Isotopic Evidence for an Aerobic Nitrogen Cycle in the Latest Archean (Science, 2009)

• Roger Buick

Full Citation:
Garvin, J., Buick, R., Anbar, A. D., Arnold, G. L., & Kaufman, A. J. (2009). Isotopic Evidence for an Aerobic Nitrogen Cycle in the Latest Archean. Science, 323(5917), 1045–1048. https://doi.org/10.1126/science.1165675

Abstract:
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.

URL:
https://science.sciencemag.org/content/323/5917/1045

VPL Research Tasks:
Task B: The Earth Through Time