Widespread uranium contamination found in India's groundwater

Widespread uranium contamination found in India's groundwater
Children collecting and using water at a well in Rajasthan, India. Credit: Avner Vengosh, Duke Univ.

A new Duke University-led study has found widespread uranium contamination in groundwater from aquifers in 16 Indian states.

The main source of the contamination is natural, but human factors such as -table decline and nitrate pollution may be exacerbating the problem.

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

"Nearly a third of all 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.

"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 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.

Vengosh and his colleagues published their peer-reviewed study May 11 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.

"Our analysis showed that the occurrence of uranium in these groundwater sources depends on several factors," said Rachel M. Coyte, a Ph.D. 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.

"In many parts of India, these factors co-occur and result in high uranium concentrations in the groundwater," Coyte explained. "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. 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 in the shallow groundwater that remains.

"One of the takeaways of this study is that human activities can make a bad situation worse, but we could also make it better," Vengosh 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 will help ensure access to safe drinking water for tens of millions in India," he said.

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More information: Rachel M. Coyte et al, Large-Scale Uranium Contamination of Groundwater Resources in India, Environmental Science & Technology Letters (2018). DOI: 10.1021/acs.estlett.8b00215
Provided by Duke University
Citation: Widespread uranium contamination found in India's groundwater (2018, June 7) retrieved 20 August 2019 from https://phys.org/news/2018-06-widespread-uranium-contamination-india-groundwater.html
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User comments

Jun 07, 2018
As weird as this sounds, it is actually not all that unusual. Well water often does contain some rather "interesting" natural toxins like Arsenic, Radium, Barium, Beryllium, etc.

Jun 08, 2018
Well, a purifier capable of removing it costs about $12,000 and is suitable for producing water for maybe five people per day. Who is going to pay for them? Yeah, who else, the West...As the other poster stated, normal non-filtered water contains all kinds of metals and minerals. All over the world. Water the world over that comes open sources contains Strontium 90 from bomb tests.

Jun 08, 2018
Just as long as it's not deadly Depleted Uranium...

Jun 08, 2018
RO units aren't that expensive

Jun 08, 2018
Water falling as rain on and passing through karst topology will be low in heavy metals. If all groundwater everywhere was the same as implied by TB, then there would be no need to test it. Oh look, they're testing water.

Jun 11, 2018
If they are so concerned about radiation, why did they allow R12 houses to be built, with no circulation to the outside, resulting in vastly increased exposure to radon gas, which is the third highest cause of lung cancer, outside of smoking and genetics. Enviro-hypocrites is a better term for them.

Jun 15, 2018
Apparently the immediate consequences of freezing to death or going bankrupt paying money to the power company are more important then the far off and small possibility of developing radon-induced lung cancer. But seriously, R12 isn't much insulation, and insulation is designed to block radiation, not air movement. Perhaps you should be more concerned about other parts of the building envelope such as vapor barriers. You really don't know much about anything, do you.

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