Reapportioning the sources of secondary components of PM2.5: A combined application of positive matrix factorization and isotopic evidence

Zeyu Sun; Zheng Zong; Chongguo Tian; Jun Li; Rong Sun; Wenwen Ma; Tingting Li; Gan Zhang

doi:10.1016/j.scitotenv.2020.142925

Reapportioning the sources of secondary components of PM_2.5: A combined application of positive matrix factorization and isotopic evidence

Sci Total Environ. 2021 Apr 10:764:142925. doi: 10.1016/j.scitotenv.2020.142925. Epub 2020 Oct 11.

Authors

Zeyu Sun¹, Zheng Zong², Chongguo Tian³, Jun Li⁴, Rong Sun⁵, Wenwen Ma¹, Tingting Li⁵, Gan Zhang⁶

Affiliations

¹ CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai 264003, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China; University of Chinese Academy of Sciences, Beijing 100049, China.
² CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai 264003, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China.
³ CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai 264003, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China. Electronic address: cgtian@yic.ac.cn.
⁴ State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China. Electronic address: junli@gig.ac.cn.
⁵ State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.
⁶ State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.

PMID: 33268246
DOI: 10.1016/j.scitotenv.2020.142925

Abstract

Secondary particles account for a considerable proportion of fine particles (PM_2.5) and reasonable reapportioning them to primary sources is critical for designing effective strategies for air quality improvement. This study developed a method which can reapportion secondary sources of PM_2.5 solved by positive matrix factorization (PMF) to primary sources based on the isotopic signals of nitrate, ammonium and sulfate. Actual PM_2.5 data in Beijing were used as a case study to assess the feasibility and capacity of this method. In the case, 20 chemical components were used to apportion PM_2.5 sources and source contributions of nitrate were applied to reapportion secondary source to primary sources. The model performance was also estimated by radiocarbon measurement (¹⁴C) of organic (OC) and elemental (EC) carbons of eight samples. The PMF apportioned seven sources: the secondary source (36.1%), vehicle exhausts (18.7%), industrial sources (13.6%), biomass burning (11.4%), coal combustion (8.10%), construction dust (7.93%) and fuel oil combustion (4.24%). After the reapportionment of the secondary source, vehicle exhausts (28.7%) contributed the most to PM_2.5, followed by biomass burning (25.1%) and industrial sources (18.9%). Fossil oil combustion and coal combustion increased to 8.00% and 11.4%, respectively, and construction dust contributed the least. The average gap between contributions of identified sources to OC and EC and the ¹⁴C measurements decreased 2.5 ± 1.2% after the reapportionment than 13.2 ± 10.8%, indicating the good performance of the developed method.

Keywords: Isotope; PMF model; Secondary particulate matter; Source apportionment.