|
|
Endocrine disruptors in reptiles
Semerád, Jaroslav ; Kratochvíl, Lukáš (advisor) ; Cajthaml, Tomáš (referee)
The ability of environmental contaminants to influence reproduction and development in vertebrates via disruption of the endocrine system is widespread. The mechanisms through which xenobiotics act can be complex and vary greatly among species. Reptiles are particularly good models for studying endocrine affecting compounds due to the fact that different species differ in modes of sex determination (genotypic sex determination or temperature-dependent sex determination) and parity (oviparity or viviparity). The sex of individual is often determined by egg incubation temperature, and exogenous application of steroid hormones and their analogs or steroidogenic enzyme inhibitors can reproduce effects of temperature. The lability of sex determination in some reptile species offers opportunity to use gonadal sex as a marker for effects of endocrine disrupting compounds (EDC), even for the effects of extremely low dosages of EDCs or EDC mixtures. The neonatal offsprings exposed to EDCs during embryogenesis provide yet another way to assess endocrine disruption, i.e., measurement of steroid hormone levels in their blood. In addition, many reptile species are highly aquatic, they use habitats near agricultural areas, where usage of pesticides is the most intense, and they are carnivores or scavengers. Therefore,...
|
|
|
Determination of endocrine disrupting compounds in wastewater in the Czech Republic.
Langová, Jana ; Cajthaml, Tomáš (advisor) ; Tylová, Tereza (referee)
Endocrine disruptors represent a group of chemical compounds that are able to negatively influence the hormonal system of vertebrates. Environmental Protection Agency (U.S.EPA) defines these compounds as exogenous substance or mixture that interferes with the synthesis, secretion, transport, binding, activity, or degradation of natural hormones. This can be observed at the level of the individual organism, its progeny, populations and subpopulations. All these changes have negative effects on homeostasis, reproduction, development or change the behavior of the affected animals. This work focuses on 7 endocrine disruptors - natural estron, 17β estradiol, estriol, and synthetic 17α-ethynylestradiol, irgasan (triclosan), 4-nonylfenol, bisphenol A in the influent and effluent of wastewater plants in the Czech Republic. The thesis contains an optimization of endocrine disruptors determination in wastewater, a preliminary screening to determinate concentration levels, 24 hours composite samples and monitoring of one selected wastewater plant during a day. The analytical procedure is based on filtration, solid-phase extraction (SPE), gel permeation chromatography (GPC), derivatization and gas chromatography coupled with mass spectrometry (GC/MS). Keywords: endocrine disruptors, wastewaters, Czech...
|
|
|
Monitoring of the occurence of Cyanobacteria in the Seč water resevoir by analytical methods
Štangelová, Pavla ; Tesařová, Eva (advisor) ; Cajthaml, Tomáš (referee)
Cyanobacteria are one of the oldest living organisms on the planet Earth. They are able to survive in different conditions under various conditions, almost in all habitats. The growth of cyanobacteria is affected by the amount of nutrients present in the environment, especially nitrogen and phosphorus, and by the climatic conditions. In larger quantities cyanobacteria began to spread in past few decades due to human activities. As a result of excessive use of fertilizers and washing nutrients from the soil is human-caused eutrophication and expansion of the so-called "water bloom". The presence of cyanobacteria in water is monitored using various analytical methods. The occurrence of cyanobacteria on the water reservoir Seč was determined by fluorimetric detection of pigment c-phycocyanin in samples of natural waters and compared with chlorophyll a content in these samples. Key words: cyanobacteria, c-phycocyanin, chlorophyll-a, fluorimetry
|
|
|
Removal of pharmaceutical products from water in wastewater treatment plants
Hamanová, Sabina ; Fuksa, Josef (advisor) ; Cajthaml, Tomáš (referee)
This thesis deals with removal of pharmaceuticals and personal care products by constructed wetlands (CWs) and compares its efficiency with removal efficiency of mechanical-biological conventional wastewater treatment plants (WWTP). In the first part the structure of WWTP is described, followed by the structure of CW. Special attention is also paid to the types of CWs, basic principles of function, physical-chemical parameters and vegetation. Below in literature review based on recent works is introduced characterization of selected pharmaceuticals with possible risks. The final section is focused on comparison of case studies from different countries in the world, oriented to the removal of organic polutants, especially PPCPs, from wastewater using various mechanisms including the use of constructed wetlands. Key words: PPCPs, constructed wetland, wastewater treatment plant, wastewater
|
|
|
Low-energy recycling of poly(ethylen terephthalate) waste
Slabá, Jitka ; Beneš, Hynek (advisor) ; Cajthaml, Tomáš (referee)
This thesis deals with a new low-energy method of chemical recycling of poly(ethylene terephthalate) (PET) using natural oils as reagents and microwave irradiation to accelerate depolymerization. The results of experiments with PET waste and castor oil, when the reaction mixture was heated in microwave reactor, showed that a complete depolymerization of PET chain has occured. Optimal conditions for the depolymerization PET were established: wt. ratio of PET / castor oil = 1 / 9.7, when the molar ratio of ester bonds of PET / hydroxyl groups of castor oil = 1 / 2.7, catalyst : zinc acetate at wt 1% from the PET mass, reaction temperature ranging from 235 to 245řC and the reaction time 60 min. Decomposition experiments also showed, that microwave irradiation accelerated decomposition of PET. Depolymerization reactionin MW reactor was complete at 6x shorter reaction time than the decomposition in the classically heated reactor. The results of analysis showed that the resulting product,the recyclate, was composed of unreacted castor oil and polyol products, that contained partially or fully esterified structural unit of PET, which were ended by ester-linked units of castor oil.
|
|
|
Application of renewable and recyclable raw materials for preparation of new polymers
Horák, Pavel ; Beneš, Hynek (advisor) ; Cajthaml, Tomáš (referee)
This thesis deals with optimalization of flexible polyurethane foam recycling with using of natural polyols based on rape seed oil and fish oil and it explores applications of depolymerized polyol product by formulations of new polyurethane materials. The experiments of depolymerisation showed that both tested natural oil (rape seed oil and fish oil) can be used as effective reagents for polyurethane recycling. Reaction conditions of depolymerisation were optimised with model flexible polyurethane foam and applied on waste foam from real conditions. Gain of depolymerisation is one-faze low viscosity (to 1500 mPa.s) liquid polyol products with content of hydroxyl groups ca 3 mmol/g. These polyols can be used for polymerisation of new materials. First application of recycled polyols was formulation of polyurethane foam systems. Through optimising of formula was prepared low-density semirigid foam containing 100 percentage of recycled polyol. Properties of these foams correspond to commercial foams. To prepare of homogenous cast polyurethane system based on recycled polyols it was necessary to add proper solvent, therefor extent of application has been lowered. On that account the systems were tested for study of polyaddition reaction and for following properties of the material. In these tests, the reactivity...
|
|
|
Carbamazepine - a study on the input to surface waters
Hromádková, Lucie ; Fuksa, Josef (advisor) ; Cajthaml, Tomáš (referee)
Anticonvulsant carbamazepine is a pharmaceutical, which is necessary to be taken continuously. Moreover carbamazepine and its metabolites are resistant to microbial degradation and sorption onto sludge in present municipal wastewater treatment plants. Therefore carbamazepine and its metabolites pass through WWTP and are constantly discharged to surface waters. Concentrations of carbamazepine measured in surface waters are too low to cause acute toxicological effects, but chronic toxicological effects or synergic effects with other pharmaceuticals cannot be excluded. Due to its physico-chemical properties carbamazepine is recalcitrant to degradation in surface waters and in soil, thus it infiltrates through bedrock to ground water. So far there is not enough information on behaviour and effects of metabolites of carbamazepine in surface waters. Besides carbamazepine, also other pharmaceuticals are nowadays often detected in surface and ground water and in the soil. Furthermore, as the population grows the consumption of pharmaceuticals increases as does their input into environment. However, given the risks, which pharmaceuticals in the environment entail, it is necessary to reduce additional input of these micropolutants into environment. As pharmaceuticals can enter the environment by many pathways, there...
|
|
|
New flame retardants in the environment
Ezechiáš, Martin ; Cajthaml, Tomáš (advisor) ; Kočí, Vladimír (referee)
In the recent years, many research articles focused on endocrine disrupting compounds in the environment. Some of these compounds are listed in a group named brominated flame retardants. However, only few articles investigated endocrine activity of several "new" brominated flame retardants. These chemicals such as 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) or bis(2-ethylhexyl) tetrabromophthalate (TBPH) are newly used due to ban of some previously most produced brominated flame retardant mixes. In this study, we used two recombinant yeast screens to measure estrogenic, androgenic, antiestrognic and antiandrogenic activities of some alternative brominated flame retardants. We also used ligninolytic fungi to investigate biodegradation of these compounds. Our results suggest, that 2,4,6-tribromophenol (TBP) may be a new environmental endocrine disruptor. This substance showed antiestrogenic and antiandrogenic activity in our tests. 1,2-bis(2,4,6- tribromophenoxy)ethane (BTBPE) had certain antagonistic activity too. In the biodegradation experiment, only three compounds showed significant degradation during the test period. No biodegradation have been observed for other compounds. In this study, we applied gas chromatography with mass spectrometry to analyze these "new" flame retardants. Method for gas...
|
|
|
Determination of white rot fungi Biomass during cultivation using analytical techniques
Vlasenkova, Tatiana ; Cajthaml, Tomáš (advisor) ; Frouz, Jan (referee)
The role of fungi in the soil ecosystems is well known. Exact determination of the fungal biomass is necessary for the understanding of their role in the cycle of soil nutrients, in the existing food chains of various animal types and in the soil aggregation. Bachelor's thesis is aimed at determination of white rot fungal (L. tigrinus, P. osteratus, I. lacteus, T. versicicolor) phospholipid-fatty acids and ergosterol (free and total) quantitative content with the subsequent comparison of the research results among themselves. Straw pellets were used as a sterile substrate for mushrooms. Their period of cultivation was 5, 8, 12, 16 and 20 days. The theoretical part describes methods for determining the microbial biomass, properties of ergosterol biosynthesis, lipids and fatty acids. Tools of gas and liquid chromatography, their use in determining the phospholipid-fatty acids and ergosterol in real samples are summarized. The experimental part of the procedure describes preparation of methylesters of fungi freeze-dried specimens that had previously been used in a biodegradation experiment. It just describes a method of determining fatty acids by gas chromatography, the extraction of ergosterol (free and total) and its subsequent determination using liquid chromatography. Based on the definition of...
|
|
|
Optimization of endocrine disruptors determination in wastewater treatment plant sludge and application of the method in environmental samples.
Medková, Jaroslava ; Cajthaml, Tomáš (advisor) ; Tesařová, Eva (referee)
Hormonaly active compounds in wastewaters represent nowdays a serious problem. Proceses currently used in watewater treatment plants (WWTP) are unefficient in removing these compounds from contaminated wastewaters. The compounds are supposed to sorb onto solid sludge elements and sediments. In this work seven endocrine disruptors were detected in the sludge samples from WWTPs. A new sensitive method for detection of seven selected endocrine disruptors (4-nonylphenol, bisphenol A, estriol, 17β-estradiol, estrone, 17α- ethynylestradiol, irgasan) was developed. The method is based on accelerated solvent extraction (ASE), gel permeation chromatography (GPC) and solid phased extraction. For final extract analysis, gas chromatography coupled with mass spectrometry (GC/MS) was used. The efficiency of this method was tested using artificially contaminated sludge and the method was used to analyse real samples from several WWTPs in Czech Republic. The effect of sludge age on detection of individual analytes was assessed as well. The concentrations of endocrine disruptors measured in the samples reached up to 1 µg/g. The results are comparable or higher then those reported in other works and they show the necessity of further research on endocrine disruptors in the environment.
|
guest ::
