Temporal Trend of Polycyclic Aromatic Hydrocarbons in Atmosphere: A Case Study within 24 h after Snowfall

Based on air samples within 24 h after snowfall, gaseous and particulate concentrations of 16 priority PAHs were obtained, which provided a good opportunity to study the temporal trend of atmospheric PAHs. An obvious temporal trend with atmospheric concentration was observed, which was mainly influenced by emission sources. It was found that the maximum concentration (Σ₁₆PAHs) was 272.8 ng/m³, appeared in the rush hour of traffic. To the contrary, the minimum concentration was 82.39 ng/m³ at the period with the least anthropogenic activities. The values of particle-phase fraction ɸ_p and G/P partitioning quotient (log K_P) were increased along with molecular weight of PAHs. However, for individual PAHs, the differences with ɸ_p and log K_P were not obvious within 24 h. Furthermore, similar statistically significant positive correlations were found between log K_P and log K_OA among different periods. According to the short sampling program, chemical properties should be the major influencing factor for the temporal trend of G/P partitioning. The results of the case study provided new insights into the research field of G/P partitioning of PAHs.