Particulate nitrosamines in the atmosphere at Seoul and their major sources

Five nitrosamines (nitroso-methyl-ethylamine (NMEA), nitroso-pyrrolidine (NPYR), nitrosodi-ethylamine (NDEA), nitroso-piperidine (NPIP), and nitrosodi-butylamine (NDBA)) in the atmospheric particulate matter with an aerodynamic diameter of less than or equal to a nominal 10 μm (PM₁₀) at Seoul were identified and quantified by using a gas chromatography/mass spectrometry (GC/MS) in chemical ionization (CI) mode. The average ambient concentrations of the sum of the five nitrosamines showed a distinctive seasonal pattern, higher in winter (2.79 ± 1.41 ng/m³) than in summer (0.92 ± 0.29 ng/m³). Diurnal pattern showed slightly higher in night time (1.67 ± 1.47 ng/m³) than day time (1.57 ± 1.04 ng/m³) but it was not statistically significant. Possible contributors of nitrosamines were discussed based on various statistical analyses. Since BaP/BeP ratio and nitrosamines’ concentrations showed negative correlation, indicating aged aerosols containing more nitrosamines, it was suggested that nitrosamines might be produced by the atmospheric reactions. However, the correlations of nitrosamines with PAHs, CO, and SO₂ were also good which were emitted from the primary emission sources, suggesting the particulate nitrosamines observed at Seoul could be also emitted from the primary emission sources. Primary emission sources were also identified by using the principal component analysis (PCA). It was concluded that NDBA could be mainly emitted from plastic and rubber combustions, release of landfill and tobacco smoke, and NPYR and NDEA might be emitted from the vehicular emission and cooking. The other nitrosamines, NMEA and NPIP, which were not included in both factors and showed relatively higher negative correlation with BaP/BeP ratios than other nitrosamines, could be produced from the atmospheric reactions.