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污染控制技术及原理

Characterization and source identification of ambient organic carbon in PM_2.5 in urban and suburban sites of Beijing

摘要：2004年在定陵、北京大学、奥体中心、良乡、通州共5个采样点采集北京市PM_2.5样品,并对其中有机碳(OC)、元素碳(EC)和有机物组成进行了测定,分析了北京市城区和郊区细粒子中有机化合物的污染特征.共检出有机物188种,主要物种为正构烷烃、正构烷酸、霍烷、多环芳烃、脱氧单糖苷以及其它多种源的示踪物.各监测点有机物浓度均呈现1月浓度最高、10月其次,7月浓度最低,4月居中的特征.市区点(奥体、北大)和近郊点(良乡、通州)的污染物浓度远高于受人为活动影响较小的远郊定陵.以正构烷烃、霍烷、多环芳烃、左旋葡聚糖和EC为示踪物,利用化学质量平衡(CMB)受体模型对北京市PM_2.5中的OC进行了来源解析.结果表明,北京市细粒子OC的主要来源为柴油车排放(15.3%)、汽油车排放(20.5%)、燃煤排放(19.0%)、生物质燃烧(2.1%)和植物碎屑(1.1%).机动车和燃煤排放仍然是北京市细粒子OC的主要来源,而且有加重趋势.

Abstract：To determine the sources of particulate matter in Beijing, PM_2.5 samples were collected at various sites in 2004: Dingling, Peking University, Olympic Park, Tongzhou, and Liangxiang. Organic Carbon (OC), Elemental Carbon (EC), and organic components in the PM_2.5 samples were measured. Atotal of 188 organic compounds were identified, and the main species were n-alkanes, n-alkanoic acids, hopanes, PAHs, monosaccharide derivatives and some other organic molecular tracers. At all five sites, the concentration of organic compounds was the highest in January, followed by October, with the lowest value in July and a medium value in April. The concentration of pollutants in the urban sites (Peking University and Olympic Park) and the suburban sites (Tongzhou and Liangxiang) was much higher than that of the background site Dingling. A Chemical Mass Balance (CMB) model using n-alkanes, hopanes, PAHs, levoglucosan and ECas tracers was applied in this study to apportion source contributions to ambient OCin PM_2.5 in Beijing. The results showed that the main sources of OCin PM_2.5 in Beijing were diesel exhaust (15.3%), gasoline exhaust (20.5%), coal combustion (19.0%), biomass burning (2.1%) and vegetative detritus (1.1%). Vehicle exhaust and coal combustion were still the main sources of ambient OCin fine particles in Beijing.