| Along with improvement of the public living standard and the continually and rapidly growth of vehicle’population, motor vehicles have gradually become one of major sources of fine particulate air pollution in cities. In previous research, PM2.5 emitted by light-duty gasoline vehicle were paid little attention, though the population of this vehicle type is the maximum, and increasing rate is very high. Some studies have showed that PM2.5 emissions from the old gasoline vehicles can’t be ignored. As a result, the contribution of vehicle emission in atmosphere increases prominent. Heavy-duty diesel trucks, because of their high PM2.5 emission factors, are always key vehicle model on the study of PM2.5 exhausted by motor vehicle. With the continuous upgrading of control technology, the emission characteristics of heavy-duty diesel trucks are changing. Therefore the object of this study is to establish PM2.5 emission inventory based on both the light-duty gasoline vehicles and the heavy-duty diesel trucks.PM2.5 emission factors of the light-duty gasoline and heavy-duty diesel vehicles were obtained based on the collected and analyzed the data of the 9 gasoline vehicles and 14 diesel trucks. This result could provide basic data support for the establishment of the two models of vehicles PM2.5 emission inventory. The emission characteristics of carbonaceous and PAHs were researched through the analysis of the carbonaceous and PAHs of the PM2.5. Based on experiments, data collection, comparative analysis and summary, PM2.5 emission factors, vehicle kilometers traveled and vehicle population, which can be used for estimating the amount of PM2.5 emitted by light-duty gasoline vehicles and heavy-duty diesel trucks, were obtained. Finally, the amount of PM2.5 emitted by the two vehicle models was calculated, and the uncertainty of amount was analyzed.The results show that:(1) In terms of tested light-duty gasoline, PM2.5 emission factors from China Ⅰ to ChinaⅣ are (50.5±45.4), (34.7±18.4), (22.6±10.3) and (1.0±0.2) mg/km, respectively. Along with the continuously tightened emissions standards, PM2.5 emission factors of light-duty gasoline vehicles decreased obviously.(2) Through comprehensively analyzing on domestic and overseas advance about light-duty gasoline vehicles emission researches, PM2.5 emission factors, which can be used to estimate the amount of PM2.5, were obtained. The results shows that:emission factors, from Pre-China Ⅰ to ChinaⅣ, are (80.4±25.2), (35.9±13.4), (18.1±13.1), (9.2±9.6) and (1.6±1.8) mg/km, respectively. According to light-duty gasoline vehicles population, vehicles sales, survival curve and vehicle kilometer traveled, it is calculated that light-duty gasoline vehicles emitted 21800 tons PM2.5 in 2012, which fills the blank of PM2.5 emission emitted by motor vehicles.(3) In terms of tested heavy-duty diesel trucks, PM2.5 emission factors from China Ⅰ to China Ⅳ are (316.9±292.9), (148.0±82.6), (49.9±24.4) and 38.7mg/km, respectively. Along with emission standards, heavy-duty diesel trucks’ PM2.5 emission factors decreased obviously.(4) According to the comprehensively analyzing on heavy-duty diesel trucks’ PM2.5 emission characteristic, PM2.5 emission factors, which can be used to estimate the amount of PM2.5, were acquired. The results shows that emission factors from Pre-China Ⅰ to ChinaⅣ are (1.198±0.12), (0.525±0.258), (0.401±0.157), (0.181 ±0.074) and (0.108±0.01)g/km, respectively. According to vehicles population, annual sales, survival curve and vehicle kilometer traveled, the amount of PM2.5 emission from heavy-duty diesel trucks in 2012, was calculated. The amount of PM2.5 emitted by heavy-duty diesel trucks is 101279 tons, which is different from the conclusion of "motor vehicle pollution control annual report". The discrepancy likely rooted in the difference of emission factors and vehicles kilometer traveled. The amount of PM2.5 emission in the report is likely over-estimated.(5) Through the analyzing carbonaceous and PAHs of collected PM2.5, the results show that:OC in TC percentage, for light-duty gasoline vehicle, is more than 90%, and EC account for less than 10%. However, EC in TC, for heavy-duty diesel trucks, significantly higher than that of light-duty gasoline vehicles. Heavy-duty diesel trucks’ EC proportion in TC is from 10% to 60%.16 kinds of Σ PAHs emission factor from heavy-duty diesel trucks is between 33.2-214.1 ug/km, the average emission factor is 103.2±76.9ug/km. |
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