Occurrence and sources of aliphatic hydrocarbons in soils within the vicinity of hot mix asphalt plants in Obigbo and Igwuruta Areas of Rivers State, Nigeria

Abstract

This study investigated the occurrence and sources of aliphatic hydrocarbons (AHCs) in soils within the vicinity of hot mix asphalt (HMA) plants. Soil samples were collected from two HMA plants and analysed with gas chromatography - flame ionisation detector (GC-FID). Sample collection was from both surface (0-15 cm) and subsurface (15-30 cm) soils at an increasing distance of 10 m from the HMA plants while the control samples at both depths were collected at 1 km away from the plants. The AHCs concentration (nC9-nC38) in soils from both HMA Plants ranged from 8.16 - 433.04 mg/kg and 5.91-177.83 mg/kg for surface and  subsurface soils respectively while the concentration in the control samples ranged from 5.97 - 23.95 mg/kg and 2.52 - 13.31 for surface and subsurface soil respectively. The sources of the AHCs were determined using isoprenoid ratios, carbon preference index (CPI) and maximum carbon chain (Cmax). The isoprenoid ratios and CPI values of the samples closer (< 20 m) to the HMA plants were < 1 and < 2 respectively indicating anthropogenic inputs. Samples > 20 m from the HMA plants showed mixture of both anthropogenic and biogenic sources.

Keywords: Asphalt Plants; Soil; Aliphatic hydrocarbons; Pristane; Phytane.