NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Regulation of Methane Oxidation in a Freshwater Wetland by Water Table Changes and AnoxiaThe effects of water table fluctuations and anoxia on methane emission and methane oxidation were studied in a freshwater marsh. Seasonal aerobic methane oxidation rates varied between 15% and 76% of the potential diffusive methane flux (diffusive flux in the absence of aerobic oxidation). On an annual basis, approximately 43% of the methane diffusing into the oxic zone was oxidized before reaching the atmosphere. The highest methane oxidation was observed when the water table was below the peat surface. This was confirmed in laboratory experiments where short-term decreases in water table levels increased methane oxidation but also net methane emission. Although methane emission was generally not observed during the winter, stems of soft rush (Juncus effusus) emitted methane when the marsh was ice covered. Indigenous methanotrophic bacteria from the wetiand studied were relatively anoxia tolerant. Surface peat incubated under anoxic conditions maintained 30% of the initial methane oxidation capacity after 32 days of anoxia. Methanotrophs from anoxic peat initiated aerobic methane oxidation relatively quickly after oxygen addition (1-7 hours). These results were supported by culture experiments with the methanotroph Methylosinus trichosporium OB3b. This organism maintained a greater capacity for aerobic methane oxidation when starved under anoxic compared to oxic conditions. Anoxic incubation of M. trichosporium OB3b in the presence of sulfide (2 mM) and a low redox potential (-110 mV) did not decrease the capacity for methane oxidation relative to anoxic cultures incubated without sulfide. The results suggest that aerobic methane oxidation was a major regulator of seasonal methane emission front the investigated wetland. The observed water table fluctuations affected net methane oxidation presumably due to associated changes in oxygen gradients. However, changes from oxic to anoxic conditions in situ had relatively little effect on survival of the methanotrophic bacteria and thus on methane oxidation potential per se.
Document ID
19980223027
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Roslev, Peter
(Maine Univ. Walpole, ME United States)
King, Gary M.
(Maine Univ. Walpole, ME United States)
Date Acquired
August 18, 2013
Publication Date
January 1, 1996
Publication Information
Publication: FEMS Microbiology Ecology
Publisher: Elsevier
Volume: 19
ISSN: 0168-6496
Subject Category
Life Sciences (General)
Report/Patent Number
DMC-Contrib-288
Funding Number(s)
CONTRACT_GRANT: NSF BSR-91-07315
CONTRACT_GRANT: NAGw-3746
CONTRACT_GRANT: EU-EU5V-CT-94-0499
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available