Abstract
Ambient particles smaller than 4 μm (PM4) in Kyoto were collected from May 2006 to December 2007, and the concentrations of PM4 mass and PAHs were determined. Such factors as meteorological conditions and air masses transported from China to Japan that affected the atmospheric behavior of particulate PAHs were analyzed. The concentrations of benzo[b]fluoranthene (BbF), Benzo[ghi]perylene (BghiP) and indeno[1,2,3-cd]pyrene (IP) were highest among PAHs contained in atmospheric particulates. Atmospheric concentrations of PAHs were high in the winter and low in the summer due to the volatilization and photodegradation of PAHs in the summer. The contents of 6-ring PAHs in PM4 were larger than those of 4-ring and 5-ring PAHs. This is because of the tendency of the 6-ring PAHs to have lower vapor pressures than 4-ring and 5-ring PAHs. The concentrations of PAHs correlated with the NO2 concentrations. These results indicate that the source of ambient PAHs may be anthropogenic emissions from automobiles. The high concentrations of atmospheric PAHs during continental yellow sand, "Kosa", and the cold season may be attributed to the long transport of air pollutants from China to Japan based on backward trajectory analysis.
