Global carbon dioxide efflux from rivers enhanced by high nocturnal emissions

Lluís Gómez-Gener, Gerard Rocher-Ros, Tom Battin, Matthew J. Cohen, Higo J. Dalmagro, Kerry J. Dinsmore, Travis W. Drake, Clément Duvert, Alex Enrich-Prast, Åsa Horgby, Mark S. Johnson, Lily Kirk, Fausto Machado-Silva, Nicholas S. Marzolf, Mollie J. McDowell, William H. McDowell, Heli Miettinen, Anne K. Ojala, Hannes Peter, Jukka PumpanenLishan Ran, Diego A. Riveros-Iregui, Isaac R. Santos, Johan Six, Emily H. Stanley, Marcus B. Wallin, Shane A. White, Ryan A. Sponseller

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Carbon dioxide (CO2) emissions to the atmosphere from running waters are estimated to be four times greater than the total carbon (C) flux to the oceans. However, these fluxes remain poorly constrained because of substantial spatial and temporal variability in dissolved CO2 concentrations. Using a global compilation of high-frequency CO2 measurements, we demonstrate that nocturnal CO2 emissions are on average 27% (0.9 gC m−2 d−1) greater than those estimated from diurnal concentrations alone. Constraints on light availability due to canopy shading or water colour are the principal controls on observed diel (24 hour) variation, suggesting this nocturnal increase arises from daytime fixation of CO2 by photosynthesis. Because current global estimates of CO2 emissions to the atmosphere from running waters (0.65–1.8 PgC yr−1) rely primarily on discrete measurements of dissolved CO2 obtained during the day, they substantially underestimate the magnitude of this flux. Accounting for night-time CO2 emissions may elevate global estimates from running waters to the atmosphere by 0.20–0.55 PgC yr−1.

    Original languageEnglish
    Pages (from-to)1-13
    Number of pages13
    JournalNature Geoscience
    DOIs
    Publication statusPublished - 15 Apr 2021

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