On-Road Particulate Matter (PM2.5 and PM10) Emissions in the Sepulveda Tunnel, Los Angeles, California

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• 作者：J. A. Gillies ; A. W. Gertler ; J. C. Sagebiel ; and W. A. Dippel
• 刊名：Environmental Science & Technology
• 出版年：2001
• 出版时间：March 15, 2001
• 年：2001
• 卷：35
• 期：6
• 页码：1054 - 1063
• 全文大小：124K
• 年卷期：v.35,no.6(March 15, 2001)
• ISSN：1520-5851

文摘

Total and speciated particulate matter (PM_2.5 and PM₁₀)emission factors from in-use vehicles were measured fora mixed light- (97.4% LD) and heavy-duty fleet (2.6%HD) in the Sepulveda Tunnel, Los Angeles, CA. Seventeen1-h test runs were performed between July 23, 1996,and July 27, 1996. Emission factors were calculated frommass concentration measurements taken at the tunnelentrance and exit, the volume of airflow through the tunnel,and the number of vehicles passing through the 582 mlong tunnel. For the mixed LD and HD fleet, PM_2.5 emissionfactors in the Sepulveda Tunnel ranged from 0.016(±0.007) to 0.115 (±0.019) g/vehicle·km traveled with anaverage of 0.052 (±0.027) g/vehicle·km. PM₁₀ emission factorsranged from 0.030 (±0.009) to 0.131 (±0.024) g/vehicle·km with an average of 0.069 (±0.030) g/vehicle·km. The PM_2.5emission factor was ~74% of the PM₁₀ factor. Speciatedemission rates and chemical profiles for use in receptormodeling were also developed. PM_2.5 was dominated byorganic carbon (OC) (31.0 ± 19.5%) and elemental carbon(EC) (48.5 ± 20.5%) that together account for 79% (±24%)of the total emissions. Crustal elements (Fe, Mg, Al, Si, Ca,and Mn) contribute ~7.8%, and the ions Cl^-, NO₃^-,NH₃⁺, SO₄^2-, and K⁺ together constitute another 9.8%. Inthe PM₁₀ size fraction the particulate emissions were alsodominated by OC (31 ± 12%) and EC (35 ± 13%). Thethird most prominent species was Fe (18.5 ± 9.0%), whichis greater than would be expected from purely geologicalsources. Other geological components (Mg, Al, Si, K, Ca, andMn) accounted for an additional 12.6%. PM₁₀ emissionfactors showed some dependence on vehicle speed, whereasPM_2.5 did not. For test runs in which the average vehiclespeed was 42.6 km/h a 1.7 times increase in PM₁₀ emissionfactor was observed compared to those runs with anaverage vehicle speed of 72.6 km/h. Speciated emissionswere similar. However, there is significantly greater massattributable to geological material in the PM₁₀, indicativeof an increased contribution from resuspended road dust.The PM_2.5 shows relatively good correlation with NO_xemissions, which indicates that even at the low percentof HD vehicles, which emit significantly more NO_x than LDvehicles, they may also have a significant impact on thePM_2.5 levels.