Organic compounds in the early atmosphere formed abiotically from atomic carbon

Abstract

ZusammenfassungDie Entdeckung des atomar gelSsten Kohlenstoffs in Olivinen aus Mantelgesteinen fiihrt zu neuen Vorstellungen fiber die Zusammensetzung der Uratmosph~ire und Entwicklungsbedingungen des Lebens. Atomarer Kohlenstoff im MgO ist in der Lage, in einer O2-freien Atmosph/ire mit dem Gittersauerstoff zu CO9 zu reagieren und mit dem aus OH-stammendeu Gitterwasserstoff eine gro13e Vielfalt yon organischen Verbindungen zu bilden.Dfffusionsprozesse und Gas-Festk6rper-Austauschreaktionen, die an diesen Reaktionen beteiligt sind, ffihren nach ersten Untersuchungen zu einer 13C-Anreicherung ira COo und einer 13C-Abreicherung bei den Kohlenwasserstoffen. Diese 12C/13C-Fraktionierung ist gleichsinnig mit der biologischen 12C/13C-Fraktionierung.Atomarer Kohlenstoff in Olivinen und Basalten zeigt ein sehr /ihnliches Reaktionsverhalten wie im MgO und fiihrt zu iihnlichen Reaktionsprodukten: 1--2 mg/g CO2 und 25--100 /zg/g Kohlenwasserstoffe zwischen 400--1000 ~ t2bertragen auf geologische Verh/iltnisse bedeutet dies, dab jeder kin 3 eines entgasenden basaltischen Magmas 3--6.109 kg (2.109 m s) CO2 und 1---3" 10 s kg (2" l0 s m 3) abiotischen Kohlenwasserstoff abgeben kann. Die Anwesenheit yon Wasser fiihrt zur Bildung yon Alkoholen und organischen S'auren. Diese Ergebnisse deuten darauf hin, dal3 die Uratmosphiire und die ,,Ursuppe" viel reicher waren als bisher angenommen an komplexen organischen Verbindungen, die rein thermisch entstanden sind. AbstractThe recent discovery that atomic carbon occurs plentiful in olivines from mantlederived rocks opens new aspects for the chemical evolution of the early atmosphere and the origin of life. It has been shown conclusively that atomic carbon which is dissolved in the model oxide MgO is capable of reacting in an O2-free atmosphere with the lattice oxygen to give CO~ and with the lattice hydrogen, derived from OH-, to give a profuse variety of hydrocarbons.The dfffusional processes and low temperature gas/solid interface reactions involved in these processes are expected to introduce, purely abiotically, isotope fraetionation resulting in a lzC enrichment of the CO s fraction and in a xzC depletion of the hydrocarbon fraction which may be confused with the ~C/~3C isotope fractionation along biological pathways. Atomic carbon dissolved in olivines and in basalts shows a similar behaviour and yields similar quantities as C in MgO: 1--2 mg/g CO~ and 9.5--100 #g/g hydrocarbons degassing between 400 and 1000 ~ On a geological scale this means that each cubic kilometer of basaltic magma degassing in an O2-free atmosphere has the capacity ot sending off about 3--6.109 kg (2.109 m ~) of CO9~ and about 1--3.10 s kg (2-108 m 9) of hydrocarbons. The presence of water modifies the composition to give, among others, alcohols and organic acids.On the basis of these results we are led to the conclusion that the early atmosphere of the earth may have contained a very high concentration of abiotically formed "organic" compounds of great chemical complexity. R6sum6La d6couverte du carbone at...

Incorporation of H2 in vitreous silica, qualitative and quantitative determination from Raman and infrared spectroscopy

“…Because of the centrosymmetry of diatomic, homonuclear molecules, the vibrations of undisturbed H 2 molecules are not IR-active and such a band should not be present in the IR spectra. Freund et al [40] attributed a band at 4130 cm −1 in the infrared spectra of crystalline CaO, to the H-H stretching mode of H 2 molecules located in non-centrosymmetrical sites. A similar effect may be responsible for the H-H vibration band in the IR absorption spectra of our samples, implying that H 2 molecules are bonded to the silicate framework or are distorted by the asymmetric field within the interstices of the silicate network.…”

Manometric and mass spectrometric analysis of fluids in geological meterials.

“…They can be the result of reactions during heating of samples. Carbon can reside in microcracks, in solid inclusions like graphite, carbynes (-C=C-) or bituminous matter (Mathez and Delaney, 1981); carbon atoms can also be inserted in silicate frameworks (Freund et al, 1982). As the temperature increases, water and carbon dioxide are reduced to hydrogen and carbon monoxide:…”