山地城市长上坡路段PM2.5浓度分布特性实测研究

与平原地区城市相比，由于山地城市地形地貌的因素，城市道路具有坡度大、弯道多、路窄、起伏大等特点。车辆在道路上行驶相较于平原存在巨大差异，使得这种道路更容易产生交通污染，为明确山地城市道路长上坡路段汽车尾气与细飘尘排放浓度及其影响因素，特选取重庆主城多条具有代表性的道路采集汽车尾气与细飘尘浓度值，采用交通系统仿真分析方法分析车流量、区域差异、横向距离等对汽车尾气与细飘尘浓度的影响。结果表明：夜间汽车尾气与细飘尘（PM2.5）浓度较日间差异性显著；整体上看，随着横向距离的增加，汽车尾气与细飘尘浓度不断衰减，根据实验结果，日间PM2.5浓度先衰减，当处于横向距离6-10m之间PM2.5浓度出现向上波动，最后下降至稳定值，而夜间PM2.5浓度呈波动式衰减，最后趋于稳定；车流量的大小不是决定山地城市日间上坡路段道路旁PM2.5数值大小的最直接原因；同一个城市的不同区域，道路两旁空气中的PM2.5浓度的含量存在巨大的差异。

Field measurement of PM2.5 concentration distribution in long uphill section of mountain city

Compared with the plain area of the city, because of the topography of the mountain city, city road has the characteristics of steep slope, bend, narrow, high relief etc.. Vehicles on the road compared to the plain there is a huge difference, make the road more prone to traffic pollution, to identify factors of mountainous city road long uphill section of automobile exhaust and dust emission concentration and fine effect, selecting Chongqing city more representative road collection vehicle exhaust and fine dust concentration value analysis method effect of traffic flow, regional difference, horizontal distance of automobile exhaust and fine dust concentration by traffic simulation system. The results demonstrate that the concentration of vehicle exhaust and fine dust (PM2.5) at night is differs greatly from it at daytime; on the whole, with the increase of the horizontal distance, vehicle exhaust and fine dust concentration to decay, according to the experimental results, the first day PM2.5 concentration decay, when in the lateral distance between 6-10m PM2.5 concentration appeared to fluctuate, down to the final stable value, and the night PM2.5 concentration was fluctuant attenuation, and finally tends to be stable; the most direct reason is not decided the size of the mountain city day uphill road traffic flow near the PM2.5 value; the same city in different areas, there is a huge difference in the concentration of PM2.5 on both sides of the road in the air.