Spatiotemporal distribution characterization and source estimation of PM2.5 components in the Ulsan Industrial Complex

Abstract Ulsan City, South Korea, hosts various industries, including metal processing, petrochemicals, machinery, and electronics. The complex interplay of industrial activities, traffic emissions, and marine influences contributes to the formation of fine particulate matter (PM 2.5 ). This study investigated the chemical composition and sources of PM 2.5 in Ulsan using samples collected periodically from five air monitoring stations between August 2020 and December 2023. The highest PM 2.5 concentrations were observed in areas with dense industrial facilities, such as the Onsan National and Mipo General Industrial Complexes. These areas were characterized by large-scale industrial operations, including metal processing facilities and petrochemical plants, which were identified as major pollution sources. Coefficient of divergence (COD) analysis revealed minimal differences in pollution sources between the monitoring sites, suggesting that the primary emission sources were relatively uniform across the study area. Furthermore, principal component analysis (PCA) identified various contributors, including metal processing and smelting industries, soil dust, and sea salt particles. Elements such as Fe and Mn were strongly associated with metal processing and machining activities, whereas V and Ni, which originated from petrochemical processes, were indicators of petroleum combustion. PM 2.5 exhibited seasonal variations, with higher levels in winter due to increased heating emissions and in spring due to dust storms. The primary sources of pollution included vehicle exhaust, metal processing and smelting, and sea salt particles, with a more pronounced distribution in regions of intense industrial activity. This study provides essential information on PM 2.5 sources and emissions within Ulsan’s industrial complexes, serving as a foundational resource for air quality management and policy development in the city. Graphical Abstract