Carbon dioxide fluxes increase from day to night across European streams
Katrin Attermeyer, Joan Pere Casas‐Ruiz, Thomas Fuß, Ada Pastor, Sophie Cauvy‐Fraunié, Danny Sheath, Anna Nydahl, A. Doretto, Ana Paula Portela, Brian C. Doyle, Nikolay Simov, Catherine Gutmann Roberts, Georg H. Niedrist, Xisca Timoner, Vesela Evtimova, Laura Barral-Fraga, Tea Bašić, Joachim Audet, Anne Deininger, Georgina Busst, Stefano Fenoglio, Núria Catalán, Elvira de Eyto, Francesca Pilotto, Jordi‐René Mor, J.L.F. Monteiro, David Fletcher, Christian Noß, Miriam Colls, Magdalena Nagler, Liu Liu, Clara Romero González‐Quijano, Ferran Romero, Nina Pansch, José L. J. Ledesma, Josephine Pegg, Marcus Klaus, Anna Freixa, Sonia Herrero Ortega, Clara Mendoza‐Lera, Adam Bednařík, Jérémy Fonvielle, Peter Gilbert, Lyubomir Kenderov, Martin Rulı́k, Pascal Bodmer
Abstract
Abstract Globally, inland waters emit over 2 Pg of carbon per year as carbon dioxide, of which the majority originates from streams and rivers. Despite the global significance of fluvial carbon dioxide emissions, little is known about their diel dynamics. Here we present a large-scale assessment of day- and night-time carbon dioxide fluxes at the water-air interface across 34 European streams. We directly measured fluxes four times between October 2016 and July 2017 using drifting chambers. Median fluxes are 1.4 and 2.1 mmol m −2 h −1 at midday and midnight, respectively, with night fluxes exceeding those during the day by 39%. We attribute diel carbon dioxide flux variability mainly to changes in the water partial pressure of carbon dioxide. However, no consistent drivers could be identified across sites. Our findings highlight widespread day-night changes in fluvial carbon dioxide fluxes and suggest that the time of day greatly influences measured carbon dioxide fluxes across European streams.