Concentrations of polycyclic aromatic hydrocarbons in soils of a mangrove forest affected by forest fire

Abstract

Surface soils affected by forest fires from Igbanko mangrove forest in Nigeria were analyzed for 16 EPA priority polycyclic aromatic hydrocarbons (PAHs) using gas chromatography–mass spectrometry (GC–MS). The total PAHs concentrations in the soils ranged from 63 to 188 µg kg−1 dry weight (average: 108 µg kg−1). The three predominant PAHs in the soils were naphthalene (Na), fluoranthene (Flu), and benzo(b)fluoranthene (BbF). Compared to the control sample (19 µg kg−1), elevated PAHs concentrations were observed in the soils, an indication of some level of PAHs contamination. PAHs source diagnostic ratios of Flu/(Flu + Pyr) and Ant/(Ant + Phe) indicated that the PAHs have a pyrogenic origin which may have resulted from combustion of grass, wood, or coal. An assessment based on Canadian soil quality guidelines indicated that the studied locations do not pose any serious adverse risk on human health.