Elemental analyses and source apportionment of PM2.5 and PM2.5–10 aerosols from Nigerian urban cities

Abstract

PM2.5 and PM2.5–10 aerodynamic diameters (x ≤ 2.5 μm) and (2.5 ≥ x ≤ 10 μm) fractions in six Nigerian urban cities (Aba, Abuja, Lagos, Kano, Maiduguri and Port-Harcourt), were monitored using “Gent” stacked filter unit sampler in order to assess elemental concentrations and to perform source apportionment. Twenty-three elements; (Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br, Rb, Sr, Zr and Pb) were analysed with Ion beam analysis (IBA) based proton induced X-ray emission (PIXE) technique. In addition, enrichment factors (EF) and pollution indices (PI) calculations were performed on the elemental concentration data. Results indicated that the elemental concentration varied across the receptor sites with some elements higher than World Health Organization (WHO) guideline values. PM2.5–10 ranged from 9 to 45,243 ng m−3 (Aba), 1 to 281 ng m−3 (Abuja), 5 to 3,936 ng m−3 (Kano), 6 to 3,872 ng m−3 (Lagos), 6 to 19,106 ng m−3 (Maiduguri) and 4 to 7,962 ng m−3 (Port Harcourt) while PM2.5 ranged from 3 to 7,089 ng m−3 (Aba), 1 to 139 ng m−3, 2 to 480 ng m−3, 1 to 153 ng m−3, 1 to 427 ng m−3 and 1 to 1,051 ng m−3 (Port Harcourt). Principal Component Analysis resolved three (soil dust 50%; sea spray 22% and industrial 15%) and four components (soil dust 42%; biomass burning 24%; petroleum products combustion (15%) and industrial emission 5%) as PM2.5–10 and PM2.5 sources, respectively.