Thesis (MPH.) --University of Limpopo, 2006 / Studies conducted on people who reside next to dust producing mines and industries show major health risks. Air pollutants from the mine and industries are inhaled by exposed miners and people who live in the vicinity (Steenland, 1995). Aim The aim of the study is to investigate non-occupational exposure to silica dust at gaMaja village in Polokwane, Limpopo Province. Methodology Study design For this study a cross sectional descriptive study design was used. Study site The study was conducted at gaMaja village near Polokwane in the Limpopo Province Sampling A total sample of 200 villagers participated in the present study. vi Data Collection Two hundred questionnaires were used to collect survey data and were coupled with four dust deposition gauges. The four gauges were mounted at four different positions in the village and were left for six hours. Data Analysis Questionnaires were analysed using SPSS computer software to determine silica-related illnesses and indicators of exposure to silicosis susceptibility. Dust samples from dust deposition gauges were analysed using a Varian 110 atomic absorption spectrometer for determination of silicon. Results The majority of both male and female participants reported that they do not wheeze (81.4%) or bring out phlegm from their chest (71.4%) as compared to those who reported episodes of cough (48%). Gauges were able to identify exposure to a particular pollutant, silica dust, and were successful.Discussion Data from questionnaires revealed that villagers do not show signs and symptoms related to silicosis, however, that does not rule out infection in a long run. The results from dust samples that were collected reveal that there are traces of silica (crystabolite) in the village of gaMaja. Dust samples were collected during normal production at the mine in the middle of summer. Conclusion Findings from this study show that people residing next to dust producing mines and industries are at high risk of health hazard. Mining companies and policy makers should take note of the findings while planning preventive strategies for reduction of air pollutants.

Expansive soils occurring in arid and semi-arid climate regions of the world cause serious problems on civil engineering structures. Such soils swell when given an access to water and shrink when they dry out. Several attempts are being made to control the swell-shrink behavior of these soils. Soil stabilization using chemical admixtures is the oldest and most widespread method of ground improvement. In this study, waste limestone dust and waste dolomitic marble dust, by-products of marble industry, were used for stabilization of expansive soils. The expansive soil is prepared in laboratory as a mixture of kaolinite and bentonite. Waste limestone dust and waste dolomitic marble dust were added to the expansive soil with predetermined percentage of stabilizer varying from 0 to 30 percent. Grain size distribution, consistency limits, chemical and mineralogical composition, swelling percentage, and rate of swell were determined for the samples. Swelling percentage decreased and rate of swell increased with increasing stabilizer percentage. Also, samples were cured for 7 days and 28 days before applying swell tests. Curing of samples affects swell percentages and rate of swell in positive way.

An investigation of the high spectral resolution signatures and radiative forcing of tropospheric aerosol in the thermal infrared was conducted. To do so and to support advanced modeling of optical properties, a high spectral resolution library of atmospheric aerosol optical constants was developed. This library includes new optical constants of sulfate-nitrate-ammonium aqueous solutions and the collection of a broad range of existing optical constants for aerosol components, particularly mineral optical constants. The mineral optical constants were used to model and study infrared dust optical signatures as a function of composition, size, shape and mixing state. In particular, spherical and non-spherical optical models of dust particles were examined and compared to high spectral resolution laboratory extinction measurements. Then the performance of some of the most common effective medium approximations for internal mixtures was examined by modeling the optical constants of the newly determined sulfate-nitrate-ammonium mixtures. The optical signature analysis was applied to airborne and satellite high spectral resolution thermal infrared radiance data impacted by Saharan dust events. A new technique to retrieve dust microphysical properties from the dust spectral signature was developed and compared to a standard technique. The microphysics retrieved from this new technique and from a standard technique were then used to investigate the effects of dust on radiative forcing and cooling rates in the thermal IR.

No description available.

Ph.D. (Geography) / The focus of Aeolian research has mainly been on wind-blown dust from desert and arid areas. Numerous dust emission schemes have been developed over the years aimed at accurately estimating dust emission rates from various soil types and land use surfaces. Limited research has been done on wind-blown dust from smaller area sources – such as mine tailings and ash storage facilities. Lately, the concern about the environmental and health impacts, caused by dust from mine tailings storage facilities and ash disposal sites, has become more prominent, calling for better methods in determining dust emissions and their related impacts. This thesis established a practical approach for wind-blown dust emissions estimation and dispersion modelling from mine waste and ash storage facilities for the purpose of legal compliance assessment. Extensive research on the physics of wind erosion has been done over the past decade, compelling the re-evaluation of previously applied techniques. The latest and most widely applied dust emission schemes are evaluated to determine, through systematic testing of parameterisation and validation, using empirical mine waste and coal ash data, a best-practice prescription for quantifying wind-blown dust emissions and determining effects on a local scale using commercially available dispersion models. The applicability of two dust-flux schemes, (one developed by Marticorena and Bergametti (1995) and the simplified Shao 2004 scheme, as reported in 2011) for the quantification of wind-blown dust emissions, were tested using site specific particle size distribution data, bulk density and moisture content from six gold- and one platinum- tailings storage facilities and from two ash storage facilities. The availability of the required input parameters and the uncertainty associated with these parameters, were tested. The dependency of the Shao et al. (2011) model on plastic pressure (P) and the coefficient cy, both of which are not easily determined, added to the uncertainty of the emission rates. In this study, P and cy were both interpolated using the range limits provided by Shao (2004) for natural soils. By calculating P, using the salt and calcium carbonate content, similar values were obtained. The minimally disturbed dust fraction, as required by the Shao et al. (2011) scheme were derived from particle size distribution analysis but found to be more representative of the fully disturbed particle size faction (𝜂fi) and therefore needed to be corrected to represent the minimally disturbed particle size faction (𝜂mi) through the application of a correction factor, CF𝜂mi. Specific attention was given to the quantification of the threshold friction velocity (u*t) and the threshold velocities (u*), and how these two parameters relate to each under variable wind speed and time durations. This was tested using sub-hourly averaged meteorological data, one set reflected 5-minute intervals and the other 10-minute intervals. Dependent on the frequency and strength of the sub-hourly wind gusts, the resulting dust-flux rates were found to vary significantly when based on hourly averaged wind data in comparison with 5- and 10-minute wind data. Dispersion models are useful tools in air quality management. Whereas ambient monitoring provides actual ambient concentrations for specific pollutants at set locations, atmospheric dispersion models can be used to simulate any number of pollutants and determine the impacts at any location within the modelling domain. These dust-flux schemes of Marticorena and Bergametti (1995) and Shao et al. (2011) have been coupled with the US EPA regulatory Gaussian plume AERMOD dispersion model for the simulation of ground level concentrations resulting from wind-blown dust from mine tailings facilities. For this study, two Case Studies were evaluated; one included two of the gold mine tailings and the second focused on the platinum tailings. Simulated ambient near surface concentrations were validated with ambient monitored data for the same period as used in the model. For the Marticorena and Bergametti (1995) dust-flux scheme, only z0 had to be adjusted to provide a good fit with measured data – whereas the Shao et al. (2011) scheme resulted in significantly higher concentrations, resulting in an over-prediction of the measured data. By applying the correction factor, CF𝜂mi, to the minimally disturbed dust fraction, the predicted concentrations improved considerably. The coupling of the dust-flux schemes with a regulatory Gaussian plume model provided simulated ground level PM10 concentrations in good agreement with measured data. The best correlation was found under conditions of high wind speeds when the prevailing wind was from the direction of the tailings storage facility. This thesis demonstrates that simulated impacts from complex source groups can be performed, within an acceptable range of certainty, using widely applied dust-flux schemes. These dust-flux schemes, developed primarily for large-scale desert and arid areas, have been demonstrated to be applicable also to small-scale sources, of the order of 1 km2, and can be coupled to regularly available dispersion models for impact evaluations of wind-blown dust. The value of this improved approach to the mining and mineral processing industries are substantial, allowing for more accurate health risks and adverse environmental assessments from wind-blown dust from large material storage piles, a source category that has hitherto been difficult to quantify.

Cette thèse est consacrée à l’étude de l’évolution des propriétés physico-chimiques d’un panache d’aérosols désertiques nord africains au cours de son transport vers l’Europe du Nord. Cet épisode de mai 2008 est considéré comme l’évènement de transport d’aérosols désertiques le plus important de ces cinq dernières années observé sur le continent européen. La propagation de ce panache a été étudiée en combinant des moyens d’observation (sols, aéroportées, spatiales) au modèle de recherche Méso-NH. L’analyse des processus de dépôt a révélée que les quantités éliminées de l’atmosphère par dépôt sec et humide représentent respectivement 7 et 40 % de la quantité émise. Les valeurs d’épaisseur optique mesurées à 440 nm sur l’Europe variaient de 0.1 à 0.8, avec un maximum proche de 1 au-dessus des Pays-Bas. Au-dessus de cette région, les aérosols désertiques sont principalement situés entre 2.5 et 5.2 km d’altitude, mais aussi proche de la surface. La concentration en aérosols désertiques au sein de ces deux couches a été estimée respectivement à 350 et 450 ��g.m-3. Néanmoins, les mesures réalisées ne présentaient pas les caractéristiques optiques habituellement associées à la présence d’aérosols désertiques. En particulier, la présence d’une importante dépendance spectrale a été observée le 30 mai à proximité de Cabauw. L’exploitation des simulations ont permis de montrer que cela résultait d’une efficacité de lessivage plus importante du mode grossier. La présence d’aérosols désertiques coïncide avec une augmentation de la concentration des noyaux de condensation (CCN). Nos résultats suggèrent que le mélange entre le panache et les aérosols de pollution d’origine anthropique a conduit à une augmentation des capacités hygroscopiques des aérosols désertiques. Ce travail de recherche confirme ainsi que les conditions physico-chimiques de l'atmosphère régissent le cycle de vie des aérosols. / This thesis focuses on the evolution of the dust physical and chemical properties through a case of long-range transport of Saharan dust over Northern Europe. This episode of May 2008 is considered as the strongest event of Saharan dust transport to Europe observed since these last five years. This spread of dust is investigated by combining observations (ground-based, airborne, satellite) and the meso-scale model Méso-NH.The analysis of the removal processes reveals that the amounts lost by dry and wet deposition represent 7 and 40 % the total dust emitted respectively. The observed aerosol optical thickness ranged from 0.1 to 0.8 at the wavelength of 440 nm, with a maximum value close to 1 is found over the Netherlands. Over that site, the dust layer was mainly located between 2.5 and 5.2 km, moreover dust was also present at 0.5 km. The concentration of dust inside these two layers is estimated to 350 and 450 ��g.m-3 respectively. Nevertheless, the usual optical characteristics of Saharan dust were not observed. In particular, the scattering coefficient measurements revealed a strong spectral dependence observed during the 30th May, close to Cabauw. The analysis of the numerical experiements revealed that this was due to high precipitation scavenging efficiency for the coarse mode. The presence of Saharan dust coincides with an increase of the cloud condensation nuclei (CCN) concentration. Our results suggest that the mixing processes between the Saharan dust and anthropogenic particles have led to an increase of the Saharan dust hygroscopic properties. Thus, this thesis confirms that physical and chemical conditions of the atmosphere govern the life cycle of dust.

Eiskristalle fördern die Bildung von Niederschlag und beeinflussen die optischen Eigenschaften einer Wolke. Damit spielen sie eine maßgebliche Rolle für das Wetter und Klima unseres Planeten. In der Atmosphäre entstehen Eiskristalle entweder durch homogene oder durch heterogene Eisnukleation. Letzteres wird durch ein sogenanntes eisnukleierendes Partikel (INP) katalysiert. Bisher ist nur wenig über die speziellen Eigenschaften eines INP bekannt und die Vorhersagbarkeit über die Eisnukleationsfähigkeit verschiedener Materialien ist somit stark limitiert. Im Rahmen dieser Arbeit wurde das Immersionsgefrierverhalten von Birkenpollen, verschiedenen Mineralstäuben sowie Mischungen aus Mineralstaub und Birkenpollen Material untersucht. Ziel dieser Untersuchungen war, das Gefrierverhalten der verschiedenen Substanzen zu quantifizieren sowie deren Bedeutung für die Atmopshärische Eisnukleation besser zu verstehen. Das Gefrierverhalten eisaktiver Birkenpollen Makromoleküle konnte in dieser Arbeit erstmals unter atmosphärisch relevanten Bedingungen quantifiziert werden. Ein Vergleich zweier Birkenpollen Proben mit unterschiedlicher Herkunft demonstrierte die Abhängigkeit der Gefriereigenschaften der Birkenpollen von der geografischen Breite. Es wurden zwei unterschiedlich eisaktive Makromoleküle identifiziert, welche beide bei Temperaturen oberhalb −20°C aktiv sind. Das Gefrierverhalten unterschiedlicher Mineralstaubpartikel wurde hinsichtlich ihres K-Feldspat Anteils verglichen. Dabei zeigte sich, dass der K-Feldspat Anteil das Gefrierverhalten der Mineralstaubpartikel kontrolliert. Außerdem konnte gezeigt werden, dass eine Beschichtung mit Schwefelsäure die Eiskeimfähigkeit von K-Feldspat stark herabsetzt. In der Atmosphäre sind Partikel, welche sowohl aus mineralischen als auch aus biologischen Komponenten bestehen sehr wahrscheinlich. Um zu demonstrieren wie sich ein Mineralstaubpartikel verhält, wenn es mit biologischem Material gemischt wird, wurde in dieser Arbeit das Gefrierverhalten von Mischpartikeln bestehend aus Illit-NX und Birkenpollen Material untersucht. Es konnte gezeigt werden, dass die eisaktiven Makromoleküle der Birkenpolle ihre Eisaktivität beibehalten, auch wenn sie an einem Illit- NX Partikel angelagert sind. Die Mischpartikel zeigen somit das selbe Gefrierverhalten, wie reine Birkenpollen Partikel. Dies zeigt die bisher unterschätzte Bedeutung von biologischem Material für die atmosphärische Eisnukleation. / It is known that ice crystals in clouds play an important role for climate and weather as they influence precipitation initiation and radiative forcing. Ice formation in clouds occurs either through homogeneous or heterogeneous ice nucleation. For the latter case an ice nucleating particle (INP) catalyzes the freezing process. The knowledge about the properties which make a particle act as efficient INP is still limited. As a consequence, the ice nucleation ability of different materials has to be examined by quantitative experimentation. In the framework of the present thesis, the immersion freezing behavior of birch pollen material, different mineral dust particles and internal mixtures of mineral dust and birch pollen material was studied to improve our understanding of the importance of these species for the atmospheric ice nucleation. A quantification of the freezing behavior of ice nucleating active (INA) birch pollen macromolecules under atmospherically relevant conditions was done for the first time. Furthermore, the freezing ability of two birch pollen samples with different local origin was compared. It could be shown that birch pollen are able to produce at least two different types of INA macromolecules, which are both ice active in a temperature regime above −20◦ C. It became obvious that one of the macromolecules is favorably produced in higher latitudes, which indicated the dependence of the freezing properties of birch pollen from their local origin. Concerning mineral dust particles the present thesis demonstrated that the freezing ability of different K-feldspar containing mineral dust proxys like Arizona test dust, kaolinite and illite-NX, is controlled by their K-feldspar content. Furthermore, it was shown that K-feldspar loses its good freezing ability after surface modification with sulfuric acid. As internal mixtures of mineral and biological components are very likely in the atmosphere, the freezing ability of such mixed particles has been investigated in the present thesis. For illite-NX particles which were mixed with birch pollen material, it could be shown that the birch pollen macromolecules maintain their freezing ability when being adsorbed to a mineral dust particle. As a result, the affected mineral dust particle initiates freezing exactly like a birch pollen particle. For atmospheric application this means that it is likely that the ascription of mineral dust to the atmospheric INPs is, at least to a certain extent, due to unnoticed attached ice nucleating biological material.

This project aims to investigate neural network systems as an effective tool for the in-space captured dust impact signal detection. Cosmic dust is the nanometre to micrometre fine-sized particles that exist in the interplanetary region. They originate from comets, asteroids, the planets and their moons and rings, or even the interstellar region. Some are visible to the human eye as, for instance, zodiacal light. However, most dust grains are sparsely spread in space and can be captured only by in-situ measurements. One method to capture such a small grain in space utilizes the whole spacecraft’s surface as a detector and uses the onboard electric field measurement to identify their impact signals. Those signals are highly non-linear and often identified manually. A neural network system is a possible solution to improve dust detection for a massive dataset.The European Space Agency’s (ESA) solar physics mission, Solar Orbiter, has electric field measurement (PWI) onboard and can detect the micrometeorite impact signals near the sun. We used two types of PWI datasets to investigate the use of neural network systems in interplanetary dust detection.We first used a pre-trained neural network to the High-Frequency (HF) Time Domain Sampler (TDS) data to adapt further to the new dataset. We were able to obtain good detection classifications as the previous work except for the data with high time resolution, which has not been used for the pre-training before. Therefore, we implemented extra preprocessing to enable classification of data with high time resolution.We trained and tested another neural network on another type of PWI dataset, that is, the Low-Frequency (LF) continuous data. This data type is different from the TDS data type in that it does not come in packets but as a continuous data stream covering an entire day and has a lower sampling frequency. Which required different preprocessing-procedures.Based on the two types of neural network analysis we use above; we have finally been able to investigate the characteristics of dust distribution in the interplanetary region. Using the statistical analysis obtained by the SolO/PWI between April of 2020 to Mars of 2023, among others, the following characteristics have been found: The neural network analysed dust impact rates show a similar trend as onboard processed dust impact rates. Dust impact amplitude was found to be correlated to distance from the sun, spacecraft velocity, and spacecraft radial velocity. The impact rate increases as the spacecraft travels sunward. Much of the dust appears to have speeds lower than the spacecraft. Overall, from this study, we concluded that the HF neural network is better in dust signal detection, but the LF network can be improved. Shortcomings and possible improvements are presented in the conclusions.

Call number: LD2668 .T4 1979 D465 / Master of Science

Detta produktutvecklingsarbete har utförts i samarbete med företaget, Pegil Innovations AB. Syftet med projektet var att utveckla en hanteringslösning för processat avloppsslam (damm) på boendeplattformar i offshore industrin. Processen för projektet kombinerade Front-End processen med detaljer från Set-Based Concurrent Engineering. Projektet inleddes med en förstudie och användarstudier för att få djupare kunskap inom ämnet. Detaljer som var viktigt för projektet samlades i en kravspecifikation som användes som stöd genom hela processen. Därefter följde en idégenerering för att utforska lösningar. Från denna framkom fem idélösningar som utforskades vidare genom en fördjupning och jämförelse mot en ny kravspecifikation. Denna var en uppdaterad version av den första för att bättre reflektera vilka krav och önskemål som kunde ställas på idélösningarna. När idélösningarna hade utforskats utfördes en ny idégenerering som ledde till att idélösningarna utvecklades till två koncept. Det fördjupades kring koncepten och dessa jämfördes mot kravspecifikationen. Sedan följde ytterligare en idégenerering för att undersöka hur koncepten kunde förbättras. Slutligen utfördes ett konceptval. Resultatet blev en påse, som fästs runt en stos, som fylldes med damm och sedan sögs luften ur (för att bilda ett undertryck) samt att påsen värmeförseglades. Personalen kan sedan enkelt bära iväg påsen för att kassera denna tillsammans med dammet. / This product development project has been carried out in cooperation with the company, Pegil Innovations AB. The purpose of the project was to develop a management solution for processed sewage sludge (dust) on accommodation vessels in the offshore industry. The process of the project combined the Front-End process with details from Set-Based Concurrent Engineering. The project started with a preliminary study and user studies to obtain deeper understanding regarding the relevant knowledge area. Details that were of importance to the project was gathered in a specification that was used through the entire process as a support. Then an idea generation was preformed, to discover and explore different solutions. From the idea generation five different idea solutions were created. These five solutions were explored deeper and then compared to a new specification. The specification was an updated version from the first one to better reflect what conditions the idea solutions should meet. When the idea solutions were explored, a new idea generation was performed, resulting in two concepts. These concepts were explored deeper and then compared to a new specification. Then followed another idea generation to explore how the concepts could be improved. In conclusion to the project a concept was chosen. The result was a plastic bag which was fastened around a spigot, that was filled with the dust and then the air was withdrawn (to create a vacuum). Then the opening of the plastic bag was heat sealed. The personal could then easily carry the bag to discard this together with the dust.