Concentrations, origin, and human health risk of polycyclic aromatic hydrocarbons in anthropogenic impacted soils of the Niger Delta, Nigeria

Abstract

The background occurrence, sources, and human health risk of 16-USEPA priority polycyclic aromatic hydrocarbons (16-PAHs) in soils from anthropogenic environments of the Niger Delta, Nigeria were investigated. After extraction with dichloromethane/n-hexane by ultrasonication and clean-up in silica gel/alumina packed column, gas chromatography-mass spectrometer (GC-MS) was used for the determination of the 16-PAHs concentration. The mean total concentration of the 16-PAHs ranged from 115 to 3920 µg/kg. The mean concentrations of the total ∑16 PAHs followed the order deep soil > top soil > bottom soil > sub soil. The ring-PAHs distribution showed an irregular trend in the soil profiles, and the average compositional pattern of the ring-PAHs is in the order of 5-ring > 4-ring > 3-ring > 2-ring > 6-ring. Depending on the exposure concentrations and duration, the total cancer risk for adults and infants may increase the health risks to workers and inhabitants. The principal sources of PAHs were attributed to anthropogenic activities associated with traffic and non-traffic emissions and spills from petroleum fractions, solvents, and crankcase oil in the solid waste, abattoir, fuel station, plastic scrap, and auto-mechanic sites.