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| Titel |
Vertical activity distribution of dissimilatory nitrate reduction in coastal marine sediments |
| VerfasserIn |
A. Behrendt, D. de Beer, P. Stief |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 11 ; Nr. 10, no. 11 (2013-11-21), S.7509-7523 |
| Datensatznummer |
250085430
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| Publikation (Nr.) |
 copernicus.org/bg-10-7509-2013.pdf |
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| Zusammenfassung |
| The relative importance of two dissimilatory nitrate reduction pathways,
denitrification (DEN) and dissimilatory nitrate reduction to ammonium
(DNRA), was investigated in intact sediment cores from five different
coastal marine field sites (Dorum, Aarhus Bight, Mississippi Delta, Limfjord
and Janssand). The vertical distribution of DEN activity was examined using
the acetylene inhibition technique combined with N2O microsensor
measurements, whereas NH4+ production via DNRA was measured with a
recently developed gel probe-stable isotope technique. At all field sites,
dissimilatory nitrate reduction was clearly dominated by DEN (59–131% of
the total NO3− reduced) rather than by DNRA, irrespective of the
sedimentary inventories of electron donors such as organic carbon, sulfide,
and iron. Highest ammonium production via DNRA, accounting for up to 8.9%
of the total NO3− reduced, was found at a site with very high
concentrations of total sulfide and NH4+ within and below the
layer in which NO3− reduction occurred. Sediment from two field
sites, one with low and one with high DNRA activity in the core incubations,
was also used for slurry incubations. Now, in both sediments high DNRA
activity was detected accounting for 37–77% of the total NO3−
reduced. These contradictory results might be explained by enhanced
NO3− availability for DNRA bacteria in the sediment slurries
compared to the core-incubated sediments in which diffusion of
NO3− from the water column may only reach DEN bacteria, but not
DNRA bacteria. The true partitioning of dissimilatory nitrate reduction
between DNRA and DEN may thus lie in between the values found in whole core
(underestimation of DNRA) and slurry incubations (overestimation of DNRA). |
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