Operationally-defined procedures (single or sequential extractions, leaching tests) are increasingly used for the evaluation of the mobility and bioavailability of contaminants (and related toxicity or nutritional capacity), and their potential risk for the environment. This approach has been widely used in soil studies for e.g. the prediction of agricultural crop deficiency or the assessment of toxical impact (contamination of groundwater through soil leaching); sequential extraction schemes have also been widely applied to sediment analysis to study the mobility of heavy metals and their adsorption pattern, as well as to study risks of eutrophication of lakes. However, the lack of harmonisation of these schemes does not enable results to be compared which render difficult any attempts to evaluate environmental risks. The European Commission (through the BCR programme) has contributed to the establishment of common methodologies which were tested and accepted by expert EU laboratories for soil (single extraction) and sediment (sequential extraction) analysis. Much remains to be done, however, to improve these schemes which are prone to errors owing to their heavy handling procedures.
The project aims to improve existing single and sequential extraction schemes used for soil and sediment analysis for heavy metal monitoring and to compare existing sequential extraction schemes used for the determination of forms of phosphate in order to develop standardized procedures for their possible implementation as standards.
The first phase of the project has consisted in testing various parameters (e.g. effects of pH, shaking speed, temperature) in order to establish common protocols (single and sequential extractions) to be tested in interlaboratory studies of which the results were evaluated in December 1997.
Following the test on existing procedures, samples will be distributed to EU laboratories (ca. 20 participants from various EU Member States) for an interlaboratory assessment. The project will be pursued by a tentative certification of extractable heavy metal forms in soil and sediment reference materials, and of extractable phosphate forms in a sediment reference material.
Funding SchemeCSC - Cost-sharing contracts