Study for PM2.5 composition and variations at Ieodo Ocean Research Station, Korea

PM2.5 has been collected since June 2004 at Ieodo Ocean Research Station (IORS), which is located in the middle of China and South Korea. For 3 years from June 2004 to June 2007, average mass concentrations were 20.97±16.86 μg/m3 and concentrations were the highest in spring (29.32μg/m3) and lowest in summer (17.00μg/m3). Water soluble ions were determined during December 2004 to September 2005. SO42- (32.2%) and NH4+ (14.2%) were the most abundant species. In winter, SO42- accounted for 42% of PM2.5 means, which was higher than that in spring (26%). Nitrate was thought to be lost through evaporation. The cluster analysis of backward trajectories for 5 days was performed to examine the possible aerosol sources. High mass concentrations were observed in air masses originating from China inland (26.93μg/m3). Also, the seasonal PM2.5 mass concentrations were well correlated with the frequency of western wind. Compared with PM2.5 measurements at Gosan during the ABC- EAREX2005 (March 2005), PM2.5 mass and major ionic concentrations were higher at IORS while the variation pattern was similar in two stations. These results implied that PM2.5 mass and its major ionic species at IROS were greatly influenced by outflows from China.