Grain size analysis. A comparison between laser granulometer and sedigraph

A total of 24 sediment samples from 5 different Italian marine sites (4 from Tyrrhenian Sea and 1 from Adriatic Sea) were analyzed for grain size using two different instruments: Laser Granulometer (LG) and X-ray Sedigraph (XS). The analysis was carried out exclusively on the fine fraction (<63 m), obtained by dry sieving, in order to compare data results and highlight potential differences. The results show an increase of 15-25% of clay content in the samples analyzed by XS with respect to the ones analyzed by LG. In spite of analyzing the <63 m fraction, both instruments recorded the presence of variable amount of sand in most samples, with high percentages (up to 53.3% for XS and 30% for LG) in the Bagnoli samples. The different results supplied by the two instruments may be attributed to the different principles of functioning of the two instruments and to the peculiar physical properties of the particles such as shape, density and mineralogical composition.