Effect of oil contamination on the course of changes in chernozem properties and phytotoxicity

Abstract

Introduction. The consumption of hydrocarbons in the world is steadily growing with the response to the progress of civilization. It is accompanied by the continuous flow of hydrocarbon pollutants into the environment. Soil pollution with oil attracts special attention, because the soil is a key element in the trophic chain of toxicants in the human body. Purpose. Investigate changes in the properties (physicochemical, agrochemical and biological) of chernozem soils and its phytotoxicity at different levels of oil pollution for further use of the parameters of these indicators during soil monitoring. Research methods. The research was conducted during 2019-2021 in the conditions of the Left-Bank Forest-Steppe of Ukraine in a field small-plot experiment on Chernozem Luvic with the frequency of observations on diagnostic indicators at 1 month, 6, 12 and 24 months. The scheme of the experiment provided for soil contamination with oil in the amount of 0.4 l/m2, 1.6 l/m2, 6.4 l/m2, 25.6 l/m2. Results. The rate of biodegradation of oil products for different levels of pollution of Chernozem Luvic was determined - with insignificant pollution, self-purification of the soil is characterized by a faster course than with medium and strong, within 24 months the content of hydrocarbons decreased by 85-87% and 60-64%, respectively. One of the important mechanisms for the loss of hydrocarbons from the soil surface is microbiological decomposition, studies have shown that in the oil concentration range of 6.4-24.6 l/m2, there was a significant increase in the intensity of carbon dioxide release from the soil, which is 60% higher than in the control option, this indicates the intensification of the processes of its biodegradation. Studies of changes in such diagnostic indicators as soil pH, the content of water-soluble potassium and sodium show a less significant influence of the factor of soil pollution with oil compared to the influence of the time factor. However, these indicators are of great diagnostic value in the process of monitoring oil-contaminated soils and remediation, since the most optimal parameters of these indicators determine the suitability of soils for plant growth and microbial life. Studies of phytotoxicity of oil-contaminated soil have shown the negative impact of oil on seed germination in the field condition. Conclusions. The research results indicate a gradual self-purification of the soil from petroleum hydrocarbons during the observation period. The obtained regularities of the dynamics of changes in the studied parameters will be used to improve the scientific and methodological support for monitoring soils affected by oil pollution.