Evaluation of total petroleum hydrocarbons (TPH) and some related heavy metals in soil and groundwater of Ubeji settlement, Warri Metropolis, Nigeria.

Soil and groundwater samples in areas of oil spill in Ubeji settlement, Warri metropolis, Nigeria, were collected in order to determine the oil and grease, total petroleum hydrocarbons (TPH) and some related heavy metals in the samples. Control samples were taken from a low density residential area in Delta State (Ekrejeta in Abraka) which is relatively free from petroleum activities. The parameters were evaluated in order to determine the quality of the soil and groundwater of Ubeji settlement, as a follow up on an earlier research conducted on the surface water and sediment of the settlement’s river. This research is so important because the local population uses the soil and water resources for agricultural and domestic purposes. Measurements of oil and grease and TPH in samples were done gravimetrically, while atomic absorption spectrophotometry was used for determination of heavy metals. For oil and grease and TPH, the soil had mean concentrations of 1064.90 ± 7.70 and 579.10 ± 9.30 mg kg-1, respectively, while groundwater had 315.15 ± 11.60 and 28.70 ± 1.30 mg L-1, respectively. Mean heavy metal concentration of the soil and groundwater varied between 0.30 ± 0.01 to 215.49 ± 25.33 mg kg-1 and 0.03 ± 0.01 to 3.05 ± 0.07 mg L-1, respectively. These values reveal that the investigated samples had higher levels of oil and grease, TPH and heavy metals than the control samples and regulatory standard limits. This however, is an indication of pollution of soil and groundwater of the settlement by petroleum hydrocarbons