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21 results on '"Slowik A."'

2. Real-Time Source Apportionment of Organic Aerosols in Three European Cities

Author

Chen, Gang, Canonaco, Francesco, Slowik, Jay G., Daellenbach, Kaspar R., Tobler, Anna, Petit, Jean-Eudes, Favez, Olivier, Stavroulas, Iasonas, Mihalopoulos, Nikolaos, Gerasopoulos, Evangelos, El Haddad, Imad, Baltensperger, Urs, and Prévôt, André S. H.

Subjects
Aerosols, Air Pollutants, Source apportionment, General Chemistry, SoFi RT, Air Pollution, Humans, Environmental Chemistry, Particulate Matter, Real-time, organic aerosol, urban pollution, Cities, Environmental Sciences, Environmental Monitoring
Abstract

97% of the urban population in the EU in 2019 were exposed to an annual fine particulate matter level higher than the World Health Organization (WHO) guidelines (5 μg/m3). Organic aerosol (OA) is one of the major air pollutants, and the knowledge of its sources is crucial for designing cost-effective mitigation strategies. Positive matrix factorization (PMF) on aerosol mass spectrometer (AMS) or aerosol chemical speciation monitor (ACSM) data is the most common method for source apportionment (SA) analysis on ambient OA. However, conventional PMF requires extensive human labor, preventing the implementation of SA for routine monitoring applications. This study proposes the source finder real-time (SoFi RT, Datalystica Ltd.) approach for efficient retrieval of OA sources. The results generated by SoFi RT agree remarkably well with the conventional rolling PMF results regarding factor profiles, time series, diurnal patterns, and yearly relative contributions of OA factor on three year-long ACSM data sets collected in Athens, Paris, and Zurich. Although the initialization of SoFi RT requires a priori knowledge of OA sources (i.e., the approximate number of factors and relevant factor profiles) for the sampling site, this technique minimizes user interactions. Eventually, it could provide up-to-date trustable information on timescales useful to policymakers and air quality modelers., Environmental Science & Technology, 56 (22), ISSN:0013-936X, ISSN:1520-5851

Published
2022
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4. Critical Role of Simultaneous Reduction of Atmospheric Odd Oxygen for Winter Haze Mitigation

Author

Yuanhang Zhang, Xin Sun, Jay G. Slowik, Qiao Zhu, Qiao-Li Zou, Kaspar R. Daellenbach, Ling-Yan He, Li-Ming Cao, Keding Lu, André S. H. Prévôt, Yong Cheng, Ye-Min Shen, Li-Liang Lin, Eri Saikawa, Xiao-Feng Huang, Nga L. Ng, Bing-Ye Xu, Min Hu, Lan Jiang, Xu-Dong Tian, Yuhan Liu, and Qian Tang

Subjects
China, Haze, Ozone, Coronavirus disease 2019 (COVID-19), Air pollution, chemistry.chemical_element, medicine.disease_cause, Atmospheric sciences, Oxygen, chemistry.chemical_compound, Air Pollution, medicine, Humans, Environmental Chemistry, Volatile organic compound, Aerosols, chemistry.chemical_classification, Air Pollutants, SARS-CoV-2, COVID-19, General Chemistry, Particulates, Aerosol, chemistry, Communicable Disease Control, Environmental science, Particulate Matter, Environmental Monitoring
Abstract

The lockdown due to COVID-19 created a rare opportunity to examine the nonlinear responses of secondary aerosols, which are formed through atmospheric oxidation of gaseous precursors, to intensive precursor emission reductions. Based on unique observational data sets from six supersites in eastern China during 2019-2021, we found that the lockdown caused considerable decreases (32-61%) in different secondary aerosol components in the study region because of similar-degree precursor reductions. However, due to insufficient combustion-related volatile organic compound (VOC) reduction, odd oxygen (Ox = O3 + NO2) concentration, an indicator of the extent of photochemical processing, showed little change and did not promote more decreases in secondary aerosols. We also found that the Chinese provinces and international cities that experienced reduced Ox during the lockdown usually gained a greater simultaneous PM2.5 decrease than other provinces and cities with an increased Ox. Therefore, we argue that strict VOC control in winter, which has been largely ignored so far, is critical in future policies to mitigate winter haze more efficiently by reducing Ox simultaneously.

Published
2021
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5. Time-Resolved Molecular Characterization of Secondary Organic Aerosol Formed from OH and NO3Radical Initiated Oxidation of a Mixture of Aromatic Precursors

Author

Kumar, Varun, Slowik, Jay G., Baltensperger, Urs, Prevot, Andre S. H., and Bell, David M.

Abstract

Aromatic hydrocarbons (ArHCs) and oxygenated aromatic hydrocarbons (ArHC–OHs) are emitted from a variety of anthropogenic activities and are important precursors of secondary organic aerosol (SOA) in urban areas. Here, we analyzed and compared the composition of SOA formed from the oxidation of a mixture of aromatic VOCs by OH and NO3radicals. The VOC mixture was composed of toluene (C7H8), p-xylene + ethylbenzene (C8H10), 1,3,5-trimethylbenzene (C9H12), phenol (C6H6O), cresol (C7H8O), 2,6-dimethylphenol (C8H10O), and 2,4,6-trimethylphenol (C9H12O) in a proportion where the aromatic VOCs were chosen to approximate day-time traffic-related emissions in Delhi, and the aromatic alcohols make up 20% of the mixture. These VOCs are prominent in other cities as well, including those influenced by biomass combustion. In the NO3experiments, large contributions from CxHyOzN dimers (C15–C18) were observed, corresponding to fast SOA formation within 15–20 min after the start of chemistry. Additionally, the dimers were a mixture of different combinations of the initial VOCs, highlighting the importance of exploring SOAs from mixed VOC systems. In contrast, the experiments with OH radicals yielded gradual SOA mass formation, with CxHyOzmonomers (C6–C9) being the dominant constituents. The evolution of SOA composition with time was tracked and a fast degradation of dimers was observed in the NO3experiments, with concurrent formation of monomer species. The rates of dimer decomposition in NO3SOA were ∼2–3 times higher compared to those previously determined for α-pinene + O3SOA, highlighting the dependence of particle-phase reactions on VOC precursors and oxidants. In contrast, the SOA produced in the OH experiments did not dramatically change over the same time frame. No measurable effects of humidity were observed on the composition and evolution of SOA.

Published
2023
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6. Critical Role of Simultaneous Reduction of Atmospheric Odd Oxygen for Winter Haze Mitigation

Author

Huang, Xiao-Feng, primary, Cao, Li-Ming, additional, Tian, Xu-Dong, additional, Zhu, Qiao, additional, Saikawa, Eri, additional, Lin, Li-Liang, additional, Cheng, Yong, additional, He, Ling-Yan, additional, Hu, Min, additional, Zhang, Yuan-Hang, additional, Lu, Ke-Ding, additional, Liu, Yu-Han, additional, Daellenbach, Kaspar, additional, Slowik, Jay G., additional, Tang, Qian, additional, Zou, Qiao-Li, additional, Sun, Xin, additional, Xu, Bing-Ye, additional, Jiang, Lan, additional, Shen, Ye-Min, additional, Ng, Nga Lee, additional, and Prévôt, André S. H., additional

Published
2021
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7. Photodegradation of α-Pinene Secondary Organic Aerosol Dominated by Moderately Oxidized Molecules

Author

Pospisilova, Veronika, primary, Bell, David M., additional, Lamkaddam, Houssni, additional, Bertrand, Amelie, additional, Wang, Liwei, additional, Bhattu, Deepika, additional, Zhou, Xueqin, additional, Dommen, Josef, additional, Prevot, Andre S.H., additional, Baltensperger, Urs, additional, El Haddad, Imad, additional, and Slowik, Jay G., additional

Published
2021
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8. Brown Carbon in Primary and Aged Coal Combustion Emission

Author

Ni, Haiyan, primary, Huang, Ru-Jin, additional, Pieber, Simone M., additional, Corbin, Joel C., additional, Stefenelli, Giulia, additional, Pospisilova, Veronika, additional, Klein, Felix, additional, Gysel-Beer, Martin, additional, Yang, Lu, additional, Baltensperger, Urs, additional, Haddad, Imad El, additional, Slowik, Jay G., additional, Cao, Junji, additional, Prévôt, André S. H., additional, and Dusek, Ulrike, additional

Published
2021
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9. Online Aerosol Chemical Characterization by Extractive Electrospray Ionization–Ultrahigh-Resolution Mass Spectrometry (EESI-Orbitrap)

Author

Lee, Chuan Ping, primary, Riva, Matthieu, additional, Wang, Dongyu, additional, Tomaz, Sophie, additional, Li, Dandan, additional, Perrier, Sebastien, additional, Slowik, Jay G., additional, Bourgain, Frederic, additional, Schmale, Julia, additional, Prevot, Andre S. H., additional, Baltensperger, Urs, additional, George, Christian, additional, and El Haddad, Imad, additional

Published
2020
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10. Inorganic Salt Interference on CO2+ in Aerodyne AMS and ACSM Organic Aerosol Composition Studies

Author

Branka Miljevic, John T. Jayne, Imad El Haddad, Jay G. Slowik, Felix Klein, Manjula R. Canagaratna, André S. H. Prévôt, Carlo Bozzetti, Jose L. Jimenez, Urs Baltensperger, Athanasia Vlachou, Kaspar R. Daellenbach, Josef Dommen, Roman Fröhlich, Simone M. Pieber, Douglas R. Worsnop, and Stephen Matthew Platt

Subjects
chemistry.chemical_classification, Ammonium sulfate, 010504 meteorology & atmospheric sciences, Ammonium nitrate, Thermal decomposition, Analytical chemistry, Salt (chemistry), General Chemistry, 010501 environmental sciences, Mass spectrometry, 01 natural sciences, Aerosol, chemistry.chemical_compound, Nitrate, chemistry, 13. Climate action, Mass spectrum, Environmental Chemistry, 0105 earth and related environmental sciences
Abstract

Aerodyne aerosol mass spectrometer (AMS) and Aerodyne aerosol chemical speciation monitor (ACSM) mass spectra are widely used to quantify organic aerosol (OA) elemental composition, oxidation state, and major environmental sources. The OA CO2+ fragment is among the most important measurements for such analyses. Here, we show that a non-OA CO2+ signal can arise from reactions on the particle vaporizer, ion chamber, or both, induced by thermal decomposition products of inorganic salts. In our tests (eight instruments, n = 29), ammonium nitrate (NH4NO3) causes a median CO2+ interference signal of +3.4% relative to nitrate. This interference is highly variable between instruments and with measurement history (percentiles P10–90 = +0.4 to +10.2%). Other semi-refractory nitrate salts showed 2–10 times enhanced interference compared to that of NH4NO3, while the ammonium sulfate ((NH4)2SO4) induced interference was 3–10 times lower. Propagation of the CO2+ interference to other ions during standard AMS and ACSM d...

Published
2016
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12. Effect of Stove Technology and Combustion Conditions on Gas and Particulate Emissions from Residential Biomass Combustion

Author

Bhattu, Deepika, primary, Zotter, Peter, additional, Zhou, Jun, additional, Stefenelli, Giulia, additional, Klein, Felix, additional, Bertrand, Amelie, additional, Temime-Roussel, Brice, additional, Marchand, Nicolas, additional, Slowik, Jay G., additional, Baltensperger, Urs, additional, Prévôt, André Stephan Henry, additional, Nussbaumer, Thomas, additional, El Haddad, Imad, additional, and Dommen, Josef, additional

Published
2019
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13. Characterization of Gas-Phase Organics Using Proton Transfer Reaction Time-of-Flight Mass Spectrometry: Residential Coal Combustion

Author

Klein, Felix, primary, Pieber, Simone M., additional, Ni, Haiyan, additional, Stefenelli, Giulia, additional, Bertrand, Amelie, additional, Kilic, Dogushan, additional, Pospisilova, Veronika, additional, Temime-Roussel, Brice, additional, Marchand, Nicolas, additional, El Haddad, Imad, additional, Slowik, Jay G., additional, Baltensperger, Urs, additional, Cao, Junji, additional, Huang, Ru-jin, additional, and Prévôt, André S. H., additional

Published
2018
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14. Characterization of Gas-Phase Organics Using Proton Transfer Reaction Time-of-Flight Mass Spectrometry: Aircraft Turbine Engines

Author

Kilic, Dogushan, primary, Brem, Benjamin T., additional, Klein, Felix, additional, El-Haddad, Imad, additional, Durdina, Lukas, additional, Rindlisbacher, Theo, additional, Setyan, Ari, additional, Huang, Rujin, additional, Wang, Jing, additional, Slowik, Jay G., additional, Baltensperger, Urs, additional, and Prevot, Andre S. H., additional

Published
2017
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15. Correction to Size-resolved Identification, Characterization and Quantification of Primary Biological Organic Aerosol at a European Rural Site

Author

Bozzetti, Carlo, primary, Daellenbach, Kaspar R., additional, Hueglin, Christoph, additional, Fermo, Paola, additional, Sciare, Jean, additional, Kasper-Giebl, Anneliese, additional, Mazar, Yinon, additional, Abbaszade, Gülcin, additional, Kazzi, Mario El, additional, Gonzalez, Raquel, additional, Shuster-Meiseles, Timor, additional, Flasch, Mira, additional, Wolf, Robert, additional, Křepelová, Adéla, additional, Canonaco, Francesco, additional, Schnelle-Kreis, Jurgen, additional, Slowik, Jay G., additional, Zimmermann, Ralf, additional, Rudich, Yinon, additional, Baltensperger, Urs, additional, Haddad, Imad El, additional, and Prévôt, André S. H., additional

Published
2016
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16. Inorganic Salt Interference on CO2+ in Aerodyne AMS and ACSM Organic Aerosol Composition Studies

Author

Pieber, Simone M., primary, El Haddad, Imad, additional, Slowik, Jay G., additional, Canagaratna, Manjula R., additional, Jayne, John T., additional, Platt, Stephen M., additional, Bozzetti, Carlo, additional, Daellenbach, Kaspar R., additional, Fröhlich, Roman, additional, Vlachou, Athanasia, additional, Klein, Felix, additional, Dommen, Josef, additional, Miljevic, Branka, additional, Jiménez, José L., additional, Worsnop, Douglas R., additional, Baltensperger, Urs, additional, and Prévôt, André S. H., additional

Published
2016
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17. Size-Resolved Identification, Characterization, and Quantification of Primary Biological Organic Aerosol at a European Rural Site

Author

Bozzetti, Carlo, primary, Daellenbach, Kaspar R., additional, Hueglin, Christoph, additional, Fermo, Paola, additional, Sciare, Jean, additional, Kasper-Giebl, Anneliese, additional, Mazar, Yinon, additional, Abbaszade, Gülcin, additional, El Kazzi, Mario, additional, Gonzalez, Raquel, additional, Shuster-Meiseles, Timor, additional, Flasch, Mira, additional, Wolf, Robert, additional, Křepelová, Adéla, additional, Canonaco, Francesco, additional, Schnelle-Kreis, Jürgen, additional, Slowik, Jay G., additional, Zimmermann, Ralf, additional, Rudich, Yinon, additional, Baltensperger, Urs, additional, El Haddad, Imad, additional, and Prévôt, André S. H., additional

Published
2016
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18. Characterization of Gas-Phase Organics Using Proton Transfer Reaction Time-of-Flight Mass Spectrometry: Cooking Emissions

Author

Klein, Felix, primary, Platt, Stephen M., additional, Farren, Naomi J., additional, Detournay, Anais, additional, Bruns, Emily A., additional, Bozzetti, Carlo, additional, Daellenbach, Kaspar R., additional, Kilic, Dogushan, additional, Kumar, Nivedita K., additional, Pieber, Simone M., additional, Slowik, Jay G., additional, Temime-Roussel, Brice, additional, Marchand, Nicolas, additional, Hamilton, Jacqueline F., additional, Baltensperger, Urs, additional, Prévôt, André S. H., additional, and El Haddad, Imad, additional

Published
2016
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21. Photodegradation of α-Pinene Secondary Organic Aerosol Dominated by Moderately Oxidized Molecules

Author

Xueqin Zhou, Liwei Wang, Jay G. Slowik, Josef Dommen, Houssni Lamkaddam, Imad El Haddad, André S. H. Prévôt, Urs Baltensperger, Deepika Bhattu, Amelie Bertrand, Veronika Pospisilova, and David M. Bell

Subjects
Aerosols, Air Pollutants, Photolysis, Chemistry, Photodissociation, General Chemistry, 010501 environmental sciences, Photochemistry, Mass spectrometry, 01 natural sciences, Aerosol, 13. Climate action, Monoterpenes, Environmental Chemistry, Molecule, Relative humidity, Photodegradation, Chemical composition, Volatility (chemistry), Bicyclic Monoterpenes, 0105 earth and related environmental sciences
Abstract

Atmospheric secondary organic aerosol (SOA) undergoes chemical and physical changes when exposed to UV radiation, affecting the atmospheric lifetime of the involved molecules. However, these photolytic processes remain poorly constrained. Here, we present a study aimed at characterizing, at a molecular level and in real time, the chemical composition of α-pinene SOA exposed to UV-A light at 50% relative humidity in an atmospheric simulation chamber. Significant SOA mass loss is observed at high loadings (∼100 μg m-3), whereas the effect is less prevalent at lower loadings (∼20 μg m-3). For the vast majority of molecules measured by the extractive electrospray time-of-flight mass spectrometer, there is a fraction that is photoactive and decays when exposed to UV-A radiation and a fraction that appears photorecalcitrant. The molecules that are most photoactive contain between 4 and 6 oxygen atoms, while the more highly oxygenated compounds and dimers do not exhibit significant decay. Overall, photolysis results in a reduction of the volatility of SOA, which cannot be explained by simple evaporative losses but requires either a change in volatility related to changes in functional groups or a change in physical parameters (i.e., viscosity).

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