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Using environmental tracers and other methods to estimate mean residence time and water flow in karst areas, Czech Republic
Bruthans, Jiří ; Krásný, Jiří (advisor) ; Bosák, Pavel (referee) ; Buzek, František (referee) ; Grmela, Arnošt (referee)
5. CONCLUSTON -Springs in 9 se|ected areas Were studied. Areas difÍer in geo|ogy (|itho|ogy, tectonics, intensity of metamorphism), recharge intensity (móuntainous coniřa lowland areas) and intensity of karst development differing by climatic conditions, geology -Concentrated recharge is only minor importance in most of areas compared to diffuse recharge -Most of the springs (90%) show predominant infiltration during last two decades with minor content (0-30%) of water infi|trated in sixties and sevénties of the twentieth century (based on tritium content). Analysis of lBO variations in spring water indicate that contribution of short residence time component (MRT in weekš to months) is about 5-20o/o of the spring yield -These numbers are similar or somewhat lower to results of MRT studies in other karst areas in the world (mostly vast carbonate bodies), which show mean residence time of water in karst aquifers to be from several years to hundreds of years -Volume of water in catchments of particular springs based on mean yield of spring and mean residence time is in orders of units to tens of millions m3 -|n studied karst areas SFo and CFCs can give re|iab|e resu|ts. |f no data from trítium are available the residence time must be considered as a minimum age. -Mean residence time of water percolating...
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Salt precipitation in subsurface zone of sandstone and other porous rocks and simulation of water transport and evaporation
Sommerová, Anna ; Bruthans, Jiří (advisor) ; Filippi, Michal (referee)
The main goal of this thesis was to find and compare salt-forming ions from samples of a subsurface zone of sandstone and other porous rocks. The surveyed samples came from different environments (humid and arid climate) from different locations in the Czech Republic, Jordan and the United States of America. Identification of various types of salt was based on evaluation of chemical analyzes of leached samples. Furthermore a laboratory experiment in which I used a fluorescein dye to observe the capillary rise and evaporation in unsaturated samples of sandstone was carried out. The salt content in the Czech Republic humid environment locations is generally lower than the one in foreign arid climate locations. Halit dominates in the locations Petra and Crystal Peak. In the other locations sulphate minerals dominate. The salts containing aluminum - alums were determined in the Czech Republic in the area of Czech Paradise and the surrounding. Relatively high concentrations of nitrate mineral nitratine were identified in the Devil's Pulpit location in Pilsen, the Czech Republic. From the observation of capillary rising experiments performed with artificially created honeycombs, I conclude that the height of the capillary rise is crucial for the transport of solution, and at a certain capillary height,...
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Tracer tests in karst with focus on new development in this field
Mareš, Jakub ; Bruthans, Jiří (advisor) ; Kůrková, Iva (referee)
The karst aquifers are formed by highly permeable conduits that allow very fast and concentrated flow. They can transport contaminants and endanger drinking water sources. Due to the large abundance of karstified carbonate rocks, it is necessary to prevent possible contamination. Tracer tests are used to determine the catchment and hydrodynamic parameters. These are constantly evolving to better simulate the transport of both dissolved and particulate substances and to minimize the risk of contamination. At present, particulate and colloidal tracers, such as DNA, are being developed to better simulate the movement of pathogenic bacteria. This bachelor thesis deals with this development. In the practical part, a tracer tests were carried out in the Bohemian Cretaceous Basin in the karst of the Jizera Formation, which utilized the obtained knowledge. There was injected NaCl and LiCl into a sinkhole in the settlement Borek and then conductivity was monitored and samples were taken at several places in the Vazovec stream, the spring of Bezednice and the springs near river Jizera. The tracer tests refuted the initial assumption that the water from the sinkhole flows directly into the Vazovec stream under the sinkhole and show one of the few found polyfurcations in the Czech Republic. Furthermore, it is...
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Comparison of hydraulic characteristics of cavernous weathering rocks forming tafoni and honeycombs
Studencová, Alžběta ; Bruthans, Jiří (advisor) ; Sněhota, Michal (referee)
Forms of cavernous weathering - tafoni and honeycombs - belong to long-term investigated and discussed phenomena in geology. The reason for the difference in size between few centimetres- long honeycombs and the several-metres-long tafoni has not been yet studied. In my master thesis I compared the hydraulic properties of rocks with developed honeycombs and tafoni. The research consists of field measurements (measurement of suction pressures and capillary water absorption using Karsten tube) and laboratory measurements on tafoni and honeycomb samples (retention curve measurement, capillary water absorption, water vapour diffusion rate and saturated hydraulic conductivity). I have been studing honeycombs from various sites in the Bohemian Cretaceous Basin and tafoni from three different sites: Carbon Arkoses near Kralupy nad Vltavou, Cambrian Sandstone in Petra (Jordan) and Tunnel Spring Tuff in Crystal Peak (Utah). The measurements showed that values of suction pressure are far higher inside tafoni than inside honeycombs. This observation corresponds to different retention curves of studied rocks: steeper retention curve for honeycomb's quartz sandstone than for fine-grained arkosic sandstones to arkoses with tafoni. In the other part of my research I have compared the properties of hydrophobic...
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Chemical composition of water from the unsaturated zone of selected sandstone outcrops
Paděra, Martin ; Bruthans, Jiří (advisor) ; Kamas, Jiří (referee)
The thesis is focused on the chemical composition of water from the unsaturated zone of sandstones on six localities in the Bohemian Cretaceous Basin and one site in the permocarbon basin. The subject of the study is mainly capillary water from several cm depth of sandstone exposure. Soil lysimeters, called rhizons, were tested to sample this water. Although rhizons are primarily designed for soil moisture sampling, under suitable conditions water abstraction has been successful. Vadose waters have low pH of 3.7-6.2, mainly caused by the infiltration of acid atmospheric precipitations, rich on sulphates and nitrates and other components, which are subsequently involved in the formation and crystallization of salts. Higher pH 5.7-6.2 show sites where rise in pH and different water chemistry are due to different geological conditions. Waters contain high concentrations of sulphates (4.9-763 mg/l), nitrates (2.2-109 mg/l), calcium (1.8-167 mg/l) and aluminium (0.1-4.7 mg/l) and compared to atmospheric precipitation are enriched for all dissolved ions. However, vadose waters sampled with rhizons do not differ from sandstone seeping waters. According to the results of geochemical modelling, waters are supersaturated with respect to quartz and chalcedony. The precipitation of main salts, such as gypsum...
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Reaction of granite with termal water and changes in permeability
Sysel, Ondřej ; Bruthans, Jiří (advisor) ; Vylita, Tomáš (referee)
The purpose of this thesis is to characterize the reaction of water with granite by describing the main factors, which control the weathering of granite. The effect of temperature on the dissolution of minerals turns to be the most significant. While the dissolution of feldspars occurs at lower temperatures, more resistant minerals such as quartz, biotite or muscovite are dissolved as well at higher temperatures. The presence of dissolved CO2 affects dissolution as well as precipitation of minerals. The research done in this thesis also reveals that flowing of water in granite is limited only to joints and fractures, which can be filled by the clay minerals originated from the weathering of feldspars. In some cases, an opposite phenomenon may occur when highly permeable channels start to grow on faults. Mineralogical analysis of the insoluble residue obtained by dissolving aragonite sinter from spring Vřídlo in Karlovy Vary was performed. Abundance of quartz in, feldspar, mica, clay minerals, oxides and hydroxides of iron and to a lesser extent, baryte, magnetite and other minerals were identified by scanning Electron Microscopy (SEM) and X-ray Powder Diffraction (XRD). In most cases, it may be assumed this these relics of granite were carried out to the surface by thermal water. The...
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