Characteristics of PM2.5 Pollution and Long-range Atmospheric Transport in Background Areas (baengnyeong and Jeju Islands)

This study evaluated the characteristics of PM2.5 pollution and long-range atmospheric transport (LRAT) at the Baengnyeong and Jeju Air Quality Research Centers in South Korea during 2018 similar to 2020. The mean concentration of PM2.5 was constant in Baengnyeong but decreased in Jeju owing to COVID-19. The significant seasonal variations of OC, EC, and NO3- in Baengnyeong and Jeju with the highest concentrations in winter may be due to the influence of high PM2.5 episodes. Meanwhile, the concentrations of SO42- and NH4+ were constant throughout the year in Baengnyeong, resulting from regional inflow from surrounding areas. The influence of anthropogenic sources and secondary formation of PM2.5 increased in summer and decreased in autumn at both sites, which was also observed at other background sites. The dominance of NO3-, K+, and Cl- in Baengnyeong was due to the influence of combustion sources and LRAT. The source of SO42-, NH4+, V, and Ni in Jeju was identified as industrial activities with the highest contribution in summer. The secondary formation of PM2.5 with external inflow effects was dominant in Baengnyeong and Jeju. The main emission source area of PM2.5 for both Baengnyeong and Jeju was East China (Hebei, Shandong, Jangsu, and Anhui), but the chemical composition and sources of PM2.5 were different between Baengnyeong and Jeju. The result of this study can be a basis for future monitoring and modeling studies on the influence of LRAT in background areas.