Vertically-resolved sources and secondary formation of fine particles: A high resolution tethered mega-balloon study over Shanghai

Yijie Shi; Dongfang Wang; Juntao Huo; Yusen Duan; Yanfen Lin; Kan Huang; Qingyan Fu; Guangli Xiu

doi:10.1016/j.scitotenv.2021.149681

Vertically-resolved sources and secondary formation of fine particles: A high resolution tethered mega-balloon study over Shanghai

Sci Total Environ. 2022 Jan 1:802:149681. doi: 10.1016/j.scitotenv.2021.149681. Epub 2021 Aug 20.

Authors

Yijie Shi¹, Dongfang Wang², Juntao Huo³, Yusen Duan³, Yanfen Lin³, Kan Huang⁴, Qingyan Fu⁵, Guangli Xiu⁶

Affiliations

¹ Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China.
² Shanghai Environmental Monitoring Center, Shanghai 200235, China; Shanghai Jianke Environmental Technology Co., Ltd, Shanghai 200032, China.
³ Shanghai Environmental Monitoring Center, Shanghai 200235, China; State Ecology and Environment Scientific Observation and Research Station for the Yangtze River Delta at Dianshan Lake, Shanghai 201713, China.
⁴ Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China; State Ecology and Environment Scientific Observation and Research Station for the Yangtze River Delta at Dianshan Lake, Shanghai 201713, China; Institute of Eco-Chongming (IEC), Shanghai 202162, China; IRDR ICoE on Risk Interconnectivity and Governance on Weather/Climate Extremes Impact and Public Health, Fudan University, Shanghai 200433, China. Electronic address: huangkan@fudan.edu.cn.
⁵ Shanghai Environmental Monitoring Center, Shanghai 200235, China; State Ecology and Environment Scientific Observation and Research Station for the Yangtze River Delta at Dianshan Lake, Shanghai 201713, China. Electronic address: qingyanf@sheemc.cn.
⁶ East China University of Science and Technology, Shanghai 200237, China. Electronic address: xiugl@ecust.edu.cn.

PMID: 34454153
DOI: 10.1016/j.scitotenv.2021.149681

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 PM_2.5, 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 PM_2.5 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.

Keywords: BC source apportionment; Long-range transport; Tethered mega-balloon; Vertical profiles of air pollutants; Vertical secondary aerosol formation.

MeSH terms

Aerosols / analysis
Air Pollutants* / analysis
Air Pollution* / analysis
China
Environmental Monitoring
Particulate Matter / analysis
Seasons

Substances

Aerosols
Air Pollutants
Particulate Matter