Aarhus Universitets segl

No. 622: Intercalibration of marine analytical methods 2006

Hjorth, M., Vang, T., Nørgaard, F., Boel, B. & Ærtebjerg, G. 2007 – NERI Technical Report no. 622, 65 pp.

 

Summary

 

This report presents the results from an intercalibration carried out at Nyborg in June 2006, where 18 measurement teams on 16 small and medium-sized monitoring ships conducted a comprehensive field and laboratory program.

 

The measurements were generally very accurate, although some problems existed in relation to certain parameters. Measurements of salinity, temperature and O2 with a CTD were of high quality and within the set criteria. Estimations of sampling depth were markedly improved compared to the previous intercalibration. Measurements of oxygen, fluorescence and light attenuation were also within the quality criteria. However, it should be noted that oxygen should still be measured by Winkler titration and fluorescence data are only valid as relative measures but are relevant for determination of the depth of chlorophyll maximum. The quality of measurements of chlorophyll a, nutrients and primary production done by the chosen laboratories of the counties were evaluated. Chlorophyll a and nutrient analyses varied considerably due to contamination and methodological errors. A more thorough guidance in the used methods to the laboratories is recommended together with an increased focus on uniform sampling and subsequent handling. Primary production measurements were reliable and the quality criteria were met in the somewhat diminished data set. Specifically for primary production it is recommended that the intercalibration is followed up by a test of calculations. For all the data from the laboratories, the outcome of the intercalibration could be improved if all quality control data were available.

 

Full report in pdf-format (3.247 kB)