Environmental and Spatial Analysis of Soil Contamination by Polycyclic Aromatic Hydrocarbons (PAHs) Near Maysan Refinery Using GIS Techniques, Southern Iraq

Abstract

This study aimed to determine and evaluate the distribution and concentration of polycyclic aromatic hydrocarbons (PAHs), total organic carbon (TOC), pH, and electrical conductivity (EC) in selected industrial soils from several facilities within the Maysan Refinery and in soils collected from urban areas surrounding the refinery in southern Iraq. Ten soil samples were collected from a depth of 15 cm. PAH concentrations were determined using GC–MS analysis, while extraction was performed using a Soxhlet apparatus. TOC values were calculated according to the Walkley and Black method. The analyses showed variations in the concentrations of hydrocarbon compounds among the samples. The highest concentration of PAHs was recorded inside the Maysan Refinery, particularly in Sample 3 collected near the oil tanks, where the total concentration reached 10.73093 ppm. This high concentration of aromatic compounds was attributed to the presence of carcinogenic aromatic hydrocarbons, especially Acenaphthylene, which showed a significant concentration of 4.2959 ppm, indicating potential environmental contamination in the refinery soils. In contrast, the lowest total concentration of aromatic compounds was approximately 0.004911 ppm in Sample 7, collected near the refinery garage. Chemical analyses revealed that TOC concentrations varied among the samples. The highest TOC value was recorded near the oil pumps at approximately 8.59%, whereas the lowest value was observed in agricultural land outside the refinery at approximately 1.09%. These variations were attributed to differences in pollutant distribution and the locations of oil spills. In general, the highest pollutant levels were recorded near the oil tanks, and soil type had a significant effect on the distribution of hydrocarbon concentrations. These hydrocarbons contained carcinogenic pollutants such as Acenaphthylene, whereas the agricultural soils were free from such contaminants.