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India is one of the countries in the world having vast reserves of heavy minerals, especially thorium bearing minerals. Beach sands of the coastal territories of Kerala and Tamil Nadu in India are very rich in monazite containing 8–10.5% of thorium (as ThO2), 0.2–0.4% of uranium (as U3O8) and K-40, hence the water body can be contaminated by the leaching of radionuclides. In the present investigation, we have made an attempt to study the extent of leaching of surface soil-borne Thorium and Potassium into water in various pH conditions. To study the effect of pH on leaching, soil samples collected were allowed to remain in contact with acidified and alkaline water samples. From the measured concentrations of radionuclides in soil and water samples, the leaching efficiency of 232Th and 40K for most of the samples was calculated to be 20 and > 40%, respectively. It has been found that the degree of acidity or a lower pH largely influenced the migration/leaching of 232Th from soil/sand to water than the alkalinity of water. On the other hand, a reverse phenomenon, i.e., the degree of alkalinity show a greater influence on the leaching of 40K from soil to water samples compared to the degree of acidity. Overall, a weak but positive correlation was observed between the concentration of 232Th and 40K in the soil samples and the corresponding concentration in the water samples indicating the possible leaching of radionuclides from the soil to water under favorable conditions. Measured data on the leachability of radionuclides can be used for any future study on safety of human health due to the contamination of waterbodies. |
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