Polynuclear Aromatic Hydrocarbon Concentrations in Road Dust and Soil Samples Collected in the United Kingdom and Pakistan

Abstract

Concentrations of polycyclic aromatic hydrocarbon (PAH) were measured in samples of soils, surface and road dusts and air from various locations in Birmingham (UK) and Lahore (Pakistan). Urban surface and road dusts were observed to decrease in PAH concentration with increasing distance from major roadways. PAH concentrations in soils in Birmingham were found to be comparable with other urban areas throughout the UK. A high correlation was found between airborne particulate matter and soil concentrations in Birmingham, which suggests that atmospheric deposition is the dominant source of PAHs in soils. A high correlation was also found between PAH concentrations in soil and road tunnel dust; this illustrates the impact of vehicle emissions as the major source of PAHs in urban areas. The high correlation between PAH species profiles distributed through soils in the UK provides evidence for either long range dispersion and deposition of particles, or similar local emission sources in all sampled areas. PAH levels in soils from Lahore were considerably lower than those collected in Birmingham despite far higher atmospheric concentrations. This is most likely to be due to Pakistan's climate enhancing the effects of photo-oxidation and volatilisation. A high correlation was found between PAHs in airborne particles and soils in Lahore.