Speaker
Description
Heavy metals are environmental pollutants with high toxicity, persistent occurrence, and can
bioaccumulate. Rapid industrialization and urbanization are increasing the contamination of heavy
metals from activities such as e-waste recycling and improper waste disposal, leading to a severe
impact on human health. This study aimed to identify the pollution sources of heavy metals and
assess the risks they pose to humans. The study area is an abandoned waste site that has been
encroached upon for activities such as e-waste recycling, residential, and commercial activities.
Concentration of ten heavy metals: As, Cd, Cr, Co, Cu, Fe, Mn, Ni, Pb, and Zn were measured in
soil using an Inductively Coupled Atomic Emission Spectrometer. The mean concentrations for
metals obtained followed the order Fe (315.8) > Cu (22.1) > Zn (16.3) > Mn (4.72) >Pb (2.02) >
Cr (1.61) > Co (0.17) >Ni (0.35) > Cd (0.04) > As (>0.001) in (mg/kg). The findings confirmed
significant enrichment of heavy metals at both recycling, commercial, and residential sites, with
levels exceeding international soil guidelines, making the area a contaminated site for humans.
The mean pH, electrical conductivity, and organic matter content were 9.14, 272 μS/cm, and
3.19%, respectively. X-ray diffraction for mineral composition analysis revealed that the soil was
dominated by quartz mineral, followed by albite and kaolinite mineral, making metals mobile and
bioavailable in the soil. Principal component and cluster analysis, risk assessments, and spatial
maps were employed to identify pollution sources and quantify ecological, human health, and
metal concentration hotspots, respectively. The results from the pollution indices suggested that
activities from commercial and e-waste sites introduce heavy metals into the soil ecosystem. The
estimated hazard index for adults and children through the exposure pathways (ingestion,
inhalation, and dermal) indicates that children are susceptible to a non-carcinogenic and
carcinogenic risk. The spatial maps also depicted a higher concentration of metals at the e-waste
site and the residential area, showing the hotspot zone that needs attention. This revelation would
enable governmental institutions to enact laws and the existing policy framework to regulate e
waste activities, and plans to tackle urbanization.
Keywords: heavy metals, pollution indices, carcinogenic, non-carcinogenic, and hotspot