Title

Effects of Fine-Fraction Pre-Treatment for Laser Diffraction Particle Size Analysis

Presenter Information

Matt Johnson
Lauren Walton

Document Type

Oral Presentation

Location

SURC Ballroom B/C/D

Start Date

21-5-2015

End Date

21-5-2015

Keywords

Geology, Sediment Analysis, Laser Diffraction

Abstract

Pretreatment of sediment samples for particle-size analysis can be costly and time consuming. Here we present results of how various levels of pretreatment affect laser diffraction results. For this study, we subjected 35 sub-samples from seven different stratigraphic layers of the Sanders archaeological site (45KT315) in central Washington State to different combinations of pretreatment (removal of organic and inorganic carbon using 30 percent H2O2 and 1N HCl, respectively, and ultrasonic dispersion). Fully treated samples were presumed to be most accurate and were used as the test control. As expected, completely untreated samples exhibited excess coarse-sized particles (i.e., most negatively skewed). Other results demonstrate inter- and intra-sample variations that are likely due to differences in physical and chemical properties of each sample. No clear patterns emerge that lead us to conclude anything other than full pretreatment is required for best results.​

Poster Number

49

Faculty Mentor(s)

Patrick Lubinski, Ian Buvit

Department/Program

Resource Management

Additional Mentoring Department

Anthropology & Museum Studies

Additional Mentoring Department

McNair Scholars

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May 21st, 11:30 AM May 21st, 2:00 PM

Effects of Fine-Fraction Pre-Treatment for Laser Diffraction Particle Size Analysis

SURC Ballroom B/C/D

Pretreatment of sediment samples for particle-size analysis can be costly and time consuming. Here we present results of how various levels of pretreatment affect laser diffraction results. For this study, we subjected 35 sub-samples from seven different stratigraphic layers of the Sanders archaeological site (45KT315) in central Washington State to different combinations of pretreatment (removal of organic and inorganic carbon using 30 percent H2O2 and 1N HCl, respectively, and ultrasonic dispersion). Fully treated samples were presumed to be most accurate and were used as the test control. As expected, completely untreated samples exhibited excess coarse-sized particles (i.e., most negatively skewed). Other results demonstrate inter- and intra-sample variations that are likely due to differences in physical and chemical properties of each sample. No clear patterns emerge that lead us to conclude anything other than full pretreatment is required for best results.​