Ecotoxicity of heavy metals in soil around long-term e-waste recycling sites in Tema and Ashaiman areas of Ghana

Abstract

Abstract The effect of e-waste recycling activities on soil quality was assessed for four e-waste sites in Ghana. Samples of top- and sub-soil were collected from dismantling and burning sections and prevalence and distribution of selected metals were determined using Atomic Absorption Spectroscopy. The concentrations of the metals analysed were above the background concentrations except Cd, which was detected at the same level as the background levels. Levels of Cu and Pb increased with increasing soil depth. Levels of Cd, Zn, As, and Ni decreased with increasing soil depth. Hg levels showed no recognizable trend in its distribution relative to soil depth. The pollution indices evaluated revealed deterioration of the soil quality at the e-waste sites. Geo-accumulation indices suggest that the soil is very highly polluted with Pb, highly polluted with Cu, and moderately polluted with As, Hg, Cd, and Zn. The enrichment factor values indicate that soil from the studied sites was very highly enriched with Pb (i.e., EF of 9.60 to 63.14; median being 28.51) and significantly enriched with Cu and Hg (i.e., EF of 3.09 to 21.86; median 7.72 for Cu and EF of 1.48 to 25.5; median 10.57 for Hg). The contamination factor analysis revealed very high contamination of soils with Pb. The metals Cu, Zn, As, Ni, Cd, and Hg exhibited moderate to considerable contamination. This study is part of the continuous effort to assist policymakers with scientific information needed to influence policy decisions on environmental management.