The use of polycyclic aromatic hydrocarbons as source signatures in receptor modeling

The purpose of this study was to explore the use of polycyclic aromatic hydrocarbons (PAH) as organic tracers and to demonstrate how their atmospheric chemical reactivity can be incorporated into a chemical mass balance (CMB) model. PAH signatures were characterized for three combustion sources; residential wood combustion, gasoline spark ignition emissions and diesel engine emissions. The ability to source-differentiate using PAH signatures was tested with a numerical simulation program. Signatures with nine different PAH ranging from benzanthracene to coronene and two smaller groups with four PAH were used. Normalized PAH signatures gave better results than un-normalized signatures. It was possible to distinguish between three sources when a minor source contributed more than 10% of the total. The resulting CMB model was evaluated with ambient data from three different studies for which PAH data existed, and receptor modeling had been undertaken using other tracers. Very reasonable results were obtained. PAH reactivity can strongly influence predicted source contributions under warm daytime conditions.