Although oxygen is the most abundant element in our oceans and atmosphere today, it comprises about 88.8 percent and 23.1 percent of the bulk of the two, this was not always the case. In fact, the abundance of oxygen on earth was only created 2.4 billion years ago Thanks to the advent of photosynthesis, the process by which some of the first life forms converted sunlight into energy. Scientists say that one of the products of this process was oxygen, which would completely transform the planet and create the conditions for increasingly complex life forms.
For all the importance of this so-called “Great Oxidation Event,” scientists have always wondered about the existence of oxygen on the planet before the invention of photosynthesis. Now, recent research in nature communication states that the shifting of geological faults may have produced hydrogen peroxide, an ancient source of oxygen in Earth’s early years. This source, the researchers say, may have contributed to the existence of oxygen on the planet before photosynthesis and influenced the evolution of early microbial life.
A rocky start
Although hydrogen peroxide damages microbial life at high intensities, it also provides an important source of oxygen in moderate amounts. According to recent research, when geological faults shift into scorching areas of the planet’s subsurface, they actually produce hydrogen peroxide and, as a result, oxygen. They possibly influenced the early evolution of life.
“While previous research suggests that small amounts of hydrogen peroxide and other oxidants can be formed by stressing or crushing rock in the absence of oxygen, this is the first study to show the critical importance of hot temperatures in maximizing hydrogen peroxide generation,” says Jordan Stone, a primary study author and researcher at Newcastle University, in a press release.
Investigation of oxygen in rocks
According to the researchers, the constant shifting of the earth’s crust creates cracks and fissures throughout the subsoil of tectonically active areas. The researchers say that these cracks and crevices are particularly sensitive. So when water seeps into the imperfections, it can create an important reaction.
The researchers tested these reactions with rocks found in the Earth’s early crust, including granite, basalt and peridotite. Under oxygen-free conditions at different temperatures, they crushed rock and added water to the fragments. Their simulations produced hydrogen peroxide, and therefore oxygen, at high temperatures approaching the boiling point of water.
Although these temperatures may seem inhospitable for life, they actually overlap with the ideal conditions for a microbial species called a hyperthermophilicwhich was one of the first forms of life on earth.
“This research shows that defects on gravel and minerals can behave very differently than one would expect more ‘perfect’ mineral surfaces to respond,” says Jon Telling, senior study author and professor at Newcastle University, in a press release.
“All of these mechanochemical reactions needed to produce hydrogen peroxide, and therefore oxygen, are water, crushed rock, and high temperatures, all of which were present on early Earth before the evolution of photosynthesis, transforming chemistry and microbiology into hot, seismically active ones.” Regions where life may have first evolved,” Telling said in a press release.
Ultimately, the researchers say more research is needed to fully understand the role of this process in supporting early life forms on Earth.