缸内直喷汽油车颗粒物化学组分特征

随着缸内直喷汽油车（GDI）的大量使用，其尾气颗粒物排放问题日益凸显.研究缸内直喷汽油车尾气颗粒物构成组分是有效控制其颗粒物排放的重要前期工作之一.选取了5辆满足国六排放标准的缸内直喷汽油车进行了尾气颗粒物碳质成分、水溶性离子和多环芳烃（PAHs）组分分析.结果发现，各类碳质是测试车辆尾气颗粒物中的主要成分，平均占比约70%.颗粒物碳质中有机碳质（OC）多于核态碳质（EC），OC/EC比值在1.03~3.43之间.测量了颗粒物中多种水溶性离子的含量，结果表明Ca²⁺和SO₄^2-是尾气颗粒物中的主要水溶性离子，主要来源均为机油添加剂.此外，结果还发现GDI车辆尾气颗粒物中高环PAHs排放占比较高，对人体健康危害大，需要重点关注.

Chemical Characterizations of Particles from Direct-injection Gasoline Vehicles

With the widespread use of direct-injection gasoline vehicles, their tailpipe particulate emissions are becoming a serious problem for the urban atmosphere. The study of tailpipe particulate components from direct-injection gasoline vehicles is an important preliminary work to control particulate emissions effectively. In this study, five direct-injection gasoline vehicles meeting the China-6 emission standard were tested to analyze the carbonaceous components, water-soluble ions, and polycyclic aromatic hydrocarbons of tailpipe particulate emissions. It was found that carbonaceous substances were the major components of exhaust particles, accounting for approximately 70%. More organic carbon than elemental carbon was found in the particulate emissions of direct-injection gasoline vehicles, with OC/EC ratios of 1.03 to 3.43. The study also measured various water-soluble ions of particles. The total mass proportions of water-soluble ions were 11.3% to 17.6%. Ca²⁺ and SO₄^2- were the main water-soluble ions, with oil additives being the main source of these two ions. In addition, it was found that the PAHs emissions were significantly reduced with stricter regulations. PAHs emission factors of GDI vehicles meeting the China-6 standard were reduced by more than half of the emission factors of China-6-standard GDI vehicles. Moreover, GDI vehicles had a high proportion of high-cyclic PAHs emissions in exhaust particles, which damages public health and requires more attention.