Vol. 10, No 1, 2013 pp. 53 - 60
UDC 631.438(662.6)
NATURAL OCCURRING RADIONUCLIDE VARIATION WITH A SOIL DEPTH PROFILE OF UDI AND EZEAGU LOCAL GOVERNMENT AREAS OF ENUGU STATE, NIGERIA
G.O. Avwiri1, J.C. Osimobi1, E.O. Agbalagba2
1Department of Physics, University of Port Harcourt, Nigeria
2Department of Physics, Federal University of Petroleum Resources, Effurun, Nigeria
E-mail: goavwiri@yahoo.com
Abstract. The assessment of the natural radionuclide concentration with a depth profile of two drilled boreholes in Enugu State, Nigeria was carried out using a gamma spectroscopy detector. Soil samples were collected at 20m depth intervals down the boreholes (wells) with a depth of about 200m and 140m for Well 1 (Amagu-Umuene) and well 2 (Ogulogu-Olo) respectively. The average values of 40K, 226Ra and 232Th obtained is 57.17Bqkg-1, 13.71Bqkg-1 and 10.49Bqkg-1 respectively for Well 1 and 59.77Bqkg-1, 11.49Bqkg-1 and 8.83Bqkg-1 respectively for Well 2.The computed absorbed dose and equivalent dose rate has a mean value of 15.20ηGyhr-1 and 0.13mSvyr-1for Well 1 and 13.30ηGyhr-1 and 0.12mSvyr-1 for Well 2, respectively. These values obtained are well within the world average value and may not result in any significant health effects on human and environmental hazard. The variation of the radionuclides for both wells is irregular down the depth of the boreholes profile. The irregular distribution pattern down the aquifer is attributed to the mineralogy and the geology of the study area.
Key Words: Natural radioactivity variation, soil depth profile, Enugu, Nigeria
PRIRODNI POJAVNI OBLICI VARIJACIJA RADIONUKLEIDA U SASTAVU ZEMLJIŠTA NA RAZLIČITIM DUBINAMA NA UDI I EZEAGU OBLASTIMA ENUGU STATE U NIGERIJI
Procena koncentracije radionukleida koji se prirodno javljaju u sastavu zemljišta na raznim dubinama u okviru dve bušotine u Enugu State u Nigeriji vršena je uz pomoć gama spektroskopa. Uzorci zemlje vađeni su na intervalima od 20 metara dubine u bušotinama (bunarima), gde je dubina bunara 1 (Amagu-Umuene) bila 200 a dubina bunara 2 (Ogulogu-Olo) bila 140m. Prosečne vrednosti 40K, 226Ra i 232Th dobijene su 57.17Bqkg-1, 13.71Bqkg-1 i 10.49Bqkg-1 tim redosledom iz bunara 1 i 59.77Bqkg-1, 11.49Bqkg-1 i 8.83Bqkg-1 tim redosledom iz bunara 2. Izračunate absorbovane doze i odgovarajuće stope doziranje imaju srednj vrednost od 15.20ηGyhr-1 i 0.13mSvyr-1 za bunar 1 i 13.30ηGyhr-1 i 0.12mSvyr-1 za bunar 2 tim redosledom. Ove vrednosti se nalaze u okviru granica preporučenih u svetu i može se reći da ne predstavljaju neki značajniji negativan uticaj na zdravlje ljudi ili životnu okolinu. Varijacije radionukleida u oba bunara su nepravilne duž samih bušotina. Nepravilna distribucija pripisuje se mineralnom i geološkom sastavu istraživane oblasti.
Ključne reči: Varijacije radioaktivnih materija u prirodi, sastav zemljišta na različitim dubinama, Enugu, Nigeria