| 1. |
- Berger, Tobias, et al.
(författare)
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Fluoride abundance and controls in fresh groundwater in Quaternary deposits and bedrock fractures in an area with fluorine-rich granitoid rocks
- 2016
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 569, s. 948-960
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on fluoride (F-) concentrations in groundwater in an area in northern Europe (Laxemar, southeast Sweden) where high F- concentrations have previously been found in surface waters such as streams and quarries. Fluoride concentrations were determined over time in groundwater in the Quaternary deposits ("regolith groundwater"), and with different sampling techniques from just beneath the ground surface to nearly -700 min the bedrock (fracture) groundwater. A number of potential controls of dissolved F- were studied, including geological variables, mineralogy, mineral chemistry and hydrology. In the regolith groundwater the F- concentrations (0.3-4.2 mg/L) were relatively stable over time at each sampling site but varied widely among the sampling sites. In these groundwaters, the F- concentrations were uncorrelated with sample (filter) depth and the water table in meters above sea level (masl), with the thicknesses of the groundwater column and the regolith, and with the distribution of soil types at the sampling sites. Fluoride concentrations were, however, correlated with the anticipated spatial distribution of erosional material (till) derived from a F-rich circular granite intrusion. Abundant release of F-from such material is thus suggested, primarily via dissolution of fluorite and weathering of biotite. In the fresh fracture groundwater, the F- concentrations (1.2-7.4 mg/L) were generally higher than in the regolith groundwater, and were uncorrelated with depth and with location relative to the granite intrusion. Two mechanisms explaining the overall high F- levels in the fracture groundwater were addressed. First, weathering/dissolution of fluorite, bastnasite and apophyllite, which are secondary minerals formed in the fractures during past hydrothermal events, and biotite which is a primary mineral exposed on fracture walls. Second, long water-residence times, favoring water-rock interaction and build-up of high dissolved F- concentrations. The findings are relevant in contexts of extraction of groundwater for drinking-water purposes. (C) 2016 Elsevier B.V. All rights reserved.
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| 2. |
- Berger, Tobias
(författare)
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Fluoride in surface water and groundwater in southeast Sweden : sources, controls and risk aspects
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis is to determine the sources, controls and risk aspects of fluoride in surface water and groundwater in a region of southeastern Sweden where the fluorine-rich 1.45 Ga circular Götemar granite (5 km in diameter) crops out in the surrounding 1.8 Ga granites and quartz monzodiorites (TIB rocks). The materials of this thesis include both primary data, collected for the purpose of this thesis, and a large set of secondary data, retrieved from the Swedish Nuclear Fuel and Waste Management Co., the Swedish Geological Survey and the Kalmar County Council. A characteristic feature of the area is high fluoride concentrations in all kinds of natural waters, including surface waters (such as streams) and groundwater in both the Quaternary deposits (regolith groundwater) and bedrock fractures (fracture groundwater). A number of potential sources and controls of the high fluoride concentrations were investigated, including a variety of geological, mineralogical, mineral-chemical and hydrological features and processes. For the stream waters and regolith groundwater, high fluoride concentrations were correlated with the location of the Götemar granite. This finding is explained by the discharge of fluoride-rich groundwater from fractures in the bedrock and/or the release of fluoride due to the weathering of fluorine-bearing minerals in the Quaternary deposits; however, the Quaternary deposits had considerably lower fluoride concentrations than the underlying bedrock. The high fluoride concentrations in the fresh fracture groundwater (up to 7.4 mg/L) in the TIB-rocks are proposed to be the result of long residence times and the alteration/dissolution of fluorine-bearing primary and secondary minerals along the fracture walls. In terms of risk aspects, this thesis shows that fluoride can add to the transport and inorganic complexation of aluminium in humic-rich, acidic streams. Additionally, 24 % of the children in households with private wells in Kalmar County were assessed to be at risk of excess fluoride intake based on the WHO drinking water guideline value (1.5 mg/L). However, the risk increased significantly when instead the US EPA reference dose (0.06 mg/kg-day) was used, both when all relevant exposure pathways were taken into account as well as water consumption alone. Hence, it is shown that the risk of an excess intake of fluoride is strongly dependent on the basis for evaluation.
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| 3. |
- Berger, Tobias, et al.
(författare)
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Fluorine geochemistry of quaternary deposits in a nemo-boreal catchment with elevated dissolved fluoride in surface waters and groundwater
- 2016
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Ingår i: Journal of Geochemical Exploration. - : Elsevier BV. - 0375-6742 .- 1879-1689. ; 170, s. 148-156
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on fluorine (F) concentrations and solid-phase speciation in Quaternary deposits, including till, sorted sediments (gravel, sand, clay/silt) and organic-rich soil types, in an area in southeast Sweden underlain by 1.8 Ga granites and quartz monzodiorites with moderate F concentrations (0.11-0.13 wt%) and an outcrop (5 km in diameter) of 1.45 Ga granite (the Gotemar granite) with high to very high F concentrations (0.38-0.54 wt%). Eighteen <1 to 5 m thick profiles were sampled both upon and in the vicinity of the Gotemar granite. The F concentrations in the Quaternary deposits were considerably lower than in the underlying fresh bedrock, with the overall highest concentrations in glacial clay having values up to 660 ppm. A contributing factor to the low F concentrations in the till, as compared to the fresh rock, is release and leaching of fluoride (F-) during alteration of biotite and amphiboles to secondary minerals. Sequential chemical extractions showed that the F in the Quaternary deposits exists mainly in the residual fraction, and also to a substantial extent in phases extractable with hydroxylamine hydrochloride in the till and in phases extractable with Na pyrophosphate in the organic-rich soil types. These features indicate that after release via alteration of primary minerals, F- has to a significant extent been scavenged by Fe/Al (and perhaps Mn) oxyhydroxides in the till and by labile organic matter in the organic soil types. The high F- concentrations previously reported for stream waters and regolith groundwaters in the area are due to weathering and leaching of the Quaternary deposits and discharge of fluoride-rich waters from underlying bedrock fractures. (C) 2016 Elsevier B.V. All rights reserved.
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| 4. |
- Berger, Tobias, et al.
(författare)
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The impact of fluoride on Al abundance and speciation in boreal streams
- 2015
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Ingår i: Chemical Geology. - : Elsevier. - 0009-2541 .- 1872-6836. ; 409, s. 118-124
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Tidskriftsartikel (refereegranskat)abstract
- The impact of fluoride on the abundance and speciation of aluminium (Al) was investigated in three boreal streams characterised by overall high concentrations of fluoride and dissolved organic matter. Stream-water sampling was carried out several times a year for at least 4 years, and a chemical equilibrium model (Visual MINTEQ) was applied in order to model the proportion of colloidal and organically/inorganically complexed Al in the waters. The Al concentrations in filtered (0.45 μm) water samples were inversely correlated with pH, and reached values up to approximately 1. mg/L during low pH conditions (pH < 6.0). In a stream with high fluoride concentrations, as compared to a similar stream with only moderately elevated fluoride concentrations, the Al concentrations were consistently elevated. For the stream with high concentrations of fluoride and Al, the model predicted both high concentrations and proportions of Al-fluoride complexation. This prediction indicates that high fluoride levels contribute to raise both the Al abundance and the ratio of inorganic to organic Al complexation in stream water. In contrast, for another stream with high fluoride concentrations and consistently high (near neutral) pH, there was no evidence of fluoride affecting Al concentration or complexation. These results show that it is important to focus future studies on the role of high levels of dissolved fluoride on both the speciation and the toxicity of Al in stream water.
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| 5. |
- Holstein, Tobias, 1984-
(författare)
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Towards a Multi-OS Architecture for Consistent User Interface Experience
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Vehicles have greatly changed over the last decades. Originally, they were used as a means of transportation, and their drivers were solely engaged in the driving task. In modern cars the user, i.e. the former driver, has to interact with many different systems, which provide access to different domains, such as vehicle functions (monitoring speed, fuel consumption), safety related features, comfort and infotainment. Advancements in technologies make it possible to cope with the increasing amount of features, as for example the introduction of input and output modalities that allow new ways of interaction, such as touch(-screens), voice control or gesture recognition. In the end a user has to interact with all systems through the overall user-interface. This requires a high usability and a consistent look and feel in order to provide a consistent user experience.On the technology side, developers have to cope with rising complexity, dependencies and inter-connections of about 80 different embedded systems in a premium car. The introduction of multi-core systems opened the way for new approaches, like Multi-OS environments. There multiple operating systems are consolidated onto a single hardware platform by the use of hardware/software virtualization. This allows for example to run real-time operating systems (RTOS) for safety critical cluster applications next to a general purpose operating system (GPOS) for infotainment applications. This also poses new challenges, such as the contradiction between a clear separation meant to reduce complexity, dependencies and to mitigate the risk of interferences, and interconnections that are required to create a composited user-interface.In this thesis, the challenges of compositing heterogeneous systems in an automotive context are explored. Current approaches are studied and the contradiction of separation and interconnection is explained. Based on this, concepts are introduced and software architectures are proposed, which can be used to implement composited user interfaces for Multi-OS environments. Furthermore, an application prototype that is used to verify the proposed software architecture in regard of graphical user-interfaces, called HTML-UI-Compositor, has been implemented. The HTML-UI-Compositor also provides a simple way of compositing graphical user-interfaces through the adaptation of a web browser engine, which allows well-known standard web development tools and languages to be used to create composited user-interfaces. Those are the first steps towards a Multi-OS architecture that supports a consistent user interface experience.
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| 6. |
- Schulz, Ava, et al.
(författare)
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A sorrow shared is a sorrow halved? A three-arm randomized controlled trial comparing internet-based clinician-guided individual versus group treatment for social anxiety disorder.
- 2016
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Ingår i: Behaviour Research and Therapy. - : Elsevier. - 0005-7967 .- 1873-622X. ; 84, s. 14-26
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Tidskriftsartikel (refereegranskat)abstract
- A growing body of evidence suggests that internet-based cognitive behavioural treatments (ICBT) are effective to treat social anxiety disorder (SAD). Whereas the efficacy of clinician-guided ICBT has been established, ICBT in a group format has not yet been systematically investigated. This three-arm RCT compared the efficacy of clinician-guided group ICBT (GT) with clinician guided individual ICBT (IT) and a wait-list (WL). A total of 149 individuals meeting the diagnostic criteria for SAD were randomly assigned to one of three conditions. Primary endpoints were self-report measures of SAD and diagnostic status taken at baseline, after the twelve-week intervention and at six-month follow-up. Secondary endpoints were symptoms of depression, interpersonal problems and general symptomatology. At post-treatment, both active conditions showed superior outcome regarding SAD symptoms (GT vs. WL: d = 0.84-0.74; IT vs. WL: d = 0.94-1.22). The two active conditions did not differ significantly in symptom reduction (d = 0.12-0.26, all ps > 0.63), diagnostic response rate or attrition. Treatment gains were maintained at follow-up. The group format reduced weekly therapist time per participant by 71% (IT: 17 min, GT: 5 min). Findings indicate that a clinician-guided group format is a promising approach in treating SAD.
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| 7. |
- Yu, Changxun, 1983-, et al.
(författare)
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Geochemical controls on dispersion of U and Th in Quaternary deposits, stream water, and aquatic plants in an area with a granite pluton
- 2019
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 663, s. 16-28
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Tidskriftsartikel (refereegranskat)abstract
- The weathering of U and/or Th rich granite plutons, which occurs worldwide, may serve as a potentially important, but as yet poorly defined source for U and Th in (sub-)surface environments. Here, we assessed the impact of an outcrop of such granite (5 km in diameter) and its erosional products on the distribution of U and Th in four nemo-boreal catchments. The results showed that (i) the pluton was enriched in both U and Th; and (ii) secondary U and Th phases were accumulated by peat/gyttja and in other Quaternary deposits with high contents of organic matter. Movement of the ice sheet during the latest glaciation led to dispersal of U- and Th-rich materials eroded from the pluton, resulting in a progressive increase in dissolved U and Th concentrations, as well as U concentrations in aquatic plants with increasing proximity to the pluton. The accumulation of U in the aquatic plants growing upon the pluton (100–365 mg kg−1, dry ash weight) shows that this rock represents a long-term risk for adjacent ecosystems. Dissolved pools of U and Th were correlated with those of dissolved organic matter (DOM) and were predicted to largely occur as organic complexes. This demonstrates the importance of DOM in the transport of U and Th in the catchments. Large fractions of Ca2UO2(CO3)30(aq) were modeled to occur in the stream with highest pH and alkalinity and thus, explain the strongly elevated U concentrations and fluxes in this particular stream. In future climate scenarios, boreal catchments will experience intensified runoff and warmer temperature that favor the production of hydrologically accessible DOM and alkalinity. Therefore, the results obtained from this study have implications for predicting the distribution and transport of Th and U in boreal catchments, especially those associated with U and/or Th rich granite plutons.
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