Exploiting Phytoremediation as a Technique for Conservation of Bitumen Polluted Soil
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Date
2018
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University of Ibadan
Abstract
Toxic metal pollution of soil is a major environmental problem bedeviling soil conservation that most conventional remediation approaches cannot solve. High concentrations of heavy metals have both
environmental and toxicological effects. This infringes on integrity of ecosystems by affecting indices such as plant abundance and diversity. Study was conducted in Ode-Irele bitumen belt of Ondo State, Nigeria where there are bitumen seepages and exploratory activities, and Ebute-Irele without any record of bitumen seepages served as control. Composite samples of bitumen, soils contaminated with bitumen, and plants naturally growing on bitumen seepage and exploratory sites were collected for determination of heavy metal concentrations using atomic absorption spectrometry. The result showed that more metals were significantly higher in soils and bitumen sample than plants of exploratory site than seepage site. Mn, 870.00±197.99mg/kg, Cu, 215±21.21mg/kg, Zn, 290.00±56.57mg/kg, Cd, 3.50±0.71mg/kg, V, 10.00±0.00mg/kg, and As, 5.00±0.00mg/kg were significantly higher in exploratory surface soil than 571.83±112.93mg/kg, 39.67±8.89mg/kg, 86.43±8.56mg/kg, 3.17±0.57mg/kg, 0.37±0.18mg/kg, 7.93± 0.57, and 3.83±0.12mg/kg respectively in plants. The result of the mean difference of heavy metals between plants on exploratory bitumen site and bitumen sample also showed that Cu, 192.50±23.33mg/kg, Zn, 244.25±47.73mg/kg, Pb, 7.80±1.27mg/kg, Cd, 3.60±0.29mg/kg, and As, 4.60±0.42mg/kg in bitumen sample were significantly higher than 39.67±8.89mg/kg, 86.43±8.56mg/kg, 3.17±0.57mg/kg, 0.37±0.18mg/kg, and 0.38±0.12mg/kg respectively in plants on the exploratory site. However, V, 7.93±0.57mg/kg was significantly higher in plants than 6.00±1.27mg/kg in bitumen sample. The result of the mean difference of heavy metals between plants on exploratory site and bitumen sample further showed that Cu, 192.50±23.33mg/kg, Zn, 244.25±47.73mg/kg, Pb, 7.80±1.27mg/kg, Cd, 3.60±0.29mg/kg, and As, 4.60±0.42mg/kg in bitumen sample were significantly higher than 39.67±8.89mg/kg, 86.43±8.56mg/kg, 3.17±0.57mg/kg, 0.37±0.18mg/kg, and 0.38±0.12mg/kg respectively in plants on the exploratory site. However, V, 7.93±0.57mg/kg was significantly higher in plants than 6.00±1.27mg/kg in bitumen sample. The higher values of heavy metals in soils and bitumen sample over corresponding values in plants was possibly due to plants’ ability to accumulate and gradually remove the metals from their tissues, a process known as phyto degradation or rhixo degradation. Panicum laxum (56.5 %) and Lycopodium ceernum (43.7%) were the most abundant plants that naturally grow on seepage and exploratory sites respectively. The plants found naturally growing on bitumen polluted soil have the capacity to hyper accumulate heavy metals, and so should be used for remediation of bitumen polluted soil.
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Ogunsusi, K. and Adeleke, B.O. (2018). Exploiting phytoremediation as a technique for conservation of bitumen polluted soil. Journal of Tropical forest Resources, 34: 10-23