Assessment of Heavy Metals Pollution in Dumpsites in Ilorin Metropolis

Abstract

Speciation and distribution of heavy metals in soil controls the degree to which metals and their compounds are mobile, extractable, and plant available. Eight strategically located dumpsites in Ilorin metropolis (an averagely growing city and a state capital) were chosen for dumpsites-soil characteristics study. Both the estimated total and potentially available metals were studied using EPA 1311 and Tessier's et al methods respectively. It was observed that the groundwater is vulnerable to contamination as no treated basement to adsorb toxic metals was provided for in the sites. About 70% of Mn, Fe, Zn, Cd and Pb were found in the exchangeable bound to carbonate and bound to iron/manganese oxide fractions. These fractions represent the mobile and lethal portion of the total metals to the ecosystem. The metal enrichment factor revealed that Zn, Cd and Pb were of anthropogenic source while Fe is of natural and anthropogenic sources. The dumpsites in Ilorin, therefore pose negative consequences on the soil and groundwater environment. Introduction he gradual increasing population and the proliferation of basic industrial processes particularly in major cities of the world has led to emergency of civilization that have greater impact on the environment. The industrial revolution gave birth to environmental pollution and the large volume of industrial chemical discharges has added to the growing load of untreated domestic waste. The disposal of domestic, commercial and industrial garbage in the world is a problem that continues to grow with human civilisation and no method so far is completely safe. Experience has shown that all forms of waste disposal have negative consequences on the environment, public health, and local economies. Dumpsite is an old traditional method of waste disposal similar to landfill method of waste management. Dumpsites are often established in disused quarries, mining or excavated pits away from residential areas. Designated government agency, corporate bodies and some individuals collect wastes routinely into these dumpsites. Here in Nigeria and particularly in Ilorin, modern landfill facilities are not found in these dumpsites; consequently sorting-out of wastes into degradable, non-degradable and recyclable precious materials cannot be achieved. Poor management of dumpsites could create a number of adverse environmental impacts, including wind-blow litter, attraction of mice and pollutants such as leachate, which can pollute underground soil bed, and / or aquifer. Landfill gas mostly composed of methane and carbon dioxide are produced through biodegradation of such waste.