北京市区春季交通源大气颗粒物污染水平及其影响因素

The pollution level and influencing factors of atmospheric particulates from traffic in Beijing city during spring.

文中以PM2．5和PM10为研究对象，于2005年3月13日至19日前后6d的时间内，在成府路东口、前门2个地区设立采样点，研究分析了北京市春季交通源大气颗粒物的污染水平及其影响因素。研究表明：（1）PM2．5和PM10的质量浓度存在明显的日变化规律，在工作日所测得的PM2．5和PM10的质量浓度值要高于在周末所测得的质量浓度值；（2）PM2.5和PM10的质量浓度存在明显的时变化规律，在7：00～9：00，19：00-21：00和23：00之后，PM2．5和PM10的质量浓度分别达到三个峰值；（3）PM2．5和PM10的质量浓度随着温度的变化而存在明显的变化规律，PM2.5和PM10质量浓度的最大值与低温（0～5℃）有关，而PM2.5和PM10质量浓度的最小值在高温（11～15℃）时被观察到；（4）PM2.5和PM10的质量浓度的最大值与高湿度值（36％～46％）有关，而PM2.5和PM10质量浓度的最小值在低湿度值（11％～25％）时被观察到；（5）通过对成府路东口、前门采样点颗粒物浓度与风级比较，发现二者呈明显的反相关关系，由此可见，风力大小对特定区域的颗粒物浓度起决定性作用；（6）与国外一些城市的PM10的污染水平相比，在北京成府路东口、前门所测得的PM10的质量浓度都要比国外一些城市高，由此可见，汽车尾气仍是北京市区大气颗粒物的主要来源之一。

We have conducted a research on PM2.5 and PM10 collected at the east crossing of Chengfu Road and Qianmen, Beijing, from March 13, 2005 to March 19, 2005, in order to analyze the pollution level of atmospheric particulate matter （PM） from traffic in Beijing and the variations of PM concentrations with weather, time and location. The research results are as follows. The concentrations of PM2.5 and PM10 vary daily owing to the increase a number of motor vehicles on working days; the PM concentrations on working days are higher than those on weekends. The concentrations of PM2.5 and PM10 vary hourly as well, and three peaks are present at different times in a day; the first peak occurs between 7 am and 9 am, coinciding with the rush hours for people going to work; the second peak occurs between 7 pm and 9 pm corresponding to the time of people returning home. The third peak occurs after 11 pm owing to the passage of heavy trucks through the city after 10 o＇clock at night. The concentrations of PM2.5 and PM10 vary with temperature as well; the highest value relates with the low temperature（0-5 ℃ ）, while the lowest value is detected at higher temperature （11-15 ℃ ）. The concentrations of PM2.5 and PM10 vary with humidity; the maximum value relates to high moisture（36-46%）, whereas the minimum value is detected at low moisture（11%-25%）. It is found that PM2.5 and PM10 concentrations are negatively correlated with wind speed. Compared to the pollution level of PM2.5 and PM10 in foreign countries, the PM concentrations detected in Beijing city are much higher than those in foreign cities. It is concluded that vehicle exhaust emissions are still one of the main sources of PM in Beijing city. New measures against vehicle exhaust emissions should be adopted as soon as possible to improve the air quality in Beijing city.