ROZDÍLY VE VLASTNOSTECH HORSKÝCH LESNÍCH PŮD NA KYSELÝCH A BAZICKÝCH MATEČNÍCH HORNINÁCH

Mountain forest soils in the region of the Jizera Mountains are polluted by acidification. These soils have a poor quality of humus substances, are highly acidic throughout the whole profile and the main substance bound in the soil sorption complex is aluminium. This study monitors what effect have the consequences of natural processes and human activities on properties of soils that develop close together and therefore are exposed to the same negative effects, covered by the same vegetation, but are situated on bedrocks with different properties. The study only partially confirmed the assumption that the soils developed on alkaline parent rock have better quality than the soils on acid parent rock. It can be concluded that the soils on alkaline bedrock are in most aspects of better quality. However, base components of a relatively rich substrate which would naturally appear on this bedrock are leached out. Analysis results include these soils into the group of soils with low quality threatened by acidification

ZMĚNY FOREM Fe A Al V RÁMCI PEDOGENEZE VÝVRATIŠŤ V PŘIROZENĚ SE VYVÍJEJÍCÍM JEDLO-BUKOVÉM PRALESE

The study is focused on changes of Fe and Al behaviour in naturally developing fir–beech forest Razula (Western Carpathians) with respect to time – in the scope of pedogenic processes. Soil samples from 14 different windthrow sites, of known age (19–192 years), were tested. Samples were taken from five depths from three parts of the windthrow – pit, mound and undisturbed part as a control. Exchangeable (“ free”), oxalate extractable and dithionate-citrate extractable forms of Al and Fe were measured. It was found that contents of Fe and Al forms significantly differed with respect to age and location (pit, mound and control). Moreover, Fe and Al forms also significantly differed in disturbed and undisturbed parts of the windthrow

Relationship between contents of LMMOA in soils and richness of herb vegetation in Carpathian beech forests

Low molecular mass organic acids (LMMOA) are a part of the carbon cycle, and represent an important component of the active organic carbon in soil. The aim of this study was to determine the content, speciation and behavior of LMMOA in soils under Carpathian beech forest with different herb vegetation (herb poor, herb rich), and to assess the relationship between herb vegetation cover and LMMOA. We hypothesize, that LMMOA can infl uence herb vegetation richness through their (LMMOA) ability to release nutrients in forests soils. Speciation of LMMOA, nutrition content (PO43-, Ca2+, K+) and element composition in aqueous extracts were determined by means of ion chromatography and inductively coupled plasma – optical emission spectrometry (ICPOES) respectively. Sorption characteristics were determined in BaCl2 extracts by ICP-OES. Active, exchangeable pH and DOC (dissolved organic carbon) were also determined. Elemental composition of parent rocks was assessed by means of X-ray fluorescence spectroscopy. It was found that, on herb poor localities with higher LMMOA contents, the elements complexation and their further transport into the deeper parts of soil profile happens. There is also an increased dissolution of alumosilicates. And conversly, lowercontents of LMMOA were determined on herb rich locality, leading to nutrients mobilization but not to their leaching. The soil sorption complex is not enriched by Al3+ as there is not increased weathering of aluminosilicates. The result of this study is a diagram showing the influence of LMMOA on vegetation cover richness.Low molecular mass organic acids (LMMOA) are a part of the carbon cycle, and represent an important component of the active organic carbon in soil. The aim of this study was to determine the content, speciation and behavior of LMMOA in soils under Carpathian beech forest with different herb vegetation (herb poor, herb rich), and to assess the relationship between herb vegetation cover and LMMOA. We hypothesize, that LMMOA can infl uence herb vegetation richness through their (LMMOA) ability to release nutrients in forests soils. Speciation of LMMOA, nutrition content (PO43-, Ca2+, K+) and element composition in aqueous extracts were determined by means of ion chromatography and inductively coupled plasma – optical emission spectrometry (ICPOES) respectively. Sorption characteristics were determined in BaCl2 extracts by ICP-OES. Active, exchangeable pH and DOC (dissolved organic carbon) were also determined. Elemental composition of parent rocks was assessed by means of X-ray fluorescence spectroscopy. It was found that, on herb poor localities with higher LMMOA contents, the elements complexation and their further transport into the deeper parts of soil profile happens. There is also an increased dissolution of alumosilicates. And conversly, lowercontents of LMMOA were determined on herb rich locality, leading to nutrients mobilization but not to their leaching. The soil sorption complex is not enriched by Al3+ as there is not increased weathering of aluminosilicates. The result of this study is a diagram showing the influence of LMMOA on vegetation cover richness

Thallium and lead variations in a contaminated peatland : a combined isotopic study from a mining/smelting area

Vertical profiles of Tl, Pb and Zn concentrations and Tl and Pb isotopic ratios in a contaminated peatland/fen (Wolbrom, Poland) were studied to address questions regarding (i) potential long-term immobility of Tl in a peat profile, and (ii) a possible link in Tl isotopic signatures between a Tl source and a peat sample. Both prerequisites are required for using peatlands as archives of atmospheric Tl deposition and Tl isotopic ratios as a source proxy. We demonstrate that Tl is an immobile element in peat with a conservative pattern synonymous to that of Pb, and in contrast to Zn. However, the peat Tl record was more affected by geogenic source(s), as inferred from the calculated element enrichments. The finding further implies that Tl was largely absent from the pre-industrial emissions (>~250 years BP). The measured variations in Tl isotopic ratios in respective peat samples suggest a consistency with anthropogenic Tl (ε205Tl between ~ -3 and 4), as well as with background Tl isotopic values in the study area (ε205Tl between ~0 and 1), in line with detected 206Pb/207Pb ratios (1.16–1.19). Therefore, we propose that peatlands can be used for monitoring trends in Tl deposition and that Tl isotopic ratios can serve to distinguish source origin(s). However, given that the studied fen has a particularly complicated geochemistry (attributed to significant environmental changes in its history), it seems that ombrotrophic peatland(s) could be better suited for this type of Tl research

Vztah vlastností rezonančního dřeva k podmínkám růstu

This work summarizes previously published research on resonant spruce wood. It focuses mainly on the properties of resonant wood to the terms of its growth. The individual values of different authors are compared with each other and summarized into concrete results, so that results could be used to search for potential sites with the possibility of an increase in the resonant layers of wood. To facilitate interpretation and subsequent application there was drawn a map of the potential occurrence of resonant wood in the Czech republic, based on the average annual temperature and rainfall, slope and orientation, optimum altitude and vegetation zones

Design of crank mechanism for an engine 50cc motorbikes

V této bakalářské práci se řeší předběžný návrh dvoudobého motoru do zdvihového objemu válce 50 cm3 pro pohon jízdního kola. Největší důraz a výpočty jsou kladeny na návrh pohyblivých součástí motoru, tedy klikového mechanismu. Pro ilustraci motoru byla provedena výkresová dokumentace jak v dvojrozměrném, tak i třírozměrném provedení.In this work deals with the preliminary draft to the two-stroke engine cylinder displacement volume of 50 cm3 for a bicycle drive. The greatest emphasis, and calculations are subject to the proposal from moving engine parts, ie crank mechanism. To illustrate the engine was made in the drawings as two-dimensional, and three-dimensional design.Katedra dopravních prostředků a diagnostikyPři obhajobě student komisi seznámil řešením výpočtu požadovaného výkonu motoru, který bude stačit pro pohon jízdního kola, pro jezdce o hmotnosti do 100 kg tak, aby motokolo vyjelo do stoupání vozovky 20 procent minimální rychlostí 20 km/h. Součástí práce bylo určení základních rozměrových parametrů, kinematiky a vybraných částí kolikového mechanizmu tak, aby vyhověly neustále se měnících se podmínek provozu motoru.Dokončená práce s úspěšnou obhajobo

Proposal of driveline of vehicle for Shell Eco-marathon

V této diplomové práci se řeší návrh pohonu vozidla určeného pro soutěž o nejnižší spotřebu paliva pořádanou společností Shell s označením Eco-marathon. V první řadě je zapotřebí určit jízdní odpory, z nichž se vypočítá potřebný výkon motoru a přiřadí se k němu odpovídající motor. Motor se upraví dle pravidel závodu a vloží se do rámu vozidla ve vlastní konstrukci. Pohon je řešen pomocí planetového převodu s řetězovým převodem. Nakonec se práce zabývá úspornými možnostmi pohonu a výpočtem spotřeby paliva.This thesis is focused on a proposal of the car propulsion for the Eco-marathon competition which is organized by the company Shell. The competition is concentrated on the best results of the lowest fuel consumption. Firstly, it is necessary to determine driving resistance. On the basis of the resistance the engine power is going to be calculated and the appropriate engine is going to be assigned to it. The engine will be modified according to the rules of the competition and it will be embedded into the vehicle frame in its own construction. The propulsion is going to solved by means of epicyclic gear with a gearing chain. At the end of this thesis I plan to study the fuel saving possibilities of the engine and I will also calculate its fuel consumption.Katedra dopravních prostředků a diagnostikyPři obhajobě diplomant komisi seznámil s diplomovou prací, ve které řešil návrh pohonu vozidla pro Shell Eco-mathon. Rozsah, zpracování a vlastní prezentace práce svědčí o náročnsti daneho probému. Na otázky oponenta diplomová práce, vedoucího diplomové práce i členů komise při rozpravě odpovídal věcně správně

The effect of beverage preparation method on aluminium content in coffee infusions

Seven types of coffee were prepared by four methods. Three of them – simple coffee infusion, preparation in ibrick and moka pot – are very often used to prepare coffee at home. The fourth one – a single-cup filter is typical for Vietnam. Cookware used for each method was made from glass, aluminium, stainless steel and two types of alloys. Amounts of Al leaching to coffee infusions were determined. On average, the highest amount of Al was in coffee infusions brewed in aluminium single-cup filter, and the lowest in infusions prepared by simple extraction. Other brewing methods in combination with different tool materials resulted in similar Al content. The type of brewing method significantly influences the Al content in final infusion. Aluminium content varies in infusions in relation to the method of choice, especially when using single-cup filter. Despite the fact that coffee is considered to be a poor source of Al for humans, in some cases, Al content in infusions can even reach the values reported for tea infusions

Sustainable Soil Washing: Shredded Card Filtration of Potentially Toxic Elements after Leaching from Soil Using Organic Acid Solutions.

Shredded card (SC) was assessed for use as a sorbent of potentially toxic elements (PTE) carried from contaminated soil in various leachates (oxalic acid, formic acid, CaCl2, water). We further assessed SC for retention of PTE, using acidified water (pH 3.4). Vertical columns and a peristaltic pump were used to leach PTE from soils (O and A/B horizons) before passing through SC. Sorption onto SC was studied by comparing leachates, and by monitoring total PTE contents on SC before and after leaching. SC buffers against acidic soil conditions that promote metals solubility; considerable increases in solution pH (+4.49) were observed. Greatest differences in solution PTE content after leaching with/without SC occurred for Pb. In oxalic acid, As, Cd, Pb showed a high level of sorption (25, 15, and 58x more of the respective PTE in leachates without SC). In formic acid, Pb sorption was highly efficient (219x more Pb in leachate without SC). In water, only Pb showed high sorption (191x more Pb in leachate without SC). In desorption experiments, release of PTE from SC varied according to the source of PTE (organic/mineral soil), and type of solvent used. Arsenic was the PTE most readily leached in desorption experiments. Low As sorption from water was followed by fast release (70% As released from SC). A high rate of Cd sorption from organic acid solutions was followed by strong retention (~12% Cd desorption). SC also retained Pb after sorption from water, with subsequent losses of ≤8.5% of total bound Pb. The proposed use of this material is for the filtration of PTE from extract solution following soil washing. Low-molecular-mass organic acids offer a less destructive, biodegradable alternative to strong inorganic acids for soil washing

Arsenic in iron disulfides in a brown coal from the North Bohemian Basin, Czech Republic

Arsenic in the coal studied is not bound to coal macerals, it is concentrated in the inorganic part of coal, specifically in the iron sulfides. This paper reports the results of five crystal structure refinements that include natural (2) and synthetic (3) sulfides, pyrite (3) and marcasite (2). Powder (3) and single-crystal (2) intensities used in the refinements were obtained by diffraction of X-rays (4) and synchrotron radiation (1). The refined occupancy factors of sulfur and the unit-cell parameters favor the possibility that As substitutes for S in both disulfides