A method for determining the environmentally safe residual content of oil and petroleum products in soils

Introduction. The Black Sea Coast of the Caucasus is one of the most important recreational and tourist regions for Russia. In recent years, it has been subjected to a sharply increased anthropogenic load, due to an increase in the number of tourists, accompanied by an increase in traffic flows and, as a result, an increase in environmental pollution, including oil hydrocarbons. The risks of leakage of oil products during transportation and pumping are increasing. To predict and prevent dangerous consequences of pollution, it is necessary to determine the environmentally safe residual content of oil and oil products in the soil, based on the regional ecological and geochemical characteristics of soils.

Materials and methods. Laboratory modelling of contamination with oil and petroleum products (fuel oil, gasoline, diesel fuel) of sod-carbonate typical soil was carried out. To simulate pollution, oil and petroleum products were added to soil samples including fuel oil, gasoline, diesel fuel in a weight concentration of 1% (low pollution), 5% (medium pollution) and 10% (high pollution) of the soil mass. The exposure period lasted 30 days. After the specified period, changes in biological parameters (enzyme activity, radish root length, number of soil bacteria) were determined. Based on the listed parameters, the integral indicator of the biological state IIBS of the soil was calculated .

Results. Oil and oil products pollution negatively affected the biological properties of the studied soil. A significant decrease in enzymatic activity, the number of bacteria, and the length of plant roots was recorded. The range of toxicity of the studied substances on biological indicators of soils is as follows: oil > fuel oil > gasoline > diesel fuel. The study made it possible to determine the maximum level of residual content of oil and petroleum products (fuel oil, gasoline, diesel fuel) in the refinery. For oil, it is 0.27%, for gasoline — 0.40%, for fuel oil — 0.30%, for diesel fuel — 0.45%.

Limitations. The proposed limit levels of residual oil and petroleum products (fuel oil, gasoline, diesel fuel) in soils are applicable primarily on the territory of the Black Sea coast of the Caucasus.

Conclusion. The proposed limit levels of the residual content of oil and petroleum products (fuel oil, gasoline, diesel fuel) in the soils of the refinery area can be used by environmental, agricultural and scientific organizations.

Compliance with ethical standards. The study does not require an opinion from a biomedical ethics committee or other documents.

Contribution:
Gaivoronskiy V.G. — literature data collection, text writing;
Kuzina A.А. — text writing, editing;
Kolesnikov S.I. — research concept and design, text writing, editing;
Minnikova T.V. — collection of material and data processing, editing;
Nevedomaya E.N. — collection of material and data processing, statistical data processing;
Kazeev K.Sh. — collection of material and data processing, editing.
All authors are responsible for the integrity of all parts of the manuscript and approval of the manuscript final version.

Conflict of interests. The authors declare that there is no conflict of interest.

Acknowledgment. The research was financially supported by the Ministry of Science and Higher Education of the Russian Federation no. FENW-2023-0008, the President of the Russian Federation (MK-2688.2022.1.5 and МК-175.2022.5).

Received: May 18, 2023 / Accepted: September 26, 2023 / Published: October 30, 2023