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Author: Jonathan Pfeil Franklin Publisher: ISBN: Category : Languages : en Pages : 100
Book Description
Organic aerosol is a central topic in environmental science due to its role in climate forcing and negative health effects. The transformation of organic species from primary gas phase emissions to secondary organic aerosol (SOA) is highly complex and poorly understood, proving difficult for even stateof- the-art computational models to predict. This thesis describes the in-depth characterization and redesign of a previously developed technique for the quantification of intermediate volatility organic compounds (IVOCs), which are compounds with saturation vapor pressures of 103-107 [mu]g/m3. This analytical technique, the thermal-desorption electron ionization mass spectrometer (TD-EIMS) provides a volatility separated, bulk measurement of IVOCs and will be used to investigate the primary emissions as well as production and evolution of IVOCs in a series of experiments described in this thesis. Primary emissions of IVOCs have been previously measured in vehicle exhaust and have been theorized as a significant precursor to secondary organic aerosol (SOA) in urban atmospheres. IVOCs are predominately emitted during cold start periods, but maintain a similar chemical composition across all engine states. As emissions controls have tightened, emissions of non-methane hydrocarbons and primary particulate matter have decreased, however emissions of IVOCs have only decreased significantly (as much as 80%) between the newest ULEV and SULEV emissions control tiers. Laboratory studies examining the atmospheric oxidation of common biogenic and anthropogenic SOA precursors in environmental "smog" chambers show different production and evolution profiles of IVOCs. The comparison of IVOCs measured by the TD-EIMS with other analytical techniques sampling in parallel show the TD-EIMS may detect a previously characterized fraction of carbon. Production of secondary low volatility organic compounds can also occur in low oxygen systems, such as in planetary atmospheres or in the process of soot formation. Ultraviolet light or heat can form radical hydrocarbon species, which, in low oxygen environments, will react with other hydrocarbon or radical species, undergoing oxidation by molecular growth. Particles made from ethane and ethylene are composed of very saturated compounds. The particles produced from the photolysis of acetylene are fundamentally different showing significantly larger molecule sizes and substantially higher degrees of unsaturation. The results from this thesis demonstrate measurements of the production and evolution of primary and secondary low volatility organic gases by new analytical techniques and provide a new insight to the complex chemical processes in the atmosphere leading to the production of secondary organic aerosol.
Author: Jonathan Pfeil Franklin Publisher: ISBN: Category : Languages : en Pages : 100
Book Description
Organic aerosol is a central topic in environmental science due to its role in climate forcing and negative health effects. The transformation of organic species from primary gas phase emissions to secondary organic aerosol (SOA) is highly complex and poorly understood, proving difficult for even stateof- the-art computational models to predict. This thesis describes the in-depth characterization and redesign of a previously developed technique for the quantification of intermediate volatility organic compounds (IVOCs), which are compounds with saturation vapor pressures of 103-107 [mu]g/m3. This analytical technique, the thermal-desorption electron ionization mass spectrometer (TD-EIMS) provides a volatility separated, bulk measurement of IVOCs and will be used to investigate the primary emissions as well as production and evolution of IVOCs in a series of experiments described in this thesis. Primary emissions of IVOCs have been previously measured in vehicle exhaust and have been theorized as a significant precursor to secondary organic aerosol (SOA) in urban atmospheres. IVOCs are predominately emitted during cold start periods, but maintain a similar chemical composition across all engine states. As emissions controls have tightened, emissions of non-methane hydrocarbons and primary particulate matter have decreased, however emissions of IVOCs have only decreased significantly (as much as 80%) between the newest ULEV and SULEV emissions control tiers. Laboratory studies examining the atmospheric oxidation of common biogenic and anthropogenic SOA precursors in environmental "smog" chambers show different production and evolution profiles of IVOCs. The comparison of IVOCs measured by the TD-EIMS with other analytical techniques sampling in parallel show the TD-EIMS may detect a previously characterized fraction of carbon. Production of secondary low volatility organic compounds can also occur in low oxygen systems, such as in planetary atmospheres or in the process of soot formation. Ultraviolet light or heat can form radical hydrocarbon species, which, in low oxygen environments, will react with other hydrocarbon or radical species, undergoing oxidation by molecular growth. Particles made from ethane and ethylene are composed of very saturated compounds. The particles produced from the photolysis of acetylene are fundamentally different showing significantly larger molecule sizes and substantially higher degrees of unsaturation. The results from this thesis demonstrate measurements of the production and evolution of primary and secondary low volatility organic gases by new analytical techniques and provide a new insight to the complex chemical processes in the atmosphere leading to the production of secondary organic aerosol.
Author: Ralf Koppmann Publisher: John Wiley & Sons ISBN: 0470994150 Category : Science Languages : en Pages : 512
Book Description
Every day, large quantities of volatile organic compounds (VOCs) are emitted into the atmosphere from both anthropogenic and natural sources. The formation of gaseous and particulate secondary products caused by oxidation of VOCs is one of the largest unknowns in the quantitative prediction of the earth’s climate on a regional and global scale, and on the understanding of local air quality. To be able to model and control their impact, it is essential to understand the sources of VOCs, their distribution in the atmosphere and the chemical transformations which remove these compounds from the atmosphere. In recent years techniques for the analysis of organic compounds in the atmosphere have been developed to increase the spectrum of detectable compounds and their detection limits. New methods have been introduced to increase the time resolution of those measurements and to resolve more complex mixtures of organic compounds. Volatile Organic Compounds in the Atmosphere describes the current state of knowledge of the chemistry of VOCs as well as the methods and techniques to analyse gaseous and particulate organic compounds in the atmosphere. The aim is to provide an authoritative review to address the needs of both graduate students and active researchers in the field of atmospheric chemistry research.
Author: Gabriel Avram Isaacman Publisher: ISBN: Category : Languages : en Pages : 167
Book Description
Particles in the atmosphere are known to have negative health effects and important but highly uncertain impacts on global and regional climate. A majority of this particulate matter is formed through atmospheric oxidation of naturally and anthropogenically emitted gases to yield highly oxygenated secondary organic aerosol (SOA), an amalgamation of thousands of individual chemical compounds. However, comprehensive analysis of SOA composition has been stymied by its complexity and lack of available measurement techniques. In this work, novel instrumentation, analysis methods, and conceptual frameworks are introduced for chemically characterizing atmospherically relevant mixtures and ambient aerosols, providing a fundamentally new level of detailed knowledge on their structures, chemical properties, and identification of their components. This chemical information is used to gain insights into the formation, transformation and oxidation of organic aerosols. Biogenic and anthropogenic mixtures are observed in this work to yield incredible complexity upon oxidation, producing over 100 separable compounds from a single precursor. As a first step toward unraveling this complexity, a method was developed for measuring the polarity and volatility of individual compounds in a complex mixture using two-dimensional gas chromatography, which is demonstrated in Chapter 2 for describing the oxidation of SOA formed from a biogenic compound (longifolene: C15H24). Several major products and tens of substantial minor products were produced, but none could be identified by traditional methods or have ever been isolated and studied in the laboratory. A major realization of this work was that soft ionization mass spectrometry could be used to identify the molecular mass and formula of these unidentified compounds, a major step toward a comprehensive description of complex mixtures. This was achieved by coupling gas chromatography to high resolution time-of-flight mass spectrometry with vacuum ultraviolet (VUV) photo-ionization. Chapters 3 and 4 describe this new analytical technique and its initial application to determine the structures of unknown compounds and formerly unresolvable mixtures, including a complete description of the chemical composition of two common petroleum products related to anthropogenic emissions: diesel fuel and motor oil. The distribution of hydrocarbon isomers in these mixtures - found to be mostly of branched, cyclic, and saturated - is described with unprecedented detail. Instead of measuring average bulk aerosol properties, the methods developed and applied in this work directly measure the polarity, volatility, and structure of individual components to allow a mechanistic understanding of oxidation processes. Novel characterizations of these complex mixtures are used to elucidate the role of structure and functionality in particle-phase oxidation, including in Chapter 4 the first measurements of relative reaction rates in a complex hydrocarbon particle. Molecular structure is observed to influence particle-phase oxidation in unexpected and important ways, with cyclization decreasing reaction rates by ~30% and branching increasing reaction rates by ~20-50%. The observed structural dependence is proposed to result in compositional changes in anthropogenic organic aerosol downwind of urban areas, which has been confirmed in subsequent work by applying the techniques described here. Measurement of organic aerosol components is extended to ambient environments through the development of instrumentation with the unprecedented capability to measure hourly concentrations and gas/particle partitioning of individual highly oxygenated organic compounds in the atmosphere. Chapters 5 and 6 describe development of new procedures and hardware for the calibration and analysis of oxygenates using the Semi-Volatile Thermal desorption Aerosol Gas chromatograph (SV-TAG), a custom instrument for in situ quantification of gas- and particle-phase organic compounds in the atmosphere. High time resolution measurement of oxygenated compounds is achieved through a reproducible and quantitative methodology for in situ "derivatization"--Replacing highly polar functional groups that cannot be analyzed by traditional gas chromatography with less polar groups. Implementation of a two-channel sampling system for the simultaneous collection of particle-phase and total gas-plus-particle phase samples allows for the first direct measurements of gas/particle partitioning in the atmosphere, significantly advancing the study of atmospheric composition and variability, as well as the processes governing condensation and re-volatilization. This work presents the first in situ measurements of a large suite of highly oxygenated biogenic oxidation products in both the gas- and particle-phase. Isoprene, the most ubiquitous biogenic emission, oxidizes to form 2-methyltetrols and C5 alkene triols, while [alpha]-pinene, the most common monoterpene, forms pinic, pinonic, hydroxyglutaric, and other acids. These compounds are reported in Chapter 7 with unprecedented time resolution and are shown for the first time to have a large gas-phase component, contrary to typical assumptions. Hourly comparisons of these products with anthropogenic aerosol components elucidate the interaction of human and natural emissions at two rural sites: the southeastern, U.S. and Amazonia, Brazil. Anthropogenic influence on SOA formation is proposed to occur through the increase in liquid water caused by anthropogenic sulfate. Furthermore, these unparalleled observations of gas/particle partitioning of biogenic oxidation products demonstrate that partitioning of oxygenates is unexpectedly independent of volatility: many volatile, highly oxygenated compounds have a large particle-phase component that is poorly described by traditional models. These novel conclusions are reached in part by applying the new frameworks developed in previous chapters to understand the properties of unidentified compounds, demonstrating the importance of detailed characterization of atmospheric organic mixtures. Comprehensive analysis of anthropogenic and biogenic emissions and oxidation product mixtures is coupled in this work with high time-resolution measurement of individual organic components to yield significant insights into the transformations of organic aerosols. Oxidation chemistry is observed in both laboratory and field settings to depend on molecular properties, volatility, and atmospheric composition. However, this work demonstrates that these complex processes can be understood through the quantification of individual known and unidentified compounds, combined with their classification into descriptive frameworks.
Author: Peijun Tu Publisher: ISBN: 9780355733846 Category : Languages : en Pages : 154
Book Description
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.
Author: James Freeman Hunter Publisher: ISBN: Category : Languages : en Pages : 110
Book Description
.Organic molecules have many important roles in the atmosphere, acting as climate and biogeochemical forcers, and in some cases as toxic pollutants. The lifecycle of atmospheric organic carbon is extremely complex, with reaction in multiple phases (gas, particle, aqueous) and at multiple timescales. The details of the lifecycle chemistry (especially the amount and properties of particles) have important implications for air quality, climate, and human and ecosystem health, and need to be understood better. Much of the chemical complexity and uncertainty lies in the reactions and properties of low-volatility oxidized intermediates that result from the oxidation of volatile organic precursors, and which have received comparatively little study thus far. This thesis describes three projects that link together the entire chain of oxidation (volatile to intermediate to condensed) in an effort to improve our understanding of carbon lifecycle and aerosol production. Laboratory studies of atmospherically relevant aerosol precursors show that the slow oxidation of intermediates is critical to explaining the yield and properties of aerosol under highly oxidized ("aged") conditions, and that the production of organic particles is significantly increased when intermediates are fully oxidized. This aging process is a strong function of molecular structure, and depends on aerosol concentration through the phenomenon of condensational trapping. Further laboratory studies of a series of (poly)cyclic 10 carbon alkanes show that structural effects are largely explained through fragmentation reactions, and that more generally, carbon-carbon bond scission is a ubiquitous and important reaction channel for oxidized intermediates. Finally, direct measurement of oxidized intermediate compounds in field studies shows that these compounds are abundant and important in the ambient atmosphere, with concentrations and properties in between those of volatile and particulate organic compounds. Together with other co-located measurements and complementary techniques, this enables estimates of emission, oxidation, and deposition to be constructed. The results from this thesis can be used to inform more sophisticated models of atmospheric organic carbon cycling, and to improve prediction of organic particulate matter concentrations.
Author: Wun-cheng Wang Publisher: ASTM International ISBN: 0803120486 Category : Biodegradation Languages : en Pages : 289
Book Description
Papers delivered at the symposium of the same name, April 1994, by speakers from seven nations. Twenty presentations are arranged under six topics: regulation and assessment, air quality, environmental fate, environmental measurement, environmental monitoring, and control and remediation. A sampling
Author: Andreas Herrmann Publisher: John Wiley & Sons ISBN: 1119956986 Category : Science Languages : en Pages : 408
Book Description
"Coming to a conclusion, this wonderful, informative and very interesting book presents an excellent overview of small volatile organic compounds and their role in our life and environment. Really fascinating is the entirety of scientific disciplines which were addressed by this book." –Flavour and Fragrance Journal, 2011 "... this book deserves to be a well-used reference in the library of any laboratory specialising in VOC". –Chemistry World, 2011 Volatile compounds are molecules with a relatively low molecular weight allowing for an efficient evaporation into the air. They are found in many areas of our everyday-life: they are responsible for the communication between species such as plants, insects or mammals; they serve as flavours or fragrances in many food products or perfumed consumer articles; and they play an important role in atmospheric chemistry. This book takes an interdisciplinary approach to volatile molecules. Review-style introductions to the main topics in volatile chemistry and biology are provided by international experts, building into a broad overview of this fascinating field. Topics covered include: The structural variety of volatile compounds Biogeneration of volatiles Synthesis of natural and non-natural volatiles Analysis of volatiles Volatile compounds as semiochemicals in plant-plant or plant-insect interactions Volatiles in pest control Pheromones and the influence of volatiles on mammals Olfaction and human perception Volatiles as fragrances The generation of flavours and food aroma compounds Stabilisation and controlled release of volatiles The impact of volatiles on the environment and the atmosphere
Author: Leonard Newman Publisher: ISBN: Category : Science Languages : en Pages : 434
Book Description
Developed from a symposium at the 199th National Meeting of the ACS, Boston, April 1990, this volume describes state-of-the-art techniques for collecting, separating, and analyzing aerosols and gases, and discusses current problems that must be solved for progress in the understanding of the atmosphere to continue. A reference for atmospheric scientists and researchers of gas-phase and aerosol interactions, and a tutorial for analytic chemists interested in undertaking atmospheric studies. Annotation copyright by Book News, Inc., Portland, OR
Author: John H. Seinfeld Publisher: John Wiley & Sons ISBN: 1118591364 Category : Science Languages : en Pages : 1249
Book Description
Thoroughly restructured and updated with new findings and new features The Second Edition of this internationally acclaimed text presents the latest developments in atmospheric science. It continues to be the premier text for both a rigorous and a complete treatment of the chemistry of the atmosphere, covering such pivotal topics as: * Chemistry of the stratosphere and troposphere * Formation, growth, dynamics, and properties of aerosols * Meteorology of air pollution * Transport, diffusion, and removal of species in the atmosphere * Formation and chemistry of clouds * Interaction of atmospheric chemistry and climate * Radiative and climatic effects of gases and particles * Formulation of mathematical chemical/transport models of the atmosphere All chapters develop results based on fundamental principles, enabling the reader to build a solid understanding of the science underlying atmospheric processes. Among the new material are three new chapters: Atmospheric Radiation and Photochemistry, General Circulation of the Atmosphere, and Global Cycles. In addition, the chapters Stratospheric Chemistry, Tropospheric Chemistry, and Organic Atmospheric Aerosols have been rewritten to reflect the latest findings. Readers familiar with the First Edition will discover a text with new structures and new features that greatly aid learning. Many examples are set off in the text to help readers work through the application of concepts. Advanced material has been moved to appendices. Finally, many new problems, coded by degree of difficulty, have been added. A solutions manual is available. Thoroughly updated and restructured, the Second Edition of Atmospheric Chemistry and Physics is an ideal textbook for upper-level undergraduate and graduate students, as well as a reference for researchers in environmental engineering, meteorology, chemistry, and the atmospheric sciences. Click here to Download the Solutions Manual for Academic Adopters: http://www.wiley.com/WileyCDA/Section/id-292291.html
Author: Jonathan Pfeil Franklin
Author: Jonathan Pfeil Franklin
Author: Ralf Koppmann
Author: 
Author: Gabriel Avram Isaacman
Author: Peijun Tu
Author: James Freeman Hunter
Author: Wun-cheng Wang
Author: Andreas Herrmann
Author: Leonard Newman
Author: John H. Seinfeld