Assessment and regulation of the ecological state of soils in the impact zone of mining and metallurgical enterprises of Norilsk Nickel Company

An assessment of the ecological state of soils has been performed in the area of mining and metallurgical enterprises of Norilsk Nickel Company with respect to the level of soil contamination by heavy metals, the state of the vegetation, and the biological activity of the soils. The territory within 4 km from Norilsk is characterized by high concentrations of heavy metals, the absence of trees, and the disturbance of the organic matter mineralization. This zone corresponds to level 5 of the loss of environmental quality. At distances of 4–16 km from the city, the state of the environment corresponds to level 4, and, at distances of 16–25 km, to level 3. In the latter zone, the soils are characterized by increased concentrations of acid-soluble and mobile metal compounds, though the concentrations of water-soluble metal compounds do not exceed the maximum permissible levels; the soil microbiological activity is normalized. The state of the environment at a distance of 25 km from Norilsk is close to level 2. Soil contamination with heavy metals is accompanied by a rise in the portion of Cu, Ni, and Co compounds bound with amorphous iron oxides and hydroxides, as well as in the portion of their mobile forms.     

Ecotoxicological assessment of nickel pollution of soil and water environments adjacent to soddy–podzolic soil

The indicators of functioning of soil microorganisms in soddy–podzolic soil contaminated with Ni compounds show different ranges of soil ecotoxicity. A halving of soil microorganisms' nitrogen-fixing activity has been shown in slightly acidic soddy–podzolic cultivated soil with a Ni concentration of 150 mg/kg and for noncultivated acidic soils with a Ni concentration 100 mg/kg. The reduction of denitrification activity in cultivated soil has been observed with a Ni concentration of 500 mg/kg, and in uncultivated soil it has been observed at a Ni dose of 100 mg/kg. The inhibition of soil respiration in slightly acidic soil occurred only at the highest dose of Ni, 1000 mg/kg, while in the acidic soil it took place at 300 mg/kg. Biotesting based on bacterial luminescence can be used for determination of soil pollution with heavy metals such as Ni, as well as for the assessment of the toxicity of aqueous environments in contact with contaminated soils.     

Soils of Ancient Agricultural Terraces of the Eastern Caucasus

Eurasian Soil Science - The morphological and chemical properties and biological activity of soils on ancient agricultural terraces in the middle-high mountains of the Eastern Caucasus are...     

Influence of Rhizosphere Bacteria on the State of Heavy Metal Сompounds in the Soil–Plant System

Eurasian Soil Science - The results of a greenhouse experiment with the humus horizon of a sandy loamy soddy-podzolic soil are presented. It was contaminated with heavy metals added with sewage...     

Formation of microelemental composition and properties of soils under model phytocenoses in soil lysimeters

The soil formation on noncalcareous loam under different phytocenoses in soil lysimeters (Soil Experimental Station of Moscow State University) for 49 years has led to a decrease in acidity and an increase in the content of organic matter, microelements, and heavy metals in the surface soil layer. The rate of microbial CO₂ emission and the microbial biomass content reached the maximum values under the mixed forest stand followed by the broad-leaved forest, then spruce forests, perennial grasses, and fallow. The minimum values of these parameters were characteristic of the black fallow. The percentage of C_mic in the organic carbon content of the soils under the broad-leaved forest was 2.7; in the mixed forest, spruce forest, fallow, and black fallow, it was 1.9, 1.2, 0.9, and 3.3, respectively. The maximum accumulation of heavy metals was recorded in the litter and at the depth of 2–15 cm. The Zn content in the soils under the woody vegetation was 18–20 times higher than in the parent mantle loam; in the soils under perennial grasses and in the plots without plants, it was 14–16 and 5 times higher, respectively. The biogenic accumulation and aerial dust transfer of heavy metals are responsible for the differences in their accumulation between the soils of the model phytocenoses and soils without vegetation. The content of elements in the dust exceeded that in the parent loam by 200–300 times for Zn, 20–40 for lead, 6–60 for nickel, and 20–30 times for strontium and barium. The composition and amount of dust determined the trends in these elements of accumulation in the soils.     

Biogeochemistry of heavy metals in contaminated excessively moistened soils (Analytical review)

The biogeochemical behavior of heavy metals in contaminated excessively moistened soils depends on the development of reducing conditions (either moderate or strong). Upon the moderate biogenic reduction, Cr as the metal with variable valence forms low-soluble compounds, which decreases its availability to plants and prevents its penetration into surface- and groundwater. Creation of artificial barriers for Cr fixation on contaminated sites is based on the stimulation of natural metal-reducing bacteria. Arsenic, being a metalloid with a variable valence, is mobilized upon the moderate biogenic reduction. The mobility of siderophilic heavy metals with a constant valence grows under the moderate reducing conditions at the expense of dissolution of iron (hydr)oxides as carriers of these metals. Zinc, which can enter the newly formed goethite lattice, is an exception. Strong reduction processes in organic excessively moist and flooded soils (usually enriched in S) lead to the formation of low-soluble sulfides of heavy elements with both variable (As) and constant (Cu, Ni, Zn, and Pb) valence. On changing aquatic regime in overmoistened soils and their drying, sulfides of heavy metals are oxidized, and previously fixed metals are mobilized.     

Self-purification of loamy-sandy agrosoddy-podzolic soils polluted by sewage sludge in the eastern Moscow region

For 12 years, the contents of Zn and Cd compounds in the plow horizons of the loamy-sandy agrosoddy-podzolic soils polluted due to the application of sewage sludge decreased by 2 times; the Cu and Ni concentrations became lower by 1.5 times. The thickness of the polluted layer increased from 20 to 45 cm. The reserves of Cd, Zn, and Cu in the 0- to 50-cm-thick layer decreased, on the average, by 22, 14, and 9%, respectively. The changes in the fractional composition of the metal compounds were found. The sum of the Cu and Ni compounds increased due to the fraction of these metals bound with organic matter; for the Cd compounds, due to the weakly adsorbed fraction.     

Phytotoxicity of Heavy Metals in Contaminated Podzolic Soils of Different Fertility Levels

Eurasian Soil Science - We have compared the impact of heavy metals (HMs: Cu 660 + Zn 1100 + Pb 650 mg/kg) on agrosoddy-podzolic soils (Albic Retisols (Loamic, Aric, Cutanic, Ochric)) of two arable...     

Effect of atmospheric precipitation on microelement composition of soils in model ecosystems of soil lysimeters

Variations in the microelement composition of soils of lysimeters under the effect of atmospheric precipitation and model phytocenoses over the 49-year-long period were studied. A drop in acidity and a rise in the content of organic matter, microelements, and heavy metals in the surface soil layer were revealed. The greatest accumulation of heavy metals was seen in the forest litter and at a depth of 2–15 cm. In comparison with the original loam, zinc content is higher 18–20 times under tree vegetation, 14–16 times under grass communities, and five times in bare soils. The difference in the content of heavy metals between the soils under model phytocenoses and soils without plant cover is explained by their biogenic accumulation and input with dust precipitated on leaves. Dust amount and composition determine the regularities of the accumulation of the elements in soils.     

Paleosols of kurgans of the Early Iron Age in the Transural steppe zone

Paleosol studies of archaeological monuments of different ages have been conducted on the Transural Plateau. The morphological and physicochemical properties of paleosols under burial mounds (kurgans) of the Early Iron Age (the fifth and fourth centuries BC) were compared with the properties of background surface soils. A paleosol of the Savromat epoch (2500 BP) is characterized by high contents of gypsum and soluble salts. The presence of humus tongues in its profile attests to the aridity and continentality of the climatic conditions during that epoch. Paleosols buried under kurgans of the Late Sarmatian epoch and the Hun epoch (about 1600 BP) are characterized by a higher content of humus and greater depth of the carbonate horizon, which attests to the humidization of climatic conditions. The evolution of soils as related to climate dynamics in the first millennium BC and the first millennium AD is characterized.