Seasonal variations of mass absorption efficiency of elemental carbon in PM2.5 in urban Guangzhou of South China

Chenglei Pei; Yunfei Wu; Jun Tao; Leiming Zhang; Tao Zhang; Runqi Zhang; Sheng Li

doi:10.1016/j.jes.2022.04.019

Seasonal variations of mass absorption efficiency of elemental carbon in PM_2.5 in urban Guangzhou of South China

J Environ Sci (China). 2023 Nov:133:83-92. doi: 10.1016/j.jes.2022.04.019. Epub 2022 Apr 22.

Authors

Chenglei Pei¹, Yunfei Wu², Jun Tao³, Leiming Zhang⁴, Tao Zhang⁵, Runqi Zhang⁶, Sheng Li⁶

Affiliations

¹ State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China; Guangzhou Sub-branch of Guangdong Ecological and Environmental Monitoring Center, Guangzhou 518049, China.
² Key Laboratory of Middle Atmosphere and Global Environment Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China. Electronic address: wuyf@mail.iap.ac.cn.
³ Institute for Environmental and Climate Research, Jinan University, Guangzhou 510632, China. Electronic address: taojun@jnu.edu.cn.
⁴ Air Quality Research Division, Science and Technology Branch, Environment and Climate Change Canada, Toronto, Canada.
⁵ State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China; Guangdong Ecological and Environmental Monitoring Center, Guangzhou 510308, China.
⁶ State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.

PMID: 37451792
DOI: 10.1016/j.jes.2022.04.019

Abstract

This study investigates seasonal variations of mass absorption efficiency of elemental carbon (MAE_EC) and possible influencing factors in urban Guangzhou of South China. Mass concentrations of elemental carbon (EC) and organic carbon (OC) in PM_2.5 and aerosol absorption coefficient (b_ap) at multi-wavelengths were simultaneously measured in four seasons of 2018-2019 at hourly resolution by a semi-continuous carbon analyzer and an aethalometer. Seasonal average mass concentrations of EC were in the range of 1.36-1.70 µgC/m³ with a lower value in summer than in the other seasons, while those of OC were in the range of 4.70-6.49 µgC/m³ with the lowest value in summer and the highest in autumn. Vehicle exhaust from local traffic was identified to be the predominant source of carbonaceous aerosols. The average aerosol absorption Ångström exponents (AAE) were lower than 1.2 in four seasons, indicating EC and b_ap were closely related with vehicle exhaust. Seasonal MAE_EC at 550 nm was 11.0, 8.5, 10.4 and 11.3 m²/g in spring, summer, autumn, and winter, respectively. High MAE_EC was related with the high mass ratio of non-carbonaceous aerosols to EC and high ambient relative humidity.

Keywords: Absorption enhancement; Non-carbonaceous aerosols; Relative humidity; Vehicle exhaust.

MeSH terms

Aerosols / analysis
Air Pollutants* / analysis
Carbon / analysis
China
Environmental Monitoring
Particulate Matter* / analysis
Seasons
Vehicle Emissions

Substances

Particulate Matter
Air Pollutants
Vehicle Emissions
Carbon
Aerosols