Monitoring of PCBs and PCNs using passive air samplers in the metropolitan city of Seoul, South Korea: Spatial distribution, seasonal variation, source identification

Abstract

Polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) are persistent organic pollutants (POPs) and semi-volatile organic compounds characterized by toxicity, bioaccumulation, and environmental persistence. PCBs and PCNs are unintentionally produced during combustion processes or released from legacy commercial products, and they can accumulate in environmental media with the potential for re-emission into the atmosphere, leading to their continuous presence in urban air. In this study, seasonal monitoring of atmospheric PCBs and PCNs was conducted across Seoul, a major metropolitan city in East Asia, using polyurethane foam passive air samplers (PUF-PASs). Samples were Soxhlet-extracted, cleaned up using multi-layer silica gel columns, and analyzed by gas chromatography coupled with a high-resolution mass spectrometer (GC/HRMS). Mean Σ30 PCB concentrations were significantly higher in summer than in winter, suggesting temperature-driven volatilization and strong influences from legacy sources. Mean Σ15 PCN concentrations were also elevated during summer, with higher levels observed in the southwestern part of Seoul, indicating additional contributions from industrial activities. In winter, long-range atmospheric transport under prevailing wind conditions may further influence PCB and PCN concentrations. Principal component analysis indicated that atmospheric PCBs were primarily associated with historical technical mixtures, whereas PCNs reflected mixed contributions from legacy use and combustion-related sources in both seasons. Overall, this study provides high-resolution spatial and seasonal information on atmospheric PCBs and PCNs in a densely populated urban environment.