Underwater spectral irradiance of freshwater reservoirs
I.A. Sutorikhin1, I.M. Frolenkov1, S.A. Litvinenko1, V.A. Soloviev2
1Institute for Water and Environmental Problems of the Siberian Branch of the RAS, Barnaul, Russia
2Polzunov Altai State Technical University, Barnaul, Russia
Keywords: underwater spectral irradiance, light absorption, light scattering, interference light filter, water transparency, Secchi depth, lake
Abstract
The results of measurement of underwater spectral irradiance at various depths in different types of intracontinental freshwater lakes, including the Kamginsky Bay of Lake Teletskoye, are presented. The measurements were carried out in summer and autumn 2018. The device for measuring the underwater spectral irradiance is described. Interference light filters with transmission maxima in different parts of the visible spectrum at wavelengths of 303, 361, 590, and 656 nm were used as light selective elements. An abnormally high absorption of light at a wavelength of 361 nm was detected in the pelagial of the Kamga Bay (territory of the Altai State Natural Biosphere Reserve), which is explained by the large amount of coniferous and deciduous wood rotting on the shores and flooded in the pelagial of the Bay and releasing phenolic compounds. The found dependence of the underwater spectral irradiance on depth is presented in the tabular form. It is shown that the underwater spectral irradiance significantly depends on the biomass of lake phytoplankton.
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