Physico-chemical Properties, Heavy-metal Contents and Radioactivity Levels in Soils around a Cement-production Facility in Ogun State, Nigeria

Abstract: The physico-chemical properties, heavy metal content and the primordial radionuclide activities in soil samples from four locations around a cement production facility were studied. The physico- chemical properties of the soil samples were determined after aqua regia (HNO3:HCl) digestion and analysis with atomic absorption spectrophotometer (AAS) Perkin Elmer Analyst 200, while the activity concentration of the radionuclides was determined by a non-destructive analysis using a computerized gamma-ray spectrometry system with high-purity germanium (HPGe). The pH and electrical conductivity in the soil were in the range of 6.57 to 7.39 and 25.5 to 462 µs cm-1, respectively. The cation-exchange capacity (meq/100 g) for Na+, K+, Ca2+ and Mg2+ were within the ranges 0.142 to 0.622, 0.145 to 1.725, 2.112 to 4.279 and 0.092 to 0.271, respectively. Lead and cadmium were each detected in only one sample. The average activity for Uranium -238, Thorium - 232 and Potassium - 40 in soil was between 3.177 ± 0.330 Bq kg-1 - 7.934±1.190 Bq kg-1, 4.201±0.429 Bq kg-1 – 10.702 ± 1.504 Bq kg-1 and 97.733 ± 2.268 Bq kg-1 – 144.926 ± 21.738 Bq kg-1, respectively. The physico-chemical properties obtained were within the range of values observed by an earlier study conducted in the area; the concentrations of the heavy metals in the soils as well as the radiological hazard indices due to the presence of naturally -occuring radionuclide materials (NORMs) in the soils were very low and are not expected to constitute any environmental hazard. Keywords: Physico-chemical properties, Radioactivity, Cement, Ewekoro, Effective dose.