Polycyclic aromatic hydrocarbons (PAHs) are very toxic and persistent environmental contaminants. The paper is aimed at investigating the PAHs levels in soil collected at 0-30 cm depths from 5 automobile repair workshops within Eket metropolis/the underground water around its vicinity. The soils and water were prepared in the laboratory following standard procedures and were analysed for 16 US EPA priority PAHs using Gas Chromatography-Mass Spectrometer (GC-MS). Total PAHs concentrations in soil (Ʃ16 EPA PAHs) from all sampling sites were in the range of 0.82-12.98 mg/ kg and 0.47-14.85 mg/kg for both dry and rainy seasons respectively and did not follow regular pattern with depth. Total PAHs concentrations in underground water from all sampling sites were in the range of 1.71-16.07 mg/l and 1.07-12.97 mg/l for both dry and rainy seasons respectively. According to European commission contamination classification and WHO maximum permissible limit for PAHs in drinking water (0.002 mg/l), the sites are said to be moderately to heavily contaminated. The total BaPeq for the soil and water samples indicated a moderate carcinogenic burden and hence low health risk. The calculated values obtained from diagnostic ratios shows that the PAHs in this study were from both pyrogenic and petrogenic sources. The correlation between total PAHs concentration in soil and water for both seasons indicated that the automobile repair activities had a moderate effect on the soil as well as the underground water around it. Therefore, boreholes should not be sited close to automobile repair yards to enable its suitability for domestic, irrigation and recreational usage.

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In this study, we screened the performance of aqueous extracts of Talinum triangulare (AET) and soap solution prepared from Hura crepitans seed oil saponified by aqueous solution of ashed plantain peels (HCS) for removal of naphthalene and phenanthrene from soil. The distribution of trace metals in the soil before and after soil washing was also investigated. The results revealed maximum removal efficiencies after 25 min washing time of 96.25, 96.14, and 25.70% naphthalene, for Tween 80, AET and HCS, respectively. While for phenanthrene, the recorded maximum removal efficiencies after 25 min washing time were: 91.80, 26.00, and 94.0 for Tween 80, AET and HCS, respectively. Based on results from other experiments, AET generally showed slightly lower removal efficiencies compared to the commercial Tween 80 surfactant. Also, the results revealed that the three remediants affected the distribution of trace metals (Cd, Pb, and Zn) in the soil after surfactant washing. Based on the amount of trace metals extracted, the performance of the three remediants are as follows: AET > Tween 80 > HCS. The performance of AET has been attributed to the presence of multiple heteroatomic moieties for trace metals adsorption and moderation of the acidic conditions of the soil.