Zhu Rencheng, Wei Yangbing, He Liqiang, Wang Menglei, Hu Jingnan, Li Zhenhua, Lai Yitu, Su Sheng
School of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, China; Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
School of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, China.
Sci Total Environ. 2024 May 20;926:171791. doi: 10.1016/j.scitotenv.2024.171791. Epub 2024 Mar 19.
Fine particulate matter (PM) from vehicle exhaust is typically emitted at breathing height and thus imposes severe adverse effects on human health and air quality. However, there is currently limited knowledge on the characteristics of PM in exhaust, specifically its chemical components, at different ambient temperatures. Particulate emissions from typical light-duty gasoline vehicles (LDGVs) were investigated on a chassis dynamometer according to the Worldwide Harmonized Light-Duty Test Cycle at ambient temperatures of 38 °C, 28 °C, 15 °C, 5 °C and - 7 °C. The results showed a significant increase in particulate mass (PM) and particle number (PN) emissions with decreasing ambient temperature, particularly during cold starts below 5 °C. The particle size distributions exhibited distinct bimodal patterns, with accumulation-mode (AM) particles (60-125 nm) dominating the gasoline direct injection (GDI) distribution and nucleation-mode (NM) particles (8-12 nm) dominating the port fuel injection (PFI) distribution. AM particles were more temperature-sensitive than NM particles. Lower temperatures produced higher emissions of elements, carbonaceous components, and large-ring polycyclic aromatic hydrocarbons, while water-soluble ions showed an opposite trend. The total toxic equivalent, primarily influenced by benzo[a]pyrene, was significantly higher at -7 °C. The penalty distribution of LDGV PM and PN, defined by comparing the emissions at the various temperatures to those at regulated temperatures (23-30 °C), exhibited notable temporal heterogeneity (winter > autumn > spring > summer) and spatial heterogeneity (northern China > southern China). These findings are essential for establishing more stringent vehicle emission standards and improving emission models in cold environments.
汽车尾气中的细颗粒物（PM）通常在呼吸高度排放，因此对人类健康和空气质量造成严重不利影响。然而，目前对于不同环境温度下尾气中PM的特性，特别是其化学成分的了解有限。根据世界统一轻型车辆测试循环，在底盘测功机上对典型轻型汽油车（LDGV）在38°C、28°C、15°C、5°C和 -7°C的环境温度下的颗粒物排放进行了研究。结果表明，随着环境温度降低，颗粒物质量（PM）和颗粒数量（PN）排放显著增加，特别是在5°C以下的冷启动期间。粒径分布呈现出明显的双峰模式，其中积聚模式（AM）颗粒（60 - 125纳米）在汽油直喷（GDI）分布中占主导，成核模式（NM）颗粒（8 - 12纳米）在进气道燃油喷射（PFI）分布中占主导。AM颗粒比NM颗粒对温度更敏感。较低温度下元素、碳质成分和大环多环芳烃的排放量更高，而水溶性离子则呈现相反趋势。主要受苯并[a]芘影响的总毒性当量在 -7°C时显著更高。通过将不同温度下的排放与规定温度（23 - 30°C）下的排放进行比较来定义的LDGV PM和PN的惩罚分布呈现出显著的时间异质性（冬季>秋季>春季>夏季）和空间异质性（中国北方>中国南方）。这些发现对于制定更严格的车辆排放标准和改进寒冷环境下的排放模型至关重要。
