Assessment of antibiotic resistance genes in soils polluted by chemical and technogenic ways with poly-aromatic hydrocarbons and heavy metals.

Anthropogenic activities are leaving lots of chemical footprints on the soil. It alters the physiochemical characteristics of the soil thereby modifying the natural soil microbiome. The prevalence of antimicrobial-resistance microbes in polluted soil has gained attention due to its obvious public health risks. This study focused on assessing the prevalence and distribution of antibiotic-resistance genes in polluted soil ecosystems impacted by industrial enterprises in southern Russia. Metagenomic analysis was conducted on soil samples collected from polluted sites using various approaches, and the prevalence of antibiotic-resistance genes was investigated. The results revealed that efflux-encoding pump sequences were the most widely represented group of genes, while genes whose products replaced antibiotic targets were less represented. The level of soil contamination increased, and there was an increase in the total number of antibiotic-resistance genes in proteobacteria, but a decrease in actinobacteria. The study proposed an optimal mechanism for processing metagenomic data in polluted soil ecosystems, which involves mapping raw reads by the KMA method, followed by a detailed study of specific genes. The study's conclusions provide valuable insights into the prevalence and distribution of antibiotic-resistance genes in polluted soils and have been illustrated in heat maps.

Effect of wood and peanut shell hydrochars on the desiccation cracking characteristics of clayey soils.

Soil cracking can significantly alter the water and nutrient migration pathways in the soil, influencing plant growth and development. While biochar usage has effectively addressed soil cracking, the feasibility of using less energy-intensive hydrochars in desiccating soils remains unexplored. This study investigates the impact of wood and peanut shell hydrochars on the desiccation cracking characteristics of clayey soil. A series of controlled environmental laboratory incubations with regular imaging was conducted to determine crack development's dynamic in unamended and hydrochar-amended soils. The results reveal that the addition of wood hydrochar at 2% and 4% dosage reduced the crack intensity factor (CIF) by 22% and 43%, respectively, compared to the unamended control soil. Similarly, the inclusion of peanut shell hydrochar at 2% and 4% lowered the CIF by 22% and 51%, respectively. The presence of hydrophilic groups on the surface of hydrochars, such as O-H, CH, and C-O-C, enhanced the water retention capacity, as confirmed by Fourier-transform infrared analysis. The CIF decrease is attributed to mitigated water evaporation rates, enabled by enhanced water retention within the hydrochar pore spaces. These findings are supported by scanning electron microscopy analyses of the hydrochar morphology. Despite CIF reduction with hydrochar incorporation, the crack length density (CLD) increased across all hydrochar-amended series. In contrast to unamended soil which exhibited pronounced widening of large cracks and extensive inter-pore voids, the incorporation of hydrochar resulted in higher CLD due to the formation of finer interconnecting crack meshes. Consequently, the unamended control soil suffered greater water loss due to heightened evaporation rates. This study sheds new light on the potential of hydrochars in addressing desiccation-induced soil cracking and its implications for water conservation.

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.

A critical review on fate, behavior, and ecotoxicological impact of zinc oxide nanoparticles on algae.

The rapid inclusion of zinc oxide nanoparticles (ZnO NPs) in nanotechnology-based products over the last decade has generated a new threat in the apprehension of the environment. The massive use of zinc nanosized products will certainly be disposed of and be released, eventually entering the aquatic ecosystem, posing severe environmental hazards. Moreover, nanosized ZnO particles owing the larger surface area per volume exhibit different chemical interactions within the aquatic ecosystem. They undergo diverse potential transformations because of their unique physiochemical properties and the feature of receiving medium. Therefore, assessment of their impact is critical not only for scavenging the present situation but also for preventing unintended environmental hazards. Algae being a primary producer of the aquatic ecosystem help assess the risk of massive NPs usage in environmental health. Because of their nutritional needs and position at the base of aquatic food webs, algal indicators exhibit relatively unique information concerning ecosystem conditions. Moreover, algae are presently the most vital part of the circular economy. Hence, it is imperative to understand the physiologic, metabolic, and morphologic changes brought by the ZnO NPs to the algal cells along with the development of the mechanism imparting toxicity mechanism. We also need to develop an appropriate scientific strategy in the innovation process to restrain the exposure of NPs at safer levels. This review provides the details of ZnO NP interaction with algae. Moreover, their impact, mechanism, and factors affecting toxicity to the algae are discussed.

Nanomaterials and biochar mediated remediation of emerging contaminants.

The unrestricted release of various toxic substances into the environment is a critical global issue, gaining increased attention in modern society. Many of these substances are pristine to various environmental compartments known as contaminants/emerging contaminants (ECs). Nanoparticles and emerging sorbents enhanced remediation is a compelling methodology exhibiting great potential in addressing EC-related issues and facilitating their elimination from the environment, particularly those compounds that demonstrate eco-toxicity and pose considerable challenges in terms of removal. It provides a novel technique enabling the secure and sustainable removal of various ECs, including persistent organic compounds, microplastics, phthalate, etc. This extensive review presents a critical perspective on the current advancements and potential outcomes of nano-enhanced remediation techniques such as photocatalysis, nano-sensing, nano-enhanced sorbents, bio/phyto-remediation, which are applied to clean-up the natural environment. In addition, when dealing with residual contaminants, special attention is paid to both health and environmental implications; therefore, an evaluation of the long-term sustainability of nano-enhanced remediation methods has been considered. The integrated mechanical approaches were thoroughly discussed and presented in graphical forms. Thus, the critical evaluation of the integrated use of most emerging remediation technologies will open a new dimension in environmental safety and clean-up program.

Biogeochemical and microscopic studies of soil and Phragmites australis (Cav.) Trin. ex Steud. plants affected by coal mine dumps.

Developed areas of the coal industry are subjected to long-term anthropogenic impacts from the input and accumulation of overburdened coal material, containing potentially toxic heavy metals and metalloids (HMM). For the first time, comprehensive studies of soils and plants in the territory of the Donetsk coal basin were carried out using X-ray fluorescence, atomic absorption analysis, and electron microscopy. The observed changes in the soil redox conditions were characterized by a high sulfur content, and formations of new microphases of S-containing compounds: FeS2, PbFe6(SO4)4(OH)12, ZnSO4·nH2O, revealed the presence of technogenic salinization, increased Сorg content, and low pH contents. Exceedances of soil maximum permissible concentrations of Pb, Zn, Cu, and As in areas affected by coal dumps were apparent. As a consequence of long-term transformation of the environment with changes in properties and chemical pollution, a phytotoxic effect was revealed in Phragmites australis (Cav.) Trin. ex Steud, accompanied by changes in ultrastructural and organization features of roots and leaves such as increases in root diameters and thickness of leaf blades. The changes in the ultrastructure of cell organelles: a violation of the grana formation process, an increase in the number of plastoglobules, a decrease in the number of mitochondrial cristae, and a reduction in the electron density of the matrix in peroxisomes were also observed. The accumulation of large electron-dense inclusions and membrane fragments in cell vacuoles was observed. Such ultrastructural changes may indicate the existence of a P. australis ecotype due to its long-term adaptation to the disturbed environment.

Transfer and Degradation of PAHs in the Soil-Plant System: A Review.

Polycyclic aromatic hydrocarbons (PAHs) are highly toxic, persistent organic pollutants that threaten ecosystems and human health. Consistent monitoring is essential to minimize the entry of PAHs into plants and reduce food chain contamination. PAHs infiltrate plants through multiple pathways, causing detrimental effects and triggering diverse plant responses, ultimately increasing either toxicity or tolerance. Primary plant detoxification processes include enzymatic transformation, conjugation, and accumulation of contaminants in cell walls/vacuoles. Plants also play a crucial role in stimulating microbial PAHs degradation by producing root exudates, enhancing bioavailability, supplying nutrients, and promoting soil microbial diversity and activity. Thus, synergistic plant-microbe interactions efficiently decrease PAHs uptake by plants and, thereby, their accumulation along the food chain. This review highlights PAHs uptake pathways and their overall fate as contaminants of emerging concern (CEC). Understanding plant uptake mechanisms, responses to contaminants, and interactions with rhizosphere microbiota is vital for addressing PAH pollution in soil and ensuring food safety and quality.

A Novel Study on Anionic Surfactant Degradation Potential of Psychrophillic and Psychrotolerant Pseudomonas spp. Identified from Surfactant-contaminated River Water.

The Yamuna River, a tributary of the holy Ganga, is heavily polluted in the Delhi-NCR region, India and has been gaining attention due to the excessive foaming of the river over the past few years. This can be directly or indirectly related to the overuse of surfactants and the discharge of untreated domestic and textile wastewater into the river. To determine the surfactant load and investigate potential surfactant-degrading bacteria in the region, 96 water samples from four sites in the Okhla Barrage stretch of the river were collected and analysed. The results showed that the selected sites have surfactant concentrations more than the permissible limit (1.00 mgL-1). Also, at most of the sites, the concentration crossed the desirable limit of BIS (0.2 mgL-1) during the period of analysis. The concentration of anionic surfactant reported in the region was found in the range of 0.29 mgL-1 and 2.83 mgL-1. A total of 38 different bacteria were isolated using selective media from the same water samples, out of which 7 bacterial isolates were screened for sodium dodecyl sulphate (SDS) tolerance activity. Based on 16S rRNA gene sequencing, 2 species, namely Pseudomonas koreensis YRW-02 and Pseudomonas songnenensis YRW-05 have been identified and their degradation potential was assessed at different SDS concentrations. The results showed that our strains YRW-02 and YRW-05 degraded 78.29 and 69.24% of SDS respectively. Growth optimization was also performed at different substrate concentrations, pH, and temperature to investigate optimum degradation conditions. This study plays a significant role in assessing the surfactant load and also gives a promising background for future use in in-situ bioremediation experiments.

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.

Uptake, accumulation, toxicity, and interaction of metallic-based nanoparticles with plants: current challenges and future perspectives.

The rapid development of industrialization is causing several fundamental problems in plants due to the interaction between plants and soil contaminated with metallic nanoparticles (NPs). Numerous investigations have been conducted to address the severe toxic effects caused by nanoparticles in the past few decades. Based on the composition, size, concentration, physical and chemical characteristics of metallic NPs, and plant types, it enhances or lessens the plant growth at various developmental stages. Metallic NPs are uptaken by plant roots and translocated toward shoots via vascular system based on composition, size, shape as well as plant anatomy and cause austere phytotoxicity. Herein, we tried to summarize the toxicity induced by the uptake and accumulation of NPs in plants and also we explored the detoxification mechanism of metallic NPs adopted by plants via using different phytohormones, signaling molecules, and phytochelatins. This study was intended to be an unambiguous assessment including current knowledge on NPs uptake, accumulation, and translocation in higher plants. Furthermore, it will also provide sufficient knowledge to the scientific community to understand the metallic NPs-induced inhibitory effects and mechanisms involved within plants.

Nanomaterials in biochar: Review of their effectiveness in remediating heavy metal-contaminated soils.

Biochar can be used for soil remediation in environmentally beneficial manner, especially when combined with nanomaterials. After a decade of research, still, no comprehensive review was conducted on the effectiveness of biochar-based nanocomposites in controlling heavy metal immobilization at soil interfaces. In this paper, the recent progress in immobilizing heavy metals using biochar-based nanocomposite materials were reviewed and compared their efficacy against that of biochar alone. In details, an overview of results on the immobilization of Pb, Cd, Cu, Zn, Cr, and As was presented by different nanocomposites made by various biochars derived from kenaf bar, green tea, residual bark, cornstalk, wheat straw, sawdust, palm fiber, and bagasse. Biochar nanocomposite was found to be most effective when combined with metallic nanoparticles (Fe3O4 and FeS) and carbonaceous nanomaterials (graphene oxide and chitosan). This study also devoted special consideration to different remediation mechanisms by which the nanomaterials affect the effectiveness of the immobilization process. The effects of nanocomposites on soil characteristics related to pollution migration, phytotoxicity, and soil microbial composition were assessed. A future perspective on nanocomposites' use in contaminated soils was presented.

Decrypting the multi-functional biological activators and inducers of defense responses against biotic stresses in plants.

Plant diseases are still the main problem for the reduction in crop yield and a threat to global food security. Additionally, excessive usage of chemical inputs such as pesticides and fungicides to control plant diseases have created another serious problem for human and environmental health. In view of this, the application of plant growth-promoting rhizobacteria (PGPR) for controlling plant disease incidences has been identified as an eco-friendly approach for coping with the food security issue. In this review, we have identified different ways by which PGPRs are capable of reducing phytopathogenic infestations and enhancing crop yield. PGPR suppresses plant diseases, both directly and indirectly, mediated by microbial metabolites and signaling components. Microbial synthesized anti-pathogenic metabolites such as siderophores, antibiotics, lytic enzymes, hydrogen cyanide, and several others act directly on phytopathogens. The indirect mechanisms of reducing plant disease infestation are caused by the stimulation of plant immune responses known as initiation of systemic resistance (ISR) which is mediated by triggering plant immune responses elicited through pathogen-associated molecular patterns (PAMPs). The ISR triggered in the infected region of the plant leads to the development of systemic acquired resistance (SAR) throughout the plant making the plant resistant to a wide range of pathogens. A number of PGPRs including Pseudomonas and Bacillus genera have proven their ability to stimulate ISR. However, there are still some challenges in the large-scale application and acceptance of PGPR for pest and disease management. Further, we discuss the newly formulated PGPR inoculants possessing both plant growth-promoting activities and plant disease suppression ability for a holistic approach to sustaining plant health and enhancing crop productivity.

Study of the Possibility of Using Sol-Gel Technology to Obtain Magnetic Nanoparticles Based on Transition Metal Ferrites.

The article presents results for the magnetic nanoparticles sol-gel method synthesis of cobalt (II) ferrite and organic-inorganic composite materials based on it. The obtained materials were characterized using X-ray phase analysis, scanning and transmission electron microscopy, Scherrer, Brunauer-Emmett-Teller (BET) methods. A composite materials formation mechanism is proposed, which includes a gelation stage where transition element cation chelate complexes react with citric acid and subsequently decompose under heating. The fundamental possibility of obtaining an organo-inorganic composite material based on cobalt (II) ferrite and an organic carrier using the presented method has been proved. Composite materials formation is established to lead to a significant (5-9 times) increase in the sample surface area. Materials with a developed surface are formed: the surface area measured by the BET method is 83-143 m2/g. The resulting composite materials have sufficient magnetic properties to be mobile in a magnetic field. Consequently, wide possibilities for polyfunctional materials synthesis open up for various applications in medicine.

Fabrication of biochar derived from different types of feedstocks as an efficient adsorbent for soil heavy metal removal.

For effective soil remediation, it is vital to apply environmentally friendly and cost-effective technologies following the notion of green sustainable development. In the context of recycling waste and preserving nutrients in the soil, biochar production and utilization have become widespread. There is an urgent need to develop high-efficiency biochar-based sorbents for pollution removal from soil. This research examined the efficacy of soil remediation using biochar made from three distinct sources: wood, and agricultural residues (sunflower and rice husks). The generated biochars were characterized by SEM/SCEM, XRF, XRD, FTIR, BET Specific Surface Area, and elemental compositions. The presence of hydroxyl and phenolic functional groups and esters in wood, sunflower and rice husk biochar were noted. The total volume of pores was in the following descending order: rice husk > wood > sunflower husk. However, wood biochar had more thermally stable, heterogeneous, irregular-shaped pores than other samples. Adsorption of soil-heavy metals into biochars differed depending on the type of adsorbent, according to data derived from distribution coefficients, sorption degree, Freundlich, and Langmuir adsorption models. The input of biochars to Calcaric Fluvic Arenosol increased its adsorption ability under contamination by Cu(II), Zn(II), and Pb(II) in the following order: wood > rice husk > sunflower husk. The addition of sunflower husk, wood, and rice husk biochar to the soil led to an increase in the removal efficiency of metals in all cases (more than 77%). The increase in the percentage adsorption of Cu and Pb was 9-19%, of Zn was 11-21%. The present results indicated that all biochars functioned well as an absorbent for removing heavy metals from soils. The tailor-made surface chemistry properties and the high sorption efficiency of the biochar from sunflower and rice husks could potentially be used for soil remediation.

Physiological and Biochemical Responses of Solanum lycopersicum L. to Benzo[a]pyrene Contaminated Soils.

Benzo[a]pyrene (BaP) is noted as one of the main cancer-causing pollutants in human beings and may damage the development of crop plants. The present work was designed to explore more insights into the toxic effects of BaP on Solanum lycopersicum L. at various doses (20, 40, and 60 MPC) spiked in Haplic Chernozem. A dose-dependent response in phytotoxicity were noted, especially in the biomass of the roots and shoots, at doses of 40 and 60 MPC BaP and the accumulation of BaP in S. lycopersicum tissues. Physiological and biochemical response indices were severely damaged based on applied doses of BaP. During the histochemical analysis of the localization of superoxide in the leaves of S. lycopersicum, formazan spots were detected in the area near the leaf's veins. The results of a significant increase in malondialdehyde (MDA) from 2.7 to 5.1 times, proline 1.12- to 2.62-folds, however, a decrease in catalase (CAT) activity was recorded by 1.8 to 1.1 times. The activity of superoxide dismutase (SOD) increased from 1.4 to 2, peroxidase (PRX) from 2.3 to 5.25, ascorbate peroxidase (APOX) by 5.8 to 11.5, glutathione peroxidase (GP) from 3.8 to 7 times, respectively. The structure of the tissues of the roots and leaves of S. lycopersicum in the variants with BaP changed depending on the dose: it increased the intercellular space, cortical layer, and the epidermis, and the structure of the leaf tissues became looser.

Microbiological status of natural and anthropogenic soils of the Taganrog Bay coast at different levels of combined pollution with heavy metals and PAHs.

The effect of heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) pollution on the microbiological status of soils on the coast of the Taganrog Bay and adjacent areas was studied. The content of total and exchangeable forms of HMs, the content of 16 priority PAHs and the abundance of several groups of culturable microorganisms was determined, namely copiotrophic, prototrophic, aerobic spore-forming bacteria, actinomycetes, molds and yeasts. The content of total and exchangeable forms of HMs in urban coastal soils in industrial zone significantly exceeded that in non-urban soils. The maximum concentrations of total forms of Mn, Cr, Ni, Cu, Zn, Pb and Cd are 1821, 871, 143, 89, 1390, 317 and 10 mg/kg, respectively. The median value of the total content of 16 PAHs in urban soils is 3 times higher than in the soils of natural areas and reached 4309 ng/g. The lowest numbers of copiotrophic bacteria, prototrophic bacteria and aerobic spore-forming bacteria were found in the soils of industrial zone: 6.8, 13.8 and 0.63 million CFU g-1 dry soil, respectively. The largest numbers of copiotrophic bacteria, prototrophic bacteria and aerobic spore-forming bacteria were recorded in the soils of natural areas-72.5, 136 and 5.73 million CFU g-1 dry soil, respectively. It was found that the abundance of copiotrophs, prototrophs, and aerobic spore-forming bacteria is more affected by the urbanization of coastal soils including the pollution of HMs and PAHs. Other groups of microorganisms (actinomycetes, molds and yeasts) turned out to be more resistant to anthropogenic factors.

Effect of chicken manure on soil microbial community diversity in poultry keeping areas.

The poultry industry is generating a significant amount of waste from chicken droppings that are abundant in microbes as well as macro- and micronutrients suitable for manure. It has the potential to improve the microbial activity and nutrient dynamics in the soil, ultimately improving soil fertility. The present study aimed to investigate the effect of chicken droppings manure (CDM) on the diversity of the soil microbiome in the free walking chicken's area located in Stefanidar, Rostov Region, Russia. The data obtained were compared with 16 s rRNA from control samples located not far from the chicken's free-walking area, but not in direct contact with the droppings. Effect of CDM on the physicochemical characteristics of the soil and changes in its microbial diversity were assessed by employing the metagenomic approaches and 16 s rRNA-based taxonomic assessment. The alpha and beta diversity indices revealed that the application of the CDM significantly improved the soil microbial diversity. The 16S taxonomical analysis confirmed Proteobacteria, Actinobacteria, Bacteroidetes, Firmicutes, and Planctomycetes as abundant bacterial phylum. It also revealed the increase in the total number of the individual operational taxonomic unit (OTU) species, a qualitative indicator of the rich microbial community. The alpha diversity confirmed that the significant species richness of the soil is associated with the CDM treatment. The increased OTUs represent the qualitative indicator of a community that has been studied up to the depth of 5-20 cm of the CDM treatment range. These findings suggested that CDM-mediated microbial richness are believed to confer the cycling of carbon, nitrogen, and sulfur, along with key soil enzymes such as dehydrogenases and catalase carbohydrate-active enzymes. Hence, the application of CDM could improve soil fertility by nutrient cycling caused by changes in soil microbial dynamics, and it could also be a cost-effective sustainable means of improving soil health.

Genotoxic and morpho-physiological responses of ZnO macro- and nano-forms in plants.

In the current study, two plants, viz., Pisum sativum L. and Hordeum vulgare L., were exposed to nano- and macro-dispersed ZnO at 1, 10, and 30 times of maximal permissible concentration (MPC). The main objective of the study is to depict and compare the genotoxicity in terms of chromosomal anomalies, cytotoxicity (i.e., mitotic index), and phytotoxicity (viz., germination, morphometry, maximal quantum yield, and chlorophyll fluorescence imaging) of macro- and nano-forms of ZnO along with their accumulation and translocation. In the case of genotoxic and cytotoxic responses, the maximal effect was observed at 30 MPC, regardless of the macro- or nano-forms of ZnO. The phytotoxic observations revealed that the treatment with macro- and nano-forms of ZnO significantly affected the germination rate, germination energy, and length of roots and shoots of H. vulgare in a dose-dependent manner. The factor toxicity index of treated soil demonstrated that toxicity soared as concentrations increased and that at 30 MPC, toxicity was average and high in macro- and nano-dispersed ZnO, respectively. Furthermore, the photosynthetic parameters were observed to be negatively affected in both treatments, but the maximal effect was observed in the case of nano-dispersed form. It was noted that the mobility of nano-dispersed ZnO in the soil was higher than macro-dispersed. The increased mobility of nano-dispersed ZnO might have boosted their accumulation and translocation that subsequently led to the oxidative stress due to the accelerated production of reactive oxygen species, thus strengthen toxicity implications in plants.

Phenanthrene uptake and translocation by Panicum miliaceum L. tissues: an experimental study in an artificial environment.

Polycyclic aromatic hydrocarbons (PAHs), as priority organic pollutants, are capable of accumulation in plants. Phenanthrene (Phe) is one of the most abundant low-molecular-weight PAH in the environment which is commonly used as a model PAH in many phytoremediation studies and as a representative compound for all PAHs group. This paper highlights the uptake, translocation, and accumulation of Phe by growing proso millet (Panicum miliaceum L.) in a pot experiment, subjected to 500, 1000, 1500, and 2000 ppm of Phe treatment after 15 and 30 days. Phe naturally existed in P. miliaceum and its concentration showed a time-dependent reduction in treated plant tissues as well as in perlites. Phe concentration in shoots was higher than in roots. During the aging process, the uptake of Phe was diminished whereas translocation factor (TF) demonstrated an overall increasing trend among treatments. The shoot concentration factor (SCF) values were higher than those of root concentration factor (RCF) on both days 15 and 30 and the highest values for both parameters were achieved in 500 ppm of Phe. Both RCFs and SCFs generally tended to decrease with the increase of perlite Phe concentrations. These results suggested that Phe tended to transfer to the shoots and be metabolized there. The Phe concentration revealed a significant decline in all levels of treatment on both 15 (84 to 96%) and 30 (76 to 94%) days. Therefore, the presence of P. miliaceum was effective in promoting the phytoremediation of Phe polluted perlites.

Potentially toxic elements in surface soils of the Lower Don floodplain and the Taganrog Bay coast: sources, spatial distribution and pollution assessment.

The pollution of floodplain, deltaic and adjacent coastal soils in large fluvial systems, considered an urgent environmental problem, as well as potentially toxic elements in such environments, can negatively affect aquatic ecosystems, as well as pose significant risks to human health. This paper is devoted to the geochemistry of potentially toxic elements in soils of the Lower Don basin, which is one of the largest and most anthropogenically transformed water bodies in Southern Russia, as well as the adjacent areas of the Taganrog Bay coast. The median element concentrations in the soils of the study area were consistent with the world soil average and the contents of elements in background soils. Comparative assessment of the spatial distributions as well as the results of Pearson's correlations, cluster analysis and principal component analysis showed that Cr, Ni, Cu and Zn are predominantly of natural origin; Mn and As are of mixed sources; and Cd and Pb are predominantly of anthropogenic origin. The geochemical anomalies of elements were associated with the impact of local anthropogenic sources. Geochemical background values for Cr, Mn, Ni, Cu, Zn, As, Cd and Pb in the soils of the Lower Don and the Taganrog Bay coast determined using the 'median + 2 median absolute deviations' approach are presented. The highest values of the integrated pollution indices were observed in floodplain soils of small rivers.