Most global and regional "greenhouse gas" budgets have neglected beaver ponds, but they have been found to be relatively high emitters of methane (CH$ sb4$) (Roulet et. al., 1992). Static chambers, bubble traps, benthic chambers. piezometers, and water column and sediment profiles were used to determine the dynamics of CH$ sb4$ production, oxidation, storage, and emissions from a northern boreal beaver pond, as part of the Boreal Forest Ecosystem-Atmosphere Study (BOREAS) from May 1 to September 15, 1994. Samples were analysed by gas chromatography, and isotopic analyses were performed by mass spectrometry. / The mean flux of CH$ sb4$ from the beaver pond (155 and 320 mg CH$ sb4$ m$ sp{-2}$ d$ sp{-1}$ for vegetated and open water sites, respectively) was greater than the flux from most other northern boreal wetlands (Bubier et. al., 1995). CH$ sb4$ availability was primarily controlled by sediment temperature, and CH$ sb4$ transport was controlled by windspeed (diffusion) and atmospheric pressure (bubbles). Bubbles comprised 20 to 52% of the net annual flux comprising the remainder. A large difference in bubble flux was observed between open water (15.7 g CH$ sb4$ m$ sp{-2}$ yr$ sp{-1}$) and vegetated sites (2.9 g CH$ sb4$ m$ sp{-2}$ yr$ sp{-1}$), and isotopic analyses indicate that this difference is due, in part, to a difference in CH$ sb4$ production pathways between sites. Greater oxidation also reduced the CH$ sb4$ flux from shallow, vegetated sites. / A preliminary CH$ sb4$ budget for the BOREAS northern study area indicates that beaver ponds contribute significantly (6% to 30%) to the regional CH$ sb4$ flux. The areal extent of beaver ponds needs to be determined for inclusion in regional and global CH$ sb4$ budgets.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.23883 |
| Date | January 1995 |
| Creators | Dove, Alice E. |
| Contributors | Roulet, N. T. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Geography.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001487443, proquestno: MM12183, Theses scanned by UMI/ProQuest. |
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