Astrobiology Science and Technology for Exploring Planets (ASTEP)

Seminar Detail

Simulating groundwater radiolysis with oxidation of pyrite by hydrogen peroxide solution

Presenter: Liliana Lefticariu

August 8, 2005 01:00 PM Pacific

Radiolytic dissociation of water produces oxidizing (e.g., H₂O₂, OH·, and
O₂) and reducing (e.g., H atoms and H₂) species. In natural environments,
radiolytically generated oxidants can react with sulfide minerals (e.g.,
pyrite) and can provide local sources of partially to fully oxidized sulfur
species suitable for microbial metabolism.



In this study, we investigate the reaction of pyrite with millimolar
solutions of H₂O₂ at temperatures from 4 to 150ºC. Results show that
radiolytically produced oxidants could efficiently oxidize pyrite in an
otherwise oxygen-limited environment. The rate of pyrite oxidation increases
with increasing peroxide concentration, pyrite surface area, and
temperature.



In natural groundwater environments where radiolysis occurs, coupled abiotic
and biotic reactions could complicate the products of radiation-induced
chemical reactions. Radiolytic pyrite oxidation can buffer oxygen
production, maintain anaerobic conditions, and supply partially to fully
oxidized sulfur species for microbial reduction or disproportionation.

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