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Anaerobic nitrification–denitrification mediated by Mn-oxides in meso-tidal sediments: Implications for N2 and N2O production..

DRS at CSIR-National Institute of Oceanography

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Title Anaerobic nitrification–denitrification mediated by Mn-oxides in meso-tidal sediments: Implications for N2 and N2O production..
 
Creator Fernandes, S.O.
Javanaud, C.
Aigle, A.
Michotey, V.D.
Guasco, S.
Deborde, J.
Deflandre, B.
Anschutz, P.
Bonin, P.C.
 
Subject nitrification
denitrification
biological production
benthic environment
 
Description Field measurements in the Arcachon Bay (southwest France) indicated anaerobic production of NOx via nitrification, which was coupled to the reduction of Mn-oxides. To prove the occurrence of this process, laboratory microcosm experiments were set up. A 15N tracer-based approach was used to track if NOx produced through Mn-oxide-mediated anaerobic nitrification would be reduced to N2 via denitrification or anammox. We also hypothesized the generation of the potent greenhouse gas nitrous oxide (N2O) during nitrification–denitrification in the presence of Mn-oxides. The microcosms were prepared using sediment sectioned at varying depths (0–2.5, 2.5–4.5, 4.5–8.5, 8.5–12 and 12–17 cm) during two sampling campaigns in October (fall) and January (winter). Labeling with 15NO3− revealed low N2 production originating from NO3− in the water column (Pw), which did not increase significantly on amendment with Mn-oxides during both sampling periods. However, for both seasons, a significant increase of N2 produced via nitrification (Pn) was observed upon addition of Mn-oxides reaching 76-fold enhancement at ≤ 2.5 cm. To support these results, sediment slurries of October were subjected to amendment of 15NH4+, 14NO3− with or without addition of Mn-oxides. A substantial production of P15 (N2 production from 15NH4+) within 0–17 cm provided further evidence on nitrification–denitrification mediated by Mn-oxides probably with minimal intervention of anammox. In organically rich sediments, anaerobic nitrification–denitrification mediated by Mn-oxides could play an important role in lowering re-mineralized NH4+ levels in the benthic system. As hypothesized, significant production of N2O through the pathway was observed revealing newer mechanisms leading to the generation of the radiative gas.
 
Date 2015-02-17T05:19:26Z
2015-02-17T05:19:26Z
2015
 
Type Journal Article
 
Identifier Journal of Marine Systems, vol.144; 1-8
http://drs.nio.org/drs/handle/2264/4705
 
Language en
 
Rights An edited version of this paper was published by Elsevier. Copyright [2014] Elsevier
 
Publisher Elsevier