Natural background radiation and dose rates measurements in surface soils in Côte d’Ivoire

 

A. A. Koua1*, M. A. Kouacou2, D. K. Konan2, M. C. Kouassi1, B. Koffi2, P. A. Dali1, G. Ardisson3

1Laboratoire de Physique Nucléaire et Radioprotection, UFR Sciences des Structures de la Matière et de la Technologie,

Université de Cocody, 22 BP 582 Abidjan 22, Côte d’Ivoire.

2Département Génie Electrique et Electronique, Institut National Polytechnique Houphouët Boigny,

B.P 1083 Yamoussoukro, Côte d’Ivoire.

3Laboratoire de Radiochimie, Sciences Analytiques et Environnement,

Université de Nice Sophia-Antipolis 06108 Nice Cedex France

* Corresponding author. E-mail: antoninkoua@yahoo.fr

Received: 24 December 2007; revised version accepted: 05 June 2008

 

Abstract

     The activity concentrations and the radiological effects of the terrestrial background gamma radiation from surface soil samples of an undisturbed forest, South-eastern, Côte d’Ivoire, were investigated using a high-resolution HPGe gamma-ray spectrometry.

     The average concentration activities were measured to be 7.5 ± 1.2 Bq kg-1 for 226Ra, 14.7 ± 3.0 Bq kg-1 for 232Th and 47.5 ± 9.0 Bq kg-1 for 40K in the forest area. In soil samples from the clearing site, 226Ra and 232Th average concentration values were found to be respectively 7.6 ± 1.2 Bq kg-1 and 14.3 ± 3.0 Bq kg-1 while 40K was undetectable. The average values of the radiological impacts due to these radionuclides were derived from Radium equivalent activity (range from 28 to 32 Bq kg-1), Absorbed dose rate in air (range from 12 to 15 nGy h-1) and the Annual effective dose outdoors (range from 0.016 to 0.018 mSv y-1). These values are far smaller than the worldwide average values 55 nGy h-1 for the Absorbed dose rate, 0.07 mSv y-1 for the Annual effective dose and 370 Bq kg-1 the maximum limit for building materials for Radium equivalent activity.

 

Keywords: Natural gamma radiation; g-ray spectroscopy; surface soil; annual effective dose.

 

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