BITUMEN POLLUTION AND HEAVY METAL CONCENTRATION IN SURFACE SOIL: IMPLICATION FOR SOIL CONSERVATION
2025
Ogunsusi, K.
Bitumen-derived heavy metals pose a serious threat to the environment by contaminating soil and harming plants, animals, and ecosystems. The study was carried out at Ode-Irele in Ondo State of Nigeria where there were seepages of bitumen as well as exploratory activities. Composite samples of soils in bitumen seepages and exploratory sites were collected to a depth of 15cm and that of the control was obtained at Ebute-Irele. Heavy metals in soils - Mn, Fe, Cu, Zn, Pb, Cr, Cd, Ni, V, and As were determined using atomic absorption spectrometry. Data were analyzed using descriptive statistics and t-tests of unpaired samples. Results showed that Mn (805.00 ± 136.30 mg/kg, 870 ± 198.00 mg/kg), Fe (992.50 + 115.30 mg/kg, 1110.00 ± 141.40 mg/kg), Pb (8.0 ± 3.00 mg/kg, 290 ± 56.60 mg/kg), and As (4.80 ± 1.30 mg/kg, 5.00 ± 0.00 mg/kg) were respectively common to soils where there were bitumen seepages and where exploratory activities had taken place with higher concentrations than corresponding values in bitumen. The values of Mn, Cu, Zn, Pb, Ni, As, Cr and Cd respectively in both seepage and exploratory soils exceeded FEPA (1991) guidelines. Higher concentrations of heavy metals in bitumen-polluted soil should be continuously monitored during bitumen mining as they may represent significant environmental risks to soil conservation.
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