Investigation of the oil-polluted dark-humus soil properties

The aim of the study was to assess the properties and ability to perform ecological functions by dark-humus soil (Rendzic Phaeozem) exposed to oil contamination and subsequent reclamation by cutting the contaminated layer. Location and time of the study. An accidental oil spill in the southern taiga subzone of the Perm Krai in 2020 resulted in the contamination of the dark-humus soil over an area of 0,52 hectares. The contaminated vegetation and topsoil were removed and transported for remediation to a specialized organization. Dark-humus soil is classified as a specially protected category of soil in the region. In 2023, soil samples were collected from the 0–20 cm and 20–40 cm layers at seven sites within the contaminated area; a post-agrogenic dark-humus soil was used as the reference standard. Methods. The soil samples were analyzed for the following parameters: residual petroleum hydrocarbon content, pH (water and salt suspension), hydrolytic acidity, total exchangeable bases, organic matter content, available phosphates and potassium, catalase, urease, and invertase activity, soil bulk density, particle density, aggregate composition, porosity, and particle-size distribution. Soil phytotoxicity was assessed using a garden cress (Lepidium sativum L.) bioassay by measuring the shoot length and fresh biomass. The significance of differences from the baseline (control) soil was determined by one-way ANOVA using the Kruskal-Wallis test at a significance level of p