Stable Sulfur Isotope Ratios of the Gases from Mt. Sakurajima and Satsuma-Iwojima Volcanoes --Assessment of Volcanic Sulfur on Rainfall Sulfate in Kagoshima Prefecture--

Kin'ichi KASASAKU*, Takashi MINARI, Hitoshi MUKAI†† and Kentaro MURANO††

Kagoshima Prefectural Institute of Industrial Technology; 1445-1, Oda, Hayato, Kagoshima 899-5105 Japan
Kagoshima Prefectural Environmental Management Division; 10-1, Kamoike-shinmachi, Kagoshima-shi 890-8577 Japan
†† National Institute for Environmental Studies; 16-2, Onogawa, Tsukuba-shi 305-0053 Japan

Stable sulfur isotope ratios of SO2 emitted from active volcanoes such as Mt. Sakurajima and Satsuma- Iwojima were determined in relation to the project clarify source of sulfur in acidic and oxidative compounds in East Asia. The δ34S of SO2 were +10.1 to +13.5% and +3.2 to +8.4% at Satsuma-Iwojima and Mt. Sakurajima, respectively. We reported the δ34S values for Mt. Sakurajima for the first time, but it should be noted that the gas samples were collected at station about 3 km away from fumarole. Nevertheless the δ34S values of Mt. Sakurajima volcano were similar to those from Mt. Use, Mt. Tarumae, Mt. Kuju-Iwoyama and Mt. Aso for which gas samples directly collected from fumarole.
The δ34S values of sulfate in wet deposition collected at Mt. Shibi and Yorita, located approximately 50 km northwest of Mt. Sakurajima volcano, varied with time, contribution of the different sources of sulfur to these two sampling localities. Wet deposition samples from Mt. Shibi were considered to be more influenced by Mt. Sakurajima emission than Yorita, which was rather affected by continental anthropogenic emission.

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