Evaluation of water suspension effect on spectral light attenuation in Novosibirsk Reservoir

Abstract

The paper presents the measurement data (August 20–22, 2019) on spectral light attenuation in the Novosibirsk reservoir waters in the range from 400 to 800 nm. In different sampling sites, attenuation (calculated at the natural logarithmic base) varied within 4.6–25.9 m^–1. Relative transparency (42–140 cm) was measured using a Secchi disk. To assess the effect of water suspension on total attenuation, we calculated its relative spectral contribution and other main optically active components of water, i.e. yellow substance, chlorophyll a and pure water. Yellow substance and suspension showed maximum contribution to light attenuation in the water from all 10 sampling sites of the reservoir. The spectral contribution of suspension made up 29.8–60.3% in the range of 430 nm, 38.8–71.4% at 550 nm and 33.2–64.1% at 670 nm, respectively. Suspension was the second optically active component affecting spectral light attenuation.