Single particle diversity and mixing state of carbonaceous aerosols in Guangzhou, China

Chunlei Cheng; Chak K Chan; Berto Paul Lee; Masao Gen; Mei Li; Suxia Yang; Feng Hao; Cheng Wu; Peng Cheng; Dui Wu; Lei Li; Zhengxu Huang; Wei Gao; Zhong Fu; Zhen Zhou

doi:10.1016/j.scitotenv.2020.142182

Single particle diversity and mixing state of carbonaceous aerosols in Guangzhou, China

Sci Total Environ. 2021 Feb 1:754:142182. doi: 10.1016/j.scitotenv.2020.142182. Epub 2020 Sep 4.

Authors

Chunlei Cheng¹, Chak K Chan², Berto Paul Lee³, Masao Gen⁴, Mei Li⁵, Suxia Yang⁶, Feng Hao⁷, Cheng Wu¹, Peng Cheng¹, Dui Wu¹, Lei Li¹, Zhengxu Huang¹, Wei Gao¹, Zhong Fu⁸, Zhen Zhou¹

Affiliations

¹ Institute of Mass Spectrometry and Atmospheric Environment, Guangdong Provincial Engineering Research Center for on-Line Source Apportionment System of Air Pollution, Jinan University, Guangzhou 510632, China; Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou 510632, China.
² School of Energy and Environment, City University of Hong Kong, Hong Kong, China. Electronic address: Chak.K.Chan@cityu.edu.hk.
³ School of Energy and Environment, City University of Hong Kong, Hong Kong, China.
⁴ Faculty of Frontier Engineering, Institute of Science and Engineering, Kanazawa University, Kanazawa 920-1192, Japan.
⁵ Institute of Mass Spectrometry and Atmospheric Environment, Guangdong Provincial Engineering Research Center for on-Line Source Apportionment System of Air Pollution, Jinan University, Guangzhou 510632, China; Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou 510632, China. Electronic address: limei2007@163.com.
⁶ Institute for Environment and Climate Research, Jinan University, Guangzhou 510632, China.
⁷ Environmental Monitoring Center of Inner Mongolia Autonomous Region, Hohhot 010011, China.
⁸ School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China.

PMID: 33254891
DOI: 10.1016/j.scitotenv.2020.142182

Abstract

Many field studies have investigated the formation mechanisms of organic aerosol (OA) based on bulk analysis, yet the source and formation process of individual organic particles may be quite different due to the diversity of chemical composition and mixing state in single particles. Here we present the observation results of chemical composition and mixing state of carbonaceous single particles at an urban site in Guangzhou. The carbonaceous particles accounted for 74.6% of the total detected single particles, and were grouped into four types including elemental carbon-aged (EC-aged), elemental and organic carbon (ECOC), organic carbon-rich (OC-rich) and secondary ions-rich (SEC) particles. The formation of EC-aged particles was closely associated with the absorption of organics onto fresh EC particles from primary sources, and the further enrichment of organics in EC-aged particles resulted in the production of ECOC particles. In the daytime OC-rich and SEC particles were mainly produced from the photochemical reactions, while in the nighttime their sharp increases were found along with the enrichment of nitrate and organic nitrogen fragments, suggesting the heterogeneous formation of nitrate and organic nitrogen in OC-rich and SEC particles. The production rates of carbonaceous particles were also investigated in an episodic event, and the EC-aged particles showed the highest production rate compared to the other carbonaceous particles both in the daytime and nighttime, suggesting a significant role of EC in the formation and aging process of carbonaceous particles. The results from this work have revealed different formation processes and production rates of carbonaceous particles due to their diversity in mixing state, providing further insights into the formation mechanisms of OA in field studies.

Keywords: Carbonaceous particles; Elemental carbon; Mixing state; Photochemical production; Single particles.