CH₄ oxidation by tundra wetlands as measured by a selective inhibitor technique

Rates of methane (CH 4 ) oxidation were measured in three wet sedge communities on Alaska's North Slope in 1993 and 1995 using the selective inhibitor methyl fluoride (CH 3 F). Comparison of CH 4 flux prior to inhibition (net flux) with flux after inhibition (gross flux) enables one to infer CH 4 oxidation rates by difference. Oxidation rates from Franklin Bluffs, Sagavanirktok River floodplain, Toolik Lake Inlet, and Toolik Lake Outlet averaged 24.9, 14.7 (1.6), (17.6), and 25.2 (49.8) mg CH 4 /m 2 /d in 1995 (1993), respectively. Plot level data suggest that oxidation rates vary greatly spatially and temporally down to the meter scale. As a percentage of flux, however, mean CH 4 oxidation rates of 13.4, 21.7 (2.0), (16.5), and 19.4 (38.0)% at Franklin Bluffs, Sagavanirktok River, Toolik Lake Inlet, and Toolik Lake Outlet in 1995 (1993), respectively, were seen to be rather uniform over the region. The effects of temperature on CH 4 production appear to be the dominant control on CH 4 oxidation rates in wet sedge environments as opposed to soil moisture dependency in upland soils. Nutrient fertilization was not found to influence the fraction of CH 4 lost to oxidation. This suggests that CH 4 oxidation, while significant in tundra wetlands, may consume a near‐constant fraction of available CH 4 .