Proc. SPIE. 6733, International Conference on Lasers, Applications, and Technologies 2007: Environmental Monitoring and Ecological Applications; Optical Sensors in Biological, Chemical, and Engineering Technologies; and Femtosecond Laser Pulse Filamentation
The humic substances (HS) are always present in the natural waters to a greater or lesser extent. Their
property to fluorescent while being excited optically can be applied to use humic substances as a water
ecosystem natural indicator.
To realize the possibility of using HS as an natural indicator it is necessary to ascertain the correlation
between the fluorescence characteristics of HS, their fluorophore structure and the genesis of HS with the
influence of the parameters of the environment. It is also important to analyze these rules in the water surface
micro-layer which is very important in the mass exchange between the hydrosphere and atmosphere (and in
the pollution transfer also).
The results of the determination of the molecular photophysical parameters of the HS fluorophores of
different genesis are presented in the paper. The non-linear and kinetical fluorimetry methods with variation
and artificial neural net algorithms were applied.
During the research were solved the inverse problems for which the kinetic fluorescence curves were taken as
an initial data. The curves were obtained through the HS excitation with the third harmonic of Yag-Nd Laser.
The differences in the meanings of these parameters are discovered. The precise analysis of the shape of HS
fluorescence band is accomplished.
The results of this analysis are used to determine the structure of the water masses using the fluorescence
characteristics of HS. The differences of the HS fluorescence characteristics in the water surface micro-layer
and in the water volume is discovered. The ability of determining the structure of water micro-layer by laser
probe is shown.
The significant investigation result is the possibility of distinguishing the small fluorescenting anthropogenic
admixture from the intense HS fluorescence background.