Systematic Study of CDOM in the Volga River Basin Using EEM-PARAFAC
Drozdova, A. N., Molkov, A. A., Kapustin, I. A., Ermoshkin, A. V., Leshchev, G. V., Krylov, I. N., Labutin, T. A.
Excitation–emission matrix fluorescence spectroscopy was used to examine dissolved organic matter along more than 1,500 km of the Volga, from the Gorky Reservoir to the Volgograd Reservoir, between May and September in 2022–2024. Parallel factor analysis identified four stable fluorescent components. Their relative proportions changed little, but fluorescence intensity varied by more than 2.5-fold between the Gorky Reservoir and the Kama River. FDOM was highest in the Gorky Reservoir and decreased downstream after the Oka and Kama inflows. Conventional lidar measurements and absorption at 440 nm did not resolve all four components; their usefulness as proxies depended on correlations between the fluorophore groups.