Behavior and origin of atmospheric NO2, SO2, and O3 in mountains around the Kyoto basin

The behavior and origin of atmospheric NO2, SO2, and O3 in mountains around the Kyoto basin were investigated by using passive samplers. Since these samplers are compact and need no batteries or pumps, they are appropriate for the measurement of atmospheric NO2, SO2, and O3 at low-level concentrations in mountains or forests. The sampling sites were Mt. Hiei, Mt. Daimonji, and 7 other mountains around the Kyoto basin, and 4 clean sites (Seryu, Kuroda, Sasari, Ashu) located about 20-30 km north of the Kyoto basin. The concentrations of atmospheric NO2, SO2, and O3 in mountains on three sides of the Kyoto basin were almost the same at the same altitude in the same season. The source of atmospheric NO2 in mountains around the Kyoto basin may be anthropogenic emission from automobiles or industrial areas, and NO2 concentration at clean sites far away from the Kyoto basin may become lower due to the diffusion of NO2. O3 concentration was higher as the altitude increased. Atmospheric O3 at mountains around the Kyoto basin has its origin in both stratospheric input and O3 production by photochemical reactions.