Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China.
Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China; Fudan-Tyndall Center, Fudan University, Shanghai 200433, China.
J Environ Sci (China). 2014 Dec 1;26(12):2412-22. doi: 10.1016/j.jes.2014.03.002. Epub 2014 Oct 20.
Physical and chemical properties of ambient aerosols at the single particle level were studied in Shanghai from December 22 to 28, 2009. A Cavity-Ring-Down Aerosol Extinction Spectrometer (CRD-AES) and a nephelometer were deployed to measure aerosol light extinction and scattering properties, respectively. An Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) was used to detect single particle sizes and chemical composition. Seven particle types were detected. Air parcels arrived at the sampling site from the vicinity of Shanghai until mid-day of December 25, when they started to originate from North China. The aerosol extinction, scattering, and absorption coefficients all dropped sharply when this cold, clean air arrived. Aerosol particles changed from a highly aged type before this meteorological shift to a relatively fresh type afterwards. The aerosol optical properties were dependent on the wind direction. Aerosols with high extinction coefficient and scattering Ångström exponent (SAE) were observed when the wind blew from the west and northwest, indicating that they were predominantly fine particles. Nitrate and ammonium correlated most strongly with the change in aerosol optical properties. In the elemental carbon/organic carbon (ECOC) particle type, the diurnal trends of single scattering albedo (SSA) and elemental carbon (EC) signal intensity had a negative correlation. We also found a negative correlation (r=-0.87) between high mass-OC particle number fraction and the SSA in a relatively clean period, suggesting that particulate aromatic components might play an important role in light absorption in urban areas.
2009 年 12 月 22 日至 28 日，在上海对大气气溶胶单颗粒的物理和化学特性进行了研究。采用腔衰荡气溶胶消光光谱仪（CRD-AES）和浊度仪分别测量了气溶胶的光消光和散射特性。气溶胶飞行时间质谱仪（ATOFMS）用于检测单颗粒粒径和化学成分。共检测到 7 种颗粒类型。气团在 12 月 25 日中午前一直从上海附近到达采样点，随后开始从华北地区起源。当寒冷、清洁的空气到达时，气溶胶的消光、散射和吸收系数都急剧下降。气溶胶颗粒在这种气象转变之前从高度老化的类型转变为相对新鲜的类型。气溶胶光学性质取决于风向。当风从西方和西北方吹来时，会观测到高消光系数和散射 Ångström 指数（SAE）的气溶胶，表明它们主要是细颗粒。硝酸盐和铵盐与气溶胶光学性质的变化相关性最强。在元素碳/有机碳（ECOC）颗粒类型中，单次散射反照率（SSA）和元素碳（EC）信号强度的日变化趋势呈负相关。在相对清洁的时期，高质量有机碳颗粒数分数与 SSA 之间也存在负相关（r=-0.87），表明颗粒状芳香族成分可能在城市地区的光吸收中起重要作用。
