Diffusive and ebullitive transport of methane and nitrous oxide from streams: Are bubble-mediated fluxes important?
Article first published online: 15 DEC 2011
Copyright 2011 by the American Geophysical Union
Journal of Geophysical Research: Biogeosciences (2005–2012)
Volume 116, Issue G4, December 2011
How to Cite
2011), Diffusive and ebullitive transport of methane and nitrous oxide from streams: Are bubble-mediated fluxes important?, J. Geophys. Res., 116, G04028, doi:10.1029/2011JG001656., , , and (
- Issue published online: 15 DEC 2011
- Article first published online: 15 DEC 2011
- Manuscript Accepted: 28 SEP 2011
- Manuscript Revised: 12 JUL 2011
- Manuscript Received: 14 JAN 2011
- nitrous oxide;
- surface aeration
 Using measured rates of bubble release and diffusive gas transport (also termed surface aeration), we address the role of these transport mechanisms in emissions of nitrous oxide and methane from four streams. While ebullition in streams and rivers has received little study, we found that ebullition was an important mode of methane emissions, contributing 20%–67% of methane emissions (among streams). Nitrous oxide emissions via ebullition were negligible (<0.1% of diffusive emissions). Total methane emissions (ebullition + diffusive transport) were over ten times greater than N2O emissions in terms of CO2 equivalents. Rates of bubble release were highly variable, ranging from 20 mL m−2 d−1 to 170 mL m−2 d−1 (seasonal average among streams, with volumes reflecting ambient temperature and pressure). Methane was the most abundant of the bubble gases that were measured (26% by volume on average among streams), followed by carbon dioxide (1% on average) then nitrous oxide. Average bubble nitrous oxide concentrations were below atmospheric mixing ratios for the majority of streams; however, one stream showed concentrations as high as 3600 ppbv. Sediment characteristics were strong predictors of bubble composition. Concentrations of methane and nitrous oxide were positively related to the proportion of fine sediments. High methane concentrations in bubbles were related to high sediment organic carbon.