Environmental Impact of Metal and Metal Containing Wastes on the Cadmium and Lead Contents of Leachate and Soils of the Aba-Eku Dumpsite, Ibadan, Nigeria

Abstract

Aims: This study evaluated the impact of metal and metal containing wastes (plastics, glass, miscellaneous and fines) on cadmium and lead contents in soil and leachate and the inter-relationships among the various waste categories dumped on the site, using Principal Component Analysis (PCA). Study Design: Cadmium and lead contents in top soils of Sub-site WDA (Waste Dump Area) and LLA (Leachate Lagoon Area) (wdatscd, wdatspb; llatscd, llatspb); at 15-30cm depth i.e. sub-soil 1 (wdass1cd, wdass1pb; llass1cd, llass1pb); at 31-60cm depth i.e. sub soil 2 (wdass2cd, wdass2pb) and attenuated leachate cadmium and lead (alcd, alpb) were used along with the various waste fractions for PCA analysis. Place and Duration of Study: Department of Zoology, University of Ibadan, Ibadan, Nigeria. January 2003-September 2004; Institute of Applied Ecology, Shenyang, China. May 2006-May 2007. Methodology: Solid waste, leachate and soil were collected from two sub-sites (WDA and LLA and comparative control 600m away) from the Aba-Eku landfill site, Ibadan, Nigeria in February, April, August, October and December 2003; as well as in June 2004. They were analyzed for cadmium and lead contents using Inductively Coupled Plasma Spectroscopy after Hydrofluoric-Perchloric-Nitric acid digestion. Data obtained were subjected to PCA analysis. Results: The tendency of the various metal containing waste categories to cluster with lead and cadmium in leachate and soil on more than one principal component is suggestive of the degree of input to lead and cadmium contamination in soil and leachate. Metals contributed the highest (cluster on all three PCs) followed by plastics and the miscellaneous fraction (cluster on two PCs), glass and the fines fraction (cluster on one PC). Results also revealed two main clusters of biodegradable (Food wastes, miscellaneous and fines or soil) and non-biodegradable wastes (Glass/ceramics and metals). Conclusion: Based on these results, increased recovery and recycling of the metal, plastics and glass/ceramics waste fractions in particular, are suggested.