HR: 14:10h
AN: A53E-03    [Abstracts]
TI: Investigation Into the Hydrophilic Versus Hydrophobic Fraction of Ambient PM2.5 Organic Particles Soluble in Water
AU: * Sullivan, A P
EM: asullivan@eas.gatech.edu
AF: Georgia Institute of Technology, ES&T Building 311 Ferst Dr., Atlanta, GA 30332 United States
AU: Weber, R J
EM: rweber@eas.gatech.edu
AF: Georgia Institute of Technology, ES&T Building 311 Ferst Dr., Atlanta, GA 30332 United States
AB: On-line water-soluble organic carbon (WSOC) measurements are made by continuously collecting ambient particles into a purified flow of water using the Particle-Into-Liquid Sampler (PILS) [Orsini et al., 2003], filtering the liquid, and quantifying the dissolved carbon using a Total Organic Carbon (TOC) analyzer. Extension of this method has allowed for quantifying broad chemical classifications of the WSOC by passing the liquid sample through various XAD resins. The resins selectively remove the most hydrophobic WSOC compounds. The fractions of hydrophobic and hydrophilic carbonaceous compounds of the WSOC are quantified online by switching the XAD column on and offline to measure the hydrophilic fraction and hydrophobic fraction by difference. When combined with online measurements of the total organic carbon (OC), provided by a Sunset Labs Carbon Analyzer (Thermal/Optical Transmittance method), hydrophobic and hydrophilic fractions of OC can be measured. Ambient results from deploying this technique in urban Atlanta and St. Louis suggest that hydrophobic and hydrophilic fractions of WSOC are typically near 50/50. However, during strong photochemical events the hydrophilic fraction dominates, reaching 65% of the WSOC, and the WSOC comprises about 75% of the OC. Investigation of the seasonal and temporal trends in the hydrophobic and hydrophilic fractions of WSOC, and more detailed chemical speciation will be discussed. Orsini, D., Y. Ma, A. Sullivan, B. Sierau, K. Baumann, and R. Weber (2003) Refinements to the particle-into-liquid sampler (PILS) for ground and airborne measurements of water soluble aerosol composition, Atmos. Environ. 37: 1243-1259.
DE: 0305 Aerosols and particles (0345, 4801)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting