Assessment of Automobile Workshops and Heavy Metal Pollution in a Typical Urban Environment in Sub-Saharan Africa
Automobile workshops (AW) are pervasive across many cities in Sub-Saharan Africa (SSA), often existing close to residential and commercial land use. Activities within these enterprises use and release many heavy metals with serious consequences for human health. This study examined soil and water samples to quantify the load of heavy metals within these enterprises. In soil, means of 3.073, 91.033 and 5.630 mg kg-1 were observed for Hg, Pb and Cd, respectively, and only Hg mean was below the benchmark. The means of 0.063, 0.114 and 0.131 mg/l were observed for water samples across the AW. On average, the soil of the AWs had about 99, 68 and 34% more Hg, Cd and Pb, respectively, compared to the background samples. Similarly, water samples around the workshops were also 82, 89 and 93% higher in Hg, Pb and Cd, respectively. Nemerow Pollution Index (NPI) shows that all the water samples from the workshop site are heavily polluted while 88% of the soil is between slightly polluted and heavily polluted. 55% of the background samples (water) are heavily polluted, while 30% of soil samples fall within the safety domain class of NPI. This shows that AWs pose a significant risk to human health, and there is an indication that increased concentration of heavy metals in soil could be linked to the content in the groundwater. There is a need to clearly identify and quantify the pool of heavy metals in soil influencing the level of heavy metals in the groundwater in order to design effective control measures.