Grain size analysis of present-day silty bottom sediments by using laser diffraction and sieve methods
Combination of laser diffraction and wet sieving through nylon screen with a 0.1 mm mesh has been suggested for a grain-size analysis of the silty sediments from estuarine and coastal sea areas. The necessity of separate determination of sand fractions even at the technical potential of the device to analyze the content of the coarse particles of 2 mm to grain size is shown. This is related with bad sorting of coastal silts and inadequate representativeness of subsamples used for standard laser diffraction grain size analysis. In addition to sand fractions, the pre-sieving affects the determination of 0.1-0.01 mm silt fractions. At the same time, the effect on the analysis of < 0.01 mm pellite fractions is minimal. The effectiveness of the proposed modified method is supported by the improvement of the correlation between the content of pellite fractions and concentration in bottom sediments of metals and organic carbon.