Atmospheric deposition and soil solution Working Ring Test 2005. Laboratory ring test for deposition and soil solution sample analyses between the countries participating in the ICP forests level II monitoring programme

Abstract

Working Ring Test (WRT) was organised in the framework of the EU Regulation (EC) No 2152/2003 ("Forest Focus") and of the UN/ECE Program "ICP Forests" in order to evaluate the overall performance of the laboratories monitoring atmospheric deposition and soil solution in European Forests, and to verify the improvement in the analytical quality as the results of the QA/QC work carried out in the laboratories which participated to a previous WRT. Seven natural samples of atmospheric deposition and soil solutions and 5 synthetic solutions were distributed to 52 laboratories, which analysed them using their routine method for the following variables: pH, conductivity, calcium, magnesium, sodium, potassium, ammonium, sulphate, nitrate, chloride, total alkalinity, phosphate, total dissolved nitrogen, dissolved organic carbon, aluminium, copper, iron, manganese, zinc, total phosphorus, total sulphur and silica. For each variable, a Data Quality Objective was defined, based on the results of the previous WRT, the comparison with the DQOs of other international networks, and the importance of the variable in deposition and soil solution monitoring. It resulted that 38% of the results do not meet the DQO, showing for which variables and in which laboratories improvement in analytical performance is needed. The results of the exercise clearly show that the use of data check procedures, as those described in the ICP Forests manual for sampling and analysis of atmospheric deposition, would make it possible to detect the presence of outliers or results not accurate, and would greatly improve the overall performance of the laboratories. Some analytical methods were found not suitable to the samples used in this WRT, nor to atmospheric deposition samples in European forests, and they include outdated methods, such as turbidimetry or nephelometry for the determination of sulphate, silver nitrate titration and ion selective electrode for chloride, Kjeldahl digestion for the determination of ammonium and organic nitrogen, and colorimetric titrations for alkalinity. A detailed discussion of the analyses of total dissolved nitrogen, dissolved organic carbon and total alkalinity is also provided, as they were the variables for which more analytical difficulty arose. Finally, a comparison between the results of this WRT and those of the previous exercise showed that the analytical performance of the laboratories participating in both WRTs improved as a consequence of the adoption of QA/QC procedures.

Referanse

Marchetto, A., Mosello, R., Tartari, G., Derome, J., Derome, K., Sorsa, P., König, N., Clarke, N., Ulrich, E. & Kowalska, A. 2006. Atmospheric deposition and soil solution Working Ring Test 2005. Laboratory ring test for deposition and soil solution sample analyses between the countries participating in the ICP forests level II monitoring programme. Office National des Forêts, Fontainebleau. 85 pp. ISBN 2-84207-310-X.