Limonene-derived Secondary Organic Aerosol PDF Download

Author: Maggie Lynn Walser
Publisher:
ISBN:
Category : Atmospheric aerosols
Languages : en
Pages : 252

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Author: Chunyi Wang
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 372

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People in developed countries spend about 90% of their time indoors, so controlling in-door air quality (IAQ) is of primary importance for not harming public health. Airborne particu-late matter (PM) is one of the most problematic pollutants indoors, since exposure to particles with aerodynamic diameters smaller than 2.5 Îơm (i.e, PM2.5) is associated with respiratory dis-eases, as well as morbidity and mortality outcomes. Organic aerosol components, so called organic aerosol (OA), generally comprise the ma-jor portion of indoor PM, owing to its large indoor emission. One important component of OA indoors is secondary organic aerosol (SOA), which are condensed phase particles composed of semi- and low-volatility compounds. Most research has focused on SOA generated by terpene ozonolysis occurring in the gas phase. This work, however, explores a lesser researched for-mation mechanism, which is the possibility of airborne SOA generated by ozone surface reac-tions with sorbed squalene (C30H50), which is a nonvolatile constituent of skin oil. As such, thirteen steady state chamber experiments were performed to measure the SOA formation en-tirely initiated by ozone reactions with squalene sorbed to glass at two RH conditions of 21% and 51%, in the absence of seed particles. SOA was initiated from these surface reactions, and all experiments but one exhibited nucleation and mass formation. Mass formation increased with ozone concentration at RH = 51% while nucleation was more obvious at RH = 21%. Additionally, most indoor OA, either emitted or generated (i.e., not only SOA), is at composed of semivolatile compounds (SVOCs) in a state of dynamic equilibrium between gas and particle phases. Filters might have a reduced efficiency on removing these kinds of particles since they coexist in gas and condensed aerosol phases. The preferential filtration of particle phase material of the OA system could disrupt the equilibrium, and the removed aerosols might be enhanced by desorption from surfaces and repartitioning from gas phase. To explore this phenomenon, three types of particles, including non-volatile ammonium sulfate ((NH4)2SO4) aerosol, incense aerosol (which might be partly semi-volatile), and SOA derived from ozone + d-limonene reactions (the majority of which are SVOCs), were characterized and compared in terms of their effective removal by a portable air cleaner. For this comparison, the metric of the Clean Air Delivery Rate, CADR (m3/h), was used, which is the volumetric flow of pollutant-free air produced by an air cleaner. Results demonstrated that the lowest effective CADR was for SOA, followed by the incense, and then the ammonium sulfate particles, indicating a repar-titioning processes reduced the filter efficiency. Then a model based on the principles of desorp-tion and repartition process was developed, to quantify the reduced CADR as a function of par-ticle concentration and distribution, in terms of parameter ATSP, which is the ratio of particle surface area to mass. Finally, the influence of the above two parameters on amount of CADR reduction was discussed. Using some details gleaned from the above two experimental studies, a thermodynamic equilibrium model was developed using the volatile basis set (VBS), to predict indoor organic aerosol concentrations and behavior. The model outcomes are the total organic mass indoors (gas + condensed phase), and the fraction of it that partitions to the aerosol phase, including that existing as SOA formed by ozone + d-limonene reactions. With this model, the total OA concentration was simulated at key locations in an indoor environment, such as in the occupied space and different positions in a building mechanical system. The impacts of different condi-tions were compared, including commercial against residential buildings, surface against gas reactions, and winter against summer, within a Monte Carlo framework. Indoor OA concentra-tion indoors were higher when reactions were involved, and gas phase reactions had much more influence on SOA than surface reactions. Finally, the result dataset was used to evaluate the influence of key factors on the indoor OA concentrations, using multiple linear regression sen-sitivity methods. The most important factor that enhanced indoor particles was d-limonene emission rate with average SRC of 0.73, while the negative related factors were filtration effi-ciency with SRC of -0.33 for commercial and surface deposition rate with SRC of -0.22 for resi-dential buildings. Beyond the three SOA studies discussed above, humidifiers used indoors might be strong PM emitters. So, as a supplementary piece, this work also investigated the influence of three humidifier types (ultrasonic, evaporative, and steam humidifiers), and water type used (tap water, de-ionized (DI) water or distilled water), on indoor aerosol number/mass concentra-tions by performing 16 experiments. Particle size distribution during emission periods and size-resolved emission rates were explored to compare the emission ability of humidifiers. Two lung deposition models were also applied to simulate the deposition percentage of particles breathed in on three lung regions (HA, TB, and AL), and total percentage on varying age groups. Results showed that two year-old group was most vulnerable, with number deposition fractions of 0.36, compared with 0.25 for adults. Furthermore, roughly 70% of the total emitted particles pene-trates into the AL region of the lung.

Author: Jean Demaison
Publisher: Springer Science & Business Media
ISBN: 9401008329
Category : Science
Languages : en
Pages : 355

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Many satellites have recently been launched or are in preparation, which operate in the microwave to IR ranges, the main objective being to observe the earth's atmosphere or interstellar clouds. Analysis of the data they supply requires extensive laboratory work because we still only have sufficiently accurate data (line positions, intensities, and profiles) for only a few species. Furthermore, the observer community is making increasing calls for laboratory data, as new development open up new observational possibilities (such as submillimeter observation). Research on these subjects involves many different areas of specialisation in fields of research that generate a wealth of data. In Spectroscopy from Space the people responsible for field observations explain which results they are expecting from their measurements and how laboratory people can help them to analyse their satellite data. Laboratory spectroscopists explain why what they can do now, and what kinds of experiment and theoretical development that might undertake to meet the needs of the remote sensing community. The problems of distributing reliable laboratory data in a timely way are also addressed.

Author: Sherri W. Hunt
Publisher: ACS Symposium
ISBN: 9780841233638
Category : Science
Languages : en
Pages : 0

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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.

Author: Jack G. Calvert
Publisher: Oxford University Press
ISBN: 9780199771547
Category : Science
Languages : en
Pages : 570

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This text reviews many of the aspects of the chemistry of the aromatic hydrocarbons and a consensus evaluation of the data by seven of the leading atmospheric scientists. The book covers topics ranging from the relative importance of the compounds in ozone and haze development to methods of estimating elemantary rate coefficients based on structural features of the compounds to mechanisms of aerosol generation and atmostpheric reaction of the polycyclic compounds to photochemical processes. It identifies features of the aromatic hydrocarbons requiring further study and appendicies give the structural formulas and nomenclature of the compounds reviewed in the book.

Author: Rekha Kale
Publisher: Scitus Academics LLC
ISBN: 9781681171326
Category : Aerosols
Languages : en
Pages : 0

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Atmospheric Aerosols is a vital problem in current environmental research due to its importance in atmospheric optics, energetics, radiative transfer studies, chemistry, climate, biology and public health. Aerosols can influence the energy balance of the terrestrial atmosphere, the hydrological cycle, atmospheric dynamics and monsoon circulations. Because of the heterogeneous aerosol field with large spatial and temporal variability and reduction in uncertainties in aerosol quantification is a challenging task in atmospheric sciences. Keeping this in view the present study aims to assess the impact of aerosols on coastal Indian station Visakhapatnam and the adjoining Bay of Bengal. An aerosol is a colloid of fine solid particles or liquid droplets, in air or another gas. Aerosols can be natural or not. Examples of natural aerosols are fog, forest exudates and geyser steam.

Author: Jack G Calvert
Publisher: Oxford University Press
ISBN: 0199710880
Category : Science
Languages : en
Pages : 1005

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An international team of eminent atmospheric scientists have prepared Mechanisms of Atmospheric Oxidation of the Alkanes as an authoritative source of information on the role of alkanes in the chemistry of the atmosphere. The book includes the properties of the alkanes and haloalkanes, as well as a comprehensive review and evaluation of the existing literature on the atmospheric chemistry of the alkanes and their major atmospheric oxidation products, and the various approaches now used to model the alkane atmospheric chemistry. Comprehensive coverage is given of both the unsubstituted alkanes and the many haloalkanes. All the existing quality measurements of the rate coefficients for the reactions of OH, Cl, O(3P), NO3, and O3 with the alkanes, the haloalkanes, and their major oxidation products have been reviewed and evaluated. The expert authors then give recommendations of the most reliable kinetic data. They also review the extensive literature on the mechanisms and rates and modes of photodecomposition of the haloalkanes and the products of atmospheric oxidation of the alkanes and the haloalkanes, and make recommendations for future use by atmospheric scientists. The evaluations presented allow an extrapolation of the existing kinetic and photochemical data to those alkanes and haloalkanes that are as yet unstudied. The current book should be of special interest and value to the modelers of atmospheric chemistry as a useful input for development of realistic modules designed to simulate the atmospheric chemistry of the alkanes, their major oxidation products, and their influence on ozone and other trace gases within the troposphere.

Author: Anne E. Osbourn
Publisher: Springer Science & Business Media
ISBN: 0387854983
Category : Science
Languages : en
Pages : 588

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Plants produce a huge array of natural products (secondary metabolites). These compounds have important ecological functions, providing protection against attack by herbivores and microbes and serving as attractants for pollinators and seed-dispersing agents. They may also contribute to competition and invasiveness by suppressing the growth of neighboring plant species (a phenomenon known as allelopathy). Humans exploit natural products as sources of drugs, flavoring agents, fragrances and for a wide range of other applications. Rapid progress has been made in recent years in understanding natural product synthesis, regulation and function and the evolution of metabolic diversity. It is timely to bring this information together with contemporary advances in chemistry, plant biology, ecology, agronomy and human health to provide a comprehensive guide to plant-derived natural products. Plant-derived natural products: synthesis, function and application provides an informative and accessible overview of the different facets of the field, ranging from an introduction to the different classes of natural products through developments in natural product chemistry and biology to ecological interactions and the significance of plant-derived natural products for humans. In the final section of the book a series of chapters on new trends covers metabolic engineering, genome-wide approaches, the metabolic consequences of genetic modification, developments in traditional medicines and nutraceuticals, natural products as leads for drug discovery and novel non-food crops.

Author: Donald Mackay
Publisher: CRC Press
ISBN: 9781566706872
Category : Science
Languages : en
Pages : 1000

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Transport and transformation processes are key for determining how humans and other organisms are exposed to chemicals. These processes are largely controlled by the chemicals’ physical-chemical properties. This new edition of the Handbook of Physical-Chemical Properties and Environmental Fate for Organic Chemicals is a comprehensive series in four volumes that serves as a reference source for environmentally relevant physical-chemical property data of numerous groups of chemical substances. The handbook contains physical-chemical property data from peer-reviewed journals and other valuable sources on over 1200 chemicals of environmental concern. The handbook contains new data on the temperature dependence of selected physical-chemical properties, which allows scientists and engineers to perform better chemical assessments for climatic conditions outside the 20–25-degree range for which property values are generally reported. This second edition of the Handbook of Physical-Chemical Properties and Environmental Fate for Organic Chemicals is an essential reference for university libraries, regulatory agencies, consultants, and industry professionals, particularly those concerned with chemical synthesis, emissions, fate, persistence, long-range transport, bioaccumulation, exposure, and biological effects of chemicals in the environment. This resource is also available on CD-ROM

Author: Ruth Signorell
Publisher: CRC Press
ISBN: 142008562X
Category : Nature
Languages : en
Pages : 513

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Helping you better understand the processes, instruments, and methods of aerosol spectroscopy, Fundamentals and Applications in Aerosol Spectroscopy provides an overview of the state of the art in this rapidly developing field. It covers fundamental aspects of aerosol spectroscopy, applications to atmospherically and astronomically relevant problem