Specific features of oil biodegradation in meadow-chestnut soils of the Stavropol region (model experiment)

Oil biodegradation in oil-contaminated meadow-chestnut soils under the impact of different biological preparations was studied in a model experiment. The soils differed from one another in the age of contamination and in the presence/absence of the stage of preliminary biological remediation. Background uncontaminated soils served as the control. To characterize oil degradation, the indices of basal respiration (BR) and dehydrogenase activity (DA) and data on oil concentrations in the soil were applied. It was shown that the most complete biodegradation of oil takes place in the soils with recent oil contamination in comparison with the soils contaminated with oil for 6.5 and 19.5 months. Maximum BR values were observed in the soils contaminated with oil for 19.5 months, whereas maximum DA values were observed in the soils contaminated with oil for 6.5 months. According to the multivariate analysis of variance, the major factors affecting the rate of oil biodegradation were the age of oil contamination, the biological preparation applied, and the presence (or absence) of the stage of preliminary biological remediation. These factors specified 18, 72, and 3% of the total variance of the residual oil content in the samples, respectively. The type of the applied biological preparations had the major effect on the BR and DA indices specifying 63 and 53% of their total variances, respectively. The results obtained in this study can be used as recommendations for remediation of oil-contaminated soils in the Stavropol region.