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Quantification of Hydrogen Concentrations in Surface and Interface Layers and Bulk Materials through Depth Profiling with Nuclear Reaction Analysis
Published on: March 29, 2016
Biogeochemistry of dihydrogen (H2)
1Exobiology Branch, NASA Ames Research Center, Moffett Field, California 94035-1000, USA. tori.m.hoehler@nasa.gov
Metal Ions in Biological Systems
|December 24, 2005
Summary
Early Earth had much higher hydrogen (H2) levels, influencing geochemistry and the origin of life. Modern microbial communities still rely on H2, with potential for future clean energy applications.
Area of Science:
- Geochemistry
- Biogeochemistry
- Astrobiology
Background:
- Hydrogen (H2) has played a crucial and evolving role in Earth's geo- and biogeochemistry since prebiotic times.
- Early Earth likely had stronger abiotic H2 sources due to higher volcanic out-gassing and hydrothermal circulation.
- Elevated prebiotic atmospheric H2 levels (3-4 orders of magnitude higher than present) impacted atmospheric redox, radiation, haze production, and biochemical precursor synthesis.
Purpose of the Study:
- To explore the historical and ongoing significance of hydrogen (H2) in Earth's geo- and biogeochemistry.
- To understand H2's role in the origin of life and early metabolic chemistry.
- To assess H2's function in modern microbial communities and its potential for future energy applications.
Main Methods:
- Review of geological and geochemical evidence for early Earth conditions.
- Analysis of the role of abiotic H2 production mechanisms (volcanism, serpentinization).
- Examination of H2's influence on prebiotic chemistry and the origin of metabolism.
- Assessment of H2's function in modern microbial ecosystems and biogeochemical cycles.
- Consideration of H2's potential as a future clean energy source.
Main Results:
- Abiotic H2 production was significantly higher on early Earth, influencing atmospheric composition and prebiotic chemistry.
- H2 likely played a critical role in the origin of life, serving as an energy source and redox agent for early metabolism.
- Modern microbial communities, including phototrophs, extensively utilize H2, linking metabolic activities and controlling biogeochemical cycles.
- H2 remains vital in global biogeochemistry, particularly in anoxic environments like sediments and digestive tracts.
- The potential for large-scale H2 utilization as a clean energy source is being explored, with possible significant biogeochemical consequences.
Conclusions:
- The early abiotic cycling of H2 established the environmental and chemical context for life's origins.
- H2 was likely fundamental to early metabolic pathways and the development of chemosynthetic ecosystems.
- Microbial H2 utilization continues to be a cornerstone of global biogeochemistry and has potential for future energy solutions.
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