Method for Determining the Environmentally Safe Residual Content of Oil and Petroleum Products in Soils

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 a rise in traffic flows and, as a result, in environmental pollution, including oil hydrocarbons. The risks of leakage of oil products during transportation and pumping are increasing. It is necessary to determine the environmentally safe residual content of oil and oil products in soil based on the regional ecological and geochemical characteristics of soils to predict and prevent dangerous consequences of pollution. Laboratory modelling of contamination with oil and petroleum products (fuel oil, gasoline, and diesel fuel) of soddy-calcareous typical soil was carried out. To simulate pollution, oil and petroleum products were added to soil samples, including fuel oil, gasoline, and diesel fuel in the 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, and number of soil bacteria) were determined. Based on the listed parameters, the integral indicator of the biological status IIBS of the soil was calculated. 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 sequence of the studied substances with respect to their toxic effect on biological indicators of soils is as follows: oil > fuel oil > gasoline > diesel fuel. The study enables us to determine the maximal permissible residual content (MPRC) of oil and petroleum products (fuel oil, gasoline, and diesel fuel) in the refinery area. It is 0.27% for oil, 0.40% for gasoline, 0.30% for fuel oil, and 0.45% for diesel fuel. The proposed MPRC of oil and petroleum products (fuel oil, gasoline, and diesel fuel) in soils are primarily applicable on the territory of the Black Sea coast of the Caucasus.The proposed MPRC of oil and petroleum products (fuel oil, gasoline, and diesel fuel) in the soils of the refinery area may be used by environmental, agricultural, and scientific organizations.