Atmospheric Oxidation Mechanism of Isoprene

Fan, Jiwen; Zhang, Renyi

doi:10.1071/en04045

Cited by 141 publications

(117 citation statements)

References 42 publications

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“…The asymmetry between Z/E isomers contradicts the conclusions drawn from quantum mechanical calculations (Dibble, 2002) as well as the assumption made by most kinetic models of isoprene photooxidation Fan and Zhang, 2004). The discrepancy with quantum mechanical calculations may be related to a difference in the reaction of the cis/trans radical with O 2 .…”

Section: Consequencescontrasting

confidence: 50%

Isoprene photooxidation: new insights into the production of acids and organic nitrates

et al. 2009

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Abstract. We describe a nearly explicit chemical mechanism for isoprene photooxidation guided by chamber studies that include time-resolved observation of an extensive suite of volatile compounds. We provide new constraints on the chemistry of the poorly-understood isoprene δ-hydroxy channels, which account for more than one third of the total isoprene carbon flux and a larger fraction of the nitrate yields. We show that the cis branch dominates the chemistry of the δ-hydroxy channel with less than 5% of the carbon following the trans branch. The modelled yield of isoprene nitrates is 12±3% with a large difference between the δ and β branches. The oxidation of these nitrates releases about 50% of the NO x . Methacrolein nitrates (modelled yield 15±3% from methacrolein) and methylvinylketone nitrates (modelled yield 11±3% yield from methylvinylketone) are also observed. Propanone nitrate, produced with a yield of 1% from isoprene, appears to be the longest-lived nitrate formed in the total oxidation of isoprene. We find a large molar yield of formic acid and suggest a novel mechanism leading to its formation from the organic nitrates. Finally, the most important features of this mechanism are summarized in a condensed scheme appropriate for use in global chemical transport models.

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Section: Consequencescontrasting

confidence: 50%

Isoprene photooxidation: new insights into the production of acids and organic nitrates

et al. 2009

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“…Biogenic and anthropogenic VOCs can react with oxidants to produce MeGly and Gly in gas phase in both daytime and nighttime. In daytime, important oxidants are OH radical (Fan and Zhang, 2004) and O 3 (Kamens et al, 1982). In contrast, the main oxidant in nighttime is NO 3 , which only react with biogenic VOCs such as isoprene and monoterpene emitted in the forest area (Warneke et al, 2004).…”

Section: Resultsmentioning

confidence: 99%

Distributions and diurnal changes of low molecular weight organic acids and ^|^alpha;-dicarbonyls in suburban aerosols collected at Mangshan, North China

Kawamura

2010

Geochem. J.

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Aerosol samples were collected at Mangshan in the north of Beijing, China in autumn 2007 and analyzed for α,ω-dicarboxylic acids (C 2 -C 12 ), ketoacids (ωC 2 -ωC 4 , ωC 9 , pyruvic acid) and α-dicarbonyls (glyoxal and methylglyoxal). Oxalic (C 2 ) acid was found as the most abundant species, followed by succinic (C 4 ) and malonic (C 3 ) acids. Concentrations of most compounds, except for C 2 and some other species, were higher in daytime than nighttime, indicating that diacids are produced by photochemical oxidation of organic precursors emitted from anthropogenic sources such as fossil-fuel combustion in Beijing, and are transported to Mangshan area by the northerly wind in daytime. Phthalic acid (Ph) was detected as the 4th most abundant diacid both in daytime and nighttime samples, indicating that anthropogenic sources significantly contribute to the organic aerosols. However, lower adipic (C 6 )/azelaic (C 9 ) acid ratios in nighttime than daytime suggest that biogenic source makes more contribution to the aerosols in nighttime. Higher ratios of C 2 /total diacids in nighttime than daytime suggest the aging of aerosols proceed more in nighttime, probably due to the aqueous phase oxidation of biogenic precursors. This study demonstrates that water-soluble organic aerosols are secondarily produced in the vicinity of Beijing by the oxidation of both anthropogenic and biogenic precursors.

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“…Biogenic and anthropogenic VOCs can react with oxidants to produce methylglyoxal (MeGly) and glyoxal (Gly) in gas phase. During mid-day, OH radicals are important oxidants (Fan and Zhang, 2004) as well as O 3 (Kamens et al, 1982). In contrast, the nighttime oxidant is mainly NO 3 , which attacks biogenic (such as monoterpenes and isoprene) and anthropogenic VOCs (Warneke et al, 2004).…”

Section: Possible Production Of Oxalic Acid In Nighttimementioning

confidence: 99%

Diurnal and temporal variations of water-soluble dicarboxylic acids and related compounds in aerosols from the northern vicinity of Beijing: Implication for photochemical aging during atmospheric transport

He¹,

Kawamura²,

Okuzawa³

et al. 2014

Science of The Total Environment

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Abstract:Aerosol samples were collected in autumn 2007 on day-and nighttime basis in the northern receptor site of Beijing, China. The samples were analyzed for total carbon (TC) and water-soluble dicarboxylic acids (C 2 -C 12 ), oxocarboxylic acids (C 2 -C 9 ), glyoxal and methylglyoxal to better understand the photochemical aging of organic aerosols in the vicinity of Beijing. Concentrations of TC are 50% greater in daytime when winds come from Beijing than in nighttime when winds come from the northern forest areas. Most diacids showed higher concentrations in daytime, suggesting that the organics emitted from the urban Beijing and delivered to the northern vicinity in daytime are subjected to photo-oxidation to result in diacids.However, oxalic acid (C 2 ), which is the most abundant diacid followed by C 3 or C 4 , became on average 30% more abundant in nighttime together with azelaic, ω-oxooctanoic and ω-oxononanoic acids, which are specific oxidation products of biogenic unsaturated fatty acids.Methylglyoxal, an oxidation product of isoprene and a precursor of oxalic acid, also became 29% more abundant in nighttime. Based on a positive correlation between C 2 and glyoxylic acid (ωC 2 ) in nighttime when relative humidity significantly enhanced, we propose a nighttime aqueous phase production of C 2 via the oxidation of ωC 2 . We found an increase in the contribution of diacids to TC by 3 folds during consecutive clear days. This study demonstrates that diacids and related compounds are largely produced in the northern vicinity of Beijing via photochemical processing of organic precursors emitted from urban center and forest areas.

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Atmospheric Oxidation Mechanism of Isoprene

Cited by 141 publications

References 42 publications

Isoprene photooxidation: new insights into the production of acids and organic nitrates

Isoprene photooxidation: new insights into the production of acids and organic nitrates

Distributions and diurnal changes of low molecular weight organic acids and ^|^alpha;-dicarbonyls in suburban aerosols collected at Mangshan, North China

Diurnal and temporal variations of water-soluble dicarboxylic acids and related compounds in aerosols from the northern vicinity of Beijing: Implication for photochemical aging during atmospheric transport

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