Department of Environmental Sciences and Engineering, Xi'an Jiaotong University, Xi'an, 710049, China; Key Lab of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 200241, China.
Department of Environmental Sciences and Engineering, Xi'an Jiaotong University, Xi'an, 710049, China.
Environ Res. 2022 Sep;212(Pt C):113357. doi: 10.1016/j.envres.2022.113357. Epub 2022 May 14.
A vehicular emission study was conducted in the longest inner-city tunnel in Xi'an, northwestern China in four time periods (I: 07:30-10:30, II: 11:00-14:00, III: 16:30-19:30, and IV: 20:00-23:00 LST). A sum of 40 PAHs, including parent (p-PAHs), alkylated (a-PAHs), and oxygenated (o-PAHs) in fine particulate matter (PM) were quantified. The relationships between the PAHs and the formation of reactive oxygen species (ROS) were also studied. The average total quantified PAHs concentration was 236.3 ± 48.3 ng m. The p-PAHs were found to be the most dominated group, accounting for an average of 88.1% of the total quantified PAHs, followed by a-PAHs (6.1%) and o-PAHs (5.8%). On the base of the number of aromatic rings, the groups of ≤5 rings (92.5 ± 1.2%) had higher fractions than the high ones (≥6 rings, 7.5 ± 1.2%) for pPAHs. Diurnal variations of PAHs subgroups exhibited the highest levels in Period III, consistent with the largest traffic counts in evening rush hours. However, less reduction of few PAHs in the night period demonstrates that the emissions of compressed natural gas (CNG) and methanol-fueled vehicles cannot be ignored while their contribution increased. High ROS activity levels were observed in the traffic-dominated samples, implying the potential oxidative damages to humans. Additionally, diurnal variation of the ROS activity was consistent with the total quantified PAHs and toxic equivalency of benzo[a]pyrene. Good correlations (R > 0.6, p < 0.05) were seen between individual groups of PAHs (especially for 3-5 rings p-PAHs, 4 rings a-PAHs, and 2-3 rings o-PAHs) and ROS activity, supporting that the vehicular emitted PAHs possibly initiate oxidative stress. The multiple linear regression analysis further illustrated that chrysene contributed the highest (25.0%) to ROS activity. In addition to highlighting the potential hazards to the PAHs from the vehicular emission, their roles to mitigate the health effects by formations of ROS were firstly reported in northwestern China.
在中国西北部的西安市，进行了一项在最长的市内隧道内的车辆排放研究，共分为四个时间段（I：07:30-10:30，II：11:00-14:00，III：16:30-19:30，和 IV：20:00-23:00 LST）。定量分析了细颗粒物（PM）中 40 种多环芳烃（PAHs），包括母体（p-PAHs）、烷基化（a-PAHs）和含氧（o-PAHs）。还研究了 PAHs 与活性氧物种（ROS）形成之间的关系。PAHs 的平均总浓度为 236.3±48.3ng/m。发现 p-PAHs 是最主要的组，占总定量 PAHs 的平均 88.1%，其次是 a-PAHs（6.1%）和 o-PAHs（5.8%）。基于芳香环的数量，低环（≤5 环）组（92.5±1.2%）的分数高于高环（≥6 环，7.5±1.2%）的分数。pPAHs 组的日变化在第三期达到最高水平，与傍晚交通高峰期的最大交通量一致。然而，夜间少数 PAHs 的减少量较少，表明在压缩天然气（CNG）和甲醇燃料车辆的排放量不可忽视，尽管它们的贡献有所增加。在以交通为主的样本中观察到高 ROS 活性水平，这意味着可能对人体造成氧化损伤。此外，ROS 活性的日变化与总定量 PAHs 和苯并[a]芘的毒性等效性一致。个体 PAHs 组（特别是 3-5 环的 p-PAHs、4 环的 a-PAHs 和 2-3 环的 o-PAHs）与 ROS 活性之间存在良好的相关性（R>0.6，p<0.05），表明车辆排放的 PAHs 可能引发氧化应激。多元线性回归分析进一步表明，䓛对 ROS 活性的贡献最大（25.0%）。除了强调车辆排放的 PAHs 可能带来的潜在危害外，它们在西北中国形成 ROS 以减轻健康影响的作用也被首次报道。
