LONG-TERM DYNAMICS OF SPECTRAL WATER TRANSPARENCY IN THE SURFACE LAYER OF LAKE KRASILOVSKOYE

Abstract

The paper presents the long-term experimental data (spring of 2012‒2023) on spectral transparency of water in the surface layer of Lake Krasilovskoye (Kosikhinsky region, Altai Krai). For the study period, the widely varying light attenuation index (0.6−35.0 m^-1) was calculated at the spectral range of 400–800 nm; the light absorption index of yellow substance made up 0.1−26.1 m^-1. The concentrations of chlorophyll a and yellow substance were measured. Over the study period, the content of chlorophyll a in the surface layer of the lake was within 2.8–34.6 mg/m³; the concentration of yellow substance determined with the use of the optical method from the measured light absorption by yellow substance at a wavelength of λ=450 nm ranged as 4.4–60.1 g/m³. We estimated the spectral contribution of the main optically active components of water (yellow substance, suspended matter, chlorophyll a and pure water) to the light attenuation index for the surface layer of the water body and revealed that yellow substance and suspended matter provided maximum contribution to the total light attenuation.