Abstract
Oil industry in Khuzestan province (Southwest Iran) is one of the main reasons contributing to pollution of the environment in this area. Total petroleum hydrocarbons, including both aromatic and aliphatic compounds, are important parameters in creating pollution. The present study aimed to investigate and source of soil contamination by total petroleum hydrocarbons (aromatic and aliphatic) in the Ahvaz oil field in 2022. The soil samples collected from four oil centers (an oil exploitation unit, an oil desalination unit, an oil rig, and a pump oil center). An area outside the oil field was determined as control area. 10 samples with three replicates were taken from each area according to the Standard Methods. Aromatic and Aliphatic compounds were measured by HPLC and GC methods. The PMF model was used to determine the source apportionment of aromatic compounds in soil samples. ERL and ERM indices were also used to assess the level of ecological risk of petroleum compounds in the soil samples. The results showed that Benzo.b.fluoranthene had the highest concentration with an average of 5667.7 ug/kg in soil samples in the Ahvaz oil field. The highest average was found in samples from the pump oil center area at 7329.48 ug/kg, while the lowest was found in control samples at 1919.4 ug/kg. The highest level of aliphatic components was also found in the pump oil center, with a total of 3649 mg/kg. The results of source apportionment of petroleum compounds in soil samples showed that oil activities accounted for 51.52% of the measured aromatic compounds in soil. 38.3% of other measured compounds had anthropogenic origins, and only 10.18% of these compounds were of biotic origin. The analysis of ecological risk indices resulting from the release of aromatic compounds in the environment showed that, except for Fluoranthene, other aromatic compounds in the oil exploitation unit area were above the ERM level (moderate risk range) and at high risk. The results of the study showed that soil pollution by total petroleum hydrocarbons, both aromatic and aliphatic, is at a high level, which is mainly caused by human activities, particularly oil activities.