Environmental Forensics ISSN: 1527-5922 (Print) 1527-5930 (Online) Journal homepage: http://www.tandfonline.com/loi/uenf20 Assessment of radiological parameters of soil in Kogi State, Nigeria M. R. Usikalu, I. A. Fuwape, S. S. Jatto, O. F. Awe, A. B. Rabiu & J. A. Achuka To cite this article: M. R. Usikalu, I. A. Fuwape, S. S. Jatto, O. F. Awe, A. B. Rabiu & J. A. Achuka (2017) Assessment of radiological parameters of soil in Kogi State, Nigeria, Environmental Forensics, 18:1, 1-14, DOI: 10.1080/15275922.2016.1263898 To link to this article: http://dx.doi.org/10.1080/15275922.2016.1263898 Published online: 26 Jan 2017. Submit your article to this journal View related articles View Crossmark data Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=uenf20 Download by: [80.248.0.226] Date: 27 January 2017, At: 00:09 ENVIRONMENTAL FORENSICS 2017, VOL. 18, NO. 1, 1–14 http://dx.doi.org/10.1080/15275922.2016.1263898 SCIENTIFIC COMMUNICATION Assessment of radiological parameters of soil in Kogi State, Nigeria M. R. Usikalua, I. A. Fuwapeb, S. S. Jattoc, O. F. Awec, A. B. Rabiuc, and J. A. Achukaa aDepartment of Physics, Covenant University, Ota, Ogun State, Nigeria; bDepartment of Physics, Federal University of Technology, Akure, Ondo State, Nigeria; cCentre of Atmospheric Research, National Space Research and Development Agency, Ayimgba, Nigeria ABSTRACT KEYWORDS The natural radioactivity levels of soil samples collected from four local government areas in Kogi Radioactivity; radiological State, Nigeria were measured using a hyper-pure germanium detector, and the radiological hazard hazard indices; soil; Kogi parameters associated with them were estimated. The measured concentration ranged from 7.82 § State 0.63 to 82.22 § 1.99 Bq kg¡1 for 238U, 11.05 § 1.10 to 114.86 § 4.72 Bq kg¡1 for 232Th, and 3.38 § 0.50 to 1272.20 § 23.36 Bq kg¡1 for 40K. Omala local government was found to have the highest concentrations of 238U (44.31 Bq kg¡1) and 232Th (52.13 Bq kg¡1), while Ajaokuta has the highest concentration of 40K (711.72 Bq kg¡1). The lowest activity concentrations of 238U and 232Th were measured from soil samples collected from Ankpa local government area and 40K from Dekina local government area. It was noted that the activity concentrations of 40K were generally low for all the areas investigated except for Ajaokuta areas. The radium equivalents calculated for all the locations were observed to be lower than the radiation protection regulatory body reference value of 370 Bq kg¡1. The radiological parameters estimated for most of the locations compared well with world average values, except for Odogba-okaba, Salem University, Forest, Nepa, Gerugu, Niger Bridge, Igaliwu, Ijeke-ogane, Bagana, and Abegikolo villages, whose values exceeded the recommended limit. This may suggest that those living or working in these areas may be exposed to higher radiation burden from the natural radionuclides. Introduction in the soil (Muhammad et al., 2011;Alharbi,2013). Terrestrial radiation exposure in form of gamma radia- Human exposure to radiation is mainly from topsoil, tion is due to primordial radionuclides of the 238U, and the concentration varies with soil types or from 232Th series, and 40Kintheearth’s crust (United the parent rock it originates from; studies have Nations Scientific Committee on the Effects of Atomic revealed high concentrations of uranium in phosphate Radiation [UNSCEAR], 2000). These radionuclides rocks and granite rocks (Sentikumar et al., 2010;Lar, and their progenies are one of the major contributors 2013; Sahu et al., 2014). It is practically impossible to to background radiation in an environment; their pres- do away with the primordial radionuclides as nearly ence in the earth’s crust has made it impossible for the all building materials are direct or finished products of soil around us to be free of radiation due to their long soil and rock. Even when it is not so, the building will half-lives. The concentration of radionuclides in an eventually be constructed on soil where radon gas environment varies from one location to another (progeny of U- and Th-decay series) can diffuse easily because of their variable composition in rock and soil out of the soil into the building. These radionuclides in different regions. Coupled with artificial activities are also ingested through food and drinking water or that release ionizing radiation to the environment, the inhaled, thereby causing internal radiation exposure. radioactivity of surface soil can sometimes be very Knowledge of their concentrations in soil is useful in high depending on the parent material. It was reported the assessment of any possible radiological hazard that that mining of uranium automatically increase its con- may arise with the use of the soil. The measurement of centration in the surface soil (Najat and Mazunga, radioactivity in soil cannot be overemphasized. Hence, 2013). Also, the presence of 238U, 232Th, and 40Kin the importance of this study as it seeks to measure the fertilizers that are applied to the soil for optimal crop activity concentrations in soils collected from Kogi yield has been reported to increase their concentration State and thereby provide baseline data for the CONTACT M. R. Usikalu [email protected] Department of Physics, Covenant University, P.M.B. 1023, Ota, Ogun State, Nigeria. Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/uenf. © 2017 Taylor & Francis 2 M. R. USIKALU ET AL. UNSCEAR databank and estimate the radiological rocks along with sediments weathered from these rocks. hazard indices emanating from the soils. Results from Ankpa is located within 7.30.57N, 7.43.29E, with an area this work would also be useful to policymakers. of 1,200 km2 and a population of 266,176 as of the 2006 census. It falls within the Anambra Basin, whose genesis has been linked with the development of the Niger Delta Materials and method Miogeosyncline and the opening of the Benue Trough Study area (Murat, 1972). The stratigraphy comprises a cyclic sedi- mentary sequence that started in the early Cretaceous Samples were collected from four local government areas (Reyment, 1965). Marine and fluviatile sediments com- (LGAs) in Kogi State, Nigeria: Dekina, Omala, Ajaokuta, prising friable to poorly cemented sands, shales, clays, and Ankpa. Dekina, which is located within 7.41.41N and limestone were deposited, with occasional coal, peat, and 7.01.20E, has an area of 2,461 km2 and a population and thin discontinuous seams of lignite (Chukwu et al., of 260,312 at the 2006 census (NPC, 2006). Geologically, 2008). The study area is typical of the Ajali formation or the area belongs to the upper Cretaceous formation of the false bedded sandstone and the Mamu formation. the Anambra Basin with a stratigraphic succession of The Ajali consists of thick, friable, poorly sorted sand- false bedded sandstone, lower coal measures, and Enugu stone, typically white in color but sometimes iron- shale. The coal outcrops occur at the bank of the Eniji stained. Ajalim sand is often overlain by a considerable River. Omala is located within 7.43N and 7.33E; it has an thickness of red earthy sands, formed by the weathering area of 1,667 km2 and a population of 108,402 at the and feruginization of the formation. The Mamu consists 2006 census. The geology of the area is more of the base- mainly of sandstone, carbonaceous shales, sandy shales, ment complex rocks of Nigeria. Reyment (1965) reported and some coal seams. that Anambra Basin is a platform that is only thinly cov- ered by older sediment during the Albian-Santonian epoch of the Cretaceous. Ajaokuta is located within Sample preparation and radioactivity counting 6.40.11N and 8.48.19E; it has an area of 1,362 km2 and a population of 122,321 at the 2006 census. This area is Five soil samples were collected from different strategic part of the basement complex of Nigeria and is underlain points at each location (LGA) for better representative mainly by schists and intrusive granitic and pegmatitic sampling (see Figure 1). Samples were kept in Ziploc Figure 1. Map showing the sampling locations. ENVIRONMENTAL FORENSICS 3 Table 1. Activity concentrations measured in the locations. Sample code Location No. of samples 238U (Bq kg¡1) 232Th (Bq kg¡1) 40K (Bq kg¡1) DK 1 Okura 5 7.94 § 0.59 13.26 § 1.23 5.15 § 0.45 DK2 Oje 5 49.70 § 2.43 48.58 § 3.42 20.78 § 1.35 DK 3 Ijale 5 8.92 § 0.99 14.02 § 1.30 7.02 § 0.50 DK 4 Ologba 5 43.62 § 2.35 56.90 § 3.16 BDL DK 5 Odu 5 9.38 § 0.71 15.87 § 1.38 9.40 § 0.64 DK 6 Dekina 5 12.51 § 1.24 21.16 § 1.78 10.35 § 0.74 DK 7 Ajiyolo 5 13.91 § 1.04 17.62 § 1.39 3.85 § 0.45 DK 8 Abocho 5 26.41 § 1.47 34.74 § 2.34 26.89 § 1.38 DK 9 Ajagum 5 15.10 § 1.29 19.45 § 1.63 19.44 § 1.01 DK 10 KSU Campus 5 22.30 § 1.29 31.71 § 2.75 BDL AK 1 Emekutu 5 17.14 § 1.55 19.95 § 1.57 8.10 § 0.61 AK 2 Ogodo 5 9.74 § 0.91 15.06 § 1.47 13.42 § 0.79 AK 3 Ankpa 5 11.62 § 1.04 19.01 § 1.79 13.90 § 0.78 AK 4 Ajobe 5 7.82 § 0.63 11.05 § 1.10 BDL AK 5 Odogba Okaba 5 73.89 § 2.69 73.29 § 4.34 251.62 § 5.90 AK 6 Ejegbo 5 16.01 § 1.21 20.53 § 1.88 18.97 § 1.13 AK 7 Anabo 5 9.91 § 1.01 12.45 § 1.08 19.62 § 1.03 AK 8 Ofugo 5 11.65 § 0.73 12.26 § 1.15 BDL AK 9 Inye 5 20.56 § 0.86 12.75 § 0.90 19.62 § 1.03 AK 10 Ejeke 5 11.54 § 0.97 14.75 § 1.63 BDL AJ 1 Salem University 5 59.23 § 1.51 63.46 § 4.75 1272.20 § 23.36 AJ 2 Prime Polytechnic 5 15.12 § 1.07 26.76 § 2.14 700.64 §