128 results on '"William C. Kuster"'
Search Results
2. Measurements of Total OH Reactivity During CalNex‐LA
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James Flynn, Carsten Warneke, Barry Lefer, Jessica B. Gilman, Stephen M. Griffith, Cora J. Young, Philip S. Stevens, Sebastien Dusanter, Steven S. Brown, Sergio Alvarez, Rebecca A. Washenfelder, J. A. de Gouw, Martin Graus, William C. Kuster, R. F. Hansen, N. Grossberg, B. Rappenglueck, Patrick R. Veres, Ecole nationale supérieure Mines-Télécom Lille Douai (IMT Nord Europe), and Institut Mines-Télécom [Paris] (IMT)
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Atmospheric Science ,010504 meteorology & atmospheric sciences ,010501 environmental sciences ,01 natural sciences ,Medicinal chemistry ,chemistry.chemical_compound ,Geophysics ,chemistry ,Space and Planetary Science ,[SDE]Environmental Sciences ,Earth and Planetary Sciences (miscellaneous) ,Environmental science ,Reactivity (chemistry) ,Hydroxyl radical ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences - Abstract
International audience
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- 2021
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3. Supplementary material to 'Anthropogenic Secondary Organic Aerosols Contribute Substantially to Air Pollution Mortality'
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Benjamin A. Nault, Duseong S. Jo, Brian C. McDonald, Pedro Campuzano-Jost, Douglas A. Day, Weiwei Hu, Jason C. Schroder, James Allan, Donald R. Blake, Manjula R. Canagaratna, Hugh Coe, Matthew M. Coggon, Peter F. DeCarlo, Glenn S. Diskin, Rachel Dunmore, Frank Flocke, Alan Fried, Jessica B. Gilman, Georgios Gkatzelis, Jacqui F. Hamilton, Thomas F. Hanisco, Patrick L. Hayes, Daven K. Henze, Alma Hodzic, James Hopkins, Min Hu, L. Greggory Huey, B. Thomas Jobson, William C. Kuster, Alastair Lewis, Meng Li, Jin Liao, M. Omar Nawaz, Ilana B. Pollack, Jeffrey Peischl, Bernhard Rappenglück, Claire E. Reeves, Dirk Richter, James M. Roberts, Thomas B. Ryerson, Min Shao, Jacob M. Sommers, James Walega, Carsten Warneke, Petter Weibring, Glenn M. Wolfe, Dominique E. Young, Bin Yuan, Qiang Zhang, Joost A. de Gouw, and Jose L. Jimenez
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- 2020
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4. Anthropogenic Secondary Organic Aerosols Contribute Substantially to Air Pollution Mortality
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M. Omar Nawaz, Jose L. Jimenez, Pedro Campuzano-Jost, Joost A. de Gouw, Alan Fried, Peter F. DeCarlo, Alma Hodzic, Dominique E. Young, Carsten Warneke, L. Greggory Huey, Jin Liao, Alastair C. Lewis, Jessica B. Gilman, Min Hu, Jacob M. Sommers, Bernhard Rappenglück, Hugh Coe, Min Shao, Dirk Richter, William C. Kuster, Manjula R. Canagaratna, Claire E. Reeves, Rachel Dunmore, Matthew M. Coggon, J. F. Hamilton, Glenn M. Wolfe, Donald R. Blake, Qiang Zhang, Patrick L. Hayes, Georgios I. Gkatzelis, Thomas B. Ryerson, James R. Hopkins, James M. Roberts, Ilana B. Pollack, Frank Flocke, James Allan, Weiwei Hu, B. Thomas Jobson, Jason C. Schroder, Duseong S. Jo, Bin Yuan, Daven K. Henze, Brian C. McDonald, Glenn S. Diskin, Meng Li, Douglas A. Day, Jeff Peischl, James Walega, Benjamin A. Nault, Petter Weibring, and Thomas F. Hanisco
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South asia ,010504 meteorology & atmospheric sciences ,Mortality model ,Secondary organic aerosols ,Air pollution ,Detailed data ,010501 environmental sciences ,Health benefits ,medicine.disease_cause ,01 natural sciences ,Aerosol ,chemistry.chemical_compound ,chemistry ,13. Climate action ,Environmental protection ,11. Sustainability ,medicine ,Environmental science ,Air quality index ,0105 earth and related environmental sciences - Abstract
Anthropogenic secondary organic aerosol (ASOA), formed from anthropogenic emissions of organic compounds, constitutes a substantial fraction of the mass of submicron aerosol in populated areas around the world and contributes to poor air quality and premature mortality. However, the precursor sources of ASOA are poorly understood, and there are large uncertainties in the health benefits that might accrue from reducing anthropogenic organic emissions. We show that the production of ASOA in 11 urban areas on three continents is strongly correlated with the anthropogenic reactivity of specific volatile organic compounds. The differences in ASOA production across different cities can be explained by differences in the emissions of aromatics and intermediate- and semi-volatile organic compounds, indicating the importance of controlling these ASOA precursors. With an improved modeling representation of ASOA driven by the observations, we attribute 340,000 PM2.5 premature deaths per year to ASOA, which is over an order of magnitude higher than prior studies. A sensitivity case with a more recently proposed model for attributing mortality to PM2.5 (the Global Exposure Mortality Model) results up to 900,000 deaths. A limitation of this study is the extrapolation from regions with detailed data to others where data is not available. Comprehensive air quality campaigns in the countries in South and Central America, Africa, South Asia, and the Middle East are needed for further progress in this area.
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- 2020
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5. An improved, automated whole air sampler and gas chromatography mass spectrometry analysis system for volatile organic compounds in the atmosphere
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Bin Yuan, Elliot Atlas, Joost A. de Gouw, Kenneth C. Aikin, Jeff Peischl, Brian M. Lerner, Carsten Warneke, Donna Sueper, Gabriel Isaacman-VanWertz, Richard J. McLaughlin, R. Lueb, Martin Graus, Thomas B. Ryerson, T. W. Tokarek, William C. Kuster, Jessica B. Gilman, Paul D. Goldan, R. Hendershot, and Abigail R. Koss
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Atmospheric Science ,Stirling engine ,Chromatography ,010504 meteorology & atmospheric sciences ,lcsh:TA715-787 ,business.industry ,lcsh:Earthwork. Foundations ,Mixing (process engineering) ,010501 environmental sciences ,Mass spectrometry ,01 natural sciences ,lcsh:Environmental engineering ,law.invention ,Trace gas ,Bellows ,law ,Environmental science ,Gas chromatography ,lcsh:TA170-171 ,Gas chromatography–mass spectrometry ,Process engineering ,business ,Gas compressor ,0105 earth and related environmental sciences - Abstract
Volatile organic compounds were quantified during two aircraft-based field campaigns using highly-automated, whole air samplers with expedited post-flight analysis via a new custom-built, field-deployable gas chromatography – mass spectrometry instrument. During flight, air samples were pressurized with a stainless steel bellows compressor into electropolished stainless steel canisters. The air samples were analyzed using a novel gas chromatograph system designed specifically for field-use which eliminates the need for liquid nitrogen. Instead, a Stirling cooler is used for cryogenic sample pre-concentration at temperatures as low as −165 °C. The analysis system was fully automated on a 20-minute cycle to allow for unattended processing of an entire flight of 72 sample canisters within 30 hours, thereby reducing typical sample residence times in the canisters to less than three days. The new analytical system is capable of quantifying a wide suite of C2 to C10 organic compounds at part-per-trillion sensitivity. This manuscript describes the sampling and analysis systems, along with the data analysis procedures which includes a new peak-fitting software package for rapid chromatographic data reduction. Instrument sensitivities, uncertainties and system artifacts are presented for 35 trace gas species in canister samples. Comparisons of reported mixing ratios from each field campaign with measurements from other instruments are also presented.
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- 2017
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6. Measurements of hydroxyl and hydroperoxy radicals during CalNex‐LA: Model comparisons and radical budgets
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N. Grossberg, Barry Lefer, Patrick R. Veres, R. F. Hansen, Cora J. Young, Sebastien Dusanter, Stephen M. Griffith, Philip S. Stevens, Eleanor M. Waxman, J. M. Roberts, Ryan Thalman, Hans D. Osthoff, Catalina Tsai, William C. Kuster, Jessica B. Gilman, Steven S. Brown, J. A. de Gouw, L. H. Mielke, Sergio Alvarez, Jochen Stutz, Rebecca A. Washenfelder, Martin Graus, B. Rappenglueck, James Flynn, Vincent Michoud, Rainer Volkamer, Université de Lille, Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Centre for Energy and Environment (CERI EE), Ecole nationale supérieure Mines-Télécom Lille Douai (IMT Lille Douai), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)
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Atmospheric Science ,Ozone ,010504 meteorology & atmospheric sciences ,Radical ,Formaldehyde ,010501 environmental sciences ,peroxy radical ,01 natural sciences ,7. Clean energy ,chemistry.chemical_compound ,Earth and Planetary Sciences (miscellaneous) ,ComputingMilieux_MISCELLANEOUS ,NOx ,0105 earth and related environmental sciences ,ozone production ,Nitrous acid ,hydroxyl radical ,Photodissociation ,CalNex ,Trace gas ,Geophysics ,chemistry ,[SDU]Sciences of the Universe [physics] ,13. Climate action ,Space and Planetary Science ,Environmental chemistry ,[SDE]Environmental Sciences ,Hydroxyl radical - Abstract
International audience; Measurements of hydroxyl (OH) and hydroperoxy (HO2*) radical concentrations were made at the Pasadena ground site during the CalNex-LA 2010 campaign using the laser-induced fluorescence-fluorescence assay by gas expansion technique. The measured concentrations of OH and HO2* exhibited a distinct weekend effect, with higher radical concentrations observed on the weekends corresponding to lower levels of nitrogen oxides (NOx). The radical measurements were compared to results from a zero-dimensional model using the Regional Atmospheric Chemical Mechanism-2 constrained by NOx and other measured trace gases. The chemical model overpredicted measured OH concentrations during the weekends by a factor of approximately 1.4 ± 0.3 (1σ), but the agreement was better during the weekdays (ratio of 1.0 ± 0.2). Model predicted HO2* concentrations underpredicted by a factor of 1.3 ± 0.2 on the weekends, while measured weekday concentrations were underpredicted by a factor of 3.0 ± 0.5. However, increasing the modeled OH reactivity to match the measured total OH reactivity improved the overall agreement for both OH and HO2* on all days. A radical budget analysis suggests that photolysis of carbonyls and formaldehyde together accounted for approximately 40% of radical initiation with photolysis of nitrous acid accounting for 30% at the measurement height and ozone photolysis contributing less than 20%. An analysis of the ozone production sensitivity reveals that during the week, ozone production was limited by volatile organic compounds throughout the day during the campaign but NOx limited during the afternoon on the weekends.
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- 2016
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7. Chemistry of Volatile Organic Compounds in the Los Angeles Basin: Formation of Oxygenated Compounds and Determination of Emission Ratios
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J. M. Roberts, Martin Graus, Sebastien Dusanter, Jochen Stutz, Stephen M. Griffith, Rebecca A. Washenfelder, Barry Lefer, Carsten Warneke, Jessica B. Gilman, Gabriel Isaacman-VanWertz, Brian C. McDonald, Bernhard Rappenglück, Sergio Alvarez, Rainer Volkamer, J. A. de Gouw, Cora J. Young, Si-Wan Kim, Brian M. Lerner, Ryan Thalman, William C. Kuster, Patrick R. Veres, Philip S. Stevens, Ecole nationale supérieure Mines-Télécom Lille Douai (IMT Lille Douai), and Institut Mines-Télécom [Paris] (IMT)
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Ozone pollution ,Atmospheric Science ,010504 meteorology & atmospheric sciences ,Chemistry ,010501 environmental sciences ,Structural basin ,01 natural sciences ,[SPI]Engineering Sciences [physics] ,Geophysics ,13. Climate action ,Space and Planetary Science ,Environmental chemistry ,Earth and Planetary Sciences (miscellaneous) ,0105 earth and related environmental sciences - Abstract
We analyze an expanded data set of oxygenated volatile organic compounds (OVOCs) in air measured by several instruments at a surface site in Pasadena near Los Angeles during the National Oceanic and Atmospheric Administration California Nexus study in 2010. The contributions of emissions, chemical formation, and removal are quantified for each OVOC using CO as a tracer of emissions and the OH exposure of the sampled air masses calculated from hydrocarbon ratios. The method for separating emissions from chemical formation is evaluated using output for Pasadena from the Weather Research and Forecasting-Chemistry model. The model is analyzed by the same method as the measurement data, and the emission ratios versus CO calculated from the model output agree for ketones with the inventory used in the model but overestimate aldehydes by ~70%. In contrast with the measurements, nighttime formation of OVOCs is significant in the model and is attributed to overestimated precursor emissions and overestimated rate coefficients for the reactions of the precursors with ozone and NO3. Most measured aldehydes correlated strongly with CO at night, suggesting a contribution from motor vehicle emissions. However, the emission ratios of most aldehydes versus CO are higher than those reported in motor vehicle emissions and the aldehyde sources remain unclear. Formation of several OVOCs is investigated in terms of the removal of specific precursors. Direct emissions of alcohols and aldehydes contribute significantly to OH reactivity throughout the day, and these emissions should be accurately represented in models describing ozone formation. ©2018. American Geophysical Union. All Rights Reserved.
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- 2018
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8. Biomass burning emissions and potential air quality impacts of volatile organic compounds and other trace gases from fuels common in the US
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Brian M. Lerner, Jessica B. Gilman, Carsten Warneke, J. A. de Gouw, I. R. Burling, Paul D. Goldan, J. M. Roberts, William C. Kuster, Robert J. Yokelson, and Patrick R. Veres
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Atmospheric Science ,010504 meteorology & atmospheric sciences ,Biomass ,010501 environmental sciences ,Combustion ,01 natural sciences ,7. Clean energy ,Methane ,lcsh:QC1-999 ,Aerosol ,Trace gas ,lcsh:Chemistry ,chemistry.chemical_compound ,chemistry ,lcsh:QD1-999 ,13. Climate action ,Environmental chemistry ,Air quality index ,NOx ,lcsh:Physics ,0105 earth and related environmental sciences ,Carbon monoxide - Abstract
A comprehensive suite of instruments was used to quantify the emissions of over 200 organic gases, including methane and volatile organic compounds (VOCs), and 9 inorganic gases from 56 laboratory burns of 18 different biomass fuel types common in the southeastern, southwestern, or northern US. A gas chromatograph-mass spectrometry (GC-MS) instrument provided extensive chemical detail of discrete air samples collected during a laboratory burn and was complemented by real-time measurements of organic and inorganic species via an open-path Fourier transform infrared spectroscopy (OP-FTIR) instrument and three different chemical ionization-mass spectrometers. These measurements were conducted in February 2009 at the US Department of Agriculture's Fire Sciences Laboratory in Missoula, Montana and were used as the basis for a number of emission factors reported by Yokelson et al. (2013). The relative magnitude and composition of the gases emitted varied by individual fuel type and, more broadly, by the three geographic fuel regions being simulated. Discrete emission ratios relative to carbon monoxide (CO) were used to characterize the composition of gases emitted by mass; reactivity with the hydroxyl radical, OH; and potential secondary organic aerosol (SOA) precursors for the 3 different US fuel regions presented here. VOCs contributed less than 0.78 % ± 0.12 % of emissions by mole and less than 0.95 % × 0.07 % of emissions by mass (on average) due to the predominance of CO2, CO, CH4, and NOx emissions; however, VOCs contributed 70–90 (±16) % to OH reactivity and were the only measured gas-phase source of SOA precursors from combustion of biomass. Over 82 % of the VOC emissions by mole were unsaturated compounds including highly reactive alkenes and aromatics and photolabile oxygenated VOCs (OVOCs) such as formaldehyde. OVOCs contributed 57–68 % of the VOC mass emitted, 41–54 % of VOC-OH reactivity, and aromatic-OVOCs such as benzenediols, phenols, and benzaldehyde were the dominant potential SOA precursors. In addition, ambient air measurements of emissions from the Fourmile Canyon Fire that affected Boulder, Colorado in September 2010 allowed us to investigate biomass burning (BB) emissions in the presence of other VOC sources (i.e., urban and biogenic emissions) and identify several promising BB markers including benzofuran, 2-furaldehyde, 2-methylfuran, furan, and benzonitrile.
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- 2015
9. Modeling the formation and aging of secondary organic aerosols in Los Angeles during CalNex 2010
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Jose L. Jimenez, Kirk R. Baker, Rebecca A. Washenfelder, André S. H. Prévôt, Annmarie G. Carlton, Ravan Ahmadov, Jessica B. Gilman, Bernhard Rappenglück, J. A. de Gouw, John H. Offenberg, Tadeusz E. Kleindienst, Peter Zotter, P. K. Ma, Soenke Szidat, Patrick L. Hayes, Sergio Alvarez, and William C. Kuster
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Pollution ,Atmospheric Science ,Meteorology ,media_common.quotation_subject ,Climate change ,lcsh:QC1-999 ,Aerosol ,lcsh:Chemistry ,Diesel fuel ,lcsh:QD1-999 ,Environmental science ,Mass concentration (chemistry) ,Climate model ,Gasoline ,Air quality index ,lcsh:Physics ,media_common - Abstract
Four different literature parameterizations for the formation and evolution of urban secondary organic aerosol (SOA) frequently used in 3-D models are evaluated using a 0-D box model representing the Los Angeles metropolitan region during the California Research at the Nexus of Air Quality and Climate Change (CalNex) 2010 campaign. We constrain the model predictions with measurements from several platforms and compare predictions with particle- and gas-phase observations from the CalNex Pasadena ground site. That site provides a unique opportunity to study aerosol formation close to anthropogenic emission sources with limited recirculation. The model SOA that formed only from the oxidation of VOCs (V-SOA) is insufficient to explain the observed SOA concentrations, even when using SOA parameterizations with multi-generation oxidation that produce much higher yields than have been observed in chamber experiments, or when increasing yields to their upper limit estimates accounting for recently reported losses of vapors to chamber walls. The Community Multiscale Air Quality (WRF-CMAQ) model (version 5.0.1) provides excellent predictions of secondary inorganic particle species but underestimates the observed SOA mass by a factor of 25 when an older VOC-only parameterization is used, which is consistent with many previous model–measurement comparisons for pre-2007 anthropogenic SOA modules in urban areas. Including SOA from primary semi-volatile and intermediate-volatility organic compounds (P-S/IVOCs) following the parameterizations of Robinson et al. (2007), Grieshop et al. (2009), or Pye and Seinfeld (2010) improves model–measurement agreement for mass concentration. The results from the three parameterizations show large differences (e.g., a factor of 3 in SOA mass) and are not well constrained, underscoring the current uncertainties in this area. Our results strongly suggest that other precursors besides VOCs, such as P-S/IVOCs, are needed to explain the observed SOA concentrations in Pasadena. All the recent parameterizations overpredict urban SOA formation at long photochemical ages (≈ 3 days) compared to observations from multiple sites, which can lead to problems in regional and especially global modeling. However, reducing IVOC emissions by one-half in the model to better match recent IVOC measurements improves SOA predictions at these long photochemical ages. Among the explicitly modeled VOCs, the precursor compounds that contribute the greatest SOA mass are methylbenzenes. Measured polycyclic aromatic hydrocarbons (naphthalenes) contribute 0.7% of the modeled SOA mass. The amounts of SOA mass from diesel vehicles, gasoline vehicles, and cooking emissions are estimated to be 16–27, 35–61, and 19–35%, respectively, depending on the parameterization used, which is consistent with the observed fossil fraction of urban SOA, 71(±3) %. The relative contribution of each source is uncertain by almost a factor of 2 depending on the parameterization used. In-basin biogenic VOCs are predicted to contribute only a few percent to SOA. A regional SOA background of approximately 2.1 μg m−3 is also present due to the long-distance transport of highly aged OA, likely with a substantial contribution from regional biogenic SOA. The percentage of SOA from diesel vehicle emissions is the same, within the estimated uncertainty, as reported in previous work that analyzed the weekly cycles in OA concentrations (Bahreini et al., 2012; Hayes et al., 2013). However, the modeling work presented here suggests a strong anthropogenic source of modern carbon in SOA, due to cooking emissions, which was not accounted for in those previous studies and which is higher on weekends. Lastly, this work adapts a simple two-parameter model to predict SOA concentration and O/C from urban emissions. This model successfully predicts SOA concentration, and the optimal parameter combination is very similar to that found for Mexico City. This approach provides a computationally inexpensive method for predicting urban SOA in global and climate models. We estimate pollution SOA to account for 26 Tg yr−1 of SOA globally, or 17% of global SOA, one-third of which is likely to be non-fossil., Atmospheric Chemistry and Physics, 15 (10), ISSN:1680-7375, ISSN:1680-7367
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- 2015
10. Intermediate-Volatility Organic Compounds: A Large Source of Secondary Organic Aerosol
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Yunliang Zhao, Daniel S. Tkacik, Agnès Borbon, Allen L. Robinson, Andrew A. May, Christopher J. Hennigan, William C. Kuster, Joost A. de Gouw, and Jessica B. Gilman
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Aerosols ,Air Pollutants ,Volatile Organic Compounds ,Time Factors ,Primary (chemistry) ,Chemistry ,General Chemistry ,Models, Theoretical ,California ,Aerosol ,Diesel fuel ,Particle mass ,Environmental chemistry ,Environmental Chemistry ,Volatility (chemistry) ,Air quality index ,Environmental Monitoring - Abstract
Secondary organic aerosol (SOA) is a major component of atmospheric fine particle mass. Intermediate-volatility organic compounds (IVOCs) have been proposed to be an important source of SOA. We present a comprehensive analysis of atmospheric IVOC concentrations and their SOA production using measurements made in Pasadena, California during the California at the Nexus of Air Quality and Climate Change (CalNex) study. The campaign-average concentration of primary IVOCs was 6.3 ± 1.9 μg m(-3) (average ± standard deviation), which is comparable to the concentration of organic aerosol but only 7.4 ± 1.2% of the concentration of speciated volatile organic compounds. Only 8.6 ± 2.2% of the mass of the primary IVOCs was speciated. Almost no weekend/weekday variation in the ambient concentration of both speciated and total primary IVOCs was observed, suggesting that petroleum-related sources other than on-road diesel vehicles contribute substantially to the IVOC emissions. Primary IVOCs are estimated to produce about 30% of newly formed SOA in the afternoon during CalNex, about 5 times that from single-ring aromatics. The importance of IVOCs in SOA formation is expected to be similar in many urban environments.
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- 2014
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11. A portable and inexpensive method for quantifying ambient intermediate volatility organic compounds
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Joost A. de Gouw, N. C. Bouvier-Brown, Vivian Okonta, James Karz, Daniel Ruiz, Jessica B. Gilman, Kylee Chang, William C. Kuster, Erica Carrasco, and Theodore Nguyen
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Detection limit ,Atmospheric Science ,Chromatography ,Adsorption ,Chemistry ,Environmental chemistry ,Gas chromatography ,Mass spectrometry ,Volatility (chemistry) ,Air quality index ,General Environmental Science ,Aerosol - Abstract
Volatile organic compounds (VOCs) and intermediate volatility VOCs (IVOCs) are gas-phase organic compounds which may participate in chemical reactions affecting air quality and climate. The development of an inexpensive, field-portable quantification method for higher molecular weight VOCs and IVOCs utilizing commercially available components could be used as a tool to survey aerosol precursors or identify and monitor air quality in various communities. We characterized the performance characteristics for the HayeSep-Q adsorbent with a representative selection of anthropogenic and biogenic VOC standards and optimized experimental conditions and procedures for field collections followed by laboratory analysis. All VOCs were analyzed using gas chromatography coupled with mass spectrometry. Precision (average 22%) and accuracy were reasonable and the limit of detection ranged from 10 to 80 pmol/mol (ppt) for the studied compounds. The method was employed at the Los Angeles site during the CalNex campaign in summer 2010 and ambient mixing ratios agreed well (slope 0.69–1.06, R 2 0.67–0.71) with measurements made using an in-situ GC–MS – a distinctly different sampling and quantification method. This new technique can be applied to quantify ambient biogenic and anthropogenic C8–C15 VOCs and IVOCs.
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- 2014
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12. An MCM modeling study of nitryl chloride (ClNO2) impacts on oxidation, ozone production and nitrogen oxide partitioning in polluted continental outflow
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K. T. Danas, Joel A. Thornton, Steven S. Brown, Brian M. Lerner, J. M. Roberts, A. Vlasenko, Glenn M. Wolfe, Theran P. Riedel, Jessica B. Gilman, Shao-Meng Li, J. S. Holloway, D. M. Bon, Barry Lefer, Patrick R. Veres, Eric J. Williams, and William C. Kuster
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Atmospheric Science ,Ozone ,Dinitrogen pentoxide ,Radical ,Inorganic chemistry ,Photodissociation ,chemistry.chemical_element ,Photochemistry ,Chloride ,chemistry.chemical_compound ,chemistry ,medicine ,Chlorine ,Nitrogen oxide ,NOx ,medicine.drug - Abstract
Nitryl chloride (ClNO2) is produced at night by reactions of dinitrogen pentoxide (N2O5) on chloride containing surfaces. ClNO2 is photolyzed during the morning hours after sunrise to liberate highly reactive chlorine atoms (Cl·). This chemistry takes place primarily in polluted environments where the concentrations of N2O5 precursors (nitrogen oxide radicals and ozone) are high, though it likely occurs in remote regions at lower intensities. Recent field measurements have illustrated the potential importance of ClNO2 as a daytime Cl· source and a nighttime NOx reservoir. However, the fate of the Cl· and the overall impact of ClNO2 on regional photochemistry remain poorly constrained by measurements and models. To this end, we have incorporated ClNO2 production, photolysis, and subsequent Cl· reactions into an existing master chemical mechanism (MCM version 3.2) box model framework using observational constraints from the CalNex 2010 field study. Cl· reactions with a set of alkenes and alcohols, and the simplified multiphase chemistry of N2O5, ClNO2, HOCl, ClONO2, and Cl2, none of which are currently part of the MCM, have been added to the mechanism. The presence of ClNO2 produces significant changes to oxidants, ozone, and nitrogen oxide partitioning, relative to model runs excluding ClNO2 formation. From a nighttime maximum of 1.5 ppbv ClNO2, the daytime maximum Cl· concentration reaches 1 × 105 atoms cm−3 at 07:00 model time, reacting mostly with a large suite of volatile organic compounds (VOC) to produce 2.2 times more organic peroxy radicals in the morning than in the absence of ClNO2. In the presence of several ppbv of nitrogen oxide radicals (NOx = NO + NO2), these perturbations lead to similar enhancements in hydrogen oxide radicals (HOx = OH + HO2). Neglecting contributions from HONO, the total integrated daytime radical source is 17% larger when including ClNO2, which leads to a similar enhancement in integrated ozone production of 15%. Detectable levels (tens of pptv) of chlorine containing organic compounds are predicted to form as a result of Cl· addition to alkenes, which may be useful in identifying times of active Cl· chemistry.
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- 2014
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13. Emission factor ratios, SOA mass yields, and the impact of vehicular emissions on SOA formation
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Allen L. Robinson, Shantanu H. Jathar, John S. Holloway, William C. Kuster, John H. Seinfeld, Jessica B. Gilman, J. A. de Gouw, Jose L. Jimenez, Patrick L. Hayes, J. J. Ensberg, and T. D. Gordon
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Atmospheric Science ,Meteorology ,Atmospheric models ,Chemistry ,Laboratory chamber ,Atmospheric sciences ,lcsh:QC1-999 ,Aerosol ,lcsh:Chemistry ,lcsh:QD1-999 ,Gasoline ,Ambient data ,Vehicular Emissions ,lcsh:Physics - Abstract
The underprediction of ambient secondary organic aerosol (SOA) levels by current atmospheric models in urban areas is well established, yet the cause of this underprediction remains elusive. Likewise, the relative contribution of emissions from gasoline- and diesel-fueled vehicles to the formation of SOA is generally unresolved. We investigate the source of these two discrepancies using data from the 2010 CalNex experiment carried out in the Los Angeles Basin (Ryerson et al., 2013). Specifically, we use gas-phase organic mass (GPOM) and CO emission factors in conjunction with measured enhancements in oxygenated organic aerosol (OOA) relative to CO to quantify the significant lack of closure between expected and observed organic aerosol concentrations attributable to fossil-fuel emissions. Two possible conclusions emerge from the analysis to yield consistency with the ambient data: (1) vehicular emissions are not a dominant source of anthropogenic fossil SOA in the Los Angeles Basin, or (2) the ambient SOA mass yields used to determine the SOA formation potential of vehicular emissions are substantially higher than those derived from laboratory chamber studies.
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- 2014
14. Organic aerosol composition and sources in Pasadena, California, during the 2010 CalNex campaign
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James Flynn, Jiumeng Liu, Jose L. Jimenez, Steven S. Cliff, A. L. Corrigan, Philip S. Stevens, Amber M. Ortega, Tadeusz E. Kleindienst, Ying Hsuan Lin, Karl D. Froyd, Rainer Volkamer, Xiaolu Zhang, Paola Massoli, J. A. de Gouw, Ryan Thalman, N. Grossberg, Sebastien Dusanter, Yongjing Zhao, Stephen M. Griffith, Weiwei Hu, William C. Kuster, Eleanor M. Waxman, Lynn M. Russell, Allen H. Goldstein, Wayne M. Angevine, Patrick L. Hayes, Sergio Alvarez, Jonathan Taylor, James Allan, Jason D. Surratt, Darin W. Toohey, David R. Worton, Rodney J. Weber, G. A. Isaacman, John H. Offenberg, Jerome Brioude, Jessica B. Gilman, John S. Holloway, Bernhard Rappenglück, Nathan M. Kreisberg, Barry Lefer, and Michael J. Cubison
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Atmospheric Science ,Elemental composition ,Meteorology ,Common line ,Particulates ,Atmospheric sciences ,Aerosol ,Geophysics ,Space and Planetary Science ,Mexico city ,Earth and Planetary Sciences (miscellaneous) ,Environmental science ,Aerosol composition ,Gasoline ,Air quality index - Abstract
[1] Organic aerosols (OA) in Pasadena are characterized using multiple measurements from the California Research at the Nexus of Air Quality and Climate Change (CalNex) campaign. Five OA components are identified using positive matrix factorization including hydrocarbon-like OA (HOA) and two types of oxygenated OA (OOA). The Pasadena OA elemental composition when plotted as H : C versus O : C follows a line less steep than that observed for Riverside, CA. The OOA components from both locations follow a common line, however, indicating similar secondary organic aerosol (SOA) oxidation chemistry at the two sites such as fragmentation reactions leading to acid formation. In addition to the similar evolution of elemental composition, the dependence of SOA concentration on photochemical age displays quantitatively the same trends across several North American urban sites. First, the OA/ΔCO values for Pasadena increase with photochemical age exhibiting a slope identical to or slightly higher than those for Mexico City and the northeastern United States. Second, the ratios of OOA to odd-oxygen (a photochemical oxidation marker) for Pasadena, Mexico City, and Riverside are similar, suggesting a proportional relationship between SOA and odd-oxygen formation rates. Weekly cycles of the OA components are examined as well. HOA exhibits lower concentrations on Sundays versus weekdays, and the decrease in HOA matches that predicted for primary vehicle emissions using fuel sales data, traffic counts, and vehicle emission ratios. OOA does not display a weekly cycle—after accounting for differences in photochemical aging —which suggests the dominance of gasoline emissions in SOA formation under the assumption that most urban SOA precursors are from motor vehicles.
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- 2013
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15. Detailed chemical characterization of unresolved complex mixtures in atmospheric organics: Insights into emission sources, atmospheric processing, and secondary organic aerosol formation
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Jason D. Surratt, Tadeusz E. Kleindienst, Robert A. Harley, Ying Hsuan Lin, Jose L. Jimenez, David R. Worton, Patrick L. Hayes, Caitlin L. Rubitschun, Drew R. Gentner, G. A. Isaacman, John H. Offenberg, Allen H. Goldstein, Jessica B. Gilman, Kevin R. Wilson, Theodora Nah, Thomas W. Kirchstetter, Arthur W. H. Chan, Timothy R. Dallmann, Joost A. de Gouw, William C. Kuster, and Christopher R. Ruehl
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Atmospheric Science ,Geophysics ,Oceanography ,Space and Planetary Science ,Earth and Planetary Sciences (miscellaneous) ,National laboratory ,Archaeology - Abstract
Detailed Chemical Characterization of Unresolved Complex Mixtures (UCM) in Atmospheric Organics: Insights into Emission Sources, Atmospheric Processing and Secondary Organic Aerosol Formation Arthur W. H. Chan 1 , Gabriel Isaacman 1 , Kevin R. Wilson 2 , David R. Worton 1,3 , Chris R. Ruehl 1 , Theodora Nah 4 , Drew R. Gentner 5 , Timothy R. Dallman 5 , Thomas W. Kirchstetter 5,6 , Robert A. Harley 5,6 , Jessica B. Gilman 7,8 , William C. Kuster 8 , Joost A. de Gouw 7,8 , John H. Offenberg 9 , Tadeusz E. Kleindienst 9 , Ying H. Lin 10 , Caitlin L. Rubitschun 10 , Jason D. Surratt 10 , and Allen H. Goldstein 1,5,6 Berkeley, CA, USA Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA Aerosol Dynamics Inc., Berkeley, CA, USA Department of Chemistry, University of California, Berkeley, CA, USA Department of Civil and Environmental Engineering, University of California, Berkeley, CA, USA CA, USA Colorado, Boulder, CO, USA Department of Environmental Science, Policy, and Management, University of California, Environment Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, Cooperative Institute for Research in the Environmental Sciences (CIRES), University of NOAA Chemical Sciences Division, Boulder, CO, USA
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- 2013
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16. Quantifying sources of methane using light alkanes in the Los Angeles basin, California
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Donald R. Blake, Steven C. Wofsy, J. Kofler, Bruce C. Daube, Michael Trainer, Drew R. Gentner, Jessica B. Gilman, Elliot Atlas, G. W. Santoni, Jerome Brioude, Kenneth C. Aikin, Robert A. Harley, John S. Holloway, P. M. Lang, J. A. de Gouw, T. B. Ryerson, Gregory J. Frost, Paul C. Novelli, Jeff Peischl, David D. Parrish, Edward J. Dlugokencky, William C. Kuster, Arlyn E. Andrews, and Allen H. Goldstein
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Hydrology ,Atmospheric Science ,business.industry ,Greenhouse gas inventory ,Structural basin ,Methane ,Pipeline transport ,chemistry.chemical_compound ,Geophysics ,chemistry ,Petroleum industry ,Space and Planetary Science ,Natural gas ,Carbon dioxide ,Earth and Planetary Sciences (miscellaneous) ,Environmental science ,business ,Carbon monoxide - Abstract
[1] Methane (CH4), carbon dioxide (CO2), carbon monoxide (CO), and C2–C5 alkanes were measured throughout the Los Angeles (L.A.) basin in May and June 2010. We use these data to show that the emission ratios of CH4/CO and CH4/CO2 in the L.A. basin are larger than expected from population-apportioned bottom-up state inventories, consistent with previously published work. We use experimentally determined CH4/CO and CH4/CO2 emission ratios in combination with annual State of California CO and CO2 inventories to derive a yearly emission rate of CH4 to the L.A. basin. We further use the airborne measurements to directly derive CH4 emission rates from dairy operations in Chino, and from the two largest landfills in the L.A. basin, and show these sources are accurately represented in the California Air Resources Board greenhouse gas inventory for CH4. We then use measurements of C2–C5 alkanes to quantify the relative contribution of other CH4 sources in the L.A. basin, with results differing from those of previous studies. The atmospheric data are consistent with the majority of CH4 emissions in the region coming from fugitive losses from natural gas in pipelines and urban distribution systems and/or geologic seeps, as well as landfills and dairies. The local oil and gas industry also provides a significant source of CH4 in the area. The addition of CH4 emissions from natural gas pipelines and urban distribution systems and/or geologic seeps and from the local oil and gas industry is sufficient to account for the differences between the top-down and bottom-up CH4 inventories identified in previously published work.
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- 2013
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17. The impact of shipping, agricultural, and urban emissions on single particle chemistry observed aboard the R/VAtlantisduring CalNex
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William C. Kuster, Timothy S. Bates, Cassandra J. Gaston, Patricia K. Quinn, D. Bon, Jessica B. Gilman, and Kimberly A. Prather
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Pollution ,Total organic carbon ,Atmospheric Science ,media_common.quotation_subject ,Air pollution ,medicine.disease_cause ,Atmospheric sciences ,Soot ,Aerosol ,chemistry.chemical_compound ,Geophysics ,chemistry ,Space and Planetary Science ,Climatology ,Earth and Planetary Sciences (miscellaneous) ,medicine ,Particle ,Sulfate ,Air quality index ,media_common - Abstract
[1] The Research at the Nexus of Air Quality and Climate Change (CalNex) field campaign was undertaken to obtain a better understanding of the regional impacts of different pollution sources in California. As part of this study, real-time shipboard measurements were made of the size-resolved, single-particle mixing state of submicron and supermicron particles (0.2–3.0 µm aerodynamic diameter) along the California coast where major differences were noted between Southern and Northern California. In Southern California, particles containing soot made up the largest fraction of submicron particles (~38% on average and up to ~89% by number), whereas organic carbon particles comprised the largest fraction of submicron number concentrations (~29% on average and up to ~78% by number) in Northern California including the Sacramento area. The mixing state of these carbonaceous particle types varied during the cruise with sulfate being more prevalent on soot-containing particles in Southern California due to the influence of fresh shipping and port emissions in addition to contributions from marine biogenic emissions. Contributions from secondary organic aerosol species, including amines, and nitrate were more prevalent in Northern California, as well as during time periods impacted by agricultural emissions (e.g., from the inland Riverside and Central Valley regions). These regional differences and changes in the mixing state and sources of particles have implications for heterogeneous reactivity, water uptake, and cloud-nucleating abilities for aerosols in California.
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- 2013
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18. Photochemical aging of volatile organic compounds in the Los Angeles basin: Weekday-weekend effect
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Robert A. Harley, Peter Edwards, Elliot Atlas, Jessica B. Gilman, Drew R. Gentner, Carsten Warneke, Donald R. Blake, Sergio Alvarez, Joost A. de Gouw, John S. Holloway, David D. Parrish, Martin Graus, Allen H. Goldstein, William C. Kuster, Michael Trainer, and B. Rappenglueck
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Atmospheric Science ,Box model ,Ozone ,Weekend effect ,Photochemistry ,chemistry.chemical_compound ,Diesel fuel ,Geophysics ,chemistry ,Space and Planetary Science ,Earth and Planetary Sciences (miscellaneous) ,Trimethyl benzene ,Environmental science ,Benzene ,Air quality index ,NOx - Abstract
[1] During the CalNex (California Research at the Nexus of Air Quality and Climate Change) field study in May–June 2010, measurements of volatile organic compounds (VOCs) were performed in the Los Angeles (LA) basin onboard a NOAA research aircraft and at a ground site located in Pasadena. A weekday-weekend effect in ozone, caused by lower NOx emissions due to reduced diesel truck traffic in the weekends, has been previously observed in Los Angeles and other cities. Measurements in the Caldecott tunnel show that emission ratios of VOCs do not vary with the day of the week, but measurements during CalNex2010 show a VOC weekday-weekend effect through faster photochemical processing at lower ambient NOx mixing ratios. Ambient VOC enhancement ratios of long-lived species such as benzene are the same between weekdays and weekends, whereas enhancement ratios of short-lived species, such as trimethyl benzene, are up to a factor of three lower on weekends. Based upon the observed differences in VOC enhancement ratios to CO, we determine that photochemical processing was on average 65%–75% faster on weekends during CalNex2010, which indicates that ambient OH radical concentrations were larger by this factor causing the observed change in VOC composition. A box model calculation based on the Master Chemical Mechanism was used to verify the increase in photochemical processing in the weekends.
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- 2013
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19. Droplet activation properties of organic aerosols observed at an urban site during CalNex-LA
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Patrick L. Hayes, Jonathan Taylor, James Allan, Amber M. Ortega, Jose L. Jimenez, Jessica B. Gilman, William C. Kuster, Jian Wang, Fan Mei, and Joost A. de Gouw
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Atmospheric Science ,Meteorology ,Condensation ,Diurnal temperature variation ,Analytical chemistry ,Aerosol ,chemistry.chemical_compound ,Geophysics ,chemistry ,Space and Planetary Science ,Volume fraction ,Earth and Planetary Sciences (miscellaneous) ,Cloud condensation nuclei ,Particle ,Atomic ratio ,Sulfate - Abstract
[1] Size-resolved cloud condensation nuclei (CCN) spectra and aerosol chemical composition were characterized at an urban supersite in Pasadena, California, from 15 May to 4 June 2010, during the CalNex campaign. The derived hygroscopicity (κCCN) of CCN-active particles with diameter between 97 and 165 nm ranged from 0.05 to 0.4. Diurnal variation showed a slight decrease of κCCN from 8:00 to 16:00 (from 0.24 to 0.20), which is attributed to increasing organics volume fraction resulted from secondary organic aerosol (SOA) formation. The derived hygroscopicity distribution and maximum activated fraction of the size selected particles were examined as functions of photochemical age. The result indicates that condensation of secondary species (e.g., SOA and sulfate) quickly converted hydrophobic particles to hydrophilic ones, and during daytime, nearly every particle became a CCN at ~0.4% in just a few hours. Based on κCCN and aerosol chemical composition, the organic hygroscopicity (κorg) was derived, and ranged from 0.05 to 0.23 with an average value of 0.13, consistent with the results from earlier studies. The derived κorg generally increased with the organic oxidation level, and most of the variation in κorg could be explained by the variation of the organic O : C atomic ratio alone. The least squares fit of the data yielded κorg = (0.83 ± 0.06) × (O:C) + (−0.19 ± 0.02). Compared to previous results based on CCN measurements of laboratory generated aerosols, κorg derived from measurements during the CalNex campaign exhibited stronger increase with O : C atomic ratio and therefore substantially higher values for organics with average O : C greater than 0.5.
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- 2013
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20. Emission ratios of anthropogenic volatile organic compounds in northern mid-latitude megacities: Observations versus emission inventories in Los Angeles and Paris
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Agnès Borbon, Roland Sarda-Esteve, Carsten Warneke, C. Dolgorouky, Servanne Chevaillier, William C. Kuster, Noël Grand, Jochen Stutz, J. A. de Gouw, Valérie Gros, Aurélie Colomb, Stuart A. McKeen, D. D. Parrish, M. Lopez, Hervé Petetin, John S. Holloway, Matthias Beekmann, and Jessica B. Gilman
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Atmospheric Science ,010504 meteorology & atmospheric sciences ,Climate change ,010501 environmental sciences ,Urban area ,Atmospheric sciences ,7. Clean energy ,01 natural sciences ,chemistry.chemical_compound ,11. Sustainability ,Earth and Planetary Sciences (miscellaneous) ,media_common.cataloged_instance ,Volatile organic compound ,Gasoline ,European union ,Air quality index ,Isoprene ,0105 earth and related environmental sciences ,media_common ,chemistry.chemical_classification ,geography ,geography.geographical_feature_category ,Geophysics ,Megacity ,chemistry ,13. Climate action ,Space and Planetary Science - Abstract
[1] Ground-based and airborne volatile organic compound (VOC) measurements in Los Angeles, California, and Paris, France, during the Research at the Nexus of Air Quality and Climate Change (CalNex) and Megacities: Emissions, Urban, Regional and Global Atmospheric Pollution and Climate Effects, and Integrated Tools for Assessment and Mitigation (MEGAPOLI) campaigns, respectively, are used to examine the spatial variability of the composition of anthropogenic VOC urban emissions and to evaluate regional emission inventories. Two independent methods that take into account the effect of chemistry were used to determine the emission ratios of anthropogenic VOCs (including anthropogenic isoprene and oxygenated VOCs) over carbon monoxide (CO) and acetylene. Emission ratios from both methods agree within ±20%, showing the reliability of our approach. Emission ratios for alkenes, alkanes, and benzene are fairly similar between Los Angeles and Paris, whereas the emission ratios for C7–C9 aromatics in Paris are higher than in Los Angeles and other French and European Union urban areas by a factor of 2–3. The results suggest that the emissions of gasoline-powered vehicles still dominate the hydrocarbon distribution in northern mid-latitude urban areas, which disagrees with emission inventories. However, regional characteristics like the gasoline composition could affect the composition of hydrocarbon emissions. The observed emission ratios show large discrepancies by a factor of 2–4 (alkanes and oxygenated VOC) with the ones derived from four reference emission databases. A bias in CO emissions was also evident for both megacities. Nevertheless, the difference between measurements and inventory in terms of the overall OH reactivity is, in general, lower than 40%, and the potential to form secondary organic aerosols (SOA) agrees within 30% when considering volatile organic emissions as the main SOA precursors.
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- 2013
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21. Source Signature of Volatile Organic Compounds from Oil and Natural Gas Operations in Northeastern Colorado
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William C. Kuster, Jessica B. Gilman, Brian M. Lerner, and J. A. de Gouw
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Colorado ,Time Factors ,Ozone ,Natural Gas ,Atmosphere ,Propane ,chemistry.chemical_compound ,Natural gas ,Pentanes ,Environmental Chemistry ,Cities ,Hydrology ,Volatile Organic Compounds ,Hydroxyl Radical ,business.industry ,General Chemistry ,chemistry ,Environmental chemistry ,Multivariate Analysis ,Environmental science ,business ,Oils ,Environmental Monitoring ,Oil and natural gas - Abstract
An extensive set of volatile organic compounds (VOCs) was measured at the Boulder Atmospheric Observatory (BAO) in winter 2011 in order to investigate the composition and influence of VOC emissions from oil and natural gas (O&NG) operations in northeastern Colorado. BAO is 30 km north of Denver and is in the southwestern section of Wattenberg Field, one of Colorado's most productive O&NG fields. We compare VOC concentrations at BAO to those of other U.S. cities and summertime measurements at two additional sites in northeastern Colorado, as well as the composition of raw natural gas from Wattenberg Field. These comparisons show that (i) the VOC source signature associated with O&NG operations can be clearly differentiated from urban sources dominated by vehicular exhaust, and (ii) VOCs emitted from O&NG operations are evident at all three measurement sites in northeastern Colorado. At BAO, the reactivity of VOCs with the hydroxyl radical (OH) was dominated by C(2)-C(6) alkanes due to their remarkably large abundances (e.g., mean propane = 27.2 ppbv). Through statistical regression analysis, we estimate that on average 55 ± 18% of the VOC-OH reactivity was attributable to emissions from O&NG operations indicating that these emissions are a significant source of ozone precursors.
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- 2013
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22. Supplementary material to 'An Improved, Automated Whole-Air Sampler and Gas Chromatography Mass Spectrometry Analysis System for Volatile Organic Compounds in the Atmosphere'
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Brian M. Lerner, Jessica B. Gilman, Kenneth C. Aikin, Elliot L. Atlas, Paul D. Goldan, Martin Graus, R. Hendershot, Gabriel A. Isaacman-VanWertz, Abigail Koss, William C. Kuster, Richard A. Lueb, Richard J. McLaughlin, Jeff Peischl, Donna Sueper, Thomas B. Ryerson, Travis W. Tokarek, Carsten Warneke, Bin Yuan, and Joost A. de Gouw
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- 2016
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23. Chemistry of Volatile Organic Compounds in the Los Angeles basin: Nighttime Removal of Alkenes and Determination of Emission Ratios
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Jochen Stutz, Barry Lefer, Stephen M. Griffith, Gabriel Isaacman-VanWertz, Carsten Warneke, Brian M. Lerner, Si-Wan Kim, Jessica B. Gilman, Brian C. McDonald, Sebastien Dusanter, J. A. de Gouw, Philip S. Stevens, and William C. Kuster
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chemistry.chemical_classification ,Atmospheric Science ,Ozone ,010504 meteorology & atmospheric sciences ,Meteorology ,Alkene ,Radical ,010501 environmental sciences ,Mass spectrometry ,01 natural sciences ,chemistry.chemical_compound ,Geophysics ,Hydrocarbon ,chemistry ,Nitrate ,Space and Planetary Science ,Environmental chemistry ,Earth and Planetary Sciences (miscellaneous) ,Air quality index ,0105 earth and related environmental sciences ,Carbon monoxide - Abstract
We reanalyze a data set of hydrocarbons in ambient air obtained by gas chromatography-mass spectrometry at a surface site in Pasadena in the Los Angeles basin during the NOAA California Nexus study in 2010. The number of hydrocarbon compounds quantified from the chromatograms is expanded through the use of new peak-fitting data analysis software. We also reexamine hydrocarbon removal processes. For alkanes, small alkenes, and aromatics, the removal is determined by the reaction with hydroxyl (OH) radicals. For several highly reactive alkenes, the nighttime removal by ozone and nitrate (NO3) radicals is also significant. We discuss how this nighttime removal affects the determination of emission ratios versus carbon monoxide (CO) and show that previous estimates based on nighttime correlations with CO were too low. We analyze model output from the Weather Research and Forecasting-Chemistry model for hydrocarbons and radicals at the Pasadena location to evaluate our methods for determining emission ratios from the measurements. We find that our methods agree with the modeled emission ratios for the domain centered on Pasadena and that the modeled emission ratios vary by 23% across the wider South Coast basin. We compare the alkene emission ratios with published results from ambient measurements and from tunnel and dynamometer studies of motor vehicle emissions. We find that with few exceptions the composition of alkene emissions determined from the measurements in Pasadena closely resembles that of motor vehicle emissions.
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- 2017
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24. Modelled and measured concentrations of peroxy radicals and nitrate radical in the U.S. Gulf Coast region during TexAQS 2006
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Steven S. Brown, Carsten Warneke, Sara C. Tucker, Daniel M. Brookes, Joost A. de Gouw, Timothy S. Bates, A. E. Parker, Hans D. Osthoff, Scott C. Herndon, James M. Roberts, Eric J. Williams, Jessica B. Gilman, William C. Kuster, Roberto Sommariva, D. Bon, Paul S. Monks, Brian M. Lerner, and Mark S. Zahniser
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Atmospheric Science ,chemistry.chemical_compound ,chemistry ,Nitrate ,Environmental chemistry ,Radical ,Environmental Chemistry ,Photochemistry ,Isoprene ,Field campaign ,Research vessel - Abstract
Measurements of total peroxy radicals (HO2 + RO2) and nitrate radical (NO3) were made on the NOAA research vessel R/V Brown along the U.S. Gulf Coast during the TexAQS 2006 field campaign. The measurements were modelled using a constrained box-model based upon the Master Chemical Mechanism (MCM). The agreement between modelled and measured HO2 + RO2 was typically within ∼40% and, in the unpolluted regions, within 30%. The analysis of the model results suggests that the MCM might underestimate the concentrations of some acyl peroxy radicals and other small peroxy radicals. The model underestimated the measurements of NO3 by 60–70%, possibly because of rapid heterogeneous uptake of N2O5. The MCM model results were used to estimate the composition of the peroxy radical pool and to quantify the role of DMS, isoprene and alkenes in the formation of RO2 in the different regions. The measurements of HO2 + RO2 and NO3 were also used to calculate the gas-phase budget of NO3 and quantify the importance of organic peroxy radicals as NO3 sinks. RO2 accounted, on average, for 12–28% of the total gas-phase NO3 losses in the unpolluted regions and for 1–2% of the total gas-phase NO3 losses in the polluted regions.
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- 2011
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25. Photochemical modeling of glyoxal at a rural site: observations and analysis from BEARPEX 2007
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Jose L. Jimenez, Joel A. Thornton, Allen H. Goldstein, Michael J. Cubison, Delphine K. Farmer, Wonsik Choi, N. C. Bouvier-Brown, Andrew J. Huisman, William C. Kuster, J. A. de Gouw, Melissa M. Galloway, Jessica B. Gilman, Katherine L. Coens, Ian Faloona, Joshua P. DiGangi, Brian W. LaFranchi, William H. Brune, Ronald C. Cohen, Glenn M. Wolfe, J. Hottle, Jingqiu Mao, Kenneth S. Docherty, and Frank N. Keutsch
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Atmospheric Science ,Box model ,Photodissociation ,Photochemistry ,Redox ,Rural environment ,lcsh:QC1-999 ,Aerosol ,lcsh:Chemistry ,chemistry.chemical_compound ,chemistry ,lcsh:QD1-999 ,TRACER ,Glyoxal ,Isoprene ,lcsh:Physics - Abstract
We present roughly one month of high time-resolution, direct, in situ measurements of gas-phase glyoxal acquired during the BEARPEX 2007 field campaign. The research site, located on a ponderosa pine plantation in the Sierra Nevada mountains, is strongly influenced by biogenic volatile organic compounds (BVOCs); thus this data adds to the few existing measurements of glyoxal in BVOC-dominated areas. The short lifetime of glyoxal of ~1 h, the fact that glyoxal mixing ratios are much higher during high temperature periods, and the results of a photochemical model demonstrate that glyoxal is strongly influenced by BVOC precursors during high temperature periods. A zero-dimensional box model using near-explicit chemistry from the Leeds Master Chemical Mechanism v3.1 was used to investigate the processes controlling glyoxal chemistry during BEARPEX 2007. The model showed that MBO is the most important glyoxal precursor (~67 %), followed by isoprene (~26 %) and methylchavicol (~6 %), a precursor previously not commonly considered for glyoxal production. The model calculated a noon lifetime for glyoxal of ~0.9 h, making glyoxal well suited as a local tracer of VOC oxidation in a forested rural environment; however, the modeled glyoxal mixing ratios over-predicted measured glyoxal by a factor 2 to 5. Loss of glyoxal to aerosol was not found to be significant, likely as a result of the very dry conditions, and could not explain the over-prediction. Although several parameters, such as an approximation for advection, were found to improve the model measurement discrepancy, reduction in OH was by far the most effective. Reducing model OH concentrations to half the measured values decreased the glyoxal over-prediction from a factor of 2.4 to 1.1, as well as the overprediction of HO2 from a factor of 1.64 to 1.14. Our analysis has shown that glyoxal is particularly sensitive to OH concentration compared to other BVOC oxidation products. This relationship arises from (i) the predominantly secondary- or higher-generation production of glyoxal from (mainly OH-driven, rather than O3-driven) BVOC oxidation at this site and (ii) the relative importance of photolysis in glyoxal loss as compared to reaction with OH. We propose that glyoxal is a useful tracer for OH-driven BVOC oxidation chemistry.
- Published
- 2011
26. Emissions and photochemistry of oxygenated VOCs in urban plumes in the Northeastern United States
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Carsten Warneke, J. A. de Gouw, Michael Trainer, Fred C. Fehsenfeld, Elliot Atlas, Roberto Sommariva, Paul D. Goldan, and William C. Kuster
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chemistry.chemical_classification ,Atmospheric Science ,Ethanol ,Ketone ,Acetaldehyde ,Photochemistry ,lcsh:QC1-999 ,City area ,lcsh:Chemistry ,chemistry.chemical_compound ,Acetic acid ,chemistry ,lcsh:QD1-999 ,Propane ,Acetone ,Methanol ,lcsh:Physics - Abstract
Photochemical processes inside urban plumes in the Northeast of the United States have been studied using a highly detailed chemical model, based upon the Master Chemical Mechanism (MCM). The model results have been compared to measurements of oxygenated VOCs (acetone, methyl ethyl ketone, acetaldehyde, acetic acid and methanol) obtained during several flights of the NOAA WP-3D aircraft, which sampled plumes from the New York City area during the ICARTT campaign in 2004. The agreement between the model and the measurements was within 40–60% for all species, except acetic acid. The model results have been used to study the formation and photochemical evolution of acetone, methyl ethyl ketone and acetaldehyde. Under the conditions encountered during the ICARTT campaign, acetone is produced from the oxidation of propane (24–28%) and i-propanol (C5 alkanes, propanal and MEK. Ethane and ethanol oxidation account, respectively, for 6–23% and 5–25% of acetaldehyde photochemical formation. The results highlight the importance of long-chain alkanes for the photochemical production of ketones and the role of hydroperoxides in sustaining their formation far from the emission sources.
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- 2011
27. Volatile organic compound emissions from switchgrass cultivars used as biofuel crops
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Russell K. Monson, E. Crespo, William C. Kuster, Carsten Warneke, Kanako Sekimoto, J. A. de Gouw, Allyson S. D. Eller, Ray Fall, Martin Graus, and Jessica B. Gilman
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chemistry.chemical_classification ,Atmospheric Science ,biology ,Environmental engineering ,biology.organism_classification ,Eucalyptus ,chemistry ,Agronomy ,Biofuel ,Cellulosic ethanol ,Panicum virgatum ,Volatile organic compound ,Cultivar ,Air quality index ,General Environmental Science ,Woody plant - Abstract
Volatile organic compound (VOC) emission rates during the growth and simulated harvest phases were determined for switchgrass (Panicum virgatum) using laboratory chamber measurements. Switchgrass is a candidate for use in second-generation (cellulosic) biofuel production and the acreage dedicated to its growth in the USA has already increased during the past decade. We estimate that the yearly emissions from switchgrass plantations, including both the growth and harvest phases will be on the order of 3 kg C ha−1 methanol, 1 kg C ha−1 acetaldehyde, 1 kg C ha−1 acetone, 0.9 kg C ha−1 monoterpenes, 0.5 kg C ha−1 isoprene + another compound, most likely 1-penten-3-ol, 0.2 kg C ha−1 hexenals, and 0.1 kg C ha−1 hexenols. These emission rates are much lower than those expected from Eucalyptus or poplar plantations, which are other potential biofuel crops and have significantly higher VOC emissions, suggesting that the choice of species in the production of biofuels could have serious implications for regional air quality.
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- 2011
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28. Isocyanic acid in the atmosphere and its possible link to smoke-related health effects
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Brian M. Lerner, Robert J. Yokelson, William C. Kuster, Anthony K. Cochran, Jessica B. Gilman, Joost A. de Gouw, Patrick R. Veres, Carsten Warneke, I. R. Burling, Ray Fall, and James M. Roberts
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Colorado ,Air pollution ,Biomass ,Nitric Oxide ,medicine.disease_cause ,Combustion ,California ,Catalysis ,Fires ,chemistry.chemical_compound ,Diesel fuel ,Smoke ,medicine ,media_common.cataloged_instance ,European union ,Cyanates ,NOx ,media_common ,Air Pollutants ,Carbon Monoxide ,Multidisciplinary ,Dose-Response Relationship, Drug ,Atmosphere ,Chemistry ,Temperature ,Hydrogen-Ion Concentration ,Isocyanic acid ,Carbon ,Solubility ,Environmental chemistry ,Physical Sciences ,Protons - Abstract
We measured isocyanic acid (HNCO) in laboratory biomass fires at levels up to 600 parts per billion by volume (ppbv), demonstrating that it has a significant source from pyrolysis/combustion of biomass. We also measured HNCO at mixing ratios up to 200 pptv (parts-per-trillion by volume) in ambient air in urban Los Angeles, CA, and in Boulder, CO, during the recent 2010 Fourmile Canyon fire. Further, our measurements of aqueous solubility show that HNCO is highly soluble, as it dissociates at physiological pH. Exposure levels > 1 ppbv provide a direct source of isocyanic acid and cyanate ion (NCO - ) to humans at levels that have recognized health effects: atherosclerosis, cataracts, and rheumatoid arthritis, through the mechanism of protein carbamylation. In addition to the wildland fire and urban sources, we observed HNCO in tobacco smoke, HNCO has been reported from the low-temperature combustion of coal, and as a by-product of urea-selective catalytic reduction (SCR) systems that are being phased-in to control on-road diesel NO x emissions in the United States and the European Union. Given the current levels of exposure in populations that burn biomass or use tobacco, the expected growth in biomass burning emissions with warmer, drier regional climates, and planned increase in diesel SCR controls, it is imperative that we understand the extent and effects of this HNCO exposure.
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- 2011
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29. VOC identification and inter-comparison from laboratory biomass burning using PTR-MS and PIT-MS
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Jessica B. Gilman, Patrick R. Veres, J. A. de Gouw, Carsten Warneke, William C. Kuster, Robert J. Yokelson, I. R. Burling, and J. M. Roberts
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Identification methods ,Calibration curve ,Chemistry ,Instrumentation ,Analytical chemistry ,Biomass ,Fraction (chemistry) ,Condensed Matter Physics ,Environmental chemistry ,Ion trap ,Physical and Theoretical Chemistry ,Fourier transform infrared spectroscopy ,Biomass burning ,Spectroscopy - Abstract
Volatile organic compounds (VOCs) emitted from fires of biomass commonly found in the southeast and southwest U.S. were investigated with PTR-MS and PIT-MS, which are capable of fast measurements of a large number of VOCs. Both instruments were calibrated with gas standards and mass dependent calibration curves are determined. The sensitivity of the PIT-MS linearly increases with mass, because the ion trap mass spectrometer used in PIT-MS is more efficient for higher masses, whereas the quadrupole in PTR-MS is most efficient around 70 amu. The identification of VOCs in the complicated mix of the fire emissions was done by gas chromatographic pre separation and inter-comparison with other instrumentation: GC–MS, FTIR, and NI-PT-CIMS. With these state of the art identification methods only 50–75% of the mass detectable by PTR-MS or PIT-MS could be identified. The amount of identified material was dependent on the type of fuel used and the phase of the burns, more can be identified in the flaming stage of the fire. Compounds with masses above 100 amu contributed the largest fraction of the unidentified mass. Emission ratios with CO for all identified and unidentified compounds were determined. Small oxygenated VOCs had the highest emission ratios of the observed compounds.
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- 2011
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30. Ozone production in remote oceanic and industrial areas derived from ship based measurements of peroxy radicals during TexAQS 2006
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J. A. de Gouw, A. E. Parker, Hans D. Osthoff, Steven S. Brown, D. Bon, Brian M. Lerner, D. M. Brookes, Gregory J. Frost, Jessica B. Gilman, Mark S. Zahniser, Eric J. Williams, William C. Kuster, Timothy S. Bates, Carsten Warneke, Paul S. Monks, Sara C. Tucker, Roberto Sommariva, Scott C. Herndon, Paul D. Goldan, and J. M. Roberts
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Atmospheric Science ,Ozone ,Radical ,Photodissociation ,Formaldehyde ,Wind direction ,lcsh:QC1-999 ,Research vessel ,lcsh:Chemistry ,chemistry.chemical_compound ,lcsh:QD1-999 ,chemistry ,Environmental chemistry ,Air quality index ,Nitrogen oxides ,lcsh:Physics - Abstract
During the Texas Air Quality Study II (TexAQS 2006) campaign, a PEroxy Radical Chemical Amplifier (PERCA) was deployed on the NOAA research vessel R/V Brown to measure total peroxy radicals (HO2+Σ RO2). Day-time mixing ratios of HO2+Σ RO2 between 25 and 110 ppt were observed throughout the study area – the Houston/Galveston region and the Gulf coast of the US – and analyzed in relation to measurements of nitrogen oxides, volatile organic compounds (VOC) and photolysis rates to assess radical sources and sinks in the region. The measurements of HO2+Σ RO2 were used to calculate the in-situ net photochemical formation of ozone. Measured median values ranged from 0.6 ppb/h in clean oceanic air masses up to several tens of ppb/h in the most polluted industrial areas. The results are consistent with previous studies and generally agree with observations made during the previous TexAQS 2000 field campaign. The net photochemical ozone formation rates determined at Barbours Cut, a site immediately south of the Houston Ship Channel, were analyzed in relation to local wind direction and VOC reactivity to understand the relationship between ozone formation and local VOC emissions. The measurements of HO2+Σ RO2 made during the R/V Brown TexAQS 2006 cruise indicate that ozone formation is NOx-limited in the Houston/Galveston region and influenced by highly reactive hydrocarbons, especially alkenes from urban and industrial sources and their photo-oxidation products, such as formaldehyde.
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- 2011
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31. The Chemistry of Atmosphere-Forest Exchange (CAFE) Model – Part 2: Application to BEARPEX-2007 observations
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Frank N. Keutsch, Joel A. Thornton, Kyung-Eun Min, Glenn M. Wolfe, John D. Crounse, Jeong-Hoo Park, M. McKay, Eleanor C. Browne, Jingqiu Mao, D. M. Matross, N. C. Bouvier-Brown, William C. Kuster, Jessica B. Gilman, Ian Faloona, Allen H. Goldstein, William H. Brune, Ronald C. Cohen, Brian W. LaFranchi, Paul J. Wooldridge, Andrew J. Huisman, and J. A. de Gouw
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Atmospheric Science ,Ozone ,Chemical transport model ,Reactive nitrogen ,Biosphere ,lcsh:QC1-999 ,lcsh:Chemistry ,Atmosphere ,chemistry.chemical_compound ,Flux (metallurgy) ,lcsh:QD1-999 ,chemistry ,Nitrate ,Environmental chemistry ,Deposition (chemistry) ,lcsh:Physics - Abstract
In a companion paper, we introduced the Chemistry of Atmosphere-Forest Exchange (CAFE) model, a vertically-resolved 1-D chemical transport model designed to probe the details of near-surface reactive gas exchange. Here, we apply CAFE to noontime observations from the 2007 Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX-2007). In this work we evaluate the CAFE modeling approach, demonstrate the significance of in-canopy chemistry for forest-atmosphere exchange and identify key shortcomings in the current understanding of intra-canopy processes. CAFE generally reproduces BEARPEX-2007 observations but requires an enhanced radical recycling mechanism to overcome a factor of 6 underestimate of hydroxyl (OH) concentrations observed during a warm (~29 °C) period. Modeled fluxes of acyl peroxy nitrates (APN) are quite sensitive to gradients in chemical production and loss, demonstrating that chemistry may perturb forest-atmosphere exchange even when the chemical timescale is long relative to the canopy mixing timescale. The model underestimates peroxy acetyl nitrate (PAN) fluxes by 50% and the exchange velocity by nearly a factor of three under warmer conditions, suggesting that near-surface APN sinks are underestimated relative to the sources. Nitric acid typically dominates gross dry N deposition at this site, though other reactive nitrogen (NOy) species can comprise up to 28% of the N deposition budget under cooler conditions. Upward NO2 fluxes cause the net above-canopy NOy flux to be ~30% lower than the gross depositional flux. CAFE under-predicts ozone fluxes and exchange velocities by ~20%. Large uncertainty in the parameterization of cuticular and ground deposition precludes conclusive attribution of non-stomatal fluxes to chemistry or surface uptake. Model-measurement comparisons of vertical concentration gradients for several emitted species suggests that the lower canopy airspace may be only weakly coupled with the upper canopy. Future efforts to model forest-atmosphere exchange will require a more mechanistic understanding of non-stomatal deposition and a more thorough characterization of in-canopy mixing processes.
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- 2011
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32. Ozone variability and halogen oxidation within the Arctic and sub-Arctic springtime boundary layer
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Eric J. Williams, William C. Kuster, L. Miller, P. C. Murphy, John F. Burkhart, Owen R. Cooper, Stephen A. Montzka, Paul D. Goldan, Carsten Warneke, Brian M. Lerner, Ben R. Miller, T. B. Ryerson, Jessica B. Gilman, J. A. de Gouw, C. Fowler, S. J. Oltmans, and Andreas Stohl
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Atmospheric Science ,geography ,geography.geographical_feature_category ,Ozone ,Planetary boundary layer ,Atmospheric sciences ,Arctic ice pack ,lcsh:QC1-999 ,Latitude ,Arctic geoengineering ,lcsh:Chemistry ,Boundary layer ,chemistry.chemical_compound ,lcsh:QD1-999 ,Arctic ,chemistry ,VDP::Mathematics and natural scienses: 400::Geosciences: 450::Meteorology: 453 ,Climatology ,Sea ice ,Environmental science ,VDP::Matematikk og naturvitenskap: 400::Geofag: 450::Meteorologi: 453 ,lcsh:Physics - Abstract
The influence of halogen oxidation on the variabilities of ozone (O3) and volatile organic compounds (VOCs) within the Arctic and sub-Arctic atmospheric boundary layer was investigated using field measurements from multiple campaigns conducted in March and April 2008 as part of the POLARCAT project. For the ship-based measurements, a high degree of correlation (r = 0.98 for 544 data points collected north of 68° N) was observed between the acetylene to benzene ratio, used as a marker for chlorine and bromine oxidation, and O3 signifying the vast influence of halogen oxidation throughout the ice-free regions of the North Atlantic. Concurrent airborne and ground-based measurements in the Alaskan Arctic substantiated this correlation and were used to demonstrate that halogen oxidation influenced O3 variability throughout the Arctic boundary layer during these springtime studies. Measurements aboard the R/V Knorr in the North Atlantic and Arctic Oceans provided a unique view of the transport of O3-poor air masses from the Arctic Basin to latitudes as far south as 52° N. FLEXPART, a Lagrangian transport model, was used to quantitatively determine the exposure of air masses encountered by the ship to first-year ice (FYI), multi-year ice (MYI), and total ICE (FYI+MYI). O3 anti-correlated with the modeled total ICE tracer (r = −0.86) indicating that up to 73% of the O3 variability measured in the Arctic marine boundary layer could be related to sea ice exposure.
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- 2010
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33. Development and validation of a portable gas phase standard generation and calibration system for volatile organic compounds
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J. A. de Gouw, Patrick R. Veres, I. R. Burling, William C. Kuster, J. M. Roberts, Carsten Warneke, and Jessica B. Gilman
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Total organic carbon ,Atmospheric Science ,lcsh:TA715-787 ,lcsh:Earthwork. Foundations ,Analytical chemistry ,chemistry.chemical_element ,Permeation ,Oxygen ,Methane ,lcsh:Environmental engineering ,chemistry.chemical_compound ,chemistry ,Calibration ,lcsh:TA170-171 ,Gas chromatography–mass spectrometry ,Benzene ,Palladium - Abstract
We report on the development of an accurate, portable, dynamic calibration system for volatile organic compounds (VOCs). The Mobile Organic Carbon Calibration System (MOCCS) combines the production of gas-phase VOC standards using permeation or diffusion sources with quantitative total organic carbon (TOC) conversion on a palladium surface to CO2 in the presence of oxygen, and the subsequent CO2 measurement. MOCCS was validated using three different comparisons: (1) TOC of high accuracy methane standards compared well to expected concentrations (3% relative error), (2) a gas-phase benzene standard was generated using a permeation source and measured by TOC and gas chromatography mass spectrometry (GC-MS) with excellent agreement (R2 of 0.91 and 0.99, respectively).
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- 2010
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34. Observational constraints on the global atmospheric budget of ethanol
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J. A. de Gouw, William C. Kuster, Vaishali Naik, Christine Wiedinmyer, Arlene M. Fiore, Paul D. Goldan, Dylan B. Millet, Allen H. Goldstein, Alex Guenther, Hanwant B. Singh, and Larry W. Horowitz
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chemistry.chemical_classification ,Atmospheric Science ,Atmospheric chemistry ,Ethanol ,Chemical transport model ,business.industry ,Fossil fuel ,Climatic changes ,lcsh:QC1-999 ,Troposphere ,lcsh:Chemistry ,chemistry.chemical_compound ,chemistry ,lcsh:QD1-999 ,Biofuel ,Atmosphere--Research ,Ethanol as fuel ,Environmental chemistry ,Hydroxyl radical ,Volatile organic compound ,business ,lcsh:Physics - Abstract
Energy security and climate change concerns have led to the promotion of biomass-derived ethanol, an oxygenated volatile organic compound (OVOC), as a substitute for fossil fuels. Although ethanol is ubiquitous in the troposphere, our knowledge of its current atmospheric budget and distribution is limited. Here, for the first time we use a global chemical transport model in conjunction with atmospheric observations to place constraints on the ethanol budget, noting that additional measurements of ethanol (and its precursors) are still needed to enhance confidence in our estimated budget. Global sources of ethanol in the model include 5.0 Tg yr−1 from industrial sources and biofuels, 9.2 Tg yr−1 from terrestrial plants, ~0.5 Tg yr−1 from biomass burning, and 0.05 Tg yr−1 from atmospheric reactions of the ethyl peroxy radical (C2H5O2) with itself and with the methyl peroxy radical (CH3O2). The resulting atmospheric lifetime of ethanol in the model is 2.8 days. Gas-phase oxidation by the hydroxyl radical (OH) is the primary global sink of ethanol in the model (65%), followed by dry deposition (25%), and wet deposition (10%). Over continental areas, ethanol concentrations predominantly reflect direct anthropogenic and biogenic emission sources. Uncertainty in the biogenic ethanol emissions, estimated at a factor of three, may contribute to the 50% model underestimate of observations in the North American boundary layer. Current levels of ethanol measured in remote regions are an order of magnitude larger than those in the model, suggesting a major gap in understanding. Stronger constraints on the budget and distribution of ethanol and OVOCs are a critical step towards assessing the impacts of increasing the use of ethanol as a fuel.
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- 2010
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35. Comparison of air pollutant emissions among mega-cities
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Yutaka Kondo, Makoto Koike, Min Shao, Paul D. Goldan, Joost A. de Gouw, Tomoko Shirai, Yoko Yokouchi, William C. Kuster, and D. D. Parrish
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chemistry.chemical_classification ,Atmospheric Science ,geography ,geography.geographical_feature_category ,Air pollution ,Environmental engineering ,medicine.disease_cause ,Urban area ,Atmospheric sciences ,chemistry.chemical_compound ,Megacity ,chemistry ,Beijing ,medicine ,Environmental science ,Volatile organic compound ,Nitrogen oxide ,Air quality index ,NOx ,General Environmental Science - Abstract
Ambient measurements of hydrocarbons, carbon monoxide and nitrogen oxides from three mega-cities (Beijing, Mexico City, Tokyo) are compared with similar measurements from US cities in the mid-1980s and the early 2000s. The common hydrocarbon pattern seen in all data sets suggests that emissions associated with gasoline-fueled vehicles dominate in all of these cities. This commonality suggests that it will be efficient and, ultimately, cost effective to proceed with vehicular emission controls in most emerging mega-cities, while proceeding with development of more locally appropriate air quality control strategies through emissions inventory development and ambient air monitoring. Over the three decades covered by the US data sets, the hydrocarbon emissions decreased by a significant factor (something like an order of magnitude), which is greater than suggested by emission inventories, particularly the EDGAR international inventory. The ambient hydrocarbon and CO concentrations reported for the three non-US mega-cities are higher than present US ambient concentrations, but lower than those observed in the 1980s in the US. The one exception to the preceding statement is the high concentrations of CO observed in Beijing, which apparently have a large regional contribution.
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- 2009
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36. In-situ ambient quantification of monoterpenes, sesquiterpenes, and related oxygenated compounds during BEARPEX 2007: implications for gas- and particle-phase chemistry
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William C. Kuster, N. C. Bouvier-Brown, Jessica B. Gilman, J. A. de Gouw, and Allen H. Goldstein
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Canopy ,Atmospheric Science ,chemistry.chemical_compound ,Tree canopy ,chemistry ,Linalool ,Environmental chemistry ,Monoterpene ,Atmospheric chemistry ,Mixing ratio ,Sesquiterpene ,Aerosol - Abstract
We quantified ambient mixing ratios of 9 monoterpenes, 6 sesquiterpenes, methyl chavicol, the oxygenated terpene linalool, and nopinone using an in-situ gas chromatograph with a quadrupole mass spectrometer (GC-MS). These measurements were a part of the 2007 Biosphere Effects on AeRosols and Photochemistry EXperiment (BEARPEX) at Blodgett Forest, a ponderosa pine forest in the Sierra Nevada Mountains of California. To our knowledge, these observations represent the first direct in-situ ambient quantification of the sesquiterpenes α-bergamotene, longifolene, α-farnesene, and β-farnesene. From average diurnal mixing ratio profiles, we show that α-farnesene emissions are dependent mainly on temperature whereas α-bergamotene and β-farnesene emissions are temperature- and light-dependent. The amount of sesquiterpene mass quantified above the canopy was small (averaging a total of 3.3 ppt during the day), but nevertheless these compounds contributed 7.6% to the overall ozone-olefin loss rate above the canopy. Assuming that the monoterpene-to-sesquiterpene emission rate in the canopy is similar to that observed in branch enclosure studies at the site during comparable weather conditions, and the average yield of aerosol mass from these sesquiterpenes is 10–50%, the amount of sesquiterpene mass reacted within the Blodgett Forest canopy alone accounts for 6–32% of the total organic aerosol mass measured during BEARPEX. The oxygenated monoterpene linalool was also quantified for the first time at Blodgett Forest. The linalool mass contribution was small (9.9 ppt and 0.74 ppt within and above the canopy, respectively), but it contributed 1.1% to the total ozone-olefin loss rate above the canopy. Reactive and semi-volatile compounds, especially sesquiterpenes, significantly impact the gas- and particle-phase chemistry of the atmosphere at Blodgett Forest and should be included in both biogenic volatile organic carbon emission and atmospheric chemistry models.
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- 2009
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37. Emission and chemistry of organic carbon in the gas and aerosol phase at a sub-urban site near Mexico City in March 2006 during the MILAGRO study
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D. R. Worsnop, Carsten Warneke, D. Welsh-Bon, Amy P. Sullivan, Rahul A. Zaveri, O. Vargas, A. Baker, Timothy B. Onasch, Alejandro Salcido, W. Junkermann, Donald R. Blake, A. T. Celada, Andreas J. Beyersdorf, David J. Tanner, J. A. de Gouw, S. J. Sjostedt, Xiao-Ying Yu, Manjula R. Canagaratna, L. Alexander, Rodney J. Weber, William C. Kuster, and L. G. Huey
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Alkane ,chemistry.chemical_classification ,Total organic carbon ,Atmospheric Science ,Levoglucosan ,chemistry.chemical_element ,Aerosol ,Atmosphere ,chemistry.chemical_compound ,Hydrocarbon ,chemistry ,Environmental chemistry ,Milagro ,Carbon - Abstract
Volatile organic compounds (VOCs) and carbonaceous aerosol were measured at a sub-urban site near Mexico City in March of 2006 during the MILAGRO study (Megacity Initiative: Local and Global Research Objectives). Diurnal variations of hydrocarbons, elemental carbon (EC) and hydrocarbon-like organic aerosol (HOA) were dominated by a high peak in the early morning when local emissions accumulated in a shallow boundary layer, and a minimum in the afternoon when the emissions were diluted in a significantly expanded boundary layer and, in case of the reactive gases, removed by OH. In comparison, diurnal variations of species with secondary sources such as the aldehydes, ketones, oxygenated organic aerosol (OOA) and water-soluble organic carbon (WSOC) stayed relatively high in the afternoon indicating strong photochemical formation. Emission ratios of many hydrocarbon species relative to CO were higher in Mexico City than in the U.S., but we found similar emission ratios for most oxygenated VOCs and organic aerosol. Secondary formation of acetone may be more efficient in Mexico City than in the U.S., due to higher emissions of alkane precursors from the use of liquefied petroleum gas. Secondary formation of organic aerosol was similar between Mexico City and the U.S. Combining the data for all measured gas and aerosol species, we describe the budget of total observed organic carbon (TOOC), and find that the enhancement ratio of TOOC relative to CO is conserved between the early morning and mid afternoon despite large compositional changes. Finally, the influence of biomass burning is investigated using the measurements of acetonitrile, which was found to correlate with levoglucosan in the particle phase. Diurnal variations of acetonitrile indicate a contribution from local burning sources. Scatter plots of acetonitrile versus CO suggest that the contribution of biomass burning to the enhancement of most gas and aerosol species was not dominant and perhaps not dissimilar from observations in the U.S.
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- 2009
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38. Radicals in the marine boundary layer during NEAQS 2004: a model study of day-time and night-time sources and sinks
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Hans D. Osthoff, A. R. Ravishankara, J. A. de Gouw, Tahllee Baynard, Eric J. Williams, William C. Kuster, Harald Stark, Brian M. Lerner, Timothy S. Bates, Paul D. Goldan, Steven S. Brown, Fred C. Fehsenfeld, Roberto Sommariva, Derek J. Coffman, Michael Trainer, and Carsten Warneke
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Atmospheric Science ,geography ,geography.geographical_feature_category ,Marine boundary layer ,Radical ,Sink (geography) ,Aerosol ,chemistry.chemical_compound ,Nitrate ,chemistry ,Environmental chemistry ,Spectroscopy ,Air quality index ,NOx - Abstract
This paper describes a modelling study of several HOx and NOx species (OH, HO2, organic peroxy radicals, NO3 and N2O5) in the marine boundary layer. A model based upon the Master Chemical Mechanism (MCM) was constrained to observations of chemical and physical parameters made onboard the NOAA ship R/V Brown as part of the New England Air Quality Study (NEAQS) in the summer of 2004. The model was used to calculate [OH] and to determine the composition of the peroxy radical pool. Modelled [NO3] and [N2O5] were compared to in-situ measurements by Cavity Ring-Down Spectroscopy. The comparison showed that the model generally overestimated the measurements by 30–50%, on average. The model results were analyzed with respect to several chemical and physical parameters, including uptake of NO3 and N2O5 on fog droplets and on aerosol, dry deposition of NO3 and N2O5, gas-phase hydrolysis of N2O5 and reactions of NO3 with NMHCs and peroxy radicals. The results suggest that fog, when present, is an important sink for N2O5 via rapid heterogeneous uptake. The comparison between the model and the measurements were consistent with values of the heterogeneous uptake coefficient of N2O5 (γN2O5)>1×10−2, independent of aerosol composition in this marine environment. The analysis of the different loss processes of the nitrate radical showed the important role of the organic peroxy radicals, which accounted for a significant fraction (median: 15%) of NO3 gas-phase removal, particularly in the presence of high concentrations of dimethyl sulphide (DMS).
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- 2009
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39. Source Identification of Reactive Hydrocarbons and Oxygenated VOCs in the Summertime in Beijing
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Sihua Lu, Ying Liu, William C. Kuster, Xiaohua Li, Min Shao, Joost A. de Gouw, and Paul D. Goldan
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China ,Time Factors ,Ozone ,Rain ,Acetaldehyde ,Wind ,chemistry.chemical_compound ,Hemiterpenes ,Beijing ,Pentanes ,Butadienes ,Environmental Chemistry ,Isoprene ,Air mass ,Volatile Organic Compounds ,Primary (chemistry) ,Hydroxyl Radical ,Methanol ,Temperature ,Humidity ,General Chemistry ,Butanones ,Hydrocarbons ,Oxygen ,chemistry ,Environmental chemistry ,Seasons - Abstract
It is important to identify the sources of reactive volatile organic compounds (VOCs) in Beijing for effective ground-level ozone abatement. In this paper, semihourly measurements of hydrocarbons and oxygenated VOCs (OVOCs) were taken at an urban site in Beijing in August2005. C2-C5 alkenes, isoprene, and C1-C3 aldehydes were determined as "key reactive species" by their OH loss rates. Principal component analysis (PCA) was used to define the major sources of reactive species and to classify the dominant air mass types at the sampling site. Vehicle exhaust was the largest contributor to reactive alkenes. More aged air masses with enriched OVOCs traveled mainly from the east or southeast of Beijing. The OVOC sources were estimated by a least-squares fit approach and included primary emissions, secondary sources, and background. Approximately half of the C1-C3 aldehydes were attributed to secondary sources, while regional background accounted for 21-23% of the mixing ratios of aldehydes. Primary anthropogenic emissions were comparable to biogenic contributions (10-16%).
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- 2008
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40. A study of organic nitrates formation in an urban plume using a Master Chemical Mechanism
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Fred C. Fehsenfeld, Roberto Sommariva, Michael Trainer, Carsten Warneke, Frank Flocke, Aaron L. Swanson, Paul D. Goldan, Joost A. de Gouw, Elliot Atlas, James M. Roberts, and William C. Kuster
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chemistry.chemical_classification ,Alkane ,Atmospheric Science ,chemistry ,Inorganic chemistry ,Mineralogy ,Alkyl ,General Environmental Science ,City area ,Organic nitrates ,Plume - Abstract
Secondary organic chemistry inside a typical urban plume in the North-East of the United States has been studied using a highly detailed chemical model, based upon the Master Chemical Mechanism (MCM). The model results have been qualitatively compared to measurements taken during three flights of the NOAA WP-3D aircraft, which sampled a plume from the New York City area during the NEAQS 2004 campaign. The model has been used to study the formation processes and photochemical evolution of alkyl nitrates. While long-chain (C5) alkyl nitrates are produced for 90% or more from the oxidation of a single parent alkane, short-chain ( C 4 ) alkyl nitrates can be formed from several precursors. The relative importance of each production route has been quantitatively determined thanks to the high level of chemical detail provided by the MCM. These secondary routes to the formation of alkyl nitrates include the oxidation of longer-chain alkanes and oxygenated intermediates, like carbonyls, peroxides and carboxylic acids.
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- 2008
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41. Source Apportionment of Ambient Volatile Organic Compounds in Beijing
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Min Shao, Ying Liu, Sihua Lu, Shaodong Xie, Yu Song, William C. Kuster, and Paul D. Goldan
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China ,Chromatography, Gas ,Ozone ,Air pollution ,medicine.disease_cause ,Liquefied petroleum gas ,Mass Spectrometry ,chemistry.chemical_compound ,Diesel fuel ,Natural gas ,medicine ,Environmental Chemistry ,Volatile organic compound ,Tropospheric ozone ,Air quality index ,Vehicle Emissions ,Flame Ionization ,chemistry.chemical_classification ,Air Pollutants ,business.industry ,Environmental engineering ,General Chemistry ,chemistry ,Environmental chemistry ,Environmental science ,Volatilization ,business ,Environmental Monitoring - Abstract
The ambient air quality standard for ozone is frequently exceeded in Beijing in summer and autumn. Source apportionments of volatile organic compounds (VOCs), which are precursors of ground-level ozone formation, can be helpful to the further study of tropospheric ozone formation. In this study, ambient concentrations of VOCs were continuously measured with a time resolution of 30 min in August 2005 in Beijing. By using positive matrix factorization (PMF), eight sources for the selected VOC species were extracted. Gasoline-related emissions (the combination of gasoline exhaust and gas vapor), petrochemicals, and liquefied petroleum gas (LPG) contributed 52, 20, and 11%, respectively, to total ambient VOCs. VOC emissions from natural gas (5%), painting (5%), diesel vehicles (3%), and biogenic emissions (2%) were also identified. The gasoline-related, petrochemical, and biogenic sources were estimated to be the major contributors to ozone formation potentials in Beijing.
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- 2007
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42. Biomass burning emissions and potential air quality impacts of volatile organic compounds and other trace gases from temperate fuels common in the United States
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J. A. de Gouw, Patrick R. Veres, Robert J. Yokelson, I. R. Burling, William C. Kuster, Carsten Warneke, J. M. Roberts, Paul D. Goldan, Jessica B. Gilman, and Brian M. Lerner
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Environmental chemistry ,Temperate climate ,Environmental science ,Biomass burning ,Air quality index ,Trace gas - Abstract
A comprehensive suite of instruments was used to quantify the emissions of over 200 organic gases, including methane and volatile organic compounds (VOCs), and 9 inorganic gases from 56 laboratory burns of 18 different biomass fuel types common in the southeastern, southwestern, or northern United States. A gas chromatograph-mass spectrometer (GC-MS) provided extensive chemical detail of discrete air samples collected during a laboratory burn and was complemented by real-time measurements of organic and inorganic species via an open-path Fourier transform infrared spectrometer (OP-FTIR) and 3 different chemical ionization-mass spectrometers. These measurements were conducted in February 2009 at the U.S. Department of Agriculture's Fire Sciences Laboratory in Missoula, Montana. The relative magnitude and composition of the gases emitted varied by individual fuel type and, more broadly, by the 3 geographic fuel regions being simulated. Emission ratios relative to carbon monoxide (CO) were used to characterize the composition of gases emitted by mass; reactivity with the hydroxyl radical, OH; and potential secondary organic aerosol (SOA) precursors for the 3 different US fuel regions presented here. VOCs contributed less than 0.78 ± 0.12 % of emissions by mole and less than 0.95 ± 0.07 % of emissions by mass (on average) due to the predominance of CO2, CO, CH4, and NOx emissions; however, VOCs contributed 70–90 (±16) % to OH reactivity and were the only measured gas-phase source of SOA precursors from combustion of biomass. Over 82 % of the VOC emissions by mole were unsaturated compounds including highly reactive alkenes and aromatics and photolabile oxygenated VOCs (OVOCs) such as formaldehyde. OVOCs contributed 57–68 % of the VOC mass emitted, 42–57 % of VOC-OH reactivity, and aromatic-OVOCs such as benzenediols, phenols, and benzaldehyde were the dominant potential SOA precursors. In addition, ambient air measurements of emissions from the Fourmile Canyon Fire that affected Boulder, Colorado in September 2010 allowed us to investigate biomass burning (BB) emissions in the presence of other VOC sources (i.e., urban and biogenic emissions) and identify several promising BB markers including benzofuran, 2-furaldehyde, 2-methylfuran, furan, and benzonitrile.
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- 2015
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43. Cluster Analysis of the Organic Peaks in Bulk Mass Spectra Obtained During the 2002 New England Air Quality Study with an Aerodyne Aerosol Mass Spectrometer
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Brian M. Lerner, Paul D. Goldan, J. M. Roberts, Fred C. Fehsenfeld, Manjula R. Canagaratna, Ann M. Middlebrook, J. F. Meagher, Roya Bahreini, Carsten Warneke, Claudia Marcolli, Eric J. Williams, William C. Kuster, Steven B. Bertman, Doug Worsnop, J. A. de Gouw, and M. Marchewka
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chemistry.chemical_classification ,Atmospheric Science ,010504 meteorology & atmospheric sciences ,Analytical chemistry ,Mineralogy ,010501 environmental sciences ,Mass spectrometry ,01 natural sciences ,lcsh:QC1-999 ,Aerosol ,Trace gas ,lcsh:Chemistry ,chemistry.chemical_compound ,lcsh:QD1-999 ,chemistry ,13. Climate action ,Mass spectrum ,Cluster (physics) ,Organic matter ,Air quality index ,lcsh:Physics ,Isoprene ,0105 earth and related environmental sciences - Abstract
We applied hierarchical cluster analysis to an Aerodyne aerosol mass spectrometer (AMS) bulk mass spectral dataset collected aboard the NOAA research vessel R. H. Brown during the 2002 New England Air Quality Study off the east coast of the United States. Emphasizing the organic peaks, the cluster analysis yielded a series of categories that are distinguishable with respect to their mass spectra and their occurrence as a function of time. The differences between the categories mainly arise from relative intensity changes rather than from the presence or absence of specific peaks. The most frequent category exhibits a strong signal at m/z 44 and represents oxidized organic matter probably originating from both anthropogenic as well as biogenic sources. On the basis of spectral and trace gas correlations, the second most common category with strong signals at m/z 29, 43, and 44 contains contributions from isoprene oxidation products. The third through the fifth most common categories have peak patterns characteristic of monoterpene oxidation products and were most frequently observed when air masses from monoterpene rich regions were sampled. Taken together, the second through the fifth most common categories represent on average 17% of the total organic mass that stems likely from biogenic sources during the ship's cruise. These numbers have to be viewed as lower limits since the most common category was attributed to anthropogenic sources for this calculation. The cluster analysis was also very effective in identifying a few contaminated mass spectra that were not removed during pre-processing. This study demonstrates that hierarchical clustering is a useful tool to analyze the complex patterns of the organic peaks in bulk aerosol mass spectra from a field study., Atmospheric Chemistry and Physics, 6 (12), ISSN:1680-7375, ISSN:1680-7367
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- 2006
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44. Development of proton-transfer ion trap-mass spectrometry: on-line detection and identification of volatile organic compounds in air
- Author
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J. A. de Gouw, Ray Fall, P. C. Murphy, Edward R. Lovejoy, William C. Kuster, and Carsten Warneke
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Detection limit ,chemistry.chemical_classification ,010504 meteorology & atmospheric sciences ,Chemistry ,010401 analytical chemistry ,Analytical chemistry ,Mass spectrometry ,01 natural sciences ,0104 chemical sciences ,Trace gas ,Ion ,13. Climate action ,Structural Biology ,11. Sustainability ,Mass spectrum ,Volatile organic compound ,Ion trap ,Quadrupole mass analyzer ,Spectroscopy ,0105 earth and related environmental sciences - Abstract
We present a newly developed instrument that uses proton-transfer ion trap-mass spectrometry (PIT-MS) for on-line trace gas analysis of volatile organic compounds (VOCs). The instrument is based on the principle of proton-transfer reaction-mass spectrometry (PTR-MS): VOCs are ionized using PTRs and detected with a mass spectrometer. As opposed to a quadrupole mass filter in a PTR-MS, the PIT-MS instrument uses an IT-MS, which has the following advantages: (1) the ability to acquire a full mass spectrum in the same time as one mass with a quadrupole and (2) extended analytical capabilities of identifying VOCs by performing collision-induced dissociation (CID) and ion molecule reactions in the IT. The instrument described has, at its current status, limits of detection between 0.05 and 0.5 pbbv for 1-min measurements for all tested VOCs. The PIT-MS was tested in an ambient air measurement in the urban area of Boulder, Colorado, and intercompared with PTR-MS. For all measured compounds the degree of correlation between the two measurements was high (r2 > 0.85), except for acetonitrile (CH3CN), which was close to the limit of detection of the PIT-MS instrument. The two measurements agreed within less than 25%, which was within the combined measurement uncertainties. Automated CID measurements on m/z 59 during the intercomparison were used to determine the contributions of acetone and propanal to the measured signal; both are detected at m/z 59 and thus are indistinguishable in PTR-MS. It was determined that m/z 59 was mainly composed of acetone. An influence of propanal was detected only during a high pollution event. The advantages and future developments of PIT-MS are discussed.
- Published
- 2005
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45. Inter-comparison of Laser Photoacoustic Spectroscopy and Gas Chromatography Techniques for Measurements of Ethene in the Atmosphere
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William C. Kuster, Frans J. M. Harren, and Joost A. de Gouw
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Flame Ionization ,Detection limit ,Absorption spectroscopy ,Atmosphere ,Chemistry ,Lasers ,Spectrum Analysis ,Analytical chemistry ,General Chemistry ,Ethylenes ,Laser ,Chemistry Techniques, Analytical ,law.invention ,Wavelength ,law ,Environmental Chemistry ,Flame ionization detector ,Molecular and Laser Physics ,Gas chromatography ,Photoacoustic spectroscopy ,Environmental Monitoring - Abstract
Laser photoacoustic spectroscopy (LPAS) is highly suitable for the detection of ethene in air due to the overlap between its strongest absorption lines and the wavelengths accessible by high-powered CO2 lasers. Here, we test the ability of LPAS to measure ethene in ambient air by comparing the measurements in urban air with those from a gas chromatography flame-ionization detection (GC-FID) instrument. Over the course of several days, we obtained quantitative agreement between the two measurements. Over this period, the LPAS instrument had a positive offset of 330 +/- 140 pptv (parts-per-trillion by volume) relative to the GC-FID instrument, possibly caused by interference from other species. The detection limit of the LPAS instrument is currently estimated around 1 ppbv and is limited by this offset and the statistical noise in the data. We conclude that LPAS has the potential to provide fast-response measurements of ethene in the atmosphere, with significant advantages over existing techniques when measuring from moving platforms and in the vicinity of emission sources.
- Published
- 2005
- Full Text
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46. Temporal Changes in U.S. Benzene Emissions Inferred from Atmospheric Measurements
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Robert A. Harley, Tara J. Fortin, Eliot L. Atlas, David D. Parrish, Paul D. Goldan, William C. Kuster, and Benjamin J. Howard
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Pollutant ,chemistry.chemical_classification ,Air Pollutants ,Atmosphere ,Environmental engineering ,Air pollution ,Benzene ,General Chemistry ,Photochemical Assessment Monitoring Station ,medicine.disease_cause ,Atmospheric sciences ,United States ,chemistry.chemical_compound ,Trend analysis ,chemistry ,medicine ,Environmental Chemistry ,Environmental science ,Volatile organic compound ,Seasons ,Clean Air Act ,Air quality index ,Environmental Monitoring - Abstract
The 1990 Clean Air Act Amendments required the United States Environmental Protection Agency (U.S. EPA) to enact stricter regulations aimed at reducing benzene emissions. In an effort to determine whether these new regulations have been successful in reducing atmospheric benzene concentrations, we have evaluated benzene-to-acetylene ratios from data sets spanning nearly three decades, collected during several field studies and from the U.S. EPA's Photochemical Assessment Monitoring Station (PAMS) network. The field-study data indicate a decrease in benzene relative to acetylene of approximately 40% from 1994 to 2002. This corresponds to a decrease in benzene alone of approximately 56% over the same period. In contrast, the PAMS data exhibit high interannual variability with no discernible trend. This discrepancy is attributed to measurement problems in the PAMS data sets.
- Published
- 2005
- Full Text
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47. Proton-Transfer-Reaction Mass Spectrometry as a New Tool for Real Time Analysis of Root-Secreted Volatile Organic Compounds in Arabidopsis
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Jorge M. Vivanco, Ray Fall, Harsh P. Bais, Marco Steeghs, Joost A. de Gouw, Paul D. Goldan, Megan Northway, and William C. Kuster
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Exudate ,Insecta ,Physiology ,Arabidopsis ,Plant Science ,Plant Roots ,Gas Chromatography-Mass Spectrometry ,Mass Spectrometry ,Acetic acid ,chemistry.chemical_compound ,Computer Systems ,Botany ,Genetics ,medicine ,Pseudomonas syringae ,Animals ,Organic Chemicals ,Proton-transfer-reaction mass spectrometry ,Plant Diseases ,Rhizosphere ,Eucalyptol ,Bacteria ,biology ,Fungi ,Acetaldehyde ,Breakthrough Technologies ,Cyclohexanols ,biology.organism_classification ,Immunity, Innate ,chemistry ,Monoterpenes ,Molecular and Laser Physics ,Stress, Mechanical ,Protons ,Volatilization ,Gas chromatography–mass spectrometry ,medicine.symptom - Abstract
Plant roots release about 5% to 20% of all photosynthetically-fixed carbon, and as a result create a carbon-rich environment for numerous rhizosphere organisms, including plant pathogens and symbiotic microbes. Although some characterization of root exudates has been achieved, especially of secondary metabolites and proteins, much less is known about volatile organic compounds (VOCs) released by roots. In this communication, we describe a novel approach to exploring these rhizosphere VOCs and their induction by biotic stresses. The VOC formation of Arabidopsis roots was analyzed using proton-transfer-reaction mass spectrometry (PTR-MS), a new technology that allows rapid and real time analysis of most biogenic VOCs without preconcentration or chromatography. Our studies revealed that the major VOCs released and identified by both PTR-MS and gas chromatography-mass spectrometry were either simple metabolites, ethanol, acetaldehyde, acetic acid, ethyl acetate, 2-butanone, 2,3,-butanedione, and acetone, or the monoterpene, 1,8-cineole. Some VOCs were found to be produced constitutively regardless of the treatment; other VOCs were induced specifically as a result of different compatible and noncompatible interactions between microbes and insects and Arabidopsis roots. Compatible interactions of Pseudomonas syringae DC3000 and Diuraphis noxia with Arabidopsis roots resulted in the rapid release of 1,8-cineole, a monoterpene that has not been previously reported in Arabidopsis. Mechanical injuries to Arabidopsis roots did not produce 1,8-cineole nor any C6 wound-VOCs; compatible interactions between Arabidopsis roots and Diuraphis noxia did not produce any wound compounds. This suggests that Arabidopsis roots respond to wounding differently from above-ground plant organs. Trials with incompatible interactions did not reveal a set of compounds that was significantly different compared to the noninfected roots. The PTR-MS method may open the way for functional root VOC analysis that will complement genomic investigations in Arabidopsis.
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- 2004
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48. Validation of Atmospheric VOC Measurements by Proton-Transfer- Reaction Mass Spectrometry Using a Gas-Chromatographic Preseparation Method
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Joost A. de Gouw, Carsten Warneke, Paul D. Goldan, William C. Kuster, and Ray Fall
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chemistry.chemical_classification ,Air Pollutants ,Chromatography ,Volatilisation ,Analytical chemistry ,General Chemistry ,Mass spectrometry ,Toluene ,Gas Chromatography-Mass Spectrometry ,chemistry.chemical_compound ,chemistry ,Environmental Chemistry ,Volatile organic compound ,Gas chromatography ,Organic Chemicals ,Protons ,Volatilization ,Gas chromatography–mass spectrometry ,Benzene ,Proton-transfer-reaction mass spectrometry ,Environmental Monitoring - Abstract
Proton-transfer-reaction mass spectrometry (PTR-MS) has emerged as a useful tool to study volatile organic compounds (VOCs) in the atmosphere. In PTR-MS, proton-transfer reactions with H30+ ions are used to ionize and measure VOCs in air with a high sensitivity and fast time response. Only the masses of the ionized VOCs and their fragments, if any, are determined, and these product ions are not unique indicators of VOC identities. Here, a combination of gas chromatography and PTR-MS (GC-PTR-MS) is used to validate the measurements by PTR-MS of a number of common atmospheric VOCs. We have analyzed 75 VOCs contained in standard mixtures by GC-PTR-MS, which allowed detected masses to be unambiguously related to a specific compound. The calibration factors for PTR-MS and GC-PTR-MS were compared and showed that the loss of VOCs in the sample acquisition and GC system is small. GC-PTR-MS analyses of 56 air samples from an urban site were used to address the specificity of PTR-MS in complex air masses. It is demonstrated that the ions associated with methanol, acetonitrile, acetaldehyde, acetone, benzene, toluene, and higher aromatic VOCs are free from significant interference. A quantitative intercomparison between PTR-MS and GC-PTR-MS measurements of the aforementioned VOCs was performed and shows that they are accurately measured by PTR-MS.
- Published
- 2003
- Full Text
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49. Ground-based intercomparison of two isoprene measurement techniques
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Paul D. Goldan, Fred C. Fehsenfeld, E. Leibrock, L. G. Huey, Eric J. Williams, and William C. Kuster
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Atmospheric Science ,chemistry.chemical_compound ,Chemical ionization ,chemistry ,Environmental chemistry ,Ionization ,Analytical chemistry ,Benzene ,Mass spectrometric ,Isoprene - Abstract
An informal intercomparison of two isoprene (C5H8) measurement techniques was carried out during Fall of 1998 at a field site located approximately 3 km west of Boulder, Colorado, USA. A new chemical ionization mass spectrometric technique (CIMS) was compared to a well-established gas chromatographic technique (GC). The CIMS technique utilized benzene cation chemistry to ionize isoprene. The isoprene levels measured by the CIMS were often larger than those obtained with the GC. The results indicate that the CIMS technique suffered from an anthropogenic interference associated with air masses from the Denver, CO metropolitan area as well as an additional interference occurring in clean conditions. However, the CIMS technique is also demonstrated to be sensitive and fast. Especially after introduction of a tandem mass spectrometric technique, it is therefore a candidate for isoprene measurements in remote environments near isoprene sources.
- Published
- 2003
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50. Investigation of secondary formation of formic acid: urban environment vs. oil and gas producing region
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Rodney J. Weber, Barry Lefer, James E. Johnson, J. M. Roberts, Bin Yuan, William P. Dubé, Robert Wild, J. A. de Gouw, Jose L. Jimenez, Jessica B. Gilman, Shao-Meng Li, Bernhard Rappenglück, Barbara Ervens, Steven S. Brown, Dylan B. Millet, Patrick R. Veres, Carsten Warneke, Timothy S. Bates, Patrick L. Hayes, Martin Graus, Abigail R. Koss, Brian M. Lerner, Robert J. Zamora, Peter Edwards, Patricia K. Quinn, Eric J. Williams, and William C. Kuster
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Atmospheric Science ,Aqueous solution ,Ozonolysis ,Ozone ,Formic acid ,Inorganic chemistry ,Formaldehyde ,lcsh:QC1-999 ,lcsh:Chemistry ,chemistry.chemical_compound ,chemistry ,Acetylene ,lcsh:QD1-999 ,mental disorders ,Acetone ,Isoprene ,lcsh:Physics - Abstract
Formic acid (HCOOH) is one of the most abundant carboxylic acids in the atmosphere. However, current photochemical models cannot fully explain observed concentrations and in particular secondary formation of formic acid across various environments. In this work, formic acid measurements made at an urban receptor site (Pasadena) in June–July 2010 during CalNex (California Research at the Nexus of Air Quality and Climate Change) and a site in an oil and gas producing region (Uintah Basin) in January–February 2013 during UBWOS 2013 (Uintah Basin Winter Ozone Studies) will be discussed. Although the VOC (volatile organic compounds) compositions differed dramatically at the two sites, measured formic acid concentrations were comparable: 2.3 ± 1.3 in UBWOS 2013 and 2.0 ± 1.0 ppb in CalNex. We determine that concentrations of formic acid at both sites were dominated by secondary formation (> 99%). A constrained box model using the Master Chemical Mechanism (MCM v3.2) underestimates the measured formic acid concentrations drastically at both sites (by a factor of > 10). Compared to the original MCM model that includes only ozonolysis of unsaturated organic compounds and OH oxidation of acetylene, when we updated yields of ozonolysis of alkenes and included OH oxidation of isoprene, vinyl alcohol chemistry, reaction of formaldehyde with HO2, oxidation of aromatics, and reaction of CH3O2 with OH, the model predictions for formic acid were improved by a factor of 6.4 in UBWOS 2013 and 4.5 in CalNex, respectively. A comparison of measured and modeled HCOOH/acetone ratios is used to evaluate the model performance for formic acid. We conclude that the modified chemical mechanism can explain 19 and 45% of secondary formation of formic acid in UBWOS 2013 and CalNex, respectively. The contributions from aqueous reactions in aerosol and heterogeneous reactions on aerosol surface to formic acid are estimated to be 0–6 and 0–5% in UBWOS 2013 and CalNex, respectively. We observe that air–snow exchange processes and morning fog events may also contribute to ambient formic acid concentrations during UBWOS 2013 (~ 20% in total). In total, 53–59 in UBWOS 2013 and 50–55% in CalNex of secondary formation of formic acid remains unexplained. More work on formic acid formation pathways is needed to reduce the uncertainties in the sources and budget of formic acid and to narrow the gaps between measurements and model results.
- Published
- 2014
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