Post-Reclamation Enhancement of Physical and Biological Properties of Soils Contaminated by Oil and Petroleum Products

Soil contamination by oil is a common issue in areas surrounding oil fields, storage depots, and refining industries. This contamination can damage the physical, chemical, and biological properties of the soil, requiring recultivation. This article presents the results of soil property recovery after biological recultivation. The results show that the rate of water transfer in treated soil was 37.5 g/kg, which is 2.5 times faster than in contaminated soil. Additionally, the water retention capacity of contaminated soil was 1200 mm after 90 minutes, while in treated soil it was only 75 mm. This represents a 16-fold improvement. Due to oil pollution, the anthropogenic carbon (Cant) in the soil increased to 1.87%. After reclamation, it decreased to 0.21%. The number of microorganisms, including heterotrophs, phosphorus-decomposing bacteria, ammonifiers, actinomycetes, and microscopic fungi, decreased as a result of oil pollution. However, after recultivation, their number increased up to several hundred times, with only oil-decomposing bacteria decreasing. The activity of catalase, invertase, phosphotase, and dehydrogenase enzymes decreased after pollution, but improved and restored after recultivation.