The impact of waste generated from automobile workshops on soils in Lagos Metropolis, South-Western Nigeria

The release of wastes generated from the activities at automobile workshops leads to heavy metals’ contamination of such soils which can be harmful to human health considering Sustainable Development Goal (SDG) number 3 of good health and well-being in mind. The study is aimed at investigating the physiochemical and heavy metal contamination of soils from three automobile workshops at Super, Jankara and Kola areas located at Alimosho, Ifako-Ijaiye and Agege Local Government areas of Lagos state. Twenty (20) samples were collected from residential houses near the automobile workshops, at 20–35 cm depth, and taken to the Federal Institute of Industrial Research (FIIRO) laboratory at Oshodi, Lagos. Electrical conductivity (EC), pH, temperature and total dissolved solids (TDS) with mean values 28.45 μs/cm, 6.5, 33.37 and 0.014 mg/L respectively were measured onsite using a 107 model pH metre. The samples were analysed for lead, magnesium, manganese, cadmium, arsenic, chromium and mercury using atomic absorption spectroscopy (Perkin Elmer Model Analyst 3000). Samples at the Super area gave the highest mean concentrations of lead (28.42 mg/kg), cadmium (0.65 mg/kg), arsenic (0.54 mg/kg) and chromium (11.70 mg/kg) while the highest mean concentrations of manganese (1.7282 mg/kg) and cadmium (0.4451 mg/kg) were high in the Kola area. The mean concentrations of metals in the soil samples were in the order Mn > Pb > Cr > Cd > As (AAS). The soil contamination degree was determined from the calculated values of the contamination factor and geo-accumulation index. The outcome of this research shows that heavy metals’ concentration in the soil existed within tolerable limits of all the standards compared with as summarised by the pollution load index. However, if the contamination continues, the concentration of the heavy metals will surpass the tolerable limits, and this could make it toxic to plants and humans.