Widespread Uranium Contamination Found in India’s Groundwater

Children collecting and using water at a well in Rajasthan, India. (Image: Avner Vengosh via Duke University)

A new Duke University-led study has found widespread uranium contamination in groundwater from aquifers in 16 Indian states. The main source of the uranium contamination is natural, but human factors, such as groundwater-table decline and nitrate pollution, may be exacerbating the problem.

Several studies have linked exposure to uranium in drinking water to chronic kidney disease. Avner Vengosh, a professor of geochemistry and water quality at Duke’s Nicholas School of the Environment, said:

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The new findings are the first to demonstrate the widespread prevalence of uranium in India’s groundwater, Vengosh went on to say:

The World Health Organization has set a provisional safe drinking water standard of 30 micrograms of uranium per liter, a level that is consistent with U.S. Environmental Protection Agency standards. Despite this, uranium is not yet included in the list of contaminants monitored under the Bureau of Indian Standards’ Drinking Water Specifications.

Coyte collects water samples from a well in Rajasthan, India, for uranium contamination.
Coyte collects water samples from a well in Rajasthan, India. (Image: Avner Vengosh via Duke University)

Vengosh and his colleagues published their findings in Environmental Science & Technology Letters. To conduct the study, they sampled water from 324 wells in the states of Rajasthan and Gujarat and analyzed the water chemistry. In a subset of samples, they measured the uranium isotope ratios.

They also analyzed similar data from 68 previous studies of groundwater geochemistry in Rajasthan, Gujarat, and 14 other Indian states. Rachel M. Coyte, a Ph.D. student in Vengosh’s lab who was the lead author of the study, said:

Amount of uranium contamination depends on several factors

These factors include the amount of uranium contained in an aquifer’s rocks; water-rock interactions that cause the uranium to be extracted from those rocks; oxidation conditions that enhance the extracted uranium’s solubility in water; and the interaction of the extracted uranium with other chemicals in the groundwater, such as bicarbonate, which can further enhance its solubility. Coyte explained:

Human activities, especially the over-exploitation of groundwater for agricultural irrigation, may contribute to the problem, she said. Many of India’s aquifers are composed of clay, silt, and gravel carried down from Himalayan weathering by streams or uranium-rich granitic rocks.

When over-pumping of these aquifers’ groundwater occurs and their water levels decline, it induces oxidation conditions that, in turn, enhance uranium enrichment in the shallow groundwater that remains. Vengosh went on to say:

Provided by: Duke University [Note: Materials may be edited for content and length.]

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