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

The evolution of oxygenic photosynthesis is a pivotal event in Earth’s history because the O 2 released fundamentally changed the planet’s redox state and facilitated the emergence of multicellular life. An intriguing hypothesis proposes that hydrogen peroxide (H 2 O 2 ) 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 H 2 O 2 production that involves the abrasion of quartz surfaces and the subsequent generation of surface-bound radicals that can efficiently oxidize H 2 O to H 2 O 2 and O 2 . We propose that in turbulent subaqueous environments, such as rivers, estuaries and deltas, this process could have provided a sufficient H 2 O 2 source that led to the generation of biogenic O 2 , creating an evolutionary impetus for the origin of oxygenic photosynthesis. Hydrogen peroxide (H 2 O 2 ) has been proposed as an electron donor for photosynthesis before water, however, the amount of H 2 O 2 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 H 2 O 2 .