Effects of Light-Absorbing Organic Species on Polycyclic Aromatic Hydrocarbon Photolysis Kinetics in Ice and Snow

Abstract:

Polycyclic aromatic hydrocarbons (PAHs) are present in snow and ice in urban and remote areas. Photolysis of these pollutants creates products that are more toxic than the parent molecule. Therefore, understanding the reaction kinetics of PAHs is important for predicting their effects on the health of organisms and people living in snow-covered regions. Snow often contains significant concentrations of organic matter. We have investigated the effects of coloured dissolved organic matter (cDOM) on anthracene photolysis kinetics in ice and at ice surfaces. We show that competitive photon absorption is the main effect of cDOM. However, anthracene itself appears to act as a photosensitizer, resulting in enhanced photolysis kinetics at high photon fluxes even in the absence of other light-absorbing species.