Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015, USA.
Science. 2012 Aug 10;337(6095):721-3. doi: 10.1126/science.1223474. Epub 2012 Jul 12.
Determining the source(s) of hydrogen, carbon, and nitrogen accreted by Earth is important for understanding the origins of water and life and for constraining dynamical processes that operated during planet formation. Chondritic meteorites are asteroidal fragments that retain records of the first few million years of solar system history. The deuterium/hydrogen (D/H) values of water in carbonaceous chondrites are distinct from those in comets and Saturn's moon Enceladus, implying that they formed in a different region of the solar system, contrary to predictions of recent dynamical models. The D/H values of water in carbonaceous chondrites also argue against an influx of water ice from the outer solar system, which has been invoked to explain the nonsolar oxygen isotopic composition of the inner solar system. The bulk hydrogen and nitrogen isotopic compositions of CI chondrites suggest that they were the principal source of Earth's volatiles.
确定地球所吸积的氢、碳和氮的来源对于理解水和生命的起源以及限制行星形成过程中所涉及的动力学过程非常重要。球粒陨石是保留了太阳系最初几百万年历史记录的小行星碎片。碳质球粒陨石中水的氘/氢 (D/H) 值与彗星和土星卫星土卫二的不同，这表明它们形成于太阳系的不同区域，与最近动力学模型的预测相反。碳质球粒陨石中水的 D/H 值也反对来自太阳系外部的水冰的涌入，这种涌入被用来解释太阳系内部非太阳的氧同位素组成。CI 球粒陨石的氢和氮同位素组成表明它们是地球挥发物的主要来源。
