@article{136,
  author = {X. Zhang and D.M. Sigman and F.M.M. Morel and },
  title = {Nitrogen isotope fractionation by alternative nitrogenases and past ocean anoxia},
  abstract = {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 (δ15N) of newly fixed N is currently believed to be\~{}-10/00, 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 δ15N (-6 to -70/00). An important contribution of alternative nitrogenases to N2 fixation provides a simple explanation for the anomalously low δ15N (\<-20/00) 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.},
  year = {2014},
  journal = {Proceedings of the National Academy of Sciences of the United States of America},
  volume = {111},
  number = {13},
  pages = {4782-4787},
  url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897561647\&doi=10.1073\%2fpnas.1402976111\&partnerID=40\&md5=5038509bbbc9996e8d5dbbf1d5565c96},
  doi = {10.1073/pnas.1402976111},
}