Preprints
https://doi.org/10.5194/acp-2020-1294
https://doi.org/10.5194/acp-2020-1294

  15 Jan 2021

15 Jan 2021

Review status: this preprint is currently under review for the journal ACP.

Measurement Report: Online Measurement of Gas-Phase Nitrated Phenols Utilizing CI-LToF-MS: Primary Sources and Secondary Formation

Kai Song1,2, Song Guo1,2, Haichao Wang3, Ying Yu1, Hui Wang1, Rongzhi Tang1, Shiyong Xia4, Yuanzheng Gong1, Zichao Wan1, Daqi Lv1, Rui Tan1, Wenfei Zhu1, Ruizhe Shen1, Xin Li1, Xuena Yu1, Shiyi Chen1, Liming Zeng1, and Xiaofeng Huang4 Kai Song et al.
  • 1State Key Joint Laboratory of Environmental Simulation and Pollution Control, International Joint Laboratory for Regional Pollution Control, Ministry of Education (IJRC), College of Environmental Sciences and Engineering, Beijing, 100871, China
  • 2Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science & Technology, Nanjing 210044, China
  • 3School of Atmospheric Sciences, Sun Yat-sen University, Zhuhai, 519082, China
  • 4Key Laboratory for Urban Habitat Environmental Science and Technology, School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen, 518055, China

Abstract. To investigate the composition, variation, and sources of nitrated phenols (NPs) in the winter of Beijing, gas-phase NPs were measured by using a chemical ionization long time-of-flight mass spectrometer (CI-LToF-MS). A box model was applied to simulate the secondary formation process of NPs. In addition, the primary sources of NPs were resolved by non-negative matrix factorization (NMF) model. Our results showed that secondary formation contributed 38 %, 9 %, 5 %, 17 % and almost 100 % of the ambient nitrophenol (NP), methyl-nitrophenol (MNP), dinitrophenol (DNP), methyl-dinitrophenol (MDNP or DNOC), and dimethyl-nitrophenol (DMNP). Phenol-OH reaction was the predominant loss pathway (46.7  %) during the heavy pollution episode, which produced phenoxy radical (C6H5O). The phenoxy radical consequently reacted with NO2, and produced nitrophenol. By estimating the primarily emitted phenol from the ratio of phenol/CO from freshly emitted vehicle exhaust, this study proposed that oxidation of primary phenol contributes much more nitrophenol (37 %) than that from benzene oxidation (< 1 %) in the winter of Beijing. The latter pathway was widely used in models and might lead to great uncertainties. The source apportionment results by NMF indicated the importance of combustion sources (> 50 %) to the gas-phase NPs. The industry source contributed 30 % and 9 % to DNP and MDNP, respectively, which was non-negligible. The concentration weighted trajectory (CWT) analysis demonstrated that regional transport from provinces that surround the Yellow and Bohai Seas contributed more primary NPs to Beijing. Both primary sources and secondary formation in either local or regional scale should be considered when making NPs control policies.

Kai Song et al.

Status: open (until 12 Mar 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2020-1294', Anonymous Referee #1, 12 Feb 2021 reply
  • RC2: 'Comment on acp-2020-1294', Anonymous Referee #2, 25 Feb 2021 reply

Kai Song et al.

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Short summary
Nitrated phenols (NPs) are crucial components of brown carbon. To comprehend the constitutes and sources of NPs in winter of Beijing, their concentration was measured by a CI-LToF-MS. The secondary formation process was simulated by a box mode. NPs were mainly influenced by primary emissions and regional transport. Primary emitted phenol rather than benzene oxidation was crucial in the heavy pollution episode in Beijing, which provides more insight into NPs pollution control strategies.
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