Methane emissions from beaver ponds: Rates, patterns, and transport mechanisms
Tóm tắt
Net methane fluxes as well as methane fluxes via gas bubbles and via molecular diffusion were measured separately at nine different sampling sites throughout a beaver pond located in the low boreal forest region of central Ontario, Canada. In 1990, the average daily methane emission rate was 37.2 ± 30.4 mg CH4 m−2 d−1, yielding a total annual methane efflux of 5.8 g CH4 m−2 of which 1.1 g CH4 m−2 were produced in the wintertime when the pond was ice covered. On average, 65% of the net methane flux was released via gas bubble emission, the remaining 35% via molecular diffusion. Gas bubble flux rates were highly variable in space and time, suggesting that low sampling frequencies, common in many methane emission studies, could introduce large uncertainties to the estimated annual flux rates for different wetland systems. The effects of changes in environmental variables on methane emissions were found to be strongly dependent on which transport mechanism dominated the release of methane from the sediments. While the gas bubble flux volume was mainly affected by changes in atmospheric pressure and sediment temperatures, the diffusive flux component was found to be more sensitive to changes in the pond water level. Overall, magnitudes of methane fluxes from this pond were similar to other beaver ponds and moderate to high when compared to other wetland types in the low boreal forest region.
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Tài liệu tham khảo
Chemical and Biological Research Institute, 1979, Agroclimatic Atlas Canada
Devito K. J. Waterborne phosphorus and nitrogen retention in some Precambrian shield wetlands: The role of hydrology and oxidation — reduction potential M.Sc. thesis Trent Univ. Peterborough Ont. 1989.
King G. M., 1990, Distribution and rate of methane oxidation in sediments of the Florida Everglades, Appl. Environ. Microbiol., 56, 2902, 10.1128/aem.56.9.2902-2911.1990
Moore T. R., 1995, Soils and Global Change, 153
Riley J. L. Peat and peatland resources of southeastern OntarioOpen File Rep. 5633Geological Survey Minist. of North. Mines and Dev. Toronto Ontario 1988.
Rudd J. W., 1980, Methane cycling in aquatic environments, Adv. Aquat. Microbiol., 2, 77
Scheider W. A. C. M.Cox C. D.Scott Hydrological data for lakes and watersheds in the Muskoka‐Haliburton study area (1976 — 1980)Data Report DR 83/6Ont. Minist. of Environ. DRC Dorset Ont. 1983.
Svenson B. H., 1984, In situ methane production from acid peat in plant communities with different moisture regimes in a subarctic mire, Oikos, 43, 341, 10.2307/3544151
Vitt D. H. S.Bayley T.Jin L.Halsey B.Parker R.Craik Methane and carbon dioxide production from wetlands in boreal AlbertaRep. contract 90‐0270Alberta Environ. Minist. Edmonton 1990.
Weyhenmeyer C. E. Methane emissions of a Boreal Beaver Pond: Rates patterns and environmental controls M.Sc. thesis Trent Univ. Peterborough Ont. 1992.
Zoltai S. C., 1983, Mires, Swamp, Bog, Fen, and Moor, 245