Numerical modeling of methane venting from lake sediments
Name
707640117-MIT.pdf
Description
Full printable version
Size
4.23 MB
Format
Adobe PDF
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dec116cf58bef0f5706373c33823e6af
Author(s)
Scandella, Benjamin P. (Benjamin Paul)
Advisor(s)
Ruben Juanes.
Date Issued
2010
Publisher
Massachusetts Institute of Technology
Abstract
The dynamics of methane transport in lake sediments control the release of methane into the water column above, and the portion that reaches the atmosphere may contribute significantly to the greenhouse effect. The observed dynamics are poorly understood. In particular, variations in the hydrostatic load on the sediments, from both water level and barometric pressure, appear to trigger free gas bubbling (ebullition). We develop a model of methane bubble ow through the sediments, forced by changes in hydrostatic load. The mechanistic, numerical model is tuned to and compared against ebullition data from Upper Mystic Lake, MA, and the predictions match the daily temporal character of the observed gas releases. We conclude that the combination of plastic gas cavity deformation and ow through "breathing" gas conduits explains methane venting from lake sediments. This research lays the groundwork for integrated modeling of methane transport in the sediment and water column to constrain the atmospheric flux from methane-generating lakes.
Description
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2010.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 91-96).
Subjects
Civil and Environmental Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
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