Origin of sulfur and nitrogen oxides in acid precipitation at Nagoya and Matsue

Abstract

Sulfur and nitrogen oxides in acid precipitation were observed at Nagoya and Matsue by collecting rainwater in each rainfall. The observation results using trajectory analysis show that these oxides mainly came from urban area at Nagoya, and their mass did not change much with season and the route of trajectories. In contrast, sulfur oxide mainly came from biological origin rather than urban one at Matsue inferred from nssδ³⁴S data, and its mass increased in winter. The seasonal and trajectorical variation in nssSO₄^2-/NO₃^- ratio and nssδ³⁴S implies that the contribution of continental and/or maritime biogenic sulfur to sulfur oxide in acid precipitation increased in winter at Matsue due to the seasonal wind.