title: Transboundary transport of anthropogenic sulfur in PM2.5 at a coastal site in the Sea of Japan as studied by sulfur isotopic ratio measurement.
abstract: 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)Snss) 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)Snss 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)Snss in sulfuric acid derived from domestic emissions in Japan are lower than those of δ(34)Snss in coal, the lower δ(34)Snss for the air mass transported over the Japanese islands suggest that sulfuric acid in PM2.5 modified the δ(34)Snss 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.
authors.affiliation: Asia Center for Air Pollution Research, 1182, Sowa, Niigata, Niigata 950-2144, Japan. Electronic address: inomata@acap.asia.
authors.forename: Yayoi
authors.initials: Y
authors.lastname: Inomata
authors.affiliation: Asia Center for Air Pollution Research, 1182, Sowa, Niigata, Niigata 950-2144, Japan; Niigata Prefectural Institute of Public Health and Environmental Sciences, 314-1, Sowa, Niigata, Niigata 950-2144, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Ohizumi
authors.affiliation: Asia Center for Air Pollution Research, 1182, Sowa, Niigata, Niigata 950-2144, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Take
authors.affiliation: Asia Center for Air Pollution Research, 1182, Sowa, Niigata, Niigata 950-2144, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Sato
authors.affiliation: National Institute for Environmental Studies, 16-2, Onogawa, Tsukuba, Ibaraki 305-8506, Japan; Tokyo University of Science, 12-1, Ichigaya Funakawara, Shinjuku, Tokyo 162-0826, Japan.
authors.forename: Masataka
authors.initials: M
authors.lastname: Nishikawa
keywords: Coal; Northeast Asia; PM2.5; Source estimate; Sulfur isotopic ratio; Transboundary transport of sulfate