Chemical Composition and Source Identification of Fine Particulate Matter (PM2.5) in Two Contrastive Areas of Lagos Megacity, Southern Nigeria

Abstract

Industrial activities contribute immensely to high emission rates of particulate matter (PM) and other pollutants into the ambient air. The siting of industrial plants close to a populated area can have adverse implications on human health and the environment at large. The industrialization and urbanization of Lagos megacity, has led to increased pressure on the city especially on air quality. The chemical complexity of airborne particles makes it imperative to consider their composition and sources of emission. This paper deals with the assessment of particulate matter pollution in an industrial and a non industrial area of Lagos State. Samples of PM2.5 were collected with an air sampler (Airmetric model 5.0) between November 2018 and April 2019. Elemental analysis was carried out using Atomic Absorption Spectroscopy (AAS). Particulate mass loading obtained was in the range of 51.28 to 190.48 μg/m 3 and 41.67 to 88.89 μg/m 3 in the industrial and control area respectively. Enrichment factor (EF) and principal component Analysis (PCA) were used for source identification. The EF analysis revealed that; Pb, Cd, Cu, Ni and Na were severely enriched while K and Ca were moderately enriched in virtually all the sites. The result of the PCA showed that the major sources of these elements were industrial/vehicular emission, marine, road dust, crustal dust and incineration.