Methane emissions from a small wind shielded lake determined by eddy covariance, flux chambers, anchored funnels, and boundary model calculations: a comparison.

Lakes are large sources of methane, held to be responsible for 18% of the radiative forcing, to the atmosphere. Periods of lake overturn (during fall/winter) are short and therefore difficult to capture with field campaigns but potentially one of the most important periods for methane emissions. We studied methane emissions using four different methods, including eddy covariance measurements, floating chambers, anchored funnels, and boundary model calculations. Whereas the first three methods agreed rather well, boundary model estimates were 5-30 times lower leading to a strong underestimation of methane fluxes from aquatic systems. These results show the importance of ebullition as the most important flux pathway and the need for continuous measurements with a large footprint covering also shallow parts of lakes. Although fluxes were high, on average 4 mmol m(-2) d(-1) during the overturn period, water column microbial methane oxidation removed 75% of the methane and only 25% of potential emissions were released to the atmosphere. Hence, this study illustrates second the importance of considering methane oxidation when estimating the flux of methane from lakes during overturn periods.

[1]  B. Wehrli,et al.  Greenhouse gas emissions (CO2, CH4, and N2O) from several perialpine and alpine hydropower reservoirs by diffusion and loss in turbines , 2012, Aquatic Sciences.

[2]  W. Eugster,et al.  Eddy covariance flux measurements confirm extreme CH 4 emissions from a Swiss hydropower reservoir and resolve their short-term variability , 2011 .

[3]  David L. Valentine,et al.  A Persistent Oxygen Anomaly Reveals the Fate of Spilled Methane in the Deep Gulf of Mexico , 2011, Science.

[4]  Patrick M. Crill,et al.  Freshwater Methane Emissions Offset the Continental Carbon Sink , 2011, Science.

[5]  S. MacIntyre,et al.  Buoyancy flux, turbulence, and the gas transfer coefficient in a stratified lake , 2010 .

[6]  W. Eugster,et al.  Field intercomparison of two optical analyzers for CH 4 eddy covariance flux measurements , 2010 .

[7]  P. Crill,et al.  Methane emissions from Pantanal, South America, during the low water season: toward more comprehensive sampling. , 2010, Environmental science & technology.

[8]  W. Eugster,et al.  A fault-tolerant eddy covariance system for measuring CH4 fluxes. , 2010 .

[9]  T. Diem,et al.  Oxidation and emission of methane in a monomictic lake (Rotsee, Switzerland) , 2010, Aquatic Sciences.

[10]  B. Wehrli,et al.  Extreme methane emissions from a Swiss hydropower reservoir: contribution from bubbling sediments. , 2010, Environmental science & technology.

[11]  P. M. Lang,et al.  Observational constraints on recent increases in the atmospheric CH4 burden , 2009 .

[12]  M. Pace,et al.  Fates of methane from different lake habitats: Connecting whole‐lake budgets and CH4 emissions , 2008 .

[13]  R. Betts,et al.  Changes in Atmospheric Constituents and in Radiative Forcing. Chapter 2 , 2007 .

[14]  Roger I. Jones,et al.  Could bacterivorous zooplankton affect lake pelagic methanotrophic activity , 2007 .

[15]  H. Nykänen,et al.  Oxidation, efflux, and isotopic fractionation of methane during autumnal turnover in a polyhumic, boreal lake , 2007 .

[16]  J. Downing,et al.  The global abundance and size distribution of lakes, ponds, and impoundments , 2006 .

[17]  Anne Ojala,et al.  Methanotrophic activity in relation to methane efflux and total heterotrophic bacterial production in a stratified, humic, boreal lake , 2006 .

[18]  Jonathan J. Cole,et al.  Methane emissions from lakes: Dependence of lake characteristics, two regional assessments, and a global estimate , 2004 .

[19]  Richard A. Feely,et al.  A global ocean carbon climatology: Results from Global Data Analysis Project (GLODAP) , 2004 .

[20]  R. Wanninkhof,et al.  � 2003, by the American Society of Limnology and Oceanography, Inc. Gas transfer velocities measured at low wind speed over a lake , 2022 .

[21]  D. M. Rosenberg,et al.  Reservoir Surfaces as Sources of Greenhouse Gases to the Atmosphere: A Global Estimate , 2000 .

[22]  T. Kratz,et al.  Seasonal dynamics of carbon dioxide and methane in two clear-water lakes and two bog lakes in northern Wisconsin, U.S.A. , 1999 .

[23]  Jonathan J. Cole,et al.  Atmospheric exchange of carbon dioxide in a low‐wind oligotrophic lake measured by the addition of SF6 , 1998 .

[24]  Y. Nojiri,et al.  Oxidation of dissolved methane in a eutrophic, shallow lake: Lake Kasumigaura, Japan , 1998 .

[25]  Michael E. McDonald,et al.  Potential methane emission from north-temperate lakes following ice melt , 1996 .

[26]  Walter Senn,et al.  A cospectral correction model for measurement of turbulent NO2 flux , 1995 .

[27]  Michael J. Whiticar,et al.  Biogenic methane formation in marine and freshwater environments: CO2 reduction vs. acetate fermentation—Isotope evidence , 1986 .

[28]  J. Barker,et al.  Carbon isotope fractionation during microbial methane oxidation , 1981, Nature.

[29]  G. L. Hutchinson,et al.  Improved Soil Cover Method for Field Measurement of Nitrous Oxide Fluxes , 1981 .

[30]  S. Juutinen,et al.  Biogeosciences Methane dynamics in different boreal lake types , 2009 .

[31]  D. Schimel,et al.  Control of methane production in terrestrial ecosystems. , 1989 .

[32]  L. Merlivat,et al.  Air-Sea Gas Exchange Rates: Introduction and Synthesis , 1986 .

[33]  D. Wiesenburg,et al.  Carbon Monoxide, and Hydrogen , 1979 .

[34]  P. Liss,et al.  Flux of Gases across the Air-Sea Interface , 1974, Nature.