부산대학교 도서관

Sulfur isotopic ratios (δ 34 S) in size separated aerosol particles (PM2.5 and coarse particles) were measured at Niigata-Maki facing the Sea of Japan. Non-sea salt δ 34 S (δ 34 S nss ) in PM2.5 showed seasonal variations with relatively high values in winter (1.0–3.9‰ in spring, 2.8–4.5‰ in summer, 1.3–4.5‰ in autumn, 3.7–5.7‰ in winter). Taking into consideration air mass transport routes, δ 34 S nss in the air masses which originated in the Asian continent and were transported over the Sea of Japan to the monitoring sites were higher than those values for air masses which were transported over the Japanese islands after leaving the Asian continent for each season. Considering that the δ 34 S nss in sulfuric acid derived from domestic emissions in Japan are lower than those of δ 34 S nss in coal, the lower δ 34 S nss for the air mass transported over the Japanese islands suggest that sulfuric acid in PM2.5 modified the δ 34 S nss due to aerosol mixing with sulfuric acid in Japan. Material balance calculations suggested that the relative contribution of transboundary transport in winter was also higher than for other seasons (40–75% in spring, 51–63% in summer, 45–73% in autumn, and 53–81% in winter). In particular, the contribution to the air masses which were transported directly from the Asian continent was relatively large (75% in spring, 59% in autumn, 78% in winter) in comparison with that for the air masses which were transported over Japan. [ABSTRACT FROM AUTHOR]