京津冀地区城市空气颗粒物中多环芳烃的污染特征及来源

在2013年4个季节,同步采集了京津冀地区3个典型城市(北京市、天津市和石家庄市)空气PM2.5和PM10样品,采用乙腈超声提取-超高压液相色谱法分析了16种多环芳烃(PAHs).结果表明,京津冀地区城市空气PM2.5和PM10中总PAHs的浓度分别为6.3~251.4ng/m3和7.0~285.5ng/m3,呈现冬季>春季>秋季>夏季的季节变化特点和石家庄>北京>天津的空间分布特点.PAHs环数分布以4、5和6环为主,比例分别为25.0%~45.1%、31.7%~40.1%、15.1%~28.2%,2和3环比例之和小于10.3%;与非采暖季相比,采暖季中4环PAHs比例显著增加,5和6环PAHs比例明显下降.PAHs比值法显示,京津冀地区城市空气颗粒物PAHs的来源呈现明显季节性变化特点,燃煤和机动车排放是2个重要的PAHs排放源,在采暖季燃煤来源的比例较大,在非采暖季以机动车排放的来源为主.

Pollution characteristics and source identification of polycyclic aromatic hydrocarbons in airborne particulates of Beijing-Tianjin-Hebei Region,China

PM2.5 and PM10 were synchronously collected in the ambient air of Beijing, Tianjin and Shijiazhuang City in four seasons of 2013. The samples were first pretreated by ultrasonic extraction with acetonitrile, and then sixteen polycyclic aromatic hydrocarbons (PAHs) were analyzed by ultrahigh-pressure liquid chromatography. The variation of total PAHs concentration was 6.3~251.4ng/m3 and 7.0~285.5ng/m3 in PM2.5 and PM10 of Beijing-Tianjin-Hebei Region, respectively. It was found that the degree of seasonal variation of PAHs pollution was as following: winter>spring>autumn>summer, and the degree of spatial variation of PAHs pollution was as following: Shijiazhuang>Beijing>Tianjin. PAHs were mainly composed of 4, 5and 6-ring PAHs with the percentage of 25.0%~45.1%, 31.7%~40.1% and 15.1%~28.2%, while the sum percentage of 2and 3-ring PAHs was below 10.3%. Compared with non-heating season, the percentage of 4-ring PAHs increased in heating season, while it was obviously deceased for 5and 6-ring PAHs. PAH diagnostic ratios showed that PAHs sources varied with season, indicating that coal burning and vehicular emission were the two main emission sources of PAHs sources. Coal burning played an important role in heating season, and vehicular emission was the main emission source in non-heating season.