Photolysis of Polycyclic Aromatic Hydrocarbons in Simulated Atmospheric Cloud Water Buffers

This study, motivated by environmental concerns, examines the predominant role of photolysis on polycyclic aromatic hydrocarbons (PAHs) in acidic cloud water. Polycyclic aromatic hydrocarbons are organic compounds fused in a ring derived from only hydrogen and carbon atoms. PAHs form through incomplete combustion reactions, particularly involving the burning of coal, gas, oil, and wood. Because these compounds are highly stable, they remain environmentally persistent within the atmosphere and bind to particulate matter, which has dangerous impacts on human health, particularly involving cancer and respiratory disorders, as these pollutants are carcinogenic. The project aimed to explore how simulated cloud water buffer systems' varying pH levels influence PAH pollutants' photolytic reactions.

Suspensions of pure PAHs were placed into simulated cloud water buffer solutions and irradiated using a solar simulator before being analyzed on an HPLC to determine PAH photoproducts. Initial findings indicated that an acidic buffered system with environmentally relevant formic or acetic acid enhances product formation. Product formation also increased under irradiation, as observed through HPLC monitoring. These preliminary results contribute to a better understanding of the mechanisms driving PAH reactions in the atmosphere, particularly with implications for environmental protection. Ongoing research into Fenton reactions using soluble iron in cloud water buffers demonstrates further observable product formation. It lays the groundwork for future studies on peroxyl radicals and other environmentally persistent free radicals.