Autoxidation of Organic Compounds in the Atmosphere

Crounse, J. D.; Nielsen, Lasse B.; Jørgensen, Solvejg; Kjaergaard, Henrik G.; Wennberg, P. O.

doi:10.1021/jz4019207

Cited by 557 publications

(787 citation statements)

References 57 publications

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“…Oxygenated compounds contribute most of the mass flux due to the combined effect of their larger molecular weight from the incorporation of oxygen during oxidation (73), and the propensity for less-volatile and more-water-soluble compounds to deposit. The oxidant deposition observed by our instrument is attributed to hydroperoxides (−OOH), although we are missing the likely minor contribution of methyl hydroperoxide (MHP).…”

Section: Resultsmentioning

confidence: 99%

Rapid deposition of oxidized biogenic compounds to a temperate forest

Nguyen

Crounse

Teng

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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246

433

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We report fluxes and dry deposition velocities for 16 atmospheric compounds above a southeastern United States forest, including: hydrogen peroxide (H 2 O 2 ), nitric acid (HNO 3 ), hydrogen cyanide (HCN), hydroxymethyl hydroperoxide, peroxyacetic acid, organic hydroxy nitrates, and other multifunctional species derived from the oxidation of isoprene and monoterpenes. The data suggest that dry deposition is the dominant daytime sink for small, saturated oxygenates. Greater than 6 wt %C emitted as isoprene by the forest was returned by dry deposition of its oxidized products. Peroxides account for a large fraction of the oxidant flux, possibly eclipsing ozone in more pristine regions. The measured organic nitrates comprise a sizable portion (15%) of the oxidized nitrogen input into the canopy, with HNO 3 making up the balance. We observe that water-soluble compounds (e.g., strong acids and hydroperoxides) deposit with low surface resistance whereas compounds with moderate solubility (e.g., organic nitrates and hydroxycarbonyls) or poor solubility (e.g., HCN) exhibited reduced uptake at the surface of plants. To first order, the relative deposition velocities of water-soluble compounds are constrained by their molecular diffusivity. From resistance modeling, we infer a substantial emission flux of formic acid at the canopy level (∼1 nmol m −2 ·s −1 ). GEOS−Chem, a widely used atmospheric chemical transport model, currently underestimates dry deposition for most molecules studied in this work. Reconciling GEOS−Chem deposition velocities with observations resulted in up to a 45% decrease in the simulated surface concentration of trace gases.biosphere−atmosphere exchange | isoprene | dry deposition | OVOCs | fluxes

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Section: Resultsmentioning

confidence: 99%

Rapid deposition of oxidized biogenic compounds to a temperate forest

Nguyen

Crounse

Teng

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

246

433

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“…An important characteristic of the organic molecules participating in nucleation is their high oxygen content and consequently low vapor pressure. The formation of these highly oxygenated molecules (HOMs) has been described by Ehn et al (2014), who found that, following the well-known initial steps of α-pinene ozonolysis through a Criegee intermediate leading to the formation of an RO 2 · radical, several repeated cycles of intramolecular hydrogen abstractions and O 2 additions produce progressively more oxygenated RO 2 radicals, a mechanism called autoxidation (Crounse et al, 2013). The (extremely) low volatility of the HOMs results in efficient NPF and growth, even in the absence of sulfuric acid .…”

Section: Introductionmentioning

confidence: 99%

Influence of temperature on the molecular composition of ions and charged clusters during pure biogenic nucleation

et al. 2018

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Abstract. It was recently shown by the CERN CLOUD experiment that biogenic highly oxygenated molecules (HOMs) form particles under atmospheric conditions in the absence of sulfuric acid, where ions enhance the nucleation rate by 1-2 orders of magnitude. The biogenic HOMs were produced from ozonolysis of α-pinene at 5 • C. Here we extend this study to compare the molecular composition of positive and negative HOM clusters measured with atmospheric pressure interface time-of-flight mass spectrometers (APi-TOFs), at three different temperatures (25, 5 and −25 • C). Most negative HOM clusters include a nitrate (NO − 3 ) ion, and the spectra are similar to those seen in the nighttime boreal forest. On the other hand, most positive HOM clusters include an ammonium (NH + 4 ) ion, and the spectra are characterized by mass bands that differ in their molecular weight by ∼ 20 C atoms, corresponding to HOM dimers. At lower temperatures the average oxygen to carbon (O : C) ratio of the HOM clusters decreases for both polarities, reflecting an overall reduction of HOM formation with decreasing temperature. This indicates a decrease in the rate of autoxidation with temperature due to a rather high activation energy as has previously been determined by quantum chemical calculations. Furthermore, at the lowest temperature (−25 • C), the presence of C 30 clusters shows that HOM monomers start to contribute to the nucleation of positive clusters. These experimental findings are supported by quantum chemical calculations of the binding energies of representative neutral and charged clusters.

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“…The formation of ELVOCs possibly involves intramolecular isomerization of RO 2 radicals. 30,[32][33][34][35] There is growing evidence that oligomers play a key role in initial particle formation from large alkenes because of their predicted very low vapor pressures. 19,36 In ozonolysis experiments where SCI were scavenged using small acids or water, particle nucleation was shown to be suppressed, suggesting that the oligomers formed from SCI were potentially the nucleating precursors.…”

Section: Introductionmentioning

confidence: 99%