Fluorescence spectroscopic studies of natural organic matter fractions
- ISBN: 0045-6535
Because of the known mol. complexity and heterogeneity of natural org. matter (NOM), an aquatic bulk NOM was fractionated into well-defined polyphenolic-rich and carbohydrate-rich subfractions. These fractions were systematically characterized by fluorescence emission, three dimensional excitation-emission matrixes, and synchronous-scan excitation spectroscopy in comparison with those of the ref. International Humic Substances Society soil humic acid and Suwannee River fulvic acid. Fluorescence spectroscopy can be useful to qual. differentiate not only NOM compds. from varying origins but also NOM subcomponents with varying compns. and functional properties. The polyphenolic-rich NOM-PP fraction exhibited a much more intense fluorescence and a red shift of peak position in comparison with the carbohydrate-rich NOM-CH fraction. Also synchronous excitation spectra were able to provide improved peak resoln. and structural signatures such as peak positioning, shift, and intensity among various NOM components as compared with those of the emission and excitation spectra. In particular, the synchronous spectral peak intensity and its red shift in the region of .apprx.450-480 nm may be used to indicate the presence or absence of high mol. wt. and polycondensed humic org. components, or the multicomponent nature of NOM or NOM subcomponents.