Tijani Saliu¹, Oluyemi E. Ayodele^1,, Olabanji I. Oluremi¹, Adeniji A. Oluwole¹

Ambient concentrations of size-segregated fractions of PM_2.5 and PM_2.5-10 were investigated for chemical compositions and pollution sources at two functional receptor sites (industrial and residential areas) in the metropolitan city of Ibadan, Nigeria between March 2014 and February, 2015. Seventy four fractions (37 each) were collected on quartz filter media using a low volume Gent sampler equipped with double-staged stacked filter unit. Elemental characterizations of both fractions were carried out using Particle Induced X-ray Emission (PIXE) technique in an external ion beam analysis set-up. Elements such as K, Na, P, S and Cl which were evidences of burning activities correlated well in the PM_2.5, while the relationship observed between Al, Si, K, Ca and Fe suggested crustal material source for the elements in the PM_10-2.5. Results of the seasalt estimation of some naturally occurring elements (Na, K, Ca and S) in the ambient air suggested their sources in Ibadan as either of crustal or anthropogenic. Source apportionment study with Positive Matrix Fractionalisation (PMF) receptor model identified five sources with stable profiles in PM_2.5; tail pipe/industrial emissions (48.5%), suspended road dust (13.1%), ferrous metal smelting (34.6%), fine brake (0%), and vegetative/biomass burning (3.8%). Six were in PM_2.5-10. They are petroleum products combustion plus smelting (9.3%), biomass burning (5.2%), exhaust and non-exhaust mobile (0%), airborne/re-suspended soil (23.4%), fuel oil combustion (24.5%), and municipal incineration plus solid waste combustion (37.6%). This study resolved high values for anthropogenic vehicular emission and solid waste burning, thus call for routine monitoring by regulatory agencies and stringent abatement options to control the possible untold hazards on health and environment.

ambient, fractions, PIXE, source apportionment