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The intercomparison discussed in this report is the first AQUACON exercise considering samples with concentrations close to those of freshwater, and including algal nutrients such as reactive phosphorus and silica. A total of 124 laboratories sent back results. Artificial surface water samples, with concentrations close to the values ordinarily measured in nature and checked for homogeneity and stability. Results showed a high number of outliers in the measurements of ammonium, reactive phosphorus and nitrate, indicating a lack of precision which was more marked on the low concentration samples. With other variables (eg pH, conductivity, reactive silica, magnesium) the number of outliers is relatively low, but there is a wide dispersion of the values around the expected concentrations. The Youden graphs showed the prevalence of systematic over random errors for most of the chemical variables examined. Results obtained in this exercise, mainly those concerning algal nutrients, indicate the need for a continuation of the activity, with further exercises.

Additional information

Authors: MOSELLO R ET AL, Istituto Italiano di Idrobiologia, National Research Council, Verbania Pallanza (IT);BIANCHI M ET AL, JRC Ispra (IT)
Bibliographic Reference: EUR 17347 EN (1997) 52pp., FS, free of charge
Availability: Available from the Public Relations and Publications Unit, JRC Ispra, I-21020 Ispra (IT), Fax: +39-332-785818
Record Number: 199710822 / Last updated on: 1997-07-02
Original language: en
Available languages: en