High Uranium Concentration in Groundwater Used for Drinking in Parts of Eastern Karnataka, India

The limits recommended by World Health Organization (WHO) and the Atomic Energy Regulatory Board (AERB) of India for uranium concentration in drinking water are 30 μg/l and 60 μg/l respectively. The present study on uranium concentration in groundwater used for drinking purposes in 73 villages of Karnataka, India, shows that in 57 villages uranium concentration is more than 30 μg/l, including 48 villages where it exceeds 60 μg/l. Thus in 78% and 66% of the villages studied, uranium concentration exceeds permissible limits given by WHO and AERB respectively. It is alarming to note that in one village each in Tumkur and Chitradurga districts, five in Kolar and seven in Chikkaballapura districts, uranium concentration is in thousands of micrograms per litre. None of the borewells from which water has been sampled is anywhere in the vicinity of nuclear facilities or urban waste disposal channels. Thus, the observed uranium contamination is considered to be geogenic. Previous geological studies have shown that the eastern portion of Karnataka is a part of the Neoarchean Eastern Dharwar Craton dominated by large ion lithophile element-rich K-feldspar granites and gneisses with higher abundance of radioactive elements (uranium and thorium) compared to the Mesoarchean tonalite–trondhjemite–gneisses and granitoids widely distributed in the Western Dharwar Craton.