Journal of Applied Biosciences (J. Appl. Biosci.) [ISSN 1997 - 5902]
Volume 40: 2727 - 2737. Published April 12, 2011.
Contributions of municipal refuse dumps to heavy metals concentrations in soil profile and groundwater in Ibadan Nigeria
B.A. Adelekan1* and A.O. Alawode2
1Department of Agricultural Engineering, Federal College of Agriculture, Institute of Agricultural Research & Training, PMB 5029, Moor Plantation, Ibadan, Nigeria; 2 Department of Agricultural and Mechanical Engineering, College of Engineering and Environmental Studies, Olabisi Onabanjo University, Ibogun, Ogun State, Nigeria.
Corresponding author e-mail: jideadelekan@yahoo.comABSTRACT
Objective: To determine the concentrations of heavy metals in soil and groundwater at municipal refuse dumps in Ibadan, Nigeria, and make recommendations to improve refuse management.
Methodology and results: Soil and groundwater samples from 7 municipal refuse dumps and a green uncontaminated control site at the Institute of Agricultural Research and Training in Ibadan, Nigeria were analyzed for Cadmium (Cd), Cobalt (Co), Lead (Pb), Chromium (Cr) and Nickel (Ni). Soil samples were obtained in triplicates and at depths of 0-15, 15-30, 30-45 and 45-60cm. Water samples were obtained from dug wells at the dump sites. The values of Cd, Co, Pb, Ni and Cr in the dumpsites soil samples ranged from 0.75-16.30; 3.45-21.00; 45.00-624.50; 4.35-49.80 and 13.15-75.55mg/kg, respectively. Evidence of contamination of these soils by Cd, Pb, Ni and Cr was obvious when compared to the control site. Ni was below detection limit in all control samples while Pb and Cd were less than 0.05 and 0.002mg/kg, respectively. Cr ranged from 6.25-19.75mg/kg. The range obtained for Co at the dumpsites was comparable to that of the control soil which was 7.22-28.15mg/kg. Compared to established limits set for soils in some countries, the values measured in this study were higher, particularly for Pb. Co conformed to the only established limit cited in Austria. Values measured in the groundwater samples were lower than the limits set by WHO for drinking water, except Cd which was detected in 3 of the samples at a concentration close to the WHO limit.
Conclusion and application of findings: This study found that there is an ongoing build up of heavy metals in soil at the waste dumps studied and concentrations were already higher than established limits for some metals. The recommendations of the study include formulation and enforcement of a directive to prevent any form of farming on the dumpsites, relocation of the dumpsites out of the city and the enforcement of other environmental protection regulations to stop the ongoing buildup of these metals on those locations. Findings from this study will be of immense help to researchers and environmental regulators in developing countries.
Key words: Soil, groundwater, heavy metals, Nigeria
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