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Yang W, Xia Z, Zheng J, Li F, Nan X, Du T, Han C. Reactive oxygen species play key roles in the nitrite formation by the inorganic nitrate photolysis in the presence of urban water-soluble organic carbon. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 946:174203. [PMID: 38909793 DOI: 10.1016/j.scitotenv.2024.174203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 05/30/2024] [Accepted: 06/21/2024] [Indexed: 06/25/2024]
Abstract
Inorganic nitrates were considered to be a potential source of atmospheric NO2-/HONO during the daytime. To better evaluate the contribution of nitrate photochemistry on NO2-/HONO formation, the photolysis of nitrates in the real atmospheric environment needs to be further explored. Here, the NO2- generation by the photolysis of inorganic nitrates in the presence of total water-soluble organic carbon (WSOC) was quantified. The physicochemical properties of WSOC were measured to understand the underlying mechanism for the photolysis of inorganic nitrates with WSOC. WSOC enhanced or suppressed the photochemical conversion of nitrates to NO2-, with the quantum yield of NO2- (ΦNO2-) varying from (0.07 ± 0.02)% to (3.11 ± 0.04)% that depended on the light absorption properties of WSOC. Reactive oxygen species (ROS) generated from WSOC, including O2-/HO2 and OH, played a dual role in the NO2- formation. Light-absorbing substances in WSOC, such as N-containing and carbonyl aromatics, produced O2-/HO2 that enhanced the secondary conversion of NO2 to NO2-. On the other hand, OH deriving from the WSOC photochemistry inhibited the nitrate photodegradation and the NO2- formation. HONO source strength by the aqueous photolysis of nitrates with WSOC was estimated to be lower than 100 ppt h-1, which may partly contribute to the atmospheric HONO source in some cases.
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Affiliation(s)
- Wangjin Yang
- School of Metallurgy, Northeastern University, Shenyang 110819, China
| | - Zhifu Xia
- School of Metallurgy, Northeastern University, Shenyang 110819, China
| | - Jianwei Zheng
- School of Metallurgy, Northeastern University, Shenyang 110819, China
| | - Fu Li
- School of Metallurgy, Northeastern University, Shenyang 110819, China
| | - Xiangli Nan
- School of Metallurgy, Northeastern University, Shenyang 110819, China
| | - Tao Du
- School of Metallurgy, Northeastern University, Shenyang 110819, China
| | - Chong Han
- School of Metallurgy, Northeastern University, Shenyang 110819, China.
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Kim H, Park EH. Effects of chemical composition of ambient PM 2.5 measured in Seoul on potential health risks and generation of reactive oxygen species. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 352:124139. [PMID: 38734055 DOI: 10.1016/j.envpol.2024.124139] [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: 10/04/2023] [Revised: 05/08/2024] [Accepted: 05/09/2024] [Indexed: 05/13/2024]
Abstract
This study assesses the health effects associated with the chemical species of ambient particulate matter (PM) with an aerodynamic diameter ≤2.5 μm (PM2.5) in Seoul, focusing on identifying key chemical constituents and their sources. We employed two approaches to estimate health risks: (1) evaluating carcinogenic and noncarcinogenic risks using IRIS (Integrated Risk Information System) data from the US EPA (Environmental Protection Agency), and (2) quantifying the generation of hydroxyl radicals (·OH) following exposure to PM2.5 in surrogate lung fluid (SLF). Our results show a significant impact on human health from certain elements (Cr, Ni, As, and Cd) and polycyclic aromatic hydrocarbons (PAHs) (DaeP, DahA, and BaP for carcinogenic risks; BaP and BeP for noncarcinogenic risks). Notably, Cr and BaP, which are influential in both risk assessment and ·OH generation, highlight their significant roles in human health impacts. However, other components (e.g., CPP, BaP, BghiP, BaA, CHR, PYR, FLT, Ca, Mg, and Cu), though contributors to ·OH generation, were not included in the EPA's health risk assessment, suggesting a need for a broader PM2.5 compositional analysis to more accurately determine exposure concentrations and assess inhalation risks. These components predominantly originate from anthropogenic sources, such as combustion, vehicles, and industrial activities, underscoring the significant health implications of the pollutants emitted from these sources. The study concluded that focusing solely on the mass reduction of PM2.5 may not suffice; a dual approach that reduces both mass concentration and chemical-specific health risks is imperative for effective public health protection.
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Affiliation(s)
- Hwajin Kim
- Department of Environmental Health Sciences, Graduate School of Public Health, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea; Institute of Health and Environment, Seoul National University, 1 Gwanak, Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.
| | - Eun Ha Park
- Institute of Health and Environment, Seoul National University, 1 Gwanak, Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea; Now at Research Institute of Industrial Science and Technology, 67 Cheongam-ro, Namgu, Pohang-si, Gyeongsangbuk-do 37673, Republic of Korea
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Huang S, Shen Z, Yang X, Bai G, Zhang L, Zeng Y, Sun J, Xu H, Ho SSH, Zhang Y, Cao J. Nitroaromatic compounds in six major Chinese cities: Influence of different formation mechanisms on light absorption properties. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 930:172672. [PMID: 38663628 DOI: 10.1016/j.scitotenv.2024.172672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2024] [Revised: 04/19/2024] [Accepted: 04/19/2024] [Indexed: 05/05/2024]
Abstract
Nitroaromatic compounds (NACs) are important nitrogen organics in aerosol with strong light-absorbing and chemically reactive properties. In this study, NACs in six Chinese megacities, including Harbin (HB), Beijing (BJ), Xi'an (XA), Wuhan (WH), Chengdu (CD), and Guangzhou (GZ), were investigated for understanding their sources, gas-particle partitioning, and impact on BrC absorption properties. The concentrations of ΣNACs in PM2.5 in the six cities ranged from 9.15 to 158.8 ng/m3 in winter and from 2.02 to 9.39 ng/m3 in summer. Nitro catechols (NCs), nitro phenols (NPs), and nitro salicylic acids (NSAs) are the main components in ΣNACs, with NCs being dominant in particulate phase and NPs being dominant in the gas phase. Correlation analysis between different pollutant species revealed that coal and biomass combustions were the major sources of NACs in the northern cities during wintertime, while secondary formation dominated NACs in the southern cities during summertime. The contribution of ΣNACs to brown carbon (BrC) light absorption ranged from 0.85 to 7.98 % during the wintertime and 2.07-6.44 % during the summertime. The mass absorption efficiency at 365 nm (MAE365) were highest for 4-nitrocatechol (4NC, 17.4-89.0 m2/g), 4-methyl-5-nitrocatechol (4M5NC, 15.0-76.9 m2/g), and 4-nitroguaiacol (4NG, 11.7-59.8 m2/g). The formation of NCs and NG through oxidation and nitration of catechol and guaiacol led to a significant increase in aerosol light absorption. In contrast, NPs and NSAs formed by the photonitration and photooxidation in liquid phase showed high polarity but low light absorption ability, and the proportions of (NPs + NSAs) in the light absorption of ΣNACs were lower than 15.3 % in the six megacities.
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Affiliation(s)
- Shasha Huang
- Department of Environmental Sciences and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Zhenxing Shen
- Department of Environmental Sciences and Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Xueting Yang
- Department of Environmental Sciences and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Gezi Bai
- Department of Environmental Sciences and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Leiming Zhang
- Air Quality Research Division, Science and Technology Branch, Environment and Climate Change Canada, Toronto, Canada
| | - Yaling Zeng
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Jian Sun
- Department of Environmental Sciences and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Hongmei Xu
- Department of Environmental Sciences and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Steven Sai Hang Ho
- Division of Atmospheric Sciences, Desert Research Institute, Reno NV89512, United States
| | - Ying Zhang
- Instruments Analysis Center of Xi'an Jiaotong University, Xi'an 710049, China
| | - Junji Cao
- Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
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Dey S, Sarkar S. Compositional and optical characteristics of aqueous brown carbon and HULIS in the eastern Indo-Gangetic Plain using a coupled EEM PARAFAC, FT-IR and 1H NMR approach. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 921:171084. [PMID: 38382603 DOI: 10.1016/j.scitotenv.2024.171084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/30/2024] [Accepted: 02/17/2024] [Indexed: 02/23/2024]
Abstract
This study provides insights into the fluorophoric composition of aqueous brown carbon (BrCaq) and chemically-separated humic-like substances (HULIS): neutral HULIS (HULIS-n; at pH = 7) and acidic HULIS (HULIS-a; at pH = 2) on a seasonal and day-night basis in the eastern Indo-Gangetic Plain (IGP), India. A coupled approach including excitation-emission matrix (EEM) fluorescence and parallel factor analysis (PARAFAC) model, Fourier-transformed infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy was employed to understand the links between structural, compositional and fluorophoric characteristics of BrCaq and HULIS fractions. HULIS fluorophores (HULISfluoro) with varying oxidation states transported from the northwest IGP were dominant during biomass burning seasons (post-monsoon and winter), while protein-like fluorophores (PRLISfluoro) from marine emissions showed large contributions during summer. HULIS-n moieties were mostly primary in nature with higher conjugation, while HULIS-a were associated with secondarily formed and aged species with a larger contribution from degradation products. A substantial presence of tyrosine-like proteins in both chemically-separated HULIS fractions indicated that atmospheric HULIS is not entirely humic or fulvic-like in the eastern IGP. Finally, the dominance of H-C-O groups across seasons suggested consistent fossil fuel signatures along with season-specific influence of photodegradable cellulose from marine organisms in the summer and biomass burning in the post-monsoon and winter.
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Affiliation(s)
- Supriya Dey
- School of Civil and Environmental Engineering, Indian Institute of Technology (IIT) Mandi, Kamand, Himachal Pradesh 175075, India
| | - Sayantan Sarkar
- School of Civil and Environmental Engineering, Indian Institute of Technology (IIT) Mandi, Kamand, Himachal Pradesh 175075, India.
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Wang D, Shen Z, Yang X, Huang S, Luo Y, Bai G, Cao J. Insight into the Role of NH 3/NH 4+ and NO x/NO 3- in the Formation of Nitrogen-Containing Brown Carbon in Chinese Megacities. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:4281-4290. [PMID: 38391182 DOI: 10.1021/acs.est.3c10374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2024]
Abstract
Particulate brown carbon (BrC) plays a crucial role in the global radiative balance due to its ability to absorb light. However, the effect of molecular formation on the light absorption properties of BrC remains poorly understood. In this study, atmospheric BrC samples collected from six Chinese megacities in winter and summer were characterized through ultrahigh-performance liquid chromatography coupled with Orbitrap mass spectrometry (UHPLC-Orbitrap MS) and light absorption measurements. The average values of BrC light absorption coefficient at a wavelength of 365 nm (babs365) in winter were approximately 4.0 times higher than those in summer. Nitrogen-containing organic molecules (CHNO) were identified as critical components of light-absorbing substances in both seasons, underscoring the importance of N-addition in BrC. These nitrogen-containing BrC chromophores were more closely related to nitro-containing compounds originating from biomass burning and nitrogen oxides (NOx)/nitrate (NO3-) reactions in winter. In summer, they were related to reduced N-containing compounds formed in ammonia (NH3)/ammonium (NH4+) reactions. The NH3/NH4+-mediated reactions contributed more to secondary BrC in summer than winter, particularly in southern cities. Compared with winter, the higher O/Cw, lower molecule conjugation indicator (double bond equivalent, DBE), and reduced BrC babs365 in summer suggest a possible bleaching mechanism during the oxidation process. These findings strengthen the connection between molecular composition and the light-absorbing properties of BrC, providing insights into the formation mechanisms of BrC chromophores across northern and southern Chinese cities in different seasons.
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Affiliation(s)
- Diwei Wang
- Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Zhenxing Shen
- Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Xueting Yang
- Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Shasha Huang
- Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Yu Luo
- Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Gezi Bai
- Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Junji Cao
- Key Lab of Aerosol Chemistry & Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710049, China
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Tang T, Huo T, Tao H, Tian M, Yang H, Wang H. Effects of aerosol water content and acidity on the light absorption of atmospheric humic-like substances in winter. CHEMOSPHERE 2024; 349:140796. [PMID: 38029936 DOI: 10.1016/j.chemosphere.2023.140796] [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: 08/02/2023] [Revised: 11/19/2023] [Accepted: 11/22/2023] [Indexed: 12/01/2023]
Abstract
Atmospheric humic-like substances (HULIS) could affect regional climate due to their strong light-absorbing capacity. Daily fine particulate matter (PM2.5) samples were collected from December 18, 2016 to January 8, 2017 at an urban site in Chongqing, Southwest China. The mean concentration of HULIS in terms of carbon (HULIS-C) was 6.4 ± 3.4 μg m-3, accounting for 72% of water-soluble organic carbon. The mass absorption efficiency at 365 nm (MAE365) and absorption Ångström index (AAE) of atmospheric HULIS were 2.8 ± 0.30 m2 g-1 C and 4.6 ± 0.37, respectively. Good correlations between the light absorption coefficients of HULIS at 365 nm (Abs365) and the concentrations of K+, elemental carbon, NO3-, and NH4+ were observed, with correlation coefficients higher than 0.83, indicating that biomass burning and secondary formation were potential sources of light-absorbing HULIS, as evidenced by abundant fluorescent components related to less-oxygenated HULIS. Comparing the changes in Abs365 values, concentrations of major water-soluble inorganic ions and carbonaceous compounds in PM2.5, and environmental factors during the clean and pollution periods, we found that extensive biomass burning during the pollution period contributed significantly to the increase of Abs365 values. Moreover, the aerosol pH during the pollution period was close to 4, and NO2 concentration and aerosol water content were about 1.6 and 2.7 times higher than those during the clean period, respectively, which were favorable to form secondary HULIS through aqueous phase reactions in the presence of high NOx, resulting in an evident increase in its light absorption. Knowledge generated from this study is critical for evaluating the regional radiative forcing of brown carbon in southwest China.
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Affiliation(s)
- Tian Tang
- School of Environment and Resource, Southwest University of Science and Technology, Mianyang, 621010, China
| | - Tingting Huo
- School of Environment and Resource, Southwest University of Science and Technology, Mianyang, 621010, China
| | - Hongli Tao
- School of Environment and Resource, Southwest University of Science and Technology, Mianyang, 621010, China
| | - Mi Tian
- College of Environment and Ecology, Chongqing University, Chongqing, 400044, China
| | - Hao Yang
- School of Environment and Resource, Southwest University of Science and Technology, Mianyang, 621010, China
| | - Huanbo Wang
- School of Environment and Resource, Southwest University of Science and Technology, Mianyang, 621010, China.
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Dhandapani A, Iqbal J, Kumar RN, Bhardwaj A, Shukla D, Raman RS, Prasad SVL, Murthy BMS. Characterization of fine particulate matter water-soluble inorganic ions and estimation of aerosol acidity at three COALESCE network sites - Mysuru, Bhopal, and Mesra - in India. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:69241-69257. [PMID: 37133667 DOI: 10.1007/s11356-023-27032-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Accepted: 04/11/2023] [Indexed: 05/04/2023]
Abstract
The study was carried out to understand the chemical, spatiotemporal characteristics of water-soluble inorganic ions (WSIIs), their association with PM2.5 mass, and aerosol acidity in three COALESCE (carbonaceous aerosol emissions, source apportionment, and climate impacts) network sites of India (Mesra - Eastern India, Bhopal - Central India and Mysuru - Southern India). Alternate-day 24-h integrated bulk PM2.5 samples were collected during 2019 along with on-site meteorological parameters. Annual average PM2.5 concentrations were 67 ± 46 µg m-3, 54 ± 47 µg m-3, and 30 ± 24 µg m-3 at Mesra, Bhopal, and Mysuru, respectively. PM2.5 concentrations exceeded the annual mean (40 µg m-3) recommended by the National Ambient Air Quality Standards (NAAQS) at Mesra and Bhopal. WSIIs existed in PM2.5 mass at Mesra (50.5%), Bhopal (39.6%), and Mysuru (29.2%). SO42-, NO3-, and NH4+ (SNA) were major secondary inorganic ions in total WSIIs, with an annual average of 88.4% in Mesra and 82.0% in Bhopal 78.4% in Mysuru. Low NO3-/SO42- ratios annually at Mesra (0.41), Bhopal (0.44), and Mysuru (0.24) indicated that stationary sources dominated vehicular emissions (1.0). Aerosol acidity varied from region to region and season to season depending on the presence of NH4+, the dominant counter-ion to neutralize anions. Aerosols were near-neutral or alkaline at all three sites, except during the pre-monsoon season in Mysuru. An assessment of neutralization pathways for major anions [SO42- + NO3-] suggests that they mainly existed as sulfate and nitrate salts such as ammonium sulfate ((NH4)2SO4) and ammonium bisulfate (NH4HSO4) in conjunction with ammonium nitrate (NH4NO3).
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Affiliation(s)
- Abisheg Dhandapani
- Department of Civil and Environmental Engineering, Birla Institute of Technology, Mesra, Ranchi, 835215, Jharkhand, India
| | - Jawed Iqbal
- Department of Civil and Environmental Engineering, Birla Institute of Technology, Mesra, Ranchi, 835215, Jharkhand, India
| | - Radhakrishnan Naresh Kumar
- Department of Civil and Environmental Engineering, Birla Institute of Technology, Mesra, Ranchi, 835215, Jharkhand, India.
| | - Ankur Bhardwaj
- Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, India
| | - Deeksha Shukla
- Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, India
| | - Ramya Sunder Raman
- Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, India
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