In the framework of the European Metrology Research Programme (EMRP) project ENV05 OCEAN (Metrology for ocean salinity and acidity), the dissolved oxygen field (in situ) intercomparison (FieldOxy 2014) test was organized onboard R/V Aranda on April 23, 2014 in the Gulf of Finland. The aim of the intercomparison was to enable the participants to assess their performance in measuring dissolved oxygen concentration in seawater under field conditions. The intercomparison measurement was organized jointly by the Finnish Environment Institute (Proftest SYKE. Envical SYKE) and University of Tartu.
Total of 21 participants from 10 institutes in Finland, Estonia, France, Germany and Sweden participated in the intercomparison. Totally, 13-18 oxygen sensors were tested depending of the test depth. Additionally, six Winkler titrimetric setups participated in the intercomparison. The metrologically traceable Winkler titration result (the assigned value) was measured by the Winkler setup of University of Tartu onboard R/V Aranda.
In total, 88 % of the results were satisfactory when total deviation of 8 % from the assigned values were accepted. Only three results were questionable and five results were unsatisfactory. A possible reason for several of the unsatisfactory results might be problems with calibration of electrochemical oxygen sensors. The movement of the water during the PT may have been insufficient for the electrochemical sensors, which may have resulted biased measurement results. Overall the share of satisfactory results was very good
