%0 Journal Article %1 Lambe:2009p2675 %A Lambe, Andrew T %A Miracolo, Marissa A %A Hennigan, Christopher J %A Robinson, Allen L %A Donahue, Neil M %D 2009 %J Environmental Science & Technology %K Diffusion, Emissions, Heterogeneous Hydrocarbons, Mass, Model Oh, Oxidation, Particle, Phase, Volatility, %N 23 %P 8794--8800 %R 10.1021/es901745h %T Effective Rate Constants and Uptake Coefficients for the Reactions of Organic Molecular Markers (n-Alkanes, Hopanes, and Steranes) in Motor Oil and Diesel Primary Organic Aerosols with Hydroxyl Radicals %U http://pubs.acs.org/doi/abs/10.1021/es901745h %V 43 %X Hydroxyl radical (OH) uptake by organic aerosols, followed by heterogeneous oxidation, happens nearly at the collision frequency. Oxidation complicates the use of organic molecular markers such as hopanes for source apportionment since receptor models assume markers are stable during transport We report the oxidation kinetics of organic molecular markers (C-25-C-32 n-alkanes, hopanes and steranes) in motor oil and primary organic aerosol emitted from a diesel engine at atmospherically relevant conditions inside a smog chamber. A thermal desorption aerosol gas chromatograph/mass spectrometer (TAG) and Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) were used to measure the changes in molecular comosition and bulk primary organic aerosol. From the measured changes in molecular composition, we calculated effective OH rate constants, effective relative rate constants, and effective uptake coefficients for molecular markers. Oxidation rates varied with marker volatility, with more volatile markers being oxidized at rates much faster than could be explained from heterogeneous oxidation. This rapid oxidation can be explained by significant gas-phase OH oxidation that dominates heterogeneous oxidation, resulting in overall oxidation life times of 1 day or less. Based on our results, neglecting oxidation of molecular markers used for source apportionment could introduce significant error, since many common markers such as norhopane appear to be semivolatile under atmospheric conditions.

@article{Lambe:2009p2675, abstract = {Hydroxyl radical (OH) uptake by organic aerosols, followed by heterogeneous oxidation, happens nearly at the collision frequency. Oxidation complicates the use of organic molecular markers such as hopanes for source apportionment since receptor models assume markers are stable during transport We report the oxidation kinetics of organic molecular markers (C-25-C-32 n-alkanes, hopanes and steranes) in motor oil and primary organic aerosol emitted from a diesel engine at atmospherically relevant conditions inside a smog chamber. A thermal desorption aerosol gas chromatograph/mass spectrometer (TAG) and Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) were used to measure the changes in molecular comosition and bulk primary organic aerosol. From the measured changes in molecular composition, we calculated effective OH rate constants, effective relative rate constants, and effective uptake coefficients for molecular markers. Oxidation rates varied with marker volatility, with more volatile markers being oxidized at rates much faster than could be explained from heterogeneous oxidation. This rapid oxidation can be explained by significant gas-phase OH oxidation that dominates heterogeneous oxidation, resulting in overall oxidation life times of 1 day or less. Based on our results, neglecting oxidation of molecular markers used for source apportionment could introduce significant error, since many common markers such as norhopane appear to be semivolatile under atmospheric conditions.}, added-at = {2010-06-22T19:38:37.000+0200}, affiliation = {Carnegie Mellon Univ, Ctr Atmospher Particle Studies, Pittsburgh, PA 15213 USA}, author = {Lambe, Andrew T and Miracolo, Marissa A and Hennigan, Christopher J and Robinson, Allen L and Donahue, Neil M}, biburl = {https://www.bibsonomy.org/bibtex/285f2cce5518fe4f1f6ddaaeb1c9dd2e9/gsmith}, date-added = {2010-03-25 11:17:46 -0400}, date-modified = {2010-03-29 14:05:25 -0400}, doi = {10.1021/es901745h}, interhash = {d091bfcb03963481ca72b31b5d8043c0}, intrahash = {85f2cce5518fe4f1f6ddaaeb1c9dd2e9}, journal = {Environmental Science {\&} Technology}, keywords = {Diffusion, Emissions, Heterogeneous Hydrocarbons, Mass, Model Oh, Oxidation, Particle, Phase, Volatility,}, language = {English}, local-url = {file://localhost/Users/geoffreysmith/Documents/Papers/Environmental%20Science%20&%20Technology/2009/Environmental%20Science%20&%20Technology,%2043,%208794-8800%202009-2.pdf}, month = Jan, number = 23, pages = {8794--8800}, pmid = {000272038900022}, rating = {0}, read = {Yes}, timestamp = {2010-06-22T19:39:15.000+0200}, title = {Effective Rate Constants and Uptake Coefficients for the Reactions of Organic Molecular Markers (n-Alkanes, Hopanes, and Steranes) in Motor Oil and Diesel Primary Organic Aerosols with Hydroxyl Radicals}, uri = {papers://E88B624E-D406-46FF-9D95-BB9C1AAE3FDC/Paper/p2675}, url = {http://pubs.acs.org/doi/abs/10.1021/es901745h}, volume = 43, year = 2009 }