I.A. Degtyareva1, S.K. Zaripova2, A.Ya. Hidiyatullina1
1Tatar Research Institute of Soil Science and Agricultural Chemistry of the Russian Academy of Agrarian Sciences, Russia, Republic of Tatarstan, Kazan city, Orenburg tract, 20 a
2Kazan National Research Technological University, Russia, Republic of Tatarstan, Kazan city, Karl Marks Str., 58
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Summary. With the aim of intensifying the process of purification of sod-calcareous soil from oil pollution in saline conditions with highly efficient oilfield waters the consortium of destructor microorganisms isolated from sludge and capable to destroying the oil at concentrations up to 10% and salt content to 3,5% was applied. In the period from the 67th upto the 75th month from the date of pollution the number of non galotolerant heterotrophic bacteria in the experimental variants were within the level of microorganisms in uncontaminated soil. Maintaining the level of halotolerant microorganisms (2,0*106…2,1*109 CFU / g of soil) despite the leaching of salts from the soil due to the creation of a drainage system that indicates that even after six years of soil contamination biocenosis didn’t return to beginning conditions. In all variants of the pollution the level of metabolic activity of soil microorganisms under the influence of anthropogenic load was low. Adding a consortium of microorganisms-destructors contributed to the most effective decreasing the number of hydrocarbons (the number of residuals after 75 months amounted less than 30%, with self-cleaning – more than 55%). Contamination with the oil concentration of 10% contributed to significant changes in behavior strategies of microbial community in comparison with the soil contamination into a salt concentration of 3%. Up to the sixth year of remediation of sod-calcareous soil contaminated with oil and related oilfield waters the total number and proportion of halotolerant aerobic heterotrophic and hydrocarbon-oxidizing microorganisms in microbiocenosis stabilized and became comparable to those in uncontaminated soil. The most pronounced effects on soil microbiocenosis produced oil pollution expressed in increasing the proportion of slowly growing heterotrophic bacteria. Halotolerant microorganisms in the researched soil implemented K-strategy.
Keywords: hydrocarbon pollution, highly mineralized oilfield water, consortium microorganisms.