Suspended minerogenic particles in a reservoir: Light-scattering features from individual particle analysis

Peng, Feng, Steven W. Effler

Limnol. Oceanogr., 52(1), 2007, 204-216 | DOI: 10.4319/lo.2007.52.1.0204

ABSTRACT: Light-scattering attributes of minerogenic particles in a reservoir, where these particles dominate over a wide range of light-scattering levels, were characterized by an individual particle analysis technique, scanning electron microscopy interfaced with automated X-ray microanalysis and image analysis (SAX). SAX provided characterizations of the elemental X-ray composition, shape, number concentration (N), particle size distribution (PSD), and projected area per unit volume (PAVm) of these particles. Clay mineral particles represented ~84% of the PAVm, and they deviated from sphericity more than the other components of the minerogenic assemblage. Scattering coefficients for minerogenic particles at 660 nm (bm(660)) were estimated directly from SAX results based on Mie theory. Both PAVm and bm(660) were strong predictors of the observed wide variations in light scattering. Most of the light scattering in the reservoir was attributable to particles in the size range 2-8 µm. Reasonably good closure is reported for estimates of bm(660), based on comparisons to in situ measurements of the beam attenuation coefficient at 660 nm. The widely used hyperbolic (or Junge) model (to describe PSDs) failed to accurately represent the total value and the particle size dependency of bm(660) as calculated from SAX observations, whereas the two-component PSD model (using both components or the ‘‘B’’-component only) succeeded for these two features. SAX offers the opportunity to advance partitioning of scattering between minerogenic and organic particle contributions as well as among constituents of the minerogenic component.

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