2008 年 23 巻 3 号 p. 194-199
Beijing and Tokyo are both megacities. As the raw material ratios on the fundamental energy for each city function are different, the major sources of aerosols in each city must be different. In this study, we compared the compositions of carbonaceous materials and the ratios of stable carbon isotopes (δ13C) of soot in aerosols collected in both megacities. The ratio of organic carbon (OC) to elemental carbon (EC) in atmospheric aerosols in Beijing showed seasonal variation, whereas the OC/EC ratio showed little seasonal variation in Tokyo. The δ13C of the atmospheric aerosols in Beijing was -24.0 ± 0.3 ‰ in the heating period (November to March) reflecting the high contribution of particles derived from coal combustion, and its value was -25.1±0.6 ‰ in the non-heating period (April to October) when contributions from sources other than coal combustion increased. On the other hand, the δ13C of the atmospheric aerosols in Tokyo was approximately constant throughout the year at -25.1 ± 0.1 ‰. Because there are clear differences between the δ13C of the atmospheric aerosols in the winter and spring seasons in Beijing and Tokyo, we consider this to be a good index for examining long-range transport aerosols.