HR: 11:05h
AN: B52C-04 INVITED    [Abstracts]
TI: Coupling Peatland Ecohydrology and Methane Ebullition
AU: * Waddington, J M
EM: wadding@mcmaster.ca
AF: McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada
AU: Baird, A J
EM: a.j.baird@qmul.ac.uk
AF: Queen Mary, University of London, Mile End Road, London, E1 4NS, United Kingdom
AB: As natural sources of methane (CH₄), peatlands play an important role in the global carbon cycle. The position of the water table within a peatland can have a large effect on CH₄ emissions. With climate models predicting enhanced evapotranspiration and lower water-table position, peatland CH₄ emissions generally are expected to decrease in coming decades. However, these predictions tend to focus almost exclusively on diffusive CH₄ fluxes. Over the last five years, our research has examined the importance of ebullition of biogenic gas bubbles as a mechanism for the transport of CH₄ to the atmosphere. Here we present a new conceptual model that addresses how changes in temperature, atmospheric pressure and peat structure affect CH₄ bubble storage and release. We suggest that many peatlands may experience a (much) higher CH₄ flux under warmer and drier conditions due to increased CH₄ ebullition despite a decrease in CH₄ flux via diffusion. In addition to influencing atmospheric CH₄ emissions, recent research suggests that biogenic gas bubbles beneath the water table also affect hydrological processes in peat soils. Our work shows that these bubbles reduce saturated volumetric water content (VWC) and ‘saturated' hydraulic conductivity, and create zones of overpressure (zones of elevated pore-water pressure). All of these factors have large hydrological and biogeochemical implications, in that they will affect directions and rates of water flow, solute transfer, and the transport of CH₄ to the atmosphere.
DE: 0490 Trace gases
DE: 0497 Wetlands (1890)
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
DE: 1813 Eco-hydrology
SC: Biogeosciences [B]
MN: 2007 Fall Meeting