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Composition And Photochemistry Of Anthropogenic And Biogenic Organic Aerosols
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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.
Book Synopsis Optical Properties, Chemical Composition, and Aqueous Photochemistry of Secondary Organic Aerosol by : Dian Elizabeth Romonosky
Download or read book Optical Properties, Chemical Composition, and Aqueous Photochemistry of Secondary Organic Aerosol written by Dian Elizabeth Romonosky and published by . This book was released on 2016 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt: A large fraction of organic aerosol particles are formed as secondary organic aerosol (SOA) resulting from the condensation of partially oxidized biogenic and anthropogenic volatile organic compounds (VOCs) with gas phase oxidants such as O3, OH, NOx, and NO3. An additional pathway for SOA formation is by the photochemical aqueous processing of VOC occurring inside cloud and fog droplets, followed by droplet evaporation. Once formed, SOA can age through heterogeneous oxidation and fog photochemical processes involving the hydroxyl radical (OH) as well as various other oxidants in the atmosphere. In addition to condensed phase oxidation, SOA can also age in the atmosphere upon exposure to radiation, for many of these organic compounds are photolabile and can degrade through direct photolysis, wherein the compounds absorb radiation and break into products, and indirect photolysis, wherein absorption of solar radiation initiates chemistry through the production of non-selective oxidants such as OH. These photochemical aging processes have the potential to be on time scales that are comparable to the typical lifetimes of droplets (hours) and particles (days), making them relevant to study further for both climate and health reasons. This dissertation presents a systematic investigation of the optical properties, molecular composition, and the extent of photochemical processing in different types of SOA from various biogenic and anthropogenic VOC precursors. Chamber- or flowtube-generated SOA is made and then analyzed using high-resolution mass spectrometry (HR-MS) to observe the extent of change in the molecular level composition of the material before and after aqueous photolysis. Significant differences in the molecular composition between biogenic and anthropogenic SOA were observed, while the composition further evolved during photolysis. To study the optical properties and lifetimes of organic aerosol, spectroscopy tools such as UV-Vis is utilized. Results of this study suggest that the condensed phase photolysis of SOA can occur with effective lifetimes ranging from minutes to hours, and therefore represents a potentially important aging mechanism for SOA. The outcome of this dissertation will be improved understanding of the role of condensed-phase photochemistry in chemical aging of aerosol particles and cloud droplets.
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.
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 772 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.
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 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 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 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.
Book Synopsis Air Pollution Modeling and its Application XVII by : Carlos Borrego
Download or read book Air Pollution Modeling and its Application XVII written by Carlos Borrego and published by Springer Science & Business Media. This book was released on 2007-04-05 with total page 750 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 1969 the North Atlantic Treaty Organisation (NATO) established the Committee on Challenges of Modern Society (CCMS). The subject of air pol- tion was from the start, one of the priority problems under study within the fra- work of various pilot studies undertaken by this committee. The organization of a periodic conference dealing with air pollution modeling and its application has become one of the main activities within the pilot study relating to air pollution. The first five international conferences were organized by the United States as the pilot country; the second five by the Federal Republic of Germany; the third five by Belgium; the next four by The Netherlands; and the next five by Denmark; and with this one, the last three by Portugal. th This volume contains the papers and posters presented at the 27 NATO/CCMS International Technical Meeting on Air Pollution Modeling and Its Application held in Banff, Canada, 24-29 October 2004. The key topics at this ITM included: Role of Atmospheric Models in Air Pollution Policy and Abatement Strategies; Integrated Regional Modeling; Effects of Climate Change on Air Quality; Aerosols as Atmospheric Contaminants; New Developments; and Model Assessment and Verification. 104 participants from North and South America, Europe, Africa and Asia attended th the 27 ITM. The conference was jointly organized by the University of Aveiro, Portugal (Pilot Country) and by The University of Calgary, Canada (Host Country). A total of 74 oral and 22 poster papers were presented during the conference.
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 Modeling the Explicit Chemistry of Anthropogenic and Biogenic Organic Aerosols by :
Download or read book Modeling the Explicit Chemistry of Anthropogenic and Biogenic Organic Aerosols written by and published by . This book was released on 2015 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The atmospheric burden of Secondary Organic Aerosols (SOA) remains one of the most important yet uncertain aspects of the radiative forcing of climate. This grant focused on improving our quantitative understanding of SOA formation and evolution, by developing, applying, and improving a highly detailed model of atmospheric organic chemistry, the Generation of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) model. Eleven (11) publications have resulted from this grant.
Book Synopsis Multiphase Environmental Chemistry in the Atmosphere by : Sherri W. Hunt
Download or read book Multiphase Environmental Chemistry in the Atmosphere written by Sherri W. Hunt and published by ACS Symposium. This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights new cross-disciplinary advances in aerosol chemistry that involve more than one phase, for example, unique chemical processes occurring on gas-solid and liquid-solid interfaces.
Book Synopsis Chemistry of Organic Aerosol Formation from Biogenic and Anthropogenic Hydrocarbon Sources by : Manuel Dekermenjian
Download or read book Chemistry of Organic Aerosol Formation from Biogenic and Anthropogenic Hydrocarbon Sources written by Manuel Dekermenjian and published by . This book was released on 1998 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Characterizing the Formation of Secondary Organic Aerosols by :
Download or read book Characterizing the Formation of Secondary Organic Aerosols written by and published by . This book was released on 2004 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic aerosol is an important fraction of the fine particulate matter present in the atmosphere. This organic aerosol comes from a variety of sources; primary organic aerosol emitted directly from combustion process, and secondary aerosol formed in the atmosphere from condensable vapors. This secondary organic aerosol (SOA) can result from both anthropogenic and biogenic sources. In rural areas of the United States, organic aerosols can be a significant part of the aerosol load in the atmosphere. However, the extent to which gas-phase biogenic emissions contribute to this organic load is poorly understood. Such an understanding is crucial to properly apportion the effect of anthropogenic emissions in these rural areas that are sometimes dominated by biogenic sources. To help gain insight on the effect of biogenic emissions on particle concentrations in rural areas, we have been conducting a field measurement program at the University of California Blodgett Forest Research Facility. The field location includes has been used to acquire an extensive suite of measurements resulting in a rich data set, containing a combination of aerosol, organic, and nitrogenous species concentration and meteorological data with a long time record. The field location was established in 1997 by Allen Goldstein, a professor in the Department of Environmental Science, Policy and Management at the University of California at Berkeley to study interactions between the biosphere and the atmosphere. The Goldstein group focuses on measurements of concentrations and whole ecosystem biosphere-atmosphere fluxes for volatile organic compounds (VOC's), oxygenated volatile organic compounds (OVOC's), ozone, carbon dioxide, water vapor, and energy. Another important collaborator at the Blodgett field location is Ronald Cohen, a professor in the Chemistry Department at the University of California at Berkeley. At the Blodgett field location, his group his group performs measurements of the concentrations of important gas phase nitrogen compounds. Experiments have been ongoing at the Blodgett field site since the fall of 2000, and have included portions of the summer and fall of 2001, 2002, and 2003. Analysis of both the gas and particle phase data from the year 2000 show that the particle loading at the site correlates with both biogenic precursors emitted in the forest and anthropogenic precursors advected to the site from Sacramento and the Central Valley of California. Thus the particles at the site are affected by biogenic processing of anthropogenic emissions. Size distribution measurements show that the aerosol at the site has a geometric median diameter of approximately 100 nm. On many days, in the early afternoon, growth of nuclei mode particles (
Book Synopsis Determining Biogenic and Anthropogenic Contributions to Secondary Organic Aerosol by : Archit Mehra
Download or read book Determining Biogenic and Anthropogenic Contributions to Secondary Organic Aerosol written by Archit Mehra and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
