某高密度街区大气颗粒物质量浓度分布特征实测研究

为研究城市高密度街区大气颗粒物浓度分布特征,2019年秋季对上海市某高密度街区道路大气颗粒物浓度、空气温度、相对湿度、地理位置、车辆与道路图像视频信息进行了同步移动在线监测,并结合街区内固定站数据和后向轨迹模拟结果,总结了影响街区大气颗粒物浓度变化的主要因素。结果表明:城市大气颗粒物背景拟合值处于较低水平时,街区内的大气颗粒物浓度变化和影响因素易被识别;机动车污染源对大气颗粒物浓度贡献大,其中大型机动车的影响明显;户外施工和道路清扫会引起大气颗粒物浓度上升,其中PM₁₀上升更明显;交通密度大的十字路口大气颗粒物浓度通常较高;城市高架的盖状结构会阻碍大气颗粒物在垂直方向上的扩散,引起局部大气颗粒物浓度上升;街区内高大浓密的乔木对近地面的大气颗粒物屏蔽效果不理想,甚至有助于颗粒物累积;早晚高峰时段大气颗粒物浓度较非高峰时段高。

Field measurement study on the distribution characteristics of atmospheric particulate matter mass concentration in a high-density urban block

In order to study the distribution characteristics of atmospheric particulate matter concentration in high-density urban blocks,mobile synchronous online monitoring was conduct on the atmospheric particulate matter concentration,air temperature,relative humidity,geographic location,vehicle and road image video information of a high-density urban block in Shanghai in the autumn of 2019.The main factors affecting the changes in the concentration of atmospheric particulate matter in the neighborhood were identified based on the analysis of mobile monitoring data,air quality fixed site monitoring data and backward trajectory simulation results.The results showed that when the background fitting concentration of atmospheric particulate matter in the city was at a low level,the changes in the concentration of atmospheric particulate matter in the urban block and the influencing factors could be easily identified.Motor vehicle pollution sources made a great contribution to the concentration of atmospheric particulate matter,among which large-scale motor vehicles had a significant impact.Outdoor construction and road cleaning caused the atmospheric particulate matter concentration to rise,and the increase of PM₁₀ was more significant.The concentration of atmospheric particulate matter was usually higher at intersections with high traffic density.The urban elevated cover structure could hinder the vertical diffusion of atmospheric particulate matter,causing local atmospheric particulate matter concentration to rise.The tall and dense trees in the block had an unsatisfactory shielding effect on atmospheric particulate matter near the ground,and even contributed to the accumulation of particulate matter.The concentration of atmospheric particulate matter in the morning and evening peak periods was higher than in non-peak period.