Selection and evaluation of sequential extraction procedures for the determination of phosphorus forms in lake sediment

In order to achieve comparable measurements in the determination of phospha te forms in freshwater sediments, the Standards, Measurements and Testing P rogramme (formerly BCR) of the European Commission has launched a project t he first step of which was to select and evaluate collaboratively existing extraction procedures. This was carried out through expert consultations an d a literature survey, and was followed by the organisation of a first inte rlaboratory study for the evaluation of four sequential extraction schemes, one of which was selected as the most promising method for achieving compa rability. This scheme, a modified version of the Williams protocol, was fur ther tested in a second interlaboratory study. The so-called SMT extraction scheme seems promising and will provide, in the near future, a valuable to ol for water managers in the field of lake restoration. It will be particul arly helpful in estimating the stock of P potentially available, hence the risk of eutrophication due to internal P release.