Ocean Science www.ocean-sci.net 1812-0784 1812-0792 5 4 2009 10.5194/os-5-547-2009 http://www.ocean-sci.net/5/547/2009/ http://www.ocean-sci.net/5/547/2009/os-5-547-2009.html http://www.ocean-sci.net/5/547/2009/os-5-547-2009.pdf 547 558 2009-11-10 Sensors and instruments for oceanic dissolved carbon measurements U. Schuster u.schuster@uea.ac.uk A. Hannides L. Mintrop A. Körtzinger University of East Anglia, School of Environmental Sciences, Norwich, NR4 7TJ, UK Department of Fisheries and Marine Research, Ministry of Agriculture, Natural Resources and the Environment, Nicosia, Cyprus MARIANDA, Marine Analytics and Data, Tulpenweg 28, Kiel, Germany Leibniz Institute of Marine Sciences, Chemical Oceanography, Düsternbrooker Weg 20, Kiel, Germany Highly accurate and precise measurements of marine carbon components are required in the study of the marine carbon cycle, particularly when investigating the causes for its variability from seasonal to interannual timescales. This is especially true in the investigation of the consequences of anthropogenic influences. <br><br> The analysis of any marine carbon component requires elaborate instrumentation, most of which is currently used onboard ships, either in manual or automated mode. Technological developments result in more and more instruments that have sufficient long-term reliability so that they can be deployed on commercial ships, surface moorings, and buoys, whilst the great technological and operational challenges mean that only few sensors have been developed that can be used for sub-surface in situ measurements on floats, robots, or gliders. There is a special need for autonomous instruments and sensors that are able to measure a combination of different components, in order to increase the spatial and temporal coverage of marine carbon data. <br><br> This paper describes analytical techniques used for the measurement of the marine dissolved carbon components, both inorganic and organic: the fugacity of CO₂, total dissolved inorganic carbon, pH, alkalinity, and dissolved organic carbon. By pointing out advantages, disadvantages, and/or challenges of the techniques employed in the analysis of each component, we aim to aid non-carbon marine scientists, sensor developers and technologists, in the decision of which challenges to address in further development. % vor jede Referenz Aluwihare, L. I., Repeta, D. J., and Chen, R. F.: A major biopolymeric component to dissolved organic carbon in surface sea water, Nature, 387, 166–169, 1997. Bauer, J. E., Williams, P. M., and Druffel, E. R. 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