High yield shock synthesis of ammonia from iron, water and nitrogen available on the early Earth

Ammonia is a necessary precursor of amino acids in terms of the origin of life on the early Earth. However, the formation of ammonia is problematic in the non-reducing atmosphere that presently believed on the early Earth. The abiotic reduction of nitrogen is, therefore, debated currently in the oceanic and hydrothermal conditions [J.A. Brandes, N.Z. Boctor, G.D. Cody, B.A. Cooper, R.M. Hazen, H.S. Yoder Jr., Abiotic nitrogen reduction on the early Earth, Nature 395 (1998), 365-367; D.P.Summers, S. Chang, Prebiotic ammonia from reduction of nitrite by iron (11) on the early Earth, Nature 365 (1993), 630-633; M. Dorr, J. Kaessbohrer, R. Grunert, G. Kreisel, W.A. Brand, R.A. Werner, H. Geilmann, C. Apfel, C. Robl, W. Weigand, A possible prebiotic formation of ammonia from dinitrogen on iron sulfide surfaces, Angew. Chem. Int. Ed. 42 (2003), 1540-1543 [1-3]]. Here we perform shock experiments with Cu3N (nitrogen source), Fe and H2O, supposing an impact event of an extraterrestrial object to the ocean. The results demonstrate clearly the formation of ammonia in high yields. This reduction process from nitrogen to ammonia is highly probable as local and transitional phenomena on the early Earth when the heavy bombardment by extraterrestrial objects had become less intense but still continued in the period from 4.3 to 3.5 Gyr ago. (c) 2005 Elsevier B.V. All rights reserved.