SOURCE APPORTIONMENT OF POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) IN SOILS WITHIN HOT MIX ASPHALT (HMA) PLANT VICINITIES

Abstract

The composition of polycyclic aromatic hydrocarbons (PAHs) in soils within the vicinities of hot mix asphalt (HMA) production plants in Port Harcourt, Nigeria, was investigated. Soil samples were collected at an increasing distance of 10 m from two HMA plants, at surface (0-15 cm) and subsurface (15-30 cm) depths during dry and wet seasons. PAHs distribution in the soil samples were analyzed with gas chromatography equipped with flame ionization detector (GC-FID). PAHs concentrations during the dry season for HMA plant A ranged from 8.20 - 449.00 mg/kg and 5.66 - 271.00 mg/kg for surface and subsurface soils respectively. The concentrations in HMA plant B ranged from 219.00 - 378.00 mg/kg and 27.00 - 264.00 mg/kg for surface and subsurface soils respectively. The PAHs concentration in the wet season for HMA plant  A ranged from 10.30 - 71.90 mg/kg and 4.11 - 38.50 mg/kg for surface and subsurface soils respectively while that of  HMA plant B was between 28.70 – 106.00 mg/kg and 8.73 – 37.00 mg/kg for surface and subsurface soils respectively. PAH diagnostic ratios of Anthracene/Phenanthrene, Fluoranthene/Pyrene and Benzo[a]Anthracene/Chrysene indicated the dominant sources of PAHs within the HMA plant vicinities were pyrogenic with variable input from petrogenic sources due to petroleum fuels and oils from vehicle traffics, vehicle repair/maintenance in the plant area and runoffs during the wet season. Multivariate analysis of PAHs diagnostic ratios showed significant correlation (³ 72.04%) in soil samples from both HMA plant vicinities and revealed similar PAHs profiles dominated by pyrogenic PAHs.