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Gu S, Khalaj F, Perraud V, Faiola CL. Emerging investigator series: secondary organic aerosol formation from photooxidation of acyclic terpenes in an oxidation flow reactor. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2024. [PMID: 38812434 DOI: 10.1039/d4em00063c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
One major challenge in predicting secondary organic aerosol (SOA) formation in the atmosphere is incomplete representation of biogenic volatile organic compounds (BVOCs) emitted from plants, particularly those that are emitted as a result of stress - a condition that is becoming more frequent in a rapidly changing climate. One of the most common types of BVOCs emitted by plants in response to environmental stress are acyclic terpenes. In this work, SOA is generated from the photooxidation of acyclic terpenes in an oxidation flow reactor and compared to SOA production from a reference cyclic terpene - α-pinene. The acyclic terpenes used as SOA precursors included β-myrcene, β-ocimene, and linalool. Results showed that oxidation of all acyclic terpenes had lower SOA yields measured after 4 days photochemical age, in comparison to α-pinene. However, there was also evidence that the condensed organic products that formed, while a smaller amount overall, had a higher oligomeric content. In particular, β-ocimene SOA had higher oligomeric content than all the other chemical systems studied. SOA composition data from ultra-high performance liquid chromatography with electrospray ionization mass spectrometry (UHPLC-ESI-MS) was combined with mechanistic modeling using the Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) to explore chemical mechanisms that could lead to this oligomer formation. Calculations based on composition data suggested that β-ocimene SOA was more viscous with a higher glass transition temperature than other SOA generated from acyclic terpene oxidation. This was attributed to a higher oligomeric content compared to other SOA systems studied. These results contribute to novel chemical insights about SOA formation from acyclic terpenes and relevant chemistry processes, highlighting the importance of improving underrepresented biogenic SOA formation in chemical transport models.
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Affiliation(s)
- Shan Gu
- Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA, USA.
| | - Farzaneh Khalaj
- Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA, USA.
| | - Veronique Perraud
- Department of Chemistry, University of California Irvine, Irvine, CA, USA
| | - Celia L Faiola
- Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA, USA.
- Department of Chemistry, University of California Irvine, Irvine, CA, USA
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2
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Witkowski B, al-Sharafi M, Błaziak K, Gierczak T. Aging of α-Pinene Secondary Organic Aerosol by Hydroxyl Radicals in the Aqueous Phase: Kinetics and Products. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:6040-6051. [PMID: 37014140 PMCID: PMC10116591 DOI: 10.1021/acs.est.2c07630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 03/20/2023] [Accepted: 03/20/2023] [Indexed: 06/19/2023]
Abstract
The reaction of hydroxyl radicals (OH) with a water-soluble fraction of the α-pinene secondary organic aerosol (SOA) was investigated using liquid chromatography coupled with negative electrospray ionization mass spectrometry. The SOA was generated by the dark ozonolysis of α-pinene, extracted into the water, and subjected to chemical aging by the OH. Bimolecular reaction rate coefficients (kOH) for the oxidation of terpenoic acids by the OH were measured using the relative rate method. The unaged SOA was dominated by the cyclobutyl-ring-retaining compounds, primarily cis-pinonic, cis-pinic, and hydroxy-pinonic acids. Aqueous oxidation by the OH resulted in the removal of early-stage products and dimers, including well-known oligomers with MW = 358 and 368 Da. Furthermore, a 2- to 5-fold increase in the concentration of cyclobutyl-ring-opening products was observed, including terpenylic and diaterpenylic acids and diaterpenylic acid acetate as well as some of the newly identified OH aging markers. At the same time, results obtained from the kinetic box model showed a high degree of SOA fragmentation following the reaction with the OH, which indicates that non-radical reactions occurring during the evaporation of water likely contribute to the high yields of terpenoic aqSOAs reported previously. The estimated atmospheric lifetimes showed that in clouds, terpenoic acids react with the OH exclusively in the aqueous phase. Aqueous OH aging of the α-pinene SOA results in a 10% increase of the average O/C ratio and a 3-fold decrease in the average kOH value, which is likely to affect the cloud condensation nuclei activity of the aqSOA formed after the evaporation of water.
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3
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West CP, Mesa Sanchez D, Morales AC, Hsu YJ, Ryan J, Darmody A, Slipchenko LV, Laskin J, Laskin A. Molecular and Structural Characterization of Isomeric Compounds in Atmospheric Organic Aerosol Using Ion Mobility-Mass Spectrometry. J Phys Chem A 2023; 127:1656-1674. [PMID: 36763810 DOI: 10.1021/acs.jpca.2c06459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Secondary organic aerosol (SOA) formed through multiphase atmospheric chemistry makes up a large fraction of airborne particles. The chemical composition and molecular structures of SOA constituents vary between different emission sources and aging processes in the atmosphere, which complicates their identification. In this work, we employ drift tube ion mobility spectrometry with quadrupole time-of-flight mass spectrometry (IM-MS) detection for rapid gas-phase separation and multidimensional characterization of isomers in two biogenic SOAs produced from ozonolysis of isomeric monoterpenes, d-limonene (LSOA) and α-pinene (PSOA). SOA samples were ionized using electrospray ionization (ESI) and characterized using IM-MS in both positive and negative ionization modes. The IM-derived collision cross sections in nitrogen gas (DTCCSN2 ) for individual SOA components were obtained using multifield and single-field measurements. A novel application of IM multiplexing/high-resolution demultiplexing methodology was employed to increase sensitivity, improve peak shapes, and augment mobility baseline resolution, which revealed several isomeric structures for the measured ions. For LSOA and PSOA samples, we report significant structural differences of the isomer structures. Molecular structural calculations using density functional theory combined with the theoretical modeling of CCS values provide insights into the structural differences between LSOA and PSOA constituents. The average DTCCSN2 values for monomeric SOA components observed as [M + Na]+ ions are 3-6% higher than those of their [M - H]- counterparts. Meanwhile, dimeric and trimeric isomer components in both samples showed an inverse trend with the relevant values of [M - H]- ions being 3-7% higher than their [M + Na]+ counterparts, respectively. The results indicate that the structures of Na+-coordinated oligomeric ions are more compact than those of the corresponding deprotonated species. The coordination with Na+ occurs on the oxygen atoms of the carbonyl groups leading to a compact configuration. Meanwhile, deprotonated molecules have higher DTCCSN2 values due to their elongated structures in the gas phase. Therefore, DTCCSN2 values of isomers in SOA mixtures depend strongly on the mode of ionization in ESI. Additionally, PSOA monomers and dimers exhibit larger DTCCSN2 values (1-4%) than their LSOA counterparts owing to more rigid structures. A cyclobutane ring is present with functional groups pointing in opposite directions in PSOA compounds, as compared to noncyclic flexible LSOA structures, forming more compact ions in the gas phase. Lastly, we investigated the effects of direct photolysis on the chemical transformations of selected individual PSOA components. We use IM-MS to reveal structural changes associated with aerosol aging by photolysis. This study illustrates the detailed molecular and structural descriptors for the detection and annotation of structural isomers in complex SOA mixtures.
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Affiliation(s)
- Christopher P West
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Daniela Mesa Sanchez
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Ana C Morales
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Yun-Jung Hsu
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Jackson Ryan
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Andrew Darmody
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States.,Department of Aeronautics and Aerospace Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Lyudmila V Slipchenko
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Julia Laskin
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Alexander Laskin
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States.,Department of Earth, Atmospheric & Planetary Sciences, Purdue University, West Lafayette, Indiana 47907, United States
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4
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Liu S, Wang Y, Xu X, Wang G. Effects of NO 2 and RH on secondary organic aerosol formation and light absorption from OH oxidation of ο-xylene. CHEMOSPHERE 2022; 308:136541. [PMID: 36150487 DOI: 10.1016/j.chemosphere.2022.136541] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 09/13/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
Ο-xylene is an important aromatic volatile organic compound (VOC) in the atmosphere over urban areas. In this work, the effect of nitrogen dioxide (NO2) concentration and relative humidity (RH) on the mass concentration of secondary organic aerosols (SOA) formed from ο-xylene OH oxidization was investigated in a photooxidation chamber. The ο-xylene SOA mass concentration increased from 54.2 μg m-3 to 127.2 μg m-3 during dry conditions, but decreased from 177.7 μg m-3 to 146.5 μg m-3 during high RH conditions when the initial NO2 concentration increased form 0 ppbv to about 900 ppbv. An increase in the ratio of [NO3-]/[Org] and a decrease in the oxidation state of carbon (OSC) of SOA suggested that acid-catalyzed heterogeneous reaction was responsible for enhancing SOA formation with increasing NO2 concentrations in dry conditions. In contrast, in humid conditions, the high molecular diffusion capacity of SOA could promote the reactivity of OH towards the interior of SOA, and the enhancement of nitrous acid (HONO) formation under high NO2 conditions could promote the SOA aging processes and be responsible for the decreasing trend of SOA formation with NO2. Light absorption by SOA was also measured, and both NO2 and RH enhanced the mass absorption coefficient (MACλ = 365 nm) value for the optical properties of ο-xylene SOA. The highest MACλ = 365 nm value of ο-xylene SOA was 0.89 m2 g-1, observed during humid conditions with an initial NO2 concentration of 862 ppbv, which was 3.9 times higher than in the experiment conducted in the absence of NO2 under dry conditions. The formation of nitrogen-containing organic compounds (NOCs) and humic-like substances (HULIS) were responsible for the increased MACλ = 365 nm values of ο-xylene derived SOA. This study provides new insight into the effect of NO2 on SOA formation through the change in ο-xylene photooxidation under different RH conditions, and the complex effect of multiple environmental factors on SOA formation was also important and should not be ignored.
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Affiliation(s)
- Shijie Liu
- Key Lab of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 210062, China; Institute of Eco-Chongming, 3663 North Zhongshan Road, Shanghai, 200062, China
| | - Yiqian Wang
- Key Lab of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 210062, China
| | - Xinbei Xu
- Key Lab of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 210062, China
| | - Gehui Wang
- Key Lab of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 210062, China; Institute of Eco-Chongming, 3663 North Zhongshan Road, Shanghai, 200062, China.
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5
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Sunlight can convert atmospheric aerosols into a glassy solid state and modify their environmental impacts. Proc Natl Acad Sci U S A 2022; 119:e2208121119. [PMID: 36269861 PMCID: PMC9618061 DOI: 10.1073/pnas.2208121119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Secondary organic aerosol is well known to affect Earth's climate, regional weather, visibility, and public health. Once these aerosols are formed, they are transported throughout the atmosphere for days or even weeks. We show that exposure of secondary organic aerosols to UV solar radiation leads to a surprising and remarkable increase in viscosity by as much as five orders of magnitude. We also show that this UV exposure can lead to an increased abundance of aerosols that are in the glassy solid state in the troposphere, with important implications for climate predictions. Overall, our results clearly demonstrate that aging by exposure to solar radiation needs to be considered when predicting the environmental impacts of secondary organic aerosols. Secondary organic aerosol (SOA) plays a critical, yet uncertain, role in air quality and climate. Once formed, SOA is transported throughout the atmosphere and is exposed to solar UV light. Information on the viscosity of SOA, and how it may change with solar UV exposure, is needed to accurately predict air quality and climate. However, the effect of solar UV radiation on the viscosity of SOA and the associated implications for air quality and climate predictions is largely unknown. Here, we report the viscosity of SOA after exposure to UV radiation, equivalent to a UV exposure of 6 to 14 d at midlatitudes in summer. Surprisingly, UV-aging led to as much as five orders of magnitude increase in viscosity compared to unirradiated SOA. This increase in viscosity can be rationalized in part by an increase in molecular mass and oxidation of organic molecules constituting the SOA material, as determined by high-resolution mass spectrometry. We demonstrate that UV-aging can lead to an increased abundance of aerosols in the atmosphere in a glassy solid state. Therefore, UV-aging could represent an unrecognized source of nuclei for ice clouds in the atmosphere, with important implications for Earth’s energy budget. We also show that UV-aging increases the mixing times within SOA particles by up to five orders of magnitude throughout the troposphere with important implications for predicting the growth, evaporation, and size distribution of SOA, and hence, air pollution and climate.
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6
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Edwards KC, Klodt AL, Galeazzo T, Schervish M, Wei J, Fang T, Donahue NM, Aumont B, Nizkorodov SA, Shiraiwa M. Effects of Nitrogen Oxides on the Production of Reactive Oxygen Species and Environmentally Persistent Free Radicals from α-Pinene and Naphthalene Secondary Organic Aerosols. J Phys Chem A 2022; 126:7361-7372. [PMID: 36194388 PMCID: PMC9574922 DOI: 10.1021/acs.jpca.2c05532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reactive oxygen species (ROS) and environmentally persistent free radicals (EPFR) play an important role in chemical transformation of atmospheric aerosols and adverse aerosol health effects. This study investigated the effects of nitrogen oxides (NOx) during photooxidation of α-pinene and naphthalene on the EPFR content and ROS formation from secondary organic aerosols (SOA). Electron paramagnetic resonance (EPR) spectroscopy was applied to quantify EPFR content and ROS formation. While no EPFR were detected in α-pinene SOA, we found that naphthalene SOA contained about 0.7 pmol μg-1 of EPFR, and NOx has little influence on EPFR concentrations and oxidative potential. α-Pinene and naphthalene SOA generated under low NOx conditions form OH radicals and superoxide in the aqueous phase, which was lowered substantially by 50-80% for SOA generated under high NOx conditions. High-resolution mass spectrometry analysis showed the substantial formation of nitroaromatics and organic nitrates in a high NOx environment. The modeling results using the GECKO-A model that simulates explicit gas-phase chemistry and the radical 2D-VBS model that treats autoxidation predicted reduced formation of hydroperoxides and enhanced formation of organic nitrates under high NOx due to the reactions of peroxy radicals with NOx instead of their reactions with HO2. Consistently, the presence of NOx resulted in the decrease of peroxide contents and oxidative potential of α-pinene SOA.
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Affiliation(s)
- Kasey C Edwards
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Alexandra L Klodt
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Tommaso Galeazzo
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Meredith Schervish
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Jinlai Wei
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Ting Fang
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Neil M Donahue
- Departments of Chemistry, Chemical Engineering, Engineering and Public Policy, Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Bernard Aumont
- CNRS, LISA, Univ of Paris Est Creteil and University Paris Cité, F-94010 Créteil, France
| | - Sergey A Nizkorodov
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Manabu Shiraiwa
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
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7
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Deng H, Lakey PSJ, Wang Y, Li P, Xu J, Pang H, Liu J, Xu X, Li X, Wang X, Zhang Y, Shiraiwa M, Gligorovski S. Daytime SO 2 chemistry on ubiquitous urban surfaces as a source of organic sulfur compounds in ambient air. SCIENCE ADVANCES 2022; 8:eabq6830. [PMID: 36170374 PMCID: PMC9519037 DOI: 10.1126/sciadv.abq6830] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The reactions of sulfur dioxide (SO2) with surface-bound compounds on atmospheric aerosols lead to the formation of organic sulfur (OS) compounds, thereby affecting the air quality and climate. Here, we show that the heterogeneous reaction of SO2 with authentic urban grime under near-ultraviolet sunlight irradiation leads to a large suite of various organic compounds including OS released in the gas phase. Calculations indicate that at the core area of Guangzhou, building surface uptake of SO2 is 15 times larger than uptake of SO2 on aerosol surfaces, yielding ~20 ng m-3 of OS that represents an important fraction of the observed OS compounds (60 to 200 ng m-3) in ambient aerosols of Chinese megacities. This chemical pathway occurring during daytime can contribute to the observed fraction of OS compounds in aerosols and improve the understanding of haze formation and urban air pollution.
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Affiliation(s)
- Huifan Deng
- 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 510 640, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou 510640, China
- Chinese Academy of Science, Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Pascale S. J. Lakey
- Department of Chemistry, University of California, Irvine, Irvine, CA 92687-2025, USA
| | - Yiqun 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 510 640, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Pan Li
- 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 510 640, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jinli Xu
- 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 510 640, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Hongwei Pang
- 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 510 640, China
| | - Jiangping 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 510 640, China
| | - Xin Xu
- Institute of Mass Spectrometry and Atmospheric Environment, Jinan University, Guangzhou 510632, China
| | - Xue Li
- Institute of Mass Spectrometry and Atmospheric Environment, Jinan University, Guangzhou 510632, China
- Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Guangzhou 510632, China
- Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou 510632, 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 510 640, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou 510640, China
- Chinese Academy of Science, Center for Excellence in Deep Earth Science, Guangzhou 510640, China
| | - Yuzhong Zhang
- Key Laboratory of Coastal Environment and Resources of Zhejiang Province, School of Engineering, Westlake University, Hangzhou 310024, China
| | - Manabu Shiraiwa
- Department of Chemistry, University of California, Irvine, Irvine, CA 92687-2025, USA
| | - Sasho Gligorovski
- 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 510 640, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou 510640, China
- Chinese Academy of Science, Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- Corresponding author.
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8
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Leglise J, Müller M, Piel F, Otto T, Wisthaler A. Bulk Organic Aerosol Analysis by Proton-Transfer-Reaction Mass Spectrometry: An Improved Methodology for the Determination of Total Organic Mass, O:C and H:C Elemental Ratios, and the Average Molecular Formula. Anal Chem 2019; 91:12619-12624. [PMID: 31525909 DOI: 10.1021/acs.analchem.9b02949] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have recently shown in this journal (Müller et al. Anal. Chem. 2017 , 89 , 10889 - 10897 ) how a proton-transfer-reaction mass spectrometry (PTR-MS) analyzer measured particulate organic matter in urban atmospheres using the "Chemical Analysis of Aerosol Online" (CHARON) inlet. Our initial CHARON studies did not take into account fragmentation of protonated analyte molecules, which introduced a small but significant negative bias in the determination of bulk organic aerosol parameters. Herein, we studied the ionic fragmentation of 26 oxidized organic compounds typically found in atmospheric particles. This allowed us to derive a correction algorithm for the determination of the bulk organic mass concentration, mOA, the bulk-average hydrogen-to-carbon ratio, (H:C)bulk, the bulk-average oxygen-to-carbon ratio, (O:C)bulk, and the bulk-average molecular formula, MFbulk. The correction algorithm was validated against AMS data using two sets of published data. Finally, we determined MFbulk of particles generated from the reaction of α-pinene and ozone and compared and discussed the results in relation to the literature.
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Affiliation(s)
| | | | - Felix Piel
- IONICON Analytik GmbH , 6020 Innsbruck , Austria.,Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , 6020 Innsbruck , Austria
| | - Tobias Otto
- Atmospheric Chemistry Department (ACD) , Leibniz Institute for Tropospheric Research (TROPOS) , 04318 Leipzig , Germany
| | - Armin Wisthaler
- Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , 6020 Innsbruck , Austria.,Department of Chemistry , University of Oslo , 0315 Oslo , Norway
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9
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Ye Z, Qu Z, Ma S, Luo S, Chen Y, Chen H, Chen Y, Zhao Z, Chen M, Ge X. A comprehensive investigation of aqueous-phase photochemical oxidation of 4-ethylphenol. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 685:976-985. [PMID: 31390715 DOI: 10.1016/j.scitotenv.2019.06.276] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 06/11/2019] [Accepted: 06/18/2019] [Indexed: 06/10/2023]
Abstract
Secondary organic aerosol (SOA) species formed in atmospheric aqueous phases is recently recognized as an important contributor to fine aerosols, which is known to be a prominent human health risk factor internationally. This work, for the first time, systematically investigated aqueous-phase photochemical oxidation of 4-ethylphenol (4-EP) - a model compound from biomass burning and a surrogate of intermediate volatility organic compounds, under both ultraviolet (UV) (Hg lamp) and simulated sunlight (Xe lamp). We found that 4-EP could degrade upon hydroxal radical (OH) oxidation under UV light nearly 15 times faster than that under simulated sunlight, but large aqueous SOA (aqSOA) yields (108%-122%) were observed under both situations. AqSOA masses and oxidation states continuously increased under simulated sunlight, yet they increased first then decreased quickly under UV light. We proposed a reaction scheme based on identified products, showing that oligomerization, functionalization and fragmentation all can occur during 4-EP oxidation. Our results demonstrate that OH radical may suppress oligomerization and functionalization, but is favorable for fragmentation. Under UV light with H2O2 (high OH), fragmentation was dominant, producing more volatile and smaller molecules, and less aqSOA in later oxidation; Under simulated sunlight with H2O2 (moderate OH), functionalization that can form hydroxylated monomer was more important. Moreover, 4-EP oxidation by the organic triplet excited state (3C*) could form species with stronger visible light absorptivity than those from OH-mediated oxidation, and the absorptivity showed positive link with contents of humic-like substances.
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Affiliation(s)
- Zhaolian Ye
- College of Chemistry and Environmental Engineering, Jiangsu University of Technology, Changzhou 213001, China
| | - Zhenxiu Qu
- College of Chemistry and Environmental Engineering, Jiangsu University of Technology, Changzhou 213001, China
| | - Shuaishuai Ma
- College of Chemistry and Environmental Engineering, Jiangsu University of Technology, Changzhou 213001, China
| | - Shipeng Luo
- College of Chemistry and Environmental Engineering, Jiangsu University of Technology, Changzhou 213001, China
| | - Yantong Chen
- College of Chemistry and Environmental Engineering, Jiangsu University of Technology, Changzhou 213001, China
| | - Hui Chen
- Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Sciences and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Yanfang Chen
- Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Sciences and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Zhuzi Zhao
- College of Chemistry and Environmental Engineering, Jiangsu University of Technology, Changzhou 213001, China
| | - Mindong Chen
- Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Sciences and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Xinlei Ge
- Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Sciences and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China.
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10
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Liu S, Tsona NT, Zhang Q, Jia L, Xu Y, Du L. Influence of relative humidity on cyclohexene SOA formation from OH photooxidation. CHEMOSPHERE 2019; 231:478-486. [PMID: 31151007 DOI: 10.1016/j.chemosphere.2019.05.131] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 05/06/2019] [Accepted: 05/14/2019] [Indexed: 06/09/2023]
Abstract
Secondary organic aerosol (SOA) is a complex mixture consisting of a variety of oxidation products. In this study, the role of relative humidity (RH) on SOA formation with different [H2O2]0/[cyclohexene]0 was investigated in a smog chamber. It was found that the cyclohexene SOA yield increases with increasing initial OH concentration at both high and low RH conditions. The increased rate of SOA formation was lower at wet conditions than that at dry conditions. For [H2O2]0/[cyclohexene]0 = 0.4 and 0.8, the SOA yield increased from 1.5% to 8% at dry condition to 7% and 12% at wet condition, respectively. In contrast, at high RH the SOA yield fell from 54% to 52% for [H2O2]0/[cyclohexene]0 = 1.3. The SOA mass loss was higher at high RH at the same OH exposure. The chemical composition of SOA was characterized using hybrid quadrupole-orbitrap mass spectrometer equipped with electrospray ionization (ESI-Q-Orbitrap-HRMS). Oligomers, which were responsible for the increase of the SOA yield, were detected in the SOA formed at high RH conditions. The esterification reaction between dicarboxylic acids and HOC6H10-O-O-C6H10OH was the pathway of oligomers formation. All the oligomers have cyclic molecular structures. For [H2O2]0/[cyclohexene]0 = 1.3, the relative intensity of both low and high molecular weight substances reduced more at wet conditions. This indicates that at sufficient OH level, the inhibition of oligomers formation and the further reaction of SOA with OH result in a slightly lower SOA yield at wet condition.
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Affiliation(s)
- Shijie Liu
- Environment Research Institute, Shandong University, Qingdao, 266237, China
| | - Narcisse T Tsona
- School of Life Science, Shandong University, Qingdao, 266237, China
| | - Qun Zhang
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China
| | - Long Jia
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China
| | - Yongfu Xu
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China
| | - Lin Du
- Environment Research Institute, Shandong University, Qingdao, 266237, China.
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11
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Giorio C, Bortolini C, Kourtchev I, Tapparo A, Bogialli S, Kalberer M. Direct target and non-target analysis of urban aerosol sample extracts using atmospheric pressure photoionisation high-resolution mass spectrometry. CHEMOSPHERE 2019; 224:786-795. [PMID: 30851530 DOI: 10.1016/j.chemosphere.2019.02.151] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 02/21/2019] [Accepted: 02/22/2019] [Indexed: 06/09/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous atmospheric pollutants of high concern for public health. In the atmosphere they undergo oxidation, mainly through reactions with ·OH and NOx to produce nitro- and oxygenated (oxy-) derivatives. In this study, we developed a new method for the detection of particle-bound PAHs, nitro-PAHs and oxy-PAHs using direct infusion into an atmospheric pressure photoionisation high-resolution mass spectrometer (APPI-HRMS). Method optimisation was done by testing different source temperatures, gas flow rates, mobile phases and dopants. Samples were extracted with methanol, concentrated by evaporation and directly infused in the APPI source after adding toluene as dopant. Acquisition was performed in both polarity modes. The method was applied to target analysis of seasonal PM2.5 samples from an urban background site in Padua (Italy), in the Po Valley, in which a series of PAHs, nitro- and oxy-PAHs were detected. APPI-HRMS was then used for non-target analysis of seasonal PM2.5 samples and results compared with nano-electrospray ionisation (nanoESI) HRMS. The results showed that, when samples were characterised by highly oxidised organic compounds, including S-containing compounds, like in summer samples, APPI did not bring any additional information with respect to nanoESI in negative polarity (nanoESI(-)). Conversely, for winter samples, APPI(-) could detect a series of aromatic and poly-aromatic compounds, mainly oxidised and nitrogenated aromatics, that were not otherwise detected with nanoESI.
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Affiliation(s)
- Chiara Giorio
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom; Department of Chemical Sciences, University of Padua, Via Marzolo 1, Padova, 35131, Italy.
| | - Claudio Bortolini
- Department of Chemical Sciences, University of Padua, Via Marzolo 1, Padova, 35131, Italy
| | - Ivan Kourtchev
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom
| | - Andrea Tapparo
- Department of Chemical Sciences, University of Padua, Via Marzolo 1, Padova, 35131, Italy
| | - Sara Bogialli
- Department of Chemical Sciences, University of Padua, Via Marzolo 1, Padova, 35131, Italy
| | - Markus Kalberer
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom; Department of Environmental Sciences, University of Basel, Klingelbergstrasse 27, 4056, Basel, Switzerland
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12
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An omnipresent diversity and variability in the chemical composition of atmospheric functionalized organic aerosol. Commun Chem 2018. [DOI: 10.1038/s42004-018-0074-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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13
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JIANG HX, LI J, TANG J, MO YZ, ZHANG G. Applications of High-Resolution Mass Spectrometry in Studies of Brown Carbon. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2018. [DOI: 10.1016/s1872-2040(18)61115-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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14
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Li Y, Zhang H, Zhao Z, Tian Y, Liu K, Jie F, Zhu L, Chen H. Mass spectral chemical fingerprints reveal the molecular dependence of exhaust particulate matters on engine speeds. J Environ Sci (China) 2018; 67:287-293. [PMID: 29778162 DOI: 10.1016/j.jes.2017.09.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Revised: 09/09/2017] [Accepted: 09/13/2017] [Indexed: 06/08/2023]
Abstract
Particulate matters (PMs) emitted by automobile exhaust contribute to a significant fraction of the global PMs. Extractive atmospheric pressure chemical ionization mass spectrometry (EAPCI-MS) was developed to explore the molecular dependence of PMs collected from exhaust gases produced at different vehicle engine speeds. The mass spectral fingerprints of the organic compounds embedded in differentially sized PMs (e.g., 0.22-0.45, 0.45-1.00, 1.00-2.00, 2.00-3.00, 3.00-5.00, and 5.00-10.00μm) generated at different engine speeds (e.g., 1000, 1500, 2000, 2500, and 3000r/min) were chemically profiled in the mass range of mass to charge ratio (m/z) 50-800. Organic compounds, including alcohols, aldehydes, and esters, were detected in all the PMs tested, with varied concentration levels for each individual PM sample. At relatively low engine speeds (≤1500r/min), the total amount of organic species embedded in PMs of 0.22-1.00μm was greater than in PMs of other sizes, while more organic species were found in PMs of 5.00-10.00μm at high engine speeds (≥3000r/min), indicating that the organic compounds distributed in different sizes of PMs strongly correlated with the engine speed. The experimental data showed that the EAPCI-MS technique enables molecular characterization of PMs in exhaust, revealing the chemical dependence of PMs on the engine speeds (i.e., the combustion conditions) of automobiles.
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Affiliation(s)
- Yi Li
- Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation, East China University of Technology, Nanchang 330013, China
| | - Hua Zhang
- Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation, East China University of Technology, Nanchang 330013, China
| | - Zongshan Zhao
- CAS Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Yong Tian
- CAS Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China.
| | - Kun Liu
- Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation, East China University of Technology, Nanchang 330013, China
| | - Feifan Jie
- Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation, East China University of Technology, Nanchang 330013, China
| | - Liang Zhu
- Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation, East China University of Technology, Nanchang 330013, China
| | - Huanwen Chen
- Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation, East China University of Technology, Nanchang 330013, China.
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15
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Affiliation(s)
- Julia Laskin
- Department of Chemistry, Purdue University , West Lafayette, Indiana 47907, United States
| | - Alexander Laskin
- Department of Chemistry, Purdue University , West Lafayette, Indiana 47907, United States
| | - Sergey A Nizkorodov
- Department of Chemistry, University of California , Irvine, California 92697, United States
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16
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Romonosky DE, Li Y, Shiraiwa M, Laskin A, Laskin J, Nizkorodov SA. Aqueous Photochemistry of Secondary Organic Aerosol of α-Pinene and α-Humulene Oxidized with Ozone, Hydroxyl Radical, and Nitrate Radical. J Phys Chem A 2017; 121:1298-1309. [DOI: 10.1021/acs.jpca.6b10900] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Dian E. Romonosky
- Department
of Chemistry, University of California, Irvine, California 92697, United States
| | - Ying Li
- National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan
| | - Manabu Shiraiwa
- Department
of Chemistry, University of California, Irvine, California 92697, United States
| | | | | | - Sergey A. Nizkorodov
- Department
of Chemistry, University of California, Irvine, California 92697, United States
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17
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Malecha KT, Nizkorodov SA. Photodegradation of Secondary Organic Aerosol Particles as a Source of Small, Oxygenated Volatile Organic Compounds. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:9990-7. [PMID: 27547987 DOI: 10.1021/acs.est.6b02313] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We investigated the photodegradation of secondary organic aerosol (SOA) particles by near-UV radiation and photoproduction of oxygenated volatile organic compounds (OVOCs) from various types of SOA. We used a smog chamber to generate SOA from α-pinene, guaiacol, isoprene, tetradecane, and 1,3,5-trimethylbenzene under high-NOx, low-NOx, or ozone oxidation conditions. The SOA particles were collected on a substrate, and the resulting material was exposed to several mW of near-UV radiation (λ ∼ 300 nm) from a light-emitting diode. Various OVOCs, including acetic acid, formic acid, acetaldehyde, and acetone were observed during photodegradation, and their SOA-mass-normalized fluxes were estimated with a Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS). All the SOA, with the exception of guaiacol SOA, emitted OVOCs upon irradiation. Based on the measured OVOC emission rates, we estimate that SOA particles would lose at least ∼1% of their mass over a 24 h period during summertime conditions in Los Angeles, California. This condensed-phase photochemical process may produce a few Tg/year of gaseous formic acid, the amount comparable to its primary sources. The condensed-phase SOA photodegradation processes could therefore measurably affect the budgets of both particulate and gaseous atmospheric organic compounds on a global scale.
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Affiliation(s)
- Kurtis T Malecha
- Department of Chemistry, University of California , Irvine, California 92697, United States
| | - Sergey A Nizkorodov
- Department of Chemistry, University of California , Irvine, California 92697, United States
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18
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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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19
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Hinks ML, Brady MV, Lignell H, Song M, Grayson JW, Bertram AK, Lin P, Laskin A, Laskin J, Nizkorodov SA. Effect of viscosity on photodegradation rates in complex secondary organic aerosol materials. Phys Chem Chem Phys 2016; 18:8785-93. [DOI: 10.1039/c5cp05226b] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
This work explores the effect of environmental conditions on the photodegradation rates of atmospherically relevant, photolabile, organic molecules embedded in a film of viscous secondary organic material (SOM).
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Affiliation(s)
| | | | - Hanna Lignell
- Department of Chemistry
- University of California
- Irvine
- USA
| | - Mijung Song
- Department of Chemistry
- University of British Columbia
- Vancouver
- Canada
| | - James W. Grayson
- Department of Chemistry
- University of British Columbia
- Vancouver
- Canada
| | - Allan K. Bertram
- Department of Chemistry
- University of British Columbia
- Vancouver
- Canada
| | - Peng Lin
- Environmental Molecular Sciences Laboratory
- Pacific Northwest National Laboratory
- Richland
- USA
| | - Alexander Laskin
- Environmental Molecular Sciences Laboratory
- Pacific Northwest National Laboratory
- Richland
- USA
| | - Julia Laskin
- Physical Sciences Division
- Pacific Northwest National Laboratory
- Richland
- USA
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20
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Rohr A, McDonald J. Health effects of carbon-containing particulate matter: focus on sources and recent research program results. Crit Rev Toxicol 2015; 46:97-137. [PMID: 26635181 DOI: 10.3109/10408444.2015.1107024] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Air pollution is a complex mixture of gas-, vapor-, and particulate-phase materials comprised of inorganic and organic species. Many of these components have been associated with adverse health effects in epidemiological and toxicological studies, including a broad spectrum of carbonaceous atmospheric components. This paper reviews recent literature on the health impacts of organic aerosols, with a focus on specific sources of organic material; it is not intended to be a comprehensive review of all the available literature. Specific emission sources reviewed include engine emissions, wood/biomass combustion emissions, biogenic emissions and secondary organic aerosol (SOA), resuspended road dust, tire and brake wear, and cooking emissions. In addition, recent findings from large toxicological and epidemiological research programs are reviewed in the context of organic PM, including SPHERES, NPACT, NERC, ACES, and TERESA. A review of the extant literature suggests that there are clear health impacts from emissions containing carbon-containing PM, but difficulty remains in apportioning responses to certain groupings of carbonaceous materials, such as organic and elemental carbon, condensed and gas phases, and primary and secondary material. More focused epidemiological and toxicological studies, including increased characterization of organic materials, would increase understanding of this issue.
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Affiliation(s)
- Annette Rohr
- a Electric Power Research Institute , Palo Alto , CA , USA
| | - Jacob McDonald
- b Lovelace Respiratory Research Institute , Albuquerque , NM , USA
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21
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Affiliation(s)
| | | | - Sergey A. Nizkorodov
- Department
of Chemistry, University of California, Irvine, Irvine, California 92697, United States
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