Formation of Low Volatility Organic Compounds and Secondary Organic Aerosol from Isoprene Hydroxyhydroperoxide Low-NO Oxidation

Abstract

Gas-phase low volatility organic compounds (LVOC), produced from oxidation of isoprene 4-hydroxy-3-hydroperoxide (4,3-ISOPOOH) under low-NO conditions, were observed during the FIXCIT chamber study. Decreases in LVOC directly correspond to appearance and growth in secondary organic aerosol (SOA) of consistent elemental composition, indicating that LVOC condense (at OA below 1 μg m–3). This represents the first simultaneous measurement of condensing low volatility species from isoprene oxidation in both the gas and particle phases. The SOA formation in this study is separate from previously described isoprene epoxydiol (IEPOX) uptake. Assigning all condensing LVOC signals to 4,3-ISOPOOH oxidation in the chamber study implies a wall-loss corrected non-IEPOX SOA mass yield of ∼4%. By contrast to monoterpene oxidation, in which extremely low volatility VOC (ELVOC) constitute the organic aerosol, in the isoprene system LVOC with saturation concentrations from 10–2 to 10 μg m–3 are the main constituents. These LVOC may be important for the growth of nanoparticles in environments with low OA concentrations. LVOC observed in the chamber were also observed in the atmosphere during SOAS-2013 in the Southeastern United States, with the expected diurnal cycle. This previously uncharacterized aerosol formation pathway could account for ∼5.0 Tg yr–1 of SOA production, or 3.3% of global SOA.

In situ secondary organic aerosol formation from ambient pine forest air using an oxidation flow reactor

“…Based on previous modeling and measurements, we assume α = 1 for LVOCs (Kulmala and Wagner, 2001;Julin et al, 2014;Krechmer et al, 2015). A sensitivity study on the values of D, the impact of deviations from α = 1, and the choice of SMPS size distribution used to calculate CS is discussed below in Sect.…”

“…These chamber experiments have provided the SOA yields for models, but recent evidence shows that chamber experiments are affected by large losses of semivolatile gases to chamber walls (Matsunaga and Ziemann, 2010;Zhang et al, 2014;Krechmer et al, 2015) in addition to well-known particle wall losses (Pierce et al, 2008). This is especially true at long (> 1 day) residence times, making it difficult to study SOA formation and aging on longer timescales.…”

Effects of gas–wall partitioning in Teflon tubing and instrumentation on time-resolved measurements of gas-phase organic compounds

“…Past work has proposed using desorption kinetics inside an inlet as a technique for identifying compounds (Schuhfried et al, 2012), and the model presented here can be used in a similar way. Another possible application is to induce time separation among different compounds that are otherwise indistinguishable to the analytical instrumentation (e.g., compounds with the same accurate mass in chemical ionization mass spectrometry (CIMS); Stark et al, 2015), since the c * of multifunctional compounds with the same molecular formula can often differ by 5 orders of magnitude (Krechmer et al, 2015). The separation in time can then be exploited via manual analyses or factor analysis techniques (e.g., Ulbrich et al, 2009).…”

“…Values of C w reported by Matsunaga and Ziemann (2010), Yeh and Ziemann (2015), and Krechmer et al (2016) ber, a range indicating that a significant fraction of organic products formed from oxidation reactions regularly studied in environmental chambers (and even some less-volatile precursors) will be absorbed into the walls at equilibrium. Using typical values for C w and the timescale for reaching gas-wall partitioning equilibrium, one can incorporate the effect into box models to estimate the effect of partitioning on chamber measurements, as has been done in several studies of secondary organic aerosol yields (Matsunaga and Ziemann, 2010;Shiraiwa et al, 2013;McVay et al, 2014;Bian et al, 2015;Krechmer et al, 2015;La et al, 2016).…”

The role of highly oxygenated molecules (HOMs) in determining the composition of ambient ions in the boreal forest

“…Although Bianchi et al (2016) observed that new particle formation in the free troposphere depends on the availability of highly oxidised organic species, they saw only a weak ion enhancement. Several studies have also demonstrated that the compounds participating in this process, highly oxygenated molecules (HOMs), often play a central role in NPF events (Kulmala et al, 1998;Ehn et al, 2014;Krechmer et al, 2015;Ortega et al, 2016;Bianchi et al, 2016).…”