Earth's core could be the largest terrestrial carbon reservoir
Earth's core could be the largest terrestrial carbon reservoir
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DOI：
10.1038/s43247-021-00222-7
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发表时间：
2021-08-19
影响因子：
7.9
通讯作者：
Dasgupta, Rajdeep
中科院分区：
文献类型：
--
作者：
Bajgain, Suraj K.;Mookherjee, Mainak;Dasgupta, Rajdeep
评估碳作为地球核心的一种轻元素的候选资格，对于限制这种生命必需元素的预算和在行星尺度上的分布至关重要。本文采用第一性原理分子动力学模拟方法，在0 ~ 360吉帕斯卡和4000 ~ 7000开尔文条件下，估计了含碳量为4 ~ 9wt .%的液态铁碳合金的密度和纵波速度。我们发现，对于铁-碳双星系统，类似1-4 wt.%的碳可以解释地震纵波速度。然而，这与我们发现解释地核密度缺陷所需要的5-7 wt.%的碳是不相容的。当我们考虑包含铁、碳和另一种轻元素的三元体系时，结合铁陨石的附加约束和内核边界的密度不连续，我们发现外核的碳含量为0.3-2.0 wt.%，能够满足这两个性质。这可能使外核成为最大的陆地碳储存库。
Evaluating carbon's candidacy as a light element in the Earth's core is critical to constrain the budget and planet-scale distribution of this life-essential element. Here we use first principles molecular dynamics simulations to estimate the density and compressional wave velocity of liquid iron-carbon alloys with similar to 4-9 wt.% carbon at 0-360 gigapascals and 4000-7000 kelvin. We find that for an iron-carbon binary system, similar to 1-4 wt.% carbon can explain seismological compressional wave velocities. However, this is incompatible with the similar to 5-7 wt.% carbon that we find is required to explain the core's density deficit. When we consider a ternary system including iron, carbon and another light element combined with additional constraints from iron meteorites and the density discontinuity at the inner-core boundary, we find that a carbon content of the outer core of 0.3-2.0 wt.%, is able to satisfy both properties. This could make the outer core the largest reservoir of terrestrial carbon.