Iron‐mediated anaerobic ammonium oxidation recorded in the early Archean ferruginous ocean
Résumé
Nitrogen is an essential nutrient for all living organisms, and its availability strongly influences biological productivity. As water column redox speciation controls active metabolic pathways of the biogeochemical nitrogen cycle, the nitrogen isotopic composition of sedimentary rocks can record oceanic redox changes in the early oceans. On the modern Earth, the atmosphere is the main surface nitrogen reservoir, where N is present mostly as gaseous dinitrogen N 2 (Ward, 2012, δ 15 N = 0‰). However, nitrogen in its N 2 form can only be assimilated by diazotrophs, prokaryotic organisms who possess the nitrogenase enzyme and are thus capable of biological N 2 fixation (Raymond et al., 2004). Bioavailable "fixed" forms of nitrogen are therefore almost exclusively provided to the biosphere by N 2-fixating
Origine | Fichiers éditeurs autorisés sur une archive ouverte |
---|