Chemical and Physical Studies of Secondary Organic Aerosol Formed from Beta-pinene Photooxidation PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Chemical and Physical Studies of Secondary Organic Aerosol Formed from Beta-pinene Photooxidation PDF full book. Access full book title Chemical and Physical Studies of Secondary Organic Aerosol Formed from Beta-pinene Photooxidation by Mehrnaz Sarrafzadeh. Download full books in PDF and EPUB format.
Author: Mehrnaz Sarrafzadeh
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
Atmospheric organic aerosols have a significant impact on climate and human health. However, our understanding of the physical and chemical properties of these aerosols is inadequate, thus their climate and health influences are poorly constrained. In this study, we investigated the secondary organic aerosol (SOA) formation from OH-initiated oxidation of -pinene. The majority of experiments were conducted in the York University smog chamber. The main objective was to identify the gas and particle phase products with an atmospheric pressure chemical ionization mass spectrometer (APCI-MS/MS). A wide variety of products were identified containing various functional groups including alcohol, aldehyde, carboxylic acid, ketone and nitrate. Following the chemical composition characterization of products, the shape, phase state and density of generated particles were determined. Images from a scanning electron microscope (SEM) revealed that SOA particles from -pinene were commonly spherical in shape, and adopted an amorphous semi-solid/liquid state. Additionally, the density was determined for SOA particles generated from -pinene/OH, nopinone/OH and nopinone/NO3 experiments for the first time using a tapered element oscillating microbalance-scanning mobility particle sizer (TEOM-SMPS) method. Our results showed a correlation between the determined particle density and the particle chemical composition of the respective system. This demonstrates that changes in particle density can be indicative of the changes in chemical composition of particles. We also investigated the chemical aging of oxidation products by exposing them to additional OH radicals or ozone. The observed changes in chemical composition of products and additional SOA mass production during OH-induced aging were attributed to further oxidation of gas phase intermediate products. The NOx dependence of SOA formation from -pinene photooxidation was investigated in the York University smog chamber and the Jlich Plant Atmosphere Chamber (JPAC). Consistent with previous NOx studies, SOA yields increased with increasing [NOx] at low-NOx conditions, whereas increasing [NOx] at high-NOx conditions suppressed the SOA yield. This increase was attributed to an increase of OH concentration. After removing the effect of [OH] on SOA yield in the JPAC, SOA yields only decreased with increasing [NOx]. Finally, the formation mechanisms of identified products were probed based on the information acquired throughout our study.
Author: Mehrnaz Sarrafzadeh
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
Atmospheric organic aerosols have a significant impact on climate and human health. However, our understanding of the physical and chemical properties of these aerosols is inadequate, thus their climate and health influences are poorly constrained. In this study, we investigated the secondary organic aerosol (SOA) formation from OH-initiated oxidation of -pinene. The majority of experiments were conducted in the York University smog chamber. The main objective was to identify the gas and particle phase products with an atmospheric pressure chemical ionization mass spectrometer (APCI-MS/MS). A wide variety of products were identified containing various functional groups including alcohol, aldehyde, carboxylic acid, ketone and nitrate. Following the chemical composition characterization of products, the shape, phase state and density of generated particles were determined. Images from a scanning electron microscope (SEM) revealed that SOA particles from -pinene were commonly spherical in shape, and adopted an amorphous semi-solid/liquid state. Additionally, the density was determined for SOA particles generated from -pinene/OH, nopinone/OH and nopinone/NO3 experiments for the first time using a tapered element oscillating microbalance-scanning mobility particle sizer (TEOM-SMPS) method. Our results showed a correlation between the determined particle density and the particle chemical composition of the respective system. This demonstrates that changes in particle density can be indicative of the changes in chemical composition of particles. We also investigated the chemical aging of oxidation products by exposing them to additional OH radicals or ozone. The observed changes in chemical composition of products and additional SOA mass production during OH-induced aging were attributed to further oxidation of gas phase intermediate products. The NOx dependence of SOA formation from -pinene photooxidation was investigated in the York University smog chamber and the Jlich Plant Atmosphere Chamber (JPAC). Consistent with previous NOx studies, SOA yields increased with increasing [NOx] at low-NOx conditions, whereas increasing [NOx] at high-NOx conditions suppressed the SOA yield. This increase was attributed to an increase of OH concentration. After removing the effect of [OH] on SOA yield in the JPAC, SOA yields only decreased with increasing [NOx]. Finally, the formation mechanisms of identified products were probed based on the information acquired throughout our study.
Author: Quentin Gerald James Malloy
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 414
Get Book Here
Book Description
Author: Lindsay Diana Yee
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 466
Get Book Here
Book Description
The photooxidation of volatile organic compounds (VOCs) in the atmosphere can lead to the formation of secondary organic aerosol (SOA), a major component of fine particulate matter. Improvements to air quality require insight into the many reactive intermediates that lead to SOA formation, of which only a small fraction have been measured at the molecular level. This thesis describes the chemistry of secondary organic aerosol (SOA) formation from several atmospherically relevant hydrocarbon precursors. Photooxidation experiments of methoxyphenol and phenolic compounds and C12 alkanes were conducted in the Caltech Environmental Chamber. These experiments include the first photooxidation studies of these precursors run under sufficiently low NOx levels, such that RO2 + HO2 chemistry dominates, an important chemical regime in the atmosphere. Using online Chemical Ionization Mass Spectrometery (CIMS), key gas-phase intermediates that lead to SOA formation in these systems were identified. With complementary particle-phase analyses, chemical mechanisms elucidating the SOA formation from these compounds are proposed. Three methoxyphenol species (phenol, guaiacol, and syringol) were studied to model potential photooxidation schemes of biomass burning intermediates. SOA yields (ratio of mass of SOA formed to mass of primary organic reacted) exceeding 25% are observed. Aerosol growth is rapid and linear with the organic conversion, consistent with the formation of essentially non-volatile products. Gas and aerosol-phase oxidation products from the guaiacol system show that the chemical mechanism consists of highly oxidized aromatic species in the particle phase. Syringol SOA yields are lower than that of phenol and guaiacol, likely due to unique chemistry dependent on methoxy group position. The photooxidation of several C12 alkanes of varying structure n-dodecane, 2-methylundecane, cyclododecane, and hexylcyclohexane) were run under extended OH exposure to investigate the effect of molecular structure on SOA yields and photochemical aging. Peroxyhemiacetal formation from the reactions of several multifunctional hydroperoxides and aldehyde intermediates was found to be central to organic growth in all systems, and SOA yields increased with cyclic character of the starting hydrocarbon. All of these studies provide direction for future experiments and modeling in order to lessen outstanding discrepancies between predicted and measured SOA.
Author: Emma Louise D'Ambro
Publisher:
ISBN:
Category :
Languages : en
Pages : 129
Get Book Here
Book Description
Author: Celia L. Faiola
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Atmospheric aerosol impact climate by scattering and absorbing radiation and contributing to cloud formation processes. One of the largest uncertainties in climate change predictions is due to limitations in our understanding of the formation of secondary organic aerosol (SOA). This dissertation investigated SOA formation from the oxidation of plant and leaf litter emissions in a laboratory chamber. To accurately measure the biogenic volatile organic compound (BVOC) emissions, a dynamic dilution system was developed and is described in the first study. This system was used to calibrate the GC-MS-FID and improve quantitation with a maximum instrumental error of +/-10%. In the second study, two separate sets of soil and leaf litter samples were transported from the University of Idaho experimental forest and brought back to the lab. The BVOC emissions from these samples were pumped to an aerosol growth chamber where they were oxidized to generate SOA. The resulting SOA composition was similar to SOA formed from the oxidation of other biogenic SOA precursors. Soil/leaf litter BVOC missions were compared to a canopy emission model and contributed from 12-136% of canopy emissions during spring and fall. Results suggest this could be a significiant emission source during those times of the year. In the third and fourth study, coniferous plants were treated with a plant hormone, methyl jasmonate, to simulate herbivory stress. The third study focused on the plant responses to the stress treatment by investigating changes to the BVOC emission profile. There was a high degree of inter- and intra-plant species variability. Some of the compounds most affected by the stress treatment were alpha-pinene, beta-pinene, limonene, 1,8-cineol, beta-myrcene, terpinolene, and the aromatic cymene isomers. The fourth study investigated changes to SOA composition due to changes in the BVOC emission profiles. Most pre-treatment SOA was very similar in composition with Pearson correlation coefficients between the AMS spectra greater than 0.88. The SOA generated after MeJA treatment produced aerosol mass spectra with similar m/z enhancements. This could indicate an herbivory stress mass spectral fingerprint that could be used to identify plant stress at an ecosystem scale.
Author: Shunsuke Nakao
Publisher:
ISBN:
Category : Air
Languages : en
Pages : 188
Get Book Here
Book Description
Author: Mark E. Davis
Publisher: Courier Corporation
ISBN: 0486291316
Category : Technology & Engineering
Languages : en
Pages : 385
Get Book Here
Book Description
Appropriate for a one-semester undergraduate or first-year graduate course, this text introduces the quantitative treatment of chemical reaction engineering. It covers both homogeneous and heterogeneous reacting systems and examines chemical reaction engineering as well as chemical reactor engineering. Each chapter contains numerous worked-out problems and real-world vignettes involving commercial applications, a feature widely praised by reviewers and teachers. 2003 edition.
Author: Rekha Kale
Publisher: Scitus Academics LLC
ISBN: 9781681171326
Category : Aerosols
Languages : en
Pages : 0
Get Book Here
Book Description
Atmospheric Aerosols is a vital problem in current environmental research due to its importance in atmospheric optics, energetics, radiative transfer studies, chemistry, climate, biology and public health. Aerosols can influence the energy balance of the terrestrial atmosphere, the hydrological cycle, atmospheric dynamics and monsoon circulations. Because of the heterogeneous aerosol field with large spatial and temporal variability and reduction in uncertainties in aerosol quantification is a challenging task in atmospheric sciences. Keeping this in view the present study aims to assess the impact of aerosols on coastal Indian station Visakhapatnam and the adjoining Bay of Bengal. An aerosol is a colloid of fine solid particles or liquid droplets, in air or another gas. Aerosols can be natural or not. Examples of natural aerosols are fog, forest exudates and geyser steam.
Author: Hajime Akimoto
Publisher: John Wiley & Sons
ISBN: 1119422426
Category : Science
Languages : en
Pages : 539
Get Book Here
Book Description
An important guide that highlights the multiphase chemical processes for students and professionals who want to learn more about aerosol chemistry Atmospheric Multiphase Reaction Chemistry provides the information and knowledge of multiphase chemical processes and offers a review of the fundamentals on gas-liquid equilibrium, gas phase reactions, bulk aqueous phase reactions, and gas-particle interface reactions related to formation of secondary aerosols. The authors—noted experts on the topic—also describe new particle formation, and cloud condensation nuclei activity. In addition, the text includes descriptions of field observations on secondary aerosols and PM2.5. Atmospheric aerosols play a critical role in air quality and climate change. There is growing evidence that the multiphase reactions involving heterogeneous reactions on the air-particle interface and the reactions in the bulk liquid phase of wet aerosol and cloud/fog droplets are important processes forming secondary aerosols in addition to gas-phase oxidation reactions to form low-volatile compounds. Comprehensive in scope, the book offers an understanding of the topic by providing a historical overview of secondary aerosols, the fundamentals of multiphase reactions, gas-phase reactions of volatile organic compounds, aqueous phase and air-particle interface reactions of organic compound. This important text: Provides knowledge on multiphase chemical processes for graduate students and research scientists Includes fundamentals on gas-liquid equilibrium, gas phase reactions, bulk aqueous phase reactions, and gas-particle interface reactions related to formation of secondary aerosols Covers in detail reaction chemistry of secondary organic aerosols Written for students and research scientists in atmospheric chemistry and aerosol science of environmental engineering, Atmospheric Multiphase Reaction Chemistry offers an essential guide to the fundamentals of multiphase chemical processes.
Author: Kenneth Stephen Docherty
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 626
Get Book Here
Book Description
