Dissolved organic matter (DOM), a heterogeneous assembly of fragmented biomacromolecules, is ubiquitous in natural waters. Upon absorbing sunlight, the chromophoric fraction of dissolved organic matter (CDOM) produces a suite of reactive species, including singlet oxygen and hydroxyl radical, which go on to react with many constituents (including contaminants such as pharmaceuticals, pesticides, etc.) within the natural waters, and thus have a significant impact on the functioning of aquatic ecosystems. The excited triplet state (3CDOM*) plays a central role in these photochemical processes. A variety of probe molecules are used to elucidate the photoreactivity of 3CDOM*, because of the molecular-scale heterogeneity. Multiple reactive pathways access different but overlapping subgroups of 3CDOM*. Awareness of the differences between the reaction types is growing; however, only limited investigation has been done on the differences between the energy transfer and redox mechanisms. The purpose of this research is to further study the ways that the probe molecules react with 3CDOM* in natural waters possessing a range of DOM characteristics.<br/>2,4,6-trimethylphenol, furfuryl alcohol and 2,4-hexadienoic acid are used as probe compounds. Water samples spiked with probe compound solutions are irradiated in a photochemical reactor, and the results of the reactions are studied via spectroscopy and HPLC techniques. We also employ fluorescence spectroscopy of the DOM and draw correlations between features in the fluorescence spectra and variations in the photoreactivity of the 3CDOM* with the different probe molecules.

Using multiple probe molecules to elucidate factors affecting the photoreactivity of excited triplet state dissolved organic matter in natural waters

2019 Spring National Meeting

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