Regional transport of anthropogenic pollution and dust aerosols in spring to Tianjin - A coastal megacity in China.
Simultaneous measurements of columnar aerosol microphysical and optical properties, as well as PM2.5chemical compositions, were made during two types of spring pollution episodes in Tianjin, a coastal megacity of China. The events were investigated using field observations, satellite data, model simulations, and meteorological fields. The lower Ångström Exponent and the higher aerosol optical depth on 29 March, compared with the earlier event on 26 March, implied a dominance of coarse mode particles - this was consistent with the differences in volume-size distributions. Based on the single scattering spectra, the dominant absorber (at blue wavelength) changed from black carbon during less polluted days to brown carbon on 26 March and dust on 29 March. The concentrations of major PM2.5species for these two episodes also differed, with the earlier event enriched in pollution-derived substances and the later with mineral dust elements. The formation mechanisms of these two pollution episodes were also examined. The 26 March episode was attributed to the accumulation of both local emissions and anthropogenic pollutants transported from the southwest of Tianjin under the control of high pressure system. While the high aerosol loading on 29 March was caused by the mixing of transported dust from northwest source region with local urban pollution. The mixing of transported anthropogenic pollutants and dust with local emissions demonstrated the complexity of springtime pollution in Tianjin. The synergy of multi-scale observations showed excellent potential for air pollution study.
Key Lab of Aerosol Chemistry & Physics, Chinese Academy of Sciences (KLACP), Chinese Academy of Sciences, Xi'an 710061, China; SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China.
Xiaoli
X
Su
State Environmental Protection Key Laboratory of Satellite Remote Sensing, Satellite Environment Center, Ministry of Environmental Protection of the People's Republic of China, Beijing 100094, China.
Qiao
Q
Wang
Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100101, China.
Zhengqiang
Z
Li
Istituto di Metodologie per l'Analisi Ambientale - CNR, Tito Scalo 85050, Italy.
Mariarosaria
M
Calvello
Scuola di Ingegneria-Università della Basilicata, Potenza 85100, Italy.
Francesco
F
Esposito
Istituto di Metodologie per l'Analisi Ambientale - CNR, Tito Scalo 85050, Italy.
Giulia
G
Pavese
Zhongshan Bureau of Meteorology, Zhongshan 528400, China.
Meijing
M
Lin
Key Lab of Aerosol Chemistry & Physics, Chinese Academy of Sciences (KLACP), Chinese Academy of Sciences, Xi'an 710061, China; SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China. Electronic address: cao@loess.llqg.ac.cn.
Junji
J
Cao
State Environmental Protection Key Laboratory of Satellite Remote Sensing, Satellite Environment Center, Ministry of Environmental Protection of the People's Republic of China, Beijing 100094, China.
Chunyan
C
Zhou
Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100101, China.
Donghui
D
Li
Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100101, China.
Hua
H
Xu
Dust transport; Formation mechanism; Multi-scale observations; Urban pollution