Characterization Of Biogenic Secondary Organic Aerosol Using Mass Spectrometry

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Characterization of Biogenic Secondary Organic Aerosol Using Mass Spectrometry

Author : Katherine J. Heaton
Publisher :
ISBN 13 : 9781124086231
Total Pages : pages
Book Rating : 4.0/5 (862 download)

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Book Synopsis Characterization of Biogenic Secondary Organic Aerosol Using Mass Spectrometry by : Katherine J. Heaton

Download or read book Characterization of Biogenic Secondary Organic Aerosol Using Mass Spectrometry written by Katherine J. Heaton and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Secondary Organic Aerosol (SOA) forms in the atmosphere from the oxidation of biogenic emissions. Even though SOA has been linked to health and climate effects, the chemical mechanism of SOA formation is not well understood. Through the use of mass spectrometry, this work characterizes SOA during the early stages of growth from the reaction of ozone with monoterpenes, a major biogenic emission. In this thesis, three types of studies are described for analyzing SOA formation: (1) the molecular composition of SOA is studied using the photoionization aerosol mass spectrometer, (2) the atomic composition is studied with the nanometer aerosol mass spectrometer and (3) high resolution mass spectrometry is used to help reconcile atomic and molecular composition data. The monoterpene ozonolysis reactions were performed in a flow tube reactor, where the reaction period could vary from 3s to 22s. The Photoionization Aerosol Mass Spectrometer (PIAMS) detected the formation of oligomers within seconds of the onset of the reaction. Ions that were detected were mapped to dimers that could form via the stabilized Criegee intermediate channel or the hydroperoxy channel. The Nanometer Aerosol Mass Spectrometer (NAMS) analyzed the elemental composition of the SOA which showed the formation of highly polar compounds during the early stages of SOA growth. NAMS also analyzed the changes in the composition of SOA when it formed in the presence of atmospheric species (water vapor, nitric acid vapor and sodium chloride seed particles). The data collected indicated that there is not as much change for endocyclic compounds as there is for exocyclic compounds. Finally, a new off-line analysis technique was created to micro-extract SOA deposited on a plate from the flow tube reactor. The samples were analyzed with the Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FTICR-MS). The FTICR-MS was used to collect molecular and elemental data simultaneously. The FTICR-MS produced accurate mass data that could be used to calculate molecular formulas. This provided a direct comparison of the data acquired with PIAMS and NAMS.

Molecular Characterization of Biogenic Secondary Organic Aerosol with Various Analytical Techniques

Author : Peijun Tu
Publisher :
ISBN 13 : 9780355733846
Total Pages : 154 pages
Book Rating : 4.7/5 (338 download)

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Book Synopsis Molecular Characterization of Biogenic Secondary Organic Aerosol with Various Analytical Techniques by : Peijun Tu

Download or read book Molecular Characterization of Biogenic Secondary Organic Aerosol with Various Analytical Techniques written by Peijun Tu and published by . This book was released on 2018 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Secondary organic aerosol (SOA), which is produced by the oxidation of volatile organic compounds (VOCs) emitted from biogenic and anthropogenic sources, has great impact on the environment and human health. In this dissertation, SOA particles derived from biogenic precursors were characterized with various mass spectrometry techniques for molecular level analysis. Differences in the chemical compositions of these particles at different formation stages were used to gain insight into the formation and fate of SOA in the atmosphere. While not pursued in this dissertation, the changes studied here may also provide significant information about SOA toxicity and harm to human health. ☐ SOA derived from ozonolysis of biogenic precursors was generated in a flow tube reactor and then sent into a photo chamber where the OH radicals could be produced to simulate further aging (fresh SOA oxidation with OH radicals to produce aged SOA). The molecular compositions of both fresh and aged SOA were studied with high resolution ESI-MS, and thousands of unique molecular formulas were characterized. Among these, a class of highly oxidized multifunctional (HOM) components, which are believed to contribute significantly to the formation of SOA, were identified and compared with previously reported Extremely Low-Volatility Organic Compounds (ELVOC) detected in the gas phase and Low Volatility Organic Oxygenated Aerosol (LV-OOA) measurements of the particle phase. HOMs in fresh SOA consisted mostly of monomers and dimers, which are consistent with condensation of ELVOCs reported from a separate study. Aging caused an increase in the average number of carbon atoms per molecule of the HOMs, which is consistent with particle phase oxidation of (less oxidized) oligomers already existing in fresh SOA. For the biogenic precursors and experimental conditions studied, HOMs in fresh biogenic SOA have molecular formulas more closely resembling LVOOA than HOMs in aged SOA, suggesting that aging of biogenic SOA is not a good surrogate for ambient LVOOA. ☐ In a separate set of experiments, SOA particles were size-selected in the 30-100 nm range with a Differential Mobility Analyzer (DMA) and analyzed by both on- and off-line mass spectrometry techniques. The chemical composition was found to change significantly with particle size. Both the average oxygen-to-carbon (O/C) ratio and carbon oxidation state (OSc) were found to decrease with increasing particle size, while the change of relative abundance of oligomers was opposite as the particle size increases. These changes allowed the relative contributions of condensation, partitioning, and particle phase oligomerization to be determined at various stages of particle formation and growth. Condensation of non-/low- volatility, highly oxidized species dominates the formation/growth of smaller SOA particles, while the partitioning of semi-volatile, less oxidized species tends to play an important role in the growth of larger SOA particles. The formation of oligomers that primarily takes place in the particle phase (accretion reactions) becomes more favored as the volume to surface area ratio of the particle increases. ☐ Additionally, due to the complex molecular components of atmospheric nanoparticles, Reverse Phase Liquid Chromatography (RPLC) and Ion-Mobility Separation (IMS)- Mass Spectrometry were employed for molecular separation. Compositions partially separated based on their size, shape and polarity were subjected to tandem mass spectrometry for structure elucidation. In some cases, isomers/ isobars were identified and separated with the help of HPLC using gradient elution method.

A Molecular Characterization of Biogenic Secondary Organic Aerosol by High-resolution Time-of-flight Mass Spectrometry

Author : Felipe Daniel Lopez-Hilfiker
Publisher :
ISBN 13 :
Total Pages : 178 pages
Book Rating : 4.:/5 (932 download)

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Book Synopsis A Molecular Characterization of Biogenic Secondary Organic Aerosol by High-resolution Time-of-flight Mass Spectrometry by : Felipe Daniel Lopez-Hilfiker

Download or read book A Molecular Characterization of Biogenic Secondary Organic Aerosol by High-resolution Time-of-flight Mass Spectrometry written by Felipe Daniel Lopez-Hilfiker and published by . This book was released on 2015 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: The guiding question to this research is: To what extent and by what mechanisms do biogenic volatile organic compounds contribute to atmospheric aerosol mass? To address this question we need to understand the chemistry that produces condensable vapors which when in the presence of particles may partition onto the aerosol surface depending on their chemical and physical properties. I developed an insitu gas and aerosol sampling system, the FIGAERO (Filter Inlet for Gases and AEROsol) to speciate gas and particle phase organics derived from photochemical reactions with biogenic volatile organic compounds under both field and laboratory conditions. By coupling the FIGAERO to a High-Resolution Time-of-Flight Chemical Ionization Mass Spectrometer (HR-TOF-CIMS) I am able to elucidate chemical pathways by identifying elemental compositions and in some cases functional groups present in the detected molecular ions. The coupling of the FIGAERO to the HR-TOF-CIMS also allows the estimation of effective vapor pressures of the aerosol components and this information can be used to improve vapor pressure models and test associated partitioning theories and parameterizations. The approach also provides hundreds of speciated chemical tracers that can be correlated with traditional environmental and chemical measurements (e.g AMS, NOx, SO2, SMPS, VOC) to help derive sources and sinks and to constrain the mechanisms responsible for the formation and growth of organic aerosol. Measurements obtained across a wide range of conditions and locations allowing connections and contrasts between different chemical systems, providing insights into generally controlling factors of secondary organic aerosol (SOA) and its properties.

Molecular Characterization and Quantification of Biogenic Secondary Organic Aerosol in Fine Particulate Matter from Confirous Forest Sites Using Liquid Chromatography/(-)electrospray Ionization Mass Spectrometry

Download Molecular Characterization and Quantification of Biogenic Secondary Organic Aerosol in Fine Particulate Matter from Confirous Forest Sites Using Liquid Chromatography/(-)electrospray Ionization Mass Spectrometry PDF Online Free

Author : Yadian Gómez González
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (91 download)

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Book Synopsis Molecular Characterization and Quantification of Biogenic Secondary Organic Aerosol in Fine Particulate Matter from Confirous Forest Sites Using Liquid Chromatography/(-)electrospray Ionization Mass Spectrometry by : Yadian Gómez González

Download or read book Molecular Characterization and Quantification of Biogenic Secondary Organic Aerosol in Fine Particulate Matter from Confirous Forest Sites Using Liquid Chromatography/(-)electrospray Ionization Mass Spectrometry written by Yadian Gómez González and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Characterization of Secondary Organic Aerosol Precursors Using Two-Dimensional Gas Chromatography with Time of Flight Mass Spectrometry (GC×GC/TOFMS)

Download Characterization of Secondary Organic Aerosol Precursors Using Two-Dimensional Gas Chromatography with Time of Flight Mass Spectrometry (GC×GC/TOFMS) PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 64 pages
Book Rating : 4.:/5 (933 download)

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Book Synopsis Characterization of Secondary Organic Aerosol Precursors Using Two-Dimensional Gas Chromatography with Time of Flight Mass Spectrometry (GC×GC/TOFMS) by :

Download or read book Characterization of Secondary Organic Aerosol Precursors Using Two-Dimensional Gas Chromatography with Time of Flight Mass Spectrometry (GC×GC/TOFMS) written by and published by . This book was released on 2013 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: The oxidation of volatile organic compounds (VOCs) plays a role in both regional and global air quality through the formation of secondary organic aerosols (SOA). More than 1000TgC/yr of non-methane VOCs are emitted from biogenic sources (significantly greater than from anthropogenic sources). Despite this magnitude and potential importance for air quality, the body of knowledge around the identities, quantities and oxidation processes of these compounds is still incomplete (e.g., Goldstein & Galbally, 2007; Robinson et al., 2009). Two-dimensional gas chromatography paired with time-of-flight mass spectrometry (GC×GC/TOFMS) is a powerful analytical technique which is explored here for its role in better characterizing biogenic VOCs (BVOCs) and thus SOA precursors.

Characterization of Oligomers in Secondary Organic Aerosol Using Advanced Mass Spectrometry Techniques

Author : Wiley A. Hall
Publisher :
ISBN 13 : 9781267214751
Total Pages : pages
Book Rating : 4.2/5 (147 download)

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Book Synopsis Characterization of Oligomers in Secondary Organic Aerosol Using Advanced Mass Spectrometry Techniques by : Wiley A. Hall

Download or read book Characterization of Oligomers in Secondary Organic Aerosol Using Advanced Mass Spectrometry Techniques written by Wiley A. Hall and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Biogenic secondary organic aerosol (SOA) forms from the reaction of gas phase organic molecules from biological sources with an atmospheric oxidant. Although biogenic SOA can comprise up to 80% of the particulate mass suspended in the atmosphere, the reactions that form SOA and the chemical identities of the compounds it contains are poorly understood, especially the oligomeric species that form the non-volatile core of SOA. In this dissertation, mass spectrometric techniques are used to characterize the oligomers found in SOA throughout their lifetime. Fresh aerosol was generated in a Tedlar bag and flow tube reactor (FTR) to determine: (1) the relevance of laboratory-generated oligomers to the atmosphere, and (2) the formation routes, and identity of the oligomers. Fresh SOA generated in the FTR was then reacted in a chamber designed to simulate photooxidation to (3) study the aging of SOA oligomers and determine if they are a source of highly oxidized atmospheric SOA. A scanning mobility particle sizer (SMPS) was found to accurately measure the concentration and size distribution of SOA. The SOA was then collected onto Teflon coated, glass fiber filters. Filter phase reactions were found to be minimal or non-existent. Various extraction solvents were tested, and acetonitrile was found to have high extraction efficiency without causing side reactions with the sample. Through the method of standard additions, the concentration of oligomeric species in the non-volatile core of the SOA collected and extracted was determined to be ~50% for laboratory SOA. SOA generated in the FTR was shown to have similar behavior as a class of organic aerosol found in the atmosphere. High resolution mass spectra revealed that oligomers undergo thermal degradation to volatile compounds when heated to high temperatures, so thermodenuders cannot be used to determine SOA volatility. High resolution tandem mass spectrometry (MSMS) was used to determine which compounds react to form oligomers and what their routes of formation are. By examining the product ions formed by dissociating oligomeric precursor ions, the monomers that are most likely to react were determined. Additionally, by searching precursor ions for the expected products of reported oligomerization reactions and examining their fragmentation spectra, several reported reactions were confirmed. These include the reactions of hydroperoxides, carbonyls and stabilized Criegee intermediates. Finally, an aerosol reaction chamber was constructed to test the theory that the oligomers found in SOA are sources of the highly oxidized class of organic aerosol found in the atmosphere after undergoing photo-oxidative aging. Freshly formed SOA was exposed to high levels of hydroxyl radical and then analyzed both online by the nanoaerosol mass (NAMS) spectrometer and off line by high resolution mass spectrometry. The average O:C and H:C ratios of the aged compounds were in the range reported for highly oxidized atmospheric SOA. Additionally, the extent of evaporation caused by the fragmentation of oligomers into smaller volatile species was not found to be significant enough to be a sink of atmospheric SOA, although the time scale of the experiment may not have been sufficient for evaporation to occur.

Chemical Characterization of Biogenic Secondary Organic Aerosol Generated from the Oxidation of Plant and Leaf Litter Emissions

Author : Celia L. Faiola
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (97 download)

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Book Synopsis Chemical Characterization of Biogenic Secondary Organic Aerosol Generated from the Oxidation of Plant and Leaf Litter Emissions by : Celia L. Faiola

Download or read book Chemical Characterization of Biogenic Secondary Organic Aerosol Generated from the Oxidation of Plant and Leaf Litter Emissions written by Celia L. Faiola and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Molecular Characterization of Atmospheric Organic Matter in Biogenic Secondary Organic Aerosol, Ambient Aerosol and Clouds

Author : Yunzhu Zhao
Publisher :
ISBN 13 :
Total Pages : 256 pages
Book Rating : 4.:/5 (94 download)

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Book Synopsis Molecular Characterization of Atmospheric Organic Matter in Biogenic Secondary Organic Aerosol, Ambient Aerosol and Clouds by : Yunzhu Zhao

Download or read book Molecular Characterization of Atmospheric Organic Matter in Biogenic Secondary Organic Aerosol, Ambient Aerosol and Clouds written by Yunzhu Zhao and published by . This book was released on 2014 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atmospheric aerosol affects the Earth's energy budget, reduces visibility and influences human health. The organic composition of aerosol is quite complex and continuously evolves through various atmospheric processes. To gain a deeper understanding of the molecular composition of atmospheric organic matter (AOM), chamber-generated biogenic secondary organic aerosol (SOA), ambient aerosol and cloud water samples were studied. Ultrahigh resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry was used to provide detailed molecular characterization of the atmospheric samples. Due to the extremely high mass resolution and mass accuracy, thousands of individual molecular formulas were identified in all of the samples studied. Multivariate statistical analysis methods were evaluated to compare the similarities and differences of the sample compositions. The biogenic SOA from three individual monoterpene precursors and a sesquiterpene precursor have clusters of peaks in their mass spectra, indicating that high molecular weight oligomers are a major component of the SOA. The monoterpene SOA have similar molecular compositions, which are different from the sesquiterpene SOA composition. The indicator species of SOA were identified using multivariate statistical analysis. Daily 24-hour water-soluble organic carbon samples from ambient aerosol collected at the Storm Peak Laboratory (SPL) show similar bulk chemical properties regarding their average elemental ratios and double bond equivalents. Using multivariate statistical analysis, the site meteorological conditions were found to affect the aerosol molecular composition. Days with strong UV radiation and high temperature were found to contain large numbers of biogenic SOA molecular formulas. Days with high relative humidity and high sulfate ion concentrations were found to contain many sulfur-containing compounds, suggesting their aqueous phase formation. The collection of cloud samples at the SPL provided an opportunity to study aqueous processing of AOM. The cloud composition was affected by biomass burning and SOA. Comparisons of the sample compositions indicate biogenic SOA components are commonly observed in ambient aerosol and cloud samples collected at the SPL. Thus, the ambient samples were used to confirm the biogenic SOA indicator species identified in chamber-generated SOA. This study of the three types of atmospheric samples helps to understand the composition of AOM with respect to atmospheric processes.

Characterization of the Molecular Composition of Secondary Organic Aerosols Using High Resolution Mass Spectrometry

Author : Rachel Elizabeth Sellon
Publisher :
ISBN 13 :
Total Pages : 274 pages
Book Rating : 4.:/5 (839 download)

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Book Synopsis Characterization of the Molecular Composition of Secondary Organic Aerosols Using High Resolution Mass Spectrometry by : Rachel Elizabeth Sellon

Download or read book Characterization of the Molecular Composition of Secondary Organic Aerosols Using High Resolution Mass Spectrometry written by Rachel Elizabeth Sellon and published by . This book was released on 2012 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atmospheric aerosols can affect visibility and the Earth's climate by scattering and absorbing light and they also can have adverse effects on human health. The organic portion of atmospheric aerosols is very complex and is a major fraction of fine particulate matter. High molecular weight (high-MW)/oligomeric organic compounds can make up a large part of this organic fraction and the composition, sources, and formation mechanisms for these compounds are not well understood. This knowledge and understanding is necessary to decrease the uncertainty in the climate affects of aerosols and to improve climate models. This dissertation investigates the composition and formation mechanisms for the high-MW/oligomeric fraction of secondary organic aerosols (SOA) collected in Bakersfield, CA and presents a comparative analysis of chamber and ambient SOA, from both Los Angeles (LA) and Bakersfield, to investigate sources at both locations. A novel sampling technique, nanospray-Desorption Electrospray Ionization (nano-DESI), was used with high resolution mass spectrometry (HR-MS) to determine the molecular formulas of the high molecular weight (HMW)/oligomeric fraction of SOA. Nano-DESI involves direct desorption from the sample surface and was used to limit reactions that can take place with extraction and storage in solvent. The samples were collected in Bakersfield and LA during CalNex 2010. Both Bakersfield and LA are out of compliance with EPA standards of ozone and particulate matter and provide opportunities to examine air masses affected by both anthropogenic and biogenic sources. This dissertation has provided the first evidence of observable changes in the composition of high-MW/oligomeric compounds throughout the day. Using positive mode nano-DESI, afternoon increases in the number of compounds that contain carbon, hydrogen and oxygen (CHO) were observed consistent with photochemistry/ozonolysis as a major source for these compounds. Compounds containing reduced nitrogen groups were dominant at night and had precursors consistent with imine formation products from the reaction of carbonyls and ammonia. In the negative mode, organonitrates (CHON) and nitroxy organosulfates (CHONS) had larger numbers of compounds in the night/morning samples consistent with nitrate radical formation reactions. A subset of the CHONS compounds and compounds containing sulfur (CHOS) had the same composition as known biogenic organosulfates and nitroxy organosulfates indicating contributions from both biogenic and anthropogenic sources to the SOA. This dissertation also provides the first analysis of the high-MW/oligomeric fraction in size resolved samples; the majority of the compounds were found in aerosol diameters between 0.18-1.0 micrometers and the CHON were bimodal with size. Finally, this dissertation presents the first comparative analysis of the overlap in the composition of this fraction of SOA between ambient and chamber samples. Samples collected in Pasadena, LA and Bakersfield were compared with samples collected in a smog chamber using diesel and isoprene sources. The results indicate that diesel had the highest overlap at both sites, Bakersfield samples were more oxidized, and LA showed evidence of a SOA plume arriving from downtown LA. The addition of ammonia to the diesel chamber experiment was necessary to form many of the 2N compounds found in Bakersfield. These results increase our understanding of the types of compounds found in urban environments and give evidence for the timescales of formation reactions in an ambient environment. They show that the majority of the high-MW oligomeric compounds are found in submicron size particles and that the composition of this fraction of SOA varies with aerosol size. Results from the chamber comparisons show that both diesel and isoprene are important sources for these compounds and also that there other sources are present. Future work that combines this type of analysis, in other ambient environments, with studies of the optical properties of aerosols could be used to help improve climate models and to start to close the gap in our understanding of the climate effects of atmospheric aerosols.

Characterization of Secondary Organic Aerosols in the Atmosphere by Using Mass Spectrometric Approaches

Author : Farhat Yasmeen
Publisher :
ISBN 13 :
Total Pages : 103 pages
Book Rating : 4.:/5 (866 download)

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Book Synopsis Characterization of Secondary Organic Aerosols in the Atmosphere by Using Mass Spectrometric Approaches by : Farhat Yasmeen

Download or read book Characterization of Secondary Organic Aerosols in the Atmosphere by Using Mass Spectrometric Approaches written by Farhat Yasmeen and published by . This book was released on 2010 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: Secondary organic aerosol (SOA) accounts for a significant fraction of ambient tropospheric aerosol. The chemical composition of SOA is highly uncertain as it depends on different ongoing chemical and physical processes of biogenic volatile organic compounds (BVOC) and anthropogenic volatile organic compounds in the atmosphere. The research performed within the frame of this doctoral thesis is focused on the characterization of SOA produced from BVOC under a variety of atmospheric reactions resorting to mass spectrometric approaches. In a first study, the aqueous-phase oligomer formation of a major atmospheric photooxidation product, i.e., methylglyoxal, has been investigated to explore an additional pathway producing SOA through cloud processes during night-time. A second study deals with the chemical characterization (sulfate and organic matter) of marine aerosols. methanesulfonic acid was the dominating organic compound in in the fine size fraction of aerosol. A third study concerns the structural characterization of a dimeric [alpha]- and [beta]-pinene SOA product. It is proposed that diaterpenylic acid is a key monomeric unit for dimers of the ester type. A fourth study deals with the chemical characterization by fragmentation of major terpenoic acids in ambient fine aerosols from a rural site. Emphasis is given to the mass spectrometric differentiation of isobaric terpenoic acids that occur in fine forest aerosol. This thesis presents results on aerosol characterization from a wide range of parent organic compounds under a variety of atmospheric conditions.

Composition and Sources of Biogenic Secondary Organic Aerosols in the Southeastern U.S. and Antarctica

Author : Jun Liu
Publisher :
ISBN 13 :
Total Pages : 201 pages
Book Rating : 4.:/5 (14 download)

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Book Synopsis Composition and Sources of Biogenic Secondary Organic Aerosols in the Southeastern U.S. and Antarctica by : Jun Liu

Download or read book Composition and Sources of Biogenic Secondary Organic Aerosols in the Southeastern U.S. and Antarctica written by Jun Liu and published by . This book was released on 2018 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biogenic Secondary Organic Aerosols (bSOA) account for a large fraction of the global aerosols budget, and thus have a significant impact on climate and public health. Observations of bSOA in the southeastern U.S. included Fourier Transform Infrared Spectroscopy (FTIR) and Aerosol Mass Spectrometer (AMS) measurements of submicron mass at Look Rock (LRK), Tennessee, and Centreville (CTR), Alabama. At LRK, Organic mass (OM) sources were apportioned to three factors, including "sulfate-related bSOA" that correlated to sulfate (r=0.72). Single-particle mass spectra also showed three composition types that corresponded to the mass-based factors with spectra cosine similarity of 0.93 and time series correlations of r>0.4. The similarity of the m/z spectra (cosine similarity=0.97) and the time series correlation (r=0.80) of the "sulfate-related bSOA" to the sulfate-containing single-particle type provide evidence for particle composition contributing to selective uptake of isoprene oxidation products onto sulfate particles. NOx had nighttime-to-early-morning peaks 3~10 times higher at CTR than at LRK, but OM sources identified by FTIR had three very similar factors at both sites including Biogenic Organic Aerosols (BOA). The BOA spectrum from FTIR is similar (cosine similarity > 0.6) to that of lab-generated particle mass from isoprene and monoterpene with NOx. NOx was correlated with FTIR-BOA and AMS related biogenic factors for NOx concentrations higher than 1 ppb at both sites, producing 0.5 to 1 [mu]g m-3 additional biogenic OM for each 1 ppb increase of NOx. Submicron organic mass (OM), particle number, and cloud condensation nuclei concentrations were measured at a costal Antarctica site and were found to be highest in summer. Natural sources that included marine sea spray and seabird emissions contributed 56% of OM in austral summer but only 3% in austral winter. Fourier transform infrared spectra showed the natural sources of organic aerosol were characterized by amide group absorption, which may be from seabird populations. Carboxylic acid group contributions from natural sources were correlated to incoming solar radiation, indicating both seasonal sources and likely secondary reactions.

Chemical and Physical Characterization of Secondary Organic Aerosol Formation from Select Agricultural Emissions

Author : Quentin Gerald James Malloy
Publisher :
ISBN 13 :
Total Pages : 414 pages
Book Rating : 4.3/5 (121 download)

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Book Synopsis Chemical and Physical Characterization of Secondary Organic Aerosol Formation from Select Agricultural Emissions by : Quentin Gerald James Malloy

Download or read book Chemical and Physical Characterization of Secondary Organic Aerosol Formation from Select Agricultural Emissions written by Quentin Gerald James Malloy and published by . This book was released on 2009 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Composition and Photochemistry of Anthropogenic and Biogenic Organic Aerosols

Author : Sandra Louise Blair
Publisher :
ISBN 13 : 9781339820262
Total Pages : 228 pages
Book Rating : 4.8/5 (22 download)

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Book Synopsis Composition and Photochemistry of Anthropogenic and Biogenic Organic Aerosols by : Sandra Louise Blair

Download or read book Composition and Photochemistry of Anthropogenic and Biogenic Organic Aerosols written by Sandra Louise Blair and published by . This book was released on 2016 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosols can substantially impact human health, atmospheric chemistry, and climate. The composition and photochemistry of a variety of anthropogenic and biogenic primary and secondary organic aerosols (POA and SOA) have yet to be fully characterized. The composition of organic aerosols is extremely complex - they contain a variety of highly oxidized, multifunctional, low vapor pressure organic compounds. The primary focus of this thesis is on the molecular characterization of organic aerosols that are not well understood or have not been studied before, such as primary emissions from electronic cigarettes, iron (III) mediated SOA, and photooxidized biodiesel and diesel fuel SOA. Another focus of this dissertation is the effect of direct photochemical aging on the composition of organic aerosol. Direct photolysis experiments were first applied to a system that is known to have a photolabile composition, alpha-pinene ozonolysis SOA, such that characterization of a photochemical effect would be possible to quantify. Photolysis of more complex SOA that have not been studied before, photooxidized biodiesel and diesel fuel SOA, were also investigated in this thesis. Advanced high resolution mass spectrometry techniques were used in the molecular characterization of organic aerosols, including nano-Desorption Electrospray Ionization Mass Spectrometry (nano-DESI) and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR). An additional suite of online instrumentation was used to measure gas-phase composition, particle-phase composition, particle size and concentration, and absorption properties: Proton Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS), Aerosol Mass Spectrometry (ToF-AMS), Scanning Mobility Particle Sizing (SMPS), and UV-vis spectroscopy. The molecular analysis of these aerosols provides valuable insight to the formation and photochemical behavior of unexpected, polymeric, light absorbing, and unique organosulfur species.

Molecular Characterization of Organic Aerosol by Mass Spectrometry

Author : Yuqian Gao
Publisher :
ISBN 13 : 9781124611839
Total Pages : pages
Book Rating : 4.6/5 (118 download)

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Book Synopsis Molecular Characterization of Organic Aerosol by Mass Spectrometry by : Yuqian Gao

Download or read book Molecular Characterization of Organic Aerosol by Mass Spectrometry written by Yuqian Gao and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic aerosol is a major constituent of atmospheric fine particles, especially over continental regions. These particles adversely affect human health and global climate. A significant fraction of organic aerosol is considered to be from the oxidation products of ozone and volatile organic compounds, which are called secondary organic aerosol (SOA). To study the formation mechanisms of secondary organic aerosol, it is important to characterize their molecular composition. The composition of secondary organic aerosol is very complex including thousands of species with molecular weight up to over a thousand Dalton. Methods utilized for the identification of these oxidation products involve advanced mass spectrometry techniques. In this dissertation, three mass spectrometry techniques were developed to study the molecular composition of organic aerosol. Firstly, online nano-aerosol sample deposition methods for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry was developed to incorporate matrix particles directly with analyte particles onto a conventional MALDI plate. Secondly, a microsampling and analysis technique was developed in order to collect microgram samples and analyze them with high performance mass spectrometry. With this technique, the molecular composition of particle phase SOA at a low mass loading can be elucidated, which provides information about SOA formation at the early stages. A species with the (neutral molecule) formula C 17 H 26 O 8 (MW 358) increased substantially in intensity relative to other products as the mass loading decreased. Tandem mass spectrometry (MS n) of this species showed it to be a dimer of C 9 H 14 O 4 and C 8 H 12 O 4, most likely pinic acid and terpenylic acid, respectively. This species is likely to be critical at the early stages of SOA formation. Thirdly, ambient secondary electrospray ionization (ESI) source was designed to characterize the molecular composition of both gas and particle phases SOA online. This ion source was demonstrated to be applicable to a wide range of mass spectrometers having an ambient inlet. This technique provides a tool to acquire detailed information about possible SOA nucleation agents. A species with the (neutral molecule) formula C 20 H 36 O 6 (MW 372) was found in the gas-phase products of SOA, which could be critical for the new particle formation of SOA. Tandem mass spectrometry (MS n) of this species showed it to be a dimer of an organic hydroperoxide C 10 H 18 O 3, which is likely formed via OH-initiated oxidation pathway.

Characterization of Products in Secondary Organic Aerosol Formation Using Mass Spectrometric Techniques

Author : Yongjie Li
Publisher :
ISBN 13 :
Total Pages : 121 pages
Book Rating : 4.:/5 (692 download)

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Book Synopsis Characterization of Products in Secondary Organic Aerosol Formation Using Mass Spectrometric Techniques by : Yongjie Li

Download or read book Characterization of Products in Secondary Organic Aerosol Formation Using Mass Spectrometric Techniques written by Yongjie Li and published by . This book was released on 2010 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Secondary Organic Aerosol Composition Studies Using Mass Spectrometry

Author : Katherine Ann Schilling
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (919 download)

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Book Synopsis Secondary Organic Aerosol Composition Studies Using Mass Spectrometry by : Katherine Ann Schilling

Download or read book Secondary Organic Aerosol Composition Studies Using Mass Spectrometry written by Katherine Ann Schilling and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Trace volatile organic compounds emitted by biogenic and anthropogenic sources into the atmosphere can undergo extensive photooxidation to form species with lower volatility. By equilibrium partitioning or reactive uptake, these compounds can nucleate into new aerosol particles or deposit onto already-existing particles to form secondary organic aerosol (SOA). SOA and other atmospheric particulate matter have measurable effects on global climate and public health, making understanding SOA formation a needed field of scientific inquiry. SOA formation can be done in a laboratory setting, using an environmental chamber; under these controlled conditions it is possible to generate SOA from a single parent compound and study the chemical composition of the gas and particle phases. By studying the SOA composition, it is possible to gain understanding of the chemical reactions that occur in the gas phase and particle phase, and identify potential heterogeneous processes that occur at the surface of SOA particles. In this thesis, mass spectrometric methods are used to identify qualitatively and qualitatively the chemical components of SOA derived from the photooxidation of important anthropogenic volatile organic compounds that are associated with gasoline and diesel fuels and industrial activity (C12 alkanes, toluene, and o-, m-, and p-cresols). The conditions under which SOA was generated in each system were varied to explore the effect of NOx and inorganic seed composition on SOA chemical composition. The structure of the parent alkane was varied to investigate the effect on the functionalization and fragmentation of the resulting oxidation products. Relative humidity was varied in the alkane system as well to measure the effect of increased particle-phase water on condensed-phase reactions. In all systems, oligomeric species, resulting potentially from particle-phase and heterogeneous processes, were identified. Imines produced by reactions between (NH4)2SO4 seed and carbonyl compounds were identified in all systems. Multigenerational photochemistry producing low- and extremely low-volatility organic compounds (LVOC and ELVOC) was reflected strongly in the particle-phase composition as well.

Molecular Composition and Chemical Transformation of Secondary Organic Aerosols from Biogenic Precursors

Author : Tran Bao Nguyen
Publisher :
ISBN 13 : 9781267427212
Total Pages : 382 pages
Book Rating : 4.4/5 (272 download)

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Book Synopsis Molecular Composition and Chemical Transformation of Secondary Organic Aerosols from Biogenic Precursors by : Tran Bao Nguyen

Download or read book Molecular Composition and Chemical Transformation of Secondary Organic Aerosols from Biogenic Precursors written by Tran Bao Nguyen and published by . This book was released on 2012 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are large gaps surrounding our understanding of secondary organic aerosols (SOA), which represent a significant fraction of fine particulate matter globally. One of the most difficult aspects of SOA to characterize is the molecular composition, because it is both complex and dynamic. However, the composition of SOA determines to a large extent the impact SOA has on climate, atmospheric chemistry, and human health. The main focus of this dissertation is the detailed composition analysis of SOA generated from important biogenic precursors and the characterization of chemistry induced by their simulated interaction with clouds, anthropogenic pollutants, and solar radiation. In particular, the gas- and aerosol-phase compounds associated with SOA from isoprene, the most abundant volatile organic compound emitted from the biosphere, are studied with the advanced technique of high-resolution mass spectrometry (HR MS). Many SOA compounds, particularly nitrogen-containing organics, are reported for the first time. Spectroscopy tools like UV-Vis, FT-IR and NMR are also used to characterize optical properties and molecular structures of SOA compounds. A secondary focus of this dissertation is to describe brown carbon formation from the ammonium- and amino acid-mediated aging of limonene SOA. Brown carbon changes the optical properties of SOA, but the sources are poorly understood. The experiments presented in this dissertation aim to elucidate the previously unknown precursors, kinetics and products of the reaction. The molecular detail gained from the HR-MS and spectroscopic analyses provides tremendous insight into the formation mechanism and further atmospheric reactions of SOA.