Assessment of Natural Radioactivity in Sediments and Groundwater from Selected Areas in Funtua Town, Katsina State, Nigeria

Abstract

Natural radionuclides, particularly ²³⁸U, ²³²Th, and ⁴⁰K are the main sources of radiation exposure. Therefore, their detection is key to radiation safety measurement, among others. Therefore, this study is aimed at assessing the natural radioactivity concentrations of ²³⁸U, ²³²Th, and ⁴⁰K of 15 sediment and water samples from selected locations in Funtua town, Katsina state, Nigeria using gamma spectroscopy NaI (TI) and CR-39 Can detectors respectively.  Data obtained show that, the activity concentrations in the sediment samples were found to range between 11.50 - 61.89, 7.15 – 69.46, and 646.01 – 1368.33 Bq/kg with average activity concentrations of 37.15, 35.66, and 914.73 Bq/kg for ²³⁸U,²³²Th, and ⁴⁰K, respectively. These average values exceeded the worldwide values of 25, 25, and 370 Bq/kg respectively. In water samples, the values of 238U ranged from 0.20 to 36.78 Bq/L ( ); activity concentration values for 232Th radionuclide ranged from 2.75 Bq/L to 76.90 Bq/L ( ) and that of 40K radionuclide ranged from 42.28 Bq/L to 179.95 Bq/L ( ) respectively. These values are higher than the recommended value of 30000 g/L as reported by the EPA. The average activity concentrations of ²³⁸U,²³²Th, and ⁴⁰K were found to be higher in the sediment samples than in the water samples. The estimated total annual effective dose AED in the water sample was found to be less than the worldwide values of 0.1mSv/y or 0.2 to 0.8. The excess life cancer risk ELCR of radon in the water ranged from 0.0983×10^-4 to 1.8084×10^-4 with a mean value of 0.7949×10^-4. This value is less than the worldwide limit of 1.0×10^-4. Therefore, the groundwater (wells) in Funtua town is said to be safe based on the effects of the activity concentrations of these natural primordial radionuclides and radon on the environment. However, the need for continuous monitoring should be a priority.