轻型汽油车尾气PM2.5的排放特征

为研究轻型汽油车尾气PM_2.5的排放特征,利用整车测试台架和颗粒物稀释采样系统,对12辆轻型汽油车尾气的PM_2.5进行了采集,并进一步分析了PM_2.5排放因子及其碳质组分——OC(有机碳)和EC(元素碳)的排放特征；在此基础上,参考文献研究结果,计算了我国轻型汽油车分阶段PM_2.5排放因子,结合活动水平数据估算轻型汽油车PM_2.5排放量.结果表明:测试的国Ⅰ前~国Ⅳ轻型汽油车PM_2.5平均排放因子分别为(73.2±3.8)(50.5±45.4)(34.7±18.4)(22.6±10.3)和(1.0±0.2)mg/km,随排放阶段升级而显著降低.OC是轻型汽油车尾气PM_2.5中的主要碳质组分,在TC(总碳)中所占比例超过90%. 2012年我国轻型汽油车PM_2.5排放量为21 828.7 t,占机动车颗粒物排放总量的3.5%,其中仅占轻型汽油车保有量17%的国Ⅰ及以前车辆排放了约43%的PM_2.5. 研究显示,轻型汽油车尤其是国Ⅰ及国Ⅰ前车辆颗粒物排放不容忽视,在机动车颗粒物减排工作中应给予足够重视. 

Emission Profile of Exhaust PM2.5 from Light-Duty Gasoline Vehicles

Abstract:Particulate matter emissions from gasoline vehicles have been left unnoticed for a long time. With the constant growth in population of gasoline vehicles in China, their contribution to ambient PM_2.5 should be paid more attention to. To investigate the emission profile of exhaust PM_2.5 of gasoline vehicles, PM_2.5 from twelve light-duty gasoline vehicles (LDGVs) was sampled on a vehicle test bench and with a particle dilution and sampling system. Emission factors of PM_2.5 and the profile of carbonaceous fraction (e.g., organic carbon, OC and elemental carbon, EC) were further analyzed. Meanwhile, literature investigation was also carried out to determine the PM_2.5 emission factors of China's LDGVs by emission standards, so that by integrating the activity data the PM_2.5 emission amount of LDGVs could be estimated. The results showed that the average PM_2.5 emission factors of Pre-China Ⅰ, China Ⅰ, China Ⅱ, China Ⅲ and China Ⅳ LDGVs were (73.2±3.8)(50.5±45.4) (34.7±18.4)(22.6±10.3) and (1.0±0.2)mg/km, respectively, which shows a clear decline in emissions with the enhancement of emission standards. In terms of carbonaceous fraction, OC was the main component, accounting for more than 90% of the TC by mass. In 2012, the amount of PM_2.5 emitted by LDGVs in China was 21,8.7 tons, which accounted for 3.5% of the total PM emitted by vehicles. In addition, 43% of the PM_2.5 emitted by LDGVs came from the Pre-China I and China I LDGVs that only had a share of 17% of the total population. The investigation implies that LDGVs, especially Pre-ChinaⅠ and ChinaⅠ LDGVs, emitted considerable particle matters, which should be taken into account in the prevention and control of motor vehicles' particle emissions.