Heavy metals pollution at municipal solid waste dumpsites in Kano and Kaduna states in Nigeria

Soil samples collected from two major dumpsites each in Kano and Kaduna states were investigated for heavy metals pollution. Each of the dumpsite was divided into north, south, east and west. Four soil samples were collected at a depth of 0-15 cm from each part and pooled to form a composite sample. Soil samples from reserve areas within the same geographical locations as the dumpsites were collected as control. Acid-extractable cadmium (Cd), chromium (Cr), nickel (Ni) and lead (Pb) were determined using 2 M nitric acid solution and atomic absorption spectroscopy. The ranges of Cd, Cr, Ni and Pb levels for all the dumpsites were 0.30 49.8, 5.76 139, 0.39 19.1 and 42.6 9662 mg/kg, respectively. Kano dumpsite 2 was found to pollute most with Cd, Cr and Pb in 50-100 % soil samples collected having concentrations higher than the threshold limits set by regulatory body. Paper and food scraps showed higher percentages in both Kano and Kaduna dumpsites. The soil was high is sand for all the dumpsites implying high leaching potentials of the heavy metals pollutants.