Prokaryotes stimulate mineral H2 formation for the deep biosphere and subsequent thermogenic activity

R. John Parkes, Cathal D. Linnane, Gordon Webster, Henrik Sass, Andrew J. Weightman, Ed R.C. Hornibrook, Brian Horsfield

Research output: Contribution to journalArticlepeer-review

Abstract

The deep subseafloor biosphere contains two-thirds of Earth's prokaryotic biomass, which may indicate the presence of novel mechanisms of energy generation as temperatures increase in the subsurface. In sediment slurry experiments (0-100 °C) with a range of common minerals and rocks (including basalt and quartz), there is significant H2 formation at elevated temperatures, but only in the presence of prokaryotes. This stimulates further prokaryotic activity, typical of deep sediments (sulfate reduction, acetogenesis, and CO2 production, plus continuing methanogenesis), and Bacteria and Archaea representative of many deep sediment types develop. H2 and acetate formation is particularly stimulated above 70 °C. This prokaryotic activity even enhances reactions when temperatures are raised to thermogenic levels (~125-155 °C), including hydrocarbon generation. Mechanochemistry may be important for mineral H2 formation; this is enhanced by prokaryotes (biomechanochemistry), and subsurface stress and fracturing, which is widespread on Earth.

Original languageEnglish
Pages (from-to)219-222
Number of pages4
JournalGeology
Volume39
Issue number3
DOIs
Publication statusPublished - Mar 2011
Externally publishedYes

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