北京市大气PM_(10)和PM_(2.5)中有机物的时空变化

Spatial-Temporal Variations of Extractable Organic Matter in Atmospheric PM_(10) and PM_(2.5) in Beijing

2005年四季在北京市不同功能区9个采样点采集大气PM10和PM2.5样品,并对其中有机物污染水平、分布特征及不同功能区PM10和PM2.5中有机物的相关性进行了探讨.结果表明,市区PM10和PM2.5中有机物年均值分别为41.39μg/m3和34.84μg/m3,是对照区十三陵的1.44倍和1.26倍;冬季有机物污染最严重,分别为春季的1.15、1.82倍,秋季的2.06、2.26倍,夏季的4.53、6.26倍.不同季节PM2.5与PM10中EOM的比值超过0.60,并呈现一定季节差异.各功能区有机污染表现出工业区(商业区)>居民区(交通区、对照区)的变化趋势,且不同功能区PM2.5中EOM对PM10中EOM的影响程度各异.有机组分的年均值有非烃>沥青质>芳烃>饱和烃的变化规律,而污染源的季节性排放是造成有机物组分季节变化的主要原因.

PM10 and PM2.5 samples were collected in parallel in different function zones of Beijing during four seasons of 2005. The pollution level, distribution characteristics of the extractable organic matter （ EOM ） and relationship between EOM （ PM10 ） and EOM （ PM2.5 ） were illustrated. The results show that： the annual mean concentrations of organic compound in PM10 and PM2.5 are 41.39 μg/m^3 and 34.84 μg/m^3 , being 1.44 times and 1.26 times higher than Ming Tombs site. The concentrations of EOM in winter are 67.04μg/m^3 （PM10） and 64.64 μg/m^3 （PM25）, which are 1.15 and 1.82 times, 2.06 and 2.26 times, 4.53 and 6.26 times higher than that in spring, autumn, summer, respectively. Ratios of EOM in PM25 to that in PMIo in different seasons exceed 0.60. In different function zones the concentrations of EOM present industrial and commercial zones 〉 living, traffic and contrast zones. The influence of EOM（PM2.5 ） on EOM（PM10 ） in different districts are various. The order of annual concentrations of organic compositions is non-hydrocarbons 〉 asphahenes 〉 aromatics 〉 saturated hydrocarbon. The seasonal emissions of pollution sources play an important role in seasonality of compositions of EOM.