Moran, M. University of Georgia, mmoran@arches.uga.edu
Sheldon, W. M. University of Georgia, wade@wiegert.marsci.uga.edu
Zepp, R. G. US Environmental Protection Agency, zepp.richard@epamail.epa.gov

 
TRANSFORMATIONS OF ESTUARINE CHROMOPHORIC DISSOLVED ORGANIC MATTER BY BIOLOGICAL AND PHOTOCHEMICAL PROCESSES
 
Terrestrial DOM exported to coastal marine environments typically contains high concentrations of chromophoric (light-absorbing) molecules. The fate of chromophoric DOM (CDOM) in estuaries and the coastal ocean has important consequences for a number of biological and chemical issues, including global carbon cycling, functioning of microbial food webs, penetration of sunlight into seawater (including potentially harmful UV-B wavelengths), and satellite sensing of ocean color. We studied the rates of photochemical degradation of CDOM irradiated with simulated sunlight for extended periods, during which up to 60% of the original absorptivity of the CDOM (but only 30% of the carbon) was lost. Subsequent biological degradation of the variously bleached CDOM samples was also measured, and found to remove an additional 15% of the original CDOM (and 17% of the carbon). Exposure to simulated sunlight converted CDOM to more biologically labile forms, but the quantity of labile organic matter produced was not linearly related to the length of irradiation. Absorbance measurements of bleached and biodegraded CDOM indicated that photochemical and biological processes had very different effects on the optical properties of CDOM, particularly in the wavelength region from 450 to 800 nm.
 
Day: Tuesday, Feb. 2
Time: 09:30 - 09:45am
Location: Eldorado Hotel
 
Code: CS61TH0445E