Ecotoxicity of AgNPs according to the state of biota

The work objective is to evaluate the ecotoxicity of silver nanoparticles (AgNPs) according to the state of the biota of Haplic Chernozems Calcic. Contamination of Haplic Chernozems Calcic with 10 nm AgNPs in concentrations of 0.1, 0.5, 1, 5, 10, 50, and 100 mg/kg was simulated in laboratory conditions. In this study, biodiagnostical methods were used to assess the ecotoxic effect of AgNPs on soil biota: the activity of catalase, dehydrogenases, invertase, phosphatase, urease, the total number of bacteria, the Azotobacter sp. abundance, germination, and length of radish roots. The response of soil biota to exposure to AgNPs was assessed by the difference between the values in contaminated and uncontaminated soil. It was found that the more silver nanoparticles were introduced into the soil, the stronger the ecotoxic effect on the biota. The highest sensitivity degree to contamination of Haplic Chernozems Calcic with AgNPs was recorded for the total number of bacteria. The critical value of the AgNPs content in Haplic Chernozems Calcic, which is 0.4 mg/kg has been developed

Approaches to the development of environmental standards for the content of petroleum hydrocarbons and Pb, Cr, Cu, Ni in soils of Greatest Caucasus

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

Assessment of Ecological Condition of Haplic Chernozem Calcic Contaminated with Petroleum Hydrocarbons during Application of Bioremediation Agents of Various Natures

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 p p 3/ha, respectively. After using Baikal EM-1”, sodium humate, and biochar, the ecological state of Haplic Chernozem Calcic was restored

Assessment of Ecological Condition of Haplic Chernozem Calcic Contaminated with Petroleum Hydrocarbons during Application of Bioremediation Agents of Various Natures

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

Assessment of the Ecotoxicity of Ag, Bi, Te and Tl According to the Biological Indicators of Haplic Chernozem

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

Estimation of the Enzymatic Activity of Haplic Chernozem under Contamination with Oxides and Nitrates of Ag, Bi, Te and Tl

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

Assessment of the Ecotoxicity of Ag, Bi, Te and Tl According to the Biological Indicators of Haplic Chernozem

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

Assessment of the ecotoxicity of bismuth at the phytotoxicity of soils

The results of the study of the ecotoxicity of bismuth on ordinary chernozem, brown forest soils and sierosands along the length of radish roots are presented. Small doses of 1.5-3 mg/kg of bismuth stimulated the growth of radish roots on ordinary chernozem. The maximum toxicity of bismuth carbonate and nitrate at a dose of 300 mg / kg was established on sierosands (reduction in the length of radish roots by 43% of the control). Bismuth carbonate 300 mg/kg showed the greatest toxicity when applied to ordinary chernozem and brown forest soil and reduced the length of radish roots by 31 and 44% of control, respectively. The series of toxicity ((on radish’s root length) of chemical forms of bismuth for soils forms the following sequence: bismuth carbonate (84) ≥ bismuth nitrate (86) > bismuth oxide (90). The toxic effect of bismuth depends on the form and concentration of bismuth in the soil,the particle-size composition, the reaction of the soil environment and the content of organic matter in the soil

Assessment of the ecological state of haplic chernozem contaminated by oil, fuel oil and gasoline after remediation

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

Soil Organic Carbon Dynamics in Response to Tillage Practices in the Steppe Zone of Southern Russia

Soil organic carbon (SOC) content is a vital indicator for soil health. The use of moldboard (traditional) plowing for many years had led to a prominent decline in the SOC and soil organic matter (SOM) in Southern Russia. Application of no-tillage (NT) is a sustainable alternative to conventional tillage (CT) as it offers an advantage for SOC store. The aim of the study was to assess soil organic carbon dynamics in response to tillage practices in the steppe zone of Southern Russia. The conservation of SOC under different tillage systems (CT and NT) was evaluated in comparison with the soils of the virgin soils (VS) in three different regions of the steppe zone of the Lower Don region (Southern of the European part of Russia). The SOC content under the conditions of CT was significantly lower than that in the VS and demonstrated an inclining trend when using NT technology. We estimate that the transition to NT over an area of 5.5 million hectares will lead to a significant reduction of carbon emissions into the atmosphere (by ~39 × 109 g C/year), thereby SOC deposition will be (~5.1 × 1012 g C) and high economic advantages will be reaped (with cost savings of up to 27%) in the Rostov region of Russia