still. It is evident that even partial gas recovery at active landfill sites can significantly reduce methane emissions, and gas recovery at closed, covered sites reduces methane emissions to the atmosphere by as much as a factor of 10.

Mosher, B.W.; Czepiel, P.M.; Harriss, R.C. (Univ. of New Hampshire, Durham, NH (United States). Complex Systems Research Center); Shorter, J.H.; Kolb, C.E.; McManus, J.B. (Aerodyne Research, Inc., Billerica, MA (United States). Center for Atmospheric and Environmental Chemistry); Allwine, E.; Lamb, B.K. (Washington State Univ., Pullman, WA (United States))

1999-06-15

216

Modeling of Large Methane Releases and their affect on the Chemistry of the Atmosphere  

NASA Astrophysics Data System (ADS)

A vast quantity of methane is locked in solid phase as methane clathrates in ocean sediments (as much carbon as all other fossil fuels combined). Rapid destabilization of the clathrates due to climate warming would significantly increase methane emissions from the ocean. This would result in a number of affects including strong greenhouse heating, increased surface ozone, reduced stratospheric ozone, and intensification of the ozone hole. Many of the affects in the chemistry of the atmosphere are non-linear and difficult to estimate without a detailed model. As part of the DOE IMPACTS project on abrupt climate change we have used our 3D global atmospheric chemistry model (IMPACT) to take a first look at some of these affects. This model includes detailed chemistry of the troposphere (including isoprene and other hydrocarbons) and the stratosphere (including the important chlorine and bromine compounds). We ran the model at 4x5 degree resolution with methane simply scaled to present day emissions. We show results for 1x, 2x, 10x, 100x, and 1000x emission scenarios. We analyzed the results after the simulations have reached steady state (many years of simulation) and show the affect of these large releases on tropospheric air quality, the “health” of the stratosphere, and greenhouse heating. Substantial increases were seen in atmospheric methane lifetime, a positive feedback, due to the increased methane reducing the OH concentration. In the future we will couple our atmospheric chemistry to a complete Earth system model (based on CCSM) for methane including ocean ecosystem, ocean sediment and boreal land models to give more accurate estimates of the emission term and to look at the full system response.

Bergmann, D. J.; Cameron-Smith, P. J.; Elliot, S.; Reagan, M. T.; Maltrud, M. E.

2009-12-01

217

Control of the Diurnal Pattern of Methane Emission from Emergent Aquatic Macrophytes by Gas Transport Mechanisms.  

National Technical Information Service (NTIS)

Methane emissions from Typha latifolia (L.) showed a large mid-morning transient peak associated with rising light levels. This peak was also associated with a steep decline in lacunal CH, concentrations near the stem base. This pattern contrasted sharply...

G. J. Whiting J. P. Chanton

1995-01-01

218

Guidelines for the Prediction and Control of Methane Emissions on Longwalls.  

National Technical Information Service (NTIS)

Although longwall mining productivity can far exceed that of room-and-pillar mining, the total methane emissions per extracted volume associated with longwall sections are generally higher than those for continuous miner or pillar removal sections. Increa...

C. Ozgen-Karacan G. S. Esterhuizen G. V. R. Goodman R. B. Krog S. J. Schatzel

2008-01-01

219

Methane emissions from a freshwater marsh in response to experimentally simulated global warming and nitrogen enrichment  

NASA Astrophysics Data System (ADS)

We determined methane (CH4) emissions in a field enclosure experiment in a littoral freshwater marsh under the influence of experimentally simulated warming and enhanced nitrogen deposition. Methane emissions by ebullition from the marsh composed of Phragmites australis were measured with funnel traps deployed in a series of enclosures for two 3 week periods. Diffusive fluxes were estimated on the basis of measured CH4 concentrations and application of Fick's law. Neither diffusive nor ebullitive fluxes of methane were significantly affected by warming or nitrate enrichment, possibly because variability both within and among replicate experimental enclosures was high. Average emission rates resulted primarily from ebullition (0.2-30.3 mmol CH4 m-2 d-1), which were 4 orders of magnitude higher than estimated diffusive fluxes and were of similar importance as the coarsely estimated advective methane transport through plants. Significant correlations between dissolved oxygen and dissolved methane and ebullition flux suggest that methane release from the sediment might feed back positively on methane production by reducing dissolved oxygen in the water column and oxygen flux into the sediment. Nitrate may have a similar effect. Extrapolation of our limited data indicates that total methane fluxes from vegetated littoral zones of temperate lakes may contribute 0.5%-7% of the global natural CH4 emissions. These results emphasize the importance of freshwater marshes as sources of methane emissions to the atmosphere, even when they occupy only relatively small littoral areas. More detailed investigations are clearly needed to assess whether global warming and nitrogen deposition can have climate feedbacks by altering methane fluxes from these wetlands.

Flury, Sabine; McGinnis, Daniel F.; Gessner, Mark O.

2010-03-01

220

Seasonal variation in methane emissions from an interior Alaska thermokarst lake  

NASA Astrophysics Data System (ADS)

Refining our knowledge of methane cycling in aquatic ecosystems and their emissions to the atmosphere is important for understanding their role in climate change. The contribution of northern high latitude lakes to terrestrial methane emissions has recently been recognized as significant, and is likely to contribute a positive feedback to increasing atmospheric temperatures. The data available for accurately defining seasonal and net annual methane emissions from northern high latitude lakes are presently limited by a seasonal imbalance in both gross and net production measurements, as well as a poor understanding of emissions pathways and geographic differences. To help fill in some of these data gaps, we conducted intensive year-round measurement of ebullition and diffusive methane flux from Goldstream Lake (informal name), a thermokarst lake in central Alaska. Additionally, we made less frequent measurements on 47 lakes in winter and summer along a latitudinal transect in Alaska from the Kenai Peninsula to Prudhoe Bay. We used several methods to measure methane flux over multiple seasons in order to better understand complexity in the fate and transport of methane. These include (i) static chamber measurements of seep ebullition, (ii) documentation of the fate of gas trapped in winter ice, (iii) dissolved gas measurements by both gas chromatography and Tunable Diode Laser Absorption Spectroscopy, and(iv) measurement of methane concentration in air above the lake surface by a LiCor 7700 Open Path Methane Analyzer. Of specific interest was seasonal variation in methane emissions and the fate of winter methane production, whose release to the atmosphere is restricted for seven months by increasingly thick ice cover.

Strohm, A. J.; Walter Anthony, K.; Thalasso, F.; Sepulveda-Jauregui, A.; Martinez Cruz, K. C.; Dove, K. L.

2011-12-01

221

Methane Emission from Irrigated and Intensively Managed Rice Fields in Central Luzon (Philippines)  

Microsoft Academic Search

Methane (CH4) emissions were measured with an automated system in Central Luzon, the major rice producing area of the Philippines. Emission records covered nine consecutive seasons from 1994 to 1998 and showed a distinct seasonal pattern: an early flush of CH4 before transplanting, an increasing trend in emission rates reaching maximum toward grain ripening, and a second flush after water

T. M. Corton; J. B. Bajita; F. S. Grospe; R. R. Pamplona; C. A. Assis; R. Wassmann; R. S. Lantin; L. V. Buendia

2000-01-01

222

IM PROVING THE ACCURACY OF SELECTING ANIMALS FOR REDUCED METHANE EMISSIONS  

Microsoft Academic Search

SUMMARY Enteric methane emissions of livestock represent 10.3% of Australia's greenhouse gas emis- sions, so it is important to identify low-emitting animals in order to study the mechanisms that lead to low emissions relative to production. This will require field testing of large numbers of animals to identify those with the lowest emissions, and at the same time generate useful

D. L. Robinson

223

Estimation and field measurement of methane emission from waste landfills in Hanoi, Vietnam  

Microsoft Academic Search

A methodology for estimating the methane emissions from waste landfills in Hanoi, Vietnam, as part of a case study on Asian\\u000a cities, was derived based on a survey of documents and statistics related to waste management, interviews with persons in\\u000a charge, and field investigations at landfill sites. The waste management system in Hanoi was analyzed to evaluate the methane\\u000a emissions

Tomonori Ishigaki; Chu Van Chung; Nguyen Nhu Sang; Michihiko Ike; Koji Otsuka; Masato Yamada; Yuzo Inoue

2008-01-01

224

Alternative tracer gases for the ERUCT technique to estimate methane emission from grazing animals  

Microsoft Academic Search

The methane emission of grazing ruminants can be estimated using the Emissions from Ruminants Using a Calibrated Tracer (ERUCT) technique by applying sulphur hexafluoride (SF6) in low-release permeation tubes. The low background concentration of SF6 coupled with its low detection limits and solubility similar to methane made SF6 a good tracer. However, discovery of alternative tracer gases is desirable since

A. Machmüller; R. S. Hegarty

2006-01-01

225

Emissions of Nitrous Oxide and Methane from Conventional and Alternative Fuel Motor Vehicles  

Microsoft Academic Search

This paper provides estimates of emissions of two important but often not well-characterized greenhouse gas (GHG) emissions related to transportation energy use: methane (CH4) and nitrous oxide (N2O). The paper focuses on emissions of CH4 and N2O from motor vehicles because unlike emissions of CO2, which are relatively easy to estimate, emissions of CH4 and N2O are a function of

Timothy E. Lipman; Mark A. Delucchi

2002-01-01

226

Spatial profiles of methane at the Swiss Plateau: A confrontation between measurements and emission inventories.  

NASA Astrophysics Data System (ADS)

Methane and carbon dioxide are the two most prominent greenhouse gases in the atmosphere and a detailed knowledge about their sources is essential for climate predictions (Solomon et al., 2007). The knowledge about greenhouse gas fluxes is usually merged, albeit including considerable uncertainties, to emission inventories. To increase the quality of the inventories a comparison with measurements is necessary. We evaluate the values given by a Swiss emission inventory with regard to atmospheric measurements of methane in Switzerland. Spatial profiles of carbon dioxide and methane were investigated at the Swiss Plateau during two consecutive warm and sunny summer days in July 2012. For the mobile methane and carbon dioxide measurements a LGR methane analyser and a LI-COR closed-path infrared gas analyser (IRGA) were mounted on a car together with an AIRMAR WeatherStation to track geodetic-coordinates and meteorological parameters. First results of the measurements including aerial profiles of the greenhouse gases and bin-averaged elevation profiles of methane and temperature will be presented and a highly-resolved methane emission inventory will be evaluated in comparison with the spatial profiles of atmospheric methane at the Swiss Plateau. References: Solomon, S., Qin D., et al. (Eds.) (2007) Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 996 S. pp., Cambridge University Press, Cambridge.

Bamberger, Ines; Eugster, Werner; Buchmann, Nina

2013-04-01

227

Ultraviolet radiation drives methane emissions from terrestrial plant pectins.  

PubMed

Recent studies demonstrating an in situ formation of methane (CH(4)) within foliage and separate observations that soil-derived CH(4) can be released from the stems of trees have continued the debate about the role of vegetation in CH(4) emissions to the atmosphere. Here, a study of the role of ultraviolet (UV) radiation in the formation of CH(4) and other trace gases from plant pectins in vitro and from leaves of tobacco (Nicotiana tabacum) in planta is reported. Plant pectins were investigated for CH(4 )production under UV irradiation before and after de-methylesterification and with and without the singlet oxygen scavenger 1,4-diazabicyclo[2.2.2]octane (DABCO). Leaves of tobacco were also investigated under UV irradiation and following leaf infiltration with the singlet oxygen generator rose bengal or the bacterial pathogen Pseudomonas syringae. Results demonstrated production of CH(4), ethane and ethylene from pectins and from tobacco leaves following all treatments, that methyl-ester groups of pectin are a source of CH(4), and that reactive oxygen species (ROS) arising from environmental stresses have a potential role in mechanisms of CH(4) formation. Rates of CH(4 )production were lower than those previously reported for intact plants in sunlight but the results clearly show that foliage can emit CH(4) under aerobic conditions. PMID:18657215

McLeod, Andy R; Fry, Stephen C; Loake, Gary J; Messenger, David J; Reay, David S; Smith, Keith A; Yun, Byung-Wook

2008-07-24

228

Reducing the environmental impact of methane emissions from dairy farms by anaerobic digestion of cattle waste.  

PubMed

Four dairy cattle farms considered representative of Northern Spain milk production were studied. Cattle waste was characterised and energy consumption in the farms was inventoried. Methane emissions due to slurry/manure management and fuel consumption on the farms were calculated. The possibility of applying anaerobic digestion to the slurry to minimise emissions and of using the biogas produced to replace fossil fuels on the farm was considered. Methane emissions due to slurry management (storage and use as fertiliser) ranged from 34 to 66kg CH(4)cow(-1)year(-1) for dairy cows and from 13 to 25kg CH(4)cow(-1)year(-1) for suckler calves. Cattle on these farms are housed for most of the year, and the contribution from emissions from manure dropped in pastures is insignificant due to the very low methane conversion factors. If anaerobic digestion were implemented on the farms, the potential GHG emissions savings per livestock unit would range from 978 to 1776kg CO(2)eq year(-1), with the main savings due to avoided methane emissions during slurry management. The methane produced would be sufficient to supply digester heating needs (35-55% of the total methane produced) and on-farm fuel energy requirements. PMID:21504844

Marañón, E; Salter, A M; Castrillón, L; Heaven, S; Fernández-Nava, Y

2011-04-19

229

Preliminary report on methane emissions from the Three Gorges Reservoir in the summer drainage period.  

PubMed

Recently reported summertime methane (CH4) emissions (6.7 +/- 13.3 mg CH4/(m2 x hr)) from newly created marshes in the drawdown area of the Three Gorges Reservoir (TGR), China have triggered broad concern in academic circles and among the public. The CH4 emissions from TGR water surfaces and drawdown areas were monitored from 3rd June to 16th October 2010 with floating and static chambers and gas chromatography. The average CH4 emission flux from permanently flooded areas in Zigui, Wushan and Yunyang Counties was (0.33 +/- 0.09) mg CH4/(m2 x hr). In half of these hottest months of the year, the wilderness, cropland and deforested drawdown sites were aerobic and located above water level, and the CH4 emissions were very small, ranging from a sink at 0.12 mg CH4/(m2 x hr) to a source at 0.08 mg CH4/(m2 x hr) except for one mud-covered site after flood. Mean CH4 emission in flooded drawdown sites was 0.34 mg CH4/(m2 x hr). The emissions from the rice paddy sites in the drawdown area were averaged at (4.86 +/- 2.31) mg CH4/(m2 x hr). Excepting the rice-paddy sites, these results show much lower emission levels than previously reported. Our results indicated considerable spatial and temporal variation in CH4 emissions from the TGR. Human activities and occasional events, such as flood, may also affect emission levels. Long-term CH4 measurements and modeling in a large region are necessary to accurately estimate greenhouse gas emissions from the TGR. PMID:22432334

Lu, Fei; Yang, Le; Wang, Xiaoke; Duan, Xiaonan; Mu, Yujing; Song, Wenzhi; Zheng, Feixiang; Niu, Junfeng; Tong, Lei; Zheng, Hua; Zhou, Yongjuan; Qiu, Jiangxiao; Ouyang, Zhiyun

2011-01-01

230

Fallow season straw and water management effects on methane emissions in California rice  

NASA Astrophysics Data System (ADS)

In response to legislative mandate to reduce postharvest straw burning and environmental concerns to restore wetland habitat for Pacific flyway waterfowl, California rice growers are incorporating straw into soil and flooding rice fields in winter. These changes were hypothesized to alter soil carbon cycling pathways across the region. The principal objective of this study was to determine how various winter fallowed straw and water management changes would affect year-round methane emissions. Main plots were winter flood and nonflood, and subplots had straw treatments: burned, soil incorporated, or rolled (partially soil incorporated). Results showed the principal factor controlling methane emissions was the interaction of flooding and straw amendments. The presence of either water or straw alone led to low emissions. Winter emissions accounted for 50% of annual totals in straw-amended treatments despite lower temperatures and the presence of plants in summer. Summer emissions were significantly influenced by winter straw amendments but not by winter flood. Postdrain peaks after winter drain accounted for 10-13% of annual emissions in treatments with amended straw. Although rolled and incorporated treatments had similar straw inputs, methane fluxes from rolled treatments were higher than from incorporated treatments. Measurements of methane should be conducted year-round to capture fallow and postdrain fluxes and improve global emission estimates. Regional emission estimates showed that 2.6 times more methane was emitted after flooding plus incorporation was implemented than before the legislative mandate was enacted.

Fitzgerald, G. J.; Scow, K. M.; Hill, J. E.

2000-09-01

231

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

SciTech Connect

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

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

2002-12-03

232

Seasonal Production and Emission of Methane from Rice Fields.  

National Technical Information Service (NTIS)

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 d...

M. A. K. Khalil R. A. Rasmussen L. Ren M. Wang M. J. Shearer R. W. Dalluge C. Duan

2003-01-01

233

Methane emissions from lakes and floodplains in Pantanal, Brazil  

NASA Astrophysics Data System (ADS)

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.

Marani, L.; Alvalá, P. C.

234

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

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

235

Retrieval of methane source strengths in Europe using a simple modeling approach to assess the potential of space-borne lidar observations  

NASA Astrophysics Data System (ADS)

We investigate the sensitivity of future space-borne lidar measurements to changes in surface methane emissions. We use surface methane observations from nine European ground stations, and a Lagrangian transport model to obtain surface methane emissions for 2010. Our inversion shows the strongest emissions from the Netherlands, the coalmines in Upper Silesia Poland, and wetlands in southern Finland. Our simulated methane surface concentration captures 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 perturb the surface fluxes and see the resulting changes in the simulated column methane measurements. For example, we show that future lidar instruments can detect a 50% reduction in methane emissions from the Netherlands and Germany, but only after averaging measurements on a monthly time scale.

Weaver, C.; Kiemle, C.; Kawa, S. R.; Aalto, T.; Necki, J.; Steinbacher, M.; Arduini, J.; Apadula, F.; Berkhout, H.; Hatakka, J.; O'Doherty, S.

2013-07-01

236

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

PubMed

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

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

237

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

NASA Astrophysics Data System (ADS)

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.

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

238

A 3D Microphysical Model of Titan's Methane Cloud  

NASA Astrophysics Data System (ADS)

A time-dependent idealized 3D microphysical model for Titan's methane cloud is described. This new high resolution microphysical model nests in a Titan WRF GCM model. It assumes the vapor-liquid equilibria of methane-nitrogen mixtures which are based on the recent chemical experiments and thermodynamics models. In particular, the methane is condensed at a given temperature and pressure. Meanwhile nitrogen is dissolved in the methane liquid. The new model first uses the data from the thermodynamic model (Kouvaris et al. 1991), which involves saturation criteria, composition of condensate, and latent heat for a given pressure-temperature profile. For altitudes lower than 14 km, methane is saturated and condensed into liquid phase. However for altitudes from 14 km above to tropopause, methane is changed into supercooled liquid state. Then, we do some testing experiments with 1D model by varying the initial methane vapor mass mixing ratio profile and the initial mole fraction of methane in liquid phase. Based on the steady state results from 1D model, an idealized 3D microphysics model is developed to investigate the convection cloud in Titan's troposphere. Due to lower relative humidity at titan's surface (Samuelson et al. 1997) and the current estimated moist adiabatic lapse rate, convection is hardly to happen without lifting. For this reason, we apply a symmetry cosine ridge in a 100*100 grids box to force the air flow lifted at certain levels, which in turn drives the condensation of methane vapor. In addition to the abundance of methane clouds and its duration provided by the 3D model, our study demonstrates that vertical motion might be likely the major cause of convection clouds in Titan's troposphere. As the future work, we will further investigate size-resolved microphysical scheme to insight into the nature of methane cycle in Titan's atmosphere.

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

2006-12-01

239

Climate versus emission drivers of methane lifetime against loss by tropospheric OH from 1860-2100  

NASA Astrophysics Data System (ADS)

With a more-than-doubling in the atmospheric abundance of the potent greenhouse gas methane (CH4) since preindustrial times, and indications of renewed growth following a leveling off in recent years, questions arise as to future trends and resulting climate and public health impacts from continued growth without mitigation. Changes in atmospheric methane lifetime are determined by factors which regulate the abundance of OH, the primary methane removal mechanism, including changes in CH4 itself. We investigate the role of emissions of short-lived species and climate in determining the evolution of methane lifetime against loss by tropospheric OH, (?CH4_OH), in a suite of historical (1860-2005) and future Representative Concentration Pathway (RCP) simulations (2006-2100), conducted with the Geophysical Fluid Dynamics Laboratory (GFDL) fully coupled chemistry-climate model (CM3). From preindustrial to present, CM3 simulates an overall 5% increase in ?CH4_OH due to a doubling of the methane burden which offsets coincident increases in nitrogen oxide (NOx emissions. Over the last two decades, however, the ?CH4_OH declines steadily, coinciding with the most rapid climate warming and observed slow-down in CH4 growth rates, reflecting a possible negative feedback through the CH4 sink. Sensitivity simulations with CM3 suggest that the aerosol indirect effect (aerosol-cloud interactions) plays a significant role in cooling the CM3 climate. The projected decline in aerosols under all RCPs contributes to climate warming over the 21st century, which influences the future evolution of OH concentration and ?CH4_OH. Projected changes in ?CH4_OH from 2006 to 2100 range from -13% to +4%. The only projected increase occurs in the most extreme warming case (RCP8.5) due to the near-doubling of the CH4 abundance, reflecting a positive feedback on the climate system. The largest decrease occurs in the RCP4.5 scenario due to changes in short-lived climate forcing agents which reinforce climate warming and enhance OH. This decrease is more-than-halved in a sensitivity simulation in which only well-mixed greenhouse gas radiative forcing changes along the RCP4.5 scenario (5% vs. 13%).

John, J. G.; Fiore, A. M.; Naik, V.; Horowitz, L. W.; Dunne, J. P.

2012-12-01

240

A conduit dilation model of methane venting from lake sediments  

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

241

A conduit dilation model of methane venting from lake sediments  

USGS Publications Warehouse

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.

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

2011-01-01

242

Global health benefits of mitigating ozone pollution with methane emission controls  

NASA Astrophysics Data System (ADS)

Methane (CH4) contributes to the growing global background concentration of tropospheric ozone (O3), an air pollutant associated with premature mortality. Methane and ozone are also important greenhouse gases. Reducing methane emissions therefore decreases surface ozone everywhere while slowing climate warming, but although methane mitigation has been considered to address climate change, it has not for air quality. Here we show that global decreases in surface ozone concentrations, due to methane mitigation, result in substantial and widespread decreases in premature human mortality. Reducing global anthropogenic methane emissions by 20% beginning in 2010 would decrease the average daily maximum 8-h surface ozone by 1 part per billion by volume globally. By using epidemiologic ozone-mortality relationships, this ozone reduction is estimated to prevent 30,000 premature all-cause mortalities globally in 2030, and 370,000 between 2010 and 2030. If only cardiovascular and respiratory mortalities are considered, 17,000 global mortalities can be avoided in 2030. The marginal cost-effectiveness of this 20% methane reduction is estimated to be 420,000 per avoided mortality. If avoided mortalities are valued at 1 million each, the benefit is 240 per tonne of CH4 (12 per tonne of CO2 equivalent), which exceeds the marginal cost of the methane reduction. These estimated air pollution ancillary benefits of climate-motivated methane emission reductions are comparable with those estimated previously for CO2. Methane mitigation offers a unique opportunity to improve air quality globally and can be a cost-effective component of international ozone management, bringing multiple benefits for air quality, public health, agriculture, climate, and energy. human health | mortality | tropospheric ozone | air quality


West, J. Jason; Fiore, Arlene M.; Horowitz, Larry W.; Mauzerall, Denise L.

2006-03-01

243

Quantifying the effect of oxidation on landfill methane emissions  

NASA Astrophysics Data System (ADS)

Field, laboratory, and computer modeling methods were utilized to quantitatively assess the capability of aerobic microorganisms to oxidize landfill-derived methane (CH4) in cover soils. The investigated municipal landfill, located in Nashua, New Hampshire, was operating without gas controls of any type at the time of sample collection. Soil samples from locations of CH4 flux to the atmosphere were returned to the laboratory and subjected to incubation experiments to quantify the response of oxidation in these soils to temperature, soil moisture, in situ CH4 mixing ratio, soil depth, and oxygen. The mathematical representations of the observed oxidation reponses were combined with measured and predicted soil characteristics in a computer model to predict the rate of CH4 oxidation in the soils at the locations of the measured fluxes described by Czepiel et al. [this issue]. The estimated whole landfill oxidation rate at the time of the flux measurements in October 1994 was 20%. Local air temperature and precipitation data were then used in conjunction with an existing soil climate model to estimate an annual whole landfill oxidation rate in 1994 of 10%.

Czepiel, P. M.; Mosher, B.; Crill, P. M.; Harriss, R. C.

1996-07-01

244

Methane emissions from the natural gas industry. Report for May-December 1992  

Microsoft Academic Search

The paper discusses a project to quantify methane (CH4) emissions from the U.S. natural gas industry. The study will measure or calculate all gas industry CH4 emissions--from production at the wellhead, through the system, to the customer's meter. Emissions downstream of the consumer's meter, such as the end-user's burner emissions, are not included. When these data are combined with data

M. R. Harrison; R. M. Cowgill; L. M. Campbell; R. A. Lott

1993-01-01

245

Airborne observations of methane emissions from rice cultivation in the Sacramento Valley of California  

NASA Astrophysics Data System (ADS)

Airborne measurements of methane (CH4) and carbon dioxide (CO2) were taken over the rice growing region of California's Sacramento Valley in the late spring of 2010 and 2011. From these and ancillary measurements, we show that CH4 mixing ratios were higher in the planetary boundary layer above the Sacramento Valley during the rice growing season than they were before it, which we attribute to emissions from rice paddies. We derive daytime emission fluxes of CH4 between 0.6 and 2.0% of the CO2 taken up by photosynthesis on a per carbon, or mole to mole, basis. We also use a mixing model to determine an average CH4/CO2 flux ratio of -0.6% for one day early in the growing season of 2010. We conclude the CH4/CO2 flux ratio estimates from a single rice field in a previous study are representative of rice fields in the Sacramento Valley. If generally true, the California Air Resources Board (CARB) greenhouse gas inventory emission rate of 2.7 × 1010 g CH4/yr is approximately three times lower than the range of probable CH4 emissions (7.8-9.3 × 1010 g CH4/yr) from rice cultivation derived in this study. We attribute this difference to decreased burning of the residual rice crop since 1991, which leads to an increase in CH4 emissions from rice paddies in succeeding years, but which is not accounted for in the CARB inventory.

Peischl, J.; Ryerson, T. B.; Holloway, J. S.; Trainer, M.; Andrews, A. E.; Atlas, E. L.; Blake, D. R.; Daube, B. C.; Dlugokencky, E. J.; Fischer, M. L.; Goldstein, A. H.; Guha, A.; Karl, T.; Kofler, J.; Kosciuch, E.; Misztal, P. K.; Perring, A. E.; Pollack, I. B.; Santoni, G. W.; Schwarz, J. P.; Spackman, J. R.; Wofsy, S. C.; Parrish, D. D.

2012-12-01

246

Evaluation of fluidized-bed methanation catalysts and reactor modeling  

Microsoft Academic Search

The simple reactor model developed for the fluidized-bed methanator PEDU gives reasonably good parity plots for six PEDU tests using six different catalysts. This model can be used to predict the performance of the pilot plant methanator and as a building block in any computerized simulation of the BI-GAS process for process development, design or optimization purposes. Some refinements could

James T. Cobb; Robert C. Streeter

1979-01-01

247

Estimation of methane and nitrous oxide emission from paddy fields and uplands during 1990–2000 in Taiwan  

Microsoft Academic Search

To investigate the greenhouse gases emissions from paddy fields and uplands, methane and nitrous oxide emissions were estimated from local measurement and the IPCC guidelines during 1990–2000 in Taiwan. Annual methane emission from 182807 to 242298 ha of paddy field in the first crop season ranged from 8062 to 12066 ton, and it was between 16261 and 25007 ton for

Shang-Shyng Yang; Chung-Ming Liu; Chao-Ming Lai; Yen-Lan Liu

2003-01-01

248

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

PubMed

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

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

2013-09-16

249

Variability in methane emissions from wetlands at northern treeline near Churchill, Manitoba, Canada  

SciTech Connect

This paper reports on a 2-yr study of methane emissions to the atmosphere made in a high subarctic wetland region at treeline near Churchill, Manitoba. Emissions were monitored from a treed bog, tundra fens, a coastal marsh and shallow ponds, which are wetland terrain types that dominate the region. There were substantial emissions from the fens, marsh, and ponds but very small emissions from the bog. Variability was large, both spatially and temporally. This included variability in measurements at a specific site, between sites, over the course of a single season and between years. Such variability was a response to edaphic factors which control methane production and consumption, differences in ground water levels and pond depths which determine whether conditions are aerobic or anaerobic, and variability in air and soil temperatures. During the cool, most summer of 1990 there were moderate to strong correlations of log normalized methane emissions with depth to water table or pond depth and with air temperature. In the warmer and drier summer of 1989 correlations were more weakly developed. Some of this behavior is explainable by the relation between methane production under anaerobic conditions and consumption under aerobic conditions. During 1990, the methane production on a site by site basis was comparable to coincident measurements made in the southern Hudson Bay Lowland and in the mid-boreal region of Ontario. In 1989, the emissions were about three-fold less than in 1990. 26 refs., 6 figs., 6 tabs.

Rouse, W.R.; Holland, S. [McMaster Univ., Ontario (Canada); Moore, T.R. [McGill Univ., Quebec (Canada)

1995-05-01

250

The Genome Sequence of the Rumen Methanogen Methanobrevibacter ruminantium Reveals New Possibilities for Controlling Ruminant Methane Emissions  

Microsoft Academic Search

BackgroundMethane (CH4) is a potent greenhouse gas (GHG), having a global warming potential 21 times that of carbon dioxide (CO2). Methane emissions from agriculture represent around 40% of the emissions produced by human-related activities, the single largest source being enteric fermentation, mainly in ruminant livestock. Technologies to reduce these emissions are lacking. Ruminant methane is formed by the action of

Sinead C. Leahy; William J. Kelly; Eric Altermann; Ron S. Ronimus; Carl J. Yeoman; Diana M. Pacheco; Dong Li; Zhanhao Kong; Sharla McTavish; Carrie Sang; Suzanne C. Lambie; Peter H. Janssen; Debjit Dey; Graeme T. Attwood; Niyaz Ahmed

2010-01-01

251

Fates of methane from different lake habitats: Connecting whole-lake budgets and CH4 emissions  

NASA Astrophysics Data System (ADS)

Methane (CH4) represents a major product of organic matter decomposition in lakes. Once produced in the sediments, CH4 can be either oxidized or emitted as a greenhouse gas to the atmosphere. Lakes represent an important source of atmospheric CH4, but the relative magnitudes of the internal pathways that lead to CH4 emissions are not yet clear. We quantified internal cycling and methane emissions in three lakes during summer stratification. These methane budgets included: sediment release of CH4 at different depths; water column transport patterns and methane oxidation; methane storage in the water column; and methane emissions to the atmosphere by diffusion and ebullition. The contribution of CH4 carbon, via oxidation by methanotrophic bacteria, to pelagic food webs was also estimated. Despite the very low concentration of CH4 in surface waters, shallow, epilimnetic sediments were major contributors of CH4 to the atmosphere. While 51-80% of the CH4 produced in deep sediments was oxidized in the water column, most of the CH4 released from shallow sediment escaped oxidation and reached the atmosphere. Epilimnetic sediments accounted for 100% of CH4 emitted during summer stratification, and 14-76% considering the release of CH4 stored in deep water layers during lake circulation after the stratification period; diffusive emission accounted for 26-48% and ebullition the remainder. These results indicate that it is important to address transport rates of CH4 from the shallow sediment along with the production-consumption processes when trying to understand methane dynamics and the regulation of lake methane emissions.

Bastviken, David; Cole, Jonathan J.; Pace, Michael L.; van de Bogert, Matthew C.

2008-06-01

252

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

PubMed

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

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

2010-01-01

253

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

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

254

Reducing Open Cell Landfill Methane Emissions with a Bioactive Alternative Daily  

SciTech Connect

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.

Helene Hilger; James Oliver; Jean Bogner; David Jones

2009-03-31

255

Methane Emission from U.S. Coal Mines in 1973, A Survey.  

National Technical Information Service (NTIS)

The survey was conducted to update the data presented in Bureau of Mines IC 8558, Methane Emission From U.S. Coal Mines, A Survey. It indicates that total daily emissions have declined from 227 MM cu ft in 1971 to 214.7 MM cu ft in 1973. The highest avera...

M. C. Irani P. W. Jeran M. Deul

1974-01-01

256

Characterization of Methane Emissions from Rice Fields in Asia. III. Mitigation Options and Future Research Needs  

Microsoft Academic Search

Methane (CH4) emissions from rice fields were determined using automated measurement systems in China, India, Indonesia, Thailand, and the Philippines. Mitigation options were assessed separately for different baseline practices of irrigated rice, rainfed, and deepwater rice. Irrigated rice is the largest source of CH4 and also offers the most options to modify crop management for reducing these emissions. Optimizing irrigation

R. Wassmann; R. S. Lantin; H. U. Neue; L. V. Buendia; T. M. Corton; Y. Lu

2000-01-01

257

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...

258

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...

259

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...

260

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...

261

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...

262

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...

263

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...

264

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...

265

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...

266

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...

267

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...

268

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...

269

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...

270

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...

271

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...

272

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...

273

Modeling of the Adiabatic and Isothermal Methanation Process  

NASA Astrophysics Data System (ADS)

Increased use of biomass offers one of the ways to reduce anthropogenic impact on the environment. Using various biomass conversion processes, it is possible to obtain different types of fuels: • solid, e.g. bio-carbon; • liquid, e.g. biodiesel and ethanol; • gaseous, e.g. biomethane. Biomethane can be used in the transport and energy sector, and the total methane production efficiency can reach 65%. By modeling adiabatic and isothermal methanation processes, the most effective one from the methane production point of view is defined. Influence of the process parameters on the overall efficiency of the methane production is determined.

Porubova, Jekaterina; Bazbauers, Gatis; Markova, Darja

2011-01-01

274

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

NASA Astrophysics Data System (ADS)

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.

Lerner, Jean; Matthews, Elaine; Fung, Inez

1988-06-01

275

Emission of Methane by Eudrilus eugeniae and Other Earthworms from Brazil  

PubMed Central

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.

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

2012-01-01

276

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

Microsoft Academic Search

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

Robert D. Shannon; Jeffrey R. White

1994-01-01

277

Correction to “Global methane emissions from wetlands, rice paddies, and lakes”  

NASA Astrophysics Data System (ADS)

In the first paragraph of the feature article “Global methane emissions from wetlands, rice paddies, and lakes,” published in the 3 February issue (Eos, 90(5), 2009), the word “nitrous” should have been “nitrogen.” The sentence should read, “Atmospheric methane is 22 times more effective, on a per-unit-mass basis, than carbon dioxide in absorbing long-wave radiation on a 100-year time horizon, and it plays an important role in atmospheric ozone chemistry (e.g., in the presence of nitrogen oxides, tropospheric methane oxidation will lead to the formation of ozone).” Eos regrets this error.

Zhuang, Qianlai; Melack, John M.; Zimov, Sergey; Walter, Katey M.; Butenhoff, Christopher L.; Khalil, M. Aslam K.

2009-03-01

278

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)

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.

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

2004-12-01

279

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

SciTech Connect

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.

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

2012-01-01

280

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

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

281

Methane emissions from beef cattle: Effects of monensin, sunflower oil, enzymes, yeast, and fumaric acid.  

PubMed

Methane emitted from the livestock sector contributes to greenhouse gas (GHG) emissions. Understanding the effects of diet on enteric methane production can help refine GHG emission inventories and identify viable GHG reduction strategies. Our study focused on measuring methane and carbon dioxide emissions, total-tract digestibility, and ruminal fermentation in growing beef cattle fed a diet supplemented with various additives or ingredients. Two experiments, each designed as a 4 x 4 Latin square with 21-d periods, were conducted using 16 Holstein steers (initial BW 311.6 +/- 12.3 kg). In Exp. 1, treatments were control (no additive), monensin (Rumensin, Elanco Animal Health, Indianapolis, IN; 33 mg/kg DM), sunflower oil (400 g/d, approximately 5% of DMI), and proteolytic enzyme (Protex 6-L, Genencor Int., Inc., CA; 1 mL/kg DM). In Exp. 2, treatments were control (no additive), Procreatin-7 yeast (Prince Agri Products, Inc., Quincy, IL; 4 g/d), Levucell SC yeast (Lallemand, Inc., Rexdale, Ontario, Canada; 1 g/d), and fumaric acid (Bartek Ingredients Inc., Stoney Creek, Ontario, Canada; 80 g/d). The basal diet consisted of 75% barley silage, 19% steam-rolled barley grain, and 6% supplement (DM basis). Four large chambers (two animals per chamber) were equipped with lasers and infrared gas analyzers to measure methane and carbon dioxide, respectively, for 3 d each period. Total-tract digestibility was determined using chromic oxide. Approximately 6.5% of the GE consumed was lost in the form of methane emissions from animals fed the control diet. In Exp. 1, sunflower oil decreased methane emissions by 22% (P = 0.001) compared with the control, whereas monensin (P = 0.44) and enzyme had no effect (P = 0.82). However, oil decreased (P = 0.03) the total-tract digestibility of NDF by 20%. When CH(4) emissions were corrected for differences in energy intake, the loss of GE to methane was decreased by 21% (P = 0.002) using oil and by 9% (P = 0.09) using monensin. In Exp. 2, Procreatin-7 yeast (P = 0.72), Levucell SC yeast (P = 0.28), and fumaric acid (P = 0.21) had no effect on methane emissions, although emissions as a percentage of GE intake were 3% (non-significant, P = 0.39) less for steers fed Procreatin-7 yeast compared with the control. This study demonstrates that sunflower oil, ionophores, and possibly some yeast products can be used to decrease the GE lost as methane from cattle, but fiber digestibility is impaired with oil supplementation. PMID:15542482

McGinn, S M; Beauchemin, K A; Coates, T; Colombatto, D

2004-11-01

282

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

PubMed

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

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

283

Methane emission from irrigated and intensively managed rice fields in Central Luzon (Philippines)  

Microsoft Academic Search

\\u000a Methane (CH4) emissions were measured with an automated system in Central Luzon, the major rice producing area of the Philippines. Emission\\u000a records covered nine consecutive seasons from 1994 to 1998 and showed a distinct seasonal pattern: an early flush of CH4 before transplanting, an increasing mend in emission rates reaching maximum toward grain ripening, and a second flush after\\u000a water

T. M. Corton; J. B. Bajita; F. S. Grospe; R. R. Pamplona; C. A. Asis; R. Wassmann; R. S. Lantin; L. V. Buendia

284

Determinants of spatial variability of methane emissions from wet grasslands on peat soil  

Microsoft Academic Search

Methane (CH4) emissions from soils, representing the consequence of CH4 production, CH4 consumption and CH4 transport, are poorly characterised and show a large spatial variability. This study aimed to assess the determinants of field-scale spatial variability of CH4 emissions from wet grasslands on peat soil. Mean CH4 emission rates of a three-year experiment at 18 plots distributed over three sites

Agnes Dasselaar; Marinus L. Beusichem; Oene Oenema

1999-01-01

285

A comparison of methane emissions from sheep grazing pastures with differing management intensities  

Microsoft Academic Search

Methane emissions were measured from sheep grazing on pastures that received one of three managements, either 70 or 270 kg\\u000a N fertiliser ha?1 or one which had a high proportion of white clover present. A system for measuring the emissions is described which enables\\u000a measurements to be made under near natural grazing conditions. Continuous measurements of emissions were made over

P. J. Murray; E. Gill; S. L. Balsdon; S. C. Jarvis

2001-01-01

286

Mathematical model for methane production from landfill bioreactor  

SciTech Connect

A mathematical model for the development of methane production from a landfill bioreactor (LFBR) treating the organic fraction of municipal solid wastes was developed from the Gompertz equation. The model incorporates three biokinetic parameters: methane production lag phase time, rate, and potential. The methane converting capacity test experiment was conducted to monitor the specific methane production rate consuming anaerobic fermentative intermediates, including carbohydrates, proteins, and lipids. The model developed in this study can be used to predict methane production based on the chemical nature and the decomposition characteristics of the organic fraction of municipal solid wastes. The simulative results indicate that the leachate recycle for the LFBR resulted in a more rapid methane production from the consumption of the carbohydrate but in less rapid production from that of the protein and lipid. Moreover, the same specific methane production rate of 2.6 mL/g volatile solid (VS) per day occurred at the LFBR with/without leachate recycle; however, a sharp drop in methane production lag phase time, from 125 to 25 days, was obtained at the LFBR incubated with leachate recycle.

Lay, J.J.; Noike, Tatsuya [Tohoku Univ., Sendai (Japan). Dept. of Civil Engineering; Li, Y.Y. [Ataka Construction and Engineering Co., Ltd., Osaka (Japan). Technical Research Inst.

1998-08-01

287

Natural emissions of methane from geothermal and volcanic sources in Europe  

NASA Astrophysics Data System (ADS)

It has recently been demonstrated that methane emission from lithosphere degassing is an important component of the natural greenhouse-gas atmospheric budget. Globally, the geological sources are mainly due to seepage from hydrocarbon-prone sedimentary basins, and subordinately from geothermal/volcanic fluxes. This work provides a first estimate of methane emission from the geothermal/volcanic component at European level. In Europe, 28 countries have geothermal systems and at least 10 countries host surface geothermal manifestations (hot springs, mofettes, gas vents). Even if direct methane flux measurements are available only for a few small areas in Italy, a fair number of data on CO2, CH4 and steam composition and flux from geothermal manifestations are today available for 6 countries (Czech Republic, Germany, Greece, Iceland, Italy, Spain). Following the emission factor and area-based approach, the available data have been analyzed and have led to an early and conservative estimate of methane emission into the atmosphere around 10,000 ton/yr (4000 16,000 ton/yr), basically from an area smaller than 4000 km2, with a speculative upper limit in the order of 105 ton/yr. Only 4 18% of the conservative estimate (about 720 ton/yr) is due to 12 European volcanoes, where methane concentration in volcanic gases is generally in the order of a few tens of ppmv. Volcanoes are thus not a significant methane source. While the largest emission is due to geothermal areas, which may be situated next to volcanoes or independent. Here inorganic synthesis, thermometamorphism and thermal breakdown of organic matter are substantial. Methane flux can reach hundreds of ton/yr from small individual vents. Geothermal methane is mainly released in three countries located in the main high heat flow regions: Italy, Greece, and Iceland. Turkey is likely a fourth important contributor but the absolute lack of data prevents any emission estimate. Therefore, the actual European geothermal volcanic methane emission could be easily projected to the 105 ton/yr levels, reaching the magnitude of some other natural sources such as forest fires or wild animals.

Etiope, G.; Fridriksson, T.; Italiano, F.; Winiwarter, W.; Theloke, J.

2007-08-01

288

Methane emission from fields with three various rice straw treatments in Taiwan paddy soils.  

PubMed

Flooded rice fields are one of the major biogenic methane sources. In this study, the effects of straw residual treatments on methane emission from paddy fields were discussed. The experimental field was located at Tainan District Agricultural Improvement Station in Chia-Yi county (23 degrees 25'08''N, 120degrees16'26''E) of southern Taiwan throughout the first and the second crop seasons in 2000. The seasonal methane fluxes in the first crop season with rice stubble removed, rice straw burned and rice straw incorporated were 4.41, 3.78 and 5.27 g CH4 m(-2), and the values were 32.8, 38.9 and 75.1 g CH4 m(-2) in the second crop season, respectively. In comparison of three management methods of rice straw residue, the incorporation of rice straw residue should show a significant tendency for enhancing methane emission in the second crop season. Moreover, stubble removed and straw burned treatments significantly reduced CH4 emissions by 28 approximately 56% emissions compared to straw incorporated plot. Concerning for air quality had led to legislation restricting rice straw burning, removing of rice stubble might be an appropriate methane mitigation strategy in Taiwan paddy soils. PMID:12856932

Liou, Rey-May; Huang, Shan-Ney; Lin, Chin-Wei; Chen, Shin-Hsiung

2003-07-01

289

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

SciTech Connect

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.

Devol, A.H.; Richey, J.E. (Univ. of Washington, Seattle (USA)); Forsberg, B.R. (Instituto Nacional de Pesquisas da Amazonia, Manaus (Brazil)); Martinelli, L.A. (Centro de Energia Nuclear na Agricultura, Piracicaba (Brazil))

1990-09-20

290

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

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

291

Methane emissions from the natural gas industry. Volume 3. General methodology. Final report, March 1991April 1996  

Microsoft Academic Search

The report describes the methods used to quantify the annual methane emissions from the natural gas industry. The methods include the general methods used for emission factor measurement, activity factor quantification, and extrapolation.

M. R. Harrison; H. J. Williamson; L. M. Campbell

1996-01-01

292

Methane Emissions from Gassy Coals in Storage Silos.  

National Technical Information Service (NTIS)

The methane gas emitted from coal samples collected from conveyor belts dumping into silos was measured by the Bureau of Mines. Approximately 50 percent of the total gas desorbed into a sealed can within 1 week was released during the first 24 hours. No s...

F. N. Kissell J. C. LaScola J. E. Matta

1978-01-01

293

Methane Emissions from Gassy Coals in Storage Silos.  

National Technical Information Service (NTIS)

The methane gas emitted from coal samples collected from the conveyor belts dumping into silos was measured. Approximately 50 pct of the total gas desorbed into a sealed can within 1 week was released during the first 24 hours. No simple correlation betwe...

J. E. Matta J. C. LaScola F. N. Kissell

1978-01-01

294

Inventory of methane and nitrous oxide emissions from agricultural soils of India and their global warming potential  

Microsoft Academic Search

Agricultural soils contribute towards the emission of methane and nitrous oxide, the two important green- house gases causing global warming. Due to the diverse soil, land-use types and climatic conditions, there are uncertainties in quantificatio n of greenhouse gas emis- sion from agricultural soils in India. An inve ntory of the emission of methane and nitrous oxide from diffe- rent

Arti Bhatia; H. Pathak; P. K. Aggarwal

2004-01-01

295

Autothermal catalytic pyrolysis of methane as a new route to hydrogen production with reduced CO 2 emissions  

Microsoft Academic Search

Hydrogen production plants are among major sources of CO2 emissions into the atmosphere. The objective of this paper is to explore new routes to hydrogen production from natural gas (or methane) with drastically reduced CO2 emissions. One approach analyzed in this paper is based on thermocatalytic decomposition (or pyrolysis) of methane into hydrogen gas and elemental carbon over carbon-based catalysts.

Nazim Muradov; Franklyn Smith; Cunping Huang; Ali T-Raissi

2006-01-01

296

Estimation of methane and nitrous oxide emission from animal production sector in Taiwan during 1990–2000  

Microsoft Academic Search

To investigate the greenhouse gases emissions from the feeding and waste management of livestock and poultry, methane and nitrous oxide emissions were estimated from the local measurement and IPCC guidelines during 1990–2000 in Taiwan. Hog is the major livestock and is followed by goat and cattle, while chicken is the major poultry and is followed by duck and geese. Methane

Shang-Shyng Yang; Chung-Ming Liu; Yen-Lan Liu

2003-01-01

297

Critical state soil constitutive model for methane hydrate soil  

NASA Astrophysics Data System (ADS)

This paper presents a new constitutive model that simulates the mechanical behavior of methane hydrate-bearing soil based on the concept of critical state soil mechanics, referred to as the "Methane Hydrate Critical State (MHCS) model". Methane hydrate-bearing soil is, under certain geological conditions, known to exhibit greater stiffness, strength and dilatancy, which are often observed in dense soils and also in bonded soils such as cemented soil and unsaturated soil. Those soils tend to show greater resistance to compressive deformation but the tendency disappears when the soil is excessively compressed or the bonds are destroyed due to shearing. The proposed model represents these features by introducing five extra model parameters to the conventional critical state model. It is found that, for an accurate prediction of ground settlement, volumetric yielding plays an important role when hydrate soil undergoes a significant change in effective stresses and hydrate saturation, which are expected during depressurization for methane gas recovery.

Uchida, S.; Soga, K.; Yamamoto, K.

2012-03-01

298

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

...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...

2013-07-01

299

Measurement of methane emissions from ruminant livestock using a SF[sub 6] tracer technique  

SciTech Connect

The purpose of this paper is to describe a method for determining methane emission factors for cattle. The technique involves the direct measurement of methane emissions from livestock in their natural environment. A small permeation tube containing SF[sub 6] is placed in the cow's rumen, and SF[sub 6] and CH[sub 4] concentrations are measured near the mouth and nostrils of the cow. The SF[sub 6] release provides a way to account for the dilution of gases near the animal's mouth. The CH[sub 4] emission rate can be calculated from the known SF[sub 6] emission rate and the measured SF[sub 6] and CH[sub 4] concentrations. The tracer method described provides an easy means for acquiring a large methane emissions data base from domestic livestock. The low cost and simplicity should make it possible to monitor a large number of animals in countries throughout the world. An expanded data base of this type helps to reduce uncertainty in the ruminant contribution to the global methane budget. 18 refs., 3 figs., 3 tabs.

Johnson, K.; Huyler, M.; Westberg, H.; Lamb, B. (Washington State Univ., Pullman, WA (United States)); Zimmerman, P. (National Center for Atmospheric Research, Boulder, CO (United States))

1994-02-01

300

Genetic parameters for predicted methane production and potential for reducing enteric emissions through genomic selection.  

PubMed

Mitigation of enteric methane (CH?) emission in ruminants has become an important area of research because accumulation of CH? is linked to global warming. Nutritional and microbial opportunities to reduce CH? emissions have been extensively researched, but little is known about using natural variation to breed animals with lower CH? yield. Measuring CH? emission rates directly from animals is difficult and hinders direct selection on reduced CH? emission. However, improvements can be made through selection on associated traits (e.g., residual feed intake, RFI) or through selection on CH? predicted from feed intake and diet composition. The objective was to establish phenotypic and genetic variation in predicted CH? output, and to determine the potential of genetics to reduce methane emissions in dairy cattle. Experimental data were used and records on daily feed intake, weekly body weights, and weekly milk production were available from 548 heifers. Residual feed intake (MJ/d) is the difference between net energy intake and calculated net energy requirements for maintenance as a function of body weight and for fat- and protein-corrected milk production. Predicted methane emission (PME; g/d) is 6% of gross energy intake (Intergovernmental Panel on Climate Change methodology) corrected for energy content of methane (55.65 kJ/g). The estimated heritabilities for PME and RFI were 0.35 and 0.40, respectively. The positive genetic correlation between RFI and PME indicated that cows with lower RFI have lower PME (estimates ranging from 0.18 to 0.84). Hence, it is possible to decrease the methane production of a cow by selecting more-efficient cows, and the genetic variation suggests that reductions in the order of 11 to 26% in 10 yr are theoretically possible, and could be even higher in a genomic selection program. However, several uncertainties are discussed; for example, the lack of true methane measurements (and the key assumption that methane produced per unit feed is not affected by RFI level), as well as the limitations of predicting the biological consequences of selection. To overcome these limitations, an international effort is required to bring together data on feed intake and methane emissions of dairy cows. PMID:22118100

Haas, Y de; Windig, J J; Calus, M P L; Dijkstra, J; Haan, M de; Bannink, A; Veerkamp, R F

2011-12-01

301

Climatology and Atmospheric Chemistry of Non-Methane Hydrocarbon Emissions over the North Atlantic  

NASA Astrophysics Data System (ADS)

Non-methane hydrocarbons (NMHC) spanning the C2-C7 volatility range have been monitored at the Pico Mountain Observatory, located at 2,225 m a.s.l., on Pico Island, in the Azores, Portugal, since 2004. Observations at this site, due to the topography, location, and height of the station, during most times reflect long-range transport of air from the continents bordering the North Atlantic. The multi-year data records show that NMHC mole fractions exhibit regular annual cycles with winter maxima and summer minima. Short-term variability of the data is driven by transport events typically lasting 2-5 days. During these events NMHC absolute levels show significant increases over their seasonal background. NMHC ratios were applied to estimate the degree of photochemical processing and transport time to the station. Transport events identified from the NMHC data were then analyzed for emission source region and transport pathway using HYSPLIT model outputs. The multi-year observations were applied to develop a seasonality of the pollution transport to Pico and contributing source regions. These analyses show that emissions from the North American continent are the primary cause for elevated NMHC levels observed at the station. Most identified transport events originate from urban areas; biomass burning transport from boreal North America was identified in a few selected cases during late summer. Emissions in air transported from Europe and Africa were encountered only on a few occasions.

Helmig, Detlev; Hueber, Jacques; Munoz, Mauricio; Mazzoleni, Claudio; Mazzoleni, Lynn; Owen, Robert; Val-Martin, Maria; Fialho, Paulo

2013-04-01

302

Titan's methane cycle in the Titan WRF general circulation model  

NASA Astrophysics Data System (ADS)

Observations of methane clouds, surface lakes and precipitation (or evidence of past precipitation) on Titan allow us to assemble information about the seasonal evolution of Titan’s methane cycle, as well as Titan’s lower atmosphere and near-surface environment in general. Using the TitanWRF general circulation model [Newman et al., 2011] we attempt to reproduce some of these observations by simulating Titan’s atmospheric circulation and methane cycle, assuming limited surface methane and using a simple large-scale cloud scheme both with and without latent heating effects included. We have performed both ‘current’ and ‘reversed perihelion’ simulations, i.e. using the current solar forcing (perihelion in southern summer) and its exact opposite (perihelion in northern summer, as occurred at some time in the past), to test the hypothesis that the timing of perihelion explains the asymmetry in surface methane distribution currently observed. We look at the net transport and latitudinal distribution of surface methane as the simulations tend toward steady state after >100 Titan years. Initially, as the equatorial regions lose and the high latitudes gain significant methane each Titan year, our results are highly sensitive to initial conditions. However, as the simulations tend toward steady state and specifically as the tropics dry out, the ‘current’ and ‘reversed perihelion’ results increasingly tend toward ‘mirror images’ of each other. With the decreased significance of tropical moisture sources, the methane balance becomes dominated by pole-to-pole exchange (inter-polar competition for methane) with the simulations tending toward final states with significantly more high latitude surface methane in the hemisphere with the longer, cooler summer (i.e., in the northern hemisphere for current solar forcing, in line with the asymmetry observed). References: Newman, C. E., et al.: "Stratospheric superrotation in the TitanWRF model". Icarus, Vol. 213, pp. 636-654, 2011.

Newman, C. E.; Lian, Y.; Richardson, M. I.; Lee, C.; Toigo, A. D.

2012-04-01

303

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

SciTech Connect

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

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

2008-04-15

304

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

SciTech Connect

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.

Tyler, S.C.; Dlugokencky, E.; Zimmerman, P.R.; Cicerone, R.J. (National Center for Atmospheric Research, Boulder, CO (USA)); Lowe, D.C. (Institute of Nuclear Sciences, Lower Hutt (New Zealand))

1990-08-20

305

Methane emissions from a full-scale A/A/O wastewater treatment plant.  

PubMed

Methane (CH(4)) emissions from a full-scale anaerobic/anoxic/oxic (A/A/O) wastewater treatment plant (WWTP) (Jinan, China) were investigated during spring and summer of 2010. Results showed that the major emission sources of CH(4) performed the following descending order: anaerobic tanks, oxic tanks, aerated grit chambers and sludge concentration tanks. The total annual fluxes of CH(4) emissions from the Jinan WWTP were 1.69 × 10(4)kg yr(-1), with the emission factors of per capita emissions of 11.3g CH(4) person(-1)yr(-1) and flow-based emissions of 1.55 × 10(-4)g CH(4) (L of wastewater)(-1). The estimated source strength of methane for all WWTPs in China was 6.2 Gg yr(-1) (1 Gg=10(9)g). The most significant factors influencing methane emissions were dissolved oxygen concentration in aerated grit chamber and oxic tank and water temperature in high density settler tanks. PMID:21084185

Wang, Jinhe; Zhang, Jian; Xie, Huijun; Qi, Pengyu; Ren, Yangang; Hu, Zhen

2010-10-23

306

Beaver population fluctuations and tropospheric methane emissions in boreal wetlands  

Microsoft Academic Search

Measurements of net methane flux were made during the 1988 ice-free season (May–October) at a beaver-meadow complex in northern Minnesota, USA. The site included upland boreal forest, sedge meadow, submerged aquatic plants, and the open water of a beaver pond. Annual fluxes were 8–11 g C\\/m2 in the permanently wetted zones and 0.2–0.4 g C\\/m2 at the occasionally inundated meadow

Robert J. Naiman; Thomas Manning; Carol A. Johnston

1991-01-01

307

Shock-tube and modeling study of methane pyrolysis and oxidation  

SciTech Connect

Methane pyrolysis and oxidation were studied behind reflected shock waves in the temperature range 1350--2400 K at pressures of 1.6 to 4.4 atm. Methane decay in both the pyrolysis and oxidation reactions was measured by using time-resolved infrared (IR) laser absorption at 3.39 {micro}m. CO{sub 2} production was also measured by time-resolved IR emission at 4.24 {micro}m. The production yields were also studied using a single-pulse method. The pyrolysis and oxidation of methane were modeled using a kinetic reaction mechanism including the most recent mechanism for formaldehyde, ketene, acetylene, ethylene, and ethane oxidations. The present and earlier shock tube data is reproduced by the proposed mechanism with 157 reaction steps and 48 species. The reactions and the rate constants, which were important to predict these and earlier shock tube data for methane pyrolysis and the oxidation with mixtures of wide composition from methane-rich to methane-lean, are discussed in detail.

Hidaka, Yoshiaki; Sato, Kazutaka; Henmi, Yusuke; Tanaka, Hiroya; Inami, Koji [Ehime Univ., Matsuyama (Japan). Dept. of Chemistry

1999-08-01

308

Implementation and evaluation of a new methane model within a dynamic global vegetation model: LPJ-WHyMe v1.3.1  

NASA Astrophysics Data System (ADS)

For the first time, a model that simulates methane emissions from northern peatlands is incorporated directly into a dynamic global vegetation model. The model, LPJ-WHyMe (LPJ Wetland Hydrology and Methane), was previously modified in order to simulate peatland hydrology, permafrost dynamics and peatland vegetation. LPJ-WHyMe simulates methane emissions using a mechanistic approach, although the use of some empirical relationships and parameters is unavoidable. The model simulates methane production, three pathways of methane transport (diffusion, plant-mediated transport and ebullition) and methane oxidation. A sensitivity test was conducted to identify the most important factors influencing methane emissions, followed by a parameter fitting exercise to find the best combination of parameter values for individual sites and over all sites. A comparison of model results to observations from seven sites resulted in normalised root mean square errors (NRMSE) of 0.40 to 1.15 when using the best site parameter combinations and 0.68 to 1.42 when using the best overall parameter combination.

Wania, R.; Ross, I.; Prentice, I. C.

2010-10-01

309

Diel variation in methane emission from a midlatitude prairie wetland: Significance of convective throughflow in Phragmites australis  

NASA Astrophysics Data System (ADS)

Methane flux was measured at a Phragmites-dominated marsh in the Sandhills of north-central Nebraska from late July to September 1993. The eddy covariance technique employing a tunable diode laser spectrometer was used to measure spatially integrated fluxes of methane. Rates of methane emission increased rapidly after sunrise and peaked (at up to 50 mg CH4 m-2 h-1) between midmorning and noon. The emission rates during midday hours were 2 to 5 times higher than the relatively constant rates observed at night. This marked diel variation was attributed to plant-mediated transport of methane by convective throughflow which typically accounted for about 60% of the total methane emission during the daylight hours. Our analysis suggests that the enhanced rate of plant-mediated methane emission during daytime is significantly correlated with changes in photosynthetically active radiation and the temperature difference between the canopy and the ambient air. Data on windy nights showed enhanced methane emission with increasing wind speeds, perhaps indicating an occurrence of Venturi-induced convection and/or enhanced ebullition. When averaged over the study period of 65 days, the methane flux was 25 mg CH4 m-2 h-1 during daytime and 8 mg CH4 m-2 h-1 during nighttime. Changes in the daily averaged methane flux were strongly correlated with sediment temperatures at 0-0.25 m depth.

Kim, J.; Verma, S. B.; Billesbach, D. P.; Clement, R. J.

1998-11-01

310

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

SciTech Connect

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.

Hughes, S.; Dowrick, D.J.; Freeman, C.; Reynolds, B. [Univ. of Wales, Bangor (United Kingdom); Hudson, J.A. [Inst. of Hydrology, Llanbrynmair (United Kingdom)

1999-01-15

311

Influences of indigenous phototrophs on methane emissions from a straw-amended paddy soil  

Microsoft Academic Search

A pot experiment was conducted to investigate the influences of indigenous phototrophs on methane (CH 4) emissions from a paddy soil where rice straw was incorporated or was surface-applied. During the cultivation, half of the pots were covered with aluminum foil, except for the minimum space for rice plants, to prevent ambient light reaching the floodwater or the soil surface.

Naoki Harada; Shigeto Otsuka; Masaya Nishiyama; Satoshi Matsumoto

2005-01-01

312

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...

313

Sulfate deposition and temperature controls on methane emission and sulfur forms in peat  

Microsoft Academic Search

Natural wetlands are the single most important contributors of methane (CH4) to the atmosphere. Recent research has shown that the deposition of sulfate (SO42-) can substantially reduce the emission of this radiatively important gas from wetlands. However, the influence of temperature in regulating the extent of this effect is unclear. Peatlands also constitute an important store of sulfur (S), so

Vincent Gauci; David Fowler; Stephen J. Chapman; Nancy B. Dise

2005-01-01

314

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

Microsoft Academic Search

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

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

2002-01-01

315

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

316

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

317

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...

318

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...

319

Methane emissions from wet grasslands on peat soil in a nature preserve  

Microsoft Academic Search

The area of wet grasslands on peat soil in the Netherlands is slowly increasing at the expense of drained, agriculturally used grasslands. This study aimed (i) to assess the contribution of wet grasslands on peat soil to methane (CH4) emissions, and (ii) to explain differences among sites and between years in order to improve our understanding of controlling factors. For

Agnes Dasselaar; Marinus L. Beusichem; Oene Oenema

1999-01-01

320

Effects of Elevated CO2 and Temperature on Methane Production and Emission from Submerged Soil Microcosm  

Microsoft Academic Search

Incubation experiments were conducted under controlled laboratory conditions to study the interactive effects of elevated carbon dioxide (CO2) and temperature on the production and emission of methane (CH4) from a submerged rice soil microcosm. Soil samples (unamended soil; soil + straw; soil + straw + N fertilizer) were placed in four growth chambers specifically designed for a combination of two

W. Cheng; K. Chander; K. Inubushi

2000-01-01

321

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...

322

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

323

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

Microsoft Academic Search

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

H. J. Laanbroek

2010-01-01

324

Dietary nitrate supplementation reduces methane emission in beef cattle fed sugarcane-based diets.  

PubMed

The objective of this study was to determine the effect of dietary nitrate on methane emission and rumen fermentation parameters in Nellore × Guzera (Bos indicus) beef cattle fed a sugarcane based diet. The experiment was conducted with 16 steers weighing 283 ± 49 kg (mean ± SD), 6 rumen cannulated and 10 intact steers, in a cross-over design. The animals were blocked according to BW and presence or absence of rumen cannula and randomly allocated to either the nitrate diet (22 g nitrate/kg DM) or the control diet made isonitrogenous by the addition of urea. The diets consisted of freshly chopped sugarcane and concentrate (60:40 on DM basis), fed as a mixed ration. A 16-d adaptation period was used to allow the rumen microbes to adapt to dietary nitrate. Methane emission was measured using the sulfur hexafluoride tracer technique. Dry matter intake (P = 0.09) tended to be less when nitrate was present in the diet compared with the control, 6.60 and 7.05 kg/d DMI, respectively. The daily methane production was reduced (P < 0.01) by 32% when steers were fed the nitrate diet (85 g/d) compared with the urea diet (125 g/d). Methane emission per kilogram DMI was 27% less (P < 0.01) on the nitrate diet (13.3 g methane/kg DMI) than on the control diet (18.2 g methane/kg DMI). Methane losses as a fraction of gross energy intake (GEI) were less (P < 0.01) on the nitrate diet (4.2% of GEI) than on the control diet (5.9% of GEI). Nitrate mitigated enteric methane production by 87% of the theoretical potential. The rumen fluid ammonia-nitrogen (NH(3)-N()) concentration was significantly greater (P < 0.05) for the nitrate diet. The total concentration of VFA was not affected (P = 0.61) by nitrate in the diet, while the proportion of acetic acid tended to be greater (P = 0.09), propionic acid less (P = 0.06) and acetate/propionate ratio tended to be greater (P = 0.06) for the nitrate diet. Dietary nitrate reduced enteric methane emission in beef cattle fed sugarcane based diet. PMID:22287674

Hulshof, R B A; Berndt, A; Gerrits, W J J; Dijkstra, J; van Zijderveld, S M; Newbold, J R; Perdok, H B

2012-01-27

325

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

NASA Astrophysics Data System (ADS)

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

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

2009-09-01

326

Atmospheric methane observed from space over the Asian monsoon: implications for emission from Asian rice paddies  

NASA Astrophysics Data System (ADS)

More than 40% of anthropogenic emissions of methane, the second most important greenhouse gas, is estimated to be from agricultural sources, including rice cultivation. Unfortunately, the strength of individual sources of methane remains uncertain, despite the importance of its effect in global warming. Here we focus on the Asian monsoon region to improve our understanding of methane emission from rice paddy fields. This region contains about 90% of the world’s rice fields. We analyze the temporal and spatial distribution of atmospheric methane concentrations observed from space and compare it with ground-based measurements and bottom-up emission inventory data coupled with rice field maps. Recently, Frankenberg et al. [2008] derived an updated version of methane concentration from the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY: SCIA hereafter) instrument onboard ENVISAT. This showed a clear signature of methane enhancement over the Asian monsoon. As SCIA retrievals include all involve column densities, we carefully examined potential biases and variability due to the gradient of methane concentration over source regions by comparing these data with ground-based measurements at 53 stations of the WDCGG network. After evaluating the bias and variability of methane concentration over the source regions, we examined selected areas where rice paddies were highly concentrated, and the methane emission inventories were estimated to be large. The sampled areas were North and South India, Bangladesh, Myanmar, Thailand, South China, and the Sichuan Basin. All of these are known to be major rice cultivation areas. The time series of monthly mean SCIA retrievals were compared with the emission inventory data for rice cultivation archived in the GISS dataset and Yan et al. [2009], as well as with precipitation data (Huffman et al., 1997). The phase of seasonal variation of SCIA retrievals corresponded closely to those of emission inventories. High methane concentrations were observed in the later period of the rainy season for each area. The amplitude of seasonal variation was large compared with the possible bias over the source regions, demonstrating the reliability of the analysis. We are planning to extend the analysis to the methane data observed by the Thermal And Near infrared Sensor for carbon Observations Fourier Transform Spectrometer (TANSO-FTS) onboard the Greenhouse gases Observing SATellite (GOSAT). GOSAT was launched successfully on January 23, 2009, and has been operating continuously since then. The TANSO-FTS will provide important information on methane emission from rice paddies with good spatial resolution (10 km in diameter). Preliminary results from this instrument will also be presented. References: Frankenberg, et al. (2008), Geophys. Res. Lett., 35, doi:10.1029/2008GL034300. Huffman et al. (1997), Bull. Am. Meteorol. Soc. Vol. 78, 5-20. Yan et al., (2009), Global Biogeochem. Cycles, 23, GB2002, doi:10.1029 /2008GB003299.

Hayashida, S.; Yoshizaki, S.; Frankenberg, C.; Yan, X.

2010-12-01

327

Palladium catalyst performance for methane emissions abatement from lean burn natural gas vehicles  

Microsoft Academic Search

As little as 1 ppm SOx present in the exhaust of a lean burn natural gas engine strongly inhibits the oxidation of CH4 over a Pd containing catalyst. Non-methane emissions oxidation, such as C2H6, C3H8 and CO, are also inhibited by low SOx concentrations, but to a lesser extent than CH4 emissions. The mechanism for SOx inhibition indicates a 1

Jordan K. Lampert; M. Shahjahan Kazi; Robert J. Farrauto

1997-01-01

328

Quantification of methane emissions from Chinese rice fields (Zhejiang Province) as influenced by fertilizer treatment  

Microsoft Academic Search

Methane emissions from rice paddies were quantified by using an automatic field system stationed in Zhejiang Province, one\\u000a of the centres for rice cultivation in China. The data set showed pronouned interannual variations over 5 consecutive vegetation\\u000a periods; by computing average values of all experimental plots the annual emissions were 177 g CH4 m?2 yr?1 in 1987, 50 g CH4

Reiner Wassmann; Helmut Schütz; Hans Papen; Heinz Rennenberg; Wolfgang Seiler; Dai Aiguo; Shen Renxing; Shangguan Xingjian; Wang Mingxing

1993-01-01

329

Processes involved in formation and emission of methane in rice paddies  

Microsoft Academic Search

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

Helmut Schütz; Wolfgang Seiler; Ralf Conrad

1989-01-01

330

Algorithms for calculating methane and nitrous oxide emissions from manure management  

Microsoft Academic Search

Biogenic emissions of methane (CH4) and nitrous oxide (N2O) from animal manure are stimulated by the degradation of volatile solids (VS) which serves as an energy source and a sink for atmospheric oxygen. Algorithms are presented which link carbon and nitrogen turnover in a dynamic prediction of CH4 and N2O emissions during handling and use of liquid manure (slurry). A

S. G. Sommer; S. O. Petersen; H. B. Møller

2004-01-01

331

Emissions of non-methane organic compounds from a grassland site  

Microsoft Academic Search

A mixture of oxygenated hydrocarbons (OxHCs), isoprene, and monoterpenes was detected in the emissions from a grassland site in the Midwestern United States. A plot dominated by crown vetch (Coronilla varia) and bluegrass (Poa spp.), exhibited a constant decrease in emissions of total non-methane organic compounds (NMOCs) from 580 μg m⁻² hr⁻¹ in June 1992 to 150 μg m{sup -

Yoshiko Fukui; P. V. Doskey

1996-01-01

332

In-flight measurement of aircraft non-methane hydrocarbon emission indices  

Microsoft Academic Search

Concentrations of non-methane hydrocarbons (NMHC) and CO were measured in exhaust plumes of the DLR experimental aircraft ATTAS equipped with Rolls Royce M 45H Mk50l engines. The emission indices (EI) of individual light NMHC were determined from ratios of NMHC and CO concentration enhancements measured in grab samples and the concurrent in-flight measurements of EI of CO by FTIR emission

F. Slemr; H. Giehl; J. Slemr; R. Busen; P. Schulte; P. Haschberger

1998-01-01

333

In-flight measurement of aircraft non-methane hydrocarbon emission indices  

Microsoft Academic Search

Concentrations of non-methane hydrocarbons (NMHC) and CO were measured in exhaust plumes of the DLR experimental aircraft ATTAS equipped with Rolls Royce M 45H Mk501 engines. The emission indices (EI) of individual light NMHC were determined from ratios of NMHC and CO concentration enhancements measured in grab samples and the concurrent in-flight measurements of EI of CO by FTIR emission

F. Slemr; H. Giehl; J. Slemr; R. Busen; P. Schulte; P. Haschberger

1998-01-01

334

Development of equations for predicting methane emissions from ruminants.  

PubMed

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

Ramin, M; Huhtanen, P

2013-02-10

335

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

NASA Astrophysics Data System (ADS)

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.

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

336

Methane emissions from rice paddies natural wetlands, and lakes in China: synthesis and new estimate.  

PubMed

Sources of methane (CH4 ) become highly variable for countries undergoing a heightened period of development due to both human activity and climate change. An urgent need therefore exists to budget key sources of CH4 , such as wetlands (rice paddies and natural wetlands) and lakes (including reservoirs and ponds), which are sensitive to these changes. For this study, references in relation to CH4 emissions from rice paddies, natural wetlands, and lakes in China were first reviewed and then reestimated based on the review itself. Total emissions from the three CH4 sources were 11.25 Tg CH4  yr(-1) (ranging from 7.98 to 15.16 Tg CH4  yr(-1) ). Among the emissions, 8.11 Tg CH4  yr(-1) (ranging from 5.20 to 11.36 Tg CH4  yr(-1) ) derived from rice paddies, 2.69 Tg CH4  yr(-1) (ranging from 2.46 to 3.20 Tg CH4  yr(-1) ) from natural wetlands, and 0.46 Tg CH4  yr(-1) (ranging from 0.33 to 0.59 Tg CH4  yr(-1) ) from lakes (including reservoirs and ponds). Plentiful water and warm conditions, as well as its large rice paddy area make rice paddies in southeastern China the greatest overall source of CH4 , accounting for approximately 55% of total paddy emissions. Natural wetland estimates were slightly higher than the other estimates owing to the higher CH4 emissions recorded within Qinghai-Tibetan Plateau peatlands. Total CH4 emissions from lakes were estimated for the first time by this study, with three quarters from the littoral zone and one quarter from lake surfaces. Rice paddies, natural wetlands, and lakes are not constant sources of CH4 , but decreasing ones influenced by anthropogenic activity and climate change. A new progress-based model used in conjunction with more observations through model-data fusion approach could help obtain better estimates and insights with regard to CH4 emissions deriving from wetlands and lakes in China. PMID:23504718

Chen, Huai; Zhu, Qiu'an; Peng, Changhui; Wu, Ning; Wang, Yanfen; Fang, Xiuqin; Jiang, Hong; Xiang, Wenhua; Chang, Jie; Deng, Xiangwen; Yu, Guirui

2012-10-26

337

Methane-Cycling Microbial Communities and Methane Emission in Natural and Restored Peatlands  

PubMed Central

We addressed how restoration of forestry-drained peatlands affects CH4-cycling microbes. Despite similar community compositions, the abundance of methanogens and methanotrophs was lower in restored than in natural sites and correlated with CH4 emission. Poor establishment of methanogens may thus explain low CH4 emissions on restored peatlands even 10 to 12 years after restoration.

Hynninen, Anu; Nieminen, Mika; Tuomivirta, Tero T.; Tuittila, Eeva-Stiina; Nousiainen, Hannu; Kell, Dana K.; Yrjala, Kim; Tervahauta, Arja; Fritze, Hannu

2012-01-01

338

One year of continuous measurements constraining methane emissions from the Baltic Sea to the atmosphere using a ship of opportunity  

NASA Astrophysics Data System (ADS)

Methane and carbon dioxide were measured with an autonomous and continuous running system on a ferry line crossing the Baltic Sea on a 2-3 day interval from the Mecklenburg Bight to the Gulf of Finland in 2010. Surface methane saturations show great seasonal differences in shallow regions like the Mecklenburg Bight (103-507%) compared to deeper regions like the Gotland Basin (96-161%). The influence of controlling parameters like temperature, wind, mixing depth and processes like upwelling, mixing of the water column and sedimentary methane emissions on methane oversaturation and emission to the atmosphere are investigated. Upwelling was found to influence methane surface concentrations in the area of Gotland significantly during the summer period. In February 2010, an event of elevated methane concentrations in the surface water and water column of the Arkona Basin was observed, which could be linked to a wind-derived water level change as a potential triggering mechanism. The Baltic Sea is a source of methane to the atmosphere throughout the year, with highest fluxes during the winter season. Stratification was found to intensify the formation of a methane reservoir in deeper regions like Gulf of Finland or Bornholm Basin, which leads to long lasting elevated methane concentrations and enhanced methane fluxes, when mixed to the surface during mixed layer deepening in autumn and winter. Methane concentrations and fluxes from shallow regions like the Mecklenburg Bight are rather controlled by sedimentary production and consumption of methane, wind events and the change in temperature-dependent solubility of methane in the surface water. Methane fluxes vary significantly in shallow regions (e.g. Mecklenburg Bight) and regions with a temporal stratification (e.g. Bornholm Basin, Gulf of Finland). On the contrary, areas with a permanent stratification like the Gotland Basin show only small seasonal fluctuations in methane fluxes.

Gülzow, W.; Rehder, G.; Deimling, J. Schneider v.; Seifert, T.; Tóth, Zs.

2012-08-01

339

One year of continuous measurements constraining methane emissions from the Baltic Sea to the atmosphere using a ship of opportunity  

NASA Astrophysics Data System (ADS)

Methane and carbon dioxide were measured with an autonomous and continuous running system on a ferry line crossing the Baltic Sea on a 2-3 day interval from the Mecklenburg Bight to the Gulf of Finland in 2010. Surface methane saturations show great seasonal differences in shallow regions like the Mecklenburg Bight (103-507%) compared to deeper regions like the Gotland Basin (96-161%). The influence of controlling parameters like temperature, wind, mixing depth and processes like upwelling, mixing of the water column and sedimentary methane emissions on methane oversaturation and emission to the atmosphere are investigated. Upwelling was found to influence methane surface concentrations in the area of Gotland significantly during the summer period. In February 2010, an event of elevated methane concentrations in the surface water and water column of the Arkona Basin was observed, which could be linked to a wind-derived water level change as a potential triggering mechanism. The Baltic Sea is a source of methane to the atmosphere throughout the year, with highest fluxes occurring during the winter season. Stratification was found to promote the formation of a methane reservoir in deeper regions like Gulf of Finland or Bornholm Basin, which leads to long lasting elevated methane concentrations and enhanced methane fluxes, when mixed to the surface during mixed layer deepening in autumn and winter. Methane concentrations and fluxes from shallow regions like the Mecklenburg Bight are predominantly controlled by sedimentary production and consumption of methane, wind events and the change in temperature-dependent solubility of methane in the surface water. Methane fluxes vary significantly in shallow regions (e.g. Mecklenburg Bight) and regions with a temporal stratification (e.g. Bornholm Basin, Gulf of Finland). On the contrary, areas with a permanent stratification like the Gotland Basin show only small seasonal fluctuations in methane fluxes.

Gülzow, W.; Rehder, G.; Deimling, J. Schneider v.; Seifert, T.; Tóth, Z.

2013-01-01

340

Methane emission from naturally ventilated livestock buildings can be determined from gas concentration measurements.  

PubMed

Determination of emission of contaminant gases as ammonia, methane, or laughing gas from natural ventilated livestock buildings with large opening is a challenge due to the large variations in gas concentration and air velocity in the openings. The close relation between calculated animal heat production and the carbon dioxide production from the animals have in several cases been utilized for estimation of the ventilation air exchange rate for the estimation of ammonia and greenhouse gas emissions. Using this method, the problem of the complicated air velocity and concentration distribution in the openings is avoided; however, there are still some important issues remained unanswered: (1) the precision of the estimations, (2) the requirement for the length of measuring periods, and (3) the required measuring point number and location. The purpose of this work was to investigate how estimated average gas emission and the precision of the estimation are influenced by different calculation procedures, measuring period length, measure point locations, measure point numbers, and criteria for excluding measuring data. The analyses were based on existing data from a 6-day measuring period in a naturally ventilated, 150 milking cow building. The results showed that the methane emission can be determined with much higher precision than ammonia or laughing gas emissions, and, for methane, relatively precise estimations can be based on measure periods as short as 3 h. This result makes it feasible to investigate the influence of feed composition on methane emission in a relative large number of operating cattle buildings and consequently it can support a development towards reduced greenhouse gas emission from cattle production. PMID:22020391

Bjerg, Bjarne; Zhang, Guoqiang; Madsen, Jørgen; Rom, Hans B

2011-10-22

341

Methane hydrate rock physics models for the Blake Outer Ridge  

Microsoft Academic Search

Seismic analyses of methane hydrate data from the Blake Outer Ridge indicate high P- wave velocity and anomalously low S-wave velocity in sediments containing methane hydrates. In an attempt to explain this observed P-wave and S-wave velocity structure at the transition from gas to hydrates, the effect of different hydrate models on elastic moduli and velocities are explored. After construction

Christine Ecker

2001-01-01

342

LANDFILL OPERATION FOR CARBON SEQUESTRATION AND MAXIMUM METHANE EMISSION CONTROL  

SciTech Connect

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.

Don Augenstein

2001-02-01

343

Methane emission estimation from landfills in Delhi: A comparative assessment of different methodologies  

NASA Astrophysics Data System (ADS)

Landfills are important anthropogenic sources of methane (CH 4 ) emission especially in fast urbanizing countries. This paper presents the CH 4 emission estimations carried out using the in-situ CH 4 measurements, IPCC 1996 Default methodology (DM), Modified Triangular Method (MTM) and First Order Decay (FOD) method for the three landfills currently operational in the capital city Delhi of India. The in-situ methodology has yielded the landfills specific methane emission factors (EFs). The annual average methane emission rates from three landfills namely, Ghazipur (GL), Bhalswa (BL) and Okhla (OL) are 14.6, 23.6 & 7.5 Gg y -1 by DM; 13.3, 10.6 & 7.2 Gg y -1 by the FOD; 17.0, 13.7 and 10.7 Gg y -1 by the MTM; and 4.6, 4.2 and 1.4 Gg y -1 by the in-situ measurement method respectively. The CH 4 EFs have been found to be 9.7 ± 2.6, 5.5 ± 1.6 and 5.5 ± 1.7 g kg -1 of waste respectively for the GL, BL and OL landfills in Delhi. The study reveals that in-situ methodology seems to provide better representative emission estimation compared to other methods. The FOD method also yields comparable results with that of in-situ methodology in cases where good waste composition data is available.

Chakraborty, Monojit; Sharma, Chhemendra; Pandey, Jitendra; Singh, Nahar; Gupta, Prabhat K.

2011-12-01

344

COAL MINE METHANE EMISSIONS REDUCTION PROJECTS IN KUZBASS: SELECTION OF METHANE UTILIZATION OPTIONS, ECONOMICAL EFFICIENCY ASSESSMENTS AND FINANCE SOURCES  

Microsoft Academic Search

Coal mine methane resources of Kuznetsk coal basin in Russia amounts to over 13 trillion cubic meters. Presently 47 coal mines operate in the region and emit 216 million cubic meters of methane per year but unfortunately none of them attempt to utilize drained methane. Development of coal mine methane recovery and utilization is of great technological, economical and ecological

345

Methane and Nitrous Oxide Emissions from Rice-Duck and Rice-Fish Complex Ecosystems and the Evaluation of Their Economic Significance  

Microsoft Academic Search

Rice-duck (RD) and rice-fish (RF) ecological systems are major complex planting and breeding models of rice paddy fields in southern China. Studying the methane (CH4) and nitrous oxide (N2O) emissions and their economic value from these two ecosystems can provide theoretical and practical basis for further development and utilization of these classical agricultural techniques. CH4 and N2O emissions from RD

Wei-ling YUAN; Cou-gui CAO; Cheng-fang LI; Ming ZHAN; Ming-li CAI; Jin-ping WANG

2009-01-01

346

A Geochemical Model for the Origin of Methane on Titan  

NASA Astrophysics Data System (ADS)

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.

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

2007-12-01

347

Primary production control of methane emission from wetlands  

NASA Astrophysics Data System (ADS)

Based on simultaneous measurements of CO2 and CH4 exchange in wetlands extending from subarctic peatlands to subtropical marshes, a positive correlation between CH4 emission and net ecosystem production is reported. It is suggested that net ecosystem production is a master variable integrating many factors which control CH4 emission in vegetated wetlands. It is found that about 3 percent of the daily net ecosystem production is emitted back to the atmosphere as CH4. With projected stimulation of primary production and soil microbial activity in wetlands associated with elevated atmospheric CO2 concentration, the potential for increasing CH4 emission from inundated wetlands, further enhancing the greenhouse effect, is examined.

Whiting, G. J.; Chanton, J. P.

1993-08-01

348

Spatial variability of methane emissions in a Phragmites australis (Cav.) Trin. Ex Steud. dominated restored coastal brackish fen  

NASA Astrophysics Data System (ADS)

Methane is a major greenhouse gas that significantly contributes to global warming with a global warming potential 25 times higher than carbon dioxide over a 100 year time horizon. Recently, closed chamber measurements of methane are replaced by ecosystem based Eddy Covariance measurements where possible. However estimates of emission factors for single vegetation units still need chamber based measurements. The resulting emission factors may be influenced by the arrangement of measurement spots in the ecosystem. Here, we analyze the spatial variability of annual emissions estimates based on dynamic closed chamber measurements in pure and mixed stands of Phragmites australis (Cav.) Trin. ex Steud. in a restored coastal brackish fen. Annual methane emissions per measurement location vary largely between 76.54 and 1332 kg ha-1 a-1 CH4 but they do not differ significantly between pure and mixed stands of Phragmites australis. Mantel tests show no correlation of distances between spots and the variation in methane emissions (p

Koch, Stefan; Jurasinski, Gerald; Glatzel, Stephan

2013-04-01

349

In-flight measurement of aircraft non-methane hydrocarbon emission indices  

NASA Astrophysics Data System (ADS)

Concentrations of non-methane hydrocarbons (NMHC) and CO were measured in exhaust plumes of the DLR experimental aircraft ATTAS equipped with Rolls Royce M 45H Mk50l engines. The emission indices (EI) of individual light NMHC were determined from ratios of NMHC and CO concentration enhancements measured in grab samples and the concurrent in-flight measurements of EI of CO by FTIR emission spectroscopy. Alkenes and alkynes generated by cracking of larger NMHC molecules and aromatic compounds originating from unburnt fuel constituted a larger and a smaller fraction of the NMHC emissions, respectively.

Slemr, F.; Giehl, H.; Slemr, J.; Busen, R.; Schulte, P.; Haschberger, P.

350

Modeling flat flames burning chlorinated methanes in a methane/air environment  

SciTech Connect

A numerical model was developed to simulate flat flames burning chlorinated methanes in a methane/air environment. The model uses a reaction mechanism containing 341 reactions and 58 species. A time-stepping solution with linearized source terms and a strict convergence criteria had to be developed to allow for convergence of the conservation equations. Simulations of ten flames were made, five simulations of dichloromethane/methane/air flames, and five simulations of carbon tetrachloride/methane/air flames. For each fuel type, simulations were performed at a constant molar Cl/H ratio of 0.3 for a stoichiometric flame, a fuel-rich flame, and a fuel-lean flame. The other simulations were made for a constant stoichiometry with varying Cl/H ratio. For dichloromethane, the fuel equivalence ratio, {Phi}, was held at 0.8 while the Cl/H ratio was varied from 0.06 to 0.5, for carbon tetrachloride {Phi} was held at 0.95, while the Cl/H ratio was changed from 0.7 to 0.5. Comparisons to experiment were made for eight of the ten simulations. Available experimental data included the major species, and ten stable intermediates. The simulations are in good agreement with experiment for the major species profiles. The computational profiles for the stable intermediates are in good agreement with experiment for forty-eight percent of the seventy-nine computational species profiles compared to experiment. Seven percent of the comparisons are poor. These computational profiles have peak values that are more than a factor of ten larger or smaller than experiment. The simulation results were used to postulate reaction pathways for the combustion of dichloromethane, carbon tetrachloride, and methane. Burner effects were found to be important in the carbon tetrachloride flames.

Miller, G.P.

1989-01-01

351

A numerical evaluation on the effects of impermeable faults on degasification efficiency and methane emissions during underground coal mining  

Microsoft Academic Search

Impermeable geologic faults in the coal seam can cause intermittent production problems or can cause unexpected amounts of water or gas to issue from degasification boreholes. These faults also can impact methane emissions into the mine workings, especially if they hinder proper and effective degasification of the coal bed. They may also act as barriers for methane flow in the

C. Ö. Karacan; J. P. Ulery; G. V. R. Goodman

2008-01-01

352

Reduced methane emissions from large-scale changes in water management of China's rice paddies during 1980-2000  

Microsoft Academic Search

Decreased methane emissions from paddy rice may have contributed to the decline in the rate of increase of global atmospheric methane (CH4) concentration over the last 20 years. In China, midseason paddy drainage, which reduces growing season CH4 fluxes, was first implemented in the early 1980s, and has gradually replaced continuous flooding in much of the paddy area. We constructed

Changsheng Li; Jianjun Qiu; Steve Frolking; Xiangming Xiao; William Salas; Berrien Moore; Steve Boles; Yao Huang; Ronald Sass

2002-01-01

353

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 ...

354

Tropospheric methane emissions from cattails along a latitudinal gradient  

SciTech Connect

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.

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

1993-06-01

355

A VCSEL based system for on-site monitoring of low level methane emission  

NASA Astrophysics Data System (ADS)

Continuous monitoring of methane emissions has assumed greater significance in the recent past due to increasing focus on global warming issues. Many industries have also identified the need for ppm level methane measurement as a means of gaining carbon credits. Conventional instruments based on NDIR spectroscopy are unable to offer the high selectivity and sensitivity required for such measurements. Here we discuss the development of a robust VCSEL based system for accurate low level measurements of methane. A possible area of application is the measurement of residual methane whilst monitoring the output of flare stacks and exhaust gases from methane combustion engines. The system employs a Wavelength Modulation Spectroscopy (WMS) scheme with second harmonic detection at 1651 nm. Optimum modulation frequency and ramp rates were chosen to maintain high resolution and fast response times which are vital for the intended application. Advanced data processing techniques were used to achieve long term sensitivity of the order of 10-5 in absorbance. The system is immune to cross interference from other gases and its inherent design features makes it ideal for large scale commercial production. The instrument maintains its calibration and offers a completely automated continuous monitoring solution for remote on site deployment.

Kannath, A.; Hodgkinson, J.; Gillard, R. G.; Riley, R. J.; Tatam, R. P.

2011-02-01

356

Fugitive hydrocarbon emissions from pacific offshore oil platforms. Models, emission factors, and platform emissions  

SciTech Connect

In 1989, the U.S. Department of the Interior sponsored a field study that included the measurement of fugitive hydrocarbon emissions from seven offshore oil and gas production platforms located in outer continental shelf waters off the coast of Southern California. This study generated a set of emission factors for five different models for ten different combinations of component style and product stream as a function of a component's screening value measured one centimeter from the source with an organic vapor analyzer (OVA). These emission factors (ranging from 1 x 10[sup [minus]6] to 8.05 pounds of total hydrocarbon per day per component) are utilized together with an inventory of the components and the OVA screening value for each component to estimate total platform fugitive hydrocarbon emission rates. For the seven platforms included in this study, the total platform emission rates ranged from 42 to 140 pounds of hydrocarbon per day with more than 70 percent of the emissions due to a very small number of large emitters. The average platform non-methane emission rate was 20 pounds per day. A comparison with measurements made a decade ago indicates that technological advances and adoption of inspection and maintenance practices have reduced fugitive hydrocarbon emissions from these offshore facilities by more than 75 percent. 7 refs., 5 tabs.

Countess, R.J. (Hughes Environmental Systems, Inc., Manhattan Beach, CA (United States)); Browne, D. (Department of the Interior, Camarillo, CA (United States))

1993-11-01

357

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

NASA Astrophysics Data System (ADS)

Enhanced emissions of methane (CH4) and nitric oxide (NO) were measured following three controlled burns in a Florida wetlands in 1987 and 1988. Wetlands are the major global source of methane resulting from metabolic activity of methanogenic bacteria. Methanogens require carbon dioxide, acetate, or formate for their growth and the metabolic production of methane. All three water-soluble compounds are produced in large concentrations during biomass burning. Postfire methane emissions exceeded 0.15 g CH4 m-2 d-1. Nitric oxide is produced by nitrifying bacteria using ammonium as the substrate. Ammonium is also produced in large concentrations during biomass burning. Preburn and postburn measurements of soil nutrients indicate significant postburn increases in soil ammonium, from 8.35 to 13.49 parts per million (ppm) in the upper 5 cm of the Juncus marsh and from 8.83 to 23.75 ppm in the upper 5 cm of the Spartina marsh. Soil nitrate concentrations were found to decrease in both marshes after the fire. These measurements indicate that the combustion products of biomass burning exert an important "fertilizing" effect on the biosphere and on the biogenic production of environmentally significant atmospheric gases. These findings are particularly important since global biomass burning appears to be far more widespread and extensive than previously believed.

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

1990-02-01

358

Wetland Methane Emission Response to Last Glacial Maximum Atmospheric Carbon Dioxide Concentration  

NASA Astrophysics Data System (ADS)

Ice core records show that the atmospheric concentration of methane (CH4) during the Last Glacial Maximum (LGM) (~21,000 years ago) was 40% lower than the preindustrial Holocene. The contribution of natural wetlands to the global CH4 budget during the LGM is determined by modelling their spatial extent and productivity. Although models provide an estimated flux of ~75-180 Tg yr-1, they adopt present day physiological relationships to reconstruct past wetland emissions. Here we show that the LGM (180 ppm) carbon dioxide (CO2) concentration lowers CH4 emissions from peat cores incubated in controlled environments compared to cores maintained under a modern atmospheric CO2 concentration (380 ppm). Peat cores (110 x 400 mm) collected from a UK minerotrophic fen and upland ombrotrophic bog were maintained either in a [CO2] of 180 ppm or 380 ppm over 21 months. CH4 fluxes were measured on a monthly/weekly basis using static chambers with [CH4] measured via an LGR Fast CH4 Analyser and GC-FID. Results show that total CH4 flux from the minerotrophic fen was suppressed by 17 and 31% in season 1 and 2 respectively under LGM CO2 starvation. The ombrotrophic bog cores were suppressed by 20% in year 1 and 10% in year 2. Both peat types exhibited a rapid initial response to the sub-ambient [CO2] treatment with a change in CH4 flux recorded 5 days into the experiment. We also measured the influence of an LGM [CO2] atmosphere on CH4 flux temperature response during years 1 and 2. These results suggest that both wetland plants, and the underlying biogeochemistry of the rhizosphere, are sensitive to a reduction in [CO2] in the atmosphere and this has yet to be incorporated into global wetland CH4 models.

Boardman, C. P.; Gauci, V.; Beerling, D. J.

2008-12-01

359

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

NASA Astrophysics Data System (ADS)

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.

Malinverno, A.; Pohlman, J. W.

2011-07-01

360

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

USGS Publications Warehouse

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.

Malinverno, A.; Pohlman, J. W.

2011-01-01

361

Comparison of methods for estimating global methane emissions from landfills  

SciTech Connect

The paper discusses research efforts to improve methodologies for estimating landfill emissions. The paper discusses two key variables: the amount of refuse landfilled, and the CH4-generating potential of that refuse. Estimates of annual U.S. municipal solid waste production are compared, and the limitations of each method are reviewed. The implications for global data development are discussed.

Peer, R.L.; Thorneloe, S.A.; Epperson, D.L.

1993-01-01

362

SPECIAL TOPICS -- Mitigation of methane and nitrous oxide emissions from animal operations: I. A review of enteric methane mitigation options.  

PubMed

The goal of this review was to analyze published data related to mitigation of enteric methane (CH4) emissions from ruminant animals to document the most effective and sustainable strategies. Increasing forage digestibility and digestible forage intake was one of the major recommended CH4 mitigation practices. Although responses vary, CH4 emissions can be reduced when corn silage replaces grass silage in the diet. Feeding legume silages could also lower CH4 emissions compared to grass silage due to their lower fiber concentration. Dietary lipids can be effective in reducing CH4 emissions, but their applicability will depend on effects on feed intake, fiber digestibility, production, and milk composition. Inclusion of concentrate feeds in the diet of ruminants will likely decrease CH4 emission intensity (Ei; CH4 per unit animal product), particularly when inclusion is above 40% of dietary dry matter and rumen function is not impaired. Supplementation of diets containing medium to poor quality forages with small amounts of concentrate feed will typically decrease CH4 Ei. Nitrates show promise as CH4 mitigation agents, but more studies are needed to fully understand their impact on whole-farm greenhouse gas emissions, animal productivity, and animal health. Through their effect on feed efficiency and rumen stoichiometry, ionophores are likely to have a moderate CH4 mitigating effect in ruminants fed high-grain or mixed grain-forage diets. Tannins may also reduce CH4 emissions although in some situations intake and milk production may be compromised. Some direct-fed microbials, such as yeast-based products, might have a moderate CH4-mitigating effect through increasing animal productivity and feed efficiency, but the effect is likely to be inconsistent. Vaccines against rumen archaea may offer mitigation opportunities in the future although the extent of CH4 reduction is likely to be small and adaptation by ruminal microbes and persistence of the effect is unknown. Overall, improving forage quality and the overall efficiency of dietary nutrient use is an effective way of decreasing CH4 Ei. Several feed supplements have a potential to reduce CH4 emission from ruminants although their long-term effect has not been well established and some are toxic or may not be economically feasible. PMID:24045497

Hristov, A N; Oh, J; Firkins, J L; Dijkstra, J; Kebreab, E; Waghorn, G; Makkar, H P S; Adesogan, A T; Yang, W; Lee, C; Gerber, P J; Henderson, B; Tricarico, J M

2013-09-17

363

A Quantification of Climate Feedback from Permafrost Degradation, Thermokarst-Lake Expansion, and Subsequent Methane Emission Under Climate Policy and Uncertainty  

NASA Astrophysics Data System (ADS)

A direct consequence of climate warming in the Arctic will be the likelihood of widespread permafrost degradation. Subsequent subsidence of the landscape and hydrologic changes would then support the expansion of saturated areas such as thermokarst lakes and wetlands. These conditions over regions of carbon-rich, yedoma soils present a strong potential for increased methane emissions. In this study, we quantify the future changes in the high latitude near-surface permafrost and methane emission from thermokarst lake regions from climate projections of the 21st century. For the model simulations, we use the MIT Integrated Global System Model (IGSM) framework, which considers the full range of plausible transient climate response (TCR), emissions uncertainty with or without greenhouse gas stabilization targets, as well as a provision for uncertainty in regional climate changes. To account for this regional climate-change uncertainty, we modify the geographic shifts in precipitation, temperature and radiation conditioned by results from general circulation models (GCMs) of the Intergovernmental Panel on Climate Change (IPCC) archive. The numerical experiments with the IGSM indicate that the Arctic undergoes widespread and nearly complete degradation of the (near-surface) permafrost under a "No Policy" case. The uncertainties in TCR, emissions, and regional climate change have little effect on this end-of-century outcome, but affect the dynamic response. Under an aggressive greenhouse stabilization target and the full range of uncertainties, the IGSM simulations substantially reduce the permafrost degradation extent. Subsequent to the permafrost degradation, the simulated expanse of saturated areas can be large (up to 50%), but the uncertainties in TCR and the regional climate response have a large impact in both the dynamic and the end-of-century response. The corresponding, inferred increases in methane emission rates by the end of the century from thermokarst lakes range between 0.5-6.5 Tg-CH4/year for the "No Policy" case and 0.1-3.0 Tg-CH4/year for the stabilization projection. However, the resulting (global) atmospheric CH4 concentrations and radiative forcing from these increased thermokarst methane emissions is small, particularly when weighted against human emissions from the no-policy scenario. From the entirety of the IGSM simulations performed, we estimate that additional warming by the end of this century from the thermokarst lake methane emissions is no greater than 0.1 K. Further sensitivity simulations with the IGSM are presented to gauge the sensitivity of this temperature feedback on the uncertainty in the simulated terrestrial methane emission response.

Schlosser, C. A.; Gao, X.; Sokolov, A. P.; Walter Anthony, K.

2011-12-01

364

Methane emissions from Pantanal, South America, during the low water season: toward more comprehensive sampling.  

PubMed

Freshwater environments contribute 75% of the natural global methane (CH(4)) emissions. While there are indications that tropical lakes and reservoirs emit 58-400% more CH(4) per unit area than similar environments in boreal and temperate biomes, direct measurements of tropical lake emissions are scarce. We measured CH(4) emissions from 16 natural shallow lakes in the Pantanal region of South America, one of the world's largest tropical wetland areas, during the low water period using floating flux chambers. Measured fluxes ranged from 3.9 to 74.2 mmol m(-2) d(-1) with the average from all studied lakes being 8.8 mmol m(-2) d(-1) (131.8 mg CH(4) m(-2) d(-1)), of which ebullition accounted for 91% of the flux (28-98% on individual lakes). Diel cycling of emission rates was observed and therefore 24-h long measurements are recommended rather than short-term measurements not accounting for the full diel cycle. Methane emission variability within a lake may be equal to or more important than between lake variability in floodplain areas as this study identified diverse habitats within lakes having widely different flux rates. Future measurements with static floating chambers should be based on many individual chambers distributed in the various subenvironments of a lake that may differ in emissions in order to account for the within lake variability. PMID:20568738

Bastviken, David; Santoro, Ana Lucia; Marotta, Humberto; Pinho, Luana Queiroz; Calheiros, Debora Fernandes; Crill, Patrick; Enrich-Prast, Alex

2010-07-15

365

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)

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.

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

2005-07-01

366

Influences of flavomycin, ropadiar, and saponin on nutrient digestibility, rumen fermentation, and methane emission from sheep  

Microsoft Academic Search

This study focused on the effects of three additives given together with a hay\\/concentrate-based diet on nutrient digestibility, rumen fermentation, and methane emission from sheep. The basal diet consisted of 1.29kg mixed hay and 0.43kg concentrate mixture based on dry matter (DM). Treatments consisted of control (no additive), flavomycin40 (250mg\\/d), ropadiar from an oregano extract (250mg\\/d), and saponin in the

C. J. Wang; S. P. Wang; H. Zhou

2009-01-01

367

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

Microsoft Academic Search

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 CHâ m⁻² d⁻¹ and were

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

1990-01-01

368

Effects of elevated CO 2 and temperature on methane production and emission from submerged soil microcosm  

Microsoft Academic Search

\\u000a Incubation experiments were conducted under controlled laboratory conditions to study the interactive effects of elevated\\u000a carbon dioxide (CO2 ) and temperature on the production and emission of methane (CH4) from a submerged rice soil microcosm. Soil samples (unamended soil; soil + straw; soil + straw + N fertilizer) were placed\\u000a in four growth chambers specifically designed for a combination of

W. Cheng; K. Chander; K. Inubushi I

369

Interactions and coupling between emissions of methane and nitrous oxide from animal husbandry  

Microsoft Academic Search

The gases methane (CH4) and nitrous oxide (N2O) contribute to global warming, while N2O also affects the ozone layer. Sources of greenhouse gas emissions in animal husbandry include animals, animal houses (indoor\\u000a storage of animal excreta), outdoor storage, manure and slurry treatment (e.g., composting, anaerobic treatment), land application\\u000a and chemical fertilisers. Although in many countries emphasis is put on reduction

G. J. Monteny; C. M. Groenestein; M. A. Hilhorst

2001-01-01

370

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

Microsoft Academic Search

Methane is a potent greenhouse gas and its release to the atmosphere is widely believed to contribute to global warming. Ruminal enteric CH4 production represents a loss of 2–15% of the animal's gross energy (GE) intake and contributes nearly 20% of US CH4 emissions. Studies have evaluated the CH4 inhibiting potential of select short chain nitrocompounds, such as nitroethane, but

Erin G. Brown; Robin C. Anderson; Gordon E. Carstens; Hector Gutierrez-Bañuelos; Jackson L. McReynolds; Lisa J. Slay; Todd R. Callaway; David J. Nisbet

2011-01-01

371

Effectiveness of a subsurface drainage system in poorly drained paddy fields on reduction of methane emissions  

Microsoft Academic Search

Intensive field experiments were conducted from 1999 to 2001 to examine the effects of farmland improvement on methane (CH4) emission from two rice paddy fields in Niigata, Japan. Rice cultivation and field management were similar in both paddy fields; however, one field had a subsurface drainage system installed 0.6–0.8 m below the soil surface (drained paddy field) and the other had

Yutaka Shiratori; Hidekazu Watanabe; Yuichiro Furukawa; Haruo Tsuruta; Kazuyuki Inubushi

2007-01-01

372

Nitrous oxide and methane emissions following application of animal manures to grassland  

Microsoft Academic Search

Nitrous oxide (NâO) and methane (CHâ) emissions were measured from grassland following manure applications at three times of the year. Pig (Sus scrofa) slurry and dairy cow (Bos taurus) slurry were applied in April, at equal rates of ammoniacal-N (NHâ{sup +}-N), and in July, at equal volumetric rates (50 m³ha⁻¹). In October, five manure types were applied to grassland plots

D. R. Chadwick; B. F. Pain; S. K. E. Brookman

2000-01-01

373

Seasonal variation in methane emission from dairy cows and breeding ewes grazing ryegrass\\/white clover pasture in New Zealand  

Microsoft Academic Search

Daily methane emission from 12 Romney?cross?bred ewes and 10 lactating Friesian dairy cows, rotationally grazed on perennial ryegrass\\/white clover dominant pastures, was measured during four seasons of a year (September, November, March, and June\\/July). Methane emission was measured from each animal for 5 consecutive days in each measurement period using the sulphur hexafluoride tracer gas technique. The pastures varied significantly

M. J. Ulyatt; K. R. Lassey; I. D. Shelton; C. F. Walker

2002-01-01

374

Microwave Emission Models of Snow.  

National Technical Information Service (NTIS)

This study is concerned with the microwave emission models of dry snow and wet snow. A review of accomplished literature surveys on microwave emission models of snow is presented, which includes the characteristics of the constituents in the snow medium, ...

W. Huining

2001-01-01

375

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

NASA Astrophysics Data System (ADS)

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

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

2002-12-01

376

Methane emission from Texas rice paddy soils. 1. Quantitative multi-year dependence of CH4 emission on soil, cultivar and grain yield  

Microsoft Academic Search

Methane emissions at different rice productivity levels were observed from Texas rice paddy soils during the years 1991-95. Analysis of field measurements showed that seasonal methane emission (E) was strongly dependent on soil, cultivar, and rice grain yield. The relationship can be quantitatively described by E (g m-2) J 0.048 H SI H VI H GY. SI is a soil

L. S ASS; F RANK; M. F ISHER

1997-01-01

377

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

SciTech Connect

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.

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

1991-04-20

378

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

SciTech Connect

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.

Bartlett, K.B.; Crill, P.M. (College of William and Mary, Williamsburg, VA (USA)); Bonassi, J.A. (Universidade de Sao Paulo (Brazil)); Richey, J.E. (Univ. of Washington, Seattle (USA)); Harriss, R.C. (Univ. of New Hampshire, Durham (USA) NASA Langley Research Center, Hampton, VA (USA))

1990-09-20

379

Glacial wetland distribution and methane emissions estimated from PMIP2 climate simulations  

Microsoft Academic Search

The interglacial–glacial decrease in atmospheric methane concentration is often attributed to a strong decline in the wetland source. This seems consistent with the extreme coldness and vastly expanded ice sheets. Here we analyse coupled model simulations for the last glacial maximum from the Paleoclimate Modelling Intercomparison Project, using simple relations to estimate wetland characteristics from the simulated climate and vegetation.

S. L. Weber; A. J. Drury; W. H. J. Toonen; M. van Weele

2010-01-01

380

In situ spectrometric and chemical measurements of methane emissions from a natural marine hydrocarbon seep field, Coal Oil Point, California: Validation of methane remote sensing techniques  

NASA Astrophysics Data System (ADS)

Remote sensing techniques can significantly improve our understanding of the sources and sinks of the important greenhouse gas methane. Field and laboratory studies used spectral and in-situ chemical measurements of geologic methane plumes from natural marine seepage and radiative-transfer calculations to test the feasibility of using NASA's Airborne Visual/Infrared Imaging Spectrometer (AVIRIS) for methane remote sensing of this marine source. Based on numerical MODTRAN simulations, the spectral region between 2200 and 2340 nm was chosen for its sensitivity to CH4 with mild sensitivity to water vapor interference. During one marine field study, an intense seep area was repeatedly transected by boat using flame ion detectors (FID) to characterize the methane plume along with detailed meteorological measurements. Based on a Gaussian plume dispersion model for 3 m/s wind speed, methane column-abundances were calculated and showed a plume with methane concentrations greater than 0.5 g/m2 extending downwind 70 m with a 20 m width, much larger than the 3 to 5 m AVIRIS pixel size. Most of the methane was in the lower 10 m. MODTRAN calculations showed this to be well above the noise equivalent detection level of AVIRIS. During a separate field study, FIDs at three heights above the sea surface (2.2, 3.6, and 5 m) measured methane concentrations as high as 200 ppm while transecting an active seep area. Simultaneous spectra were obtained with a field spectrometer. Several plumes were identified from the FID data and a clear relationship was shown between the presence of methane plumes along the incident path and the presence of methane absorption features in spectra. Methane absorption features above atmospheric background were not observed outside the plumes.

Luyendyk, B. P.; Leifer, I.; Roberts, D.; Margolis, J. S.

2006-12-01