Gas sampling was performed with floating chambers adapted from field static chamber (Environment Agency, 2010 ) in which the gaseous matrix volume was sampled in triplicate, in intervals of 5, 10, and 15 min, stored at room temperature, and transported to the laboratory. The CH
4 and CO
2 concentrations were determined in mg m
2 h
–1, through Gas Chromatography–Flame Ionization Detector (GC-FID, Varian
CP 8400, United States) (Yuesi and Yinghong, 2003 (
link)), and converted to gas flow rate express in mg m
–2 d
–1, calculated from emission rates of the compounds in the static chamber, from the rate of change in the species concentration determined by GC-FID and with sampling intervals in the chamber using the first Fick’s law, as follows (Venterea, 2010 (
link)):
Where:
F is the flow of gases on the water surface (mg m
–2 d
–1); ρ is the specific mass of the air according to the temperature during the sampling (mg m
–3);
V is the internal volume of the chamber (m
3);
A is the surface area of the chamber exposed to water (m
2); and (dC/dt) is the concentration gradient of the target species as a function of sampling intervals. The estimated CH
4 flow rate limit of detection was 120 mg m
–2 d
–1.
Pierangeli G.M., Domingues M.R., de Jesus T.A., Coelho L.H., Hanisch W.S., Pompêo M.L., Saia F.T., Gregoracci G.B, & Benassi R.F. (2021). Higher Abundance of Sediment Methanogens and Methanotrophs Do Not Predict the Atmospheric Methane and Carbon Dioxide Flows in Eutrophic Tropical Freshwater Reservoirs. Frontiers in Microbiology, 12, 647921.
