Supplement of Biogeosciences, 13, 3777–3791, 2016 http://www.biogeosciences.net/13/3777/2016/ doi:10.5194/bg-13-3777-2016-supplement © Author(s) 2016. CC Attribution 3.0 License.
Supplement of Summer fluxes of methane and carbon dioxide from a pond and floating mat in a continental Canadian peatland
Magdalena Burger et al.
Correspondence to: Christian Blodau ([email protected])
The copyright of individual parts of the supplement might differ from the CC-BY 3.0 licence. 1 1. Chamber flux measurements
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4.5 5.0 4.5 (B) (C) 4.0 4.5 4.0 3.5 4.0 3.5 3.0 3.5 3.0
2.5 3.0(ppm) ratio mixing 2.5 4 concentration (ppm) concentration
concentration (ppm) concentration 4
4 2.0 2.5CH 2.0 CH
CH 0 100 200 0 100 200 2 time (s) time (s)
3 Figure S1. Set-up of flux measurements on the pond including the floating boardwalk and 4 chamber (A). Example of a concentration time series with a constant slope representing 5 diffusive CH 4 flux or continuous flux of micro-bubbles (panel B) and example of a 6 concentration time series including a CH 4 bubble event visible by a sudden increase of slope 7 over a short duration (panel C). 8
9 2. CO 2 flux calculation with the gradient method
10 CO 2 fluxes across the air-water interface were estimated according to the boundary layer equation 11 approach, equation (1). (1) 12 F = k ∙ (c − c ) −2 −1 F CO 2 flux (mmol m h ) −1 k gas transfer velocity (m h ) c CO 2 concentration in the surface water (mmol m−3)
c theoretical CO 2 concentration of the surface water in equilibrium
with the atmospheric CO 2 concentration (mmol m−3)
13 c and c were calculated with Henry’s law from the CO 2 mixing ratios measured in the surface 14 water and the atmosphere using Henry’s law constants (Sander, 1999) corrected for surface water temperature. The gas transfer velocity was calculated from the gas transfer velocity normalized 15 k
16 to a Schmidt number of 600 ( k ) according to equation (2) (Crusius and Wanninkhof, 2003). 17 k = k ∙ ( ) (2) −1 k gas transfer velocity (m h ) k gas transfer velocity normalized to a Schmidt number of 600 (m h−1)
Sc Schmidt number for CO 2 corrected for temperature (−)
600 Schmidt number of CO 2 at 20 °C B for wind speed > 3 m s−1 for wind speed ≤ 3 m s−1
1 k depends on the wind speed at a height of 10 m according to the empirical relationship defined by Cole and Caraco (1998) (equation 3). was calculated as a function of water temperature 2 Sc 3 (equation 5; Wanninkhof, 1992). 4 . 5 k = 0.0207 +0.00215∙ U (3) k gas transfer velocity normalized to a Schmidt number of 600 (m h−1) −1 U wind speed at 10 m height (m s )