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1
Davidson, Nicholas Mark. "Atmospheric processing of aerosols." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8298/.
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The chemistry of aerosol particles is critical to the influence said particles have over human health, air quality and the distribution of nutrients across the world. Current models estimate that windborne dust represents the movement of thousands of teragrams of solid material of varying composition and solubility across continents and into the world’s oceans. Understanding the composition and surface reactivity of anthropogenic particles from industry, agriculture and vehicle emissions is vital to understanding their potential impact on the world, and the structure and behaviour of inhalable pharmaceuticals is a strong determinant of their efficacy. The following work examines a broad selection of natural and anthropogenic particulate samples with synchrotron-based techniques, including analysis of ship emissions collected directly from stacks for the first time. The effect of simulated atmospheric acid processing on the solubility of iron on coal fly ash is evaluated, and optical trapping is used in conjunction with analytical techniques to observe the influence of relative humidity on the properties of pharmaceutical aerosols and aqueous droplets containing fluorescent protein solutions.
2
Ju, Dehao. "Experimental and numerical research on pharmaceutical aerosols." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/348916/.
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With the background of health issues regarding the consumption of tobacco, the widespread availability of safer nicotine products and a harm reduction policy is encouraged. A cigarette alternative is designed to deliver a dose of medicinal nicotine within a timeframe comparable to that of a cigarette, and gives much of what smokers expect from a cigarette without the risks of smoking tobacco. The general purpose of this Ph.D. project is to study the process of flashing atomization and dispersion, with a view to supporting the development of a cigarette replacement device. In order to test the effectiveness of the nicotine formulations, the analysis is carried out sizing the droplets of the aerosols at the position where human oropharynx locates, to support the further research on the deposition of droplets in the human respiratory tract. A mechanical lung has been assembled and programmed to trigger the ‘cigarette-like’ devices with different inhalation profiles, and a dual laser system has been designed to measure the global actuation flow characteristics (e.g. spray velocity and opacity). In order to efficiently acquire sufficient droplet information (e.g. diameter and aspect ratio) from images of in and out of focus droplets, a multi-threshold algorithm is developed and successfully implemented in the automatic particle/droplet image analysis (PDIA) system. It increases the depth of field (DoF) of small particles with diameters smaller than 50μm, and it performs more efficiently than the dual threshold methods which are widely used in the commercial software. A numerical multi-component two-phase actuation flow model has been developed, in order to test different formulations within various flow domains of the cigarette replacement devices. The simulated results of the numerical model have been validated with the experimental measurements and the results of previous researchers. In order to acquire an aerosol with relatively low and steady mass flow rate of nicotine, it is recommended that the mass fraction of propellant (HFA 134a) should be kept around 75%~90% to avoid the sharp temperature drop causing the sensation of freezing. The actuator nozzle diameter should be 0.2mm~0.3mm to produce a flow with relatively low mass flow rate. Furthermore the numerical model is capable of predicting the residual mass median diameter (MMD) of the spray, by using evaporation model of multicomponent liquid droplets, to quantify the sprays. Two different formulations with 95% and 98% mass fraction of HFA 134a, and two prototype cigarette alternatives with different expansion chamber volumes, have been analyzed by the numerical model and compared with the dual laser measurements. In addition, it considers the spray character by high speed imaging, with the special interest in the flashing phenomena and droplet sizes. It concludes that a larger expansion chamber volume enhances the propellant evaporation, recirculation, bubble generation and growth inside the chamber, and it made a significant improvement to produce finer sprays. Although the formulation with 98% of HFA 134a can generate smaller droplets, the formulation with 95% of HFA 134a produces more steady puffs with relatively low mass flow rate.
3
Hennigan, Christopher James. "Properties of secondary organic aerosol in the ambient atmosphere sources, formation, and partitioning /." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26598.
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Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2009.<br>Committee Chair: Weber, Rodney; Committee Co-Chair: Bergin, Michael; Committee Member: Mulholland, James; Committee Member: Nenes, Athanasios; Committee Member: Russell, Armistead. Part of the SMARTech Electronic Thesis and Dissertation Collection.
4
Altman, Igor, and n/a. "Peculiarities of Nanoparticle Formation and Implications to Generation of Environmental Aerosols." Griffith University. School of Environmental Engineering, 2005. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20051111.122816.
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This Thesis considers peculiarities of nanoparticle formation from the gas in different systems. The main role of the surface condensation in the nanoparticle growth in metal flames was established through a series of experiments and was described by the developed model. The stagnation of the post-nucleation nanoparticle growth was experimentally revealed and theoretically explained. The influence of generation conditions on the post-processing nanoparticle properties was examined. The non-isothermal approach to correct the homogeneous nucleation theory was developed. The results of this work can be summarized in 3 categories: (1) Nanoparticle formation in metal flames. In this work, it was demonstrated that the surface condensation is a main process responsible for nanooxides growth during metal combustion. It was shown that the rate of this condensation growth is consistent with the exponential law, which could lead to the formation of the lognormal particle size distribution in the system, where the Brownian coagulation is suppressed. The post-nucleation stagnation of the nanoparticle growth was found. The particle overheating was suggested as a cause of the growth stagnation. The found stagnation leads to the accumulation of the supercritical clusters in the system generating nanoparticles. The role of these supercritical clusters in the nanoparticle agglomeration was considered. (2) Study of properties of nanoparticles generated in different metal flames. The light absorption, photoluminescence and magnetic properties of nanoparticles produced in different metal flames were examined. The significant broadening of the absorption edge was found in nanooxides produced by direct metal combustion. This broadening allowed one to excite the unforeseen photoluminescence from these nanoparticles. The significant light absorption in the visible light found in the titania particles produced by metal combustion allows one to consider these particles as a prospective photocatalyst. The unusual optical properties revealed were related to the extreme conditions of the nanoparticle formation, namely, to high energy release (about 5 eV per condensing molecule). The stabilization of spinel structure was found in iron oxide particles synthesized by iron combustion. It allowed one to produce nanoparticles with magnetization close to the high-limit value of the bulk. (3) Approach to correct the homogeneous nucleation theory. The existing homogeneous nucleation theory implies that nucleation occurs at isothermal conditions, i.e. subcritical clusters have the same temperature as the ambient gas does. However, the theory overestimates the actual nucleation rate and underestimates the critical cluster size. It is understandable that due to release of the latent heat of condensation, the cluster temperature in the nucleating system should be higher than the environment temperature. In this work, it was suggested the method to account for the cluster overheating during nucleation. It was demonstrated that the consistent description of the detailed balance in the nucleating system may allow one to evaluate magnitudes of overestimation of the actual nucleation rate and underestimation of the number of molecules in the critical cluster, usually obtained by the isothermal nucleation theory. The numerical estimates are in good agreement with the wellknown experimental results. The implications of the results to generation of atmospheric aerosols were discussed.
5
Yu, Hongbin. "Radiative effects of aerosols on the environment in China." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/25746.
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Gross, Benjamin. "Lithogenic, Marine and Anthropogenic Aerosols in an Ice Core from the Saint Elias Mountains, Yukon, Canada: Lead-Aerosol Provenance and Seasonal Variability." Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/GrossB2008.pdf.
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Woo, Chunho Anthony, and 鄔俊豪. "Molecular ecology and public health risks of urban bio-aerosols." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B49617680.
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The Earth’s atmosphere supports microorganisms and they include potential pathogens and microbial allergens. Whilst indoor environments have been well studied, relatively little is known of bio-aerosols in outdoor locations and their potential influence on human health, particularly with regard to urban development. Hong Kong provides an ideal model system for testing hypotheses related to the impact of urbanization on bio-aerosols, with a well-defined gradient of urbanization and large population. This thesis describes work to establish the biodiversity and spatio-temporal dynamics of outdoor bio-aerosols in Hong Kong. A comprehensive study of multi-domain microbial diversity and allergen levels in urban aerosols over a contiguous annual timescale and along a gradient of urbanization was carried out. A comprehensive suite of climatic and pollutant variables were also recorded during the sampling interval. Terminal restriction fragment length polymorphism (T-RFLP) was employed to investigate variations in bacterial and eukaryal assemblages, followed by phylogenetic assessment using high-throughput sequencing. The results revealed a strong seasonality in both bacterial and eukaryal assemblages, with Archaea forming a negligible part of the urban bio-aerosols. The most abundant bacteria were proteobacteria but community shifts were seen due to increases in algae in summer, and betaproteobacteria and cyanobacteria in winter. This was most parsimoniously explained by considering the backward trajectory analysis of air mass. A greater abundance of marine-associated phylotypes such as Bacillariophyta and Chlorophyta were identified when the dominant air mass arriving in Hong Kong in the summer originated from oceanic sources. In contrast, betaproteobacteria, which indicated soil sources were prevalent when the origin of air mass was from terrestrial sources. A trend in fungal phylotypes was also apparent, with summer samples dominated by basidiomycetous Agaricales, and winter samples by the ascomycete genus Cladosporium. This was likely due to favourable climatic conditions during wetter summer months enhancing release of fungal basidiospores. A range of airborne human pathogens was also detectable at low levels including pathogenic bacteria such as Acinetobacter baumannii, Clostridium perfringens, Escherichia coli O157:H7, and Ricinus communis, and the pathogenic fungus Aspergillus terreus. Microbial allergens including bacterial endotoxins and fungal glucans were also quantified with immunological assays. These generally followed variations in biomass, and during some months were recorded at levels that may impact human health upon chronic exposure. Carbon dioxide levels were the only climatic or pollutant variable that correlated with allergen levels. Conversely changes in microbial assemblages were strongly correlated to several climatic variables including temperature, rainfall, air pressure and relative humidity, but not with the degree of urbanization or airborne pollutants. This study highlights the importance of including microbial assessments in future bio-surveillance of urban aerosols.<br>published_or_final_version<br>Biological Sciences<br>Doctoral<br>Doctor of Philosophy
8
Holmes, Jennifer L. "Radioanalytical techniques applied to environmental chemistry : a two case study /." Thesis, Connect to this title online; UW restricted, 1993. http://hdl.handle.net/1773/8527.
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Koolik, Libby (Libby P. ). "The phase separation inlet for droplets, ice residuals, and interstitial aerosols." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/115782.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2018.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 39-43).<br>A new inlet for studying the composition of mixed-phase clouds - the phaSe seParation Inlet for Droplets icE residuals and inteRstitial aerosols (SPIDER) - is described. SPIDER combines an omni-directional inlet, a Large-Pumped Counterflow Virtual Impactor (L-PCVI), a flow tube as evaporation chamber, and a Pumped Counterflow Virtual Impactor (PCVI) to separate droplets, ice crystals, and interstitial aerosols for simultaneous sampling. Verification tests of each individual component of SPIDER were positive, as was the result of investigating that the components work together as a whole setup without flow blockage or choking. SPIDER was installed at Mt. Washington Observatory (MWO), a mountain top research facility in the White Mountains, for a two-week field campaign. There, SPIDER showed promising performance as a field instrument and provided first data that suggest its capability of separating distinct cloud particles. Future design improvements of SPIDER are suggested along with potential locations for field measurements.<br>by Libby Koolik.<br>M. Eng.
10
Gao, Shuang. "Performance of Filtering Facepieces and Powered Air-purifying Respirators Challenged with Different Aerosols." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1459155521.
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Wang, Xuan Ph D. Massachusetts Institute of Technology. "Exploring the absorption properties and direct radiative impact of atmospheric carbonaceous aerosols." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113493.
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Thesis: Ph. D. in Environmental Chemistry, Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2017.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 125-141).<br>Atmospheric aerosols are important due to their adverse effects on human health and their direct and indirect radiative effects on climate, which are significant and very uncertain factors contributing to global climate change. In estimating the direct radiative effect (DRE), the absorption from carbonaceous aerosols, including black carbon (BC) and brown carbon (BrC, a component of organic aerosol, OA), are highly uncertain. This thesis addresses this uncertainty by combining models and observations to better constrain the optical properties and radiative impact of carbonaceous aerosols. First, a global model simulation (GEOS-Chem) of BC is expanded to separately treat both the aging and physical properties of BC from different sources. By combining model and observations, the global BC lifetime is found to be overestimated in previous investigations, leading to higher estimates of its warming potential. The DRE of BC is estimated to be less than one quarter of the previously reported value. Second, a new method is developed to derive BrC absorption from measurements and used to identify BrC from total absorption observations. The absorption efficiency of BrC is found to be positively correlated with the emitted BC/OA mass ratio, which is related to combustion conditions. In addition, measured BrC absorption from biomass burning plumes is found to decrease with photochemical aging with a lifetime of one day. Third, a global model simulation of BrC is developed and tested against BrC absorption measurements from aircraft campaigns in the continental United States. The BrC absorption properties from biomass burning estimated based on laboratory measurements are found to overestimate the direct measurements of ambient BrC absorption. In addition, applying a photochemical aging scheme for BrC improves the model skill. The simulation suggests that the DRE of BrC has been overestimated previously due to the lack of observational constraints from direct measurements and omission of the effects of photochemical aging. Finally, the influence of mixing state on the global absorption of carbonaceous aerosols is estimated through simplified model experiments. This thesis suggests that policies for reducing emissions of carbonaceous aerosols may have a limited impact on mitigating global climate warming.<br>by Xuan Wang.<br>Ph. D. in Environmental Chemistry
12
Andronache, Constantin. "A study of aerosol interactions in aircraft wake and background atmosphere." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/26008.
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Zavvos, Konstantinos. "Collection And Pre-Concentration of Aerosol for Optical Spectroscopies." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1463130721.
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Csavina, Janae Lynn. "Metal and Metalloid Contaminants in Atmospheric Aerosols from Mining Operations." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/242386.
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Mining operations, including crushing, grinding, smelting, refining, and tailings management, are a significant source of airborne metal and metalloid contaminants such as As, Pb, Cd and other potentially toxic elements. Dust particles emitted from mining operations can accumulate in surrounding soils, natural waters and vegetation at relatively high concentrations through wind and water transport. Human exposure to the dust can occur through inhalation and, especially in the case of children, incidental dust ingestion, particularly during the early years when children are likely to exhibit pica. Furthermore, smelting operations release metals and metalloids in the form of fumes and ultra-fine particulate matter, which disperses more readily than coarser soil dusts. Of specific concern, these fine particulates can be transported to the lungs, allowing contaminants to be transferred into the blood stream. The main aim of this research is to assess the role of atmospheric aerosol and dust in the transport of metal and metalloid contaminants from mining operations to assess the deleterious impacts of these emissions to ecology and human health. In a field campaign, ambient particulates from five mining sites and four reference sites were examined utilizing micro-orifice deposit impactors (MOUDI), total suspended particulate (TSP) collectors, a scanning mobility particle sizer (SMPS), and Dusttrak optical particle counters for an understanding of the fate and transport of atmospheric aerosols. One of the major findings from size-resolved chemical characterization at three mining sites showed that the majority of the contaminant concentrations were found in the fine size fraction (<1 micrometer). Further, metal and metalloids (e.g. As, Cd, and Pb) around smelting activities are significantly enriched in both the coarse and fine size fraction when compared to reference sites. Additionally, with dust events being a growing concern because of predicted climate change and mine tailings being a significant source for dust, high wind conditions around mine tailings were studied for dust generation. Relative humidity was found to play an important predicting role in atmospheric dust concentration. More generally, findings indicate mining activities remain a serious threat to human health and ecology despite the regulations in place to protect from their pollution.
15
Thompson, Andrea Elizabeth. "Reactions of Bromide Ions with Atmospheric Trace Gases and Aerosols." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10447.
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I investigated the utility of Br- as a chemical ionization mass spectrometry (CIMS) reagent ion for the detection and measurement of both atmospheric trace gases and aerosol species. The primary goals of this study are to obtain fast, very sensitive measurements of nitrate and sulfate and to ascertain if gas phase PAN and HNO3 could be measured simultaneously with the same chemical ionization scheme. Gas-phase measurements of PAN and nitric acid were conducted and the sensitivities of these measurements to temperature and relative humidity were determined. The potential for measuring aerosol composition by CIMS was assessed by comparison with PILS (particle-into-liquid sampler) measurements.
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Chen, Zhong. "Cutting fluid aerosol generation and dissipation in machining process : analysis for environmental consciousness." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/17929.
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Zheng, Lina. "Studies on the Elemental Measurement of Aerosols Using Microplasma Spectroscopy." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin147981742920461.
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Li, Hanyang. "Identification, Quantification, and Constraint of Uncertainties Associated with Atmospheric Black Carbon Aerosols." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu158533806705194.
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Thomas, Stephen Bradley. "Characterisation of ambient fine and ultrafine atmospheric aerosols." Thesis, Queensland University of Technology, 2001.
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Johnson, Graham Richard. "The Formation and Growth of Marine Aerosols and the Development of New Techniques for their In-situ Analysis." Thesis, Queensland University of Technology, 2005. https://eprints.qut.edu.au/16117/1/Graham_Johnson_Thesis.pdf.
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Marine aerosols have attracted increasing attention over the past 15 years because of
their potential significance for global climate modelling. The size distribution of these
aerosols extends from super-micrometer sea salt mode particles down through 150 nm
accumulation mode particles, 40 nm Aitken mode particles and nucleation mode
particles which extend from 25 nm right down to clusters of a few molecules. The
process by which the submicrometer modes form and grow and their composition
have remained topics of debate throughout this time in large part because of the
difficulties associated with determining their composition and relating it to proposed
models of the formation process.
The work compared the modality of marine aerosol influencing the South-east-Queensland region with that of other environmental aerosols in the region. The aerosol was found to be consistent with marine aerosols observed elsewhere with
concentrations below 1000 cm-3 and frequently exhibiting the distinct bimodal structure associated with cloud processing, consisting of an Aitken mode at approximately 40 nm, an accumulation mode in the range 100-200 nm and a coarse mode attributed to sea salt between 600 and 1200 nm.
This work included the development of two new techniques for aerosol research. The first technique measures aerosol density using a combination of aerosol size distribution and gravimetric mass concentration measurements. This technique was used to measure the density of a number of submicrometer aerosols including
laboratory generated NaCl aerosol and ambient aerosol. The densities for the laboratory generated aerosols were found to be similar to those for the bulk materials used to produce them. The technique, extended to super-micrometer particle size range may find application in ambient aerosol research where it could be used to discriminate between periods when the aerosol is dominated by NaCl and periods
when the density is more representative of crustal material or sulfates. The technique
may also prove useful in laboratory or industrial settings for investigating particle
density or in case where the composition is known, morphology and porosity.
The second technique developed, integrates the existing physicochemical techniques
of volatilisation and hygroscopic growth analysis to investigate particle composition
in terms of both the volatilisation temperatures of the chemical constituents and their
contribution to particle hygroscopic behaviour. The resulting volatilisation and humidification tandem differential mobility analyser or VH-TDMA, has proven to be a valuable research tool which is being used in ongoing research.
Findings of investigations relating the composition of the submicrometer marine
aerosol modes to candidate models for their formation are presented. Sea salt was not
found in the numerically dominant particle type in coastal nucleation mode or marine
Aitken and accumulation modes examined on the Southeast Queensland coast during
periods where back trajectories indicated marine origin. The work suggests that all
three submicrometer modes contain the same four volatile chemical species and an
insoluble non-volatile residue. The volatility and hygroscopic behaviours of the
particles are consistent with a composition consisting of a core composed of sulfuric
acid, ammonium sulfate and an iodine oxide coated with a volatile organic compound.
The volume fraction of the sulfuric acid like species in the particles shows a strong
dependence on particle size.
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Johnson, Graham Richard. "The Formation and Growth of Marine Aerosols and the Development of New Techniques for their In-situ Analysis." Queensland University of Technology, 2005. http://eprints.qut.edu.au/16117/.
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Marine aerosols have attracted increasing attention over the past 15 years because of their potential significance for global climate modelling. The size distribution of these aerosols extends from super-micrometer sea salt mode particles down through 150 nm accumulation mode particles, 40 nm Aitken mode particles and nucleation mode particles which extend from 25 nm right down to clusters of a few molecules. The process by which the submicrometer modes form and grow and their composition have remained topics of debate throughout this time in large part because of the difficulties associated with determining their composition and relating it to proposed models of the formation process. The work compared the modality of marine aerosol influencing the South-east-Queensland region with that of other environmental aerosols in the region. The aerosol was found to be consistent with marine aerosols observed elsewhere with concentrations below 1000 cm-3 and frequently exhibiting the distinct bimodal structure associated with cloud processing, consisting of an Aitken mode at approximately 40 nm, an accumulation mode in the range 100-200 nm and a coarse mode attributed to sea salt between 600 and 1200 nm. This work included the development of two new techniques for aerosol research. The first technique measures aerosol density using a combination of aerosol size distribution and gravimetric mass concentration measurements. This technique was used to measure the density of a number of submicrometer aerosols including laboratory generated NaCl aerosol and ambient aerosol. The densities for the laboratory generated aerosols were found to be similar to those for the bulk materials used to produce them. The technique, extended to super-micrometer particle size range may find application in ambient aerosol research where it could be used to discriminate between periods when the aerosol is dominated by NaCl and periods when the density is more representative of crustal material or sulfates. The technique may also prove useful in laboratory or industrial settings for investigating particle density or in case where the composition is known, morphology and porosity. The second technique developed, integrates the existing physicochemical techniques of volatilisation and hygroscopic growth analysis to investigate particle composition in terms of both the volatilisation temperatures of the chemical constituents and their contribution to particle hygroscopic behaviour. The resulting volatilisation and humidification tandem differential mobility analyser or VH-TDMA, has proven to be a valuable research tool which is being used in ongoing research. Findings of investigations relating the composition of the submicrometer marine aerosol modes to candidate models for their formation are presented. Sea salt was not found in the numerically dominant particle type in coastal nucleation mode or marine Aitken and accumulation modes examined on the Southeast Queensland coast during periods where back trajectories indicated marine origin. The work suggests that all three submicrometer modes contain the same four volatile chemical species and an insoluble non-volatile residue. The volatility and hygroscopic behaviours of the particles are consistent with a composition consisting of a core composed of sulfuric acid, ammonium sulfate and an iodine oxide coated with a volatile organic compound. The volume fraction of the sulfuric acid like species in the particles shows a strong dependence on particle size.
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Felix, Villar Omar Ignacio. "Metals And Metalloids In Atmospheric Dust: Use Of Lead Isotopic Analysis For Source Apportionment." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/338751.
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Mining activities generate aerosol in a wide range of sizes. Smelting activities produce mainly fine particles (<1 μm). On the other hand, milling, crushing and refining processes, as well tailings management, are significant sources of coarse particles (>1 μm). The adverse effects of aerosols on human health depend mainly on two key characteristics: size and chemical composition. One of the main objectives of this research is to analyze the size distribution of contaminants in aerosol produced by mining operations. For this purpose, a Micro-Orifice Uniform Deposit Impactor (MOUDI) was utilized. Results from the MOUDI samples show higher concentrations of the toxic elements like lead and arsenic in the fine fraction (<1 μm). Fine particles are more likely to be deposited in the deeper zones of the respiratory system; therefore, they are more dangerous than coarse particles that can be filtered out in the upper respiratory system. Unfortunately, knowing the total concentration of contaminants does not give us enough information to identify the source of contamination. For this reason, lead isotopes have been introduced as fingerprints for source apportionment. Each source of lead has specific isotopic ratios; by knowing these ratios sources can be identified. During this research, lead isotopic ratios were analyzed at different sites and for different aerosol sizes. From these analyses it can be concluded that lead isotopes are a powerful tool to identify sources of lead. Mitigation strategies could be developed if the source of contamination is well defined. Environmental conditions as wind speed, wind direction, relative humidity and precipitation have an important role in the concentration of atmospheric dust. Dry environments with low relative humidity are ideal for the transport of aerosols. Results obtained from this research show the relationship between dust concentrations and meteorological parameters. Dust concentrations are highly correlated with relative humidity and wind speed. With all the data collected on site and the analysis of the meteorological parameters, models can be develop to predict the transport of particles as well as the concentration of contaminants at a specific point. These models were developed and are part of the results shown in this dissertation.
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Marcella, Marc Pace. "Biosphere-atmosphere interactions over semi-arid regions : modeling the role of mineral aerosols and irrigation in the regional climate system." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/79490.
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Thesis (Ph. D. in the Field of Hydrometeorology)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, February 2013.<br>"February 2013." Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 263-282).<br>This dissertation describes the role of land surface processes in shaping semi-arid climates, namely those of Southwest Asia and Northwest Africa. The interactions between dust emissions, irrigation, and climate processes are studied and quantified using a regional climate model to perform a series of carefully designed numerical experiments. The performance of the numerical model is tested by comparing simulation results against observations from satellites and other standard platforms. Modeling results indicate significant improvements in simulating mineral aerosols over Southwest Asia. Results suggest that including representations for sub-grid scale wind gustiness as well as mineral aerosols at the boundaries, improve the model skill in simulating the spatial distribution and magnitude of suspended dust. Over Southwest Asia, a large bias in original simulations of surface temperature is eliminated by improving surface albedo, and including mineral aerosols and irrigation. These modifications reduced other biases associated with simulated surface shortwave incident radiation, surface absorbed radiation, and surface vapor pressure. As a result of these improvements, the model now successfully reproduces the climate of Southwest Asia. Another set of numerical experiments is performed over West Africa focusing on the same processes of dust emissions and irrigation. Over the Sahel region, it is found that both mineral aerosols and irrigation have similar effects on the surrounding climate: cooling of surface temperature, increased surface humidity, but no change in rainfall. With dust, a shallower boundary layer redistributes moisture closer to the surface thus offsetting negative temperature effects on the boundary layer moist static energy. With irrigation, a large reduction of the boundary layer height results in less triggering of convective activity and hence mitigates any increase in convective rainfall efficiency due to irrigation. Lastly, a numerical simulation over West Africa that includes simultaneous representations of dust emissions and irrigation is analyzed. Increased soil moisture, vegetation coverage, and dry deposition due to irrigation result in decreased emissions and suspension of dust. This experiment revealed an additional feedback due to irrigation: warming of the surface temperature due to a reduction in mineral aerosols concentration.<br>by Marc Pace Marcella.<br>Ph.D.in the Field of Hydrometeorology
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Niakan, Negar. "Effects of Molecular Structure of the Oxidation Products of Reactive Atmospheric Hydrocarbons on the Formation of Secondary Organic Particulate Matter, Including the Effects of Water." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/617.
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Organic aerosols have significant effects on human health, air quality and climate. Secondary organic aerosols (SOA) are produced by the oxidation of primary-volatile organic compounds (VOC). For example, α-pinene reacts with oxidants such as hydroxyl radical (OH), ozone (O3), and nitrate radical (NO3), accounting for a significant portion of total organic aerosol in the atmosphere. Experimental studies have shown that the oxidation process between α-pinene and ozone has the most significant impact in the formation of SOA (Hoffmann et al., 1997). Most of the models used to predict SOA formation, however, are limited in that they neglect the role of water due to uncertainty about the structure and nature of organic compounds, in addition to uncertainty about the effect of varying relative humidity (RH) on atmospheric organic particulate matter (OPM) (Kanakidou et al., 2005). For this study, structures of organic compounds involved in the formation of SOA are estimated, and the role of water uptake is incorporated in the process. The Combinatorial Aerosol Formation Model (CAFM) is a deterministic model used to determine the amount of organic mass (Mo µg m-3) formation based on the predicted structures. Results show that the amount of SOA that is formed is almost negligible when the amount of parent hydrocarbon involved in the reaction is low (i.e. around 5 µg m-3), especially at lower RH. Observing compounds with a greater number of polar groups (alcohol and carboxylic acid) indicates that structure has a significant effect on organic mass formation. This observation is in agreement with the fact that the more hydrophilic the compound is, the higher RH, leading to more condensation into the PM phase.
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Peter, Justin R. "Numerical investigation of aerosol dynamics : evaluation of the Hamaker constant for environmental tobacco smoke." Thesis, Queensland University of Technology, 1996. https://eprints.qut.edu.au/36917/1/36917_Peter_1996.pdf.
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Human exposure to atmospheric pollutants (aerosols) depends on the nature and concentration of the pollutants, and also on the size distribution of the particulate phase of the aerosol. One such commonly encountered aerosol of significant physiological importance is Environmental Tobacco Smoke (ETS). Knowledge of the time evolution of combustion aerosols is necessary to understand the interactions which shape the aerosol size distribution, and thus lead to conclusions as to the health risk associated with exposure to ETS.
A systematic numerical investigation of the dynamics of aerosol coagulation with the inclusion of van der Waal's forces has been undertaken. Numerical results are compared with those obtained experimentally for the size distribution ofETS in the particle range, 10 nm < particle diameter < 1000 nm. These particles diameters lie in the Cunningham Slip-Flow region, between the free-molecule and continuum regions. The newly developed numerical method allows direct simulation to obtain the size distributions of aging aerosols of arbitrary diameter. Considering that other processes such as condensation and wall deposition are not considered, results obtained theoretically are in excellent agreement with those obtained experimentally.
The comparison of experimental and numerical results enables conclusions to be made as the value of the Hamaker constant for ETS. Although the Hamaker constant is only defined for a pure substance, the method allows an average value over all the constituents of ETS to be evaluated. This value can then be used as input for any further modelling ofETS.
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Xia, Shasha. "CROSS PHOTOREACTION OF PYRUVIC AND GLYOXYLIC ACIDS IN MODEL AQUEOUS AEROSOLS." UKnowledge, 2014. https://uknowledge.uky.edu/chemistry_etds/42.
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Aerosols affect climate change, the energy balance of the atmosphere, and public health due to their variable chemical composition, size, and shape. Aerosols from natural and anthropogenic sources can be primary organic aerosols (POA), which are directly emitted to the atmosphere, or secondary organic aerosols (SOA) that are formed from chemical reactions of gas-phase precursors. At variance with the well investigated formation of SOA from gas phase precursors, the chemistry of aqueous SOAs that contribute to the total SOA budget remains unknown. Field measurements have revealed that carboxylic, dicarboxylic and oxocarboxylic acids are abundant species present in SOAs. This thesis explores the fate of two such acids, pyruvic (PA) and glyoxylic (GA) acids surrogates of the oxocarboxylic acids in the atmosphere, in their cross reaction under solar irradiation and dark thermal aging. Mixtures of complex photoproducts are identified by ion chromatography (IC) with conductivity and electrospray (ESI) mass spectrometry (MS) detection, direct ESI-MS analysis in the negative ion mode, and nuclear magnetic resonance spectroscopy (NMR) analysis including one-dimensional (1H- and 13C-NMR) and two-dimensional techniques such as gradient correlation spectroscopy (gCOSY) and heteronuclear single quantum correlation (HSQC). A reaction mechanism for the cross reaction is provided based on all experimental observations.
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Hergert, Randall J. "Saharan Air Layer Dust Loading: Effects on Convective Strength in Tropical Cloud Clusters." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5882.
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Numerous factors play a role in the development and maintenance of North Atlantic tropical cyclones as they originate and cross the Main Development Region. These factors include sea-surface temperatures (SSTs), relative humidity, vertical wind shear, etc. One key player in many of these factors is the Saharan Air Layer (SAL) which has been a source for study for nearly five decades.
The interplay between dust loading within the SAL and the development of African Easterly Waves (AEWs) has been repeatedly noted in many of the studies in this field. The cumulative indirect effect of the dust on AEWs however remains unknown (Evan et al., 2006a). On a case by case basis, the SAL has been shown to negatively influence the development of AEWs, i.e. entrainment of dry air into the low to mid-levels, enhanced vertical wind shear and suppression of convection within the storm (Dunion & Velden, 2004). Positive influences on AEW development have also been attributed to the SAL, namely its enhancement of the African Easterly Jet (AEJ) which in turn helps produce positive vorticity along its southern edge that AEWs tap into for energy (Karyampudi & Pierce, 2002).
Further study is indeed warranted to try to fully understand whether or not the SAL has a positive or negative influence on the development of AEWs. A polarized view may be inadequate, as the SAL’s role could very well be positive, negative or somewhere in between depending on the storm characteristics and environmental conditions present at that unique time.
This study looked into the role dust loading has on the mixing between the SAL and the moist marine boundary layer directly beneath the base of the SAL, which can range from 500 – 1500m and revealed a dynamic and varying relationship. It also demonstrated, through a decrease in cloud top temperatures, that dust levels are associated with the convective strength of AEWs by acting as cloud condensation nuclei (CCNs). However this association can be nullified through other parameters unique to each individual storm; SSTs, vertical wind shear, dry-air entrainment, etc.
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Benjamin, Michael L. "Investigations of Cleaning Product Sprays." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504873614623952.
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Huffman, Demie R. "Refractory black carbon at Crawford Point, Greenland: Implications for mitigation policy." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534523019443308.
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Berlanga, Jesus Alejandro. "Kinetic Modeling of the Atmospheric Photooxidation of Reduced Sulfur and Nitrogen Compounds." TopSCHOLAR®, 2018. https://digitalcommons.wku.edu/theses/2686.
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Atmospheric aerosols encapsulate a wide variety of particles with different compositions, sizes and sources of origin. They also directly and indirectly affect climate by their interactions with sunlight, clouds, atmospheric chemical species, and even other suspended particles. To understand the atmospheric aerosol processes and the effects they have in global and regional climate is of utmost importance for the future establishment of environmental regulations and emission policies that affect aerosol precursor compounds in an effective and beneficial manner. In particular, aerosols are known to be formed from emissions from human activities, such as fossil fuel burning, agriculture, or concentrated animal feeding operations (CAFOs). Secondary organic aerosols (SOA) constitute a type of atmospheric aerosols that are formed from the atmospheric oxidation of organic compounds that are released from various sources into the atmosphere. Due to the complexity of the atmosphere and variability of its conditions, the direct study of SOA formation is a challenging task, but the implementation of atmospheric chamber facilities to study aerosol formation and growth under controlled conditions has provided a way to study the formation and growth of SOA. However, chamber experiments cannot study specific reactions or individual compounds from the aerosol formation mechanisms in isolation, they can only provide insight on what is produced and what it is produced from, and under what conditions. Thus, kinetic modeling of the mechanisms of gas-phase atmospheric oxidation of the compounds of interest is used to develop reliable and accurate chemical models that will help have precise estimations and determine the mechanisms by which volatile organic compounds interact to produce aerosol particles. Dimethyl sulfide (DMS), dimethyl disulfide (DMDS) and trimethylamine (TMA) are three relevant atmospheric compounds, due to their emissions from many natural and anthropogenic sources and recent studies on emissions of these compounds from animal waste from CAFOs has triggered the interests on the study of SOA formation from these and other similar compounds. In this study, kinetic modeling of the atmospheric oxidation mechanisms of DMDS, DMS and TMA is used to simulate atmospheric chamber studies of aerosol formation to develop accurate models and help determine the mechanisms of aerosol formation.
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Rawle, Christopher B., and n/a. "Coherent multiwavelength sources for tropospheric aerosol lidar." University of Otago. Department of Physics, 2005. http://adt.otago.ac.nz./public/adt-NZDU20070427.114533.
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The monitoring and study of the earth�s atmosphere is becoming an increasingly important task given the current uncertainties in climate prediction. Areas where lidar has been used to further understanding of the atmosphere include monitoring of greenhouse gases, global warming, stratospheric ozone depletion, photochemical smog and aerosol photochemistry. However, the potentially severe long term effects of anthropogenic aerosols on earth�s biosphere are poorly understood. This project seeks to apply state of the art laser technology to develop an innovative multiwavelength lidar system capable of providing new information and new insights into the field of tropospheric aerosol lidar.
Several novel tunable laser and laser-like sources have been investigated and developed for the purpose of tropospheric aerosol lidar at The National Institute of Water and Atmospheric Research (Niwa), Central Otago. Multiwavelength operation in the visible and near infrared portion of the spectrum has been emphasised with the sources developed collectively spanning the wavelength interval of 400-1369 nm. The laser sources investigated were the LiF:F2+ colour centre, Titanium Sapphire (Ti:sapphire) and barium nitrate Raman lasers. In addition to the laser sources, the β-barium borate optical parametric oscillator (BBO OPO) was characterised. For each of the sources, lidar relevant aspects were studied. The results recorded include conversion efficiency with respect to the pump source, linewidth and tuning characteristics, beam quality, temporal behaviour, and device reliability and ruggedness.
It was found that the LiF:F2+ laser offered significantly lower threshold, broader tuning and higher output pulse energies than the Ti:sapphire laser in the 900-1000 nm region. The high optical gain of the LiF:F2+ medium facilitated cavity optical alignment and operation of the system. The high gain also resulted in temporal behaviour well suited to the existing Niwa lidar detection scheme. When using a 5 ns pump source, amplified spontaneous emission (ASE) was found to limit the laser tuning range and efficiency.
The barium nitrate Raman laser was based on a simple linear cavity arrangement which resulted in a compact and robust device with no moving components. The stimulated Raman scattering process offers relatively narrow linewidth laser operation at the first and second Stokes wavelengths of 1197 nm and 1369 nm respectively. This laser offered efficient operation once the high operation threshold was reached. Second harmonic generation was used to extend the number of potential lidar transmitter lines produced. The barium nitrate Raman laser possessed high beam divergence and a maximum of three discrete transmitter wavelengths.
The BBO OPO used a type I collinear signal resonant configuration. A plane-plane cavity configuration with pump reflection was found to provide simplicity of design, low threshold, highly efficient operation and output pointing stability. The BBO OPO signal wavelength could be tuned over the wavelength interval of 400-700 nm. The disadvantage of the plane cavity was high output beam divergence. However, this was successfully brought within the required limits through the use of a 40 mm long cavity in conjunction with an expanding and collimating telescope.
As a result of the study, a Tunable lidar Transmitter (TLT) system based on the BBO OPO was designed and constructed at the Physics Department. The TLT was computer-controlled using custom written software and constructed in a self contained modular manner with all required mechanical, electrical and optical components. A user manual was also written to accompany the TLT. The TLT was installed at Niwa and was successfully used to gather preliminary multiwavelength lidar data.
The TLT BBO OPO threshold occurred for a pump energy of 5.2 mJ (10.6 MW/cm2) and had a maximum slope efficiency of 53%. Signal efficiency varied from 24-41-35% over the intervals of 410-500-600 nm. A maximum signal energy of 21 mJ was obtained for a signal wavelength of 492 nm when using the maximum available pump energy of 42 mJ. OPO signal linewidth varied from 0.1-1-8 nm over the signal wavelength intervals of 400-600-700 nm. The associated OPO finesse varied between 370 and 100 as the signal wavelength was tuned over the wavelength interval of 400-600 nm. The temporal behaviour of the BBO OPO was a slowly varying function of pump energy and closely followed the temporal behaviour of the pump laser, making it well suited to the existing Italian lidar detection and timing scheme.
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Burn, Laurie. "Isotopic and elemental tracers in ice and snow as indicators of source regions of aerosols and changing environmental conditions." Thesis, Curtin University, 2009. http://hdl.handle.net/20.500.11937/152.
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Pioneering studies of lead (Pb) concentrations in polar ice by Clair C. Patterson and co-workers (e.g. Murozumi et al., 1969; Boutron and Patterson, 1983, 1986) revealed important information on climatic changes dating many thousands of years in the past and the effect that humans have had on these pristine environments. Rosman and co-workers (e.g. Rosman et al., 1993, 1994a) extended this research utilising the isotopic composition of Pb preserved in the ice to identify the source regions of both natural and anthropogenic Pb transported to the polar regions, thereby adding significantly to the understanding of atmospheric transport mechanisms and the impact of continental anthropogenic activity on the pristine polar environments. This thesis extends this area of research by investigating seasonal and short-term variability in Pb, Ba and In concentrations and Pb isotopes through the accurate sectioning of decontaminated glacial ice cores at high spatial resolution. This improves our understanding of the processes impacting on the deep ice core records, which, in turn, expands the interpretation and application of these records.A new sample preparation technique, incorporating a mechanised circular saw blade arrangement into the lathe design, first described by Candelone et al. (1994), has been developed to sample glacial ice cores at high spatial resolution with minimal contamination. This technique was extensively tested using artificially made ice cores, prepared from ultra-pure water, to quantify and minimise the Pb, Ba and In contamination associated with the process. The residual contamination in each inner core slice from the procedure amounted to 0.2 ± 0.2 pg Pb with [superscript]206Pb/[superscript]207Pb, [superscript]208Pb/[superscript]207Pb and [superscript]206Pb/[superscript]204Pb ratios of 1.16 ± 0.12, 2.35 ± 0.16 and 15.3 ± 6.7 respectively, 1.5 ± 0.4 pg Ba and 0.6 ± 2.0 fg In. This technique was then utilised to obtain high resolution analyses of Pb, Ba and In concentrations, and Pb isotopes in ice core sections recovered from Law Dome, East Antarctica and from the East Rongbuk Glacier on the northern slope of Mount Everest in the Himalaya.Law Dome, East Antarctic Holocene ice cores provide strong evidence for the transport of anthropogenic Pb from Australia to the Law Dome environment during the late 19th century, with [superscript]206Pb/[superscript]207Pb and [superscript]208Pb/[superscript]207Pb ratios as low as 1.061 ± 0.001 and 2.339 ± 0.002 respectively, in close agreement with the Pb isotopic characteristics of Australian Broken Hill Pb ores. The onset of anthropogenic pollution of the Law Dome environment occurred in spring 1889 AD, associated with the onset of Pb ore smelting activities in Port Pirie, South Australia. Seasonal variability is most clearly seen in anthropogenic Pb and Ba (as a proxy for mineral dust) concentrations where peaks in concentrations generally occur in the autumn and spring periods, with consistently low concentrations during winter. Lead isotopic [superscript]206Pb/[superscript]207Pb ratios are inversely correlated with residual (anthropogenic + crustal) Pb concentrations with the lowest ratios occurring during periods of high Pb concentrations. The observed seasonal variability is associated with the annual cycle in position and strength of the Antarctic Circumpolar Trough, a region of low pressure situated off the coast of Antarctica, which moves closest to the Antarctic coast and increases in strength during the autumn and spring seasons. Concurrently, a strengthening of the Southern Ocean westerlies entrains and transports more atmospheric impurities from continental regions such as Australia. The low Pb concentrations and relatively more radiogenic [superscript]206Pb/[superscript]207Pb ratios that appear in the winter layers are indicators of aerosol inputs into the Law Dome environment from a well mixed Southern Hemisphere atmospheric background.Law Dome deep ice core sections, sampled at short-term resolution, show variability in all measured species over time indicating a general instability in temperature (as indicated by δ18O compositions) and environmental conditions (as indicated by elemental concentrations) prevailing during the periods of time integrated by the ice. Based on Pb isotopic [superscript]206Pb/[superscript]207Pb ratios, which reach values of 1.225 ± 0.004 and 1.230 ± 0.003 in glacial, and last glacial – Holocene transition ice respectively, noticeable volcanic Pb contributions are found to occur in both time periods, reaching as high as ~39% and ~46% respectively. These increases are associated with a decrease in mineral dust concentrations due to relatively warmer climatic conditions prevailing within the times integrated by the ice core sections. A link between temperature and environmental conditions in glacial ice is observed when changes in δ18O compositions (as a proxy for temperature) exceed 0.24‰. In contrast, there is no link between temperature and environmental conditions during the last glacial – Holocene transition period, demonstrating a complicated climatic and environmental state existing at Law Dome at this time that incorporates aspects of both cold and warm climates.The high spatial resolution sectioning of continental glacial ice cores recovered from the East Rongbuk Glacier on the northern slopes of Mount Everest, and dated to the 18th and 20th centuries, has similarly shown variability in all measured species over time. Elemental Pb, Ba and In concentrations are very well correlated in all ice core sections confirming the environment of the East Rongbuk Glacier, within the investigated time periods, to be strongly controlled by the input of mineral dust. Isotopic [superscript]206Pb/[superscript]207Pb ratios in 18th century ice range from 1.18 – 1.21 which are attributed to a natural mineral dust background devoid of any influences of anthropogenic [or volcanic] activity. During 18th century monsoon periods (when mineral dust concentrations are generally low), local Himalayan material plays an important role on crustal inputs into the sampling region, with some inputs of Indian derived material possibly sourced to the Indian Peninsula, and Trans-Himalayan belt/Lhasa block material sourced to locations slightly north of Mount Everest. During non-monsoon periods (when mineral dust concentrations are generally high), it is likely that mineral dust from regions in northern Africa and central Asia are impacting on the high altitude Himalaya, with some possible contributions from the arid regions in north-western India and local Himalayan material.Based on elemental (Pb/Ba) and Pb isotopic ratios, there is no indication ofanthropogenic [or volcanic] Pb contributions in the 20th century East RongbukGlacier ice core samples indicating that, prior to 1952 AD, the high altitude samplingsite was isolated from the effects of anthropogenic Pb pollution. Consequently, inthe 20th century, Pb transported to the East Rongbuk Glacier site is sourced tomineral dust. An increase in elemental concentrations is observed in 20th century ice,indicating increased mineral dust deposition relative to the 18th century.Concurrently, a marked change in the isotopic characteristics of 20th century ice coredata, relative to 18th century ice core data, is observed, with a clear segregation ofmonsoon and non-monsoon data and the transition of 20th century data to lessradiogenic values. This adjustment likely reflects environmental changes that haveoccurred from the 18th to the 20th centuries.
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Beekman, Christopher Paul. "Differential Optical Absorption Spectroscopy of Trace Gas Species and Aerosols in the Upper Ohio River Valley." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1268143515.
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Luma, Johnson. "Sleep Loss and Environmental Exposures in Asthma Patients (SLEEAP):Chemical and Statistical Analyses for Interior Aerosols from Buffalo, NY Residences." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1523636175286216.
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Iizuka, Yoshinori, Torbjorn Karlin, and Margareta Hansson. "Sulphate and chloride aerosols during Holocene and last glacial periods preserved in the Talos Dome Ice Core, a peripheral region of Antarctica." Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-90812.
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Antarctic ice cores preserve the record of past aerosols, an important proxy of past atmospheric chemistry. Here we present the aerosol compositions of sulphate and chloride particles in the Talos Dome (TD) ice core from the Holocene and Last Glacial Period. We find that the main salt types of both periods are NaCl, Na2SO4 and CaSO4, indicating that TD ice contains relatively abundant sea salt (NaCl) from marine primary particles. By evaluating the molar ratio of NaCl to Na2SO4, we show that about half of the sea salt does not undergo sulphatisation during late Holocene. Compared to in inland Antarctica, the lower sulphatisation rate at TD is probably due to relatively little contact between sea salt and sulphuric acid. This low contact rate can be related to a reduced time of reaction for marine-sourced aerosol before reaching TD and/or to a reduced post-depositional effect from the higher accumulation rate at TD. Many sulphate and chloride salts are adhered to silicate minerals. The ratio of sulphate-adhered mineral to particle mass and the corresponding ratio of chloride-adhered mineral both increase with increasing dust concentration. Also, the TD ice appears to contain Ca(NO3)(2) or CaCO3 particles, thus differing from aerosol compositions in inland Antarctica, and indicating the proximity of peripheral regions to marine aerosols.<br><p>AuthorCount:9;</p>
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Lindelof, Kara L. "Contribution of Biosolids-derived Bioaerosols to the Airborne Microbial Population." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1302299544.
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Titov, Mikhail. "Investigation of winter aerosol dispersion using the MM5/WRF-CAMx4 numerical modelling system : application to the aerosol abatement strategy for the city of Christchurch : a thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in Environmental Science at the University of Canterbury /." Thesis, University of Canterbury. Geography, 2008. http://hdl.handle.net/10092/1581.
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Air circulation and air pollution dispersion models are used by a range of stakeholders involved in managing air quality in New Zealand following the recent establishment and implementation of the National Environmental (Air Quality) Standards by the Ministry for the Environment. MM5-CAMx4 and WRF-CAMx4 numerical modelling systems were utilized to air circulation over the complex terrain of the Christchurch area for investigation applied to winter aerosol pollution, following the recent establishment and implementation of the National Environmental Standards. A new method using several different chemical scenarios is developed to calculate optimal chemical composition of the input gridded aerosol emissions. This method improves the accuracy of predicted PM concentrations. The MM5-CAMx4.2 numerical system is evaluated to predict aerosol concentrations over a 48-72 hour time period for Christchurch for winter 2005. The aerosol concentrations are obtained for four different chemical compositions of the input aerosol emissions. The fine-total PM regression error between observed and modelled aerosol is used to find the minimum difference between modelled and ambient aerosol. Combination of the chemical scenarios with the minimum error between modelled and ambient data is employed to create a new complex chemical scenario. A reduction of the systematic error in the scenario method is achieved by applying the MM5/WRF - CAMx4.2 numerical system and observations for winter 2006, aerosol data from 2 observation sites. Assessment of the efficiency of PM abatement strategies for the period 2005- 2013 is undertaken using winter 2005 meteorology and application of a linear reduction in emissions according to Environment Canterbury proposed plan for aerosol reduction. A new numerical approach to selection of PM monitoring sites optimal localisation is also developed and could be applied to any air pollutant to find the optimal positions for installing new observation sites.
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Fishwick, Matthew Paul. "A study of the dissolution of atmospherically derived trace metals into North Atlantic seawater." Thesis, University of Plymouth, 2016. http://hdl.handle.net/10026.1/5288.
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The aim of this study was to investigate the factors that affect the dissolution of a suite of trace metals from aerosols into seawater from wet and dry deposition, with a focus on important trace metals: manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu) and lead (Pb). To this end, aerosol and rainwater samples were collected from Tudor Hill (Bermuda) and Penlee Point (Cornwall) atmospheric observatories and surface seawater samples were collected from the Sargasso Sea and the Celtic Sea. These representative aerosol, rainwater and seawater samples were used in aerosol leaching and rainwater mixing experiments, which simulated the processes of mixing and trace metal dissolution following wet and dry deposition as closely as possible within the laboratory. Key variables were changed to investigate the effect of aerosol source/composition, seawater temperature, pH, dissolved oxygen concentration and organic ligand amendments on aerosol and rainwater trace metal dissolution. Results for aerosol leaching experiments revealed that changes to key physico-chemical conditions had little effect on the amount of Mn, Fe, Co, Ni and Pb leached from aerosols and therefore plausible future changes in ocean surface temperature, pH and oxygenation are unlikely to affect the flux of these important trace metals to surface waters. Conversely, aerosol source and composition had a significant effect on the dissolution of aerosol Fe, Co and Pb, with the most anthropogenically influenced aerosol samples displaying the highest solubilities. Therefore, future changes in land use and fossil fuel combustion are likely to affect the flux of these metals to the surface ocean. Fractional solubilities were in the range of 50 – 104% for Mn, 0.3 – 3.2% for Fe, 29 – 58% for Co, 40 – 85% for Ni and 67 – 112% for Pb. In addition, novel empirical relationships were found between the fractional solubilities of Fe, Co and Pb and enrichment factors for antimony, vanadium, Ni and Cu. This suggests that these fractional solubilities in seawater could be predicted using only total aerosol trace metal concentrations. The use of ultrafiltration provided unique insight into the size fractionation (colloidal 0.02 – 0.4 μm; soluble < 0.02 μm) of dissolved aerosol trace metals and showed Fe and Pb were mostly colloidal (77 – 98% colloidal), Mn and Co were mostly soluble (0 – 48% colloidal) and Ni showed a mixed profile (6 – 58% colloidal) when released from aerosols into ambient seawater. However, in the presence of a sufficient concentration of strong organic ligands the majority colloidal Fe was converted to soluble Fe (up to 100% soluble). Some of these organic ligands were also able to increase the soluble fraction of dissolved aerosol Mn. Similarly, the presence of organic ligands in rainwater maintained Mn, Fe, Co, Cu and Pb in the dissolved phase following delivery by rain into seawater. Rainwater ligands had no effect on the typically varied size fractionation profile of Mn, Fe, Co and Cu in rainwater mixed with seawater, UV-irradiation of rainwater, however, shifted the size fractionation of Pb in rainwater/seawater mixtures from 80 – 100% colloidal to 13 – 63% soluble, indicating that Pb-binding rainwater ligands are either colloidal or attached to colloidal matter. These findings highlight the importance of organic ligands in rainwater and seawater for retaining trace metal micronutrients and toxicants in the surface ocean, with implications for primary production.
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Niemeier-Walsh, Christine. "Exposure to Traffic-Related Air Pollution and Biological Aerosols: Effect on the Respiratory Microbiome and a Comparison of Measurement Methods." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1592134878472621.
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Thomson, Rachel M. "Characteristics of nontuberculous mycobacteria from a municipal water distribution system and their relevance to human infections." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/65483/1/Rachel_Thomson_Thesis.pdf.
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This thesis documented pathogenic species of nontuberculous mycobacteria in the Brisbane water distribution system. When water and shower aerosol strains were compared with human strains of mycobacteria, the study found that the likelihood of acquiring infection from municipal water was specific for four main species. The method for isolation of mycobacteria from water was refined, followed by sampling from 220 sites across Brisbane. A variety of species (incl 15 pathogens) were identified and genotypically compared to human strains. For M. abscessus and M. lentiflavum, water strains clustered with human strains. Pathogenic strains of M. kansasii were found, though non-pathogenic strains dominated. Waterborne strains of M. fortuitum differed to human strains. Extensive home sampling of 20 patients with NTM disease, supported the theory that the risk of acquiring NTM from water or shower aerosols appears species specific for M. avium, M. kansasii, M. lentiflavum and M. abscessus.
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Pillar-Little, Elizabeth A. "MECHANISMS OF HETEROGENEOUS OXIDATIONS AT MODEL AEROSOL INTERFACES BY OZONE AND HYDROXYL RADICALS." UKnowledge, 2017. http://uknowledge.uky.edu/chemistry_etds/80.
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Atmospheric aerosols play an important role in climate by scattering and absorbing radiation and by serving as cloud condensation nuclei. An aerosol’s optical or nucleation properties are driven by its chemical composition. Chemical aging of aerosols by atmospheric oxidants, such as ozone, alters the physiochemical properties of aerosol to become more hygroscopic, light absorbing, and viscous during transport. However the mechanism of these transformations is poorly understood. While ozone is a protective and beneficial atmospheric gas in the stratosphere, it is a potent greenhouse gas in the troposphere that traps heat near the Earth’s surface. It also impacts human heath by irritating the respiratory tract and exacerbating cardiovascular diseases. Additionally, ozone can alter the ecosystem through oxidizing plant foliage which can lead to deforestation and crop losses as well. Both gases and aerosols in the troposphere can react with ozone directly and indirectly with hydroxyl radicals. While daytime aging is thought to be primarily driven by photochemical processes and hydroxyl radicals, ozone is thought to be a key player in nighttime or dark aging processes that can alter the physicochemical properties of aerosols. Measured concentrations of trace gases and aged aerosol components in the field are higher than values predicted based on laboratory studies and computer simulations. Consequently, new experimental approaches are needed to narrow the gaps between observations and mechanistic understandings.
In this dissertation, a plume of microdroplets was generated by pneumatically assisted aerosolization and then exposed to a flow of ozone before entering a mass spectrometer. This surface-specific technique allowed for the real-time analysis of reaction products and intermediates at the air-water interface. This work explores the in situ oxidation of iodide, a component of sea spray aerosols, by 0.05 – 13.00 ppmv ozone to explore how heterogeneous oxidation could enhance the production of reactive iodide species. Methods to study the reaction channels and intermediates were also established to not only determine a mechanism of iodide oxidation by ozone, but to enable the study of more complex systems. The developed approach was then applied to examine the oxidation of catechol and its substituted cousins, a family of compounds selected to model biomass burning and combustion emissions, at the air-water interface. While literature suggested that the primary mechanism of catechol oxidation by ozone would be the cleavage of the C1-C2 bond, it was determined that this was only a minor pathway. An indirect oxidation channel dominated heterogeneous processes at the air-water interface, giving rise to hydroxyl and semiquinone radicals that recombine to produce polyhydroxylated aromatics and quinones. This new mechanism of aging represents an overlooked channel by which brown, light-absorbing carbon aerosols are produced in the atmosphere.
In addition, the work investigates how reactions on solid particulate aerosols proceed under variable relative humidity. Thin films were developed alongside a novel flow-through reactor to study of how aerosols are transformed by ozone and hydroxyl radicals when exposed to 50 ppbv - 800 ppmv of ozone. This system was employed to probe how catechol reacts with ozone under variable relative humidity. Further work was undertaken to model the adsorption process at the air-solid interface under variable humidity, permitting the estimation of the reactive uptake of ozone by the film at concentrations (50-200 ppbv) seen in rural and urban areas. Together, these results provide an increased understanding of how heterogeneous oxidation of aerosols contributes to aerosol aging processes as well as free radical production in the troposphere.
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Zuluaga-Arias, Manuel D. "Spatio-temporal variability of aerosols in the tropics relationship with atmospheric and oceanic environments." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41202.
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Earth's radiation budget is directly influenced by aerosols through the absorption of solar radiation and subsequent heating of the atmosphere. Aerosols modulate the hydrological cycle indirectly by modifying cloud properties, precipitation and ocean heat storage. In addition, polluting aerosols impose health risks in local, regional and global scales.
In spite of recent advances in the study of aerosols variability, uncertainty in their spatial and temporal distributions still presents a challenge in the understanding of climate variability. For example, aerosol loading varies not only from year to year but also on higher frequency intraseasonal time scales producing strong variability on local and regional scales. An assessment of the impact of aerosol variability requires long period measurements of aerosols at both regional and global scales.
The present dissertation compiles a large database of remotely sensed aerosol loading in order to analyze its spatio-temporal variability, and how this load interacts with different variables that characterize the dynamic and thermodynamic states of the environment. Aerosol Index (AI) and Aerosol Optical Depth (AOD) were used as measures of the atmospheric aerosol load. In addition, atmospheric and oceanic satellite observations, and reanalysis datasets is used in the analysis to investigate aerosol-environment interactions. A diagnostic study is conducted to produce global and regional aerosol satellite climatologies, and to analyze and compare the validity of aerosol retrievals. We find similarities and differences between the aerosol distributions over various regions of the globe when comparing the different satellite retrievals. A nonparametric approach is also used to examine the spatial distribution of the recent trends in aerosol concentration. A significant positive trend was found over the Middle East, Arabian Sea and South Asian regions strongly influenced by increases in dust events.
Spectral and composite analyses of surface temperature, atmospheric wind, geopotential height, outgoing longwave radiation, water vapor and precipitation together with the climatology of aerosols provide insight on how the variables interact. Different modes of variability, especially in intraseasonal time scales appear as strong modulators of the aerosol distribution. In particular, we investigate how two modes of variability related to the westward propagating synoptic African Easterly Waves of the Tropical Atlantic Ocean affect the horizontal and vertical structure of the environment. The statistical significance of these two modes is tested with the use of two different spectral techniques. The pattern of propagation of aerosol load shows good correspondence with the progression of the atmospheric and oceanic synoptic conditions suitable for dust mobilization over the Atlantic Ocean. We present extensions to previous studies related with dust variability over the Atlantic region by evaluating the performance of the long period satellite aerosol retrievals in determining modes of aerosol variability. Results of the covariability between aerosols-environment motivate the use of statistical regression models to test the significance of the forecasting skill of daily AOD time series. The regression models are calibrated using atmospheric variables as predictors from the reanalysis variables. The results show poor forecasting skill with significant error growing after the 3rd day of the prediction. It is hypothesized that the simplicity of linear models results in an inability to provide a useful forecast.
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Zeng, Qing-Yin. "Development of molecular techniques for fungal diagnostic research." Doctoral thesis, Umeå : Umeå universitet : Arbetslivsinstitutet, 2005. http://kb.se/resolve?urn=urn:nbn:se:umu:diva-656.
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Young, Dominique Emma. "Characterisation of the chemical properties and behaviour of aerosols in the urban environment." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/characterisation-of-the-chemical-properties-and-behaviour-of-aerosols-in-the-urban-environment(27de7e50-5069-40a0-b5cd-1370747f646a).html.
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Atmospheric aerosols have adverse effects on human health, air quality, and visibility and frequently result in severe pollution events, particularly in urban areas. However, the sources of aerosols and the processes governing their behaviour in the atmosphere, including those which lead to high concentrations, are not well understood thus limit our ability to accurately assess and forecast air quality. Presented here are the first long-term chemical composition measurements from an urban environment using an Aerodyne compact Time-of-Flight Aerosol Mass Spectrometer (cToF-AMS). Organic aerosols (OA) were observed to account for a significant fraction (44%) of the total non-refractory submicron mass during 2012 at the urban background site in North Kensington, London, followed by nitrate (28%), sulphate (14%), ammonium (13%), and chloride (1%). The sources and components of OA were determined using Positive Matrix Factorisation (PMF) and attributed as hydrocarbon-like OA (HOA), cooking OA (COA), solid fuel OA (SFOA), type 1 oxygenated OA (OOA1), and type 2 oxygenated OA (OOA2), where HOA, COA, and SFOA were observed to be of equal importance across the year. The concentration of secondary OA increased during the summer yet the extent of oxidation, as defined by the oxygen content, showed no variability during the year. The main factors governing the diurnal, monthly, and seasonal trends observed in all organic and inorganic species were meteorological conditions, specific nature of the sources, and availability of precursors. Regional and transboundary pollution influenced total aerosol concentrations and high concentration events were observed to be governed by different factors depending on season. High-Resolution ToF-AMS measurements were used to further probe OA behaviour, where two SFOA factors were derived from PMF analysis in winter, which likely represent differences in burn conditions. In the summer an OA factor was identified, likely of primary origin, which was observed to be strongly associated with organic nitrates and anthropogenic emissions. This work uses instruments and techniques that have not previously been used in this way in an urban environment, where the results further the understanding of the chemical components of urban aerosols. Aerosol sources are likely to change in the future with increases in solid fuel burning as vehicular emissions decrease, with significant implications on air quality and health. Thus it is important to understand aerosol sources and behaviour in order to develop effective pollution abatement strategies.
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Pushpawela, Buddhi G. "The formation and characteristics of new particles in the atmosphere." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/122854/2/__qut.edu.au_Documents_StaffHome_StaffGroupH%24_halla_Desktop_Buddhi_Pushpawela_Thesis.pdf.
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Airborne particles play a major role in climate change and human health. Drawing on the results of extensive measurements carried out in the relatively clean environment of Brisbane and the heavily polluted megacity of Beijing, this thesis has significantly furthered our knowledge of the physical mechanisms of new particle formation in the lower atmosphere. Several characteristics of new particle formation events, such as their temporal distribution, the effect of wind speed and the role of atmospheric ions on the particle formation rate, were investigated for the very first time.
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Li, Sujuan. "Evaluating ambient fine particulate matter source regions in the Ohio River Valley Region." Ohio : Ohio University, 2003. http://www.ohiolink.edu/etd/view.cgi?ohiou1070550479.
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Dogan, Guray. "Comparison Of The Rural Atmosphere Aerosol Compositions At Different Parts Of Turkey." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12605844/index.pdf.
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Long term data generated at four rural stations are compared to determine similarities and differences in aerosol compositions and factors contributing to observed differences at different regions in Turkey. The stations used in this study are located at Mediterranean coast (20 km to the west of Antalya city), Black Sea coast (20 km to the east of Amasra town), Central Anatolia (Ç<br>ubuk, Ankara) and Northeastern part of the Anatolian Plateau (at Mt. Uludag). Data used in comparisons were generated in previous studies. However, some re-analysis of data were also performed<br>(1) to improve the similarities of the parameters compared and (2) to be able to apply recently-developed methodologies to data sets.
Data from Mediterranean and Black Sea stations were identical in terms of parameters measured and were suitable for extensive comparison. However, fewer parameters were measured at Ç<br>ubuk and Uludag stations, which limited the comparisons involving these two stations. Comparison included levels of major ions and elements, short-term and seasonal variations in concentrations, background (baseline) concentrations of elements, flow climatology of regions, correlations between elements, potential source areas affecting regions, and source types affecting chemical composition of particles.
Comparison of levels of measured parameters in four regions showed that there are some differences in concentrations that arise from differences in the local characteristics of the sampling points. For example very high concentrations of elements such as Na and Cl in the Mediterranean region is attributed to closer proximity of the Antalya station to coast and not a general feature of the Mediterranean aerosol. There are also significant regional differences in the concentrations of measured elements and ions as well. Concentrations of anthropogenic elements are very similar at two coastal stations (Antalya and Amasra), but they are approximately a factor of two smaller at the two stations that are located on the Anatolian Plateau. This difference between coastal and high altitude plateau stations, which is common to all anthropogenic species, is attributed to different source regions and transport mechanisms influencing coastal regions and Anatolian Plateau.
Some statistically significant differences were also observed in the temporal variations of elements and ions measured in different stations. The elements with crustal origin showed similar seasonal pattern at all stations, with higher concentrations in summer and lower concentrations in winter. This difference between summer and winter is attributed to suppression of re-suspension of crustal aerosol from wet or ice-covered surface soil in winter. Concentrations of anthropogenic elements, on the other hand, did not show a statistically significant seasonal trend at Amasra, Ç<br>ubuk and Uludag stations, but they have higher concentrations during summer months at the Antalya station. This difference between Mediterranean aerosol and aerosol at the Central and Northern Turkey is due to influence of more local sources on Ç<br>ubuk, Amasra and Uludag stations and domination of more distant source in determining aerosol composition at the Mediterranean region. A similar conclusion of strong influence of local sources on chemical composition of particles at the Central Anatolia was also suggested by the comparison of baseline concentrations in each station.
General features in flow climatology (residence times of upper atmospheric air masses) in each region are found to be similar with more frequent flow from W, WNW, NW and NNW wind sectors. Since these are the sectors that include high emitting countries in Eastern and Western Europe and Russia, transport from these sectors are expected to bring pollution from both distant European countries and more local Balkan countries and western parts of Turkey.
Flow climatology in stations showed small, but statistically significant, differences between summer and winter seasons. These variations suggested that the station at the Central Anatolia and Black Sea (Ç<br>ubuk Amasra and Uludag stations) are affected from sources located at the Western Europe in winter season and from sources located at the Eastern Europe in summer. Mediterranean aerosol, on the other hand, are affected from sources at the Western Europe and do not show any seasonal differences. This variation in flow climatology between summer and winter seasons (and lack of variation at the Mediterranean station) is supported by the seasonal variation (and lack of variation at the Mediterranean station) in SO42-/NO3- ratio measured at the stations.
Potential source contribution function (PSCF) values are calculated for selected elements and ions in each station. Statistical significance of calculated PSCF values is tested using bootstrapping technique. Results showed that specific grids at Russia and at Balkan countries are common source regions affecting concentrations of anthropogenic elements at all four regions in Turkey. However, each station is also affected from specific source regions as well. Aerosol composition at the Anatolian Plateau are affected from sources closer to the sampling points whereas Mediterranean and Black Sea aerosol are affected from source regions that farther away from the receptors. It should be noted that the same conclusion is also reached in comparison of seasonal patterns and baseline concentrations at these stations.
Types of sources affecting aerosol composition at Black Sea, Mediterranean and Central Anatolia are also compared. Source types affecting atmospheric composition in these regions were calculated using positive matrix factorization (PMF). The results showed that aerosol at the Black Sea, Central Anatolia and Mediterranean atmosphere consists of 8, 6 and 7 components, respectively. Two of these components, namely a crustal component and a long-range transport component are common in all three stations. The chemical compositions of these common components are shown to the same within 95% statistical significance interval. Three factors, namely a fertilizer factor, which is highly enriched in NH4+ ion, a sea salt component and an arsenic factor are common in the Mediterranean and Black Sea aerosol but not observed at the Central Anatolia. Other factors found in the regions are specific for that region.
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Marks, Marguerite Colasurdo. "Incorporating Chemical Activity and Relative Humidity Effects in Regional Air Quality Modeling of Organic Aerosol Formation." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1511.
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Atmospheric particulate matter is known to have significant effects on human health, visibility, and global climate. The magnitudes of these effects, however, depend in complex ways on chemical composition, relative humidity, temperature, phase state, and other parameters. Current regional air quality models such as CMAQ (Community Multiscale Air Quality model) ignore many of these considerations, and consider that the formation of secondary organic aerosol (SOA) can be calculated by assuming thermodynamic ideality in the organic particulate matter (OPM) phase as well as negligible uptake of water into the OPM phase. Theoretical predictions and model simulations considering non-ideality and water uptake show that the standard model assumptions can lead to large errors in predicted SOA mass, and that the magnitude of these errors is sensitive to the composition of the OPM phase.
The SOA module in CMAQ v4.7.1 has been revised in this work to allow consideration of the effects of both non-ideality and water uptake. First, a reasonable specific surrogate structure was assigned to each of the lumped products assumed to be produced by reaction of the different precursor hydrocarbons considered in CMAQ (e.g., isoprene, benzene, and toluene). Second, the CMAQ code was modified to allow iterative calculation (at each point in space and time) of the gas/particle partitioning coefficient for each of the SOA-forming products and for water. Third, model simulations were performed for the Eastern US at a resolution of 36-km x 36-km for late summer 2006, under a range of relative humidity conditions.
When compared with an appropriate base case, the modified code produced increases in SOA ranging from 0.17 to 0.51 micrograms per cubic meter. The average change was 0.30 micrograms per cubic meter, corresponding to a 37% increase in SOA formation. Incorporation of phase separation effects would likely lead to further increases in predicted SOA levels.
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Zubkova, Galina. "Analysis of Ambient Fine Particulate Matter, PM 2.5 , in Pittsburgh Using Time-Series Techniques and Meteorology." Ohio : Ohio University, 2003. http://www.ohiolink.edu/etd/view.cgi?ohiou1060032557.
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Scott, Krista Janette. "Temperature dependency of burn-off emissions in the automobile industry." Thesis, University of Iowa, 2008. http://ir.uiowa.edu/etd/24.
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