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A B S T R A C TGroundwater and soil samples from 16 locations near petrol stations (PS) and mechanic workshops (MW) around Calabar, Nigeria, were analyzed for heavy metals and hydrocarbons to determine their concentrations and assess the impact of the PS and MW on groundwater in the area. Results show that mean concentrations of arsenic, cadmium, chromium, copper, iron, mercury, manganese, nickel, lead, and zinc in groundwater are higher than the reference data (maximum admissible concentration, baseline value, and control site value). The mean concentration of total organic content in soil is low (4.03%), but the mean concentrations of total petroleum hydrocarbons (46.87 mg kg À 1 ) and naphthalene (340.00 mg g À 1 ) in the soil are high in comparison to the reference data. The mean concentrations of parameters in soil and groundwater are higher where PS and MW are located near each other (PS/MW). The mean total hydrocarbon content (0.66 mg L À 1 ) and total polycyclic aromatic hydrocarbon ( P PAH) (66.64 mg L À 1 ) in groundwater are higher than the maximum admissible concentration of 0.1 mg L À 1 and 0.2 mg L À 1 , respectively. The concentration of PAH compounds with mean concentrations greater than 1 mg L À 1 are of the order phenanthrene > anthracene > fluorene > benzo(b)fluoranthenebenzo(k)fluoranthene pyrene > naphthalene. The ratios of phenanthrene/anthracene, fluoranthene/pyrene, and benzo(a)anthracene/ chrysene and factor analysis indicate several sources for the PAH. The most important sources include anthropogenic (petrogenic, pyrolytic) and natural.

The level of concentrations of polycyclic aromatic hydrocarbons (PAHs) in surface soils from petroleum handling facilities (kerosene tank, generating plant, petrol stations, mechanic workshops, leaking pipeline and air port fuel dump) from Calabar metropolis southeastern Nigeria was determined by gas chromatography/ mass spectrometry. The results show that total polycyclic aromatic hydrocarbons (PAHs) varied from 1.80 to 334.43 mg/kg with a mean of 50.31 mg/kg. The lowest value of 1.80 mg/kg was obtained from petrol station while the highest value of 334.43 mg/kg was obtained from facility characterised by petrol stations and mechanic workshops. The ratio of phenanthrene/anthracene and fluoranthene/pyrene, varied from 0.43 to 27.72 and from 0.14 to 17.76 respectively. These ratios indicate various sources for the PAH. The two to three ring PAHs are the most abundant. Based on the PAH ratios and content alone it is not possible to distinguish between contribution from motor vehicle exhaust, gasoline spillage, used engine oil or petroleum production. However, considering the area of the study, it is very likely that the major source of soil contamination is originating from petroleum product.

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