National Repository of Grey Literature 131 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Influence of soil pretreatment on the determination of its properties using thermogravimetry
Ragačová, Lucia ; Doležalová Weissmannová, Helena (referee) ; Kučerík, Jiří (advisor)
This diploma thesis focuses on the influence of soil pretreatment on the determination of its properties by the method of thermogravimetry, which allows the soil sample to be analyzed as a whole. The aim is to clarify how soil preparation affects the results of TG soil analysis. Soil preparation can have a major impact on its quality and thus disrupt the interrelationships of soil components that have been formed as a result of long-term pedogenesis. In this thesis, therefore, the original soils were compared with the soils, which were grinded using a ball mill before the analysis, which represented a very intensive intervention in the soil structure and was therefore a mechanically disturbed soil. A modified method of deriving weight loss has been used to evaluate the issue. The data obtained were divided into 10°C thermal intervals, in-between which the loss of weight of the individual intervals were identified. The impact of soil milling on its determinability in relation to the total carbon and nitrogen content in the soil have been compared through the correlation of data obtained from elemental analysis and TG data. Subsequently, we focused on comparing the interrelationships of the equations of ground and unground soil samples, based on the theoretical equations of the issue. As a final look, we chose autocorrelation of TG data for the obtained ground and unground samples. The results of the examination have shown that even though grinding of samples represents a very intensive intervention into the soil structure and thus the soil is mechanically disturbed, such sample preparation has only a minimal effect on the determinability of soil properties.
CARBON AND NITROGEN POOLS AND FLUXES OF TWO FOREST ECOSYSTEMS IN THE ORE MOUNTAINS
Růžek, Michal ; Oulehle, Filip (advisor) ; Tahovská, Karolina (referee)
CARBON AND NITROGEN POOLS AND FLUXES OF TWO FOREST ECOSYSTEMS IN THE ORE MOUNTAINS With increasing atmospheric CO2 concentrations, forest ecosystems are considered for their sequestration ability. However, there are differences between coniferous and deciduous tree species in their impact on the carbon (C) and nitrogen (N) fluxes within forest ecosystems, which influence soil carbon and nitrogen pools. In natural beech and monoculture spruce stands on research sites of Czech Geological Survey in the Ore Mountains, C and N fluxes and pools were investigated. There were investigated ecosystem inputs (C, N, in throughfall, litterfall) as well as outputs (soil respiration, concentrations of C, N in seepage water discharge). Further, C and N pools of living biomass and soils were determined. Throughfall DOC was significantly higher in the spruce stand, on the other hand litterfall C flux showed the opposite relationship. At output, DOC, DON and NH4 + discharge fluxes from O horizon were significantly higher in the spruce stand whereas in the beech stand higher NO3 - flux from mineral soil was recorded. Soil respiration was quite similar in the both stands, however different parts of original sources of respiration among tree species were different. Beech stand has larger pools of carbon and nitrogen in...
Atmospheric deposition of nitrogen - application of stable isotopes
Hanzlová, Barbora ; Hůnová, Iva (advisor) ; Hovorka, Jan (referee)
Human impact on particular parts of ecosystems has become a highly discussed topic. Due to different isotopic values of nitrogen, it is possible to evaluate the extent to which human influences the natural nitrogen cycle, using isotope measurements. Stable isotope measurement has been used in various scientific disciplines around the world. This thesis summarizes the findings about atmospheric deposition and the subsequent use of stable nitrogen isotopes. The objective of this work was to gather the information about the use of stable isotopes in the study of the atmospheric deposition and how to make better use of the information obtained from the measurements. Based on the literature review, it has been found that, unlike other countries, nitrate substances such as NH3 and HNO3 are not measured in the Czech Republic, which distorts the data on the nitrogen produced. The use of stable isotopes is a convenient method of measuring both not yet quantified substances as well as already measured substances contributing to atmospheric deposition. The stable isotope measurement method represents an improvement for the overall estimation of atmospheric deposition to provide more realistic values compared to the current approach. Key words: atmospheric deposition, nitrogen, stable isotopes
Trends in composition of atmospheric precipitation and deposition in Europe
Šimková, Petra ; Hůnová, Iva (advisor) ; Maznová, Jana (referee)
This bachelor thesis describes the historical development of emissions and their associated composition of atmospheric precipitation and atmospheric deposition in Europe. It is the work with review character, which summarizes and evaluates current knowledge of the majority components of atmospheric deposition. It relies particularly on articles and a summary reports of monitoring networks devoted to the large time horizon. At the beginning part of this work are defined the major components of atmospheric deposition. In another part is described composition of atmospheric precipitation, sampling dry and wet deposition and subsequent chemical analysis. The main part is devoted to evaluate the development of emission and sputtering of the main trends of acidifying compounds, and basic cations in Europe. Emission and deposition trends are divided into time periods, which were defined in relation to the development of historical, political or economic situation. Another criterion in the evaluation of trends in the composition of atmospheric precipitation and atmospheric deposition was the State's geographical position within Europe. There are summarized the results of studies on the deposition trends across Europe, but the main attention is devoted to the differences between Western and Eastern Europe...
Lateral root development in response to mineral nutrients; signal mechanisms and pathways.
Halamková, Daniela ; Tylová, Edita (advisor) ; Lhotáková, Zuzana (referee)
TTL3 gene was identified by forward screening of genes involved in lateral root development in Arabidopsis thaliana based on its expression pattern. TTL3 belongs to the TTL (TETRATRICOPEPTIDE-REPEAT THIOREDOXIN-LIKE) gene family. The diploma thesis is aimed on characterisation of changes in TTL1, TTL3 a TTL4 promotor activities in response to external conditions (availability of nitrogen or phosphorus) that affect root growth. Obtained data should elucidate possible relation among TTL gene expression activities, root growth rate, and apical meristem activity. Nitrogen or phosphorus deficiency triggered changes in root growth and root system morphology of experimental plants. Short-term nitrogen deficiency stimulated root growth. Short-term phosphorus deficiency induced gradual growth cessation in main root and long laterals. Long-term deficiency reduced root growth of both N-deficient and P-deficient plants compared to control. The root system size of N-deficient and P-deficient plant was almost similar. Determination of promotor activity using β-glucuronidase reporter gene showed changes in expression activity and its localization in response to root growth intensity. TTL4 gene promotor activity was the most responsive. Its activity was generally higher in slowly growing roots, particularly under...
Trends in sulphur and nitrogen occult deposition across the Northern Hemisphere
Švorc, Daniel ; Hůnová, Iva (advisor) ; Stráník, Vojtěch (referee)
The aim of my bachelor thesis is to collect data of concentrations and depositions of sulfur and nitrogen from occult precipitation, using the research of available scientific publications. Through atmospheric deposition are pollutants from air transported into other environmental spheres. It has two main components: dry (which takes place mainly by gravitational processes and its ongoing) and wet (which takes place in the presence of precipitations). Wet component consist of vertical and occult parts, representing the types of precipitations. Establishing total wet deposition encounter a problem in establishing a occult deposition. Problem is, in particular, setting of deposition flux, for which it is necessary to determinate a number of parameters. A considerable part of studies, therefore, do not examine the deposition itself, because of complexity of assessment, but examines chemical composition of fog, low clouds and rime, which is proportionally related to values of occult deposition. Most studies were examining from occult precipitation a fog, especially at higher altitudes, where due to the more frequent occurrence, significant contribute to the total atmospheric wet deposition. Occult precipitations are in longer contact with vegetation, and unlike the rainfall, are surrounded whole leaf,...
Interactions of initially mycoheterotrophic plants with environment
Figura, Tomáš ; Ponert, Jan (advisor) ; Kolařík, Miroslav (referee) ; Janoušková, Martina (referee)
Initially mycoheterotrophic plants have recently been declining in the wild, even without apparent causes. They are affected by a number of biotic and abiotic factors. The aim of this work is to investigate how selected factors, such as nitrate or symbiotic fungi, may influence their distribution in nature. In particular, the work applies in vitro experiments, molecular determination of fungal symbionts and stable isotope analyses. It describes both the effects of abiotic factor, specifically nitrate, and biotic interactions of initially mycoheterotrophic plants with fungal symbionts. The inhibition of germination by extremely low concentrations of nitrate in asymbiotic in vitro cultures was observed in several orchid species. The degree of sensitivity of each species to nitrate corresponds with the nitrate content of the soil and the nutrient availability requirements of the species according to Ellenberg indicator values. The inhibitory effect of nitrate on orchid germination was also observed in symbiotic in vitro cultures. Out of five tested fungal strains, only one Ceratobasidium was capable of eliminating the inhibitory effect of nitrate. Furthermore, the work reveals that green mixotrophic orchids use photosynthates to nourish the aboveground parts, whereas the belowground parts are...
Mechanisms of exodermal response to nutrient availability in the environment
Gargoš, Ondřej ; Tylová, Edita (advisor) ; Kummerová, Marie (referee)
in English The apoplastic barriers of the root (endodermis and exodermis) represent an important regulatory mechanism for the uptake of water and nutrients from the environment, ensuring its selectivity. In addition, both layers respond to stress factors by altering its rate and degree of cell wall modification, which affects the transport properties of the root and represents adaptive plants to high heterogeneity of the soil environment. Apoplastic barriers also respond to the availability of mineral nutrients. This issue has recently been intensively studied and a number of ambiguities persist. Interestingly, the deficiency of some mineral nutrients stimulates the differentiation of barriers, while the deficiency of other mineral nutrients delays the differentiation. In addition, different plant species react differently to the deficiency of the same element. Another interesting aspect is the fact that the reaction of the endodermis and exodermis is localized and takes place mainly in that part of the root system which is directly exposed to the stress factor. This phenomenon has been observed with cadmium toxicity, but more recently with local nutrient deficiencies (nitrogen and potassium) in Zea mays. This diploma thesis deals with the functional significance of localized enhancing or delaying...
CARBON AND NITROGEN POOLS AND FLUXES OF TWO FOREST ECOSYSTEMS IN THE ORE MOUNTAINS
Růžek, Michal
CARBON AND NITROGEN POOLS AND FLUXES OF TWO FOREST ECOSYSTEMS IN THE ORE MOUNTAINS With increasing atmospheric CO2 concentrations, forest ecosystems are considered for their sequestration ability. However, there are differences between coniferous and deciduous tree species in their impact on the carbon (C) and nitrogen (N) fluxes within forest ecosystems, which influence soil carbon and nitrogen pools. In natural beech and monoculture spruce stands on research sites of Czech Geological Survey in the Ore Mountains, C and N fluxes and pools were investigated. There were investigated ecosystem inputs (C, N, in throughfall, litterfall) as well as outputs (soil respiration, concentrations of C, N in seepage water discharge). Further, C and N pools of living biomass and soils were determined. Throughfall DOC was significantly higher in the spruce stand, on the other hand litterfall C flux showed the opposite relationship. At output, DOC, DON and NH4 + discharge fluxes from O horizon were significantly higher in the spruce stand whereas in the beech stand higher NO3 - flux from mineral soil was recorded. Soil respiration was quite similar in the both stands, however different parts of original sources of respiration among tree species were different. Beech stand has larger pools of carbon and nitrogen in...
Intraspecific variability in seeds nutrient stoichiometry
Kesl, Tomáš ; Mašková, Tereza (advisor) ; Konečná, Marie (referee)
Immediately after germination, the plants depend on the nutrients stored in the seed from which they germinated, until the nutrient intake is completely replaced by the mature leaves and roots. Nutrients in seeds are important for early development of vegetative organs. Their content and concentration in seeds can be influenced by various factors such as nutrient availability in soil, latitude, temperature, photoperiod, granivory and competition. This bachelor's thesis summarizes current knowledge about intraspecific and interspecific variability of seed nutrient stoichiometry, specifically nitrogen, phosphorus and carbon, as they most often limit plant growth. For all three elements, common and different trends can be observed, both at the intra-species and inter-species level. The only trend comparable between the intra-species and inter-species level is correlation of carbon seed concentration and latitude, while at the inter-species level there is also the opposite trend of negative correlation of latitude and carbon concentration in seeds. Other observed trends are not comparable between the intra-species and inter-species level. It is not possible to compare these trends, as there is lack of studies on the variability of seed nutrient stoichiometry. Therefore it is necessary to focus on seed...

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