STUDY OF THE STABILITY OF EXTRACTABLE TRACE-METAL CONTENTS IN A RIVER SEDIMENT USING SEQUENTIAL EXTRACTION

Sequential extraction schemes have been used in recent years to study the environmental behaviour of trace metals present in soils and sediments. Owing to the variety of the different extraction procedures, the results obtained were not comparable as they were highly dependent on the procedure. Moreover, the lack of suitable reference materials for this type of analysis prevents quality control of the measurements. In 1987 the Community Bureau of Reference (BCR, now Measuring and Testing Programme) started a programme to harmonize the methodology and to produce certified reference materials. This paper presents the work carried out to prepare a river sediment sample to be analysed in an intercomparison exercise using a common sequential extraction scheme adopted at Sitges by a group of European experts. The studies of homogeneity and stability with time of the extractable trace metal contents in the sample are also reported.