Release of multiple bubbles from cohesive sediments

• Published in: Geophysical research letters Vol. 38; no. 8; pp. np - n/a
• Main Authors: Algar, Christopher K., Boudreau, Bernard P., Barry, Mark A.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 28-04-2011; American Geophysical Union; John Wiley & Sons, Inc
• Subjects: Air pollution; Biological oceanography; Bubbles; Chemical oceanography; Climate change; Cohesive sediments; Earth sciences; Earth, ocean, space; ebullition; Exact sciences and technology; facture; Flux; Fracture mechanics; Geochemistry; Geophysics; Greenhouse gases; Lookouts; Marine; Marine geology; Mathematical models; methane; Sedimentary geology; Sediments; tides; North Carolina; Cape Lookout; United States; Carteret County North Carolina; atmosphere; Mechanical model; North America; tides; greenhouse gas; fracturing; wetlands; methane; prediction; warming; growth; bubbles; fractures; climate change
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2011GL046870

Methane is a strong greenhouse gas, and marine and wetland sediments constitute significant sources to the atmosphere. This flux is dominated by the release of bubbles, and quantitative prediction of this bubble flux has been elusive because of the lack of a mechanistic model. Our previous work has shown that sediments behave as elastic fracturing solids during bubble growth and rise. We now further argue that bubbles can open previously formed, partially annealed, rise tracts (fractures) and that this mechanism can account for the observed preferential release at low tides in marine settings. When this mechanical model is applied to data from Cape Lookout Bight, NC (USA), the results indicate that methanogenic bubbles released at this site do indeed follow previously formed rise tracts and that the calculated release rates are entirely consistent with the rise of multiple bubbles on tidal time scales. Our model forms a basis for making predictions of future bubble fluxes from warming sediments under the influence of climate change.
Key Points
Bubbles in sediments can grow on tidal time scales
They can do so because they grow by re‐opening previous fracture trails
We can explain the bubble release observed at Cape Lookout Bight