Ambient Air Emission Profiles of Polycyclic Aromatic Hydrocarbons around a Typical University Power House in Nigeria

Abstract

The level of electricity generation in Nigeria is presently grossly inadequate. Consequently, the productive sectors of the economy do not presently enjoy an uninterrupted supply of electrical energy from the country's national grid and the downtime is in most cases too much. Using diesel-fueled electric power generators has become an attractive alternative to meet the shortfall in the energy supply gap. In this study, the levels of polycyclic aromatic hydrocarbons in the vicinity of the diesel-fueled electric power generators operated by Osun State University, Osogbo, Nigeria were investigated with a view to ascertain the priority levels and carcinogenic PAHs. Since the generators were recently relocated, the study covered the old and the new sites. Polyurethane foam passive samplers were deployed at the old and new sites for 28 days. They were subjected to sohxlet extraction using dichloromethane to extract the PAHs from the PUFs. Cleaning up and elution were done with 5 g of silica gel column and 40 mL 1:1, DCM:Hexane followed by concentration in a rotary evaporator using a stream of nitrogen. Gas chromatographymass spectrometry (GC-MS) analysis was used to determine of PAHs. The Ʃ priority PAHs around the old and new sites were in the range of 4.43-5.44 μg/m 3 and 4.47-5.35 μg/m 3 , respectively. The Ʃ carcinogenic PAHs at the sites were 2.98 -3.42 μg/m 3 and 3.35 -4.17 μg/m 3 . Higher molecular weight PAHs dominated the measured PAHs with benzo[a]pyrene being the most significant contributor to the computed total toxicity equivalence (TTEQ). The PAHs diagnostic ratios affirmed that the measured PAHs were from dieselrelated sources. The levels of the PAHs obtained in this study are above permissible limits specified for ambient air; hence, the air around the power plant is considered unsafe.