Interfacial water on Mars and its possible role on hydrogen peroxide decomposition

Kereszturi, Ákos and Góbi, Sándor (2014) Interfacial water on Mars and its possible role on hydrogen peroxide decomposition. In: Mars – Connecting Planetary Scientits in Europe, 5-7 June 2012, Budapest.

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Abstract

Possiblity of H2O2 decomoposition in the thin ephemeral but currently existing interfacial water on Mars was analyzed. Currently at 200 K and Phoenix lander’s wet che-mistry laboratory results, the pH is not favourable for Fe mobility that supports decomposition. But at volcanically active periods de-composition might take place at the current temperature range if solved sulphur produces pH4.5. Interfacial water probably ap-peared regularly in the Amazonian and during volcanic acivity might produce better sites for any possible biogen activity with less H2O2 there than other terrains without this liquid interfacial water. During more favourable period by rotational axis change driven climatic changes, the duration of water ice cover might be longer and salts could increase the thickness of the liquid layer. By heterogeneous catalysis, decomposition without acidic pH and mobile Fe can happen at mineral surfaces containing Fe with half life of 20 days in bulk water, and longer timescale in thin inter-facial liquid today. This might be important in the Amazonian when low temperature was present occasionally with elevated acidic con-ditions by volcanism. Under volcanically influenced acid weathering conditions [28], mobile Fe ions could decompose much H2O2, gene-rating less aggressive environment in the top regolith. Our know-ledge is limited on chemical processes in thin liquid film although such sprocess might work not only at the seasonal but also at the the permanent cap around the embedded dust grains there.

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