Persistence of bubble outlets in soft, methane-generating sediments
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Juanes_Persistence of bubble.pdf
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2.69 MB
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Author(s)
Scandella, Benjamin
Delwiche, Kyle Brook
Hemond, Harold F
Juanes, Ruben
Date Issued
April 2017
Journal
Journal of Geophysical Research: Biogeosciences
Publisher
American Geophysical Union (AGU)
Citation
Scandella, Benjamin P.; Delwiche, Kyle; Hemond, Harold F. and Juanes, Ruben. “Persistence of Bubble Outlets in Soft, Methane-Generating Sediments.” Journal of Geophysical Research: Biogeosciences 122 (June 2017): 1-26. © 2017 American Geophysical Union
Version
Final published version
Abstract
Sediments submerged beneath many inland waterways and shallow oceans emit methane, a potent greenhouse gas, but the magnitude of the methane flux to the atmosphere remains poorly constrained. In many settings, the majority of methane is released through bubbling, and the spatiotemporal heterogeneity of this ebullition both presents challenges for measurement and impacts bubble dissolution and atmospheric emissions. Here we present laboratory-scale experiments of methane ebullition in a controlled incubation of reconstituted sediments from a eutrophic lake. Image analysis of a 0.14 m2 sediment surface area allowed identification of individual bubble outlets and resolved their location to ∼1 cm. While ebullition events were typically concentrated in bursts lasting ∼2 min, some major outlets showed persistent activity over the scale of days and even months. This persistence was surprising given the previously observed ephemerality of spatial structure at the field scale. This persistence suggests that, at the centimeter scale, conduits are reopened as a result of a drop in tensile strength due to deformation of sediments by the rising bubbles. The mechanistic insight from this work sheds light on the spatiotemporal distribution of methane venting from organic-rich sediments and has important implications for bubble survival in the water column and associated biogeochemical pathways of methane.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1002/2016jg003717
