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Studying characteristics and properties of dissolved organic matter (DOM), its fluorescent fractions (FDOM)
in waters of the Yenisei and Angara rivers has been carried out. Spectral light absorption coefficients (in spectral range
400-800 nm), as well as the intensity of DOM fluorescence in three wave lengths (505, 525 and 540 nm) at the wave
length of exciting radiation 390 nm have been determined. Total DOM concentration was defined by the standard
method of bichromatic oxidation. In the studied water objects the relation of average efficacy (r= 0.6) between fluorescence
intensity and DOM concentration as well as absence of relation between light absorbing and DOM concentration
are noted. To get a qualitative and quantitative assessment of FDOM parameters the calculation algorithm was suggested
based on similarity of dependency course (variations) of FDOM characteristics and corresponding dependencies
of total DOM characteristics. The following parameters were used: coefficients which characterize inclination of spectral
distribution of light absorption and DOM fluorescence, also specific coefficients of absorbing DOM and FDOM
radiation at the wave length of fluorescence excitation (κsp, κf sp), energy (and quantum) fluorescence efficiencies for
DOM and its fluorescent fraction as well as specific fluorescence for DOM and FDOM, respectively.
These calculations enabled to assess the most probable FDOM parameters. The FDOM share in the total DOM
varies for studied waters from 8 to 40% at the average value 19%. The quantum efficiency varies from 0.18 to 0.40
(an average value is 0.28). Specific light absorption coefficients of DOM and FDOM are on average close between each
other (κf sp / κsp makes 0.93). Some decrease of the share of fluorescent DOM fractions at the increase of both total
DOM and FDOM was stated what says about different correlation of FDOM and non- fluorescent fractions in allochthonous
OM due to which the main variations take place both in DOM and in indigenous OM which is formed in the
water storage due to photosynthesis.
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