Abstract
Laser diffraction spectrometry allows for efficiently obtaining high-resolution grain size data. However, pretreatment and dispersion of aggregates in sediment samples are essential pre-requisites for acquiring accurate results using this method. This study evaluates the effectiveness of five dispersing agents in deflocculating the investigated fluvial sediments and the resulting grain size distribution obtained by laser diffraction spectrometry. We also examine the ability of the different dispersing agents to deflocculate sediment samples treated by thermal combustion. Distilled water presented a low efficiency in deflocculating the samples and yielded a near-zero clay content for samples with an expected clay content. The other chemical dispersants were effective in dispersing aggregates and yielding clay, albeit with different efficiencies. Calgon had the highest dispersing ability, followed closely by sodium tripolyphosphate. The performance of chemical treatment with sodium oxalate approaches that of sodium tripolyphosphate. However, it leads to the formation of precipitates in the samples, obscuring the actual grain size data. Sodium pyrophosphate derived the least amount of deflocculation among the four chemical dispersants. Furthermore, all the chemical dispersants were found to be ineffective in dispersing aggregates in samples treated by thermal combustion.
Highlights
IntroductionThe grain size distribution observed in a sediment is determined by the availability, entrainment, transport, and deposition of detrital debris [1] and provides valuable information regarding provenance, transport processes, and depositional mechanisms [1,2]
Grain size is one of the most important physical properties of sediments
This study evaluates the effectiveness of different chemical dispersing agents on the grain size distribution of Quaternary fluvial sediments from the Upper Rhine Plain, France
Summary
The grain size distribution observed in a sediment is determined by the availability, entrainment, transport, and deposition of detrital debris [1] and provides valuable information regarding provenance, transport processes, and depositional mechanisms [1,2]. Over the last few decades, the introduction of laser diffraction spectrometry (LDS) has provided a means to obtain high-resolution grain size data. The scattered light data is converted into particle size information using the Mie theory of light scattering or the Fraunhofer diffraction theory. This analytical technique offers extensive measurement capabilities, allowing for rapid measurement of grain size distribution over a wide range of materials, from clay to very coarse sand (0.01–3500 μm) [13]. It is a powerful tool for measuring grain sizes as found in many depositional environments
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