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有机气溶胶(OA)是大气细粒子中的重要组分,其化学组成和来源的识别对有效控制颗粒物污染水平具有重要意义.利用高分辨率气溶胶飞行质谱对北京2010年冬季亚微米气溶胶(PM1)中OA质量浓度和粒径分布进行了高时间分辨率(5min)的在线测定,以了解其化学特征及来源.结果表明,北京冬季OA的平均浓度为20.9±25.3ug/m3,最小值与最大值分别为1.9和284.6ug/m3.OA的H/C,O/C,N/C的摩尔比分别为1.70,0.17和0.005,相应的OM/OC(有机物和有机碳的质量比)为1.37.OA的粒径分布范围较宽,在积聚模态450nm附近有明显的峰值,而对超细粒子(Dva<100nm)的贡献主要来自燃烧源的一次排放.北京冬季的OA主要分为3类:烃类有机气溶胶(HOA)、烹饪类有机气溶胶(COA)和氧化性有机气溶胶(OOA),分别占OA的26.9%,49.7%和23.4%.HOA和COA分别来自燃烧源和烹饪源排放的一次有机气溶胶(POA),而OOA则对应着“老化”的二次有机气溶胶(SOA).
Organic aerosol (OA) is an important component of atmospheric fine particles, and its chemical composition and source identification is of great significance to effectively control the level of particulate pollution.Using high-resolution aerosol mass spectrometry (MS-MS) on the 2010 Beijing sub-micron aerosol (PM1) was used to determine the chemical characteristics and sources of OA in the air.The results showed that the average concentration of OA in winter was 20.9 ± 25.3ug / m3, the minimum The values and maxima were 1.9 and 284.6 ug / m 3, respectively. The molar ratios of H / C, O / C and N / C for OA were 1.70, 0.17 and 0.005 respectively. The corresponding OM / OC (mass ratio of organic to organic carbon ) Was 1.37, showing a wide range of particle size distribution, with obvious peaks around 450 nm in the accumulation mode, while the contribution to the ultrafine particles (Dva <100 nm) mainly came from the primary emission of the combustion source. (HOA), cooking organic aerosol (COA) and oxidative organic aerosol (OAA) accounted for 26.9%, 49.7% and 23.4% of OA, respectively.HOA and COA were from combustion Source and culinary source emits an organic aerosol (POA), while OOA corresponds to the “aging” of the secondary organic aerosol (SOA).