Secondary organic aerosol formation from semi‐ and intermediate‐volatility organic compounds and glyoxal: Relevance of O/C as a tracer for aqueous multiphase chemistry

Abstract

[1] The role of aqueous multiphase chemistry in the formation of secondary organic aerosol (SOA) remains difficult to quantify. We investigate it here by testing the rapid formation of moderate oxygen-to-carbon (O/C) SOA during a case study in Mexico City. A novel laboratorybased glyoxal-SOA mechanism is applied to the field data, and explains why less gas-phase glyoxal mass is observed than predicted. Furthermore, we compare an explicit gasphase chemical mechanism for SOA formation from semiand intermediate-volatility organic compounds (S/IVOCs) with empirical parameterizations of S/IVOC aging. The mechanism representing our current understanding of chemical kinetics of S/IVOC oxidation combined with traditional SOA sources and mixing of background SOA underestimates the observed O/C by a factor of two at noon. Inclusion of glyoxal-SOA with O/C of 1.5 brings O/C predictions within measurement uncertainty, suggesting that field observations can be reconciled on reasonable time scales using laboratory-based empirical relationships for aqueous chemistry. Citation: Waxman, E. M., K. Dzepina, B.Ervens, J. Lee-Taylor, B. Aumont, J.-L. Jimenez, S. Madronich, and R. Volkamer (2013), Secondary organic aerosol formation from semi-and intermediate-volatility organic compounds and glyoxal: Relevance of O/C as a tracer for aqueous multiphase chemistry, Geophys. Res. Lett., 40,[978][979][980][981][982]

Potential of Aerosol Liquid Water to Facilitate Organic Aerosol Formation: Assessing Knowledge Gaps about Precursors and Partitioning

“…These "salting-in" and "saltingout" effects are not typically accounted for when calculating partitioning and uptake coefficients for WSOGs other than glyoxal in models. 64,65 Recent field evidence suggests that isoprene−SOA is directly modulated by an abundance of sulfate in the southeastern U.S. 66 Sulfate-induced molality impacts on partitioning and uptake of isoprene oxidation products, 27,67 the subsequent rate of their multiphase reactions, 46,48 partitioning of reaction products, or a combination of these effects is consistent with these field observations. However, the dominant reason(s) for the strong associations between sulfate and this significant portion of ambient SOA remains elusive.…”

simpleGAMMA v1.0 – a reduced model of secondary organic aerosol formation in the aqueous aerosol phase (aaSOA)

“…A recent data analysis study using GAMMA (Sumner et al, 2014) suggested a possible role for photo-enhanced chemistry in aaSOA formation by glyoxal involving organic photosensitizers such as fulvic acid (Monge et al, 2012). This chemistry can be represented in simpleGAMMA by including irreversible glyoxal uptake with γ ∼ 10 −3 during sunlit hours, consistent with Fu et al (2008), who based their representation on the experiments of Liggio et al (2005), and with Waxman et al (2013). A reactive uptake formulation was also used by Pye et al (2013) to represent aaSOA formation by IEPOX.…”

Aqueous-phase mechanism for secondary organic aerosol formation from isoprene: application to the southeast United States and co-benefit of SO<sub>2</sub> emission controls

“…Glyoxal forms SOA with higher yields during the day than at night due to OH aqueousphase chemistry (Tan et al, 2009;Volkamer et al, 2009;Sumner et al, 2014). We use a daytime γ of 2.9 × 10 −3 for glyoxal from Liggio et al (2005) and a nighttime γ of 5 × 10 −6 (Waxman et al, 2013;Sumner et al, 2014). The SOA yield of methylglyoxal is small compared with that of glyoxal (McNeill et al, 2012).…”