Abstract
We have been measuring several air pollutants, such as the total odd nitrogen species (NOy), ammonium (NH4+), sulfate (SO4 = HSO4- + SO42-), organic aerosol (Org), carbon monoxide (CO) and PM2.5 at Cape Hedo, Okinawa, focusing on the long-range transport of air pollutants from the Asian continent. Yearly variations in their concentrations were analyzed using these observational data. Although the amount of air pollutants emitted from East Asia would increase year by year, the corresponding increase of their concentrations was not observed at Cape Hedo. The average concentrations of NOy, NH4+, SO4, and Org in the spring of 2008 were relatively high. The CO concentration in 2008 was not high in comparison to that in the other years, there fore the influence of emissions by combustion in East Asia would not be so large. In order to discuss the influence of the air mass originating from that East Asia for the yearly variations, we classified the origins of air masses arrived at Cape Hedo using backward trajectory analyses and investigated the yearly variations of these concentrations for each air mass. The result suggested that the contribution of air pollutants from the North China air mass origin has been increasing year after year..
