Photochemical Aging of α-pinene and β-pinene Secondary Organic Aerosol formed from Nitrate Radical Oxidation

Abstract

The nitrate radical (NO3) is the dominant nighttime oxidant in most urban and rural environments and reacts rapidly with biogenic volatile organic compounds to form secondary organic aerosol (SOA) and organic nitrates (ON). Here, we study the formation of SOA and ON from the NO3 oxidation of two monoterpenes (α-pinene and β-pinene) and investigate how they evolve during photochemical aging. High SOA mass loadings are produced in the NO3+β-pinene reaction, during which we detected 41 highly oxygenated gas- and particle-phase ON possessing 4 to 9 oxygen atoms. The fraction of particle-phase ON in the β-pinene SOA remains fairly constant during photochemical aging. In contrast to the NO3+β-pinene reaction, low SOA mass loadings are produced during the NO3+α-pinene reaction, during which only 5 highly oxygenated gas- and particle-phase ON are detected. The majority of the particle-phase ON evaporates from the α-pinene SOA during photochemical aging, thus exhibiting a drastically different behavior from that of β-pinene SOA. Our results indicate that nighttime ON formed by NO3+monoterpene chemistry can serve as either permanent or temporary NOx sinks depending on the monoterpene precursor.

Highly functionalized organic nitrates in the southeast United States: Contribution to secondary organic aerosol and reactive nitrogen budgets

“…S1 and S2) in chamber studies of both monoterpenes and isoprene oxidation in the presence of nitrogen oxides. Recent work with a similar methodology also shows highly oxygenated ON from other monoterpenes (37). Moreover, the fact that the relative abundances of species within each carbon number group differ between the particle ( Fig.…”

Decadal changes in summertime reactive oxidized nitrogen and surface ozone over the Southeast United States

“…Field and laboratory studies have indicated a potential contribution to the aerosol formation of organic nitrates from BVOC oxidation Fry et al, 2009Fry et al, , 2014Nah et al, 2016;Rollins et al, 2009;Rindelaub et al, 2015;Boyd et al, 2015Boyd et al, , 2017Lee et al, 2016;Ng et al, 2008;Xu et al, 2015;Lee et al, 2014;Bean and Hildebrandt Ruiz, 2016;Spittler et al, 2006). Aerosol yield depends on both the VOC precursor and the oxidant.…”

“…For example, -3-carene oxidation by NO 3 can produce a 38-65 % yield of organic aerosols in a smog chamber (Fry et al, 2014), which is much higher than the 1-24 % yield from NO 3 -initiated isoprene oxidation (Ng et al, 2008;Rollins et al, 2009;Ayres et al, 2015). Recent chamber studies indicate a very low aerosol yield from α-pinene oxidation by NO 3 (Nah et al, 2016;Fry et al, 2014); the aerosol yield increases to ∼ 18 % when α-pinene is oxidized by OH (Rollins et al, 2010;Rindelaub et al, 2015). However, these results might not be representative of atmospheric conditions in terms of the RO 2 reaction partner or RO 2 lifetime, warranting further studies on the effects of RO 2 fates on aerosol formation (Boyd et al, , 2017Ng et al, 2008;Schwantes et al, 2015).…”

“…This is further complicated by particle-phase RONO 2 , an important component of secondary organic aerosol (SOA) over the Southeast US Lee et al, 2016). The fate of particle-phase RONO 2 is unclear, with the possibility for removal by hydrolysis to form HNO 3 (Jacobs et al, 2014;Hu et al, 2011;Rindelaub et al, 2015;Szmigielski et al, 2010;Sato, 2008;Romer et al, 2016;Wolfe et al, 2015;Boyd et al, , 2017Bean and Hildebrandt Ruiz, 2016), photochemical aging (Nah et al, 2016), and deposition . To what extent RONO 2 affects the partitioning of RON and surface ozone remains to be elucidated.…”

Photooxidation of cyclohexene in the presence of SO<sub>2</sub>: SOA yield and chemical composition

“…Reactions of ozone with alkenes are an important source of free radicals in the lower atmosphere and thus highly influence the oxidative capacity of the atmosphere (Paulson and Orlando, 1996). Some products of these reactions have sufficiently low vapour pressure, allowing them to condense with other gaseous species, and contribute to the secondary organic aerosol (SOA) mass (Sarwar and Corsi, 2007;Sakamoto et al, 2013;Nah et al, 2016;Kroll and Seinfeld, 2008;Hallquist et al, 2009). SOA formation from the oxidation of VOCs has been receiving significant attention in recent years due to its large implication in the formation of atmospheric fine particulate matter (Jimenez et al, 2009).…”