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Natural sources and sinks of volatile chlorinated hydrocarbons in the spruce forest ecosystem
Štangelová, Pavla ; Tesařová, Eva (advisor) ; Pavlík, Milan (referee)
Biogeochemical cycle of chlorine, particularly the formation of organically bound chlorine is still not well understood. In continental ecosystems chlorides act as source of chlorine, and also as a stress factor. Chlorides originate from precipitation of marine cloud masses. Organically bound chlorine in the environment is formed naturally by biotical and abiotical way. The biotical factors are microorganisms, plants, soil enzymes and animals. Volatile chlorinated hydrocarbons (VOCl) represent one group of organically bound chlorines. Several volatile chlorinated hydrocarbons reacts with atmospheric ozone, consequently causing depletion of the ozone layer. The most important known terrestrial source of volatile chlorinated hydrocarbons is the spruce forest ecosystem. Chlorine in the soil can be transformed by microorganisms into organically bound chlorine or translocated by transpiration stream in plants, where they are also transformed enzymatically into organically bound chlorine, and both of them can be emitted into the atmosphere. Too large amounts of chloride can affect the physiological functions of plants. In this thesis experiments were designed for measuring the natural emissions of volatile halogenated hydrocarbons from plants and fungi, with various periods of incubation, and also to...
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Natural sources and sinks of volatile chlorinated hydrocarbons in the spruce forest ecosystem
Štangelová, Pavla ; Tesařová, Eva (advisor) ; Pavlík, Milan (referee)
Biogeochemical cycle of chlorine, particularly the formation of organically bound chlorine is still not well understood. In continental ecosystems chlorides act as source of chlorine, and also as a stress factor. Chlorides originate from precipitation of marine cloud masses. Organically bound chlorine in the environment is formed naturally by biotical and abiotical way. The biotical factors are microorganisms, plants, soil enzymes and animals. Volatile chlorinated hydrocarbons (VOCl) represent one group of organically bound chlorines. Several volatile chlorinated hydrocarbons reacts with atmospheric ozone, consequently causing depletion of the ozone layer. The most important known terrestrial source of volatile chlorinated hydrocarbons is the spruce forest ecosystem. Chlorine in the soil can be transformed by microorganisms into organically bound chlorine or translocated by transpiration stream in plants, where they are also transformed enzymatically into organically bound chlorine, and both of them can be emitted into the atmosphere. Too large amounts of chloride can affect the physiological functions of plants. In this thesis experiments were designed for measuring the natural emissions of volatile halogenated hydrocarbons from plants and fungi, with various periods of incubation, and also to...
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Volatilization of inorganic chlorides by haloperoxidases of soil microorganisms and plants
Loukotová, Šárka ; Stiborová, Marie (advisor) ; Moserová, Michaela (referee)
Biogeochemical cycle of chlorine, particularly formation of organically bound chlorine (Clorg), is still known only in outlines. In continental ecosystems chloride acts as stress factor, and also as source of chlorine; it originates from precipitation, which comes from marine cloud masses. Clorg are formed naturally by biotical and abiotical way. The biological factors are microorganisms, soil enzymes, plants and even animals. Halogenation processes undergo in marine environment as well, the main difference is the presence of bromine besides chlorine, therefore the reaction and formation of brominated compounds. One group of Clorg represents volatile chlorinated hydrocarbons (VOCl). Several VOCl can react with atmospheric ozone, consequently causing its depletion. The best known sources of VOCl are soil, the microorganisms living in it, and their exoenzymes released into it. The heme peroxidases in the group EC 1.11.1.X can perform halogenation of organic compounds. Hydrogen peroxide or organic peroxides are the substrates of this reaction in which hypochlorous acid is generated. The halogen in reactive form then carries chlorine onto the organic compound. To study enzymatic mediation of chlorination processes, we chose commercially available enzymes (chloroperoxidase from Caldariomyces fumago and...
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