Risk Assessment by Estimating Radio-Ecological Half-Life of Radionuclides Present in Soil Samples of Kovalam Beach, Kerala

Natural radioactivity is distributed throughout the earth's geological formations. Southern coastal parts of India are considered high-radiation background areas due to the presence of monazite sand, an ore of thorium. In the present study, the radioecological half-life of radionuclides present in soil samples of Kovalam beach, Kerala, was determined, which could be utilized to understand the possible long-term potential health impacts in individuals (such as radiation sickness, risk of cancer, and genetic effects) as well as the ecosystem. The gamma ray spectrum of the soil sample indicates the presence of naturally occurring radionuclides such as 214Pb (Eγ: 295.2 keV), 212Pb (Eγ: 238 keV), 228Ac (Eγ: 338.2 keV, 911 keV), 212Bi (Eγ: 727 keV), 214Bi (Eγ: 351.9 keV, 609.3 keV, 1760 keV), and 208Tl (Eγ: 583.2 keV, 2614 keV). Ecological half-life (Teco) of 232Th, 238U, and radionuclides from their decay series such as 228Ac, 212Bi, 214Bi, 212Pb, and 208Tl were calculated using measured radioactivity of these radioisotopes. The ecological half-life of 40K, 238U, and 232Th was estimated, and the results are found to be 1730 ± 87 yr, 175 ± 9 yr, and 170 ± 8 yr, respectively. The long ecological half-life of 40K, 238U, and 232Th indicates the presence of these isotopes in the environment for extended periods of time due to their slow ecological removal processes. This could imply several potential risks in terms of long-term radiation exposures, environmental contamination, and bioaccumulation.