oxidation is a chemical process, [LEO says GER] that which Loses Electrons is Oxidized, that which Gains Electrons is Reduced.
it isnt always oxygen that does this, a difference of RedOx potential allowing redistribution of electrons is all you need.
mars has a perchlorate problem thus carbon compounds are converted to carbonate via Oxidation when encountering ubiquitous perchloate mineral deposits.
its toxic to carbon based biochemical forms, and destructive to carbon materials, such as carbon fibre; carbon nanotubes; carbon steel; even a lot of keypads.
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Pesky Perchlorates All Over Mars:
We learned it as OILRIG: oxidation is loss, reduction is gain