IOSR Journal Of Applied Physics (IOSR-JAP) e-ISSN: 2278-4861.Volume 12, Issue 3 Ser. I (May–June 2020), PP 07-12 www.Iosrjournals.Org DOI: 10.9790/4861-1203010712 www.iosrjournals.org 7 | Page Determination of the Transfer Factor and Dose Rate of radionuclides in Some Selected Crops in Kogi state, Nigeria. John Actor Ocheje 1 , Alexander A. Tyovenda 2 1. Department of Pure & Applied Physics, Federal University Wukari Taraba state, 2. Department of Physics,Federal University of Agriculture Makurdi Benue state Abstract Radionuclide activity distribution and transfer factor (TF) in plants are crucial parameters used to assess radioactive contamination in the environment, impact of soil radioactivity on agricultural crops and its risks to humans. The activity concentrations of 238 U, 232 Th and 40 K in some selected crops and soils of Kogi state have been determined. The average activity concentration of 40 K, 232 Th and 238 U in crop were 180.18, 25.82 and 30.15 Bqkg -1 respectively. The activity concentration of 40 K, 232 Th and 238 U in soil ranges from 218.22 to 626.92 Bqkg -1 with an average value of 331.82, 32.76to 118.93 Bqkg -1 with average values of 67.38 Bqkg -1 and 41.36 to 67.30 Bqkg -1 with an average value of 52.84 Bqkg -1 respectively. And the values of the transfer factor obtained for 40 K, 232 Th and 238 U were in the range of 0.45 to 0.79 with an average value of 0.35, 0.15 to 0.58 with an average value of 0.56 and 0.28 to 1.09 with an average value of 0.43 respectively. The high value of transfer factor in some locations may be due the long usage of inorganic fertilizers and herbicides in those farms. The average values of radium equivalent activity (Ra eq ), absorbed dose rate (D), annual effective dose rate (AEDE), external and internal hazard indices and excess life cancer risk (ELCR) are 174.74 Bqk -1 , 79.45 nGyh -1 , 0.10 mSvy -1 , 0.47, 0.62 and 0.34 for respectively. These values are within the recommended values by UNSCEAR except for AEDE and ELCR. The mean values of H ex. and H in are less than unity, hence the result does not constitute any significant radiological health risk to the farmers and the community as a whole. --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 29-04-2020 Date of Acceptance: 13-05-2020 --------------------------------------------------------------------------------------------------------------------------------------- I. Introduction A lot of contaminants in human environment have attracted serious attention in research community all around the world. This is as a result of environmental and human healthconsequences associated with its exposure, especially at levels above the prescribed safetylimits. Natural radioactivity has always been present and broadly distributed in the earth’scrust and the atmosphere, either as primordial radionuclides of uranium ( 238 U) and thorium( 232 Th) decay series and radioactive potassium ( 40 K), or as cosmic radiations that are producedconstantly in the atmosphere (Samadet al., 2012, Hasan et al., 2013, ferdous et al., 2015) Primordial radionuclides of 238 U and 232 Th decay series and 40 K which has extremely long half-lives are ofgreat concern in terms of radiation exposure due to their gamma ray emitting potentials. There are two mechanisms for the contamination of vegetation, i.e., by root uptake or directly by aerial deposition of fallout radionuclides on plants. It is necessary to carry out an accurate assessment of these radionuclides in the daily used food materials in order to ascertain the degree of risk and deleterious effects to the public health (Alharbi and El-Taher, 2013). The amount of radioactivity in soil is transferred in minute quantities into plants. Plants absorb radionuclides from soil and enter the human body via food. The supply of plant nutrient is limited and depleted with every harvest leading to a drastic reduction in quality and yield in crop plant. Just like the rest of the world, Nigeria’s population is increasing and there is also the need to increase availability of food by increasing the rate of food production via application of chemical fertilizers. The major raw materials for the production of chemical fertilizers must therefore supply the essential nutrients necessary for plant growth. The essential nutrients are Nitrogen, phosphorus and potassium. Natural radioactivity of mainly Uranium-238 ( 238 U), Thorium-232 ( 232 Th) and Potassium-40 ( 40 K) seen in phosphate fertilizers emanate from the phosphate ore, (due to geological reasons) which is the main raw material used for phosphate fertilizer production. The application of phosphate fertilizer globally for increased crop production and land reclamation has risen to more than 30 million tons annually (Ei-Taher and Abbady, 2012).The normal concentration of uranium in phosphate rocks is between 30 and 260 ppm which by far exceeds its abundance in the earth’s crust. Theapplication of chemical fertilizers may increase the phosphate and uranium concentration in thesoil thereby increasing the concentration in nutrients. Kogi state is blessed with a lot of nature resources which has attracted industries like the cement factory, steel industry and many more. The waste and operation of these industries could directly or indirectly