On April 23, 2014 the in situ Interlaboratory comparison measurement (ILC) of dissolved oxygen concentration Fieldoxy 2014, organised jointly by the Finnish Environmental Institute (SYKE) and University of Tartu (UT) took place in the Gulf of Finland, on board of SYKE’s research vessel Aranda. The intercomparison was organised in the framework of the EMRP ENV05 Ocean project funded within the framework of the European Metrology Research Programme (EMRP). There were altogether 20 participants from 10 research institutes from 5 countries (Finland, Estonia, Sweden, France, Germany).
The role of University of Tartu in the intercomparison was to provide reliable reference values for the intercomparison, against which the results of the participants could be assessed. This was done using the modified highly accurate Winkler titration procedure developed previously at UT in the framework of the same project. The main modification were (1) using high-precision piston burette instead of weighing (it is not possible to accurately weigh on a ship) and (2) taking into account the uncertainty due to possible oxidizing or reducing impurities ion the seawater. In addition to the measurement uncertainty sources intrinsic in the procedure, the uncertainty due to spatial inhomogeneity of seawater around the rosette sampler (see presentation slides) was taken into account. This uncertainty contribution was found to be very important (it was the dominant uncertainty source at two immersion depths out of three).
On June 16, 2014 the coordinator from SYKE, Teemu Näykki, made a presentation on the preliminary results of the Fieldoxy 2014 intercomparison at the project meeting of ENV 05. The results show good agreement between the results of the participants and the reference values. In particular, and very importantly, there was no bias evident between the reference values and the participant results.
For comprehensive results of the intercomparison please see the final report of the Fieldoxy 2014 intercomparison.
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Organization of this intercomparison has been partly funded by the European Metrology Research Programme (EMRP), project ENV05 “Metrology for ocean salinity and acidity”. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union.
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