Экологически безопасные концентрации никеля в почвах Центрального Предкавказья и Кавказа

Abstract

An extensive number of enterprises are located on the territory of the Central Ciscaucasia and the Caucasus. Emissions from these industrial facilities enter the atmosphere, settle on the soil, drain into reservoirs. Among the main pollutants is the heavy metal nickel (Ni). Nickel is at the same time a vital chemical element, and, at the same time, it can act as a toxicant metal that can cause mutations. Its biological role depends on the concentration of metal in the soil. The aim of the study is to establish ecologically safe concentrations of nickel for the soils of the Central Ciscaucasia and the Caucasus. Materials and methods of research. Nickel oxides were added to soil samples at a dose of 100, 1000, and 10000 mg/ kg and incubated in plastic vessels at a temperature of 20-22 °C and 55-60% soil moisture. In this work, the biological parameters of soils were determined on the basis of methods generally accepted in soil science and ecology (phytotoxicity of soils, total number of bacteria, catalase activity, dehydrogenase activity, abundance of Azotobacter bacteria, changes in cellulolytic activity). According to the indicators of microbiological, biochemical and phytotoxic parameters, we calculated IIBS - an integral indicator of the biological state of the soil The results obtained and their discussion. Based on the analysis of the soils of the Central Ciscaucasia and the Caucasus, the following were ranked according to their resistance to nickel contamination: ordinary chernozem (91) >chernozem podzolized (mountain) (84) ≥ chernozem typical (mountain) (83) ≥ chernozems leached (mountain) (82) = mountain-meadow chernozem-likes (82) ≥ mountain-meadow sod-peaty (80) ≥ mountain meadow-steppe (78) ≥ sod-calcareouses (76) ≥ dark gray forest(75) ≥ mountain-meadow soddy (71) ≥ brown forest weakly unsaturated(68).The greater the soil IPBS, the more resistant the biological indicators of this type of soil are to nickel contamination. The study made it possible to calculate the regional maximum permissible concentrations (rMPC) of Ni in the soils of the Сentral Ciscaucasia and the Caucasus. For this purpose, regression equations were constructed reflecting the dependence of the IIBS of each studied soil on the content of Ni in it. The rMPC of Ni in ordinary chernozem is 170 mg/kg, in typical chernozem (mountain) and mountain meadow chernozem-like soil — 160 mg/kg, in podzolized chernozem (mountain) — 150 mg/kg, in leached chernozem and mountain meadow turf-peat soil — 130 mg/kg, in sod—carbonate and dark gray forest — 120 mg/ kg, in mountain meadow-steppe — 145 mg/kg, in mountain meadow turf — 140 mg/kg, in brown forest slightly unsaturated — 100 mg/kg.