New Delhi: Scientists from Duke University have found widespread uranium contamination in groundwater from aquifers across 16 states in India, much above the WHO provisional standard for the country. The findings published in the journal Environmental Science & Technology Letters are the first to demonstrate the predominant prevalence of uranium in India’s groundwater.
The findings published in the journal Environmental Science & Technology Letters are the first to demonstrate the predominant prevalence of uranium in India’s groundwater. The researchers from Duke University in the US unveiled new data showing that the occurrence of uranium in Indian groundwater — a primary source of drinking water and irrigation — is an emerging and widespread phenomenon.
Uranium found in groundwater
The research team had gathered the data from 324 wells in the states of Rajasthan and Gujarat, as well as 68 previous studies on groundwater geochemistry in the same areas. Uranium is often found naturally in rocks, which, under varying environmental conditions, allows it to more easily seep into surrounding water. Much of the gravel, clay and silt that are found in India’s aquifers were brought there through the weathering of the Himalayan mountains, the rocks of which contain high levels of uranium. As India’s aquifers are over-harvested to support agricultural industry, oxidation of these rocks enable uranium to escape and contaminate its surrounding environment.
WHO standards of safe drinking water
They compiled data on groundwater uranium from 16 Indian states and new data from 324 wells in Rajasthan and Gujarat that shows a high prevalence of uranium concentrations above the World Health Organization (WHO) provisional guideline value across India. The WHO has set a provisional safe drinking water standard of 30 microgrammes of uranium per litre for India, 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, researchers 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.
While much of the uranium contamination is natural in its origin, groundwater-table decline and nitrate pollution from agriculture also contribute to the widespread public health problem; high levels of uranium in drinking water have been linked to chronic kidney disease.