Contributions of Municipal Solid Waste to Heavy Metal Concentration in Soil Near Oke Ese Dumpsite, Ilesha, Osun State, Nigeria

E. E. Awokunmi; S. S. Asaolu; S. O. Adefemi; A. Y. Gbolagade
The levels of heavy metals in water and soil have increased due to the indiscriminate dumping of domestic and industrial wastes. This research was conducted to examine the contributions of municipal solid waste disposal to the concentrations of heavy metals in water sources near Oke-Ese Dumpsite in Ilesha, Osun State. Soil samples were collected from Oke -Ese Dumpsite at intervals of 10 m, at depths of 0-15 cm using calibrated soil auger. A control soil sample was also collected at a distance of 200 m from the last sampling point at the dumpsites. Water samples were randomly collected from five water sources (river and wells). Physicochemical parameters, sequential extraction and heavy metals analyses were conducted on collected samples. Results indicate that pH (6.20 ± 0.11), organic matter content (8.60 ± 0.16) and Cation Exchange Capacity (78.4 ± 0.17) of the control sample were greater than 5.70 ± 0.12, 7.62 ± 0.14 and 56.26 ± 0.24 respectively. Heavy metals were observed at elevated concentrations at dumpsites locations with average values in the following order: Pb (22.7), Fe (134.9), Cd (42.7), Cu (9.0), Zn (116.0), Mn (15.5), Ni (27.7) and Cr (11.0). However, the results of sequential extraction revealed that these heavy metals were distributed in considerable proportions in the exchangeable fraction of soil (11.2 – 89.3 mg/kg). Both Sequential Extraction Procedures (SEPs) employed, indicated the possibility of these metals leaching into the surrounding water sources. In addition, these heavy metals were found in greater concentrations than the limit set by World Health Organisation (WHO) in all water sources near the Oke-Ese Dumpsite. In conclusion, there is need to cite dumpsite away from residential area and contaminated water sources should be treated before domestic applications.
Contributions; Municipal; Heavy Metals; Dumpsites; Concentrations
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