Chemical characteristics and source apportionment of particulate matter in the largest industrial city of Ulsan, South Korea

Abstract

Because of rapid economic growth and the increasing speed of urbanization and industrialization, particulate matter (PM) pollution has become a primary global concern. PM consists of various chemical compositions, such as elemental species, carbonaceous species, and water-soluble inorganic ions (WSIIs). Moreover, toxic organic compounds [e.g., polycyclic aromatic carbons (PAHs)] in PM have also been reported with high carcinogenic risk. Thus, in-depth investigations of chemical characteristics, source apportionment, and PM formation pathways are essential for controlling and mitigating air pollution. This doctoral thesis provides detailed knowledge regarding the damage effects of PM. The characterization of PM2.5 chemical compositions indicates that the high levels of PM2.5 were due to a rise in the concentration of almost all studied compounds (i.e., PAHs, WSIIs, and trace elements). Besides, examining the variations in the origin of PM on days with high and low pollution levels could be beneficial for policymakers. It could help pinpoint the primary emission sources on polluted days, ultimately resulting in improved air quality. According to positive matrix factorization results, coal/biomass burning, primary sulfate, and secondary inorganic aerosols were the largest contributors to PM2.5 on polluted days, which may be influenced by both local emission sources and long-range atmospheric transport. Day–night variation and size distribution of PAHs and WSIIs were also investigated in this thesis. Finally, the effect of meteorological parameters [ambient temperature (T) and relative humidity (RH)] on the formation of secondary PM from gaseous precursors was considered. The result shows more apparent effects of T on the relationship between PM2.5 and gaseous pollutants than that of RH. In general, the findings observed in this thesis are not only valuable for environmental scientists but also for those in government. The thesis provides an in-depth understanding of PM air pollution in the largest industrial city of Ulsan, South Korea. In this thesis, the sampling may be applicable for research on the impact of industrial activity on the formation of secondary PM in industrial and urban areas. Meanwhile, the approach in this thesis can be useful for further research aimed at identifying different sources of pollution in industrial and urban areas.