CGWB study finds high uranium concentration in nine TN districts
The report explained that excessive abstraction reduces the volume of water available for recharge, limiting the natural process of dilution of contaminants like uranium.
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CHENNAI: The over-extraction of groundwater has resulted in higher uranium concentration in nine districts in Tamil Nadu, revealed an analysis by the Central Ground Water Board (CGWB).
As per the Annual Ground Water Quality Report - 2024, the groundwater in Cuddalore, Dindigul, Erode, Krishnagiri, Perambalur, Pudukkottai, Salem, Thoothukudi, and Virudhunagar have been contaminated with uranium with 30 ppb (parts per billion) at one or more location.
While Uttar Pradesh, Punjab, Rajasthan, and Haryana have more districts with uranium contamination due to leaching through soil by heavy use of fertilizers, the contamination in Tamil Nadu, Karnataka, and Chhattisgarh are due to natural causes of water and hard rock interaction (known as geogenic inputs).
"The analysis revealed that the majority of the samples with uranium concentrations exceeding 30 ppb cluster in regions identified as Over-exploited, Critical, and Semi-Critical groundwater stress zones. The key regions where this overlap occurs include Rajasthan, Gujarat, Haryana, Punjab, Tamil Nadu, Andhra Pradesh, and Karnataka," the report said.
The report explained that excessive abstraction reduces the volume of water available for recharge, limiting the natural process of dilution of contaminants like uranium. This lack of recharge, combined with excessive withdrawal, makes it more difficult for the aquifers to maintain lower uranium concentrations, thus exacerbating contamination.
Water with uranium concentration above the recommended maximum permissible concentration of 30 ppb is not safe for drinking purposes, as it can cause damage to internal organs, on continuous intake. Elevated uranium concentrations in drinking water have been associated with many epidemiological studies such as urinary tract cancer as well as kidney toxicity.
According to 'Dynamic Ground Water Resources of India, 2024', a majority of the over-exploited, critical, and semi-critical taluks are in west and south Tamil Nadu districts. Dindigul, Perambalur, and Salem are among the districts that extract more than 100 per cent of their extractable groundwater.
Out of 1,08,613.35 sq km recharge worthy area of Tamil Nadu, as much as 33,301.69 sq km (30.66 %) area are under 'Over-Exploited' category, 8,540.25 sq km (7.86 %) under 'Critical', 19,244.96 sq km (17.72 %) under 'Semi-critical'.
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