成都地铁运营区间隧道颗粒物成分及浓度分析

Analysis of the Composition and Concentration of Particulate Matters in Chengdu Operational Metro Running Tunnels

地铁运营过程中在区间隧道产生的污染物会通过风亭排放到大气中,为了解地铁区间隧道颗粒物浓度分布、成分及形貌特征等,依托四川省成都市4个典型的地铁站,采用激光粉尘检测仪对4个站点的活塞风亭处颗粒物浓度进行现场测试,采集颗粒物样品进行扫描电镜和能谱分析确定颗粒物来源,并运用皮尔逊系数进行区间隧道与周围环境相关性分析。研究结果表明:地铁经过区间隧道产生的颗粒物形态多为球状、棱角状等,所含元素主要为Fe、Al、Ba、Zn等金属元素,其主要来源为地铁运行过程中轨道与车轮、制动器之间以及地铁车辆的受电弓与供电的接触网之间界面处的机械损耗和摩擦;PM_(10)浓度远高于PM_(1)及PM_(2.5)浓度,且各粒径颗粒物浓度无明显关系;地铁区间隧道颗粒物浓度受季节影响较大,冬季产生的PM_(2.5)、PM_(10)浓度值高于其他季节,且PM_(10)排放浓度超标;4个站点各PM指标的皮尔逊相关系数r均大于0.8,风亭处污染物浓度与周边环境大气污染程度高度线性相关。

During metro train operation,the pollutants generated in the running tunnels will be emitted into the at⁃mosphere through ventilation pavilions.To understand the concentration distribution,composition,and morphologi⁃cal characteristics of particulate matters in metro running tunnels,a study was conducted based on four typical met⁃ro stations in Chengdu,Sichuan Province.The laser dust detector was used for on-site testing of particulate matter concentrations at the piston wind pavilions of the four stations.Particulate matter samples were collected for scan⁃ning electron microscopy(SEM)and energy dispersive spectroscopy(EDS)analysis to determine their sources.Pear⁃son correlation coefficients were used to analyze the relationship between the running tunnel and ambient environ⁃mental conditions.The results show that the particulate matters generated by the train passing through metro run⁃ning tunnels are mostly spherical or angular and so on,with elemental contents mainly consisting of metals such as Fe,Al,Ba,and Zn.These particles primarily originate from mechanical wear and friction at the interfaces between tracks and wheels,brakes,and the contact points between the pantograph and catenary during metro train operation.The concentration of PM_(10)is much higher than that of PM_(1) and PM_(2.5),with no significant correlation between the con⁃centrations of particulate matters with different particle sizes.The particulate matter concentration in metro running tunnels is significantly influenced by the season,with PM_(2.5)and PM_(10)levels higher in winter than in other seasons,and PM_(10)emissions exceeding the standard limits.The Pearson correlation coefficients r for PM indicators at the four stations are all greater than 0.8,indicating a high linear correlation between the pollutant concentrations at the ventilation pavilions and the air pollution levels in surrounding environment.