SECONDARY FORMATION AND THE SMOKY MOUNTAIN ORGANIC AEROSOL - AN EXAMINATION OF AEROSOL POLARITY AND FUNCTIONAL-GROUP COMPOSITION DURING SEAVS

Size-resolved particle samples were collected in the Smoky Mountains a t Look Rock, TN, during the Southeastern Aerosol and Visibility Study (SEAVS) July-August 1995 and analyzed directly by Fourier transform in frared (FTIR) spectroscopy for functional group and chemical bond info rmation. Twenty-eight samples were also gently rinsed in hexane, aceto ne, and water and reanalyzed after each rinse. Direct FTIR analyses of substrates rinsed with solvents enabled separation by polarity and id entification of sulfur-containing organics even though samples were to o small for traditional extraction and analysis (approximately 10-15 m u g). The submicron organic aerosol was predominantly polar. Most of t he nonpolar material, including aliphatic carbon and various minerals, was concentrated in particles greater than 1.0 mu m and is most likel y from primary biogenic and geogenic emissions, such as plant waxes an d windblown soil dust. Unlike Los Angeles, carbonyl size distributions were unimodal and usually peaked in the 0.5-1.0 mu m diameter size ra nge. The predominance of sulfate, carbonyl, and organosulfur absorbanc es, the polarity of the aerosol, and the carbonyl size distributions i ndicate that secondary formation processes have a large influence on t he concentrations, composition, and size distributions of the Smoky Mo untain aerosol.