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Nitrogen Oxides in Early Earth's Atmosphere as Electron Acceptors for Life's Emergence

Wong, Michael L. and Charnay, Benjamin D. and Gao, Peter and Yung, Yuk L. and Russell, Michael J. (2017) Nitrogen Oxides in Early Earth's Atmosphere as Electron Acceptors for Life's Emergence. Astrobiology, 17 (10). pp. 975-983. ISSN 1531-1074. doi:10.1089/ast.2016.1473.

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We quantify the amount of nitrogen oxides (NOx) produced through lightning and photochemical processes in the Hadean atmosphere to be available in the Hadean ocean for the emergence of life. Atmospherically generated nitrate (NO_3−) and nitrite (NO_2−) are the most attractive high-potential electron acceptors for pulling and enabling crucial redox reactions of autotrophic metabolic pathways at submarine alkaline hydrothermal vents. The Hadean atmosphere, dominated by CO_2 and N_2, will produce nitric oxide (NO) when shocked by lightning. Photochemical reactions involving NO and H_2O vapor will then produce acids such as HNO, HNO_2, HNO_3, and HO_2NO_2 that rain into the ocean. There, they dissociate into or react to form nitrate and nitrite. We present new calculations based on a novel combination of early-Earth global climate model and photochemical modeling, and we predict the flux of NOx to the Hadean ocean. In our 0.1-, 1-, and 10-bar pCO_2 models, we calculate the NOx delivery to be 2.4 × 10^5, 6.5 × 10^8, and 1.9 × 10^8 molecules cm^(−2) s^(−1). After only tens of thousands to tens of millions of years, these NOx fluxes are expected to produce sufficient (micromolar) ocean concentrations of high-potential electron acceptors for the emergence of life.

Item Type:Article
Related URLs:
URLURL TypeDescription
Gao, Peter0000-0002-8518-9601
Yung, Yuk L.0000-0002-4263-2562
Additional Information:© 2017 Mary Ann Liebert, Inc. Submitted 25 January 2016; Accepted 22 March 2017; Online Ahead of Print: October 12, 2017. This research was supported in part by an NAI Virtual Planetary Laboratory grant from the University of Washington to the Jet Propulsion Laboratory and California Institute of Technology. B.D.C. acknowledges support from an appointment to the NASA Postdoctoral Program, administered by Universities Space Research Association. M.J.R.'s research was supported by the National Aeronautics and Space Administration, through the NASA Astrobiology Institute under cooperative agreement issued through the Science Mission directorate; No. NNH13ZDA017C (Icy Worlds) at the Jet Propulsion Laboratory. No competing financial interests exist.
Group:Astronomy Department
Funding AgencyGrant Number
University of WashingtonUNSPECIFIED
NASA Postdoctoral ProgramUNSPECIFIED
Subject Keywords:Nitrogen oxides; Nitrate; Nitrite; Photochemistry; Lightning; Emergence of life
Issue or Number:10
Record Number:CaltechAUTHORS:20171016-153957584
Persistent URL:
Official Citation:Wong Michael L., Charnay Benjamin D., Gao Peter, Yung Yuk L., and Russell Michael J.. Astrobiology. October 2017, 17(10): 975-983.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:82391
Deposited By: Tony Diaz
Deposited On:17 Oct 2017 21:39
Last Modified:15 Nov 2021 19:50

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