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Title: Persistence of bubble outlets in soft, methane-generating sediments

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. In this paper, 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 m 2 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. Finally, 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 themore » water column and associated biogeochemical pathways of methane.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [1] ; ORCiD logo [2]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Civil and Environmental Engineering
  2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Civil and Environmental Engineering. Dept. of Earth, Atmospheric and Planetary Sciences
Publication Date:
Grant/Contract Number:
FE0013999; 1045193
Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Biogeosciences
Additional Journal Information:
Journal Volume: 122; Journal Issue: 6; Journal ID: ISSN 2169-8953
Publisher:
American Geophysical Union
Research Org:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Org:
USDOE Office of Fossil Energy (FE); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; methane venting; sediment; methanogenesis; incubation; experiment
OSTI Identifier:
1466702
Alternate Identifier(s):
OSTI ID: 1402403