HR: 1330h
AN: NB33C-15    [Abstracts]
TI: Experimental verification of a mechanistic model of methane bubble formation in non-vegetated flooded rice field soil
AU: * Conrad, R
EM: conrad@staff.uni-marburg.de
AF: Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Str., Marburg, 35043 Germany
AU: Kusmin, A
EM: kouzmine@hmi.de
AF: Hahn-Meitner Institute, Glienicker Str. 100, Berlin, 14103 Germany
AU: Bazhin, N M
EM: bazhin@ns.kinetics.nsc.ru
AF: Institute of Chemical Kinetics and Combustion, Institutskaya 3, Novosibirsk, 630090 Russian Federation
AB: Anoxic wetlands are an important source for the greenhouse gas CH4, much of which is emitted in form of gas bubbles. The conditions for formation of gas bubbles have recently been described by an analytical model, which allows the prediction of fluxes by first physical principles using the knowledge of gas concentration profiles and/or gas production rates. We verified parts of this model by experiments using microcosms of flooded, non-vegetated and homogeneous rice field soil incubated under different gas atmospheres and at different temperatures. In these experiments we determined rates of CH4 and CO2 production, upper boundaries of the bubble zone, gas-filled porosities and vertical profiles of dissolved CH4, CO2 and N2. Methane production rates were measured from slurry incubations and/or from CH4 emission rates by inhibition of CH4 oxidation with methyl fluoride. Vertical gas concentration profiles were measured by using gas diffusion probes and peepers. The vertical gas concentrations were used to determine the diffusive CH4 flux. The results of our experiments confirmed that by knowing only one of the following parameters, i.e. CH4 production, diffusive CH4 flux and depth of upper boundary of bubble zone, the remainder could be predicted from the model. In particular, we were able to predict the percentage of gas bubble flux from measured CH4 emission rates under the experimental conditions, which was on the order of 90 percent.
DE: 0315 Biosphere/atmosphere interactions
DE: 0400 Biogeosciences
DE: 1615 Biogeochemical processes (4805)
DE: 1890 Wetlands
DE: 3210 Modeling
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly