Boehme, J. R.. University of South Florida, jboehme@marine.usf.edu
Coble, P. R.. University of South Florida, pcoble@marine.usf.edu

 
HIGH-ENERGY LASER FRAGMENTATION OF DISSOLVED ORGANIC MATTER: A NEW APPROACH FOR STUDYING CHEMICAL CHARACTERISTICS OF DISSOLVED ORGANIC MATTER.
 
High-energy laser fragmentation (HELF) followed by excitation emission matrix (EEM) spectroscopy provides a new approach for studying the chemical characteristics of dissolved organic matter. Exposure of water samples to laser fragmentation not only aids studies of photodegradation processes, but also provides useful insight into the composition of the original DOM. HELF appears to selectively remove individual DOM components, making it a precise tool for isolating groups of fluorophores. HELF exposes water samples to intense UV radiation at five successive wavelengths followed by the generation of fluorescence excitation-emission matrices. An optical parametric oscillator pumped by a Nd:YAG laser, which can be tuned to produce specific wavelengths from 280-390 nm, generates the high-energy output. Data from rivers that drain into the Tampa Bay estuary will be presented which show that the effects of fragmentation varied by wavelength, with each wavelength targeting distinct fluorophores of DOM. Individual wavelengths selectively destroyed separate components within the DOM matrix, with some wavelengths simultaneously generating new fluorescence. The wavelength position of the new fluorescence suggests the material developed a protein-like signal generated from high-energy UV exposure. These results indicate that HELF is a potentially useful tool for studying the chemical composition and photochemistry of DOM. SS34 CS07 CS21 Oral
 
Day: Monday, Feb. 1
Time: 02:30 - 02:45pm
Location: Eldorado Hotel
 
Code: SS34MO0230E