Institute of Mass Spectrometry and Atmospheric Environment, Jinan University, Guangzhou 510632, PR China.
State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China; Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou 510640, PR China.
J Hazard Mater. 2021 Sep 15;418:126304. doi: 10.1016/j.jhazmat.2021.126304. Epub 2021 Jun 10.
The rapid development of cities and economic prosperity greatly motivates the growth of vehicular exhaust particles, especially the diesel-exhausted particles from the large fleet of passenger and freight, which present profound implications on climate, air quality, and biological health (e.g., pulmonary, autoimmune and cardiovascular diseases). As important physiochemical properties of atmospheric aerosols, however, the mixing state and effective density of individual particles emitted from diesel-powered vehicles under different driving conditions and their environmental implications remain uncertain. Here, a single-particle aerosol mass spectrometer (SPAMS) was used to investigate the chemical composition and vacuum aerodynamic diameter (D), along with the aerodynamic diameter (D) from an aerodynamic aerosol classifier (AAC), to determine the effective density of primary particles emitted from a light- duty diesel vehicle (LDDV) under the launching and idling engine states. Interestingly, the particle types and effective density appear to vary significantly with the engine status. A single particle type of Ca-rich particles, named Na-Ca-PAH, was predominant in the idling state, whose chemical components may be affected by the lubricants and incomplete combustion, contributing to a higher effective density (0.66 ± 0.21 g cm). In contrast, launching particles exhibited a lower effective density (0.34 ± 0.17 g cm) because of the substantial elemental carbon (EC). In addition, the effective density depends not only on the particle size but also on the chemical components with various abundances. EC and Ca play opposite roles in the effective density of LDDV emissions. Notably, a higher proportion of polycyclic aromatic hydrocarbons (PAHs) was observed in the idling particles, contributing to 78 ± 1.2%. Given the high contribution to these PAH-containing particles in the idling state, indispensable precautions should be taken at bus stops or waiting for pedestrians. This study provides more comprehensive insights into the initial characteristics of LDDV particles due to the launching and idling states, which is beneficial for improving the model results of source apportionment and understanding its environmental behavior regarding human health.
城市的快速发展和经济繁荣极大地推动了车辆排放颗粒的增长，尤其是来自客运和货运大型车队的柴油废气颗粒，这对气候、空气质量和生物健康（如肺部、自身免疫和心血管疾病）都有着深远的影响。然而，作为大气气溶胶的重要物理化学性质，在不同行驶条件下，来自柴油动力车辆的单个颗粒的混合状态和有效密度及其环境影响仍然不确定。在这里，使用单颗粒气溶胶质谱仪（SPAMS）来研究化学组成和真空空气动力学直径（D），以及使用空气动力学气溶胶分类器（AAC）确定从轻型柴油车（LDDV）排放的初级颗粒的有效密度在启动和怠速发动机状态下。有趣的是，颗粒类型和有效密度似乎随着发动机状态的变化而显著变化。在怠速状态下，主要的颗粒类型是富含钙的颗粒，称为 Na-Ca-PAH，其化学成分可能受到润滑剂和不完全燃烧的影响，导致更高的有效密度（0.66±0.21gcm）。相比之下，由于大量的元素碳（EC），启动颗粒的有效密度较低（0.34±0.17gcm）。此外，有效密度不仅取决于颗粒尺寸，还取决于具有各种丰度的化学组分。EC 和 Ca 在 LDDV 排放的有效密度中起着相反的作用。值得注意的是，在怠速颗粒中观察到更高比例的多环芳烃（PAHs），占 78±1.2%。鉴于在怠速状态下这些含 PAH 颗粒的高贡献，在公共汽车站或等待行人时应采取不可缺少的预防措施。本研究由于启动和怠速状态，提供了对 LDDV 颗粒初始特征的更全面的了解，这有利于提高源分配模型的结果并理解其对人类健康的环境行为。
