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Global carbon dioxide efflux from rivers enhanced by high nocturnal emissions
Journal article   Peer reviewed

Global carbon dioxide efflux from rivers enhanced by high nocturnal emissions

Lluis Gomez-Gener, Gerard Rocher-Ros, Tom Battin, M Cohen, Higo J Dalmagro, Kerry J Dinsmore, Travis W Drake, Clément Duvert, Alex Enrich-Prast, Asa Horgby, …
Nature Geoscience, Vol.14(5), pp.289-294
31/05/2021
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Global carbon dioxide efflux from rivers enhanced by high nocturnal emissionsView
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UN Sustainable Development Goals (SDGs)

This output has contributed to the advancement of the following goals:

#6 Clean Water and Sanitation
#13 Climate Action
#14 Life Below Water

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Abstract

Earth and Related Environmental Sciences Geovetenskap och miljövetenskap Natural Sciences Naturgeografi Naturvetenskap Physical Geography
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). Failing to account for emission differences between day and night will lead to an underestimate of global CO2 emissions from rivers by up to 0.55 PgC yr(-1), according to analyses of high-frequency CO2 measurements.

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