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Updated: May 12, 2025
08:18
Design and Use of a Full Flow Sampling System FFS for the Quantification of Methane Emissions
Published on: June 12, 2016
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Fate of Dissolved Methane from Ocean Floor Seeps
Tor Nordam1,2, Anusha L Dissanayake3, Odd Gunnar Brakstad1
1SINTEF Ocean, 7010 Trondheim, Norway.
Environmental Science & Technology
|April 23, 2025
Summary
Seafloor methane seeps release greenhouse gases. Biodegradation in the water column significantly reduces methane release, especially at deeper locations, mitigating climate impact.
Area of Science:
- Environmental Science
- Oceanography
- Climate Science
Background:
- Methane is a potent greenhouse gas with higher global warming potential than carbon dioxide.
- Seafloor methane seeps, both natural and anthropogenic, are a potential source of atmospheric greenhouse gas emissions.
Purpose of the Study:
- To model the fate of methane released from seafloor seeps on the Norwegian continental shelf.
- To quantify methane biodegradation and its impact on atmospheric release.
Main Methods:
- Modeling of methane bubble dissolution, mixing, and biodegradation in seawater.
- Laboratory experiments using tritium-labeled methane to determine biodegradation rates.
- Analysis of methane fate across varying water depths and biodegradation half-lives.
Main Results:
- Biodegradation significantly reduces methane released from seeps.
- At 65m depth, 57-68% biodegradation occurs with a 9-16 day half-life.
- Deeper seeps (106m and 303m) show 75-83% and >99% biodegradation, respectively.
Conclusions:
- Water column biodegradation is a critical process controlling methane flux from seafloor seeps.
- The depth of the seep and the methane biodegradation rate are key factors in determining atmospheric methane release.
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