Carbonyls and BTEX (Benzene, Toluene, Ethylbenzene, and Xylenes) represent an important class of VOCs (volatile organic compounds) in the atmosphere. They are emitted into the atmosphere through anthropogenic and biogenic sources. Their atmospheric degradation leads to the formation of ozone, photooxidants and organic aerosols affecting the air quality at the local and regional scales and human health. It is, hence, of importance to measure their atmospheric concentrations and investigate their fate. In the present thesis, we have conducted a systematic measurement study of carbonyls and BTEX in Beijing during the period of Jul 2008-Aug 2010 in order to evaluate their ambient levels, possible sources and the influence of characteristic weather conditions. In a separate work, we performed a series of experimental studies on the OH-initiated oxidation of isopropyl formate, isobutyl formate, and n-propyl isobutyrate using the ICARE-CNRS (Orleans) simulation chamber from which we derived the product yields. The data obtained are presented and discussed.

Interest in volatile organic compounds (VOCs) as air pollutants has increased dramatically in recent years. This book covers a number of very topical issues concerning VOCs, including stratospheric ozone depletion due to CFCs, and the properties of alternative substances; the role of VOCs in the photochemical formation of lower atmosphere (tropospheric) ozone; and the problem of the direct toxicity of VOCs such as benzene and formaldehyde. This Issue reviews our current knowledge of VOCs, drawing upon the expertise of renowned experts and major national and international research programmes. It examines man-made and natural sources, as well as pathways and chemical reactions in the atmosphere. It also looks closely at the sources and concentrations of VOCs indoors, where humans are most likely to be exposed to them. Volatile Organic Compounds in the Atmosphere describes techniques used for the calculation of emissions inventories and strategies for control, and explores the many Government policy matters relating to VOCs. It provides readers with in-depth, clearly explained coverage of the many complex scientific and policy issues surrounding VOCs in the atmosphere.

Every day, large quantities of volatile organic compounds (VOCs) are emitted into the atmosphere from both anthropogenic and natural sources. The formation of gaseous and particulate secondary products caused by oxidation of VOCs is one of the largest unknowns in the quantitative prediction of the earth’s climate on a regional and global scale, and on the understanding of local air quality. To be able to model and control their impact, it is essential to understand the sources of VOCs, their distribution in the atmosphere and the chemical transformations which remove these compounds from the atmosphere. In recent years techniques for the analysis of organic compounds in the atmosphere have been developed to increase the spectrum of detectable compounds and their detection limits. New methods have been introduced to increase the time resolution of those measurements and to resolve more complex mixtures of organic compounds. Volatile Organic Compounds in the Atmosphere describes the current state of knowledge of the chemistry of VOCs as well as the methods and techniques to analyse gaseous and particulate organic compounds in the atmosphere. The aim is to provide an authoritative review to address the needs of both graduate students and active researchers in the field of atmospheric chemistry research.

To be able to understand and predict the concentration of a target compound in the atmosphere one must understand the atmospheric chemistry involved. The transformation of volatile organic compounds (VOCs) in the troposphere is predominantly driven by the interaction with the hydroxyl and nitrate radicals. The hydroxyl radical exists in daylight conditions and its reaction rate constant with an organic compound is typically very fast. The nitrate radical drives the nighttime chemistry. These radicals can scavenge hydrogen from an organic molecule generating secondary products that are often overlooked in detection schemes. Secondary products can be more stable and serve as a better target compound in detection schemes. The gas-phase reaction of the hydroxyl radical (OH) with cyclohexanol (COL) has been studied. The rate coefficient was determined to be (19.0+4.8) x 10-12cm3 molecule-1 s-1 (at 297+3 oK and 1 atmosphere total pressure) using the relative rate technique with pentanal, decane, and tridecane as the reference compounds. Assuming an average OH concentration of 1 x 106 molecules cm-3, an atmospheric lifetime of 15 h is calculated for cyclohexanol. Products of the OH + COL reaction were determined to more clearly define cyclohexanol's atmospheric degradation mechanism. The observed products were: cyclohexanone, hexanedial, 3-hydroxycyclohexanone, and 4-hydroxycyclohexanone. Consideration of the potential reaction pathways suggests that each of these products is formed via hydrogen abstraction at a different site on the cyclohexanol ring.

Prepared by an international team of eminent atmospheric scientists, Mechanisms of Atmospheric Oxidation of the Oxygenates is an authoritative source of information on the role of oxygenates in the chemistry of the atmosphere. The oxygenates, including the many different alcohols, ethers, aldehydes, ketones, acids, esters, and nitrogen-atom containing oxygenates, are of special interest today due to their increased use as alternative fuels and fuel additives. This book describes the physical properties of oxygenates, as well as the chemical and photochemical parameters that determine their reaction pathways in the atmosphere. Quantitative descriptions of the pathways of the oxygenates from release or formation in the atmosphere to final products are provided, as is a comprehensive review and evaluation of the extensive kinetic literature on the atmospheric chemistry of the different oxygenates and their many halogen-atom substituted analogues. This book will be of interest to modelers of atmospheric chemistry, environmental scientists and engineers, and air quality planning agencies as a useful input for development of realistic modules designed to simulate the atmospheric chemistry of the oxygenates, their major oxidation products, and their influence on ozone and other trace gases within the troposhere.

Oxides and acids of nitrogen play an important role in regulating atmospheric radical levels, in particular, that of the OH radical the main initiator of the degradation of chemicals in the atmosphere. A comprehensive overview on the methods used to measure nitrogen oxides and acids in the troposphere is given and difficulties and artefacts associated with the use of the techniques for measurements in urban and mega city environments is illustrated. State-of-the-art methods for the measurement of OH and HO2 radicals are reviewed and recently recognised difficulties, in particular with the measurement of HO2 radicals, are highlighted. Other contributions to the book cover our present understanding of the gas, aqueous and particulate/aerosol phase atmospheric degradation chemistry of volatile organic compounds (VOCs) under NOx conditions typical of rural, urban and mega city environments. Examples of measurements of NOx and VOCs in the atmospheres of these environments are given, in particular for the megacities Cairo and Beijing, in conjunction with modelling studies which attempt to simulate the field observations using state-of-the art knowledge on the chemistry of the VOCs and radical levels.

In the early 1980s, two water-supply systems on the Marine Corps Base Camp Lejeune in North Carolina were found to be contaminated with the industrial solvents trichloroethylene (TCE) and perchloroethylene (PCE). The water systems were supplied by the Tarawa Terrace and Hadnot Point watertreatment plants, which served enlisted-family housing, barracks for unmarried service personnel, base administrative offices, schools, and recreational areas. The Hadnot Point water system also served the base hospital and an industrial area and supplied water to housing on the Holcomb Boulevard water system (full-time until 1972 and periodically thereafter). This book examines what is known about the contamination of the water supplies at Camp Lejeune and whether the contamination can be linked to any adverse health outcomes in former residents and workers at the base.

The Committee on Ozone-Forming Potential for Reformulated Gasoline was asked whether the existing body of scientific and technical information is sufficient to permit a robust evaluation and comparison of the emissions from motor vehicles using different reformulated gasolines based on their ozone-forming potentials and to assess the concomitant impact of that approach on air-quality benefits of the use of oxygenates within the RFG program. As part of its charge, the committee was asked to consider (1) the technical soundness of various approaches for evaluating and comparing the relative ozone-forming potentials of RFG blends, (2) technical aspects of various air-quality issues related to RFG assessment, and (3) the sensitivity of evaluations of the relative ozone-forming potentials to factors related to fuel properties and the variability of vehicle technologies and driving patterns.