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PHOTOCHEMICAL PRODUCTION OF REACTIVE OXYGEN SPECIES BY CONSTITUENTS OF COLORED DISSOLVED ORGANIC MATTER AND COASTAL RIVER WATERS IN THE SOUTHEASTERN UNITED STATES
Citation:
Vaughan, P. P., N. V. Blough, AND R G. Zepp. PHOTOCHEMICAL PRODUCTION OF REACTIVE OXYGEN SPECIES BY CONSTITUENTS OF COLORED DISSOLVED ORGANIC MATTER AND COASTAL RIVER WATERS IN THE SOUTHEASTERN UNITED STATES. Presented at American Geophysical Union Ocean Sciences Meeting, San Antonio, TX, January 24-28, 2000.
Description:
Using a previously developed method to measure OH production, formation rates were obtained for several water systems. Employing an amino-nitroxide probe and DMSO, an action
spectrum for the product consistent with the production of OH by quinone moieties within humic material was observed for Suwannee River fulvic acid. However, model competition
studies with 1,4-benzoquinones indicate that the product formed may not result from the
production of free OH but rather be due to a photosolvate which acts to hydroxylate certain
compounds. The quantum yield for the formation of this intermediate correlates with free
energy values for electron transfer from water to the excited triplet states of substituted
1,4-benzoquinones and 9,10-anthraquinones. This method is further applied to examine OH
production in whole filtered water and size fractionated samples from the Satilla River. The possible involvement of the photo-Fenton reaction in the production of OH will be discussed as it relates to changes in concentrations of hydrogen peroxide, Fe(II) and Fe(III).