Laboratory Modeling of Environmentally Safe Concentrations of Fuel Oil in the Soils of Crimea

There are unique types and subtypes of soils on the Crimean Peninsula. The growing tourist load on the region requires an increase in the productivity of all industries, including oil refining. All of this increases risks of spills and leaks of oil and petroleum products during their transportation and pumping. There is a large gap in the field of regulation of soil pollution with petroleum products (gross content), which consists in the absence of maximum permissible concentrations in the regulatory framework of the Russian Federation. To predict the possible negative consequences of environmental pollution with oil and oil products, it is necessary to develop regional environmentally safe concentrations of oil and oil products that will take into account the local regional ecological and geochemical characteristics of soil types. The purpose of this study is to conduct laboratory modelling of environmentally safe oil concentrations in the soils of Crimea. Fuel oil contamination (1, 5, and 10% of the soil mass) was simulated under laboratory conditions. The study examined seven types of soils in Crimea: residual carbonate chernozem, drained solonetzic chernozem, dark chestnut solonetzic soil, brown carbonate soil, brown leached red soil, brown forest acidic soil, and underdeveloped chernozem. After 30 days of the model experiment, the most informative biological indicators have been determined in soil samples: biochemical indicators (activity of catalase and dehydrogenases), microbiological indicators (total abundance of soil bacteria and abundance of bacteria of the genus Azotobacter sp.), and phytotoxic indicators (root length). It has been established that fuel oil contamination has a negative impact on the biological properties of the studied soils in Crimea. A series of soil resistance to fuel oil contamination has been obtained: residual-carbonate chernozem ≥ solonetzic drained chernozem = dark chestnut solonetzic soil = brown leached red soil ≥ underdeveloped chernozem ≥ brown carbonate soil > brown forest acidic soil. The values of the maximum permissible levels of residual fuel oil content (MRLC) have been determined in the soils of Crimea: it is 0.33% in residual carbonate chernozem, 0.30% in dark chestnut solonetzic soil and solonetzic chernozem, 0.28% in brown carbonate soil, 0.35% in brown leached red soil, 0.33% in underdeveloped chernozem, and 0.21% in brown forest acidic soil. The results of the study can be used in biodiagnostics of the ecological state and health of soils when polluted with fuel oil.