TECHNOLOGY OF ESTIMATION OF THE STATE OF LAND BY NORMALIZATION OF MERCURY BY RELATION OF ITS THERMOFORM IN THE LITHOSUBSTRATE
The article reveals the technology of the ecological conditions diagnostics of lands of different-sized area and varying degrees of urbanization, located in different agro-climatic conditions of European Russia (the southern Astrakhan region, Moscow). Technology is considered as an approach that includes a combination of methods and actions to solve theoretical issues and practical problems for the production of environmental assessment works. The normalization of Hg in the soil needs to be adjusted, since a wide range of metal threshold concentrations is observed in hygienically justified methods. Hygienically grounded assessment criteria are not available for bottom sediments of water bodies. Assessments of the territories use a new approach to rationing of Hg - by quantitative relations of its thermoform content in soils, grounds and alluvium (in litho substrate). The method of diagnostics is based on the known properties of Hg forms: their geochemical activity (migration mobility) and toxicity are reducing while increasing the Hg temperature release threshold in the process of continuous warming up of the litho substrate sample (up to 1100°C). Thermoforms are not tied to specific minerals or chemicals and are conditionally designated as SV (Free: <180°C), CL (Chloride: 180-250°C), FS and CS (physically and chemically sorbed: 250-400°C), SU (Sulfide: 400-500°C) IZ (isomorphic: >500°C) Hg forms. Groups of "mobile", "sustainable" and "inert" forms are also conditionally pointed among these forms based on the complexes of low, medium and high temperature variations (SV + CL, FS + CS and SU + IZ, respectively). Anthropogenic Hg is characterized by the predominance of "mobile" thermoforms in the sample group, to a lesser extent - "stable" thermoforms. The more intense is this predominance, the higher is environmental hazard. The natural accumulation is diagnosed by the presence and prevalence of the amount of medium- and high-temperature inert forms of Hg. According to the relations of Hg content, its forms and groups, as well as correlation ratio density between them, 6 soil and alluvium condition indicators were developed. Key indicators of diagnostics results based on its information value are the following factors: Endogenous supply, geochemical activity and Hg mobility. With regard to the combination of variability in values, the total amount of Hg, the genesis and intensity of its accumulation (natural or anthropogenic), the ranking scales of ecological and hygienic condition of the land areas and surface water bodies were also developed. As a result, the information value of mercury contamination of land significantly increased based on this approach to Hg rationing. At the assessments sites the following areas were identified: outbreaks of underlying Hg emanations on the landscape surface - dispersion halos in the areas of the crust fracture (the dome of the Astrakhan gas condensate field); environmentally dangerous (sometimes even at a low total content of Hg) parts of cities, towns, their districts, as well as beds of watercourses and water reservoirs bottom (the Volga river valley and delta, the Lefortovo quarter in Moscow). Threshold and background distribution of gross Hg content was also detected = 0,2-0,3 mg / kg. Its magnitude is consistent with domestic and abroad safe levels of Hg concentration in soils = 0,3-0,4 mg / kg. The approach enables the differentiation of the environmental hazard lands. Technology approach can be used in the development of normative Instrument for the diagnosis of environmental and sanitary conditions of the territories in the Classifications of hazardous waste, decontamination of territories, water areas and land zoning according to the criteria of natural or anthropogenic Hg accumulation