Na Kwangsam
Bourns College of Engineering, Center for Environmental Research and Technology, University of California, Riverside, CA 92507, USA.
J Environ Manage. 2006 Dec;81(4):392-8. doi: 10.1016/j.jenvman.2005.11.004. Epub 2006 Apr 17.
This study describes the methodology used to obtain the volatile organic compound (VOC) source signature of vehicle exhaust. To accomplish this, C(2)-C(9) VOCs were measured in a traffic tunnel located in Seoul, South Korea. The effect of VOC concentrations from the outside ambient air was considered in the determination of the source signature. To examine the effects of ambient air on VOC concentrations inside the tunnel, the ratio of propane to the total VOC concentrations was compared between the entrance and middle sites in the tunnel. Propane was used as a standard not only because of its insignificant contribution to vehicle exhaust gas, but also the fact that propane is the most abundant VOC in the atmosphere of Seoul. The ratio of propane to the total VOC concentrations was higher at the entrance site than at the middle location by, on average, 60%. This suggests that ambient air affects the inside tunnel air to a greater extent at the entrance site as compared to the middle site. The contribution of ambient air to the air inside the tunnel at the entrance location varied from 30% to 67%, with an average of 55%. This is 1.5 times higher than the value measured at the middle location, which ranged from 20% to 48%, with an average of 36%. This shows that ambient air substantially affects the inside air of the tunnel. Excluding the effects of ambient air on the air inside the tunnel can provide an improved chemical composition for vehicle exhaust using tunnel measurements. We believe that the concentration difference between the two sites within the tunnel provides a more accurate chemical composition of vehicle exhaust as compared to that obtained from a measurement taken at only one point inside the tunnel.
本研究描述了用于获取汽车尾气挥发性有机化合物（VOC）源特征的方法。为此，在韩国首尔的一条交通隧道中对C(2)-C(9)挥发性有机化合物进行了测量。在确定源特征时考虑了外部环境空气中挥发性有机化合物浓度的影响。为了研究环境空气对隧道内挥发性有机化合物浓度的影响，比较了隧道入口和中间位置丙烷与总挥发性有机化合物浓度的比值。丙烷被用作标准，不仅是因为它对汽车尾气的贡献微不足道，还因为丙烷是首尔大气中含量最丰富的挥发性有机化合物。入口处丙烷与总挥发性有机化合物浓度的比值平均比中间位置高60%。这表明与中间位置相比，环境空气在入口处对隧道内空气的影响更大。入口处环境空气对隧道内空气的贡献在30%至67%之间，平均为55%。这比在中间位置测得的值高1.5倍，中间位置的值在20%至48%之间，平均为36%。这表明环境空气对隧道内空气有显著影响。排除环境空气对隧道内空气的影响，可以通过隧道测量为汽车尾气提供改进的化学成分。我们认为，与仅在隧道内一个点进行测量相比，隧道内两个位置之间的浓度差异能提供更准确的汽车尾气化学成分。
