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Mercury dynamics in soil systems: A comprehensive study on natural and anthropogenic sources using elemental and isotopic analysis
Domingues Vieira, Alda Maria ; Vaňková, Maria (advisor) ; Navrátil, Tomáš (referee) ; Doušová, Barbora (referee)
Human activities (in)directly affects the biogeochemical cycle of mercury (Hg) in the environment. However, many aspects of Hg behaviour remain poorly understood. In this thesis, three different case studies addressed two main themes: i) the influence of climate change on Hg re-emissions from fire-affected soils and ii) the fate and behaviour of Hg in soils contaminated by non-ferrous ore mining and smelting. The first study investigated total Hg concentrations in uncontaminated soil profiles and Hg pools in organic horizons to estimate the fire-induced Hg emissions from the soil during a wildfire in Portugal. Fire-undisturbed soil profiles displayed higher Hg concentrations (156 μg kg-1) in the organic horizons, decreasing with depth in the mineral horizons. The Hg pool in these organic horizons was estimated at 10.6 g ha- 1. We calculated the wildfire released up to 133 g of Hg from the forest floor within the 12.5 ha burned area, emphasising its dual role in Hg (im)mobilisation in a region increasingly affected by extreme fire-prone weather events. In the second study, Hg stable isotope ratios and solid phase speciation data were determined in soil profiles contaminated by historical Hg-Fe mining and smelting in Czechia (Jedová Hora). The total Hg soil concentration reached up to 17.8 mg kg-1....
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Elimination Voltammetry with Linear Scan: Advantages and Disadvantages
Navrátil, Tomáš ; Trnková, L. ; Hrdlička, Vojtěch ; Li, X.
Elimination voltammetry with linear scan (EVLS) represents an almost traditional\nmathematical method that helps to obtain additional and detailed information about the recorded\nelectrochemical signals and therefore, to better understand the analyzed systems. Although it\nhas been substantially developed and expanded during its existence of more than a quarter of a\ncentury and has found many areas of application, like any other mathematical and experimental\nmethod, it exhibits several advantages and disadvantages. In this contribution, we summarize\nits strengths, weaknesses, opportunities, as well as threats.\n
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Analytical Derivatization for Identification of Electrochemical Oxidation Products of Fentanyls
Barták, P. ; Skopalová, J. ; Jerga, R. ; Štolbová, D. ; Navrátil, Tomáš ; Langmaier, Jan
Analytical derivatization and GC-MS analysis were employed for the identification of main\nproducts from the electrochemical oxidation of fentanyl derivatives. Chemical derivatization\nprovides proof of the chemical reactivity of functional groups in oxidation products and serves\nfor the chemical conversion of target compounds into the second series of derivatives to confirm\nthe identification of particular products. Using the direct GC-MS analysis of oxidation products,\nderivatization of aldehydes with cysteamine and derivatization of amides by acidic hydrolysis\nand subsequent reaction with ethylchloroformiate, phenylacetaldehyde, and Nphenylpropanamide\nwere unambigously identified as oxidation products from fentanyl,\nthiophen-2-ylacetaldehyde, and N-phenylpropanamide from sufentanil, and\nphenylacetaldehyde and 2-furanilid from furanylfentanyl.
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Vliv vybraných podmínek prostředí na klíčení semen plevelů
Navrátil, Tomáš
The aim of this thesis was to find out the influence of temperature on germination seeds of Galium aparine. There were suggested labour experiments. In the first experiment seeds were exposed to various temperatures. In the second experiment was monitoring the influence on germination of seeds which were exposed to frost for a specific time. Best germination had seeds at 6 °C. In the second experiment the best germination had seeds that were exposed to frost for five days. Average total germination of all seed were 65.8%. Results have been written to the tables and processed to graphs. Evaluation of the work is adduced in discussion.
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Carbon - based electrodes: From detection of biologically significant compounds to application in neurodegenerative diseases
Jarošová, Romana ; Zima, Jiří (advisor) ; Vyskočil, Vlastimil (referee) ; Navrátil, Tomáš (referee)
CARBON BASED ELECTRODES: FROM DETECTION OF BIOLOGICALLY SIGNIFICANT COMPOUNDS TO APPLICATION IN NEURODEGENERATIVE DISEASES By Romana Jarošová Carbon is a truly remarkable element that is essential to life on Earth, and its unique properties have made it an indispensable component in an astonishingly diverse array of applications. Whether serving as a fuel source or as a key component in electronic devices, carbon's ability to exist in different forms, each with their distinct physical and chemical properties, contributes to its widespread and continued use. Electrode production is one of the areas where carbon found its significant use. This thesis represents a unique combination of fundamental and applied electrochemistry using carbon-based electrodes. It explores a wide range of topics, from evaluating electrode microstructure as a critical factor affecting its electroanalytical behavior, to the use of carbon- based electrodes in Alzheimer's disease (AD) research. The first part of this Thesis focuses on the electrochemical performance of carbon-based electrodes with distinct microstructures. Specifically, this section discusses two novel electrode materials: boron-doped diamond and nitrogen-incorporated tetrahedral amorphous carbon. The microstructure of each electrode was investigated, and the...
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Analytical approaches to study group interactions of azole pesticides with important biological active compounds
Kovač, Ishak ; Jaklová Dytrtová, Jana (advisor) ; Száková, Jiřina (referee) ; Navrátil, Tomáš (referee)
This dissertation presents a developed capillary electrophoresis method for analysing residues of triazole fungicides (TAF) from real samples ("Sweet cherry" tomato - Solanum lycopersicum L) and shows its potential application in environmental analysis. The developed method was validated in-house and characterised by a relatively short analysis time and low cost with sufficient LOD and LOQ. As an additional part of this dissertation, which rose from the tomato plants' treatment with TAF, we studied the impact of triazole fungicides on plant development and their impact on biologically active compounds. Determination of TAF residues from tomato peel carried out with capillary electrophoresis. Capillary electrophoresis is a versatile technique with minute amounts of sample required, with high efficiency in separating small molecules, such as selected TAF. The developed method, cyclodextrin-modified micellar electrokinetic chromatography, accomplished a baseline separation of the TAF mixture from tomato peel. The optimal conditions for separation were in the background electrolyte comprised of phosphoric acid and Tris (100 mM concentration, respectively), 20% v/v methanol, with apparent p[H+ ] 4.8. The constituents of the mixed micellar pseudo-stationary phase were ionic detergent sodium dodecyl...
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Continuous monitoring of anthraquinone-based anticancer drugs by amperometric technique
Skalová, Štěpánka ; Fischer, J. ; Barek, J. ; Navrátil, Tomáš ; Krejčí, J. ; Kučerová, R. ; Vyskočil, V.
This contribution is focused on the development of electroanalytical methods for the monitoring of anthraquinone-based anticancer drugs in physiological solution by combination of liquid-flow system and dialysis catheter, possibly inserted into blood circulation of patients. For this purpose, amperometric detection with dual glassy carbon electrode was developed and derivate of these drugs, anthraquinone-2-sulphonate, was used as a model compound. Two different flow rates of carrier solution (physiological solution) were tested (specifically, 1 and 5 mu L min(-1)) and the dependence of peak currents of anthraquinone-2-sulphonate on its concentration was verified
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A study of the behavior of selected metals in affected environments using an isotopic approach
Santos Baieta, Rafael ; Mihaljevič, Martin (advisor) ; Navrátil, Tomáš (referee) ; Tejnecký, Václav (referee)
Metals of anthropogenic origin have consistently polluted the environment. This thesis focuses mainly on highly contaminated soils or tree rings near mines and smelters in Sub-Saharan Africa. However, Portuguese soils were also assessed to study Pb isotopes in post-fire soils. The tracing capabilities of Pb isotopic ratios were employed to determine contamination sources and to evaluate the potential of pine trees as an environmental archive. Several analytical methods were applied, such as catalytic oxidation, Q-ICP-MS, ICP-OES, FEG-SEM/EDS, EPMA, XRD, etc. Soils near smelters located in three different cities [Kabwe (Pb-Zn), Luanshya (Cu, Co), and Selebi Phikwe (Ni, Pb)] exhibited concentrations of metals greatly exceeding those deemed acceptable by the competent authorities. In Kabwe, for example, concentrations of Pb exceeded 16 000 mg kg-1 . In all sites, contamination was shown to be significant only in the upper ±15 cm of soil. Samples of soils taken in remote locations were always clear of contamination. In Luanshya, metal(oid) bearing particles found in the soils were typically spherical and composed of rapidly cooled sulfides and oxides in the flue gas chambers of the local smelter. These were present only in the topsoil. The tree ring record of pine trees in Kabwe was shown to mimic the...
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