Transformation and photodegradation of chromophoric dissolved organic matter (CDOM) were analyzed in Southern California coastal waters. Using optical analysis, the absorption coefficient, fluorescence intensities, and spectral slope showed an increase for samples collected in anaerobic regions with greater microbial activity. Fluorescence intensities were depicted using 3D excitation-emission matrix (EEM) fluorescence spectroscopy. Terrestrial humic peaks A and C showed higher fluorescence intensity in anaerobic waters and lower fluorescence intensity in aerobic waters. Tryptophan-type and tyrosine-type protein peaks T and B, respectively, were more prominent in waters with anaerobic microbial activity and greater input of terrestrial and senesce plant matter. High molecular weight and aromaticity were characteristic of humification in anaerobic waters from the microbial biodegradation of organic material. The optical distribution and properties of CDOM in coastal waters suggest specific dependences on the degree of photochemistry, microbial activity, season, and regional geography.

Optical analysis of chromophoric dissolved organic matter (CDOM) photodegradation in Southern California coastal waters

248th National Meeting (2014)

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