Aquatic Sciences Meeting, Albuquerque 2001

PC15 Photochemistry

Date: Thursday, February 15, 2001

Location: Southwest Hall

Del Vecchio, R, , Univ. of Maryland, College Park, USA, rossdv@wam.umd.edu

Blough, N, V, Univ. of Maryland, College Park, USA, nb41@umail.umd.edu

MODELING OF CDOM PHOTOBLEACHING IN FIELD ENVIRONMENTS

The spectral dependence of the rates of photobleaching of colored dissolved organic matter (CDOM) has been measured for waters from the Chesapeake and Delaware Bays and for a standard Suwannee River fulvic acid (SRFA). The SRFA decay rates have been used to create a matrix of the photobleaching cross-sections that can be employed to predict the CDOM photobleaching rates of natural waters under broad-band light fields. This model has been applied to natural waters under field settings to predict the change in the CDOM spectral shape caused by photodegradation and to test whether the timescale of photobleaching is consistent with field observations acquired during the summertime for coastal waters in the middle Atlantic Bight (MAB). Using the measured values for the solar irradiance and CDOM absorption coefficients in the MAB, the wavelength dependence of the rates for CDOM absorption loss of with time and depth was determined, with the loss of absorption over short time intervals averaged across the mixed layer to account for vertical mixing. Results from the model will be presented and compared to field measurements.

This Session Listing

Aquatic Sciences Meeting, Albuquerque 2001

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