[Pollution Characteristics and Health Risk Assessment of Polycyclic Aromatic Hydrocarbons and Their Derivatives in Urban Shanghai].

Abstract

Polycyclic aromatic hydrocarbons （PAHs） and their derivatives, nitrated polycyclic aromatic hydrocarbons （NPAHs） and oxygenated polycyclic aromatic hydrocarbons （OPAHs）, have been under constant scrutiny for their prominent carcinogenicity and mutagenicity. In this study, fine particulate matter （PM_2.5） was collected in the urban area of Shanghai from 2022 to 2023. Their diurnal and nocturnal mass concentration variations, sources, and health risk assessment were analyzed. Two-dimensional gas chromatography-time-of-flight mass spectrometry （GC×GC-ToF-MS） was used to quantify PAHs, NPAHs, and OPAHs. The results showed that the daily average concentrations of PAHs, NPAHs, and OPAHs were 4.44, 0.89, and 2.38 ng·m^-3, respectively, in winter. The concentration levels were much lower in summer than those in winter, which were 0.20, 0.04, and 0.40 ng·m^-3, respectively. The ratio of the concentrations of NPAHs to those of PAHs and OPAHs concentrations by 1-2 orders of magnitude. The substance concentrations of PAHs and NPAHs in summer were higher in the daytime than those at nighttime and vice versa for OPAHs. Concentrations of the few target substances in winter samples were higher at night. The substances with the highest concentrations of PAHs during the sampling period were fluoranthene and benzo（b）fluoranthene, whereas the substances with the highest concentrations of NPAHs and OPAHs were 9-nitroanthracene and 9,10-anthraquinone, respectively. Based on the results of correlation analysis and source analysis by the diagnostic ratios, PAHs and their derivatives in PM_2.5 in the urban area of Shanghai were affected by mixed emission sources, with primary emissions accounting for a significant portion. In addition to vehicle emissions and some coal and biomass combustion, the generation of PAHs was also affected by aerosol aging. Vehicle emissions were the major source of NPAHs, whereas OPAHs might be from the same primary emission sources as those of PAHs. Primary emissions contributed more to PAHs in winter than in summer. Comparison of the toxic equivalents of PAHs, NPAHs, and OPAHs in PM_2.5 in winter and summer during the sampling period revealed that the average daily TEQ value was higher in winter （441.4 pg·m^-3） than that in summer （39.8 pg·m^-3）, which was consistent with the seasonal variation of mass concentrations. The toxicity of PAHs and their derivatives in PM_2.5 in the Shanghai urban area was higher during nighttime than that in the daytime. Most of the potential carcinogenic risk originated from PAHs, and the ILCR values caused by NPAHs and OPAHs were 1-2 orders of magnitude lower than those caused by PAHs. The results of health risk assessment based on incremental lifetime cancer risk modeling showed that the total cancer risk was higher in adults than that in adolescents and children and that females had a higher cancer risk than males through different exposure pathways. Adults had a higher risk of cancer from respiratory inhalation and dermal exposure than that of adolescents and children, whereas adolescents had a higher risk of cancer from oral ingestion. The results showed that the carcinogenic risk of PAHs and their derivatives in the atmosphere in the urban area of Shanghai in winter and summer was within controllable range.