A Multicomponent Model of Chromophoric Dissolved Organic Matter Photobleaching

• Published in: Photochemistry and photobiology Vol. 80; no. 1; pp. 52 - 60
• Main Authors: Goldstone, Jared V., Del Vecchio, Rossana, Blough, Neil V., Voelker, Bettina M.
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.07.2004
• Subjects: Light; Organic Chemicals - chemistry; Organic Chemicals - radiation effects; Research s; Ultraviolet Rays
• ISSN: 0031-8655; 1751-1097
• DOI: 10.1562/TM-03-17.1

Light absorption by chromophoric dissolved organic matter (CDOM) plays a number of roles in natural waters, including both control of the underwater light field and the initiation of many photochemical reactions. A multicomponent analysis was used to describe the effects of UV and visible radiation on the optical absorption spectra of two natural water samples, a Suwannee River fulvic acid standard (SRFA) and a Delaware Bay water sample. This analysis used a constrained minimization technique to fit independent spectral components to the observed bleaching behavior of the water samples under monochromatic irradiation. Spectra derived from these fits were used to predict the bleaching behavior of both samples under polychromatic irradiation (λ > 320 nm). This approach reproduces the kinetics and spectral behavior of polychromatic photobleaching very well at times <48 h, but underpredicts the bleaching at longer time periods.