Year-end Sale % OFF 
Abstract
Abstract. The yields of organic nitrates and of secondary organic aerosol (SOA) particle formation were measured for the reaction NO3+β-pinene under dry and humid conditions in the atmosphere simulation chamber SAPHIR at Research Center Jülich. These experiments were conducted at low concentrations of NO3 (NO3+N2O5<10 ppb) and β-pinene (peak~15 ppb), with no seed aerosol. SOA formation was observed to be prompt and substantial (~50% mass yield under both dry conditions and at 60% RH), and highly correlated with organic nitrate formation. The observed gas/aerosol partitioning of organic nitrates can be simulated using an absorptive partitioning model to derive an estimated vapor pressure of the condensing nitrate species of pvap~5×10−6 Torr (6.67×10−4 Pa), which constrains speculation about the oxidation mechanism and chemical identity of the organic nitrate. Once formed the SOA in this system continues to evolve, resulting in measurable aerosol volume decrease with time. The observations of high aerosol yield from NOx-dependent oxidation of monoterpenes provide an example of a significant anthropogenic source of SOA from biogenic hydrocarbon precursors. Estimates of the NO3+β-pinene SOA source strength for California and the globe indicate that NO3 reactions with monoterpenes are likely an important source (0.5–8% of the global total) of organic aerosol on regional and global scales.
Highlights
Recent studies indicate that SOA is a major fraction of total organic aerosol, up to 90% regionally (Turpin and Huntzicker, 1995; Kanakidou et al, 2005), with the source underestimated by 1–2 orders of magnitude in models, indicating that the chemistry of atmospheric secondary organic aerosol (SOA) formation remains incompletely understood
Large NO3-initiated aerosol formation from biogenic volatile organic compounds (VOCs) would provide one potential resolution to an apparent paradox noted in the SOA literature: while radiocarbon measurements indicate a large fraction of modern carbon in aerosol from urban (∼50%) to remote areas (80–100%) (Schichtel et al, 2008), SOA plumes in both types of locations have been frequently observed to be correlated with anthropogenic sources
We find that aerosol formation is correlated with organic nitrate formation, suggesting that this product channel is responsible for condensation and that ambient atmospheric aerosol formed via this mechanism should contain organic nitrate signatures
Summary
Organic material constitutes a major fraction (Kanakidou et al, 2005; Fuzzi et al, 2006; Zhang et al, 2007) of atmospheric aerosol particulate matter, which affects Earth’s climate by absorbing and scattering solar radiation and altering the brightness and lifetime of clouds (Forster et al, 2007) and has been implicated in asthma, heart and lung disease, and mortality (Dockery and Pope, 1994; Pope et al, 1995; Alfaro-Moreno et al, 2007; Pope, 2007). Large NO3-initiated aerosol formation from biogenic volatile organic compounds (VOCs) would provide one potential resolution to an apparent paradox noted in the SOA literature: while radiocarbon measurements indicate a large fraction of modern carbon in aerosol from urban (∼50%) to remote areas (80–100%) (Schichtel et al, 2008), SOA plumes in both types of locations have been frequently observed to be correlated with anthropogenic sources (de Gouw et al, 2005; Quinn et al, 2006; Weber et al, 2007). We find that aerosol formation is correlated with organic nitrate formation, suggesting that this product channel is responsible for condensation and that ambient atmospheric aerosol formed via this mechanism should contain organic nitrate signatures
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
