Effect of temperature and atmospheric pressure on methane (CH<sub>4</sub>) ebullition from near‐surface peats

Kellner, Erik; Baird, Andy J.; Oosterwoud, Marieke; Harrison, Kerry A.; Waddington, J. M.

doi:10.1029/2006gl027509

Cited by 89 publications

(134 citation statements)

References 12 publications

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“…Briefly, the simulated aqueous CH 4 concentration in each soil level is used to estimate the expected equilibrium gaseous partial pressure as a function of temperature and pressure. When this partial pressure exceeds C e,max (taken as 15 % of the ambient pressure; Baird et al, 2004;Strack et al, 2006;Wania et al, 2010), bubbling occurs to remove CH 4 to below this value, modified by the fraction of CH 4 in the bubbles (taken as 57 %; Kellner et al, 2006;Wania et al, 2010). Bubbles are immediately added to the surface flux for saturated columns and are placed immediately above the water table interface in unsaturated columns.…”

Section: Ebullitionmentioning

confidence: 99%

Barriers to predicting changes in global terrestrial methane fluxes: analyses using CLM4Me, a methane biogeochemistry model integrated in CESM

et al. 2011

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Abstract. Terrestrial net CH 4 surface fluxes often represent the difference between much larger gross production and consumption fluxes and depend on multiple physical, biological, and chemical mechanisms that are poorly understood and represented in regional-and global-scale biogeochemical models. To characterize uncertainties, study feedbacks between CH 4 fluxes and climate, and to guide future model development and experimentation, we developed and tested a new CH 4 biogeochemistry model (CLM4Me) integrated in the land component (Community Land Model; CLM4) of the Community Earth System Model (CESM1). CLM4Me includes representations of CH 4 production, oxidation, aerenchyma transport, ebullition, aqueous and gaseous diffusion, and fractional inundation. As with most global models, CLM4 lacks important features for predicting current and future CH 4 fluxes, including: vertical representation of soil organic matter, accurate subgrid scale hydrology, realistic representation of inundated system vegetation, anaerobic decomposition, thermokarst dynamics, and aqueous chemistry. We compared the seasonality and magnitude of predicted CH 4 emissions to observations from 18 sites and three global atmospheric inversions. Simulated net CH 4 emissions using our baseline parameter set were 270, 160, 50, and 70 Tg CH 4 yr −1 globally, in the tropics, in the temperate zone, and north of 45 • N, respectively; these values are within the range of previous estimates. We then used the model to characterize the sensitivity of regional and global CH 4 emission estimates to uncertainties in model paCorrespondence to: W. J. Riley (wjriley@lbl.gov) rameterizations. Of the parameters we tested, the temperature sensitivity of CH 4 production, oxidation parameters, and aerenchyma properties had the largest impacts on net CH 4 emissions, up to a factor of 4 and 10 at the regional and gridcell scales, respectively. In spite of these uncertainties, we were able to demonstrate that emissions from dissolved CH 4 in the transpiration stream are small (<1 Tg CH 4 yr −1 ) and that uncertainty in CH 4 emissions from anoxic microsite production is significant. In a 21st century scenario, we found that predicted declines in high-latitude inundation may limit increases in high-latitude CH 4 emissions. Due to the high level of remaining uncertainty, we outline observations and experiments that would facilitate improvement of regional and global CH 4 biogeochemical models.

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Section: Ebullitionmentioning

confidence: 99%

Barriers to predicting changes in global terrestrial methane fluxes: analyses using CLM4Me, a methane biogeochemistry model integrated in CESM

et al. 2011

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Section: Carbon Cycling and Ecohydrologymentioning

confidence: 66%

“…Evidence of this has been found in both laboratory (Baird et al, 2004;Kellner et al, 2006) and field (Strack et al, 2005) experiments. Baird et al (2004) found a threshold gas content limit of approximately 10-14% while Kellner et al (2006) found threshold values of 12 and 15% provided very good results when modelling ebullition events. These gas bubbles also affect the hydrological properties of peat since as bubbles form, they block off voids, and have the potential to greatly reduce water and solute transfer from surrounding areas , creating a localized zone of over-pressuring (Kellner et al, 2004).…”

Section: Carbon Cycling and Ecohydrologymentioning

confidence: 66%

Advances in Canadian Peatland Hydrology, 2003-2007

Waddington¹,

Quinton²,

Price³

et al. 2009

Canadian Water Resources Journal

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Abstract:Peatlands represent over 90% of Canadian wetlands and are the focus of considerable hydrological and biogeochemical research. Research on evapotranspiration (ET) has shown that it can exceed annual precipitation (P) where there are replenishing flood events. Evaporation from open water ponds in boreal peatlands exceeds ET from vegetated riparian zones by about two times, but surrounding forests can shelter small ponds by reducing turbulence. In an open bog, evaporation was modelled by separating the surface into vascular vegetation, hummock moss and hollow moss surfaces, and showed that vascular plants contribute 60-80% of ET, mosses making up the remainder with hummock mosses dominant over hollows. Runoff from peatlands is enhanced by features ranging from headwater swamps, ice-cored peat plateaus, patchy arctic wetlands and even sections of riverine peatlands. Groundwater fluxes can be quite erratic, and depend on transient properties of the peat that depend on moisture content (e.g., unsaturated hydraulic conductivity) to unsteady saturated hydraulic properties (e.g., hydraulic conductivity, specific yield) caused by peat compression and dilation associated with water storage changes. Surface elevation adjustments can result in a more stable depth to water table, increase evaporation losses, increase methane emission, and attenuate pore-water concentration of contaminants. Research on Canadian peatlands has also made significant methodological advances, including measurement of hydraulic properties of living mosses and peat pore-water and pore dimension characteristics. A considerable multi-annual effort has also been made in evaluating carbon dynamics from Canadian peatlands. Summer moisture availability is important to determining carbon fluxes with some peatlands experiencing enhanced productivity following drought (water table drawdown). Sudden changes in water table elevation promote DOC production and export. Methane bubbles confound hydraulic gradients and flows by creating local pockets of pressure, which are then released episodically when the entrapped gas reaches a threshold content. Canadian peatland hydrology continues to be actively researched in lab, field and modelling studies.

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“…Somewhat similar ebullitions occur in natural systems, such as saturated sediment (Winterwerp et al 2004;Amos and Mayer 2006), peatlands (Tokida et al 2005;Kellner et al 2006), and in gas-driven eruptions for some types of volcanic activity (Gaonach et al 1996;Lovejoy et al 2004;Stix 2007), and lake and ocean activities (Zhang and Kling 2006). Strack et al (2005) described what could be essentially the same behavior as "potential episodic release of CH4 via ebullition events."…”

Section: Introductionmentioning

confidence: 92%

The start of ebullition in quiescent, yield-stress fluids

Sherwood¹,

Sáez

2014

Nuclear Engineering and Design

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Non-Newtonian rheology is typical for the high-level radioactive waste (HLW) slurries processed in the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Hydrogen and other flammable gases are generated in the aqueous phase by radiolytic and chemical reactions. HLW slurries have a capacity for retaining gas characterized by the shear strength holding the bubbles still. The sizes and degassing characteristics of flammable gas bubbles in the HLW slurries expected to be processed by the WTP are important considerations for designing equipment and operating procedures. Slurries become increasingly susceptible to degassing as the bubble concentration increases. This susceptibility and the process of ebullitive bubble enlargement are described here. When disturbed, the fluid undergoes localized flow around neighboring bubbles which are dragged together and coalesce, producing an enlarged bubble. For the conditions considered in this work, bubble size increase is enough to displace the weight required to overcome the fluid shear strength and yield the surroundings. The buoyant bubble ascends and accumulates others within a zone of influence, enlarging by a few orders of magnitude. This process describes how the first bubbles appear on the surface of a 7 Pa shear strength fluid a few seconds after being jarred.

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Effect of temperature and atmospheric pressure on methane (CH₄) ebullition from near‐surface peats

Cited by 89 publications

References 12 publications

Barriers to predicting changes in global terrestrial methane fluxes: analyses using CLM4Me, a methane biogeochemistry model integrated in CESM

Barriers to predicting changes in global terrestrial methane fluxes: analyses using CLM4Me, a methane biogeochemistry model integrated in CESM

Advances in Canadian Peatland Hydrology, 2003-2007

The start of ebullition in quiescent, yield-stress fluids

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Effect of temperature and atmospheric pressure on methane (CH4) ebullition from near‐surface peats

Cited by 89 publications

References 12 publications

Barriers to predicting changes in global terrestrial methane fluxes: analyses using CLM4Me, a methane biogeochemistry model integrated in CESM

Barriers to predicting changes in global terrestrial methane fluxes: analyses using CLM4Me, a methane biogeochemistry model integrated in CESM

Advances in Canadian Peatland Hydrology, 2003-2007

The start of ebullition in quiescent, yield-stress fluids

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Effect of temperature and atmospheric pressure on methane (CH₄) ebullition from near‐surface peats