Impact of soil physicochemical properties on the transfer of natural radionuclides from soil to Cassava in Parts of Akwa Ibom State, Nigeria

The transfer of natural radionuclides from soil to cassava is essential in studying the influence of soil properties on the movement of elements. This study investigated the impact of soil physicochemical properties on the soil-to-plant transfer of ²³⁸U, ²³²Th, and ⁴⁰K from agricultural soils to cassava tubers across three Local Government Areas (LGAs): Uyo, Ibiono Ibom, and Itu, in Akwa Ibom State, Nigeria. A total of 12 paired soil and cassava samples were collected and prepared according to standard protocols. Activity concentrations of the radionuclides were measured using a NaI(Tl) gamma-ray spectrometer at the Centre for Energy Research and Development, Obafemi Awolowo University, Ile-Ife, Nigeria. Soil physicochemical parameters were determined using established laboratory methods. Mean transfer factor (TF) values for ²³⁸U, ²³²Th, and ⁴⁰K ranged from 0.73–1.04, 0.57–1.11, and 1.33–1.51 respectively across the three LGAs, revealing pronounced radionuclide-specific and spatial variability in transfer efficiency. Pearson correlation analysis revealed statistically significant relationships between soil physicochemical parameters and transfer factors. Clay content showed a strong positive correlation with ²³⁸U (r = 0.995, p < 0.05), while soil organic matter was strongly negatively correlated with TF_th(²³²Th) (r = −1.000, p < 0.05). The TF_k(⁴⁰K) exhibited a significant positive correlation with exchangeable Ca (r = 0.998, p < 0.05) and Na (r = 0.999, p < 0.05). The predominantly sandy, acidic soils of the study area facilitated moderate to high radionuclide mobility. These findings contribute essential baseline radiological and pedological data for cassava-growing communities in Akwa Ibom State.