Unexpected rise of ozone in urban and rural areas, and sulfur dioxide in rural areas during the coronavirus city lockdown in Hangzhou, China: implications for air quality

Autor: Pengfei Li, Xue Chen, Linhui Jiang, Jiali Li, Yibo Zhang, Mengying Li, Daniel Rosenfeld, Zhen Li, Weiping Liu, Eric Lichtfouse, Yan Xia, John H. Seinfeld, Shaocai Yu, Liqiang Wang
Přispěvatelé: Zhejiang University, California Institute of Technology (CALTECH), Agricultural University of Hebei, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), The Hebrew University of Jerusalem (HUJ), Department of Science and Technology of China2016YFC02027022018YFC02135062018YFC0213503National Research Program for Key Issues in Air Pollution Control in ChinaDQGG0107National Natural Science Foundation of China (NSFC)2157712641561144004Research Center for Air Pollution and Health in Zhejiang UniversityInitiation Fund for Introducing Talents of Hebei Agricultural University412201904Zhejiang 1000 Talent Plan
Rok vydání: 2020
Předmět:
Zdroj: Environmental Chemistry Letters
Environmental Chemistry Letters, 2020, 18 (5), pp.1713-1723. ⟨10.1007/s10311-020-01028-3⟩
Environmental Chemistry Letters, Springer Verlag, 2020, 18 (5), pp.1713-1723. ⟨10.1007/s10311-020-01028-3⟩
ISSN: 1610-3661
1610-3653
Popis: The outbreak of coronavirus named COVID-19, initially identified in Wuhan, China in December 2019, has spread rapidly at the global scale. Most countries have rapidly stopped almost all activities including industry, services and transportation of goods and people, thus decreasing air pollution in an unprecedented way, and providing a unique opportunity to study air pollutants. While satellite data have provided visual evidence for the global reduction in air pollution such as nitrogen dioxide (NO2) worldwide, precise and quantitative information is missing at the local scale. Here we studied changes in particulate matter (PM2.5, PM10), carbon monoxide (CO), NO2, sulfur dioxide (SO2) and ozone (O3) at 10 urban sites in Hangzhou, a city of 7.03 million inhabitants, and at 1 rural site, before city lockdown, January 1–23, during city lockdown, January 24-February 15, and during resumption, February 16–28, in 2020. Results show that city lockdown induced a sharp decrease in PM2.5, PM10, CO, and NO2 concentrations at both urban and rural sites. The NO2 decrease is explained by reduction in traffic emissions in the urban areas, and by lower regional transport in rural areas during lockdown, as expected. SO2 concentrations decreased from 6.3 to 5.3 μg m−3 in the city, but increased surprisingly from 4.7 to 5.8 μg m−3 at the rural site: this increase is attributed both to higher coal consumption for heating and emissions from traditional fireworks of the Spring Eve and Lantern Festivals during lockdown. Unexpectedly, O3 concentrations increased by 145% from 24.6 to 60.6 μg m−3 in the urban area, and from 42.0 to 62.9 μg m−3 in the rural area during the lockdown. This finding is explained by the weakening of chemical titration of O3 by NO due to reductions of NOx fresh emissions during the non-photochemical reaction period from 20:00 PM to 9:00 AM (local time). During the lockdown, compared to the same period in 2019, the daily average concentrations in the city decreased by 42.7% for PM2.5, 47.9% for PM10, 28.6% for SO2, 22.3% for CO and 58.4% for NO2, which is obviously explained by the absence of city activities. Overall, we observed not only the expected reduction in some atmospheric pollutants (PM, SO2, CO, NO2), but also unexpected increases in SO2 in the rural areas and of ozone (O3) in both urban and rural areas, the latter being paradoxically due to the reduction in nitrogen oxide levels. In other words, the city lockdown has improved air quality by reducing PM2.5, PM10, CO, and NO2, but has also decreased air quality by augmenting O3 and SO2. Electronic supplementary material The online version of this article (10.1007/s10311-020-01028-3) contains supplementary material, which is available to authorized users.
Databáze: OpenAIRE
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