Impacts of heavy duty truck emissions on the vertical distributions of soil polycyclic aromatic hydrocarbons at a big haulage vehicle park

Abstract

Nigeria relies heavily on heavy duty haulage vehicles to convey commodities from one end of the nation to the other, owing to the decades-long collapse of the rail transportation infrastructure. This is resulting in settings with very high concentrations of the trucks on the country's key roads. Diesel engine exhausts have long been recognized to be detrimental to human health. The concentrations of polycyclic aromatic hydrocarbons (PAHs) in the top and bottom soil samples from an extensive haulage vehicle stop located at Ogere, a roadside town along the ever busy Lagos-Ibadan highway were investigated. Soil samples taken at depths of 0–15 cm and 15–30 cm were subjected gas-chromatographic/mass spectrometer analysis. The Ʃ priority PAHs in the top and bottom soils at four sampling locations ranged between 16.4 and 32.0 mg/kg and 18.6–26.6 mg/kg respectively. The corresponding Ʃ carcinogenic PAHs for top and bottom soils ranged between 9.2 and 17.4 mg/kg and 8.7–12.0 mg/kg respectively. The concentrations of PAHs obtained in this study clearly exceeded the permissible limits set for soil PAHs in most developed nations of the world. The diagnostic ratio attributed the observed PAHs to diesel emissions. The study concluded that the emissions from the trucks at the haulage vehicle stop have tremendous impact on the soil PAH concentrations.