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Atmospheric Nitrogen When Life Evolved on Earth.
Gebauer, Stefanie; Grenfell, John Lee; Lammer, Helmut; de Vera, Jean-Pierre Paul; Sproß, Laurenz; Airapetian, Vladimir S; Sinnhuber, Miriam; Rauer, Heike.
Afiliação
  • Gebauer S; Institute for Planetary Research (PF), German Aerospace Centre (DLR), Berlin, Germany.
  • Grenfell JL; Institute for Planetary Research (PF), German Aerospace Centre (DLR), Berlin, Germany.
  • Lammer H; Space Research Institute, Austrian Academy of Sciences, Graz, Austria.
  • de Vera JP; Institute for Planetary Research (PF), German Aerospace Centre (DLR), Berlin, Germany.
  • Sproß L; Space Research Institute, Austrian Academy of Sciences, Graz, Austria.
  • Airapetian VS; Institute for Physics, University of Graz, Graz, Austria.
  • Sinnhuber M; NASA Goddard Space Flight Center (GSFC), Greenbelt, Maryland, USA.
  • Rauer H; American University, NW Washington, District of Columbia, USA.
Astrobiology ; 20(12): 1413-1426, 2020 12.
Article em En | MEDLINE | ID: mdl-33121251
ABSTRACT
The amount of nitrogen (N2) present in the atmosphere when life evolved on our planet is central for understanding the production of prebiotic molecules and, hence, is a fundamental quantity to constrain. Estimates of atmospheric molecular nitrogen partial surface pressures during the Archean, however, widely vary in the literature. In this study, we apply a model that combines newly gained insights into atmospheric escape, magma ocean duration, and outgassing evolution. Results suggest <420 mbar surface molecular nitrogen at the time when life originated, which is much lower compared with estimates in previous works and hence could impact our understanding of the production rate of prebiotic molecules such as hydrogen cyanide. Our revised values provide new input for atmospheric chamber experiments that simulate prebiotic chemistry on the early Earth. Our results that assume negligible nitrogen escape rates are in agreement with research based on solidified gas bubbles and the oxidation of iron in micrometeorites at 2.7 Gyr ago, which suggest that the atmospheric pressure was probably less than half the present-day value. Our results contradict previous studies that assume N2 partial surface pressures during the Archean were higher than those observed today and suggest that, if the N2 partial pressure were low in the Archean, it would likely be low in the Hadean as well. Furthermore, our results imply a biogenic nitrogen fixation rate from 9 to 14 Teragram N2 per year (Tg N2/year), which is consistent with modern marine biofixation rates and, hence, indicate an oceanic origin of this fixation process.
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Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Atmosfera / Planeta Terra / Origem da Vida / Nitrogênio Idioma: En Ano de publicação: 2020 Tipo de documento: Article

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Atmosfera / Planeta Terra / Origem da Vida / Nitrogênio Idioma: En Ano de publicação: 2020 Tipo de documento: Article