Source Apportionment of Heavy Metals and Ionic Species in Road Dust in the Vicinity of University of Lagos, Lagos State, Nigeria
The increasing levels of heavy metals and ionic species in road dust around the University of Lagos and its surrounding environments, which are believed to exceed recommended environmental standards, emphasizes the need for the present study. This study investigates the concentrations of selected heavy metals ((Zn, Pb,Cu,, Ni, Cd) and ionic species(SO₄²⁻, NO₃⁻, Cl⁻, CO₃²⁻,C₂O₄²⁻) in road dust samples collected around the University of Lagos, Akoka, Lagos State, Nigeria. 44, road dust samples were collected between January and June 2025 across eleven sampling locations, with sampling conducted four times monthly. Dust samples were swept using a hand brush into plastic containers and transferred into sterile vials. The samples were sieved through a 75-µm stainless steel mesh, weighed, and digested using nitric acid (HNO₃) and sulphuric acid (H₂SO₄). Heavy metal concentrations were analyzed using inductively coupled plasma - optical emission spectrometry (ICP - OES), while ionic species were determined using standard analytical procedures. Zinc (Zn) - (1710.86 mg/kg) recorded the highest heavy metal concentration while Cadmium (Cd)-(48.73 mg/kg) had the lowest concentration. Sulphate (SO₄²⁻) - (1266.62 mg/kg), was the most abundant ionic species while oxalate (C₂O₄²⁻) -(116.05 mg/kg) recorded the lowest value. Principal Component Analysis (PCA) identified three principal components (PC1, PC2, PC3)accounting for 90.78% of total variance, indicating anthropogenic sources such as vehicular emissions, lubricating oil, diesel fuel combustion, waste burning, tire and brake wear, chemical/ solvent usage, construction materials, microplastics, and organic activities. Heavy metal concentrations exceeded WHO/FAO, USEPA and NESREA permissible limits, posing environmental and public health concerns.