Physical and Chemical Diversity of Seafloor Hydrothermal Systems and Presentation of Associated Chemolithoautotrophic Ecosystem

Abstract

Deep-sea hydrothermal vents are among the habitats that host the most diverse microbial communities on the Earth. It is promised that hydrothermal vent microbial communities play a major role in the circulation of energy and materials in the global oceanic and suboceanic environments, and even provide important insights into the origin and early evolution of life on the Earth and extraterrestrial life on other planets and moons. Deep-sea hydrothermal vent ecosystems are strongly dependent on the primary production of symbiotic and free-living chemolithoautotrophic microorganisms that can obtain energy from inorganic substances such as H2S, CO2, H2, and CH4 derived from hydrothermal vent fluids. The diversity and abundance of these energy and carbon sources at hydrothermal vent fluids are, in turn, controlled by subseafloor physical and chemical processes such as fluid-rock interactions and phase-separation and-partition of fluids. Therefore, linkage between rock (magma) , hydrothermal fluid, and ecosystem is a key to understanding how deep-sea hydrothermal ecosystems are generated and sustained. In this article, we approach this whole "Rock-Fluid-Ecosystem linkage" with the two separate sub-linkages of "Rock-Fluid linkage" and "Fluid-Ecosystem linkage" , which have not been addressed by the individual research fields of the Geochemistry of Hydrothermal Systems and Hydrothermal Vent Microbiology, respectively. Here, we overview the progress of understanding the "Rock-Fluid" and "Fluid-Ecosystem" linkages, both of which will establish the basis for an integrated "Rock-Fluid-Ecosystem linkage". In seafloor hydrothermal systems, three major physical and chemical processes affect hydrothermal fluid chemistry: (1) chemical interactions between rock and hydrothermal fluid, (2) volatile inputs from magmas, and (3) phase-separation and-partition of hydrothermal fluids. The chemistry of hydrothermal fluids is primarily controlled by subseafloor fluid-rock interactions, and chemical behavior during fluid-rock interactions is constrained by phase equilibria among primary and secondary minerals in rocks. Therefore, the chemical compositions of rocks and pressure-temperature conditions of fluid-rock reactions play dominant roles in controlling fluid chemistry. Volatile inputs from magma to hydrothermal fluid are conspicuous in arc-back arc hydrothermal systems, due to the remarkable enrichment of

One-Pot Rapid Synthesis of Mo(S,Se)2 Nanosheets on Graphene for Highly Efficient Hydrogen Evolution

“…The SCF technique also has some advantages for materials synthesis, , including fast reaction rates due to the highly diffuse supply of solute under high temperatures. In addition, the reductive condition in subcritical or supercritical fluids facilitates the facile conversion from metal oxide to metal sulfide, which was previously used to develop a new chalcogenization process using scEtOH to prepare metal–chalcogenide thin films, such as CuInSe 2 and Cu 2 ZnSn­(S,Se) 4 . , In the previous report, scEtOH readily dissolved the solid feedstocks, S and SeO 2 , enabling a sufficient supply of S and Se to the metal-oxide precursor, even at low temperature. This reductive supercritical condition enabled reducing graphene oxide and fabricating a solid solution of metal–sulfide with metal–selenide only by controlling the ratio of solid chalcogen sources …”