On diagnostics and estimation of chernozems polluted by oil

Pollution of the soil cover by oil and oil products is one of themost urgent problems of ecology. It is relevant not only for areas where objects of oil-extracting, petrochemical branches of economyare located. Hydrocarbon raw materials are transported across vast territories far from the places of their production. The consumptionof oil products and emissions of their waste in the environment is practically everywhere. At present much attention is paid to the studyof processes of natural bioremediation and working out of methods of polluted soils re-cultivation for further agricultural use. Thesuccessful solution of the given problem in many respects depends on how well the estimation methods of the degree of soil pollutionare developed. For rationing oil pollution it is important to establish the level of oil concentration in soils, above which it cannot copewith pollution itself, i.e. to define the potential of its ability to self-clean. During the field experiment with soils artificially polluted withvarious concentrations of oil an attempt to estimate the ability of ordinary chernozem to natural bioremediation was undertaken. Thesamples of soils were selected from the layer of 0-30 cm. They were investigated on the 5, 30, 100, 310 and 365 day after pollution. Theadmissible level of pollution was the amount of oil exposed to natural mineralization in soil for the time interval of less than a year. Itwas revealed that of the set of diagnostic features defining the degree of influence of oil on a soil ecosystem, such as humus stock,cations exchange capacity, humus horizon capacity, number of nutritious elements, the most reliable indicator and index of stability ofsoils to anthropogenic influence is microbiological and fermentation activity of soils, which are labile signs reacting to insignificantconcentrations of oil. Heterotrophic microorganisms react to oil by decrease in number. The increase in the number of hydrocarbonoxidising microorganisms is the result of the processes of detoxification in soil. Close correlation dependence between the change inmicrobiological and fermentation activity of soils is observed. Changes in microorganisms and fermentation activity of ordinarychernozem in combination with classical chemical analyses are expedient to use for detailed diagnostics, monitoring and rationing of theoil polluted chernozems.

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