Rivers and streams are significant sources of carbon dioxide and methane in the atmosphere. There is a lack of measurements from boreal ecosystems: controls and magnitude of these emissions remain highly uncertain. This study provides the longest carbon dioxide and the first ever methane flux dataset measured by the Eddy Covariance technique over a river (river Kitinen, northern Finland).
The river Kitinen was, on average, a source of carbon dioxide and methane for the atmosphere with the highest monthly fluxes occurring in July. The river acted occasionally as a net carbon dioxide sink briefly during the midday hours in June. The partial pressure of carbon dioxide in water, photosynthetically active radiation, water flow velocity, and wind speed largely explain patters of carbon dioxide mean fluxes. Methane fluxes were driven by water surface temperature and wind speed.
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