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Abstract: To identify the ambient characteristics of a mega city in Northeast Asia, the particulate PAHs in TSP were measured for 18months at Seoul, the capital of Korea. The average concentration of the ambient particulate PAHs at Seoul for the sampling period was 26.6±28.4ngm−3 with the range from 1.57 to 166ngm−3. It showed winter maxima and summer minimum mainly due to the increased fuel consumption in winter both at Seoul and Northeast Asia. The ambient level of PAHs in Seoul was lower than the cities in China but higher than other urban areas. The stronger relationship between the ambient particulate PAHs concentrations and the inverse of the ambient temperature (1/T) at Seoul compared to Gosan, a background site in Korea and the difference of the distributions of BeP/BaP ratios at Seoul and Gosan might be due to the characteristics of Seoul which was governed by both transport from outside and local emissions. The relationship between the particulate PAHs concentration and (1/T) can be used as an indicator for those two factors for Seoul. [ABSTRACT FROM AUTHOR]

The atmospheric size distributions of particulate polycyclic aromatic hydrocarbons (PAHs) and their deposition fluxes were measured at four sites in August and at three sites in November 1999, in Korea. The total ambient particulate PAHs concentrations at each site ranged between 6.7 and 128.7 ng m−3. In November, the total PAHs concentrations at Inchon (IC) were the highest, followed by Yangsuri (YS) and Seoul (SE). This trend is contrary to the expectation that the total PAHs concentrations at IC and SE be higher than that at YS because IC and SE are highly industrialized large cities and YS is rural area. The size distributions of individual PAHs in IC and SE show trimodal in Dp ≤ 9 µm while the particulate PAHs in YS were distributed evenly to fine- and coarse-size particles. These results suggest that YS has local sources in addition to transport of PAHs emitted from urban sources. The measured dry deposition fluxes of total PAHs ranged from 6.9 to 12.6 µg m−2 day−1 in August, and from 5.9 to 8.5 µg m−2 day−1 in November. Individual PAH fluxes were dominated by high molecular weight (MW) PAHs at all sampling sites in August. But dry deposition fluxes of low MW PAHs were higher than high MW PAHs at all sampling sites in November. This result indicates that major sources of ambient PAHs have seasonal variety. The Sehmel-Hodgson model was used to estimate dry deposition velocities as a function of particle size for the multistep deposition model calculation. The calculated fluxes agreed fairly well with the measured fluxes, and it was shown that large particles (Dp > 9 µm) are more important than small particles (Dp > 9 µm) in particulate dry deposition of PAHs. [ABSTRACT FROM AUTHOR]