Spatial and Temporal Distribution Characteristics of VOCs in Seoul Ambient Air and Identification of Potential Pollution Sources Using Principal Component Analysis.

This study analyzed the spatial distribution and seasonal variation characteristics of Volatile Organic Compounds (VOCs) at four sites (GS, GJ, BHS, and JN) representing different emission environments in Seoul and identified potential pollution sources using principal component analysis (PCA). The results showed that VOC concentrations were relatively high at the GS site, which is influenced by both industrial and traffic emissions, and at the JN site, characterized by heavy urban traffic, whereas the BHS site, representing a background area, exhibited the lowest concentrations, indicating clear spatial heterogeneity. Alkanes accounted for the largest proportion of VOCs at all sites, and low-molecular-weight alkanes as well as combustion-related compounds showed elevated concentrations during winter. In contrast, aromatic compounds exhibited site-specific seasonal patterns, with relatively higher concentrations observed during summer or autumn at some locations. The diurnal variation patterns displayed a bimodal distribution with concentration peaks during morning and evening rush hours, indicating the direct influence of traffic emissions. Furthermore, the T/B ratio and PCA results suggested that vehicle emissions and combustion sources were the dominant contributing factors (PC1) to ambient VOCs in Seoul, while non-road emission sources such as solvent use and industrial activities, characterized mainly by aromatic compounds, also contributed significantly (PC2). The findings of this study can serve as fundamental data for future quantitative source apportionment studies and the development of risk-based air quality management strategies for VOCs in Seoul.