Potential groundwater contamination with toxic metals around refuse dumps in some parts of Lagos metropolis, Nigeria

Abstract

Industrial evolution in developing countries, most especially Nigeria in the last century, has resulted in geometrical increase in waste generation compared to the arithmetic progress in management methods, thereby creating the problem of effective waste management and disposal. Wastes generated from industries have become a major source of pollution of groundwater when contaminants become leached into the groundwater. Water samples collected from 44 wells within 25 m radius from six refuse dump sites within Lagos metropolis during the months of February and September, 2006 were analyzed for nine heavy metals, namely, Lead (Pb), Chromium (Cr), Zinc (Zn), Cadmium (Cd), Nickel (Ni), Cobalt (Co), Iron (Fe), Manganese (Mn) and Copper (Cu), using AAS according to standard procedures. The results showed elevated concentrations of most heavy metals determined. Pb, Cd, Mn and Fe have their concentrations clearly above the World Health Organization (WHO) and Standard Organization of Nigeria (SON) recommended limit for potable water, showing contamination from the refuse dumps, while the concentrations of Cu and Zn were below toxic levels for drinking water in all the samples. Co was not detected in most of the samples, while the concentration of Ni detected was also quite low except at one of the sites where it was above the recommended level.