The relationship between near-surface turbulence and gas transfer velocity in freshwater systems and its implications for floating chamber measurements of gas exchange

• Published in: Limnology and oceanography Vol. 55; no. 4; pp. 1723 - 1732
• Main Authors: Vachon, Dominic, Prairie, Yves T., Cole, Jonathan J.
• Format: Journal Article
• Language: English
• Published: Waco, TX American Society of Limnology and Oceanography 01.07.2010
• Subjects: Earth sciences; Earth, ocean, space; Exact sciences and technology; Hydrology; Hydrology. Hydrogeology; Canada; Quebec; Eastern Canada; models; fresh-water environment; aquatic environment; air-water interface; reservoirs; gaseous phase; least-squares; velocity; turbulence; North America; energy dissipation; winds; lakes
• ISSN: 0024-3590; 1939-5590
• DOI: 10.4319/lo.2010.55.4.1723

We performed a series of gas exchange measurements in 12 diverse aquatic systems to develop the direct relationship between near-surface turbulence and gas transfer velocity. The relationship was log-linear, explained 78% of the variation in instantaneous gas transfer velocities, and was valid over a range of turbulent energy dissipation rates spanning about two orders of magnitude. Unlike wind-based relationships, our model is applicable to systems ranging in size from less than 1 km² to over 600 km². Gas fluxes measured with our specific model of floating chambers can be grossly overestimated (by up to 1000%), particularly in low-turbulence conditions. In high-turbulence regimes, flux overestimation decreases to within 50%. Direct measurements of turbulent energy dissipation rate provide reliable estimation of the associated gas transfer velocity even at short temporal and spatial scales.