气候变化领域集成服务门户(CCPortal): Aerosol number concentrations and new particle formation events over a polluted megacity during the COVID-19 lockdown

CCPortal

DOI	10.1016/j.atmosenv.2021.118526
	Aerosol number concentrations and new particle formation events over a polluted megacity during the COVID-19 lockdown
	Yadav S.K.; Kompalli S.K.; Gurjar B.R.; Mishra R.K.
发表日期	2021
ISSN	1352-2310
卷号	259
英文摘要	The present study investigates the particle number concentrations and size distributions in the ultrafine and fine-sized regimes over a polluted megacity, New Delhi (28.75° N, 77.12° E), India. The experiments were conducted during the periods (April–May 2020) of strict social and travel restrictions (lockdown) imposed by the Government of India aiming to contain the spread of Coronavirus Disease 19 (COVID-19) pandemic. The different phases of the COVID-19 lockdown witnessed restrictions of varying magnitudes with the significant cessation of anthropogenic sources, viz., industrial, road, railways, and air traffic emissions. Using this unique opportunity, the impact of varying urban emissions on particle number size distributions and new particle formation events were examined. The mean total number concentrations were in the range of ~ (2–3.5) x 104 cm−3 and depicted a gradual increase (~26%) with progressive unlock of the anthropogenic activities. At the same time, accumulation particle concentrations were doubled. However, ultrafine particles (UFP) (diameter < 100 nm) dominated (50–88%) the total number concentrations during most of the days and several new particle formation (NPF) events resulting in elevated (2–5 fold) UFP concentrations were observed. Subsequently, the particles grew to larger sizes with rates ~3.31–8.37 nm h−1. The NPF events occurred during the daytime, and during the events, a clear enhancement in the concentrations of [H2SO4] proxy (2–3.5 × 107 molecules cm−3; 2–3 orders higher than the non-event values) suggesting the role of strong gas-phase photochemistry. Also, some of the NPF events were associated with increased odd oxygen concentrations [Ox = O3+NO2], indicating the regional nature of the precursors and participation of VOC precursors in nucleation/growth. Interestingly, different classes of NPF events were seen during the strictest lockdown period, whereas more frequent and well-defined NPF events were witnessed when anthropogenic activities were opened up with conditional relaxations. These events demonstrated the competition between source strengths of precursor vapors from anthropogenic activities and primary particles acting as condensation sink restricting NPF. This study highlighted that urban pollution mitigation policies need to consider ultrafine particles emanating from the secondary aerosol formation process from traffic emissions. © 2021 Elsevier Ltd
关键词	COVID-19 Lockdown Megacity New particle formation Trace gases Ultrafine particles Urban air pollution
语种	英语
scopus关键词	Air pollution; Industrial emissions; Anthropogenic activity; Coronavirus disease 19; Coronaviruses; Lockdown; Megacities; New particle formation; Trace gas; Traffic emissions; Ultrafine particle; Urban air pollution; Size distribution; carbon monoxide; nitrogen dioxide; nitrogen oxide; ozone; sulfur dioxide; sulfuric acid; volatile organic compound; accumulation; aerosol formation; air traffic; anthropogenic source; concentration (composition); condensation; COVID-19; human activity; megacity; mitigation; nucleation; oxygen; particle size; photochemistry; size distribution; traffic emission; aerosol; air pollutant; air pollution; Article; circadian rhythm; concentration (parameter); coronavirus disease 2019; environmental policy; gas; industry; lockdown; meteorology; oxygen concentration; pandemic; particle size; photochemistry; railway; traffic pollution; travel restriction; ultrafine particulate matter; urban area; vapor; Delhi; India; New Delhi; Coronavirus
来源期刊	ATMOSPHERIC ENVIRONMENT
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/248363
作者单位	Department of Environmental Engineering, Delhi Technological University, New Delhi, India; Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram, India; Department of Civil Engineering, Indian Institute of Technology, Roorkee, India
推荐引用方式 GB/T 7714	Yadav S.K.,Kompalli S.K.,Gurjar B.R.,et al. Aerosol number concentrations and new particle formation events over a polluted megacity during the COVID-19 lockdown[J],2021,259.
APA	Yadav S.K.,Kompalli S.K.,Gurjar B.R.,&Mishra R.K..(2021).Aerosol number concentrations and new particle formation events over a polluted megacity during the COVID-19 lockdown.ATMOSPHERIC ENVIRONMENT,259.
MLA	Yadav S.K.,et al."Aerosol number concentrations and new particle formation events over a polluted megacity during the COVID-19 lockdown".ATMOSPHERIC ENVIRONMENT 259(2021).