AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Chemical Characteristics of Submicrometer Aerosols at Urban Gwangju in Korea Measured with Aerosol Mass Spectrometer
Kihong Park, Jiyeon Park, Seungyong Lee, HEE-JOO CHO, Minsoo Kang, Gwangju Institute of Science and Technology
Abstract Number: 296 Working Group: Urban Aerosols
Abstract Size-resolved chemical composition of submicrometer non-refractory particles was measured with quadruple aerosol mass spectrometer (QAMS) at urban Gwangju in Korea in fall (8/30/2011-9/19/2011) and winter (12/19/2011-12/30/2011) with varying air masses. It was found that organics was dominant chemical species (~50%) of submicrometer non-refractory aerosol mass. Average mass concentrations of organics were 4.7±1.8 μg/m³ and 6.3±1.8 μg/m³ in fall and winter, respectively. The ratio of m/z 44 to organics and sulfate increased significantly in the afternoon, suggesting that intense photochemical activity led to produce oxidized organics and sulfate in the afternoon. The average sulfate concentration was 1.8 μg/m³, which was the lowest among sites in other East Asia countries due to few SO₂ emission sources around the sampling site. The nitrate concentration in winter was ~4 times higher than those in fall (2.45 versus 0.62 μg/m³). The low temperature and strong temperature inversion might lead to the significant increase of nitrate concentration in winter. It was observed that sulfate, nitrate, and chloride were fully neutralized by the ammonium in winter, while these anions were not fully neutralized by ammonium in fall. Size distribution data showed that sulfate had only one peak at Dva of 500-600 nm, regardless of season, while organics had one peak (500-600 nm) in fall and bimodal distribution (100-200 nm and 500-600 nm) in winter. The absence of the first mode (i.e., Dva<200 nm) in organics in fall suggests that oxidized organic species would be more dominant than hydrocarbon-like organics, which is consistent with the higher ratios of m/z 44 to organics in fall (0.10±0.02) than winter (0.07±0.01). Air-mass dependent concentrations of species showed that northwest air mass (i.e., long-range transported from industrial areas in China) and southeast air mass (i.e., transported from industrial area in Korea) were mainly responsible for high loadings of organics and sulfate.