National Repository of Grey Literature 26 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
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...
Role of carbohydrate metabolism in defence against oxidative stress induced by arsenic
Kofroňová, Monika ; Lipavská, Helena (advisor) ; Száková, Jiřina (referee) ; Kovalíková, Zuzana (referee)
Heavy metal contamination significantly reduces crop yields, causing serious problems in agriculture and having a major impact on human health if these contaminants enter the food chain. Understanding the mechanisms of plant responses could help to increase their resistance to heavy metals as well as their potential use in phytoremediation. Carbohydrates play an important role in plant growth and development as well as in defense reactions. This work summarizes the results of four publications focused on the effects of arsenic and thorium on antioxidant mechanisms in tobacco plants and horseradish root crops. Attention is paid, among other things, to the dynamics of sugar contents, which are potentially important molecules involved in the fight against oxidative stress. The first publication summarizes arsenic effects on plant physiological parameters, focusing on arsenic tolerance-enhancing mechanisms as well as summarizing the ability of plants to cope with arsenic-induced oxidative and nitrosative stress. Emphasis was placed on, among other things, a topic that was unjustly neglected in previous publications - i.e. carbohydrate metabolism. Further work was already experimental and dealt with the study of arsenic as a trigger of oxidative stress in the root culture of horseradish and...
Chemical Properties of Flue Gas Desulphurization Gypsums from Different Energy Sources
Kroulíková, S. ; Mercl, F. ; Száková, J. ; Perná, Ivana ; Tlustoš, P.
There were compared flue gas desulphurization gypsums (FGDGs) from four different power plants in the Czech Republic on chemical properties (pH, total content of nutrients and risk elements) and then was assessed their potential for utilization in agriculture as fertilizer without any risk to the environment. According to our results, the FGDGs represent an important possible source of sulphur (17.8 – 19.0 %) and calcium (23.0 – 30.2 %) for reduction of their deficit in the soil. However, contents of arsenic and of mercury in three of the tested FGDGs not fulfil the limit values for fertilizers. In the future, the remaining FGDG is thus necessary to evaluate for its fertilizing effects in model and field conditions.\n\n
Selenium uptake by the organism of the spontaneously hypertensive rats (SHR)
Růnová, Karolína ; Száková, Jiřina (advisor) ; Václav, Václav (referee)
The aim of this thesis was to evaluate the effect of increased intake of selenium from the diet of rats with spontaneous hypertension (SHR) on other essential elements. The effect of different diets on the element levels in kidney, liver, testes, and blood of rats was observed under model conditions. Tested rats were divided into five groups, where the first group A was the reference group and feed mixture contained no additive. In groups B and C was soybean meal replaced by defatted rapeseed and into feed mixture of group C was additionally added vitamin E. Diet groups D and E contained added selenium and zinc, and group E contained additionally vitamin E in comparison to reference group A. Se content in kidney, liver, testicles, and blood of animals was determined by inductively coupled plasma mass spectrometry (ICP MS). The other essential elements (Cu, Fe, Mn, P, S, and Zn) were determined by inductively coupled plasma optical emission spectrometry (ICP OES). The content of Ca, K and Mg was determined by atomic absorption spectrometry with flame atomizer (F-AAS). The hypothesis has been that the increased intake of selenium should improve the use of other essential elements by the rat organism. It was expected that there will be influenced elements mainly involved in the defense of the organism against oxidative stress. This was not confirmed by this experiment. Changes in the concentrations of these elements occurred only at very high dose of selenium that is already toxic to the organism. This toxic effect could be also responsible for fifty percent mortality of rats in group E, where perhaps even increased concentration of vitamin E could not sufficiently reduce the toxicity of high doses of selenium.
Microbial mobilization of arsenic from soil at the Mokrsko gold deposit
Redlich, Aleš ; Drahota, Petr (advisor) ; Száková, Jiřina (referee)
The Mokrsko gold deposit is characterised by high arsenic concentrations in regolith. Naturally contaminated regolith and stream sediment samples have been studied in order to determine microbially mediated processes that lead to As mobilization. Arsenic concentration in regolith and sediment were 905 mg kg-1 and 1749 mg kg-1 , respectively. The mineralogy of arsenic in the regolith is dominated by arsenic-bearing goethite and minor arseniosiderite and Ba-pharmacosiderite. In contrast, highly reducing sediments are mainly characterised by secondary realgar and less arsenic-bearing goethite and secondary arsenates. These samples were used for incubation experiments under both aerobic and anaerobic conditions. When glucose was supplied as a C source under anaerobic conditions, indigenous bacteria significantly enhanced the extent of As release from the solid samples into solution. Highly positive correlation between the extracted amount of As and Fe implied that the microbial dissolution of Fe(III)-oxides is responsible for the As release, with possible contribution of secondary arsenates dissolution. On the other side, small amount of arsenic was released from the sediment during the aerobic incubation through the microbially mediated oxidation of secondary realgar. In attempt to find some bacterial...
Speciation analysis of toxicologocally important forms of arsenic: development and comparison of hydride generation based methods with ICP-MS detection
Trojánková, Nikola ; Matoušek, Tomáš (advisor) ; Száková, Jiřina (referee)
Nowadays, arsenic is becoming an important pollutant in the environment. Chronic exposure to arsenic can cause number of serious diseases. Therefore, a development of analytical methods for trace and ultratrace speciation analysis- analysis of individual forms or phases in which As is found in the sample - is fully in place. This Thesis compares four methods of trace speciation analysis, with focus on limits of detection and quantification, and on comparison of results of analysis of river and sea water reference materials. Methods based on hydride generation with preconcentration by cryotrapping and AAS or ICP-MS detection, with limits of detection in ng or tenths of ng·dm-3 , are compared with procedures employing HPLC, with ICP-MS detection. The Thesis includes development and optimization of a pre-reduction step of postcolumn hydride generation with on-line pre-reduction of pentavalent arsenic species, in order to improve sensitivity of this method. Limits of detection around 10 ng·dm-3 are achieved. The results of analyses obtained by individual methods are in excellent agreement. Keywords: Arsenic, speciation analysis, hydride generation, atomic absorption spectrometry, inductively coupled plasma- mass spectrometry, high efficiency liquid chromatography, limits of detection.
Determination of mercury content in materials in various stages of wine production, geochemistry of mercury in the vineyard
Buchtová, Jana ; Mihaljevič, Martin (advisor) ; Száková, Jiřina (referee)
This work was focused on determination of mobility of mercury and its content in materials from each part of the wine production process. The aim of this work was to establish the most suitable analytical method for determination and evaluation of changes in content of mercury during the production process. Samples of soil, biomass, vine wood, vine leaves, berries, grapes, rough wine and cider sediment of red wine and also four liquid samples of white wine were analyzed. All the samples originated from the area of Malé Žernoseky and Rudoltice nad Bílinou, white wine samples were collected in Chrámce u Mostu in the northern part of the Czech Republic. Analyzer AMA 254 was used for determination of mercury in solid samples and liquid samples had to be prearranged by PSA analyzer. This analytical approach was not so sufficient and mercury from liquid samples had to be captured by gold-coated amalgamator in first step and then analyzed by AMA 254. Obtained results confirmed interception of mercury mostly in leaves and in the grapes peelings. The grapes from Rudoltice contained 0,0022 mg/kg in dry mass and further processed wine grapes contained 0,0068 mg/kg in dry mass. The lowest content of mercury was in cider and completed wine contained less mercury then the rough wine. Unfiltrated cider from Chrámce has...
Geochemical model of arsenic at the Mokrsko gold deposit
Drahota, Petr ; Pertold, Zdeněk (advisor) ; Száková, Jiřina (referee) ; Zeman, Josef (referee)
Geochemical model of arsenic at the Mokrsko gold deposit Dissertation of Petr Drahota 1 Abstract The dissertation contributes to the As mobility at the naturally contaminated site of Mokrsko gold deposit in Central Czech Republic. The primary goal of the dissertation is to fill some gaps in previous research carried out at the study site in order to contribute to the quantitative biogeochemical model of As in the bedrock-groundwater-soil-surface water system. In the first part, the previous research related to As environmental issues at the study site has been reviewed, discussed and evaluated. These include detail information on (i) the extent of natural As contamination in bedrock and soil, (ii) the extent of As contamination in groundwater, (iii) the primary and secondary As mineralogy in bedrock and soil, (iv) the chemical speciation of As in soil and (v) the leaching experiments of the gold ore. In the second part, the mineralogical and chemical speciation of As in soil, in stream and fishpond sediments and dissolved As concentrations in waters have been studied to determine the processes that lead to release of As into solution and control its concentration under different redox conditions at the Mokrsko gold deposit. The highest dissolved As was found in groundwater (more than 1000 g L-1 ), which...
Total contents and speciation of arsenic and selenium in plants growing in soils with different physico-chemical properties
Tremlová, Jana ; Száková, Jiřina (advisor) ; Vymazal, Jan (referee)
This dissertation thesis deals with uptake, accumulation and transformation of arsenic and selenium in plants growing on soils with different chemico-physical soil properties. The contents of arsenic were investigated in 99 wild plant species, coming from 27 different families and 6 different vegetables growing in arsenic contaminated soils. The results suggest that there are species-specific mechanisms which protects certain plants from the excessive uptake of arsenic from the soil. On the other hand, there are plants using a strategy of accumulation, which theoretically may increase the risk of arsenic entry into the food chain, whether through grazing cattle and wildlife or through consumption of vegetables growing on arsenic contaminated soils. The most prevalent arsenic compounds are AsV and AsIII. Other arsenic compounds occure as minor species. An important finding was detection of arsenobetaine in Plantago lanceolata L. and Carex praecox Schreb .. The contents of selenium were examined in 73 species of wild plants, coming from 29 different families. The results suggest that naturally low levels of selenium in the soil of selected locations along with a low capability of selenium uptake via collected plant species lead to the low content of selenium in plant biomass which may contribute to selenium deficient throughout the food chain. Foliar application of selenate on wild plant communities and on some types of vegetables in our case Brassica oleracea var. italica can have a positive impact on increasing the selenium content in the aboveground biomass of these plants and by extension, increase the selenium content in the human diet. Dominant selenium compounds in the aboveground biomass of the analyzed plants were SeVI and selenomethionine, with variable proportion of other commonly occurring organic selenium compounds, which is mainly affected by plant species.

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