Analysis of Metal Concentration Distribution and Seasonal–Spatial Characteristics in PM2.5 in Ulsan

This study aimed to analyze the concentration distribution and seasonal–spatial characteristics of 15 metallic elements contained in PM2.5 in Ulsan, a representative industrial city in Korea, from January to November 2024. PM2.5 samples were collected monthly at seven monitoring sites—three located in industrial areas and four in residential areas—and the concentrations of metal components were quantitatively analyzed using ICP-MS. The annual average concentrations of metals in PM2.5 were highest in the order of Fe, Zn, Pb, and Mn, indicating a strong influence from industrial activities. Seasonally, most metals showed peak concentrations in winter, while Fe and Mn were highest in autumn, and V peaked in summer. During yellow dust events, metal concentrations in PM2.5 and PM10 increased by approximately 6-fold and 12-fold, respectively, compared to non-event periods, with a particularly larger increase observed in PM10. Spatial analysis revealed that the Onsan National Industrial Complex exhibited the highest concentrations, while some residential areas such as Jeonha-dong and Deoksin-ri also recorded metal levels comparable to or higher than those in industrial zones. These findings suggest the potential dispersion of industrial emissions into nearby residential areas, influenced by wind direction, topography, and atmospheric flow. Significant positive correlations were observed between PM2.5 concentrations and V, Pb, Cd, As, Zn, Cu and Fe, implying that multiple metal species emitted from industrial sources may be concurrently transported in the atmosphere. This study provides a scientific basis for developing localized air quality management strategies and public health protection policies in Ulsan through detailed identification of the spatial and temporal distribution and source characteristics of metal components in PM2.5.