Scientists Surprised by Alien Life in Ancient Canadian Water

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#Canadian #AlienScientists Surprised by Alien Life in Ancient Canadian Water : Scientists have found evidence that the oldest water in the world, which is deep below ground in northern Ontario, could have microbial life that is “alien” to life on the surface.

“Microbial subsurface communities are often chemosynthetic, not photosynthetic,” says University Professor Barbara Sherwood Lollar in the department of earth sciences at the Faculty of Arts & Science.

“In chemosynthesis, a molecule like hydrogen ‘donates’ electrons, and sulfate ‘accepts’ them. Basically, all metabolism works through this kind of exchange of electrons.

That’s how energy works. That’s how life works.” The chemical reactions producing the electron donor in these deep waters had been identified several years ago, but the source of sulfate – the electron acceptor – had been elusive.

In a paper published this week in Nature Communications, Sherwood Lollar and her colleagues report that sulfate dissolved in these waters 2.4 km below the surface comes from oxidation of the sulfide minerals in the ancient rocks via chemicals produced when radiation breaks the water down into its constituent parts.

First author Long Li, now the Canada Research Chair in stable isotope geochemistry at the University of Alberta, worked with Sherwood Lollar at U of T as a postdoctoral fellow.

Along with researchers from McGill University, they studied the distribution pattern of multiple sulfur isotopes – that is, sulfur atoms that differ by the number of neutrons – in the dissolved sulfate in ancient subterranean waters near Timmins, Ont.

Their earlier work had revealed that these waters contain hydrogen and sulfate – key components that make life possible without sunlight. The multiple sulfur isotope compositions in the sulfate show a unique pattern, only seen in rocks formed before oxygen appeared in Earth’s atmosphere about 2.4 billion years ago.

By matching this isotopic feature in the dissolved sulfate with that of pyrite in the 2.7-billion-year-old rocks hosting the waters, the researchers demonstrated that the same pyrite and other sulfide ores that make these rocks ideal for economic mining of metals, produce the “fuel” for microbial metabolisms.

But there were other surprises in store. “When we looked at the sulfate dissolved in these waters, we found it was more enriched in an isotope called sulphur 34 than expected,” Sherwood Lollar says.