Polycyclic aromatic hydrocarbons in bulk PM2.5 and size-segregated aerosol particle samples measured in an urban environment |
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Authors: | Seung Shik Park Young J Kim Chang Hee Kang |
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Institution: | (1) Department of Environmental Engineering, Chonnam National University, 300 Yong-bong dong, Buk-ku, Gwangju, 500-757, Korea;(2) Department of Environmental Engineering and Science, Advanced Environmental Monitoring Center (ADEMRC), Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-ku, Gwangju, 500-712, Korea;(3) Department of Chemistry, Cheju National University, Aradong-1, Cheju, 690-756, Korea |
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Abstract: | To analyze polycyclic aromatic hydrocarbons (PAHs) at an urban site in Seoul, South Korea, 24-hr ambient air PM2.5 samples were collected during five intensive sampling periods between November 1998 and December 1999. To determine the PAH
size distribution, 3-day size-segregated aerosol samples were also collected in December 1999. Concentrations of the 16 PAHs
in the PM2.5 particles ranged from 3.9 to 119.9 ng m−3 with a mean of 24.3 ng m−3.An exceptionally high concentration of PAHs(∼120 ng m−3) observed during a haze event in December 1999 was likely influenced more by diesel vehicle exhaust than by gasoline exhaust,
as well as air stagnation, as evidenced by the low carbon monoxide/elemental carbon (CO/EC) ratio of 205 found in this study
and results reported by previous studies.
The total PAHs associated with the size-segregated particles showed unimodal distributions. Compared to the unimodal size
distributions of PAHs with modal peaks at < 0.12 μm measured in highway tunnels in Los Angeles (Venkataraman and Friedlander,
1994), four- to six-ring PAHs in our study had unimodal size distributions, peaking at the larger size range of 0.28–0.53
μm, suggesting the coagulation of freshly emitted ultrafine particles during transport to the sampling site. Further, the
fraction of PAHs associated with coarse particles(> 1.8 μm) increased as the molecular weight of the PAHs decreased due to
volatilization of fine particles followed by condensation onto coarse particles. |
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Keywords: | PAHs PM2 5 Size distribution MOUDI CO/EC ratio |
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