Heavy metals assessment of soils and vegetation within and around a scrap metal recycling factory site in Ile-Ife, Osun State, Nigeria.
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Date
2013
Authors
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Publisher
Obafemi Awolowo University
Abstract
This study determined the trace metal concentrations of soil and plants around the scrap metal recycling factory in Ile – Ife, Nigeria with a view to assessing the impact of emissions, slag and sorted wastes from the recycling process on the soil and vegetation in the study area.
Sample plots of 10 m x 10 m were established at 50 m interval from the factory site up to 350 m in the four directions of North, East, West, and South of the factory and at a control site 5 km from the factory during the dry and wet seasons. Within each plot, plant species were identified to species level and five core soil samples were randomly collected with a soil auger at a depth of 0 – 15 cm. The soil samples were homogenized before a composite sample was drawn, which was air-dried, sieved through a 2 mm sieve and analysed for heavy metals (Pb, Cd, Cu, Zn) using Atomic Absorption Spectrophotometer (AAS) after extraction. Plant parts of the identified plants species were also collected and analysed for heavy metals using AAS after wet digestion. The data collected were subjected to one way analysis of variance and Duncan Multiple Range Test to test for significance at p < 0.05.
The soil within the factory had higher concentrations of Cd, 2.08 mg kg–1; Zn, 72.69 mg kg–1 and Cu, 2.72 mg kg–1 than soil outside the factory Cd, 0.78 mg kg–1; Zn, 24.70 mg kg–1 and Cu, 1.97 mg kg–1. However, the soil at the dumpsite for sorted wastes contained high Cd content of 4.83 mg kg–1 above tolerable level of 3.0 mg kg–1. The northern side of the factory had elevated concentrations of Pb (2.32 mg kg–1) and Zn (19.24 mg kg–1) compared with those in the southern side (Pb, 0.83 mg kg–1 and Zn, 7.36 mg kg–1). Also, Pb and Cu concentrations in the soil increased with increasing distance from the factory site in all directions except in the southern direction which showed no specific pattern. Seasonal variation also occurred in the soil heavy metal contents with elevated concentrations of Pb, Cu and Zn during the dry season. The study further revealed that the plant tissues from the study area contained high concentrations of heavy metals of Pb (0.59 mg kg–1), Cd (0.67 mg kg–1), Cu (0.86 mg kg–1) and Zn (0.94 mg kg–1) compared with that of the undisturbed forest (Pb 0.29 mg kg–1, Cd 0.07 mg kg–1, Cu 0.48 mg kg–1 and Zn 0.50 mg kg–1). The Cd level in the plant tissues of the study site ranged from 0.54 mg kg–1 to 0.67 mg kg–1 and was above the tolerable level of 0.20 mg kg–1.
The study concluded that the emissions and wastes generated from the scrap metal recycling factory elevated the heavy metal burden of the soil and vegetation within and around the factory.
Description
xii, 98p
Keywords
Scrap metal recycling, Heavy metals, Soils, Vegetation, Emissions, Metals, Scrap
Citation
Salami, O.O. (2013). y metals assessment of soils and vegetation within and around a scrap metal recycling factory site in Ile-Ife, Osun State, Nigeria. Obafemi Awolowo University