Biological Activity of Leached Chernozem under Oil and Sodium Chloride Pollution and the Effect of Treatment with Halotolerant Oil-Destructing Bacteria

Abstract

Soil contamination with oil is often accompanied by pollution by oilfield wastewater, which contains a significant amount of NaCl, which enhances the negative impact of hydrocarbons on soil, plants, and soil microbiota. Therefore, for the biotechnological purification of soils subjected to such combined pollution, hydrocarbon-oxidizing bacteria resistant to salinity should be used. In a model experiment, the effect of artificial pollution with oil (5%) and sodium chloride (1 and 3%) and their combinations, as well as bioremediation using halotolerant hydrocarbon-oxidizing bacteria on the biological activity of leached chernozem (Luvic Chernozem) was studied. Soil contamination with all types of pollution increased its phytotoxicity, while bacterization did not have a positive effect on this indicator in the presence of NaCl and with combined pollution, but contributed to a decrease in toxicity for plants of oil-containing soil. The most sensitive to the presence of oil and/or NaCl were actinomycetes, the number of which decreased by 1–2 orders of magnitude. The introduction of microorganisms increased the decomposition of hydrocarbons, including in complex polluted soil by 10.5–31.8%. In general, the presence of pollutants reduced the activity of soil enzymes. Bacterization contributed to some increase in the level of catalase in soil with oil, restored urease activity in oil-containing soil and under the combined action of pollutants, and increased invertase activity under combined pollution.