Radiation-chemical decomposition of seawater: The appearance and accumulation of oxygen in the Earth's atmosphere

The paper addresses the role of natural radioactivity in the origin of the Earth's oxygen atmosphere. The statement is substantiated that oxygen appeared in the hydrosphere and atmosphere as a result of radiolysis of global ocean water induced by radiation of the radioactive isotopes such as 40K; 235U; 238U, and 232Th. The radiation chemical yield of oxygen is approximately 0.22 molecules/100 eV for β-particles and γ-quanta and 0.7 molecules/100 eV for α-particles. The calculations show that over the last 3.8 billion years, the total concentration of the formed oxygen is approximately 8 × 1017 kg, i.e., it corresponds, in the order of magnitude, to the current oxygen content in the atmosphere. The ocean served as the intermediate reservoir, which provided for origination of new oxygen-breathing biological living species. •Natural radioactivity initiated the formation of oxygen of Earth's atmosphere.•Oxygen is the product of radiolysis of seawater.•The oxygen accumulation upon the decay of the radioactive isotopes (40K; 235U; 238U, and 232Th) is described.