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Understanding Organic Aerosol Formation Processes In Atmosphere Using Molecular Markers
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Book Synopsis Understanding Organic Aerosol Formation Processes in Atmosphere Using Molecular Markers by : Grazia Maria Lanzafame
Download or read book Understanding Organic Aerosol Formation Processes in Atmosphere Using Molecular Markers written by Grazia Maria Lanzafame and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic aerosols (OA) account for a large fraction of ambient air particulate matter and have strong impacts on air quality and climate. As their sources and atmospheric formation processes, notably for secondary OA (SOA), are still not fully understood, their concentrations are often underestimated by air quality models. This work aimed at improving OA modelling by implementing specific organic molecular marker emissions and formation processes into the chemistry-transport model CHIMERE. It was based on the comparison of model outputs with measurements from field studies performed in the Paris region (suburban site of SIRTA, 25 km SW of Paris) over 2015 and 10 French urban locations in winter 2014-2015. 25 biogenic and anthropogenic SOA markers have been quantified in both, particulate and gas phases and the formation pathways of 10 have been developed and simulated using CHIMERE. The evolution of levoglucosan concentrations (biomass burning marker) has been also modeled. The results obtained showed that sources and precursor emissions (missing or underestimated), radical concentrations (NO, HO2 and RO2) and the lack of formation pathways, are key parameters for the simulation of SOA markers. Gas/particle partitioning seemed poorly linked to the T°C while the inclusion of hydrophilic non-ideal partitioning, usually neglected, seemed essential. Levoglucosan was well simulated, even if some underestimations existed in some regions. A significant theoretical gaseous fraction was also highlighted. The model/measurements comparison of molecular markers is a powerful tool to evaluate precursor emissions, physicochemical processes and in the end, to estimate OA sources.
Book Synopsis Atmospheric Multiphase Chemistry by : Hajime Akimoto
Download or read book Atmospheric Multiphase Chemistry written by Hajime Akimoto and published by John Wiley & Sons. This book was released on 2020-06-02 with total page 539 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Environmental Chemistry of Aerosols by : Ian Colbeck
Download or read book Environmental Chemistry of Aerosols written by Ian Colbeck and published by John Wiley & Sons. This book was released on 2008-03-24 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosol particles are ubiquitous in the Earth’s atmosphere and are central to many environmental issues such as climate change, stratospheric ozone depletion and air quality. In urban environments, aerosol particles can affect human health through their inhalation. Atmospheric aerosols originate from naturally occurring processes, such as volcanic emissions, sea spray and mineral dust emissions, or from anthropogenic activity such as industry and combustion processes. Aerosols present pathways for reactions, transport, and deposition that would not occur in the gas phase alone. Understanding the ways in which aerosols behave, evolve, and exert these effects requires knowledge of their formation and removal mechanism, transport processes, as well as their physical and chemical characteristics. Motivated by climate change and adverse health effects of traffic-related air pollution, aerosol research has intensified over the past couple of decades, and recent scientific advances offer an improved understanding of the mechanisms and factors controlling the chemistry of atmospheric aerosols. Environmental Chemistry of Aerosols brings together the current state of knowledge of aerosol chemistry, with chapters written by international leaders in the field. It will serve as an authoritative and practical reference for scientists studying the Earth’s atmosphere and as an educational and training resource for both postgraduate students and professional atmospheric scientists.
Book Synopsis Improving Aerosol Simulations by : Jaemeen Baek
Download or read book Improving Aerosol Simulations written by Jaemeen Baek and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Both long-term and short-term exposure to fine particulate matter (PM2.5) has been shown to increase the rate of respiratory and cardiovascular illness, premature death, and hospital admissions from respiratory causes. It is important to understand what contributes to ambient PM2.5 level to establish effective regulation, and air quality model can provide guidance based on the best scientific understanding available. However, PM2.5 simulations in air quality models have often found performance less than desirable, particularly for organic carbon levels. Here, some of major shortcomings of current air quality model will be addressed and improved by using CMAQ, receptor models, and regression analysis. Detailed source apportionment of PM2.5 performed using the CMAQ-tracer method suggests that wood combustion and mobile sources are the largest sources of PM2.5, followed by meat cooking and industrial processes. Biases in emission estimates are investigated using tracer species, such as organic molecular markers and trace metals that are used in receptor models. Comparison of simulated and observed tracer species shows some consistent discrepancies, which enables us to quantify biases in emissions and improve CMAQ simulations. Secondary organic aerosol (SOA) is another topic that is investigated. CMAQ studies on organic aerosol usually underestimate organic carbon with larger than a 50% bias. Formation of aged aerosol from multigenerational semi-volatile organic carbon is added to CMAQ, significantly improving performance of organic aerosol simulations.
Book Synopsis Atmospheric Aerosol Properties by : Kirill Ya. Kondratyev
Download or read book Atmospheric Aerosol Properties written by Kirill Ya. Kondratyev and published by Springer Science & Business Media. This book was released on 2006-08-29 with total page 595 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides the first comprehensive analysis of how aerosols form in the atmosphere through in situ processes as well as via transport from the surface (dust storms, seas spray, biogenic emissions, forest fires etc.). Such an analysis has been followed by the consideration of both observation data (various field observational experiments) and numerical modeling results to assess climate impacts of aerosols bearing in mind that these impacts are the most significant uncertainty in studying natural and anthropogenic causes of climate change.
Book Synopsis Molecular Composition, Volatility, and Formation Mechanisms of Biogenic Secondary Organic Aerosol by : Emma Louise D'Ambro
Download or read book Molecular Composition, Volatility, and Formation Mechanisms of Biogenic Secondary Organic Aerosol written by Emma Louise D'Ambro and published by . This book was released on 2018 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Insights Into Predicting Secondary Organic Aerosol Formation from Anthropogenic Volatile Organic Compounds by : Lijie Li
Download or read book Insights Into Predicting Secondary Organic Aerosol Formation from Anthropogenic Volatile Organic Compounds written by Lijie Li and published by . This book was released on 2016 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding secondary organic aerosol (SOA) formation is of critical importance to public health and global climate. SOA formation from anthropogenic volatile organic compounds (VOCs) is influenced by NO, precursor molecular structure, oxidation conditions and other factors. This dissertation explores the impact of NO effect and molecular structure for two categories of VOCs at urban atmosphere relevant conditions by utilizing the state of art 90 m3 UCR/CE-CERT chamber facilities.
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.
Book Synopsis A Computational Approach to Understanding Aerosol Formation and Oxidant Chemistry in the Troposphere by :
Download or read book A Computational Approach to Understanding Aerosol Formation and Oxidant Chemistry in the Troposphere written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An understanding of the mechanisms and kinetics of aerosol formation and ozone production in the troposphere is currently a high priority because these phenomena are recognized as two major effects of energy-related air pollution. Atmospheric aerosols are of concern because of their effect on visibility, climate, and human health. Equally important, aerosols can change the chemistry of the atmosphere, in dramatic fashion, by providing new chemical pathways (in the condensed phase) unavailable in the gas phase. The oxidation of volatile organic compounds (VOCs) and inorganic compounds (e.g., sulfuric acid, ammonia, nitric acid, ions, and mineral) can produce precursor molecules that act as nucleation seeds. The U.S. Department of Energy (DOE) Atmospheric Chemistry Program (ACP) has identified the need to evaluate the causes of variations in tropospheric aerosol chemical composition and concentrations, including determining the sources of aerosol particles and the fraction of such that are of primary and secondary origin. In particular, the ACP has called for a deeper understanding into aerosol formation because nucleation creates substantial concentrations of fresh particles that, via growth and coagulation, influence the Earth's radiation budget. Tropospheric ozone is also of concern primarily because of its impact on human health. Ozone levels are controlled by NOx and by VOCs in the lower troposphere. The VOCs can be either from natural emissions from such sources as vegetation and phytoplankton or from anthropogenic sources such as automobiles and oil-fueled power production plants. The major oxidant for VOCs in the atmosphere is the OH radical. With the increase in VOC emissions, there is rising concern regarding the available abundance of HOx species needed to initiate oxidation. Over the last five years, there have been four field studies aimed at initial measurements of HOx species (OH and HO? radicals). These measurements revealed HOx levels that are two to four times higher than expected from the commonly assumed primary sources. Such elevated abundances of HOx imply a more photochemically active troposphere than previously thought. This implies that rates of ozone formation in the lower region of the atmosphere and the oxidation of SO? can be enhanced, thus promoting the formation of new aerosol properties. Central to unraveling this chemistry is the ability to assess the photochemical product distributions resulting from the photodissociation of by-products of VOC oxidation. We propose to use state-of-the-art theoretical techniques to develop a detailed understanding of the mechanisms of aerosol formation in multicomponent (mixed chemical) systems and the photochemistry of atmospheric organic species. The aerosol studies involve an approach that determines homogeneous gas-particle nucleation rates from knowledge of the molecular interactions that are used to define properties of molecular clusters. Over the past several years we developed Dynamical Nucleation Theory (DNT), a novel advance in the theoretical description of homogeneous gas-liquid nucleation, and applied it to gas-liquid nucleation of a single component system (e.g., water). The goal of the present research is to build upon these advances by extending the theory to multicomponent systems important in the atmosphere (such as clusters containing sulfuric acid, water, ions, ammonia, and organics). In addition, high-level ab initio electronic structure calculations will be used to unravel the chemical reactivity of the OH radical and water clusters.
Book Synopsis Atmospheric Aerosol Properties by : Kirill Ya. Kondratyev
Download or read book Atmospheric Aerosol Properties written by Kirill Ya. Kondratyev and published by Springer. This book was released on 2005-11-10 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides the first comprehensive analysis of how aerosols form in the atmosphere through in situ processes as well as via transport from the surface (dust storms, seas spray, biogenic emissions, forest fires etc.). Such an analysis has been followed by the consideration of both observation data (various field observational experiments) and numerical modeling results to assess climate impacts of aerosols bearing in mind that these impacts are the most significant uncertainty in studying natural and anthropogenic causes of climate change.
Book Synopsis Enabling the Identification, Quantification, and Characterization of Organics in Complex Mixtures to Understand Atmospheric Aerosols by : Gabriel Avram Isaacman
Download or read book Enabling the Identification, Quantification, and Characterization of Organics in Complex Mixtures to Understand Atmospheric Aerosols written by Gabriel Avram Isaacman and published by . This book was released on 2014 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Formation and Chemical Evolution of Secondary Organic Aerosol from Aqueous-phase Reactions of Atmospheric Phenols by : Lu Yu
Download or read book Formation and Chemical Evolution of Secondary Organic Aerosol from Aqueous-phase Reactions of Atmospheric Phenols written by Lu Yu and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Secondary organic aerosol (SOA) is formed and transformed in atmospheric aqueous phases (e.g., cloud and fog droplets and deliquesced airborne particles containing small amounts of water) through a multitude of chemical and physical processes. Understanding the formation and transformation processes of SOA via aqueous-phase reactions is important for properly presenting its atmospheric evolution pathways in models and for elucidating its climate and health effects. Phenolic compounds, which are emitted in significant amounts from biomass burning, can undergo fast reactions in atmospheric aqueous phases to form secondary organic aerosol (aqSOA). In this study, we investigate the formation and evolution of phenol (C6H6O), guaiacol (C7H8O2; 2-methoxyphenol) and syringol (C8H10O3; 2,6-dimethoxyphenol) and with two major aqueous phase oxidants -- the triplet excited state of an aromatic carbonyl (3C*) and hydroxyl radical (·OH) - and interpret the reaction mechanisms. In addition, given that dissolved organic matter (DOM) is an important component of fog and cloud water and that it can undergo aqueous reactions to form more oxidized, less volatile species, we further investigate the photochemical processing of DOM in fog water to gain insights into the aqueous-phase processing of organic aerosol (OA) in the atmosphere. In Chapter 2, we thoroughly characterize the bulk chemical and molecular compositions of phenolic aqSOA formed at half-life (t[subscript 1/2]), and interpret the formation mechanisms. We find that phenolic aqSOA formed at t[subscript 1/2] is highly oxygenated with atomic oxygen-to-carbon ratio (O/C) in the range of 0.85-1.23. Dimers, higher oligomers (up to hexamers), functionalized monomers and oligomers with carbonyl, carboxyl, and hydroxyl groups, and small organic acids are detected. Compared with ·OH-mediated reactions, reactions mediated by 3C* are faster and produce more oligomers and hydroxylated species at t[subscript1/2]. We also find that aqSOA shows enhanced light absorption in the UV-vis region, suggesting that aqueous-phase reactions of phenols are an important source of secondary brown carbon in the atmosphere, especially in regions impacted by biomass burning. In Chapter 3, we investigate the chemical evolution of phenolic aqSOA via aqueous-phase reactions on the molecular level and interpret the aging mechanisms. Our results indicate that oligomerization is an important aqueous reaction pathway for phenols, especially during the initial stage of photooxidation. Functionalization and fragmentation become dominant at later stages, forming a variety of functionalized aromatic and ring-opening products with higher carbon oxidation states. Fragmentation reactions eventually dominate the photochemical evolution of phenolic aqSOA, forming a large number of highly oxygenated ring-opening molecules. In addition, phenolic aqSOA has a wide range of saturation vapor pressures (C*), varying from 10−20 [mu]g m−3 for functionalized phenolic oligomers to 10 [mu]g m−3 for ring-opening species with number of carbon less than 6. The detection of abundant extremely low volatile organic compounds (ELVOC) indicates that aqueous reactions of phenolic compounds are likely an important source of ELVOC in the atmosphere. Chapter 3 investigates the molecular transformation with aging based on the characterization of three aqSOA filter samples collected at the defined time intervals of the photoreaction. However, the chemical evolution of aqSOA products with hours of illumination at a higher time resolution is largely unknown. In Chapter 4, we investigate the chemical evolution of aqSOA at a 1-min time resolution based on high-resolution aerosol mass spectrometer (AMS) analysis. This is important for understanding the continuous evolution of phenolic aqSOA with aging as well as for elucidating the formation and transformation of different generations of products. Our results suggest that dimer and higher-order oligomers (trimers, tetramers, etc.) are formed continuously during the first 1-2 hours of photoreaction but show a gradual decrease afterwards. Functionalized derivatives grow at a later time and then gradually decrease. Highly oxidized ring-opening species continuously increase over the course of reactions. Positive matrix factorization (PMF) analysis of the AMS spectra of phenolic aqSOA identifies multiple factors, representing different generations of products. The 1st-generation products include dimers, higher-order oligomers and their oxygenated derivatives. The 2nd-generation products include oxygenated monomeric derivatives. The 3rd-generation products include highly oxidized ring-opening species. In Chapter 5, we investigate the evolution of dissolved organic matter (DOM) in fog water. Our results show that the mass concentration of DOM[subscript OA] (i.e., low-volatility DOM in fog water) is enhanced over the course of illumination, with continuous increase of O/C and atomic nitrogen-to-carbon ratio (N/C). The increase of DOM[subscript OA] is due to the incorporation of oxygen- and nitrogen-containing functional groups into the molecules. The aqueous aging of DOM[subscript OA] can be modeled as a linear combination of the dynamic variations of 3 factors using PMF analysis. Factor 1 is chemically similar to the DOM[subscript OA] before illumination, which is quickly reacted away. Factor 2 is representative of an intermediate component, which is first formed and then transformed, and O/C of Factor 2 is intermediate between that of Factor 1 and Factor 3. Factor 3 represents highly oxidized final products, which is continuously formed during illumination. Fog DOM absorbs significantly in the tropospheric sunlight wavelengths, but this absorption behavior stays almost constant over the course of illumination, despite the significant change in chemical composition.
Book Synopsis Aerosols in Atmospheric Chemistry by : Yue Zhang
Download or read book Aerosols in Atmospheric Chemistry written by Yue Zhang and published by American Chemical Society. This book was released on 2022-04-01 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: The uncertainties in the aerosol effects on radiative forcing limit our knowledge of climate change, presenting us with an important research challenge. Aerosols in Atmospheric Chemistry introduces basic concepts about the characterization, formation, and impacts of ambient aerosol particles as an introduction to graduate students new to the field. Each chapter also provides an up-to-date synopsis of the latest knowledge of aerosol particles in atmospheric chemistry.
Book Synopsis Atmospheric Aerosols by : Hayder Abdul-Razzak
Download or read book Atmospheric Aerosols written by Hayder Abdul-Razzak and published by BoD – Books on Demand. This book was released on 2012-09-12 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book is divided into two sections. The first section presents characterization of atmospheric aerosols and their impact on regional climate from East Asia to the Pacific. Ground-based, air-born, and satellite data were collected and analyzed. Detailed information about measurement techniques and atmospheric conditions were provided as well. In the second section, authors provide detailed information about the organic and inorganic constituents of atmospheric aerosols. They discuss the chemical and physical processes, temporal and spatial distribution, emissions, formation, and transportation of aerosol particles. In addition, new measurement techniques are introduced. This book hopes to serve as a useful resource to resolve some of the issues associated with the complex nature of the interaction between atmospheric aerosols and climatology.
Download or read book Aerosols written by George Hidy and published by Elsevier. This book was released on 2012-12-02 with total page 795 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosols: An Industrial and Environmental Science is a comprehensive account of the science and technology of aerosols as well as their aerodynamic and physico-chemical properties. Measurement techniques and results are presented in terms of a framework of classical mechanics and macroscopic chemistry. This book is comprised of 10 chapters and begins with a discussion on the foundations of modern aerosol science and technology, followed by a review of the dynamic theory of aerosols as rigid spheres. The production of particle suspensions, the methods of particle sampling and measurement, and physical or chemical characterization are then considered, along with particle diffusion by Brownian motion, particle formation and growth, and coagulation processes. The formation of particle clouds is described by means of molecular agglomeration (condensation) processes, breakup and disintegration, and chemical reactions. The remaining chapters focus on several major applications of aerosol science in areas such as combustion, agriculture, and medicine. This monograph is intended to serve scientists and engineers who are concerned with the underlying principles of aerodynamic and physical chemical behavior of aerosols, and could also be used as a text for graduate students in specialized courses on aerosol or colloid chemistry, atmospheric processes, and chemical, mechanical, or environmental engineering.
Book Synopsis Molecular Marker Analysis as a Guide to the Sources of Fine Organic Aerosols by :
Download or read book Molecular Marker Analysis as a Guide to the Sources of Fine Organic Aerosols written by and published by . This book was released on 1992 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The molecular composition of fine particulate (D{sub p} ≥ 2 [mu]m) organic aerosol emissions from the most important sources in the Los Angeles area has been determined. Likewise, ambient concentration patterns for more than 80 single organic compounds have been measured at four urban sites (West Los Angeles, Downtown Los Angeles, Pasadena, and Rubidoux) and at one remote offshore site (San Nicolas Island). It has been found that cholesterol serves as a marker compound for emissions from charbroilers and other meat cooking operations. Vehicular exhaust being emitted from diesel and gasoline powered engines can be traced in the Los Angeles atmosphere using fossil petroleum marker compounds such as steranes and pentacyclic triterpanes (e.g., hopanes). Biogenic fine particle emission sources such as plant fragments abraded from leaf surfaces by wind and weather can be traced in the urban atmosphere. Using distinct and specific source organic tracers or assemblages of organic compounds characteristic for the sources considered it is possible to estimate the influence of different source types at any urban site where atmospheric data are available.
Book Synopsis Laboratory Studies of the Multiday Oxidative Aging of Atmospheric Organic Aerosol by : Christopher Yung-Ta Lim
Download or read book Laboratory Studies of the Multiday Oxidative Aging of Atmospheric Organic Aerosol written by Christopher Yung-Ta Lim and published by . This book was released on 2019 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fine particulate matter (PM, or "aerosol") in the atmosphere affects the Earth's radiative balance and is one of the most important risk factors leading to premature mortality worldwide. Thus, understanding the processes that control the loading and chemical composition of PM in the atmosphere is key to understanding air quality and climate. However, the chemistry of organic aerosol (OA), which comprises a significant fraction of submicron atmospheric PM, is immensely complex due to the vast number of organic compounds in the atmosphere and their numerous reaction pathways. Laboratory experiments have generally focused on the initial formation of OA from volatile organic compounds (VOCs), but have neglected processes that can change the composition and loading of OA over longer timescales ("aging"). This thesis describes several laboratory studies that better constrain the effect of two important aging processes over timescales of several days, the oxidation of gas phase species to form secondary OA (condensation) and the reaction of gas phase radicals with organic molecules in the particle phase (heterogeneous oxidation). First, the oxidation of biomass burning emissions is studied by exposing particles and gases present in smoke to hydroxyl radicals (OH). Increases in organic aerosol mass are observed for all fuels burned, and the amount of OA formed is explained well by the extent of aging and the total concentration of measured organic gases. Second, the effect of particle morphology on the rate of heterogeneous oxidation is examined by comparing the oxidation of particles with thin organic coatings to the oxidation of pure organic particles. Results show that morphology can have a strong impact on oxidation kinetics and that particles with high organic surface area to volume ratios can be rapidly oxidized. Third, the molecular products from the heterogeneous OH oxidation of a single model compound (squalane) are measured. Formation of a range of gas-phase oxygenated VOCs is observed, indicating the importance of fragmentation reactions that decrease OA mass, and providing insight into heterogeneous reaction mechanisms. The results from this work emphasize that the concentration and composition of OA can change dramatically over multiple days of atmospheric oxidation.
