Hydraulics are a first order control on CO2 efflux from fluvial systems

Long, H., Vihermaa, L., Waldron, S. , Hoey, T. , Quemin, S. and Newton, J. (2015) Hydraulics are a first order control on CO2 efflux from fluvial systems. Journal of Geophysical Research: Biogeosciences, 120(10), pp. 1912-1922. (doi:10.1002/2015JG002955)

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Abstract

Evasion of carbon dioxide (CO2) from fluvial systems is now recognized as a significant component of the global carbon cycle. However the magnitude of, and controls on, this flux remain uncertain and improved understanding of both are required to refine global estimates of fluvial CO2 efflux. CO2 efflux data show no pattern with latitude suggesting that catchment biological productivity is not a primary control and that an alternative explanation for inter-site variability is required. It has been suggested that increased flow velocity and turbulence enhance CO2 efflux, but this is not confirmed. Here, using contemporaneous measurements of efflux (range: 0.07 – 107 µmol CO2 m-2 s-1), flow hydraulics (mean velocity range: 0.03 – 1.39 m s-1) and pCO2 (range: 174 – 10712 µatm) at six sites, we find that flow intensity is a primary control on efflux across two climatically different locations (where pH is not a limiting factor) and that the relationship is refined by incorporating the partial pressure of CO2 (pCO2) of the water. A remaining challenge is how to upscale from point to reach or river basin level. Remote imaging or river surface may be worth exploring if subjectivity in interpreting surface state can be overcome.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Waldron, Professor Susan and Newton, Dr Jason and Vihermaa, Dr Leena and Hoey, Professor Trevor
Authors: Long, H., Vihermaa, L., Waldron, S., Hoey, T., Quemin, S., and Newton, J.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Journal of Geophysical Research: Biogeosciences
Publisher:American Geophysical Union
ISSN:2169-8953
ISSN (Online):2169-8961
Published Online:01 September 2015
Copyright Holders:Copyright © 2015 The Authors
First Published:First published in Geophysical Research 120(10):1912-1922
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
467662Amazon Integrated Carbon Analysis (AMAZONICA)Susan WaldronNatural Environment Research Council (NERC)NE/F005482/1SCHOOL OF GEOGRAPHICAL & EARTH SCIENCES
613121NERC DTG 2012-2016Mary Beth KneafseyNatural Environment Research Council (NERC)NE/K501098/1VICE PRINCIPAL RESEARCH & ENTERPRISE