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Content of iron and quality of organic matter as a factor affecting stabilization of carbon and nutrients in fresh water ecosystems.
Osafo, Nana O. A. ; Jan, Jiří ; Porcal, Petr ; Borovec, Jakub
The effect of watershed geochemistry, in terms of soil pH, Fe concentration and organic matter quality, on the stability of organic carbon and nutrients level in freshwater sediments of shallow lakes was studied. Twelve fishponds were divided into two groups based on the typical soil pH: i) watershed with acidic soils (pH 5.1 – 6.3) rich in Fe called H_Fe and ii) watershed with neutral pH soils (pH 6.8 – 7.6) poor in Fe called L_Fe. The parameters of the water column, pore water and sediment chemical extractions were compared. A higher concentration of hydrated Fe oxides, together with the aromatic character of organic substances were shown to highly contribute to the overall stabilization of the sediment. Conversely, low Fe concentrations were accompanied by lower mineralization of sediments and a higher risk for the aquatic ecosystem in terms of nutrient release or the development of anoxic conditions.
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Tooth Clasification on Jaw 3D Polygonal Model
Hulík, Rostislav ; Španěl, Michal (referee) ; Kršek, Přemysl (advisor)
This document discusses a solution for tooth classification on 3D jaw polygonal model. Sequentially, I describe techniques for representation and browsing of polygonal model saved in computer memory, techniques for dental curve detection and finally, creation of surface representing approximated tooth plane. After it, I analyze possibilities of height map creation from jaw model which helps in tooth classification in the scope of entire dental curve context and, as a last step, final detection of these teeth in two dimensions. In the same time, I discuss 3D polygonal model segmentation for border extraction, which separates teeth from the rest of the model. In the end of proposed algorithm, I join these two runs into one final detection and classification process of separate teeth, so presented application can automatically indentify and classify teeth to corresponding names and positions with a minimum user interaction. In a second half of this document, I describe implemented solution. According to primary goal, I propose these techniques forcefully to multiplatform approach and maximal user comfort.
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Changes in chemical composition of surface water at the model catchment Lesni potok during the spring snowmelt 2009
Navrátil, Tomáš ; Dobešová, Irena ; Rohovec, Jan ; Buchtová, Jana
Changes of surface water chemistry during the spring snowmelt were evaluated at the forested experimental catchment Lesni Potok found in National Reservation Area Voděradské bučiny. The pH value of surface waters decreased and together with high discharge it launched changes of solutes concentrations. As a good indicator of groundwater in the discharge were evaluated concentrations of Si and isotopic signature of 18O-H2O. The concentration of the main anion SO42- in waters of Lesni potok oscillated during the spring snowmelt in dependence of ratio between melting snow, soil solution, precipitation and groundwater. During the period of increased penetration of surface soil horizons with the water from melting snow causing the increase of DOC concentrations. Concentrations of DOC determined the export of total Fe. Concentrations of Al with DOC did not correlate because the driving factor on concentrations of Al at Lesni Potok is the surface water pH. Concentrations of NO3- were rapidly decreasing during the snowmelt and at the end of this episodic event NO3- concentrations were trivial due to the rapid flushing of soil horizons.
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