Grain size analyzers: results of an intercomparison study

Abstract

In sciences involving soil and sediment, particle size distribution (PSD) has been one of the parameters given most attention over the past few decades. Formerly measured by sieving and sedimentation techniques, it is nowadays routinely characterized by the laser diffraction method (LDM). Many manufacturers develop particle size analyzers using LDM, but each device is characterized by specific parameters that can lead to different PSDs. At the Rhône Sediment Observatory, suspended particulate matter collected along the Rhône River is analyzed for PSD by four different LDM devices. Analyses were conducted on certified materials and sediment samples for each device. The tests highlighted the difficulty of accurately characterizing PSD, even in the case of certified materials. First, differences observed for a specific device were linked to the heterogeneity observed in the subsamples due to the presence of organic materials such as tree leaves. Second, the difference regarding the certified materials was linked to the laser diffraction method which leads in some cases to underestimating clay content and sand. Third, the main difference observed between the devices was linked to sonication. The results demonstrate that its power is rarely investigated and that it has a considerable impact when used. However, despite significant differences, the trend was similar for each device, with accurate characterizations of the main modal class in most cases. Thus, in the absence of exact knowledge of parameters such as sonication power and pump speed, it is recommended to compare only the trends of the results obtained from the different devices.

Concentrations and fluxes of suspended particulate matter and associated contaminants in the Rhône River from Lake Geneva to the Mediterranean Sea

“…The database provides information on characteristic diameters D10, D50 and D90 of the particle size distribution. Non-negligible differences between these parameters were found during an intercomparison of the two devices (Lepage et al, 2019). The comparison of the results must therefore be done with caution.…”

Dating the late Miocene marine sediments around the southern middle Durance valley (Provence, SE France): new evidences for a Tortonian age

“…The particle size limits follow the recent classification of Blott and Pye 2012. The reproducibility of the analyses obtained using the BC LS 13 320 have been carefully evaluated (Lepage et al, 2019).…”

Hydro-climatic drivers of land-based organic and inorganic particulate micropollutant fluxes: The regime of the largest river water inflow of the Mediterranean Sea

“…The particle size distributions of the SPM samples collected in the present study (i.e., for the six river stations investigated) are mainly multimodal. Indeed, between 2 and 4 (3 in most cases) Gaussian distributions were generally observed: mode 1 between 1 and 10 µm (average 4 µm particle size; clays and very fine silts), mode 2 between 10 and 27 µm (average 14 µm; fine silts), mode 3 between 27 and 80 µm (average 39 µm; coarse silts), and mode 4 between 80 and 2000 µm (average 136 µm; fine to coarse sands) (Launay, 2014;Masson et al, 2018;Lepage et al, 2019). The SPM samples were sorted depending on the hydrological conditions during SPM sampling, and the median micropollutants concentrations was calculated for low flow and flood conditions.…”