Anoxic aggregates - an ephemeral phenomenon in the pelagic environment?

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Show simple item record Ploug, Helle en_US Kuhl, Michael en_US Buchholz-Cleven, Berit en_US Jorgensen, Bo en_US
dc.contributor.editor en_US 2012-02-02T08:24:56Z 2012-02-02T08:24:56Z 1997 en_US
dc.identifier 2009005739 en_US
dc.identifier.citation Ploug Helle et al. 1997, 'Anoxic aggregates - an ephemeral phenomenon in the pelagic environment?', Inter-Research, vol. 13, pp. 285-294. en_US
dc.identifier.issn 0948-3055 en_US
dc.identifier.other C1UNSUBMIT en_US
dc.description.abstract Radial microscale distributions of oxygen and pH were studied in ca 1.5 mm large laboratory-made aggregates composed of phytoplankton detritus and fecal pellets. Microsensor measurements were done at spatial increments down to 0.05 mm in a vertical flow system in which the individual aggregates stabilized their position in the water phase according to the upward flow velocity. The aggregates were surrounded by a diffusive boundary layer with steep gradients of oxygen and pH. They were highly heterotrophic communities both under natural light conditions and in darkness. pH was lowered from 8.2 in the surrounding water to 7.4 in the center of an anoxic aggregate. Sulfide was not detectable by use of sulfide microelectrodes in anoxic aggregates, and methanogenic bacteria could not be detected after PCR (polymerase chain reaction) amplification using archaebacterial-specific primers. The oxygen respiration rate decreased exponentially over time with a T1/2 of 2.3 d. Theoretical calculations of the volumetric oxygen respiration rate needed to deplete oxygen inside aggregates was compared to the density of organic matter in natural marine aggregates. These calculations showed that carbon limitation of heterotrophic processes would limit anoxic conditions to occurring only over a few hours, depending on the size of the aggregates. Therefore slow-growing obligate anaerobic microorganisms such as sulfate reducing bacteria and methanogenic bacteria may be limited by the relatively short persistence of anoxia in marine aggregates. en_US
dc.language en_US
dc.publisher Inter-Research en_US
dc.relation.isbasedon en_US
dc.title Anoxic aggregates - an ephemeral phenomenon in the pelagic environment? en_US
dc.parent Aquatic Microbial Ecology en_US
dc.journal.volume 13 en_US
dc.journal.number en_US
dc.publocation Oldendorf, Germany en_US
dc.identifier.startpage 285 en_US
dc.identifier.endpage 294 en_US SCI.Environmental Sciences en_US
dc.conference Verified OK en_US
dc.for 060200 en_US
dc.personcode 0000062542 en_US
dc.personcode 107129 en_US
dc.personcode 0000062587 en_US
dc.personcode 0000061185 en_US
dc.percentage 100 en_US Ecology en_US
dc.classification.type FOR-08 en_US
dc.edition en_US
dc.custom en_US en_US
dc.location.activity en_US
dc.description.keywords Microelectrodes ? Molecular techniques ? Diffusive boundary layers ? Modeling en_US
dc.staffid en_US

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