Beam attenuation

Beam attenuation in the red is linearly correlated with particle mass concentration. Where phytoplankton are the dominant particulates, the beam atteunation coefficient can be correlated to the particulate organic carbon (POC) concentration and can be used to estimate net primary production and biomass-specific production rates.

Phytoplankton composition

Spectral absorption

Phytoplankton have specific pigment compositions related to species and physiological parameters. Precise absorption spectra can distinguish the bulk ratios of pigments in a given population and can be used for taxonomic and niche identification.

Particle composition: the proportion of pigmented to non-pigmented particles

a/b (absorption-to-scattering ratio)

Can estimate the abundance of phytoplankton particles relative to the total particle population

Size distributions

Spectral attenuation

The hyperbolic slope of the attenuation spectrum in the visible is linearly linked to the slope of the hyperbolic, Junge-type particle size distribution, thus providing a simple means of determining relative proportions of small and large particles.

Bulk refractive indices—PIC:POC

Backscattering ratio
and spectral attenuation

The strong relationship between the backscattering ratio and bulk refractive index allows a direct estimate of the proportion of organic to inorganic particulate material (POC:PIC)

Colored dissolved organic matter (CDOM)

UV and blue wavelength spectral fluorescence and dissolved absorption

Identification of fluorescent amino acids, terrestrial humic and fulvic acids, aquatic humic acids and whitening agents. Composition of chromophoric dissolved organic material based on dissolved absorption spectrum.