We have investigated the effects of organic matter (OM) on the photolysis kinetics of polycyclic aromatic hydrocarbons (PAHs) in ice and at ice surfaces. Nonchromophoric OM (i.e. OM that does not absorb sunlight) reduces PAH photolysis rates dramatically within bulk ice samples. Photolysis rates at ice surfaces depended on OM phase, with solid OM having a greater suppressing effect than liquid OM. Spectroscopy of the PAH naphthalene at ice surfaces suggests that naphthalene partitions between ice and organic phases present there. We also investigated the effects of chromophoric OM (fulvic and humic acids) on anthracene photolysis kinetics in aqueous solution, in ice, and at ice surfaces. In all cases the chromophoric OM reduced anthracene photolysis kinetics solely by competitively absorbing photons. These results show that OM can affect PAH photolysis kinetics in ice and at ice surfaces in complex manners, and that OM should be considered when predicting PAH fates in snow-covered regions.

Effects of organic matter on polycyclic aromatic hydrocarbon photolysis kinetics in ice and at ice surfaces

249th National Meeting (2015)

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