Study on the distribution of primordial radionuclides in soil and the effects of fertilizers and physicochemical parameters on radionuclides in the soil of tobacco-growing regions in Karnataka state, India.

The activity concentrations of primordial radionuclides Radium-226 (226Ra), Thorium-232 (232Th) and Potassium-40 (40K) in soil and fertilizer samples from tobacco-growing areas in Karnataka state were determined by Gamma-ray spectrometry using a NaI(Tl) detector. The average activity concentrations of 226Ra, 232Th and 40K in soil samples were found to be 33.44 ± 2.3, 93.79 ± 3.4 and 663.4 ± 6.2 Bq.kg-1 respectively. The physicochemical parameters of the soil were determined by standard methods and analyzed systematically in this paper. The correlation between these parameters and natural radionuclides was examined using Pearson's correlation co-efficient. The results showed that the fertilizers and physicochemical parameters affect the natural radionuclides in soil. The data related to forest soil shows slightly lesser activity of radionuclides than in the cultivated soil for the same type of rock distribution. Notably, some parameters showed positive correlation coefficients with radionuclides, while others showed negative correlations. This phenomenon is discussed in detail within the paper. It was found that physical parameters, such as sand, silt, and clay, have a significant impact on the natural radionuclides. Similarly, the effects of Potential of Hydrogen (pH), Soil Organic Carbon (SOC), Moisture Content (MC), and Electrical Conductivity (EC) on the natural radionuclides are explored thoroughly in this study. Additionally, the local geology plays a crucial role in the variation of natural radionuclide levels. The measured activity concentrations of these radionuclides found in soil, and the calculated radiological hazard indices, were assessed against internationally accepted values.