Anaerobic ammonium oxidation by nitrite (anammox): Implications for N 2 production in coastal marine sediments
Abstract
The respiratory reduction of nitrate (denitrification) is acknowledged as the most important process that converts biologically available nitrogen to gaseous dinitrogen (N 2) in marine ecosystems. Recent findings, however, indicate that anaerobic ammonium oxidation by nitrite (anammox) may be an important pathway for N 2 formation and N removal in coastal marine sediments and in anoxic water columns of the oceans. In the present study, we explored this novel mechanism during N mineralization by 15N amendments (single and coupled additions of 15NH 4+, 14NO 3- and 15NO 3-) to surface sediments with a wide range of characteristics and overall reactivity. Patterns of 29/30N 2 production in the pore water during closed sediment incubations demonstrated anammox at all 7 of the investigated sites. Stoichiometric calculations revealed that 4% to 79% of total N 2 production was due to this novel route. The relative importance of anammox for N 2 release was inversely correlated with remineralized solute production, benthic O 2 consumption, and surface sediment Chl a. The observed correlations indicate competition between reductants for pore water nitrite during early diagenesis and that additional factors (e.g. availability of Mn-oxides), superimposed on overall patterns of diagenetic activity, are important for determining absolute and relative rates of anammox in coastal marine sediments.
- Publication:
-
Geochimica et Cosmochimica Acta
- Pub Date:
- April 2005
- DOI:
- 10.1016/j.gca.2004.09.032
- Bibcode:
- 2005GeCoA..69.2057E