Study of spectral and fluorescent properties of different samples of humic acids

Depending on their origin and structure, humic acids (HAs) have a remarkable ability to absorb light and transfer this energy to other substrates and in some cases strongly affect photolysis of xenobiotics. This search exhibits several examples of spectral and fluorescent study of humics acids with different genesis. The group of studied HAs was isolated from an unditourified high-moor peat with different humidity in the Mezensky District of the Arkhangelsk Region. The standard commercial preparation of humic acids Aldrich was also studied. For photochemical studies, an excilamp on working molecules KrCl with λ_rad = 222 nm, developed at the Institute of High Current Electronics of the SB RAS, was used as sources of UV radiation. The results of direct and sensitized (in the presence of HAs) photolysis are discussed. For samples of HAs from the Arkhangelsk region, the dependence of the absorption spectra and fluorescence on the duration of drying and the depth of occurrence was found. The longer is the duration of drying of the samples, the lower is the optical density of the absorption spectra. In the process of humification and with the duration of peat drying, the fluorescence intensity of the HAs increases. The dependence of the fluorescence spectra of the studied samples on the wavelength of fluorescence excitation was found.