Receptor modeling of atmospheric aerosols in Federal Capital Territory (FCT), Nigeria

Abstract

The air quality of Abuja urban air shed was investigated with a view to establishing sources of pollution in the city. Forty samples of coarse atmospheric particulates (PM_2.5-10) were collected at different categories of spatially distributed receptor locations; high (High-dra) and low (Low-dra) density residential, commercial (Comm-1&2) and institutional (Institute) areas with a sequential double stage sampler for eight non-sequential months. Positive matrix factorization (PMF) receptor model was used for source apportionment of aerosols' inorganic chemical species characterized using an ion beam analysis (IBA) technique with incident particle energy of 2.5 MeV. A data matrix of 40 by 20 species (Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Cd, Sn, Ta, Pb and PM) was used to run the model. Mean mass concentration in High-dra, Low-dra,  Comm-1, Comm-2 and Institute were 21 μg/m³ (range, 10 - 49 μg/m³ ), 66 μg/m³ (range, 7 - 287 μg/m³ ), 42 μg/m³ (range, 7 – 91 μg/m³ ), 63 μg/m³ (range, 10 - 183 μg/m³ ), and 60 μg/m³ (range, 4 – 167 μg/m³ ) respectively. Three distinct sources; Crustal 4.2%, Biomass/Fuel burning 8.8%, Vehicular 87.0% were identified and apportioned by the PMF model. On site measured concentrations and model predicted concentrations of PM in this study were related by equation y = (0.59 ± 0.07)x + (14.73 ± 5.38) with a good coefficient of determination r³ = 0.67. The study concluded that traffic-related pollution posed a great hazard to the atmospheric environment of Abuja and likewise on human receptors in the study areas.

Keywords: PM_2.5-10 , PIXE, Trace Elements, Receptor Model