The role of suspended minerogenic particles in light scattering in eastern Lake Superior and Keweenaw Bay (11 sites) during July of 2006 was evaluated with an individual particle analysis technique (scanning electron microscopy interfaced with automated image and X-ray analyses, SAX), along with bulk measurements of particulate scattering and backscattering coefficients (b p and b bp ) and chlorophyll a concentration ([Chl]). SAX measurements provided information on light-scattering attributes of minerogenic particles, including chemical composition and particle size distribution (

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Inorganic particles in the upper waters of the 11 Finger Lakes of New York are morphometrically and elementally characterized by individual particle analysis conducted with scanning electron microscopy interfaced with automated image and X-ray analyses (IPA/SAX). Coupled measurements of Secchi disk transparency (SD), the attenuation coefficient for downwelling irradiance (K d ), the beam attenuation coefficient at 660 nm, and turbidity (T n ) were made to support evaluation of the importance of non-living, inorganic particles (inorganic tripton) in regulating these optical features of water quality. Wide differences in levels of inorganic tripton, represented in terms of particle projected area per unit volume (PAV in ), and the optical measures are reported for these lakes. However, generally similar size distributions are observed for the inorganic tripton for the lakes. Terrigenous suspensoids, in the form of clay minerals, dominated the inorganic tripton particle assemblage of nine lakes, while CaCO 3 , formed autochthonously, dominated in the other two and was a noteworthy contributor in four others. PAV in is demonstrated to be an important regulator of the optical properties of these lakes, performing substantially better than chlorophyll in predicting SD, and T n , and interlake differences in these optical measures.

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 (PAV m ) of these particles. Clay mineral particles represented ,84% of the PAV m , and they deviated from sphericity more than the other components of the minerogenic assemblage. Scattering coefficients for minerogenic particles at 660 nm (b m (660)) were estimated directly from SAX results based on Mie theory. Both PAV m and b m (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 mm.Reasonably good closure is reported for estimates of b m (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 b m (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.

The dynamics of light scattering by minerogenic particles in the upper waters of Cayuga Lake, New York, were characterized for the spring-autumn interval of 8 yr (1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006) at pelagic and nearshore sites with a scanning electron microscope interfaced with automated image and x-ray analyses (SAX). SAX results were used to estimate the minerogenic scattering coefficient ( Light scattering by particles, a fundamental process regulating radiative transfer in water (Kirk 2011), is important in determining apparent optical properties (AOPs, depend on geometry of the light field) of interest, including clarity (Preisendorfer 1986) and the remote sensing signal (Woźniak and Stramski 2004). The total scattering coefficient (b; m 21 ), corresponding to the integration of the volume-scattering function over all directions (Kirk 2011), quantifies a central feature of the light-scattering regime. b is an inherent optical property, independent of the geometry of the light field. The magnitude and spectral features of the particulate component of scattering, b p (which greatly exceeds that due to water), depend on multiple attributes of a particle population, including the number concentration (N), the particle size distribution (PSD), the composition of the individual particles and their shapes (Babin et al. 2003).The particle populations of aquatic ecosystems are heterogeneous, varying in time and space and differing greatly among systems in response to an array of drivers (Stramski et al. , 2007Peng and Effler 2011). Protocols for resolving the various components of light scattering are needed to understand these differences and dynamics, and to identify their origins and drivers, objectives that are consistent with the reductionist approach advocated by Stramski and co-workers (Stramski et al. 2001(Stramski et al. , 2007 where V is the sample volume, N m is the number of minerogenic particles in a sampled volume of water, and PA m,i is the projected area (m 2 ) of minerogenic particle i. Q bm,i depends on the complex refractive index (m i , function of composition) and size (d i ) of the particle, and the wavelength of light (l). This SAX-Mie approach supports further partitioning of b m into contributions according to size and particularly composition (e.g., clay minerals, quartz, and calcite) of particles Effler 2010, 2011). Early research with the SAX-Mie approach had appropriately focused first on testing the credibility of the forward estimates of b m for a range of particle assemblage conditions (see