Highly functionalized organic nitrates in the southeast United States: Contribution to secondary organic aerosol and reactive nitrogen budgets
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- Department of Atmospheric Sciences, University of Washington, Seattle, WA 98195,
- Department of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, SE-41296 Gothenburg, Sweden,
- Department of Chemistry, University of California, Berkeley, CA 94720,
- Department of Chemistry, Laboratory of Physical Chemistry, University of Helsinki, Helsinki FIN-00014, Finland,
- Department of Chemistry and Biochemistry, University of Colorado Boulder, Boulder, CO 80309,, Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309,
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332,
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332,, School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332,
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332,
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309,, Chemical Sciences Division, National Oceanic and Atmospheric Administration, Boulder, CO 80305,
- Chemical Sciences Division, National Oceanic and Atmospheric Administration, Boulder, CO 80305,
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720,
- Department of Earth System Science, School of Physical Sciences, University of California, Irvine, CA 92697,
- Departments of Chemistry and Earth, Atmospheric and Planetary Sciences and Purdue Climate Change Research Center, Purdue University, West Lafayette, IN 47907,
- Department of Chemistry, West Chester University, West Chester, PA 19383,
- Atmospheric Research and Analysis, Inc., Cary, NC 27513,
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA 99352,
- Department of Meteorology, Pennsylvania State University, University Park, PA 16802,
- Department of Chemistry, University of Washington, Seattle, WA 98195
Organic nitrates (ON = RONO2 + RO2NO2) are an important reservoir, if not sink, of atmospheric nitrogen oxides (NOx=NO+NO2). ON formed from isoprene oxidation alone are responsible for the export of 8 to 30% of anthropogenic NOx out of the U.S. continental boundary layer [Horowitz et al., 1998; Liang et al., 1998]. Regional NOx budgets and tropospheric ozone (O3) production, are therefore particularly sensitive to uncertainties in the yields and fates of ON [Beaver et al., 2012; Browne et al., 2013]. The yields implemented in modeling studies are determined from laboratory experiments in which only a few of the first generation gaseous ON or the total gas and particle-phase ON have been quantified [Perring et al., 2013 and references therein], while production of highly functionalized ON capable of strongly partitioning to the particle-phase have been inferred [Farmer et al., 2010; Ng et al., 2007; Nguyen et al., 2011; Perraud et al., 2012; Rollins et al., 2012], or directly measured [Ehn et al., 2014]. Addition of a nitrate (–ONO2) functional group to a hydrocarbon is estimated to lower the equilibrium saturation vapor pressure by 2.5 to 3 orders of magnitude [e.g. Capouet and Muller, 2006]. Thus, organic nitrate formation can potentially enhance particle-phase partitioning of hydrocarbons in regions with elevated levels of nitrogen oxides, contributing to secondary organic aerosol (SOA) formation [Ng et al., 2007]. There has, however, been no high time-resolved measurements of speciated ON in the particle-phase. We utilize a newly developed high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) using Iodide-adduct ionization [B H Lee et al., 2014a] with a filter inlet for gases and aerosols (FIGAERO) [Lopez-Hilfiker et al., 2014] that allows alternating in situ measurement of the molecular composition of gas and particle phases. We present observations of speciated ON in the particle-phase obtained during the 2013 Southern Oxidant and Aerosol Study (SOAS). We compare these speciated measurements to total unspeciated particulate organic nitrate measured by three independent methods, and analyze using a zero-dimensional box model the diel cycles of individual components to elucidate differential source and sink terms. Biogenic volatile organic compounds (VOCs), including isoprene, monoterpenes, and sesquiterpenes appear to dominate the ON sources during SOAS. We show that the molecular compositions that dominate the particle-phase are significantly more oxygenated than the most abundant gas-phase counterparts, consistent with volatility and solubility driven partitioning requirements. However, the detailed mechanisms by which most of these ON arise are not yet clear. These speciated measurements put a strong constraint on the extent to which ON directly contribute to SOA in regions with high biogenic hydrocarbon emissions, and illustrate that the fate of particulate ON can have significant implications for SOA and the reactive nitrogen budget.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Univ. of Washington, Seattle, WA (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- SC0004577; SC0006867; SC0011791; AC05-76RL01830
- OSTI ID:
- 1235971
- Alternate ID(s):
- OSTI ID: 1255381; OSTI ID: 1390589
- Report Number(s):
- PNNL-SA-110400
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Vol. 113 Journal Issue: 6; ISSN 0027-8424
- Publisher:
- Proceedings of the National Academy of SciencesCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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