Arab J Sci Eng (2012) 37:1483–1490 DOI 10.1007/s13369-012-0245-y RESEARCH ARTICLE - PHYSICS Matthew Omoniyi Isinkaye Distribution of Heavy Metals and Natural Radionuclides in Selected Mechanized Agricultural Farmlands Within Ekiti State, Nigeria Received: 24 December 2010 / Accepted: 5 June 2011 / Published online: 19 April 2012 © King Fahd University of Petroleum and Minerals 2012 Abstract Topsoil samples collected from five mechanized agricultural land were analyzed for their heavy metal and natural radionuclide constituents using atomic absorption (AAS) and γ -ray spectrometric methods, respectively. The results of the atomic absorption spectrometric analysis show that Pb and Zn have low concen- trations, while Ca, As and Cu have enhanced level of concentrations in all the farmlands. γ -ray spectrometric analysis indicates that 40 K concentrations are higher than the world average value for soil, while 226 Ra and 232 Th are lower than their corresponding world average values. Pearson correlation coefficients were deter- mined among heavy metals and natural radionuclides concentrations. The dose rates at 1 m above the ground level and the corresponding biological effective dose rates were estimated. The values obtained were compared with values from other locations around the world. The ranges and mean values of all the radiation hazard parameters considered in this study do not show any significant departure from the values obtained for areas with normal background levels around the world. Keywords Heavy metals · Natural radioactivity · Agricultural farmlands · Pearson correlation coefficient · Dose rates 1 Introduction Heavy metals occur in the environment primarily as a result of natural processes such as weathering of the source rock and atmospheric deposition. Pollution of the environment by toxic contaminants such as heavy metal ions may occur as a result of human activities, which include application of organic fertilizer in agricul- ture, burning of fossil fuel, mining and metallurgical processes and their waste disposal [1]. Some metals like Zn, Cu, Fe and Mn are essential for the metabolic activities in organisms, while others such as Cd, Hg, Cr and Pb are extremely toxic even at low levels [2]. Toxic metals can be taken by humans through direct inhalation M. O. Isinkaye (B ) Department of Physics, University of Ado Ekiti, P.M.B. 5363, Ado Ekiti, Nigeria E-mail: niyikaye2002@yahoo.com 123