Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 6 8 2009 10.5194/bg-6-1491-2009 http://www.biogeosciences.net/6/1491/2009/ http://www.biogeosciences.net/6/1491/2009/bg-6-1491-2009.html http://www.biogeosciences.net/6/1491/2009/bg-6-1491-2009.pdf 1491 1504 2009-08-07 Methanotrophy potential versus methane supply by pore water diffusion in peatlands E. R. C. Hornibrook ed.hornibrook@bristol.ac.uk H. L. Bowes A. Culbert A. V. Gallego-Sala Bristol Biogeochemistry Research Centre, Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, UK Low affinity methanotrophic bacteria consume a significant quantity of methane in wetland soils in the vicinity of plant roots and at the oxic-anoxic interface. Estimates of the efficiency of methanotrophy in peat soils vary widely in part because of differences in approaches employed to quantify methane cycling. High resolution profiles of dissolved methane abundance measured during the summer of 2003 were used to quantity rates of upward methane flux in four peatlands situated in Wales, UK. Aerobic incubations of peat from a minerotrophic and an ombrotrophic mire were used to determine depth distributions of kinetic parameters associated with methane oxidation. The capacity for methanotrophy in a 3 cm thick zone immediately beneath the depth of nil methane abundance in pore water was significantly greater than the rate of upward diffusion of methane in all four peatlands. Rates of methane diffusion in pore water at the minerotrophic peatlands were small (<10%) compared to surface emissions during June to August. The proportions were notably greater in the ombrotrophic bogs because of their typically low methane emission rates. Methanotrophy appears to consume entirely methane transported by pore water diffusion in the four peatlands with the exception of 4 of the 33 gas profiles sampled. 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