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1

Coupled land-atmosphere modeling of methane emissions with WRF  

NASA Astrophysics Data System (ADS)

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

Taylor, D.

2013-12-01

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

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

5

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

6

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

7

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 is the effects of aviation emissions on ozone and atmospheric chemistry. In this study the effects of aviation emissions on atmospheric ozone for 2006 and two projections for 2050 are compared among seven models

Jacobson, Mark

8

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

9

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

10

Characterization of urban methane emissions in Boston, Massachusetts using an observational network and inverse modeling framework  

NASA Astrophysics Data System (ADS)

There is much uncertainty about the magnitude of methane emissions from natural gas production and delivery infrastructure, yet this quantity is necessary for understanding the climate impact of natural gas as a major fuel source and for partitioning the global methane budget. Preliminary evidence suggests that leaks from urban natural gas distribution systems may release substantial quantities of methane to the atmosphere, but this source has seldom been directly investigated in the scientific literature. As a case study, we seek to describe and quantify the natural gas fraction of the total methane source in the Boston, Massachusetts metropolitan region. We describe the design of an atmospheric methane monitoring network in and around the city. Periodic measurements of atmospheric ethane are used to estimate the fractional contribution of natural gas to the total observed urban methane enhancement. A methane emission inventory is compiled from high-resolution information on biogenic methane sources, street-level methane concentrations, and the natural gas distribution infrastructure. We present preliminary results from the observational network and an inverse modeling framework.

McKain, K.; Wofsy, S. C.; John, B.; Hutyra, L.; Raciti, S.; Briber, B.; Phillips, N. G.; Jackson, R. B.; Down, A.; Schaaf, C.

2012-12-01

11

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

NASA Astrophysics Data System (ADS)

Methane is an important greenhouse gas contributing approximately 15% to the present greenhouse warming. Tundra ecosystems between 50°N and 70°N are estimated to contain 14% of the global soil carbon and account for between 20 and 25% of the natural methane emissions. Consequently, enhanced anaerobic decomposition of tundra soil carbon and the associated increase in methane production could provide a significant positive feedback on the anthropogenic greenhouse effect. This work is an attempt to quantify this feedback for arctic tundra. A model of permafrost thermodynamics and methane emission has been developed for inclusion in the UK Meteorological Office land surface scheme. This improved scheme was tested by driving it directly with surface meteorological observations and comparing the simulated methane emission to those observed during a field study on the North Slope of Alaska. Results are also presented from simulations carried out with the single column version of the Hadley Centre climate model, for both current conditions and a simple doubled carbon dioxide warming scenario. The latter shows a significantly enhanced methane emission. In order to assess the dependence of this result on the particular scenario chosen, offline sensitivity studies were carried out using meteorological observations and a range of perturbations to air temperature and rainfall.

Christensen, T. R.; Cox, P.

1995-07-01

12

Methane emission by camelids.  

PubMed

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

13

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

14

The landfill methane balance: Model and practical applications  

SciTech Connect

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

Bogner, J.; Spokas, K.

1995-10-01

15

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

NASA Astrophysics Data System (ADS)

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, C.; Melack, J.; Hess, L.; Forsberg, B.; Novo, E. M.; Klooster, S.

2004-12-01

16

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

17

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

18

Methane emissions from MBT landfills.  

PubMed

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

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

2013-09-01

19

Estimating National Landfill Methane Emissions: An Application of the 2006 Intergovernmental Panel on Climate Change Waste Model in Panama  

Microsoft Academic Search

This paper estimates national methane emissions from solid waste disposal sites in Panama over the time period 1990–2020 using both the 2006 Intergovernmental Panel on Climate Change (IPCC) Waste Model spreadsheet and the default emissions estimate approach presented in the 1996 IPCC Good Practice Guidelines. The IPCC Waste Model has the ability to calculate emissions from a variety of solid

Melissa Weitz; Jeffrey B. Coburn; Edgar Salinas; Chart Chiemchaisri; Wilai Chiemchaisri; Sayan Tudsri; Sunil Kumar; Josias Zietsman; Muhammad Bari; Aaron Rand; Bhushan Gokhale; Dominique Lord; Jenny Sanderson; Patrick Hettiaratchi; Carlos Hunte; Omar Hurtado; Alejandro Keller; Chettiyappan Visvanathan; Ahmed Soliman; Robert Jacko; Nancy Burton; Atin Adhikari; Yulia Iossifova; Sergey Grinshpun; Tiina Reponen; James Wilson; Maureen Mullen; Andrew Bollman; Kirstin Thesing; Manish Salhotra; Frank Divita; James Neumann; Jason Price; James DeMocker; Mae Gustin; Jody Ericksen; George Fernandez; Ryan LeBouf; Liesel Yesse; Alan Rossner; Deborah Luecken; Alan Cimorelli; Wei-Hsin Chen; Shan-Wen Du; Hsi-Hsien Yang; Jheng-Syun Wu; Diane Ivy; James Mulholland; Armistead Russell

2008-01-01

20

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

21

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

22

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

23

Modeling methane emissions from paddy rice fields under elevated atmospheric carbon dioxide conditions  

NASA Astrophysics Data System (ADS)

Methane (CH4) emissions from paddy rice fields substantially contribute to the dramatic increase of this greenhouse gas in the atmosphere. Due to great concern about climate change, it is necessary to predict the effects of the dramatic increase in atmospheric carbon dioxide (CO2) on CH4 emissions from paddy rice fields. CH4MOD 1.0 is the most widely validated model for simulating CH4 emissions from paddy rice fields exposed to ambient CO2 (hereinafter referred to as aCO2). We upgraded the model to CH4MOD 2.0 by: (a) modifying the description of the influences of soil Eh and the water regime on CH4 production; (b) adding new features to reflect the regulatory effects of atmospheric CO2 upon methanogenic substrates, soil Eh during drainages, and vascular CH4 transport; and (c) adding a new feature to simulate the influences of nitrogen (N) addition rates on methanogenic substrates under elevated CO2 (hereinafter referred to as eCO2) condition. Validation with 109 observation cases under aCO2 condition showed that CH4MOD 2.0 possessed a minor systematic bias in the prediction of seasonally accumulated methane emissions (SAM). Validation with observations in free-air CO2 enrichment (FACE) experiments in temperate and subtropical climates showed that CH4MOD 2.0 successfully simulated the effects of eCO2 upon SAM from paddy rice fields incorporated with various levels of previous crop residues and/or N fertilizer. Our results imply that CH4MOD 2.0 provides a potential approach for estimating of the effects of elevated atmospheric CO2 upon CH4 emissions from regional or global paddy rice fields with various management practices in a changing climate.

Xie, Baohua; Zhou, Zaixing; Zheng, Xunhua; Zhang, Wen; Zhu, Jianguo

2010-01-01

24

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

25

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

26

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

27

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

28

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

29

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

30

Estimating historical landfill quantities to predict methane emissions  

NASA Astrophysics Data System (ADS)

There are no observations for methane emissions from landfill waste in Ireland. Methane emissions are imputed from waste data. There are intermittent data on waste sent to landfill. We compare two alternative ways to impute the missing waste "data" and evaluate the impact on methane emissions. We estimate Irish historical landfill quantities from 1960-2008 and Irish methane emissions from 1968-2006. A model is constructed in which waste generation is a function of income, price of waste disposal and, household economies of scale. A transformation ratio of waste to methane is also included in the methane emissions model. Our results contrast significantly with the Irish Environmental Protection Agency's (EPA) figures due to the differences in the underlying assumptions. The EPA's waste generation and methane emission figures are larger than our estimates from the early 1990s onwards. Projections of the distance to target show that the EPA overestimates the required policy effort.

Lyons, Seán; Murphy, Liam; Tol, Richard S. J.

2010-10-01

31

Methane emissions from grasslands  

Microsoft Academic Search

IntroductionMethane (CH 4<\\/sub> ) is an important greenhouse gas. The concentration of greenhouse gases in the atmosphere has been increasing since pre-industrial times, mainly due to human activities. This increase gives concern, because it may cause global warming due to an enhanced greenhouse effect.In the soil, CH 4<\\/sub> may be produced under anaerobic conditions, and consumed under aerobic conditions. Net

Pol-van Dasselaar van den A

1998-01-01

32

Observational Constraints on Changing Arctic Methane Emissions  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

33

Investigations of methane emissions from rice cultivation in Indian context.  

PubMed

The increasing demand of the growing population requires enhancement in the production of rice. This has a direct bearing on the global environment since the rice cultivation is one of the major contributors to the methane emissions. As the rice cultivation is intensified with the current practices and technologies, the methane fluxes from paddy fields will substantially rise. Improved high yielding rice varieties together with efficient cultivation techniques will certainly contribute to the curtailment of the methane emission fluxes. In this paper, the system dynamic approach is used for estimating the methane emissions from rice fields in India till the year 2020. Mitigation options studied for curtailing the methane emissions include rice production management, use of low methane emitting varieties of rice, water management and fertilizer amendment. The model is validated quantitatively and sensitivity tests are carried out to examine the robustness of the model. PMID:15788188

Anand, Shalini; Dahiya, R P; Talyan, Vikash; Vrat, Prem

2005-05-01

34

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

35

Methane emissions from the West Siberian wetlands  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

36

Climatic and Chemical Controls on Methane Emissions from Wetlands  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

37

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

38

Estimation of wetland methane emissions in a biogeochemical model integrated in CESM: sensitivity analysis and comparison against surface and atmospheric measurements  

NASA Astrophysics Data System (ADS)

Methane emissions from natural wetlands and rice paddies constitute a large proportion of atmospheric methane, but the magnitude and year-to-year variation of these methane sources is still unpredictable. Here we describe and evaluate the integration of a methane biogeochemical model (CLM4Me; Riley et al. 2011) into the Community Land Model 4.0 (CLM4CN) in order to better explain spatial and temporal variations in methane emissions. We test new functions for soil pH and redox potential that impact microbial methane production in soils. We also constrain aerenchyma in plants in always-inundated areas in order to better represent wetland vegetation. Satellite inundated fraction is explicitly prescribed in the model because there are large differences between simulated fractional inundation and satellite observations and thus we do not use CLM4 simulated inundated area. The model is evaluated at the site level with vegetation cover and water table prescribed from measurements. Explicit site level evaluations of simulated methane emissions are quite different than evaluating the grid cell averaged emissions against available measurements. Using a baseline set of parameter values, our model-estimated average global wetland emissions for the period 1993-2004 were 256 Tg CH4 y-1 (including the soil sink). Tropical wetlands contributed 201 Tg CH4 y-1, or 78% of the global wetland flux. Northern latitude (>50N) systems contributed 12 Tg CH4 y-1. Our sensitivity studies show a large range (150-346 Tg CH4 y-1) in predicted global methane emissions. In order to evaluate our methane emissions on the regional and global scales against atmospheric measurements, we conducted simulations with the Community Atmospheric Model with chemistry (CAM-chem) forced with our baseline simulation of wetland and rice paddy emissions along with other methane sources (e.g. anthropogenic, fire, and termite emissions) and compared model simulations against measured atmospheric concentrations obtained from the World Data Centre for Greenhouse Gases (WDCGG) at http://ds.data.jma.go.jp/gmd/wdcgg/. Overall, using our estimated wetland and rice paddy emissions, CAM-chem model can produce seasonal and interannual variations of observed atmospheric concentration performs well. Thus, within the current level of uncertainty, our emissions appear to be reasonable.

Meng, L.; Mahowald, N. M.; Hess, P. G.; Yavitt, J. B.; Riley, W. J.; Subin, Z. M.; Lawrence, D. M.; Swenson, S. C.; Jauhiainen, J.; Fuka, D. R.

2012-12-01

39

Diurnal variations in methane emission from rice plants  

E-print Network

of water and subsequently the emission of methane. Methane emission was negatively correlated with biomass, probably due to effects of root biomass on soil water methane concentration. Methane concentration in soil water was negatively correlated...

Laskowski, Nicholas Aaron

2004-11-15

40

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

41

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

42

Methane emission during municipal wastewater treatment.  

PubMed

Municipal wastewater treatment plants emit methane. Since methane is a potent greenhouse gas that contributes to climate change, the abatement of the emission is necessary to achieve a more sustainable urban water management. This requires thorough knowledge of the amount of methane that is emitted from a plant, but also of the possible sources and sinks of methane on the plant. In this study, the methane emission from a full-scale municipal wastewater facility with sludge digestion was evaluated during one year. At this plant the contribution of methane emissions to the greenhouse gas footprint were slightly higher than the CO? emissions related to direct and indirect fossil fuel consumption for energy requirements. By setting up mass balances over the different unit processes, it could be established that three quarters of the total methane emission originated from the anaerobic digestion of primary and secondary sludge. This amount exceeded the carbon dioxide emission that was avoided by utilizing the biogas. About 80% of the methane entering the activated sludge reactor was biologically oxidized. This knowledge led to the identification of possible measures for the abatement of the methane emission. PMID:22575155

Daelman, Matthijs R J; van Voorthuizen, Ellen M; van Dongen, Udo G J M; Volcke, Eveline I P; van Loosdrecht, Mark C M

2012-07-01

43

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.

Bank, World

44

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

45

Methane emissions from floodplains in the Amazon Basin: challenges in developing a process-based model for global applications  

NASA Astrophysics Data System (ADS)

Tropical wetlands are estimated to represent about 50% of the natural wetland methane (CH4) emissions and explain a large fraction of the observed CH4 variability on timescales ranging from glacial-interglacial cycles to the currently observed year-to-year variability. Despite their importance, however, tropical wetlands are poorly represented in global models aiming to predict global CH4 emissions. This publication documents a first step in the development of a process-based model of CH4 emissions from tropical floodplains for global applications. For this purpose, the LPX-Bern Dynamic Global Vegetation Model (LPX hereafter) was slightly modified to represent floodplain hydrology, vegetation and associated CH4 emissions. The extent of tropical floodplains was prescribed using output from the spatially explicit hydrology model PCR-GLOBWB. We introduced new plant functional types (PFTs) that explicitly represent floodplain vegetation. The PFT parameterizations were evaluated against available remote-sensing data sets (GLC2000 land cover and MODIS Net Primary Productivity). Simulated CH4 flux densities were evaluated against field observations and regional flux inventories. Simulated CH4 emissions at Amazon Basin scale were compared to model simulations performed in the WETCHIMP intercomparison project. We found that LPX reproduces the average magnitude of observed net CH4 flux densities for the Amazon Basin. However, the model does not reproduce the variability between sites or between years within a site. Unfortunately, site information is too limited to attest or disprove some model features. At the Amazon Basin scale, our results underline the large uncertainty in the magnitude of wetland CH4 emissions. Sensitivity analyses gave insights into the main drivers of floodplain CH4 emission and their associated uncertainties. In particular, uncertainties in floodplain extent (i.e., difference between GLC2000 and PCR-GLOBWB output) modulate the simulated emissions by a factor of about 2. Our best estimates, using PCR-GLOBWB in combination with GLC2000, lead to simulated Amazon-integrated emissions of 44.4 ± 4.8 Tg yr-1. Additionally, the LPX emissions are highly sensitive to vegetation distribution. Two simulations with the same mean PFT cover, but different spatial distributions of grasslands within the basin, modulated emissions by about 20%. Correcting the LPX-simulated NPP using MODIS reduces the Amazon emissions by 11.3%. Finally, due to an intrinsic limitation of LPX to account for seasonality in floodplain extent, the model failed to reproduce the full dynamics in CH4 emissions but we proposed solutions to this issue. The interannual variability (IAV) of the emissions increases by 90% if the IAV in floodplain extent is accounted for, but still remains lower than in most of the WETCHIMP models. While our model includes more mechanisms specific to tropical floodplains, we were unable to reduce the uncertainty in the magnitude of wetland CH4 emissions of the Amazon Basin. Our results helped identify and prioritize directions towards more accurate estimates of tropical CH4 emissions, and they stress the need for more research to constrain floodplain CH4 emissions and their temporal variability, even before including other fundamental mechanisms such as floating macrophytes or lateral water fluxes.

Ringeval, B.; Houweling, S.; van Bodegom, P. M.; Spahni, R.; van Beek, R.; Joos, F.; Röckmann, T.

2014-03-01

46

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

47

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...

48

Regional landfills methane emission inventory in Malaysia.  

PubMed

The decomposition of municipal solid waste (MSW) in landfills under anaerobic conditions produces landfill gas (LFG) containing approximately 50-60% methane (CH(4)) and 30-40% carbon dioxide (CO(2)) by volume. CH(4) has a global warming potential 21 times greater than CO(2); thus, it poses a serious environmental problem. As landfills are the main method for waste disposal in Malaysia, the major aim of this study was to estimate the total CH(4) emissions from landfills in all Malaysian regions and states for the year 2009 using the IPCC, 1996 first-order decay (FOD) model focusing on clean development mechanism (CDM) project applications to initiate emission reductions. Furthermore, the authors attempted to assess, in quantitative terms, the amount of CH(4) that would be emitted from landfills in the period from 1981-2024 using the IPCC 2006 FOD model. The total CH(4) emission using the IPCC 1996 model was estimated to be 318.8 Gg in 2009. The Northern region had the highest CH(4) emission inventory, with 128.8 Gg, whereas the Borneo region had the lowest, with 24.2 Gg. It was estimated that Pulau Penang state produced the highest CH(4) emission, 77.6 Gg, followed by the remaining states with emission values ranging from 38.5 to 1.5 Gg. Based on the IPCC 1996 FOD model, the total Malaysian CH( 4) emission was forecast to be 397.7 Gg by 2020. The IPCC 2006 FOD model estimated a 201 Gg CH(4) emission in 2009, and estimates ranged from 98 Gg in 1981 to 263 Gg in 2024. PMID:20858637

Abushammala, Mohammed F M; Noor Ezlin Ahmad Basri; Basri, Hassan; Ahmed Hussein El-Shafie; Kadhum, Abdul Amir H

2011-08-01

49

Methane emission from wetlands in Taiwan  

NASA Astrophysics Data System (ADS)

To investigate methane emission from wetlands in Taiwan, soil properties, environmental conditions and methane emission were determined at three wetlands in northern Taiwan from September 1995 to April 1999. Soil pH values ranged from 6.15 to 7.80. Total organic carbon and total nitrogen contents were high in Kuan-du wetland and Kang-nan lake area, where the soils were sandy loam. In Kang-nan wetland, total organic carbon and total nitrogen contents were low and the soil was clay loam. Soil redox potential of Kuan-du wetland and Kang-nan lake area was lower than that of Kang-nan wetland. Atmospheric methane concentration was 0.8-2.7, 0.7-1.6 and 0.8-1.7 ppm (mg kg -1) in Kang-du wetland, Kang-nan wetland and Kang-nan lake area, respectively. Average methane emission rate was 1.82, 0.14 and 0.23 mg m -2 h -1 and annual methane emission was about 1.59×10 -1, 1.23×10 -2 and 2.02×10 -2 ton ha -1, respectively. Annual methane emission from 11,896 ha of nine wetlands is estimated around 340 ton in Taiwan.

Chang, Tsan-Chang; Yang, Shang-Shyng

50

Measurement and prediction of enteric methane emission  

NASA Astrophysics Data System (ADS)

The greenhouse gas (GHG) emissions from the agricultural sector account for about 25.5% of total global anthropogenic emission. While CO2 receives the most attention as a factor relative to global warming, CH4, N2O and chlorofluorocarbons (CFCs) also cause significant radiative forcing. With the relative global warming potential of 25 compared with CO2, CH4 is one of the most important GHGs. This article reviews the prediction models, estimation methodology and strategies for reducing enteric CH4 emissions. Emission of CH4 in ruminants differs among developed and developing countries, depending on factors like animal species, breed, pH of rumen fluid, ratio of acetate:propionate, methanogen population, composition of diet and amount of concentrate fed. Among the ruminant animals, cattle contribute the most towards the greenhouse effect through methane emission followed by sheep, goats and buffalos, respectively. The estimated CH4 emission rate per cattle, buffaloe, sheep and goat in developed countries are 150.7, 137, 21.9 and 13.7 (g/animal/day) respectively. However, the estimated rates in developing countries are significantly lower at 95.9 and 13.7 (g/animal/day) per cattle and sheep, respectively. There exists a strong interest in developing new and improving the existing CH4 prediction models to identify mitigation strategies for reducing the overall CH4 emissions. A synthesis of the available literature suggests that the mechanistic models are superior to empirical models in accurately predicting the CH4 emission from dairy farms. The latest development in prediction model is the integrated farm system model which is a process-based whole-farm simulation technique. Several techniques are used to quantify enteric CH4 emissions starting from whole animal chambers to sulfur hexafluoride (SF6) tracer techniques. The latest technology developed to estimate CH4 more accurately is the micrometeorological mass difference technique. Because the conditions under which animals are managed vary greatly by country, CH4 emissions reduction strategies must be tailored to country-specific circumstances. Strategies that are cost effective, improve productivity, and have limited potential negative effects on livestock production hold a greater chance of being adopted by producers. It is also important to evaluate CH4 mitigation strategies in terms of the total GHG budget and to consider the economics of various strategies. Although reductions in GHG emissions from livestock industries are seen as high priorities, strategies for reducing emissions should not reduce the economic viability of enterprises.

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

2011-01-01

51

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

Microsoft Academic Search

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

Robin Matthews; Reiner Wassmann

2003-01-01

52

METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY  

EPA Science Inventory

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

53

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

54

The Boston Methane Project: Mapping Surface Emissions to Inform Atmospheric Estimation of Urban Methane Flux  

NASA Astrophysics Data System (ADS)

Lost and unaccounted natural gas can amount to over 6% of Massachusetts' total annual greenhouse gas inventory (expressed as equivalent CO2 tonnage). An unknown portion of this loss is due to natural gas leaks in pipeline distribution systems. The objective of the Boston Methane Project is to estimate the overall leak rate from natural gas systems in metropolitan Boston, and to compare this flux with fluxes from the other primary methane emissions sources. Companion talks at this meeting describe the atmospheric measurement and modeling framework, and chemical and isotopic tracers that can partition total atmospheric methane flux into natural gas and non-natural gas components. This talk focuses on estimation of surface emissions that inform the atmospheric modeling and partitioning. These surface emissions include over 3,300 pipeline natural gas leaks in Boston. For the state of Massachusetts as a whole, the amount of natural gas reported as lost and unaccounted for by utility companies was greater than estimated landfill emissions by an order of magnitude. Moreover, these landfill emissions were overwhelmingly located outside of metro Boston, while gas leaks are concentrated in exactly the opposite pattern, increasing from suburban Boston toward the urban core. Work is in progress to estimate spatial distribution of methane emissions from wetlands and sewer systems. We conclude with a description of how these spatial data sets will be combined and represented for application in atmospheric modeling.

Phillips, N.; Crosson, E.; Down, A.; Hutyra, L.; Jackson, R. B.; McKain, K.; Rella, C.; Raciti, S. M.; Wofsy, S. C.

2012-12-01

55

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 ...

56

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

57

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

58

ESTIMATE OF GLOBAL METHANE EMISSIONS FROM LANDFILLS AND OPEN DUMPS  

EPA Science Inventory

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

59

Ecological controls on methane emissions from a northern peatland complex in the zone of discontinuous permafrost, Manitoba, Canada  

Microsoft Academic Search

The goals of this study were to: (1) measure methane (CHâ) emissions from peatland soils, (2) improve process models of peatland-atmospheric methane exchange by identifying environmental controls on methane emission, and (3) provide a method of extending CHâ emissions data from the laboratory to the landscape scale by determining the relationships between plant associations and CHâ flux. Sites representing a

Jill L. Bubier; Tim R. Moore; Lianne Bellisario; Neil T. Comer; Patrick M. Crill

1995-01-01

60

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

61

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

62

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

63

Methane emission from Western Siberia derived from the integral methane balance in the troposphere for 2001 -2011  

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 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.

Bogomolov, Vasiliy; Stepanenko, Victor; Okladnikov, Igor; Titov, Alexander

2014-05-01

64

Carbon dioxide emissions in a methane economy  

Microsoft Academic Search

Increasing reliance on natural gas (methane) to meet global energy demands holds implications for atmospheric CO2 concentrations. Analysis of these implications is presented, based on a logistic substitution model viewing energy technologies like biological species invading an econiche and substituting in case of superiority for existing species. This model suggests gas will become the dominant energy source and remain so

Jesse H. Ausubel; Arnulf Grübler; Nebojsa Nakicenovic

1988-01-01

65

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

66

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

Microsoft Academic Search

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

Gunnar Börjesson; Bo H. Svensson

1997-01-01

67

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

68

The feasibility of estimating New Zealand s methane emission using satellite data  

NASA Astrophysics Data System (ADS)

A preliminary retrieval algorithm has been developed for deriving methane sources from satellite measurements of mean tropospheric mixing ratio. A detailed meterological model of the New Zealand region (the New Zealand Limited Area Model) has been used to simulate the methane field in the region for assumed source distributions. This `forward model' has been coupled with an optimal estimation inverse model to form the methane source retrieval algorithm. We calculate, first, the sensitivity of the mixing ratio to the emission (measurement weighting functions), second, we simulate retrievals for assumed methane sources, and third, we calculate the sensitivity of the retrieved emission to the assumed emission (measurement averaging kernels). The last two require assumptions about the uncertainty in the satellite measurements and the a priori used in their retrieval of the CH4 column. We use the results to assess the practicality of characterizing New Zealand's methane emission from satellites.

Connor, B.; Struthers, H.; Uddstrom, M.; Lowe, D.; Wood, S.; Andrews, P.; Rodgers, C.

69

The importance of overturns for annual methane emissions from lakes  

NASA Astrophysics Data System (ADS)

The dynamics of dissolved methane were measured over a whole year in a small, dimictic lake, which develops an anoxic hypolimnion during summer stratification. We analyze and compare the diffusive methane fluxes from different time periods: the stratified period in summer, the autumn overturn, the winter mixing period, and the period from spring to summer stratification. Changes in the budget of dissolved methane indicate that anoxic conditions in the hypolimnion and overturn periods are key factors for the overall annual methane emissions from lakes. During autumn overturn, most of the stored methane was emitted to the atmosphere, which supports the assumption made in the global estimates and suggest that the oxidation of methane during overturn may differ between lakes. Changes in the amount of methane efflux during overturns may be an important aspect to consider in the assessment of methane emission estimates from lakes on a global scale.

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

2014-05-01

70

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

71

Indian methane and nitrous oxide emissions and mitigation flexibility  

NASA Astrophysics Data System (ADS)

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

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

72

Methane emissions from floodplains in the Amazon Basin: towards a process-based model for global applications  

NASA Astrophysics Data System (ADS)

Tropical wetlands are estimated to represent about 50% of the natural wetland emissions and explain a large fraction of the observed CH4 variability on time scales ranging from glacial-interglacial cycles to the currently observed year-to-year variability. Despite their importance, however, tropical wetlands are poorly represented in global models aiming to predict global CH4 emissions. This study documents the first regional-scale, process-based model of CH4 emissions from tropical floodplains. The LPX-Bern Dynamic Global Vegetation Model (LPX hereafter) was modified to represent floodplain hydrology, vegetation and associated CH4 emissions. The extent of tropical floodplains was prescribed using output from the spatially-explicit hydrology model PCR-GLOBWB. We introduced new Plant Functional Types (PFTs) that explicitly represent floodplain vegetation. The PFT parameterizations were evaluated against available remote sensing datasets (GLC2000 land cover and MODIS Net Primary Productivity). Simulated CH4 flux densities were evaluated against field observations and regional flux inventories. Simulated CH4 emissions at Amazon Basin scale were compared to model simulations performed in the WETCHIMP intercomparison project. We found that LPX simulated CH4 flux densities are in reasonable agreement with observations at the field scale but with a~tendency to overestimate the flux observed at specific sites. In addition, the model did not reproduce between-site variations or between-year variations within a site. Unfortunately, site informations are too limited to attest or disprove some model features. At the Amazon Basin scale, our results underline the large uncertainty in the magnitude of wetland CH4 emissions. In particular, uncertainties in floodplain extent (i.e., difference between GLC2000 and PCR-GLOBWB output) modulate the simulated emissions by a factor of about 2. Our best estimates, using PCR-GLOBWB in combination with GLC2000, lead to simulated Amazon-integrated emissions of 44.4 ± 4.8 Tg yr-1. Additionally, the LPX emissions are highly sensitive to vegetation distribution. Two simulations with the same mean PFT cover, but different spatial distributions of grasslands within the basin modulated emissions by about 20%. Correcting the LPX simulated NPP using MODIS reduces the Amazon emissions by 11.3%. Finally, due to an intrinsic limitation of LPX to account for seasonality in floodplain extent, the model failed to reproduce the seasonality in CH4 emissions. The Inter Annual Variability (IAV) of the emissions increases by 90% if the IAV in floodplain extent is account for, but still remains lower than in most of WETCHIMP models. While our model includes more mechanisms specific to tropical floodplains, we were unable to reduce the uncertainty in the magnitude of wetland CH4 emissions of the Amazon Basin. Our results stress the need for more research to constrain floodplain CH4 emissions and their temporal variability.

Ringeval, B.; Houweling, S.; van Bodegom, P. M.; Spahni, R.; van Beek, R.; Joos, F.; Röckmann, T.

2013-10-01

73

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

NASA Astrophysics Data System (ADS)

Natural methane hydrate has been scientifically studied as a carbon reservoir globally. However, in Japan, the potential for energy resource has been industrially highlighted. There is less domestic oil and natural gas resources in Japan, but many potential deposition areas for methane hydrate in ocean around Japan are the reasons. Less CO2 discharge from methane compared with coal, oil and conventional natural gas when the same calorie value we get is considered as the advantage for energy resource. However, because methane hydrate distributes in shallower sediment layer in ocean floor, accidental leakage of methane may occur while we utilize methane hydrate. Methane itself has 21-times impact on the greenhouse effect, if it reaches the atmosphere. Therefore, it is necessary to estimate the behavior in the environment after the leakage, if we want to use methane hydrate as energy resource. The mass balance after leakage of methane on seafloor and in water column is numerically studied through the analyses of methane emissions from natural cold seepages and hydrothermal activities in this research. The outline structure of mass balance ecosystem model creating is introduced and some preliminary examination results from the test calculation are discussed.

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

2005-05-01

74

Measurements of Methane Emissions at Natural Gas Production Sites  

E-print Network

· Sponsors were an environmental group and nine natural gas producers ­ Environmental Defense Fund (EDFMeasurements of Methane Emissions at Natural Gas Production Sites in the United States #12;Why = 21 #12;Need for Study · Estimates of methane emissions from natural gas production , from academic

Lightsey, Glenn

75

Tropical methane emissions: A revised view from SCIAMACHY onboard ENVISAT  

Microsoft Academic Search

Methane retrievals from near-infrared spectra recorded by the SCIAMACHY instrument onboard ENVISAT hitherto suggested unexpectedly large tropical emissions. Even though recent studies confirm substantial tropical emissions, there were indications for an unresolved error in the satellite retrievals. Here we identify a retrieval error related to inaccuracies in water vapor spectroscopic parameters, causing a substantial overestimation of methane correlated with high

Christian Frankenberg; Peter Bergamaschi; André Butz; Sander Houweling; Jan Fokke Meirink; Justus Notholt; Anna Katinka Petersen; Hans Schrijver; Thorsten Warneke; Ilse Aben

2008-01-01

76

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

77

Spatial variability of methane: attributing atmospheric concentrations to emissions.  

PubMed

Atmospheric methane concentrations were quantified along transects in Switzerland, using a mobile laser spectrometer combined with a GPS, to identify their spatio-temporal patterns and their controlling factors. Based on these measurements in complex terrain dominated by agriculture, three main factors were found to be responsible for the diurnal and regional patterns of atmospheric methane: (1) magnitude and distribution of methane sources within the region, (2) efficiency of vertical exchange, and (3) local wind patterns within the complex topography. An autocorrelation analysis of measured methane concentrations showed that nighttime measurements close to the ground provide information about regional sources (up to 8.3 km), while daytime measurements only carry information about sources located up to 240 m away in the upwind fetch. Compared to daytime concentrations, nighttime methane concentrations do also better reflect emissions obtained from a spatially explicit methane emission inventory and allowed the investigation of inconsistencies in this emission inventory. PMID:24727588

Bamberger, I; Stieger, J; Buchmann, N; Eugster, W

2014-07-01

78

Atmospheric inverse estimates of methane emissions from Central California  

NASA Astrophysics Data System (ADS)

Methane mixing ratios measured at a tall tower are compared to model predictions to estimate surface emissions of CH4 in Central California for October-December 2007 using an inverse technique. Predicted CH4 mixing ratios are calculated based on spatially resolved a priori CH4 emissions and simulated atmospheric trajectories. The atmospheric trajectories, along with surface footprints, are computed using the Weather Research and Forecast (WRF) coupled to the Stochastic Time-Inverted Lagrangian Transport (STILT) model. An uncertainty analysis is performed to provide quantitative uncertainties in estimated CH4 emissions. Three inverse model estimates of CH4 emissions are reported. First, linear regressions of modeled and measured CH4 mixing ratios obtain slopes of 0.73 ± 0.11 and 1.09 ± 0.14 using California-specific and Edgar 3.2 emission maps, respectively, suggesting that actual CH4 emissions were about 37 ± 21% higher than California-specific inventory estimates. Second, a Bayesian "source" analysis suggests that livestock emissions are 63 ± 22% higher than the a priori estimates. Third, a Bayesian "region" analysis is carried out for CH4 emissions from 13 subregions, which shows that inventory CH4 emissions from the Central Valley are underestimated and uncertainties in CH4 emissions are reduced for subregions near the tower site, yielding best estimates of flux from those regions consistent with "source" analysis results. The uncertainty reductions for regions near the tower indicate that a regional network of measurements will be necessary to provide accurate estimates of surface CH4 emissions for multiple regions.

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

2009-08-01

79

LANDFILL OPERATION FOR CARBON SEQUESTRATION AND MAXIMUM METHANE EMISSION CONTROL  

SciTech Connect

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

Don Augenstein

1999-01-11

80

Tropospheric impact of methane emissions from clathrates 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 both ocean sediments and underneath permafrost regions. Clathrates are stable under high pressures and low temperatures. In a warming climate, increases in ocean temperatures could lead to dissociation of the clathrates and release of methane into the ocean and subsequently into the atmosphere. This is of particular importance in the shallow part of the Arctic Ocean, where clathrates are expected to start outgassing abruptly at depths of around 300m. Here we present a comparison of simulations from the Community Earth System Model (CESM1) for present-day conditions with and without additional methane emissions from a plausible clathrate release scenario based on a state-of-the-art ocean sediment model. The model includes a fully interactive physical ocean and a fast atmospheric chemistry mechanism that represents methane as a fully interactive tracer (with emissions rather than concentration boundary conditions), along with the main chemical reactions for methane, ozone, and nitrous oxide. The results show that such clathrate emissions increase methane concentrations spatially non-uniformly, and that increases in surface ozone concentrations are greatest in polluted regions. We also find that the interannual variability in surface methane and ozone increases. 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-570979

Bhattacharyya, S.; Cameron-Smith, P. J.; Bergmann, D.; Reagan, M. T.; Elliott, S. M.; Moridis, G. J.

2012-12-01

81

Tropospheric impact of methane emissions from clathrates 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 both ocean sediments and underneath permafrost regions. Clathrates are stable under high pressures and low temperatures. In a warming climate, increases in ocean temperatures could lead to dissociation of the clathrates and release methane into the ocean and subsequently the atmosphere. This is of particular importance in the shallow parts of the Arctic Ocean, since clathrates are expected to start outgassing abruptly at depths of around 300 m. In this paper, we present a comparison of simulations from the Community Earth System Model (CESM1) for present-day conditions with and without additional methane emissions from a plausible clathrate release scenario based on a state-of-the-art ocean sediment model. The CESM model includes a fully interactive physical ocean and we added a fast atmospheric chemistry mechanism that represents methane as a fully interactive tracer (with emissions rather than concentration boundary conditions) along with the main chemical reactions for methane, ozone, and nitrous oxide. The results show that such Arctic clathrate emissions increase methane concentrations non-uniformly, and that increases in surface ozone concentrations are greatest in polluted regions. We also find that the interannual variability in surface methane and ozone increases.

Bhattacharyya, S.; Cameron-Smith, P.; Bergmann, D.; Reagan, M.; Elliott, S.; Moridis, G.

2012-10-01

82

Methane Emission through Trees in Temperate and Tropical Wetlands  

NASA Astrophysics Data System (ADS)

Methane produced in wetland soil generally is thought to be emitted by a combination of three key processes: 1) diffusion through water-filled pores, 2) abrupt release of bubbles (ebullition), and 3) via internal spaces within the stems of herbaceous plants adapted to live in waterlogged soils. The capacity for trees to mediate methane emissions has received limited attention despite mesocosm studies of seedlings and saplings demonstrating that wetland trees have a significant capacity to transport soil-produced methane to the atmosphere. Notably ~60% of global wetlands are forested. We present in situ measurements of methane flux from a temperate carr (swamp) composed of alder (Alnus glutinosa) and birch (Betula pubescens) situated in the United Kingdom and a tropical forested peat swamp located in Borneo. The in situ data are complemented by a mesocosm experiment in which methane emissions were measured from alder saplings subjected to two water-regime treatments. In both the in situ and mesocosm studies, emissions from trees are compared to methane flux from the ground surface, the latter occurring via pore water diffusion, ebullition or via the aerenchyma of herbaceous plants. We show that tree stem emissions are controlled by a number of factors including tree species, soil pore-water concentration and stem lenticel density. Our results demonstrate that the omission of tree-mediated methane fluxes from measurement campaigns conducted in forested wetland can significantly underestimate the total ecosystem flux of methane.

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

2012-12-01

83

Methane emissions from Earth’s degassing: Implications for Mars  

NASA Astrophysics Data System (ADS)

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

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

2011-02-01

84

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...

85

Estimating Methane Emissions from Central California  

NASA Astrophysics Data System (ADS)

A three-month time series of continuous CH4 mixing ratio measurements obtained from a tall-tower are applied in an inverse model to estimate regional surface emissions of CH4 in Central California. Simulated CH4 mixing ratios are calculated based on spatially resolved a priori CH4 emission estimates and simulated atmospheric transport. Atmospheric transport and surface influences (footprints) are computed using the Stochastic Time-Inverted Lagrangian Transport (STILT) model driven by customized output from the Weather Research and Forecasting (WRF) model. An uncertainty analysis is performed that propagates measurement and model errors through the inverse model to provide quantitative uncertainties in the estimated CH4 emissions. WRF-STILT predictions of daytime planetary boundary layer (PBL) heights are found to be over-estimated by a factor of 1.33 ± 0.13 (1s) through comparison with PBL heights estimated from a wind profiler located near the tower site for October, 2007. The inverse model estimates of CH4 emissions are performed in three ways. First, geometric linear regressions of modeled and measured CH4 mixing ratios obtains slopes of 0.95 ± 0.14 and 1.12 ± 0.12 for the October and Oct.-Dec., 2007 periods respectively, suggesting that total a priori CH4 emissions estimates are consistent with the atmospheric measurements and the transport model. Second, a Baysian inverse analysis of the Oct.-Dec., 2007 period obtains posterior scaling factors for CH4 suggesting that landfills and crop agriculuture are lower and livestock and petroleum emissions are higher than a priori estimates respectively. Third, a Baysian analysis of uncertainty, using 13 spatial sub-regions as basis functions, shows that the CH4 measurements significantly reduce posterior uncertainties in CH4 emissions relative the a priori assumptions for only the three sub-regions nearest the tower site. This suggests that a regional network of measurement sites will be necessary to provide high-accuracy retrievals of surface CH4 emissions for multiple regions comprising California's CH4 emissions.

Zhao, C.; Fischer, M. L.; Andrews, A. E.; Eluszkiewicz, J.; MacDonald, C. P.; Nehrkorn, T.; Hirsch, A. I.

2008-12-01

86

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

87

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.; Stern, David I.

1998-01-01

88

A multitower measurement network estimate of California's methane emissions  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

89

Environmental factors controlling methane emissions for peatlands in Northern Minnesota  

SciTech Connect

Controls on methane emission from peatlands in northern Minnesota were investigated by correlation to environmental variables and by field manipulations. From September 1988 through September 1990, methane flux measurements were made at weekly to monthly intervals at six sites in the Marcell Experimental Forest, northern Minnesota (two open bog sites, two forested bog sites, a poor fen, and a fen lagg). Flux was related to water table position and peat temperature with simple correlations at individual sites and multiple regression on all sites together. The effect of water table was also investigated experimentally in {open_quotes}bog corrals{close_quotes} (open-ended metal enclosures set in the peat) in which water table was artificially raised to the surface in the driest peatland. Temperature largely controlled variation in flux within individual ecosystems at Marcell, but hydrology distinguished between-site variation. Water table position, peat temperature, and degree of peat humification explained 91% of the variance in log CH{sub 4} flux, predicted annual methane emission from individual wetlands successfully, and predicted the change in flux due to the water table manipulation. Raising the water table in the bog corrals by an average of 6 cm in autumn 1989 and 10 cm in summer 1990 increased emission by 2.5x and 2.2x, respectively. Just as expanding the scale of investigation from a single habitat in a wetland to several wetlands necessitates incorporation of additional variables to explain flux (water table, peat characteristics), modeling flux from several wetland regions, if possible, will require the addition of climate parameters. 30 refs., 8 figs., 21 tabs.

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

1993-06-20

90

Methane emission by bubbling from Gatun Lake, Panama  

NASA Technical Reports Server (NTRS)

We studied methane emission by bubbling from Gatun Lake, Panama, at water depths of less than 1 m to about 10 m. Gas bubbles were collected in floating traps deployed during 12- to 60-hour observation periods. Comparison of floating traps and floating chambers showed that about 98% of methane emission occurred by bubbling and only 2% occurred by diffusion. Average methane concentration of bubbles at our sites varied from 67% to 77%. Methane emission by bubbling occurred episodically, with greatest rates primarily between the hours of 0800 and 1400 LT. Events appear to be triggered by wind. The flux of methane associated with bubbling was strongly anticorrelated with water depth. Seasonal changes in water depth caused seasonal variation of methane emission. Bubble methane fluxes through the lake surface into the atmosphere measured during 24-hour intervals were least (10-200 mg/m2/d) at deeper sites (greater than 7 m) and greatest (300-2000 mg/m2/d) at shallow sites (less than 2 m).

Keller, Michael; Stallard, Robert F.

1994-01-01

91

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

92

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 inte...

93

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

94

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

95

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

96

Influence of rumen protozoa on methane emission in ruminants: a meta-analysis approach.  

PubMed

A meta-analysis was conducted to evaluate the effects of protozoa concentration on methane emission from ruminants. A database was built from 59 publications reporting data from 76 in vivo experiments. The experiments included in the database recorded methane production and rumen protozoa concentration measured on the same groups of animals. Quantitative data such as diet chemical composition, rumen fermentation and microbial parameters, and qualitative information such as methane mitigation strategies were also collected. In the database, 31% of the experiments reported a concomitant reduction of both protozoa concentration and methane emission (g/kg dry matter intake). Nearly all of these experiments tested lipids as methane mitigation strategies. By contrast, 21% of the experiments reported a variation in methane emission without changes in protozoa numbers, indicating that methanogenesis is also regulated by other mechanisms not involving protozoa. Experiments that used chemical compounds as an antimethanogenic treatment belonged to this group. The relationship between methane emission and protozoa concentration was studied with a variance-covariance model, with experiment as a fixed effect. The experiments included in the analysis had a within-experiment variation of protozoa concentration higher than 5.3 log10 cells/ml corresponding to the average s.e.m. of the database for this variable. To detect potential interfering factors for the relationship, the influence of several qualitative and quantitative secondary factors was tested. This meta-analysis showed a significant linear relationship between methane emission and protozoa concentration: methane (g/kg dry matter intake)=-30.7+8.14×protozoa (log10 cells/ml) with 28 experiments (91 treatments), residual mean square error=1.94 and adjusted R 2=0.90. The proportion of butyrate in the rumen positively influenced the least square means of this relationship. PMID:25075950

Guyader, J; Eugène, M; Nozière, P; Morgavi, D P; Doreau, M; Martin, C

2014-11-01

97

An approach for measuring methane emissions from whole farms.  

PubMed

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

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

2006-01-01

98

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

99

Methane emissions from fen, bog and swamp peatlands in Quebec  

Microsoft Academic Search

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

T. R. Moore; R. Knowles

1990-01-01

100

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

101

High-resolution inversion of methane emissions in North America using satellite observations (SCIAMACHY, TES, GOSAT)  

NASA Astrophysics Data System (ADS)

Methane emissions from North America are poorly known and potentially subject to rapid anthropogenic and natural changes. Satellite retrievals of methane columns from SCIAMACHY, TES, and GOSAT offer a unique resource for constraining and monitoring methane emissions using adjoint inverse modeling. We validate these methane retrievals using INTEX-A, HIPPO and NOAA/GMD aircraft observations. We also evaluate the consistency between the different satellite instruments with respect to the GEOS-Chem chemical transport model (CTM) as an intercomparison platform. We derive fine-scale constraints on methane sources through a four-dimensional variational (4D-VAR) inversion using the adjoint of GEOS-Chem with 1/2o × 2/3o (~50 × 50 km2) horizontal resolution over North America. Boundary conditions over the oceans are optimized as part of the inversion, thus preventing any global model bias from impacting the North American GEOS-Chem domain. In situ observations from aircraft campaigns and ground-based networks are used to evaluate the inversion results. We find that current inventories overestimate emissions from natural wetlands and underestimate emissions from natural gas production and enteric fermentation. Our results provide guidance to the US EPA for improving its national emission inventories.

Wecht, K.; Jacob, D. J.; Payer, M.; Henze, D. K.; Worden, J.; Payne, V.; Frankenberg, C.; Bowman, K. W.; Boesch, H.

2012-12-01

102

Predicting methane emission from bryophyte distribution in northern Canadian peatlands  

SciTech Connect

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

Bubier, J.L.; Moore, T.R. [McGill Univ., Quebec (Canada); Juggins, S. [Univ. College London (United Kingdom)

1995-04-01

103

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

104

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.

105

Climate Feedback on Methane Emissions From Terrestrial Ecosystems  

NASA Astrophysics Data System (ADS)

Terrestrial ecosystems are one of the important components of the climate system that are bound to change and cause feedbacks with global warming. One major mechanism of this feedback is the response of biological processes, mostly bacteria, that produce or consume greenhouse gases such as carbon dioxide (CO2) and methane (CH4). Here we are concerned with the emissions of CH4 which is considered the most important non-CO2 greenhouse gas because it has more than doubled during the last century and is about 20 times more potent per kilogram once emitted to the atmosphere. Methane is produced by anaerobic methanogens in wetland soils and rice paddies, and is consumed by methanotrophic bacteria in aerobic and upland soils. Together these sources account for about 40-60% of global methane emissions. Properly accounting for the feedback of CH4 emissions with temperature in Earth Systems Models (ESMs) remains an open challenge in part due to the lack of experimental data. Reported Q10 values (factor by which reaction rate increases for a 10°C rise in temperature) of CH4 flux from wetlands and rice agriculture vary over an order of magnitude for reasons that are not well known contributing to this uncertainty. We report here a suite of experimental measurements to determine the Q10 of CH4 flux from rice agriculture and to understand how it depends on the temperature responses of its underlying processes. Since processes may have different Q10 values it is essential that these are properly represented in ESMs. We grew rice plants in temperature-controlled mesocosms at 20, 24, 28 and 32°C over two seasons (years 2009 - 2010) and measured flux, production and oxidation rates, at regular intervals using static chambers, soil core incubations, and carbon isotopes (?13C-CH4), respectively. In addition we used qPCR techniques to measure methyl coenzyme M reductase (mcrA) and particulate methane monooxygenase (pmoA) genes from mesocosm soil cores to establish the temperature response of methanogen and methanotroph populations. We used a simple box model to relate the flux Q10 with the Q10 values for production, oxidation, and plant-mediated transport. Among other results, we found that flux Q10 values varied between 1 and 20 on a day-to-day basis throughout the growing season, with the largest values occurring at the beginning of the season when fluxes were low. This variation could in part be explained by differences in rates of plant-mediated transport brought about by the different plant growth rates at different temperatures. The seasonally-averaged flux Q10 was ~2, which was lower than the average production Q10 of ~3, indicating that the temperature response of CH4 oxidation in part offsets the increased emissions expected from enhanced production at higher temperatures. This has important implications for how CH4 emissions from terrestrial ecosystems will respond to global warming.

Butenhoff, C. L.; Sithole, A.; Khalil, A. K.; Rice, A. L.; Shearer, M. J.

2012-12-01

106

Nitrous oxide and methane emissions from aero engines  

SciTech Connect

The emissions of nitrous oxide and methane from a Pratt & Whitney Canada PW 305 and a Rolls Royce RB 211 jet engine were measured under various flight conditions either on a ground level stationary test stand or in altitude test cells by using an off-line sampling technique. The concentrations of the gases were determined by long path infrared diode laser absorption spectroscopy in the laboratory. The calculated emission indices indicate that, at present, air traffic does not contribute significantly to the global budgets of methane and nitrous oxide.

Wiesen, P.; Kleffmann, J.; Kurtenbach, R.; Becker, K.H. [Univ. Wuppertal, Wuppertal (Germany)] [Univ. Wuppertal, Wuppertal (Germany)

1994-09-01

107

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

PubMed

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

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

2013-12-01

108

Methane emissions from wetlands, southern Hudson Bay lowland  

SciTech Connect

This article describes the monitoring of methane emissions at 39 wetland ecosystem sites in the Hudson Bay Lowland. The study sites were located along a transect from the James Bay Coast at the tip of the Hudson Bay to Kinosheo Lake near Moosonee, Ontario, Canada. Measurements of methane flux were made using a static chamber technique. Weak statistical relationships were noted at each site between the daily methane flux rate, ground-water depth, and peat temperatures. On a regional scale, a significant correlation was noted over the complete range of sites between the seasonal methane flux and the average position of the ground-water table. Other observations are also described. 51 refs., 7 figs., 4 tabs.

Moore, T.R.; Heyes, A. [McGill Univ., Montreal (Canada)] [McGill Univ., Montreal (Canada); Roulet, N.T. [York Univ., Ontario (Canada)] [York Univ., Ontario (Canada)

1994-01-20

109

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

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

110

Indian oil company joins efforts to reduce methane emissions  

NASA Astrophysics Data System (ADS)

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

Kumar, Mohi

111

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

PubMed

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

Ishii, Kazuei; Furuichi, Toru

2013-09-01

112

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...

113

Methane Emissions from Point and Area Sources in California  

NASA Astrophysics Data System (ADS)

Airborne measurements of methane (CH4), carbon monoxide (CO), sulfur dioxide, ammonia, and nitric oxides were made aboard the NOAA WP-3D during May and June 2010, during the CalNex (Research at the Nexus of Air Quality and Climate Change) field campaign based out of Ontario, California. Emission ratios of CH4 to these other trace gas species are calculated from observations downwind of point sources and compared to national emissions inventories. Further, background urban ratios of CH4 to CO are established, and enhancements from known area CH4 sources, such as rice paddies and cattle ranches, are analyzed. Finally, significant methane emissions from point sources not in emissions inventories are examined.

Peischl, J.; Ryerson, T. B.; Frost, G. J.; Holloway, J. S.; McKeen, S. A.; Neuman, J.; Nowak, J. B.; Pollack, I. B.; Roberts, J. M.; Trainer, M.; Parrish, D. D.

2010-12-01

114

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

115

Methane emissions to the atmosphere through aquatic plants  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

116

Nitrous oxide and methane emissions from aero engines  

Microsoft Academic Search

The emissions of nitrous oxide and methane from a Pratt & Whitney Canada PW 305 and a Rolls Royce RB 211 jet engine were measured under various flight conditions either on a ground level stationary test stand or in altitude test cells by using an off-line sampling technique. The concentrations of the gases were determined by long path infrared diode

P. Wiesen; J. Kleffmann; R. Kurtenbach; K. H. Becker

1994-01-01

117

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

118

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

119

Annual cycle of methane emission from a subarctic peatland  

Microsoft Academic Search

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

Marcin Jackowicz-Korczy?ski; Torben R. Christensen; Kristina Bäckstrand; Patrick Crill; Thomas Friborg; Mikhail Mastepanov; Lena Ström

2010-01-01

120

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

121

Measurement and prediction of enteric methane emission  

Microsoft Academic Search

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

Veerasamy Sejian; Rattan Lal; Jeffrey Lakritz; Thaddeus Ezeji

2011-01-01

122

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

123

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

124

Hydrogen sulphide and methane emissions on the central Namibian shelf  

NASA Astrophysics Data System (ADS)

Hydrogen sulphide occurs frequently in the waters of the inner shelf coastal upwelling area off central Namibia. The area affected coincides with hatching grounds of commercially important pelagic fish, whose recruitment may be severely affected by recurring toxic sulphidic episodes. Both episodic biogenic methane gas-driven advective and molecular diffusive flux of hydrogen sulphide have been implicated as transport mechanisms from the underlying organic-matter-rich diatomaceous mud. To test hypotheses on the controls of hydrogen sulphide transport from the sediments on the inner Namibian shelf, water column and sediment data were acquired from four stations between 27 and 72 m water depth over a 3 year long period. On 14 cruises, temperature, salinity, dissolved oxygen, nitrate, methane, and total dissolved sulphide were determined from water column samples, and pore water dissolved methane, total dissolved sulphide, biomass of benthic sulphide-oxidising bacteria Beggiatoa and Thiomargarita, and bacterial sulphate reduction rates were determined from sediment cores. Superimposed on a trend of synchronous changes in water column oxygen and nutrient concentrations controlled by regional hydrographic conditions were asynchronous small-scale variations at the in-shore stations that attest to localized controls on water column chemistry. Small temporal variations in sulphate reduction rates determined with 35S-labeled sulphate do not support the interpretation that variable emissions of sulphide and methane from sediments are driven by temporal changes in the degradation rates of freshly deposited organic matter. The large temporal changes in the concentrations of hydrogen sulphide and the co-occurrence of pore water sulphate and methane support an interpretation of episodic advection of methane and hydrogen sulphide from deeper sediment depths - possibly due to gas bubble transport. Effective fluxes of hydrogen sulphide and methane to the water column, and methane and sulphide concentrations in the bottom waters were decoupled, likely due to the activity of sulphide-oxidising bacteria. While the causal mechanism for the episodic fluctuations in methane and dissolved sulphide concentrations remains unclear, this data set points to the importance of alternating advective and diffusive transport of methane and hydrogen sulphide to the water column.

Brüchert, Volker; Currie, Bronwen; Peard, Kathleen R.

2009-12-01

125

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

126

High rates of methane emissions from south taiga wetland ponds.  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

127

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

128

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

129

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

Microsoft Academic Search

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

Susanne Liebner; Josef Zeyer; Christian Knoblauch

2010-01-01

130

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

NASA Astrophysics Data System (ADS)

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

Pikaleva, A.

2012-04-01

131

Methane oxidation and methanotrophs: resistance and resilience against model perturbations  

NASA Astrophysics Data System (ADS)

Biodiversity is claimed to be essential for ecosystem functioning. However, most experiments on biodiversity and ecosystem functioning (BEF) have been made on higher plants, while only few studies have dealt with microbial communities. Overall microbial diversity may be very high, and general functions like aerobic carbon mineralization are assumed to be supported by highly redundant communities. Therefore, we focused on methane oxidation, a microbial process of global importance mitigating methane emissions from wetland, rice fields, and landfills. We used a rice paddy as our model system, where >90% of potentially emitted methane may be oxidized in the oxic surface layer. This community is presumed to consist of 10-20 taxa more or less equivalent to species. We focused on the ability of methanotrophs to recover from a disturbance causing a significant die-off of all microbial populations. This was simulated by mixing native with sterile soil in two ratios (1:4 and 1:40). Microcosms were incubated and the temporal shift of the methanotrophic communities was followed by pmoA-based Terminal Restriction Length Polymorphism (T-RFLP), qPCR, and a pmoA-based diagnostic microarray. We consistently observed distinctive temporal shifts between Methylocystaceaea and Methylococcacea, a rapid population growth leading to the same or even higher cell numbers as in microcosms made from native soil alone, but no effect on the amount of methane oxidized. The ratio of different methanotrophs changed with treatment, while the number of taxa stayed nearly the same. Overall, methanotrophs showed a remarkable resilience compensating for die-offs. It has to be noted, however, that our experiment focused on methanotrophs adapted to and living at high methane fluxes. Quite different, methanotrophs living in upland soils do not mitigate methane emissions, but are the only biological sink to atmospheric methane. These microbes are severely substrate limited, and will be much more susceptible to perturbations.

Ho, A.; Frenzel, P.

2009-04-01

132

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

133

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

134

Possible reasons of the enhanced methane emission from the permafrost part of Russia  

NASA Astrophysics Data System (ADS)

Our last study was focused on researching into the methane emission from Russian frozen wetlands and evaluation of this effect on global radiative forcing. Results for the mid-21st century indicate that the annual emission of methane from Russian permafrost region may increase by 6-8 Mt y-1. Resulting from such an increase additional radiative forcing may raise the global mean of annual air temperature by 0.012 oC. In this research we developed a conceptual model explaining enhanced methane emission at the shelf of the East Siberian Arctic Seas (ESAS). Although observations are infrequent in time and space, they clearly indicate the presence of strong sources of methane at selected locations on the ESAS-shelf. Natalia Shakhova with co-authors hypothesized in numerous publications that enhanced methane emissions are attributed to recent thawing of sub-aquatic permafrost at ESAS, and predicted catastrophic environmental changes in the nearest future, which was called the "methane bomb" scenario. We don't share this point of view. According their results, the annual methane emission from ESAS is 7,9 Mt. But if we refer to our research of emission from wetlands, we can see that this amount is not so catastrophic for global temperature. So we focused on the concept indicating that observed enhanced fluxes are not related to recent changes in the subaquatic permafrost but are rather attributed to other mechanisms, which are yet to be studied. In our primarily opinion those mechanisms are associated with the geological history of ESAS. The ultimate goal is to combine them into conceptual model that explains methane observations at ESAS in the context of the past, present, and future environmental changes. We shall explore the hypothesis which suggests that observed methane venting is mostly bound to unfrozen bottom sediments surrounding fault zones and paleo river beds, while elsewhere on the inner ESAS shelf sediments remain frozen and impermeable for gases since the last glacial maximum. We checked this hypothesis by collecting published geological and paleo data, including those on high resolution batimetry, analysing of genesis of the bottom sediment samples, and constructing the digital high resolution map of the fault zones and paleo river and lake beds at ESAS, which is compared with locations of the hydrographic stations where enhanced methane fluxes have been observed. Our hypothesis suggests that the methane emission at ESAS is controlled by geological factors rather than by recent changes in permafrost. This study made a step towards bridging the gap between the two competing positions of Shakhova's team and our group, and in the follow-up discussion we agreed that the analysis of the geological history and paleo data from bottom sediments is a key to understanding the mechanisms of methane venting at ESAS.

Reneva, Svetlana; Strelchenko, Julia; Anisimov, Oleg; Kokorev, Vasily

2013-04-01

135

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

136

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

137

Effect of wetland types on methane emission from Russian frozen wetlands under conditions of climate change  

NASA Astrophysics Data System (ADS)

Natural wetlands are responsible for the majority of global methane emissions from natural sources, accounting for about 175 Mt of methane per year (IPCC 2007). The climate change will have significant impact on permafrost, leading to thawing of the frozen wetlands and release of carbon to the atmosphere. The potential feedback to climate system depends on both the soil pool size and the rate of release to the atmosphere. Earlier studies suggest that Northern peat deposits store about 500 Pg C, of which about 278 PgC is located in permafrost regions. More recent data indicate that the circumpolar permafrost region may contain 1024 Pg of soil C in the surface 0-3 m depth, and additional 648 Pg C in deeper layers up to 25 m thick. This carbon may become available for decomposition under warmer climatic conditions. In this study we focus on permafrost wetlands because they favour the production of methane in the anaerobic carbon-rich soil layer. 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. Unlike it was a case with the preceding study, we explicitly take into account the difference in methane production rates in different wetland types. To accomplish this goal, we constructed the map of different wetland provinces, as defined by Katz classification and overlaid it by the digital geographically referenced contours of Russian wetlands from 1:1,000,000-scale topographic maps. As a result, we calculated the total area and the fraction of land each wetland type occupies in the nodes of 0.5 by 0.5 degree lat/long regular grid spanning permafrost regions. These data were combined with the results from predictive permafrost model forced by CCC, HadCM3, GFDL, NCAR climatic projections for 2050 under B1 emission scenario. 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. The results indicated 8-10 Pg per year potential increase of methane emission from the thawing frozen wetlands in Russian permafrost region by mid-21st century. Although the overall impact of such additional emission on global climate is small, at regional level it may shift the balance between the sinks and sources of carbon.

Reneva, S.

2010-09-01

138

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

139

Mitigation options for methane emissions from rice fields in the Philippines  

SciTech Connect

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

Lantin, R.S.; Buendia, L.V.; Wassmann, R. [International Rice Research Institute, Laguna (Philippines)] [and others

1996-12-31

140

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

141

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

Microsoft Academic Search

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

PETER H. V ERBURG

2001-01-01

142

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

143

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

144

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

145

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

146

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

147

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

148

Measurements of methane emission from a temperate wetland by the eddy covariance method  

NASA Astrophysics Data System (ADS)

Methane emission from a wetland was measured with the eddy covariance system. The location of the system allowed observation of methane efflux from areas that were covered by different vegetation types. The data presented in this paper were collected in the period between the13th of June and the 31st of August 2012. During the warmest months of the summer, there was no strong correlation between methane emissions and either the water table depth or peat temperature. The presence of reed and cattail contributed to a pronounced diurnal pattern of the flux and lower methane emission, while areas covered by sedges emitted higher amounts more with no clear diurnal pattern.

Kowalska, N.; Chojnicki, B. H.; Rinne, J.; Haapanala, S.; Siedlecki, P.; Urbaniak, M.; Juszczak, R.; Olejnik, J.

2013-09-01

149

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

150

Development and application of a detailed inventory framework for estimating nitrous oxide and methane emissions from agriculture  

Microsoft Academic Search

A detailed inventory framework was developed to estimate nitrous oxide (N2O) and methane (CH4) emissions from UK agriculture using the IPCC approach. The inventory framework model was illustrated by combining relevant emission factors with agricultural census data for England, Wales, Scotland and Northern Ireland for the year 2000 to derive country-specific emission estimates which were summed to derive the UK total.

Junye Wang; Laura M. Cardenas; Tom H. Misselbrook; Sarah Gilhespy

2011-01-01

151

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

152

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

153

Sediment Trapping by Dams Creates Methane Emission Hot Spots Andreas Maeck,*,|  

E-print Network

Sediment Trapping by Dams Creates Methane Emission Hot Spots Andreas Maeck,*,| Tonya Del. Direct comparison of riverine and reservoir reaches, where sedimentation in the latter is increased due to trapping by dams, revealed that the reservoir reaches are the major source of methane emissions (0.23 mmol

Wehrli, Bernhard

154

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

E-print Network

clear. We quantified internal cycling and methane emissions in three lakes during summer stratification stratification, and 14­76% considering the release of CH4 stored in deep water layers during lake circulationFates of methane from different lake habitats: Connecting whole-lake budgets and CH4 emissions

Pace, Michael L.

155

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...

156

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

157

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...

158

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

159

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

160

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

161

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

162

Detection of marine methane emissions with AVIRIS band ratios  

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

163

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

164

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

165

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

166

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

PubMed

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

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

2014-09-01

167

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

168

Status of worldwide coal mine methane emissions and use  

Microsoft Academic Search

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

Carol J Bibler; James S Marshall; Raymond C Pilcher

1998-01-01

169

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

170

Sire and liveweight affect feed intake and methane emissions of sheep confined in respiration chambers.  

PubMed

Daily methane production and feed intake were measured on 160 adult ewes, which were the progeny of 20 sires and 3 sire types (Merino, dual-purpose and terminal) from a genetically diverse flock. All animals were housed in individual pens and fed a 50/50 mix of chaffed lucerne and oaten hays at 20 g/kg liveweight (LW), with feed refusals measured for at least 10 days before the first of three 22-h measurements in respiration chambers (RC). Feed was withdrawn at 1600 h on the day before each RC test to encourage the ewes to eat the entire ration provided for them in the RC. After the first 1-day RC test, the sheep were returned to their pens for a day, then given a second 1-day RC test, followed by another day in their pens, then a third RC test. After all animals had been tested, they were ranked according to methane emissions adjusted for feed intake in the RC and on the previous day, enabling 10 low and 10 high methane animals to be chosen for repeat measurement. No variation between sires nor consistent effects of LW on feed eaten (%FE, expressed as per cent of feed offered) was evident in the 10 days before the first RC measurement. However, significant differences between sires (equivalent to an estimated heritability of 41%) were identified for %FE during the 2nd and 3rd days of RC testing (2 and 4 days after the initial RC test). The analysis of all data showed that methane emissions in the RC were related to feed intake on the day of testing and the two previous days (all P<0.0005). Before correcting for feed intake on previous days, there was some variation between sires in methane yield, equivalent to an estimated heritability of 9%. Correction for feed intake on the 2 previous days halved the residual variation, allowing other effects to be detected, including effects of LW, twins reared as singles, test batch, RC and test-day effects, but estimated sire variation fell to zero. In order to avoid potential biases, statistical models of methane emissions in the RC need to consider potential confounding factors, such as those identified as significant in this study. PMID:25404195

Robinson, D L; Goopy, J P; Donaldson, A J; Woodgate, R T; Oddy, V H; Hegarty, R S

2014-12-01

171

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

172

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

173

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

174

Baseline study of methane emission from anaerobic ponds of palm oil mill effluent treatment.  

PubMed

The world currently obtains its energy from the fossil fuels such as oil, natural gas and coal. However, the international crisis in the Middle East, rapid depletion of fossil fuel reserves as well as climate change have driven the world towards renewable energy sources which are abundant, untapped and environmentally friendly. Malaysia has abundant biomass resources generated from the agricultural industry particularly the large commodity, palm oil. This paper will focus on palm oil mill effluent (POME) as the source of renewable energy from the generation of methane and establish the current methane emission from the anaerobic treatment facility. The emission was measured from two anaerobic ponds in Felda Serting Palm Oil Mill for 52 weeks. The results showed that the methane content was between 35.0% and 70.0% and biogas flow rate ranged between 0.5 and 2.4 L/min/m(2). Total methane emission per anaerobic pond was 1043.1 kg/day. The total methane emission calculated from the two equations derived from relationships between methane emission and total carbon removal and POME discharged were comparable with field measurement. This study also revealed that anaerobic pond system is more efficient than open digesting tank system for POME treatment. Two main factors affecting the methane emission were mill activities and oil palm seasonal cropping. PMID:16125215

Yacob, Shahrakbah; Ali Hassan, Mohd; Shirai, Yoshihito; Wakisaka, Minato; Subash, Sunderaj

2006-07-31

175

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

176

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

NASA Astrophysics Data System (ADS)

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

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

1994-08-01

177

Mitigation of methane emissions from rice fields: Possible adverse effects of incorporated rice straw  

NASA Astrophysics Data System (ADS)

Increased world demand for rice production may lead to an increase in methane emission to the atmosphere and future global warming. One suggested way to reduce methane emission is to discourage the practice of incorporating previous crop residue prior to planting rice, since the residue may enhance methane emission from flooded rice fields. This concept is supported by data from a 2-year study of flooded rice fields on two different soil types in Texas. In 1990, rice stubble from 1989 was incorporated into both soils. Seasonal methane emission from a Lake Charles clay field increased from 15.9 g m-2 in 1989 to 31.0 g m-2 in 1990. In the Beaumont clay field, seasonal methane emission increased from 4.5 to 11.4 g m-2. While methane emission increased between 1989 and 1990, grain yield dropped by 2100 and 840 kg ha-1 in the Lake Charles and Beaumont fields, respectively. Visual inspection at harvest indicated that the 1990 rice yield decrease resulted from grain abortion, presumably caused by the rice cultivar's sensitivity to soil anaerobiosis. The calculated amount of organic carbon not translocated to grain was comparable to the estimated amount of organic carbon required for the increased methane emission. We hypothesize that labile carbon in straighthead susceptible rice cultivars can "leak" from roots damaged by excessively anaerobic soil and be metabolized to its equivalent in methane. These data suggest that minimizing incorporation of crop residue prior to planting can decrease methane emission from flooded rice and reduce the potential for yield loss, particularly with some cultivars and in soils with low rates of seepage and percolation.

Sass, R. L.; Fisher, F. M.; Harcombe, P. A.; Turner, F. T.

1991-09-01

178

Validation of TES methane with HIPPO aircraft observations: implications for inverse modeling of methane sources  

NASA Astrophysics Data System (ADS)

We validate satellite methane observations from the Tropospheric Emission Spectrometer (TES) with 151 aircraft vertical profiles over the Pacific from the HIAPER Pole-to-Pole Observation (HIPPO) program. We find that a collocation window of ±750 km and ±24 h does not introduce significant error in comparing TES and aircraft profiles. We validate both the TES standard product (V004) and an experimental product with two pieces of information in the vertical (V005). We determine a V004 mean bias of 65.8 ppb and random instrument error of 43.3 ppb. For V005 we determine a mean bias of 42.3 ppb and random instrument error of 26.5 ppb in the upper troposphere, and mean biases (random instrument errors) in the lower troposphere of 28.8 (28.7) and 16.9 (28.9) ppb at high and low latitudes respectively. Even when V005 cannot retrieve two pieces of information it still performs better than V004. An observation system simulation experiment (OSSE) with the GEOS-Chem chemical transport model (CTM) and its adjoint shows that TES V004 has only limited value for constraining methane sources. Our successful validation of V005 encourages its production as a standard retrieval to replace V004.

Wecht, K. J.; Jacob, D. J.; Wofsy, S. C.; Kort, E. A.; Worden, J. R.; Kulawik, S. S.; Henze, D. K.; Kopacz, M.; Payne, V. H.

2012-02-01

179

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 at determining the relationships in the system "coal-gas-water", in the context of the flooding of unexploited

Boyer, Edmond

180

Global methane emission from wetlands and its sensitivity to climate change  

Microsoft Academic Search

The concentration of atmospheric methane (CH4) exerts a strong influence on atmospheric chemistry and the global climate. Natural and cultivated wetlands (rice paddies) are important sources of CH4, and the extent and strength of these sources may increase as a result of global warming and extension of rice production. Emission of methane from wetlands is an ecosystem process, closely coupled

Mingkui Cao; Keith Gregson; Stewart Marshall

1998-01-01

181

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

Microsoft Academic Search

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

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

2008-01-01

182

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

PubMed

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

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

2014-11-01

183

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

PubMed

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

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

2014-08-19

184

Effects of decadal deposition of nitrogen and sulfur, and increased temperature, on methane emissions from a boreal peatland  

Microsoft Academic Search

Boreal peatlands represent a significant source of methane to the atmosphere. Pollutants and climate changes resulting from human activity are likely to affect the processes controlling methane emissions from these systems. This study investigated the effects of decadal deposition of nitrogen and sulfate, and increased air temperature, on methane emissions from a northern Swedish peatland during the snow-free seasons of

Tobias Eriksson; Mats G. Öquist; Mats B. Nilsson

2010-01-01

185

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

186

Seasonal variation in methane emissions from an interior Alaska thermokarst lake  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

187

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

188

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

PubMed

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

189

Study of thin biocovers (TBC) for oxidizing uncaptured methane emissions in bioreactor landfills.  

PubMed

Bioreactor landfills are designed to accelerate municipal solid waste biodegradation and stabilization; however, the uncaptured methane gas escapes to the atmosphere during their filling. This research investigates the implementation of a novel methane emission control technique that involves thin biocovers (TBC) placed as intermediate waste covers to oxidize methane without affecting the operation of bioreactor landfills. Batch incubation experiments were conducted for selecting the optimum TBC materials, capable of oxidizing methane to carbon dioxide by methanotrophic bacteria. Column experiments were performed to investigate the TBC performance under varying moisture content, compost-to-sawdust ratio, methane flow rate, and biocover thickness. Overall, the optimum TBC is comprised of a 30-cm thick bed of 0-10mass% sawdust mixed with compost, having a moisture content of 52% ww, which showed 100% CH4 oxidation efficiency over an extended period of time even at a relatively high methane inlet load of 9.4gm(-3)h(-1). PMID:17851063

Perdikea, Konstantina; Mehrotra, Anil K; Hettiaratchi, J Patrick A

2008-01-01

190

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

Microsoft Academic Search

Sulfate in acid rain is known to suppress methane (CH4) emissions from natural freshwater wetlands. Here we examine the possibility that CH4 emissions from rice agriculture may be similarly affected by acid rain, a major and increasing pollution problem in Asia. Our findings suggest that acid rain rates of SO4 2- deposition may help to reduce CH4 emissions from rice

Vincent Gauci; Nancy B. Dise; Graham Howell; Meaghan E. Jenkins

2008-01-01

191

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

Microsoft Academic Search

Sulfate in acid rain is known to suppress methane (CH4) emissions from natural freshwater wetlands. Here we examine the possibility that CH4 emissions from rice agriculture may be similarly affected by acid rain, a major and increasing pollution problem in Asia. Our findings suggest that acid rain rates of SO42? deposition may help to reduce CH4 emissions from rice agriculture.

Vincent Gauci; Nancy B. Dise; Graham Howell; Meaghan E. Jenkins

2008-01-01

192

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

Microsoft Academic Search

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

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

2000-01-01

193

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

Microsoft Academic Search

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

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

2000-01-01

194

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

195

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

196

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

197

The effect of clipping on methane emissions from Carex  

Microsoft Academic Search

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

DOROTHY KELKER; JEFFREY CHANTON

1997-01-01

198

ESTIMATING METHANE EMISSION AND OXIDATION FROM TWO TEMPORARY  

E-print Network

with a high fraction of oxidized methane (up to 80%). These results were obtained with favourable humidity oxidation efficiency (nearly 100% for a methane supply of 4 - 4.5 l/m2 /h) was measured with column tests using old municipal solid waste material (Huber-Humer & al, 2007, 2008). Another result of these studies

Paris-Sud XI, Université de

199

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

200

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

201

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

202

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

203

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

204

Trees are important conduits for emission of methane from temperate and tropical wetlands  

NASA Astrophysics Data System (ADS)

Methane produced in wetland soil generally is thought to be emitted to the atmosphere primarily via diffusion through pore water, release of gas bubbles (i.e., ebullition), and gas phase diffusion through the aerenchyma of herbaceous plants. The role of trees as a conduit for methane export from soil to the atmosphere has received limited attention despite evidence from mesocosm experiments showing that seedlings and saplings of wetland trees have a significant capacity to transport soil-produced gases. Notably ~60% of global wetlands are forested. We present in situ measurements of methane flux from a temperate carr (swamp) composed of alder (Alnus glutinosa) and birch (Betula pubescens) situated in the United Kingdom and a tropical forested peat swamp located in Borneo. The in situ data are complemented by a mesocosm experiment in which methane emissions were measured from alder saplings subjected to two water-regime treatments. In both the in situ and mesocosm studies, emissions from trees are compared to methane flux from the ground surface, the latter occurring via pore water diffusion, ebullition or the aerenchyma of herbaceous plants. We show that tree stem emissions are controlled by a number of factors including tree species, soil pore-water concentration and stem lenticel density. Our results demonstrate that the omission of tree-mediated methane fluxes from measurement campaigns conducted in forested wetland can significantly underestimate total ecosystem flux of methane.

Gauci, Vincent; Pangala, Sunitha; Gowing, David; Hornibrook, Edward

2013-04-01

205

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

206

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

207

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

208

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

209

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

210

Influence of organic matter incorporation on the methane emission from a wetland rice field  

Microsoft Academic Search

Methane (CH4) emission from Philippine rice paddies was monitored with a closed chamber technique during the 1992 dry and wet season. CH4 emissions were significantly higher in the dry season. Application of green manure stimulated CH4 emissions. In plots that received more than 11 t ha-1 of fresh green manure, CH4 emission was highest during the first half of the

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

1995-01-01

211

Influence of organic matter incorporation on the methane emission from a wetland rice field  

Microsoft Academic Search

Methane (CH4) emission from Philippine rice paddies was monitored with a closed chamber technique during the 1992 dry and wet season. CH4 emissions were significantly higher in the dry season. Application of green manure stimulated CH4 emissions. In plots that received more than 11 t ha?1 of fresh green manure, CH4 emission was highest during the first half of the

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

1995-01-01

212

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

PubMed

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

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

2010-01-01

213

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

SciTech Connect

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

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

1995-05-01

214

Reducing Open Cell Landfill Methane Emissions with a Bioactive Alternative Daily  

SciTech Connect

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

Helene Hilger; James Oliver; Jean Bogner; David Jones

2009-03-31

215

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...

216

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...

217

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

E-print Network

Environmental and physical controls on northern terrestrial methane emissions across permafrost of growing-season CH4 emissions from terrestrial ecosys- tems located across permafrost zones, including 303 sites described in 65 studies. Data on environmental and physical variables, including permafrost

Ickert-Bond, Steffi

218

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...

219

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...

220

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...

221

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...

222

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...

223

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...

224

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...

225

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...

226

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...

227

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...

228

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...

229

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...

230

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...

231

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...

232

Methane Emissions from Irrigated Rice Fields in Northern India (New Delhi)  

Microsoft Academic Search

Methane (CH4) emission fluxes from rice fields as affected by water regime, organic amendment, and rice cultivar were measured at the Indian Agricultural Research Institute, New Delhi, using manual and automatic sampling techniques of the closed chamber method. Measurements were conducted during four consecutive cropping seasons (July to October) from 1994 to 1997. Emission rates were very low (between 16

M. C. Jain; S. Kumar; R. Wassmann; S. Mitra; S. D. Singh; J. P. Singh; R. Singh; A. K. Yadav; S. Gupta

2000-01-01

233

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

234

Mapping Asian anthropogenic emissions of non-methane volatile organic compounds to multiple chemical mechanisms  

NASA Astrophysics Data System (ADS)

An accurate speciation mapping of non-methane volatile organic compounds (NMVOC) emissions has an important impact on the performance of chemical transport models (CTMs) in simulating ozone mixing ratios and secondary organic aerosols. In this work, we developed an improved speciation framework to generate model-ready anthropogenic Asian NMVOC emissions for various gas-phase chemical mechanisms commonly used in CTMs by using an explicit assignment approach and updated NMVOC profiles, based on the total NMVOC emissions in the INTEX-B Asian inventory for the year 2006. NMVOC profiles were selected and aggregated from a wide range of new measurements and the SPECIATE database. To reduce potential uncertainty from individual measurements, composite profiles were developed by grouping and averaging source profiles from the same category. The fractions of oxygenated volatile organic compounds (OVOC) were corrected during the compositing process for those profiles which used improper sampling and analyzing methods. Emissions of individual species were then lumped into species in different chemical mechanisms used in CTMs by applying mechanism-dependent species mapping tables, which overcomes the weakness of inaccurate mapping in previous studies. Gridded emissions for eight chemical mechanisms are developed at 30 min × 30 min resolution using various spatial proxies and are provided through the website: http://mic.greenresource.cn/intex-b2006. Emission estimates for individual NMVOC species differ between one and three orders of magnitude for some species when different sets of profiles are used, indicating that source profile is the most important source of uncertainties of individual species emissions. However, those differences are diminished in lumped species as a result of the lumping in the chemical mechanisms.

Li, M.; Zhang, Q.; Streets, D. G.; He, K. B.; Cheng, Y. F.; Emmons, L. K.; Huo, H.; Kang, S. C.; Lu, Z.; Shao, M.; Su, H.; Yu, X.; Zhang, Y.

2013-12-01

235

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

236

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

237

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

238

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

239

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

240

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

241

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

SciTech Connect

Methane emission rates from wetland rice fields were determined in Los Banos (Philipppines) using an automatic system that allows continuous measurements over time. Methane emission was monitored in an irrigated Aquandic Epiaqualf planted to rice cultivar IR72. Urea fertilizer was applied using four modes: (1) broadcast 10 days after transplanting, (2) broadcast at transplanting, (3) broadcast and incorporated at final harrowing, and (4) deep placement as sulfur-coated granules. The treatments were laid out in a randomized complete block design with four replicates. Measurements were done in the 1991 wet season, 1992 dry season (four treatments), and the 1992 wet season (only treatment 3). Methane emission rates from the experimental plots showed pronounced season and diel variations. The diel pattern of methane emission rates followed a consistent pattern, with highest rates observed in the early afternoon and lowest rates in the early morning. Methane emission rate was generally highest at the ripening stage. The average methane emission rate during the 1992 dry season (190 mg CH{sub 4} m{sup {minus}2} d{sup {minus}1}) exceeded the average flux rates of the 1992 wet season (79 mg CH{sub 4} m{sup {minus}2} d{sup {minus}1}) by a factor of 2.4. The total methane emitted from these flooded rice fields amounted to 19 g CH{sub 4} m{sup {minus}2} in the dry season with rice yields of 5.2-6.3 ha{sup {minus}1} and 7 g CH{sub 4} m{sup {minus}2} in the wet season with rice yields of 2.4-3.3 t ha{sup {minus}1} regardless of the mode of N application. Significant amounts corresponding to 20% of the methane released under waterlogged conditions were released when the soil was drained after harvest. Emission rates increased sharply when the floodwater receded and macropores started to drain. Emission of methane stopped only when the soil became fully aerated. 25 refs., 5 figs., 1 tab.

Wassmann, R. [International Rice Research Institute, Los Banos (Philippines)] [International Rice Research Institute, Los Banos (Philippines); [Fraunhofer Institute for Atmospheric Environmental Research, Garmisch-Partenkirchen (Germany); Neue, H.U.; Lantin, R.S.; Aduna, J.B.; Alberto, M.C.R.; Andales, M.J.; Tan, M.J. [International Rice Research Institute, Los Banos (Philippines)] [International Rice Research Institute, Los Banos (Philippines); Hoffmann, H.; Papen, H. [Fraunhofer Institute for Atmospheric Environmental Research, Garmisch-Partenkirchen (Germany)] [Fraunhofer Institute for Atmospheric Environmental Research, Garmisch-Partenkirchen (Germany); Gon, H.A.C. D. van der [Agricultural Univ., Wageningen (Netherlands)

1994-08-20

242

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

243

Methane and nitrous oxide sources and emissions in a subtropical freshwater reservoir, south east Queensland, Australia  

NASA Astrophysics Data System (ADS)

Reservoirs have been identified as an important source of non-CO2 greenhouse gases, especially methane (CH4). This study investigates CH4 and nitrous oxide (N2O) sources and emissions in a subtropical freshwater reservoir Gold Creek Dam, Australia using a combination of water-atmosphere and sediment-water flux measurements, water column sampling and pore water analysis. The reservoir was clearly a net source as surface waters were supersaturated with CH4 and N2O. CH4 flux rates were one to two orders of magnitude higher than N2O rates when expressed as CO2 equivalents. Atmospheric CH4 fluxes were dominated by ebullition (<60%) relative to diffusive fluxes and ranged from 165 to 6526 mg CO2 eq m-2 d-1. Dissolved CH4 concentrations in sediment pore waters were approximately 5 000 000% supersaturated. However, dissolved N2O concentrations were 140 to 220% supersaturated and generally confined to the water column greatly reducing the likelihood of ebullition. The flux measurements from this study support past findings that demonstrate the potential important contribution of emissions from subtropical reservoirs to overall GHG budgets. Results suggest future efforts to monitor and model emissions that concentrate on quantifying the ebullition pathway for CH4 as this was dominant relative to diffusive fluxes as well as total N2O emissions.

Sturm, K.; Yuan, Z.; Gibbes, B.; Grinham, A.

2013-12-01

244

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

245

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

246

Record of methane emissions from the Arctic during the last Deglaciation  

NASA Astrophysics Data System (ADS)

The methane hydrates of the Arctic represent potentially significant carbon resources that are sensitive to climate change. Methane hydrate provinces are widespread in the Arctic, but their stability and longevity through time, and the significance of their contribution to the global carbon budget, is still poorly understood. It is, therefore, critical to resolve the frequency of methane (CH4) seafloor emissions through time, in relation to past climate change with a special focus on periods of climate warming. The values of ?13C in benthic foraminifera have been measured in two cores, one collected from an area of active methane venting and one from an inactive area on the Vestnesa Ridge (NW Svalbard continental margin), in order to reconstruct the local history of methane emissions over the past 16,000 years BP. The chronostratigraphic framework of the cores has been derived from biostratigraphic analysis and AMS 14C dates. While foraminifera from some intervals have ?13C within the normal marine range (0 to -1), several intervals are characterized by much lower ?13C, as low as -17.4o in the active core and as low as -4.37o in the inactive core. These intervals are interpreted to record the incorporation of 13C-depleted carbon in the presence of methane emissions at the seafloor during biomineralization of the carbonate foraminiferal tests and subsequent secondary mineralization. The longest of these 'methane emission events' (MEE) coincides with the start of the warm Bølling-Allerød Interstadial (GI-1 in the Greenland ice core record). The lack of correlation between the values of ?13C and ?18O, however, appears to preclude warming of bottom waters as the principal control on methane release. Rather, it seems likely that methane release is related to changes in gas migration pathways, or other geological processes still under debate. Details on the CAGE research plan and organization can be found on www.cage.uit.no to foster opportunities for cross-disciplinary collaboration. Based in Tromsø, at the world's northernmost University, CAGE establishes the intellectual and infrastructure resources for studying the amount of methane hydrate and magnitude of methane release in Arctic Ocean environments on time scales from the Neogene to the present. The Centre of Excellence is funded by the Norwegian Research Council (grant No. 223259) over a period of ten years.

Panieri, Giuliana; Consolaro, Chiara; James, Rachael; Westbrook, Graham; Rasmussen, Tine; Mienert, Jürgen

2014-05-01

247

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

248

Natural emissions of methane from geothermal and volcanic sources in Europe  

NASA Astrophysics Data System (ADS)

It has recently been demonstrated that methane emission from lithosphere degassing is an important component of the natural greenhouse-gas atmospheric budget. Globally, the geological sources are mainly due to seepage from hydrocarbon-prone sedimentary basins, and subordinately from geothermal/volcanic fluxes. This work provides a first estimate of methane emission from the geothermal/volcanic component at European level. In Europe, 28 countries have geothermal systems and at least 10 countries host surface geothermal manifestations (hot springs, mofettes, gas vents). Even if direct methane flux measurements are available only for a few small areas in Italy, a fair number of data on CO 2, CH 4 and steam composition and flux from geothermal manifestations are today available for 6 countries (Czech Republic, Germany, Greece, Iceland, Italy, Spain). Following the emission factor and area-based approach, the available data have been analyzed and have led to an early and conservative estimate of methane emission into the atmosphere around 10,000 ton/yr (4000-16,000 ton/yr), basically from an area smaller than 4000 km 2, with a speculative upper limit in the order of 10 5 ton/yr. Only 4-18% of the conservative estimate (about 720 ton/yr) is due to 12 European volcanoes, where methane concentration in volcanic gases is generally in the order of a few tens of ppmv. Volcanoes are thus not a significant methane source. While the largest emission is due to geothermal areas, which may be situated next to volcanoes or independent. Here inorganic synthesis, thermometamorphism and thermal breakdown of organic matter are substantial. Methane flux can reach hundreds of ton/yr from small individual vents. Geothermal methane is mainly released in three countries located in the main high heat flow regions: Italy, Greece, and Iceland. Turkey is likely a fourth important contributor but the absolute lack of data prevents any emission estimate. Therefore, the actual European geothermal-volcanic methane emission could be easily projected to the 10 5 ton/yr levels, reaching the magnitude of some other natural sources such as forest fires or wild animals.

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

2007-08-01

249

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

250

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

251

Mechanisms of crop management impact on methane emissions from rice fields in Los Baños, Philippines  

Microsoft Academic Search

\\u000a This article comprises 4 yr of field experiments on methane (CH4) emissions from rice fields conducted at Los Baños, Philippines. The experimental layout allowed automated measurements of\\u000a CH4 emissions as affected by water regime, soil amendments (mineral and organic), and cultivars. In addition to emission records\\u000a over 24 h, ebullition and dissolved CH4 in soil solution were recorded in weekly

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

252

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

Microsoft Academic Search

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

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

253

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

254

A COMPARISON OF METHODS FOR ESTIMATING METHANE EMISSIONS  

E-print Network

measurement of methane concentration, differential pressure between the interior and the exterior of the chamber, and temperature inside the chamber. The sensor is a semiconductor (TGS doped SnC>2, Figaro Engineering Inc., in an atmosphere desiccated by silica gel). These two chambers were compared using a test

Paris-Sud XI, Université de

255

Methane and nitrous oxide emissions from a subtropical estuary (the Brisbane River estuary, Australia).  

PubMed

Methane (CH4) and nitrous oxide (N2O) are two key greenhouse gases. Their global atmospheric budgeting is, however, flout with challenges partly due to lack of adequate field studies determining the source strengths. Knowledge and data limitations exist for subtropical and tropical regions especially in the southern latitudes. Surface water methane and nitrous oxide concentrations were measured in a subtropical estuarine system in the southern latitudes in an extensive field study from 2010 to 2012 and water-air fluxes estimated using models considering the effects of both wind and flow induced turbulence. The estuary was found to be a strong net source of both CH4 and N2O all-year-round. Dissolved N2O concentrations ranged between 9.1 ± 0.4 to 45.3 ± 1.3 nM or 135 to 435% of atmospheric saturation level, while CH4 concentrations varied between 31.1 ± 3.7 to 578.4 ± 58.8 nM or 1210 to 26,430% of atmospheric saturation level. These results compare well with measurements from tropical estuarine systems. There was strong spatial variability with both CH4 and N2O concentrations increasing upstream the estuary. Strong temporal variability was also observed but there were no clear seasonal patterns. The degree of N2O saturation significantly increased with NOx concentrations (r(2)=0.55). The estimated water-air fluxes varied between 0.1 and 3.4 mg N2O m(-2)d(-1) and 0.3 to 27.9 mg CH4 m(-2)d(-1). Total emissions (CO2-e) were N2O (64%) dominated, highlighting the need for reduced nitrogen inputs into the estuary. Choice of the model(s) for estimation of the gas transfer velocity had a big bearing on the estimated total emissions. PMID:24333994

Musenze, Ronald S; Werner, Ursula; Grinham, Alistair; Udy, James; Yuan, Zhiguo

2014-02-15

256

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

257

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

258

New Result on Methane Emissions from the East Siberian Arctic Shelf  

NASA Astrophysics Data System (ADS)

Methane release from thawing Arctic permafrost is one of the few carbon-climate mechanisms that could change projected climate forcing substantially in this century. Venting of methane to the atmosphere in the East Siberian Arctic Shelf, the world's largest yet shallowest shelf, was recently shown to be ubiquitous. Here we report results of multi-year investigations performed in the coastal East Siberian Arctic Shelf (ESAS), where invasion of relatively warm seawater occurred most recently. Observational data and simulation of the warming effect of seawater on subsea permafrost suggest that disintegrating subsea permafrost allows formation of migration pathways for methane bubbles released from the sea floor. Sonar data collected in the coastal area and in the mid-outer shelf area together with data, obtained using high-resolution high-speed video camera, enabled area-weighted methane fluxes to be estimated. New factors controlling spatial and temporal variability of methane fluxes on the ESAS were found. In the outer shelf, it was shown that methane releases from the seabed via strong flare-like ebullition that produces fluxes much greater than on the shallow shelf, where largely frozen sediments restrict fluxes. The coastward progression of thawing subsea permafrost in a warming Arctic could potentially result in a significant increase in methane emissions from the East Siberian Arctic Shelf.

Shakhova, N. E.; Semiletov, I. P.; Sergienko, V.; Lobkovsky, L. I.; Dmitrevsky, N.; Salyuk, A.; Yusupov, V.; Salomatin, A.; Karnaukh, V.; Chernykh, D.; Kosmach, D.; Ananiev, R.; Meluzov, A.; Nicolsky, D.; Panteleev, G.

2013-12-01

259

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

260

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...

261

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...

262

Large Scale Constraints on Methane Emissions Determined from Observations  

NASA Astrophysics Data System (ADS)

Measurements of atmospheric CH4 from the NOAA Global Monitoring Division's, Global Cooperative Air Sampling Network began in 1983. These high-precision observations offer key constraints on CH4's budget including the global burden, the rate of increase, and the spatial distribution of CH4 at the surface. These observations allow estimates of total global CH4 emissions without using a chemical transport model. A surprising result of this analysis is that, if the CH4 lifetime has been constant, then total global emissions have been approximately constant since the mid-1980s. This result is difficult to reconcile with bottom-up inventories that report increasing anthropogenic emissions, unless natural emissions have decreased considerably. Analysis of anomalies in CH4 growth rate also allow us to test our understanding of the processes that affect the atmospheric CH4 burden. Large anomalies have been attributed to decreased CH4 sink after the eruption of Mt. Pinatubo in 1992, decreased emissions from wetlands because of cooler than normal temperatures in 1992, and increased emissions from biomass burning and wetlands in 1997/98. The most recent anomaly, starting in 2007 and continuing into early-2011 with an average rate of increase of ~6 ppb yr-1, is more persistent than previous ones and may indicate a permanent change to the global CH4 budget. Dlugokencky et al. [Geophys. Res. Lett., 36, 2009] attributed the increases in 2007 and 2008 to anomalously high temperatures in the Arctic (2007) and greater than average precipitation in the tropics (2007 and 2008). Continuing increases in 2009 and 2010 may be related to a very strong La Niña starting in 2010, the same climate pattern responsible for large positive precipitation anomalies in tropical wetland regions in 2007 and 2008. Indeed, strong precipitation anomalies were observed in SE Asia during 2010. This is a likely cause of continued CH4 increase, and it is consistent with the observation that the largest growth rates in 2010 were in the southern tropics. For 2009, when we were in a weak El Niño, no clear cause has emerged. The observations indicate the largest growth rates were observed in mid-latitudes of the northern hemisphere, a departure from 2007, 2008, and 2010 when signals were clearly dominated by the tropics. A recent model study by Bousquet et al. (Atmos. Chem. Phys., 11, 3689-3700, 2011) is consistent with our earlier study on the role of tropical and high northern latitude wetlands in increased CH4 growth during 2007, but unclear as to the causes of increase in 2008. Little additional information about the causes of the recent anomaly has been determined from satellite retrievals of CH4 column abundance (Frankenberg et al., J. Geophys. Res., 116, 2011).

Dlugokencky, E. J.; Lang, P.; Masarie, K.; Crotwell, A. M.; Bruhwiler, L.

2011-12-01

263

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

...2013-07-01 true 7 of Subpart W of Part 98-Default Methane Emission Factors for Natural Gas Distribution W Table W...Table W-7 Table W-7 of Subpart W of Part 98—Default Methane Emission Factors for Natural Gas Distribution Natural...

2014-07-01

264

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

265

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

SciTech Connect

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

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

2008-04-15

266

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

PubMed

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

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

2011-12-01

267

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

SciTech Connect

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

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

1994-02-01

268

Beaver population fluctuations and tropospheric methane emissions in boreal wetlands  

Microsoft Academic Search

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

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

1991-01-01

269

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

270

Methane Oxidation to Methanol without CO2 Emission: Catalysis by Atomic Negative Ions  

E-print Network

The catalytic activities of the atomic Y-, Ru-, At-, In-, Pd-, Ag-, Pt-, and Os- ions have been investigated theoretically using the atomic Au- ion as the benchmark for the selective partial oxidation of methane to methanol without CO2 emission. Dispersion-corrected density-functional theory has been used for the investigation. From the energy barrier calculations and the thermodynamics of the reactions, we conclude that the catalytic effect of the atomic Ag-, At-, Ru-, and Os- ions is higher than that of the atomic Au- ion catalysis of CH4 conversion to methanol. By controlling the temperature around 290K (Os-), 300K (Ag-), 310K (At-), 320K (Ru-) and 325K (Au-) methane can be completely oxidized to methanol without the emission of CO2. We conclude by recommending the investigation of the catalytic activities of combinations of the above negative ions for significant enhancement of the selective partial oxidation of methane to methanol.

Tesfamichael, Aron; Felfli, Zineb; Msezane, Alfred Z

2014-01-01

271

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

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

272

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

SciTech Connect

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

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

1990-08-20

273

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

Microsoft Academic Search

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

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

2005-01-01

274

Encapsulated fumaric acid as a feed ingredient to decrease ruminal methane emissions  

Microsoft Academic Search

Decreasing methanogenesis in ruminants would benefit the agricultural industry because it would lead to lower energy losses from the animals as well as being beneficial for the environment in decreasing emissions of a greenhouse gas. Fumaric acid (FA) as a feed supplement has the potential to decrease methane production as well as increase glucogenesis and hence milk yield, but the

T. A. Wood; R. J. Wallace; A. Rowe; J. Price; D. R. Yáñez-Ruiz; P. Murray; C. J. Newbold

2009-01-01

275

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

Microsoft Academic Search

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

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

2010-01-01

276

How northern peatlands influence the Earth's radiative budget: Sustained methane emission versus sustained carbon sequestration  

Microsoft Academic Search

Northern peatlands sequester carbon and emit methane, and thus have both cooling and warming impacts on the climate system through their influence on atmospheric burdens of CO2 and CH4. These competing impacts are usually compared by the global warming potential (GWP) methodology, which determines the equivalent CO2 annual emission that would have the same integrated radiative forcing impact over a

Steve Frolking; Nigel Roulet; Jan Fuglestvedt

2006-01-01

277

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

Microsoft Academic Search

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

M. G. Oquist

2001-01-01

278

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

Microsoft Academic Search

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

M. G. Öquist; B. H. Svensson

2002-01-01

279

Emission of nitrous oxide and methane from aero engines: monitoring by tunable diode laser spectroscopy  

Microsoft Academic Search

The emissions of nitrous oxide and methane from a Pratt & Whitney Canada PW 305 and a Rolls Royce RB211 jet engine were measured under various flight conditions either on a ground level stationary test stand or in altitude test cells by using an off-line sampling technique. The concentrations of the gases were determined by long path infrared diode laser

P. Wiesen; J. Kleffmann; R. Kurtenbach; K. H. Becker

1996-01-01

280

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

Microsoft Academic Search

Methane (CH4) represents a major product of organic matter decomposition in lakes. Once produced in the sediments, CH4 can be either oxidized or emitted as a greenhouse gas to the atmosphere. Lakes represent an important source of atmospheric CH4, but the relative magnitudes of the internal pathways that lead to CH4 emissions are not yet clear. We quantified internal cycling

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

2008-01-01

281

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

Microsoft Academic Search

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

J. C. von Fischer; R. Rhew

2008-01-01

282

Emissions of non-methane organic compounds from a grassland site  

Microsoft Academic Search

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

Yoshiko Fukui; P. V. Doskey

1996-01-01

283

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

284

Remote Sensing of Nitrous Oxide and Methane Using Emission Lines of a CO Overtone Laser  

NASA Astrophysics Data System (ADS)

We have conducted laboratory experiments on remote sensing of methane in the 3.440 ?m region and nitrous oxide in the 3.877 ?m region, using emission lines of a CO overtone laser in the differential absorption method. We present the results of measurements of absorption and extinction of the emission lines from an CO overtone laser in the region of selected sensing wavelengths in mixtures with the analyte gases for different experimental configurations.

Ionin, A. A.; Klimachev, Yu. M.; Kozlov, A. Yu.; Kotkov, A. A.; Romanovskii, O. A.; Kharchenko, O. V.; Yakovlev, S. V.

2014-05-01

285

Methane emissions from irrigated rice fields in northern India (New Delhi)  

Microsoft Academic Search

\\u000a Methane (CH4) emission fluxes from rice fields as affected by water regime, organic amendment, and rice cultivar were measured at the\\u000a Indian Agricultural Research IInstitute, New Delhi, using manual and automatic sampling techniques of the closed chamber method.\\u000a Measurements were conducted during four consecutive cropping seasons (July to October) from 1994 to 1997. Emission rates were\\u000a very low (between 16

M. C. Jain; S. Kumar; R. Wassmann; S. Mitra; S. D. Singh; J. P. Singh; R. Singh; A. K. Yadav; S. Gupta

286

A Geochemical Model for the Origin of Methane on Titan  

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

287

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

288

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

289

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

290

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

291

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

E-print Network

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

Zhuang, Qianlai.

292

Methane concentration and emission as affected by methane transport capacity of plants in freshwater marsh  

Microsoft Academic Search

To elucidate effect of the CH4 transport capacity of plants on CH4 production and CH4 emission, we measured CH4 emission and the CH4 transport capacity of plants as well as CH4 and dissolved organic carbon (DOC) concentrations in porewater and redox potential in the freshwater marsh vegetated with Carex lasiocarpa, Carex meyeriana and Deyeuxia angustifolia. Although only 31% of CH4

Weixin Ding; Zucong Cai; Haruo Tsuruta

2004-01-01

293

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

294

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

295

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

PubMed

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

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

2013-12-01

296

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

297

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

298

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

299

METHANE: INDUSTRIAL SOURCES  

EPA Science Inventory

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

300

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

301

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

NASA Astrophysics Data System (ADS)

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

Koch, Stefan; Jurasinski, Gerald; Glatzel, Stephan

2013-04-01

302

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

303

Tropospheric methane emissions from cattails along a latitudinal gradient  

SciTech Connect

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

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

1993-06-01

304

Mitigation strategies for methane emissions from agricultural sources  

SciTech Connect

Anthropogenic emissions of CH{sub 4} account for 70% of total global emissions of this greenhouse gas. Current anthropogenic emissions of CH{sub 4} in the US are estimated to be between 24-30 Tg CH{sub 4} or 7-9% of the global anthropogenic total. By comparison the US is responsible for 27% of anthropogenic emissions of CO{sub 2} from fossil fuel use. Table 1 shows that the major anthropogenic sources of CH{sub 4} in the US are landfills (37%), domestic livestock and livestock waste (31%) and the coal mining/natural gas/petroleum industries (28%). On a global basis it is estimated that US landfills contribute 30% to the global landfill total, whereas livestock (including waste) and the coal mining/natural gas/petroleum industries each contribute about 8% to their respective global totals. The US is an insignificant contributor (< 1%) to global emissions of CH{sub 4} from rice paddies.

Duxbury, J.M. [Cornell Univ., Ithaca, NY (United States)

1993-12-31

305

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

306

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

307

Development of a purpose built landfill system for the control of methane emissions from municipal solid waste  

E-print Network

and leachate collection system targeting at methane harvest. Unlike landfills in western world, PBLFDevelopment of a purpose built landfill system for the control of methane emissions from municipal 2001; accepted 11 December 2001 Abstract In the present paper, a new system of purpose built landfill

Columbia University

308

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

309

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

310

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

311

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

312

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

313

40 CFR 86.1710-99 - Fleet average non-methane organic gas exhaust emission standards for light-duty vehicles and...  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Fleet average non-methane organic gas exhaust emission standards...86.1710-99 Fleet average non-methane organic gas exhaust emission standards... Table R99-15—Fleet Average Non-Methane Organic Gas Standards (g/mi)...

2011-07-01

314

40 CFR 86.1710-99 - Fleet average non-methane organic gas exhaust emission standards for light-duty vehicles and...  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Fleet average non-methane organic gas exhaust emission standards...86.1710-99 Fleet average non-methane organic gas exhaust emission standards... Table R99-15—Fleet Average Non-Methane Organic Gas Standards (g/mi)...

2013-07-01

315

40 CFR 86.1710-99 - Fleet average non-methane organic gas exhaust emission standards for light-duty vehicles and...  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Fleet average non-methane organic gas exhaust emission standards...86.1710-99 Fleet average non-methane organic gas exhaust emission standards... Table R99-15—Fleet Average Non-Methane Organic Gas Standards (g/mi)...

2012-07-01

316

40 CFR 86.1710-99 - Fleet average non-methane organic gas exhaust emission standards for light-duty vehicles and...  

...2013-07-01 true Fleet average non-methane organic gas exhaust emission standards...86.1710-99 Fleet average non-methane organic gas exhaust emission standards... Table R99-15—Fleet Average Non-Methane Organic Gas Standards (g/mi)...

2014-07-01

317

Sensitivity analysis of modeling parameters that affect the dual peaking behaviour in coalbed methane reservoirs  

E-print Network

gas reservoirs, one of which is in its modeling. This thesis includes a sensitivity study that provides a fuller understanding of the parameters involved in coalbed methane production, how coalbed methane reservoirs are modeled and the effects...

Okeke, Amarachukwu Ngozi

2006-10-30

318

[Methane emission from aquatic vegetation zones of Wuliangsu Lake, Inner Mongolia].  

PubMed

To quantify the variations of methane fluxes from different aquatic vegetation zones, two-year measurements were measured at different aquatic vegetation zones and water depths using static chamber technique during two growing season from April to October in 2003 and 2004. Results showed that the average emission flux of CH4 from Potamogeton pectinatus (submerged macrophyte) growing zones was (3.44 +/- 1.60) mg x (m2 x h)(-1), 78.06% lower than that from Phragmites australis (emergent macrophyte). Significant seasonal and diurnal variations of CH4 emission were observed for Phragmites community; however, the variations were minor for P. pectinatus. Sediment temperature at 5 cm and photosynthesis active radiation were important factors influencing seasonal and diurnal variations of CH4 fluxes from Phragmites zone. Annual methane flux from the lake was 1 024.6 t and 1 156.7 t in 2003 and 2004, respectively. PMID:17633615

Duan, Xiao-Nan; Wang, Xiao-Ke; Chen, Lin; Mu, Yu-Jing; Ouyang, Zhi-Yun

2007-03-01

319

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

320

Estimates of methane and ethane emissions from the Texas Barnett Shale  

NASA Astrophysics Data System (ADS)

The recent development of horizontal drilling technology by the oil and gas industry has dramatically increased onshore U.S. natural gas and oil production in the last several years. This production boom has led to wide-spread interest from the policy and scientific communities in quantifying the climate impact of the use of natural gas as a replacement for coal. Because the primary component of natural gas is methane, a powerful greenhouse gas, natural gas leakage into the atmosphere affects its climate impact. Several recent scientific field studies have focused on using atmospheric measurements to estimate this leakage in different producing basins. Methane can be measured precisely with commercial analyzers, and deployment of such analyzers on aircraft, coupled with meteorological measurements, can allow scientists to estimate emissions from regions of concentrated production. Ethane and other light hydrocarbons, also components of raw gas, can be used as tracers for differentiating natural gas emissions from those of other methane sources, such as agriculture or landfills, which do not contain any non-methane hydrocarbons such as ethane. Here we present results from one such field campaign in the Barnett Shale near Fort Worth, Texas, in March 2013. Several 4-hour flights were conducted over the natural gas and oil production region with a small single-engine aircraft instrumented with analyzers for measuring ambient methane, carbon monoxide, carbon dioxide, and ethane at high frequencies (0.3-1Hz). The aircraft also measured horizontal winds, temperature, humidity, and pressure, and collected whole air samples in flasks analyzed later for several light hydrocarbons. In addition to the aircraft, a ground-based High-Resolution Doppler Lidar was deployed in the basin to measure profiles of horizontal winds and estimate the boundary layer height 24 hours a day over the campaign period. The aircraft and lidar measurements are used together to estimate methane and ethane emissions in the region. Flight track colored by methane (CH4, left) and ethane (C2H6, right) mole fraction. A three-hour back trajectory (red line) constructed from lidar wind measurements passes over the Barnett natural gas well locations (gray points) prior to reaching the location on the flight path indicated by the red star.

Karion, A.; Sweeney, C.; Yacovitch, T.; Petron, G.; Wolter, S.; Conley, S. A.; Hardesty, R. M.; Brewer, A.; Kofler, J.; Newberger, T.; Herndon, S.; Miller, B. R.; Montzka, S. A.; Rella, C.; Crosson, E.; Tsai, T.; Tans, P. P.

2013-12-01

321

Northern fens - Methane flux and climatic change  

Microsoft Academic Search

Methane flux from northern peatlands is believed to be an important contribution to the global methane budget. High latitude regions are predicted to experience significant changes in surface temperature and precipitation associated with the 2 x CO2 climate scenarios, but the effects of these changes on methane emission are poorly understood. A peatland hydrologic model predicted June-August decreases in water

Nigel Roulet; Tim Moore; Jill Bubier; Peter Lafleur

1992-01-01

322

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

323

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

Microsoft Academic Search

Natural wetlands are the single most important contributors of methane (CH4) to the atmosphere. Recent research has shown that the deposition of sulfate (SO\\u000a4\\u000a2–\\u000a) can substantially reduce the emission of this radiatively important gas from wetlands. However, the influence of temperature in regulating the extent of this effect is unclear. Peatlands also constitute an important store of

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

2005-01-01

324

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

325

Earth System Modeling of Ozone, Methane, and DMS  

Microsoft Academic Search

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,

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

2010-01-01

326

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

327

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

328

Effects of decadal deposition of nitrogen and sulfur, and increased temperature, on methane emissions from a boreal peatland  

NASA Astrophysics Data System (ADS)

Boreal peatlands represent a significant source of methane to the atmosphere. Pollutants and climate changes resulting from human activity are likely to affect the processes controlling methane emissions from these systems. This study investigated the effects of decadal deposition of nitrogen and sulfate, and increased air temperature, on methane emissions from a northern Swedish peatland during the snow-free seasons of 2005 and 2006, the latter being exceptionally dry. The experimental setup involved a full factorial design at two levels with greenhouse cover (present or absent), nitrogen deposition (2 or 30 kg N ha-1 a-1), and sulfate deposition (3 or 20 kg S ha-1 a-1) as experimental factors. Methane emission rates were measured using static chambers after 10-11 years of experimental manipulations. Emissions were significantly reduced by the greenhouse treatment in 2005, by 30% on average, but not in 2006. The reduction in methane emissions in response to the greenhouse treatment were counteracted by nitrogen deposition; with high nitrogen deposition the effect of the greenhouse cover was low and nonsignificant. High nitrogen deposition increased methane emissions at ambient sulfate levels, probably due to sedge cover increasing from 37 to 65%, but the combination of high nitrogen deposition and high sulfate deposition did not affect methane emissions. Effects of increased nitrogen on methane emission have previously in short-term manipulations (<6 years) been ranging from slightly negative to slightly positive. The substantial positive effects observed in this study emphasize the need for long-term manipulations to obtain valid results under natural conditions.

Eriksson, Tobias; Öquist, Mats G.; Nilsson, Mats B.

2010-12-01

329

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

NASA Astrophysics Data System (ADS)

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

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

2002-12-01

330

Isotopic Ratios in Titan's Methane: Measurements and Modeling  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

331

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

332

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

SciTech Connect

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

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

2011-10-01

333

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

334

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

NASA Astrophysics Data System (ADS)

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

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

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

2005-07-01

335

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

336

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

337

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

338

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

NSDL National Science Digital Library

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

Hatch, Harold

2007-08-29

339

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.

340

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

NASA Astrophysics Data System (ADS)

Rice paddy fields are one of the greatest anthropogenic sources of methane (CH4), the third most important greenhouse gas after water vapour and carbon dioxide. In agricultural fields, CH4 is usually measured with the closed chamber technique, resulting in discontinuous series of measurements performed over a limited area, that generally do not provide sufficient information on the short-term variation of the fluxes. On the contrary, aerodynamic techniques have been rarely applied for the measurement of CH4 fluxes in rice paddy fields. The eddy covariance (EC) technique provides integrated continuous measurements over a large area and may increase our understanding of the underlying processes and diurnal and seasonal pattern of CH4 emissions in this ecosystem. For this purpose a Fast Methane Analyzer (Los Gatos Research Ltd.) was installed in an eddy-covariance field set-up in a rice paddy field in the Po Valley (Northern Italy). Methane fluxes were measured during the rice growing season, both with EC and with manually operated closed chambers. Methane fluxes were strongly influenced by the presence of the water table, with emissions peaking when it was above 10-12 cm. Further studies are required to evaluate if water table management could decrease CH4 emissions. The development of rice plants and soil temperature were also responsible of the seasonal variation on the fluxes. The EC measured showed a diurnal cycle in the emissions, which was more relevant during the vegetative period, and with CH4 emissions being higher in the late evening, possibly associated with higher water temperature. The comparison between both measurement techniques shows that greater fluxes are measured with the chambers, especially when higher fluxes are being produced, resulting in 30 % higher seasonal estimations with the chambers than with the EC (41.1 and 31.8 g CH4 m-2 measured with chambers and EC respectively). The differences may be a result of the combined effect of overestimation with the chambers, the possible underestimation by the EC technique and of not having considered the daily course of the fluxes for the calculation of seasonal emissions from chambers.

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

2011-09-01

341

A methane production feasibility model for central anaerobic digesters  

NASA Astrophysics Data System (ADS)

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

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

1981-01-01

342

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

343

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

344

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

345

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

346

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

347

Exploration strategies based on a coalbed methane producibility model  

SciTech Connect

Knowing geologic and hydrologic characteristics of a basin does not necessarily lead to a determination of its coalbed methane producibility because it is the synergy among key hydrogeologic controls that governs producibility. Detailed studies performed in the San Juan, Piceance, and Sand Wash Basins determined that the key hydrogeologic factors affecting producibility include depositional setting and coal distribution, tectonic and structural setting, coal rank and gas generation, hydrodynamics, permeability, and gas content. The conceptual model based on these factors provides a rationale for exploration and development strategies for unexplored areas or in basins having established or limited production. Exceptionally high productivity requires good permeability; thick, laterally continuous high-rank and high-gas-content coals; dynamic flow of ground water through those coals; generation of secondary biogenic gases; and migration and conventional trapping of thermogenic and biogenic gases. Higher coalbed methane producibility commonly occurs in areas of upward flow associated with permeability barriers (no-flow boundaries). Fluid migration across a large gathering area orthogonal to permeability barriers and/or in situ generation of secondary biogenic gases concentrate the coal gas, resulting in higher gas contents. Low coalbed methane production is typically associated with very low permeability systems; the absence of conventional or hydrodynamic traps; and thin, low-rank coals below the threshold of thermogenic gas generation. Production from relatively low-gas-content coals in highly permeable recharge areas may result in excessive water and limited coalbed methane production. Thus, high permeability can be as detrimental to coalbed methane producibility as is low permeability.

Scott, A.R.; Kaiser, W.R.; Hamilton, D.S.; Tyler, R.; Finley, R.J. (Univ. of Texas, Austin, TX (United States))

1996-01-01

348

Exploration strategies based on a coalbed methane producibility model  

SciTech Connect

Knowing geologic and hydrologic characteristics of a basin does not necessarily lead to a determination of its coalbed methane producibility because it is the synergy among key hydrogeologic controls that governs producibility. Detailed studies performed in the San Juan, Piceance, and Sand Wash Basins determined that the key hydrogeologic factors affecting producibility include depositional setting and coal distribution, tectonic and structural setting, coal rank and gas generation, hydrodynamics, permeability, and gas content. The conceptual model based on these factors provides a rationale for exploration and development strategies for unexplored areas or in basins having established or limited production. Exceptionally high productivity requires good permeability; thick, laterally continuous high-rank and high-gas-content coals; dynamic flow of ground water through those coals; generation of secondary biogenic gases; and migration and conventional trapping of thermogenic and biogenic gases. Higher coalbed methane producibility commonly occurs in areas of upward flow associated with permeability barriers (no-flow boundaries). Fluid migration across a large gathering area orthogonal to permeability barriers and/or in situ generation of secondary biogenic gases concentrate the coal gas, resulting in higher gas contents. Low coalbed methane production is typically associated with very low permeability systems; the absence of conventional or hydrodynamic traps; and thin, low-rank coals below the threshold of thermogenic gas generation. Production from relatively low-gas-content coals in highly permeable recharge areas may result in excessive water and limited coalbed methane production. Thus, high permeability can be as detrimental to coalbed methane producibility as is low permeability.

Scott, A.R.; Kaiser, W.R.; Hamilton, D.S.; Tyler, R.; Finley, R.J. [Univ. of Texas, Austin, TX (United States)

1996-12-31

349

Methane emissions, body composition, and rumen fermentation traits of beef heifers differing in residual feed intake.  

PubMed

This study examined the relationship of residual feed intake (RFI) and performance with methane emissions, rumen fermentation, and digestion in beef heifers. Individual DMI and growth performance were measured for 22 Simmental heifers (mean initial BW 449 kg, SD = 46.2 kg) offered grass silage ad libitum for 120 d. Ultrasonically scanned muscle and fat depth, BCS, muscularity score, skeletal measurements, blood variables, rumen fermentation (via stomach tube), and total tract digestibility (indigestible marker) were measured. Methane production was estimated using the sulfur hexafluoride tracer gas technique over two 5-d periods beginning on d 20 and 75 of the RFI measurement period. Phenotypic RFI was calculated as actual DMI minus expected DMI. The residuals of the regression of DMI on ADG and midtest metabolic body weight, using all heifers, were used to compute individual RFI coefficients. Heifers were ranked by RFI and assigned to low (efficient), medium, or high (inefficient) groupings. Overall ADG and DMI were 0.58 kg (SD = 0.18) and 7.40 kg (SD = 0.72), respectively. High-RFI heifers consumed 9 and 15% more (P < 0.05) than medium- and low-RFI groups, respectively. Body weight, growth, skeletal, and composition traits did not differ (P > 0.05) between low- and high-RFI groups. High-RFI heifers had higher concentrations of plasma glucose (6%) and urea (13%) and lower concentrations of plasma creatinine (9%) than low-RFI heifers (P < 0.05). Rumen pH and apparent in vivo digestibility did not differ (P > 0.05) between RFI groups, although acetate:propionate ratio was lowest (P = 0.07) for low-RFI (3.5) and highest for high-RFI (4.6) heifers. Methane production expressed as grams per day or grams per kilogram metabolic body weight was greater (P < 0.05) for high (297 g/d and 2.9 g/kg BW0.75) compared with low (260 g/d and 2.5 g/kg BW0.75) RFI heifers, with medium (275 g/d and 2.7 g/kg BW0.75) RFI heifers being intermediate. Regression analysis indicated that a 1 kg DM/d increase in RFI was associated with a 23 g/d increase (P = 0.09) in methane emissions. Results suggest that improved RFI will reduce methane emissions without affecting productivity of growing beef cattle. PMID:24146149

Fitzsimons, C; Kenny, D A; Deighton, M H; Fahey, A G; McGee, M

2013-12-01

350

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

351

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 st