Soil contamination with heavy metals release from e-waste management activities in Nigeria

This study assessed the levels of heavy metals contamination of soil of four different e-waste management activity sites in Lagos, Nigeria where open burning, dismantling/disposal, stockpiling and dismantling/stockpiling of e-waste were ongoing. Soil samples were collected seasonally during dry and wet seasons, for two years from each site. The samples were analysed for selected metals using atomic absorption spectrometer after aqua regia digestion. The soil at the open burning site was observed with the highest concentrations of all the metals with mean values (mg/kg) of 24.8 (Cd), 69.3 (Cr), 108 (Ni), 4,380 (Zn), 15,200 (Pb), 41,700 (Cu) for the wet season. The extreme values of contamination factor (> 6) obtained for the open burning site indicated very strong contamination by Pb and Cu. Sequential extraction showed higher proportions of Zn, Pb and Cu in the non-residual soil fractions with mobility factors suggestive of high mobility and bioavailability of the metals.