Microbes living under the seabed largely feed on the products of radioactive decay, aided by seabed sediments, a new study finds. This discovery radically changes the way we look at the processes of life in one of the largest ecosystems on our planet. It could also change our view of how life may have evolved on Mars or other alien worlds.
Generally, it was believed that organic matter was the primary source of energy for microbes living far under the oceans. However, most organic material is consumed on the seabed, or just below. The researchers were able to determine that radiolysis (the breakdown of water by radiation) is the main source of energy for these aquatic beings in sediments over a few million years old.
“This work offers an important new perspective on the availability of resources that underground microbial communities can use to sustain themselves. It is fundamental to understand life on Earth and to limit the habitability of other planetary bodies, such as Mars ”, explains Justine Sauvage, postdoctoral fellow at the University of Gothenburg who conducted the research as a doctoral student at the University of Rhode Island (URI).
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Your name is mud. Don’t worry it’s a good thing
“Welcome to the new era, to the new era
Whoa-oh-oh-oh, oh … Whoa-oh-oh-oh
I’m radioactive, radioactive“- Radioactive, Imagine Dragons
Water molecules, as most people know, are made up of two atoms of hydrogen and one of oxygen. Nature, like college science students, can break the water molecules in their components. They can also be broken down by natural radiation, in a process called radiolysis, providing a source of energy for microbes.
This new study shows that sediment on the seabed can increase the production of hydrogen and oxidants up to 30 times over typical production in pure water.
“Marine sediments actually amplify the production of these usable chemicals. If you have the same amount of irradiation in pure water and in wet sediment, you get a lot more hydrogen from wet sediment. Sediments make hydrogen production much more efficient, ”explains Steven D’Hondt, professor of oceanography at the URL.
Why marine sediments have this effect on radiolysis remains a question. However, D’Hondt hypothesizes that the minerals contained in the sediments can behave like a semiconductor, thus increasing the production of the products of this molecular degradation.
Waterworld is not as bad as you remember it
“Radiolytic H2 has been identified as the main electron donor (food) for microorganisms in continental aquifers miles below the Earth’s surface. Radiolytic products may also be important in sustaining life in undersea sediments and underground environments on other planets, ”the researchers describe in an article detailing the study, published in Nature communications.
Our solar system – and our galaxy – is teeming with aquatic worlds. This process could also take place on other planets and moons, providing a vital reserve of energy for alien microbes, the researchers suggest.
The Perseverance rover which recently landed on Mars, its main mission is to collect samples on Mars to be returned by future missions. Once on Earth, these samples will be intensely studied by researchers around the world.
“Some of the same minerals are present on Mars, and as long as you have these wet catalytic minerals, you’re going to have this process. If you can catalyze the production of radiolytic chemicals at high rates in humid Martian subsoil, you could potentially maintain life at the same levels as in marine sediments, ”D’Hondt said.
In the video above, watch our interview with Steven D’Hondt about his work on finding a 100 million years old colony of marine organisms. (Video credit: The Cosmic Companion)
Europe – one of Jupiter’s largest moons contains much more water than Earth, which makes this Jovian moon an exciting step to study how radiolysis could feed alien microbes on this alien world.
This finding could also have implications for the storage of nuclear waste, and nuclear accidents are addressed. Nuclear waste stored in rock or sediment could generate hydrogen and oxidants at a significantly higher rate than the same deposits in pure water. These environments would be much more corrosive on storage systems than previously believed.
The team will continue to study how this process might behave on other planets, including March. A closer look at microbes will help the team better understand how microbes survive and behave when they live off the products of the radioactive division of water.