Although it has been assumed that “fossil” reserves of groundwater found hundreds of metres underground would be largely untouched by modern water sources, the world’s oldest and deepest waters are not immune from contamination. A new isotope study of sampling from some 10,000 wells shows this not to be the case, showing that about half of the deep groundwater has had contact with rains and snows that fell in the past 60 years.
And that means the aquifers are also at some risk from pollution if waste disposal and land management practices are defective. It is an issue of significance because fossil waters are an important resource, providing drinking supplies and irrigation for millions of people across the globe.
The results were presented at the recent EGU meeting in Vienna and have been published in the journal Nature Geoscience.
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