When geologists from the University of Toronto discovered water dating back 1.5 billion years at the Kidd Mine in Ontario, Canada, in 2013, they thought they had hit the jackpot. However, digging further inside the world’s deepest base metal mine led to an even bigger discovery — water that has been locked in the earth’s crust for at least 2 billion years!
The team, led by Dr. Long Li, now an assistant professor at the University of Alberta, said the lukewarm water, discovered in May 2016, was flowing in abundance, often even splashing the researchers in their faces as they worked. The geologists were able to verify the age of the water by calculating the concentration of the various gases — helium, argon, neon, krypton, and xenon — trapped in the ancient liquid.
While discovering the world’s oldest known water is certainly exciting, what is even more so is the presence of sulfur, both in the latest sample and the one discovered in 2013. As you may know, all living organisms on Earth receive energy from chemical reactions that move electrons — electrically charged particles — from one place to another. Humans and most living creatures do it by a process called aerobic respiration, which takes the electrons derived from the food they consume and transfers them to the oxygen they breath. However, some types of bacteria have evolved to use an alternate method. They get their electrons from hydrogen gas and transfer it to sulfate, a dissolved form of sulfur. The energy released from the chain of chemical reactions is enough to sustain the microbes.
The researchers were already aware of the presence of abundant hydrogen in Canada’s ancient water. Their latest research showed that there was enough sulfate to sustain life. More importantly, Dr. Li and his colleagues found that the sulfur was produced by the mineral pyrite present in the rocks surrounding the water. When rock’s organic radioactivity split some of the water into its elements, hydrogen and oxygen, the latter dissolved with the sulfur to create the sulfate. The fact that the chemical is produced at the site, rather than coming from surface water, suggested that any microbes present are billions of years old.
To investigate the possibility of living organisms in the water, the researchers measured the quantity of sulfate and found that it was 100 to 1,000 times less than would be expected. This led Dr. Li and his team, who published their findings in the journal Nature in October 2016, to speculate that the water is harboring a tiny population of microbes that are using the sulfate for energy. The researchers are now working with a team of microbiologists to try to trace the suspected “aliens” that may have been living in the ancient water for billions of years.
Dr. Li says, “Because this is a fairly common geological setting in early Earth as well as modern Mars, we think that as long as the right minerals and water are present, likely kilometers below the surface, they can produce the necessary energy source to support the microbes.” The researcher adds, “I’m not saying that these microbes definitively exist, but the conditions are right to support microbial life on Mars.” However, the researcher does recommend looking below the surface or the Red Planet.
Alex Sessions, a professor of geobiology at the California Institute of Technology who was not involved in the study, agrees and says regardless of whether any single-celled bacteria are detected in the ancient water, the discovery that the sulfate is being generated by radioactive decay is a significant find. According to the scientist, it opens up the possibility of alien life surviving on water, sulfur, and radioactive elements on planets that do not have Earth’s hospitable environment.
In case you are wondering, according to Barbara Sherwood Lollar, a University of Toronto geochemist and the study’s senior researcher, the ancient water is “very salty and bitter.” Of course, the biggest reason to avoid taking a sip is that the liquid is “scientifically too valuable to waste like that.”
Resources: mcgill.ca, theglobeandmail.com,bbc.co.uk,nature.com