Concentration Assessment And Source Evaluation of Polycyclic Aromatic Hydrocarbons (PAHs) In Soil And Crops of The Agro-Industrial Tobacco Production Area of Igboho, Nigeria

Abstract The contribution of tobacco smoking and cigarette butts to global environmental pollution has been given significant attention. However, little is known about tobacco-related agricultural activities on environmental pollution by polycyclic aromatic hydrocarbons (PAHs). In this study, the spatial distributions, composition, source, and toxicity potential of polycyclic aromatic hydrocarbons (PAHs) in soil and food crops within the vicinity of the agro-industrial tobacco production area of Igboho, Nigeria was investigated. Soil and food crop (Zea mays, Dioscorea alata, and Manihot esculenta) samples collected from the tobacco curing site and the surrounded farmlands were analyzed for the PAHs concentrations. The identification and quantification of priority PAHs in the samples were carried out using a gas chromatograph equipped with a flame-ionization detector. The total concentration of the priority PAHs in the soil ranged between 136.70 ng.g-1 to 889.30 ng.g-1. The total concentration of carcinogenic PAHs ranged from 6.07 ng.g-1 to 321.04 ng.g-1, and the total concentration of toxic PAHs ranged from 6.27 ng.g-1 to 254.37 ng.g-1. The PAHs level was highest in crops from farmlands closest to the tobacco curing site. The distribution of PAHs ring size is in the order of 6-rings ˃ 4-rings ˃5-rings ˃ 3-rings ˃ 2, and the diagnostic indices showed that the sources of PAHs in the samples were mainly pyrogenic and associated with tobacco curing activities in the area.