Formation, Ageing and Thermal Properties of Secondary Organic Aerosol [Elektronisk Resurs] PDF Download

Author:
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ISBN: 9789162886202
Category :
Languages : en
Pages : 62

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Author: Kaytlin Henry
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Category :
Languages : en
Pages : 0

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Author: Alison Mariko Fankhauser
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ISBN:
Category :
Languages : en
Pages :

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We utilize the current state of knowledge surrounding IEPOX SOA formation in an attempt to elucidate a unifying mechanism. However, model results suggest that significant gaps remain in our understanding of formation and aging processes, especially oligomerization. Finally, we consider microbial consumption of aerosol organics in the atmosphere. Observations of culturable cells in aqueous aerosols and cloud water suggest that they may be actively metabolizing aqueous media while they are airborne, which could have significant impacts on aerosol and cloud properties. Metabolic rates of cells cultured from atmospheric samples are incorporated into GAMMA. While there is a substantial decrease in the concentration of organic species for particles in which cells reside, the overall effect on populations of particles is negligible, and bacterial metabolism is not expected to measurably alter the organic content of the atmosphere.

Author: Huiming Gong
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ISBN:
Category : Aerosols
Languages : en
Pages : 162

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Author: Kenneth Stephen Docherty
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ISBN:
Category : Aerosols
Languages : en
Pages : 626

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Author: Yong Bin Lim
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ISBN:
Category : Aerosols
Languages : en
Pages : 396

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Author: Chen Song
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ISBN:
Category : Aerosols
Languages : en
Pages : 532

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Author: Chen Wang
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Category :
Languages : en
Pages :

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A sound parameterization of the gas-particle partitioning process is essential for understanding and quantifying secondary organic aerosol (SOA) formation. This thesis aimed to improve the understanding and description of phase partitioning during SOA formation through a combination of both laboratory and modeling studies. Partitioning of organic compounds between gas and particle phase is influenced by the presence of a large quantity of inorganic salts in aerosol, which is known as the salt effect. The salt effects of atmospherically relevant inorganic salts for a large number of organic compounds with various functional groups were measured in this study. The results revealed the importance of both salt species and organic compound identities on the salt effect, with the former as the dominant determinant. Models in predicting salt effect were calibrated and evaluated using the experimental data. Salt effect in mixtures was also investigated, which assists the understanding of salt effect in mixture salt solutions, including aerosols. A new approach for predicting gas-particle partitioning during SOA formation based on quantum chemical calculations was presented, which considers the partitioning species explicitly and captures the dynamic aspects of the aerosol formation processes. The role of different atmospheric parameters and chemical properties (organic loading, liquid water content, salinity, chemical ageing, etc.) was investigated and compared. Performance of the model was found to be comparable to the best currently used group contribution methods. SOA formation from constant emission and oxidation of precursor compounds was simulated to resemble the realistic scenario in the ambient atmosphere. The differential yield that describes the amount of SOA formed from a certain amount of added oxidation products was introduced, which is more relevant for SOA formation in the ambient atmosphere. The necessity of considering kinetic processes in addition to the thermodynamic equilibrium process was also discussed.

Author: Katherine Smith
Publisher:
ISBN: 9780355967500
Category :
Languages : en
Pages :

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The volatility of secondary organic aerosol (SOA) formed from the dark ozonolysis of [alpha]-pinene in a flow tube at temperatures ranging from 275 to 298 K has been characterized by thermally induced evaporation. The SOA was heated from the formation temperature (T[subscript f]) in a thermodenuder and the temperature-dependent volume loss was measured. The resulting thermograms for the SOA formed at the different temperatures were nearly identical when considered as a function of [delta]T (= T – T[subscript f]), rather than absolute temperature. A kinetic model of aerosol evaporation was used to derive T[subscript f]-specific effective volatility distributions for the SOA. The derived distributions indicate SOA formed at lower temperatures is composed of compounds having higher effective volatilities compared to that formed at higher temperatures. However, the increased abundance of compounds having higher effective volatilities at lower T[subscript f] cannot be explained solely due to increased partitioning into the particle phase due to a decrease in vapor pressures. Instead, much of the dependence on T[subscript f] likely results from T-dependent changes in the fraction of the particles that is monomers versus dimers (or higher order oligomers). The relatively short formation time (

Author: Chia-Li Chen
Publisher:
ISBN: 9781339182704
Category : Aerosols
Languages : en
Pages : 150

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This thesis enhances our understanding of secondary organic aerosol (SOA) formation from select anthropogenic sources including polycyclic aromatic hydrocarbons (PAHs), PAHs mixed with m -xylene and an atmospheric surrogate, and unburned whole gasoline vapors. Major SOA chemical characteristics and physical properties were explored along with SOA formation within the UCR CE-CERT environmental chamber.