The early atmosphere as a source of biogenic compounds

Kasting, James F.; Brown, L. L.

doi:10.1017/cbo9780511626180.004

Cited by 82 publications

(63 citation statements)

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“…The value for the CH 4 concentration on the prebiotic Earth is not certain, because the magnitude of abiotic CH 4 production from possible sources such as mid-Atlantic ridges (47) is unknown. However, it is possible that the abiotic sources may have supported a mixing ratio of CH 4 up to 1 ϫ 10 Ϫ4 (48). With this amount of CH 4 in the atmosphere, the CO 2 mixing ratio on an unfrozen early Earth is expected to be at least 3 ϫ 10 Ϫ4 (23).…”

Section: Implications For Early Earthmentioning

confidence: 99%

Organic haze on Titan and the early Earth

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

236

267

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Recent exploration by the Cassini͞Huygens mission has stimulated a great deal of interest in Saturn's moon, Titan. One of Titan's most captivating features is the thick organic haze layer surrounding the moon, believed to be formed from photochemistry high in the CH 4͞N2 atmosphere. It has been suggested that a similar haze layer may have formed on the early Earth. Here we report laboratory experiments that demonstrate the properties of haze likely to form through photochemistry on Titan and early Earth. We have used a deuterium lamp to initiate particle production in these simulated atmospheres from UV photolysis. Using a unique analysis technique, the aerosol mass spectrometer, we have studied the chemical composition, size, and shape of the particles produced as a function of initial trace gas composition. Our results show that the aerosols produced in the laboratory can serve as analogs for the observed haze in Titan's atmosphere. Experiments performed under possible conditions for early Earth suggest a significant optical depth of haze may have dominated the early Earth's atmosphere. Aerosol size measurements are presented, and implications for the haze layer properties are discussed. We estimate that aerosol production on the early Earth may have been on the order of 10 14 g⅐year ؊1 and thus could have served as a primary source of organic material to the surface.planetary atmospheres ͉ tholins ͉ atmospheric aerosol ͉ Archaen ͉ astrobiology

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Section: Implications For Early Earthmentioning

confidence: 99%

Organic haze on Titan and the early Earth

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

236

267

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“…The relevance of all of this early work to the origin of life has been questioned because it now seems very unlikely that the Earth's atmosphere was ever as strongly reducing as Miller and Urey assumed. However, it still seems possible that that the Earth's atmosphere was once sufficiently reducing to have supported Miller/Urey chemistry to some extent (Kasting & Brown, 1998).…”

Section: Prebiotic Synthesis Of Nucleotides Prebiotic Synthesismentioning

confidence: 99%

Prebiotic Chemistry and the Origin of the RNA World

Orgel

2004

Critical Reviews in Biochemistry and Molecular Biology

909

248

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The demonstration that ribosomal peptide synthesis is a ribozyme-catalyzed reaction makes it almost certain that there was once an RNA World. The central problem for origin-of-life studies, therefore, is to understand how a protein-free RNA World became established on the primitive Earth. We first review the literature on the prebiotic synthesis of the nucleotides, the nonenzymatic synthesis and copying of polynucleotides, and the selection of ribozyme catalysts of a kind that might have facilitated polynucleotide replication. This leads to a brief outline of the Molecular Biologists' Dream, an optimistic scenario for the origin of the RNA World. In the second part of the review we point out the many unresolved problems presented by the Molecular Biologists' Dream. This in turn leads to a discussion of genetic systems simpler than RNA that might have "invented" RNA. Finally, we review studies of prebiotic membrane formation.

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“…Kasting et al 1984;Kasting & Brown 1998) has shown that rainout of photochemically produced oxidants and reductants is also important in the atmospheric redox balance. Indeed, rainout of oxidants such as H 2 O 2 and H 2 SO 4 becomes significant at atmospheric O 2 levels that are substantially lower than those shown in figure 7b.…”

Section: Possible Cause Of the Mid-archaean Glaciationsmentioning

confidence: 99%

Palaeoclimates: the first two billion years

Kasting

Ono

2006

Phil. Trans. R. Soc. B

124

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Earth's climate during the Archaean remains highly uncertain, as the relevant geologic evidence is sparse and occasionally contradictory. Oxygen isotopes in cherts suggest that between 3.5 and 3.2 Gyr ago (Ga) the Archaean climate was hot (55-85 8C); however, the fact that these cherts have experienced only a modest amount of weathering suggests that the climate was temperate, as today. The presence of diamictites in the Pongola Supergroup and the Witwatersrand Basin of South Africa suggests that by 2.9 Ga the climate was glacial. The Late Archaean was relatively warm; then glaciation (possibly of global extent) reappeared in the Early Palaeoproterozoic, around 2.3-2.4 Ga.Fitting these climatic constraints with a model requires high concentrations of atmospheric CO 2 or CH 4 , or both. Solar luminosity was 20-25% lower than today, so elevated greenhouse gas concentrations were needed just to keep the mean surface temperature above freezing. A rise in O 2 at approximately 2.4 Ga, and a concomitant decrease in CH 4 , provides a natural explanation for the Palaeoproterozoic glaciations. The Mid-Archaean glaciations may have been caused by a drawdown in H 2 and CH 4 caused by the origin of bacterial sulphate reduction. More work is needed to test this latter hypothesis.

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The early atmosphere as a source of biogenic compounds

Cited by 82 publications

References 0 publications

Organic haze on Titan and the early Earth

Organic haze on Titan and the early Earth

Prebiotic Chemistry and the Origin of the RNA World

Palaeoclimates: the first two billion years

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