2002 Annual

Thursday, 17 January 2002: 1:30 PM
Aerosol Chemical Characterization on Board the DOE G1 Aircraft using a Particle-into-Liquid-Sampler during the TexAQS 2000 experiment
Yin-Nan Lee, Brookhaven National Laboratory, Upton, NY; and Z. Song, Y. Liu, P. Daum, R. Weber, D. Orsini, N. Laulainen, J. Hubbe, and V. Morris
Poster PDF (596.2 kB)
A particle-into-liquid-sampler (PILS) coupled to ion chromatography (IC) analysis was deployed on board the DOE-G1 aircraft during the 2000 Texas Air Quality Study to determine the ionic components of aerosol particles with aerodynamic size smaller than 2.5 µm (PM2.5). The sampling frequency was 3 minutes with a sample integration time of ~120 seconds. Six ions, namely, NH4+, SO42-, NO3-, Na+, K+, and Ca2+, were quantified with a limit of detection of ~0.1 µg m-3. While NH4+ and SO42- (median and maximum concentrations of 1.6 and 5.0, and 1.8 and 9.4 µg m-3, respectively) dominated the ionic components, NO3- was typically very low, less than 0.2 µg m-3, with occasional excursions reaching nearly half that of SO42-. Na+ was nearly always present but at low concentration levels, i.e., < 0.3 µg m-3. Although K+ and Ca2+ were observed in only ~15% of the samples, K+ reached as high as 6 µg m-3. NH4+ to SO42- molar ratios were typically greater than 2 and frequently exceeded 4, suggesting the presence of additional anions. The total ion mass concentration correlated strongly with the PM2.5 mass estimated from the size/number distributions of accumulation mode particles. The mass fraction of the ions varied between ~40% and ~90%. The mass difference between the PM2.5 and total ions showed a good correlation with black carbon. Since organic carbon and black carbon are typically strongly correlated, this observation suggests that organic compounds dominated this mass difference.

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