Scientists at the University of Newcastle have discovered a source of oxygen that may have influenced the evolution of life before the advent of photosynthesis.
The groundbreaking research project, led by Newcastle University’s School of Natural and Environmental Sciences and published today in Nature Communication, discovered a mechanism that can generate hydrogen peroxide from rocks during the movement of geological faults.
While hydrogen peroxide in high concentrations can be harmful to life, it can also be a useful source of oxygen for microbes. This supplemental oxygen source may have influenced the early evolution, and possibly even the origin, of life in warm environments on early Earth prior to the evolution of photosynthesis.
In tectonically active regions, the movement of the Earth’s crust not only triggers earthquakes, but riddles the subsurface with fissures and fractures lined with highly reactive rock surfaces that contain many imperfections or defects. Water can then filter down and react with these defects on the freshly broken rock.
In the lab, master’s student Jordan Stone simulated these conditions by crushing granite, basalt and peridotite – rocks that would have been present in the Earth’s early crust. These were then added to water under well-controlled oxygen-free conditions at varying temperatures.
The experiments showed that significant amounts of hydrogen peroxide — and, as a result, possibly oxygen — were generated only at temperatures close to the boiling point of water. Importantly, the temperature of hydrogen peroxide formation overlaps the growth range of some of the most heat-loving microbes on Earth, called hyperthermophiles, including evolutionary ancient oxygen-consuming microbes near the root of the universal tree of life.
Lead author Jordan Stone, who conducted this research as part of his MRes in Environmental Geoscience, said: “While previous research has suggested that small amounts of hydrogen peroxide and other oxidants can be formed by straining or crushing rocks in the absence of oxygen, this is the first study demonstrating the vital importance of high temperatures in maximizing hydrogen peroxide formation.”
Principal investigator Dr. Jon Telling, senior lecturer, added: “This research shows that crushed stone and mineral defects can behave very differently than you would expect more ‘perfect’ mineral surfaces to react. All of these mechanochemical reactions have to generate hydrogen peroxide, and thus oxygen is water, rock chips and high temperatures, all of which were present on early Earth before the evolution of photosynthesis and which could have influenced chemistry and microbiology in hot, seismically active regions where life may have first evolved.”
The work was supported by grants from the Natural Environmental Research Council (NERC) and the UK Space Agency. An important new sequel project led by dr. Jon Telling, funded by NERC, is underway to determine the significance of this mechanism for sustaining life in the Earth’s subsurface.
Weathering rocks hold clues to Earth’s major oxidation event
Tectonic-driven oxidant production in the hot biosphere, nature communication (2022). DOI: 10.1038/s41467-022-32129-y
Provided by the University of Newcastle
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