Dynamics of methane emissions in beaver ponds
Methane (CH4) is a greenhouse gas that is 23 times stronger than CO2. In freshwater ecosystems, it is produced by anaerobic decomposition of organic matter and it is emitted by three processes: diffusion, ebullition (bubbling) and transport by plants. Bubbling may represent the majority of methane emissions; however, because of sampling difficulties and large variability, few studies have measured the ebullition in lakes and wetlands.
My research interests focus mainly on the dynamics of methane emissions in beaver ponds. Beaver ponds represent about 5 to 10% of all boreal wetlands but, according to several studies, these systems may be an important source of methane at the regional scale. The objectives of my project are therefore 1) to quantify methane emissions from beaver ponds, 2) to determine the importance of emissions via ebullition and diffusion, and 3) to identify the factors controlling the importance of these emissions.
I predict that a large proportion of the spatial variability in bubbling events can be explained by changes in atmospheric pressure and variations in water level, which lead to differences in hydrostatic pressure. In addition, I expect to explain a significant proportion of the seasonal variability in total methane emissions by differences in sediment temperature.
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