Carbonaceous aerosol characteristics of PM2.5 particles in Northeastern Asia in summer 2002

PM2.5 fine particles were collected at four sites in Northeast Asia, Beijing, Gwangju, Kyoto, and Ulaan-Battor, during an intensive sampling period of 23 July–2 August 2002, within the framework of the Asia-Pacific Network for Global Change Research (APN) project. The carbonaceous species, organic carbon (OC) and elemental carbon (EC), in the PM2.5 samples were analyzed by the selective thermal manganese dioxide oxidation method. The average PM2.5 mass concentrations were measured to be 144.9, 17.1, 37.9 and 17.4 μgm−3 at Beijing, Gwangju, Kyoto and Ulaan-Battor, respectively. The average OC and EC concentrations were 12.4 and 5.4 μgm−3 for Beijing, 1.4 and 0.3 μgm−3 for Gwangju, 5.0 and 1.3 μgm−3 for Kyoto and 2.3 and 0.4 μgm−3 for Ulaan-Battor. Average OC/EC ratio was computed to be 2.4, 4.2, 5.0 and 6.6 for Beijing, Gwangju, Kyoto and Ulaan-Battor, respectively. Source–receptor relationships of fine carbonaceous particles were investigated by air mass back-trajectories. The results indicated that organic carbons at Beijing are mainly from primary organic local sources.