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The intercomparison exercise discussed in this report is the second AQUACON exercise considering samples with concentrations close to those of natural freshwater, and including algal nutrients such as reactive phosphorus and silica. Artificial surface water samples, with concentrations close to the values ordinarily measured in nature and solutions of ammonium chloride, potassium di-hydrogen phosphate, creatinine, glucose 1-phosphate di-sodium salt and sodium esafluorosilicate, stabilized with chloroform and sulphuric acid to pH 3.5 were prepared and checked for homogeneity and stability in time. 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 the number of outliers is relatively low, but there is a wide dispersion of the values around the expected concentrations. Several results showed marked differences in the ionic balance and between measured and calculated conductivity. The Youden graphs showed the prevalence of systematic over random errors for most of the chemical variables examined.

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 18075 EN (1998) 66pp., free of charge
Availability: Available from the Public Relations and Publications Unit, JRC Ispra, I-21020 Ispra (IT), Fax: +39-0332-785818
Record Number: 199810868 / Last updated on: 1998-08-04
Original language: en
Available languages: en