High background radiation investigated by gamma spectrometry of the soil in the southwestern region of Cameroon

The aim of this work is to determine the radioactivity concentration of 226Ra, 232Th and 40K in sub-surface (0-5cm) soil samples collected from Awanda, Bikoué, Ngombas in the southwestern region of Cameroon, to assess their contribution to the external dose exposure relative to the United Nation Scientific Committee on Effects of Atomic Radiation (UNSCEAR) data. An HPGe p-type detector coupled to a multichannel analyzer was used to perform measurements and data processing. The activity concentrations of 226Ra varied from 0.06±0.01 to 0.27±0.02kBqkg-1 with a mean value of 0.13±0.01kBqkg-1 wet weight. The activity concentrations of 232Th varied from 0.10±0.01 to 0.70±0.05kBqkg-1 with a mean value of 0.39±0.03kBqkg-1 wet weight, and 40K concentrations varied from 0.37±0.02 to 1.53±0.11 kBqkg-1 with a mean value of 0.85±0.07kBqkg-1 wet weight, respectively. The mean value of outdoor annual effective doses were estimated to be 0.48mSvy-1, 0.39mSvy-1 and 0.38mSvy-1 from Ngombas, Awanda and Bikoué, respectively. The studied areas can be said to have a high background radiation level. © 2010 Elsevier Ltd.