Geospatial assessment of radiation hazard indices in soil samples from Njaba, Imo State, South-Eastern Nigeria

Abstract

Radiation emitted from Radioactive Materials present in terrestrial environment is responsible for an estimated level of radiation exposure to both human and non-human biota. In this study, assessment of soil radioactivity level in several locations covered within Njaba, South-Eastern Nigeria has been carried out to ascertain the radioactivity concentration level of radionuclides; 238U, 232Th and 40K, in soil using Radiation Alert Inspector device and gamma-spectrometry system equipped with Sodium Iodide (NaI) detector. Due to the environmental concern arising from the human activities in this Niger Delta region, 55 soil samples were collected for analysis from; operational sites of factories, farmlands, gullies, landslides, water eroded areas and soil deposits very close to running rivers from source rocks. The result showed that the activity concentration values for 238U, 232Th and 40K has average mean values of 3.73, 1.19 and 71.23 Bq.kg−1, respectively. The mean values of the samples for radium equivalent activity, absorbed dose rate and gamma index were 10.914 Bq.kg−1, 5.432 nGyh−1 and 0.084 mSv.yr−1, respectively, with the obtained values been below United Nations Scientific Committee on the Effects of Atomic Radiation safe limit values. The results obtained from the study regions revealed that the regions are relatively safe for human outdoor activities; agriculture, building, and factory activities.

Keywords

• Primordial radionuclides
• Radiation hazard
• Gamma dose rate
• Activity concentrations
• Njaba