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Technical Note: Large overestimation of pCO2 calculated from pH and alkalinity in acidic, organic-rich freshwaters

dc.rights.licenseopenen_US
hal.structure.identifierEnvironnements et Paléoenvironnements OCéaniques [EPOC]
dc.contributor.authorABRIL, Gwenaël
dc.contributor.authorBOUILLON, S.
dc.contributor.authorDARCHAMBEAU, François
dc.contributor.authorTEODORU, Cr R.
dc.contributor.authorMARWICK, Tr R.
dc.contributor.authorTAMOOH, F.
dc.contributor.authorOCHIENG OMENGO, F.
dc.contributor.authorGEERAERT, N.
hal.structure.identifierEnvironnements et Paléoenvironnements OCéaniques [EPOC]
dc.contributor.authorDEIRMENDJIAN, Loris
hal.structure.identifierEnvironnements et Paléoenvironnements OCéaniques [EPOC]
dc.contributor.authorPOLSENAERE, Pierre
dc.contributor.authorBORGES, Alberto V.
dc.date.accessioned2024-05-02T09:00:32Z
dc.date.available2024-05-02T09:00:32Z
dc.date.issued2014-07-31
dc.identifier.urihttp://www.biogeosciences.net/12/67/2015/bg-12-67-2015.html
dc.identifier.urihttp://www.biogeosciences-discuss.net/11/11701/2014/bgd-11-11701-2014.html
dc.identifier.urioai:crossref.org:10.5194/bg-12-67-2015
dc.identifier.urihttps://pub.orcid.org/v2.1/0000-0002-5720-9951/work/53035248
dc.identifier.uriftcopernicus:oai:publications.copernicus.org:bg2444
dc.identifier.uriftcopernicus:oai:publications.copernicus.org:bgd2733
dc.identifier.uriftorbi:oai:orbi.ulg.ac.be:2268/175879
dc.identifier.urioai:researchgate.net:269956827
dc.identifier.urioai:crossref.org:10.5194/bgd-11-11701-2014
dc.identifier.urihttps://oskar-bordeaux.fr/handle/20.500.12278/199566
dc.description.abstractEnAbstract. Inland waters have been recognized as a significant source of carbon dioxide (CO2) to the atmosphere at the global scale. Fluxes of CO2 between aquatic systems and the atmosphere are calculated from the gas transfer velocity and the water–air gradient of the partial pressure of CO2 (pCO2). Currently, direct measurements of water pCO2 remain scarce in freshwaters, and most published pCO2 data are calculated from temperature, pH and total alkalinity (TA). Here, we compare calculated (pH and TA) and measured (equilibrator and headspace) water pCO2 in a large array of temperate and tropical freshwaters. The 761 data points cover a wide range of values for TA (0 to 14 200 μmol L−1), pH (3.94 to 9.17), measured pCO2 (36 to 23 000 ppmv), and dissolved organic carbon (DOC) (29 to 3970 μmol L−1). Calculated pCO2 were >10% higher than measured pCO2 in 60% of the samples (with a median overestimation of calculated pCO2 compared to measured pCO2 of 2560 ppmv) and were >100% higher in the 25% most organic-rich and acidic samples (with a median overestimation of 9080 ppmv). We suggest these large overestimations of calculated pCO2 with respect to measured pCO2 are due to the combination of two cumulative effects: (1) a more significant contribution of organic acids anions to TA in waters with low carbonate alkalinity and high DOC concentrations; (2) a lower buffering capacity of the carbonate system at low pH, which increases the sensitivity of calculated pCO2 to TA in acidic and organic-rich waters. No empirical relationship could be derived from our data set in order to correct calculated pCO2 for this bias. Owing to the widespread distribution of acidic, organic-rich freshwaters, we conclude that regional and global estimates of CO2 outgassing from freshwaters based on pH and TA data only are most likely overestimated, although the magnitude of the overestimation needs further quantitative analysis. Direct measurements of pCO2 are recommended in inland waters in general, and in particular in acidic, poorly buffered freshwaters.
dc.description.sponsorshipCOntinental To coastal Ecosystems: evolution, adaptability and governance - ANR-10-LABX-0045en_US
dc.language.isoENen_US
dc.sourcecrossref
dc.sourceorcid
dc.sourcebase
dc.sourceresearchgate
dc.title.enTechnical Note: Large overestimation of pCO2 calculated from pH and alkalinity in acidic, organic-rich freshwaters
dc.typeArticle de revueen_US
dc.subject.halSciences de l'environnementen_US
bordeaux.journalBiogeosciencesen_US
bordeaux.hal.laboratoriesEPOC : Environnements et Paléoenvironnements Océaniques et Continentaux - UMR 5805en_US
bordeaux.institutionUniversité de Bordeauxen_US
bordeaux.institutionCNRSen_US
bordeaux.teamECOBIOCen_US
bordeaux.peerReviewedouien_US
bordeaux.inpressnonen_US
bordeaux.import.sourcedissemin
hal.identifierhal-04565795
hal.version1
hal.date.transferred2024-05-02T09:00:35Z
hal.popularnonen_US
hal.audienceInternationaleen_US
hal.exporttrue
workflow.import.sourcedissemin
dc.rights.ccCC BYen_US
bordeaux.COinSctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=Biogeosciences&rft.date=2014-07-31&rft.au=ABRIL,%20Gwena%C3%ABl&BOUILLON,%20S.&DARCHAMBEAU,%20Fran%C3%A7ois&TEODORU,%20Cr%20R.&MARWICK,%20Tr%20R.&rft.genre=article


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