Ocean Science
Ocean Science
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Articles | Volume 22, issue 1
Articles | Volume 22, issue 1
https://doi.org/10.5194/os-22-75-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/os-22-75-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
Articles | Volume 22, issue 1
Research article
 | 
08 Jan 2026
Research article |  | 08 Jan 2026

Metrological concepts applied to Total Alkalinity measurements in seawater: reference materials, inter-laboratory comparison and uncertainty budget

Gaëlle Capitaine, Samir Alliouane, Thierry Cariou, Jonathan Fin, Paola Fisicaro, and Thibaut Wagener

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Cited articles

Acquafredda, M., Cochran, C., Busch, D. S., Jewett, L., Edmonds, H., and Dickson, A. G.: Understanding the Current Use and Future Needs of CO2 in Seawater Certified Reference Materials, NOAA Technical Memorandum OAR-OAP-5, https://doi.org/10.25923/ANC4-GJ33, 2022. 
Bockmon, E. E. and Dickson, A. G.: An inter-laboratory comparison assessing the quality of seawater carbon dioxide measurements, Marine Chemistry, 171, 36–43, https://doi.org/10.1016/j.marchem.2015.02.002, 2015. 
Boggs, P. T., Byrd, R. H., Rogers, J. E., and Schnabel, R. B.: User's reference guide for ODRPACK version 2.01::software for weighted orthogonal distance regression, NIST, https://doi.org/10.6028/nist.ir.4834, 1992. 
Capitaine, G., Fisicaro, P., and Wagener, T. Towards improved metrological traceability of seawater Total Alkalinity measurements: advancing assessment of Ocean Alkalinity Enhancement, in preparation, 2026. 
Dickson, A. G.: An exact definition of total alkalinity and a procedure for the estimation of alkalinity and total inorganic carbon from titration data, Deep Sea Research Part A. Oceanographic Research Papers, 28, 609–623, https://doi.org/10.1016/0198-0149(81)90121-7, 1981. 
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Measuring total alkalinity in seawater is essential for understanding and monitoring the ocean carbonate system. To improve the reliability of these measurements, we developed reference materials and tested them in an inter-laboratory comparison. We also thoroughly quantified, for the first time, the uncertainty of the standard measurement method. These results, as well as the key metrological tools developed, support more accurate long-term monitoring of the ocean carbonate system.
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