Naphthenic acids are a group of polar organic carboxylic acids that are present in crude oil naturally. They are cycloaliphatic carboxylic acids which have 10 to 16 carbons, which gained importance since the early twentieth century because of corrosion in oil refineries. Moreover, they are the most important environmental pollutants caused by oil extraction from oil sand reserves. Heavy crude oils which have high concentration of naphthenic acids are usually considered as poor-quality oil and sold at a lower price. Often, the high concentration of naphthenic acids in crude oil reduces the life of the equipment which are used in the exploration and refining process because of corrosion. Hence, researchers are increasingly interested in the chemical properties of naphthenic acids and the acidic components of the crude oils. The most popular methods for the identification and analysis of naphthenic acids are liquid and gas chromatography (GC), liquid-liquid extraction, Fourier transform infrared spectroscopy (FTIR), and solid-phase extraction (SPE). Naphthenic acids are the most important environmental pollutants caused by oil extraction from oil sand reserves. Previous studies have revealed that naphthenic acids can be absorbed by fish, but their distribution in different tissues of fish has not been specified. Experimental samples showed the highest toxicity to fish, while there was less toxicity to invertebrates and algae. Moreover, naphthenates have various industrial utilizations; they are used in synthetic detergents, corrosion inhibitors, lubricants, fuel and oil additives, wood preservatives, insecticides, fungicides, pesticides, wetting agents, napalm thickening agents, and oil desiccants that are utilized in painting and treating wood surfaces.

Middle and southern Iraq suffers from polluted soils due to crude oil, spilled on land, leakage from transmitting pipe networks, or petroleum products from refineries. Many researchers have studied pollution impacts on the soil in details, but there is a clear lack of investigation on the influence of crude oil on soil erodibility. Recent researches have investigated the influence of pollution on erodibility parameters, which include critical shear stress (τc) and detachment factor (dc). The variability of dc and τc due to different in-situ scaling has not been thoroughly established for polluted and unpolluted soils. Thus this research aims at investigating the influence of different in-situ scaling ratios (1:1, 1:30, and 1:50) on variability of dc and τc for polluted and unpolluted soils under controlled laboratory conditions, using Jet Erosion Test (JET), and tries to compare the three solution techniques (namely, Blaisdell’s approach, depth scour approach, and iterative approach) to solve dc and τc from JETs for polluted and unpolluted soils. The polluted soil samples have been prepared by submerging the soil surface with crude oil for 24 hours prior to testing. Results show that there have been statistical differences in dc and τc between polluted and unpolluted soil samples on the dry side of water contents with no statistically significant difference of measured dc and τc being observed across different in-situ scale ratios for polluted and unpolluted soils. All told, the study shows less variability of measured dc and τc across different solution techniques, compared to previous study findings.