Observations of organic material in individual marine particles at Cape Grim during the First Aerosol Characterization Experiment (ACE 1)

Middlebrook, A. M.; Murphy, D. M.; Thomson, D. S.

doi:10.1029/97jd03719

Cited by 335 publications

(300 citation statements)

References 54 publications

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“…We investigated processing of oleate by NO 3 using the aerosol CIMS technique to monitor oleate in the presence of NO 3 /N 2 O 5 . We did not observe a measurable decay in oleic acid signal on the timescales of our experiments for up to 100 ppb NO 3 . Thus, γ NO 3 < 10 -3 is a conservative upper limit to the reaction probability for NO 3 loss to oleate in our particles.…”

Section: Results Andcontrasting

confidence: 62%

“…Thus, atomizing a solution containing 0.001 M sodium oleate and 0.05 M Na 2 SO 4 yielded aerosols at 62% RH that were ∼3.2 wt % oleate. It is possible that the aqueous particles become slightly acidic during transport through the tubing and reactors, which have been exposed to trace levels of HNO 3 and HCl, from many experiments in addition to these reported here. But, given the available aerosol volumes and reasonable estimates of acid backgrounds from the CIMS, we feel the pH of the particles is likely greater than 5 implying that there is a mixture of oleic acid and oleate.…”

Section: Methodsmentioning

confidence: 86%

“…Atmospheric aerosols are exposed to oxidants such as the hydroxyl radical (OH), ozone (O 3 ), and the nitrate radical (NO 3 ), leading to oxidation and possible shortening of carbon chains 26,27 located at the surface. Ozone is a particularly efficient oxidant of unsaturated organics.…”

Section: Introductionmentioning

confidence: 99%

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The Oxidation of Oleate in Submicron Aqueous Salt Aerosols: Evidence of a Surface Process

2007

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We have studied the oxidation of submicron aqueous aerosols consisting of internal mixtures of sodium oleate (oleic acid proxy), sodium dodecyl sulfate, and inorganic salts by O 3 , NO 3 /N 2 O 5 , and OH. Experiments were performed using an aerosol flow tube and a continuous flow photochemical reaction chamber coupled to a chemical ionization mass spectrometer (CIMS). The CIMS was fitted with a heated inlet for volatilization and detection of organics in the particle phase simultaneously with the gas phase. A differential mobility analyzer/condensation particle counter was used for determining aerosol size distributions. The oxidation of oleate by O 3 follows Langmuir-Hinshelwood kinetics, with γ O 3 ≈ 10 -5 calculated from the observed loss rate of oleate in the particle phase. The best fit Langmuir-Hinshelwood parameters are k max I ) 0.05 ( 0.01 s -1 and K O 3 ) 4((3) × 10 -14 cm 3 molec -1 . These parameters showed no dependence on the ionic composition of the aerosols or on the presence of alkyl surfactants. Several ozone oxidation products were observed to be particle-bound at ambient temperature, including nonanoic acid. We observed efficient processing of oleate by OH (0.1 e γ OH e 1), and we suggest an upper bound of γ Ν 3 < 10 -3 . We conclude that for the aerosol compositions studied, oxidation occurs near the gas-aerosol interface and that the 1 e-fold lifetime of unsaturated organics at the aerosol surface is ∼10 min due to O 3 oxidation under atmospheric conditions. In the context of a Langmuir-Hinshelwood mechanism, different underlying aerosol compositions may extend the lifetime of oleic acid at the surface by reducing K O 3 .

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Section: Results Andcontrasting

confidence: 62%

Section: Methodsmentioning

confidence: 86%

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The Oxidation of Oleate in Submicron Aqueous Salt Aerosols: Evidence of a Surface Process

2007

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“…Condensation of organic species on existing inorganic aerosol will form an outer organic film encompassing an inner aqueous or solid core [Gill and Graedel, 1983]. Indeed, measurements show organics to be present in the same particles with sulfate [Murphy et al, 1998a;Posfai et al, 1998] and sea-salt aerosol [Middlebrook et al, 1998]. Organic compounds are also found in cloud droplets [bbcchini et al, 1999].…”

Section: Introductionmentioning

confidence: 99%

Reactive uptake of ozone by proxies for organic aerosols: Surface versus bulk processes

Moise¹,

Rudich²

2000

J. Geophys. Res.

128

215

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Abstract. Uptake measurements of ozone were conducted with two types of proxies for atmospheric organic aerosols: organic liquids and self-assembled organic monolayers. Alkanes and terminal alkenes were used. The monolayer surface was characterized, prior to and after reaction, using IR spectroscopy. Uptake experiments were conducted using a flow tube reactor coupled to a chemical ionization mass spectrometer. The reactive uptake coefficient, ¾, is shown to be due to reaction with the double bond. For the monolayers, ¾ is composed solely of a surface reactive component and is smaller by at least an order of magnitude than values obtained for a liquid of the same chain length. Uptake by the liquids is higher due to solubility and reaction in the bulk. The phase of the atmospheric organic aerosol will determine the appropriate use of a bulk or surface uptake probability in atmospheric models. Since the aerosol surface is processed and sites are consumed, ¾ is time variant. We define a parameter ¾' as the surface uptake probability per reactive site and determine its value as 9 x 10 -•9 cm: molecule '•. This enables the modeling of surface reactions as surface site concentrations diminish following interaction with the gaseous species.

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“…This chemical system is often used as a model for complex multicomponent atmospheric particles. Furthermore, surface-active organic components, such as oleic acid, are ubiquitous components of atmospheric particles, 6 at times making up 50% of the total particulate mass. 7 These organic components impact direct and indirect radiative properties of the particles, 8,9 reactively take up atmospheric trace gases (e.g., O 3 , OH., and NO x ) through heterogeneous chemical reactions, [10][11][12] and can pose severe human health hazards.…”

mentioning

confidence: 99%

Photoelectron resonance capture ionization mass spectrometry: a soft ionization source for mass spectrometry of particle‐phase organic compounds

LaFranchi

Zahardis

Petrucci

2004

Rapid Comm Mass Spectrometry

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Photoelectron resonance capture ionization (PERCI) is a soft and sensitive ionization method, based on the attachment of low-energy (<1 eV) photoelectrons to organic analyte molecules. PERCI has been developed in our laboratory for the real-time analysis of organic particles by mass spectrometry, and is employed here to monitor the heterogeneous reaction of ozone with oleic acid. Simplified identification of the reaction products is possible as a result of the soft nature of PERCI, giving predominantly the [M-H] À ions. The major particle-phase products are identified as: 1-nonanal, nonanoic acid, 9-oxononanoic acid, and azelaic acid, consistent with proposed mechanisms. New insight into this well-studied heterogeneous reaction is gained as additional minor particlephase products, consistent with the Criegee mechanism, are readily detected. Copyright # 2004 John Wiley & Sons, Ltd.We wish to report the successful development and application of a new ionization source for the on-line analysis of condensed-phase organic compounds by mass spectrometry. Photoelectron resonance capture ionization (PERCI) provides improved real-time and on-line identification capabilities for condensed-phase organics over alternate ionization methods such as conventional electron impact, resonanceenhanced multiphoton ionization (REMPI), and chemical ionization. The relatively simple mass spectra produced by PERCI make it well suited to study heterogeneous reactions on organic particles. PERCI operates on the principle of a tunable, laser-induced photoelectric effect to controllably generate low-energy electrons (<1 eV). Ionization occurs when these electrons resonantly attach, through associative and/ or dissociative mechanisms, to nearby gas-phase molecules. 1,2 PERCI provides an exceptionally soft and sensitive ionization, which generates primarily intact molecular ions. Reducing the amount of fragmentation not only simplifies component identification, but also provides an added inherent sensitivity since the analyte signal is concentrated to fewer ion peaks. When used in conjunction with mass spectrometry, PERCI should have wide ranging applications from identification and measurement of ultratrace quantities of organic pollutants to the direct study of heterogeneous reactions occurring on atmospheric particles.A relatively new class of mass spectrometers has been under development with the unique ability to analyze particles on-line and in real time. 3 Traditionally more successful for the analysis of inorganic particles, this new class of instruments has recently been applied to organic compounds; 4 however, fundamental limitations, primarily resulting from extensive molecular fragmentation, still exist for the identification of some important classes of organic particles. 5 The integration of PERCI into particle mass spectrometers is a promising method for overcoming these limitations and providing complete qualitative pictures of the organic composition of these particles.Here, for the first time, the exceptionally soft and sens...

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Observations of organic material in individual marine particles at Cape Grim during the First Aerosol Characterization Experiment (ACE 1)

Cited by 335 publications

References 54 publications

The Oxidation of Oleate in Submicron Aqueous Salt Aerosols: Evidence of a Surface Process

The Oxidation of Oleate in Submicron Aqueous Salt Aerosols: Evidence of a Surface Process

Reactive uptake of ozone by proxies for organic aerosols: Surface versus bulk processes

Photoelectron resonance capture ionization mass spectrometry: a soft ionization source for mass spectrometry of particle‐phase organic compounds

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