HR: 09:30h
AN: A41B-06    [PDF]
TI: Fatty Acids as Surfactants on Aerosol Particles
AU: * Tervahattu, H
EM: heikki.tervahattu@helsinki.fi
AF: Nordic Envicon Oy, Koetilantie 3, Helsinki, FIN-00710 Finland
AU: Juhanoja, J
EM: jyrki.juhanoja@topanalytica.com
AF: Top Analytica Ltd, Ruukinkatu 4, Turku, FIN-20540 Finland
AU: Niemi, J
EM: jarkko.v.niemi@helsinki.fi
AF: University of Helsinki, Department of Limnology and Environmental Sciences, P.O.Box 27, Helsinki, FIN-00014 Finland
AB: Fatty acids (n-alcanoic acids) are common compounds in numerous anthropogenic and natural emissions. According to Rogge et al. (1993), catalyst-equipped automobiles emitted more than 600 ęg km-1 of fatty acids which was over 50% of all identified organics in fine aerosol emissions. Coal burning produces fatty acids ranging from about 1700 mg kg-1 for bituminous coal to over 10000 mg kg-1 for lignite (Oros and Simoneit, 2000). Similarly, biomass burning is an important source for aerosol fatty acids. They are the major identified compound group in deciduous tree smoke, their total emission factor being measured as 1589 mg kg-1 which was 56% of all identified organic compounds (Oros and Simoneit, 2001a). Large amounts of fatty acid are also emitted from burning of conifer trees and grass (Oros and Simoneit, 2001a; Simoneit, 2002). Fatty acids have been reported to be major constituents of marine aerosols in many investigations (Barger and Garrett, 1976; Gagosian et. al, 1981; Sicre et al., 1990; Stephanou, 1992). It has been suggested that as the marine aerosol particles form, they acquire a coating of organic surfactants (Blanchard, 1964; Gill et al., 1983; Middlebrook et al., 1998; Ellison et al., 1999). Amphiphilic molecules, including lipids, can be assembled as monomolecular layers at air/water interfaces as well as transported to a solid support. Recently, we could show by time-of-flight secondary ion mass spectrometry that fatty acids are important ingredients of the outermost surface layer of the sea-salt aerosol particles (Tervahattu et al., 2002). In their TOF-SIMS studies on the surface composition of atmospheric aerosols, Peterson and Tyler (2002) found fatty acids on the surface of Montana forest fire particles. In this work we have studied by TOF-SIMS the surface chemical composition of aerosol particles emitted from field fires in the Baltic and other East European countries and transported to Finland as well as aerosol particles transported from Russian forest and peat fires. Fatty acids were commonly observed on the surface layer of these particles. The chain length composition was characteristic to each emission source. In our previous work (Tervahattu et al., 2002), fatty acids on sea-salt particles were originated from dead sea plankton organisms with major peaks ranging from C14 to C18 and maximum at C16 (palmitic acid). Major peaks on the surface of forest fire particles ranged from C16 to C30 with the maximum at C24. This composition indicates the involvement of the smoke from both conifer trees and peat (Oros and Simoneit, 2000; 2001b). On the other hand, TOF-SIMS analysis of the surface of field fire particles showed major peaks from C14 to C30 with two maximums at C16 (highest intensity) and C22. It was concluded that the results indicate emissions from both grass burning and fossil fuels (Simoneit, 2002; Oros and Simoneit, 2000). The presence of surface film on aerosol particles may have an impact on their chemical, physical and optical properties and change their role in light scattering and as cloud condensation nuclei as well as interactions with human tissue.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0345 Pollution--urban and regional (0305)
DE: 4801 Aerosols (0305)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting