北京市秋季大气颗粒物的污染特征研究

大气颗粒物是造成城市空气污染的重要原因之一,并已经成为我国北京等大中城市空气污染中的首要污染。为了分析北京市大气细颗粒物的污染水平及其影响因素,以大气中的PM10和PM2.5为研究对象,于2005年秋季在北京市设立了9个采样点进行采样监测,通过对所采集到的PM10和PM2.5质量浓度的对比来分析大气颗粒物的空间分布和时间变化特征,并建立起PM10和PM2.5质量浓度与风力、温度、湿度等气象条件的对应关系来分析各种气象因素对大气细颗粒物污染水平的影响。结果表明:北京市不同区域的PM10和PM2.5的质量浓度差异较大,同时,值得注意的是通过对同一地点同一采样时间大气颗粒物质量浓度的对比发现PM2.5质量浓度的空间分布并不完全同于PM10,这主要是与采样点所处的环境中不同污染源影响的强弱有关;气象条件稳定时,PM10和PM2.5质量浓度的日变化表现出一定的规律性,这种时间变化的特征主要取决于所在环境中排放的污染物变化情况;气象条件是影响PM10和PM2.5污染程度的重要因素,在一定的范围内,颗粒物质量浓度随着温度的上升而下降,随着相对湿度的升高而增大,随着风力的增强而减小。

Research on the pollution situation of atmospheric particulates during Autumn in Beijing city

The pollution caused by atmospheric particulates is one of the important factors affecting the urban air quality, which has been the chief air pollutant in many middle-large-sized cities like Beijing in our country. In order to analyze the pollution level and the influence factors of atmospheric particulates in Beijing city, the authors sampled PM10 and PM2.5 at nine areas in Beijing city during autumn in 2005. The spatial distribution and temporal variation features of atmospheric particulates were analyzed through the comparison of the mass concentrations of PM10 and PM2.5 sampled at different areas during different periods, and the influence of meteorological factors was analyzed based on the relationship of the mass concentrations of PM10 and PM2.5 with weather conditions such as temperature, wind speed and relative humidity. The results are concluded as follows. Because of the influence of pollution sources at each sampling area, the mass concentrations of PM10 and PM2.5 in different regions of Beijing city are different from the others, and it also shows that not all the spatial distribution regulations of the mass concentrations of PM2.5 are the same as PM10 on the whole at the same sampling area and the same time. As weather conditions keep stable, the hourly variation of PM10 and PM2.5 concentrations presents regularly, the temporal variation mostly depends on the variety of contaminations released to the environment. Weather conditions are the important influence factors of PM10 and PM2.5 pollution level, the mass concentrations of atmospheric particulates decrease with the rise of the temperature and wind speed, while they increase with the increase of relative humidity.