Johannesburg - In one of the deepest mines in the world lies water that has been there so long it could one day help scientists in the search for extraterrestrial life.
An international team of scientists have discovered 1.2 billion-year-old groundwater in the Moab Khotsong gold and uranium mine near Klerksdorp, in the North West.
The water was found 2.9km below the surface and it’s the second time water that age has been found.
“Ten years ago, we discovered billion-year-old groundwater from below the Canadian Shield – this was just the beginning, it seems,” says Professor Barbara Sherwood Lollar, of the Department of Earth Sciences at the University of Toronto, Canada.
“Now, 2.9km below the Earth’s surface in Moab Khotsong, we have found that the extreme outposts of the world’s water cycle are more widespread than once thought.”
It is not that the water is a billion years old, explains Oliver Warr, research associate in the same department and lead author of the study. He says it is better to use the term “residence time”.
“It’s like you are living in your house. It’s how long you have resided in the house, rather than how old you are.”
The water usually gushes out when the miners bore into the rock; it is held in the cracks. And because of the amount of time it has spent in the rock, it is extremely salty – far saltier than the sea.
So salty that Warr admitted to not wanting to taste it when he watched it spew out of the cracks in the rock 2.9km down. Sometimes litres and litres will spill out, water that the mine doesn’t want.
“But it’s gold for us,” laughs Warr.
To age this water, scientists measure the noble gases in the water, which are produced when uranium, thorium and potassium decay.
But what is of interest are the microbes that live in the perpetual darkness 2.9km below the surface.
These are chemolithotrophic, or rock-eating, groups of co-habitating micro-organisms.
The decay of uranium, thorium and potassium also causes chemical reactions deep underground, including the production of hydrogen.
“This hydrogen can be used by small microbes underground to power themselves with an energy source completely independent from the sun,” Warr told the “Saturday Star”.
The findings were published earlier this month in the journal “Nature Communications”.
It is this kind of power source that might power microbes on other planets and moons in the solar system.
Understanding how subsurface life is sustained on Earth could in the future help in the search for new species on Mars, Titan, Enceladus and Europa.
Now that scientists know there are other such sites around the world that hold ancient water, the search is on to find them so as to better understand the past and perhaps help in the future, when humankind ventures out to other unexplored worlds.