Impact of forest fires on polycyclic aromatic hydrocarbon concentrations and stable carbon isotope compositions in burnt soils from tropical forest, Nigeria

• Main Authors: Oluwabamise L. Faboya, Samuel O. Sojinu, Bola J. Oguntuase, Oluwadayo O. Sonibare
• Format: Article
• Language: English
• Published: Elsevier 2020-07-01
• Series: Scientific African
• Subjects: Forest fire; Fired soils; PAHs distribution; Carbon isotope compositions
• Online Access: http://www.sciencedirect.com/science/article/pii/S2468227620300697

Forest fire has been fingered as an important source of polycyclic aromatic hydrocarbons (PAHs) in the environment. One of the major causes of global warming is expected increase in wildfire frequencies and intensities. Studying the quantity and speciation of PAHs emanating from different burn intensities has significant implications for environmental quality and global soil dynamics. The levels and distribution profiles of polycyclic aromatic hydrocarbons (PAHs) in soils from a tropical rain forest in Nigeria that has witnessed series of seasonal wild fire were investigated using gas chromatography–mass spectrometry (GC–MS). The concentrations of PAHs in the fire affected soils ranged from 104.36 to 1868.93 ng/g (average: 713.36 ng/g). The average value of PAHs concentrations in the soil samples were higher than the values reported in similar soils from other region of the world. The soils samples composed predominantly of higher amount of light PAHs with two to three rings, suggesting direct emissions from biomass burning. Source diagnostic indices established that the PAHs were mainly from combustion sources. The soil samples showed enriched δ13C (−17.7 to −20.8‰) as compared to control soil samples (−25.6 to −26.2‰). Given the high erodibility of wildfire ash owing to its physico-chemical properties, the emerging PAHs from them can be easily transported to rivers and reservoirs where they could impact the aquatic food chain and drinking water sources.