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The ecotoxicity of tellurium (Te) compounds (oxide and nitrate) is assessed by changing the biological properties of soils of contrasting properties: Haplic Chernozem (Loamic), Eutric Cambisol, and Eutric Arenosol. Soil stability was assessed by the most sensitive and informative biological indicators: microbiological (total number of bacteria), biochemical (catalase and dehydrogenase activity), and phytotoxic (changes in the length of wheat roots and shoots). Te contamination was simulated at concentrations of 0.5, 1, 3, 10, and 30 possible permissible concentrations (PPC). It has been established that already at minimum concentrations of Te (0.5 and 1 PPC), the biological indicators of soils decrease. As a rule, a direct relationship between Te concentration and the degree of deterioration of the studied soil properties was observed. Te nitrate showed higher ecotoxicity than oxide. A stronger negative effect of Te contamination was manifested 10 and 30 days after contamination. After 90 days, the restoration of the biological properties of the soils was observed. Haplic Chernozem (Loamic) showed greater resistance to Te contamination than Haplic Cambisols Eutric and Eutric Arenosol. The obtained results can be used to predict environmental risks from soil contamination with Te and to develop maximum permissible concentrations of Te in soils of contrasting properties.

The intensive use of petroleum hydrocarbon products has made them priority environmental pollutants. When petroleum hydrocarbons enter the soil, a change in physical, chemical, and biological properties is observed. The natural restoration of oil-contaminated soils is a lengthy process; therefore, remediation is often required. The aim of this study is to assess the change in the ecological state of haplic chernozem soil contaminated with oil, fuel oil, and gasoline after remediation. The indicators of soil biological activity, such as phytotoxicity (germination, length of shoots and roots), the activity of oxidoreductase enzymes (catalase and dehydrogenases), and the total number of bacteria were studied. The effects of nitroammophoska fertilizer, sodium humate, biochar, and the biofertilizer “Baikal EM-1” on the ecological state of soils contaminated with oil, fuel oil, and gasoline were studied. Pollution with oil, fuel oil, and gasoline decreased the values of all biological indicators. The most sensitive indicator was the length of radish roots in soils polluted with oil, gasoline, and fuel oil after remediation with nitroammophoska and Baikal EM-1 addition. The length of roots was the most sensitive indicator when remediation was performed with biochar and sodium humate added to soil contaminated with oil and gasoline, and with contamination of haplic chernozem soil with fuel oil, the total number of bacteria was the most sensitive indicator. The most effective ameliorant to phytotoxicity indicators for oil pollution was a 1 D dose of biochar, for fuel oil it was 1 D biochar and 2 D sodium humate, and for gasoline it was a 2 D dose of biochar and Baikal EM-1. All ameliorants at most of the studied doses increased dehydrogenase activity, but increased catalase activity only in some cases. An increase in the total number of bacteria in oil-contaminated soils was promoted by biochar and nitroammophoska at a dose of 2 D. Nitroammophoska was the most effective in ameliorant in soils contaminated with fuel oil; in soils polluted with gasoline, all doses of ameliorant increased the number of bacteria equally. The stimulating effect of ameliorants on biological activity of oil-contaminated haplic chernozem were in the following sequence: nitroammophoska > biochar > sodium humate > Baikal EM-1. The 2 D biochar dose was most effective. The stimulation of biological indicators by ameliorants when soil was contaminated with fuel oil were in the following sequence: biochar > Baikal EM-1 > sodium humate > nitroammophoska. The same sequence of ameliorant stimulation was observed in soil polluted with gasoline. The results of this study can be used to biodiagnose the ecological state of oil-contaminated soils after remediation.

Lead (Pb) is one of the most common environmental pollutants. Lead has an acute toxic effect on soil biotas and the enzymatic system of soils. The objective of this study is to carry out enzymatic diagnostics of soil health in the European part of Russia after Pb contamination. As a part of the simulation experiment, Pb (at maximum permissible concentrations (MPCs) of 1, 10, and 100) was used to contaminate 12 types of soils in the south and center of the European part of Russia, which differed in their physical and chemical properties. To assess soil health, the activity of oxidoreductases (catalase, dehydrogenases, and cysteine reductase) and hydrolases (invertase, urease, and phosphatase) was studied. Most enzymes were inhibited with increased Pb dosage. The most sensitive soils to Pb contamination, assessed by enzyme activity, are soils of semi-deserts and dry steppes. Cysteine reductase is considered the most sensitive enzyme to Pb contamination. The most informative indicators for Pb contamination were phosphatase, cysteine reductase, and invertase. The P (phosphatase) cycle and the redox enzyme (catalase) also have instability in Pb-contaminated soils. The C (invertase and dehydrogenases) and N (urease) cycles do not change significantly when contaminated with lead. The results of this study can be used for the diagnostics of the condition of soils in different natural areas after Pb contamination.

The development of tourism and leisure infrastructure results in a continuous increase of anthropogenic impact on soils of wet and dry subtropics of the Greatest Caucasus. It is very important for the region to preserve the sustainable functions of soils and ecosystems, maintain a comfortable life and recreation environment create environmentally friendly agricultural products. It is conducted studies to determine the limits of resistance of soils in wet and dry sub-tropics to priority pollutants, especially petroleum hydrocarbons and heavy metals (Pb, Cr, Cu, Ni). It was found that the soils of wet and dry subtropics for resistance by Pb, Cr, Cu, and Ni are located as follows: south-ern chernozem > typical sod-carbonate soil ≥ brown typical soil ≥ brown carbonate soil = brown leached soil ≥ leached sod-carbonate soil = yellow soil >acid brown forest soil ≥ acid brown forest podzolized soil. In terms of the degree of resistance to oil pollution, studied soils create certain series: brown carbonate ≥ brown typical = sod-carbonate leached ≥ sod-carbonate typical > southern chernozem ≥ yellow soil ≥ brown leached soil > acid brown forest soil = acid brown forest podzolized soil. Heavy metals by ecotoxicity to the soils of wet and dry subtropics from the following series: Cr> Cu ≥ Ni = Pb. Based on the degradation of ecological functions of soils, we offer regional standards of the maximum permissible content of Pb, Cr, Cu, and Ni for the main soils of wet and dry subtropics.

It was evaluated the impact of biochar on the petroleum hydrocarbons degradation intensity and the ecological condition of Haplic Chernozem. The study was conducted in the model experiment conditions with Haplic Chernozem contaminated with 5% of petroleum hydrocarbons with application of 10 and 20% biochar. The number of soil bacteria, the activity of catalase and dehydrogenases, germination ability and radish root and shoot length, soil respiration considered to evaluate biological activity. It has been established that 10% biochar application led to intensification of petroleum hydrocarbons degradation up to 17% compare to contaminated soil. Upon adding 10% biochar the СО2 emission increased up to 70-85% on the 18-19th days, then reduced by the 28-30th days till soil emission with the application of biochar in the amount of 20% from soil mass. Activity of dehydrogenases of Haplic Chernozem were stimulated after application of 10% biochar up to 49% compared to control. Biochar application in the doses of 10 and 20% increased the number of soil bacteria up to 209 and 203%, respectively. Application of 20% biochar intensified the germination and early growth of radish seeds. The germination ability, length of radish shoots and roots increased to 44, 66 and 44%, respectively, compare to control. The biochar application in petroleum contaminated soil increased the activity of catalase, dehydrogenases and the number of soil bacteria. Biochar using in doses 10% and 20% contributes to acceleration of petroleum hydrocarbons degradation and improvement of the soil ecological condition.

Nanoparticles are increasingly used in many industrial fields because of their special properties. In this context, several questions arise related to possible negative consequences associated with nanoparticle (NPs) entrance into the ecosystem. The adsorption of NPs by soil can adversely influence its biological properties. In the present article, the influence of Cu, Zn, and Ni NPs on the biological characteristics of Arenosol is considered. Research aimed to study the effect of Cu, Zn, Ni NPs on the biological characteristics of sandy loam chernozem. Copper, Zn, and Ni NPs were added to the soil in concentrations of 100, 1,000, and 10,000 mg kg-1. The effect of NPs on the biological properties of Arenosol was evaluated after 10-day incubation. The biological indices of the ecological condition of the soil, including the germination of radish, the length of the roots, the bacteria population, Azotobacter sp. count, the catalase activity, and dehydrogenases were studied. As a result of this study, it was revealed that the degree of indices changes depending on the concentration of Cu, Zn, and Ni NPs in the Arenosols. Microbiological characteristics (bacteria population, and Azotobacter sp. count) and phytotoxic feature (length of roots and radish germination) properties were most sensitive to contamination compared to the enzyme activity of Arenosol. Based on the soil integral index of a biological state, the strongest inhibitory effect on biological parameters of Arenosols relative to the control was exerted by Cu NPs (lower than control by 48-72%), while the greatest stability in Arenosol was found for Ni NPs (lower than control by 30-55%). The studied biological parameters allow characterizing the severity of nanoparticle exposure on Arenosols. Early diagnostics of the severity of soil contamination by NPs can be successfully used to quickly assess their impact on the soil condition and prevent possible adverse consequences.

The present study was performed for the ecotoxicity assessment of the bismuth (Bi) effect on the biological indicators of soil condition: total number of soil bacteria, catalase activity, dehydrogenases activity and germination of Radish seeds and length of the Radish roots. Three soil types with significantly different resistance ability to heavy metal pollution were studied: Haplic Chernozems Calcic, Haplic Arenosols Eutric and Haplic Cambisols Eutric.Soil contamination of Bi was simulated in the lab (3, 30 and 300 mg kg-1 dry weight). Changes in the biological parameters of the soil were assessed at 10 day treatment. The data obtained showed that the soils contaminated with Bi in South Russia generally characterized by oppression of the biological properties. The total number of bacteria and enzymatic activity (catalase and dehydrogenases) decreased over the Bi contamination. The indicators of phytotoxicity (germination of radish seeds) increase when bismuth 3 and 30 mg kg-1 is added to the soil. The degree of deterioration in biological properties depends on the concentration of Bi in the soil and the period of time after the onset of pollution. Resistance of soil types to Bi pollution can be described by the following decreasing series: Haplic Chernozem Calcic > Haplic Arenosols Eutric > Haplic Cambisols Eutric. The following regional maximum permissible concentrations (rMPC) of Bi have been proposed: Haplic Chernozem Calcic – 8.5 mg kg-1, Haplic Arenosols Eutric – 2.2 mg kg-1 and Haplic Cambisols Eutric – 1.8 mg kg-1.

Soil health is the basis of ecological and food security for humanity. Among the informative indicators of soil health are microbiological indicators based on the intensity of the carbon dioxide release from the soil. The reaction of the microbial community of Haplic Chernozem Loamic, Haplic Arenosols Eutric, and Haplic Cambisols Eutric to contamination with oxides and nitrates of Ag, Bi, Tl, and Te at doses of 0.5, 1, 3, 10, and 30 derived specific permissible concentrations (SPC) was analyzed in the conditions of a vegetation experiment (the exposure period was 10 days). One derived concentration is assumed to be equal to three background concentrations of the element in the soil. The carbon content of microbial biomass in Haplic Chernozem varied between the experimental options from 6 to 218 mg/kg of soil; in Haplic Arenosols, from 3 to 349 mg/kg of soil; and in Haplic Cambisols, from 7 to 294 mg/kg of soil. Microbial biomass was a more sensitive indicator of contamination by the studied pollutants than basal soil respiration. A decrease in specific microbial respiration was found when Haplic Cambisols were contaminated with Ag, Bi, Te, and Tl oxides. Te and Tl nitrates had a significant toxic effect on each type of soil. At the maximum dose of Tl and Te nitrate, a decrease in basal soil respiration of 56–96% relative to the control and an increase in the metabolic coefficient by 4–6 times was found. The toxicity series of heavy metals averaged for all types of soils in terms of microbiological activity was established: Bi > Ag > Te > Tl (oxides) and Te > Tl > Ag > Bi (nitrates). Nitrates of the elements were more toxic than oxides. Soil toxicity due to Ag, Bi, Tl, and Te contamination was dependent on soil particle size distribution, organic matter content, and soil structure. A series of soil sensitivity to changes in microbial biomass and basal soil respiration when contaminated with the studied pollutants: Haplic Arenosols > Haplic Chernozems > Haplic Cambisols. When diagnosing and assessing the health of soils contaminated with Ag, Bi, Tl, and Te, it is advisable to use indicators of soil microbiological activity.

The effect of bacterial strains on certain genera, both independently and in combination with biochar in various options, on petroleum hydrocarbon decomposition in chernozem and the restoration of the ecological state of the soil were studied. To simulate petroleum hydrocarbon contamination, petroleum hydrocarbons were introduced into soil in the amount of 5% of soil weight. Strains of Bacillus and Paenibacillus bacteria (in recommended and increased doses × 100) and biochar (1% of soil weight) were introduced into contaminated soil separately and together. It was found that after 30 days, the oil content decreased with the joint introduction of an increased dose of Bacillus, Panibacillus and biochar by 64%, as well as with the inoculation of biochar with Bacillus and Panibacillus bacteria at the recommended dose by 67%. The introduction of biochar, inoculated with BP and BP × 100, contributed to an increase in the intensity of CO2 emission compared to the background by 5–10%. With the joint introduction of BP + B, stimulation was 70%, with an increase in the concentration of BP × 100–115%. The preparation BP and BP × 100 introduced with biochar stimulated the activity of the enzyme by 49 and 61%; with the preinoculation of BP in biochar, stimulation was 27% relative to the background value. The most informative biological indicators when introducing ameliorants of biochar, Bacillus and Paenibacillus were the total number of bacteria, the length of the barley roots and the catalase activity, demonstrating the greatest sensitivity. The results of the study should be used for the remediation and biomonitoring of the state of oil-contaminated soils.

Soil contamination with such rare heavy metals as silver (Ag), bismuth (Bi), tellurium (Te), and thallium (Tl) leads to disruption of its agricultural and ecological functions. Each of these rare heavy metals has a different level of soil toxicity, which affects the ecological state of the soil and its recovery degree estimated by biological indicators. The work objective is to assess the ecotoxicity of oxides and nitrates of silver, bismuth, tellurium, and thallium by biological indicators of Haplic Chernozem. Under the conditions of a laboratory simulation experiment, silver, bismuth, tellurium, and thallium were introduced into the samples of soil. The ecological state of the soil for each incubation period was assessed by the activity of soil enzymes (catalase and dehydrogenases), the intensity of seed development in polluted soil (the length of shoots and roots of winter wheat), and microbiological indicators (the total number of bacteria and Azotobacter sp. abundance). For 90 days, when contaminated with oxides of silver, bismuth, tellurium, and thallium, the most sensitive biological indicator was the length of wheat roots; when contaminated with nitrates, the total number of bacteria was the most sensitive biological indicator. The most informative biological indicator for contamination with both chemical forms of rare elements (silver, bismuth, tellurium, and thallium) was the Azotobacter sp. abundance. The most ecotoxic elements among those studied were thallium and tellurium, both in the form of oxides and nitrates. The results of the study may be useful for biomonitoring and diagnostics of the state of soils contaminated with silver, bismuth, tellurium, and thallium.

Sustainable agriculture is only possible if the agroecological services of the soil are preserved. Soil contamination with rare elements such as silver (Ag), bismuth (Bi), tellurium (Te), and thallium (Tl) is less studied, but their toxicity is no less high than in other heavy metals. Activity of soil enzymes is of great importance for the healthy functioning of soils, agroecosystem services, and their fertility. It is necessary to assess the ecological state of black soil using the most sensitive and informative indicators of the state of soils—their enzymatic activity. The objective of this research was to evaluate changes in activity of five priority soil enzymes (catalase, dehydrogenases, invertase, phosphatase, and urease) when contaminated with oxides and nitrates of Ag, Bi, Te, and Tl in a laboratory model experiment. The integral toxicity of nitrates and oxides of Ag, Bi, Te, and Tl was assessed by the integrated index of soil enzymatic activity. A comparison of the toxicity of oxides and nitrates of each element, according to the integrated index of soil enzymatic activity, allowed us to establish that Ag oxide is more toxic than Ag nitrate; Bi oxide is equivalent in its toxicity to Bi nitrate; and Tl and Te oxides are less toxic than Tl and Te nitrates. When contaminated with oxides, the most informative indicators are activity of invertase (Ag), urease (Bi, Tl), and phosphatase (Te). When contaminated with nitrates, the most informative indicators are activity of phosphatase (Ag) and invertase (Bi, Tl, and Te). Activity of phosphatase and catalase are the most sensitive to contamination by oxides and nitrates of Ag, Bi, Tl, and Te, and dehydrogenases, invertase, and urease are the least sensitive.

An increase in the penetration of metal-based nanoparticles (NPs) into the environment requires an assessment of their ecotoxicity as they impair the critical activity of plants, animals, bacteria, and enzymes. Therefore, the study aimed to observe the effects of metal-based NPs, including copper (Cu), nickel (Ni), and zinc (Zn), on the Cambisols, which cover a significant part of the earth’s soil and play an important role in the biosphere. Metal-based NPs were introduced into the soil at concentrations of 100, 1000, and 10,000 mg/kg. The biological properties of the soil are being investigated as the most sensitive to external contamination. The highest ecotoxicity of the studied pollutants introduced into the soil at the same concentrations was shown by Cu (up to 34%) and Zn (up to 30%) NPs, while Ni NPs showed less (up to 22%). Microbiological (total number of bacteria, Azotobacter sp. abundance) and phytotoxic properties (radish seed germination and length of roots) of Cambisols were more sensitive (22–53%) to pollution by NPs of Cu, Zn, and Ni, while enzymatic activity (catalase and dehydrogenases) showed less sensitivity (14–32%). The present results could be useful for biomonitoring the state of contaminated soils, especially by NPs.

In recent years, silver nanoparticles (AgNPs) are increasingly used in various industries due to their antibacterial properties, which lead to an increase in pollution of the environment and soil ecosystems. However, the ecological effects of soil pollution by AgNPs were poorly studied than that with AgNPs of other metal-based NPs. The aim of this study is to assess the influence of AgNPs on the biological properties of Haplic Chernozem. Silver was introduced into the soil in the form of AgNPs with a concentration of 0.5; 1; 5; 10; 50, and 100 mg/kg in laboratory conditions. The influence of AgNPs on the biological properties of Haplic Chernozem was assessed 30 days after contamination. The degree of reduction in biological properties depends on the AgNPs concentration in the soil. This study showed that the sensitivity to contamination by AgNPs in the total number of bacteria and enzymatic activity was more than that in the abundance of bacteria of the genus Azotobacter. The integrated index of biological state (IIBS) of Haplic Chernozem was decreased by contamination with AgNPs. Silver nanoparticles in the concentration of 10 mg/kg caused a decrease in the indicator by 13% relative to the control. It also decreased IIBS by doses of 50 and 100 mg/kg by 22 and 27% relative to the control. All used biological indicators could be used for biomonitoring, biodiagnosis, bioindication, and regulation of ecological condition of soil contamination by AgNPs.

Petroleum hydrocarbon contamination disrupts ecological and agricultural soil functions. For their restoration, bioremediation agents of various natures are used (nonorganic or organic fertilizers, bacterial preparations, adsorbing agents) featuring different remediation mechanisms (adsorption or biostimulation of petroleum hydrocarbon decomposition). The objective of this research is the assessment of the ecological condition of petroleum hydrocarbon-contaminated Haplic Chernozem Calcic after the application of bioremediation agents of various natures. The influence of glauconite, nitroammophos, sodium humate, the bacterial preparation “Baikal EM-1”, and biochar on the intensity of petroleum hydrocarbon decomposition and the ecological condition of Haplic Chernozem Calcic was analyzed. The ecological condition of Haplic Chernozem Calcic was assessed based on the residual content of petroleum hydrocarbons in soil and the following biological parameters: changes in the number of soil bacteria, activity of catalase and dehydrogenases, soil respiration (CO2 emission), germinating ability, lengths of roots and shoots, and integrated index of the biological state. The minimum concentrations of residual petroleum hydrocarbons in soil were observed after the use of biochar (44% from initial content) and glauconite (49%). The biological properties of soils were affected in different ways. Soil respiration was stimulated by 3-6-fold after adding nitroammophos. Indices for the intensity of the early growth and germination of radish in soil with glauconite, sodium humate, and biochar were increased by 37–125% (p < 0.01) compared with the reference value. After the application of biochar, sodium humate, and “Baikal EM-1”, the number of soil bacteria was 66–289% higher (p < 0.01) than the reference value. At the same time, the activities of catalase and dehydrogenases were inhibited by up to 35% in variants with bioremediation agents and petroleum hydrocarbons relative to the reference values. The maximum stimulation of the biological activity (as the integrated index of the biological state (IISB)) of Haplic Chernozem Calcic was observed after applying sodium humate and biochar, with 70 and 66% (p < 0.01) increases from the reference value, respectively. Considering the net cost of bioremediation agents, the maximum cost efficiency is achieved with “Baikal EM-1”, sodium humate, and biochar: 110, 527, and 847 USD·103/ha, respectively. After using Baikal EM-1”, sodium humate, and biochar, the ecological state of Haplic Chernozem Calcic was restored.