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. 2020 Dec 16;47(23):e2020GL090444.
doi: 10.1029/2020GL090444. Epub 2020 Nov 28.

Variation in Concentration and Sources of Black Carbon in a Megacity of China During the COVID-19 Pandemic

Liang Xu  1 , Jian Zhang  1 , Xin Sun  2 , Shengchen Xu  2 , Meng Shan  3 , Qi Yuan  1 , Lei Liu  1 , Zhenhong Du  1 , Dantong Liu  1 , Da Xu  2 , Congbo Song  4 , Bowen Liu  5 , Gongda Lu  4 , Zongbo Shi  4 , Weijun Li  1
Affiliations

Variation in Concentration and Sources of Black Carbon in a Megacity of China During the COVID-19 Pandemic

Liang Xu et al. Geophys Res Lett. .

Abstract

Black carbon (BC) not only warms the atmosphere but also affects human health. The nationwide lockdown due to the Coronavirus Disease 2019 (COVID-19) pandemic led to a major reduction in human activity during the past 30 years. Here, the concentration of BC in the urban, urban-industry, suburb, and rural areas of a megacity Hangzhou were monitored using a multiwavelength Aethalometer to estimate the impact of the COVID-19 lockdown on BC emissions. The citywide BC decreased by 44% from 2.30 to 1.29 μg/m3 following the COVID-19 lockdown period. The source apportionment based on the Aethalometer model shows that vehicle emission reduction responded to BC decline in the urban area and biomass burning in rural areas around the megacity had a regional contribution of BC. We highlight that the emission controls of vehicles in urban areas and biomass burning in rural areas should be more efficient in reducing BC in the megacity Hangzhou.

Keywords: COVID‐19 lockdown; black carbon; source.

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Conflict of interest statement

The authors declare no competing financial interests.

Figures

Figure 1
Figure 1
The location of observation sites and the population density of Hangzhou City.
Figure 2
Figure 2
(a) The hourly averaged vehicle number running on the roads showing the variation in traffic in downtown Hangzhou. Data source: Hangzhou Traffic Police Division. The figure was generated using Igor Probased computer programs developed by (Wu et al. (2018)). (b) The mean deweathered BC concentration in different areas during the five stages. The detailed BC concentration is presented in Table S3 in the supporting information.
Figure 3
Figure 3
Mean diurnal variations in BC (without deweathering) in the four areas on weekdays. (a) Urban, (b) Urban industry, (c) Suburban, and (d) Rural.
Figure 4
Figure 4
Average variation in the BC source apportionment from fossil fuel (gray area) and biomass burning (orange area) for the four areas on weekdays (deweathered data). (a) Urban, (b) Urban industry, (c) Suburban, and (d) Rural. The detailed data are presented in Table S4.
See this image and copyright information in PMC

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