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Enhancing surface methane fluxes from an oligotrophic lake: exploring the microbubble hypothesis
Environmental Science & Technology
|December 17, 2014
Summary
Microbubbles in Lake Stechlin significantly enhance methane (CH4) and carbon dioxide (CO2) gas transfer rates. This finding impacts our understanding of greenhouse gas emissions and aquatic carbon cycling.
Area of Science:
- Environmental Science
- Geochemistry
- Limnology
Background:
- Greenhouse gas exchange (CO2 and CH4) across inland waters is crucial for terrestrial carbon budgets.
- Understanding gas transfer mechanisms is key to accurate carbon balance assessments.
Purpose of the Study:
- To investigate the surface fluxes of carbon dioxide (CO2) and methane (CH4) in oligotrophic Lake Stechlin.
- To determine the role of microbubbles in modulating gas transfer rates.
Main Methods:
- Utilized a floating chamber technique to measure gas fluxes.
- Analyzed normalized gas transfer rates (k600) for CH4 and CO2.
Main Results:
- The methane transfer rate (k600,CH4) was 2.5 times higher than that for carbon dioxide (k600,CO2).
- Elevated CH4 flux is attributed to microbubbles in the surface layer, potentially from atmospheric entrainment or gas supersaturation.
- An estimated 145 L m(–2) d(–1) of gas must exit via microbubbles to explain the observed k600,CH4.
Conclusions:
- Microbubbles significantly influence gas exchange in inland waters, affecting CH4 and potentially overall carbon balances.
- The presence of microbubbles necessitates re-evaluation of gas transfer models and their application in aquatic systems.
- These findings have implications for other sparingly soluble gases like oxygen (O2) and nitrogen (N2).
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