[ { "id": "authors:cb84p-vye63", "collection": "authors", "collection_id": "cb84p-vye63", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190529-082821644", "type": "article", "title": "450 d of Type II SN 2013ej in optical and near-infrared", "author": [ { "family_name": "Yuan", "given_name": "Fang", "clpid": "Yuan-Fang" }, { "family_name": "Jerkstrand", "given_name": "A.", "clpid": "Jerkstrand-A" }, { "family_name": "Valenti", "given_name": "S.", "orcid": "0000-0001-8818-0795", "clpid": "Valenti-S" }, { "family_name": "Sollerman", "given_name": "J.", "orcid": "0000-0003-1546-6615", "clpid": "Sollerman-J" }, { "family_name": "Seitenzahl", "given_name": "I. R.", "clpid": "Seitenzahl-I-R" }, { "family_name": "Pastorello", "given_name": "A.", "clpid": "Pastorello-A" }, { "family_name": "Schulze", "given_name": "S.", "orcid": "0000-0001-6797-1889", "clpid": "Schulze-S" }, { "family_name": "Chen", "given_name": "T.-W.", "orcid": "0000-0002-1066-6098", "clpid": "Chen-Ting-Wan" }, { "family_name": "Childress", "given_name": "M. J.", "clpid": "Childress-M-J" }, { "family_name": "Fraser", "given_name": "M.", "clpid": "Fraser-M-P" }, { "family_name": "Fremling", "given_name": "C.", "orcid": "0000-0002-4223-103X", "clpid": "Fremling-C" }, { "family_name": "Kotak", "given_name": "R.", "orcid": "0000-0001-5455-3653", "clpid": "Kotak-R" }, { "family_name": "Ruiter", "given_name": "A. J.", "clpid": "Ruiter-A-J" }, { "family_name": "Schmidt", "given_name": "B. P.", "orcid": "0000-0001-6589-1287", "clpid": "Schmidt-B-P" }, { "family_name": "Smartt", "given_name": "S. J.", "orcid": "0000-0002-8229-1731", "clpid": "Smartt-S-J" }, { "family_name": "Taddia", "given_name": "F.", "orcid": "0000-0002-2387-6801", "clpid": "Taddia-F" }, { "family_name": "Terreran", "given_name": "G.", "clpid": "Terreran-G" }, { "family_name": "Tucker", "given_name": "B. E.", "clpid": "Tucker-B-E" }, { "family_name": "Barbarino", "given_name": "C.", "orcid": "0000-0002-3821-6144", "clpid": "Barbarino-C" }, { "family_name": "Benetti", "given_name": "S.", "orcid": "0000-0002-3256-0016", "clpid": "Benetti-S" }, { "family_name": "Elias-Rosa", "given_name": "N.", "orcid": "0000-0002-1381-9125", "clpid": "Elias-Rosa-N" }, { "family_name": "Gal-Yam", "given_name": "A.", "orcid": "0000-0002-3653-5598", "clpid": "Gal-Yam-A" }, { "family_name": "Howell", "given_name": "D. A.", "orcid": "0000-0003-4253-656X", "clpid": "Howell-D-A" }, { "family_name": "Inserra", "given_name": "C.", "orcid": "0000-0002-3968-4409", "clpid": "Inserra-C" }, { "family_name": "Kankare", "given_name": "E.", "orcid": "0000-0001-8257-3512", "clpid": "Kankare-E" }, { "family_name": "Lee", "given_name": "M. Y.", "clpid": "Lee-M-Y" }, { "family_name": "Li", "given_name": "K. L.", "orcid": "0000-0001-8229-2024", "clpid": "Li-Kwan-Lok" }, { "family_name": "Maguire", "given_name": "K.", "orcid": "0000-0002-9770-3508", "clpid": "Maguire-K" }, { "family_name": "Margheim", "given_name": "S.", "clpid": "Margheim-S" }, { "family_name": "Mehner", "given_name": "A.", "orcid": "0000-0002-9564-3302", "clpid": "Mehner-A" }, { "family_name": "Ochner", "given_name": "P.", "clpid": "Ochner-P" }, { "family_name": "Sullivan", "given_name": "M.", "orcid": "0000-0001-9053-4820", "clpid": "Sullivan-Mark" }, { "family_name": "Tomasella", "given_name": "L.", "clpid": "Tomasella-L" }, { "family_name": "Young", "given_name": "D. R.", "clpid": "Young-D-R" } ], "abstract": "We present optical and near-infrared photometric and spectroscopic observations of SN 2013ej, in galaxy M74, from 1 to 450\u2009d after the explosion. SN 2013ej is a hydrogen-rich supernova, classified as a Type IIL due to its relatively fast decline following the initial peak. It has a relatively high peak luminosity (absolute magnitude MV = \u221217.6) but a small ^(56)Ni production of \u223c0.023 M\u2299. Its photospheric evolution is similar to other Type II SNe, with shallow absorption in the H_\u03b1 profile typical for a Type IIL. During transition to the radioactive decay tail at \u223c100\u2009d, we find the SN to grow bluer in B \u2212 V colour, in contrast to some other Type II supernovae. At late times, the bolometric light curve declined faster than expected from ^(56)Co decay and we observed unusually broad and asymmetric nebular emission lines. Based on comparison of nebular emission lines most sensitive to the progenitor core mass, we find our observations are best matched to synthesized spectral models with a M_(ZAMS) = 12\u201315 M\u2299progenitor. The derived mass range is similar to but not higher than the mass estimated for Type IIP progenitors. This is against the idea that Type IIL are from more massive stars. Observations are consistent with the SN having a progenitor with a relatively low-mass envelope.", "doi": "10.1093/mnras/stw1419", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2016-09-11", "series_number": "2", "volume": "461", "issue": "2", "pages": "2003-2018" }, { "id": "authors:y5gsn-ac250", "collection": "authors", "collection_id": "y5gsn-ac250", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150220-105538803", "type": "article", "title": "Methane Emissions from Process Equipment at Natural Gas Production Sites in the United States: Pneumatic Controllers", "author": [ { "family_name": "Allen", "given_name": "David T.", "clpid": "Allen-D-T" }, { "family_name": "Pacsi", "given_name": "Adam P.", "clpid": "Pacsi-A-P" }, { "family_name": "Sullivan", "given_name": "David W.", "clpid": "Sullivan-D-W" }, { "family_name": "Zavala-Araiza", "given_name": "Daniel", "clpid": "Zavala-Araiza-D" }, { "family_name": "Harrison", "given_name": "Matthew", "clpid": "Harrison-M" }, { "family_name": "Keen", "given_name": "Kindal", "clpid": "Keen-K" }, { "family_name": "Fraser", "given_name": "Matthew P.", "clpid": "Fraser-M-P" }, { "family_name": "Hill", "given_name": "A. Daniel", "clpid": "Hill-A-D" }, { "family_name": "Sawyer", "given_name": "Robert F.", "clpid": "Sawyer-R-F" }, { "family_name": "Seinfeld", "given_name": "John H.", "orcid": "0000-0003-1344-4068", "clpid": "Seinfeld-J-H" } ], "abstract": "Emissions from 377 gas actuated (pneumatic) controllers were measured at natural gas production sites and a small number of oil production sites, throughout the United States. A small subset of the devices (19%), with whole gas emission rates in excess of 6 standard cubic feet per hour (scf/h), accounted for 95% of emissions. More than half of the controllers recorded emissions of 0.001 scf/h or less during 15 min of measurement. Pneumatic controllers in level control applications on separators and in compressor applications had higher emission rates than controllers in other types of applications. Regional differences in emissions were observed, with the lowest emissions measured in the Rocky Mountains and the highest emissions in the Gulf Coast. Average methane emissions per controller reported in this work are 17% higher than the average emissions per controller in the 2012 EPA greenhouse gas national emission inventory (2012 GHG NEI, released in 2014); the average of 2.7 controllers per well observed in this work is higher than the 1.0 controllers per well reported in the 2012 GHG NEI.", "doi": "10.1021/es5040156", "issn": "0013-936X", "publisher": "American Chemical Society", "publication": "Environmental Science and Technology", "publication_date": "2015-01-06", "series_number": "1", "volume": "49", "issue": "1", "pages": "633-640" }, { "id": "authors:3fqn0-pch10", "collection": "authors", "collection_id": "3fqn0-pch10", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150223-111044023", "type": "article", "title": "Methane Emissions from Process Equipment at Natural Gas Production Sites in the United States: Liquid Unloadings", "author": [ { "family_name": "Allen", "given_name": "David T.", "clpid": "Allen-D-T" }, { "family_name": "Sullivan", "given_name": "David W.", "clpid": "Sullivan-D-W" }, { "family_name": "Zavala-Araiza", "given_name": "Daniel", "clpid": "Zavala-Araiza-D" }, { "family_name": "Pacsi", "given_name": "Adam P.", "clpid": "Pacsi-A-P" }, { "family_name": "Harrison", "given_name": "Matthew", "clpid": "Harrison-M" }, { "family_name": "Keen", "given_name": "Kindal", "clpid": "Keen-K" }, { "family_name": "Fraser", "given_name": "Matthew P.", "clpid": "Fraser-M-P" }, { "family_name": "Hill", "given_name": "A. Daniel", "clpid": "Hill-A-D" }, { "family_name": "Lamb", "given_name": "Brian K.", "clpid": "Lamb-B-K" }, { "family_name": "Sawyer", "given_name": "Robert F.", "clpid": "Sawyer-R-F" }, { "family_name": "Seinfeld", "given_name": "John H.", "orcid": "0000-0003-1344-4068", "clpid": "Seinfeld-J-H" } ], "abstract": "Methane emissions from liquid unloadings were measured at 107 wells in natural gas production regions throughout the United States. Liquid unloadings clear wells of accumulated liquids to increase production, employing a variety of liquid lifting mechanisms. In this work, wells with and without plunger lifts were sampled. Most wells without plunger lifts unload less than 10 times per year with emissions averaging 21\u2009000\u201335\u2009000 scf methane (0.4\u20130.7 Mg) per event (95% confidence limits of 10\u2009000\u201350\u2009000 scf/event). For wells with plunger lifts, emissions averaged 1000\u201310\u2009000 scf methane (0.02\u20130.2 Mg) per event (95% confidence limits of 500\u201312\u2009000 scf/event). Some wells with plunger lifts are automatically triggered and unload thousands of times per year and these wells account for the majority of the emissions from all wells with liquid unloadings. If the data collected in this work are assumed to be representative of national populations, the data suggest that the central estimate of emissions from unloadings (270 Gg/yr, 95% confidence range of 190\u2013400 Gg) are within a few percent of the emissions estimated in the EPA 2012 Greenhouse Gas National Emission Inventory (released in 2014), with emissions dominated by wells with high frequencies of unloadings.", "doi": "10.1021/es504016r", "issn": "0013-936X", "publisher": "American Chemical Society", "publication": "Environmental Science and Technology", "publication_date": "2015-01-06", "series_number": "1", "volume": "49", "issue": "1", "pages": "641-648" }, { "id": "authors:7rdgj-g2k45", "collection": "authors", "collection_id": "7rdgj-g2k45", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131210-101910500", "type": "article", "title": "Measurements of methane emissions at natural gas production sites in the United States", "author": [ { "family_name": "Allen", "given_name": "David T.", "clpid": "Allen-D-T" }, { "family_name": "Torres", "given_name": "Vincent M.", "clpid": "Torres-V-M" }, { "family_name": "Thomas", "given_name": "James", "clpid": "Thomas-J" }, { "family_name": "Sullivan", "given_name": "David W.", "clpid": "Sullivan-D-W" }, { "family_name": "Harrison", "given_name": "Matthew", "clpid": "Harrison-M" }, { "family_name": "Hendler", "given_name": "Al", "clpid": "Hendler-A" }, { "family_name": "Herndon", "given_name": "Scott C.", "clpid": "Herndon-S-C" }, { "family_name": "Kolb", "given_name": "Charles E.", "clpid": "Kolb-C-E" }, { "family_name": "Fraser", "given_name": "Matthew P.", "clpid": "Fraser-M-P" }, { "family_name": "Hill", "given_name": "A. Daniel", "clpid": "Hill-A-D" }, { "family_name": "Lamb", "given_name": "Brian K.", "clpid": "Lamb-B-K" }, { "family_name": "Miskimins", "given_name": "Jennifer", "clpid": "Miskimins-J" }, { "family_name": "Sawyer", "given_name": "Robert F.", "clpid": "Sawyer-R-F" }, { "family_name": "Seinfeld", "given_name": "John H.", "orcid": "0000-0003-1344-4068", "clpid": "Seinfeld-J-H" } ], "abstract": "Engineering estimates of methane emissions from natural gas production have led to varied projections of national emissions. This work reports direct measurements of methane emissions at 190 onshore natural gas sites in the United States (150 production sites, 27 well completion flowbacks, 9 well unloadings, and 4 workovers). For well completion flowbacks, which clear fractured wells of liquid to allow gas production, methane emissions ranged from 0.01 Mg to 17 Mg (mean = 1.7 Mg; 95% confidence bounds of 0.67\u20133.3 Mg), compared with an average of 81 Mg per event in the 2011 EPA national emission inventory from April 2013. Emission factors for pneumatic pumps and controllers as well as equipment leaks were both comparable to and higher than estimates in the national inventory. Overall, if emission factors from this work for completion flowbacks, equipment leaks, and pneumatic pumps and controllers are assumed to be representative of national populations and are used to estimate national emissions, total annual emissions from these source categories are calculated to be 957 Gg of methane (with sampling and measurement uncertainties estimated at \u00b1200 Gg). The estimate for comparable source categories in the EPA national inventory is \u223c1,200 Gg. Additional measurements of unloadings and workovers are needed to produce national emission estimates for these source categories. The 957 Gg in emissions for completion flowbacks, pneumatics, and equipment leaks, coupled with EPA national inventory estimates for other categories, leads to an estimated 2,300 Gg of methane emissions from natural gas production (0.42% of gross gas production).", "doi": "10.1073/pnas.1304880110", "pmcid": "PMC3816463", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "publication_date": "2013-10-29", "series_number": "44", "volume": "110", "issue": "44", "pages": "17768-17773" }, { "id": "authors:wfz64-yq135", "collection": "authors", "collection_id": "wfz64-yq135", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160629-151751994", "type": "article", "title": "Air Quality Model Evaluation Data for Organics. 6. C_3\u2212C_(24) Organic Acids", "author": [ { "family_name": "Fraser", "given_name": "M. P.", "clpid": "Fraser-M-P" }, { "family_name": "Cass", "given_name": "G. R.", "clpid": "Cass-G-R" }, { "family_name": "Simoneit", "given_name": "B. R. T.", "clpid": "Simoneit-B-R-T" } ], "abstract": "The atmospheric concentrations of 47 carboxylic acids in the semivolatile and particle phases are quantified in the Los Angeles area, as part of a larger study of the vapor-phase, semivolatile, and particle-phase organic compounds. Variations in the spatial and temporal distributions of acid concentrations are analyzed to determine whether atmospheric formation or primary emissions are responsible for the observed levels. Relatively low molecular weight aliphatic dicarboxylic acids (e.g., butanedioic acid, hexanedioic acid, and propanedioic acid) and some n-alkanoic acids (e.g., n-octanoic acid and n-nonanoic acid) are found at an offshore sampling location at levels comparable to urban area concentrations indicating that these compounds or their atmospheric precursors may be derived from long-range transport or natural background sources. Some aromatic carboxylic acids (e.g., benzoic acid and 1,2-benzenedicarboxylic acid) have spatial and temporal distributions suggesting that formation from anthropogenic emissions of gaseous precursors dominates their atmospheric concentrations. Additionally, the distributions of aliphatic carboxylic acid concentrations known to be emitted from primary sources (e.g., hexadecanoic acid and octadecanoic acid) are consistent with direct emissions as the dominant source of these compounds.", "doi": "10.1021/es0209262", "issn": "0013-936X", "publisher": "American Chemical Society", "publication": "Environmental Science and Technology", "publication_date": "2003-02-01", "series_number": "3", "volume": "37", "issue": "3", "pages": "446-453" }, { "id": "authors:3cxx2-wp366", "collection": "authors", "collection_id": "3cxx2-wp366", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141027-144829433", "type": "article", "title": "Secondary organic aerosol 3. Urban/regional scale model of size- and composition-resolved aerosols", "author": [ { "family_name": "Griffin", "given_name": "Robert J.", "clpid": "Griffin-R-J" }, { "family_name": "Dabdub", "given_name": "Donald", "clpid": "Dabdub-D" }, { "family_name": "Kleeman", "given_name": "Michael J.", "clpid": "Kleeman-M-J" }, { "family_name": "Fraser", "given_name": "Matthew P.", "clpid": "Fraser-M-P" }, { "family_name": "Cass", "given_name": "Glen R.", "clpid": "Cass-G-R" }, { "family_name": "Seinfeld", "given_name": "John H.", "orcid": "0000-0003-1344-4068", "clpid": "Seinfeld-J-H" } ], "abstract": "The California Institute of Technology (CIT) three-dimensional urban/regional atmospheric model is used to perform comprehensive gas- and aerosol-phase simulations of the 8 September 1993 smog episode in the South Coast Air Basin of California (SoCAB) using the atmospheric chemical mechanism of part 1 [Griffin et al., 2002] and the thermodynamic module of part 2 [Pun et al., 2002]. This paper focuses primarily on simulations of secondary organic aerosol (SOA) and determination of the species and processes that lead to this SOA. Meteorological data and a gas and particulate emissions inventory for this episode were supplied directly by the South Coast Air Quality Management District. A summer 1993 atmospheric sampling campaign provides data against which the performance of the model is evaluated. Predictions indicate that SOA formation in the SoCAB is dominated by partitioning of hydrophobic secondary products of the oxidation of anthropogenic organics. The biogenic contribution to total SOA increases in the more rural eastern portions of the region, as does the fraction of hydrophilic SOA, the latter reflecting the increasing degree of oxidation of SOA species with atmospheric residence time.", "doi": "10.1029/2001JD000544", "issn": "0148-0227", "publisher": "American Geophysical Union", "publication": "Journal of Geophysical Research D", "publication_date": "2002-09-16", "series_number": "D17", "volume": "107", "issue": "D17", "pages": "Art. No. 4334" }, { "id": "authors:4903x-v4b37", "collection": "authors", "collection_id": "4903x-v4b37", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160607-125105203", "type": "article", "title": "Source Reconciliation of Atmospheric Gas-Phase and Particle-Phase Pollutants during a Severe Photochemical Smog Episode", "author": [ { "family_name": "Schauer", "given_name": "James J.", "clpid": "Schauer-J-J" }, { "family_name": "Fraser", "given_name": "Matthew P.", "clpid": "Fraser-M-P" }, { "family_name": "Cass", "given_name": "Glen R.", "clpid": "Cass-G-R" }, { "family_name": "Simoneit", "given_name": "Bernd R. T.", "clpid": "Simoneit-B-R-T" } ], "abstract": "A comprehensive organic compound-based receptor model is developed that can simultaneously apportion the source contributions to atmospheric gas-phase organic compounds, semivolatile organic compounds, fine particle organic compounds, and fine particle mass. The model is applied to ambient data collected at four sites in the south coast region of California during a severe summertime photochemical smog episode, where the model determines the direct primary contributions to atmospheric pollutants from 11 distinct air pollution source types. The 11 sources included in the model are gasoline-powered motor vehicle exhaust, diesel engine exhaust, whole gasoline vapors, gasoline headspace vapors, organic solvent vapors, whole diesel fuel, paved road dust, tire wear debris, meat cooking exhaust, natural gas leakage, and vegetative detritus. Gasoline engine exhaust plus whole gasoline vapors are the predominant sources of volatile organic gases, while gasoline and diesel engine exhaust plus diesel fuel vapors dominate the emissions of semivolatile organic compounds from these sources during the episode studied at all four air monitoring sites. The atmospheric fine particle organic compound mass was composed of noticeable contributions from gasoline-powered motor vehicle exhaust, diesel engine exhaust, meat cooking, and paved road dust with smaller but quantifiable contributions from vegetative detritus and tire wear debris. In addition, secondary organic aerosol, which is formed from the low-vapor pressure products of gas-phase chemical reactions, is found to be a major source of fine particle organic compound mass under the severe photochemical smog conditions studied here. The concentrations of secondary organic aerosol calculated in the present study are compared with previous fine particle source apportionment results for less intense photochemical smog conditions. It is shown that estimated secondary organic aerosol concentrations correlate fairly well with the concentrations of 1,2-benzenedicarboxylic acid in the atmospheric fine particle mass, indicating that aromatic diacids may be useful in the quantification of certain sources of secondary organic aerosol in the atmosphere.", "doi": "10.1021/es011458j", "issn": "0013-936X", "publisher": "American Chemical Society", "publication": "Environmental Science and Technology", "publication_date": "2002-09-01", "series_number": "17", "volume": "36", "issue": "17", "pages": "3806-3814" }, { "id": "authors:xfgcj-3zq92", "collection": "authors", "collection_id": "xfgcj-3zq92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160622-152147558", "type": "article", "title": "Modeling the Atmospheric Concentrations of Individual Gas-Phase and Particle-Phase Organic Compounds", "author": [ { "family_name": "Fraser", "given_name": "M. P.", "clpid": "Fraser-M-P" }, { "family_name": "Kleeman", "given_name": "M. J.", "clpid": "Kleeman-M-J" }, { "family_name": "Schauer", "given_name": "J. J.", "clpid": "Schauer-J-J" }, { "family_name": "Cass", "given_name": "G. R.", "clpid": "Cass-G-R" } ], "abstract": "An Eulerian photochemical airshed model is adapted to track the concentrations of individual vapor-phase, semivolatile, and particle-phase compounds over the carbon number range from C_1 to C_(34). The model incorporates primary emissions of organic gases and particles from sources based on recent source tests. These emissions are processed through a photochemical airshed model whose chemical mechanism has been expanded to explicitly follow the reaction or formation of 125 individual vapor-phase organic compounds plus 11 lumped vapor-phase compound groups. Primary organic compounds in the particle phase can be disaggregated at will from a lumped primary organic compound mass category; in the present model application, 31 individual primary particulate organic compounds are tracked as they are transported from sources to receptor air monitoring sites. The model is applied to study air quality relationships for organics in California's South Coast Air Basin that surrounds Los Angeles during the severe photochemical smog episode that occurred on September 8\u22129, 1993. The ambient concentra tions of all normal alkanes and most aromatic hydrocarbons are predicted within the correct order of magnitude over 6 orders of magnitude concentration change from most abundant gas phase to least abundant particulate species studied. A formal evaluation of model performance shows that, with the exception of a few outliers, the concentrations of over 100 organic compounds studied were reproduced with an average absolute bias of \u00b147% and with roughly equal numbers of compounds underpredicted (58) versus overpredicted (46). The time series of observed aromatic hydrocarbons concentrations are reproduced closely, production of methylglyoxal from aromatic precursors is tracked, and the predicted olefinic hydrocarbon concentrations decline dramatically in concentration due to chemical reaction and dilution during downwind transport as is observed in the ambient monitoring database. This ability to simultaneously account for the concentrations of individual gas-phase and particulate organic compounds lays a foundation for future calculations of secondary organic aerosol formation and gas/particle repartitioning in the atmosphere.", "doi": "10.1021/es9901922", "issn": "0013-936X", "publisher": "American Chemical Society", "publication": "Environmental Science and Technology", "publication_date": "2000-04-01", "series_number": "7", "volume": "34", "issue": "7", "pages": "1302-1312" }, { "id": "authors:z2akx-bn737", "collection": "authors", "collection_id": "z2akx-bn737", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160629-103517481", "type": "article", "title": "Particulate organic compounds emitted from motor vehicle exhaust and in the urban atmosphere", "author": [ { "family_name": "Fraser", "given_name": "Matthew P.", "clpid": "Fraser-M-P" }, { "family_name": "Cass", "given_name": "Glen R.", "clpid": "Cass-G-R" }, { "family_name": "Simoneit", "given_name": "Bernd R. T.", "clpid": "Simoneit-B-R-T" } ], "abstract": "The emission rate of particle-phase petroleum biomarkers in vehicular exhaust compared to the concentrations of these biomarkers in ambient air is used to determine the particulate organic compound concentration due to primary particle emissions from motor vehicles in the southern California atmosphere. A material balance on the organic particulate matter emitted from motor vehicle traffic in a Los Angeles highway tunnel first is constructed to show the proportion which is solvent-extractable and which will elute from a GC column, the ratio of resolved to unresolved compound mass, the portion of the resolved material that can be identified as single organic compounds, and the contribution of different classes of organic compounds to the overall identified fraction. It is shown that the outdoor ambient concentrations of the petroleum biomarkers track primary emissions measured in the highway tunnel, confirming that direct emissions of these compounds from vehicles govern the observed ambient petroleum biomarker concentrations. Using organic chemical tracer techniques, the portion of fine organic particulate matter in the Los Angeles atmosphere which is attributable to direct particle emissions from vehicle exhaust is calculated to vary from 7.5 to 18.3% at different sites throughout the air basin during a summertime severe photochemical smog episode. A similar level of variation in the contribution of primary motor vehicle exhaust to fine particulate organic matter concentrations during different times of day is seen. While peak atmospheric concentrations of fine particulate organic carbon are observed during the 1200\u20131600 PDT afternoon sampling period, only 6.3% of that material is apportioned to the directly emitted particles from vehicle exhaust. During the morning traffic peak between 0600\u20131000 PDT, 19.1% of the fine particulate organic material is traced to primary emissions from motor vehicles.", "doi": "10.1016/S1352-2310(98)00311-2", "issn": "1352-2310", "publisher": "Elsevier", "publication": "Atmospheric Environment", "publication_date": "1999-08", "series_number": "17", "volume": "33", "issue": "17", "pages": "2715-2724" }, { "id": "authors:gctqy-gnp06", "collection": "authors", "collection_id": "gctqy-gnp06", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160613-112921434", "type": "article", "title": "Gas Phase C_2\u2212C_(10) Organic Acids Concentrations in the Los Angeles Atmosphere", "author": [ { "family_name": "Nolte", "given_name": "Christopher G.", "clpid": "Nolte-C-G" }, { "family_name": "Fraser", "given_name": "Matthew P.", "clpid": "Fraser-M-P" }, { "family_name": "Cass", "given_name": "Glen R.", "clpid": "Cass-G-R" } ], "abstract": "The atmospheric concentrations of gas-phase C_2\u2212C_(10) monocarboxylic and benzoic acids are reported in samples collected during a severe Los Angeles area photochemical smog episode. Average urban concentrations are 10\u221250 \u00d7 greater than concentrations observed at a remote background location, indicating an anthropogenic origin for these compounds. Average urban concentrations during the episode were 16.1 \u03bcg m^(-3) (6.6 ppb) for acetic acid and 1.67 \u03bcg m^(-3) (0.55 ppb) for propionic acid, with progressively lesser amounts as the carbon chain length of the acids is increased. Spatial and diurnal variations in atmospheric organic acids concentrations point to the importance of both direct emissions from primary sources and formation by photochemical reaction of precursor compounds.", "doi": "10.1021/es980626d", "issn": "0013-936X", "publisher": "American Chemical Society", "publication": "Environmental Science and Technology", "publication_date": "1999-02-15", "series_number": "4", "volume": "33", "issue": "4", "pages": "540-545" }, { "id": "authors:gss95-2cj80", "collection": "authors", "collection_id": "gss95-2cj80", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160613-112922470", "type": "article", "title": "Gas-Phase and Particle-Phase Organic Compounds Emitted from Motor Vehicle Traffic in a Los Angeles Roadway Tunnel", "author": [ { "family_name": "Fraser", "given_name": "Matthew P.", "clpid": "Fraser-M-P" }, { "family_name": "Cass", "given_name": "Glen R.", "clpid": "Cass-G-R" }, { "family_name": "Simoneit", "given_name": "Bernd R. T.", "clpid": "Simoneit-B-R-T" } ], "abstract": "The emission rates for 221 vapor-phase, semivolatile, and particle-phase organic compounds from motor vehicles plus fine particulate matter mass and some inorganic particle-phase species are calculated based on measurements made inside and outside a Los Angeles roadway tunnel in 1993. These emission rates are calculated based on fuel consumption to remove any uncertainties based on tunnel dilution rates or air circulation. The results show carbon monoxide emissions rates of 130 g L^(-1) of gasoline-equivalent fuel burned and volatile organic compound (VOC) emissions of 9.1 g L^(-1). These values are higher than predicted by the baseline version of California's EMFAC 7G emissions inventory program but are within the coemission rate range of 108 \u00b1 25 g L^(-1) reported by roadside remote sensing studies in Los Angeles [Singer, B. C.; Harley, R. A. J. Air Waste Manage. Assoc. 1996, 46, 581\u2212593]. When the VOC emissions composition in the tunnel is compared to that of tailpipe emissions source test data and to the composition of additional unburned whole gasoline, the tunnel atmosphere is found to be consistent with a linear combination of these major contributors over a fairly broad range of about 74\u221297% vehicle exhaust depending on the tailpipe profiles used. Fine particulate emissions within the tunnel consist largely of carbonaceous material accompanied by a significant amount of ammonium nitrate apparently formed by gas-to-particle conversion processes within the tunnel atmosphere. Certain gas-phase and particulate organic compounds traditionally thought to be the secondary products of atmospheric chemical reactions are enriched inside the tunnel, and from this enrichment, the primary emission rates of aromatic alcohols, aliphatic dicarboxylic acids, and aromatic polycarboxylic acids are calculated. Data on petroleum biomarkers emissions rates in the tunnel can be used in the future to estimate primary vehicle exhaust fine particulate matter concentrations in the urban atmosphere.", "doi": "10.1021/es970916e", "issn": "0013-936X", "publisher": "American Chemical Society", "publication": "Environmental Science and Technology", "publication_date": "1998-07-15", "series_number": "14", "volume": "32", "issue": "14", "pages": "2051-2060" }, { "id": "authors:3vngn-cjj08", "collection": "authors", "collection_id": "3vngn-cjj08", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160613-112922732", "type": "article", "title": "Air Quality Model Evaluation Data for Organics. 5. C_6\u2212C_(22) Nonpolar and Semipolar Aromatic Compounds", "author": [ { "family_name": "Fraser", "given_name": "Matthew P.", "clpid": "Fraser-M-P" }, { "family_name": "Cass", "given_name": "Glen R.", "clpid": "Cass-G-R" }, { "family_name": "Simoneit", "given_name": "Bernd R. T.", "clpid": "Simoneit-B-R-T" }, { "family_name": "Rasmussen", "given_name": "R. A.", "clpid": "Rasmussen-R-A" } ], "abstract": "The concentrations of 86 vapor-phase, semivolatile, and particle-phase aromatic compounds are measured during a severe Los Angeles photochemical smog episode. The measurements are part of a larger experiment designed to acquire a nearly complete description of organic air pollutants for use in verifying the predictions of photochemical airshed models for organics. Compound classes formed by grouping all aromatic hydrocarbons having the same number of aromatic rings show progressively declining concentrations as the number of aromatic rings is increased. Examination of the partitioning of the polycyclic aromatic hydrocarbons (PAH) between the gas and particle phases shows the transition from purely gaseous PAH at low molecular weight to purely particle-phase PAH at high molecular weight, with compounds such as the mutagen cyclopenta[cd]pyrene present about equally in both gas and particle phases. Primary aromatics, both the vapor-phase mono-aromatics and the PAH, show evidence of depletion by atmospheric chemical reaction over downwind transport with apparent depletion rates generally increasing as the degree of substitution of the aromatic rings increases. In contrast, many nitro-PAH and some oxy-PAH accumulate during downwind transport, consistent with their likely formation as products of atmospheric chemical reactions. Historical data generally show that aromatics concentrations declined substantially from the 1950s to the 1980s, but that concentrations measured during the present 1993 experiment are very similar to those measured during the mid-1980s including the August episode of the 1987 SCAQS experiment. The present experiment provides baseline data prior to the introduction of California Phase II reformulated gasoline that can be used in future years to examine the effect of the reduced aromatic content of that Phase II gasoline.", "doi": "10.1021/es970349v", "issn": "0013-936X", "publisher": "American Chemical Society", "publication": "Environmental Science and Technology", "publication_date": "1998-06-15", "series_number": "12", "volume": "32", "issue": "12", "pages": "1760-1770" }, { "id": "authors:g3twf-neh68", "collection": "authors", "collection_id": "g3twf-neh68", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160614-135825025", "type": "article", "title": "Detection of Excess Ammonia Emissions from In-Use Vehicles and the Implications for Fine Particle Control", "author": [ { "family_name": "Fraser", "given_name": "Matthew P.", "clpid": "Fraser-M-P" }, { "family_name": "Cass", "given_name": "Glen R.", "clpid": "Cass-G-R" } ], "abstract": "The emission rate for ammonia from in-use vehicles is calculated based on measurements made inside a Los Angeles roadway tunnel. Using fleet distributions by vehicle age and type, known catalyst distributions, and fuel economy by model year and vehicle type and attributing all ammonia to vehicles equipped with three-way catalysts or three-way catalysts plus oxidizing catalysts (dual-bed catalysts), we estimate an average ammonia emission rate of 72 mg km^(-1) for these vehicles, or 61 mg km^(-1) driven by the vehicle fleet as a whole. These emissions can emanate from vehicles running under rich air\u2212fuel conditions, with three-way catalytic converters designed to reduce NO_x to N_2 and O_2 in addition forming NH_3. Resulting calculations estimate ammonia emissions of 24\u221229 t of NH_3 day^(-1) from the vehicle fleet for the South Coast Air Basin (SoCAB) that surrounds Los Angeles. This represents an increase in the daily emissions of ammonia attributable to motor vehicles in the SoCAB from 2% of basin wide emissions before the introduction of catalyst-equipped automobiles to 15% based on the current experiment. The air basin wide emission rate of ammonia from motor vehicles is compared to ammonia emissions from livestock waste decomposition at local dairies, and the implications for control of fine particle ammonium nitrate concentrations are discussed.", "doi": "10.1021/es970382h", "issn": "0013-936X", "publisher": "American Chemical Society", "publication": "Environmental Science and Technology", "publication_date": "1998-04-15", "series_number": "8", "volume": "32", "issue": "8", "pages": "1053-1057" }, { "id": "authors:a9gpv-qs971", "collection": "authors", "collection_id": "a9gpv-qs971", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160614-135824135", "type": "article", "title": "Air Quality Model Evaluation Data for Organics. 4. C_2\u2212C_(36) Non-Aromatic Hydrocarbons", "author": [ { "family_name": "Fraser", "given_name": "Matthew P.", "clpid": "Fraser-M-P" }, { "family_name": "Cass", "given_name": "Glen R.", "clpid": "Cass-G-R" }, { "family_name": "Simoneit", "given_name": "Bernd R. T.", "clpid": "Simoneit-B-R-T" }, { "family_name": "Rasmussen", "given_name": "R. A.", "clpid": "Rasmussen-R-A" } ], "abstract": "The concentrations of 143 non-aromatic hydrocarbons are quantified in 36 samples (32 urban and 4 background) collected during a severe Los Angeles area photochemical smog episode. Gas phase, semivolatile, and particle phase organic compounds are viewed simultaneously across the carbon number range from C_2 to C_(36). Compound classes studied include the n-alkanes, branched alkanes, n-alkenes, branched alkenes, diolefins, alkynes, saturated cyclic hydrocarbons, unsaturated cyclic hydrocarbons, biogenic hydrocarbons, petroleum biomarkers, and the unresolved complex mixture contained within the semivolatile and particle phase organics samples. The abundance of the n-alkanes falls almost exponentially with increasing n-alkane carbon number, and the distribution of the n-alkanes between the gas and particle phases follows vapor/particle partitioning theory. The concentrations of individual low molecular weight alkenes decline during transport across the urban area in about the order expected given their initial rates of reaction with the hydroxyl radical. Petroleum biomarker concentrations that act as tracers for particulate organics emitted from vehicle exhaust have declined substantially between 1982 and 1993, reflecting the increased penetration of catalyst-equipped cars into the vehicle fleet. The most pronounced change in vapor phase non-aromatic hydrocarbons concentrations between 1987 and 1993 is a reduction in the concentration of the lightest blending components of gasoline (e.g., butanes), reflecting new regulations that limit the Reid vapor pressure of gasoline.", "doi": "10.1021/es960980g", "issn": "0013-936X", "publisher": "American Chemical Society", "publication": "Environmental Science and Technology", "publication_date": "1997-08", "series_number": "8", "volume": "31", "issue": "8", "pages": "2356-2367" }, { "id": "authors:n16rb-mez93", "collection": "authors", "collection_id": "n16rb-mez93", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160622-130628605", "type": "article", "title": "Air Quality Model Evaluation Data for Organics. 3. Peroxyacetyl Nitrate and Peroxypropionyl Nitrate in Los Angeles Air", "author": [ { "family_name": "Grosjean", "given_name": "Eric", "clpid": "Grosjean-E" }, { "family_name": "Grosjean", "given_name": "Daniel", "clpid": "Grosjean-D" }, { "family_name": "Fraser", "given_name": "Matthew P.", "clpid": "Fraser-M-P" }, { "family_name": "Cass", "given_name": "Glen R.", "clpid": "Cass-G-R" } ], "abstract": "Ambient levels of peroxyacetyl nitrate [PAN, CH_3C(O)OONO_2] and peroxypropionyl nitrate [PPN, CH_3CH_2C(O)OONO_2] have been measured during the 2-week period Aug 28\u2212Sept 13, 1993, at four locations in the urban Los Angeles area. Highest concentrations recorded were 9.9 ppb for PAN and 1.5 ppb for PPN. Diurnal and spatial variations were consistent with photochemical production during eastward (inland) transport. Results for PAN are compared to those obtained in previous studies of ambient PAN in the urban Los Angeles area. Results for PPN, measured for the first time in the urban Los Angeles area, are compared to those recently obtained at southern California mountain sites and other locations. Ambient levels of PPN were correlated with those of PAN, with least squares linear regressions slopes (PPN vs PAN) of 0.153 \u00b1 0.030 (Long Beach), 0.136 \u00b1 0.026 (Los Angeles), 0.166 \u00b1 0.018 (Azusa), and 0.097 \u00b1 0.014 (Claremont). These ratios are compared to those measured previously at other locations and are briefly discussed with respect to spatial changes in the relative importance of those hydrocarbons that are precursors to PAN and PPN. The amount of PAN lost due to thermal decomposition was calculated and was comparable in magnitude to that measured.", "doi": "10.1021/es9508535", "issn": "0013-936X", "publisher": "American Chemical Society", "publication": "Environmental Science and Technology", "publication_date": "1996-09", "series_number": "9", "volume": "30", "issue": "9", "pages": "2704-2714" }, { "id": "authors:3e48p-j5b39", "collection": "authors", "collection_id": "3e48p-j5b39", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160630-064617145", "type": "article", "title": "Air Quality Model Evaluation Data for Organics. 2. C_1\u2212C_(14) Carbonyls in Los Angeles Air", "author": [ { "family_name": "Grosjean", "given_name": "Eric", "clpid": "Grosjean-E" }, { "family_name": "Grosjean", "given_name": "Daniel", "clpid": "Grosjean-D" }, { "family_name": "Fraser", "given_name": "Matthew P.", "clpid": "Fraser-M-P" }, { "family_name": "Cass", "given_name": "Glen R.", "clpid": "Cass-G-R" } ], "abstract": "As part of a larger experiment that provides a comprehensive set of observations to be used for testing air quality models for organic air pollutant transport and reaction, ambient air samples have been collected using DNPH-coated C_(18) cartridges at four urban locations and one background location in the Los Angeles area and have been analyzed for carbonyls as their DNPH derivatives. Twenty-three carbonyls have been identified and their concentrations measured:\u2009 14 aliphatic aldehydes (from formaldehyde to tetradecanal), two aromatics (benzaldehyde and m-tolualdehyde), three ketones (acetone, 2-butanone, and cyclohexanone), one unsaturated carbonyl (crotonaldehyde), and three dicarbonyls (glyoxal, methylglyoxal, and biacetyl). Another 19 carbonyls have been tentatively identified including 11 low molecular weight (MW) and intermediate MW carbonyls (of which four may be due to reactions of ambient NO, NO_2, and ozone with DNPH on the sampling cartridge), four C_4\u2212C_6 dicarbonyls present at trace levels, and four high MW aliphatic carbonyls (C_(15)\u2212C_(18)). Total carbonyl concentrations (4-h samples) averaged 22 ppb at the urban locations and 3.5 ppb at the background location and were highest (29 ppb) at the Azusa, CA, monitoring site that is downwind of downtown Los Angeles. Formaldehyde (urban average 5.3 ppb), acetaldehyde, and acetone accounted for 24%, 18%, and 7%, respectively, of the total carbonyls on a ppbv basis. The nine high MW carbonyls (C_8\u2212C_(14)) accounted for 11\u221214% of the total carbonyls. The acetaldehyde/formaldehyde concentration ratio averaged 0.75 at the urban locations. Ranking of the measured carbonyls with respect to removal of the hydroxyl radical showed acetaldehyde to be the most important followed by formaldehyde and nonanal. Diurnal and spatial variations in ambient carbonyls levels are briefly examined and appear to be consistent with both direct emissions and in-situ formation during eastward transport over the urban area.", "doi": "10.1021/es950758w", "issn": "0013-936X", "publisher": "American Chemical Society", "publication": "Environmental Science and Technology", "publication_date": "1996-08-27", "series_number": "9", "volume": "30", "issue": "9", "pages": "2687-2703" }, { "id": "authors:5wcyh-jpp25", "collection": "authors", "collection_id": "5wcyh-jpp25", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160622-125623427", "type": "article", "title": "Air Quality Model Evaluation Data for Organics. 1. Bulk Chemical Composition and Gas/Particle Distribution Factors", "author": [ { "family_name": "Fraser", "given_name": "Matthew P.", "clpid": "Fraser-M-P" }, { "family_name": "Grosjean", "given_name": "Daniel", "clpid": "Grosjean-D" }, { "family_name": "Grosjean", "given_name": "Eric", "clpid": "Grosjean-E" }, { "family_name": "Rasmussen", "given_name": "R. A.", "clpid": "Rasmussen-R-A" }, { "family_name": "Cass", "given_name": "Glen R.", "clpid": "Cass-G-R" } ], "abstract": "During the period of September 8\u22129, 1993, the South Coast Air Basin that surrounds Los Angeles experienced the worst photochemical smog episode in recent years; ozone concentrations exceeded 0.29 ppm 1-h average, and NO_2 concentrations peaked at 0.21 ppm 1-h average. Field measurements were conducted at a five-station air monitoring network to obtain comprehensive data on the identity and concentration of the individual organic compounds present in both the gas and particle phases during that episode. The data will also serve to support future tests of air quality models designed to study organic air pollutant transport and reaction. Air samples taken in stainless steel canisters were analyzed for 141 volatile organic compounds by GC/ECD, GC/FID, and GC/MS; PAN and PPN were measured by GC/ECD; particulate organics collected by filtration were analyzed for total organics and elemental carbon by thermal evolution and combustion and for individual organic compounds by GC/MS; semivolatile organics were analyzed by GC/MS after collection on polyurethane foam cartridges. The present paper describes this experiment and presents the concentrations of major organic compound classes and their relationship to the inorganic pollutants present. At the farthest downwind site studied (Claremont), extensive modification of primary pollutants by atmospheric chemical reactions was evident during the peak photochemical smog period:\u2009 vapor-phase olefins and aromatics were depleted, the majority of the nitrogen-containing pollutants were present as organic plus inorganic nitrates, the fraction of organics in the particle phase rose to 12.5% (versus 2.6\u22125.4% at the coast), one fourth of the pollutant-derived nitrogen was in the particle phase, and nearly all of the Cl- had been removed from the particle phase. Of the total nitrate measured at Claremont, on the average only 33.6% was present as organic nitrates, which is a much lower ratio of organic nitrate to total nitrate than has been seen in previous years.", "doi": "10.1021/es9507325", "issn": "0013-936X", "publisher": "American Chemical Society", "publication": "Environmental Science and Technology", "publication_date": "1996-05", "series_number": "5", "volume": "30", "issue": "5", "pages": "1731-1743" } ]