Radiometric impact assessment around two quarry sites, Benin-Owo express way, southwestern Nigeria

Abstract

Total reliance on quarry products as construction materials has prompted commercial quarry activities globally. However, potential risks introduced by radiation exposure to quarries in two different locations in Ondo State, Nigeria were assessed to evaluate the background radiation and distribution of naturally occurring radionuclides associated with these areas. A ground radiometric mapping of eleven traverses across the two quarry sites was carried out using Gamma ray spectrometer. Naturally occurring radionuclides ²³⁸U, ²³²Th and ⁴⁰K in natural quarried materials of coarse rock aggregates and soil samples collected at a maximum depth of 2 m and up to 500 m away from the quarry sites were measured using gamma spectrometry method. Spectrometric data were processed and presented in form of radiometric maps showing the distribution of radiation level in each location. Results show that activity concentrations varied from one location to another. The radiation level in the recently quarried coarse rock aggregates (QF1 and QF2) (372 cps and 382 cps) are higher than the previously quarried coarse rock aggregates (QP1 and QP2) (365 cps and 377 cps) of the quarry sites. Activity concentrations in soils are in the order ²³²Th < ²³⁸U < ⁴⁰K. The mean radioactivity concentration values of ²³²Th, ²³⁸U and ⁴⁰K are 0.0027±0.0003 Bq/kg, 0.028±0.0012 Bq/kg, 47.45±0.0313 Bq/kg and 0.0036±0.00036 Bq/kg, 0.026±0.0012 Bq/kg and 69.42±0.0313 Bq/kg respectively for soils within the quarries. At 500 m away from the quarry sites, mean values are 0.0008±0.75 Bq/kg, 0.020±0.0012 Bq/kg, 41.54±0.0313 Bq/kg and 0.0049±0.0004 Bq/kg, 0.052±0.0012 Bq/kg and 200.32±0.0313 Bq/kg respectively. The radiological hazard indices calculated were used to access the health implication of exposure to rock aggregates and soil of the study areas. The values obtained when compared with their corresponding world permissible values were found to be below the internationally recommended values. Therefore, the level of radiation and interaction with the rock aggregates and soils do not expose the workers and people within and around the quarries to health problem. Hence, the quarry products can be used as building material for housing and road constructions.

Keywords

• Quarries
• Radiometric mapping
• Radionuclides
• Hazard indices
• Rock aggregates

References

1. Avwiri, G.O., Osimobi, J.O. and Agbalagba, E.O., 2012. Evaluation of radiation hazard indices and excess lifetime cancer risk due to natural radioactivity in soil profile of Udi and Ezeagu Local Government Areas of Enugu State, Nigeria. Journal of Environmental and Earth Sciences, 1(1), 1-10.
2. Avwiri, G.O., Egieya, J.M. and Ononugbo, C.P., 2013. Radiometric assay of hazard indices and excess lifetime cancer risk due to natural radioactivity in soil profile in Ogba/Egbama/Ndoni Local Government Area of Rivers State, Nigeria. Academic Research International, 4(5), 54-65.
3. Beretka, J. and Mathew, P.J., 1985. Natural radioactivity of Australia building materials industrial wastes and byproducts. Health Physics, 48, 87-95.
4. Brimhal, W.H. and Adams, J.A.S., 1982. Concentration changes of thorium, uranium and metals in hydrothermally altered Conway Granite, New Hamsphire. Geochim, Cosmochim Acta, 33, 130-131.
5. David, O., 1998. Mining and quarrying occupational health and safety committee. Quarrysafe hazardous substances in quarries.
6. Environmental Measurement Laboratory (EML) manual, 1983. Volchok, Herbert, L., dePlanque, Gail (Eds.), twenty-sixth ed. New York, US Department of Energy, Environmental Measurement Laboratory.
7. Gunn, P., Minty, B. and Milligan, P., 1997b. The airborne gamma-ray spectrometric response over Arid Australian Terranes. In A. Gubins (Ed.), Proceedings of Exploration 97: Fourth Decennial International Conference on Mineral Exploration, Australia. 733-740.
8. IAEA, 1991. Airborne gamma ray spectrometer surveying, International Atomic Energy Agency, Technical Report Series, No. 323, 97.

9. IAEA, 2003. International Atomic Energy Agency (IAEA) guidelines for radioelement mapping using gamma ray spectrometry data, Vienna.
10. James, L.W., 2013. Health hazards of mining and quarry ing, safework_bookshelf. http: // www. Ilo.org/safework _bookshelf/English?content&nd=857170934.
11. Milsom, J., 2003. Field Geophysics: The geological field guide series, John Milsom University College, London. Published by John Wiley and Sons Ltd. Third edition. 51- 70.
12. MontajTM Tutorial, 2004. Two-Dimensional frequency domain processing of potential field data.
13. Rahaman, M.A., 1989. Review of the basement geology of southwestern Nigeria. In: Kogbe, C.A., (ed) Geology of Nigeria, Rock View (Nig.) Limited, Jos, Nigeria. 39- 56.
14. Ramasamy, V., Suresh, G., Meenakshisundaram, V. and Gajendran, V., 2009. Evaluation of natural radionuclide content in river sediments and excess lifetime cancer risk due to gamma radioactivity. Research Journal of Environmental and Earth Sciences, 1(1), 6-10.
15. Taskin, H., Karavus, M., Topuzoglu, A., Hindiroglu, S. and Karahan, G., 2009. Radionuclide concentrations in soil and lifetime cancer risk due to the gamma radioactivity in Kirklareli, Turkey. Journal of Environmental Radioactivity, 100, 49-53.
16. Tim Driscoll, Steenland, K., Nelson, D.I. and James, L., 2004. Environmental Burden of Disease Series, No. 7; World Health Organization Protection of the Human En vironment, Geneva.
17. Tufail, M., Akhar, N., Jaried, S.A. and Hamid, T., 2007. Natural radiation hazard in building bricks fabrication from soils of two districts of Pakistan. Radiological Protection, 27, 481-492.
18. UNSCEAR, 2000. United Nations Scientific Committee on the Effects of Atomic Radiation. Sources, effects and risks of ionizing radiation. Report to the general assembly, annexes B: Exposure from natural radiation sources. New York. 678-679.
19. Veiga, R.G., Sanches, N., Anjos, R.M., Macario, K., Bastos, J., Iguatemy, M., Aguitar, J.G., Santos, M.A., Mosquera, B., Carvaiho, C., Baptista, M. and Umisedo, N.K., 2006. Measurement of natural radioactivity in Brazilian beach sands. Radiation Measurements, 41, 189- 196.
20. Wilford, J., Bierwirth, P. and Craig, M., 1997. Application of gamma-ray spectrometry in soil or regolith mapping and applied geomorphology. Journal of Australian Geology and Geophysics, 17(2), 201-216.