Abiotic redox reactions in hydrothermal mixing zones: Decreased energy availability for the subsurface biosphere

• DOI: 10.1073/pnas.2003108117
• Publication Date: 2020-08-12T23:50:12Z
• Authors: Jill M. McDermott; Sean P. Sylva; Shuhei Ono; Christopher R. Ge...; Jeffrey S. Seewald
• Keywords: Hot Temperature; 550; Hydrothermal vent; Bioenergetics; Biogeochemistry; 01 natural sciences; Hydrothermal Vents; 13. Climate action; Physical Sciences; Subsurface biosphere; Seawater; 14. Life underwater; Oxidation-Reduction; Hydrogen; 0105 earth and related environmental sciences

Significance Hydrothermal fluid geochemistry exerts a key control on subseafloor microbial community structure and function. However, the effects of metabolic activity, thermal decomposition biomass, abiotic reactions remain unconstrained. Depletions in molecular hydrogen enrichments methane submarine hydrothermal mixing zones have been interpreted to reflect influence an active biosphere. In contrast, our work reveals that these chemical shifts are driven by thermogenic processes at temperatures beyond limit for life. These findings critical implications constraining extent which global geochemical cycles can sustain deep biosphere, budget.