Grain-size analysis of lacustrine sediments: a comparison of pre-treatment methods; pp. 231–243

Abstract

This study presents the results of an experimental investigation of five different pre-treatment methods for measuring the grain-size distribution of allochthonous siliclastic matter in cohesive organic-rich sediments and some comparisons with mineral-rich sediments. The loss on ignition (LOI) methods were the fastest for eliminating organic matter but here a problem of aggregate formation may arise. Oxidation with H2O2 was time and resource consuming. Getting reproducible results was hard and the reaction was not completed for grain-size analysis. Therefore the samples were also treated and carbonates were removed with HCl. It was also very important to remove biogenic silica by alkali treatment. The median values in grain-size spectra had trends towards finer grain size after treatment with KOH and observations with light microscope showed changes during treatments. The grain-size distribution measured by a laser particle sizer differed considerably between the five pre-treatment methods studied.