Fused glass beads as a sample preparation method for X-ray Fluorescence spectroscopy (XRF) were introduced in 1957 by Claisse; it soon became the preferred method to introduce oxide samples to the spectrometer, because heterogeneity, mineralogical and particle size effects are eliminated during the fusion process. Matrix effects are largely reduced by the resulting dilution. With the recent advances in XRF spectrometers, instruments with enhanced generator and temperature stability, improved sensitivity (even for light elements), and effective matrix correction software are available. Consequently, the largest proportion of analytical error results from the sample preparation step. Sampling error will always contribute the largest overall error but that is not the topic of this discussion. After more than 50 years of fused bead use in XRF analysis, certain matrices remain problematic. Although many fusion methods for chromite-, sulphide- and cassiterite-rich materials have been published, easily reproduced, routine methods for these still elude analytical chemists. Lengthy fusions at temperatures higher than 1100ºC are often prescribed for refractory materials and ores, and until recently one of the biggest challenges was a metal-bearing sample e.g. contained in slags or certain refractory materials. This study was conducted to identify and elucidate the reactions occurring in the formation of a lithium borate glass, but also between the lithium borate and oxides during glass formation. Different analytical techniques were used to investigate the reactions occurring during the fusion process based on theoretical glass-making principles. As a starting point, Thermo Gravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) were used jointly to evaluate the reactions occurring during the fusion of lithium borate glasses, and at a later stage, oxide/flux mixtures. When a different TGA instrument was used, Differential Scanning Calorimetry (DSC) was used in conjunction with the TGA. Observed reactions were modelled in a muffle furnace to produce identical material in larger quantities, and this material was then investigated using X-ray Powder Diffractometry (XRD), Raman Spectroscopy and Electron Microprobe Analysis (EPMA). The most enlightening result from the TGA/DSC results was the large mass loss above 1050 ºC. Literature often prescribes prolonged fusions at elevated temperatures for certain fusions, but it was proved beyond reasonable doubt that this practise causes volatilisation of the flux and leads to erroneous analytical results. The next analytical technique applied to the flux and flux/oxide samples was XRD. Where pre-fused fluxes were investigated, the XRD data served as confirmation of the glassy state of the pre-fused flux as a broad humpy scan indicative of an amorphous material was seen in stead of a diffractogram with sharp, well defined peaks. After heating to above the temperature of re-crystallisation, the phases present could be identified from the diffractogram. Provisional results using the in-situ, high temperature stage point towards the possibility of using this technique to great effect to investigate the presence of different phases formed at high temperatures. Flux-oxide mixtures were measured on the high temperature stage and after cooling a new phase was observed indicating that new phases formed during a fusion reaction. As the heating stage is slow-cooled, the chance of crystallisation in the glass is good, providing the possibility for investigating this formation of new phases at elevated temperatures further with a more suitable heating element that will contain the material. Raman spectroscopy was subsequently used to gain information about the bonds within the flux. Pure lithium tetraborate and lithium metaborate fluxes were analysed as well as flux oxide mixtures. The vibrations could not be predicted from first principles as band broadening occurs in glasses that makes theoretical predictions very difficult. The data obtained was compared to similar studies in literature and good agreement was found. In oxide-flux mixtures definite new bands were observed that was not part of the flux or oxide spectrum. EPMA results allowed calculation of the maximum solubilities of an oxide in a specific flux. It was done using Cr2O3 and ZrO2 and compared well with experimental values obtained from literature. The microscope images revealed some new insights into the theory of XRF fusions. It could clearly be seen that dissociation of the minerals in the sample occurred, thus proving that no mineralogical effects exist in a fused glass bead, and it could be observed that the flux oxide mixture devitrify when over saturated. / Dissertation (MSc)--University of Pretoria, 2010. / Chemistry / unrestricted

Sigtuna is one of the first settlements in Sweden considered to be a proper town. Taking over Birka´s function as a central trading hub when it was founded in the late 10th century AD, Sigtuna was characterized by its early connection to Christianity, and many churches were built there. The foundations of one of these medieval stone churches and its churchyard lie beneath Sigtuna museum’s plot on the block S: t Gertrud 3. However, the full extent of this church and churchyard as well as its foundation date and function is not fully known. The over-arching purpose of this study is to achieve a better understanding of this church’s function. This will be done by geochemically analysing soil samples taken from the museum plot under which the churchyard is located. The first aim of this study is to establish the extent of the churchyard. During excavations carried out between 1990- 1991 in the neighbouring block Urmakaren, archaeologists discovered the remains of King Olof Skötkonung’s minting house along with various finds, notably two lead pieces with imprints of coin stamps. The second aim of this study is to see if traces of these metalworking activities can be detected on the museum plot. The third aim is to see how the church and churchyard related to the minting house on a spatial plane.

Heavy metals, such as mercury (Hg), have a long residence time in the atmosphere and can be transported long distances and deposited in the Arctic via wet and dry deposition. Still, there are few studies on the complex mercury cycle and how different plant groups absorb Hg. In this study, I investigated if and/or how Hg concentrations differ between different humus soils in tundra vegetation types in Alaska and Abisko. I also investigated the potential changes in Hg deposition with increasing elevation in Abisko (500, 750, and 1000 m a.s.l). Further, a comparison between the analyzing methods XRF (X-ray fluorescence) and HF digestion was evaluated to investigate if XRF is a suitable method for analyzing heavy metals in the humus layer of soils. To achieve this, humus soil samples from four different vegetation types in Alaska and two from Abisko were analyzed with a Hg analyzer (DMA-80 Direct Mercury Analyzer) and a handheld XRF. The results show that Hg concentration was highest in heath vegetation for Alaska and Abisko. Meanwhile, increasing elevation had no impact on Hg concentration in general, nor was there a difference within the two vegetation types. The comparison between HF digestion and XRF resulted in a positive linear relationship for P, Fe, and Al. The results highlight that Hg concentration differs between humus soil due to different vegetation types, although there is no clear explanation to the distribution of Hg in aboveground vegetation. Litterfall and precipitation may influence Hg concentrations with elevation, and the XRF samples need to be replicated multiple times to avoid errors, as my study shows.

Målet med det här projektet var att undersöka huruvida en XRF signalkan förbättras genom att filtrera denna genom en tunn skiva avantingen aluminium, bly eller molybden. För att undersöka dettaanvändes programmet MCNP6.2 för att simulera strålningsspektrat fråntvå olika strålkällor; ett röntgenrör av Wolfram som kan genererafotoner med energier så höga som 120keV, och ett radioaktivt Co-57preparat. Projektet visade på att detta är möjligt, och även attaluminium är att föredra i de flesta fall då det förbättrar XRFsignalenavsevärt, utan att behöva vara varken väldigt tjockt, elleroapplicerbart tunt. Utöver detta är aluminium även billigare samtlättare än de båda andra materialen. Även molybden kunde filtrerastrålningen på ett användbart vis när en Co-57 källa används. Dockbehövde filtret vara extremt tunt, därför rekommenderas ej molybden.Projektets slutsats var att ett 0,3 mm tjockt aluminiumfilterförbättrar signalen som mest när röntgenröret användes som källa,medans ett 0,8 mm tjockt aluminiumfilter fungerar bäst för Co-57 källan.

It is well established that mining and metallurgy on a larger scale in Sweden originated in Bergslagen. The historical mining district Garpenberg in Bergslagen presently show the oldest signs of mining in Sweden (2300 BP) based on a study of a lake sediment profile from Gruvsjön. This report focuses on the mining history around Finnhytte-dammsjön (Garpenberg) to assess when the first signs of mining occur, what type of ore was being mined, when the first sign of modern mining was observed and when the lake development stabilized. A complete sediment profile was sampled from Finnhytte-dammsjön which was analyzed with X-Ray Fluorescence spectroscopy. An age-depth model was created for the sediment profile using the introduction of Norway Spruce (Picea Abies) pollen and by matching known peaks in historical atmospheric pollution of Pb as points of reference. Increased Fe concentrations (3.6 ± 0.4 %) compared to deeper sections (2.6 ± 0.2 %) was observed which were well correlated with Ca (R2: 0.73). Indications of increased Fe concentrations relative to Ca was found from 2000 BP. Stabilization of LOI550 and changes in sediment geochemistry indicates that a steady state in the lake development was reached around 4600 BP. Major increases in Zn and Cu that was presumed to be from modern mining was observed from 1800 CE. This report concludes that Fe-rich dolomite or skarn was mined from 500 CE with indications that mining started as early as 2000 BP.

Heavy metals, such as mercury (Hg), have a long residence time in the atmosphere and can be transported long distances and deposited in the Arctic via wet and dry deposition. Still, there are few studies on the complex mercury cycle and how different plant groups absorb Hg. In this study, I investigated if and/or how Hg concentrations differ between different humus soils in tundra vegetation types in Alaska and Abisko. I also investigated the potential changes in Hg deposition with increasing elevation in Abisko (500, 750, and 1000 m a.s.l). Further, a comparison between the analyzing methods XRF (X-ray fluorescence) and HF digestion was evaluated to investigate if XRF is a suitable method for analyzing heavy metals in the humus layer of soils. To achieve this, humus soil samples from four different vegetation types in Alaska and two from Abisko were analyzed with a Hg analyzer (DMA-80 Direct Mercury Analyzer) and a handheld XRF. The results show that Hg concentration was highest in heath vegetation for Alaska and Abisko. Meanwhile, increasing elevation had no impact on Hg concentration in general, nor was there a difference within the two vegetation types. The comparison between HF digestion and XRF resulted in a positive linear relationship for P, Fe, and Al. The results highlight that Hg concentration differs between humus soil due to different vegetation types, although there is no clear explanation to the distribution of Hg in aboveground vegetation. Litterfall and precipitation may influence Hg concentrations with elevation, and the XRF samples need to be replicated multiple times to avoid errors, as my study shows.

By analyzing the texture, composition and chemical composition of loess soils, the reconstruction ofpast climate regimes is enabled, which can improve our understanding of current and future climatechange. Properties such as grain size and composition, mineralogy, organic matter and chemicalcomposition can provide information about which environmental factors were present during thedeposition of the sediment, which can lead to a detailed picture of the climate history of a site. Researchon loess soils in the polar regions is particularly valuable because its climate is most rapidly affected byglobal warming. The purpose of the study has therefore been to understand and convey new data to thepaleo-climate around the Arctic by examining and analyzing loess soil sequences at a depth between 0and 175 cm from Adventdalen, Svalbard. In this study, the samples are analyzed with XRF (X-rayfluorescence) and LOI (Loss of Ignition). XRF is used to find out the mineral composition of the soils,while LOI is used to find out the percentage of organic content and carbonates.Data from the oldest part of the stratigraphic section indicate a sharp increase in weathering, from acooler period about 3000 years ago to a warming until about 2000 years ago. Weathering intensitiesderived from Na/Al-based indices show relatively frequent oscillations throughout the section, but arestable from about 100-70 cm. The high and stable weathering values during this period can probably beattributed to the Medieval Warm Period, which coincides with the relative dating of the site. Datacollected from the LOI shows a clear trend throughout the section, with a decrease in organic matterfrom 3000 BC to the present.

The intent of this thesis is to analyze obsidian artifacts from Chiquiuitan, Guatemala to see if the samples can be traced to known obsidian sources in the Maya region based on their unique chemical elements. Another aspect of this analysis is to determine the accuracy and validity of the Handheld XRF instrument on small and irregular obsidian samples. Furthermore, sourcing analysis allows researchers to acquire information about trade, exchange, and acquisition patterns of the material and gives researchers indications to prehistoric, social, and economic features.

No description available.

No description available.