Photolysis is an important process in the fate of many organic pollutants in surface waters. While means to measure the steady state concentrations of photochemically produced reactive intermediates and second order reaction rate constants are well known, predicting these values is more problematic. At the molecular scale, computed one-electron oxidation potentials correlate with second order rate constants for reaction of triplet excited states, singlet oxygen, and carbonate radicals with phenols. In river systems dominated by wastewater, the photoreactivity will be driven by the organic matter in the effluents. Spectral properties of effluent organic matter are key to predicting the quantum yield for the formation of triplet excited state organic matter and singlet oxygen. At the watershed scale, a combination of the spectral properties organic matter and landscape features provide improved prediction of the quantum yield for the formation of triplet excited state organic matter via multiple linear regression models. At large spatial scales, prediction of colored dissolved organic matter levels in lakes using satellite imagery leads to the ability to predict levels of photochemically produced reactive intermediates, and thus pollutant degradation rates, in lakes across Minnesota.

Photolysis across scales: From molecules to space

2019 Spring National Meeting

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