JOURNAL OF HAZARDOUS MATERIALS
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2024
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IF 12.2
Danni Wu,Haonan Wu,Yan Lyu,Huiying Zhang,Jiade Wang,Xiang Li,Xiaobing Pang
Atmospheric particulate matter (PM) poses adverse effects on human via producing reactive oxygen species (ROS). Oxidative potential (OP, ability to generate ROS) can be induced by various chemicals in PM, while their interplay remains poorly characterized. Here, we systematically assessed influences of Cu 2+ on OP of Brown carbon (BrC) (e.g., imidazoles) using dithiothreitol (DTT) assay. Results showed DTT consumption rate exhibited an initial rise and later decline (0.25 −0.56 µM/min) along with increase of BrC concentration (0.1 − 2 µM), while no general trend was observed for • OH formation. Although Cu 2+ showed either antagonism or synergism with BrC against DTT consumption, Cu 2+ displayed antagonism with most BrC against • OH generation. Fluorescence quenching experiments provided evidence of complexation between Cu 2+ and water-soluble organic compounds (WSOCs, from ambient PM 2.5 ), which was influenced by Cu 2+ concentration. Further parallel factor analysis of spectra showed that polycarboxylate-type humic acid-like substances (complexation site number ( n ): 0.46, complexation equilibrium constant ( k ): 0.51) and fulvic acid-like compounds ( n : 0.42, k : 0.62) were the main components in WSOCs that complexed with Cu 2+ . Our results suggest the interactions of BrC and copper play a crucial role in PM OP and highlight complexation in evaluation of PM OP.
研究领域:
环境科学
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生物化学
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PubMed
高影响因子
ATMOSPHERIC ENVIRONMENT
·
2024
·
IF 4.2
Hongxing Yang,Wangjin Yang,Jiawei Ma,Chong Han
The heterogeneous reactions of SO 2 on organic aerosols (OA) have been proposed as a significant source of sulfates. The photochemical conversion of SO 2 to sulfates on the surface of light-absorbing OA, i.e., brown carbon (BrC), remained slight understanding. Herein, the photochemical uptake of SO 2 on typical BrC species, including aromatic carbonyl compounds (ACs), polycyclic aromatic hydrocarbons (PAHs) and phenols (PHs), was systematically investigated by a flow tube reactor. Light can significantly promote the uptake of SO 2 on all BrC species used here, especially for ACs. The initial and steady-state uptake coefficients (γ i and γ ss ) of SO 2 exhibited positive relationships with the light intensity, whereas they negatively correlated with the initial SO 2 concentration. Significant sulfate formation was clearly observed with in situ attenuated total internal reflection infrared (ATR-IR) spectrometer, and H 2 O and O 2 had obvious enhancement effects on the sulfate production. Photoinduced •OH, which primarily originated from •O 2 − that was generated through an electron transfer process on BrC under irradiation, was determined to be a key driver for the oxidation of SO 2 to sulfates. Finally, SO 2 lifetime and sulfate formation rate were evaluated on the basis of experimental results, highlighting potential contributions of BrC photochemistry to atmospheric SO 2 loss and sulfate sources.
研究领域:
大气科学
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环境化学
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DOI
高影响因子
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2019
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IF 2.931
Yan Gao,Yunhong Zhang
In recent years, “brown carbon” (BrC), as an important contributor to light absorption and climate forcing as aerosols, has been one of the forefronts in the field of atmospheric research. Aqueous BrC aerosols can be formed through aqueous reactions of methylglyoxal (MG) with nitrogen compounds, such as glycine (Gly) and ammonium sulfate (AS). When exposed to nitrogen compounds for several days, aqueous carbonyl compound MG became absorbent and fluorescent in the ultraviolet and near visible regions, according to UV/Vis and fluorescence spectroscopies. Experiment results showed that optical absorption of two aqueous BrC solutions in the spectral range of 250–480 nm significantly increased with increasing reaction time. After the reactions of MG with Gly and AS, the product absorbance followed the order of MG-Gly>MG-AS. For H 2 O 2 oxidation photolysis, the atmospheric aqueous BrC showed the dynamic nature. Reaction kinetic, effective quantum yields and size distribution studies were conducted in the paper. Fluorescence lifetime values of the two BrC solutions were calculated. LC/MS analysis results clearly indicated that complicated organic compounds were formed in the reactions of MG with Gly and AS.
研究领域:
大气科学
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环境化学
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DOI
PubMed
高影响因子
Journal of Environmental Sciences
·
2025
·
IF 6.3
Kun Liu,Tao Wang,Guohua Zhang,Wei Sun,Ye Yang,Mingjin Tang,Xinming Wang,Xinhui Bi
Aqueous-phase reactions between carbonyls and reduced nitrogen compounds play a considerable role in the formation of secondary organic aerosols and brown carbon in the atmosphere. However, the reported reaction rate constants for these reactions have largely been limited to bulk aqueous-phase simulations, which may not accurately represent the real state of atmospheric cloud droplets. We employed an integration of optical tweezers and Raman spectroscopy to manipulate and analyze simulated cloud droplets (size range 8000-10000 nm), comprising a mixture of glyoxal and ammonium sulfate. This approach enabled us to delve into the intricate realm of their reaction kinetics at individual droplet level mimicking cloud droplets. Raman spectroscopy provided high temporal resolution (20 s) measurements of the changes in the amount of nitrogen-containing organics (or NOCs as represented by the C-N bond) within the droplets. The results indicate that the reaction follows first-order kinetics throughout the monitoring over 80-400 minutes. The average reaction rate constant for the formation of NOCs within the single droplet was determined to be (6.77 ± 0.98) × 10 -5 s -1 , up to three orders of magnitude higher than those through the bulk aqueous-phase simulations, especially at lower pH levels. Additionally, the reaction rate constant in single droplet increases with increasing pH, consistent with the trend previously reported for the aqueous-phase simulations. The results highlight the difference of the reaction rate constant between bulk aqueous phase and droplets, which would improve our understanding on the formation and impacts of secondary organic aerosols and brown carbon in atmospheric aqueous phase.
研究领域:
大气科学
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化学动力学
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PubMed
高影响因子
Environmental Chemistry Letters
·
2018
·Vol. 16
·期 3
·1083-1088
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IF 3.125
Yi Yayi,Zhou Xuehua,Xue Likun,Wang Wenxing
Air pollution by industry and humans activities is a major health issue, notably in major cities. Secondary organic aerosols are formed by oxidation of volatile organic compounds, accounting for 20–80% of organic aerosols in the atmosphere. Secondary organic aerosols are contributing to photochemical smog in urban areas. However, the mechanisms of formation of secondary organic aerosols are still poorly understood. Here, we synthesized secondary organic aerosols by aqueous reaction of hydroxyacetone and methylamine in the dark. Products were analyzed by UV–Vis spectrophotometry and liquid chromatography–mass spectrometry-ion trap-time of flight. Results showed that all reactions fit first-order kinetics, and reactions were accelerated with reactants’ concentrations and pH. The main reaction mechanisms were aldolization of hydroxyacetone, and nucleophilic attack of methylamine to hydroxyacetone, followed by dehydration. The main products were imines, transforming the solution from colorless to deep brown, which is responsible for about 1% of light absorption by atmospheric brown carbon.
研究领域:
环境科学
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大气化学
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DOI
高影响因子
Atmospheric Pollution Research
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2022
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IF 4.831
Mincong Zhu,Mingqiang Huang,Tingting Lu,Shunyou Cai,Xiaobin Shan,Liusi Sheng,Weixiong Zhao,Xuejun Gu,Weijun Zhang
Imidazole and its derivatives are the main heterocyclic nitrogen-containing brown carbon constituents in aerosol particles. Imidazoles of aqueous secondary organic aerosol (aqSOA) particles formed from the reaction of methylglyoxal and ammonium sulphate ((NH 4 ) 2 SO 4 ) are detected by vacuum ultraviolet photoionization aerosol mass spectrometer (VUV-PIMS) in real-time and verified off-line with optical spectrometry in current study. The experimental results showed that the single photon ionization mass spectrum of aqSOA particles measured by VUV-PIMS emerged the molecular ion peaks at m/z = 68, 82 and 110. While, the extraction solution of aqSOA particles detected by off-line techniques demonstrated that the characteristic peaks at 217 and 282 nm appeared in the UV–Vis spectrum; the strong emission in 405–480 nm with maximum emission wavelength at 435 nm contained in the 3D fluorescence spectra; and the chemical shift peaks of hydrogen atoms on N–H, C C and C N bond on imidazole ring and methyl group arised in the 1 H-NMR spectrum. In view of these spectral information, 4-methyl-imidazole and 4-methyl-imidazole-2-carbaldehyde are determined as the principal products of the aqueous reaction between methylglyoxal and (NH 4 ) 2 SO 4 . The possible reaction mechanism leading to the generation of imidazole compounds are also discussed. These will help to understand the formation process of imidazole compounds in atmospheric aerosol particles , and provide experimental basis for the model mechanism study of aqSOA particles.
研究领域:
大气化学
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环境科学
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DOI
高影响因子
Environmental Science-Processes & Impacts
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2024
·Vol. 26
·期 9
·1526-1542
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IF 4.3
Junwei Yang,Tianye Zhou,Yuting Lyu,Brix Raphael Go,Jason Chun-Ho Lam,Chak K. Chan,Theodora Nah
Many phenolic compounds (PhCs) in biomass burning and fossil fuel combustion emissions can partition into atmospheric aqueous phases (e.g., cloud/fog water and aqueous aerosols) and undergo reactions to form secondary organic aerosols (SOAs) and brown carbon (BrC). Redox-active transition metals, particularly Fe and Cu, are ubiquitous species in atmospheric aqueous phases known to participate in Fenton/Fenton-like chemistry as a source of aqueous ˙OH. However, even though the concentrations of water-soluble Cu are close to those of water-soluble Fe in atmospheric aqueous phases in some areas, unlike Fe, the effects that Cu have on SOA and BrC formation in atmospheric aqueous phases have scarcely been studied and remain poorly understood. We investigated the effects of Cu(II) on PhC reaction rates and BrC formation during the aqueous oxidation of four PhCs (guaiacol, catechol, syringol, and vanillin) by ˙OH generated from Fenton-like chemistry under different pH conditions. While the PhCs reacted when both H2O2 and Cu(II) were present in the absence (i.e., dark oxidation) and presence (i.e., photooxidation) of light, the reaction rates were at least one order of magnitude higher during photooxidation. Higher PhC reaction rates were measured at higher pH during both dark oxidation and photooxidation as a result of higher ˙OH concentrations produced by Fenton-like chemistry. Only water-soluble BrC was formed during dark oxidation and photooxidation when Cu(II) was present. Mass absorption coefficients (103 to 104 cm2 g−1) comparable to those of biomass burning BrC were measured during dark oxidation and photooxidation when Cu(II) was present. Light absorption was enhanced at higher pH during dark oxidation and photooxidation, which indicated that higher quantities and/or more absorbing BrC chromophores were formed at higher pH. The effects that Cu(II) had on the PhC reaction rates and the composition of SOAs and BrC formed depended on the PhC base structure (i.e., benzenediol vs. methoxyphenol). Overall, these results show how aqueous reactions involving Cu(II), H2O2, and PhCs can be an efficient source of daytime and nighttime water-soluble BrC and SOAs, which can have significant implications for how the atmospheric fates of PhCs are modeled for areas with substantial concentrations of water-soluble Cu in highly to moderately acidic cloud/fog water and aqueous aerosols.
研究领域:
大气化学
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环境科学
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DOI
高影响因子
Chemical Science
·
2022
·Vol. 13
·期 28
·8401-8411
·
IF 9.969
Shanshan Tang,Feifei Li,Jitao Lv,Lei Liu,Guangming Wu,Yarui Wang,Wanchao Yu,Yawei Wang,Guibin Jiang
Atmospheric brown carbon (BrC) exerts a key impact on the global radiative balance due to its light-absorbing properties. Maillard-like reactions between carbonyl and amino compounds have been identified as an important pathway for forming secondary BrC. Although optical properties have been widely studied, the molecular composition of secondary BrC generated in Maillard chemistry remains unclear, resulting in a knowledge gap to understand its formation and light-absorbing mechanism. In this study, a combination of optical spectroscopy, 1H nuclear magnetic resonance (NMR), and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was employed to comprehensively characterize the chemical and light-absorbing characteristics of secondary BrC. The results indicate that both the light-absorbing and molecular characteristics of secondary BrC were highly related to the structures of their precursors. Organic amine precursors consistently result in enhanced light-absorbing capacities of BrC compared to ammonium, but have inconsistent effects on the molecular diversity of BrC. Compared to amino precursors (i.e., glycine, ethylamine, propylamine, and ammonium), carbonyl precursors play a more important role in determining the molecular diversity of BrC. Different from black carbon, the light-absorbing products from Maillard-like reactions are mainly nitrogen-containing heterocycles. Unexpectedly, 35–64% of molecular formulae detected in real atmospheric samples were found in simulated Maillard reaction products, implying a potentially important contribution of Maillard chemistry to the atmospheric organic molecular pool. These results will improve our understanding of the formation and molecular diversity of BrC, and further help to manage emissions of secondary aerosol precursors.
研究领域:
环境科学
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化学
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PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2020
·
IF 6.551
Yangyang Liu,Tao Wang,Xiaozhong Fang,Yue Deng,Hanyun Cheng,Aziz-Ur-Rahim Bacha,Iqra Nabi,Liwu Zhang
The rapid sulfate formation is a crucial factor determining the explosive growth of fine particles and the frequent occurrence of severe haze events in China. Recent field observations also show that brown carbon is one of the most critical components in aerosol particles sampled during haze episodes. To this day, there is limited knowledge that accesses the role of brown carbon in atmospheric chemistry . In fact, these carbonaceous particulate matters , mainly derived from forest fires, biomass burning , and biogenic release, can act as photosensitizers and produce varieties of active intermediates to alter oxidation capacity. Experimental results in this work provide evidence that hydroxyl radical (∙OH) stems from brown carbon proxies fulvic acid /humic acid (FA/HA) upon irradiation, leading to rapid SO 2 oxidation on brown carbon particles in the atmosphere. Further correlation analyses for sulfate formation and chromophore properties of 12 model compounds demonstrate that brown carbon particles with higher aromaticity and E 2 /E 3 (the ratio of absorbance at 254 nm to that at 365 nm) would facilitate ∙OH production and SO 2 photo-oxidation. Uptake coefficient measurements and sulfate production rate estimation indicate that brown carbon could gain importance in atmospheric SO 2 oxidation. A better understanding of SO 2 uptake kinetics on brown carbon surfaces favors in defining new regulations to improve air quality and reduce the harmful effects of haze events on resident health and the environment.
研究领域:
大气科学
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环境化学
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DOI
PubMed
高影响因子
ENVIRONMENTAL POLLUTION
·
2025
·
IF 7.3
Shan Zhang,Kun Li,Xiaowen Chen,Zhaomin Yang,Lin Du
Brown carbon (BrC) and its light absorption properties, linked to molecular chromophores, influence Earth's radiative balance. However, the chemical complex formation of secondary BrC has obscured the relationship between molecular composition and optical characteristics. In this study, we investigated the secondary organic aerosol (SOA) optical properties and BrC chromophores formed from the oxidation of styrene, a typical compound from various anthropogenic emissions. The photochemical age spanned low to high oxidation degrees by deploying a smog chamber and an oxidation flow reactor (OFR). Light absorption increased with rising NO x concentrations under low oxidation degrees in the smog chamber experiments, followed by a decline with increasing photochemical ages at high oxidation degrees in the OFR experiments, likely attributed to the transition from functionalization to fragmentation reactions. Employing a high-resolution quadrupole time-of-flight mass spectrometer with a diode array detector, we characterized the BrC chromophores at a molecular level. We show that the dominant BrC chromophores in styrene SOA are nitrophenol compounds (e.g., C 6 H 5 NO 5 , C 6 H 5 NO 4, and C 6 H 5 NO 3 ). These nitrophenol compounds are proposed to primarily originate from the OH oxidation of benzaldehyde, an intermediate product in the oxidation of styrene. Overall, this study presents a comprehensive characterization of the light absorption of styrene SOA under varying oxidation degrees and provides insights into the contribution of styrene-derived BrC and its implications for radiative forcing.
研究领域:
大气化学
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环境科学
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DOI
PubMed
高影响因子
ENVIRONMENTAL POLLUTION
·
2025
·
IF 7.3
Hongxing Yang,Wangjin Yang,Shiwei Lai,Fu Li,Shaojie Yang,Chong Han
The role of NO 2 in the heterogeneous photochemical formation of sulfates by SO 2 uptake on typical brown carbon (BrC) species (Fluoranthene, FL; 4-(benzoyl) benzoic acid , 4–BBA; 3,7-dihydroxy-2-naphthoic acid, 3,7–DHNA) was systemically explored in a flow tube reactor with the infrared spectroscopy , ion chromatography as well as theoretical calculation. NO 2 enhanced SO 2 uptake and sulfate generation on BrC under irradiation, as shown by larger steady-state uptake coefficients of SO 2 and sulfate formation rates. NO 2 − can be produced through the reduction of NO 2 by the photogenerated electrons on BrC, and it was proven to be the trigger that promoted the oxidation of SO 2 to sulfates. NO 2 − was more easily formed on FL, followed by 4−BBA and 3,7−DHNA, which can be evidenced by the energy barrier for NO 2 − production: FL (0.01 kJ mol −1 ) < 4−BBA (0.12 kJ mol −1 ) < 3,7−DHNA (1.33 kJ mol −1 ). SO 2 lifetimes and sulfate formation rates during the reaction of SO 2 /NO 2 with BrC were estimated to be 10.60–31.75 days and 0.02–0.04 μg m −3 h −1 , respectively.
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高影响因子
ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2024
·
IF 10.8
Qiuju Shi,Lei Gao,Wenjian Li,Jiaxin Wang,Zhang Shi,Yixin Li,Jiangyao Chen,Yuemeng Ji,Taicheng An
Uncertain chemical mechanisms leading to brown carbon (BrC) formation affect the drivers of the radiative effects of aerosols in current climate predictions. Herein, the aqueous-phase reactions of methylglyoxal (MG) and typical reduced nitrogen species (RNSs) are systematically investigated by using combined quantum chemical calculations and laboratory experiments. Imines and diimines are identified from the mixtures of methylamine (MA) and ammonia (AM) with MG, but not from dimethylamine (DA) with the MG mixture under acidic conditions, because deprotonation of DA cationic intermediates is hindered by the amino groups occupied by two methyl groups. It leads to N-heterocycle (NHC) formation in the MG + MA (MGM) and MG + AM (MGA) reaction systems but to N-containing chain oligomer formation in the MG + DA (MGD) reaction system. Distinct product formation is attributed to electrostatic attraction and steric hindrance, which are regulated by the methyl groups of RNSs. The light absorption and adverse effects of NHCs are also strongly related to the methyl groups of RNSs. Our finding reveals that BrC formation is mainly contributed from MG reaction with RNSs with less methyl groups, which have more abundant and broad sources in the urban environments.
研究领域:
大气化学
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环境科学
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量子化学
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PubMed
高影响因子
危险品化学品经营许可证（带存储）