Simulating serpentinization as it could apply to the emergence of life using the JPL hydrothermal reactor
Simulating serpentinization as it could apply to the emergence of life using the JPL hydrothermal reactor
复制标题
使用 JPL 水热反应堆模拟蛇纹石化，因为它可以应用于生命的出现
DOI：
10.1089/ast.2018.1949
复制
发表时间：
2020
期刊：
影响因子：
4.2
通讯作者：
M.J.
中科院分区：
文献类型：
--
作者：
White;L.M.;Shibuya;T.;Vance;S.D.;Christensen;L.E.;Bhartia;R.;Kid;R.;Hoffmann;A.;Stucky;G.D.;Kanik;I. and Russell;M.J.
供给生命出现的分子被认为是通过对流的含碳海洋沃茨与构成早期冥古宙海洋地壳的矿物的热液相互作用提供的。很少有实验室实验模拟古代热液条件来验证这一猜想。我们使用JPL热液流反应器研究了模拟古碱性对流系统中3天内的CO2还原（T = 120°C，P= 100 bar，pH = 11）。富H2的热液模拟物和富CO2的海洋模拟溶液被周期性地驱动通过合成的镁铁和超镁铁基底和Fe>Ni硫化物在4小时的循环。由此产生的还原剂包括微摩尔的HS-和甲酸盐，可能伴随着微摩尔的乙酸盐和间歇性的甲烷小爆发，这是通过同位素标记确定的。甲酸盐浓度直接与CO2输入以及与毫摩尔的Mg 2+离子，而乙酸盐没有。此外，数十微摩尔的甲烷被连续从反应堆材料在什么似乎是开始的蛇纹石化。这些结果支持的假设，甲酸可能已被直接交付到一个新兴的乙酰辅酶-A途径的分支，从而避免了需要的第一个氢化的CO2在水热丘。早期代谢的另一个饲料可能是甲烷，可能主要是从原始冥古宙地壳中存在的初级CH 4中沥滤出来的，或者来自地幔。少量的甲烷是从13 CO2供给中零星产生的，也许是从短暂的闭塞中产生的，这与其他实验室的混合结果和解释相呼应。由于蛇纹石化和热液浸出可以发生在任何海洋对流的无水橄榄石和硫化物丰富的地壳，这些结果可以推广到其他潮湿的岩石行星和卫星在我们的太阳系和超越。
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 CO2reduction 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 CO2input 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 CO2to be made in a hydrothermal mound. Another feed to early metabolism could have been methane, likely mostly leached from primary CH4present in the original Hadean crust or emanating from the mantle. That a small volume of methane was produced sporadically from the13CO2-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.