Despite the extremely low oxygen levels in the early Earth's atmosphere, genomic and geochemical evidence indicates that oxygen has played a significant role in the evolutionary history of early life. Therefore, the origin of the initial oxygen on Earth is key to interpreting the evolution of Earth's habitability and life. However, where did the oxidants on early Earth come from?

The research team selected quartz (SiO₂) as a typical representative of silicate minerals and mechanically abraded it in an atmosphere simulating the Archean environment (PO₂ < 10⁻⁶ atm). They used the¹⁸O tracing method to study the production of reactive oxygen species (ROS) via radical reactions at the mineral-water interface. The results showed that the oxygen in H₂O₂ and O₂ mainly originated from mineral surface groups (peroxyl radicals), with only a small amount of ·OH coming from the dissociation of H₂O. Oxygen atoms rapidly exchanged at the triphase interface of mineral-water-atmosphere. Under mechanical force, the silicate mineral-water interface could continuously release reactive oxygen, and this effect is widely present in geological processes such as weathering and erosion, river scouring, and tectonic movements, constituting an important source of abiotic oxidants on early Earth.

This discovery overturns the traditional view that the initial oxygen on Earth originated from the decomposition of H₂O, revealing that mineral surfaces provided the initial oxygen on early Earth. The oxygen-producing mechanism of mineral-water interface reactions plays a significant role in the evolution of Earth's habitability. This abiotic oxidant is an intrinsic driving force in the co-evolution of the lithosphere, hydrosphere, atmosphere, and biosphere.

mineral, radical, oxygen, isotope exchange, early life