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Volumn 308, Issue 5724, 2005, Pages 1014-1017

A hydrogen-rich early Earth atmosphere

Author keywords

[No Author keywords available]

Indexed keywords

DEGASSING; HYDROGEN; HYDROTHERMAL SYNTHESIS; OCEANOGRAPHY; ORGANIC COMPOUNDS; VOLCANOES;

EID: 18644381196     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.1106983     Document Type: Article
Times cited : (335)

References (40)
  • 9
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    • note
    • 3 could have been adequate to maintain high concentrations of these gases.
  • 10
    • 18644372431 scopus 로고    scopus 로고
    • note
    • -3 or below (21, 31), unless the oxidation state of Earth's mantle was more reduced than its current oxidation state. But Earth's mantle has been suggested to be in a similar oxidation state to that of today for the past 3.96 billion years (32). The common consensus among planetary scientists for the past 30 years has been that early Earth's atmosphere had a low hydrogen concentration.
  • 11
    • 18644379720 scopus 로고    scopus 로고
    • note
    • However, experiments to date generate only methane or formate in realistic hydrothermal-like systems (33). The exogenous flux of organic materials at about 4 billion years ago (Ga), primarily interplanetary dust particles (IDPs), may be less than 150 times the present value (34), although the interpretations of the Akilia rocks are debatable (35).
  • 14
    • 2142803437 scopus 로고    scopus 로고
    • Materials and methods are available as supporting material on Science Online.
    • Science Online
  • 15
    • 0345792735 scopus 로고    scopus 로고
    • H. Lammer et al., Icarus 165, 9 (2003).
    • (2003) Icarus , vol.165 , pp. 9
    • Lammer, H.1
  • 18
    • 18644377143 scopus 로고    scopus 로고
    • note
    • Nonthermal escape from a hydrogen-rich early Earth has not been studied in detail. Although a similar upper limit of nonthermal hydrogen escape rate should apply to early Earth, it is important to note that non-thermal hydrogen escape processes may also be rather different for Earth than for Venus because of the presence of a strong magnetic field on Earth. Future work should include these processes in escape models to make more accurate estimates.
  • 20
    • 18644374267 scopus 로고    scopus 로고
    • note
    • -1) for the same homopause hydrogen density. Hence, the diffusive flux does not become limiting except for extreme EUV input.
  • 22
    • 18644374658 scopus 로고    scopus 로고
    • note
    • 2 (21). Therefore, the homopause mixing ratio of hydrogen is representative of the whole homosphere.
  • 23
    • 18644384493 scopus 로고    scopus 로고
    • note
    • 7 kg/year) of the amino acid production rate by electric discharge is taken.
  • 24
    • 18644363088 scopus 로고    scopus 로고
    • note
    • -7 mole/liter, assuming a mean molecular weight of 100) in 10 million years, which is the time scale for the entire ocean to circulate through submarine vents at 300°C, potentially destroying the organics (25).
  • 28
    • 18644369697 scopus 로고    scopus 로고
    • note
    • 8 kg/year (39). Therefore, the production of prebiotic organic compounds by UV in a hydrogen-rich atmosphere is ∼2 orders of magnitude greater than the delivery of organic compound from outer space or the synthesis of organic compounds in hydrothermal systems at 3.8 Ga.
  • 40
    • 18644381015 scopus 로고    scopus 로고
    • note
    • We thank two anonymous reviewers and J. F. Kasting for valuable comments. This study was supported by the NASA Astrobiology Institute.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.