Ecological risk assessment of the levels of polycyclic aromatic hydrocarbons in soils of the abandoned sections of Orji Mechanic Village, Owerri, Imo State, Nigeria

Abstract

Background: Ecological risk assessment of the levels of polycyclic aromatic hydrocarbons in soils of the abandoned sections of Orji Mechanic Village, Owerri, Imo State, Nigeria. The main objective of the study was to determine the levels of soil contamination from polycyclic aromatic compounds (PAHs) due to anthropogenic events in the mechanic village before reclamation. Results: Analysis of soil samples revealed mean PAH levels ranging from 1.22E−02 ± 0.00 to 5.60E−02 ± 0.01 mg/kg, with higher PAH concentrations observed at 0-10 cm compared to other depths. The sum of PAHs (∑PAHs) ranged from 1.58E−01 to 6.71E−01 mg/kg, as the sum of low molecular weight PAHs (∑LPAHs) varied from 7.16E−03 to 1-1.60E−01 mg/kg, while the sum of high molecular weight PAHs (∑HPAHs) ranged from 1.81E−02 to 5.42E−01 mg/ kg. The sum of carcinogenic PAHs (∑Carcino-PAHs) varied from 5.39E−01 to 9.74E−02 mg/kg, indicating elevated levels of carcinogens in the sampled soils. Diagnostic ratio, principal component, and correlation analysis of the results revealed that pyrogenic sources were primarily responsible for the observed PAHs owing to the activities of automobile mechanics in the Orji Mechanic Village. Benzo(a)pyrene equivalent (BePeq) of the PAHs indicated high carcinogenic potency for sample A. The total cancer risk was above 1 × 10-6 , indicating a greater risk of cancer due to contact with the contaminated soil samples; hence, the result of this study is a serious ecological concern. Conclusion: There may be accumulation of these contaminants in the investigated area, which will eventually contaminate the groundwater as well as surface water resources. Remedial measures to prevent possible health problems due to the PAHs which results from the activities of automobile mechanics are therefore recommended.