Author: Murtaza Hyder Publisher: LAP Lambert Academic Publishing ISBN: 9783659222955 Category : Languages : en Pages : 76
Book Description
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.
Author: Publisher: ISBN: Category : Languages : en Pages : 306
Book Description
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.
Author: Publisher: ISBN: Category : Languages : en Pages : 6
Book Description
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.
Author: Peter H. McMurry Publisher: Cambridge University Press ISBN: 9780521842877 Category : Law Languages : en Pages : 652
Book Description
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.
Author: Carlos Borrego Publisher: Springer Science & Business Media ISBN: 0387688544 Category : Science Languages : en Pages : 750
Book Description
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.
Author: Murtaza Hyder
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Author: Jody H. Heiken
Author: James J. Schauer
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Author: Grish Chandra
Author: Peter H. McMurry
Author: Carlos Borrego