长沙市城区典型交通路口PM_(10)和PM_(2.5)污染特征研究

利用车载环境空气质量监测系统对长沙市城区典型交通路口的近地面空气质量进行了实时监测。结果表明,在监测时段(14∶00~20∶00)内,该监测点环境空气中PM10的小时质量浓度范围在0.097~0.222mg/m3之间,平均值0.163mg/m3;PM2.5的小时质量浓度范围在0.050~0.158mg/m3之间,平均值0.103mg/m3。PM2.5/PM10比值在48.1%~76.6%之间,平均值62.4%。PM10与PM2.5质量浓度在星期一相对较低,星期二有所升高,星期三至周末总体上保持基本稳定。在监测时段PM10与PM2.5小时质量浓度呈现先降后升的变化规律,即14∶00~15∶00,PM10与PM2.5质量浓度相对较高,16∶00左右降至最低,从17∶00开始逐渐升高,20∶00达到峰值。PM10和PM2.5的质量浓度变化与车流量和车速密切相关,温度、相对湿度和风速等气象因素对PM10和PM2.5质量浓度的变化影响也较显著。

Pollution Characters of PM10 and PM2.5 at Typical Traffic Crossing in Changsha City

The ambient air quality near surface at typical traffic intersections in Changsha was monitored using vehicle automatic monitoring system. Results showed that the hourly mass concentration of PM10 in ambient air at the monitored site ranged from 0. 097 to 0. 222 mg/m3 with the average value of 0. 163mg/m3 , and PM：.5 ranged from 0. 050 to 0. 158 mg/m3 with the average value of 0. 103mg/m3. PM2.5PM10 ratio ranged from 48.1% to 76. 6% with the average value of 62. 4%. Within the studied week, the mass concentration of PM10 and PM2.5 at the sampling site was relatively lower on Monday, then gradually increased from Tuesday, and stabled from Wednesday to weekend. Furthermore, during the monitoring period, the hourly mass concentrations hour of PM10 or PM2.5 showed the trend of decreasing first and then increase, relatively higher between 14：00 and 15：00, reaching the minimum value at about 16： 00, gradually increasing from 17：00 and reaching the maximum value at 20： 00. Further more, results indicated that the change of PM10 and PM2. 5 mass concentration were closely related to the traffic flow and speed. The ambient temperature, relative humidity and wind speed also had a significant impact on the variation of hourly mass concentration of PM10 and PM2.5.