The collection site of the raw material is situated at the lower river Po close to the city of Gorino. The site was approached by boat and the sediment taken from 2- 3m depth by means of a stainless-steel grab sampler. The sampled material was immediately passed through a 2 mm stainless-steel sieve and the fraction >2 mm (stones, mussel shells, etc.) was discarded. Following to the transport to the JRC premises at Ispra, the sediment was spread out in lx2x0.2m stainless-steel containers and air dried at ambient temperature, breaking the slowly forming lumps at regular time intervals for better drying.
The drying process was completed in a drying oven with circulating air, not exceeding 60°C for saving the organic phosphorus compounds. Weight ccnstancy was controlled at laboratory conditions. The dried material was passed through a RETSCH-jaw crusher, set at its smallest opening (lmm) and ground in a RETSCH-hammer mill equipped with tungsten carbide blades. The ground material was passed on a 90 µm stainless-steel sieve and the <90 µm fraction collected in a especially designed PVC-mixing drum. The material was homogenised for two weeks. In order to test the obtained homogeneity, ten subsamples of about 30 g were taken at different positions inside the mixing drum. From each bottle (subsample) a pellet was prepared and the pellets were analysed for a number of major, minor and trace elements by X-ray fluorescence spectrometry using a SIEMENS Sequential Spectrometer, calibration was assured by Certified Reference Materials.
keywords: Environmental material, Particulate matter, Soil/Sediment, Speciation analysis, Phosphorous speciation