These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

2

Modeling methane emissions from boreal peatlands  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

3

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

E-print Network

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 ...

Locatelli, R.

4

DEVELOPMENT OF AN EMPIRICAL MODEL OF METHANE EMISSIONS FROM LANDFILLS  

EPA Science Inventory

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

5

DEVELOPMENT OF AN EMPIRICAL MODEL OF METHANE EMISSIONS FROM LANDFILLS  

EPA Science Inventory

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

6

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

E-print Network

Computer models were constructed to estimate methane emissions from cow/calf, replacement heifers, burs, stockers and feedlot sectors of the U.S. beef cattle industry. Methane (CH4) yields were calculated based on net energy values and forage...

Turk, Danny Carroll

2012-06-07

7

Modeling methane emissions by cattle production systems in Mexico  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

8

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

9

Modelling global methane emissions from livestock: Biological and nutritional controls  

NASA Technical Reports Server (NTRS)

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

Johnson, Donald E.

1992-01-01

10

Modelling the effects of climate change on methane emission from a northern ombrotrophic bog in Canada  

Microsoft Academic Search

Peatlands are a large potential source of methane (CH4) to the atmosphere. In order to investigate the effects of climate change on CH4 emission from northern ombrotrophic peatlands, a simulation model coupling water table dynamics with methane emission was\\u000a developed for the Mer Bleue Bog in Ontario, Canada. The model was validated against reported values of CH4 flux from field

Derrick Y. F. Lai

2009-01-01

11

Evaluation of a plot-scale methane emission model using eddy covariance observations and footprint modelling  

NASA Astrophysics Data System (ADS)

Most plot-scale methane emission models - of which many have been developed in the recent past - are validated using data collected with the closed-chamber technique. This method, however, suffers from a low spatial representativeness and a poor temporal resolution. Also, during a chamber-flux measurement the air within a chamber is separated from the ambient atmosphere, which negates the influence of wind on emissions. Additionally, some methane models are validated by upscaling fluxes based on the area-weighted averages of modelled fluxes, and by comparing those to the eddy covariance (EC) flux. This technique is rather inaccurate, as the area of upscaling might be different from the EC tower footprint, therefore introducing significant mismatch. In this study, we present an approach to validate plot-scale methane models with EC observations using the footprint-weighted average method. Our results show that the fluxes obtained by the footprint-weighted average method are of the same magnitude as the EC flux. More importantly, the temporal dynamics of the EC flux on a daily timescale are also captured (r2 = 0.7). In contrast, using the area-weighted average method yielded a low (r2 = 0.14) correlation with the EC measurements. This shows that the footprint-weighted average method is preferable when validating methane emission models with EC fluxes for areas with a heterogeneous and irregular vegetation pattern.

Budishchev, A.; Mi, Y.; van Huissteden, J.; Belelli-Marchesini, L.; Schaepman-Strub, G.; Parmentier, F. J. W.; Fratini, G.; Gallagher, A.; Maximov, T. C.; Dolman, A. J.

2014-09-01

12

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

E-print Network

Comparison of model estimates of the effects of aviation emissions on atmospheric ozone and methane emissions on atmospheric ozone for 2006 and two projections for 2050 are compared among seven models altitudes from 8 to 12 km. In this upper troposphere-lower stratosphere (UTLS) region, the ozone production

Jacobson, Mark

13

Methane Emission by Camelids  

PubMed Central

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

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

2014-01-01

14

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

15

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

PubMed

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

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

2014-09-01

16

Estimating methane gas generation from Devil's swamp landfill using greenhouse gas emission models  

NASA Astrophysics Data System (ADS)

Greenhouse gas (GHG) has been a key issue in the study, design, and management of landfills. Landfill gas (LFG) is considered either as a significant source of renewable energy (if extracted and processed accordingly) or significant source of pollution and risk (if not mitigated or processed). A municipal solid waste (MSW) landfill emits a significant amount of methane, a potent GHG. Thus, quantification and mitigation of GHG emissions is an important area of study in engineering and other sciences related to landfill technology and management. The present study will focus on estimating methane generation from Devils swamp landfill (DSLF), a closed landfill in Baton Rouge, LA. The landfill operated for 53 years (1940-1993) and contains both industrial and municipal waste products. Since the Clean Air Act of 1963, landfills are now classified as New Source Performance Standard (NSPS) waste (i.e., waste that will decompose to generate LFG). Currently, the DSLF is being used as source of renewable energy through the "Waste to Energy" program. For this study, to estimate the methane potential in the DSLF, it is important to determine the characteristics and classification of the landfill's wastes. The study uses and compares different GHG modeling tools---LandGEM, a multiphase model, and a simple first-order model---to estimate methane gas emission and compare results with the actual emissions from the DSLF. The sensitivity of the methane generation rate was analyzed by the methane generation models to assess the effects of variables such as initial conditions, specific growth rate, and reaction rate constants. The study concludes that methane (L0) and initial organic concentration in waste (k) are the most important parameters when estimating methane generation using the models.

Adeyemi, Ayodeji Thompson

17

The environmental impact of fertility in dairy cows: a modelling approach to predict methane and ammonia emissions  

Microsoft Academic Search

Dairy cows are estimated to contribute about 20% of total UK atmospheric methane emissions and 25% of total UK ammonia emissions. Previous models of atmospheric emissions have linked dietary inputs to gas emissions, but fertility models have not included emissions by herd replacements. The objective of this study was to construct a model that linked changes in fertility to herd

P. C Garnsworthy

2004-01-01

18

Modeling of methane bubbles released from large sea-floor area: Condition required for methane emission to the atmosphere  

NASA Astrophysics Data System (ADS)

Massive methane release from sea-floor sediments due to decomposition of methane hydrate, and thermal decomposition of organic matter by volcanic outgassing, is a potential contributor to global warming. However, the degree of global warming has not been estimated due to uncertainty over the proportion of methane flux from the sea-floor to reach the atmosphere. Massive methane release from a large sea-floor area would result in methane-saturated seawater, thus some methane would reach the atmosphere. In this study, we discussed the possibility of the methane release from a large sea-floor area to the atmosphere focusing on methane saturation in the water column necessary for a methane bubble to reach the atmosphere. Using a one-dimensional numerical model integrated over time, we predict methane bubbles and methane concentration in the water column under the condition of continuous methane input from the sea-floor to the water column. We found that some methane bubbles reach the atmosphere even when the methane saturation fraction in the water column is much lower than 100%. We compared the methane input from the sea-floor required for a methane bubble to reach the atmosphere to the amount of methane in the sediment in the form of methane hydrate and free gas. In most cases, our results suggest that the typical amount of methane in the sediment (i.e., typical hydrate fraction of ~ 2% and free gas of two-thirds of the amount of hydrate) is significantly lower than the required minimum methane input. It is, therefore, suggested that, except in the case of an extraordinary methane flux, the massive quantity of methane bubbles released from sea-floor gas hydrate would not reach the atmosphere directly but would be dissolved in the seawater. With regard to global warming due to human activities, the release of methane bubbles due to methane hydrate decomposition may not be enough to significantly accelerate total global warming. In the case of metamorphic methane release during PETM, there is the possibility that the released methane resulted in methane-saturated seawater, allowing some methane to reach the atmosphere.

Yamamoto, A.; Yamanaka, Y.; Tajika, E.

2009-07-01

19

Methane emissions from MBT landfills  

SciTech Connect

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

Heyer, K.-U., E-mail: heyer@ifas-hamburg.de; Hupe, K.; Stegmann, R.

2013-09-15

20

Estimates of surface methane emissions over Europe using observed surface concentrations and the FLEXPART trajectory model  

NASA Astrophysics Data System (ADS)

We use surface methane observations from nine European ground stations, and the FLEXPART Lagrangian transport model to obtain surface methane emissions for 2010. Our inversion shows the strongest emissions from the Netherlands and the coal mines in Upper Silesia Poland. This is qualitatively consistent with the EDGAR surface flux inventory. We also report significant surface fluxes from wetlands in southern Finland during July and August and reduced wetland fluxes later in the year. 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. We also use our trajectory model to determine whether future space-based remote sensing instruments (MERLIN) will be able to detect both natural and anthropogenic changes in the surface flux strengths.

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

2013-12-01

21

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

22

Modeling methane emissions from the Alaskan Yukon River basin, 19862005, by coupling a large-scale hydrological model  

E-print Network

Modeling methane emissions from the Alaskan Yukon River basin, 1986­2005, by coupling a large modeling framework was applied to the Yukon River basin at a spatial resolution of 1 km from 1986 to 2005 emissions from the Alaskan Yukon River basin, 1986­2005, by coupling a large-scale hydrological model

23

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

24

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

25

An Ecosystem Simulation Model for Methane Production and Emission from Wetlands  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

26

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

27

WHOLE FARM METHANE EMISSIONS USING A DISPERSION MODEL  

Technology Transfer Automated Retrieval System (TEKTRAN)

In Canada, dairy cows are estimated to contribute 27% of the emitted CH4 from livestock. This estimate, like many national greenhouse gas emissions factors, is extrapolated from experiments conducted under ideal conditions, which may not reflect actual farm emissions. Our objective was to determin...

28

Evaluation of a plot scale methane emission model at the ecosystem scale using eddy covariance observations and footprint modelling  

NASA Astrophysics Data System (ADS)

Most plot-scale methane emission models - of which many have been developed in the recent past - are validated using data collected with the closed-chamber technique. This method, however, suffers from a low spatial representativeness and a poor temporal resolution. Also, during a chamber-flux measurement the air within a chamber is separated from the ambient atmosphere, which negates the influence of wind on emissions. Additionally, some methane models are validated by upscaling fluxes based on the area-weighted averages of closed-chamber measurements, and by comparing those to the eddy covariance (EC) flux. This technique is rather inaccurate, as the area of upscaling might be different from the EC tower footprint, therefore introducing significant mismatch. In this study, we present an approach to validate plot-scale methane models with EC observations using the footprint-weighted average method. Our results show that the fluxes obtained by the footprint-weighted average method are of the same magnitude as the EC flux. More importantly, the temporal dynamics of the EC flux on a daily time scale are also captured (r2 = 0.7). In contrast, using the area-weighted average method yielded a low (r2 = 0.14) correlation with the EC measurements and an underestimation of methane emissions by 27.4%. This shows that the footprint-weighted average method is preferable when validating methane emission models with EC fluxes for areas with a heterogeneous and irregular vegetation pattern.

Budishchev, A.; Mi, Y.; van Huissteden, J.; Belelli-Marchesini, L.; Schaepman-Strub, G.; Parmentier, F. J. W.; Fratini, G.; Gallagher, A.; Maximov, T. C.; Dolman, A. J.

2014-03-01

29

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

30

An analytical model for estimating the reduction of methane emission through landfill cover soils by methane oxidation.  

PubMed

Landfill is an important source of atmospheric methane (CH4). In this study, the development and partial validation are presented for an analytical model for predicting the reduction of CH4 emission in landfill cover soils by CH4 oxidation. The model combines an analytic solution of a coupled oxygen (O2) and CH4 soil gas transport in landfill covers with a piecewise first-order aerobic biodegradation, including the influences of environmental factors such as cover soil thickness, CH4 oxidation and CH4 production rate. Comparison of soil gas concentration profiles with a soil column experiment is provided for a partial validation, and then this model is applied to predict the reduction of CH4 emission through landfill covers in several other cases. A discussion is provided to illustrate the roles of soil layer thickness, reaction rate constant for CH4 oxidation and CH4 production rate in determining CH4 emissions. The results suggest that the increase of cover soil thickness cannot always increase CH4 oxidation rates or removal efficiency, which becomes constant if the thickness of landfill cover soil is larger than a limit. PMID:25464331

Yao, Yijun; Su, Yao; Wu, Yun; Liu, Weiping; He, Ruo

2015-02-11

31

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. PMID:19141418

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

2009-01-01

32

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

USGS Publications Warehouse

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

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

2014-01-01

33

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

NASA Technical Reports Server (NTRS)

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

Walter, Bernadette P.; Heimann, Martin

1999-01-01

34

Future methane emissions from animals  

SciTech Connect

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

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

1993-04-20

35

A Variational Inverse Model Study of Amazonian Methane Emissions including Observations from the AMAZONICA campaign  

NASA Astrophysics Data System (ADS)

Methane (CH4) is a greenhouse gas which is emitted from a range of anthropogenic and natural sources, and since the industrial revolution its mean atmospheric concentration has climbed dramatically, reaching values unprecedented in at least the past 650,000 years. CH4 produces a relatively high radiative forcing effect upon the Earth's climate, and its atmospheric lifetime of approximately 10 years makes it a more appealing target for the mitigation of climate change over short timescales than long-lived greenhouse gases such as carbon dioxide. However, the spatial and temporal variation of CH4 emissions are still not well understood, though in recent years a number of top-down and bottom-up studies have attempted to construct improved emission budgets. Some top-down studies may suffer from poor observational coverage in tropical regions, however, especially in the planetary boundary layer, where the atmosphere is highly sensitive to emissions. For example, although satellite observations often take a large volume of measurements in tropical regions, these retrievals are not usually sensitive to concentrations at the planet's surface. Methane emissions from Amazon region, in particular, are often poorly constrained. Since emissions form this region, coming mainly from wetland and biomass burning sources, are thought to be relatively high, additional observations in this region would greatly help to constrain the geographical distribution of the global CH4 emission budget. In order to provide such measurements, the AMAZONICA project began to take regular flask measurements of CH4 and other trace gases from aircraft over four Amazonian sites from the year 2010 onwards. We first present a forward modelling study of these observations of Amazonian methane for the year 2010 using the TOMCAT Chemical Transport Model. The model is used to attribute variations at each site to a source type and region, and also to assess the ability of our current CH4 flux estimates to reproduce these observations. Although there is mostly good agreement between the modelled and observed CH4, we find discrepancies between the two at one site in the east of the region, indicating possible errors surrounding the surface fluxes of methane affecting this site. We also present the results of an inverse modelling study of methane emissions for the year 2010, using INVICAT, which is a new variational inverse model based upon TOMCAT. This study represents the first use of the INVICAT scheme to constrain emissions of an atmospheric trace gas. Similarly to many previous inverse model studies, this top-down study assimilates ground-based flask observations of CH4 from the NOAA ground network. However, in order to provide additional constraints of CH4 emissions in the Amazon region, flask observations taken as part of the AMAZONICA campaign are also assimilated. The results of this inversion provide improved Amazonian and global CH4 emission budgets for the year 2010.

Wilson, C. J.; Gloor, M.; Chipperfield, M.; Miller, J. B.; Gatti, L.

2013-12-01

36

Measuring methane emission rates of a dairy cow herd (II): results from a backward-Lagrangian stochastic model  

Microsoft Academic Search

We apply a backward-Lagrangian stochastic (BLS) model to determine methane (CH4) emission rates from a herd of dairy cows freely grazing pasture within a fenced paddock. We assess how model characteristics and measurement errors of the input variables contribute to the error of the emission rate. This error is of order 20%. We find a scattered but systematic trend for

Johannes Laubach; Francis M. Kelliher

2005-01-01

37

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

PubMed

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

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

2015-01-01

38

Prediction of enteric methane emissions from cattle.  

PubMed

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

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

2014-07-01

39

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

SciTech Connect

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

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

2011-08-15

40

Methane Emissions from Deciduous Trees  

NASA Astrophysics Data System (ADS)

There is some disagreement today over whether terrestrial plants present a significant source of methane to the atmosphere. Even if the plants are recognized as a source, there is no clear method to extrapolate plant emissions to the global atmospheric budget of methane and estimates vary widely. There is also no consensus on a mechanism for methane production and/or plant-mediated transport to the atmosphere. Here, we present preliminary data showing a significant flux of methane to the atmosphere from three wetland deciduous tree species. Ash (Fraxinus latifolia), cottonwood (Populus deltoides L.), and willow (Salix fluviatillis) were grown in a greenhouse under inundated rice-cultivation conditions using a rice straw amendment equivalent to 3 t/ha to enhance below ground anaerobic methane production. Results of measurements of redox potential and methane concentrations in soil pore water show significant methane production similar to that observed in rice plots (Oryza sative L. 'M-103') and controls of the same treatment. Measurements of the stable carbon isotopic composition (?13C) of methane dissolved in soil pore water show no significant difference from rice plots showing no discernable difference in bulk carbon substrate. Methane flux from trees, measured using static flux chamber and bag-tree enclosures, was found to be significantly higher than control treatments (i.e., no plants) but lower than rice plants overall. The carbon isotopic composition of emitted methane from tree species was found to be approximately 8‰ enriched in ?13C compared with methane emitted from rice. This difference in ?13C of emitted methane observed between rice and trees suggests the mechanisms contributing to regulating plant-mediated methane transport (e.g. transport, oxidation, carbon sources) may be quite distinct between diverse plant functional types. Identifying the mechanistic basis of this response will be a key development towards developing more accurate estimates of methane flux over local and regional scales.

Rice, A. L.; Teama, D.; Khalil, M. K.; Shearer, M. J.; Rosenstiel, T. N.

2008-12-01

41

Methane Emissions from Cattle  

Microsoft Academic Search

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

K. A. Johnson; D. E. Johnson

2010-01-01

42

Sensitivity and Uncertainty of High-Latitude Terrestrial Methane Emissions in a Changing Climate: Application of a Methane Biogeochemical Model in CLM4  

NASA Astrophysics Data System (ADS)

Current terrestrial methane biogeochemical models rely on a suite of uncertain mechanistic representations and process parameterizations. These uncertainties propagate to large-scale predictions of current and future methane emissions. To improve understanding of these uncertainties and how they may propagate to climate feedback analyses, we applied a recently developed and tested CH4 biogeochemistry submodel integrated in CLM4 (the land-surface model of the Community Earth System Model (CESM)). The model includes process-based representations of CH4 production, oxidation, aerenchyma transport, ebullition, aqueous and gaseous diffusion, and fractional inundation. The seasonality and magnitude of predicted CH4 emissions were compared with observations from 18 sites spanning the tropics to high latitudes. We also compared model predictions to two global atmospheric inversions and a wide range of previous bottom-up CH4 emission estimates. Using the model, we demonstrate that increased aerenchyma area tends to decrease net CH4 emissions when the water table is at the surface, but can increase emissions when the water table is below the surface. Sensitivity and uncertainty analyses across the model parameter space were used to identify the dominant parameters affecting regional and global CH4 emissions. The microbial temperature responses, aerenchyma characteristics, oxidation, and redox parameterizations had large impacts on high-latitude fluxes. Using the full range found in the literature for each of these parameters yields up to a factor of five range in high-latitude methane emissions. We will also characterize these uncertainties under future climate scenarios. Finally, we discuss observations and experiments that would facilitate improvement of the growing number of regional and global CH4 biogeochemical models.

Riley, W. J.; Subin, Z.; Lawrence, D. M.; Swenson, S. C.; Torn, M. S.; Meng, L.; Mahowald, N. M.; Hess, P. G.

2010-12-01

43

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

PubMed

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

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

2015-02-01

44

METHANE EMISSIONS FROM INDUSTRIAL SOURCES  

EPA Science Inventory

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

45

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

46

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

47

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

48

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

49

Improving a plot-scale methane emission model and its performance at a northeastern Siberian tundra site  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

50

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

51

Anthropogenic emissions of methane in the United States  

PubMed Central

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

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

2013-01-01

52

Anthropogenic emissions of methane in the United States.  

PubMed

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

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

2013-12-10

53

Methane emissions from Carex rostrata  

NASA Astrophysics Data System (ADS)

Peatlands, especially in northern regions, are known for their contribution to the increase of methane (CH4) in the atmosphere. Methane emissions from peatlands are strongly correlated with water table, temperature, and species composition. Sedges, in particular, are a conduit for the release of CH4 directly to the atmosphere. This study examines the impact of clipping and sealing sedges (Carex rostrata) on CH4 emissions from a temperate peatland (Sallie's Fen, Barrington, NH, USA). Measurements of CH4 fluxes, dissolved CH4, and environmental conditions were made over a six-year period. Data from 2008 to 2013 show that the presence of Carex rostrata in this peatland increases CH4 emissions. Clipped plots have both lower seasonal and annual CH4 emissions, compared to control plots. By studying the type of environment associated with C. rostrata through measurements of water-table depth, pore water characteristics, and the peat, surface, and air temperature of each surrounding location, further studies will show how these factors affect the rate at which CH4 is emitted into the atmosphere.

Yelverton, C. A.; Varner, R. K.; Roddy, S.; Noyce, G. L.

2013-12-01

54

Effects of permafrost thaw on northern wetland methane emissions  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

55

Impacts of climate change on methane emissions from wetlands  

Microsoft Academic Search

We have included climate-sensitive methane emissions from wetlands within the GISS climate model using a linear parameterization derived from a detailed process model. The geographic distribution of wetlands is also climate–dependent. Doubled CO2 simulations using this model show an increase in annual average wetland methane emissions from 156 to 277 Tg\\/yr, a rise of 78%. The bulk of this increase

Drew T. Shindell; Bernadette P. Walter; Greg Faluvegi

2004-01-01

56

Methane emissions (kt of CO2 equivalent)  

NSDL National Science Digital Library

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

World Bank

57

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

NASA Astrophysics Data System (ADS)

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 CH4 fluxes predicted by the revised DNDC model agreed well with observations. Seasonal CH4 emissions simulated by the revised model showed significantly higher correlation with observations than those obtained with the original model. Errors in the simulation appear to have resulted from uncertainties in both the input parameters and the model descriptions. Sensitivity analysis revealed that the revised DNDC model is highly sensitive to the concentration of reducible soil Fe, the rate of rice straw incorporation, and rice root biomass. Therefore, uncertainties in these factors may strongly affect the prediction of CH4 emissions. These results suggest that for reliable prediction of CH4 emissions from Thai rice fields, further work is needed to improve the estimates of reducible soil Fe, to quantify the rate of straw incorporation, and to parameterize the crop submodel for the dominant rice varieties grown in Thailand.

Smakgahn, Kruamas; Fumoto, Tamon; Yagi, Kazuyuki

2009-06-01

58

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

59

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 climate. Could the rice paddies in this domain be an important source of global methane? To answer this question, methane (CH4) emissions from the region were calculated by integrating remote sensing mapping with a process-based biogeochemistry model, Denitrification and Decomposition or DNDC. To quantify regional CH4 emissions from the plain, the model was first tested against a two-year dataset of CH4 fluxes measured at a typical rice field within the domain. 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 acquired in 2006, which provided crucial information about the spatial distribution of the rice fields within the domain of 10.93 million ha. The modeled results showed that the total 1.44 million ha of rice paddies in the plain emitted 0.48-0.58 Tg CH4-C in 2006 with spatially differentiated annual emission rates ranging between 38.6-943.9 kg CH4-C ha-1, 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.

2011-05-01

60

Ebullitive methane emissions from oxygenated wetland streams.  

PubMed

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

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

2014-11-01

61

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

PubMed

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

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

2014-01-01

62

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

63

APPROACH FOR ESTIMATING GLOBAL LANDFILL METHANE EMISSIONS  

EPA Science Inventory

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

64

Methane emissions from natural wetlands  

SciTech Connect

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

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

1993-09-01

65

Global methane emissions from pit latrines.  

PubMed

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

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

2014-08-01

66

Methane emission by adult ostriches (Struthio camelus).  

PubMed

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

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

2015-02-01

67

Quantification of Methane Emissions From Street Level Data  

NASA Astrophysics Data System (ADS)

The problem of identifying, attributing, and quantifying methane emissions from urban sources such as landfills, waste-water treatment facilities and natural gas distribution systems is an active area of research. This interest is fueled, in part, by recent measurements indicating that urban emissions are a significant source of methane (CH4, a potent greenhouse gas) and in fact may be substantially higher than current inventory estimates. As a result, developing methods for locating and quantifying emissions from urban methane sources is of great interest to industries such as landfill owners, and governmental agencies. In an attempt to identify major methane source locations and emissions in the city of Indianapolis, systematic measurements of CH4 concentrations and meteorology data were made at street level using multiple vehicles equipped with cavity ring-down spectrometers. A number of discrete sources were detected at methane molar ratios in excess of 15 times background levels. The street level data is analyzed with plume inversion models including Weather Research and Forecasting (WRF) software, Fire Dynamics Simulator (FDS) and backward Lagrangian Simulations (bLS) to identify source location and emission rates. The methodology for analyzing the street level data and our estimates of CH4 emissions from various sources in the city of Indianapolis will be presented.

Prasad, K.; Cambaliza, M. L.; Lavoie, T. N.; Salmon, O. E.; Shepson, P. B.; Lauvaux, T.; Davis, K. J.; Whetstone, J. R.

2013-12-01

68

Future methane emissions from animals  

NASA Astrophysics Data System (ADS)

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

Anastasi, C.; Simpson, V. J.

1993-04-01

69

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

70

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

SciTech Connect

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

Johnson, D.E.

1992-10-01

71

Diurnal variations in methane emission from rice plants  

E-print Network

A greenhouse study was conducted to investigate the mechanisms causing diurnal variations in methane emission from rice plants (Oryza sativa L.). Methane emission was measured using a closed chamber system on individual rice plants at five stages...

Laskowski, Nicholas Aaron

2004-11-15

72

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 ...

73

Diel methane emission patterns from Scirpus lacustris and Phragmites australis  

Microsoft Academic Search

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

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

1998-01-01

74

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 ...

75

Higher Methane Emissions in Regions of Sea Ice Retreat  

NASA Astrophysics Data System (ADS)

In recent decades, the Arctic has lost more and more sea ice, which has concurrently led to higher temperatures across the high latitudes (Screen et al., 2012). Although increasingly strong evidence exists for this link between sea ice and temperature, the extra step of linking sea ice retreat - through these climatic changes - to a change in greenhouse-gas exchange is much less clear. Recently, however, it has been suggested that methane emissions have increased while sea ice declined (Parmentier et al., 2013). This initial analysis compared average methane emissions for the Arctic Region with anomalies in the average sea ice extent, which evens out regional differences. Year-to-year variations in sea ice extent are different from region to region and would therefore impact methane emissions - through temperature - differently, too. Our goal is therefore to evaluate, with the use of models, whether methane emissions are more strongly correlated to sea ice in areas of high retreat rather than in areas that have seen little variation in sea ice. For this use, the output from three regional methane models (LPJ-GUESS WhyMe, Peatland-VU and TEM6), designed to be applied to the Arctic Region, are compared to sea ice decline. A similar spatial response to sea ice retreat by these models will increase our confidence that methane emissions in the Arctic are indeed spatially linked to sea ice decline. References: Parmentier, F. J. W., Christensen, T. R., Sørensen, L. L., Rysgaard, S., McGuire, A. D., Miller, P. A., & Walker, D. A. (2013). The impact of lower sea-ice extent on Arctic greenhouse-gas exchange. Nature Climate Change, 3, 195-202. doi:10.1038/nclimate1784 Screen, J. A., Deser, C., & Simmonds, I. (2012). Local and remote controls on observed Arctic warming. Geophysical Research Letters, 39, L10709. doi:10.1029/2012GL051598

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

2014-05-01

76

Atmospheric Impact of Large Methane Emission in the Arctic Region  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

77

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

78

Timelines for mitigating methane emissions from energy technologies  

E-print Network

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

Roy, Mandira; Trancik, Jessika E

2015-01-01

79

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

E-print Network

Methane oxidation associated with submerged brown mosses reduces methane emissions from Siberian (methanotrophy) associated with submerged brown moss species occurs in polygonal tundra environments of the Siberian Arctic. Methanotrophic bacteria living in close association with mosses are thus not restricted

Wehrli, Bernhard

80

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

PubMed

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

Muha, Ivo; Linke, Bernd; Wittum, Gabriel

2015-02-01

81

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...

82

Impact of Changes in Barometric Pressure on Landfill Methane Emission  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

83

Assessment of RANS-Based Turbulent Combustion Models for Prediction of Emissions from Lean Premixed Combustion of Methane  

Microsoft Academic Search

Reynolds-Averaged Navier-Stokes (RANS) simulations of Lean Premixed Combustion (LPC) of methane–air in a bluff-body stabilized combustor were performed with several widely used turbulent combustion methodologies in order to assess their prediction capabilities. The methods employed are the Eddy Dissipation Concept (EDC), the Composition Probability Density Function (CPDF) and the Joint Velocity–Frequency-Composition PDF (VFCPDF) models. Where needed, two different models were

J. R. Nanduri; D. R. Parsons; S. L. Yilmaz; I. B. Celik; P. A. Strakey

2010-01-01

84

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

85

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

E-print Network

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

86

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

87

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

88

Inventory of methane emissions from U.S. cattle  

Microsoft Academic Search

Many countries, including the United States, are in the process of inventorying greenhouse gas emissions as a prerequisite for designing control strategies. We have developed a measurement-based inventory of methane emissions from cattle in the United States. Methane emission factors were established for the major livestock groups using an internal tracer method. The groups studied included cows, replacement heifers, slaughter

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

2001-01-01

89

Estimation of methane emissions from a wastewater treatment plant in Valence  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

90

Methane emissions from Alaska in 2012 from CARVE airborne observations.  

PubMed

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

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

2014-11-25

91

Methane emission from Yangtze estuarine wetland, China  

NASA Astrophysics Data System (ADS)

Yangtze estuary, lying in the subtropical monsoon region of China, is characterized by a unique environmental setting and endemic wetland plant species (Scirpus mariqueter). Methane (CH4) emission fluxes were measured at the Yangtze estuarine wetland, Chongming Dongtan (CD), by a static closed chamber technique from May 2004 to April 2005. The results showed that CD is the source of atmospheric CH4, and emission fluxes had significant diurnal and seasonal variation. The annual average CH4 emission flux was 2.06 mg m-2 h-1 at the CD marsh site and 0.04 mg m-2 h-1 at the CD bare tidal flat (nonvegetated). Wetland plant species (S. mariqueter) and temperature were the primary factors controlling the CH4 emission. The results of the light and dark chamber comparison and plant shoot clipping experiment suggest that molecular diffusion and convective gas flow methods were the two main mechanisms of CH4 transported via S. mariqueter plants in July. However, molecular diffusion was believed to be the primary transport mechanism from August to October, with leaf resistance as one of the factors regulating CH4 diffusion. There was significant correlation between CH4 fluxes and temperature, especially the 10 cm depth ground temperature (R2 = 0.7784). Although sediment organic carbon content did not determine CH4 fluxes, net ecosystem production was significantly correlated with CH4 fluxes, suggesting that the photosynthates of S. mariqueter effectively provided the substrate for methanogenic bacteria.

Wang, Dongqi; Chen, Zhenlou; Xu, Shiyuan

2009-06-01

92

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

SciTech Connect

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

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

1994-12-31

93

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

PubMed

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

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

2014-07-21

94

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

PubMed

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

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

2015-02-01

95

Methane Emissions from Rice Fields - Final Report  

SciTech Connect

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.

Khalil, M. Aslam; Rasmussen,Reinhold A.

2002-12-03

96

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

97

Non-microbial methane emissions from soils  

NASA Astrophysics Data System (ADS)

Traditionally, methane (CH4) is anaerobically formed by methanogenic archaea. However, non-microbial CH4 can also be produced from geologic processes, biomass burning, animals, plants, and recently identified soils. Recognition of non-microbial CH4 emissions from soils remains inadequate. To better understand this phenomenon, a series of laboratory incubations were conducted to examine effects of temperature, water, and hydrogen peroxide (H2O2) on CH4 emissions under both aerobic and anaerobic conditions using autoclaved (30 min, 121 °C) soils and aggregates (>2000 ?m, A1; 2000-250 ?m, A2; 250-53 ?m, M1; and <53 ?m, M2). Results show that applying autoclaving to pre-treat soils is effective to inhibit methanogenic activity, ensuring the CH4 emitted being non-microbial. Responses of non-microbial CH4 emissions to temperature, water, and H2O2 were almost identical between aerobic and anaerobic conditions. Increasing temperature, water of proper amount, and H2O2 could significantly enhance CH4 emissions. However, the emission rates were inhibited and enhanced by anaerobic conditions without and with the existence of H2O2, respectively. As regards the aggregates, aggregate-based emission presented an order of M1 > A2 > A1 > M2 and C-based emission an order of M2 > M1 > A1 > A2, demonstrating that both organic carbon quantity and property are responsible for CH4 emissions from soils at the scale of aggregate. Whole soil-based order of A2 > A1 > M1 > M2 suggests that non-microbial CH4 release from forest soils is majorly contributed by macro-aggregates (i.e., >250 ?m). The underlying mechanism is that organic matter through thermal treatment, photolysis, or reactions with free radicals produce CH4, which, in essence, is identical with mechanisms of other non-microbial sources, indicating that non-microbial CH4 production may be a widespread phenomenon in nature. This work further elucidates the importance of non-microbial CH4 formation which should be distinguished from the well-known microbial CH4 formation in order to define both roles in the atmospheric CH4 global budget.

Wang, Bin; Hou, Longyu; Liu, Wei; Wang, Zhiping

2013-12-01

98

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

99

Methane Emissions of Differently Fed Dairy Cows and Corresponding Methane and Nitrogen Emissions from their Manure during Storage  

Microsoft Academic Search

This study investigated the effects of supplementing 40 g lauric acid (C12) kg-1 dry matter (DM) in feed on methane emissions from early-lactating dairy cows and the associated effects on methane, nitrous oxide and ammonia release from the manure during storage. Stearic acid (C18), a fatty acid without assumed methane-suppressing potential in the digestive tract of ruminants, was added at

D. R. Külling; Frigga Dohme; H. Menzi; F. Sutter; P. Lischer; M. Kreuzer

2002-01-01

100

Impact of changes in barometric pressure on landfill methane emission  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

101

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

NASA Technical Reports Server (NTRS)

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

King, G. M.

1997-01-01

102

Extreme Methane Emissions from a Swiss Hydropower Reservoir  

E-print Network

Extreme Methane Emissions from a Swiss Hydropower Reservoir: Contribution from Bubbling Sediments and their importance were quantified during a yearlong survey of a temperate hydropower reservoir. Measurements using measured in the reservoir discharge. A strong positive correlation between water temperature

Wehrli, Bernhard

103

MEASUREMENT OF METHANE EMISSIONS FROM UNDERGROUND DISTRIBUTION MAINS AND SERVICES  

EPA Science Inventory

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

104

Quantifying methane emissions from rice fields in Tai-Lake region, China by coupling detailed soil database with biogeochemical model  

NASA Astrophysics Data System (ADS)

China's paddy rice accounts for about 22% of the world's rice fields, therefore it is crucial to accurately estimate the CH4 emissions at regional scale to gauge their contribution to global greenhouse gas effect. This paper reports an application of a biogeochemical model, DeNitrification and DeComposition or DNDC, for quantifying CH4 emissions from rice fields in Tai-Lake region of China by linking DNDC to a 1:50 000 soil database, which was derived from 1107 paddy soil profiles in the Second National Soil Survey of China in the 1980s-1990s. The modeled results estimate that the 2.34 M ha of paddy rice fields in Tai-Lake region emitted about CH4 of 5.67 Tg C for the period of 1982-2000, with the average CH4 flux ranged from 114 to 138 kg C ha-1y-1. The highest emission rate (659.24 kg C ha-1 y-1) occurred in the subgroup of "gleyed paddy soils", while the lowest (90.72 kg C ha-1y-1) were associated with the subgroup "degleyed paddy soils". The subgroup "hydromorphic paddy soils" accounted for about 52.82% of the total area of paddy soils, the largest of areas of all the soil subgroups, with the CH4 flux rate of 106.47 kg C ha-1y-1. On a sub-regional basis, the annual average CH4 flux in the Tai-Lake plain soil region and alluvial plain soil region was higher than that in low mountainous and hilly soil region and polder soil region. The model simulation was conducted with two databases using polygon or county as the basic unit. 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 CH4 emissions in Tai-Lake region. However, discrepancies exist between the results from the two methods, the relative deviation is -42.10% for the entire region, and the relative deviation ranged from -19.53% to 97.30% for most counties, which indicates that the more precise soil database was necessary to better simulate CH4 emissions from rice fields in Tai-Lake region using the DNDC model.

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

2008-12-01

105

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.

Kaufmann, Robert K.

1998-01-01

106

Inventory of methane emissions from U.S. cattle  

NASA Astrophysics Data System (ADS)

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

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

2001-01-01

107

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

108

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

2014-10-01

109

Methane emissions from a temperate agricultural reservoir  

EPA Science Inventory

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

110

Prediction of Methane Production from Dairy Cows Using Existing Mechanistic Models and Regression Equations1  

Microsoft Academic Search

Ruminants may contribute to global warming through the release of methane gas by enteric fermentation. Until now, methane emissions from ruminants were estimated using simple regres- sion equations. The objective of this study was to compare the capacity of dynamic and mechanistic models to that of regression equations to predict methane production from dairy cows. The updated version of the

C. Benchaar; J. Rivest; C. Pomar; J. Chiquette

111

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

112

Methane emissions from dairy cows: Comparing open-path laser measurements to profile-based techniques  

Microsoft Academic Search

Methane emission rates from a herd of grazing dairy cows were determined from concentration measurements with four open-path lasers positioned around the fenced grazing area. The emission rates were calculated with the aid of a backward-Lagrangian stochastic model (BLS). After discarding data with insufficient laser light levels (due to technical issues discussed in the paper) and periods of light winds,

Johannes Laubach; Francis M. Kelliher

2005-01-01

113

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

114

ESTIMATE OF GLOBAL METHANE EMISSIONS FROM COAL MINES  

EPA Science Inventory

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

115

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

116

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...

117

Aerobic methane emissions from stinkweed (Thlaspi arvense) capsules.  

PubMed

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

Qaderi, Mirwais M; Reid, David M

2014-10-01

118

Natural emissions of methane from geological seepage in Europe  

Microsoft Academic Search

Recent studies have shown that geological emissions of methane are an important greenhouse-gas source. Remarkable amounts of methane, estimated in the order of 40–60Tgyr?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

Giuseppe Etiope

2009-01-01

119

Methane emissions from an alpine fen in central Switzerland  

Microsoft Academic Search

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

Susanne Liebner; Simon P. Schwarzenbach; Josef Zeyer

120

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

121

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

122

Methane emissions measured directly from grazing livestock in New Zealand  

NASA Astrophysics Data System (ADS)

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

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

123

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

124

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

125

Simulating the effects of grassland management and grass ensiling on methane emission from lactating cows  

Microsoft Academic Search

A dynamic, mechanistic model of enteric fermentation was used to investigate the effect of type and quality of grass forage, dry matter intake (DMI) and proportion of concentrates in dietary dry matter (DM) on variation in methane (CH4) emission from enteric fermentation in dairy cows. The model represents substrate degradation and microbial fermentation processes in rumen and hindgut and, in

A. Bannink; M. C. J. Smits; E. Kebreab; J. A. N. Mills; J. L. Ellis; A. Klop; J. Dijkstra

2010-01-01

126

Methane emissions from enteric fermentation in dairy cows, 1990-2008  

Microsoft Academic Search

The Dutch protocol for the national inventory estimates the methane emission of the average Dutch dairy cow based on a Tier 3 approach. A dynamic, mechanistic model is used to represent the enteric fermentation processes, using annual national statistics on feed intake and feed composition as model inputs. Dutch dairy rations are based mainly on roughage (3\\/4 of dry matter

A. Bannink

2011-01-01

127

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...

128

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

129

A model study of mechanisms of methane transfer from Arctic shelf to the atmosphere  

NASA Astrophysics Data System (ADS)

A possible positive feedback to rapid climate warming in Arctic - degradation of methane hydrates in the shelf bottom ground - has recently attracted attention of many research groups. This was primarily caused by new empirical evidence of very high concentrations of dissolved methane in Russian Arctic and methane fluxes to the atmosphere. A number of studies were conducted to access a possible effect of methane hydrates degradation in response to future warming of the ocean. Climate change scenarios were used to force the models of heat transfer in shelf ground. However, in majority of these works it was assumed that all methane released from shelf bottom reaches atmosphere. This precludes the possibility of taking into account methane bubbles dissolution, methane oxidation and subsequent ocean acidification effects. In this study we apply three modeling frameworks for quantifying these effects. First, one-dimensional (in vertical) model of water reservoir is used (Stepanenko et al. 2011), calculating vertical profiles of dissolved methane, bubbles' parameters and emission to the atmosphere. This model utilizes a bubble model by McGinnis et al. (2006), and diffusion-reaction equations for methane, oxygen and carbon dioxide concentrations in dissolved state. Thus, interaction between bubbles and dissolved gases and methane oxidation are described explicitly. Second, one-dimensional methane model is forced by temperature profile and eddy diffusion coefficients from 3D ocean dynamics model (Iakovlev 2009). And third, methane model is coupled to 3D ocean dynamics model allowing to reproduce advection of methane by oceanic currents in addition to above mentioned processes. This set of experiments allows to assess a significance of ocean dynamics for bottom-released methane transport and methane emission to the atmosphere. Since a number of parameters (e.g. initial bubble radius at the bottom, constants entering reaction rates formulae) are highly uncertain due to lack of relevant observational data, a sensitivity study if performed in respect to these parameters.

Stepanenko, V. M.; Iakovlev, N. G.

2012-04-01

130

Salinity and organic amendment effects on methane emission from a rain-fed saline paddy field  

Microsoft Academic Search

Organic amendment is a traditional practice for rehabilitating saline patches in north-east Thailand, but organic matter is known to enhance methane emission. However, a high degree of salinity might mitigate methane emission. The objective of the present study was to quantify the effects of salinity and organic amendments on methane emission from rain-fed paddy fields exposed to increasing salinity. A

Sakulrat Supparattanapan; Patcharee Saenjan; Cécile Quantin; Jean Luc Maeght; Olivier Grünberger

2009-01-01

131

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

132

On the gas hydtrate methane emissions and possible hypoxia in the East Siberian Arctic Seas  

NASA Astrophysics Data System (ADS)

Recent field companies showed the high concentrations of dissolved methane in the region of East Siberian Arctic Seas (ESAS). These high concentrations were attributed to the degradation of the underwater permafrost which corked the methane from the shallow gas-hydrates deposits (Shakhova, et. al., 2010). Some aspects of the problem of the methane evolution, released at ESAS, were investigated in (Malakhova amd Golubeva, 2013), where the estimated methane emission to the atmosphere was two order lower than the estimates by Shakhova, et.al., 2010. In this study the version of the regional 3D coupled ice-ocean model FEMAO-1 was applied to the problem of the methane transport, oxidation and emission to the atmosphere. Model was driven by the AOMIP-FAMOS forcing 1948-2011, and showed the steady rise of mean bottom temperature at ESAS after 1990 till now. This temperature rise assumed to be sufficient to destabilize undersea permafrost and provoke the additional methane release from gas-hydrates. A set of numerical experiments were carried out to simulate various scenarios of the methane evolution: 1. The quasi-equilibrium state of the dissolved methane distribution forced by the sources at the continental slope and river runoff transport for the period of 1948-1990. This set of experiments was aimed to reproduce the observed methane concentrations and to tune the model parameterizations. 2. The scenario of ESAS abrupt methane release during 1990-2011 with various fractions of dissolved methane and bubbles. The fractions of the dissolved methane and bubbles were previously estimated in (Stepanenko and Iakovlev, 2013). This set of experiments was aimed to reproduce the observed vertical methane distribution with maximum at the ocean surface. 3. The ESAS abrupt methane release with limitation of oxidation in areas of hypoxia. This set of experiments was aimed to evaluate the possibility of hypoxia at the ESAS shelf and beyond, and to estimate the required methane flux to switch off the oxidation. Acknowledgements: This work was supported by the Russian Foundation for Basic Research Project 13-05-12052ofi_m. References. Shakhova, N., I.Semiletov, A.Salyuk, V.Yusupov, D.Kosmach, and Ö.Gustafsson. Extensive Methane Venting to the Atmosphere from Sediments of the East Siberian Arctic Shelf. Science 5 March 2010: Vol. 327 no.5970 pp. 1246-1250 DOI: 10.1126/science.1182221. Malakhova, V. and E. Golubeva. On the possible methane emissions from the East Siberian Arctic Seas. Geophysical Research Abstracts Vol. 15, EGU2013-4480, 2013, EGU General Assembly 2013. Iakovlev, N.G. On the Simulation of Temperature and Salinity Fields in the Arctic Ocean. Izvestiya, Atmospheric and Oceanic Physics. 2012. 48(1), pp. 86-101. doi: 10.1134/S0001433812010136. V. Stepanenko and N. Iakovlev. Numerical simulation of vertical transport and oxidation of methane in Arctic Ocean. Geophysical Research Abstracts Vol. 15, EGU2013-4009-1, 2013, EGU General Assembly 2013.

Iakovlev, Nikolay

2014-05-01

133

Assessment of nitrous oxide and methane emissions for California agriculture  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

134

Methodology of Estimation of Methane Emissions from Coal Mines in Poland  

NASA Astrophysics Data System (ADS)

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

Paty?ska, Renata

2014-03-01

135

In situ sensing of methane emissions from natural marine hydrocarbon seeps: A potential remote sensing technology  

Microsoft Academic Search

The sources and sinks of methane, an important greenhouse gas, are poorly constrained. Remote sensing techniques can significantly improve our understanding of the global methane budget. Field and laboratory studies using in situ direct and spectral measurements of methane emissions from natural marine seepage allowed assessment of the feasibility of remote sensing. Methane plume characteristics were estimated by repeated transects

Ira Leifer; Dar Roberts; Jack Margolis; Frank Kinnaman

2006-01-01

136

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

137

Global Scale Methane Emissions from On-Site Wastewater Management  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

138

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

139

Methane emission from mires of the West Siberian taiga  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

140

Methane emission by Nellore cattle subjected to different nutritional plans.  

PubMed

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

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

2014-10-01

141

Methane production, oxidation and emission in United Kingdom peatlands and the effect of anions from acid rain  

NASA Astrophysics Data System (ADS)

The production, oxidation and emission of methane in UK peatlands was investigated. The main field study site was Ellergower Moss, Dumfriesshire where the peat was characterised by hollows (water-filled depressions) and hummocks (raised vegetative areas). The pathways of carbon flow in peat under hummocks and hollows were determined and compared on a seasonal basis. Methane emissions were significantly greater from hollows than hummocks (0.88 mols and 0.07 mols CH4 m-2 y-1 respectively). Methane emission rates varied seasonally e.g. for hollows were 0.04 mmols CH4 m-2 d-1 for January and 2.3 mmols CH4 m-2 d-1 for June. Methane emissions were modulated by biological methane oxidation by 0% of methane produced in the winter months, increasing during spring until 97% of methane produced was oxidised in the summer months. Both methane oxidation and methanogenesis were strongly temperature dependant with Q10 values of 2.2 and 16, respectively. Rates of methane oxidation potential (MOP) were greatest between 4-8 cm depths below the level of the water table, and were located above the most active zone of methanogenesis (8-16 cm depths below the water table levels). This enabled vertically diffusing methane to be utilised by methanotrophic bacteria, providing a very efficient filter for methane. Methanogenesis was limited by hydrogen availability in the peat, but not by acetate, suggesting that methane was produced by hydrogenophilic methanogenic bacteria (MB), rather than acetate utilising MB. Acid rain pollutants were found to significantly affect carbon flow, with sulphate deposition causing a seasonal inhibition in methanogenesis. Carbon flow predominated through sulphate reduction in the winter and spring months (sulphate reduction to methane production ratio was 1008 and 189, for hummocks and hollows respectively) when sulphate was freely available and when temperatures were low. During the summer when temperatures increased and sulphate became limited carbon flow through methanogenesis predominated (sulphate reduction to methane production ratio 0.39 and 0.07, for hummocks and hollows respectively). The examination of two other peatlands-Great Dun Fell and Caithness which received higher and lower sulphate loadings than Ellergower respectively, did not show a consistent effect of sulphate inhibition on methanogenesis. The methane oxidation kinetics were used in a mathematical model to examine the effect of plant roots on increasing the vertical transport rate of methane out, and oxygen into the peat, by gas phase transport through the roots. (Abstract shortened by UMI.)

Watson, Andrea

142

Methane from the Tropospheric Emission Spectrometer (TES)  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

143

A model of enteric fermentation in dairy cows to estimate methane emission for the Dutch National Inventory Report using the IPCC Tier 3 approach  

Microsoft Academic Search

The protocol for the National Inventory of agricultural greenhouse gas emissions in The Netherlands includes a dynamic and mechanistic model of animal digestion and fermentation as an Intergovernmental Panel on Climate Change (IPCC) Tier 3 approach to estimate enteric CH4 emission by dairy cows. The model differs from an IPCC Tier 2 approach in that it predicts hydrogen sources (i.e.,

A. Bannink; M. W. van Schijndel; J. Dijkstra

2011-01-01

144

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

145

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

146

The estimation of methane emissions from landfills with different cover systems  

NASA Astrophysics Data System (ADS)

Methane is a very potent greenhouse gas, second only to CO2 as an anthropogenic contributor to global warming. Landfills are important anthropogenic source in the CH4 emissions. Microbially mediated CH4 oxidation in landfills with conventional soil covers can serve as an efficient biological sink. Methane from modern sanitary landfills equipped with composite covers and gas collection system is vented directly to the atmosphere, except for some of the largest landfills at which it is collected and burned. However, previous laboratory research has shown that biofilters have the potential to reduce CH4 emissions from landfills with modern composite covers. In this study a CH4 emission model was developed. The model used the calculated CH4 oxidation rates to estimate CH4 emissions from landfills constructed with conventional soil covers, modern composite covers, and modern composite covers plus biofilters. According to the CH4 emission rates predicted by CH4 emission model, it was estimated that 90% of the generated CH4 was emitted to the atmosphere for landfills with modern composite cover. For landfills with modern composite cover plus biofilters, an average of only 9% of the generated CH4 was estimated to be emitted. For landfills with conventional covers, an average of 83% of the generated CH4 was estimated to be emitted. By comparing the CH4 emission rates from three different landfill types, the use of a properly managed biofilter should be an effective technique to reduce CH4 emissions from landfills.

Park, S.; Lee, K.; Sung, K.

2006-12-01

147

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

148

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

149

Methane and ammonia emissions from New Mexico dairy lagoons in summer  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

150

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

151

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

152

Global annual methane emission rate derived from its current atmospheric mixing ratio and estimated lifetime  

NASA Astrophysics Data System (ADS)

We use the estimated lifetime of methane (CH4), the current methane concentration, and its annual growth rate to calculate the global methane emission rate. The upper and lower limits of the annual global methane emission rate, depending on loss of CH4 into the stratosphere and methane consuming bacteria, amounts to 648.0 Mt a-1 and 608.0 Mt a-1. These values are in reasonable agreement with satellite and with much more accurate in situ measurements of methane. We estimate a mean tropospheric and mass-weighted temperature related to the reaction rate and employ a mean OH-concentration to calculate a mean methane lifetime. The estimated atmospheric lifetime of methane amounts to 8.28 years and 8.84 years, respectively. In order to improve the analysis a realistic 3D-calculations should be performed.

Sonnemann, G. R.; Grygalashvyly, M.

2014-03-01

153

Evaluation of enteric methane prediction equations for dairy cows used in whole farm models  

Microsoft Academic Search

The importance of evaluating greenhouse gas (GHG) emissions from dairy cows within the whole farm setting is being realized as more important than evaluating these emissions in isolation. Current whole farm models aimed at evaluating GHG emissions make use of simple regression equations to predict enteric methane (CH4) production. The objective of the current paper is to evaluate the performance

J. L. Ellis; A. Bannink; E. Kebreab; J. Dijkstra

2010-01-01

154

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

PubMed

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

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

2014-10-01

155

Effect of some essential oils on in vitro methane emission.  

PubMed

The objectives of this study were to characterise four essential oils (EO) chemically and to evaluate their effect on ruminal fermentation and methane emission in vitro. The investigated EO were isolated from Achillea santolina, Artemisia judaica, Schinus terebinthifolius and Mentha microphylla, and supplemented at four levels (0, 25, 50 and 75 microl) to 75 ml of buffered rumen fluid plus 0.5 g of substrate. The main components of the EO were piperitone (49.1%) and camphor (34.5%) in A. judaica, 16-dimethyl 15-cyclooactdaiene (60.5%) in A. santolina, piperitone oxide (46.7%) and cis-piperitone oxide (28%) in M. microphylla, and gamma-muurolene (45.3%) and alpha-thujene (16.0%) in S. terebinthifolius. The EO from A. santolina (at 25 and 50 j1), and all levels of A. judaica increased the gas production significantly, but S. terebinthifolius (at 50 and 75 microl), A. santolina (at 75 microl) and all levels of M. microphylla decreased the gas production significantly in comparison with the control. The highest levels of A. santolina and A. judaica, and all doses from M. microphylla EO inhibited the methane production along with a significant reduction in true degradation of dry matter and organic matter, protozoa count and NH3-N concentration. It is concluded that the evaluated EO have the potential to affect ruminal fermentation efficiency and the EO from M. microphylla could be a promising methane mitigating agent. PMID:21776837

Sallam, Sobhy Mohamed Abdallah; Abdelgaleil, Samir Abdelazim Mohamed; Bueno, Ives Claudio da Silva; Nasser, Mohamed Emad Abdelwahab; Araujo, Rafael Canonenco; Abdalla, Adibe Luiz

2011-06-01

156

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

157

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

158

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

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

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

PubMed

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

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

2014-11-01

161

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

162

Estimation of the methane emission factor for the Italian Mediterranean buffalo.  

PubMed

In order to contribute to the improvement of the national greenhouse gas emission inventory, this work aimed at estimating a country-specific enteric methane (CH4) emission factor for the Italian Mediterranean buffalo. For this purpose, national agriculture statistics, and information on animal production and farming conditions were analysed, and the emission factor was estimated using the Tier 2 model of the Intergovernmental Panel on Climate Change. Country-specific CH4 emission factors for buffalo cows (630 kg body weight, BW) and other buffalo (313 kg BW) categories were estimated for the period 1990-2004. In 2004, the estimated enteric CH4 emission factor for the buffalo cows was 73 kg/head per year, whereas that for other buffalo categories it was 56 kg/head per year. Research in order to determine specific CH4 conversion rates at the predominant production system is suggested. PMID:22443738

Cóndor, R D; Valli, L; De Rosa, G; Di Francia, A; De Lauretis, R

2008-08-01

163

Atmospheric Impact of Large Methane Emissions and the Gulf Oil Spill  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

164

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

EPA Science Inventory

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

165

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

166

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...

167

Suppression of methane emission from rice paddies by ferric iron fertilization  

Microsoft Academic Search

Rice microcosms incubated in the greenhouse showed that methane emission was reduced after fertilization of the soil with ferric iron oxide–ferrihydrite. The total methane emission during the vegetation period of rice was reduced by 43% and 84%, with the addition of 15 and 30 g of ferrihydrite per kg of soil, respectively. Growth of the rice plants was reduced during

Udo Jäckel; Sylvia Schnell

2000-01-01

168

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

169

On the possible methane emissions from the East Siberian Arctic Seas  

NASA Astrophysics Data System (ADS)

Global changes in the Arctic occur in the growth of average air temperatures, rapidly melting ice on land and sea, and underwater permafrost degradation. The extensive Arctic Shelf can play an important role in methane cycling because of the huge storage of organic matter buried in permafrost, which can be involved in the modern biogeochemical cycles under warming. The dissolved methane concentrations in the East Siberian Arctic Shelf water during summers of 2003 to 2008 show a widespread oversaturation in large spatial scales [1]. The horizontal and vertical methane distributions in the observational data indicate a sedimentary source which is likely associated with thawing of the underwater permafrost and release of gas from the shallow Arctic gas hydrate. Based on the regional model the Arctic Ocean-North Atlantic, developed in ICMMG SB RAS [2], the variability of the Arctic Ocean water masses state was simulated for the period from 1948 to 2010. The model was driven by atmospheric data from the CORE-2 and NCEP/NCAR reanalysis. The analysis of the thermohaline characteristics of the East Siberia Shelf water in the model run showed the positive trend in the bottom temperature, which is in agreement with the observational data. Temperature increase of the bottom waters can lead to the thawing of the frozen bottom sediments and the release of additional amount of methane from gas hydrates. Assuming the increase in the gas permeability of the perennial frozen sediment caused by climate change, the numerical simulation of the dissolved methane transport from the bottom reservoirs in the shelf water was performed. A three-dimensional mathematical model of the dissolved gas transport by the ocean currents with the parameterization of the oxidation process was used for the quantitative evaluation of the scale of a possible methane flux from the submarine sources. According to our numerical results obtained in the period from 2002 to 2010, the total methane emission in the eastern Arctic shelf waters can be estimated from 16 to 54 kilotons per year, which is two orders lower than the estimates given in [1]. Acknowledgements: This work is supported by the IP SB RAS #109, RFBR # 11-05-01075- projects. 1. Shakhova N., Semiletov I., Salyuk A., Yusupov V., Kosmach D., Gustafsson O. Extensive methane venting to the atmosphere from sediments of the East Siberian Arctic Shelf // Science. 2010. # 327. P. 1246-1250. 2. Golubeva E.N., Platov G.A. On improving the simulation of Atlantic Water circulation in the Arctic Ocean // J.Geoph.Res. - 2007. - Vol. 112. - C04S05. - doi:10.1029/2006JC003734.

Malakhova, Valentina; Golubeva, Elena

2013-04-01

170

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

171

Tank bromeliad - a natural model ecosystem for methane cycling research  

NASA Astrophysics Data System (ADS)

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

Martinson, Guntars; Brandt, Franziska; Conrad, Ralf

2014-05-01

172

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

PubMed

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

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

2014-07-15

173

Trends and Climatology of Northern Hemisphere Non-Methane Hydrocarbon Emissions  

NASA Astrophysics Data System (ADS)

Atmospheric non-methane hydrocarbon (NMHC) data can yield valuable insight into anthropogenic and biogenic emissions into the atmosphere. For instance, recent research has pointed out a tight linkage of the atmospheric concentration of the NMHC ethane to the atmospheric growth rate of methane, and this relationship has been used to infer global changes in methane emission sources. Furthermore, NMHC play a pivotal role in photochemical production of ozone in the troposphere. We reconstructed the 1950-2010 Northern Hemisphere concentrations of the NMHC ethane, propane, i-butane, n-butane, i-pentane, and n-pentane using 1. measurements of air samples extracted from three boreholes in the firn layer at North Greenland Eemian Ice Drilling (NEEM) project site; 2. a firn air transport model that allows reconstructing atmospheric concentrations of trace gas from borehole measurements; and 3. eight years of data from ambient NMHC monitoring at five Arctic sites within the NOAA Global Monitoring Division Cooperative Air Sampling Network. Results indicate that these C2-C5 NMHC increased by ~ 40-120% after 1950, then peaked between 1965-1985, and have since dramatically decreased to near-1950 levels. Different peak times of ethane versus C3-C5 NMHC suggest that different processes and emission mitigation measures contributed to the decline in these NMHC. NMHC mole fraction trends, observed changes in the ratio of selected NMHC pairs, and NMHC/carbon monoxide ratios are used to infer post-1950 changes in fossil fuel sources and tropospheric ozone production.

Helmig, Detlev; Petrenko, Vasilli; Martinerie, Patricia; Witrant, Emmanuel; Roeckmann, Thomas; Hueber, Jacques; Sturges, William; Baker, Angela; Blunier, Thomas; Etheridge, David; Rubino, Mauro; Tans, Pieter; Zuiderweg, Adriaan; Holzinger, Rupert

2013-04-01

174

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

PubMed

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

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

2014-09-01

175

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

176

Global impacts of sulfate deposition from acid rain on methane emissions from natural wetlands.  

NASA Astrophysics Data System (ADS)

Natural wetlands form the largest methane (CH_4) source to the atmosphere. A collection of recent field and laboratory studies point to an anthropogenic control on CH_4 emissions from these systems: acid rain sulfate (SO_42-) deposition. These studies ranging from the UK, USA, Canada, Sweden and Czech Republic demonstrate that low rates of SO_42- deposition, within the range commonly experienced in acid rain impacted regions, can suppress CH_4 emissions by as much as 40% and that the response of CH_4 emissions to increasing rates of SO_42- deposition closely mirrors changes in sulfate reduction rates with SO_42- deposition. This indicates that the suppression in CH_4 flux is the result of acid rain stimulating a competitive exclusion of methanogenesis by sulfate reducing bacteria, resulting in reduced methane production. These findings were extrapolated to the global scale by combining modelled, spatially explicit data sets of CH_4 emission from wetlands across the globe with modelled S deposition. Results indicate that this interaction may be important at the global scale, suppressing CH_4 emissions from wetlands in 2030 by as much as 20--28Tg, and, in the process, offsetting predicted climate induced growth in the wetland CH_4 source.

Gauci, V.

2003-04-01

177

Open Path Tracer Measurements of Methane Emissions from Free Ranging Cattle  

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

178

Methane emission from single cropping rice paddies amended different manures  

SciTech Connect

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

Du Daodeng; Tao Zhan [Agro-Environ. Prot. Inst., Tianjin (China)

1996-12-31

179

Measurement and modelling of methane fluxes from UK peatlands  

NASA Astrophysics Data System (ADS)

Nearly 5000 chamber measurements of CH4 flux were collated from 21 sites across the UK, covering a range of soil and vegetation types, to derive a parsimonious model that explains as much of the variability as possible, with the least input requirements. Less than half of the observed variability in instantaneous fluxes could be explained by the independent variables measured. Measurement error is one reason for this, and here we analyse several of the uncertainties inherent in these measurements, including the choice of model used to calculate the flux. Other reasons include the stochastic nature of some of the transport processes and the poor correspondence between the independent variables measured and the actual variables influencing the processes underlying methane production, transport and oxidation. Alternative measurement methods are considered which may circumvent some of these problems. When temporal variation was removed, and the fluxes averaged at larger spatial scales, simple models explained up to ~75 % of the variance in CH4 fluxes. Soil carbon, peat depth, soil moisture and pH together provided the best sub-set of explanatory variables. To estimate the impact of changes in peatland water table on CH4 emissions in the UK, an emission factor of +0.4 g CH4 m-2 y-1 per cm increase in water table was derived from the data. As an alternative approach, vegetation species composition provides a long-term integrator of environmental conditions, which may correlate with methane flux. Here, we used a "weighted averaging" approach to predict methane flux from plant species composition at a range of sites in the UK, continental Europe and Canada. Species were classified into functional groups, defined by a number of qualitative traits considered relevant to methane dynamics. We compared the results based on this functional classification with those based on the original species composition data with a purely taxonomic classification.

Levy, P. E.; Gray, A.

2012-12-01

180

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

181

Methane Emissions from Woody Stems of Tropical and Temperate Wetland Trees  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

182

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

183

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

PubMed

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

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

2014-07-01

184

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

185

Methane emissions from bald cypress tree trunks in a bottomland forest  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

186

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

PubMed

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

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

2014-12-23

187

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

PubMed Central

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

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

2014-01-01

188

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

PubMed Central

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

2013-01-01

189

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

190

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

191

Surface water inundation in the boreal-Arctic: potential impacts on regional methane emissions  

NASA Astrophysics Data System (ADS)

Northern wetlands may be vulnerable to increased carbon losses from methane (CH4), a potent greenhouse gas, under current warming trends. However, the dynamic nature of open water inundation and wetting/drying patterns may constrain regional emissions, offsetting the potential magnitude of methane release. Here we conduct a satellite data driven model investigation of the combined effects of surface warming and moisture variability on high northern latitude (?45° N) wetland CH4 emissions, by considering (1) sub-grid scale changes in fractional water inundation (Fw) at 15 day, monthly and annual intervals using 25 km resolution satellite microwave retrievals, and (2) the impact of recent (2003-11) wetting/drying on northern CH4 emissions. The model simulations indicate mean summer contributions of 53 Tg CH4 yr-1 from boreal-Arctic wetlands. Approximately 10% and 16% of the emissions originate from open water and landscapes with emergent vegetation, as determined from respective 15 day Fw means or maximums, and significant increases in regional CH4 efflux were observed when incorporating satellite observed inundated land fractions into the model simulations at monthly or annual time scales. The satellite Fw record reveals widespread wetting across the Arctic continuous permafrost zone, contrasting with surface drying in boreal Canada, Alaska and western Eurasia. Arctic wetting and summer warming increased wetland emissions by 0.56 Tg CH4 yr-1 compared to the 2003-11 mean, but this was mainly offset by decreasing emissions (-0.38 Tg CH4 yr-1) in sub-Arctic areas experiencing surface drying or cooling. These findings underscore the importance of monitoring changes in surface moisture and temperature when assessing the vulnerability of boreal-Arctic wetlands to enhanced greenhouse gas emissions under a shifting climate.

Watts, Jennifer D.; Kimball, John S.; Bartsch, Annett; McDonald, Kyle C.

2014-07-01

192

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

193

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

PubMed Central

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

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

2012-01-01

194

Methane emissions from a New Mexico dairy lagoon system  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

195

Evidence of species specific vascular plant functions as regulators of methane emissions from northern peatlands  

NASA Astrophysics Data System (ADS)

Peatlands play an indisputable role in the global carbon cycle by their net accumulation of atmospheric carbon dioxide and storage of carbon in the form of peat. They are also intimately tied into the fundamental processes of the atmospheric greenhouse gas balance through their production and concomitant emission of methane. During the last decade several studies have emphasized the function of vegetation as an important regulator of methane emissions from wetland ecosystems, including northern peatlands. Vascular plants can affect methane emissions either by facilitating transportation of methane over the soil/atmosphere interface, or by supplying the microbial soil communities with readily degradable organic substrates through root activity, stimulating biogeochemical transformation rates including methanogenesis. We found evidence of both these types of vegetation-based interactions in a sub-arctic peatland ecosystem and also indications that the two different processes of vegetation induced stimulation of methane emission rates are species specific with respect to the vascular plant communities. By reducing incoming PAR through shading manipulations and comparing these to ambient light control plots we created an intra-habitat gradient of vascular plant photosynthesis at two contrasting sites, one ombrotrophic (dominated by Eriophorum vaginatum/Carex rotundata) and one minerotrophic (dominated by Eriophorum angustifolium). The position of the water table was found to be the dominating environmental factor controlling methane emission rates in both habitat types. At the ombrotrophic site the photosynthetic rate was the second most important factor, especially during peak vascular plant activity (late June- early August) when this variable could explain ca 15% of the variations in methane flux rates. Furthermore, the photosynthetic rates in the shaded plots were reduced by ca 25% and was accompanied by a significant 20% (P=0.01) reduction in methane emission rates, as compared to ambient controls. At the minerotrophic site no relationship between photosynthesis and methane emissions was found, but instead it was the actual number of vascular plant shoots that positively correlated as the second most important variable and explained ca 10% of the methane flux variations. Although shading reduced photosynthesis at the minerotrophic site by almost 50%, methane flux rates were unaffected. We conclude that at the minerotrophic site the vegetation influence methane emission rates by facilitating methane transportation between the soil and the atmosphere, while at the ombrotrophic site the relationship between the vascular plant community and methane emissions is mediated by substrate-based interactions regulated by plant physiological activity.

Oquist, M. G.

2001-05-01

196

Quantification of Fugitive Methane Emissions with Spatially Correlated Measurements Collected with Novel Plume Camera  

NASA Astrophysics Data System (ADS)

Quantification of fugitive methane emissions from unconventional natural gas (i.e. shale gas, tight sand gas, etc.) production, processing, and transport is essential for scientists, policy-makers, and the energy industry, because methane has a global warming potential of at least 21 times that of carbon dioxide over a span of 100 years [1]. Therefore, fugitive emissions reduce any environmental benefits to using natural gas instead of traditional fossil fuels [2]. Current measurement techniques involve first locating all the possible leaks and then measuring the emission of each leak. This technique is a painstaking and slow process that cannot be scaled up to the large size of the natural gas industry in which there are at least half a million natural gas wells in the United States alone [3]. An alternative method is to calculate the emission of a plume through dispersion modeling. This method is a scalable approach since all the individual leaks within a natural gas facility can be aggregated into a single plume measurement. However, plume dispersion modeling requires additional knowledge of the distance to the source, atmospheric turbulence, and local topography, and it is a mathematically intensive process. Therefore, there is a need for an instrument capable of simple, rapid, and accurate measurements of fugitive methane emissions on a per well head scale. We will present the "plume camera" instrument, which simultaneously measures methane at different spatial points or pixels. The spatial correlation between methane measurements provides spatial information of the plume, and in addition to the wind measurement collected with a sonic anemometer, the flux can be determined. Unlike the plume dispersion model, this approach does not require knowledge of the distance to the source and atmospheric conditions. Moreover, the instrument can fit inside a standard car such that emission measurements can be performed on a per well head basis. In a controlled experiment with known releases from a methane tank, a 2-pixel plume camera measured 496 ± 160 sccm from a release of 650 sccm located 21 m away, and 4,180 ± 962 sccm from a release of 3,400 sccm located 49 m away. These results in addition to results with a higher-pixel camera will be discussed. Field campaign data collected with the plume camera pixels mounted onto a vehicle and driven through the natural gas fields in the Uintah Basin (Utah, United States) will also be presented along with the limitations and advantages of the instrument. References: 1. S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.). IPCC, 2007: Climate Change 2007: The Physical Science Basis of the Fourth Assessment Report. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. 2. R.W. Howarth, R. Santoro, and A. Ingraffea. "Methane and the greenhouse-gas footprint of natural gas from shale formations." Climate Change, 106, 679 (2011). 3. U.S. Energy Information Administration. "Number of Producing Wells." . Accessed 6 January 2013.

Tsai, Tracy; Rella, Chris; Crosson, Eric

2013-04-01

197

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

PubMed

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

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

2014-07-01

198

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

199

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

200

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

201

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

202

Vascular plants as regulators of methane emissions from a subarctic mire ecosystem  

NASA Astrophysics Data System (ADS)

Vascular plant functions as controlling mechanisms of methane emissions were investigated at two contrasting habitat types at a subarctic peatland ecosystem in northern Sweden. One of the habitats was ombrotrophic (vegetation dominated by Eriophorum vaginatum and Carex rotundata), while the other was minerotrophic (vegetation dominated by Eriophorum angustifolium). Through shading manipulations we successfully reduced the gross photosynthetic rates of the vascular plant communities. At the ombrotrophic site a 25% reduction in gross photosynthesis lead to a concomitant 20% reduction in methane emission rates, indicating a strong substrate-based coupling between the vascular plant community and the methanogenic populations. At the minerotrophic site, methane emission rates were unaffected, although plant photosynthesis was reduced by almost 50%. However, the methane emission rates at the minerotrophic site were significantly correlated with the number of vascular plants. We conclude that at the minerotrophic site the vegetation influences methane emission rates by facilitating methane transportation between the soil and the atmosphere, while at the ombrotrophic site the relationship between the vascular plant community and methane emissions is mediated by substrate-based interactions regulated by plant photosynthetic activity.

Öquist, M. G.; Svensson, B. H.

2002-11-01

203

Stable atmospheric methane in the 2000s: key-role of emissions from natural wetlands  

NASA Astrophysics Data System (ADS)

Two atmospheric inversions (one fine-resolved and one process-discriminating) and a process-based model for land surface exchanges are brought together to analyse the variations of methane emissions from 1990 to 2009. A focus is put on the role of natural wetlands and on the years 2000-2006, a period of stable atmospheric concentrations. From 1990 to 2000, the top-down and bottom-up visions agree on the time-phasing of global total and wetland emission anomalies. The process-discriminating inversion indicates that wetlands dominate the time-variability of methane emissions (90% of the total variability). The contribution of tropical wetlands to the anomalies is found to be large, especially during the post-Pinatubo years (global negative anomalies with minima between -41 and -19 Tg yr-1 in 1992) and during the alternate 1997-1998 El-Niño/1998-1999 La-Niña (maximal anomalies in tropical regions between +16 and +22 Tg yr-1 for the inversions and anomalies due to tropical wetlands between +12 and +17 Tg yr-1 for the process-based model). Between 2000 and 2006, during the stagnation of methane concentrations in the atmosphere, the top-down and bottom-up approaches agree on the fact that South America is the main region contributing to anomalies in natural wetland emissions, but they disagree on the sign and magnitude of the flux trend in the Amazon basin. A negative trend (-3.9 ± 1.3 Tg yr-1) is inferred by the process-discriminating inversion whereas a positive trend (+1.3 ± 0.3 Tg yr-1) is found by the process model. Although processed-based models have their own caveats and may not take into account all processes, the positive trend found by the B-U approach is considered more likely because it is a robust feature of the process-based model, consistent with analysed precipitations and the satellite-derived extent of inundated areas. On the contrary, the surface-data based inversions lack constraints for South America. This result suggests the need for a re-interpretation of the large increase found in anthropogenic methane inventories after 2000.

Pison, I.; Ringeval, B.; Bousquet, P.; Prigent, C.; Papa, F.

2013-12-01

204

Methane emission from flooded coal seams in abandoned mines, in the light of laboratory investigations  

E-print Network

Methane emission from flooded coal seams in abandoned mines, in the light of laboratory of methane from flooded unexploited coal seams Field experience from the flooding operations of the abandoned gassy coal seams in abandoned mines. The tests included the following main stages: - Determining

Boyer, Edmond

205

The Role of Sedges in Methane Production and Emission From a Temperate Fen  

Microsoft Academic Search

Northern peatlands are the largest single natural source of atmospheric methane (CH4) and thus any changes in these fluxes could have global consequences. Positive correlations have been observed between sedge biomass and high CH4 emissions from peatlands. We examined the effect that Carex rostrata has on methane production and transport in Sallie's Fen, Barrington, NH. During the summer of 2008,

G. L. Noyce; E. R. Szarkowski; J. L. Bubier; R. K. Varner

2008-01-01

206

A new tracer experiment to estimate the methane emissions from a dairy cow shed using sulfur hexafluoride (SF6)  

Microsoft Academic Search

Methane emission from livestock and agricultural wastes contribute globally more than 30% to the anthropogenic atmospheric methane source. Estimates of this number have been derived from respiration chamber experiments. We determined methane emission rates from a tracer experiment in a modern cow shed hosting 43 dairy cows in their accustomed environment. During a 24-hour period the concentrations of CH4, CO2,

Thomas Marik; Ingeborg Levin

1996-01-01

207

Temporal and spatial variability of methane emissions in a northern temperate marsh  

NASA Astrophysics Data System (ADS)

Although methane (CH4) fluxes from northern wetlands in Asia have been described in previous research at different temporal and spatial scales, integrated studies at the ecosystem scale were scarce. In this study, CH4 fluxes were measured using eddy covariance (EC) technique and the chamber method in a cool temperate marsh in northeast China during the growing season (May-September) of 2011. CH4 emissions were highly variable, both temporally and spatially during the measurement period. According to the EC observation data, CH4 fluxes showed a significant diurnal cycle during the mid-growing season with nighttime average flux about 67% of the average daytime values. Daily cumulative CH4 fluxes varied from 54 to 250 mg CH4 m-2 d-1 with an average flux of 136.2 mg CH4 m-2 d-1. The observations of chamber method showed that CH4 emissions differed markedly among the three main plant communities. Average flux at the Carex lasiocarpa site was about 4 times and 13.5 times of that at the Glyceria spiculosa site and Deyeuxia angustifolia site, respectively. The spatial variability of CH4 flux was mainly controlled by the varying water table level as well as the spatial distribution of different vascular plants, while the seasonal dynamic of CH4 emission could be best explained by the change of surface soil temperature and air pressure. A comparison was made between EC measurements and the upscaled chamber based model. The results from the model overestimated CH4 emission by 28% compared to the EC data. Considering the large variability of methane emission, it is necessary to conduct continuous observations on CH4 emission from northern wetlands at different temporal and spatial scales to comprehend the variability and also to predict responses to climate change.

Sun, Li; Song, Changchun; Miao, Yuqing; Qiao, Tianhua; Gong, Chao

2013-12-01

208

Modelling an experimental methane fuel processor  

NASA Astrophysics Data System (ADS)

Steady-state models are developed to describe an experimental methane fuel processor that is intended to provide hydrogen for a fuel cell system for power generation (2-3 kW). First-principle reactor models are constructed to describe a series of reactions, i.e., steam and autothermal reforming (SR/ATR), high- and low-temperature water-gas shift (HTS/LTS) reactions and preferential oxidation (PROX) reactions, at different sectors of the reactor system for methane reforming as well as gas cleaning. The pre-exponential factors of the rate constants are adjusted to fit the experimental data and the resultant reactor model provides a reasonably good description of steady-state behaviour. Next, sensitivity analyses are performed to locate the optimum operating point of the fuel processor. The objective function of the optimization is fuel processor efficiency. The dominating optimization variables include: the ratios of water and oxygen to the hydrocarbon feed to the autothermal reforming reactor and the inlet temperature of the reactor. The results indicate that further improvement in fuel processor efficiency can be made with a reliable process model.

Lin, Shi-Tin; Chen, Yih-Hang; Yu, Cheng-Ching; Liu, Yen-Chun; Lee, Chiou-Hwang

209

Enteric methane emissions from dairy cows fed different proportions of highly digestible grass silage  

Microsoft Academic Search

Enteric methane (CH4) emissions were measured from six lactating dairy cows using the sulfur hexafluoride tracer technique. Three diets with different proportions of highly digestible grass silage\\/concentrates were fed: 500\\/500, 700\\/300, or 900\\/100 g kg dry matter (DM). The average daily CH4 emissions were 282, 300, and 321 g animal, respectively and the methane conversion factor (Ym) from gross energy

M. Patel; E. Wredle; G. Börjesson; R. Danielsson; A. D. Iwaasa; E. Spörndly; J. Bertilsson

2011-01-01

210

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

PubMed Central

Methane is a substantial contributor to climate change. It also contributes to maintaining the background levels of tropospheric ozone. Among a variety of CH4 sources, current estimates suggest that CH4 emissions from oil and gas processes account for approximately 20% of worldwide anthropogenic emissions. Here, we report on observational evidence of CH4 emissions from offshore oil and gas platforms in Southeast Asia, detected by a highly time-resolved spectroscopic monitoring technique deployed onboard cargo ships of opportunity. We often encountered CH4 plumes originating from operational flaring/venting and fugitive emissions off the coast of the Malay Peninsula and Borneo. Using night-light imagery from satellites, we discovered more offshore platforms in this region than are accounted for in the emission inventory. Our results demonstrate that current knowledge regarding CH4 emissions from offshore platforms in Southeast Asia has considerable uncertainty and therefore, emission inventories used for modeling and assessment need to be re-examined. PMID:25266041

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

2014-01-01

211

Grape marc reduces methane emissions when fed to dairy cows.  

PubMed

Grape marc (the skins, seeds, stalk, and stems remaining after grapes have been pressed to make wine) is currently a by-product used as a feed supplement by the dairy and beef industries. Grape marc contains condensed tannins and has high concentrations of crude fat; both these substances can reduce enteric methane (CH4) production when fed to ruminants. This experiment examined the effects of dietary supplementation with either dried, pelleted grape marc or ensiled grape marc on yield and composition of milk, enteric CH4 emissions, and ruminal microbiota in dairy cows. Thirty-two Holstein dairy cows in late lactation were offered 1 of 3 diets: a control (CON) diet; a diet containing dried, pelleted grape marc (DGM); and a diet containing ensiled grape marc (EGM). The diet offered to cows in the CON group contained 14.0kg of alfalfa hay dry matter (DM)/d and 4.3kg of concentrate mix DM/d. Diets offered to cows in the DGM and EGM groups contained 9.0kg of alfalfa hay DM/d, 4.3kg of concentrate mix DM/d, and 5.0kg of dried or ensiled grape marc DM/d, respectively. These diets were offered individually to cows for 18d. Individual cow feed intake and milk yield were measured daily and milk composition measured on 4d/wk. Individual cow CH4 emissions were measured by the SF6 tracer technique on 2d at the end of the experiment. Ruminal bacterial, archaeal, fungal, and protozoan communities were quantified on the last day of the experiment. Cows offered the CON, DGM, and EGM diets, ate 95, 98, and 96%, respectively, of the DM offered. The mean milk yield of cows fed the EGM diet was 12.8kg/cow per day and was less than that of cows fed either the CON diet (14.6kg/cow per day) or the DGM diet (15.4kg/cow per day). Feeding DGM and EGM diets was associated with decreased milk fat yields, lower concentrations of saturated fatty acids, and enhanced concentrations of mono- and polyunsaturated fatty acids, in particular cis-9,trans-11 linoleic acid. The mean CH4 emissions were 470, 375, and 389g of CH4/cow per day for cows fed the CON, DGM, and EGM diets, respectively. Methane yields were 26.1, 20.2, and 21.5g of CH4/kg of DMI for cows fed the CON, DGM, and EGM diets, respectively. The ruminal bacterial and archaeal communities were altered by dietary supplementation with grape marc, but ruminal fungal and protozoan communities were not. Decreases of approximately 20% in CH4 emissions and CH4 yield indicate that feeding DGM and EGM could play a role in CH4 abatement. PMID:24952778

Moate, P J; Williams, S R O; Torok, V A; Hannah, M C; Ribaux, B E; Tavendale, M H; Eckard, R J; Jacobs, J L; Auldist, M J; Wales, W J

2014-08-01

212

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

213

Methane emission from the mud volcanoes of Sicily (Italy)  

Microsoft Academic Search

Mud volcanoes represent the largest expression of natural methane release into the atmosphere; however, the gas flux has never been investigated in detail. Methane output from vents and diffuse soil degassing is herewith reported for the first time. Measurements were carried out at 5 mud volcano fields around Sicily (Italy). Each mud volcano is characterized by tens of vents and

G. Etiope; A. Caracausi; R. Favara; F. Italiano; C. Baciu

2002-01-01

214

Methane emissions from terrestrial plants under aerobic conditions  

Microsoft Academic Search

Methane is an important greenhouse gas and its atmospheric concentration has almost tripled since pre-industrial times. It plays a central role in atmospheric oxidation chemistry and affects stratospheric ozone and water vapour levels. Most of the methane from natural sources in Earth's atmosphere is thought to originate from biological processes in anoxic environments. Here we demonstrate using stable carbon isotopes

Frank Keppler; John T. G. Hamilton; Marc Braß; Thomas Röckmann

2006-01-01

215

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

216

Methane emission from Russian frozen wetlands under conditions of climate change  

NASA Astrophysics Data System (ADS)

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

Reneva, S.

2009-04-01

217

Laboratory measurements and methane photochemistry modeling  

NASA Technical Reports Server (NTRS)

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

Romani, P. N.

1990-01-01

218

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

219

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

220

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

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

221

Significant Methane Emissions from Abandoned Oil and Gas wells in Northwest Pennsylvania  

NASA Astrophysics Data System (ADS)

Abandoned (no longer operated), Orphaned (abandoned and responsible party unavailable), and/or Lost (location unknown, cannot be confirmed, or not on record) (AOL) wells provide a potential pathway for subsurface migration, and emissions to the atmosphere, of methane and other volatile hydrocarbons. However, little is known about methane fluxes from AOL wells. Of the 12,000 abandoned and orphaned oil and gas wells on the Pennsylvania Department of Environmental Protection's (PA DEP) list, 36% are in McKean County. McKean County is home to the Bradford Oil Field, the world's first large oil field, which in 1881 produced 83% of America's output. A large fraction of the oil and gas wells in McKean County are AOL and some estimates of the number of AOL wells exceed the number of wells listed by the PA DEP by factors of 20 or more. To characterize AOL wells' potential as a significant methane source, we made first-of-a-kind measurements of methane fluxes from 8 abandoned wells in McKean County using static flux chambers. These wells are on a 40-acre lot, which includes various land cover types. Four of the eight measured wells are in forested areas, while three are in grassland, and one is in wetland areas. Two of the eight wells, one in a forested area and one in the grassland area, are plugged. Fluxes of methane, ethane, propane, and n-butane were measured using flame ionization gas chromatography. To gain insight into the source of methane (biogenic vs. thermogenic), carbon and hydrogen isotopes of methane were analyzed and the ratio of methane to heavier hydrocarbons were computed. In addition, a LI-7700 open path methane analyzer was used to provide on-line methane concentration measurement in the vicinity of AOL wells and in flux chambers. We found methane fluxes from the measured AOL wells to be significantly higher than fluxes observed in similar natural environments. Methane emissions from the two plugged wells were smaller than those from unplugged wells but non-negligible. The atmospheric methane concentration in the vicinity of some wells was elevated up to fifteen times higher than the background concentration, indicating that methane concentrations near the land surface can be used to detect emissions from AOL wells. Given the large number of AOL wells in Pennsylvania and across the country, methane emissions from AOL wells may be a significant anthropogenic source of methane and other hydrocarbons to the atmosphere. An improved understanding of the role of AOL wells as methane emission sources can aid in bridging the current gap in global and regional methane budgets, while plugging wells could provide a future opportunity for emissions reduction. Furthermore, with the growth of unconventional oil and gas production in Pennsylvania and across the globe, characterization of AOL wells as a methane source is useful for determining impacts of past, current, and future oil and gas production.

Kang, M.; Zhang, X.; Reid, M. C.; Kanno, C.; Celia, M. A.; Mauzerall, D. L.; Sun, K.; Miller, D. J.; Zondlo, M. A.; Chen, Y.; Onstott, T. C.

2013-12-01

222

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

223

Latitudinal variation of the effect of aviation NOx emissions on atmospheric ozone and methane and related climate metrics  

NASA Astrophysics Data System (ADS)

We evaluate the response to regional and latitudinal changes in aircraft NOx emissions using several climate metrics (radiative forcing (RF), Global Warming Potential (GWP), Global Temperature change Potential (GTP)). Global chemistry transport model integrations were performed with sustained perturbations in regional aircraft and aircraft-like NOx emissions. The RF due to the resulting ozone and methane changes is then calculated. We investigate the impact of emission changes for specific geographical regions (approximating to USA, Europe, India and China) and cruise altitude emission changes in discrete latitude bands covering both hemispheres. We find that lower latitude emission changes (per Tg N) cause ozone and methane RFs that are about a factor of 6 larger than those from higher latitude emission changes. The net RF is positive for all experiments. The meridional extent of the RF is larger for low latitude emissions. GWPs for all emission changes are positive, with tropical emissions having the largest values; the sign of the GTP depends on the choice of time horizon.

Köhler, M. O.; Rädel, G.; Shine, K. P.; Rogers, H. L.; Pyle, J. A.

2013-01-01

224

Potential contributions of process modeling to understanding and constraining the global methane budget  

NASA Astrophysics Data System (ADS)

The global methane budget is fairly well-constrained in aggregate, but the partitioning of global emissions into the various natural and anthropogenic sources is not. Direct measurements of emissions are essential for quantifying the various terms, but alone are not up to the task as some important source terms are widely distributed across the planet and often remote, and emissions can be highly variable in space and time. The various components of global methane emissions can also be estimated by inverse modeling, which can be constrained by the network of atmospheric concentration and isotopic measurements, but has coarse spatial resolution, and is not so useful for prognostic modeling. Process-based modeling can also help to constrain and evaluate the global methane budget. Using the DNDC model as an example, we review both strengths (e.g., spatial and temporal extrapolation), weaknesses (e.g., incomplete representations; generalization), and challenges (e.g., adequate ancillary data) of process models as a scientific tool for understanding the global methane budget.

Frolking, S.; Li, C.

2008-12-01

225

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

226

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

227

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

NASA Astrophysics Data System (ADS)

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

Sung, K.; Park, S.

2007-12-01

228

Methane emissions from wetlands on the Qinghai-Tibet Plateau  

Microsoft Academic Search

The areal extent of cold freshwater wetlands on the Qinghai-Tibet Plateau (QTP) is estimated at 0.133 × 106 km2, suggesting a significant methane potential. Methane fluxes from wet alpine meadows, peatlands,Hippuris vulgaris mires and secondary marshes were 43.18, 12.96, ?0.28 and 45.90 mg · m?2 · d?1, respectively based on the transect flux studies at the Huashixia Permafrost Station (HPS)

JIN Huijunl; Jie Wu; CHENG Guodongl; Tomoko Nakano; Guangyou Sun

1999-01-01

229

Global methane emissions from minor anthropogenic sources and biofuel combustion in residential stoves  

Microsoft Academic Search

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 emissions are estimated for a wide variety of individual minor emissions sources on a country-specific basis. Emissions from biomass

Stephen D. Piccot; Lee Beck; Sridhar Srinivasan; Sharon L. Kersteter

1996-01-01

230

Global methane emissions from minor anthropogenic sources and biofuel combustion in residential stoves  

Microsoft Academic Search

Most global methane (CH4) budgets have failed to include emissions from a diverse group of minor anttu'opogenic sources. Individually, these minor sources emit small quantities of CH4, but collectively, their contributions to the budget may be significant. In this paper, CH 4 emissions are estimated for a wide variety of individual minor emissions sources on a country-specific basis. Emissions from

Stephen D. Piccot; Lee Beck; Sridhar Srinivasan; Sharon L. Kersteter

1996-01-01

231

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

PubMed Central

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.

2013-01-01

232

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

2013-10-29

233

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

SciTech Connect

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

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

1997-10-01

234

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

235

Isolation of Succinivibrionaceae implicated in low methane emissions from Tammar wallabies.  

PubMed

The Tammar wallaby (Macropus eugenii) harbors unique gut bacteria and produces only one-fifth the amount of methane produced by ruminants per unit of digestible energy intake. We have isolated a dominant bacterial species (WG-1) from the wallaby microbiota affiliated with the family Succinivibrionaceae and implicated in lower methane emissions from starch-containing diets. This was achieved by using a partial reconstruction of the bacterium's metabolism from binned metagenomic data (nitrogen and carbohydrate utilization pathways and antibiotic resistance) to devise cultivation-based strategies that produced axenic WG-1 cultures. Pure-culture studies confirm that the bacterium is capnophilic and produces succinate, further explaining a microbiological basis for lower methane emissions from macropodids. This knowledge also provides new strategic targets for redirecting fermentation and reducing methane production in livestock. PMID:21719642

Pope, P B; Smith, W; Denman, S E; Tringe, S G; Barry, K; Hugenholtz, P; McSweeney, C S; McHardy, A C; Morrison, M

2011-07-29

236

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

EPA Science Inventory

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

237

High methane emissions from a midlatitude reservoir draining an agricultural watershed  

EPA Science Inventory

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

238

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

E-print Network

Earth'sFuture Remote sensing of fugitive methane emissions from oil and gas production in North and tight oil reservoirs to exploit formerly inaccessible or unprofitable energy resources in rock and oil provide an opportunity to achieve energy self-sufficiency and to reduce greenhouse gas emissions

Dickerson, Russell R.

239

NITROUS OXIDE AND METHANE EMISSIONS UNDER VARYING TILLAGE AND FERTIIZER MANAGEMENT  

Technology Transfer Automated Retrieval System (TEKTRAN)

Reduced tillage is being examined as a means of enhancing soil carbon and mitigating greenhouse gas (GHG) emissions. There is relatively little information regarding tillage effects on emissions of nitrous oxide (N2O) and methane (CH4), which have higher global warming potentials than carbon dioxide...

240

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

EPA Science Inventory

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

241

Alcohol, Volatile Fatty Acid, Phenol, and Methane Emissions from Dairy Cows and Fresh Manure  

Microsoft Academic Search

Th ere are approximately 2.5 million dairy cows in California. Emission inventories list dairy cows and their manure as the major source of regional air pollutants, but data on their actual emissions remain sparse, particularly for smog-forming volatile organic compounds (VOCs) and greenhouse gases (GHGs). We report measurements of alcohols, volatile fatty acids, phenols, and methane (CH 4) emitted from

Huawei Sun; Steven L. Trabue; Kenwood Scoggin; Wendi A. Jackson; Yuee Pan; Yongjing Zhao; Irina L. Malkina; Jacek A. Koziel; Frank M. Mitloehner

2008-01-01

242

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...

243

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...

244

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...

245

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...

246

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...

247

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...

248

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...

249

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...

250

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...

251

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...

252

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...

253

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...

254

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...

255

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...

256

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...

257

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...

258

Quantifying methane and nitrous oxide emissions from the UK using a dense monitoring network  

NASA Astrophysics Data System (ADS)

The UK is one of several countries around the world that has enacted legislation to reduce its greenhouse gas emissions. Monitoring of emissions has been done through a detailed sectoral level bottom-up inventory (UK National Atmospheric Emissions Inventory, NAEI) from which national totals are submitted yearly to the United Framework Convention on Climate Change. In parallel, the UK government has funded four atmospheric monitoring stations to infer emissions through top-down methods that assimilate atmospheric observations. In this study, we present top-down emissions of methane (CH4) and nitrous oxide (N2O) for the UK and Ireland over the period August 2012 to August 2014. We used a hierarchical Bayesian inverse framework to infer fluxes as well as a set of covariance parameters that describe uncertainties in the system. We inferred average UK emissions of 2.08 (1.72-2.47) Tg yr-1 CH4 and 0.105 (0.087-0.127) Tg yr-1 N2O and found our derived estimates to be generally lower than the inventory. We used sectoral distributions from the NAEI to determine whether these discrepancies can be attributed to specific source sectors. Because of the distinct distributions of the two dominant CH4 emissions sectors in the UK, agriculture and waste, we found that the inventory may be overestimated in agricultural CH4 emissions. We also found that N2O fertilizer emissions from the NAEI may be overestimated and we derived a significant seasonal cycle in emissions. This seasonality is likely due to seasonality in fertilizer application and in environmental drivers such as temperature and rainfall, which are not reflected in the annual resolution inventory. Through the hierarchical Bayesian inverse framework, we quantified uncertainty covariance parameters and emphasized their importance for high-resolution emissions estimation. We inferred average model errors of approximately 20 and 0.4 ppb and correlation timescales of 1.0 (0.72-1.43) and 2.6 (1.9-3.9) days for CH4 and N2O, respectively. These errors are a combination of transport model errors as well as errors due to unresolved emissions processes in the inventory. We found the largest CH4 errors at the Tacolneston station in eastern England, which is possibly to do with sporadic emissions from landfills and offshore gas in the North Sea.

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

2015-01-01

259

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. PMID:22344639

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

2012-01-01

260

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

261

Fluctuations in methane emission in response to feeding pattern in lactating dairy cows  

Microsoft Academic Search

\\u000a Methane from enteric fermentation of organic matter by ruminants is considered a key contributor to climate change. This study\\u000a examined the effect of feeding a total mixed ration at different intervals, either once, twice or four times daily, on pattern\\u000a of methane emission by lactating dairy cows and developed a response function based on exponentials to describe the observed\\u000a patterns

L. A. Crompton; J. A. N. Mills; C. K. Reynolds

262

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

263

EVALUATION OF METHANE EMISSION AND POTENTIAL MITIGATION FROM FLOODED RICE FIELD  

Microsoft Academic Search

Reduction of methane (CH4) emission from rice field is essential to prevent ecological destruction due to global climate change as an impact of global warming. It was predicted that in the year 2100, the average temperature of the earth surface would increase approximately 2?3oC. Methane mitigation studies were carried out in Jakenan, Central Java with the objectives of assessing various

Prihasto Setyanto; Rosenani Abubakar

264

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

NASA Astrophysics Data System (ADS)

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

Archer, D.

2014-06-01

265

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

NASA Technical Reports Server (NTRS)

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

Matthews, Elaine; John, Jasmin; Fung, Inez

1994-01-01

266

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

267

Methane on the Move: natural greenhouse gas emissions over geological time  

NASA Astrophysics Data System (ADS)

The mass of organic carbon in sedimentary basins amounts to a staggering 1016 tons, dwarfing the mass contained in coal, oil, gas and all living systems by ten thousand-fold. The changing fate of this giant mass during subsidence and uplift, via chemical, physical and biological processes, is known to ultimately control fossil energy resource occurrence worldwide. But what has been overlooked and/or ignored until now is its enormous capacity for driving global climate: only a tiny degree of leakage, particularly when focussed through the clathrate cycle, can result in high greenhouse gas emissions. Understanding the workings of sedimentary basins in time and space is fundamental to gaining insights into Earth's climate. Here we shall present an integrated framework based on petroleum system modelling that will ultimately quantify methane migration and emission from one hundred of the world's most prolific petroliferous sedimentary basins. Timing of hydrocarbon generation from globally occurring prolific Jurassic and Cretaceous source rocks is regarded to be the key factor in quantifying gas release. Combined thermogenic and biogenic methane fluxes are the base for prediction of gas hydrate formation through time and space, by application of kinetics developed in the laboratory to geological scenarios. Results are calibrated in basin scale by emission structure evaluation (mud volcanoes, carbonate mounds, pockmarks) and on a global scale by proxy data from sedimentary archives and local atmospheric data. Identifying potential climate feedback processes over a geological time line that spans the Cenozoic requires a comprehensive understanding of source-sink relationships by coupling these feedstock fluxes with gas hydrate stability considerations, deep biosphere activity, ocean and atmosphere modelling

Horsfield, B.; di Primio, R.; Kroeger, K. F.; Schicks, J. M.

2008-12-01

268

Abiotic emissions of methane and reduced organic compounds from organic matter  

NASA Astrophysics Data System (ADS)

Recent laboratory studies show that the important greenhouse gas methane, but also other reduced atmospheric trace gases, can be emitted by abiotic processes from organic matter, such as plants, pure organic compounds and soils. It is very difficult to distinguish abiotic from biotic emissions in field studies, but in laboratory experiments this is easier because it is possible to carefully prepare/sterilize samples, or to control external parameters. For example, the abiotic emissions always show a strong increase with temperature when temperatures are increased to 70C or higher, well above the temperature optimum for bacterial activity. UV radiation has also been clearly shown to lead to emission of methane and other reduced gases from organic matter. Interesting information on the production mechanism has been obtained from isotope studies, both at natural abundance and with isotope labeling. For example, the methoxyl groups of pectin were clearly identified to produce methane. However, analysis of the isotopic composition of methane from natural samples clearly indicates that there must be other molecular mechanisms that lead to methane production. Abiotic methane generation could be a ubiquitous process that occurs naturally at low rates from many different sources.

Roeckmann, T.; Keppler, F.; Vigano, I.; Derendorp, L.; Holzinger, R.

2012-12-01

269

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

270

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

PubMed

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

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

2014-07-01

271

A model for methane production in sewers.  

PubMed

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

Chaosakul, Thitirat; Koottatep, Thammarat; Polprasert, Chongrak

2014-09-19

272

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

273

Methane and nitrous oxide (N{sub 2}O) emission characteristics from automobiles  

SciTech Connect

Exhaust gases discharged from automobiles are noticed as one of the reasons for recent increase in atmospheric methane and nitrous oxide concentration, which have been considered as greenhouse gases. In order to make an accurate estimation of methane and nitrous oxide discharged from automobiles, measurement methods were experimentally developed and emissions were measured for different kinds of automobiles under various driving conditions. Then, the authors have tried to estimate the annual global emissions from automobiles using these measurement results and statistical data such as the number of automobiles, the total annual mileage, and the total annual fuel consumption, etc. The emissions from passenger vehicles which have been estimated from the global number of automobiles were 477.263 t/year for methane and 313.472 t/year for nitrous oxide. These numbers are higher than what had been estimated.

Koike, Noriyuki; Odaka, Matsuo

1996-09-01

274

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

SciTech Connect

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

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

1996-12-31

275

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

276

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

PubMed

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

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

2014-01-01

277

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

278

Methane Emissions from Dairy Cows Measured Using the Sulfur Hexafluoride (SF6) Tracer and Chamber Techniques  

Microsoft Academic Search

Our study compared methane (CH4) emissions from lactating dairy cows measured using the sulfur hexa- fluoride (SF6) tracer and open-circuit respiration cham- ber techniques. The study was conducted using 16 lac- tating Holstein-Friesian cows. In each chamber, the cowwasfittedwiththeSF6tracerapparatustomeasure total CH4 emissions, including emissions from the rec- tum. Fresh ryegrass pasture was harvested daily and fed ad libitum to each

C. Grainger; T. Clarke; S. M. McGinn; M. J. Auldist; K. A. Beauchemin; M. C. Hannah; G. C. Waghorn; H. Clark; R. J. Eckard

2007-01-01

279

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

Microsoft Academic Search

Mitigation of enteric methane (CH4) emission in ruminants has become an important area of research because accumulation of CH4 is linked to global warming. Nutritional and microbial opportunities to reduce CH4 emissions have been extensively researched, but little is known about using natural variation to breed animals with lower CH4 yield. Measuring CH4 emission rates directly from animals is difficult

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

2011-01-01

280

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

Microsoft Academic Search

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

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

1986-01-01

281

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

NASA Astrophysics Data System (ADS)

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 isotopic composition. Point sources and hot spots had a strong association with thermokarst (thaw) erosion because permafrost degradation along lake margins releases ancient organic matter into anaerobic lake bottoms, fueling methanogenesis. With increasing ebullition rate, we observed increasing CH4 concentration of greater radiocarbon age, depletion of 13CCH4, and decreasing bubble N2 content. Microbial oxidation of methane was observed in bubbles that became trapped below and later within winter lake ice; however, oxidation appeared insignificant in bubbles sampled immediately after release from sediments. Methanogenic pathways differed among the bubble sources: CO2 reduction supported point source and hot spot ebullition to a large degree, while acetate fermentation appeared to contribute to background bubbling. To provide annual whole-lake and regional CH4 isofluxes for the Siberian lakes, we combined maps of bubble source distributions with long-term, continuous flux measurements and isotopic composition. In contrast to typical values used in inverse models of atmospheric CH4 for northern wetland sources (?13CCH4 = -58‰, 14C age modern), which have not included northern lake ebullition as a source, we show that this large, new source of high-latitude CH4 from lakes is isotopically distinct (?13CCH4 = -70‰, 14C age 16,500 years, for North Siberian lakes).

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

2008-09-01

282

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

283

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

NASA Astrophysics Data System (ADS)

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

Bourakkadi, Zakia; Payan, Sébastien; Bureau, Jérôme

2014-05-01

284

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

NSDL National Science Digital Library

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

1999-01-01

285

Methane emission from dairy cows and wether sheep fed subtropical grass?dominant pastures in midsummer in New Zealand  

Microsoft Academic Search

Methane emission was measured from 10 dairy cows and 12 wether sheep grazing kikuyu grass? (Pennisetum clandestinum) dominant pastures at Waimate North, Northland, in February 1997 and March 1999, and from 10 dairy cows grazing summer grass? (Digitaria sanguinalis) dominant pasture at Edgecumbe, Bay of Plenty, in March 2000. Methane emission was measured from each animal for 5 consecutive days

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

2002-01-01

286

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

EPA Science Inventory

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

287

NATURAL EMISSIONS OF NON-METHANE VOLATILE ORGANIC COMPOUNDS, CARBON MONOXIDE, AND OXIDES OF NITROGEN FROM NORTH AMERICA. (R825259)  

EPA Science Inventory

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

288

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

289

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

290

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

291

Mapping of North American methane emissions with high spatial resolution by inversion of SCIAMACHY satellite data  

NASA Astrophysics Data System (ADS)

estimate methane emissions from North America with high spatial resolution by inversion of Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) satellite observations using the Goddard Earth Observing System Chemistry (GEOS-Chem) chemical transport model and its adjoint. The inversion focuses on summer 2004 when data from the Intercontinental Chemical Transport Experiment-North America (INTEX-A) aircraft campaign over the eastern U.S. are available to validate the SCIAMACHY retrievals and evaluate the inversion. From the INTEX-A data we identify and correct a water vapor-dependent bias in the SCIAMACHY data. We conduct an initial inversion of emissions on the horizontal grid of GEOS-Chem (1/2° × 2/3°) to identify correction tendencies relative to the Emission Database for Global Atmospheric Research (EDGAR) v4.2 emission inventory used as a priori. We then cluster these grid cells with a hierarchical algorithm to extract the maximum information from the SCIAMACHY observations. A 1000 cluster ensemble can be adequately constrained, providing ~100 km resolution across North America. Analysis of results indicates that the Hudson Bay Lowland wetlands source is 2.1 Tg a-1, lower than the a priori but consistent with other recent estimates. Anthropogenic U.S. emissions are 30.1 ± 1.3 Tg a-1, compared to 25.8 Tg a-1 and 28.3 Tg a-1 in the EDGAR v4.2 and Environmental Protection Agency (EPA) inventories, respectively. We find that U.S. livestock emissions are 40% greater than in these two inventories. No such discrepancy is apparent for overall U.S. oil and gas emissions, although this may reflect some compensation between overestimate of emissions from storage/distribution and underestimate from production. We find that U.S. livestock emissions are 70% greater than the oil and gas emissions, in contrast to the EDGAR v4.2 and EPA inventories where these two sources are of comparable magnitude.

Wecht, Kevin J.; Jacob, Daniel J.; Frankenberg, Christian; Jiang, Zhe; Blake, Donald R.

2014-06-01

292

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

293

Species-specific Effects of Vascular Plants on Carbon Turnover and Methane Emissions from Wetlands  

Microsoft Academic Search

Species composition affects the carbon turnover and the formation and emission of the greenhouse gas methane (CH4) in wetlands. Here we investigate the individual effects of vascular plant species on the carbon cycling in a wetland ecosystem. We used a novel combination of laboratory methods and controlled environment facilities and studied three different vascular plant species (Eriophorum vaginatum, Carex rostrata

Lena Ström; Mikhail Mastepanov; Torben R. Christensen

2005-01-01

294

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...

295

Effect of Dietary Forage to Concentrate Ratio on Lactation Performance and Methane Emission from Dairy Cows  

Technology Transfer Automated Retrieval System (TEKTRAN)

Our objective was to determine the effect of feeding diets with different forage to concentrate ratios (F:C) on performance and methane (CH4) emission from lactating dairy cows. Eight multiparous Holstein cows (means ± standard deviation: 620 ± 38 kg of body weight (BW); 41 ± 34 days in milk (DIM)) ...

296

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...

297

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

298

Measuring methane emission rates of a dairy cow herd by two micrometeorological techniques  

Microsoft Academic Search

Two well-known micrometeorological techniques were used to measure methane emission rates from a herd of dairy cows freely grazing within a fenced paddock. The integrated horizontal flux technique (IHF) was preferable to the flux-gradient technique (FG) because it does not rely on similarity assumptions, and because it had the smaller measurement error. Both techniques were comparable, within estimated errors, with

Johannes Laubach; Francis M. Kelliher

2004-01-01

299

Tillage and Fertilizer Effects on Soil Methane and Nitrous Oxide Emissions  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

300

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...

301

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

302

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

303

Assessment of the Sulfur Hexafluoride (SF) Tracer Technique for Measuring Enteric Methane Emissions from Cattle  

Microsoft Academic Search

A commonly used method of measuring enteric methane (CH4) emissions from ruminants is the SF6 tracer technique that measures respired and eructated CH4. However, within the animal, a small proportion of CH4 is produced post-ruminally and some of this may escape through the rectum. The comparison of emissions using a chamber technique that measures all enteric CH4 losses, and the

S. M. McGinn; K. A. Beauchemin; A. D. Iwaasa; T. A. McAllister

2006-01-01

304

Plant species from mesotrophic wetlands cause relatively high methane emissions from peat soil  

Microsoft Academic Search

Plants can influence methane emissions from wetland ecosystems by altering its production, consumption and transport in the\\u000a soil. The aim of this study was to investigate how eight vascular plant species from mesotrophic to eutrophic wetlands vary\\u000a in their influence on CH4 emissions from peat cores, under low and high N supply. Additionally, we measured the production of low-molecular-weight\\u000a organic

Albert Koelbener; Lena Ström; Peter J. Edwards; Harry Olde Venterink

2010-01-01

305

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

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

306

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

307

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

SciTech Connect

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

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

1997-12-31

308

Positive and negative feedbacks to climate change associated with methane emissions from arctic permafrost systems (Invited)  

NASA Astrophysics Data System (ADS)

Arctic permafrost contains 950 billion tons of organic carbon (C) in the surface tens of meters, an amount comparable to the current atmospheric CO2 burden of 750 billion tons. This C pool, which accumulated in permafrost over tens of thousands of years, is a threat to global climate because of its vulnerability to rapid microbial decomposition upon thaw, resulting in the release of greenhouse gases CO2 and CH4 to the atmosphere. Greenhouse gas release from thawing permafrost constitutes one of the most important positive feedbacks of terrestrial ecosystems to climate warming in a warmer world. Based on patterns of permafrost degradation during the present interglacial period, estimates of the amount of C remaining in permafrost today, long term field measurements of CH4 and CO2 flux, laboratory incubation experiments, and mass balance calculations of the efficiency of CH4 production from thawed permafrost, we predict that at least 50 billion tons of CH4 (equivalent to 10 times the current atmospheric methane burden) will escape from thermokarst (thaw) lakes in Siberia’s Yedoma Ice Complex as it warms and thaws. Additional CH4 will be released from the remainder of arctic lakes. Under current projections of arctic warming of 7-8 deg C by 2100, widespread permafrost thaw will release 0.1-0.2 billion tons of CH4 yr-1 by 2100, an order of magnitude more than its current source strength, adding another 20-40% of all human and natural sources of CH4 to the atmosphere. Permafrost thaw may lead to an additional source of methane if expanding thaw bulbs beneath lakes and rivers intersect faults and unconsolidated sediments leading to the escape of CH4 from geological sources, such as those recently observed on the North Slope of Alaska with a flux of 60-100 kg CH4 m-2 d-1. Thermokarst lake dynamics play a pivotal role in permafrost degradation and aggradation in the Arctic such that the landscape resembles a palimpsest of lakes and drained lake basins. Analysis of remote sensing time series of thermokarst lakes on the Northern Seward Peninsula in Alaska revealed that while lakes are rapidly expanding, an unprecedented number of lakes drained during the past 55 years, suggesting that degradation of permafrost may be accelerating in some regions. Drained basins fill in with new terrestrial vegetation, often becoming wetlands. Although these are a source of methane to the atmosphere when their surface is unfrozen in summer, their total annual emissions are often lower than lakes because of refreezing of the lake thaw bulb. Plant productivity in basins, together with the buildup of peat, serve as a sink of atmospheric carbon and a negative feedback to permafrost thaw. Results presented here aim to improve understanding of microbial and geologic methane emission dynamics related to permafrost degradation in various regions of the Arctic in order to better constrain current and future atmospheric methane budgets and global climate models.

Walter Anthony, K. M.; Grosse, G.; Jones, B. M.

2009-12-01

309

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)] [Univ. of Wales, Bangor (United Kingdom); Hudson, J.A. [Inst. of Hydrology, Llanbrynmair (United Kingdom)] [Inst. of Hydrology, Llanbrynmair (United Kingdom)

1999-01-15

310

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

311

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

PubMed Central

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

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

2014-01-01

312

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

PubMed

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

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

2014-04-29

313

LOX/Methane Main Engine Igniter Tests and Modeling  

NASA Technical Reports Server (NTRS)

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

Breisacher, Kevin J.; Ajmani, Kumund

2008-01-01

314

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

315

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

316

Physical injury stimulates aerobic methane emissions from terrestrial plants  

NASA Astrophysics Data System (ADS)

Physical injury is common in terrestrial plants as a result of grazing, trampling, and extreme weather events. Previous studies demonstrated enhanced emission of non-microbial CH4 under aerobic conditions from plant tissues when they were exposed to increasing UV radiation and temperature. Since physical injury is also a form of environmental stress, we sought to determine whether it would also affect CH4 emissions from plants. Physical injury (cutting) stimulated CH4 emission from fresh twigs of Artemisiaspecies under aerobic conditions. More cutting resulted in more CH4 emissions. Hypoxia also enhanced CH4 emission from both uncut and cut Artemisia frigida twigs. Physical injury typically results in cell wall degradation, which may either stimulate formation of reactive oxygen species (ROS) or decrease scavenging of them. Increased ROS activity might explain increased CH4 emission in response to physical injury and other forms of stress. There were significant differences in CH4 emissions among 10 species of Artemisia, with some species emitting no detectable CH4 under any circumstances. Consequently, CH4 emissions may be species-dependent and therefore difficult to estimate in nature based on total plant biomass. Our results and those of previous studies suggest that a variety environmental stresses stimulate CH4 emission from a wide variety of plant species. Global change processes, including climate change, depletion of stratospheric ozone, increasing ground-level ozone, spread of plant pests, and land-use changes, could cause more stress in plants on a global scale, potentially stimulating more CH4 emission globally.

Wang, Z.-P.; Gulledge, J.; Zheng, J.-Q.; Liu, W.; Li, L.-H.; Han, X.-G.

2009-01-01

317

Physical injury stimulates aerobic methane emissions from terrestrial plants  

NASA Astrophysics Data System (ADS)

Physical injury is common in terrestrial plants as a result of grazing, harvesting, trampling, and extreme weather events. Previous studies demonstrated enhanced emission of non-microbial CH4 under aerobic conditions from plant tissues when they were exposed to increasing UV radiation and temperature. Since physical injury is also a form of environmental stress, we sought to determine whether it would also affect CH4 emissions from plants. Physical injury (cutting) stimulated CH4 emission from fresh twigs of Artemisia species under aerobic conditions. More cutting resulted in more CH4 emissions. Hypoxia also enhanced CH4 emission from both uncut and cut Artemisia frigida twigs. Physical injury typically results in cell wall degradation, which may either stimulate formation of reactive oxygen species (ROS) or decrease scavenging of them. Increased ROS activity might explain increased CH4 emission in response to physical injury and other forms of stress. There were significant differences in CH4 emissions among 10 species of Artemisia, with some species emitting no detectable CH4 under any circumstances. Consequently, CH4 emissions may be species-dependent and therefore difficult to estimate in nature based on total plant biomass. Our results and those of previous studies suggest that a variety of environmental stresses stimulate CH4 emission from a wide variety of plant species. Global change processes, including climate change, depletion of stratospheric ozone, increasing ground-level ozone, spread of plant pests, and land-use changes, could cause more stress in plants on a global scale, potentially stimulating more CH4 emission globally.

Wang, Z.-P.; Gulledge, J.; Zheng, J.-Q.; Liu, W.; Li, L.-H.; Han, X.-G.

2009-04-01

318

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

PubMed

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

Chiemchaisri, Wilai; Chiemchaisri, Chart; Boonchaiyuttasak, Jindaruch

2013-08-01

319

Diffusive emissions of hydrothermal methane and higher hydrocarbons from the soil at Nisyros (Greece)  

NASA Astrophysics Data System (ADS)

Methane plays an important role in the Earth's atmospheric chemistry and radiative balance being the second most important greenhouse gas after carbon dioxide. Methane is released to the atmosphere by a wide number of sources, both natural and anthropogenic, with the latter being twice as large as the former. It has recently been established that significant amounts of geological methane and higher hydrocarbons, produced within the Earth's crust, are currently released naturally into the atmosphere. Active or recent volcanic/geothermal areas represent one of these sources of geological methane and higher hydrocarbons. Here we report on soil gas flux measurements made at Nisyros a currently quiescent active volcanic system with strong fumarolic activity due to the presence of a high enthalpy geothermal system. Methane and CO2 flux measurements from the soils were made with the accumulation chamber method in Lakki plain covering an area of about 0.01 km2 including the main fumarolic areas of Kaminakia, Ramos, Stefanos, Lofos and Phlegeton. The 127 measurements range from -3.4 to 1420 mg m-2 d-1 for CH4 and from 0.1 to 383 g m-2 d-1 for CO2. The five fumarolic areas show very different methane degassing pattern Kaminakia showing the highest flux values. The estimated methane output of these areas range about 0.01 t/a at Phlegeton to about 0.25 t/a at Kaminakia. The total output from the entire geothermal system of Nisyros should not exceed 1 t/a. The results of the chemical analyses of the concurrently collected fumarolic gases of the island gave clues on probable methanotrophic activity within the soil. Microbial activity in the soil of Lakki plain also controls the diffusive emission of thermogenic hydrocarbons released from the hydrothermal reservoir, mainly consisting of alkanes, aromatics and alkenes, which are partially transformed into their derivatives, such as aldehydes, ketons and alcohols.

D'Alessandro, Walter; Cabassi, Jacopo; Calabrese, Sergio; Capecchiacci, Francesco; Daskalopoulou, Kyriaki; Fiebig, Jens; Gagliano, Antonina Lisa; Kontomichalou, Artemis; Kyriakopoulos, Konstantinos; Milazzo, Silvia; Tassi, Franco

2014-05-01

320

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

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

321

Non-methane Hydrocarbon Emissions from a Subarctic Mire in Northern Sweden  

NASA Astrophysics Data System (ADS)

Northern peatlands in the Abisko region of northern Sweden are now subjected to climatic warming. In addition to carbon dioxide (CO2) and methane (CH4), which are intensively studied regarding carbon cycling and climate, there are non-methane hydrocarbons (NMHCs) emitted by plants. NMHC emissions may be a substantial part of the carbon emissions from an ecosystem. They can play a role in tropospheric radiation balance, oxidation chemistry and biogenic aerosol formation. The dynamics of NMHC emissions are not well understood, but impacts of light, temperature and photosynthetic rate and stress have been documented. There has been very little research conducted on NMHCs from vegetation in high latitude ecosystems. We have made high frequency automated chamber measurements of CO2 and total hydrocarbon (THC) fluxes from different subhabitats in a subarctic mire underlain by discontinuous permafrost in northern Sweden. Methane fluxes were also measured regularly but less frequently by manual grab sampling from the same chambers. During the summer of 2003-2004, a detailed study of the THC and methane flux rates was conducted in order to resolve patterns of NMHC fluxes. Four different sub-ecosystems are involved in the study. Manual sampling of methane was conducted three times a week during June to August in order to compare the THC to the methane flux. The THC fluxes range from near 0 to greater than 650 mg m-2 d-1 (calibrated as CH4). The highest fluxes are from the wettest sites. NMHCs are often more than 10% of the THC fluxes with a greater proportion of the THC flux from the drier sites with the lowest THC fluxes. The largest emissions were recorded from the wet, minerotrophic sites (E. angustifolium, E. vaginatum) followed by a semiwet site (Sphagnum mosses, C. rotundata). The dry ombrotrophic sites with several types of herbs and dwarf shrubs have much lower emission rates during clear chamber measurements but a distinct dark chamber effect has been detected from this vegetation, showing high rates of NMHC emission when darkened. Preliminary results from the HC analyses will be presented.

Backstrand, K.; Crill, P. M.; Christensen, T. R.; Mastepanov, M.

2004-12-01

322

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

SciTech Connect

Enhanced emissions of methane (CH{sub 4}) and nitric oxide (NO) were measured following three controlled burns in a Florida wetlands in 1987 and 1988. Wetlands are the major global source of methane resulting from metabolic activity of methanogenic bacteria. Methanogens require carbon dioxide, acetate, or formate for their growth and the metabolic production of methane. All three water-soluble compounds are produced in large concentrations during biomass burning. Postfire methane emissions exceeded 0.15 g CH{sub 4}/m{sup 2} d. 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, J.S.; Cofer, W.R. III; Sebacher, D.I.; Rhinehart, R.P. (NASA Langley Research Center, Hampton, VA (United States)); Winstead, E.L.; Sebacher, S. (ST Systems Corp., Hampton, VA (United States)); Hinkle, C.R.; Schmalzer, P.A.; Koller, A.M. Jr. (Bionetics Corp., NASA Kennedy Space Center, Cocoa Beach, FL (United States))

1990-02-20

323

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

324

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

325

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

NASA Astrophysics Data System (ADS)

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

Mastepanov, Mikhail; Christensen, Torben

2014-05-01

326

Identifying hot-spot methane emission sites in an impounded river  

NASA Astrophysics Data System (ADS)

Greenhouse gas (GHG) emissions on a landscape level are difficult to assess due to large spatial and temporal variations in fluxes. Freshwater ecosystems in particular, despite their limited spatial extent, can often have a disproportionately high impact on the GHG balance within the terrestrial landscape. Compounding the difficulties in assessing GHG emissions within these aquatic systems is that local production and emission rates show large variations due to small-scale physical and biogeochemical heterogeneity within the waterbody and sediment. Therefore, to ultimately characterize the total methane emissions from a limnic system using a bottom-up approach, the primary emission pathways and locations must be identified and quantified. To achieve this goal, we recorded continuous data with ship-mounted instruments over a 93 km longitudinal transect of the heavily impounded River Saar which consists of 7 dams and locks located every 15 km on average (Germany, France). A Contros HydroC Methane sensor measured the dissolved methane concentration to locate hot-spots and to estimate the diffusive flux across the water-air interface. Gas bubbles were detected and mapped using a Simrad Scientific echosounder and were processed to quantify ebullition-flux rates. Concentration differences directly up- and downstream of the dams were used to quantify the atmospheric transport component due to outgassing at the dams. Additional water and sediment samples along the 93 km transect completed the data set and allowed for sensor calibration. Methane concentrations ranged from 60 nM up to 1800 nM during the survey. Sharp and significant increases in dissolved methane concentrations were observed towards the forebay of three dams, with lower concentrations observed in the immediate tailwater of these dams. The areas of increasing concentrations coincided well with acoustically detected bubbles and with the distribution of cohesive muddy sediments. Ebullition flux rates varied between 20 to as much as 1300 mg CH4 m-2 d-1. While the areas where ebullition was detected covered only 15% of the total water surface area, they contributed 43% of the total emissions, while outgassing at the dams was quantified to yield about 53% of the total emissions (the remaining 4% by surface diffusion). Both pathways combined account for over 90% of the total methane emissions to the atmosphere and were identified using our high-resolution longitudinal methane concentration and acoustic bubble-detection survey. Our approach and results illustrate the importance of performing spatially-fine surveys on accurately resolving the spatial extent of outgassing "hot-spots" and pathways within freshwater systems. Temporal extrapolation of the quantified emissions would lead to the emission of 117 t CH4 yr-1 or 87 t CH4-C yr-1 from the Saar river system, but this estimate is limited because it represents only a snap-shot of the emission pattern and seasonal variations are not included. Despite this limitation, we show the importance of rivers, which are under-represented in the literature, as significant GHG contributors.

Maeck, A.; Flury, S.; DelSontro, T.; Schmidt, M.; McGinnis, D. F.; Fischer, H.; Fietzek, P.; Lorke, A.

2012-04-01

327

Measurements of biogenic non-methane organic compound emissions from grasslands  

SciTech Connect

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

Fukui, Yoshiko

1994-12-31

328

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

329

Physical injury stimulates aerobic methane emissions from terrestrial plants  

Microsoft Academic Search

Physical injury is common in terrestrial plants as a result of grazing, harvesting, trampling, and extreme weather events. Previous studies demonstrated enhanced emission of non-microbial CH4 under aerobic conditions from plant tis- sues when they were exposed to increasing UV radiation and temperature. Since physical injury is also a form of envi- ronmental stress, we sought to determine whether it

Z.-P. Wang; J. Gulledge; J.-Q. Zheng; W. Liu; L.-H. Li; X.-G. Han

2009-01-01

330

Physical injury stimulates aerobic methane emissions from terrestrial plants  

Microsoft Academic Search

Physical injury is common in terrestrial plants as a result of grazing, trampling, and extreme weather events. Previous studies demonstrated enhanced emission of non-microbial CH4 under aerobic conditions from plant tissues when they were exposed to increasing UV radiation and temperature. Since physical injury is also a form of environmental stress, we sought to determine whether it would also affect

Z.-P. Wang; J. Gulledge; J.-Q. Zheng; W. Liu; L.-H. Li; X.-G. Han

2009-01-01

331

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

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

332

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

333

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

334

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

335

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

336

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

337

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

338

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

339

Seasonal and diel variations of ammonia and methane emissions from a naturally ventilated dairy building and the associated factors influencing emissions.  

PubMed

Understanding seasonal and diel variations of ammonia (NH3) and methane (CH4) emissions from a naturally ventilated dairy (NVD) building may lead to develop successful control strategies for reducing emissions throughout the year. The main objective of this study was to quantify seasonal and diel variations of NH3 and CH4 emissions together with associated factors influencing emissions. Measurements were carried out with identical experimental set-up to cover three winter, spring and summer seasons, and two autumn seasons in the years 2010, 2011, and 2012. The data from 2010 and 2011 were used for developing emission prediction models and the data from 2012 were used for model validation. The results showed that NH3 emission varied seasonally following outside temperature whereas CH4 emission did not show clear seasonal trend. Diel variation of CH4 emission was less pronounced than NH3. The average NH3 and CH4 emissions between 6a.m. and 6p.m. were 66% and 33% higher than the average NH3 and CH4 emissions between 6p.m. and 6a.m., respectively for all seasons. The significant relationships (P<0.0001) between NH3 and influencing factors were found including outside temperature, humidity, wind speed and direction, hour of the day and day of the year. The significant effect (P<0.0001) of climate factors, hours of the day and days of the year on CH4 emission might be directly related to activities of the cows. PMID:24012895

Saha, C K; Ammon, C; Berg, W; Fiedler, M; Loebsin, C; Sanftleben, P; Brunsch, R; Amon, T

2014-01-15

340

A global model of natural volatile organic compound emissions  

Microsoft Academic Search

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

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

1995-01-01

341

Isotopic Ratios in Titan's Methane: Measurements and Modeling  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

342

ISOTOPIC RATIOS IN TITAN's METHANE: MEASUREMENTS AND MODELING  

SciTech Connect

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

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

2012-04-20

343

Reduction of Non-CO2 Gas Emissions Through The In Situ Bioconversion of Methane  

SciTech Connect

The primary objectives of this research were to seek previously unidentified anaerobic methanotrophs and other microorganisms to be collected from methane seeps associated with coal outcrops. Subsurface application of these microbes into anaerobic environments has the potential to reduce methane seepage along coal outcrop belts and in coal mines, thereby preventing hazardous explosions. Depending upon the types and characteristics of the methanotrophs identified, it may be possible to apply the microbes to other sources of methane emissions, which include landfills, rice cultivation, and industrial sources where methane can accumulate under buildings. Finally, the microbes collected and identified during this research also had the potential for useful applications in the chemical industry, as well as in a variety of microbial processes. Sample collection focused on the South Fork of Texas Creek located approximately 15 miles east of Durango, Colorado. The creek is located near the subsurface contact between the coal-bearing Fruitland Formation and the underlying Pictured Cliffs Sandstone. The methane seeps occur within the creek and in areas adjacent to the creek where faulting may allow fluids and gases to migrate to the surface. These seeps appear to have been there prior to coalbed methane development as extensive microbial soils have developed. Our investigations screened more than 500 enrichments but were unable to convince us that anaerobic methane oxidation (AMO) was occurring and that anaerobic methanotrophs may not have been present in the samples collected. In all cases, visual and microscopic observations noted that the early stage enrichments contained viable microbial cells. However, as the levels of the readily substrates that were present in the environmental samples were progressively lowered through serial transfers, the numbers of cells in the enrichments sharply dropped and were eliminated. While the results were disappointing we acknowledge that anaerobic methane oxidizing (AOM) microorganisms are predominantly found in marine habitats and grow poorly under most laboratory conditions. One path for future research would be to use a small rotary rig to collect samples from deeper soil horizons, possibly adjacent to the coal-bearing horizons that may be more anaerobic.

Scott, A R; Mukhopadhyay, B; Balin, D F

2012-09-06

344

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

PubMed

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

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

2014-06-01

345

Effect of Terminalia chebula and Allium sativum on in vivo methane emission by sheep.  

PubMed

A study was conducted to evaluate some plant parts (already tested for their antimethanogenic activity in in vitro gas production test in the authors' laboratory) as feed additive to combat methane emission from sheep. Sixteen male sheep with average body weight of 29.96±1.69 kg (22 months of age) were divided into four groups in a randomized block design. The animals were fed on a diet containing forage to concentrate ratio of 1:1. The concentrate fraction composed (in parts) of maize grain, 32; wheat bran, 45; deoiled soybean meal, 20; mineral mixture, 2 and common salt, 1. The four treatments were control (without additive), seed pulp of Terminalia chebula (Harad), bulb of Allium sativum (Garlic) and a mixture (Mix) of the latter two in equal proportions at the rate of 1% of dry matter (DM) intake. There was no effect on DM intake due to the inclusion of these feed additives. The digestibilities of DM and organic matter tended to be higher (p<0.1) in the groups with T. chebula and A. sativum, whereas, neutral detergent fibre (NDF), acid detergent fibre (ADF) and cellulose digestibilities were higher (p<0.05) in all the three experimental groups compared with control. The nitrogen balance and plane of nutrition were not affected by inclusion of any of the feed additives. Methane emission (L/kg digested DM intake) as estimated by open circuit respiration chamber and methane energy loss as per cent of digestible energy intake tended to be lower in T. chebula (p=0.09) and Mix (p=0.08) groups compared with control. The data indicated that T. chebula showed antimethanogenic activity, whereas both T. chebula and A. sativum improved nutrient digestibility. Therefore, these two plants appear to be suitable candidates for use as feed additive to mitigate methane emission and to improve nutrient utilization by sheep. PMID:20666858

Patra, A K; Kamra, D N; Bhar, R; Kumar, R; Agarwal, N

2011-04-01

346

The effect of biofuel production on swine farm methane and ammonia emissions.  

PubMed

Methane (CH) and ammonia (NH3) are emitted to the atmosphere during anaerobic processing of organic matter, and both gases have detrimental environmental effects. Methane conversion to biofuel production has been suggested to reduce CH4 emissions from animal manure processing systems. The purpose of this research is to evaluate the change in CH4 and NH3 emissions in an animal feeding operation due to biofuel production from the animal manure. Gas emissions were measured from swine farms differing only in their manure-management treatment systems (conventional vs. biofuel). By removing organic matter (i.e., carbon) from the biofuel farms' manure-processing lagoons, average annual CH4 emissions were decreased by 47% compared with the conventional farm. This represents a net 44% decrease in global warming potential (CO2 equivalent) by gases emitted from the biofuel farms compared with conventional farms. However, because of the reduction of methanogenesis and its reduced effect on the chemical conversion of ammonium (NH4+) to dinitrogen (N2) gas, NH3 emissions in the biofuel farms increased by 46% over the conventional farms. These studies show that what is considered an environmentally friendly technology had mixed results and that all components of a system should be studied when making changes to existing systems. PMID:21284295

Harper, Lowry A; Flesch, Thomas K; Weaver, Kim H; Wilson, John D

2010-01-01

347

Measurements of methane emissions from natural gas gathering facilities and processing plants: measurement methods  

NASA Astrophysics Data System (ADS)

Increased natural gas production in recent years has spurred intense interest in methane (CH4) emissions associated with its production, gathering, processing, transmission and distribution. Gathering and processing facilities (G&P facilities) are unique in that the wide range of gas sources (shale, coal-bed, tight gas, conventional, etc.) results in a wide range of gas compositions, which in turn requires an array of technologies to prepare the gas for pipeline transmission and distribution. We present an overview and detailed description of the measurement method and analysis approach used during a 20-week field campaign studying CH4 emissions from the natural gas G&P facilities between October 2013 and April 2014. Dual tracer flux measurements and onsite observations were used to address the magnitude and origins of CH4 emissions from these facilities. The use of a second tracer as an internal standard revealed plume-specific uncertainties in the measured emission rates of 20-47%, depending upon plume classification. Combining downwind methane, ethane (C2H6), carbon monoxide (CO), carbon dioxide (CO2), and tracer gas measurements with onsite tracer gas release allows for quantification of facility emissions, and in some cases a more detailed picture of source locations.

Roscioli, J. R.; Yacovitch, T. I.; Floerchinger, C.; Mitchell, A. L.; Tkacik, D. S.; Subramanian, R.; Martinez, D. M.; Vaughn, T. L.; Williams, L.; Zimmerle, D.; Robinson, A. L.; Herndon, S. C.; Marchese, A. J.

2014-12-01

348

Quantifying the relative contribution of natural gas fugitive emissions to total methane emissions in Colorado and Utah using mobile stable isotope (13CH4) analysis  

NASA Astrophysics Data System (ADS)

Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Because methane is more energy-rich than coal per kg of CO2 emitted into the atmosphere, it represents an attractive alternative to coal for electricity generation. However, given that the global warming potential of methane is many times greater than that of carbon dioxide (Solomon et al. 2007), the importance of quantifying the fugitive emissions of methane throughout the natural gas production and distribution process becomes clear (Howarth et al. 2011). A key step in the process of assessing the emissions arising from natural gas production activities is partitioning the observed methane emissions between natural gas fugitive emissions and other sources of methane, such as from landfills or agricultural activities. One effective method for assessing the contribution of these different sources is stable isotope analysis. In particular, the 13CH4 signature of natural gas (-35 to -40 permil) is significantly different that the signature of other significant sources of methane, such as landfills or ruminants (-45 to -70 permil). In this paper we present measurements of mobile field 13CH4 using a spectroscopic stable isotope analyzer based on cavity ringdown spectroscopy, in two intense natural gas producing regions of the United States: the Denver-Julesburg basin in Colorado, and the Uintah basin in Utah. Mobile isotope measurements in the nocturnal boundary layer have been made, over a total path of 100s of km throughout the regions, allowing spatially resolved measurements of the regional isotope signature. Secondly, this analyzer was used to quantify the isotopic signature of those individual sources (natural gas fugitive emissions, concentrated animal feeding operations, and landfills) that constitute the majority of methane emissions in these regions, by making measurements of the isotope ratio directly in the downwind plume from each source. These data are combined to establish the fraction of the observed methane emissions that can be attributed to natural gas activities in the regions. The fraction of total methane emissions in the Denver-Julesburg basin that can be attributed to natural gas fugitive emissions has been determined to be 71 +/- 9%. References: 1. S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.). IPCC, 2007: Climate Change 2007: The Physical Science Basis of the Fourth Assessment Report. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. 2. R.W. Howarth, R. Santoro, and A. Ingraffea. "Methane and the greenhouse-gas footprint of natural gas from shale formations." Climate Change, 106, 679 (2011).

Rella, Chris; Jacobson, Gloria; Crosson, Eric; Karion, Anna; Petron, Gabrielle; Sweeney, Colm

2013-04-01

349

Methane emissions from beef and dairy cattle: quantifying the effect of physiological stage and diet characteristics.  

PubMed

The prediction of methane outputs from ruminant livestock data at farm, national, and global scales is a vital part of greenhouse gas calculations. The objectives of this work were to quantify the effect of physiological stage (lactating or nonlactating) on predicting methane (CH4) outputs and to illustrate the potential improvement for a beef farming system of using more specific mathematical models to predict CH4 from cattle at different physiological stages and fed different diet types. A meta-analysis was performed on 211 treatment means from 38 studies where CH4, intake, animal, and feed characteristics had been recorded. Additional information such as type of enterprise, diet type, physiological stage, CH4 measurement technique, intake restriction, and CH4 reduction treatment application from these studies were used as classificatory factors. A series of equations for different physiological stages and diet types based on DMI or GE intake explained 96% of the variation in observed CH4 outputs (P<0.001). Resulting models were validated with an independent dataset of 172 treatment means from 20 studies. To illustrate the scale of improvement on predicted CH4 outputs from the current whole-farm prediction approach (Intergovernmental Panel on Climate Change [IPCC]), equations developed in the present study (NewEqs) were compared with the IPCC equation {CH4 (g/d)=[(GEI×Ym)×1,000]/55.65}, in which GEI is GE intake and Ym is the CH4 emission factor, in calculating CH4 outputs from 4 diverse beef systems. Observed BW and BW change data from cows with calves at side grazing either hill or lowland grassland, cows and overwintering calves and finishing steers fed contrasting diets were used to predict energy requirements, intake, and CH4 outputs. Compared with using this IPCC equation, NewEqs predicted up to 26% lower CH4 on average from individual lactating grazing cows. At the herd level, differences between equation estimates from 10 to 17% were observed in total annual accumulated CH4 when applied to the 4 diverse beef production systems. Overall, despite the small number of animals used it was demonstrated that there is a biological impact of using more specific CH4 prediction equations. Based on this approach, farm and national carbon budgets will be more accurate, contributing to reduced uncertainty in assessing mitigation options at farm and national level. PMID:24174549

Ricci, P; Rooke, J A; Nevison, I; Waterhouse, A

2013-11-01

350

Earth System Modeling of Ozone, Methane, and DMS  

NASA Astrophysics Data System (ADS)

One of the ways that the various Earth system components (land, atmosphere, ocean, and sea-ice) interact with each other is through chemical species, causing positive and negative feedbacks on the climate system. We will summarize the capabilities we have implemented within the Community Earth System Model (CESM, formerly known as CCSM) to simulate the Earth system interactions of ozone, methane, and dimethyl sulfide (DMS), including a fast atmospheric chemistry capability for millenial scale simulations (including IPCC AR5) that includes ozone, methane, sulfate aerosols, and related reactive gases, as well as an ocean ecosystem sulfur cycle, and the DMS coupling between ocean and atmosphere. We will then present the impacts of these chemical interactions on multi-decadal climate simulations, including the simulated changes in methane lifetime over the industrial era (1850-2000), the effect of the methane distribution on improving the fidelity of surface winds in the model, and the orographic enhancement of ozone concentrations in southern California in global simulations at high-resolution (0.25 degrees). Part of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

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

2010-12-01

351

Methane production and emission from peat. the influence of anions (sulphate, nitrate) from acid rain  

NASA Astrophysics Data System (ADS)

The influence of sulphate concentrations on the production and emission of methane in two contrasting peat sites was determined. Seasonal changes in sulphate concentrations appeared to influence the amount of organic carbon oxidised to carbon dioxide by sulphate reduction at both peat sites. For the majority of the year at both sites the amount of carbon mineralised through sulphate reduction exceeded that being transformed to methane by methanogenic bacteria, except when sulphate reduction became sulphate limited. In order to sustain the high sulphate reduction rates measured in the peat sulphide formed from dissimilatory sulphate reduction must be reoxidised rapidly to sulphate within the peat. Laboratory experiments showed that addition of 500 ?M sulphate and 100 ?M nitrate to peat samples significantly inhibited methanogenesis. Sulphate appeared to be the more important inhibitor of methanogenesis since inhibition of methane formation occurred with additions of sulphate reflecting in situ concentrations. Supplements of either acetate and/or hydrogen in combination with molybdate to peat samples revealed that methanogenesis was hydrogen limited and that the majority of active methanogens were hydrogen-utilising methanogens. Methanogenesis in peat samples appeared to be dependant on sulphate reducing bacteria for provision of substrates. Great Dun Fell, receiving the largest sulphate loading, had the lower rates of microbial activity (methane formation and sulphate reduction rates) than Ellergower, which received less than half the annual sulphate deposition of Great Dun Fell. This implied that some other factor—possibly organic matter lability, was limiting microbial rates of methane formation and sulphate reduction at Great Dun Fell.

Watson, Andrea; Nedwell, David B.

352

Methane and Nitrous Oxide Emissions from Livestock Agriculture in 16 Local Administrative Districts of Korea  

PubMed Central

This study was conducted to evaluate methane (CH4) and nitrous oxide (N2O) emissions from livestock agriculture in 16 local administrative districts of Korea from 1990 to 2030. National Inventory Report used 3 yr averaged livestock population but this study used 1 yr livestock population to find yearly emission fluctuations. Extrapolation of the livestock population from 1990 to 2009 was used to forecast future livestock population from 2010 to 2030. Past (yr 1990 to 2009) and forecasted (yr 2010 to 2030) averaged enteric CH4 emissions and CH4 and N2O emissions from manure treatment were estimated. In the section of enteric fermentation, forecasted average CH4 emissions from 16 local administrative districts were estimated to increase by 4%–114% compared to that of the past except for Daejeon (?63%), Seoul (?36%) and Gyeonggi (?7%). As for manure treatment, forecasted average CH4 emissions from the 16 local administrative districts were estimated to increase by 3%–124% compared to past average except for Daejeon (?77%), Busan (?60%), Gwangju (?48%) and Seoul (?8%). For manure treatment, forecasted average N2O emissions from the 16 local administrative districts were estimated to increase by 10%–153% compared to past average CH4 emissions except for Daejeon (?60%), Seoul (?4.0%), and Gwangju (?0.2%). With the carbon dioxide equivalent emissions (CO2-Eq), forecasted average CO2-Eq from the 16 local administrative districts were estimated to increase by 31%–120% compared to past average CH4 emissions except Daejeon (?65%), Seoul (?24%), Busan (?18%), Gwangju (?8%) and Gyeonggi (?1%). The decreased CO2-Eq from 5 local administrative districts was only 34 kt, which was insignificantly small compared to increase of 2,809 kt from other 11 local administrative districts. Annual growth rates of enteric CH4 emissions, CH4 and N2O emissions from manure management in Korea from 1990 to 2009 were 1.7%, 2.6%, and 3.2%, respectively. The annual growth rate of total CO2-Eq was 2.2%. Efforts by the local administrative offices to improve the accuracy of activity data are essential to improve GHG inventories. Direct measurements of GHG emissions from enteric fermentation and manure treatment systems will further enhance the accuracy of the GHG data. (Key Words: Greenhouse Gas, Methane, Nitrous Oxide, Carbon Dioxide Equivalent Emission, Climate Change) PMID:25049543

Ji, Eun Sook; Park, Kyu-Hyun

2012-01-01

353

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

NASA Technical Reports Server (NTRS)

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 with emissions from Peltandra virginica (L.) that gradually rose to a peak in the mid-afternoon corresponding to elevated air temperatures. Internal CH4 concentrations within P. virginica stems did not change significantly over the diurnal period. Stomatal conductance appeared to correlate directly with light levels in both plant types and were not associated with peak CH4 emission events in either plant. These patterns are consistent with a convective throughflow and diffusive gas ventilation systems for Typha and Peltandra, respectively. Further effects of the convective throughflow in T. latifolia were evident in the elevated CH4 concentrations measured within brown leaves as contrasted to the near ambient levels measured within live green leaves. Experimental manipulation of elevated and reduced CO2 levels in the atmosphere surrounding the plants and of light/dark periods suggested that stomatal aperture has little or no control of methane emissions from T. latifolia.

Whiting, Gary J.; Chanton, Jeffrey P.

1995-01-01

354

Surface water methane super-saturation and emission in Lake Lugano, southern Switzerland  

NASA Astrophysics Data System (ADS)

Large amounts of greenhouse gases are produced in anoxic aquatic environments. Emission of these greenhouse gases to the atmosphere depends on their turbulent diffusion across the water - air boundary, which in turn depends on the concentrations within the boundary layers. We measured methane concentrations in the surface water of the northern basin of Lake Lugano in spring and autumn, and calculated diffusive fluxes to the atmosphere, using three different relationships for the parameterisation of the transfer velocity, taking into account temperature and wind effects. Surface water concentrations always exceeded atmospheric equilibrium concentration, and increased from 16 nmol L-1 in May to 45 nmol L-1 in October, indicating CH4 accumulation in the surface mixed layer during summer. Calculated CH4 fluxes were highly variable in space and time. As a result of the higher surface water CH4 concentration and cooling of the surface boundary layer, resulting in increased buoyancy turbulence, the diffusive flux was highest in October (97 ?mol m-2 d-1, compared to 7 ?mol m-2 d-1 in May). The observed concentration profiles indicate that mixed layer CH4 accumulation derives from a near-surface source, and cannot be explained by the diffusive supply of CH4 from the large deep-water CH4 pool in the anoxic hypolimnion, where CH4 oxidation at the redox transition zone consumes CH4 effectively. Our study confirms that lake environments can act as a significant terrestrial source for atmospheric methane, despite efficient microbial CH4 oxidation in the hypolimnion. The fact that the magnitude of the observed total CH4 flux increases during the productive period between spring (409 mol d-1) and autumn (968 mol d-1) suggests links between methane evasion and the annual biological cycle, yet wind and temperature forcing of the surface mixed layer must play an equally important role for lacustrine methane emission.

Blees, Jan; Niemann, Helge; Erne, Markus; Simona, Marco; Lehmann, Moritz F.

2014-05-01

355

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

356

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

357

Emissions of non-methane organic compounds from a grassland site  

SciTech Connect

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 {mu}g m{sup -2} hr{sup -1} in June 1992 to 150 {mu}g m{sup - 2} hr{sup -1} in October 1992, except for a slight increase in August. Oxygenated hydrocarbons (methanol, acetaldehyde, and acetone) and terpenes (isoprene, limonene, myrcene, {alpha}-pinene, and {beta}- pinene) composed about 90% and 10% of the identified NMOC emissions, respectively. Isoprene represented about 10% of the terpene emissions. Total NMOC emission rates based on vegetative biomass averaged 2.3 {mu}g g{sup -1} hr{sup -1}, with 10% of the identified NMOCs attributed to monoterpenes and the remainder mainly OxHCs. Over the course of the investigation, the relationship between the monoterpene emission rate and the temperature for a single plot was logarithmic and similar to the one between compound vapor pressure and temperature. However, emission rates normalized to temperature decreased throughout the summer and fall, indicating that parameterizations of emission rates from herbaceous plants must include a factor to compensate for environmental conditions such as soil moisture and nutrient deposition, which affect plant phenology and the seasonal pattern of species dominance.

Fukui, Yoshiko; Doskey, P.V.

1996-03-01

358

A conduit dilation model of methane venting from lake sediments  

E-print Network

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 ...

Ruppel, Carolyn

359

Environmental controls over methane emissions from bromeliad phytotelmata: The role of phosphorus and nitrogen availability, temperature, and water content  

NASA Astrophysics Data System (ADS)

bromeliads are common epiphytic plants throughout neotropical forests that store significant amounts of water in phytotelmata (tanks) formed by highly modified leafs. Methanogenic archaea in these tanks have recently been identified as a significant source of atmospheric methane. We address the effects of environmental drivers (temperature, tank water content, sodium phosphate [P], and urea [N] addition) on methane production in anaerobically incubated bromeliad slurry and emissions from intact bromeliad tanks in montane Ecuador. N addition ? 1 mg g-1 had a significantly positive effect on headspace methane concentrations in incubation jars while P addition did not affect methane production at any dosage (? 1 mg g-1). Tank bromeliads (Tillandsia complanata) cultivated in situ showed significantly increased effluxes of methane in response to the addition of 26 mg N addition per tank but not to lower dosage of N or any dosage of P (? 5.2 mg plant-1). There was no significant interaction between N and P addition. The brevity of the stimulatory effect of N addition on plant methane effluxes (1-2 days) points at N competition by other microorganisms or bromeliads. Methane efflux from plants closely followed within-day temperature fluctuations over 24 h cycles, yet the dependency of temperature was not exponential as typical for terrestrial wetlands but instead linear. In simulated drought, methane emission from bromeliad tanks was maintained with minimum amounts of water and regained after a short lag phase of approximately 24 h. Our results suggest that methanogens in bromeliads are primarily limited by N and that direct effects of global change (increasing temperature and seasonality, remote fertilization) on bromeliad methane emissions are of moderate scale.

Kotowska, Martyna M.; Werner, Florian A.

2013-12-01

360

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

Microsoft Academic Search

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

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

2000-01-01

361

EPA's Global Climate Change Program. Program plan for methane emissions from landfills and other waste disposal facilities  

Microsoft Academic Search

The paper discusses a portion of EPA's global climate change program, a program plan for methane emissions from landfills and other waste disposal facilities. In response to concerns about global climate change, the U.S. EPA's Office of Research and Development (ORD) has initiated an emissions and mitigation program. ORD's Air and Energy Engineering Research Laboratory (AEERL) has begun research on

Thorneloe

1991-01-01

362

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

EPA Science Inventory

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

363

An inverse modeling approach to investigate the global atmospheric methane cycle  

Microsoft Academic Search

Estimates of the global magnitude of atmospheric methane sources are currently mainly based on direct flux measurements in source regions. Their extrapolation to the entire globe often involves large uncertainties. In this paper, we present an inverse modeling approach which can be used to deduce information on methane sources and sinks from the temporal and spatial variations of atmospheric methane

Ralf Hein; Paul J. Crutzen; Martin Heimann

1997-01-01

364

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

365

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

NASA Astrophysics Data System (ADS)

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

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

1991-02-01

366

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

PubMed

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

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

2014-10-01

367

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

PubMed

The global warming caused by greenhouse gases emission has raised serious concerns. Recent studies found that the carbon dioxide (CO2) and methane (CH4) emissions from river ecosystem can partly offset the carbon sequestration by terrestrial ecosystem, leading to a rethink of the effects of river ecosystem on the global carbon balance and greenhouse gases emission inventory. As an important primary producer in urban river ecosystem, filamentous macroalgae can deeply affect the carbon cycle process of river system through changing the abiotic and biotic factors in the interface of water-sediment. This paper reviewed the effects of filamentous macroalgae on the CH4 emission from urban river system from the aspects of 1) the effects of urbanization on the river ecosystem and its CH4 emission flux, 2) the effects of filamentous macroalgae on the CH4 generation and emission process in natural river systems, and 3) the effects of filamentous macroalgae on the primary productivity and CH4 emission process in urban river systems. The current problems and future directions in related researches were discussed and prospected. PMID:24015546

Zhang, Xiu-Yun; Liang, Xia; He, Chi-Quan

2013-05-01

368

Environmental and physical controls on northern terrestrial methane emissions across permafrost zones  

USGS Publications Warehouse

Methane (CH4) emissions from the northern high-latitude region represent potentially significant biogeochemical feedbacks to the climate system. We compiled a database of growing-season CH4 emissions from terrestrial ecosystems located across permafrost zones, including 303 sites described in 65 studies. Data on environmental and physical variables, including permafrost conditions, were used to assess controls on CH4 emissions. Water table position, soil temperature, and vegetation composition strongly influenced emissions and had interacting effects. Sites with a dense sedge cover had higher emissions than other sites at comparable water table positions, and this was an effect that was more pronounced at low soil temperatures. Sensitivity analysis suggested that CH4 emissions from ecosystems where the water table on average is at or above the soil surface (wet tundra, fen underlain by permafrost, and littoral ecosystems) are more sensitive to variability in soil temperature than drier ecosystems (palsa dry tundra, bog, and fen), whereas the latter ecosystems conversely are relatively more sensitive to changes of the water table position. Sites with near-surface permafrost had lower CH4 fluxes than sites without permafrost at comparable water table positions, a difference that was explained by lower soil temperatures. Neither the active layer depth nor the organic soil layer depth was related to CH4 emissions. Permafrost thaw in lowland regions is often associated with increased soil moisture, higher soil temperatures, and increased sedge cover. In our database, lowland thermokarst sites generally had higher emissions than adjacent sites with intact permafrost, but emissions from thermokarst sites were not statistically higher than emissions from permafrost-free sites with comparable environmental conditions. Overall, these results suggest that future changes to terrestrial high-latitude CH4 emissions will be more proximately related to changes in moisture, soil temperature, and vegetation composition than to increased availability of organic matter following permafrost thaw.

Olefeldt, David; Turetsky, Merritt R.; Crill, Patrick M.; McGuire, A. David

2013-01-01

369

Zero Emissions Hydrogen Production by Fluidized Bed Catalytic Decomposition of Methane  

NASA Astrophysics Data System (ADS)

The present paper deals with the strategic field of production of clean fuels with very low to zero emissions. A two stage fluidized bed process for catalytic decomposition of methane has been investigated. Firstly, the fluidized bed has been operated for the thermo-catalytic decomposition (TCD) of methane to produce hydrogen and solid carbon, which deposited on the catalyst. Secondly, the carbon oxy-combustion has been carried out to regenerate the catalyst producing a separated CO2 stream candidate to be directly fed to a sequestration unit. Experiments have been carried out in a laboratory scale bubbling fluidized bed reactor (26mm ill) using a home-made copper dispersed on ?-alumina as catalyst operated at 800°C. The carbon oxy-combustion regeneration strategy have been compared to the carbon combustion one on the basis of the efficiency of carbon removal and the performance ofregenerated catalyst with respect to the TCD process. The effect of multiple cycles of decomposition and regeneration steps has been also quantified. A reasonable cycli