Abstract
The rate of decrease of 13 polycyclic aromatic hydrocarbons (PAHs) in atmospheric aerosols (fine particulate matter; particle diameter<7.0μm and coarse particulate matter; particle diameter>7.0μm) and deposited particulate matter was measured. The atmospheric aerosols and deposited particulate matter were collected and the decrease of the PAHs contents was measured over one year at the site in a suburban area. The rate of decrease (k) of PAHs was determined from the first-order law for each collected particulate matter and kmed was defined as the median value of all PAHs for each sampling. The Kmed value was 0.3d-1 at maximum. For the comparisons of different particulate matters, the kmed values were largest for fine particulate matters (0.1-0.3d-1). The Kmed values were larger in summer for fine particulate matters than those in other seasons, while those of coarse and deposited particulate matters showed less seasonal variations. For deposited particulate matters, the Kmed values were higher in winter and were contrary to the expectations. For fine particulate matter, the seasonal variation of the PAHs contents was strongly related to those of the k values. This study showed the importance of the content pattern changes of PAHs by decomposition in elucidating the behavior of PAHs in atmospheric environments.
