Exploring sustainable management by using green nano-silver to combat three post-harvest pathogenic fungi in crops

Global crop protection and food security have become critical issues to achieve the 'Zero Hunger' goal in recent years, as significant crop damage is primarily caused by biotic factors. Applying nanoparticles in agriculture could enhance crop yield. Nano-silver, or AgNPs, have colossal importance in many fields like biomedical, agriculture, and the environment due to their antimicrobial potential. In this context, nano-silver was fabricated by Citrus medica L. (Cm) fruit juice, detected visually and by UV-Vis spectrophotometric analysis. Further, AgNPs were characterized by advanced techniques. UV-Vis spectroscopic analysis revealed absorbance spectra at around 487 nm. The zeta potential measurement value was noted as -23.7 mV. Spectral analysis by FT-IR proved the capping of the acidic groups. In contrast, the XRD analysis showed the Miller indices like the face-centered cubic (fcc) crystalline structure. NTA revealed a mean size of 35 nm for nano-silver with a 2.4 × 108 particles mL-1 concentration. TEM analysis demonstrated spherical Cm-AgNPs with 20-30 nm sizes. The focus of this research was to evaluate the antifungal activity of biogenic AgNPs against post-harvest pathogenic fungi, including Aspergillus niger, A. flavus, and Alternaria alternata. The Cm-AgNPs showed significant antifungal activity in the order of A. niger > A. flavus > A. alternata. The biogenic Cm-AgNPs can be used for the inhibition of toxigenic fungi.

New approach to soil management focusing on soil health and air quality: one earth one life (critical review)

Soil plays a key role in ecosphere and air quality regulation. Obsolete environmental technologies lead to soil quality loss, air, water, and land systems pollution. Pedosphere and plants are intertwined with the air quality. Ionized O2 is capable to intensify atmosphere turbulence, providing particulate matter (PM2.5) coalescence and dry deposition. Addressing environmental quality, a Biogeosystem Technique (BGT*) heuristic transcendental (nonstandard and not direct imitation of nature) methodology has been developed. A BGT* main focus is an enrichment of Earth's biogeochemical cycles through land use and air cleaning. An intra-soil processing, which provides the soil multilevel architecture, is one of the BGT* ingredients. A next BGT* implementation is intra-soil pulse continuously discrete watering for optimal soil water regime and freshwater saving up to 10-20 times. The BGT* comprises intra-soil dispersed environmentally safe recycling of the PM sediments, heavy metals (HMs) and other pollutants, controlling biofilm-mediated microbial community interactions in the soil. This provides abundant biogeochemical cycle formation and better functioning of the humic substances, biological preparation, and microbial biofilms as a soil-biological starter, ensuring priority plants and trees nutrition, growth and resistance to phytopathogens. A higher underground and aboveground soil biological product increases a reversible C biological sequestration from the atmosphere. An additional light O2 ions photosynthetic production ensures a PM2.5 and PM0.1 coalescence and strengthens an intra-soil transformation of PM sediments into nutrients and improves atmosphere quality. The BGT* provides PM and HMs intra-soil passivation, increases soil biological productivity, stabilizes a climate system of the earth and promotes a green circular economy.

Trace Metals and Polycyclic Aromatic Hydrocarbons in the Snow Cover of the City of Nizhnevartovsk (Western Siberia, Russia)

The city of Nizhnevartovsk is one of the centers of oil production in Western Siberia (Russia). A survey of the contents of trace metals and metalloids (TMMs) and polycyclic aromatic hydrocarbons (PAHs) in the snow cover was conducted there. It was aimed to study insoluble particles in the snow where the predominant fraction of pollutants in urban areas is concentrated. In contrast to the background area, the deposition of TMMs in Nizhnevartovsk increases by 1-2 orders of magnitude. The deposition of V and Mn increases by 37 and 88 times, respectively, and the deposition of W increases at most (by 98 times). Abrasion of spikes of winter tires, abrasion of metal parts of vehicles, and combustion of motor fuels cause the pollution with W, Co, and V, respectively. The total content of 12 EPA PAHs in the particulate fraction of snow in the urban area averaged 148.2 ng l^-1, and the deposition rate was 17.0 μg/m². In contrast to the background area, the fraction of high molecular weight 5-6-ring PAHs significantly increases in the city, especially dibenzo(a,h)anthracene (DahA). The indicative ratios of PAHs showed that the snowpack composition was influenced by both petrogenic and pyrogenic sources. The proportion of pyrogenic sources is the highest in the low-rise residential area due to fuel combustion to produce heat and burning of household waste. The impact of motor transport is also major and is manifested in the maximum pollution in areas of heavy traffic. No emissions of PAHs from oil spills from the nearby Samotlor oil field have been identified. It is concluded that the hydrocarbon pollution of the atmosphere from the field weakens during the winter period compared to the warm season. Application of the integral TDF index characterizes the majority (72%) of the studied samples as lowly polluted, 24% of the observation sites are classified as moderately polluted, and one (4%), as highly polluted. The maximum TDF values are observed in the industrial area. The data obtained during the study allowed us to identify the central areas and sites along the roads with the heaviest traffic as the most contaminated areas of the city. This study can be a reference for air pollution monitoring in Nizhnevartovsk.

Intra-soil waste recycling provides safety of environment

Amelioration and remediation technology was developed for phosphogypsum utilization in Haplic Chernozem of South-European facies (Rostov Region). The technology comprises phosphogypsum dispersed application into the soil layer of 20-45 cm during intra-soil milling. In the model experiment, the phosphogypsum doses 0 (control), 10, 20, and 40 t ha^-1 were studied. The Cd thermodynamic forms in soil solution were calculated via the developed mathematical chemical-thermodynamic model and program ION-3. The form of ion in soil solution (or water extract) was considered accounting the calcium-carbonate equilibrium (CCE) and association of ion pairs CaCO₃⁰; CaSO₄⁰, MgCO₃⁰, MgSO₄⁰, CaHCO₃⁺, MgHCO₃⁺, NaCO₃^-, NaSO₄^-, CaOH⁺, MgOH⁺. For calculation of the equilibrium of microelements concentration in soil solution ion including heavy metals (HMs), the coefficient of microelement association k_as was proposed. According to calculations, Cd²⁺ ion in soil solution was mostly bounded to associates CdOH⁺, partly to associates CdCO₃⁰ and CdHCO₃⁺. The calculated k_as of Cd was 1.24 units in the control option of experiment and decreased to 0.95 units at phosphogypsum dose 40 t ha^-1. The ratio of "active [Cd²⁺] to total Cd" reduced from 33.5% in control option to 28.0% in the option of phosphogypsum dose 40 t ha^-1. The biogeochemical barrier for penetration of HMs from soil to plant roots was high after application of phosphogypsum. According to calculation by ION-3, the standard soil environmental limitations overestimate the toxicity of Cd in soil solution. New decision for intra-soil milling and simultaneous application of phosphogypsum was developed to provide the environmentally safe waste recycling.

Metal(loid) nanosorbents in restoration of polluted soils: geochemical, ecotoxicological, and remediation perspectives

Nowadays, the applications of nanomaterials (NMs) are becoming the edge over others and referred as one of the pillars of emerging science and technology. Thereby, a wide array of NMs have been developed along with the products that can be used for the reclamation of contaminated terrestrial ecosystems. The NMs got a great consideration due to their peculiar characteristics and high efficacy. Therefore, this review addresses in depth the ability of metal(loid) NMs as nanosorbents along with their applications in soil remediation. Adsorption is commonly employed for the elimination of innumerable contaminants because of low expenses, reliability, and convenience. The first emphasis of this work will be the use of nanoscale meta(loid) adsorbents for contaminated soil remediation along with their geochemistry. Because NMs mediated soil remediation promises more efficient and cost-effective than conventional methods and can enhance the probability of in situ contaminants remediation. However, the extensive usage of NMs is enhancing their concentrations in the environment and get a route to enter the surrounding flora and fauna that can induce serious concerns due to the lack of absolute understanding regarding NMs interactions with living organisms. Therefore, the second focus of this work will be on the ecotoxicological impacts with special attentions on morpho-physiological alterations in edible plants.

Bioindication of soil pollution in the delta of the Don River and the coast of the Taganrog Bay with heavy metals based on anatomical, morphological and biogeochemical studies of macrophyte (Typha australis Schum. & Thonn)

The results of biogeochemical and bioindication studies on the resistance of natural populations of macrophyte plant-cattail (Typha australis Schum. & Thonn) on the coast of the Taganrog Bay of the Sea of Azov and the sea edge of the Don River delta with regard to local pollution zones are presented. Plant resistance has been assessed through manifestation of their protective functions in relation to heavy metals. An excess in the lithospheric Clarkes and MPC in Zn, Cd and Pb in Fluvisols has been found. The total index of soil pollution (Z_c) has made it possible to identify areas with different categories of contamination within the study area exposed to human impact. High mobility of Zn, Cd, Pb, Cr and Ni in Fluvisols has been revealed, which is confirmed by the significant bioavailability of Zn, Cr and Cd that are accumulated in the macrophyte plant tissues. The absorption of heavy metals by cattail plants is allowed for both the soil and the water of the nearby reservoir, where aquatic systems are a kind of "biological filter" contributing to water purification from pollutants. The impact of the environmental stress factor has been found to be manifested not only in the features of heavy metal accumulation and distribution in plant tissues, but also at the morphological and anatomical level according to the type of prolification. Changes in the cell membranes as well as in main cytoplasmic organelles (mitochondria, plastids, pyroxis, etc.) of the root and leaf cells have been identified, the most significant changes in the ultrastructure being noted in the tissues of leaf chlorenchyma. It is assumed that the identified structural changes contribute to slowing down of the ontogenetic development of plants and reduction in their morphometric parameters when exposed to anthropogenic pollution. Therefore, cattails can be effectively used as biological indicators while determining environmental pressures.

The identification of phytoextraction potential of Melilotus officinalis and Amaranthus retroflexus growing on copper- and molybdenum-polluted soils

The contamination of soils by heavy metals from the mining industry nowadays is one of the greatest threats to environment and human health. The cleaning of polluted soils using cost-effective and eco-friendly methods such as phytoextraction has wide public recognition. Considering the above-mentioned ones, the objectives of the present study were the identification of Cu and Mo accumulation capability and the phytoextraction potential of Melilotus officinalis and Amaranthus retroflexus as well as the determination of the influence of ammonium nitrate and EDTA on phytoextraction effectiveness. The contaminated soil samples for phytoremediation experiments under ex situ conditions were collected from the surroundings of the Zangezur Copper and Molybdenum Combine, Armenia. During the studies, it was found out that M. officinalis and A. retroflexus are capable of growing in polluted soils. M. officinalis grown in polluted soil had greater ability to accumulate heavy metals in roots, while the ability to transport the copper to aboveground parts was more pronounced in A. retroflexus. During the growing of these plant species for phytoextraction of soils contaminated by copper, it is necessary to use chelates, in particular the EDTA, for the enhancement of the effectiveness of phytoextraction process. EDTA due to chelating influence increased the availability of copper for plants and its mobility in them that lead to greater accumulation of this metal in shoots. The application of chelates did not have a significant impact on molybdenum accumulation intensity in plants; therefore, in case of this metal, it is unreasonable to use additional chelating compounds.

The toxic effect of CuO of different dispersion degrees on the structure and ultrastructure of spring barley cells (Hordeum sativum distichum)

Nowadays, nanotechnology is one of the most dynamically developing and most promising technologies. However, the safety issues of using metal nanoparticles, their environmental impact on soil and plants are poorly understood. These studies are especially important in terms of copper-based nanomaterials because they are widely used in agriculture. Concerning that, it is important to study the mechanism behind the mode of CuO nanoparticles action at the ultrastructural intracellular level. It is established that the contamination with CuO has had a negative influence on the development of spring barley. A greater toxic effect has been exerted by the introduction of CuO nanoparticles as compared to the macrodispersed form. A comparative analysis of the toxic effects of copper oxides and nano-oxides on plants has shown changes in the tissue and intracellular levels in the barley roots. However, qualitative changes in plant leaves have not practically been observed. In general, conclusions can be made that copper oxide in nano-dispersed form penetrates better from the soil into the plant and can accumulate in large quantities in it.

Thermodynamic mathematical model of the Kastanozem complex and new principles of sustainable semiarid protective silviculture management

The Kastanozem complex in the dry steppe of southern Russia underlies an artificially-constructed forest strips. Deep ploughing to a depth of 45 cm was used to process the soil prior to planting. Between 20 and 40 cm depth, soil density was high, 1.57 t m^-3. Soil hardness was also high, 440 psi. Soil aggregates greater than 5 cm in size were impermeable to tree roots. The content of such aggregates was high, comprising 35%. The number of tree roots with diameters greater than 0.5 cm that cross the soil profile was as low as 0.15 to 0.3 pcs cm^-2. The soil matric potential signifying water availability was low in the vegetation period -0.9 MPa to a depth of 1.0 m. According to modelling experiments, the main salt components in the soil solution drive the transfer of soil organic matter (SOM) and heavy metals (HM). The composition of the soil solution determined by the calcium carbonate equilibrium (CCE) and the association and complexation of ions. ION-3 software was used to calculate the ion equilibrium in the soil solution. Macro-ions Cа²⁺, Mg²⁺, SO₄^2-, and CO₃^2- partly bonded as ion pairs. Oversaturation of the soil solution with CaCO₃ was calculated according to the analytical content of macro-ion, which was high up to 1000 units, and its value decreased in response to ionic strength, activity, association, complexation, and thermodynamic equilibrium of macro-ions in the soil solution. Oversaturation calculated for Salic Solonetz and Gleyic Solonetz soil solutions was small considering the SOM content. Calculations indicate the profile and lateral loss of C from the soil to the vadose zone. The content of Pb in the soil solution was calculated sirca 75%-80%. The calculated coefficient of Pb²⁺ association was as high as 52.0. The probability of Pb passivation by SOM in the Kastanozem complex was significant. The probability of uncontrolled transfer and accumulation of HM in the soil and vadose zone was high. Biogeosystem Technique (BGT*) transcendental methodology, an innovative methodology created for stable geomorphological system formation to achieve sustainable agriculture and silviculture, was applied. The BGT* elements were: intra-soil milling of the 30-60 cm soil layer for geophysical conditioning; intra-soil continuously-discrete pulse watering for plants and trees to improve the hydrologic regime. The BGT* methodology reduced HM mobility, controlled biodegradation, enriched nutrient biogeochemical cycling, increased C content, increased soil productivity, and reversible carbon sequester in biological form.

Polycyclic aromatic hydrocarbons, antibiotic resistance genes, toxicity in the exposed to anthropogenic pressure soils of the Southern Russia

The influence of anthropogenic pollution, particularly with polycyclic aromatic hydrocarbons (PAHs) on soil toxicity and spread of antibiotic resistance genes (ARGs) is extremely important nowadays. We studied 20 soil samples from a technogenically polluted site, municipal solid wastes (MSW) landfills, and rural settlements in the southwestern part of the Rostov Region of Russia. A close correlation was established between the results of biosensor testing for integral toxicity, the content of genes for the biodegradation of hydrocarbons, and the concentration of PAHs in soils. The relation between the quantitative content of ARGs and the qualitative and quantitative composition of PAHs has not been registered. Soils subjected to different types of the anthropogenic pressure differed in PAHs composition. The technogenic soils are the most polluted ones. These soils are enriched with 5 ring PAHs and carry the maximum variety of assayed ARGs, despite the fact that they do not receive household or medical waste.

The mechanisms of biochar interactions with microorganisms in soil

Biochar, a carbonaceous material, is increasingly used in the remediation of the anthropogenically polluted soils and the restoration of their ecological functions. However, the interaction mechanisms among biochar, inorganic and organic soil properties and soil biota are still not very clear. The effect of biochar on soil microorganisms is very diverse. Several mechanisms of these interactions were suggested. However, a well acceptable mechanism of biochar effect on soil microorganisms is still missing. Therefore, efforts were made to examine and proposed a mechanism of the interactions between biochar and microorganisms, as well as existing problems of biochar impacts on main groups of soil enzymes, the composition of the microbiota and the detoxification (heavy metals) and degradation (polycyclic aromatic hydrocarbons) of soil pollutants. The data on the process of biochar colonization by microorganisms and the effect of volatile pyrolysis products released by biochar on the soil microbiota were analysed in detail. The effects of biochar on the physico-chemical properties of soils, the content of mineral nutrients and the response of microbial communities to these changes are also discussed. The information provided here may contribute to the solution of the feasibility, effectiveness and safety of the biochar questions to enhance the soil fertility and to detoxify pollutants in soils.

Chemical Soil-Biological Engineering Theoretical Foundations, Technical Means, and Technology for Safe Intrasoil Waste Recycling and Long-Term Higher Soil Productivity

The amelioration and remediation technology was developed on the basis of research of phosphogypsum and utilization in the Haplic Chernozem of South-European facies (Rostov Region). Phosphogypsum was utilized via dispersed application into a soil layer of 20-45 cm with intrasoil milling of this layer. The phosphogypsum utilization doses were 0, 10, 20, and 40 t ha^-1. The Pb analytical content in soil solution was studied in the model experiment. The soil solution Pb thermodynamic forms were calculated. The mathematical chemical-thermodynamic model ION-2 was developed to calculate the real soil solution (water extract) calcium-carbonate equilibrium (CCE) ion forms, considering the ion pair association. The associated ion pairs CaCO₃ ⁰, CaSO₄ ⁰, MgCO₃ ⁰, MgSO₄ ⁰, CaHCO₃ ⁺, MgHCO₃ ⁺, NaCO₃ ^-, NaSO₄ ^-, CaOH⁺, and MgOH⁺ were accounted for in soil solution equilibrium macroion form calculation. The procedure for the microelement ion [including heavy metals (HMs)] equilibrium concentration in the soil solution coefficient k _as calculation was proposed to account for the real soil solution CCE, macroions, and HM (including Pb) association. The Pb²⁺ ion in soil solution was mostly bound to associates PbOH⁺, Pb(OH)₂ ⁰, PbCO₃ ⁰, Pb(CO₃)₂ ^2-, and PbHCO₃ ⁺. The calculation of CCE and ion association in soil solution revealed 14.5-21.5 times HM passivation compared to HM water-soluble values. The calculated HM activity in the soil solution in the example of the Pb²⁺ ion was less than 4% after phosphogypsum application in the target amelioration layer of 20-45 cm. The studied phosphogypsum doses were substantiated as environmentally safe. This was because the real soil solution CCE provided HM ion form association and consequent passivation. The dry steppe soil remediation after phosphogypsum application was justified as highly probable. The intrasoil milling chemical soil-biological engineering technology was developed for simultaneous soil amelioration and remediation on the basis of the biogeosystem technique (BGT*) transcendental methodology. The BGT*-based technology was tested in the long-term field experiments and is capable of ensuring the priority geophysical micro- and macroaggregate structure via intrasoil milling and mixing of soil illuvial and transitional horizons. This helps synthesize soil multilevel architecture, providing intrasoil-dispersed environmentally safe recycling of wastes of different origin. Addressing the environment safety concerns, a new decision of the intrasoil milling device was proposed for phosphogypsum and other substance application to soil.

Method for hydrophytic plant sample preparation for light and electron microscopy (studies on Phragmites australis Cav.)

Nowadays there are no well-established, standard methods in electron microscopy despite its 50-year history. An excessive variety of research objects prompt researchers to modify and improve methodological approaches to sample preparation. One of the difficult objects to study by electron microscopy is hydrophytic plants, for example, Phragmites australis Cav. Traditional approaches to fixation and sample preparation do not give satisfactory results due to the peculiarities in structure and physiology of hydrophytic plants. The purpose of present research is modification description of the widespread method developed for double fixation of hydrophytic plant tissue for transmission electron microscopy. Suggested approach takes into account the features of hydrophyte plants. •The developed method allows improving the quality of plant samples by additional fixatives imbibition and removing of air bubbles from aerenchyma tissue using a vacuum.•The new step of sample preparation consisting in the layer-by-layer sample mixing in a special inclined mixer is applied for the embedding media penetrate sufficiently into the sample tissue.•The process of samples inclusion in polymeric resins is carried out in the flat-bottom capsules. Compare to standard conical capsules, flat-bottom capsules allow strictly defined orientation sample pieces, that is permit to produce a semi-thin and ultra-thin slices of perpendicular to the longitudinal structures of the plant. This is especially important to conduct an adequate comparative analysis of dimensions, shape, and electron density of fragments and parts of the studying samples.

Method of determining loosely bound compounds of heavy metals in the soil

Method of determination of heavy metals loosely bound compounds in the soil was developed using three separate extractions. The group of loosely bound compounds of metals includes exchangeable, complexed, and specifically adsorbed forms. This method is available, rapid and not expensive. Extraction takes less than 24 h. Sample procedure preparation is simple, and the analysis consists of only three steps, which can be performed simultaneously. The parallel extraction gives reliable and reproducible results and provides a relatively complete idea of the metals mobility in the soil, their availability to plants, migratory capacity, and transformation.

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Method is suitable for a wide range of heavy metals and soil types. From the obtained data, the content of loosely bound compounds of heavy metals and the coefficients of metals mobility in the soil can be calculated.

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Method is suitable for estimation the microelement supply of uncontaminated soils. The content of elements in the 1 N CH₃COONH₄ extract characterizes the actual pool of elements, and their content in the 1 N HCl extract defines their potential pool in the soil.

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The coefficient of mobility (Km) is calculated to assess the contamination of soil with heavy metals. Estimation criteria of Km for Haplic Chernozem were developed.