King, D. W., Colby College, Waterville, USA, dwking@colby.edu
Powers, L. C., Colby College, Waterville, USA,
Ong, T. ., Colby College, Waterville, USA,

REACTIVITY OF SUPEROXIDE IN NATURAL WATERS

Superoxide is a radical anion produced in surface waters by the photooxidation of dissolved organic matter. Because of its intermediate redox potential, superoxide participates in the oxidation of dissolved organic materials and the redox cycling of dissolved metal ions like iron and copper. Steady state superoxide concentrations in natural waters are in the picomolar to nanomolar range requiring sensitive chemiluminescence methods for detection. Two chemiluminescent reagents have been investigated, 2-Methyl-6-(4-methoxyphenyl)imidazo[1,2-a]pyrazin-3(7H)-one (MCLA) and 1,10-phenanthroline in a cetyldimethylethylammonium bromide micelle. Using these systems we have studied the reactivity of superoxide in natural waters. A surprising outcome of these studies is the reaction of superoxide with dissolved carbon dioxide to form the peroxycarbonate radical and subsequent dimers. Because carbon dioxide is ubiquitous in natural waters, the formation of the peroxycarbonate radical may significantly modify the reactivity of superoxide.

Oral presentation

Presentation is given by student: No
Session #:SS01
Date: Friday, June 13, 2008
Time: 2:00 PM

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