Elemental characterization of urban particulates at receptor locations in Abuja, north-central Nigeria

Abstract

The rising population and increasing urban infrastructures of Abuja have led to increased pressure on the urban environment. Two decades after putting the city of Abuja to use, there is yet no information on the air quality status of the city. Hence, this study was conducted in order to assess the mass concentration and elemental characterization of airborne particulate matter in Abuja, north-central Nigeria. Sampling of PM2.5: aerodynamic diameter ≤2.5 μm and PM10: aerodynamic diameter ≤10 μm were carried out in five urban sites within the city from April, 2009 to May, 2010. "Gent" stacked filter unit sampler equipped with a double stage filters in series was employed for sample collection. Charged helium (4He+) Particle Induced X-ray Emission technique of 2500 keV particle energy and Genie 2000 software were used for spectra acquisition while elemental characterization was achieved using Gupixwin software in order to determine the concentration of eighteen elements (Si, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Sn, Ba, Ta and Pb). Mass concentrations range between 7–86 μg m−3 and 22–343 μg m−3 for PM2.5 and PM10 respectively. Crustal elements (Si, Ca, and Fe) were found to be predominant in PM10 than in PM2.5 fraction with very high values. Positive correlation r > 0.90 and r > 0.53 to 0.90 exist between metals (V, Co, Ni, Cd, Zn and Pb). PM2.5/PM10 mass ratios were well within the range specified by WHO for developing urban scenario.