The Great Lakes have over 100 tributaries that contribute natural organic matter and other natural photosensitizers to nearshore sites on the lakes. Absorption of sunlight by these sensitizers results in indirect (sensitized) photoreactions of the widespread chemical and biological contaminants that occur in these locations. Singlet molecular oxygen is one reactive transient that plays a dominant role in indirect photoreactions. For example, singlet oxygen reactions inactivate bacteriophages that are being evaluated as indicators of viral pathogens in recreational waters. We emphasized indirect photoreactions involving chromophoric dissolved organic matter (CDOM) in these studies. In addition to its important role as a photosensitizer, CDOM also modulates photoreactions as one of the most important UV-protective substances in Great Lakes waters. Here, we present action spectra (wavelength studies), UV-visible spectral data, and other data and relationships for evaluating photoproduction and steady state concentrations of singlet molecular oxygen in selected tributaries and nearshore areas in Lake Michigan and Lake Erie.

Impacts of tributaries on optical properties, singlet oxygen concentrations and contaminant photoreactions in selected near-shore areas of the Great Lakes

251st National Meeting (2016)

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