This paper presents the results of a greenhouse experiment conducted on the humus horizon of a sod–podzolic sandy loam soil (Albic Retisol) contaminated with heavy metals due to the past application of sewage sludge as a fertilizer. The soil was used to cultivate vegetables and forage grasses; however, over the past 10 years, it lay fallow. The experiment was conducted to examine the effect exercised by rhizospheric bacteria of the genus Pseudomonas on biomass of spring wheat plants and the inflow of micro- and macroelements into their vegetative organs and root systems. As a result of bacterial inoculation, the biomass of wheat plants increased by 10–12

The results of a vegetation experiment on the humus horizon of soddy-podzolic sandy loamy soil (Albic Retisol), which was contaminated with heavy metals as a re sult of sewage sludge as a fertilize r, are presented. The soil was used for growing vegetables and forage grasses but has been abandoned for the last 10 years. In the experiment, the effect of rhizospheric bacteria of the genus Pseudomonas on biomass and the entry of micro- and heavy metals into the vegetative organs and root system of spring wheat plants was studied. Under the influence of inoculation with bacteria, the biomass of wheat plants increased by 10–12% and the content of the main macro- and microelements in plants changed. The content of Ca, K, Mg, Na and P decreased by 1,5–2 times in the vegetative part of wheat plants inoculated with P. fluorescens 21 and P. putida 23. The content of macroelements in wheat roots changed little, but the ratio between the content of elements increased in roots and vegetative parts of plants. The distribution of the content of trace elements and HMs was much more contrasting: the content of Cd in the roots of wheat plants exceeded that in the vegetative part of plants by 9 times without treatment with bacteria and by 18 and 11 times aft er inoculation with P. fluorescens 21 and P. putida 23, and in variants with P. fl uorescens 20 by 7 times. A decrease in the content of Cd in the vegetative part of wheat plants was noted, by 2 times upon inoculation with P. fluorescens 21 and by 1,5 times for variants with P. putida 23. The content of Zn in the aerial parts of plants also decreased upon inoculation with P. fluorescens 21 and by 1,8 times for variants with and P. putida 23 by 1,4 times. An increase in the ratio of the content of elements in the roots and vegetative mass of plants indicates an increase in the resistance of plants to the toxic effect of heavy metals and the barrier function of the roots.

Impact of genus Pseudomonas bacteria on fractional composition of nickel compounds in artificially contaminated agro-gray soil and yield of spring wheat was studied in pot experiment. Plants were grown up to booting stage with NiCl2·6H2O contamination at a rate of 300 Ni/kg of soil against background of NPK fertilization. Distribution of nickel in soil fractions isolated by the method of successive selective extractions has been established. Nickel content in plants after combustion in mixture of HNO3:HClO4 (2:1)and in soil fractions was determined by inductively coupled plasma emission-optical spectrometry. Application of bacteria increased plant resistance to elevated nickel concentration and increased yield, significantly reducing heavy metal phytotoxicity. Bacteria increased nickel content in exchangeable and specifically sorbed fractions and, to a lesser extent, in fractions associated with organic matter and ferruginous minerals, and reduced metal content in residual fraction. Bacteria increased nickel uptake from soil by plant shoots due to increase in yield, without changes or increase in plant metal content. Thus, bacteria increased phytoextraction - cleaning soil from heavy metal. Nickel uptake by plants was increased due to increase in its bioavailability, mainly in exchangeable and specifically sorbed fractions.

The most promising areas of ecological assessment, regulation, and quality management of soils and lands include in-depth study of their ecological functions and the role of the anthropogenic factor in the formation of a lands’ natural complex established within the boundaries of specific land plots, considering the natural conditions, type of natural-resource use management, and direct–inverse relationships with adjoining environmental segments; study of natural relations between the soil cover and subsurface geological layers; determination of permissible changes in soil quality due to petroleum contamination and the forest and peat harvesting taking into account the prospects of natural self-repair (regeneration) of landscapes; study of direct and inverse relationships among soils, aquatic environments, and semi-aquatic landscapes exposed to contamination of lands; identification of functional relationship between the state of soils and the quality of atmospheric air; and insight into aspects of soil interface with other environmental compartments and the production and consumption waste. Analysis of the existing laws aimed at protecting soil as an environmental compartment suggests that the structure of environmental-protection legislation that incorporates in its framework the federal laws regulating the protection of environmental compartments contains gaps, and so a soil-protection law needs to be developed.

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 sludge before 1990, then fodder grasses were grown for 20 years, after that the soil was left for 10 years under fallow. In the experiment, the influence of rhizosphere bacteria of the Pseudomonas genus on the mobility and fractional composition of the compounds of heavy metals: Cu, Zn, Cd, Ni, and Pb in the soil and their entering into the vegetative organs and root system of spring wheat were studied. Under the influence of inoculation with bacteria, the content and ratio of heavy metals compounds in the experimental soil changed with an increase in the contents of mobile Cd and Cd bound with organic matter; and Cu, Ni, Pb, also Zn to a lesser extent, bound with organic matter and iron compounds. At the same time, the contents of Cd and Zn d in the vegetative mass of wheat decreased, and the ratios between the contents of the elements in roots and vegetative mass became wider, which indicated an increase in the plant tolerance towards toxic effect of heavy metals and in the barrier function of the roots.

A theoretical equation describing concentrations of microelement compounds entering the soil with atmospheric precipitation as functions of depth and time was validated using data on the long-time (1967, 1995, 2006, and 2013) dynamics of Cu, Ni, and Mn compounds in the soil profile under artificial phytocoenoses developing in soil lysimeters of Moscow State University. The obtained results indicate that this analytical model can be used to forecast the content of heavy metals in the soil profile.

The operation of stationary soil lysimeters is largely determined by the areal and vertical limitations of the soil mass. The areal spatial limitations of large lysimeters operating at the Moscow State University Soil Station and the proximity of phytocoenoses developing in them to each other contribute to the additional transport of plant litterfall by wind, while the vertical limitations eliminate the role of groundwaters and their soil-forming effects. The absence of lateral subsurface flow that is typical for natural landscapes and the increased inflow of alkaline-earth elements with atmospheric precipitation and dust reduce the manifestation of the eluvial–illuvial process. Comparative analysis of lysimetric waters in 1967–1968 and in 2014–2015 shows a significant increase in concentrations of such cations as calcium, sodium, magnesium, and potassium and such anions as chloride and sulfate over this period. The local spatial geochemical contrast of lysimetric waters caused by the impact of deicing agents does not affect the relative migration capacity of elements. Based on their biogeochemical accumulation levels in the soil, macroelements form the following series Ca > K > Al > Mg > N; microelements: Zn > Sr > Cu > Ba. The above patterns persist in all types of lysimeters. The calcium concentration in soils increases in the series: broadleaf forest > mixed forest > spruce forest > black fallow. The increased accumulation of elements in soils of spruce forests correlates with the humus type (moder-like) formed under them; this humus type is determined by the combination of coniferous and deciduous litterfall.

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 fields (Chashnikovo, Moscow oblast) with different contents of organic carbon (C org 3.86 and 1.30%) and different fertility levels using indicators of acute and chronic phytotoxicity. At the same level of polymetallic contamination, the responses of test plants to the presence of high concentrations of HMs and potential remediants (lignohumate and biochar) in soils of the same type with different C org contents noticeably differ with respect to plant growth parameters and metal accumulation in the phytomass. The HMs contamination of low-fertile soil leads to the complete death of plants in the pot experiment, while plants on highly fertile soil continued to develop until flowering with only slight deviations from the control. Experimental data on the contents of total and water-soluble forms of HMs and nutrients in the studied soils are presented. The relationships between the chemical composition of soils and the results of phytotests have been found using the principal component analysis. It is shown that the threefold difference in the content of C org between the soils of the same texture and acidity (pH) result in significantly different response of test plants to the same concentration of HMs. The necessity of correcting the standards for the permissible concentration of HMs in soils with due account for the C org content in addition to pH and texture is discussed.

Sewage sludge that was added to sod–podzolic sandy loam soils 28 years ago determines an increased content and mobility of Zn, Cd, Cu, and Ni compounds and this is most typical for Cd and Zn. Arable soil horizons are most severely polluted, which indicates a low migration rate of heavy metal compounds. The latter are slightly removed from soils by intrasoil flow. This is determined by their chemical properties: low solubility of their compounds and adsorption by mineral and organic soil components, as well as neutral pH values of the soils themselves. Plants grown on contaminated soils are characterized by an increased concentration of heavy metals, which varies from 5 to 7 times, depending on the species of plants and their ability to accumulate heavy metals.

The experiment has shown that in soils contaminated by heavy metals, the boundary metal concentrations, above which ecotoxicity evidences are recorded, are different for the test plant and microbial community. Respiration inhibition in the studied soils occurs at higher doses of Pb, Zn, and Cd than a decrease in germination and length of white mustard ( Sinapis alba ) seedlings. Cd compounds and a complex of contaminants are the most toxic for both test plants and microorganisms. Concentrations of heavy metals, exerting a significant adverse impact on test plants and soil microbial community, have been revealed for soddy-podzolic, gray forest, leached chernozemic, and chestnut soils. With respect to the resistance to the contamination by heavy metals, the studied soils may be arranged in the following sequence: leached chernozem (Luvic Chernozem (Loamic, Aric, Pachic)) > gray forest soil (Eutric Retisol (Loamic, Aric, Cutanic, Ochric)) > chestnut soil (Haplic Kastanozem (Loamic, Aric)) > soddy-podzolic soil (Eutric Albic Retisol (Loamic, Aric, Cutanic, Differentic, Ochric)). At the contamination by Pb, Zn, and Cd acetates, the increase in the content of their mobile compounds is much greater as compared to their total content. The highest mobility of Pb, Zn, and Cd occurs at their simultaneous input to the soil.

Concentrations of heavy metals (HM) that may have a significant negative impact on plants and soil microbiota have been identified at different pollution levels for sod-podzolic, gray forest, leached chernozem and chestnut soils. The investigated soils can be arranged in descending resistance to HM in the following order: leached chernozem, gray forest soil, chestnut, sod-podzolic soil. A comparison of the results of phytotoxicity determination in growing plants on soils and on soil extracts showed that phytotoxicity on soils polluted with HM appears at lower concentrations than on soil extracts. This is a consequence of low solubility of heavy metal compounds that are strongly sorbed by the mineral and organic components of soils, and also remain in the form of poorly soluble compounds.

For the first time, a theoretical equation is derived for the concentration of microelements entering the soil with atmospheric precipitation as a function of depth and time; it was tested with data on the longterm dynamics of certain metals (copper, nickel, and manganese) in the soils of Moscow State University lysimeters under different types of plantations.