A comparison of four methods of size analysis of fine-grained sediments

Abstract

Four established methods of analysing particle sizes finer than 63 μm are compared: pipette, hydrometer, SediGraph, and hydrophoto-meter. Four samples were analysed: a high plasticity mud, a p-layer loess, a highly micaceous silt, and a synthetic pure quartz mud. All results of pipette and hydrometer analysis are close throughout the entire size range. SediGraph results compare closely with pipette results at sizes finer than 16 μm (6φ))) but indicate a markedly coarser distribution at larger diameters. The hydrophotometer gives anomalously coarse results throughout the size range. No general conversion factor could be devised to adjust hydrophotometer results to those of the pipette and hydrometer methods. Reproducibility is excellent for pipette and hydrometer, good for hydrophotometer, and fair for SediGraph. Instrument precision of the SediGraph and hydrophotometer is excellent; imprecision arises mainly through the subsampling process.

Keywords:

• granulometry
• pipette
• hydrometer
• SediGraph
• hydrophotometer