HR: 14:25h
AN: A53E-04    [Abstracts]
TI: Speciated Organic Composition of Atmospheric Aerosols: A New, In-Situ Instrument
AU: * Williams, B J
EM: brentw@nature.berkeley.edu
AF: University of California - Berkeley, ESPM Ecosystem Sci. Division 151 Hilgard Hall, Berkeley, CA 94720-3110 United States
AU: Goldstein, A H
EM: ahg@nature.berkeley.edu
AF: University of California - Berkeley, ESPM Ecosystem Sci. Division 151 Hilgard Hall, Berkeley, CA 94720-3110 United States
AU: Hering, S V
EM: susanne@aerosol.us
AF: Aerosol Dynamics Inc., 2329 4th St, Berkeley, CA 94710 United States
AU: Kreisberg, N M
EM: nathan@aerosol.us
AF: Aerosol Dynamics Inc., 2329 4th St, Berkeley, CA 94710 United States
AB: Identification and quantification of the organic composition of ambient atmospheric aerosols is key to tracking sources of aerosols which impact human health, atmospheric visibility, and global climate. Organic matter is a major constituent of airborne particles, comprising 20-50% of the mass of airborne particles below 2.5 æm in diameter. The composition is complex, with hundreds of compounds identified through chromatographic mass spectrometry techniques. While the identified compounds only comprise a fraction of the total organic mass, those that are quantified serve as valuable tracers for sources. For example, hopanes, which are remnants of the biological material from which petroleum originated, serve as a unique tracer for fossil fuel combustion. Levoglucosan is a product of the breakdown of cellulose, and is a unique tracer for wood combustion. A substantial limitation in the use of organic marker compounds for source identification is the difficulty, and cost of the analyses. Needed are time-resolved, cost-effective measurements of specific organic marker compounds. Reported here are initial results from a new, in-situ instrument, the Thermal desorption Aerosol GC-MS/FID (TAG). This is an automated instrument for the time-resolved identification and quantitation of selected organic marker compounds in airborne particles over the size range from 0.1 to 2.5 æm. Atmospheric aerosol samples are collected into a thermal desorption cell by means of humidification and impaction. The sample is transferred onto a GC column by thermal desorption, with subsequent GC-MS/FID analysis. The collection and analysis steps are automated, yielding around the clock speciation. A droplet injector is being developed to provide internal standards for each sample. An advantage of our approach is that it builds on the extensive body of knowledge on the quantification of organic material, and on the identification of the origins of organic aerosols available from past research using filter-based GC/MS analyses. Initial results of ambient aerosol measurements made at Chebogue Point, Nova Scotia, Canada from July-August 2004 during the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT 2004) study will be presented.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0315 Biosphere/atmosphere interactions
DE: 0322 Constituent sources and sinks
DE: 0345 Pollution--urban and regional (0305)
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting