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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2018-530
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
13 Jun 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Chemistry and Physics (ACP).
A comprehensive organic nitrate chemistry: insights into the lifetime of atmospheric organic nitrates
Azimeh Zare1, Paul S. Romer1, Tran Nguyen2, Frank N. Keutsch3,a, Kate Skog3,b, and Ronald C. Cohen1,4 1Department of Chemistry, University of California Berkeley, Berkeley, CA, USA
2College of Agricultural and Environmental Sciences, University of California, Davis, CA, USA
3Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
4Department of Earth and Planetary Sciences, University of California Berkeley, Berkeley, CA, USA
anow at: School of Engineering and Applied Sciences and Department of Chemistry & Chemical Biology, Harvard University, Cambridge, MA, USA
bnow at: Department of Chemical & Environmental Engineering, Yale University, New Haven, CT, USA
Abstract. Organic nitrate chemistry is the primary control over the lifetime of nitrogen oxides (NOx) in rural and remote continental locations. As NOx emissions decrease, organic nitrate chemistry becomes increasingly important to urban air quality. However, the lifetime of individual organic nitrates and the reactions that lead to their production and removal remain relatively poorly constrained, causing organic nitrates to be poorly represented by models. Guided by recent laboratory and field studies, we developed a detailed gas phase chemical mechanism representing most of the important individual organic nitrates. We use this mechanism within the WRF-Chem model to describe the role of organic nitrates in nitrogen oxide chemistry and in comparisons to observations. We find the daytime lifetime of total organic nitrates with respect to all loss mechanisms to be 2.6 h in the model. This is consistent with analyses of observations at a rural site in central Alabama during the Southern Oxidant and Aerosol Study (SOAS) in summer 2013. The lifetime of the first-generation organic nitrates is ~ 2 h versus the 3.2 h lifetime of secondary nitrates produced by oxidation of the first-generation nitrates. The different generations are subject to different losses, with dry deposition to the surface dominant loss process for the second-generation organic nitrates, and chemical loss dominant for the first-generation organic nitrates. Removal by hydrolysis is found to be responsible for the loss of ~ 30 % of the total organic nitrate pool.
Citation: Zare, A., Romer, P. S., Nguyen, T., Keutsch, F. N., Skog, K., and Cohen, R. C.: A comprehensive organic nitrate chemistry: insights into the lifetime of atmospheric organic nitrates, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-530, in review, 2018.
Azimeh Zare et al.
Azimeh Zare et al.
Azimeh Zare et al.

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Short summary
Organic nitrates play an important role in concentrations and distribution of NOx, ozone and aerosol as the most important air pollutants. We develop a state-of-the-science detailed chemical mechanism representing individual organic nitrates, which is appropriate to use in air quality models and results in a more accurate simulation of the atmospheric chemistry. Using this mechanism we explore production and removal process of organic nitrates in a rural environment that are poorly constrained.
Organic nitrates play an important role in concentrations and distribution of NOx, ozone and...
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