Changes of fatty acid aerosol hygroscopicity induced by ozonolysis  under humid conditions

Vesna, O.; Sjögren, S.; Weingärtner, E.; Samburova, Vera; Kalberer, Markus; Gäggeler, H. W.; Ammann, Markus

doi:10.5194/acp-8-4683-2008

Cited by 44 publications

(62 citation statements)

References 52 publications

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“…Since the temperature in the reaction chamber was nearly constant, a similar relationship existed between κ and r, indicating that the SOA was more hygroscopic when the reaction proceeded under humid conditions. Vesna et al (2008) investigated the modification of the hygroscopic properties of fatty acids in the condensed phase following ozonolysis at different relative humidities in a flow reactor. Their results for the polyunsaturated arachidonic acid showed an increase of the growth factor when the heterogeneous reaction of condensed-phase products with ozone proceeded in the presence of water vapour, similar to our observations for SOA products formed in the gas-phase from ozonolysis of α-pinene.…”

Section: Relation Between κ and Water Vapour Concentration During Thementioning

confidence: 99%

“…This finding suggests that the oxidation level of the SOA increased as the water vapour mixing ratio increased, and may be interpreted as increase in oxygenated functional groups relative to the total number of carbon molecules in the SOA. Vesna et al (2008) used the ratio of carboxylic acid protons to aliphatic protons obtained by 1 H-NMR analysis to characterise the oxidation level of the products of ozonolysis of arachidonic acid in the condensed phase. This ratio increased with the relative humidity, up to double the initial value.…”

Section: Impact Of Water Vapour On Soa Composition At Room Temperaturmentioning

confidence: 99%

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Towards closing the gap between hygroscopic growth and CCN activation for secondary organic aerosols – Part 3: Influence of the chemical composition on the hygroscopic properties and volatile fractions of aerosols

Poulain

Petters

et al. 2010

Atmos. Chem. Phys.

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Abstract. The influence of varying levels of water mixing ratio, r, during the formation of secondary organic aerosol (SOA) from the ozonolysis of α-pinene on the SOA hygroscopicity and volatility was investigated. The reaction proceeded and aerosols were generated in a mixing chamber and the hygroscopic characteristics of the SOA were determined with the Leipzig Aerosol Cloud Interaction Simulator (LACIS) and a Cloud Condensation Nuclei counter (CCNc). In parallel, a High-Resolution Time-of-Flight Aerodyne Aerosol Mass Spectrometer (HR-ToF-AMS) located downstream of a thermodenuder (TD) sampling from the mixing chamber, to collect mass spectra of particles from the volatile and less-volatile fractions of the SOA. Results showed that both hygroscopic growth and the volatile fraction of the SOA increased with increases in r inside the mixing chamber during SOA generation. An effective density of 1.40 g cm −3 was observed for the generated SOA when the reaction proceeded with r>1 g kg −1 . Changes in the concentrations of the fragment CO + 2 and the sum of C x H y O + z (short name CHO) and C x H + y (short name CH) fragments as measured by the HR-ToF-AMS were used to estimate changes in the oxidation level of the SOA with reaction conditions, using the ratios CO + 2 to CH and CHO to CH. Under humid conditions, both ratios increased, corresponding to the presence of more oxygenated functional groups (i.e., multifunctional carboxylic acids). This result is consistent withCorrespondence to: L. Poulain (poulain@tropos.de) the α-pinene ozonolysis mechanisms which suggest that water interacts with the stabilized Criegee intermediate. The volatility and the hygroscopicity results show that SOA generation via ozonolysis of α-pinene in the presence of water vapour (r<16.9 g kg −1 ) leads to the formation of more highly oxygenated compounds that are more hygroscopic and more volatile than compounds formed under dry conditions.

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Section: Relation Between κ and Water Vapour Concentration During Thementioning

confidence: 99%

Section: Impact Of Water Vapour On Soa Composition At Room Temperaturmentioning

confidence: 99%

Towards closing the gap between hygroscopic growth and CCN activation for secondary organic aerosols – Part 3: Influence of the chemical composition on the hygroscopic properties and volatile fractions of aerosols

Poulain

Petters

et al. 2010

Atmos. Chem. Phys.

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“…Laboratory proxies of organic biogenic aerosols have been found to be reasonably hygroscopic (e.g. Vesna et al, 2008;Wex et al, 2009) and CCN active in laboratory studies (e.g. Duplissy et al, 2008;Hartz et al, 2005;Jurányi et al, 2009;Prenni et al, 2007;VanReken et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Slower CCN growth kinetics of anthropogenic aerosol compared to biogenic aerosol observed at a rural site

et al. 2010

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Abstract. Growth rates of water droplets were measured with a static diffusion cloud condensation chamber in MayJune 2007 at a rural field site in Southern Ontario, Canada, 70 km north of Toronto. The observations include periods when the winds were from the south and the site was impacted by anthropogenic air from the U.S. and Southern Ontario as well as during a 5-day period of northerly wind flow when the aerosol was dominated by biogenic sources. The growth of droplets on anthropogenic size-selected particles centred at 0.1 µm diameter and composed of approximately 40% organic and 60% ammonium sulphate (AS) by mass, was delayed by on the order of 1 s compared to a pure AS aerosol. Simulations of the growth rate on monodisperse particles indicate that a lowering of the water mass accommodation coefficient from α c =1 to an average of α c =0.04 is needed (assuming an insoluble organic with hygroscopicity parameter, κ org , of zero). Simulations of the initial growth rate on polydisperse anthropogenic particles agree best with observations for α c =0.07. In contrast, the growth rate of droplets on size-selected aerosol of biogenic character, consisting of >80% organic, was similar to that of pure AS. Simulations of the predominantly biogenic polydisperse aerosol show agreement between the observations and simulations when κ org =0.2 (with upper and lower limits of 0.5 and 0.07, respectively) and α c =1. Inhibition of water uptake by the anthropogenic organic applied to an adiabatic cloud parcel model in the form of a constant low α c increases the number of droplets in a cloud compared to pure AS. If the α c is assumed to increase with increasing liquid water on the droplets, then the number of droplets decreases which could diminish the Correspondence to: N. C. Shantz (nicole.shantz@ec.gc.ca) indirect climate forcing effect. The slightly lower κ org in the biogenic case decreases the number of droplets in a cloud compared to pure AS.

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“…1,2 Aerosols undergo physical and chemical ageing in the atmosphere, which can change their properties such as absorptivity, 3 hygroscopicity 4 and toxicity. 5,6 OM in aerosols has often been assumed to be well mixed, with respect to both gas-particle partitioning 7,8 and reactions in the condensed phase (subsequently termed ''bulk'', in contrast to the particle's surface region).…”

Section: Introductionmentioning

confidence: 99%

Shikimic acid ozonolysis kinetics of the transition from liquid aqueous solution to highly viscous glass

Steimer

Berkemeier

Gilgen

et al. 2015

Phys. Chem. Chem. Phys.

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Ageing of particulate organic matter affects the composition and properties of atmospheric aerosol particles. Driven by temperature and humidity, the organic fraction can vary its physical state between liquid and amorphous solid, or rarely even crystalline. These transitions can influence the reaction kinetics due to limitations of mass transport in such (semi-) solid states, which in turn may influence the chemical ageing of particles containing such compounds. We have used coated wall flow tube experiments to investigate the reaction kinetics of the ozonolysis of shikimic acid, which serves as a proxy for oxygenated, water-soluble organic matter and can form a glass at room temperature. Particular attention was paid to how the presence of water influences the reaction, since it acts a plasticiser and thereby induces changes in the physical state. We analysed the results by means of a traditional resistor model, which assumes steady-state conditions. The ozonolysis rate of shikimic acid is strongly increased in the presence of water, a fact we attribute to the increased transport of O-3 and shikimic acid through the condensed phase at lower viscosities. The analysis using the resistor model suggests that the system undergoes both surface and bulk reaction. The second-order rate coefficient of the bulk reaction is 3.7 (+1.5/-3.2) x 10(3) L mol(-1) s(-1). At low humidity and long timescales, the resistor model fails to describe the measurements appropriately. The persistent O-3 uptake at very low humidity suggests contribution of a self-reaction of O-3 on the surface

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Changes of fatty acid aerosol hygroscopicity induced by ozonolysis under humid conditions

Cited by 44 publications

References 52 publications

Towards closing the gap between hygroscopic growth and CCN activation for secondary organic aerosols – Part 3: Influence of the chemical composition on the hygroscopic properties and volatile fractions of aerosols

Towards closing the gap between hygroscopic growth and CCN activation for secondary organic aerosols – Part 3: Influence of the chemical composition on the hygroscopic properties and volatile fractions of aerosols

Slower CCN growth kinetics of anthropogenic aerosol compared to biogenic aerosol observed at a rural site

Shikimic acid ozonolysis kinetics of the transition from liquid aqueous solution to highly viscous glass

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