Triplet excited dissolved organic matter (3DOM●) is as an important photo-produced reactive intermediate that impacts pollutant and carbon cycling in natural waters. Unlike other reactive species present in sunlit waters, such as 1O2 or hydroxyl radicals, 3DOM● consists of a complex, heterogeneous mixture of individual species. Due to this fact, much remains unknown about specific rate constants of reaction with pollutants and triplet probe molecules (e.g., trimethylphenol, sorbic acid) that are commonly employed in environmental photochemistry. Herein, we present research that utilizes time-resolved 1O2 phosphorescence as a means to monitor and assess 3DOM● reactivity. A focus is placed on triplet quenching with sorbic acid, a well-established triplet energy transfer probe. From kinetic analysis, rate constants of triplet quenching and the distribution of triplet energies within DOM are determined for a wide-spanning set of DOM isolates and whole natural waters. Results provide insight into the role DOM source (e.g., terrestrial- vs. algal-derived) plays in observed reactivity.

1O2 phosphorescence as a probe for 3DOM●: Assessing triplet reactivity with sorbic acid

255th National Meeting (2018)

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