2 0 0 0 OA 洞爺湖における過塩素酸の分布と動態解析
In the present study, the distributions and dynamics of perchlorate in atmospheric and aquatic environment in and around Lake Toya, Hokkaido, Japan was investigated. The perchlorate concentrations in atmospheric aerosol were in the range of 0.03-0.21 ng/m^3 from july to October when the fireworks events are held every night, while those after the end of the events were less than the detection limit (< 0.01 ng/m^3). Since the firework events started in May, the perchlorate ware detected in the lake waters collected at the southern part of Lake Toya, while those before the beginning of the events ware less than the detection limit (< 0.33 μg/L). Especially, the concentrations of perchlorate in the lake water were observed locally in the range of 2-7 μg/L, which were exceeded the U.S. drinking water quality standard (2 μg/L). After the end of fireworks events, the perchlorate in lake water collected at lakeside could be observed in the range of 0.33-1.65 μg/L. In addition, perchlorate was detected in the range of 0.5-2.1 μg/L in waters collected around the center (Nakashima), the southern part (Takarada) and the downstream (Shinzan-numa) of the lake throughout the year. From these results, it was concluded that the fireworks is the main source of perchlorate around Lake Toya and the emitted perchlorate is wholly diffused in the water through the water circulation of Lake Toya. Furthermore, the perchlorate was detected in the water after the end of fireworks event, showing that perchlorate was detected in the water after the end of fireworks event, showing that perchlorate is resistant to decomposition in the aquatic environment.