Environment

Ancient underground water sources not immune to today’s pollution

New research suggests ancient underground water sources long believed to be shielded from modern-day contaminants may not be as safe as previously thought.

The study, led by University of Calgary hydrogeologist Scott Jasechko, involved delving into data collected from 6,000 groundwater wells around the world.

The research yielded two interesting findings – up to 85 per cent of the fresh, unfrozen water in the upper kilometre of the earth’s crust is more than 12,000 years old and it’s possible for ancient and recent water sources to mingle deep underground.

The implication of that finding is that, unfortunately, even deep wells are vulnerable to modern land uses.

The tests released a specific radioactive hydrogen isotope into the environment called tritium, which has been useful in dating water samples. Trace levels of tritium – too low to pose any danger – were found in deep groundwater wells, demonstrating there is a way for old and new water to mix.

“Its presence alone indicates that some of the water in the well is recent rain and snow,” said Jasechko. “And the fact that we find that at deep depths implies that even deep wells are vulnerable to modern-era contaminants.”