The Breath of Rivers

Rivers breathe: they emit carbon dioxide in different ways, depending on local environmental conditions, latitude, season, and time of day. These findings, stemming from the EURORUN project (Assessing CO2 Fluxes from European Running Waters), were published in a journal belonging to the Nature group in collaboration with 16 research groups from 11 European countries, with ALPSTREAM representing Italy.

Globally, inland waters emit over 2 Pg of carbon/year as CO2, most of which originates from streams and rivers. However, the daily dynamics of these fluxes remain poorly understood. The EURORUN project carried out a large-scale assessment of daytime and nighttime CO2 fluxes at the water-air interface across 34 European rivers. CO2 fluxes were measured during four sampling campaigns between October 2016 and July 2017 using specialized floating chambers. The average fluxes were 1.4 and 2.1 mmol m⁻² h⁻¹ at noon and midnight, respectively, with nighttime fluxes exceeding daytime fluxes by 39%. We attribute the variability in carbon dioxide flux primarily to changes in the partial pressure of carbon dioxide in the water. However, it was not possible to consistently identify the driving factors behind this phenomenon across the different sites. The results of this project highlighted the widespread day-night variations in riverine carbon dioxide fluxes, suggesting that the time of day significantly influences the measured CO2 fluxes across European rivers. Understanding the role of rivers in the complex carbon dioxide cycle is crucial under the current climate change scenario.

For further information:

• from site www.repubblica.it read the article

• from site www.lescienze.it read the article