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Diversity of the soil microbial community and its functional aspects in man-influenced environments
CHROŇÁKOVÁ, Alica
Diversity of the soil microbial community and its functional aspects were investigated in man-influenced environments, such as colliery spoil heaps in post mining sites and upland pasture used for outdoor cattle husbandry. The study was based on the cultivation of bacteria and streptomycetes as well as culture-independent approaches. Cultivated bacteria and streptomycetes were characterized by phenotypic and genotypic means. The culture-independent approaches were based on an analysis of environmental DNA in terms of both qualitative and quantitative parameters.
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Gaseous products of microbial decomposition of organic pollution in constructed wetland used for wastewater treatment.
ŠTĚPÁNEK, Jindřich
This master thesis is dealing with monitoring of gaseous products of microbial decomposition of organic pollution in constructed wetland. This wetland was used for wastewater treatment in a village Slavošovice, Czech Republic. Emissions of CO2, CH4 and N2O were measured in one treatment bed of the system. The emissions were quantified, their seasonal course was followed, and the main factors affecting gaseous emissions were identified. Only 3 % of total C emissions were in form of methane, N2O emissions were negligible and only 1,5 % of nitrogen denitrified were in form of N2O. Carbon and nitrogen balances of the system were estimated.
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Soil micromycetes - the potential source of N.sub.2./sub.O in soils
Jirout, Jiří ; Šimek, Miloslav ; Elhottová, Dana
The aim of this paper is to summarize knowledge on potential production of N.sub.2./sub.O by fungi. The processes involved in the global nitrogen cycle are suggested to have an important role in the global environmental changes. Nitrification and denitrification processes cotribute to the production of N.sub.2./sub.O, which belongs to the group of highly active greenhouse gases. Denitrification - the successive reduction of nitrate to N.sub.2./sub. - was supposed to occur only in prokaryotes, but recently the evidence for dissimilation of nitrates and formation of nitrogen oxides and N.sub.2./sub. was reported also in fungi. N.sub.2./sub.O of fungal origin is formed from nitrate or nitrite by reduction under anaerobic or microaerobic conditions. Since fungi showed the capability to use denitrification and oxygen respiration simultaneously under various pO.sub.2./sub. conditions, the N.sub.2./sub.O production by fungi is expected in a wide range of soils with different aeration status.
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Emissions of greenhouse gases (N2O and CO2) from pasture soil as a result of activity of soil microbial community - preliminary results
Šimek, Miloslav ; Hynšt, Jaroslav ; Brůček, Petr ; Čuhel, Jiří
Cattle overwintering area was shown an important point source of N2O and CO2. The emissions of N2O were mostly directly related to the rate of animal impact as the greatest fluxes of N2O and the highest total cumulative N2O emissions as well were found at the most impacted site. The fluxes of N2O were however very variable in time and most of N2O was emitted during several short events in spring or in winter. Laboratory experiments suggested that total amount of nitrogen escaping from soil from impacted sites is much greater than indicated by field measurements of N2O fluxes and molecular nitrogen (N2) was shown as the main nitrogen gas. It is hypothesized that soil pH is a crucial soil factor controlling the mole fraction of N2O: under slightly alkaline conditions in severely impacted soils, denitrification is completed and most of nitrogen escapes from the soil as N2; under more acidic conditions, however, the activity of nitrous oxide reductase is partly reduced.
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Catalytic Decomposition of Nitrous Oxide over Calcined Hydrotalcite-like Compounds
Obalová, L. ; Kovanda, F. ; Jirátová, Květa ; Chmielová, M. ; Wichterle, K. ; Dorničák, V.
Mixed oxide based catalysts prepared by the thermal decomposition of Hydrotalcite-like compounds were used in catalytic decomposition of nitrous oxide into nitrogen and oxygen. The catalytic reaction was performed in a fixed-bed reactor at 1000 ppm N2O inlet concentration in the temperature range 603 - 723 K. Ni and Co-containing catalysts showed high activity in nitrous oxide decomposition. A very poor activity was observed for Mg-Al mixed oxide catalyst. The prepared catalysts were characterized by the thermal analysis, powder X-ray diffraction, infrared spectroscopy, BET surface area measurement, temperature-programmed reduction and temperature-programmed desorption. The determined reaction rate constants of N2O decomposition were approximately proportional to the amount of reducible components and inversely proportional to the amount of strong basic centres of catalyst.
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