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Uranium contamination found in groundwater across 16 Indian states

New Delhi : A team of US researchers has found widespread uranium contamination in groundwater from aquifers in 16 Indian states.

While the main source of uranium contamination is natural, human factors such as groundwater-table decline and nitrate pollution may also be exacerbating the problem, the Duke University-led study found.

Several studies have linked exposure to uranium in drinking water to chronic kidney disease.

“Nearly a third of all water wells we tested in one state, Rajasthan, contained uranium levels that exceed the World Health Organization and US Environmental Protection Agency’s safe drinking water standards,” said Avner Vengosh, a professor of geochemistry and water quality at Duke’s Nicholas School of the Environment.

”By analyzing previous water quality studies, we also identified aquifers contaminated with similarly high levels of uranium in 26 other districts in northwestern India and nine districts in southern or southeastern India,” he said.

The new findings are the first to demonstrate the widespread prevalence of uranium in India’s groundwater.

“The results of this study strongly suggest there is a need to revise current water-quality monitoring programs in India and re-evaluate human health risks in areas of high uranium prevalence,” Vengosh said. “Developing effective remediation technologies and preventive management practices should also be a priority.”

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 US 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.

To conduct the study, the team sampled water from 324 wells in 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.

“Our analysis showed that the occurrence of uranium in these groundwater sources depends on several factors,” said Rachel M Coyte, a PhD student in Vengosh’s lab, who was lead author of the study.

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.

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