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Zhang Z, He HD, Yang JM, Wang HW, Xue Y, Peng ZR. Spatiotemporal evolution of NO 2 diffusion in Beijing in response to COVID-19 lockdown using complex network. CHEMOSPHERE 2022; 293:133631. [PMID: 35041819 PMCID: PMC8760926 DOI: 10.1016/j.chemosphere.2022.133631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 01/10/2022] [Accepted: 01/12/2022] [Indexed: 06/14/2023]
Abstract
The COVID-19 pandemic and the corresponding lockdown measures have been confirmed to reduce the air pollution in major megacities worldwide. Especially at some monitoring hotspots, NO2 has been verified to show a significant decrease. However, the diffusion pattern of these hotspots in responding to COVID-19 is not clearly understood at present stage. Hence, we selected Beijing, a typical megacity with the strictest lockdown measures during COVID-19 period, as the studied city and attempted to discover the NO2 diffusion process through complex network method. The improved metrics derived from the topological structure of the network were adopted to describe the performance of diffusion. Primarily, we found evidences that COVID-19 had significant effects on the spatial diffusion distribution due to combined effect of changed human activities and meteorological conditions. Besides, to further quantify the impacts of disturbance caused by different lockdown measures, we discussed the evolutionary diffusion patterns from lockdown period to recovery period. The results displayed that the difference between normal operation and pandemic operation firstly increased at the cutoff of lockdown measures but then declined after the implement of recovery measures. The source areas had greater vulnerability and lower resilience than receptors areas. Furthermore, based on the conclusion that the diffusion pattern changed during different periods, we explored the key stations on the path of diffusion process to further gain information. These findings could provide references for comprehending spatiotemporal pattern on city scale, which might be help for high-resolution air pollution mapping and prediction.
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Affiliation(s)
- Zhe Zhang
- Center for Intelligent Transportation Systems and Unmanned Aerial Systems Applications, State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean & Civil Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Minhang District, Shanghai, 200240, China
| | - Hong-Di He
- Center for Intelligent Transportation Systems and Unmanned Aerial Systems Applications, State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean & Civil Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Minhang District, Shanghai, 200240, China.
| | - Jin-Ming Yang
- Center for Intelligent Transportation Systems and Unmanned Aerial Systems Applications, State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean & Civil Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Minhang District, Shanghai, 200240, China
| | - Hong-Wei Wang
- Center for Intelligent Transportation Systems and Unmanned Aerial Systems Applications, State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean & Civil Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Minhang District, Shanghai, 200240, China
| | - Yu Xue
- Institute of Physical Science and Technology, Guangxi University, Nanning, 53004, China
| | - Zhong-Ren Peng
- International Center for Adaptation Planning and Design, College of Design, Construction and Planning, University of Florida, Gainesville, FL, 32611-5706, USA
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Fellini S, Salizzoni P, Ridolfi L. Vulnerability of cities to toxic airborne releases is written in their topology. Sci Rep 2021; 11:23029. [PMID: 34845266 PMCID: PMC8630004 DOI: 10.1038/s41598-021-02403-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 11/09/2021] [Indexed: 11/09/2022] Open
Abstract
The incidental or malicious release of toxic gases in the atmosphere is one of the most critical scenarios for cities. The impact of these releases varies with the ventilation potential of the urban environment. To disentangle this crucial aspect, vulnerability to airborne releases is here traced back to essential properties of the urban fabric. To this aim, pollutant dispersion is disassembled in its fundamental bricks and the main drivers of the process are captured. The analysis is based on four cities with emblematic architectures: Paris, Firenze, Lyon and New York. Results show that vulnerability is driven by the topology of the city and by its interaction with the approaching wind. In this sense, fragility to toxic releases is written in the layout of the urban fabric and results from its historical evolution. This study paves the way to the assessment of air pollution-related issues from a morphological point of view.
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Affiliation(s)
- Sofia Fellini
- Laboratoire de Mécanique des Fluides et d'Acoustique, UMR CNRS 5509, Université de Lyon, École Centrale de Lyon, INSA Lyon, Université Claude Bernard Lyon I, 69134, Écully, France. .,Department of Environmental, Land and Infrastructure Engineering, Politecnico di Torino, 10129, Turin, Italy.
| | - Pietro Salizzoni
- grid.7849.20000 0001 2150 7757Laboratoire de Mécanique des Fluides et d’Acoustique, UMR CNRS 5509, Université de Lyon, École Centrale de Lyon, INSA Lyon, Université Claude Bernard Lyon I, 69134 Écully, France
| | - Luca Ridolfi
- grid.4800.c0000 0004 1937 0343Department of Environmental, Land and Infrastructure Engineering, Politecnico di Torino, 10129 Turin, Italy
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