Χαρακτηρισμός των μικροοργανισμών που αναπτύσσονται σε θαλάσσια ιζήματα στη ζώνη κρυστάλλων υδριτών μεθανίου.
In Anaximander Mountains, in Eastern Mediterranean Sea, at a water depth of 1260-2000m., several active mud volcanoes have been identified that emit methane to the water column. Inside the sediment, in shallow depths, pressure and temperature favor gas hydrate formation, accumulating upward migratin...
| Main Authors: | , |
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | Greek |
| Published: |
Technical University of Crete (TUC)
2012
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| Subjects: | |
| Online Access: | http://hdl.handle.net/10442/hedi/32103 https://doi.org/10.12681/eadd/32103 |
| Summary: | In Anaximander Mountains, in Eastern Mediterranean Sea, at a water depth of 1260-2000m., several active mud volcanoes have been identified that emit methane to the water column. Inside the sediment, in shallow depths, pressure and temperature favor gas hydrate formation, accumulating upward migrating methane, which may at the same time represent a possible source of methane emission, in case of destabilization due to changing conditions. High methane concentrations have been identified in the water column over these mud volcanoes. Methane emitted through the sediment is diluted in the water column, where methane oxidation rapidly occurs by methanotrophs. The remaining amount of methane is released to the atmosphere, increasing atmospheric methane budget, which contributes to the greenhouse effect.In sediments rich in methane, methanotrophs are thought to oxidize methane under anaerobic conditions, through a procedure that remains vague up to date. The Anaerobic Oxidation of Methane (AOM) in marine sediments, is thought to consume more than 80% of methane produced in marine sediments, which otherwise would end up to the water column. Methane that is finally emitted to the water column is what has not been sequestered in gas hydrates, and has not been consumed by methanotrophs.Previous investigations of AOM in Amsterdam and Kazan MV’s have provided information on the presence of anaerobic methanotrophs in the upper sediment layers. Up to date though, there has not been investigated the particular structures (aggregates) that these microorganism form, and their ecologic relations with other microorganisms. In the present study, the prokaryotic abundance has been estimated in sediment cores from Amsterdam, Kazan and Kula mud volcanoes, in depth up to 150cm. In these sediments, the occurrence of AOM activity was investigated and it was examined how fluid flow and methane hydrate formations affected it. At the same time, vivid cultures of sulfate reducing Bacteria and unknown Bacteria, probably methylotrophs, were ... |
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