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Analysis Of Tracer Molecules From Organic Aerosols
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Book Synopsis Analysis of Tracer Molecules from Organic Aerosols by : Murtaza Hyder
Download or read book Analysis of Tracer Molecules from Organic Aerosols written by Murtaza Hyder and published by LAP Lambert Academic Publishing. This book was released on 2012-08 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Airborne particulate matter is well known because of its adverse impacts on human health and its role in climate processes. The chemical composition of atmospheric aerosols is of basic importance. Chemical analysis of aerosols involves broadly two steps, extraction step and detection/quantification of chemical constituents. Generally aerosols are extracted using classical techniques which, have many disadvantages. This dissertation addresses the use of both classical extraction methods and liquid membrane based extraction as a sample preparation steps for aerosols analysis. Common techniques that are used for this purpose are not environmentally green as they involve a lot of organic solvent, they are not efficient and selective enough and do not serve the purpose of trace level analysis as they do not give sufficiently high enrichment. We have shown that hollow fiber liquid phase microextraction (HF-LPME), which is environmentally green is applicable to aerosol samples. Both two-phase and three phase HF-LPME are very helpful in pre-concentration of analytes from aerosol. The dissertation summarises the results of our research for the last four years.
Book Synopsis Small Molecules as Tracers in Atmospheric Secondary Organic Aerosol by :
Download or read book Small Molecules as Tracers in Atmospheric Secondary Organic Aerosol written by and published by . This book was released on 2015 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: Secondary organic aerosol (SOA), formed from in-air oxidation of volatile organic compounds, greatly affects human health and climate. Although substantial research has been devoted to SOA formation and evolution, the modeled and lab-generated SOA are still low in mass and degree of oxidation compared to ambient measurements. In order to compensate for these discrepancies, the aqueous processing pathway has been brought to attention. The atmospheric waters serve as aqueous reaction media for dissolved organics to undergo further oxidation, oligomerization, or other functionalization reactions, which decreases the vapor pressure while increasing the oxidation state of carbon atoms. Field evidence for aqueous processing requires the identification of tracer products such as organosulfates. We synthesized the standards for two organosulfates, glycolic acid sulfate and lactic acid sulfate, in order to measure their aerosol-state concentration from five distinct locations via filter samples. The water-extracted filter samples were analyzed by LC-MS. Lactic acid sulfate and glycolic acid sulfate were detected in urban locations in the United States, Mexico City, and Pakistan with varied concentrations, indicating their potential as tracers. We studied the aqueous processing reaction between glyoxal and nitrogen-containing species such as ammonium and amines exclusively by NMR spectrometry. The reaction products formic acid and several imidazoles along with the quantified kinetics were reported. The brown carbon generated from these reactions were quantified optically by UV-Vis spectroscopy. The organic-phase reaction between oxygen molecule and alkenes photosensitized by [alpha]-dicarbonyls were studied in the same manner. We observed the fast kinetics transferring alkenes to epoxides under simulated sunlight. Statistical estimations indicate a very effective conversion of aerosol-phase alkenes to epoxides, potentially forming organosulfates in a deliquescence event and increasing aerosol mass. Finally, we built a containerless apparatus to study aqueous processing reactions using an acoustic levitator paired with a mass spectrometer. The levitator is capable of trapping droplets with the size of 80-500 [mu]m in diameter for over eight hours. The apparatus is also capable of drying and wetting the droplet in a controllable manner. We performed am example reaction between glyoxal and ammonium sulfate using this instrument, and showed that it could qualitatively monitor aqueous processing reactions.
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:
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 Atmospheric Tracer Technology and Applications by : Jody H. Heiken
Download or read book Atmospheric Tracer Technology and Applications written by Jody H. Heiken and published by William Andrew. This book was released on 1986 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Source Apportionment of Carbonaceous Aerosols Using Integrated Multi-variant and Source Tracer Techniques and a Unique Molecular Marker Data Set by : James J. Schauer
Download or read book Source Apportionment of Carbonaceous Aerosols Using Integrated Multi-variant and Source Tracer Techniques and a Unique Molecular Marker Data Set written by James J. Schauer and published by . This book was released on 2012 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 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 Complex Mixtures by : Emma Quinn Walhout
Download or read book Complex Mixtures written by Emma Quinn Walhout and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Complex organic mixtures in the environment can contain hundreds to thousands of different organic molecules, and their composition and reactivity can have important environmental implications. In addition to gases, the atmosphere is made of a variety of small liquids and solids called aerosols. These aerosols have large impacts on human health, climate, and atmospheric chemical reactions. Here, secondary organic aerosol (SOA) from the ozonolysis of [alpha]-pinene is characterized. The atmospheric lifetime of SOA is very uncertain, but recent laboratory and modeling studies have demonstrated that photolysis is potentially an important process for organic mass loss from aerosol particles.1-5 Photolysis modifies the molecular composition and properties of aerosols through photolytic cleaving and repartitioning of volatile products. Characterization of dry, irradiated SOA can provide insights into photolysis driven changes in absorption properties and chemical composition. These results illuminate aging mechanisms and chemical and physical properties of organic aerosols in order to improve atmospheric modeling and the understanding of atmospheric chemical reactions. However, the high chemical complexity and low atmospheric abundance presents a difficult analytical challenge. Milligrams, or more, of material may be needed for speciated spectroscopic analysis.6 This study used a suite of advanced analytical techniques, including a novel combination of action spectroscopy and mass spectrometry that provides more structural information on organic mixtures than mass spectrometry alone. This study also used tunable light from a free electron laser, infrared and UV/Vis absorption, and computational chemistry to characterize molecules in [alpha]-pinene SOA. In addition, complex organic mixtures are also found in particulate matter that has deposited onto Earth’s surface. The preliminary results of dew analysis, including a foundation method of analysis for future study, gives the first look at organic material deposited into dew water on natural surfaces. This offers insight into atmospheric organic deposition to better understand chemical transport, air quality, and carbon cycling in the atmosphere.
Book Synopsis Ozone and Other Photochemical Oxidants by :
Download or read book Ozone and Other Photochemical Oxidants written by and published by National Academies. This book was released on 1977-01-01 with total page 740 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Organosilicon Materials by : Grish Chandra
Download or read book Organosilicon Materials written by Grish Chandra and published by . This book was released on 2014-01-15 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Particulate Matter Science for Policy Makers by : Peter H. McMurry
Download or read book Particulate Matter Science for Policy Makers written by Peter H. McMurry and published by Cambridge University Press. This book was released on 2004-11-29 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt: Particulate Matter Science for Policy Makers: A NARSTO Assessment was commissioned by NARSTO, a cooperative public-private sector organization of Canada, Mexico and the United States. It is a concise and comprehensive discussion of the current understanding by atmospheric scientists of airborne particulate matter (PM). Its goal is to provide policy makers who implement air-quality standards with this relevant and needed scientific information. The primary audience for this volume will be regulators, scientists, and members of industry, all of whom have a stake in effective PM management. It will also inform exposure and health scientists, who investigate causal hypotheses of health impacts, characterize exposure, and conduct epidemiological and toxicological studies.
Book Synopsis Urban Aerosols and Their Impacts by : Jeffrey S. Gaffney
Download or read book Urban Aerosols and Their Impacts written by Jeffrey S. Gaffney and published by . This book was released on 2006 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: Urban aerosols have been identified as important species of concern due to their potential health and environmental impacts. This symposium series book will describe the basic chemistry and physics determining the impacts of aerosol species and will highlight the research results from the measurements that were taken following the collapse of the World Trade Center (WTC) on 9/11/01. The WTC tragedy led to the release of millions of pounds of debris aside from the structural steel, part of which was widely dissipated as aerosols and particulates in the debris cloud over lower Manhattan. Additionally, continuing fires under the debris led to the release of fine combustion related aerosols for a considerable time period in this urban environment. Held during the week of the second anniversary of the WTC tragedy in NYC, the symposium book will describe various aspects of the event, aerosol and gas exposures, and the related impacts of these aerosols. The book contributions will highlight efforts work from atmospheric chemists, meteorologists, health workers, and biologists for a timely compilation of what is known and not known about the composition and transport of tropospheric aerosols in urban environs, particularly those from the WTC collapse. Particular interest is in the acute and chronic environmental effects of these aerosols as they impact human health. Chapters included in the book will also address aerosol lifetimes, aerosol transport and removal processes, acute and chronic health effects to fine aerosol and particulate exposures, and the environmental impacts of aerosols.
Book Synopsis Natural Organic Compounds as Tracers for Biomass Combustion in Aerosols by :
Download or read book Natural Organic Compounds as Tracers for Biomass Combustion in Aerosols written by and published by . This book was released on 1995 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biomass combustion is an important primary source of carbonaceous particles in the global atmosphere. Although various molecular markers have already been proposed for this process, additional specific organic tracers need to be characterized. The injection of natural product organic tracers to smoke occurs primarily by direct volatilization/steam stripping and by thermal alteration based on combustion temperature. The degree of alteration increases as the burn temperature rises and the moisture content of the fuel decreases. Although the molecular composition of organic matter in smoke particles is highly variable, the molecular structures of the tracers are generally source specific. The homologous compound series and biomarkers present in smoke particles are derived directly from plant wax, gum and resin by volatilization and secondarily from pyrolysis of biopolymers, wax, gum and resin. The complexity of the organic components of smoke aerosol is illustrated with examples from controlled burns of temperate and tropical biomass fuels. Burning of biomass from temperate regions (i.e., conifers) yields characteristic tracers from diterpenoids as well as phenolics and other oxygenated species, which are recognizable in urban airsheds. The major organic components of smoke particles from tropical biomass are straight-chain, aliphatic and oxygenated compounds and triterpenoids. The precursor-to-product approach of organic geochemistry can be applied successfully to provide tracers for studying smoke plume chemistry and dispersion.
Book Synopsis Molecular Characterization of Organic Aerosol by Mass Spectrometry by : Yuqian Gao
Download or read book Molecular Characterization of Organic Aerosol by Mass Spectrometry written by Yuqian Gao and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic aerosol is a major constituent of atmospheric fine particles, especially over continental regions. These particles adversely affect human health and global climate. A significant fraction of organic aerosol is considered to be from the oxidation products of ozone and volatile organic compounds, which are called secondary organic aerosol (SOA). To study the formation mechanisms of secondary organic aerosol, it is important to characterize their molecular composition. The composition of secondary organic aerosol is very complex including thousands of species with molecular weight up to over a thousand Dalton. Methods utilized for the identification of these oxidation products involve advanced mass spectrometry techniques. In this dissertation, three mass spectrometry techniques were developed to study the molecular composition of organic aerosol. Firstly, online nano-aerosol sample deposition methods for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry was developed to incorporate matrix particles directly with analyte particles onto a conventional MALDI plate. Secondly, a microsampling and analysis technique was developed in order to collect microgram samples and analyze them with high performance mass spectrometry. With this technique, the molecular composition of particle phase SOA at a low mass loading can be elucidated, which provides information about SOA formation at the early stages. A species with the (neutral molecule) formula C 17 H 26 O 8 (MW 358) increased substantially in intensity relative to other products as the mass loading decreased. Tandem mass spectrometry (MS n) of this species showed it to be a dimer of C 9 H 14 O 4 and C 8 H 12 O 4, most likely pinic acid and terpenylic acid, respectively. This species is likely to be critical at the early stages of SOA formation. Thirdly, ambient secondary electrospray ionization (ESI) source was designed to characterize the molecular composition of both gas and particle phases SOA online. This ion source was demonstrated to be applicable to a wide range of mass spectrometers having an ambient inlet. This technique provides a tool to acquire detailed information about possible SOA nucleation agents. A species with the (neutral molecule) formula C 20 H 36 O 6 (MW 372) was found in the gas-phase products of SOA, which could be critical for the new particle formation of SOA. Tandem mass spectrometry (MS n) of this species showed it to be a dimer of an organic hydroperoxide C 10 H 18 O 3, which is likely formed via OH-initiated oxidation pathway.
Book Synopsis Introduction to Atmospheric Chemistry by : Daniel J. Jacob
Download or read book Introduction to Atmospheric Chemistry written by Daniel J. Jacob and published by Princeton University Press. This book was released on 1999 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atmospheric chemistry is one of the fastest growing fields in the earth sciences. Until now, however, there has been no book designed to help students capture the essence of the subject in a brief course of study. Daniel Jacob, a leading researcher and teacher in the field, addresses that problem by presenting the first textbook on atmospheric chemistry for a one-semester course. Based on the approach he developed in his class at Harvard, Jacob introduces students in clear and concise chapters to the fundamentals as well as the latest ideas and findings in the field. Jacob's aim is to show students how to use basic principles of physics and chemistry to describe a complex system such as the atmosphere. He also seeks to give students an overview of the current state of research and the work that led to this point. Jacob begins with atmospheric structure, design of simple models, atmospheric transport, and the continuity equation, and continues with geochemical cycles, the greenhouse effect, aerosols, stratospheric ozone, the oxidizing power of the atmosphere, smog, and acid rain. Each chapter concludes with a problem set based on recent scientific literature. This is a novel approach to problem-set writing, and one that successfully introduces students to the prevailing issues. This is a major contribution to a growing area of study and will be welcomed enthusiastically by students and teachers alike.
