MEASUREMENT OF ACTIVITY CONCENTRATIONS OF NATURAL RADIONUCLIDES IN THE TOP SOIL OF UNIVERSITY OF AGRICULTURE, ABEOKUTA, (UNAAB) FARMS

I. C. OKEYODE
S. A. GANIYU

Keywords: Top Soil Samples, Baseline, Activity, Radionuclides

Abstract

The natural radioactivity levels in the soils of University of Agriculture Abeokuta farms were measured. 20 soil samples were collected to a depth of about 10cm in twelve different farmlands within UNAAB community. The average activity concentrations obtained for the three radionuclides were 520.13±32.06 Bq/kg for ⁴⁰K, 33.66±23.27 Bq/kg for²³⁸U and 49.83±15.61 Bq/kg for²³²Th, respectively. The distributions of these radionuclides were found to be uneven. The value of Uranium-238 was the same at locations 4 and 16 but not detectable at locations 9 and 11, respectively. The average values of the absorbed dose rates in air of each radionuclides were found to be 21.84 nGy/hr for ⁴⁰K, 14.99 nGy/hr for ²³⁸U and 33.19 nGy/hr for ²³²Th. The baseline average outdoor annual effective dose equivalent in UNAAB farms due to the radioactivity concentrations was found to be 86.92±28.37mSv/yr. This value can be taken as representing the baseline values of natural radioactivity as no artificial radionuclide was detected at any of the locations visited.

References

Anthony, A.E., Bolarinwa, A.T. 2004. Petrochemistry and Petrogenesis of granite gneisses in Abeokuta area south western Nigeria. J. of Mining and Geology, 40(1): 1-8.

Arogunjo, A.M. 2007. Terrestrial gamma radiation and the radiological implication in south western Nigeria J. Applied Sci., 7(11): 1534- 537

Bakac, M. 2003. Radioactivity Measurements in Soils, Sediments and waters from Salihli basin, Western Turkey., Fifth-General Conference of the Balkan Physical Union, August 25-29, 2003, Vrnjacka Banja, Serbia and Montenegro, P. 1437-1442

Beck, H.L., Decompo, J., Gologak, J. 1972. “In-Situ Ge (Li) and NaI (Tl) gamma – ray Spectrometry”. Health and Safety Laboratory, U.S. Atomic Energy Commission Report, 258.

Evans R.D. 1974. Radium in man. Health Phys, 27:497-510

Farai, I.P., Jibiri, N.N. 2000. Baseline Studies of Terrestrial Outdoor Gamma Dose rate Levels in Nigeria. Rad. Protection Dosimetry, 88(3):247-254. 2nd Edition Pergamon Press Limited U.K.

Jibiri, N.N., Farai, I.P. 1998 Assessment of dose rate and Collective Effective Dose Equivalent due to Terrestrial Gamma Radiation in the city of Lagos, Nigeria Rad. Protection Dosimetry, 76(3): 191-194

SKB 1999. SR97-Post Closure Safety, TR-99-06, SKB, Stockholm

Stanley, E.M 1994: Environmental Chemistry 6th Edition Lewis Publishers London.

UNSCEAR, 1988. Ionizing Radiation Sources, Effects and Risks of Ionizing Radiation.

Issue

Vol 8 No 2 (2009)

Section

Articles