Author: Kimberly A. Prather
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 102

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Author: Kimberly A. Prather
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 100

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Author: Don-Yuan Liu
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 608

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Author: David Philip Fergenson
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 302

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Author: Andrew Phillip Ault
Publisher:
ISBN: 9781124201214
Category :
Languages : en
Pages : 558

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Book Description
Atmospheric aerosols have a significant impact on human health and climate, yet the full scope of these influences are only beginning to be discovered and characterized. To understand these impacts, detailed in-situ measurements of the physical, chemical, and optical properties of aerosols are necessary. Aerosol time-of-flight mass spectrometry (ATOFMS) provides the ability to measure chemical, physical, and optical properties of single particles in real-time. This dissertation uses ATOFMS to explore both the properties and evolution of particles as they are transported over local to global distances. The results of numerous field studies are utilized to explore the changes to these particles as they travel through the atmosphere from their source to eventual deposition. Local to regional scale transport of particles was observed from a number of perspectives in this dissertation. Particles regionally transported from the Ports of Los Angeles and Long Beach to San Diego were identified chemically as ship and truck emissions and shown to overwhelm local sources during peak transport conditions. Ship emissions were studied in detail at the Port of Los Angeles by characterizing individual ship plumes at a site adjacent to the main channel. Mobile laboratory measurements demonstrated the variation in particle concentrations and composition on a local-to-regional level. On the intercontinental-to-global scale, Asian dust was observed in precipitation samples collected in the Sierra Nevada Mountains during orographic precipitation. The incorporation of the long range-transported dust might enhance precipitation, which may alter California's precipitation patterns and water supply. The outflow of particles from Asia to North America were measured on a remote island off Korea, and the sources and aging of particles in Chinese urban, Chinese dust, and Korean air masses were compared to marine air masses. Lastly, ATOFMS studies from sites across North America, Asia, Europe, and Africa were compared to determine similarities and differences in size-resolved chemical mixing state of particles across numerous types of sampling sites, with the objective being to provide information for global climate models to more accurately represent particles. Taken together these results provide an increased understanding of particle chemistry and transport on the scale of meters-to-continents.

Author: Kimberly Louise Salt
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 504

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Author: Philip Joseph Silva
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 904

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Author: John Francis Cahill
Publisher:
ISBN: 9781321232462
Category :
Languages : en
Pages : 419

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Book Description
In the environment, aerosol particles can affect climate directly though scattering and absorbing radiation and indirectly by influencing cloud formation, albedo, and lifetime. Beyond the environment, aerosols are commonly used as a delivery mechanism for a variety of products, such as inhalers and spray paints. Chemically characterizing aerosols is a difficult endeavor, and relatively few instrumental methods are capable of doing so. A unique subset of instrumentation and techniques exist to measure aerosol chemical and physical properties. Among these, the aerosol time-of-flight mass spectrometer (ATOFMS) can measure single particle chemistry and size in real time. The ATOFMS was developed for the study atmospheric aerosols, and data acquired by the ATOFMS over the years since its creation has provided significant insight into many atmospheric phenomena; however, the application of this technique into disciplines other than atmospheric chemistry has been relatively unexplored. In this dissertation the ATOFMS is used in a conventional sense, to provide insight into atmospheric particle chemistry through two field studies in California, but also in an unconventional way by using the ATOFMS to answer outstanding questions in other disciplines, including nanomaterials and biochemistry. Often the chemistry of a single unit, rather than of the bulk, is needed in these disciplines, and the ATOFMS is uniquely suited to provide this information. The ATOFMS was used to chemically characterize single particles of a unique class of nanomaterials, called metal organic frameworks (MOFs), comprised of functionalized organic linkers and metal ions or metal ion clusters. ATOFMS data was able to show the presence of MOFs with mixed functionality, and show the exchange of functional groups between materials. Cell processes can be monitored by measuring small molecules that are part of cell metabolism, which can provide insight into cell functions, environment, and disease. Using an ATOFMS with a modified aerodynamic lens inlet, single microalgae cells 4-10 μm in diameter of various types have been be characterized. Compared to other single cell mass spectrometry techniques, the modified ATOFMS has unprecedented throughput, up to 50 Hz. Time-resolved measurements of cells undergoing nitrogen deprivation further highlight the abilities of the technique for single cell analysis.

Author: Jonathan O. Allen
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 190

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Author: Lindsay Erighn Hatch
Publisher:
ISBN: 9781267646781
Category :
Languages : en
Pages : 172

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Aerosol particles are ubiquitous in the atmosphere and induce significant impacts on human health and climate that depend on their physical and chemical properties, such as size, composition, and mixing state (chemical associations). Measurements of aerosol composition at the single-particle level are necessary to better understand these effects. Aerosol time-of-flight mass spectrometry (ATOFMS) is able to monitor the size and chemical composition of individual particles in real time. In this doctoral research, ATOFMS analysis was extended to identify new mass spectral markers and improve the potential for quantitative measurements. Development of novel instrumentation was also undertaken. Ion markers indicative of organosulfate compounds were identified in ATOFMS mass spectra collected in Atlanta, GA. In this study, the mixing state and temporal behavior of particulate organosulfate compounds were observed for the first time. Organosulfates were overwhelmingly detected in carbonaceous submicron particles and the temporal trends indicated that they likely formed by the daytime oxidation of isoprene followed by aqueous reaction with sulfate overnight. These results highlight the roles of mixing state and multi-phase reactivity on the formation of secondary organic aerosols. ATOFMS measurements of thermally-conditioned aerosol residuals obtained during the 2005 Study of Organic Aerosols in Riverside, CA were analyzed to determine the impacts of atmospheric aging on the laser desorption/ionization process. Coatings of secondary species suppressed the ionization efficiency, thereby impacting the mass spectral peak areas; however, a novel analysis method was found to correct these artifacts and produced strong agreement with collocated quantitative instrumentation. This new analysis technique was then applied to investigate the mixing-state dependence of aerosol volatility observed in Riverside. It was observed that particulate nitrate evaporated at different temperatures from different particle types (e.g., organic vs. biomass burning), which may influence the regional transport of nitrate species. ATOFMS provides important insights into size-resolved particle sources; however it heavily fragments most organic species, resulting in loss of the molecular information. Therefore, a novel chemical ionization mass spectrometer was developed to better characterize the molecular organic aerosol constituents. In particular, an ion funnel was incorporated into a home-built proton-transfer-reaction mass spectrometer. Initial characterization studies and ion simulations indicated that the ion funnel can provide high-efficiency ion transfer from the ionization region to the mass spectrometer. These results demonstrate the potential for this instrument to ultimately achieve highly sensitive analyses of organic aerosols.