Letters to Nature

Nature 412, 61-64 (5 July 2001) | doi:10.1038/35083537; Received 10 November 2000; Accepted 21 May 2001

A possible nitrogen crisis for Archaean life due to reduced nitrogen fixation by lightning

Rafael Navarro-González1, Christopher P. McKay2 & Delphine Nna Mvondo1

  1. Laboratorio de Química de Plasmas y Estudios Planetarios, Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Apartado Postal 70-543, México Distrito Federal 04510, Mexico
  2. Space Science Division, NASA-Ames Research Center, Moffett Field, California 94035-1000, USA

Correspondence to: Rafael Navarro-González1 Correspondence and requests for materials should be addressed to R.N.-G. (e-mail: Email: Navarro@nuclecu.unam.mx).

Nitrogen is an essential element for life and is often the limiting nutrient for terrestrial ecosystems1, 2. As most nitrogen is locked in the kinetically stable form3, N2, in the Earth's atmosphere, processes that can fix N2 into biologically available forms—such as nitrate and ammonia—control the supply of nitrogen for organisms. On the early Earth, nitrogen is thought to have been fixed abiotically, as nitric oxide formed during lightning discharge4, 5, 6. The advent of biological nitrogen fixation suggests that at some point the demand for fixed nitrogen exceeded the supply from abiotic sources, but the timing and causes of the onset of biological nitrogen fixation remain unclear7, 8, 9, 10, 11. Here we report an experimental simulation of nitrogen fixation by lightning over a range of Hadean (4.5–3.8 Gyr ago) and Archaean (3.8–2.5 Gyr ago) atmospheric compositions, from predominantly carbon dioxide to predominantly dinitrogen (but always without oxygen). We infer that, as atmospheric CO2 decreased over the Archaean period, the production of nitric oxide from lightning discharge decreased by two orders of magnitude until about 2.2 Gyr. After this time, the rise in oxygen (or methane) concentrations probably initiated other abiotic sources of nitrogen. Although the temporary reduction in nitric oxide production may have lasted for only 100 Myr or less, this was potentially long enough to cause an ecological crisis that triggered the development of biological nitrogen fixation.