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Armstrong NC, Chen Y, Cui T, Zhang Y, Christensen C, Zhang Z, Turpin BJ, Chan MN, Gold A, Ault AP, Surratt JD. Isoprene Epoxydiol-Derived Sulfated and Nonsulfated Oligomers Suppress Particulate Mass Loss during Oxidative Aging of Secondary Organic Aerosol. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:16611-16620. [PMID: 36378716 DOI: 10.1021/acs.est.2c03200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Acid-driven multiphase chemistry of isoprene epoxydiols (IEPOX) with inorganic sulfate aerosols contributes substantially to secondary organic aerosol (SOA) formation, which constitutes a large mass fraction of atmospheric fine particulate matter (PM2.5). However, the atmospheric chemical sinks of freshly generated IEPOX-SOA particles remain unclear. We examined the role of heterogeneous oxidation of freshly generated IEPOX-SOA particles by gas-phase hydroxyl radical (•OH) under dark conditions as one potential atmospheric sink. After 4 h of gas-phase •OH exposure (∼3 × 108 molecules cm-3), chemical changes in smog chamber-generated IEPOX-SOA particles were assessed by hydrophilic interaction liquid chromatography coupled with electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (HILIC/ESI-HR-QTOFMS). A comparison of the molecular-level compositional changes in IEPOX-SOA particles during aging with or without •OH revealed that decomposition of oligomers by heterogeneous •OH oxidation acts as a sink for •OH and maintains a reservoir of low-volatility compounds, including monomeric sulfate esters and oligomer fragments. We propose tentative structures and formation mechanisms for previously uncharacterized SOA constituents in PM2.5. Our results suggest that this •OH-driven renewal of low-volatility products may extend the atmospheric lifetimes of particle-phase IEPOX-SOA by slowing the production of low-molecular weight, high-volatility organic fragments and likely contributes to the large quantities of 2-methyltetrols and methyltetrol sulfates reported in PM2.5.
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Affiliation(s)
- N Cazimir Armstrong
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Yuzhi Chen
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Tianqu Cui
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Yue Zhang
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Cade Christensen
- Department of Chemistry, College of Arts and Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Zhenfa Zhang
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Barbara J Turpin
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Man Nin Chan
- Earth System Science Programme, Faculty of Science, The Chinese University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Avram Gold
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Andrew P Ault
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jason D Surratt
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
- Department of Chemistry, College of Arts and Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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Liu J, Chu B, Chen T, Zhong C, Liu C, Ma Q, Ma J, Zhang P, He H. Secondary Organic Aerosol Formation Potential from Ambient Air in Beijing: Effects of Atmospheric Oxidation Capacity at Different Pollution Levels. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:4565-4572. [PMID: 33733751 DOI: 10.1021/acs.est.1c00890] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Secondary organic aerosol (SOA) plays a critical role in sustained haze pollution in megacities. Traditional observation of atmospheric aerosols usually analyzes the ambient organic aerosol (OA) but neglects the SOA formation potential (SOAFP) of precursors remaining in ambient air. Knowledge on SOAFP is still limited, especially in megacities suffering from frequent haze. In this study, the SOAFP of ambient air in urban Beijing was characterized at different pollution levels based on a two-year field observation using an oxidation flow reactor (OFR) system. Both OA and SOAFP increased as a function of ambient pollution level, in which increasing concentrations of precursor volatile organic compounds (VOCs) and decreasing atmospheric oxidation capacity were found to be the two main influencing factors. To address the role of the atmospheric oxidation capacity in SOAFP, a relative OA enhancement ratio (EROA = 1 + SOAFP/OA) and the elemental composition of the OA were investigated in this study. The results indicated that the atmospheric oxidation capacity was weakened and resulted in higher SOAFP on more polluted days. The relationship found between SOAFP and the atmospheric oxidation capacity could be helpful in understanding changes in SOA pollution with improving air quality in the megacities of developing countries.
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Affiliation(s)
- Jun Liu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Biwu Chu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tianzeng Chen
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Cheng Zhong
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Changgeng Liu
- School of Biological and Chemical Engineering, Panzhihua University, Panzhihua 617000, China
| | - Qingxin Ma
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jinzhu Ma
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Peng Zhang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Hong He
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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Liu J, Chu B, Chen T, Liu C, Wang L, Bao X, He H. Secondary Organic Aerosol Formation from Ambient Air at an Urban Site in Beijing: Effects of OH Exposure and Precursor Concentrations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:6834-6841. [PMID: 29775300 DOI: 10.1021/acs.est.7b05701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Secondary organic aerosol (SOA) is an important component of atmospheric fine particles (PM2.5), while the key factors controlling SOA formation in ambient air remain poorly understood. In this work, the SOA formation in Beijing urban ambient air was investigated using an oxidation flow reactor (OFR) with high concentrations of OH radicals. The SOA formation potential increased significantly with the increase of ambient PM2.5 concentration during the observation. The optimum ambient exposure time, which is the aging time equivalent to atmospheric oxidation (with similar OH exposure) associated with the peak SOA formation, varied between 2 and 4 days in this study. The OA enhancement in this study was much higher than that of developed countries under different environmental conditions. The higher OA enhancement is probably due to the higher concentrations of volatile organic compounds (VOCs) in the urban air of Beijing. This might also have occurred because fragmentation did not dominate in the oxidation of OA, and did not result in negative OA enhancement on highly polluted days compared to relatively clean days with similar exposure time. These results suggested that under typical ambient conditions, high concentrations of VOC precursors might contribute to sustained organic aerosol growth and long duration haze events in Beijing.
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Affiliation(s)
- Jun Liu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , Beijing 100085 , China
- College of Environmental Science and Engineering , North China Electric Power University , Beijing 102206 , China
| | - Biwu Chu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , Beijing 100085 , China
- Center for Excellence in Regional Atmospheric Environment , Institute of Urban Environment, Chinese Academy of Sciences , Xiamen 361021 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Tianzeng Chen
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , Beijing 100085 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Changgeng Liu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , Beijing 100085 , China
- School of Resources and Environmental Engineering , Panzhihua University , Panzhihua 617000 , China
| | - Ling Wang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , Beijing 100085 , China
- College of Environmental Science and Engineering , North China Electric Power University , Beijing 102206 , China
| | - Xiaolei Bao
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , Beijing 100085 , China
- Hebei Provincial Academy of Environmental Sciences , Shijiazhuang 050051 , China
| | - Hong He
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , Beijing 100085 , China
- Center for Excellence in Regional Atmospheric Environment , Institute of Urban Environment, Chinese Academy of Sciences , Xiamen 361021 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
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Wu Y, Johnston MV. Aerosol Formation from OH Oxidation of the Volatile Cyclic Methyl Siloxane (cVMS) Decamethylcyclopentasiloxane. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:4445-4451. [PMID: 28333451 DOI: 10.1021/acs.est.7b00655] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Aerosol formation from OH oxidation of decamethylcyclopentasiloxane (D5, C10H30O5Si5), a cyclic volatile methyl siloxane (cVMS) found in consumer products, was studied in a flow-through photo-oxidation chamber with and without the presence of ammonium sulfate seed aerosol. For the unseeded experiments, chemical characterization with high-performance mass spectrometry showed that the molecular composition changed substantially with aerosol mass loading in the 1-12 μg/m3 range. Monomers (5 Si atoms/molecule) and dimers (10 Si atoms/molecule) dominated the mass spectra of aerosols at higher mass loadings, while ring-opened species (neither 5 nor 10 Si atoms/molecule) dominated the mass spectra of aerosols at lower mass loadings. Molecular signal intensity dependencies upon the aerosol volume/surface area ratio suggest that non-volatile ring-opened species are formed in the gas phase and assist particle formation through condensation, while dimers are formed by accretion reactions within the particle phase as the particles grow. These conclusions are supported by experiments in the presence of seed aerosol with a similar siloxane aerosol mass loading but higher volume/surface area ratio, where ring-opened species are much less prevalent than monomers or dimers and the aerosol yield is higher. Because of the importance of accretion chemistry, the aerosol yield from D5 oxidation is likely to be strongly dependent upon the particle size and morphology.
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Affiliation(s)
- Yue Wu
- Department of Chemistry and Biochemistry University of Delaware , Newark, Delaware 19716, United States
| | - Murray V Johnston
- Department of Chemistry and Biochemistry University of Delaware , Newark, Delaware 19716, United States
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Tu P, Hall WA, Johnston MV. Characterization of Highly Oxidized Molecules in Fresh and Aged Biogenic Secondary Organic Aerosol. Anal Chem 2016; 88:4495-501. [PMID: 27000653 PMCID: PMC4924475 DOI: 10.1021/acs.analchem.6b00378] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this work, highly oxidized multifunctional molecules (HOMs) in fresh and aged secondary organic aerosol (SOA) derived from biogenic precursors are characterized with high-resolution mass spectrometry. Fresh SOA was generated by mixing ozone with a biogenic precursor (β-pinene, limonene, α-pinene) in a flow tube reactor. Aging was performed by passing the fresh SOA through a photochemical reactor where it reacted with hydroxyl radicals. Although these aerosols were as a whole not highly oxidized, molecular analysis identified a significant number of HOMs embedded within it. HOMs in fresh SOA consisted mostly of monomers and dimers, which is consistent with condensation of extremely low-volatility organic compounds (ELVOCs) that have been detected in the gas phase in previous studies and linked to SOA particle formation. Aging caused an increase in the average number of carbon atoms per molecule of the HOMs, which is consistent with particle phase oxidation of (less oxidized) oligomers already existing in fresh SOA. HOMs having different combinations of oxygen-to-carbon ratio, hydrogen-to-carbon ratio and average carbon oxidation state are discussed and compared to low volatility oxygenated organic aerosol (LVOOA), which has been identified in ambient aerosol based on average elemental composition but not fully understood at a molecular level. For the biogenic precursors and experimental conditions studied, HOMs in fresh biogenic SOA have molecular formulas more closely resembling LVOOA than HOMs in aged SOA, suggesting that aging of biogenic SOA is not a good surrogate for ambient LVOOA.
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Affiliation(s)
- Peijun Tu
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA
| | - Wiley A. Hall
- DFA of California, 1855 South Van Ness Avenue, Fresno, CA 93721, USA
| | - Murray V. Johnston
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA
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Glasius M, Goldstein AH. Recent Discoveries and Future Challenges in Atmospheric Organic Chemistry. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:2754-64. [PMID: 26862779 DOI: 10.1021/acs.est.5b05105] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Earth's atmosphere contains a multitude of organic compounds, which differ by orders of magnitude regarding fundamental properties such as volatility, reactivity, and propensity to form cloud droplets, affecting their impact on global climate and human health. Despite recent major research efforts and advances, there are still substantial gaps in understanding of atmospheric organic chemistry, hampering efforts to understand, model, and mitigate environmental problems such as aerosol formation in both polluted urban and more pristine regions. The analytical toolbox available for chemists to study atmospheric organic components has expanded considerably during the past decade, opening new windows into speciation, time resolution and detection of reactive and semivolatile compounds at low concentrations. This has provided unprecedented opportunities, but also unveiled new scientific challenges. Specific groundbreaking examples include the role of epoxides in aerosol formation especially from isoprene, the importance of highly oxidized, reactive organics in air-surface processes (whether atmosphere-biosphere exchange or aerosols), as well as the extent of interactions of anthropogenic and biogenic emissions and the resulting impact on atmospheric organic chemistry.
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Affiliation(s)
- Marianne Glasius
- Department of Chemistry and iNANO, Aarhus University , 8000 Aarhus C, Denmark
| | - Allen H Goldstein
- Department of Environmental Science, Policy and Management, and Department of Civil and Environmental Engineering, University of California , Berkeley, California 94720, United States
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Wu Y, Johnston MV. Molecular Characterization of Secondary Aerosol from Oxidation of Cyclic Methylsiloxanes. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:402-9. [PMID: 26729452 PMCID: PMC4929013 DOI: 10.1007/s13361-015-1300-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 10/08/2015] [Accepted: 10/10/2015] [Indexed: 05/06/2023]
Abstract
Cyclic volatile methylsiloxanes (cVMS) have been identified as important gas-phase atmospheric contaminants, but knowledge of the molecular composition of secondary aerosol derived from cVMS oxidation is incomplete. Here, the chemical composition of secondary aerosol produced from the OH-initiated oxidation of decamethylcyclopentasiloxane (D5, C10H30O5Si5) is characterized by high performance mass spectrometry. ESI-MS reveals a large number of monomeric (300 < m/z < 470) and dimeric (700 < m/z < 870) oxidation products. With the aid of high resolution and MS/MS, it is shown that oxidation leads mainly to the substitution of a CH3 group by OH or CH2OH, and that a single molecule can undergo many CH3 group substitutions. Dimers also exhibit OH and CH2OH substitutions and can be linked by O, CH2, and CH2CH2 groups. GC-MS confirms the ESI-MS results. Oxidation of D4 (C8H24O4Si4) exhibits similar substitutions and oligomerizations to D5, though the degree of oxidation is greater under the same conditions and there is direct evidence for the formation of peroxy groups (CH2OOH) in addition to OH and CH2OH.
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Affiliation(s)
- Yue Wu
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Murray V Johnston
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
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Marine biogenic source of atmospheric organic nitrogen in the subtropical North Atlantic. Proc Natl Acad Sci U S A 2016; 113:925-30. [PMID: 26739561 DOI: 10.1073/pnas.1516847113] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Global models estimate that the anthropogenic component of atmospheric nitrogen (N) deposition to the ocean accounts for up to a third of the ocean's external N supply and 10% of anthropogenic CO2 uptake. However, there are few observational constraints from the marine atmospheric environment to validate these findings. Due to the paucity of atmospheric organic N data, the largest uncertainties related to atmospheric N deposition are the sources and cycling of organic N, which is 20-80% of total N deposition. We studied the concentration and chemical composition of rainwater and aerosol organic N collected on the island of Bermuda in the western North Atlantic Ocean over 18 mo. Here, we show that the water-soluble organic N concentration ([WSON]) in marine aerosol is strongly correlated with surface ocean primary productivity and wind speed, suggesting a marine biogenic source for aerosol WSON. The chemical composition of high-[WSON] aerosols also indicates a primary marine source. We find that the WSON in marine rain is compositionally different from that in concurrently collected aerosols, suggesting that in-cloud scavenging (as opposed to below-cloud "washout") is the main contributor to rain WSON. We conclude that anthropogenic activity is not a significant source of organic N to the marine atmosphere over the North Atlantic, despite downwind transport from large pollution sources in North America. This, in conjunction with previous work on ammonium and nitrate, leads to the conclusion that only 27% of total N deposition to the global ocean is anthropogenic, in contrast to the 80% estimated previously.
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Bzdek BR, Horan AJ, Pennington MR, DePalma JW, Zhao J, Jen CN, Hanson DR, Smith JN, McMurry PH, Johnston MV. Quantitative and time-resolved nanoparticle composition measurements during new particle formation. Faraday Discuss 2013; 165:25-43. [DOI: 10.1039/c3fd00039g] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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