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Rana A, Sarkar S. The role of nitroaromatic compounds (NACs) in constraining BrC absorption in the Indo-Gangetic Plain (IGP). THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 917:170523. [PMID: 38296066 DOI: 10.1016/j.scitotenv.2024.170523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 01/09/2024] [Accepted: 01/26/2024] [Indexed: 02/04/2024]
Abstract
We present here the first measurements of nitroaromatic compounds (NACs) including nitrophenols (NPs), nitrocatechols (NCs) and nitrosalicylic acids (NSAs) from the Indian subcontinent and their role in constraining brown carbon (BrC) absorption. NACs at a rural receptor site in the eastern Indo-Gangetic Plain (IGP) (annual average: 185 ± 94 ng m-3) was dominated by NSAs (135 ± 77 ng m-3), followed by NPs (29 ± 11 ng m-3) and NCs (17 ± 16 ng m-3), with notable enrichments during nighttime and during the biomass burning seasons. An equilibrium absorption partitioning model estimated that >90 % of NSAs and NCs were in the particle-phase, suggesting lower degradation rates via oxidation and photolysis potentially due to year-round high relative humidity. While the contribution of NACs to organic aerosol mass was only 0.42 ± 0.23 %, their contribution to BrC absorption in the 300-450 nm range was higher by an order of magnitude (8 ± 4 %), with NCs and NSAs contributing almost equally in the low-visible (400-450 nm) range as at 365 nm. Despite having mass concentrations lower than NPs by factors of ∼2, contribution of NCs to BrC absorption at λ ≥ 400 nm was comparable to that by NPs, indicating the importance of the absorption efficiency of chromophores. The receptor model positive matrix factorization (PMF) quantified three major NAC sources: fossil fuel combustion (49 ± 15 %; annual average), secondary formation (40 ± 12 %), and biomass burning (11 ± 9 %), with variable contributions on seasonal and day-night bases. In summary, the study uncovered the significant role of NACs in constraining BrC absorption in the IGP, which stresses the importance for molecular-level characterization of BrC chromophores.
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Affiliation(s)
- Archita Rana
- Department of Earth Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, 741246, Nadia, India
| | - Sayantan Sarkar
- School of Civil and Environmental Engineering, Indian Institute of Technology (IIT) Mandi, Kamand, Himachal Pradesh, 175005, India.
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Guo Z, Hu X, Sun W, Peng X, Fu Y, Liu K, Liu F, Meng H, Zhu Y, Zhang G, Wang X, Xue L, Wang J, Wang X, Peng P, Bi X. Mixing state and influence factors controlling diurnal variation of particulate nitrophenol compounds at a suburban area in northern China. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 344:123368. [PMID: 38246217 DOI: 10.1016/j.envpol.2024.123368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 12/28/2023] [Accepted: 01/14/2024] [Indexed: 01/23/2024]
Abstract
Nitrophenols have received extensive attention due to their strong light-absorbing ability in the near-ultraviolet-visible region, which could be influenced by the atmospheric processes of nitrophenols. However, our knowledge and understanding of the formation and evolution of nitrophenols are still in the nascent stages. In the present study, the mixing states of four mononitrophenol particles (i.e., nitrophenol, methynitrophenol, nitrocatechol, and methoxynitrophenol), and one nitropolycyclic aromatic hydrocarbon particles (i.e., nitronaphthol (NN)) were investigated using a single-particle aerosol mass spectrometer (SPAMS) in November 2019 in Qingdao, China. The results showed, for the first time, that mononitrophenols and NN exhibit different mixing states and diurnal variations. Four mononitrophenols were internally mixed well with each other, and with organic acids, nitrates, potassium, and naphthalene. The diurnal variation in the number fraction of mononitrophenols presented two peaks at 07:00 to 09:00 and 18:00 to 20:00, and a valley at noon. Atmospheric environmental conditions, including NO2, O3, relative humidity, and temperature, can significantly influence the diurnal variation of mononitrophenols. Multiple linear regression and random forest regression models revealed that the main factors controlling the diurnal variation of mononitrophenols were photochemical reactions during the day and aqueous-phase reactions during the night. Unlike mononitrophenols, about 62-83% of NN were internally mixed with [NH4]+ and [H(NO3)2]-, but not with organic acids and potassium. The diurnal variation of NN was also different from that of mononitrophenols, generally increased from 17:00 to 10:00 and then rapidly decreaed from 11:00 to 16:00. These results imply that NN may have sources and atmospheric processes that are different from mononitrophenols. We speculate that this is mostly controlled by photochemical reactions and mixing with [NH4]+, which may influence the diurnal variation of NN in the ambient particles; however, this requires further confirmation. These findings extend our current understanding of the atmospheric formation and evolution of nitrophenols.
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Affiliation(s)
- Ziyong Guo
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China; College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, 030024, PR China
| | - Xiaodong Hu
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China
| | - Wei Sun
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China
| | - Xiaocong Peng
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China
| | - Yuzhen Fu
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China
| | - Kun Liu
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China
| | - Fengxian Liu
- School of Economics and Management, Taiyuan University of Technology, Taiyuan, 030024, PR China
| | - He Meng
- Qingdao Eco-environment Monitoring Center of Shandong Province, Qingdao, 266003, PR China
| | - Yujiao Zhu
- Environment Research Institute, Shandong University, Qingdao, 266237, PR China
| | - Guohua Zhang
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China; Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China
| | - Xinfeng Wang
- Environment Research Institute, Shandong University, Qingdao, 266237, PR China
| | - Likun Xue
- Environment Research Institute, Shandong University, Qingdao, 266237, PR China
| | - Jiancheng Wang
- College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, 030024, PR China
| | - Xinming Wang
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China; Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China
| | - Ping'an Peng
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China; Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China
| | - Xinhui Bi
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China; Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China.
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