Abstract
Numerous studies have focused on air pollution near the surface in China, yet we still have little knowledge on the characteristics, formation mechanisms, and sources of air pollutants aloft. Based on a tethered mega-balloon platform, the vertical profiles of PM2.5, black carbon (BC), SO2, O3, and meteorological parameters were measured within the lower troposphere of 1000 m over Shanghai. One clean and slightly polluted period (CP) and one heavily polluted period (HP) with continuously measured profiles were compared. The potential source areas of PM2.5 at different altitudes during HP were determined based on the time-lag spatial correlation analysis, indicating the surrounding regions were the main sources of low-altitude particles in Shanghai and farther regions of northern China significantly affected the upper atmosphere. By apportioning the sources of vertical BC profiles, fossil fuel combustion contributed >80% to BC below 600 m during HP, exhibiting a higher contribution than CP. An indicator (i.e. SA/SO2, SA represents secondary aerosols) was established to investigate the vertical evolution of secondary aerosol formation. During CP, relatively low SA/SO2 ratios were observed within the boundary layer due to the weak atmospheric processing. SA/SO2 profiles showed the opposite vertical trend of higher ratios below about 600 m while lower values at high altitudes during HP. Regional and long-range transport regulated the extents of secondary aerosol formation. Northeasterlies transported abundant aged aerosols from northern China while sea breezes suppressed the columnar secondary aerosol formation. This study provided insights into the vertical structures of typical air pollutants in a Chinese megacity and implied that high-resolution measurements of atmospheric vertical profiles were valuable for diagnosing sources and potential secondary formation of fine particles.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
