Tectonically-driven oxidant production in the hot biosphere.

Area of Science:

• Geochemistry
• Origin of Life Studies
• Early Earth Science

Background:

• Genomic studies suggest early life utilized hydrogen peroxide (H2O2) and oxygen (O2).
• The origin of these oxidants is debated, with lateral gene transfer being a common hypothesis.
• An alternative hypothesis involves geological sources predating oxygenic photosynthesis.

Purpose of the Study:

• To investigate a potential geological source of H2O2 and O2 on the early Earth.
• To determine the conditions under which silicate rocks release oxidants.
• To link geological oxidant production to the environmental conditions of early life.

Main Methods:

• Experimentally heating crushed silicate rocks under oxygen-free conditions with added water.
• Measuring the release of H2O2 and O2 at varying temperatures.
• Comparing experimental temperature windows with the known growth ranges of ancient microorganisms.

Main Results:

• High concentrations of H2O2 were released from crushed silicate rocks when heated near boiling point.
• Minimal H2O2 release occurred below 80°C.
• The temperature range for oxidant release aligns with the habitats of early heat-loving, oxygen-respiring life.

Conclusions:

• Geological processes, specifically the thermal activation of mineral defects, can generate H2O2 and O2.
• These geological oxidants may have been crucial for early life's biogeochemistry in hot environments.
• This provides a plausible abiotic source for oxidants supporting the origin and evolution of early life.