Deparment Of Environmental Management and Toxicology

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Browsing Deparment Of Environmental Management and Toxicology by Author "Awotoye, Olusegun O."

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    Markers of Environmental Health: Nickel and Chromium Levels in Soil and Vegetation around a Steel Recycling Facility in Southwest Nigeria
    (SCIENCEDOMAIN international, 2014-01-02) Salami, Olalekan O.; Awotoye, Olusegun O.; Owoade, Oyediran K.
    Aim: To mark the environmental health status in the vicinity of a steel recycling facility in southwestern Nigeria using Nickel and Chromium levels in the topsoil and leaves of Chromolaena odorata. Methodology: Conventional methods were used to determine some soil parameters (pH and electrical conductivity in 1:1 soil: deionized water; percentage organic carbon using chromic acid oxidation method and particle size analysis using hydrometer method). The metal content in the soil and plant samples were analysed using the Atomic Absorption Spectrophotometer after digestion and extraction. Results: The results of the soil within the factory showed pH values of 7.50 – 8.80 and reduced organic matter content indicating alkaline conditions. Electrical conductivity values were comparatively higher for soils within the factory (423 – 1550 µs/m) than soils outside the factory (146 – 226 µs/m) showing presence of some soluble salts in the soil. The levels of Ni and Cr in the soil were higher within the factory than outside of the factory. Nickel concentrations of the soil increased with increasing distance from the factory up to 200 m. Similar trends occurred for Cr in the eastern side of the factory where the detectable concentrations (2.29±0.05 – 33.26±0.02 mgkg–1) was observed. The Ni content in the soil around the factory ranged from: North (0.76±0.01 – 1.46±0.06 mgkg–1); East (0.19±0.05 – 2.68±0.04 mgkg–1); West (0.21 ± 0.01 – 1.46±0.07 mgkg–1) and South (0.22±0.02 – 1.89±0.01 mgkg–1). Within the factory however, the scrap yard contained high concentration of Cr 24.15±0.04 mgkg–1 while the soils from the dumpsite for sorted wastes contained elevated concentrations of Ni (73.17±0.02 mgkg–1). Nickel and chromium content in the plant leaves in this study ranged from 1.40 – 3.60 mgkg–1 and 0.40 – 1.5 mgkg–1. Conclusion: Further increase in the Cr and Ni levels in the soil and plants of the study site poses a potential health hazard to animals that graze the area and man through consumption of forage and agronomic crops cultivated around the factory by peasant farmers.
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    Soil Quality from Nigerian Alfisol Under Different Agricultural Land Use Types
    (Springer, 2023-06-28) Salami, Olalekan O.; Adesanwo, Olushola O.; Awotoye, Olusegun O.
    This study focuses on the evaluation of different chemical characteristics of humic acids (HA) from Nigeria Alfisol as surrogates of soil agroecological quality under different cultivation regimes in proximity. Conventional cassava farm, oil palm plantation, agroforestry and undisturbed sites were studied at two soil depths of 0 – 15 cm and 15 – 30 cm using elemental analysis and Fourier transform infrared spectroscopy (FTIR). The highest yield of HAs was recorded at the undisturbed site at the two soil depths (topsoil, 25% and subsoil, 15%). The per cent carbon of the humic acid extracted from the topsoil and subsoil clustered around 56%. Strong peaks attributed to structural vibrations of aromatic C=C and antisymmetrical stretching of COO– groups around 1630 cm–1 region was common to all the spectra. The topsoil of the oil palm plantation showed band peak at 1230 cm-1 which were attributed to C-O stretching and OH bending of COOH functional group. Cultivation type and soil depth had a great influence on the humic acid yield. Crops planted on the farms do not significantly influence the characteristics of humic acids which suggest high stability and resilience as shown in the FTIR spectra of HAs. However, notable differences in the intensity of some bands were observed depending on site characteristics and soil depth. A steady supply of plant residues in the tree-based agricultural systems significantly improved OM accumulation and quantity of humic acid.