The Impact of oil contamination on soil hydrophobicity and physico-chemical properties around Bandar Abbas oil refinery, Hormozgan Province, Iran

Background: The leakage of oil, in addition to negative environmental effects such as groundwater contamination, causes changes in the geotechnical characteristics of the soil. Methods: The soil hydrophobicity test was carried out using the Water Drop Penetration Time (WDPT) method in the contaminated places, and soil samples with minimum corrosion were collected, and some physical and chemical properties of the soils were measured. To evaluate the stability of the soil structure, wet sieving and mechanically dispersible clay (MDC) methods were used, and the mean weighted diameter (MWD) and geometric mean diameter (GMD) indicators of soil grains and MDC were calculated. Results: The results showed that the amount of TOC and TPHs in the soils around the refinery was found to be 68.16±3.18 and 37.27±2.22 percent, respectively. The results indicated that the increasing impact of oil contamination on MWD and GMD and its decreasing impact on MDC were statistically significant. A significant positive correlation was obtained between hydrophobicity and GMD in soils. But the densities of TPHs more than 6.4% in the soil led to a decrease in MWD and GMD, which can be due to the increase of anionic repulsion between clay particles and functional groups of hydrocarbons. Conclusion: Although hydrophobicity increased the stability of the soil structure in oil-contaminated places compared to the control places, the severe decrease in soil water retention caused by oil contamination creates unfavorable conditions for the green spaces of the soils around Bandar Abbas oil refinery.