John V Ortega | National Center for Atmospheric Research (NCAR) (original) (raw)

Papers by John V Ortega

The Science of the total environment, Jan 2, 2018

A large fraction of the global population relies on the inefficient combustion of solid fuels for... more A large fraction of the global population relies on the inefficient combustion of solid fuels for cooking and home heating, resulting in household exposure to combustion byproducts. In the southwestern United States, unhealthy air quality has been observed in some homes that use solid fuels as a primary source of heat on the Navajo Nation. In order to better understand how home heating fuel choice can influence indoor air quality in this region, we used recently developed low-cost electrochemical sensors to measure carbon monoxide (CO) air mole fractions continuously inside and outside 41 homes in two communities on the Navajo Nation. Using low-cost sensors in this study, which don't require extensive training to operate, enabled collaboration with local Diné College students and faculty in the planning and implementation of home deployments. Households used natural gas, propane, pellets, wood, and/or coal for heating. We developed quantification methods that included uncertaint...

Understanding the mechanisms of secondary organic aerosol formation is of critical importance for... more Understanding the mechanisms of secondary organic aerosol formation is of critical importance for assessing aerosol radiative forcing and improving air quality control. A key quantity describing the gas-to-particle conversion is the rate at which nanoparticles of certain size are formed per unit volume and time. The quantification of nanoparticle formation rates requires precise knowledge of growth rates. Here we present a newly developed DMA train capable of providing definitive growth rates from size distribution scan frequencies of 1 Hz. This system has proven to yield statistically significant data even at ultra-low post-classification concentrations of 0.1 cm−3. A chamber study of α-pinene ozonolysis under close-to-ambient conditions demonstrates the need for particle size distribution measurements with increased time resolution.

Environmental Science & Technology, 2007

Atmospheric Environment, 2006

Atmospheric Environment, 2008

The photooxidation of ∼1ppm α-pinene in the presence of increasing concentrations of NO2 was stud... more The photooxidation of ∼1ppm α-pinene in the presence of increasing concentrations of NO2 was studied in a Teflon® chamber at 72–88% relative humidity and 296–304K. The loss of α-pinene and formation of gas-phase products were followed using proton-transfer reaction mass spectrometry (PTR-MS). Gas-phase reaction products (and their yields) include formaldehyde (5±1%), formic acid (2.5±1.4%), methanol (0.6±0.3%), acetaldehyde (3.9±1.7%), acetic acid

Atmospheric Environment, 2007

Diurnal branch-level emission rates of biogenic volatile organic compounds (BVOC) including isopr... more Diurnal branch-level emission rates of biogenic volatile organic compounds (BVOC) including isoprene, monoterpenes (MT), and sesquiterpenes (SQT) were determined at the University of Michigan Biological Station for the tree species red maple (Acer rubrum), red oak (Quercus rubra), paper birch (Betula papyrifera), white pine (Pinus strobus), and big tooth aspen (Populus grandidentata). These emission rates were combined with detailed biomass distribution and meteorological data and incorporated into the canopy model, model of emissions of gasses and aerosols from nature (MEGAN), for estimating whole-canopy fluxes of isoprene. The modeled half-hour fluxes ðmg C m À2 h À1 Þ and cumulative seasonal fluxes ðmg C m À2 Þ compared favorably with results from direct, canopy-level eddy covariance (EC) isoprene measurements; modeled cumulative seasonal flux deviated less than 30% from the EC results. Significant MT emissions were found from four of the five tree species. MT emissions from three of these were both light-and temperature-dependent and were approximately one order of magnitude greater than light-independent MT emissions. SQT emissions were identified from three of the five tree species. The model was modified to incorporate SQT and both light-dependent and light-independent MT emissions for determining fluxes. Isoprene comprised 495% of the total terpenoid flux with MT and SQT comprising 4% and 0.3%, respectively. The average cumulative fluxes (in mg C m À2) from June through September were 2490 for isoprene, 105 for MT, and 7 for SQT. A simple box model analysis was used to estimate the contribution of the isoprene, MT, and SQT emissions to the total OH reactivity. These results confirm that isoprene dominates OH reactions especially during daytime hours. Emissions of reactive MT and SQT increase the BVOC+OH reactivity, but are still lower than estimates of BVOC fluxes at this site necessary for affecting OH reactivity to the significant degree suggested by recent reports.

Atmospheric Chemistry and Physics, 2008

Atmospheric Chemistry and Physics, 2010

Aerosol Science and Technology, 2012

Atmospheric Chemistry and Physics Discussions, 2014

The Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H 2 O, Organics & Nitrogen (BE... more The Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H 2 O, Organics & Nitrogen (BEACHON) project seeks to understand the feedbacks and interrelationships between hydrology, biogenic emissions, carbon assimilation, aerosol properties, clouds and associated feedbacks within water-limited ecosystems. The

Aerosol Science and Technology

Several different types of measurements of particle size and concentration were compared during t... more Several different types of measurements of particle size and concentration were compared during the 2016 Airborne Research Instrumentation Testing Opportunity (ARISTO) campaign. The scanning mobility particle sizer (SMPS) measured number-size distributions for mobility diameters between 20−350and20-350 and 20−350and8-110 nm, depending on the mobility analyzer chosen. Also included were two stand-alone condensation particle counters (CPC) for determining size-integrated particle concentrations. A wing-mounted and a rack-mounted Ultra-High Sensitivity Aerosol Spectrometer (UHSAS) were used to measure size distributions between 60 and 1000 nm. Lastly, two different sampling inlets were used to investigate performance and observe any systematic biases. Most sampling occurred during cloud-free summer conditions in the western United States. Number concentrations from the two CPCs typically agreed within 12% once the flows in the ultrafine particle counter were corrected as a function of pressure. As expected, the size-integrated number concentrations from the SMPS and UHSAS were generally less than those of the CPCs, as the former cover only part of the total range of particle sizes measured by the CPCs. Integrated number concentrations from the wing-mounted and rack-mounted UHSAS generally agreed within 20% for all diameter ranges analyzed. The overlap region between the SMPS and the UHSAS showed reasonable agreement of ±20%. Some of the uncertainty regarding these measurement comparisons originates from a variety of factors, including sampling frequency, particle refractive index, differences between physical and mobility diameters, and counting efficiency uncertainties in the UHSAS optical cavity, especially for the smallest diameters (60-100 nm).

Nature, Jan 11, 2016

Nitrogen oxides are essential for the formation of secondary atmospheric aerosols and of atmosphe... more Nitrogen oxides are essential for the formation of secondary atmospheric aerosols and of atmospheric oxidants such as ozone and the hydroxyl radical, which controls the self-cleansing capacity of the atmosphere. Nitric acid, a major oxidation product of nitrogen oxides, has traditionally been considered to be a permanent sink of nitrogen oxides. However, model studies predict higher ratios of nitric acid to nitrogen oxides in the troposphere than are observed. A 'renoxification' process that recycles nitric acid into nitrogen oxides has been proposed to reconcile observations with model studies, but the mechanisms responsible for this process remain uncertain. Here we present data from an aircraft measurement campaign over the North Atlantic Ocean and find evidence for rapid recycling of nitric acid to nitrous acid and nitrogen oxides in the clean marine boundary layer via particulate nitrate photolysis. Laboratory experiments further demonstrate the photolysis of particulat...

Chemistry of Materials, 1991

Submicron particles of barium calcium titanate (B%. C%. 14Ti0J were generated by aerosol decompos... more Submicron particles of barium calcium titanate (B%. C%. 14Ti0J were generated by aerosol decomposition at reactor temperatures ranging from 900 to 1600 O?!. X-ray diffraction showed phase-pure tetragonal BQ.~ CQ.~~ T~ O~ for all reactor temperatures. Particle ...

Environmental science & …, 2005

Atmospheric standards containing parts-per-billion levels of 14 semivolatile hydrocarbon compound... more Atmospheric standards containing parts-per-billion levels of 14 semivolatile hydrocarbon compounds, including eight sesquiterpenes (SQTs) (longipinene, alpha-copaene, isolongifolene, alpha-cedrene, trans-caryophyllene, aromadendrene, alpha-humulene, delta-cadinene), two oxidized sesquiterpenoids (cisnerolidol, trans-nerolidol), one biogenic ketone (geranylacetone) and three aromatic compounds (1,3,5-triisopropylbenzene, diphenylmethane, nonylbenzene), were collected onto four solid adsorbent materials at increasing ozone mixing ratios (0-100 ppbv 03) for analysis by thermodesorption-gas chromatography. Substantial sampling losses of up to >90% were found for the most reactive SQT, even at the lowest ozone level investigated of 20 ppbv. Loss rates from the ozone-SQT reaction were used to derive estimates of gas-phase ozone reaction rate constants for longipinene, alpha-copaene, isolongifolene, geranylacetone, aromadendrene, delta-cadinene, cis-nerolidol, and transnerolidol. Three different ozone mitigation techniques were investigated to prevent these sampling losses. These strategies included (a) placing glass fiber filters impregnated with sodium thiosulfate (Na2S2O3) into the sampling line, (b) titration of ozone in the sampling stream with nitric oxide (NO), and (c) catalytically removing ozone with a commercially available manganese dioxide (MnO2) catalyst. All three techniques reduced ozone-mixing ratios from 100 ppbv to <0.6 ppbv at sampling flow rates of 1 L min(-1). When the Na2S2O3 filters and the NO-titration techniques were applied, SQT loss rates decreased from 25-60% to 0-5% for most SQT compounds and from >90% to approximately 10-50% for the two most reactive compounds at ozone mixing ratios of up to 100 ppbv. The commercial manganese dioxide scrubber, however, caused complete analyte losses (>98%) even at 0 ppbv ozone. These results underline the need and present applicable techniques for removal of ozone in air samples for SQT analysis by solid adsorption techniques.

Atmospheric Chemistry and Physics, 2009

As part of the MILAGRO field campaign, the DOE G-1 aircraft was used to make measurements over an... more As part of the MILAGRO field campaign, the DOE G-1 aircraft was used to make measurements over and downwind of Mexico City with the objective of determining growth characteristics of aerosols from a megacity urban source. This study focuses on number concentration and size distributions. It is found that a 5-fold increase in aerosol volume is accompanied by about a 5-fold increase in accumulation mode number concentration. There is growth in aerosol volume because there are more accumulation mode particles, not because of an increase in the average size of accumulation particles. Condensation and volume growth laws were examined to see whether either is consistent with observations. Condensation calculations show that the growth of Aitken mode particles into the accumulation mode size range gives the required increase in number concentration. There are minimal changes in the accumulation mode size distribution with age, consistent with observations. Volume-growth in contrast yields a population of large particles, distinctly different from what is observed. Detailed model calculations are required to translate our observations into specific information on the volatility and properties of secondary organic aerosol.

Atmospheric Environment, 2009

... 2, Allée du Parc de Brabois F-54514 Vandoeuvre-lès-Nancy Cedex France Phone: +33 (0)3 83 50 4... more ... 2, Allée du Parc de Brabois F-54514 Vandoeuvre-lès-Nancy Cedex France Phone: +33 (0)3 83 50 46 64 Fax ... SPICER Chester W. ; HOLDREN Michael W. ; COWEN Kenneth A. ; JOSEPH Darrell W. ; SATOLA Jan ; GOODWIN Bradley ; MAYFIELD Howard ; LASKIN Alexander ...

Atmospheric …, 2009

Aircraft emissions affect air quality on scales from local to global. More than 20% of the jet fu... more Aircraft emissions affect air quality on scales from local to global. More than 20% of the jet fuel used in the U.S. is consumed by military aircraft, and emissions from this source are facing increasingly stringent environmental regulations, so improved methods for quickly and accurately determining emissions from existing and new engines are needed. This paper reports results of a study to advance the methods used for detailed characterization of military aircraft emissions, and provides emission factors for two aircraft: the F-15 fighter and the C-130 cargo plane. The measurements involved outdoor ground-level sampling downstream behind operational military aircraft. This permits rapid change-out of the aircraft so that engines can be tested quickly on operational aircraft. Measurements were made at throttle settings from idle to afterburner using a simple extractive probe in the dilute exhaust. Emission factors determined using this approach agree very well with those from the traditional method of extractive sampling at the exhaust exit. Emission factors are reported for CO 2 , CO, NO, NO x , and more than 60 hazardous and/or reactive organic gases. Particle size, mass and composition also were measured and are being reported separately. Comparison of the emissions of nine hazardous air pollutants from these two engines with emissions from nine other aircraft engines is discussed.

Atmospheric Environment, 2008

The photooxidation of ∼1ppm α-pinene in the presence of increasing concentrations of NO2 was stud... more The photooxidation of ∼1ppm α-pinene in the presence of increasing concentrations of NO2 was studied in a Teflon® chamber at 72–88% relative humidity and 296–304K. The loss of α-pinene and formation of gas-phase products were followed using proton-transfer reaction mass spectrometry (PTR-MS). Gas-phase reaction products (and their yields) include formaldehyde (5±1%), formic acid (2.5±1.4%), methanol (0.6±0.3%), acetaldehyde (3.9±1.7%), acetic acid

Chemistry of …, 1991

Submicron particles of barium calcium titanate (B%. C%. 14Ti0J were generated by aerosol decompos... more Submicron particles of barium calcium titanate (B%. C%. 14Ti0J were generated by aerosol decomposition at reactor temperatures ranging from 900 to 1600 O?!. X-ray diffraction showed phase-pure tetragonal BQ.~ CQ.~~ T~ O~ for all reactor temperatures. Particle ...

Journal of Analytical and Applied Pyrolysis, May 31, 2011

Pyrolysis oils were produced from hardwood or softwood feedstocks in a vacuum batch reactor and t... more Pyrolysis oils were produced from hardwood or softwood feedstocks in a vacuum batch reactor and trapped at 0° C. The vacuum process was used to intentionally avoid the presence of entrained char particles. The hardwood feedstock was a pelletized mixture of various Eastern tree species. The softwood samples were de-barked Lodgepole pine (Pinus contorta) and Douglas Fir (Pseudotsuga menziesii) wood cut into the same dimensions as the pellets. The oils' physical (viscosity) and chemical (speciation) properties were ...

The Science of the total environment, Jan 2, 2018

A large fraction of the global population relies on the inefficient combustion of solid fuels for... more A large fraction of the global population relies on the inefficient combustion of solid fuels for cooking and home heating, resulting in household exposure to combustion byproducts. In the southwestern United States, unhealthy air quality has been observed in some homes that use solid fuels as a primary source of heat on the Navajo Nation. In order to better understand how home heating fuel choice can influence indoor air quality in this region, we used recently developed low-cost electrochemical sensors to measure carbon monoxide (CO) air mole fractions continuously inside and outside 41 homes in two communities on the Navajo Nation. Using low-cost sensors in this study, which don't require extensive training to operate, enabled collaboration with local Diné College students and faculty in the planning and implementation of home deployments. Households used natural gas, propane, pellets, wood, and/or coal for heating. We developed quantification methods that included uncertaint...

Understanding the mechanisms of secondary organic aerosol formation is of critical importance for... more Understanding the mechanisms of secondary organic aerosol formation is of critical importance for assessing aerosol radiative forcing and improving air quality control. A key quantity describing the gas-to-particle conversion is the rate at which nanoparticles of certain size are formed per unit volume and time. The quantification of nanoparticle formation rates requires precise knowledge of growth rates. Here we present a newly developed DMA train capable of providing definitive growth rates from size distribution scan frequencies of 1 Hz. This system has proven to yield statistically significant data even at ultra-low post-classification concentrations of 0.1 cm−3. A chamber study of α-pinene ozonolysis under close-to-ambient conditions demonstrates the need for particle size distribution measurements with increased time resolution.

Environmental Science & Technology, 2007

Atmospheric Environment, 2006

Atmospheric Environment, 2008

The photooxidation of ∼1ppm α-pinene in the presence of increasing concentrations of NO2 was stud... more The photooxidation of ∼1ppm α-pinene in the presence of increasing concentrations of NO2 was studied in a Teflon® chamber at 72–88% relative humidity and 296–304K. The loss of α-pinene and formation of gas-phase products were followed using proton-transfer reaction mass spectrometry (PTR-MS). Gas-phase reaction products (and their yields) include formaldehyde (5±1%), formic acid (2.5±1.4%), methanol (0.6±0.3%), acetaldehyde (3.9±1.7%), acetic acid

Atmospheric Environment, 2007

Diurnal branch-level emission rates of biogenic volatile organic compounds (BVOC) including isopr... more Diurnal branch-level emission rates of biogenic volatile organic compounds (BVOC) including isoprene, monoterpenes (MT), and sesquiterpenes (SQT) were determined at the University of Michigan Biological Station for the tree species red maple (Acer rubrum), red oak (Quercus rubra), paper birch (Betula papyrifera), white pine (Pinus strobus), and big tooth aspen (Populus grandidentata). These emission rates were combined with detailed biomass distribution and meteorological data and incorporated into the canopy model, model of emissions of gasses and aerosols from nature (MEGAN), for estimating whole-canopy fluxes of isoprene. The modeled half-hour fluxes ðmg C m À2 h À1 Þ and cumulative seasonal fluxes ðmg C m À2 Þ compared favorably with results from direct, canopy-level eddy covariance (EC) isoprene measurements; modeled cumulative seasonal flux deviated less than 30% from the EC results. Significant MT emissions were found from four of the five tree species. MT emissions from three of these were both light-and temperature-dependent and were approximately one order of magnitude greater than light-independent MT emissions. SQT emissions were identified from three of the five tree species. The model was modified to incorporate SQT and both light-dependent and light-independent MT emissions for determining fluxes. Isoprene comprised 495% of the total terpenoid flux with MT and SQT comprising 4% and 0.3%, respectively. The average cumulative fluxes (in mg C m À2) from June through September were 2490 for isoprene, 105 for MT, and 7 for SQT. A simple box model analysis was used to estimate the contribution of the isoprene, MT, and SQT emissions to the total OH reactivity. These results confirm that isoprene dominates OH reactions especially during daytime hours. Emissions of reactive MT and SQT increase the BVOC+OH reactivity, but are still lower than estimates of BVOC fluxes at this site necessary for affecting OH reactivity to the significant degree suggested by recent reports.

Atmospheric Chemistry and Physics, 2008

Atmospheric Chemistry and Physics, 2010

Aerosol Science and Technology, 2012

Atmospheric Chemistry and Physics Discussions, 2014

The Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H 2 O, Organics & Nitrogen (BE... more The Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H 2 O, Organics & Nitrogen (BEACHON) project seeks to understand the feedbacks and interrelationships between hydrology, biogenic emissions, carbon assimilation, aerosol properties, clouds and associated feedbacks within water-limited ecosystems. The

Aerosol Science and Technology

Several different types of measurements of particle size and concentration were compared during t... more Several different types of measurements of particle size and concentration were compared during the 2016 Airborne Research Instrumentation Testing Opportunity (ARISTO) campaign. The scanning mobility particle sizer (SMPS) measured number-size distributions for mobility diameters between 20−350and20-350 and 20−350and8-110 nm, depending on the mobility analyzer chosen. Also included were two stand-alone condensation particle counters (CPC) for determining size-integrated particle concentrations. A wing-mounted and a rack-mounted Ultra-High Sensitivity Aerosol Spectrometer (UHSAS) were used to measure size distributions between 60 and 1000 nm. Lastly, two different sampling inlets were used to investigate performance and observe any systematic biases. Most sampling occurred during cloud-free summer conditions in the western United States. Number concentrations from the two CPCs typically agreed within 12% once the flows in the ultrafine particle counter were corrected as a function of pressure. As expected, the size-integrated number concentrations from the SMPS and UHSAS were generally less than those of the CPCs, as the former cover only part of the total range of particle sizes measured by the CPCs. Integrated number concentrations from the wing-mounted and rack-mounted UHSAS generally agreed within 20% for all diameter ranges analyzed. The overlap region between the SMPS and the UHSAS showed reasonable agreement of ±20%. Some of the uncertainty regarding these measurement comparisons originates from a variety of factors, including sampling frequency, particle refractive index, differences between physical and mobility diameters, and counting efficiency uncertainties in the UHSAS optical cavity, especially for the smallest diameters (60-100 nm).

Nature, Jan 11, 2016

Nitrogen oxides are essential for the formation of secondary atmospheric aerosols and of atmosphe... more Nitrogen oxides are essential for the formation of secondary atmospheric aerosols and of atmospheric oxidants such as ozone and the hydroxyl radical, which controls the self-cleansing capacity of the atmosphere. Nitric acid, a major oxidation product of nitrogen oxides, has traditionally been considered to be a permanent sink of nitrogen oxides. However, model studies predict higher ratios of nitric acid to nitrogen oxides in the troposphere than are observed. A 'renoxification' process that recycles nitric acid into nitrogen oxides has been proposed to reconcile observations with model studies, but the mechanisms responsible for this process remain uncertain. Here we present data from an aircraft measurement campaign over the North Atlantic Ocean and find evidence for rapid recycling of nitric acid to nitrous acid and nitrogen oxides in the clean marine boundary layer via particulate nitrate photolysis. Laboratory experiments further demonstrate the photolysis of particulat...

Chemistry of Materials, 1991

Submicron particles of barium calcium titanate (B%. C%. 14Ti0J were generated by aerosol decompos... more Submicron particles of barium calcium titanate (B%. C%. 14Ti0J were generated by aerosol decomposition at reactor temperatures ranging from 900 to 1600 O?!. X-ray diffraction showed phase-pure tetragonal BQ.~ CQ.~~ T~ O~ for all reactor temperatures. Particle ...

Environmental science & …, 2005

Atmospheric standards containing parts-per-billion levels of 14 semivolatile hydrocarbon compound... more Atmospheric standards containing parts-per-billion levels of 14 semivolatile hydrocarbon compounds, including eight sesquiterpenes (SQTs) (longipinene, alpha-copaene, isolongifolene, alpha-cedrene, trans-caryophyllene, aromadendrene, alpha-humulene, delta-cadinene), two oxidized sesquiterpenoids (cisnerolidol, trans-nerolidol), one biogenic ketone (geranylacetone) and three aromatic compounds (1,3,5-triisopropylbenzene, diphenylmethane, nonylbenzene), were collected onto four solid adsorbent materials at increasing ozone mixing ratios (0-100 ppbv 03) for analysis by thermodesorption-gas chromatography. Substantial sampling losses of up to >90% were found for the most reactive SQT, even at the lowest ozone level investigated of 20 ppbv. Loss rates from the ozone-SQT reaction were used to derive estimates of gas-phase ozone reaction rate constants for longipinene, alpha-copaene, isolongifolene, geranylacetone, aromadendrene, delta-cadinene, cis-nerolidol, and transnerolidol. Three different ozone mitigation techniques were investigated to prevent these sampling losses. These strategies included (a) placing glass fiber filters impregnated with sodium thiosulfate (Na2S2O3) into the sampling line, (b) titration of ozone in the sampling stream with nitric oxide (NO), and (c) catalytically removing ozone with a commercially available manganese dioxide (MnO2) catalyst. All three techniques reduced ozone-mixing ratios from 100 ppbv to <0.6 ppbv at sampling flow rates of 1 L min(-1). When the Na2S2O3 filters and the NO-titration techniques were applied, SQT loss rates decreased from 25-60% to 0-5% for most SQT compounds and from >90% to approximately 10-50% for the two most reactive compounds at ozone mixing ratios of up to 100 ppbv. The commercial manganese dioxide scrubber, however, caused complete analyte losses (>98%) even at 0 ppbv ozone. These results underline the need and present applicable techniques for removal of ozone in air samples for SQT analysis by solid adsorption techniques.

Atmospheric Chemistry and Physics, 2009

As part of the MILAGRO field campaign, the DOE G-1 aircraft was used to make measurements over an... more As part of the MILAGRO field campaign, the DOE G-1 aircraft was used to make measurements over and downwind of Mexico City with the objective of determining growth characteristics of aerosols from a megacity urban source. This study focuses on number concentration and size distributions. It is found that a 5-fold increase in aerosol volume is accompanied by about a 5-fold increase in accumulation mode number concentration. There is growth in aerosol volume because there are more accumulation mode particles, not because of an increase in the average size of accumulation particles. Condensation and volume growth laws were examined to see whether either is consistent with observations. Condensation calculations show that the growth of Aitken mode particles into the accumulation mode size range gives the required increase in number concentration. There are minimal changes in the accumulation mode size distribution with age, consistent with observations. Volume-growth in contrast yields a population of large particles, distinctly different from what is observed. Detailed model calculations are required to translate our observations into specific information on the volatility and properties of secondary organic aerosol.

Atmospheric Environment, 2009

... 2, Allée du Parc de Brabois F-54514 Vandoeuvre-lès-Nancy Cedex France Phone: +33 (0)3 83 50 4... more ... 2, Allée du Parc de Brabois F-54514 Vandoeuvre-lès-Nancy Cedex France Phone: +33 (0)3 83 50 46 64 Fax ... SPICER Chester W. ; HOLDREN Michael W. ; COWEN Kenneth A. ; JOSEPH Darrell W. ; SATOLA Jan ; GOODWIN Bradley ; MAYFIELD Howard ; LASKIN Alexander ...

Atmospheric …, 2009

Aircraft emissions affect air quality on scales from local to global. More than 20% of the jet fu... more Aircraft emissions affect air quality on scales from local to global. More than 20% of the jet fuel used in the U.S. is consumed by military aircraft, and emissions from this source are facing increasingly stringent environmental regulations, so improved methods for quickly and accurately determining emissions from existing and new engines are needed. This paper reports results of a study to advance the methods used for detailed characterization of military aircraft emissions, and provides emission factors for two aircraft: the F-15 fighter and the C-130 cargo plane. The measurements involved outdoor ground-level sampling downstream behind operational military aircraft. This permits rapid change-out of the aircraft so that engines can be tested quickly on operational aircraft. Measurements were made at throttle settings from idle to afterburner using a simple extractive probe in the dilute exhaust. Emission factors determined using this approach agree very well with those from the traditional method of extractive sampling at the exhaust exit. Emission factors are reported for CO 2 , CO, NO, NO x , and more than 60 hazardous and/or reactive organic gases. Particle size, mass and composition also were measured and are being reported separately. Comparison of the emissions of nine hazardous air pollutants from these two engines with emissions from nine other aircraft engines is discussed.

Atmospheric Environment, 2008

The photooxidation of ∼1ppm α-pinene in the presence of increasing concentrations of NO2 was stud... more The photooxidation of ∼1ppm α-pinene in the presence of increasing concentrations of NO2 was studied in a Teflon® chamber at 72–88% relative humidity and 296–304K. The loss of α-pinene and formation of gas-phase products were followed using proton-transfer reaction mass spectrometry (PTR-MS). Gas-phase reaction products (and their yields) include formaldehyde (5±1%), formic acid (2.5±1.4%), methanol (0.6±0.3%), acetaldehyde (3.9±1.7%), acetic acid

Chemistry of …, 1991

Submicron particles of barium calcium titanate (B%. C%. 14Ti0J were generated by aerosol decompos... more Submicron particles of barium calcium titanate (B%. C%. 14Ti0J were generated by aerosol decomposition at reactor temperatures ranging from 900 to 1600 O?!. X-ray diffraction showed phase-pure tetragonal BQ.~ CQ.~~ T~ O~ for all reactor temperatures. Particle ...

Journal of Analytical and Applied Pyrolysis, May 31, 2011

Pyrolysis oils were produced from hardwood or softwood feedstocks in a vacuum batch reactor and t... more Pyrolysis oils were produced from hardwood or softwood feedstocks in a vacuum batch reactor and trapped at 0° C. The vacuum process was used to intentionally avoid the presence of entrained char particles. The hardwood feedstock was a pelletized mixture of various Eastern tree species. The softwood samples were de-barked Lodgepole pine (Pinus contorta) and Douglas Fir (Pseudotsuga menziesii) wood cut into the same dimensions as the pellets. The oils' physical (viscosity) and chemical (speciation) properties were ...