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碳同位素比率12C和13C的同位素丰度之比,是研究古气候时,地球植被是否繁茂的一个指示要素.
生物倾向于利用12C , 大气中的12C 通过生物化学过程优先被生物利用。生物死后,一部分转化为化石和沉积物,不再释放到大气中。但是,地质和无机化学过程,对于12C和13C 就不太有“选择性吸收”。
因此,有生物活动的行星,比如地球,12C/13C 的比例可能会偏低。土卫六的比率也值得注意。
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天体(空间介质) 12C/13C同位素丰度比
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太阳风[1] 97.7±10
地球[2]: 89.2±0.3
金星[3]: 185±69
火星[4] : 94.7±13.4
木星[5] : 160(-55~+40)
土卫六[6] : 89.9±3.4
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[1] R. F. Wimmer-Schweingruber1, L. Berger1
THE 13C/12C ISOTOPIC RATIO IN THE SOLAR WIND
[2] Vladimír VanysekJürgen Rahe.The12C/13C isotope ratio in comets, stars and interstellar matter.[J]The moon and the planets.June (1978), Volume 18, Issue 4, pp 441–446
[3] R. T. Clancy, D. O. Muhleman. A measurement of the (C-12)O/(C-13)O) ratio in the mesosphere of Venus [DB]. NASA Technical Reports Server (NTRS).(1983)
[4] V.A.Krasnopolsky, M.J.Mumma et.al. Oxygen and Carbon Isotope Ratios in Martian Carbon Dioxide: Measurements and Implications for Atmospheric Evolution[J].Icarus.Volume 124, Issue 2, December (1996), Pages 553-568
[5] R.Courtin,D.Gautier et.al. The 12C/13C ratio in jupiter from the Voyager infrared investigation[J].Icarus.Volume 53, Issue 1, January (1983), Pages 121-132
[6] Serigano, Joseph; Nixon, C. A.; Cordiner, M. A. el. al. Isotopic Ratios of Carbon and Oxygen in Titan’s CO using ALMA[J] The Astrophysical Journal Letters, Volume 821, Issue 1, article id. L8, 6 pp. (2016).
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