Fossil-driven secondary inorganic PM2.5 enhancement in the North China Plain: Evidence from carbon and nitrogen isotopes

Saehee Lim, Xiaoyang Yang, Meehye Lee, Gang Li, Yuanguan Gao, Xiaona Shang, Kai Zhang, Claudia I. Czimczik, Xiaomei Xu, Min Suk Bae, Kwang Joo Moon, Kwonho Jeon

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

Measuring isotopic ratios in aerosol particles is a powerful tool for identifying major sources, particularly in separating fossil from non-fossil sources and investigating aerosol formation processes. We measured the radiocarbon, stable carbon, and stable nitrogen isotopic composition of PM2.5 in Beijing (BJ) and Changdao (CD) in the North China Plain (NCP) from May to mid-June 2016. The mean PM2.5 concentrations were 48.6 ± 28.2 μg m−3 and 71.2 ± 29.0 μg m−3 in BJ and CD, respectively, with a high contribution (∼66%) from secondary inorganic aerosol (SIA; NO3, NH4+, and SO42−). The mean δ13C of total carbon (TC) and δ15N of total nitrogen (TN) values differed significantly between the two sites (p-value of <0.001): −25.1 ± 0.3‰ in BJ and −24.5 ± 0.4‰ in CD and 10.6 ± 1.8‰ in BJ and 5.0 ± 3.1‰ in CD, respectively. In BJ, the average δ15N (NH4+) and δ15N (NO3) values were 12.9 ± 2.3‰ and 5.2 ± 3.5‰, respectively. The ionic molar ratios and isotopic ratios suggest that NO3 in BJ was formed through the phase-equilibrium reaction of NH4NO3 under sufficient NH3 (g) conditions, promoted by fossil-derived NH3 (g) transported with southerly winds. In BJ, fossil fuel sources comprised 52 ± 7% of TC and 45 ± 28% of NH4+ on average, estimated from radiocarbon (14C) analysis and the δ15N and isotope mixing model, respectively. These multiple-isotopic composition results emphasize that PM2.5 enhancement is derived from fossil sources, in which vehicle emissions are a key contributor. The impact of the coal source was sporadically noticeable. Under regional influences, the fossil fuel-driven SIA led to the PM2.5 enhancements. Our findings demonstrate that the multiple-isotope approach is highly advantageous to elucidate the key sources and limiting factors of secondary inorganic PM2.5 aerosols.

Original languageEnglish
Article number115163
JournalEnvironmental Pollution
Volume266
DOIs
Publication statusPublished - 2020 Nov

Bibliographical note

Funding Information:
This research was supported by the National Strategic Project-Fine Particle of the National Research Foundation of Korea ( NRF ), funded by the Ministry of Science and ICT ( MSIT ), Ministry of Environment (ME), and Ministry of Health and Welfare ( MOHW ) ( 2017M3D8A1092015 ).The China-Korea joint research on air quality was sponsored by the National Institute of Environment Research ( NIER ) through the Ministry of Environment (MOE) of the Republic of Korea ( NIER-2017-03-02-011 ). Funding to S. Lim was provided by the National Research Foundation of Korea ( NRF ) from the Ministry of Science and ICT ( 2016R1D1A1B03934532 and 2018R1D1A1B07050849 ). The Chinese scientists would like to thank the Natural Science Foundation of China for their support (grant number 41105090 ) and the National Key R&D Program of China (grant number 2016YFC0206001 ).

Funding Information:
This research was supported by the National Strategic Project-Fine Particle of the National Research Foundation of Korea (NRF), funded by the Ministry of Science and ICT (MSIT), Ministry of Environment (ME), and Ministry of Health and Welfare (MOHW) (2017M3D8A1092015).The China-Korea joint research on air quality was sponsored by the National Institute of Environment Research (NIER) through the Ministry of Environment (MOE) of the Republic of Korea (NIER-2017-03-02-011). Funding to S. Lim was provided by the National Research Foundation of Korea (NRF) from the Ministry of Science and ICT (2016R1D1A1B03934532 and 2018R1D1A1B07050849). The Chinese scientists would like to thank the Natural Science Foundation of China for their support (grant number 41105090) and the National Key R&D Program of China (grant number 2016YFC0206001).

Publisher Copyright:
© 2020 Elsevier Ltd

Keywords

  • Fossil fuel
  • PM
  • Radiocarbon
  • Secondary inorganic aerosol
  • Stable isotope

ASJC Scopus subject areas

  • Toxicology
  • Pollution
  • Health, Toxicology and Mutagenesis

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