AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Photooxidation of Polycyclic Aromatic Hydrocarbons in Clouds and Fog – Laboratory and Model Studies
JERSHON EAGAR, Pierre Herckes, Barbara Ervens, Arizona State University
Abstract Number: 441 Working Group: Aerosols, Clouds, and Climate
Abstract Cloud and fog droplets are an atmospheric medium for aqueous phase photochemical reactions. Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the atmosphere and are among products formed during the incomplete pyrolysis of organic matter. Higher molecular weight PAHs bound to particulate matter may dissolve in the aqueous phase during cloud and fog droplet nucleation. The reactivity of these higher molecular weight PAH (four, five, and six ring) has not received much attention from the atmospheric chemistry community. This work will present laboratory studies on the photodegradation of chrysene under atmospherically relevant conditions. In a first step, reaction kinetics and product formation will be discussed.
In a second step, the significance of cloud and fog droplets as a sink for the photodegradation of four, five, and six ring PAHs will be explored as compared to the sink strength of gas and particle phase reactions. Parameter spaces will be mapped out by means of a box model using literature data and new experimentally-determined values of photochemical kinetic data. The partitioning between gas and aqueous phases will be described using literature Henry’s law constants. Photooxidation in the aqueous phase will be calculated for several droplet formation and evaporation cycles.