城市隧道机动车细颗粒物排放研究

Study on Pollutants Emitted from Motor Vehicle in Urban Tunnel

机动车尾气排放的颗粒物对城市大气污染影响作用日趋明显,本文选取南宁市凤岭南隧道对机动车排放颗粒物的浓度及其成分进行监测分析,结果显示,实验期间隧道内外3个采样点处的PM2.5平均质量浓度值分别为166.869,237.529,111.314μg/m3,且浓度变化趋势基本相似.隧道内机动车排放的PM2.5中含碳物质所占的比重最大,水溶性离子次之,金属元素最少.其中,含碳物质中EC的浓度大于OC,OC/EC的值约为0.511-0.660,而隧道重型车比重并不大,但EC与重型车的相关系数在0.59-0.89间,可见其对颗粒物污染的影响很大.此外,金属元素Ca及其水溶性离子Ca2＋的占比均是最大的,表明机动车带起的扬尘加重了颗粒物污染.

The effect of vehicle exhaust emissions on air pollution is becoming more and more obvious. It is analyzed the particle concentration and composition of the vehicle emissions in South Fengling tunnel in Nanning city. The results show that the average mass concentrations of PM2.5 in three sampling points are 166. 869 μg/ma, 237. 529 μg/m3, 111. 314μg/m3 and have the similar daily variation. In the tunnel, the carbon content in PM2. 5 emitted from the vehicle is the largest, and the water soluble ion is second, while the metal element is the least. NO3- , SO4 2-, Ca2＋ are the main ions in the Water soluble ions, it is up to about 90% in the total ions, crust elements, such as Fe, Al and Ca are dominant in the metal elements, that means the vehicle＇s dust enhanced the particulate matter pollution. The concentration of EC in PM2.5 is more than OC, the ratio of OC/EC is about 0. 511-0. 660, which indicates that proportion of the heavy vehicles in tunnel is small, but it has a great influence on the particle pollution.