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Toxic products of cyanobacteria with the focus on endotoxins
Eršilová, Kateřina ; Načeradská, Jana (advisor) ; Semerád, Jaroslav (referee)
Cyanotoxins are toxic products of cyanobacteria that cause problems (e.g. humans can experience unrecognised health effects), especially when they are overgrown. These cyanotoxins include the group of endotoxins, which includes lipopolysaccharides. Based on a literature search, it was found that the structure of these compounds consists of three chemical parts, Lipid A, a central oligosaccharide and O-Antigen. The structure is not the same for all cyanobacterial species and shows considerable variation. As far as the toxicity of lipopolysaccharides is concerned, it appears to be higher in Gram-negative bacteria than in cyanobacteria. The work in section 4.1 on toxicity states that microcystins do not play a major role in toxicity to Daphnia and that other substances from cyanobacteria will be toxic, while lipopolysaccharides are not excreted. In contrast, Chapter 6 states that lipopolysaccharides from Microcystis are not toxic to Daphnia and that other substances will be behind the toxicity. The thesis further considers that a large number of toxic substances coexist in water blooms, thus synergistic effects are at work in water blooms, hence the toxicity of cultures cultivated in laboratories is lower compared to the toxicity of natural cyanobacterial blooms. Water bloom contain many different...
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Perfluorinated and polyfluorinated substances in ski waxes
Hrubý, Martin ; Cajthaml, Tomáš (advisor) ; Semerád, Jaroslav (referee)
Perfluorinated and polyfluorinated compounds (PFAS) represent a group of thousands of anthropogenically produced substances. The strong bonding of carbon and fluorine gives these compounds unique properties, which have been used in ski waxes, among other applications. There is limited data on the specific PFAS used in wax production. This is due not only to the difficulty of analysis but also to the reluctance of manufacturers to disclose this information. The application of ski waxes has been associated with increased PFAS concentrations in the blood and some lung problems. Because of their persistence in ski areas, PFAS can be found in snow, soil, animals and plants. Although there is a gradual ban on the production and use of these substances, the issue of PFAS in ski waxes continues. This paper focuses on particular aspects of the issue. Key words: perfluorinated and polyfluorinated substances, PFAS, PFOA, ski waxes
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Possibilities of perfluorinated organic compounds (PFCs) removal in drinking water treatment plants and their occurrence in drinking water sources in the Czech Republic
Čermáková, Lenka ; Fialová, Kateřina ; Prokopová, Michaela ; Semerád, Jaroslav ; Petříček, Radim ; Pivokonská, Lenka ; Cajthaml, Tomáš ; Pivokonský, Martin
This summary research report was implemented within the project TAČR TJ04000212 program to support applied research ZÉTA „Possibilities of perfluorinated organic compounds (PFCs) removal in drinking water treatment plants and their occurrence in drinking water sources in the Czech Republic“. This report is addressed to water treatment plant operators and serves as a basic material for optimizing the coagulation / flocculation and adsorption process in water treatment. The report explains in detail the issue of removal of perfluorinated organic substances (PFCs) in water treatment, especially the process of adsorption in pilot plant conditions. This report will be used as a theoretical basis for the operation of the water treatment plant in Kutná Hora operated by the Water Management Company Vrchlice - Maleč, a. s.
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The mechanisms and efficiency of uptake of selected micropollutants by crops irrigated with reclaimed wastewater
Šrédlová, Kamila ; Semerád, Jaroslav ; Šereš, M. ; Mrvová, M. ; Rozkošný, M. ; Cajthaml, Tomáš
Water scarcity and the quality of fresh water are important global issues, which relate to all areas of human activity. One of the possible ways of reducing water consumption in agriculture is using treated (recycled) wastewater for irrigation. However, when applying recycled wastewater or biosolids to crops, it is necessary to monitor the content of micropollutants. The Summary research report describes the mechanisms of uptake of selected micropollutants (perfluorinated alkyl compounds and pharmaceuticals) by crops during automated irrigation with recycled wastewater. A detailed literature review complemented by experimental data describes micropollutant bioaccumulation in the fruits of several plants, which represent an exposure pathway for humans. Furthermore, the risk of human intake of micropollutants from crops potentially contaminated when grown using this technology is outlined
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Per- and polyfluoroalkyl substances in drinking water
Skalický, Daniel ; Načeradská, Jana (advisor) ; Semerád, Jaroslav (referee)
Per- and polyfluoroalkyl substances are synthetic organic compounds which, due to their physicochemical properties, have a high application in many consumer products such as aqueous film forming foams or detergents. In the context with their worldwide use and their long persistance in the environment their concentrations also have been detected in remote areas without direct surrounding sources including plants, animals and humans. PFAS concentrations in surface water and groundwater range from tens of ng/l, in the case of strong point sources to hundreds of ng/l. In the seas and oceans, PFAS concentrations are most often in the tens of pg/l due to dilution. The 2 most frequently discussed substances, perfluorooctanoic acid and perfluorooctanesulfonate, have been classified as a persistent organic pollutants because of their negative effects on human health. However, based on toxicological studies, many other substances in this group also appear to be toxic so some countries have set recommended limits for their reduction. Drinking waters have concentrations in the order of units up to tens of ng/l and therefore generally do not exceed the recommended values. However, in the area of point source of pollution, PFASs values are strongly elevated and therefore their identification and subsequent...
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Toxicity and environmental fate of nanoscale zerovalent iron
Semerád, Jaroslav
Nowadays, nanoscale zerovalent iron (nZVI) is a nanomaterial commonly used in remediation practice. Although worldwide applications of nZVI have shown its effectiveness in degradation and immobilization of a wide range of organic and inorganic pollutants, potential negative effects of nZVI on exposed organisms have not been sufficiently explored. To avoid possible environmental risks, understanding of the mechanism of nZVI toxicity and its overall effects on microbial populations indigenous to remediation sites is needed. The presented thesis summarizes current knowledge of nZVI toxicity, and, moreover, deals with the development and application of a new test for in vitro evaluation of acute toxicity caused by newly developed nZVI-based materials. Additionally, in this thesis, the risk associated with changes in the toxicity of the aforementioned materials during the aging process was examined. In the last part, the effect of several nZVI-based materials on microbial communities of a real contaminated soil was monitored and evaluated using artificial microcosms. In addition, in this part, the potential of nZVI and its derived materials in combination with a biostimulation step during nanobioremediation is outlined.
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Toxicity and environmental fate of nanoscale zerovalent iron
Semerád, Jaroslav
Nowadays, nanoscale zerovalent iron (nZVI) is a nanomaterial commonly used in remediation practice. Although worldwide applications of nZVI have shown its effectiveness in degradation and immobilization of a wide range of organic and inorganic pollutants, potential negative effects of nZVI on exposed organisms have not been sufficiently explored. To avoid possible environmental risks, understanding of the mechanism of nZVI toxicity and its overall effects on microbial populations indigenous to remediation sites is needed. The presented thesis summarizes current knowledge of nZVI toxicity, and, moreover, deals with the development and application of a new test for in vitro evaluation of acute toxicity caused by newly developed nZVI-based materials. Additionally, in this thesis, the risk associated with changes in the toxicity of the aforementioned materials during the aging process was examined. In the last part, the effect of several nZVI-based materials on microbial communities of a real contaminated soil was monitored and evaluated using artificial microcosms. In addition, in this part, the potential of nZVI and its derived materials in combination with a biostimulation step during nanobioremediation is outlined.
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