A light-scattering matrix for unicellular marine phytoplankton

Abstract

This paper presents angular and spectral measurements of the functions that create a scattering matrix (Mtiller matrix). The investigations were carried out on monocultures of the unicellular phytoplankton ChZoreZEa vulgar-is, ChZoreZZu kesleri, and Chroococcus minor at scattering angles from 8" to 155" and at wavelengths of 488, 514, and 633 nm. Living cultures of phytoplankton as well as cultures treated chemically (boiled in 5% NaOH) and physically (ultrasound) were tested. These treatments alter the internal structures of the cells, and show that the altered structures modify the scattering matrix functional.

Using a two-layered sphere model to investigate the impact of gas vacuoles on the inherent optical properties of <i>Microcystis aeruginosa</i>

“…Similar to other studies citing the importance of intracellular structure on the scattering matrix (e.g. QuinbyHunt et al, 1989;Witkowski et al, 1998;Svensen et al, 2007), these features have been speculatively attributed to gas vacuoles. The same studies used a population of homogeneous spheres using Lorenz-Mie theory to attempt to fit the measurements (n = 1.04, n = 0.000).…”

Optical scattering properties of phytoplankton: Measurements and comparison of various species at scattering angles between 1° and 170°

“…Differences in the scattering properties of the other species may be explained by the work of Volten et al (1998) and Witkowski et al (1998), who demonstrated that vacuoles and other internal structures can significantly affect scattering. For example, the lower scattering of perpendicular polarization by I. galbana in the middle angles is likely due to its relative lack of internal structures.…”

“…For example, Slade and Boss (2006) and Agrawal (2005) consider forward angles ,20u, whereas Vaillancourt et al (2004) and Ulloa et al (1994) study primarily backscattering. Large-angle experiments have been performed, of course: Volten et al (1998) covers intermediate angles between 20u and 160u, Witkowski et al (1998) looked at the large-angle scattering matrix for a single species, and Shao et al (2006) recently presented compelling theoretical as well as experimental results in the 40u to 140u range (albeit without considering polarization effects). Chami et al (2006) discuss spectral aspects of scattering at large angles.…”

Determination of the volume scattering function of aqueous particle suspensions with a laboratory multi-angle light scattering instrument

“…However, in contrast to other inherent optical properties, such as the absorption and beam attenuation coefficients, the volume scattering function has not been routinely measured and the existing measurements are typically limited in terms of spectral and angular coverage. A significant portion of available data of βψ; λ for natural waters [6][7][8][9][10][11][12][13][14][15][16][17], and for various particle types such as phytoplankton species and sediment particulate assemblages [18][19][20][21][22][23][24] was obtained with custom-built prototype instrumentation. For example, among the most commonly used sets of βψ measurements that represent oceanic and coastal waters are those documented in [6].…”