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Author: Shang Liu (earth scientist.)
Publisher:
ISBN: 9781267621498
Category :
Languages : en
Pages : 234
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Book Description
Secondary organic aerosols (SOA), known to form in the atmosphere, are a poorly understood but important component of atmospheric fine particles. This study aims to improve the understanding of the composition, source, and formation mechanism of SOA. Ambient particles were measured at urban centers (Mexico City, Mexico; Bakersfield, US), urban pollution-influenced coastal area (San Diego, US), high-elevation (4010 m) site (Altzomoni; 60 km southeast of Mexico City), and onboard the NCAR C130 flight (over Mexico and the coast of the Gulf of Mexico). Ensemble- and single-particle functional group and mass spectral compositions were analyzed using complementary techniques, mainly including Fourier transform infrared spectroscopy (FTIR), high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) coupled with a light scattering module, and scanning transmission X-ray microscopy combined with near-edge X-ray absorption fine structure (STXM-NEXAFS). The organic mass was found to be dominated by alkane, carboxylic acid, hydroxyl, and nonacid carbonyl groups. By applying factor analysis independently to the FTIR- and AMS-measured organic mass, a variety of sources was consistently identified in the urban plumes, with fossil fuel combustion emission accounting for 60- 90% of the organic mass. Volatile organic compounds emitted by the sources underwent fast oxidation. As a result, SOA contributed to 60- 90% of the organic mass, even in regions close to the sources. The SOA components formed from different precursor hydrocarbons were distinguished, with their mass fraction, diurnal cycle, size, and likely formation pathway discussed. The field studies were facilitated by laboratory reaction chamber studies focusing on organonitrate (ON) groups, which are potentially important photochemical products. It was found that ON groups hydrolyze in aerosol water at a rate of 4 day−1 (corresponds to a lifetime of 6 hours) when relative humidity exceeds 20%, which could explain the lower concentration of ON groups in aerosol particles than model prediction. Overall, the combined field and laboratory studies demonstrate that SOA formation is a dynamic and multivariate process; more work is needed to characterize SOA for quantitative and predictive understanding of the impacts of aerosols.
Author: Shang Liu (earth scientist.)
Publisher:
ISBN: 9781267621498
Category :
Languages : en
Pages : 234
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Book Description
Secondary organic aerosols (SOA), known to form in the atmosphere, are a poorly understood but important component of atmospheric fine particles. This study aims to improve the understanding of the composition, source, and formation mechanism of SOA. Ambient particles were measured at urban centers (Mexico City, Mexico; Bakersfield, US), urban pollution-influenced coastal area (San Diego, US), high-elevation (4010 m) site (Altzomoni; 60 km southeast of Mexico City), and onboard the NCAR C130 flight (over Mexico and the coast of the Gulf of Mexico). Ensemble- and single-particle functional group and mass spectral compositions were analyzed using complementary techniques, mainly including Fourier transform infrared spectroscopy (FTIR), high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) coupled with a light scattering module, and scanning transmission X-ray microscopy combined with near-edge X-ray absorption fine structure (STXM-NEXAFS). The organic mass was found to be dominated by alkane, carboxylic acid, hydroxyl, and nonacid carbonyl groups. By applying factor analysis independently to the FTIR- and AMS-measured organic mass, a variety of sources was consistently identified in the urban plumes, with fossil fuel combustion emission accounting for 60- 90% of the organic mass. Volatile organic compounds emitted by the sources underwent fast oxidation. As a result, SOA contributed to 60- 90% of the organic mass, even in regions close to the sources. The SOA components formed from different precursor hydrocarbons were distinguished, with their mass fraction, diurnal cycle, size, and likely formation pathway discussed. The field studies were facilitated by laboratory reaction chamber studies focusing on organonitrate (ON) groups, which are potentially important photochemical products. It was found that ON groups hydrolyze in aerosol water at a rate of 4 day−1 (corresponds to a lifetime of 6 hours) when relative humidity exceeds 20%, which could explain the lower concentration of ON groups in aerosol particles than model prediction. Overall, the combined field and laboratory studies demonstrate that SOA formation is a dynamic and multivariate process; more work is needed to characterize SOA for quantitative and predictive understanding of the impacts of aerosols.
Author: Ian Colbeck
Publisher: John Wiley & Sons
ISBN: 1405139196
Category : Science
Languages : en
Pages : 276
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Book Description
Aerosol particles are ubiquitous in the Earth’s atmosphere and are central to many environmental issues such as climate change, stratospheric ozone depletion and air quality. In urban environments, aerosol particles can affect human health through their inhalation. Atmospheric aerosols originate from naturally occurring processes, such as volcanic emissions, sea spray and mineral dust emissions, or from anthropogenic activity such as industry and combustion processes. Aerosols present pathways for reactions, transport, and deposition that would not occur in the gas phase alone. Understanding the ways in which aerosols behave, evolve, and exert these effects requires knowledge of their formation and removal mechanism, transport processes, as well as their physical and chemical characteristics. Motivated by climate change and adverse health effects of traffic-related air pollution, aerosol research has intensified over the past couple of decades, and recent scientific advances offer an improved understanding of the mechanisms and factors controlling the chemistry of atmospheric aerosols. Environmental Chemistry of Aerosols brings together the current state of knowledge of aerosol chemistry, with chapters written by international leaders in the field. It will serve as an authoritative and practical reference for scientists studying the Earth’s atmosphere and as an educational and training resource for both postgraduate students and professional atmospheric scientists.
Author: Yinping Zhang
Publisher: Springer Nature
ISBN: 9811676801
Category : Science
Languages : en
Pages : 2182
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Book Description
People live in indoor environment about 90% of lifetime and an adult inhales about 15 kg air each day, over 75% of the human body’s daily mass intake (air, food, water). Therefore, indoor air quality (IAQ) is very important to human health. This book provides the basic knowledge of IAQ and highlights the research achievements in the past two decades. It covers the following 12 sections: introduction, indoor air chemicals, indoor air particles, measurement and evaluation, source/sink characteristics, indoor chemistry, human exposure to indoor pollutants, health effects and health risk assessment, IAQ and cognitive performance, standards and guidelines, IAQ control, and air quality in various indoor environments. It provides a combination of an introduction to various aspects on IAQ studies, the current state-of-knowledge, various advances and the perspective of IAQ studies. It will be very helpful for the researchers and technicians in the IAQ and the related fields. It is also useful for experts in other fields and general readers who want to obtain a basic understanding of and research advances in the field of IAQ. A group of experts in IAQ research have been recruited to write the chapters. Their research interests and experience cover the scope of the book. In addition, some experienced experts in IAQ field have been invited as advisors or reviewers to give their comments, suggestions and revisions on the handbook framework and the chapter details. Their contribution guarantees the quality of the book. We are very grateful to them. Last but not least, we express our heartfelt thanks to Prof. Spengler, Harvard University, for writing the foreword of the current Handbook of Indoor Air Quality both as a pioneer scientist who contributed greatly to indoor air science and as an Editor-in-chief of Handbook of Indoor Air Quality 2001, 1st ed. New York: McGraw-Hill. In addition to hard copies, the book is also published online and will be updated by the authors as needed to keep it aligned with current knowledge. These salient features can make the handbook fresh with the research development.
Author: Rachel Elizabeth Sellon
Publisher:
ISBN:
Category :
Languages : en
Pages : 274
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Book Description
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.
Author: Yue Zhang
Publisher: American Chemical Society
ISBN: 0841299293
Category : Science
Languages : en
Pages : 176
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Book Description
The uncertainties in the aerosol effects on radiative forcing limit our knowledge of climate change, presenting us with an important research challenge. Aerosols in Atmospheric Chemistry introduces basic concepts about the characterization, formation, and impacts of ambient aerosol particles as an introduction to graduate students new to the field. Each chapter also provides an up-to-date synopsis of the latest knowledge of aerosol particles in atmospheric chemistry.
Author: Regina M. B. O. Duarte
Publisher: MDPI
ISBN: 3039439316
Category : Science
Languages : en
Pages : 146
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Book Description
The challenges faced by the atmospheric research community today are vast, complex, and multi-faceted. The book Urban Atmospheric Aerosols: Sources, Analysis, and Effects highlights important aspects concerning the chemical and optical properties, size distribution, sources, and potential health effects of fine urban air particles (PM2.5). The physical and chemical characterization of PM2.5, its source assignment, and the assessment of the magnitude and distribution of its emissions are crucial for establishing effective fine air particle regulations and assessing the associated risks to human health. This book brings together eight papers covering the main topics of the field and will be of interest to researchers who are interested in air quality in outdoor and indoor environments, air particle toxicity, and atmospheric chemistry, as well as global climate modelers.
Author: Xiaolu Zhang
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages :
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Book Description
900 archived FRM filters from 15 sites over the southeast during 2007 were analyzed for PM2.5 chemical composition and physical properties. Secondary components (i.e. sulfate aerosol and SOA) were the major contributors to the PM2.5 mass over the southeast, whereas the contribution from biomass burning varied with season and was negligible (2%) during summer. Excluding biomass burning influence, FRM WSOC was spatially homogeneous throughout the region, similar to sulfate, yet WSOC was moderately enhanced in locations of greater predicted isoprene emissions in summer. On smaller spatial scale, a substantial urban/rural gradient of WSOC was found through comparisons of online WSOC measurements at one urban/rural pair (Atlanta/Yorkville) in August 2008, indicating important contribution from anthropogenic emissions. A comparative study between Atlanta and LA reveals a number of contrasting features between two cities. WSOC gas-particle partitioning, investigated through the fraction of total WSOC in the particle phase, Fp, exhibited differing relationships with ambient RH and organic aerosols. In Atlanta, both particle water and organic aerosol (OA) can serve as an absorbing phase. In contrast, in LA the aerosol water was not an important absorbing phase, instead, Fp was correlated with OA mass. Fresh LA WSOC had a consistent brown color and a bulk absorption per soluble carbon mass at 365 nm that was 4 to 6 times higher than freshly-formed Atlanta soluble organic carbon. Interpreting soluble brown carbon as a property of freshly-formed anthropogenic SOA, the difference in absorption per carbon mass between the two cities suggests most WSOC formed within Atlanta is not from an anthropogenic process similar to LA.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 25
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Book Description
Author: Marissa A. Miracolo
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Author: Claudio Tomasi
Publisher: John Wiley & Sons
ISBN: 3527336451
Category : Science
Languages : en
Pages : 706
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Book Description
Ein Blick auf die morphologischen, physikalischen und chemischen Eigenschaften von Aerosolen aus den unterschiedlichsten natürlichen und anthropogenen Quellen trägt zum besseren Verständnis der Rolle bei, die Aerosolpartikel bei der Streuung und Absorption kurz- und langwelliger Strahlung spielen. Dieses Fachbuch bietet Informationen, die sonst schwer zu finden sind, und vermittelt ausführlich die Kenntnisse, die erforderlich sind, um die mikrophysikalischen, chemischen und Strahlungsparameter zu charakterisieren, die bei der Wechselwirkung von Sonnen- und Erdstrahlen so überaus wichtig sind. Besonderes Augenmerk liegt auf den indirekten Auswirkungen von Aerosolen auf das Klima im Rahmen des komplexen Systems aus Aerosolen, Wolken und der Atmosphäre. Auch geht es vorrangig um die Wirkungen natürlicher und anthropogener Aerosole auf die Luftqualität und die Umwelt, auf die menschliche Gesundheit und unser kulturelles Erbe. Mit einem durchgängig lösungsorientierten Ansatz werden nicht nur die Probleme und Gefahren dieser Aerosole behandelt, sondern auch praktikable Lösungswege aufgezeigt.
