Elemental Characterization and Source Identification of Fine Particulate Matter (PM2.5) in an Industrial Area of Lagos State, Nigeria

Abstract

Fine particles (PM2.5) are mainly generated by combustion processes including emissions from motor vehicles, combustion of fossil fuel for power generation and large industrial processes such as ore and metal smelting. They may also include natural emissions such as fine windblown soils, sea spray and smoke from biomass burning. Based on the field study conducted, the concentrations of PM2.5 at the different locations vary with respect to anthropogenic activities. The PM2.5 levels obtained ranged from 14.00 to 32.67 µg/m3 during wet season and 18.67 to 34.67 µg/m3 during dry season. Trace elements especially heavy metals are significant components of PM2.5 in industrial environments. The heavy metals are of particular concern due to their persistence in the environmental media and their human toxicity. The particulate matter concentration was obtained using Casella cel-712 microdust pro-real time dust monitor and flame atomic absorption spectrophotometer was used to determine the elemental content. The Enrichment Factor (EF) analysis showed very high enrichment for the elements; Pb, Cd, Cr, Cu, Ni, Na, K, Mg, and Ca in the fine fraction (PM2.5). The Principal Component Analysis explained three common contributing sources of fine particulates (PM2.5) such as entrained soil, sea salt and combustion. Spatial variation was performed and mean concentration of some of the elements in the various locations showed significant difference at P<0.05. Correlation matrix was also determined and some of the elements were strongly correlated while some were not. Seasonal variation for the elemental concentration also revealed that the mean values for some of the elements were statistically significant at P<0.05 for both seasons.