Twardowski, M. S. Oregon State University, mtwardo@oce.orst.edu
Desiderio, R. S. Oregon State University, desi@oce.orst.edu
Donaghay, P. L. University of Rhode Island, donaghay@gsosun1.gso.uri.edu
Cowles, T. J. Oregon State University, tjc@oce.orst.edu

 
USING FINESCALE, IN SITU OPTICAL MEASUREMENTS TO CHARACTERIZE DOM POOL SIGNATURES IN COASTAL WATERS
 
As the composition of the DOM pool changes as a result of in situ processes such as photodegradation, certain inherent optical properties of colored DOM (CDOM) should change as well. These parameters include the shape of the absorption spectrum, the shape of fluorescence excitation-emission spectra, the quantum yield of fluorescence, and the spectral shape of the quantum yield. Previously, some of these parameters have not been accurately quantified in natural samples because of the difficulty in measuring CDOM absorption with adequate precision at low natural levels. To investigate this problem, finescale vertical profiles of the spectral absorption (precision better than 0.005 m-1) and 2D fluorescence by dissolved materials were simultaneously collected in situ with hydrographic parameters in East Sound, WA. The most striking changes in the optical parameters were associated with photodegradation at the surface, evident in a steeper spectral slope of CDOM absorption and a lower quantum yield of fluorescence. Results from in situ incubations corroborated our field observations. The optical signatures were used to spatially and temporally track different CDOM pools and, in the case of photobleaching, could be used to estimate solar radiation dosages and the total amount of CDOM absorption that had been bleached.
 
Day: Monday, Feb. 1
Time: 02:45 - 03:00pm
Location: Eldorado Hotel
 
Code: SS34MO0245E