Significant reduction in atmospheric organic and elemental carbon in PM2.5 in 2+26 cities in northern China

Xu Dao; Dongsheng Ji; Xian Zhang; Jun He; Jiaqi Sun; Jianlin Hu; Yu Liu; Lili Wang; Xiaojuan Xu; Guigang Tang; Yuesi Wang

doi:10.1016/j.envres.2022.113055

Significant reduction in atmospheric organic and elemental carbon in PM_2.5 in 2+26 cities in northern China

Environ Res. 2022 Aug:211:113055. doi: 10.1016/j.envres.2022.113055. Epub 2022 Mar 4.

Authors

Xu Dao¹, Dongsheng Ji², Xian Zhang¹, Jun He³, Jiaqi Sun¹, Jianlin Hu⁴, Yu Liu⁵, Lili Wang⁵, Xiaojuan Xu⁶, Guigang Tang¹, Yuesi Wang⁵

Affiliations

¹ China National Environmental Monitoring Station, Beijing, 100012, China.
² State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Atmosphere Sub-Center of Chinese Ecosystem Research Network, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100191, China. Electronic address: jds@mail.iap.ac.cn.
³ Natural Resources and Environment Research Group, International Doctoral Innovation Centre, Department of Chemical and Environmental Engineering, University of Nottingham Ningbo China, Ningbo, 315100, China; Nottingham Ningbo China Beacons of Excellence Research and Innovation Institute, Ningbo, 315101, China.
⁴ Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science & Technology, Nanjing, 210044, China.
⁵ State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Atmosphere Sub-Center of Chinese Ecosystem Research Network, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100191, China.
⁶ Atmosphere Sub-Center of Chinese Ecosystem Research Network, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100191, China.

PMID: 35257685
DOI: 10.1016/j.envres.2022.113055

Abstract

To better understand the change characteristics and reduction in organic carbon (OC) and elemental carbon (EC) in particulate matter (PM) with a diameter of ≤2.5 μm (PM_2.5) driven by the most stringent clean air policies and pandemic-related lockdown measures in China, a comprehensive field campaign was performed to measure the carbonaceous components in PM_2.5 on an hourly basis via harmonized analytical methods in the Beijing-Tianjin-Hebei and its surrounding region (including 2 + 26 cities) from January 1 to December 31, 2020. The results indicated that the annual average concentrations of OC and EC reached as low as 6.6 ± 5.7 and 1.8 ± 1.9 μg/m³, respectively, lower than those obtained in previous studies, which could be attributed to the effectiveness of the Clean Air Action Plan and the impact of the COVID-19-related lockdown measures implemented in China. Marked seasonal and diurnal variations in OC and EC were observed in the 2 + 26 cities. Significant correlations (p < 0.001) between OC and EC were found. The annual average secondary OC levels level ranged from 1.8-5.4 μg/m³, accounting for 37.7-73.0% of the OC concentration in the 2 + 26 cities estimated with the minimum R squared method. Based on Interagency Monitoring of Protected Visual Environments (IMPROVE) algorithms, the light extinction contribution of carbonaceous PM to the total amount reached 21.1% and 26.0% on average, suggesting that carbonaceous PM played a less important role in visibility impairment than did the other chemical components in PM_2.5. This study is expected to provide an important real-time dataset and in-depth analysis of the significant reduction in OC and EC in PM_2.5 driven by both the Clean Air Action Plan and COVID-19-related lockdown policies over the past few years, which could represent an insightful comparative case study for other developing countries/regions facing similar carbonaceous PM pollution.

Keywords: Beijing-Tianjin-Hebei and its surrounding region of China; Elemental carbon; Light extinction; Organic carbon; PM(2.5); Temporal variation.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aerosols / analysis
Air Pollutants* / analysis
COVID-19* / prevention & control
Carbon / analysis
China
Cities
Communicable Disease Control
Environmental Monitoring
Humans
Particle Size
Particulate Matter / analysis
Seasons

Substances

Aerosols
Air Pollutants
Particulate Matter
Carbon