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An explanation of the spectral variation in freshwater CDOM fluorescence
Author(s) -
Vodacek Anthony
Publication year - 1992
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1992.37.8.1808
Subject(s) - colored dissolved organic matter , fluorescence , dissolved organic carbon , wavelength , spectral slope , chemistry , environmental science , spectral line , analytical chemistry (journal) , environmental chemistry , optics , physics , organic chemistry , phytoplankton , astronomy , nutrient
The variation of freshwater chromophoric (or colored) dissolved organic matter (CDOM) fluorescence with respect to sample pH was examined. Trends from previous studies are supported by results obtained from fluorescence spectra collected during sample titration. The evidence suggests spectral variation of CDOM fluorescence can arise from pH‐dependent photo‐oxidation of a portion of the catechol component of CDOM to coumarin structures. A hypothesis is drawn that the observed shorter wavelength fluorescence exhibited by acid lake samples relative to the spectra of more neutral lake samples is, in part, a result of the inhibition of CDOM photo‐oxidation under the acid conditions. By careful choice of both excitation and emission wavelengths, fluorescence measurements may monitor changes in the composition of CDOM.