An abiotic source of Archean hydrogen peroxide and oxygen that pre-dates oxygenic photosynthesis

Abstract

The evolution of oxygenic photosynthesis is a pivotal event in Earth’s history because the O₂ released fundamentally changed the planet’s redox state and facilitated the emergence of multicellular life. An intriguing hypothesis proposes that hydrogen peroxide (H₂O₂) once acted as the electron donor prior to the evolution of oxygenic photosynthesis, but its abundance during the Archean would have been limited. Here, we report a previously unrecognized abiotic pathway for Archean H₂O₂ production that involves the abrasion of quartz surfaces and the subsequent generation of surface-bound radicals that can efficiently oxidize H₂O to H₂O₂ and O₂. We propose that in turbulent subaqueous environments, such as rivers, estuaries and deltas, this process could have provided a sufficient H₂O₂ source that led to the generation of biogenic O₂, creating an evolutionary impetus for the origin of oxygenic photosynthesis.

Hydrogen peroxide (H₂O₂) has been proposed as an electron donor for photosynthesis before water, however, the amount of H₂O₂ available on early Earth was thought to be limited. Here the authors propose a new abiotic pathway wherein abrasion of quartz surfaces would have provided enough H₂O₂.