Ekaterina Igorevna Kovaleva

The estimation of the radial migration of petroleum hydrocarbons (TPH) in soil profile and their inflow into lysimetric leachates was done to establish acceptable TPH limits in main soil types of Sakhalin Island. The maximum concentrations of TPH, especially medium and high-boiling fractions of TPH, were accumulated in peat and humus horizons, as well as in soil horizons, characterized by heavy loam or clay granulometric composition, which could be considered as radial geochemical barriers to the migration of pollutants. Benzene and its homologues were detected in filtrates from soil monoliths, after passing a water volume corresponding to three-quarters of the annual precipitation, yet these compounds were not revealed after passing the annual precipitation rate through the soil. The toxicity of the leachates was assessed in bioassay with ceriodaphnia and ciliates. The criteria for establishing the acceptable TPH norms in soils according water migration index can be: concentration of TPH, the content of monoaromatic compounds in leachates and their toxicity for hydrobionts in lysimetric experiments.

In Russia, the lands with oil contaminated soils exceed tens of thousands hectares. However, to date, there were no unified approaches to the rationing of oil and petroleum hydrocarbons (PH) in soils, a guideline to choose optimal evaluation indicators. The response of plants in the pot experiment could provide significant results for assessing and rationing of PH content in soils and their use in agriculture after land remediation. In this work we assessed the response of higher plants as a marker of the direction and intensity of biological processes in soils in the pot experiment under oil contamination to justify the standards of permissible residual content of PH in soils of agricultural lands. The composition and properties of Luvic Chernozems, Calcic Chernozems, Voronic Chernozems (WRB, 2015) used in the pot experiment, which was carried out in a month after the soil contamination with crude sulfur-containing oil, were investigated. The effect of different oil doses on the bioproductivity of wheat and peas was evaluated. Wheat in terms of dry biomass showed higher sensitivity to PH, containing medium and heavy fractions, than peas. Rationing the PH content in chernozems, a nonlinear regression model described by a logistic curve was applied. The quality standard values found for wheat biomass was 0,9; 0,4; 1,0 g * kg^-1 for Luvic Сhernozems (humus content ~ 9,8%, sandyloam texture); Calcic Chernozems (humus content ~7,6%, clay loam texture), Voronic Chernozems (humus content ~12.8%, loam texture), respectively. The residual PH contents, found as 30% of soil functioning change, which corresponded to the risk level of soil degradation, estimated by the soil fertility parameter — dry wheat biomass were 1,2 g·kg^-1 for Voronic Chernozems; 0,5 g·kg^-1 — Calcic Chernozems; 1,1 g·kg^-1 in Luvic Chernozems.

Milestones in the study of oil-contaminated soils at the Faculty of Soil Science for 50 years of its foundation are dis- cussed from the prospects for the development of environmental regulation and new technologies of soil reclamation. The development of a methodological framework for the determination of oil and petroleum hydrocarbons in soils, studies of soil properties, the chemistry of oil and its components in soil and adjacent media are shown. The devel- opment of legislation on the rationing of petroleum hydrocarbons in soils is given, including the important role of the staff of Faculty of Soil Science of Moscow State University in the work out of a number of regional standards for the permissible residual content of petroleum hydrocarbons in soils is noted. The approaches to ecological rationing of oil and petroleum hydrocarbons in soils are proposed, in the aspects of natural climatic zones and the type of landuse. The importance of improving the regulatory and methodological framework and continuing work in this direction is emphasized. The necessity of research at developing technologies for reclamation of oil-contaminated lands and special use of oil-contaminated waste is indicated.

The effectiveness of remediators in detoxification of soils contaminated with heavy metals was studied in a lab experiment. The objects of the study were the soils of the southern tundra, functioning under conditions of anthropogenic impact: Haplic Gleysols (Gelic) and Histic Fluvisols (Oxyaquic). The chemical ability of remediants to bind metals (Ni and Cu), transferring them to a sedentary state in comparison with the reference variants (without any addition of remediants), was evaluated. In experiments, remediants were used in three doses (D1, D2, D3): shungite; diatomite, glauconite and bentonite. To assess the immobilization of Ni and Cu in soils, acid-soluble (CR) forms (extraction of 1 n. HNO₃), mobile forms (ammonium acetate buffer solution with pH 4.8), water-soluble forms of Ni and Cu (1:20 aqueous extract) were determined by inductively coupled plasma mass spectrometry. The effectiveness of soil detoxification during the application of remediants was evaluated by the phytotoxic effect in an express phytoassay with standardized tests (Brassica rapa CrGC and Avena sativa) represented by higher plants. A decrease in the proportion of mobile forms of Ni and Cu by 50% or more in Haplic Gleysols (Gelic) was revealed with the addition of any dose of ameliorants. The greatest effect of reducing mobility was exerted by shungite and diatomite at a dose of D1 — up to 15% Ni and Cu for Histic Fluvisols (Oxyaquic) soil. The use of the selected remediants in the indicated amounts did not reveal a phytotoxic effect on the tests in the experiment.