Estimation of sampling uncertainty in lake-water monitoring in a collaborative field trial
Abstract
A collaborative sampling trial was performed by AQUAREF (French national reference laboratory for water and the aquatic environment) at Paladru Lake, Isere, France. This trial was the first national test aiming at improving knowledge of the effect, in lake water, of sampling on global uncertainty. Ten sampling teams regularly involved in Water Framework Directive monitoring of lake water were asked to participate, in agreement with the Regional Water Agencies. All the samples were collected and analyzed by INERIS in order to minimize the analytical impact on global uncertainty. The data treatment was performed according to standard NF ISO 5725-5. Overall results for a few metals (cobalt and nickel) showed predominance (> 90 %) of sampling uncertainty compared to analytical uncertainty. For other metals, the initial blank tests showed possible contamination of sampling systems, and really pointed to the importance of blank sampling. Finally, this trial highlighted the need for general guidelines for sampling that could minimize the risk of misclassification of lake-water status.