INFLUENCE OF VOLCANOES TO THE ACID DEPOSITION AT FUKUI

Air at Fukui in 1993 was traced by Inverse-Trajectory method. Air at Fukui comes from China mainland from October to next May when Siberian anticyclone is superior. In July and August air comes fmm Pacific Ocean, while June and September comes from almost all directions. SO2 load in East Asia was estimated by Akimoto et al. Using Eliassen's dispersion and chemical reaction formulae, origin of acid deposition to Fukui was estimated. Fukui is situated close to Japan Sea so that contribution of China mainland reaches up to 90%, but during the summer season no pollution comes from China. Not only artificial sources, but volcanoes discharge SO2 in the air. In Kyushu Islands amount of SO2 discharged is much more than artificial ones. Sakurajima, Aso and Suwanosejima are three main volcanoes whose SO2 release affects the acid deposition at Fukui. In 1993, maximum portion of volcanic vent to the total acid deposition at Fukui was about 40%.