Radioactive decay
Radioactive decay of naturally occurring uranium (238U and 235U), thorium (232Th), and potassium (40K) in seafloor sediments collectively bombard the interstitial water with α, β, and γ radiation. The irradiation ionizes and breaks apart water molecules, eventually yielding H2. The products of this reaction are aqueous electrons (e−aq), hydrogen radicals (H·), protons (H+), and hydroxyl radicals (OH·). The radicals are highly reactive, therefore short-lived, and recombine to produce hydrogen peroxide (H2 O2), and molecular hydrogen (H2).