Evaluation of Pollution of Soils and Particulate Matter Around Metal Recycling Factories in Southwestern Nigeria

BACKGROUND. Metal recycling factories (MRFs) have developed rapidly in Nigeria as recycling policies have been increasingly embraced. These MRFs are point sources for introducing potentially toxic elements (PTEs) into environmental media. OBJECTIVES. The aim of this study was to determine the constituents (elemental and mineralogy) of the wastes (slag and particulate matter, (PM)) and soils around the MRFs and to determine the level of pollution within the area. METHODS. Sixty samples (30 slag samples, 15 soil samples and 15 PM samples) were collected for this study. The soils, slag and PM samples were analyzed for elemental constituents using inductively coupled plasma optical emission spectrometry. Mineralogy of the PM was determined using scanning electron microscope-energy dispersive spectroscopy (SEM-EDS), and soil mineralogy was determined by an X-ray diffractometer (XRD). RESULTS. The results of the soil analyses revealed the following concentrations for the selected metals in mg/kg include lead (Pb) (21.0–2399.0), zinc (Zn) (56.0–4188.0), copper (Cu) (10.0–1470.0), nickel (Ni) (6.0–215.0), chromium (Cr) (921.0–1737.0) and cadmium (Cd) (below detectable limit (Bdl)-18.1). For the slags the results were Pb (68.0–.333.0), Zn (1364.0–3062), Cu (119.0–1470.0), Ni (12.0–675.0), Cr (297–1737) and Cd (Bdl-15.8). The results in μg/g for the metal analysis in PM were Pb (4.6–160.0), Zn (18.0–471.0), Cu (2.5–11.0), Ni (0.8–4.2), and Cr (2.5–11.0), while Cd was undetected. The slags are currently utilized for filling the foundations of buildings and roads, providing additional pathways for the introduction of PTEs into the environment from the suspended materials generated from mechanical breakdown of the slags. CONCLUSIONS. The MRFs were found to have impacted the quality of environmental media through the introduction of PTEs, impairing soil quality, in addition to PM, which can have detrimental health consequences. Further studies on the health implications of these pollutants and their impacts on human health are needed. COMPETING INTERESTS. The authors declare no competing financial interests