1993 年 27 巻 2 号 p. 109-118
We surveyed the sulfur isotope ratio of sulfate in rain waters collected in Kanazawa city from December 1986 to November 1991 to investigate the origin of sulfate in rain waters. The sulfur isotope ratio of sulfate in rain waters varied from +0.9 to +14.7‰ and its average was +6.3‰. The ratio was higher in winter than that in the other seasons. The sulfur isotope ratio of nss-sulfate which was calculated by elimination of the contribution of sea salts from the sulfur isotope ratio of rain water sulfate also showed relatively higher value in winter. This seasonal variation suggested that sulfate in the rain waters collected in winter was mainly derived from the source having a higher sulfur isotope ratio, such as coal combustion in northern China, (north of Yangtze-jiang).