Characteristics and sources of PM2.5 with focus on two severe pollution events in a coastal city of Qingdao, China
Characteristics and sources of PM2.5 with focus on two severe pollution events in a coastal city of Qingdao, China
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PM2.5特征及来源——以中国沿海城市青岛两起严重污染事件为中心
DOI：
10.1016/j.chemosphere.2020.125861
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发表时间：
2020-05-01
期刊：
影响因子：
8.8
通讯作者：
Yao, Xiaohong
中科院分区：
文献类型：
--
作者：
Gao, Yang;Shan, Huayao;Yao, Xiaohong
本研究首先分析了沿海城市青岛2014-2018年的季节平均PM2.5浓度，其中冬季尤其是2015年的浓度最高。为了阐明PM2.5的来源和控制因素，采用了三维天气研究与预报模型（WRF）、社区多尺度空气质量模型（CMAQ）和柔性粒子模型（FLEXPART）。2015年12月至2016年1月，模拟结果表明，青岛本地排放对PM2.5质量浓度的平均贡献为25%，来自北部和西部的运输几乎占一半。在两个偶然污染期（2015年12月29日至31日；2016年1月15日至17日），青岛的本地排放对PM2.5质量浓度的贡献分别为18%和24%，这表明其他地区的贡献占主导地位，如山东青岛以外的地区和京津冀（BTH）。结果表明：根据FLEXPART的推断，PM2.5的源区域和贡献随气流路径的变化而发生显著变化，而近地面PM2.5的增强主要是由向下的垂直平流和气溶胶化学反应的增强引起的，同时伴随着边界层高度的下降。该研究还揭示了运输贡献对空气包裹轨迹的敏感。因此，我们建议基于运输轨迹的有效排放控制在短期内改善青岛空气质量。(C) 2020 Elsevier Ltd.版权所有。
In this study, the seasonal mean PM2.5 concentration in Qingdao, a coastal city, during 2014-2018 was first analyzed and the winter, in particular of 2015, showed the highest concentration. To elucidate the sources and control factors of PM2.5, three dimensional model Weather Research and Forecasting (WRF), Community Multiscale Air Quality model (CMAQ), as well as Flexible Particle model (FLEXPART), were used. During December 2015 and January 2016, modeling results showed that the mean contribution to PM2.5 mass concentrations from local emissions in Qingdao was 25%, and the transport from north and west accounted for almost half. Over the two episodically polluted periods (29-31 December 2015; 15-17 January 2016), the local emissions in Qingdao surprisingly contributed to only 18% and 24% to PM2.5 mass concentrations, respectively, indicating the dominant contributions from other regions, such as areas outside Qingdao in Shandong and Beijing-Tianjin-Hebei (BTH). The results show the sources region and contribution may vary remarkably along with the change in the pathways of the air parcel, inferred by the FLEXPART, while the near-surface PM2.5 enhancement is largely caused by downward vertical advection and enhanced aerosol chemistry reactions, accompanied by simultaneous drop in the boundary layer height. This study also reveals that the transport contribution is sensitive to the air parcel trajectories. We, therefore, recommend the efficient emission control based on transport trajectories in short-term air quality improvement in Qingdao. (C) 2020 Elsevier Ltd. All rights reserved.