Nitrogen isotope fractionation by alternative nitrogenases and past ocean anoxia
Open accessAbstract
Biological nitrogen fixation constitutes the main input of fixed nitrogen to Earth's ecosystems, and its isotope effect is a key parameter in isotope-based interpretations of the N cycle. The nitrogen isotopic composition (δ(15)N) of newly fixed N is currently believed to be ∼-1‰, based on measurements of organic matter from diazotrophs using molybdenum (Mo)-nitrogenases. We show that the vanadium (V)- and iron (Fe)-only "alternative" nitrogenases produce fixed N with significantly lower δ(15)N (-6 to -7‰). An important contribution of alternative nitrogenases to N2 fixation provides a simple explanation for the anomalously low δ(15)N (<-2‰) in sediments from the Cretaceous Oceanic Anoxic Events and the Archean Eon. A significant role for the alternative nitrogenases over Mo-nitrogenase is also consistent with evidence of Mo scarcity during these geologic periods, suggesting an additional dimension to the coupling between the global cycles of trace elements and nitrogen.
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V-Fe nitrogenase varieties might have contributed to nitrogen fixation during the Paleoproterozoic, although the V variety is less efficient.
“Both Anbar and Knoll (2002) and Zhang et al. (2014) suggested that the V-Fe nitrogenase varieties might have contributed to nitrogen fixation during the Paleoproterozoic, although the V variety is less efficient (Eady, 1996).”
From Trace elements at the intersection of marine biological and geochemical evolution (2016) · cites this paper as Zhang et al. (2014)
Low δ15N values in Archean cherts may be more consistent with alternative nitrogenases using Fe or V instead of Mo, suggesting a more important role for these variants in deep time.
“Zhang et al. (2014) indicated that low δ 15 N values in Archean cherts may be more consistent with alternative nitrogenases using Fe or V instead of Mo, suggesting a more important role for these variants in deep time”
From Trace elements at the intersection of marine biological and geochemical evolution (2016) · cites this paper as Zhang et al. (2014)
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- Authors
- Zhang, X., Sigman, D. M., Morel, F. M. M., & Kraepiel, A. M. L.
- Affiliations
- Princeton University (US)
- Departments of aGeosciences and
- Venue
- Proceedings of the National Academy of Sciences
- Publisher
- National Academy of Sciences
- Published
- 2014-03-17
- Volume
- 111
- Issue
- 13
- Pages
- 4782-4787
- ISSN
- 0027-8424 (ISSN-L)
- 1091-6490
- PMC
- PMC3977277
- OpenAlex
- W2034320900
- Cited by
- 215
- References
- 81
- Citations by year
- 2026: 12 · 2025: 23 · 2024: 31 · 2023: 17 · 2022: 16 · 2021: 22 · 2020: 17 · 2019: 21 · 2018: 19 · 2017: 10 · 2016: 15 · 2015: 9 · 2014: 2
- FWCI
- 8.74
- Type
- journal article
- Language
- en
- Open access
- green
- www.ncbi.nlm.nih.gov
- Locations
- Proceedings of the National Academy of Sciences (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Physical Sciences › Earth and Planetary Sciences › Paleontology › Paleontology and Stratigraphy of Fossils
- Physical Sciences › Energy › Renewable Energy, Sustainability and the Environment › Metalloenzymes and iron-sulfur proteins
- Physical Sciences › Earth and Planetary Sciences › Oceanography › Marine and coastal ecosystems
- Keywords
- nitrogen isotope fractionation, alternative nitrogenases, vanadium nitrogenase, iron nitrogenase, molybdenum nitrogenase, nitrogen fixation, ocean anoxia, oceanic anoxic events, Cretaceous sediments, trace element cycling, nitrogen cycling
- MeSH terms
- Anaerobiosis, Bacteria, Chemical Fractionation, Metals, Nitrogen Fixation, Nitrogen Isotopes, Nitrogenase, Oceans and Seas, Biomass, Geologic Sediments
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