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Title: Photooxidation of Alpha-Pinene at High Relative Humidity in the Presence of Increasing Concentrations of NOx

Abstract

The photooxidation of ~1 ppm alpha-pinene in the presence of increasing concentrations of NO2 was studied in a Teflon chamber at relative humidities from 70 - 88% and temperatures from 296 - 304 K. The loss of alpha-pinene and formation of gas phase products were followed using proton transfer reaction mass spectrometry (PTR-MS). Gas phase reaction products measured by PTR-MS 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 (10 + 2%), acetone (11.5 + 3.1%), pinonaldehyde (22 + 6%), and pinene oxide (0.9 + 0.1%). There was evidence of organic nitrates in the gas phase and small peaks were tentatively assigned to norpinonaldehyde, 4-oxopinonaldehyde, propanedial, 2,3-dioxobutanal and 3,5,6-trioxoheptanal or 3-hydroxymethyl-2,2-dimethylcyclobutylethanone. The formation and growth of new particles were followed using a scanning mobility particle sizer (SMPS), and their chemical composition was probed using single particle mass spectrometry (SPLAT II). SPLAT II analysis also provided measurements of the vacuum aerodynamic diameters of the newly formed secondary organic aerosol (SOA) particles and, in combination with the electrical mobility diameter, a particle density of 1.21 + 0.02 g cm-3 was calculated, 20% larger than often assumed in calculatingmore » SOA yields. SPLAT II showed that the suspended SOA consisted of a complex mixture of organic nitrates and organics, possibly including pinonic acid, pinic acid and trans-sobrerol. Three-wavelength light scattering measurements made using an integrating nephelometer were consistent with particles having a refractive index characteristic of organic compounds, but the data could not be well matched at all three wavelengths with a single refractive index. The effect of addition of cyclohexane or NO on particle formation showed that ozonolysis was the major mechanism of SOA formation in this system. However, unlike simple ozonolysis, organic nitrates are formed in both the gas and particle phases. Identifying and measuring specific organic nitrates in both the gas and particle phases in air may help to elucidate why SOA formation has been reported in field studies to be associated with polluted urban areas, yet the carbon in these particles is largely contemporary, i.e., non-fossil fuel carbon.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
945999
Report Number(s):
PNNL-SA-58440
Journal ID: ISSN 0004-6981; ATENBP; 24590; 17498; KC0302020; TRN: US200903%%894
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Atmospheric Environment, 42(20):5044-5060
Additional Journal Information:
Journal Volume: 42; Journal Issue: 20; Journal ID: ISSN 0004-6981
Country of Publication:
United States
Language:
English
Subject:
10 SYNTHETIC FUELS; ACETALDEHYDE; ACETIC ACID; ACETONE; AEROSOLS; CARBON; CHEMICAL COMPOSITION; CYCLOHEXANE; FORMALDEHYDE; FORMIC ACID; HUMIDITY; LIGHT SCATTERING; MASS SPECTROSCOPY; METHANOL; NITRATES; ORGANIC COMPOUNDS; OXIDES; PROTONS; REFRACTIVE INDEX; TEFLON; TRANSFER REACTIONS; WAVELENGTHS; Environmental Molecular Sciences Laboratory

Citation Formats

Yu, Yong, Ezell, Michael J., Zelenyuk, Alla, Imre, Dan G., Alexander, M. Lizabeth, Ortega, John V., D'Anna, Barbara, Harmon, Chris W., Johnson, Stan, and Finlayson-Pitts, Barbara J. Photooxidation of Alpha-Pinene at High Relative Humidity in the Presence of Increasing Concentrations of NOx. United States: N. p., 2008. Web. doi:10.1016/j.atmosenv.2008.02.026.
Yu, Yong, Ezell, Michael J., Zelenyuk, Alla, Imre, Dan G., Alexander, M. Lizabeth, Ortega, John V., D'Anna, Barbara, Harmon, Chris W., Johnson, Stan, & Finlayson-Pitts, Barbara J. Photooxidation of Alpha-Pinene at High Relative Humidity in the Presence of Increasing Concentrations of NOx. United States. doi:10.1016/j.atmosenv.2008.02.026.
Yu, Yong, Ezell, Michael J., Zelenyuk, Alla, Imre, Dan G., Alexander, M. Lizabeth, Ortega, John V., D'Anna, Barbara, Harmon, Chris W., Johnson, Stan, and Finlayson-Pitts, Barbara J. Sun . "Photooxidation of Alpha-Pinene at High Relative Humidity in the Presence of Increasing Concentrations of NOx". United States. doi:10.1016/j.atmosenv.2008.02.026.
@article{osti_945999,
title = {Photooxidation of Alpha-Pinene at High Relative Humidity in the Presence of Increasing Concentrations of NOx},
author = {Yu, Yong and Ezell, Michael J. and Zelenyuk, Alla and Imre, Dan G. and Alexander, M. Lizabeth and Ortega, John V. and D'Anna, Barbara and Harmon, Chris W. and Johnson, Stan and Finlayson-Pitts, Barbara J.},
abstractNote = {The photooxidation of ~1 ppm alpha-pinene in the presence of increasing concentrations of NO2 was studied in a Teflon chamber at relative humidities from 70 - 88% and temperatures from 296 - 304 K. The loss of alpha-pinene and formation of gas phase products were followed using proton transfer reaction mass spectrometry (PTR-MS). Gas phase reaction products measured by PTR-MS 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 (10 + 2%), acetone (11.5 + 3.1%), pinonaldehyde (22 + 6%), and pinene oxide (0.9 + 0.1%). There was evidence of organic nitrates in the gas phase and small peaks were tentatively assigned to norpinonaldehyde, 4-oxopinonaldehyde, propanedial, 2,3-dioxobutanal and 3,5,6-trioxoheptanal or 3-hydroxymethyl-2,2-dimethylcyclobutylethanone. The formation and growth of new particles were followed using a scanning mobility particle sizer (SMPS), and their chemical composition was probed using single particle mass spectrometry (SPLAT II). SPLAT II analysis also provided measurements of the vacuum aerodynamic diameters of the newly formed secondary organic aerosol (SOA) particles and, in combination with the electrical mobility diameter, a particle density of 1.21 + 0.02 g cm-3 was calculated, 20% larger than often assumed in calculating SOA yields. SPLAT II showed that the suspended SOA consisted of a complex mixture of organic nitrates and organics, possibly including pinonic acid, pinic acid and trans-sobrerol. Three-wavelength light scattering measurements made using an integrating nephelometer were consistent with particles having a refractive index characteristic of organic compounds, but the data could not be well matched at all three wavelengths with a single refractive index. The effect of addition of cyclohexane or NO on particle formation showed that ozonolysis was the major mechanism of SOA formation in this system. However, unlike simple ozonolysis, organic nitrates are formed in both the gas and particle phases. Identifying and measuring specific organic nitrates in both the gas and particle phases in air may help to elucidate why SOA formation has been reported in field studies to be associated with polluted urban areas, yet the carbon in these particles is largely contemporary, i.e., non-fossil fuel carbon.},
doi = {10.1016/j.atmosenv.2008.02.026},
journal = {Atmospheric Environment, 42(20):5044-5060},
issn = {0004-6981},
number = 20,
volume = 42,
place = {United States},
year = {2008},
month = {6}
}