西安市汽车尾气污染物与气象条件特征分析  

Analysis of Vehicle Exhaust Pollutants and Meteorological Conditions in Xi’an

作　　者：唐智亿 徐军昶 张雅斌 罗慧[3] 杨晓春 Tang Zhiyi;Xu Junchang;Zhang Yabin;Luo Hui;Yang Xiaochun(Department of Engineering Mechanics of Xi’an Jiaotong University,Xi’an 710049,China;Xi’an Meteorological Office,Xi’an 710016,China;Shaanxi Meteorological Bureau,Xi’an 710015,China)

机构地区：[1]西安交通大学工程力学系,西安710049 [2]西安市气象局,西安710016 [3]陕西省气象局,西安710015

出　　处：《气象与环境科学》2020年第2期70-78,共9页Meteorological and Environmental Sciences

基　　金：国家自然科学基金国际合作项目(41861144021);陕西重点产业创新链(群)项目(2020ZDLSF06-02);中国气象局软科学研究重点项目(2020ZDIANXM07);陕西省关中地区大气污染防治技术研究与示范(群)项目(2018ZDCXL-SF-02-06)。

摘　　要：基于西安城区与郊区两个环境路边站和区域气象站20162018年观测的逐小时气象、环保和交通监测数据,对西安尾气污染物、机动车流量和气象要素条件进行统计分析。结果表明:1)2016年以来,西安市冬季空气质量指数和主要污染物浓度整体呈逐年下降趋势,治污减霾成效明显。主要尾气污染物浓度月际变化趋势相同,冬季11月到次年1月的浓度均明显高于其他月份的,夏季6月到8月的浓度较低,冬季的约为夏季的2~4倍。西安冬季汽车尾气污染物中,氮氧化物(NOx)、碳氧化物(CO)、碳氢化物(HC)日变化特征相似,但细颗粒物(PM2.5)空间差异大。2)NOx和CO与汽车尾气排放关系密切,每日上午时段二者浓度随车流量增大而增大,车流量整体偏大40%的城区比郊区污染物偏多20%~30%。尾气污染物浓度分布与风频、风速等密切相关:西安城市道路风速较低,风向与汽车尾气污染物的扩散方向基本一致,较高污染浓度通常都出现在主导风向的下风向。城市建筑和道路规划建设中,要保留足够的“城市通风廊道”。3)西安尾气污染物浓度不存在明显的“周末效应”,城区站NOx浓度无明显起伏变化,郊区站道路环境中的NOx浓度受柴油车通行量影响较大,说明重型车可能对污染的影响更大。4)降水对污染物稀释沉降效果明显,对NOx作用不明显。前期超过60%以上的相对湿度是降水开始前出现颗粒物小时最大增幅超过200μg/m^3的有利条件,高湿环境是重污染天气过程颗粒物暴发式增长的有利气象条件,因此静风或小风大气环境下,通过水雾“高射炮式”播撒方式增加低层湿度并非是沉降稀释颗粒物的有效方法。Based on hourly meteorological data,environmental protection and traffic monitoring data respectively from two roadside environmental stations and regional automatic weather stations in urban and suburban areas of Xi’an from 2016 to 2018,the exhaust pollutants,motorized vehicle flow and meteorological elements are statistically analyzed.The results show that:1)the winter air quality index and major pollutant concentrations in Xi’an have been declining year by year since 2016,and the effectiveness of pollution control are obvious.The monthly variation trend of main exhaust pollutant concentration keeps the same.In winter from November to next January,the exhaust pollutant concentration is significantly higher than in other months,about 24 times higher than in summer.In summer(JuneAugust),the value of exhaust pollutant concentration is the lowest.Among the automobile exhaust pollutants in Xi’an,the daily variation characteristics of nitrogen oxides(NOx),carbon oxides(CO)and hydrocarbons(HC)are similar in winter,but the fine particles(PM2.5)have large spatial differences.2)NOx and CO are closely related to vehicle exhaust emissions,and the concentrations of NOx and CO increase with the vehicle flow every morning.The urban areas with the traffic volume more than 40%have 20%30%more pollutants than the suburban areas.The concentration distribution of exhaust pollutants is closely related to wind frequency and wind speed.On the roads of urban Xi’an,wind speed is relatively low,and the wind direction is basically consistent with the diffusion direction of automobile exhaust pollutants.The higher pollution concentration usually appears in the downwind direction of the dominant wind direction.So,it is necessary to preserve adequate urban ventilating corridors in the construction of urban buildings and roads.3)There is no obvious“weekend effect”of exhaust pollutant concentrations in Xi’an.No obvious fluctuation of NOx concentration is observed at urban stations.The NOx concentration at suburban stations by roa

关 键 词：汽车尾气 PM2.5 NOx 气象要素 扩散条件 

分 类 号：X513[环境科学与工程—环境工程] X734.2