Grant: Research Tools and Instruments - Category 1 (<$150,000)

The size and proportions of a sedimentary particle has a strong correlation to how the grain will interact with the environmental setting.  Grain size analysis is thus a powerful tool in sedimentological analysis, as the variability in grain size of a material (e.g. sediment, soil, plume, aerosol) provides invaluable data for assessing the nature and history of physical properties within an environment.  The co-investigators are involved in a wide variety of sedimentological, hydrological, paleoclimate, paleolimnological and ecological research where various grain size analysis methodologies can be utilized to provide important paleoenvironmental data.There are three types of practical grain size analysis instruments on the market; sedigraphs, laser particle analyzers, and coulter counters.  For the reasons outlined below the coulter counter best meets the requirements of the co-investigators.  A sedigraph measures the dynamical grain size of particles and is useful in distinguishing particles in the 1-63µm range. Unfortunately, these instruments have poor resolution for grains above 63µm and for any size fractions comprising < 5% of a sample. Laser particle analyzers measure particle sizes by analyzing the forward scattering of a laser beam around a particle.  These instruments provide excellent data on the distribution of grain sizes above 30µm but severely underestimate the percentage of fine-grained particles, particularly for very fine plate-like clays.  Coulter counters measure grain size by using the charge displacement of a particle in an electrolyte, which is then used to determine a particle volume that is subsequently converted to an equivalent spherical diameter.  This instrument can accurately determine grain size for material between 1 - 1000µm and as such is best suited for the size range and resolution required by the co-investigators.  We propose to purchase the Multisizer 3 Coulter Counter from Beckman-Coulter.  The instrument not only meets the research requirements of the research co-investigators but also was the cheapest of the instrument quotations obtained.