Some Compositional and Kinetic Controls on the Bioenergetic Landscapes in Oceanic Basement.
Some Compositional and Kinetic Controls on the Bioenergetic Landscapes in Oceanic Basement.
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DOI：
10.3389/fmicb.2016.00107
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发表时间：
2016
影响因子：
5.2
通讯作者：
Bach W
中科院分区：
文献类型：
--
作者：
Bach W
这一贡献评估了大洋中脊侧翼水岩反应期间微生物生命的分解代谢能量的可用性，在那里玄武岩和超镁铁岩与循环海水相互作用。除了平衡热力学计算，动力学反应路径的结果。在这些计算中，假设橄榄石和玄武岩玻璃的溶解分别控制超镁铁质和玄武质岩石中氢生成反应的速率。结果表明，所有的洋壳基底岩石释放足够的氢（H2，aq），以支持氢营养生命在低水岩比。橄榄石溶解速率控制施加更强的影响，比相平衡控制的氢生产，表明磁铁矿的形成是不需要生产大量的氢在超镁铁岩。形成的non-tronite和绿松石是主要负责形成的中等数量的氢（H2，水）预期在玄武岩脊侧翼。然而，在大的海水通量的条件下，需要考虑到巨大的全球对流热流脊侧翼，玄武岩脊侧翼的氢生产是不足以支持氢营养生命。因此，建议的作用，铁氧化玄武岩脊侧翼大于以前建议。玄武岩脊侧翼的铁氧化物可能支持2.4 × 1028个细胞的现存量，相当于沉积深层生物圈的约10%。海洋地壳内氢营养生物量的大小更难以估计，因为氢释放的速率和过程没有得到充分的限制。在任何情况下，海洋地壳中的氢营养作用应该是非常重要的，只有在富含橄榄石的基底岩石和沉积的山脊侧翼与低时间综合海水通量。
This contribution assesses the availability of catabolic energy for microbial life during water–rock reactions in the flanks of mid-ocean ridges, where basaltic and ultramafic rocks interact with circulating seawater. In addition to equilibrium thermodynamic computations, results for kinetic reaction paths are presented. In these calculations, it is assumed that dissolution of olivine and basalt glass control the rates of hydrogen forming reactions in ultramafic and basaltic rocks, respectively. The results suggest that all ocean crust basement rocks release enough hydrogen (H2,aq) to support hydrogenotrophic life at low water-to-rock ratios. Olivine dissolution rate control imposes a stronger effect on hydrogen production than phase equilibrium controls, indicating that magnetite formation is not a requirement for production of large amounts of hydrogen in ultramafic rocks. The formation of non-tronite and celadonite are primarily responsible for the formation of the moderate amounts of hydrogen (H2,aq) expected in basaltic ridge flanks. Under conditions of large seawater fluxes required to account for the great global convective heat flow in ridge flanks, however, hydrogen production in basaltic ridge flanks is insufficient for supporting hydrogenotrophic life. It is hence proposed that the role of Fe oxidation in basaltic ridge flanks is greater than previously suggested. A standing stock of 2.4∗1028 cells may be supported by Fe oxidation in basaltic ridge flanks, equivalent of about 10% of the sedimentary deep biosphere. The size of a hydrogenotrophic biomass within the ocean crust is more difficult to estimate because the rates and processes of hydrogen release are insufficiently constrained. In any case, hydrogenotrophy in the ocean crust should be of key importance only in olivine-rich basement rocks and in sedimented ridge flanks with low time-integrated seawater fluxes.