Qualitative and Quantitative Assessment of Hydrocarbons in Soil Profiles of Auto-Mechanic Workshop: A Case Study of Akure City, Nigeria

Abstract

The total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbon (PAH) contents of soils collected at various depths (0–15 cm, 15–30 cm, and 30–45 cm) within automobile repair workshops in Akure metropolis, Nigeria were qualitatively and quantitatively assessed using gas chromatographic-mass spectrometer (GC-MS). Long chain n-alkanes (n C8–C32) were detected across all soils. TPH concentration (in mg/kg) for the top soils ranged from 85.42 ± 3.42 to123.76 ± 4.37. The middle had a concentration range of 63.45 ± 3.47–90. 80 ± 3.97 and a range of 12.59 ± 3.34–72.97 ± 3.97 recorded for the 30–45 cm depths measured. Similarly, the mean total PAHs concentrations in top, middle and bottom soils ranged from 0.14 to 0.21 mg/kg, 0.11 to 0.17 mg/kg, and <0.01 to 0.11 mg/kg respectively. Positive correlation in TPAH and particle sizes and organic carbon was recorded (R2 > 0.890). Partitioning of the more hydrophobic high molecular weight (HMW)-PAHs occurs to a greater extent (72–93%) compared with low molecular weight (LMW)-PAHs. The overall results showed that the soils of the area were highly contaminated and might be detrimental to living existence, through contamination of ground and surface water.