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| Titel |
Anammox, denitrification and dissimilatory nitrate reduction to ammonium in the East China Sea sediment |
| VerfasserIn |
G. D. Song, S. M. Liu, H. Marchant, M. M. M. Kuypers, G. Lavik |
| 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 (2013-11-02), S.6851-6864 |
| Datensatznummer |
250085387
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| Publikation (Nr.) |
 copernicus.org/bg-10-6851-2013.pdf |
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| Zusammenfassung |
| Benthic nitrogen transformation pathways were investigated in the sediment
of the East China Sea (ECS) in June of 2010 using the 15N isotope
pairing technique. Slurry incubations indicated that denitrification,
anammox and dissimilatory nitrate reduction to ammonium (DNRA) as well as
intracellular nitrate release occurred in the ECS sediments. These four
processes did not exist independently, nitrate release therefore diluted the
15N labeling fraction of NO3−, and a part of the
15NH4+ derived from DNRA also formed 30N2 via
anammox. Therefore, current methods of rate calculations led to over and
underestimations of anammox and denitrification respectively. Following the
procedure outlined in Thamdrup and Dalsgaard (2002), denitrification rates
were slightly underestimated by an average 6% without regard to the
effect of nitrate release, while this underestimation could be counteracted
by the presence of DNRA. On the contrary, anammox rates calculated from
15NO3− experiment were significantly overestimated by 42%
without considering nitrate release. In our study, this overestimation could
only be compensated 14% by taking DNRA into consideration. In a parallel
experiment amended with 15NH4++14NO3−,
anammox rates were not significantly influenced by DNRA due to the high
background of 15NH4+ addition. The significant correlation
between potential denitrification rate and sediment organic matter content
(r = 0.68, p < 0.001, Pearson) indicated that denitrification was
regulated by organic matter, while, no such correlations were found for
anammox and DNRA. The relative contribution of anammox to the total N-loss
increased from 13% at the shallowest site near the Changjiang estuary to
50% at the deepest site on the outer shelf, implying the significant role
of anammox in benthic nitrogen cycling in the ECS sediments, especially on
the outer shelf. N-loss as N2 was the main pathway, while DNRA was also
an important pathway accounting for 20–31% of benthic nitrate reduction
in the ECS. Our study demonstrates the complicated interactions among
different benthic nitrogen transformations and the importance of considering
denitrification, DNRA, anammox and nitrate release together when designing
and interpreting future studies. |
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