HR: 11:15h
AN: A41G-04 INVITED     [PDF]
TI: Secondary Organic Aerosol Formation: New Insights
AU: * Kamens, R M
EM: kamens@unc.edu
AU: Jang, M
EM: mjang@email.unc.edu
AU: Lee, S
EM: goodlsd@email.unc.edu
AU: Czoschke, N
EM: nadine@email.unc.edu
AU: Leungsakul, S
EM: sleungsa@email.unc.edu
AU: Hu, D
EM: dhu@email.unc.edu
AB: A discussion of some of the important issues related to secondary organic aerosol (SOA) formation is presented, and SOA formation is placed in a context of global fine aerosol sources. Outdoor smog chamber experiments are described for the purposes of exploring the effects of different types of background aerosols on SOA formation from the reaction of $\alpha$-pinene with NO$_{x}$ in the presence of natural sunlight. Experiments were carried out by first adding 20 to 200 $\mu$g/m$^{3}$ of background aerosols (such as diesel soot, wood smog, and ammonium sulfate seed particles) into 190m$^{3}$, 140m$^{3}$, and 25m$^{3}$ Teflon film outdoor chambers prior to the addition of $\alpha$-pinene and NO$_{x}$. SOA formation was monitored using a scanning mobility particle sizer (TSI-SMPS). Gas and particle phase products were sampled over the course of experiments using denuders and filters. Chamber results indicated that condensed SOA can dramatically alter the chemical composition of primary diesel soot particles as they age in the atmosphere. Since particle phase aldehyde chemistry has recently been implicated as a potentially large source of SOA (Jang and Kamens, et al., {\it Science} 2002), aerosol growth by the heterogeneous reactions of different organic carbonyls in the presence/absence of acidified seed aerosols was studied in a flow reactor and 500-liter Teflon bag system under dark conditions. The results from unsaturated carbonyl and dicarbonyl experiments indicate large increases in SOA formation in the presence of acidified aerosols. This has implications for both biogenic and aromatic systems that generate SOA.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting