DURHAM, N.C. – A new Duke University-led study has found widespread uranium contamination in groundwater from aquifers in 16 Indian states.
“Nearly a third of all water wells we tested in one state, Rajasthan, contained uranium levels that exceed the World Health Organization and U.S. 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.
“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 U.S. Environmental Protection Agency standards.
To conduct the study, they sampled water from 324 wells in the states of Rajasthan and Gujarat and analyzed the water chemistry.
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.
“Geochemistry and isotopic tools help us to better understand the process and conditions that control uranium occurrence in groundwater.” Human activities, especially the over-exploitation of groundwater for agricultural irrigation, may contribute to the problem, she said.
“Including a uranium standard in the Bureau of Indian Standards’ Drinking Water Specification based on uranium’s kidney-harming effects, establishing monitoring systems to identify at-risk areas, and exploring new ways to prevent or treat uranium contamination will help ensure access to safe drinking water for tens of millions in India,” he said.
CITATION: "Large-scale Uranium Contamination of Groundwater Resources in India,” Rachel M. Coyte, Ratan C. Jain, Sudhir K. Srivastava, Kailash C. Sharma, Abedalrazq Khalil, Lin Ma and Avner Vengosh; Environmental Science & Technology Letters, May 11, 2018.