Hot springs and natural radiation

The hot springs in the village Tuwa and around in Gujarat State exhibit radioactivity which is found to be due to 224Ra and 222Rn, both being daughter products of uranium. The region shows. an external gamma dose in the range of 0.4 to 2.2 mR/hr, the higher dose of 2.2 mR/hr being observed at Ramkund, the central hot spring. This is higher than the maximum permissible dose recommended for the occupational workers, hence it is not advisable to use these springs for bathing purposes and as a source of drinking water. The presence of daughter products of uranium in spring water indicates the presence of uranium deposits in the nearby region. The sediments from the hot springs and the Khari river nearby give an activity ratio of 234/238U in the range of 2.3 to 2.8, but this disequilibrium exists only on the surface labile layer, because on removal of surface organic matter and cleansing, the sediment shows an activity ratio of 1 for 234U/238U which for them is an equilibrium ratio. (author)