Isotopic evidence for an aerobic nitrogen cycle in the latest Archean

Jessica Garvin, Roger Buick, Ariel Anbar, Gail L. Arnold, Alan J. Kaufman

Research output: Contribution to journalArticlepeer-review

196 Scopus citations


The nitrogen cycle provides essential nutrients to the biosphere, but its antiquity in modern form is unclear. In a drill core though homogeneous organic-rich shale in the 2.5-billion-year-old Mount McRae Shale, Australia, nitrogen isotope values vary from +1.0 to +7.5 per mil (‰) and back to +2.5‰ over ∼30 meters. These changes evidently record a transient departure from a largely anaerobic to an aerobic nitrogen cycle complete with nitrification and denitrification. Complementary molybdenum abundance and sulfur isotopic values suggest that nitrification occurred in response to a small increase in surface-ocean oxygenation. These data imply that nitrifying and denitrifying microbes had already evolved by the late Archean and were present before oxygen first began to accumulate in the atmosphere.

Original languageEnglish (US)
Pages (from-to)1045-1048
Number of pages4
Issue number5917
StatePublished - Feb 20 2009

ASJC Scopus subject areas

  • General


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