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Simulating Serpentinization as It Could Apply to the Emergence of Life Using the JPL Hydrothermal Reactor.
Astrobiology ( IF 3.5 ) Pub Date : 2020-03-01 , DOI: 10.1089/ast.2018.1949
Lauren M White 1, 2, 3 , Takazo Shibuya 4, 5 , Steven D Vance 1 , Lance E Christensen 1 , Rohit Bhartia 1 , Richard Kidd 1 , Adam Hoffmann 1 , Galen D Stucky 2, 6 , Isik Kanik 1 , Michael J Russell 1
Affiliation  

The molecules feeding life's emergence are thought to have been provided through the hydrothermal interactions of convecting carbonic ocean waters with minerals comprising the early Hadean oceanic crust. Few laboratory experiments have simulated ancient hydrothermal conditions to test this conjecture. We used the JPL hydrothermal flow reactor to investigate CO2 reduction in simulated ancient alkaline convective systems over 3 days (T = 120°C, P = 100 bar, pH = 11). H2-rich hydrothermal simulant and CO2-rich ocean simulant solutions were periodically driven in 4-h cycles through synthetic mafic and ultramafic substrates and Fe>Ni sulfides. The resulting reductants included micromoles of HS- and formate accompanied possibly by micromoles of acetate and intermittent minor bursts of methane as ascertained by isotopic labeling. The formate concentrations directly correlated with the CO2 input as well as with millimoles of Mg2+ ions, whereas the acetate did not. Also, tens of micromoles of methane were drawn continuously from the reactor materials during what appeared to be the onset of serpentinization. These results support the hypothesis that formate may have been delivered directly to a branch of an emerging acetyl coenzyme-A pathway, thus obviating the need for the very first hydrogenation of CO2 to be made in a hydrothermal mound. Another feed to early metabolism could have been methane, likely mostly leached from primary CH4 present in the original Hadean crust or emanating from the mantle. That a small volume of methane was produced sporadically from the 13CO2-feed, perhaps from transient occlusions, echoes the mixed results and interpretations from other laboratories. As serpentinization and hydrothermal leaching can occur wherever an ocean convects within anhydrous olivine- and sulfide-rich crust, these results may be generalized to other wet rocky planets and moons in our solar system and beyond.

中文翻译:

使用JPL水热反应器模拟蛇毒化,因为它可能适用于生命的出现。

人们认为,通过将碳海对流与包括早期哈代海地壳在内的矿物质对流的热液相互作用,可以提供提供生命生命的分子。很少有实验室实验能够模拟古代的热液条件来证明这一推测。我们使用JPL水热流反应器研究了3天(T = 120°C,P = 100 bar,pH = 11)在模拟的古代碱性对流系统中的CO2减少量。通过合成镁铁矿和超镁铁矿基质以及Fe> Ni硫化物,以4小时为周期定期驱动富含H2的水热模拟物和富含CO2的海洋模拟物溶液。所得还原剂包括小分子的HS-和甲酸酯,可能伴随着小分子的乙酸酯和通过同位素标记确定的间歇性甲烷小脉冲。甲酸盐的浓度与CO2输入以及毫摩尔的Mg2 +离子直接相关,而乙酸盐则与之无关。同样,在似乎是蛇纹石化的开始期间,从反应器材料中连续抽出数十微摩尔甲烷。这些结果支持以下假设:甲酸盐可能已经直接传递到了新兴的乙酰辅酶A途径的一个分支上,从而避免了在热液堆中进行第一次CO2氢化的需要。早期代谢的另一种来源可能是甲烷,可能主要来自原始Hadean地壳中存在的初级CH4或地幔中散发出的CH4。从13CO2进料中偶尔会产生少量甲烷,可能是由于瞬时吸留所致,呼应其他实验室的混合结果和解释。由于在无水富含橄榄石和硫化物的硬壳中对流的任何地方都可能发生蛇纹石化和热液浸出,因此这些结果可能会推广到我们太阳系及其他地区的其他潮湿岩石行星和卫星。
更新日期:2020-03-01
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