Secondary organic aerosol formation from aromatic precursors. 1. Mechanisms for individual hydrocarbons.

Quantitative kinetic and physical phase partitioning models of secondary organic aerosol (SOA) formation resulting from the reactions of aromatic species were integrated into a mechanism for gas-phase reactions. Using the resulting model, analyses of the sensitivity of SOA formation to several parameters (e.g., VOC/NOx ratio, rate parameters) were performed. Results indicated that aerosol yield (SOA formed per amount of hydrocarbons reacted) depends on the extent of conversion of parent hydrocarbons, partitioning coefficient, initial aerosol mass concentration, and rate parameters. On the basis of the sensitivity studies, models for SOA yield were developed for 11 aromatic compounds. Comparison of the results from current SOA models to the results from this study suggests that mechanisms describing SOA formation from aromatic species must incorporate the reactions of reactive intermediates.