ZHU Ying^1a,b，LUO Jingqi^1a,b，LIU Huanwu²，SHEN Zhenxing³，LI Yexin⁴，LIU Yanzheng⁵，ZHOU Yong^1a,b

(1 a. School of Environment and Municipal Engineering; b. Shaanxi Key Laboratory of Environmental Engineering，Xi’an University of Architecture and Technology, Xi’an 710055, China; 2. Xi’an Environmental Monitoring Station,Xi’an 710061, China; 3. School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China;4. Ankang Environmental Engineering Design Limited Company, Ankang 725000, China;5. Xi’an University of Architecture and Technology of South Australia An De College, Xi’an 710311, China)

Abstract：In order to study the chemical characteristics of PM_2.5 during the COVID-19 pandemic,this study used online observation instruments to continuously observe chemical components of PM_2.5 in the northern urban area of Xi'an from 01 January to 31 March,2020. The results show that NO₃^-,SO₄^2-,NH₄⁺are the most important components of water-soluble ions,and the watersoluble ions are neutrality skew alkaline. Compared with pre-COVID-Lockdown stage(PC),the mass concentrationsof PM_2.5,CO,SO_2,NO_X,elemental carbon,NO₃^-,SO₄^2-are reduced by 10. 56%,21. 89%,13. 40%,65. 98%,9. 54%,29. 69%and 10. 04% respectively in COVID-Lockdown stage(DC),and the mass concentration ratio of NO₃^-and SO₄^2-is reduced by 29. 41%. The mass concentration ratio of organic carbon to elemental carbon reveals that the carbon component in the measurement period mainly come from coal and vehicle exhaust sources. The estimation of the secondary organic carbon found that the secondary organic carbon is the main source of gradual resumption of work(GW) and almost complete resumption of work(AW) stages,and primary organic carbon is the main source of PC and DC stages. Positive matrix factorization source analysis results show that coal combustion(accounting for 64. 00%) is the main source of organic carbon in PC,DC and GW stages,and the contribution value of construction and dust in AW stage is the largest(61. 34%). Due to the control measures,the motor vehicle source in DC stage decreases by 3. 20%,and the industrial process source decreases by 1. 82%.

Keywords：COVD-19 pandemic; PM_2.5; water-soluble ions; carbonaceous; source

中图分类号：X513

文献标志码：A

文章编号：1008-5548(2021)06-0037-13

DOI:10.13732/j.issn.1008-5548.2021.06.005

收稿日期： 2021-04-11，修回日期：2021-07-09，在线出版时间：2021-10-18 14:25。

基金项目：国家重点研发计划项目，编号：2016YFC0207800；国家自然科学基金，编号：51608422；陕西省大学生创新创业训练计划项目，编号：S201910703084；陕西省一流专业建设项目，编号：YLZY0303C02。

第一作者简介：祝颖(1984—)，女(蒙古族)，博士，副教授，硕士生导师，研究方向为大气污染控制。E-mail：zhuyingxauat@163.com。