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Methane‐limited methanotrophy in tidal freshwater swamps
Author(s) -
Megonigal J. Patrick,
Schlesinger William. H.
Publication year - 2002
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2001gb001594
Subject(s) - anaerobic oxidation of methane , wetland , methane , environmental chemistry , swamp , environmental science , vegetation (pathology) , chemistry , hydrology (agriculture) , ecology , geology , medicine , geotechnical engineering , organic chemistry , pathology , biology
We investigated the relationship between CH 4 production and oxidation in two tidal freshwater wetland forests in order to determine whether CH 4 oxidation efficiency was limited by O 2 or CH 4 . Methane oxidation was measured in situ over a 16‐month period with bi‐monthly applications of the inhibitor CH 3 F. Oxidation consumed 52 ± 10 and 81 ± 9% of diffusive CH 4 emissions on the two sites. Methane oxidation rates were linearly related to gross CH 4 emissions on both sites ( r 2 = 0.96), demonstrating the process was CH 4 ‐limited. This interpretation is consistent with the fact that the apparent activation energies for the potential CH 4 production and oxidation differed by <4 kJ mol −1 . Apparent activation energies calculated from field emissions data were also similar for the two processes. The high CH 4 oxidation efficiency on these sites may be attributed to relatively low rates of methane production, a deep oxidizing zone (5–10 cm), and low cover of understory vegetation capable of CH 4 transport. If our results are typical of forested wetlands, CH 4 oxidation efficiency in forested wetlands will not change in response to soil warming.