Contemporary pollutants can reach deep wells that tap fossil aquifers, says a study by an international team of researchers.
More than half of some 6,000 wells studied around the world by the researchers showed traces of tritium, a radioactive isotope of hydrogen that has been marking water since 1953 when nuclear weapons testing became widespread. As tritium released by nuclear tests shows up in rainfall, it has become a handy tool in studying hydrological cycle.
The discovery of tritium traces in deep fossil aquifers, which were originally recharged by precipitation more than 12,000 years ago, is being attributed by the researchers to contamination by ‘younger’ groundwater closer to the earth’s surface.
“In the vast majority of wells we examined, tritium does not exist at levels high enough to present a human health risk,” clarifies Scott Jasechko, assistant professor, department of geography, University of Calgary, Canada and lead author of the study published on 25 April in Nature Geoscience.
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