Assessment of Environmental Levels of Pollution in Soil Contaminated with Crude Oil Using Soil Contamination Indexes Models

The Ajeel oil field in central Iraq was selected to conduct a study on soil contaminated with crude oil. The site was divided into two areas: Area 1 and area 2. Four samples were studied for each region, and concentrations of 11 toxic elements were studied. The results showed that cadmium Cd⁺² and arsenic As⁺³, significantly exceeded permissible limits, reflecting a significant environmental risk to soil and water. While the level of contamination with lead elements Pb⁺², chromium Cr⁺³, zinc⁺², Zn⁺², nickel Ni⁺², copper Cu⁺², lead Fe⁺³, manganese Mn⁺², cobalt Co⁺² and molybdenum Mo⁺⁶, was moderate. Contamination models and indicators were used to evaluate the level of contamination that occurred. PRI results showed that zone 2 had severe and widespread contamination, especially in samples 5, 7, and 8, which recorded very high PRI values up to 1800.36, indicating very high contamination. While the results of the Nemerow Pollution Index model indicate a serious exceedance of the limits. Zone 2 was recorded as the most polluted zone according to the Nemerow Pollution Index PN, with the highest value of 40.72, followed by Zone 1 in terms of pollution intensity.