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UCL Home  /  Geography  /  News & Events  /  News  /  News Archive  /  2017  /  May 2017  /  Fossil groundwater vulnerable to modern contamination

Fossil groundwater vulnerable to modern contamination

Richard Taylor’s warning on its future human use

Fossil groundwater vulnerable to modern contamination

Most of the groundwater in the world that is accessible by deep wells is fossil groundwater, stored beneath the earth's surface for more than 12,000 years.

In a study published online by Nature Geoscience on 25 April, an international team of researchers, led by Dr. Scott Jasechko (University of Calgary) and including Professor Richard Taylor (UCL Geography & UPGro GroFutures), shows that ancient water is not immune to modern contamination, as has been widely assumed.

By measuring the amount of radioactive carbon in the water, the team discovered that the majority of the earth's groundwater is derived from rain and snow that fell more than 12,000 years ago. It also accounts for between 42-85 per cent of total fresh, unfrozen water in the upper kilometre of the earth's crust.

Rain and snow that has fallen since the 1950s contains tritium, a radioactive isotope resulting from thermonuclear bomb testing. Disturbingly, traces of tritium were found in deep well waters, indicating the mixing of contaminated contemporary rain with deep fossil groundwater.

According to Richard, this discovery has important ramifications for the future human use of groundwater:

"Our results reveal not only current use of fossil groundwater but also the potential risks to water quality associated with the use of deep wells. Indeed, we need to better understand how the construction and pumping of deep wells themselves may connect fossil groundwater to the present-day water cycle.”

 

For the paper, click here.

 

See also:


Image

Artesian well in central semi-arid Tanzania (Richard Taylor)


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