Measurement of interferences associated with the detection of the hydroperoxy radical in the atmosphere using laser-induced fluorescence

Lew, M.; Dusanter, Sébastien; Stevens, P. S.

doi:10.5194/amt-11-95-2018

Cited by 32 publications

(54 citation statements)

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“…Figure 7 indicates that the measured, midday values of LIF-HO 2 are generally larger than modelled HO 2 and that the diel variation in LIF-HO 2 (including large night-time values) is incompatible with the modelled HO 2 profile (red line). LIF-HO 2 measurements taken during HUMPPA-COPEC-2010 are prone to interference from organic peroxy radicals (Fuchs et al, 2011(Fuchs et al, , 2016Lew et al, 2018) and the predicted presence of large concentrations of RO * 2 at night-time has important consequences for our interpretation of the LIF-HO 2 data set. In Fig.…”

Section: Box Model Resultsmentioning

confidence: 99%

“…J values were obtained from process-specific parameterizations based on J -NO 2 and J -(O( 1 D)) measured by filter radiometers (Bohn et al, 2008). Owing to known interferences by organic peroxy radicals (Fuchs et al, 2011(Fuchs et al, , 2016Lew et al, 2018), especially in forested regions, we refer to the measurements of HO 2 as LIF-HO 2 which represent an upper limit to true HO 2 levels. Since the discovery of this interference in 2010, it was eliminated from all later LIF measurements by reducing the amount of NO added internally to the sampled air and by regularly performing titration tests in the field.…”

Section: Campaign Site and Instrumentsmentioning

confidence: 99%

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Insights into HOx and ROx chemistry in the boreal forest via measurement of peroxyacetic acid, peroxyacetic nitric anhydride (PAN) and hydrogen peroxide

et al. 2018

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Abstract. Unlike many oxidised atmospheric trace gases, which have numerous production pathways, peroxyacetic acid (PAA) and PAN are formed almost exclusively in gas-phase reactions involving the hydroperoxy radical (HO2), the acetyl peroxy radical (CH3C(O)O2) and NO2 and are not believed to be directly emitted in significant amounts by vegetation. As the self-reaction of HO2 is the main photochemical route to hydrogen peroxide (H2O2), simultaneous observation of PAA, PAN and H2O2 can provide insight into the HO2 budget. We present an analysis of observations taken during a summertime campaign in a boreal forest that, in addition to natural conditions, was temporarily impacted by two biomass-burning plumes. The observations were analysed using an expression based on a steady-state assumption using relative PAA-to-PAN mixing ratios to derive HO2 concentrations. The steady-state approach generated HO2 concentrations that were generally in reasonable agreement with measurements but sometimes overestimated those observed by factors of 2 or more. We also used a chemically simple, constrained box model to analyse the formation and reaction of radicals that define the observed mixing ratios of PAA and H2O2. After nudging the simulation towards observations by adding extra, photochemical sources of HO2 and CH3C(O)O2, the box model replicated the observations of PAA, H2O2, ROOH and OH throughout the campaign, including the biomass-burning-influenced episodes during which significantly higher levels of many oxidized trace gases were observed. A dominant fraction of CH3O2 radical generation was found to arise via reactions of the CH3C(O)O2 radical. The model indicates that organic peroxy radicals were present at night in high concentrations that sometimes exceeded those predicted for daytime, and initially divergent measured and modelled HO2 concentrations and daily concentration profiles are reconciled when organic peroxy radicals are detected (as HO2) at an efficiency of 35 %. Organic peroxy radicals are found to play an important role in the recycling of OH radicals subsequent to their loss via reactions with volatile organic compounds.

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Section: Box Model Resultsmentioning

confidence: 99%

Section: Campaign Site and Instrumentsmentioning

confidence: 99%

Insights into HOx and ROx chemistry in the boreal forest via measurement of peroxyacetic acid, peroxyacetic nitric anhydride (PAN) and hydrogen peroxide

et al. 2018

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“…It is known that the measurement of HO 2 by chemical conversion can introduce an interference from specific RO 2 radicals (Fuchs et al, 2011;Whalley et al, 2013;M. Lew et al, 2018).…”

Section: Oh Ho 2 and Ro 2 Measurementsmentioning

confidence: 99%

Wintertime photochemistry in Beijing: Observations of ROx radical concentrations in the North China Plain during the BEST-ONE campaign

Tan¹,

Rohrer²,

Lu³

et al. 2018

Preprint

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Abstract. The first wintertime in-situ measurements of hydroxyl (OH), hydroperoxy (HO 2 ) and organic peroxy (RO 2 ) 15 radicals (RO x =OH+HO 2 +RO 2 ) in combination with observations of total reactivity of OH radicals, k OH in Beijing are presented. The field campaign "Beijing winter finE particle STudy -Oxidation, Nucleation and light Extinctions" (BEST-ONE) was conducted at the suburban site Huairou near Beijing from January to March 2016. It aimed to understand oxidative capacity during wintertime and to elucidate the secondary pollutants formation mechanism in the North China Plain (NCP). OH radical concentrations at noontime ranged from 2.4×10 6 cm -3 in severely polluted 20 air (k OH ~ 27 s -1 ) to 3.6×10 6 cm -3 in relatively clean air (k OH ~ 5 s -1). These values are nearly two-fold larger than OH concentrations observed in previous winter campaign in Birmingham, Tokyo, and New York City. During this campaign, the total primary production rate of RO x radicals was dominated by the photolysis of nitrous acid accounting for 46% of the identified primary production pathways for RO x radicals. Other important radical sources were alkene ozonolysis (28%) and photolysis of oxygenated organic compounds (24%). A box model was used to 25 simulate the OH, HO 2 and RO 2 concentrations based on the observations of their long-lived precursors. The model was capable of reproducing the observed diurnal variation of the OH and peroxy radicals during clean days with a factor of 1.5. However, it largely underestimated HO 2 and RO 2 concentrations by factors up to 5 during pollution episodes. The HO 2 and RO 2 observed-to-modeled ratios increased with increasing NO concentrations, indicating a deficit in our understanding of the gas-phase chemistry in the high NO x regime. The OH concentrations observed in 30 the presence of large OH reactivities indicate that atmospheric trace gas oxidation by photochemical processes can be highly effective even during wintertime, thereby facilitating the vigorous formation of secondary pollutants.

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“…As shown for several LIF instruments, the HO 2 signal can also contain contributions from RO 2 radicals that rapidly form HO 2 in the reaction with NO (Fuchs et al, 2011;Whalley et al, 2013;Lew et al, 2018). This applies for those RO 2 radicals which form an alkoxy radical (RO) in the reaction with NO that rapidly produces HO 2 and other products.…”

Section: Instrumentationmentioning

confidence: 94%

Investigation of the oxidation of methyl vinyl ketone (MVK) by OH radicals in the atmospheric simulation chamber SAPHIR

Fuchs¹,

Albrecht²,

Acir

et al. 2018

Atmos. Chem. Phys.

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Abstract. The photooxidation of methyl vinyl ketone (MVK) was investigated in the atmospheric simulation chamber SAPHIR for conditions at which organic peroxy radicals (RO 2 ) mainly reacted with NO ("high NO" case) and for conditions at which other reaction channels could compete ("low NO" case). Measurements of trace gas concentrations were compared to calculated concentration time series applying the Master Chemical Mechanism (MCM version 3.3.1). Product yields of methylglyoxal and glycolaldehyde were determined from measurements. For the high NO case, the methylglyoxal yield was (19 ± 3) % and the glycolaldehyde yield was (65 ± 14) %, consistent with recent literature studies. For the low NO case, the methylglyoxal yield reduced to (5 ± 2) % because other RO 2 reaction channels that do not form methylglyoxal became important. Consistent with literature data, the glycolaldehyde yield of (37 ± 9) % determined in the experiment was not reduced as much as implemented in the MCM, suggesting additional reaction channels producing glycolaldehyde. At the same time, direct quantification of OH radicals in the experiments shows the need for an enhanced OH radical production at low NO conditions similar to previous studies investigating the oxidation of the parent VOC isoprene and methacrolein, the second major oxidation product of isoprene. For MVK the model-measurement discrepancy was up to a factor of 2. Product yields and OH observations were consistent with assumptions of additional RO 2 plus HO 2 reaction channels as proposed in literature for the major RO 2 species formed from the reaction of MVK with OH. However, this study shows that also HO 2 radical concentrations are underestimated by the model, suggesting that additional OH is not directly produced from RO 2 radical reactions, but indirectly via increased HO 2 . Quantum chemical calculations show that HO 2 could be produced from a fast 1,4-H shift of the second most important MVK derived RO 2 species (reaction rate constant 0.003 s −1 ). However, additional HO 2 from this reaction was not sufficiently large to bring modelled HO 2 radical concentrations into agreement with measurements due to the small yield of this RO 2 species. An additional reaction channel of the major RO 2 species with a reaction rate constant of (0.006 ± 0.004) s −1 would be required that produces concurrently HO 2 radicals and glycolaldehyde to achieve modelmeasurement agreement. A unimolecular reaction similar to the 1,5-H shift reaction that was proposed in literature for RO 2 radicals from MVK would not explain product yields for conditions of experiments in this study. A set of H-migration reactions for the main RO 2 radicals were investigated by quantum chemical and theoretical kinetic methodologies, but did not reveal a contributing route to HO 2 radicals or glycolaldehyde.

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Measurement of interferences associated with the detection of the hydroperoxy radical in the atmosphere using laser-induced fluorescence

Cited by 32 publications

References 50 publications

Insights into HO<sub><i>x</i></sub> and RO<sub><i>x</i></sub> chemistry in the boreal forest via measurement of peroxyacetic acid, peroxyacetic nitric anhydride (PAN) and hydrogen peroxide

Insights into HO<sub><i>x</i></sub> and RO<sub><i>x</i></sub> chemistry in the boreal forest via measurement of peroxyacetic acid, peroxyacetic nitric anhydride (PAN) and hydrogen peroxide

Wintertime photochemistry in Beijing: Observations of RO<sub>x</sub> radical concentrations in the North China Plain during the BEST-ONE campaign

Investigation of the oxidation of methyl vinyl ketone (MVK) by OH radicals in the atmospheric simulation chamber SAPHIR

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Measurement of interferences associated with the detection of the hydroperoxy radical in the atmosphere using laser-induced fluorescence

Cited by 32 publications

References 50 publications

Insights into HO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; and RO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; chemistry in the boreal forest via measurement of peroxyacetic acid, peroxyacetic nitric anhydride (PAN) and hydrogen peroxide

Insights into HO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; and RO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; chemistry in the boreal forest via measurement of peroxyacetic acid, peroxyacetic nitric anhydride (PAN) and hydrogen peroxide

Wintertime photochemistry in Beijing: Observations of RO&lt;sub&gt;x&lt;/sub&gt; radical concentrations in the North China Plain during the BEST-ONE campaign

Investigation of the oxidation of methyl vinyl ketone (MVK) by OH radicals in the atmospheric simulation chamber SAPHIR

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Product

Resources

About

Insights into HO<sub><i>x</i></sub> and RO<sub><i>x</i></sub> chemistry in the boreal forest via measurement of peroxyacetic acid, peroxyacetic nitric anhydride (PAN) and hydrogen peroxide

Insights into HO<sub><i>x</i></sub> and RO<sub><i>x</i></sub> chemistry in the boreal forest via measurement of peroxyacetic acid, peroxyacetic nitric anhydride (PAN) and hydrogen peroxide

Wintertime photochemistry in Beijing: Observations of RO<sub>x</sub> radical concentrations in the North China Plain during the BEST-ONE campaign