Assessment of Concentrations and Distributions of Natural Radionuclides in Soils of Abandoned Mine Sites of Jos South and Barkin Ladi in Plateau State Nigeria

Abstract

Barkin Ladi and Jos South Local Government Area of Plateau State is situated in the central part of Northern Nigeria, on a rugged terrain of lowlands. It is the principal centre of tin and columbite mineralization, which forms the focal area of younger granites. The work was aimed at assessing the concentration and distribution of radionuclides in soils of abandoned tin mines and the soil’s physicochemical properties. The samples were collected in July, from five different locations in both Barkin Ladi and Jos South where mining activities were predominant. The samples were analyzed using a gamma-ray spectrometer. The result obtained reveals a range of the concentrations of 40K as 116.76 ± 0.21 to 250.15 ±0.,42 Bq/kg, 226Ra from 24.37 ± 0.31 to 90.45 ± 0.86 Bq/kg, and 232Th from 15.74 ± 0.71 to 88.43 ± 0.14 Bq/kg. The result of the physicochemical properties of the soil analyzed ranges from pH (3.12 to 6.81); organic carbon (0.01 to 1.62%); organic matter (0.22 to 3.01 %), cation exchange capacity (1.01 to 4,21Cmol/kg); clay (9.72 to 40.82 %); silt (8.32 to 40.32% and sand (32.42 to 75.38%) respectively. All the 40K results analyzed in all the sampling sites were lower than the recommended limits of 412Bq/kg, whereas most of the results of 226Ra and 232Th were above the 33Bq/kg and 45Bq/kg recommended safe limits. Exposure to elevated levels of naturally occurring radionuclides in soil can pose potential health risks to nearby populations. The physicochemical properties of the soil varied across the sampling sites. Most of the sampling sites are polluted with radionuclides and migrations of the radionuclides from the ex-mining sites to other parts of the environment were noticed from the studies conducted.