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Infusorial Earth - Reactive Admixture for Cement Composites
Zimmermann, Štěpán ; Žižková, Nikol (referee) ; Rovnaníková, Pavla (advisor)
The aims of this bachelor´s thesis are the properties and the use of diatomaceous earth as a partial replacement of cement in concrete. It provides information about the origin of diatomaceous earth, sedimentation of dead diatoms and variety of algae, including chemical and physical properties of the diatoms according to origin. The paper also contains information about significant deposits of diatoms, the manner and intensity of mining, including treatment of raw diatomaceous earth for further use. The main use of diatomaceous earth is in the filtration, which represents more than half of total consumption. An important factor for use in building is a high content of amorphous SiO2 and associated pozzolana activity of diatomaceous earth. The experimental part was carried out research on the influence of diatomaceous earth as pozzolanic admixtures on the properties of cement mortars. Tested specimens were obtained by adding 10% diatomaceous earth by weight of cement in the cement mortars. As admixtures were use three diatomaceous earth of different chemical composition, particle size and pozzolanic activity. The evaluated parameters were mortar density, flexural and compressive strength. The microsture of mortars were also observed. Test results were compared with those determined by reference mortars.
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Effect of partial replacement of Portland cement by diatomaceous earth on selected parameters of cement mortar
Rousková, Jana ; Sedlmajer, Martin (referee) ; Rovnaníková, Pavla (advisor)
The subject of this thesis is selected parameters cement mortars with partial replacement of Portland cement diatomaceous earth. This work provides information on the basic properties of diatomaceous earth and its deposits with a focus on deposit in Borovany. From the properties is very important pozzolanic activity due to the high content of amorphous silica of this soil. The main use of diatomaceous earth is in the area filtration and is used widely as a nutritional supplement. In the building industry, diatomite can be applied as an admixture to mortar and concrete, where it can, with its abilities, improve some physical mechanical properties. In the experimental part was diatomaceous earth, in its raw and calcined form, tested as admixture for cement pastes and mortars. The main criterion for evaluating these composites was bulk density, flexural and compressive strength. It was also investigated mineralogical composition, microstructure, freeze–thaw resistance and sulfate resistance.
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Diatoms as bioindicators for tracking freshwater salinization.
Severa, František ; Kopalová, Kateřina (advisor) ; Dobiáš, Jakub (referee)
The focus of this thesis is on the relationship of diatom (Bacilariophyta) communities to conductivity, and the utilization of this relationship for the monitoring of freshwater salinization. Salinization of freshwaters as a consequence of anthropogenic influences is emerging as a threat to many freshwater habitats due to increasing anthropogenic sources of salts (like use of de-icing salts on roads), wastewaters, and fertilizers. The problem is intensifying because salts are further concentrated through increased evaporation as a consequence to climatic changes. Salinization of ecosystems has a direct impact on the physiological processes of present organisms, and because the ability to adapt to this stress differs between organisms, results in the reorganization of communities. In this way, salinization can indirectly threaten ecosystem services that benefit mankind. Furthermore, salinization is a direct threat in terms of its influence on drinking water and crop irrigation. These forces also act on diatoms, which have long been used as bioindicators, and exhibit strong community links with conductivity. Like for other organisms, this tight relationship is caused by differences in adaptation mechanisms between species, which includes osmolytes, extracellular polymeric substances and adaptation of...
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Společenstva rozsivek oligo - mesotrofních rybníků Novohradských hor
HRUBÝ, František
This thesis focuses on diatoms of little studied water reservoirs of the Novohradské hory area. During the 2019, three seasonal samples were collected. At all five sampling sites various environmental parameters were measured. A total of 321 taxa were identified, a large proportion of which are classified as boreo-alpine, rare or indicative of very good water quality. The available data were used to calculate diatom indices and to determine the saprobity and trophy of the Novohradské hory reservoirs. The similarity of the communities of each sampling type was compared and discussed using the statistical program Canoco.
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Niche width of eukaryotic marine phytoplankton with respect to recent and future climate change.
Junková, Natálie ; Kulichová, Jana (advisor) ; Neustupa, Jiří (referee)
This paper describes the concept of niche breadth of photoautotrophic protists and attempts to introduce us to the basic concepts we may encounter when studying the ecological niche. The review clarifies what a niche is and its components fundamental and realized niche and presents some examples of organisms that are specialists or generalists. It uses diatoms, dinoflagellates and Haptophytes to describe how they can be affected by climate change. Since the number of environmental changes is steadily increasing, it is very difficult to predict the changes in the coexistence of generalists and specialists. The thesis presents some of the main methods used in measuring the width of the ecological niche of protists, which can be MaxEnt, ONE and the most frequently mentioned OMI (outlying mean index) method, which is described in more detail in the thesis. Given the focus of the thesis on photoautotrophic marine plankton, the most frequently mentioned organisms are diatoms, dinoflagellates and Haptophyta. Finally, I summarize the main ocean factors that could be affected by climate change, which are mainly pH, temperature, salinity or the amount of available nutrients (carbon, nitrogen, phosphorus, silicon and iron).
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Molecular variability and distribution of the Frustulia rhomboides species complex (Bacillariophyceae)
Urbánková, Pavla ; Kulichová, Jana (advisor) ; Bešta, Tomáš (referee)
Recent use of molecular methods to revisit taxonomically problematic diatom species revealed severe limitations of morphological species concept. Characterization of diatom species which was based solely on the morphology of their frustules often generated too broad species boundaries which inevitably lead to wrong conclusions about their ecology and distribution. Widespread opinion that many diatom species are cosmopolitan generalists resulted in a theory that dispersal of diatoms is not limited by geographical distance. However, a number of recent studies showed that dispersal of diatoms is governed by the same rules which matter for macroorganisms. Proposed master thesis addresses the topic of diversity and dispersal in diatom species complex Frustulia rhomboides sensu lato in Europe and New Zealand. Results suggest that: (1) although revealed molecular variability in this complex shows clear ecological and biogeographical signal, it is not correlated in morphology. This is another support to general need for adoption of different species concept in diatoms. (2) A considerably uneven ratio in species diversity of genus Frustulia found in ecological similar habitats in Europe and New Zealand supports the idea that diatom dispersal is limited and stressed the need for studies dealing with biogeography.
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Geometric morphometrics of diatom frustules.
Hubáčková, Kateřina ; Kulichová, Jana (advisor) ; Pichrtová, Martina (referee)
This bachelor thesis includes a theoretical and a practical part. In the theoretical part, I focused problematic parts of research of diatoms biology. I will discuss morphology of specific silica scale and its morphogenesis; life cycle, characteristic by the size diminution in vegetative phasis, and conception of taxonomy of these organisms which is rather complicated because of unclear species concept. Another part presents tools of geometric morphometrics which is rapidly developing method for investigation and quantification of biological shape. In the practical part, I present the results from own research. This experiment is preliminary study for diploma thesis and its purpose is to appropriate tools of geometric morphometrics and to present advantages of its methods. I will investigate morphological disparity of three strains of pennate diatoms cultivated in standard conditions studied by landmark methos. The aim of this study is to discover if small cells which have gone trough the long phasis of vegetative multiplication and are close to the sexual reproduction have diferent degree of morphological variability than the bigger ones just undergone by sexual process.
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Biogeography and habitat preferences for genus Luticola
Hanišová, Lucie ; Kopalová, Kateřina (advisor) ; Kulichová, Jana (referee)
The genus Luticola is one of the most species rich group belonging to the diatom class (Bacillariophyceace) containing 204 described species. The aim of this work is to summarize the available literature on the genus Luticola concerning its biogeography, habitat preferences of polar and temperate species, and their ecological treshold for important factors relating and forming their presence - pH and conductivity. Records suggest that the Luticola genus is presence worldwide, with higher species diversity in Europe, South America and the Antarctic region, the latter of which harbors a substantial amount of endemic species. In terms of habitat preference, records suggest that temperate species occur mostly in aquatic habitats, while polar species occupy terrestrial environments. Polar species also differ from temperate species by occupying narrower margin of pH values. However, both groups prefer low conductivity, and most species of the genus Luticola are located in environments with values up to 100 μS/cm. Key words: biogeography, conductivity, Luticola, pH.
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Diversity and relative biovolume of benthic diatom assemblages in relation to environmental conditions.
Šoljaková, Tereza ; Kulichová, Jana (advisor) ; Chattová, Barbora (referee)
iv ABSTRACT Benthic diatoms are due to a number of positive characteristics (such as high abundances, diversified communities, sensitive responses to environmental conditions, capturing long-term changes in the environmental conditions) currently the most commonly used bioindicators of the ecological status of freshwater ecosystems. However, due to problems associated with the use of traditional methods based on species composition (time-consuming identification, presence of species complexes, and requirements for calibration of water quality indexes for geographical regions) searching for alternative methods has been induced. The monitoring of the size structure of diverse diatom communities has been proposed as one of the methods. This approach would mainly eliminate the necessity of time-consuming determination of species. The main purpose of this thesis was therefore to determine the relationship between the size structure of benthic diatom communities, expressed as the relative biovolume, and selected environmental factors (pH, conductivity, habitat type) within freshwater lentic habitats. Furthermore, the variability of biovolume in dependence on environmental variables was compared with the change in species composition. If there would be a similar response pattern of both the biovolume and species...
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