To restore oil-contaminated soil in this work, humic acids in monomeric and polymeric forms were used in the process of sorption decontamination and purification of oil-contaminated soils. The choice of these reagents is due to high reactivity of humic acids in relation to petroleum hydrocarbons, which is associated with presence of a hydrophobic aromatic framework in their structure. This made it possible consider humic substances as natural detoxicants capable of reducing ecological load of oil pollution on environment.
The studies were carried out on soil sampled from bottom of open evaporation ponds of LLP "Atyrau Oil Refinery" on herbaceous plants from legume family - alfalfa, melilot, sainfoin. The initial oil content in the studied soil -17.38%, the pH of water extract of soil -7.62, electrical conductivity -2735Sm/m, the salt content -1680mg/kg.
Among leguminous grasses, alfalfa occupies leading place, being the main source of vegetable protein. Due to its productive longevity and ability to assimilate atmospheric nitrogen in grass mixtures, it increases their yield. Melilot saturates the soil with oxygen and nitrogen, improves the structure of the soil. Sainfoin is a soil conditioner, used as a green fertilizer, which gives high yields even on poor washed-out soils of the slopes of hollow, ravines.
The soil was treated with 0.1% and 0.5% solutions of humic acids, then samples were stirred with an electric stirrer until uniform and dried in air at room temperature for 24 hours. The seeds were also treated with a 0.0025% solution of polymeric form of humic acids.
The study of the phytotoxicity of soils was carried out in laboratory conditions; the sowing of herbaceous plants was carried out in plastic cups. Sowing depth of seeds - 1 cm.
In the experiments, phenological observations were carried out in each variant. Research have shown that seedlings were not observed in soils treated with 0.1% and 0.5% solutions of monomeric form of humic acids. However, with additional treatment of seeds with a 0.0025% solution of the polymeric form of humic acids, the first shoots appeared on the 7th day from the moment of sowing. The largest number of sprouts was observed for sainfoin seeds.
Analyzing the data obtained, it is not difficult to notice that the polymeric form of the growth stimulator turned out to be a factor affecting the growth of the assimilation surface, and, as a result, an increase in seed germination.