Xu Jian, Wang Qiongzhen, Deng Congrui, McNeill V Faye, Fankhauser Alison, Wang Fengwen, Zheng Xianjue, Shen Jiandong, Huang Kan, Zhuang Guoshun
Center for Atmospheric Chemistry Study, Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China; Institute of Atmospheric Sciences, Fudan University, Shanghai 200433, China.
Center for Atmospheric Chemistry Study, Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China; Environmental Science Research & Design Institute of Zhejiang Province, Hangzhou, Zhejiang 310007, China.
Environ Pollut. 2018 Feb;233:1177-1187. doi: 10.1016/j.envpol.2017.10.003. Epub 2017 Oct 14.
There is growing evidence suggesting that organic aerosols play an important role in the evolution of severe haze episodes. However, long-term investigations of the different characteristics of carbonaceous aerosols during haze and non-haze days are insufficient. In this work, hourly measurements of organic carbon (OC) and elemental carbon (EC) in PM were conducted in Shanghai, a megacity in Eastern China, over the course of a year from July 2013 to June 2014. Both OC and EC exhibited a bimodal diel pattern and were highly dependent on the wind speed and direction. The concentration-weighted trajectory (CWT) analysis illustrated that primary OC (POC) and EC were largely associated with regional and long-range transport. Secondary OC (SOC) formation was the strongest during the harvest season owing to significant biomass burning emissions from the adjacent Yangtze River Delta and farther agricultural regions. Compared to OC (6.7 μg m) and EC (2.0 μg m) in the non-haze days, higher levels of both OC (15.6 μg m) and EC (7.7 μg m) were observed in the haze days as expected, but with lower OC/EC ratios in the haze days (2.4) than in non-haze days (4.6). The proportion of POC and EC in PM remained relatively constant as a function of PM mass loadings, while that of SOC significantly decreased on the highly polluted days. It is concluded that the haze pollution in urban Shanghai was influenced more by the primary emissions (POC and EC), while the role of SOC in triggering haze was limited.
越来越多的证据表明，有机气溶胶在严重雾霾事件的演变中起着重要作用。然而，对雾霾天和非雾霾天期间碳质气溶胶不同特征的长期调查并不充分。在这项研究中，于2013年7月至2014年6月期间，在中国东部的一个特大城市上海，对细颗粒物中的有机碳（OC）和元素碳（EC）进行了逐小时测量。OC和EC均呈现双峰日变化模式，并且高度依赖于风速和风向。浓度加权轨迹（CWT）分析表明，一次有机碳（POC）和EC在很大程度上与区域和长距离传输有关。由于邻近的长江三角洲地区及更远的农业地区存在大量生物质燃烧排放，二次有机碳（SOC）的形成在收获季节最为强烈。与非雾霾天的OC（6.7μg/m）和EC（2.0μg/m）相比，正如预期的那样，雾霾天的OC（15.6μg/m）和EC（7.7μg/m）水平均更高，但雾霾天的OC/EC比值（2.4）低于非雾霾天（4.6）。随着细颗粒物质量负荷的变化，POC和EC在细颗粒物中的比例保持相对恒定，而在高污染日，SOC的比例显著下降。研究得出结论，上海市区的雾霾污染受一次排放（POC和EC）的影响更大，而SOC在引发雾霾中的作用有限。
