Per-and polyfluoroalkyl substances (PFAS) are anthropogenic compounds that have been spread all over the world. The use of fluorotelomer compounds, short-chained homologues, and other PFASs with perfluorinated moieties has emerged recent years. One of these emerging compound classes is polyfluoroalkyl phosphate esters (PAPs), which have the ability to degrade into persistent PFCAs. The aim of this thesis was to assess the contribution of PAPs and other precursors to the exposure of PFCAs to humans and the environment. The main objective was to analyze a wide range of PFAS in human serum, wild bird eggs, indoor dust, waste water, and sludge. There was a significant contribution from selected precursors to the total amount of PFASs in the abiotic compartments indoor dust, waste water, and sludge. Levels of PAPs found in house dust exceeded those of PFCAs and perfluorosulfonic acids (PFSAs), revealing PAPs as a world-wide important exposure source. A net increase was during waste water treatment was observed for several PFASs in Swedish waste water treatment plants. Together with presence of precursor compounds and intermediates in the influent water and the sludge, this suggest that degradation of PFCA precursors contributed to the increase of PFCAs. Detection of precursors in human serum, together with slow declining trends of PFCAs, revealed an ongoing exposure of PFCAs to the general population of Australia. The diPAPs and the FTSAs were also detected in raptor bird eggs from Sweden from both the terrestrial and the freshwater environment. The precursors concentrations and patterns observed reveal that current regulatory measures are insufficient for the purpose of protecting humans and the environment from PFASs exposure.

Patagonie et la Namibie sont deux sources importantes d'aérosol minéral qui alimente la section Atlantique Sud de l'océan Austral avec les micronutriments.L'objet de ma thèse est d'étudier 1) la concentration atmosphérique et la variation temporel de la poussière en Patagonie, 2) l'hétérogénéité spatiale de composition élémentaire de poussière en Patagonie et en Namibie, et 3) la solubilité élémentaire de poussière en Patagonie et en Namibie. Ces trois aspects sont les principaux enjeux pour modéliser les inventaires des émissions de micronutriments biodisponibles à partir de sources de poussière.La concentration en poussière mesurée en Patagonie montre une variation saisonnière avec un niveau plus bas en hiver. Les données météorologiques suggèrent que cette variation saisonnière est associée à la variation de l'humidité du sol dans les zones source plutôt qu'à la vitesse du vent. Des échantillons d'aérosol minéral ont été générés à partir des sols de Patagonie et de Namibie. La composition élémentaire des poussières diffère de celles des sols parents, en particulier en Namibie en raison de l'effet de dilution par le quartz dans les sols. Des compositions élémentaires varient spatialement aux échelles continentale et régionale en Patagonie et Namibie. Les variations de Ca et Mg sont les principales raisons conduisant à l'hétérogénéité spatiale de la composition élémentaire des poussières. Les solubilités élémentaires des aérosols minéraux de Patagonie et de Namibie augmentent avec l'acidité de la solution altérante. Les poussières riches en calcium présentent une solubilité plus élevée pour les éléments les plus solubles (Ca, etc.) en raison de la présence de carbonate. Le suivi de la concentration en poussières obtenu en Patagonie peut aider à mieux en quantifier les émissions dans la région subantarctique et ainsi à mieux contraindre les modèles. La base de données que nous avons obtenue sur les poussières et leur solubilité contribue également à l'évaluation des émissions d'éléments solubles dans la région Australe. / Mineral dust is considered to be an important supplier of micronutrient for the Southern Ocean where the primary production is limited by insufficient supply of micronutrients. Patagonia (South America) and Namibia (Southern Africa) are two main dust sources for the South Atlantic section of the Southern Ocean. Emission inventories of bioavailable micronutrients from these two regions regulate the final biological impact on marine ecosystem in the South Atlantic Ocean. This thesis is mainly focused on the investigation of 1) the atmospheric dust concentration and its temporal pattern in Patagonia, 2) the spatial heterogeneity of dust elemental composition in Patagonia and Namibia, and 3) the pH dependence of elemental solubility in Patagonian and Namibian dust. These three aspects are the key issues to model the emission inventories of bioavailable micronutrients from dust sources. Dust concentration measurements were conducted in Patagonia-Atlantic Coast and revealed a seasonal pattern of dust concentration with lower dust level in winter than the other three seasons. Meteorological records suggest that this seasonal pattern is associated with the variation of soil moisture in source areas rather than the recurrently high wind speed. Dust samples were generated from Patagonian and Namibian soils to investigate the elemental composition and the elemental solubility of source dust. Dust elemental composition differs to different degrees from their parents soils, particularly in Namibia due to the dilution effect of quartz in soil. Spatial variability of dust elemental composition was observed at both continental scale and regional scale in Patagonia and Namibia. Variations in Ca and Mg content are the main reasons for the spatial heterogeneity of dust elemental composition. Elemental solubility of Patagonian and Namibian dust increased with acidity of leaching solution. More soluble elements namely Ca, K, Mg, Mn, Sr and Ba showed much higher solubility in calcium-rich dust due to the presence of carbonate. The dust concentration record obtained in Patagonia may help to better quantify the dust emission in subantarctic region and to constrain dust models. Database of dust elemental composition and elemental solubility in Patagonia and Namibia also contributes to the evaluation of emission inventories of soluble elements from dust sources to the Southern Ocean.

Title: Dust trap for light scattering study Author: Petr Bartoň Department: Department of Surface and Plasma Science Supervisor: doc. RNDr. Jiří Pavlů, Ph.D., Department of Surface and Plasma Science Abstract: Light scattering on small grains is common interaction occurring wi- dely in space environments, including Moon surface, dusty nebulas or even the upper atmosphere of the Earth. For experimental measurements of light scatte- ring intensity profiles, we designed and constructed a unique experiment. Using so called acoustic trapping, we are able to capture a single dust grain (or small water droplet) in midair, to irradiate it with the laser beam, and to observe scattered light directly with the photodiode mounted on a precise goniometer. In the thesis, we present not only construction details, but also the first results, which help us to evaluate abilities of the experiment, and provide useful recommendations for further development of all dust-related experiments. Keywords: light scattering, acoustic trap, dust grain, scattering measurement 1

Master of Public Health / Department of Diagnostic Medicine/Pathobiology / John A. Pickrell / Beef cattle feed lots produce significant, local point source pollution of the atmosphere. The dusts generated in the CAFOs are complex mixture of fine and ultra fine particles, organic compounds, transition metals, and adsorbed toxic gases. Since each component is toxic in itself, we do not fully understand the relative importance of each component in the dust and their interactions to inducing inflammatory changes in the lung. We did extensive literature searches to understand the mechanism of dust toxicity in respiratory system. This lead to focusing on solubility of dust in lung simulant fluid, and in-vitro study of release of two common biomarkers of inflammatory processes IL-6 and IL-8 from lung epithelial cells. Various concentrations (1 to 50%) of the dust extract induced release of IL-6, and IL-8 from lung epithelial cell as indicators of pro-inflammatory changes (IL-6), and amplification and maintenance of inflammation (IL-8). IL-6 release had dose dependence; peak production was seen with 25% dust extract. IL-8 production went down as the concentration of the dust extract increased from 1% to 25%. However, 50% dust extract was cytotoxic to the cell leading to 10-15% cell viability. At non-cytotoxic concentrations for lung epithelial cells, production of IL-8 was reduced. These findings suggested that higher exposure concentration were required to initiate inflammation as indicated by IL-6 release. Lower exposure concentrations (1 and 5% extracts) were related to optimal release of IL-8 needed to amplify and maintain the inflammatory response. Inhibition of endotoxin didn't significantly change the pattern of IL-6 or IL-8 release from epithelial cells. This finding suggested that at least a portion of the mechanism by which particle induced cytokine release from the lung epithelial cells was not endotoxin dependent. Heating samples at 1200C for 5 minutes modified some of the toxic properties of the dust extracts but didn't completely detoxify it. We observed that longer incubation period was required to peak release for both IL-6 and IL-8. However, the higher concentration of sample (50% extract) found to be cytotoxic in non-heat treated sample was no longer cytotoxic and induced both IL-6 and IL-8 release from the lung epithelial cells. This result suggested that heat treatment could reduce some of the dust extract's cytotoxic properties. However, the extract's potential to induce peak cytokine release increased.

L'étude des plasmas poussiéreux est maintenant un domaine scientifique en plein développement qui attire l'attention d’une large communauté de scientifiques. Rappelons que le plasma poussiéreux est un plasma classique avec des particules injectées ou qui s’y sont formées dont les tailles peuvent atteindre quelques micromètres. Ces particules (poussières) peuvent acquérir de très grandes charges jusqu'à 103 à 105 charges élémentaires. Dans la littérature, il est également appelé plasma à phase condensée dispersée, plasma aérosol et aussi plasma complexe. Les plasmas poussiéreux sont d’un grand intérêt à la fois sur le plan pratique afin de trouver des solutions à des problèmes industriels et sur le plan scientifique fondamental afin d’élargir nos connaissances sur les phénomènes fondamentaux de la nature ainsi que les propriétés et la structure de la matière. En raison du fait que les particules de poussière macroscopique sont visuellement distinguables, le plasma poussiéreux est un objet d’étude unique pour l'étude de certaines propriétés physiques de la matière condensée, telles que les transitions de phase, la propagation d’ondes, les phénomènes de dislocation, les processus de transport, etc…On a constaté que dans de nombreuses technologies modernes mettant en oeuvre un plasma, en raison de l'interaction du plasma avec la surface des matériaux, des particules macroscopiques sont éjectées de celles-ci dans le plasma (dont les tailles peuvent être de quelques nanomètres jusqu'à quelques dizaines de micromètres). Il en résulte ainsi la formation d’un plasma complexe. Le nom le plus commun de ce plasma est un plasma poussiéreux. Un des aspects les plus intéressants est la formation dans certaines conditions de structures ordonnées (« cristaux ou liquide coulombiens »). Toutes ces structures plasmapoussière, se formant de façon naturelle, sont une contamination indésirable qui affecte négativement les propriétés physiques et mécaniques (micro dureté, résistance à la corrosion, etc.) des matériaux et dispositifs manufacturés.L'un des problèmes scientifiques et technologiques les plus importants, à l’heure actuelle, est la réalisation de la fusion thermonucléaire contrôlée. Dans ces conditions extrêmes se forment aussi au voisinage des parois des Tokamaks des poussières qui jouent un rôle fondamental : les données expérimentales récentes montrent que la présence de poussières dans le plasma peut affecter le temps global de confinement du plasma. L'utilisation du plasma poussiéreux dans la production de matériaux composites, à haute valeur ajoutée, est un nouveau champ d'applications. On peut citer à titre d’exemples, le traitement de surface de petites particules sphériques avec des revêtements, d’épaisseur nanométrique, déposés par plasma. Afin d'étudier les mécanismes de formation de particules homogènes ayant des propriétés désirées et une production stable, il est nécessaire de trouver les conditions optimales de production. Ainsi, l'étude des propriétés des plasmas poussiéreux et leurs diagnostics sont des tâches très importantes, à la fois pour les connaissances scientifiques fondamentales et que pour les aspects appliqués. / The study of the dusty plasma is now a developing scientific field, attracting the attention of scientists. Recall that the dusty plasma is conventional plasma with inserted or formed therein particles of condensed matter of microns sizes, the size of these particulates (dusts) can acquire very large charges up to 3 5 10 ¸10 of the elementary charges. In the literature, it is also named as plasma with a condensed dispersed phase, aerosol plasma. Dusty plasma is of interest both for the solution of the applied problems, and to expand our knowledge of the fundamental phenomena in nature, properties and structure of matter. Due to the fact that the macroscopic dust are visually distinguishable the dispersed plasma is unique comfort object for the study of some physical properties of condensed matter, such as phase transitions, transport processes, etc.It was found that in many modern plasma technologies, due to the interaction of the plasma with the material surfaces macroscopic particles from the material fall into the plasma (sizes are from micron fractions up to a few hundred microns). As result complex plasma is formed. The most common name of this plasma is dusty plasma. An interesting fact is that the dusty plasma forms under certain conditions the ordered structures ("plasma crystal", clouds, droplets). All of these plasma- dust structures are naturally occurring undesirable contamination and negatively affect on the physical and mechanical properties (microhardness, corrosion resistance, etc.) of the constructional materials.One of the most important scientific and technological problems is the realization of the controlled thermonuclear fusion. Formed in the wall region of the Tokamak dusty plasma can play a big role: recent experimental data show that the presence of dust in the plasma can affect the global energy confinement time. The use of the dusty plasma in the production of high composite materials is new field of application, for example, small spherical particles with nanocoating deposited in the plasma. In order to study formation of a homogeneous powder of the dust particles with desired properties and stability of its production, it is necessary to find the optimal conditions and time of production. Thus, the study of dusty plasma properties, their diagnostics are very important tasks, both from the scientific and applied aspects.

In South Africa, the ferrochromium industry produces approximately 100,000 t bag house filter dust and slurry, while the stainless steel industry produces 24,000 t of dust annually [17,39]. The toxic substances in these wastes potentially pose a threat to the environment and human health, especially Cr (VI) due to its toxic, carcinogenic, highly soluble and strongly oxidizing properties. Therefore, the existence and treatment of wastes from stainless steel and ferrochrome production remain a challenge and an issue of concern. The increase of environmental legislation globally and the trend towards sustainable development are drives for alternatives to landfill. In the present thesis, the characteristics, formation mechanisms, leachability and stabilisation of the Cr (VI)-containing electric furnace dust and filter cake were investigated using various techniques such as XRD, XRF, TG/DTA, XPS, SEM-EDS, FT-IR, Raman spectrometer and UV/Vis spectrometer. The electric furnace dust and filter cake are very fine particles. Stainless steel dust forms by the entrainment of charge materials, evaporation or volatilisation of elements and ejection of slag and metal by spitting or the bursting of gas bubbles. It was found that ferrochrome dust is formed by the ejection of slag and metals droplets from the electrode hole, the entrainment of charge materials, vaporisation as well as the formation and precipitation of compounds from vaporised species in the off-gas duct. Filter cake contains crystal phases (CaF2 and CaSO4 ) and metal rich amorphous phases. It is formed due to super saturation and precipitation. Leaching experiments on the wastes showed that Cr (VI) rapidly leaches out by distilled water. Bricks were produced by mixing wastes (stainless steel plant dust, ferrochrome dust and filter cake) and clay. The optimum sinter parameter was found to be 1100oC and 5 hours for a 50wt% SPD-50wt% AS mixture in the brick. The leachability of Cr(VI) is strongly influenced by the mass%CaO/mass%SiO2 ratio and alkali metal oxides content in the wastes. The emission factors from the stabilised wastes (SPD, FCD1, FCD2 and FC) are similar to those reported for the cement industry. Semi-dynamic leaching tests indicated that the predominant leaching mechanisms of chromium species are initial surface wash-off followed by matrix diffusion. / Thesis (PhD (Metallurgical Engineering))--University of Pretoria, 2007. / Materials Science and Metallurgical Engineering / unrestricted

The work conducted in this thesis examines the nature of circumstellar discs by investigating irradiance and polarization of scattered light. Two circumstellar discs are investigated. Firstly, H-band high contrast imaging data on the transitional disc of the Herbig Ae/Be star HD169142 are presented. The images were obtained through the polarimetric differential imaging (PDI) technique on the Very Large Telescope (VLT) using the adaptive optics system NACO. Our observations use longer exposure times, allowing us to examine the edges of the disc. Analysis of the observations shows distinct signs of polarization due to circumstellar material, but due to excessive saturation and adaptive optics errors further information on the disc could not be inferred. The HD169142 disc is then modelled using the 3D radiative transfer code Hyperion. Initial models were constructed using a two disc structure, however recent PDI has shown the existence of an annular gap. In addition to this, the annular gap is found not to be devoid of dust. This then led to the construction of a four-component disc structure. Estimates of the mass of dust in the gap (2:10x10⁻⁶ M⊙) are made as well as for the planet (≈1:53 x 10⁻⁵ M⊙ (0.016MJupiter)) suspected to be responsible for causing the gap. The predicted polarization was also estimated for the disc, peaking at 14 percent. The use of realistic dust grains (ballistic aggregate particles) in Monte Carlo code is also examined. The fortran code DDSCAT is used to calculate the scattering properties for aggregates which are used to replace the spherical grain models used by the radiative transfer code Hyperion. Currently, Hyperion uses four independent elements to de ne the scattering matrix, therefore the use of rotational averaging and a 50/50 percent population of grains and their enantiomers were explored to reduce the number of contributing scattering elements from DDSCAT. A python script was created to extract the scattering data from the DDSCAT output les and to apply a size distribution to the data. The second circumstellar disc investigated is the debris disc of the M dwarf star AU Mic. The disc was modelled, using the radiative transfer code Hyperion, based on F606W (HST) and JHK0-band (Keck II) scattered light observations and F606Wband polarized light observations. Initially, the disc is modelled as a two component structure using two grain types: compact silicate grains and porous dirty ice water. Both models are able to reproduce the observed SED and the F606W and H-band surface brightness pro les, but are unable to t the observed F606W degree of polarization. Therefore, a more complex/realistic grain model was examined (ballistic aggregate particles). In addition, recent millimetre observations suggest the existence of a planetesimal belt < 3 AU from the central star. This belt is included in the BAM2 model and was successful in fitting the observed SED, F606W and H-band surface brightness and F606W polarization. These results demonstrate the limitations of spherical grain models and indicate the importance of modelling more realistic dust grains.

Ever since the first observations of diffuse ultraviolet radiation by Hayakawa et al. (1969) and Lillie & Witt (1976), there has been an effort to understand its distribution and its origin. Unfortunately, because of the difficulty of the observations and the faintness of the background, many of the early observations were conspicuous more by their disagreements than by the light they shed on the topic. The state of the observations and theories before 1990 have been reviewed by Bowyer (1991) and Henry (1991). There has been significant progress in more recent years, particularly in the far ultraviolet (< 1200˚A) where Murthy et al. (1999) and Murthy & Sahnow (2004) have used spectroscopic data from the Voyager and FUSE (Far Ultraviolet Spectroscopic Explorer) spacecraft, respectively, to trace the radiation field over many different locations in the sky. There have also been a number of observations at longer wavelengths, most recently by the SPEAR instrument (Ryu et al. 2008, and references therein), but no systematic study of the UV background. The Galaxy Evolution Explorer (GALEX) offers us the opportunity to extend coverage of the diffuse background to a significant fraction of the sky with a sensitivity of better than 100 photons cm−2 sr−1 s−1 ˚A−1 . In this work, we will report on one such observation, that of the nebulosity observed near M82 by Sandage (1976). These GALEX observations are the first to probe the diffuse UV background at a spatial resolution comparable to other surveys of dust emission, notably the IR. We obtain a quantitative estimate of the Airglow, the Zodiacal Light and the Extragalactic Background Radiation. We have modelled the data with our monte carlo scattering simulation program, and inferred an estimate of albedo and scattering phase function parameter of the dust in Sandage region. In this thesis the methods and results of these deductions are explained in detail.

Despite increasing concern about the presence of heavy metals, pesticides and other toxins in indoor environments, very little is known about the physical and chemical composition of ordinary household dust. This study represents the first systematic investigation of the mineralogical composition of indoor dust in residential housing in Canada. Specimens of dust were obtained from homes in six geographically separate cities in the Province of Ontario: two located on the metamorphic and igneous rocks of the Precambrian Canadian Shield (Thunder Bay and Sudbury), the other four located on Palaeozoic limestone and shale dominated bedrock (Barrie, Burlington, Cambridge, and Hamilton). Forty samples of household vacuum dust were obtained. The coarse fraction (80 – 300 µm) of this dust was subjected to flotation (using water) to separate the organic components (e.g. insect fragments, dander), natural and synthetic materials (e.g. fibres, plastics) from the mineral residue. The mineral fraction was then analyzed using quantitative point counting, polarizing light microscopy, powder X-ray diffraction and scanning electron microscopy methods. Despite the great distances between the sampling localities and the distinct differences in bedrock geology, the mineral fraction of dust from all six cities is remarkably similar and dominated by quartz and feldspar, followed by lithic fragments, calcite, and amphibole. Some evidence of the influence of local geology can nevertheless be found. For example, a relatively higher proportion of sulphide minerals is observed in the two cities on the Canadian Shield where these minerals are clearly more abundant in the bedrock. Specimens from Sudbury, Canada’s largest mining centre located atop a nickel-sulphide mineral deposit, showed the highest sulphide contents. Quartz is the dominant mineral in all cities. All quartz grains have internal strain features and fluid inclusions that are indicative of a metamorphic-igneous provenance. In all cities, sand is used on the streets as an abrasive for traction during the icy winter season. This sand is obtained in all cases from local glaciofluvial deposits that were ultimately derived principally from the rocks of the Canadian Shield in the last Pleistocene glaciations that affected all of Ontario. Thus, tracking in sand is the most plausible mechanism by which quartz was introduced into these homes since sampling was done, in all cases, in the winter season. The results indicate that glacial deposits dominate the mineral composition of indoor dust in Ontario cities and that nature of the bedrock immediately underlying the sampling sites is relatively of minor importance.

Stars on the asymptotic giant branch (AGB) lose a significant fraction of their mass to their surroundings through stellar winds. As a result, they are surrounded by circumstellar shells of gas and dust. This stellar mass loss replenishes and enriches the interstellar medium (ISM) with the products of stellar nucleosynthesis, progressively increasing its metallicity and thereby driving galactic chemical evolution. In this thesis I present a comprehensive study of oxygen-rich (O-rich) AGB stars and red supergiants (RSG) observed with the Spitzer Infrared Spectrograph and Infrared Space Observatory Short Wavelength Spectrometer in the Milky Way, the Large and Small Magellanic Clouds, and Galactic globular clusters; focusing on the composition of the dust in the circumstellar envelopes surrounding these stars. Combining spectroscopic and photometric observations with the GRAMS grid of radiative transfer models to derive (dust) mass-loss rates, I detect crystalline silicates in stars with dust mass-loss rates which span over a factor of 1000, down to rates of ~10^{-9} Msun/yr. Detections of crystalline silicates are more prevalent in higher mass-loss rate objects, and our results indicate that the dust mass-loss rate has a greater influence on the crystalline fraction than the gas mass-loss rate, suggesting that thermal annealing of amorphous silicate grains is the primary formation mechanism of crystalline silicates in such environments rather than the direct condensation of crystalline silicates from the gas phase. I also find that metallicity influences the composition of crystalline silicates, with enstatite seen increasingly at low metallicity, while forsterite becomes depleted at these metallicities due to the different chemical composition of the gas. To trace the evolution of alumina and silicate dust along the AGB, I present an alternative grid of MODUST radiative transfer-models for a range of dust compositions, mass-loss rates, dust shell inner radii and stellar parameters. Our analysis shows that the AKARI [11]-[15] versus [3.2]-[7] colour is a robust indicator of the fractional abundance of alumina in O-rich AGB stars. From the modelling, I show that a grain mixture consisting primarily of amorphous silicates, with contributions from amorphous alumina and metallic iron provides a good fit to the observed spectra of O-rich AGB stars in the LMC. In agreement with previous studies, we find a correlation between the dust composition and mass-loss rate; the lower the mass-loss rate the higher the percentage of alumina in the shell. Finally, I present mid-infrared observations of the Local Group dwarf elliptical galaxy M32; where I find a large population of dust-enshrouded stars. These observations will act as a pathfinder for future observations with the JWST and SPICA.