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Volatile Organic Compounds (VOC), including saturated, unsaturated, and other substituted hydrocarbons, play a major role in atmospheric chemistry. They are primarily emitted by anthropogenic and biogenic sources into the atmosphere; they are also transformed in situ by chemical reactions, and more specifically, by photo-oxidation leading to the formation of ozone (O3) and Secondary Organic Aerosol (SOA). By altering the organic fraction of aerosol particles, VOC modify the Earth's radiative balance through a direct effect (absorption and scattering of solar radiation) or through indirect effect by altering cloud microphysical properties. They also present a direct effect on human health and on the environment.During their atmospheric transport, VOC and their oxidation products, Oxygenated Volatile Organic Compounds (OVOC), may partition between the gaseous and aqueous phases depending on their solubility. Clouds have a significant effect on tropospheric chemistry by redistributing trace constituents between phases and by providing liquid water in which aqueous phase chemistry can take place. Indeed, during the cloud lifetime, chemical compounds and particularly VOC are efficiently transformed since clouds favor the development of complex “multiphase chemistry”. The latter presents several particularities. First, photochemical processes inside the droplets are important in the transformation of chemical compounds. Second, aqueous chemical reactions are efficient and can be faster than the equivalent reactions in the gas phase. This can be related to the presence of strong oxidants such as hydrogen peroxide H2O2 or Transition Metal Ions (TMI), which participate in the formation of radicals such as hydroxyl radicals (HO•) that favor oxidation processes. Furthermore, the presence of viable microorganisms has been highlighted and shown to participate in transformations of the chemical species. Finally, these transformations in clouds are also strongly perturbed by microphysical processes that control formation, lifetime and dissipation of clouds. These processes will redistribute the chemical species between the different reservoirs (cloud water, rain, particle phase, gaseous phase, and solid ice phase). In this frame, the transformation of VOC in the cloud medium can lead to the production of secondary compounds contributing to SOA formation, reported as “cloud aqSOA”. This secondary organic aerosol mass produced during the cloud lifetime could explain in part the ubiquity of small dicarboxylic and keto acids and high molecular-weight compounds measured in aerosol particles, fog water, cloud water, or rainwater at many locations, as they have neither substantial direct emission sources nor any identified important source in the gas phase. This aqSOA mass stays in the particle phase after cloud evaporation implying a modification of the (micro)physical and chemical properties of aerosol particles (particle size, chemical composition, morphology). This leads to modifications of their impacts on consecutive cloud or fog cycles (aerosol indirect effects) and of their interactions with incoming radiation by scattering/absorbing (aerosol direct effect). (...).
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.
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.
Biogenic Volatile Organic Compounds and Climate Change highlights the relationship between climate change and biogenic VOC and the impact they have on each other. Topics include the synthesis and emission of VOC in plants, how they respond to environmental stresses, how sustainable agricultural practices plants can be used to directly impact climate change beyond carbon sequestration, a review of biogenic VOCs as air pollutants, and the impact of biogenic VOC on clouds. This groundbreaking work is essential for anyone in climate change, global warming and cooling, atmospheric chemistry, clouds, fate and transport of chemicals in the atmosphere, air pollution, sustainability or agriculture. - Explains how volatile organic compound (VOC) production and emission in plants can ameliorate the consequences of climate change induced abiotic and biotic stresses - Comprehensively addresses the complex interactions between global warming, atmospheric composition and plant ecology beyond carbon sequestration - Reviews the use of biogenic VOC in sustainability
Volatile organic compounds (VOCs) are hazardous highly toxic pollutants that cause a number of environmental and human health problems. They are released during a wide range of industrial, transportation and commercial activities and their emissions have reached high levels. This book provides a review of the occurrence, behavior and ecological implications of VOCs. Chapter One evaluates the biogeneration of volatile organic compounds produced by microalgae. Chapter Two investigates VOC pollution from industrial complexes and wastewater treatment plants (WWTPs). Chapter Three illustrates the current knowledge of intra- and inter- organismal Microbial Volatile Organic Compounds (mVOCs)-based interactions, volatile perception, signal transduction and phenotypical responses in the receiver organisms. Chapter Four summarises the current state of knowledge regarding the impact of emissions from gasoline powered vehicles on historical ambient VOC concentration trends, and on the current ambient urban atmosphere of the South Coast Air Basin. Chapter Five discusses the oxidation of VOCs over cyptomelane catalysts. Chapter Six studies VOCs from truffles and false truffles from Basilicata in Southern Italy. Chapter Seven discusses the removal of VOCs in the air by total catalytic oxidation promoted by catalysts.
The complete guide to the control of volatile organic compound (VOC) emissions. With increased regulatory pressures on air pollution emissions, there is a growing need for innovative control technologies in a wide range of industries. This timely and authoritative book explores the science, technology, economics, and applications specific to the control of volatile organic compound (VOC) emissions. Engineer Paige Hunter joins forces with S. Ted Oyama, an expert in VOC control and a renowned ozone chemist, to present a thorough review of both conventional and emerging techniques for the treatment of VOC-containing streams. They provide detailed technical descriptions, up-to-date cost data on processes, and practical information for industry professionals on how to apply the techniques in diverse fields. Coverage includes: * Comparisons of the major conventional control methods for the treatment of VOC-containing streams * The new technologies of membrane filtration, ultraviolet oxidation, and corona destruction * The cutting-edge technology of catalytic ozonation, suitable for retrofitting existing processes or control systems * International aspects of air pollution and VOC control * A comprehensive listing of hazardous air pollutants (HAPSs) and VOCs * Dozens of illustrations and photographs as well as references to Internet resources
Volatile Organic Compounds (VOCs) have anthropogenic and biogenic origins. At the Earth's scale, the natural sources represent a great part of the total VOCs present in the atmosphere but in industrialized regions, anthropogenic ones become the majority due to the various human activities related mainly to chemical industries (liquid fuels, solvents, thinners, detergents, degreasers, cleaners and lubricants). Almost all VOCs have effects on human health and many of them are even carcinogenic. It is also known that the VOCs can affect the central nervous system and may have mutagenic effects. Apart from human health, they also play an important role towards the environment, especially in the atmospheric pollution processes. Indeed, VOCs emissions lead to the promotion of photochemical reactions in the atmosphere (ozone formation, depletion of the stratospheric ozone layer and formation of photochemical smog). The present book gathers and presents some current research from across the world conducted by scientific experts in their fields. In seven valuable contributions, it deals with the emission and the environmental impact as well as the control of the Volatile Organic Compounds.