Quantifying uncertainty of the reference sampling procedure used at Dornach under different soil conditions.

The reference sampling procedure, used in the CEEM soil project on a single test area at Dornach, had been applied under different soil conditions in a sampling proficiency test and in the Swiss national soil-monitoring network related to pollution (NABO). Methods of analysis of variance (ANOVA) were used to quantify sampling and analytical uncertainty. The soil sampling procedure and the chemical analysis were considered as two parts of the same measurement process and the so-called 'top-down' approach was used to quantify their combined contribution to the uncertainty. By this approach a systematic error of one sampler or of one laboratory becomes a random error when assessed as part of a multi-sampler or multi-laboratory comparison.