The fractionation of potentially toxic elements (PTE) in environmental and anthropogenic solid samples has a crucial influence on their leaching, mobility and bioavailability, or conversely, their immobilization. Redistribution of PTE in different fractions is affected by various soil properties, such as soil reaction, redox conditions, and soil organic matter composition and its content. Fractionation of PTE in soils and other environmental materials is therefore dynamic, as it is controlled by external conditions. Certain changes of soil conditions caused by, for example, climatic events (floods, soil washing, etc.) and human activities (eg. liming) may lead to significant changes in the distribution of fractions of PTE in soils and anthropogenic materials. The aim of this study is to assess the impact of changes of conditions on the short- and long-term diferences in fractionation of selected PTE (As, Cd, Cr, Cu, Pb, Zn) in soils and other solid samples mainly of anthropogenic origin (e.g., smelter slag) in the environment.

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Seed germination is a crucial phase of the plant life cycle. Despite the huge progress that has been made in the last decade, the molecular mechanisms regulating seed germination are far from being resolved. Most of the early events of germination are mediated by molecules stored in seeds during the seed development and thus we employed proteomic analyses to elucidate the mechanism behind this process. This thesis - Proteome dynamics during seed germination - reviews present-day knowledge of this topic. In the experimental part, the results of three related research projects are summarized. First, the effects of a novel class of growth regulators were analyzed in the barley germination assay and the optimal concentrations were determined. The methodology for an improved analysis of barley seed proteins was developed and the optimized targeted analysis will allows the detection of over 4,000 proteins. Finally, Arabidopsis thaliana seed proteome was analyzed and the results indicate that (i) an alternative MS/MS data processing significantly improves the detection limits and (ii) the proteasome-ubiquitin system plays a crucial role in adjusting the seed proteome dynamics during the germination progress.

The diploma thesis deals with lignitic humic acids. Bibliographic search can be divided into three parts. The aim of the first part is characterization of humic substances, presence, composition, structure and exploitation especially of humic acids. The second part describes a division of heterogeneous mixture of humic acids into closed fractions with more specific properties. The final part is a study of solubility of humic acids. The experimental part of the diploma thesis is structured similarly. In this work, a gradual fractionation with pH is used. Obtained fractions were characterized by UV/VIS and FT-IR spectroscopy. We assessed the portion of ash and carboxyl groups have been identified. Subsequently, all fractions extracted by gradual fractionation as well as some soluble fractions obtained by direct fractionation have been analyzed in view of solubility and their behaviour in water environment. Both used methods were compared.

A review on plant rhizodeposition, nutrient uptake and interactions with rhizosphere microbial community is presented. Based on reviewed findings, a study on rhizodeposition rates and rhizodeposits bioavailability of two macrophyte species with different life strategies (stress-tolerator and competitor) was conducted. The effects of P addition and sediment type on rhizodeposition and microbial activity were examined. Research was carried out in tropical marshes of Belize; results from field were supported by C partitioning mesocosm study. This project was supported by NSF # 0089211 and ME 912.

In the diploma thesis have been tested four extraction techniques for isolation of organic forms of mercury from sediments (liquid liquid extraction, microwave extraction in liquid liquid extraction, solid phase extraction and extraction with use of ionic exchange) followed by determination of mercury by atomic absorption spectrometer AMA?254. It has been achieved great results during liquid liquid extraction likewise ionic exchange extraction. Reached percents of orgHg were in accord with certified reference material for sediments CRM-580 and corresponded to 86,44 ? 16,63 %, resp. 87,01 ? 29,22 %. Thanks to a simple procedure, extraction speed and ease of determination of organic forms of mercury contain was first of all (in the first instance) verified a method with use of ionic exchange, whose principle and procedure is very elementary. This technique was applied to a number of real sediment samples collected from water tanks Jordan and Skalka. It was approved that this method has been presenting a suitable alternative to chromatographic methods or methods of electro?migration.

Thesis is focused on structural study of ethylene-propylene copolymers (E/P copolymers) produced by gas phase polymerization. Goal of work was to determine the effect of used catalysts on the distribution of ethylene units in the resulting material. Three E/P copolymers were prepared on commercial Ziegler Natta catalysts with diether or phthalate based internal donors. The copolymers were fractionated according crystallization ability and molar mass. Next, the mass content and the distribution of the ethylene units in the copolymer were determined in each fraction by nuclear magnetic resonance (NMR). Together with other structural analytical methods, phthalate internal donor has been found to produce ethylene blocks under certain conditions, while the diether ID lacks this ability.

Comparison of two different soil organic matter fractionation methods Soil organic matter (SOM) significantly affects physical, chemical and biological properties of soils and plays also a crucial role in the global carbon cycle. In order to simulate SOM dynamics a number of mathematical models have been developed. These models divide SOM into several theoretical pools according to their stability. Unfortunately, lacking experimental procedure which could measure these pools directly, although for this purpose a wide range of fractionation procedures were developed, that are trying identified empirical fractions with theoretical model pools. An objective of this experiment was to reproduce two fractionation procedures on a set of twenty-seven laboratory-prepared samples: according to Six and according to Zimmermann and to compare their results. Also the relationship between respiration and the amount of carbon in different pools was compared. The most significant differences were found in active pools, where Six's method found twice as much carbon than Zimmermann's one. Finally response of both method results to various environmental parameters (mineral composition, litter type and soil mixing) was compared. According to the results of Zimmermann's method the amount of carbon in different pools was mainly...

The thesis assesses forms of phosphorus, aluminium, and iron in soils of catchments of acidified mountain lakes. The aim of the study was to determinate changes in soil chemistry in catchments of Bohemian Forest lakes between years 2000 and 2010. The next aim was to compare fractionation according to Psenner and Pucsko (1988) with standard pedological extractions.

The thesis assesses forms of phosphorus, aluminium, and iron in soils of catchments of acidified mountain lakes. The aim of the study was to determinate changes in soil chemistry in catchments of Bohemian Forest lakes between years 2000 and 2010. The next aim was to compare fractionation according to Psenner and Pucsko (1988) with standard pedological extractions.