Effect of restricted emissions during COVID-19 on atmospheric aerosol chemistry in a Greater Cairo suburb: Characterization and enhancement of secondary inorganic aerosol production

Atmospheric Pollution Research

article

Salwa K. Hassan¹  Mansour A. Alghamdi²  Mamdouh I. Khoder¹ 

[1] Air Pollution Research Department, Environmental and Climate Change Research Institute, National Research Centre;Department of Environmental Sciences, Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University

关键词: COVID-19 partial lockdown;    Emission reduction;    PM 2.5;    Secondary inorganic production;    Aerosol acidity;   

DOI  :  10.1016/j.apr.2022.101587

学科分类：农业科学（综合）

来源: Dokuz Eylul Universitesi * Department of Environmental Engineering

【 摘 要 】

To prevent the rapid spreading of the COVID-19 pandemic, the Egyptian government had imposed partial lockdown restrictions which led emissions reduction. This served as ideal conditions for a natural experiment, for study the effect of partial lockdown on the atmospheric aerosol chemistry and the enhanced secondary inorganic aerosol production in a semi-desert climate area like Egypt. To achieve this objective, SO 2 , NO 2 , and PM 2.5 and their chemical compositions were measured during the pre-COVID, COVID partial lockdown, and post-COVID periods in 2020 in a suburb of Greater Cairo, Egypt. Our results show that the SO 2 , NO 2 , PM 2.5 and anthropogenic elements concentrations follow the pattern pre-COVID > post-COVID > COVID partial lockdown. SO 2 and NO 2 reductions were high compared with their secondary products during the COVID partial lockdown compared with pre-COVID. Although, PM 2.5 , anthropogenic elements, NO 2 , SO 2 , SO 4 2− , NO 3 − , and NH 4 + decreased by 39%, 38–55%, 38%, 32.9%. 9%, 14%, and 4.3%, respectively, during the COVID partial lockdown compared with pre-COVID, with the secondary inorganic ions (SO 4 2− , NO 3 − , and NH 4 + ) being the dominant components in PM 2.5 during the COVID partial lockdown. Moreover, the enhancement of NO 3 − and SO 4 2− formation during the COVID partial lockdown was high compared with pre-COVID. SO 4 2− and NO 3 − formation enhancements were significantly positive correlated with PM 2.5 concentration. Chemical forms of SO 4 2− and NO 3 − were identified in PM 2.5 based on their NH 4 + /SO 4 2− molar ratio and correlation between NH 4 + and both NO 3 − and SO 4 2− . The particles during the COVID partial lockdown were more acidic than those in pre-COVID.

【 授权许可】

CC BY