Our analysis of metabolic and ecological features of fungi indicates a high bioremediation potential of fungal mycelium. The relevance of the problems solved in this work is conditioned by insufficiently studied mechanisms and conditions of micromycetal activity on heavy metal detoxication. The effect of copper on the development of two micromycete species, namely, melanised Alternaria alternata (Fr.) Keissl., 1912 and hyaline Fusarium oxysporum Schltdl., 1824 cultivated on Czapek agar (with 2 or 3% sucrose) was compared; the ability of mycelium to sorb copper cations when grown in a liquid culture with 0, 0.05, 0.1, 0.25, and 0.5 mg Cu2+ / L was evaluated. F. oxysporum had noticeable advantages in terms of growth rate, tolerance, conidia production on medium with Cu2+. The effective concentration of copper (EC50), indicating the resistance of the fungus, increased for F. oxysporum by 1.5 times with increasing sucrose content in the medium. The melanised culture of A. alternata was superior to F. oxysporum in terms of sorption capacity. The percentage of Cu2+ extraction by fungal mycelium from the medium reached 40% in the case of F. oxysporum and twice as much in the case of A. alternata . The vast majority of copper was sorbed by the cell walls of hyphae and washed away by water. A small amount (a maximum of 0.16 µg Cu2+ /g dry mycelium of A. alternate ) penetrated inside the mycelial cells. F. oxysporum, which had no intracellular protective melanins, accumulated Cu2+ (2 to 14 times) less. The results show that the mechanisms of resistance to Cu2+ and sorption are different in the studied species: in Fusarium they are determined mainly by the barrier functions of hyphae cell walls, while in Alternaria melanin plays a significant role in protection against Cu toxic action.

Biochar as a soil remediation product does not always produce a promising result. In a number of studies, this is explained by the nature and properties of biochar. The dependence of the efficacy of biochar application on the level of chemical pollution and soil properties has not been sufficiently studied. The study aimed to evaluate the effects of biochar in case of heavy polymetallic contamination of agricultural sandy podzolic soils (Albic Glossic Retisols (Loamic, Aric Cutanic, Ochric) with different levels of humus content using the ecotoxicological and microbiological parameters. Soils with different organic carbon contents (S1 with Corg 3.86 and S2 with 1.30

Background Iron oxide mineral–humic complexes serve as a reservoir of bioavailable Fe for plants, releasing metal ligands and providing Fe–humic complexes directly usable by plant Fe-uptake mechanisms. In this study, we synthesized and characterized goethite α-FeOOH (G) nanoparticles (NPs) intercalated in coal (GC) to estimate the bioactivity effect of humic acids (HA). The synthesized GC NPs were characterized by X-ray diffraction, scanning electron microscopy (SEM), Mössbauer spectroscopy, N 2 adsorption–desorption Brunauer–Emmett–Teller (BET) specific surface area, zeta potential, hydrodynamic particle diameter, iron ions release, and a phytoassay method of root elongation using the higher plant Sinapis alba . Results X-ray diffraction revealed that G was the primary phase in both GC and GC–HA complexes. Mössbauer spectroscopy analysis identified a goethite-doped Fe 2+ -in the GC samples. The intercalation of G into the coal matrix increased the specific surface area of GC, enhancing its HA sorption capacity. In addition, GC–HA demonstrated superior plant growth stimulation compared to HA and GC alone, indicating its role in colloidal stability. In contrast to GC, GC–HA exhibited a more consistent and time-dependent release of Fe 3+ and Fe 2+ . This sustained Fe release from GC–HA, coupled with the formation of Fe 3+ and more bioavailable (soluble) Fe 2+ humic complexes is a promising result in terms of iron nanofertilizers production. Conclusions The use of goethite nanoparticles intercalated within a coal matrix and subsequently complexed with HA contributes to prolonged phytoactivity by employing slowly released nutrient additives within the coal mesoporous matrix. Graphical Abstract

The effects of aging of colloidal dispersions of iron (Fe) oxy(hydr)oxides have practical implications for a variety of fields, including medicine, biology, chemistry, and environmental science. Aging affects the stability of these materials under different environmental conditions, thereby affecting their reactivity and applicability in remediation. However, only a limited number of studies have focused on aging-induced changes in the phase composition, surface properties, and toxicological effects of nanoparticles (NPs). In this study, a variety of Fe oxides were synthesized, including the closely related Fe oxides magnetite and maghemite, intermediate phases (Fe 3-δ O 4 : Fe 3 O 4 , γ-Fe 2 O 3 , 5Fe 2 O 3 ∙9H 2 O), and δ-FeOOH. Fe 3 O 4 was synthesized by precipitation, γ-Fe 2 O 3 by direct oxidation of Fe 3 O 4 , while 5Fe 2 O 3 ∙9H 2 O and δ-FeOOH were prepared by precipitation with slow and fast oxidation, respectively. The crystal structure, surface charge, and leaching of Fe ions of these materials were measured. All synthesized materials were then tested in bioassays with ciliates and higher plants at circumneutral pH, both upon preparation and after aqueous aging. Quantitative analysis of the XRD data using the Rietveld method showed that the crystal structure of the magnetite nanoparticles changed to γ-Fe 2 O 3 . The evaluation of biological activity in Sinapis alba (white mustard) showed that NPs of different compositions, stored at a maximum concentration of 10 g L -1 , inhibited root growth by 50%. In the case of δ-FeOOH and Fe 3 O 4 , however, concentrations of 1 g L -1 caused only minor inhibition. The toxic effects of Fe-NPs, attributed to the release of Fe 2+ and Fe 3+ ions by oxidation, were found to be consistent with the redox behavior of NPs. The study of the properties of magnetic nanoparticles, both in their initial state and after aqueous aging, enhances our understanding of their performance in magnetic nanofluids.

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X23070413

The specific features of halotolerant fungi are analyzed to assess their potential for indicating chemical contamination of saline soils and to search for the promising test species for laboratory mycotesting. The listed halophile and halotolerant micromycete genera comprise the representatives suitable as indicators of pollution by heavy metals, oil products, and other toxicants on the background of increased salinity of soil substrates. The moderately halotolerant species of micromycetes are proposed as promising for biotesting of the soils with moderate salinity. Morphological, physiological, and molecular mechanisms underlying the adaptation of halophilic and halotolerant fungi to an increased salinity of habitats are analyzed. The responses of fungal communities to the combined impact of salinization and toxic substances of different natures are discussed. The methodological aspects of the application of halotolerant fungi for biotesting the degree of disturbance of saline soils are considered, including the composition of media, cultivation conditions, and test responses of fungal cultures optimal for an adequate assessment of the degree of fungal halotolerance and the ecotoxicity of soil samples.

Pharmaceuticals and antibiotics in the environment are of increasing concern due to the impact on representatives of all links in the food chain of natural ecosystems. The effect of the widespread antibiotic ciprofloxacin (Cip) on the green protococcal microalgae Scenedesmus quadricauda and Chlorella vulgaris in water and aqueous soil extracts (artificial standard soil, technosoil, soddy-podzolic soil) was studied in model experiments. Fluorescent parameters were assessed by two different methods (Fluorat 02-5M and Water-PAM devices). The phenomenon of hormesis was observed at low antibiotic concentrations of 5 and 10 mg/L. A decrease in the photosynthetic activity of algae was recorded at an increase of Cip content from 20 to 50 mg/L. A comparison was made of the median (average effective) concentration of the EC50 antibiotic, which suppresses the fluorescent characteristics of microalgae by 50% on 3 days of exposure in different media. The decrease in the toxicity of the studied dose of Cip (300 mg/L) in a number of studied objects can be represented as follows: water > technosoil > artificial standard soil > soddy-podzolic soil. It reflects the percentage of inhibition of the test function relative to the control (samples without antibiotic) by 91.5, 80.0, 62.5, and 60.0% respectively. In the soil matrix, the inhibitory effect of the antibiotic is less pronounced (by 10–30%), probably due to the protective properties of humic substances that adsorb the antibiotic or its metabolites.

We studied the safety of sorbents based on zerovalent iron in the form of micro- and nanoparticles and their detoxifying activity in peat eutrophic soil (Eutric Histosol) polluted by emissions from a copper-nickel (Cu/Ni) plant (Kola Peninsula, Russia). Iron nanoparticles, as well as iron microparticles at a dose of 2%, turned out to be non-toxic according to the results of three standard bioassays based on the reactions of test organisms of different taxonomic affiliation. Toxicity was assessed by the change in the length of the roots of seedlings of plants Sinapis alba L. in uncontaminated peat, by the survival of Ceriodaphnia affinis Lilljeborg and the protozoan Parameciun caudatum Ehrenberg in water extracts of the samples. Fe-containing preparations significantly reduced the ecotoxicity of the soil due to the extremely high content of copper (6877 mg/kg) and nickel (2580 mg/kg). Differences in the remediating ability of the preparations were revealed. According to the results of soil phytotesting, iron nanoparticles significantly outperformed the detoxifying effect of microparticles (iron powder). When analyzing the water extract, the superiority of nanoparticles in reducing soil toxicity was not found. The dependence of the assessment of the detoxifying ability of zerovalent iron nanoparticles on soil properties and the plant species used in phytotesting is discussed.

The methodology for biodiagnostics of the ecological state of soils and other environmental objects involves the use of two approaches: bioindicative observations in situ and biotesting of samples, carried out according to standard methods in controlled laboratory conditions ex situ. An integrated assessment of soils based on an interdisciplinary approach in accordance with the international standard ISO19204-2017 makes it possible to diagnose of the “health” of soils based on biotic parameters in the course of observations of the natural environment and ecotoxicity indicators, which are supplemented by the results of quantitative che-mical analysis (TRIAD methodology). For soils, indicators of the state of higher plants and microbial communities, especially in agroecosystems, are of paramount importance. This article analyzes the advantages and limitations of well-known methods of phytoindication, laboratory phytotesting, soil respiration, structural and functional indicators of microbiota diversity, and bacterial biosensors. The responses of living systems to the same pollutant content largely depend on the carbon content of organic matter. The existing regulatory framework for the ecological assessment of the biological state of soil ecosystems practically does not take into account this, as well as the level of mineralization and pH of the analyzed objects. For an adequate assessment of the ecological quality of soils, it is proposed to improve the methods of measuring toxicity by more targeted recommendations for application (for example, for certain gradations of humus content, mineralization, and pH).

Известные факты повышения доли фитопатогенных форм микромицетов в почвах, загрязненных тяжелыми металлами (ТМ), делают актуальными исследования механизмов их резистентности, что важно для выбора эффективных средств борьбы с возбудителями болезней растений. Не менее актуальными и нуждающимися в изучении остаются вопросы взаимодействия металл-резистентных фитопатогенов с непатогенными видами на фоне загрязнения. В лабораторных экспериментах с чистыми культурами четырех видов грибов (фитопатогенные штаммы Alternaria alternata и Fusarium oxysporum и непатогенные Trichoderma harzianum и Clonostachys rosea) исследовали резистентность к катионам Cu, Zn, Pb, по отдельности добавленных в питательную среду с разным содержанием доступного углерода (сахарозы). Измеряли рост колоний, активность спорообразования и накопление биомассы. Рассчитывали эффективные концентрации, приводящие к 50%-му ингибированию параметров роста, - EC50. Исследуемые грибы проявляли различную устойчивость к ТМ. T. harzianum и C. rosea были более устойчивы к Zn и Pb при любом содержании доступного углерода. Наиболее устойчивы к Cu были пары A. alternata - C. rosea и T. harzianum - C. rosea на средах с меньшим и большим содержанием углерода соответственно. При этом для всех грибов Zn и Pb оказались менее токсичны, чем Сu. Антагонистическая активность, оцененная методом встречных культур на средах с добавлением ТМ, зависела как от ростовых характеристик, так и от выявленной устойчивости вида к ТМ. Активность быстрорастущего T. harzianum как территориального антагониста стимулировалась внесением Zn и Pb. Медленнорастущий C. rosea проявлял конкурентоспособность благодаря высокой устойчивости к ТМ. Сделан вывод о необходимости учета видовой устойчивости к ТМ для прогноза развития взаимоотношений патогенных и непатогенных видов в грибных сообществах на фоне загрязнения почвы. The facts of an increase in the proportion of phytopathogenic forms of micromycetes in soils contaminated with heavy metals (HM) make it relevant to study the mechanisms of their resistance, which is important to choose effective phytopathogen control methods. The issues of interaction between metal-resistant phytopathogens and non-pathogenic species against the background of pollution remain no less relevant and need to be studied. In laboratory experiments with pure cultures of four fungal species (phytopathogenic strains Alternaria alternata and Fusarium oxysporum and non-pathogenic strains Trichoderma harzianum and Clonostachys rosea), the resistance to Cu, Zn, Pb cations, separately added to nutrient medium with different content of available carbon (sucrose), was studied. Colony growth, sporulation activity, and biomass accumulation were measured. The effective concentrations, resulting in 50 % inhibition of growth parameters (EC50), were calculated. The studied fungi showed different resistance to HM. T . harzianum and C. rosea were more resistant to Zn and Pb at any available carbon content. The pairs A. alternata-C. rosea and T. harzianum-C. rosea were the most resistant to Cu on media with lower and higher carbon contents, respectively. At the same time, Zn and Pb turned out to be less toxic than Cu for all fungi. The antagonistic activity, assessed by the dual culture method on media supplemented with HM cations, depended both on the growth characteristics and on the revealed resistance to HM. The activity of fast growing T. harzianum as a territorial antagonist was stimulated by the addition of Zn and Pb. The slow-growing C. rosea showed competitiveness due to its high resistance to HM. It is concluded that it is necessary to take into account species resistance to HM in order to predict the development of relationships between pathogenic and non-pathogenic species in fungal communities against the background of soil pollution.

The increase in the production and application of engineered nanomaterials, including nanoparticles (NPs), leads to their discharge into the environment, where they can interact with coexisting antibiotics from wastewater, causing a complicated joint effect on organisms that need to be studied. Herein, a typical engineered nanomaterial, silica-magnetite NPs modified with tetraethoxysilane and 3-aminopropyltriethoxysilane (MTA-NPs, 1-2 g/L), and common antibiotic ciprofloxacin (CIP, 0-5 mg/L) were selected as the analytes. Their joint toxicity to a model of ciliates infusoria, Paramecium caudatum was specifically investigated. The impact of CIP, MTA-NPs, and humic acids (HA) was tracked for 24 h, individually and collectively, on the mortality of infusoria. The addition of MTA-NPs and HA at the studied concentrations leads to 40% mortality of organisms. The combined presence of the MTA-NPs at a concentration of 1.5-2 mg/L and HA at a concentration of 20-45 mg/L has a multiplier effect and allows to reduce the mortality rate of ciliates > 30% due to the enhanced removal of CIP. That finding demonstrated a clearly detoxifying role of dissolved organic matter (here, humic substances) in case of complex water pollution where pharmaceuticals and nanomaterials are presented.

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

Contamination soils with heavy metals is a problem with high interest, because contamination with heavy metals affect food chains and human health by intake and accumulation in living beings. Although all of these methods not quite effective for recovering contaminated environments, however they are still good options for recovering contaminated soils. In this research evaluated the recovering potential in different concentrations and combinations of dolomite with additives like zerovalent iron, Fe-Mn concretions, iron powder, ferrihydrite and iron nanoparticles. With these treatments, achieved reduction of concentration of all heavy metals founded (Co, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) and also reduction in toxicity, confirmed with a biotest with Daphnia magna. These findings confirms that the optimal remediants are nanoparticles with biochar and iron powder with and without biochar.

Interpolyelectrolyte complexes (IPECs) formed by the interaction of two oppositely charged polyelectrolytes have been proposed as soil structure stabilizers. However, little is known about the environmental safety of IPECs. The goal of this study was to investigate the toxicity of a positively charged IPEC formed by two commercial polymers, namely the cationic biopolymer poly(diallyldimethylammonium chloride) (PDDA) and the anionic biopolymer lignohumate (LH), a humic-based plant growth promoter. Toxicity was assessed using cultures of the bacteria Escherichia coli, the ciliate Paramecium caudatum, mammalian (Bos taurus) spermatozoa in vitro, and three plant species (Sinapis alba, Raphanus sativus, and Triticum durum). The responses of test organisms were evaluated in contact with (1) polymer and water and (2) polymer and soil. In water, PDDA and IPEC were highly toxic to bacteria and ciliates at all concentrations and less toxic to mammalian cells. Higher plants were less sensitive to the polymers, and the toxicity progressively decreased in the order PDDA > IPEC > LH. In soil matrices; the phytotoxicity of PDDA and IPEC was found to be quite low, and none of the polymers was toxic to plants at concentrations that allowed the formation of polymeric soil crusts against erosion. This is because the toxicity of cationic polymers decreases as they enter the soil matrix and bind to organic matter and minerals.

The main directions of using biotesting to assess the environmental risk of pollution-(a) predictive (predicting possible effects of chemicals and determining safe levels of their use) and (b) diagnostic, allowing one to assess the real hazard or damage at the moment-are considered. The historical stages of ecotoxicology development are analyzed. An idea is given about the variety of test systems and methods for assessing ecotoxicity and criteria for selecting test species in biotest batteries. Examples of the use of OMICS technologies, molecular biomarkers, nanoecotoxicology, and ecotoxicogenomics in the assessment of soil toxicity are presented. In world practice, in order to compare the results of standard tests, reference (standard, artificial) soil recommended as a reference sample according to the ISO11268 protocol. Attention is focused on the relevance of soil assessment based on the biotic concept of modern environmental control. The advantages and disadvantages of some methods and indices of the ecological state of soils based on the use of reactions of living systems to environmental pollution (in particular, the so called integral indicator of the biological state of the soil (IIBS), the functional diversity of the microbiome (FDM), and the state index according to the TRIAD methodology) are characterized. At the present stage, the best way to integrate the results of biotesting into the overall assessment of soils is an interdisciplinary TRIAD methodology, which implies a set of chemical, bioindication (in situ) and toxicological (ex situ) studies.

Heavy metals (HM) in the soil cause changes in the ratio of resistant and susceptible fungal species, the mechanisms of interaction between which are not well understood. The aim of this work is to study the resistance to Cu and Pb cations and the antagonistic properties of two species of soil micromycetes Alternaria alternata and Trichoderma viride. Fungal resistance was assessed by the following test functions: biomass accumulation, colony diameter, and sporulation activity. The antagonistic activity of fungal species was assessed by competition test. The calculated effective concentrations and tolerance indices made it possible to conclude that A. alternata and T. viride are highly resistant to the investigated HMs. At the same time, species differences in the patterns of reactions were found. The growth of A. alternata colonies was inhibited to a greater extent than T. viride, however at the same HM concentration, the stimulation of sporulation in Alternaria was more pronounced than in the rapidly growing Trichoderma. The studied strain T. viride turned out to be quite competitive with respect to the phytopathogenic fungus A. alternata, and its antagonistic properties were well pronounced in the medium with HM. The data obtained can be useful for predicting the phytopathogenic activity of micromycetes against the background of chemical pollution and the dynamics of accumulation of various fungal species under adverse environmental conditions.

Experimentally substantiated assessment of the remediation properties of humic products is an important condition for their safe and effective use. The review provides an analysis of existing approaches to biotesting of humic products, which enable us to draw a conclusion about the efficiency of detoxification of soils and adjacent media and about ensuring the viability of biocenoses, when using humic products. The advantages and disadvantages of traditional approaches to biotesting of humic products in soil media based on well-known reactions of higher plants and microorganisms, as well as the possibility of algotesting, using fluorescent methods, and mycotesting of humic products in aqueous and artificial nutrient media are discussed. The results of the experimental verification of the remediating ability of humic products during biotesting in media rich in organic substances indicate the need to standardize the conditions for the quantitative assessment of the quality of humic products. Standard artificial soil (according to ISO 11268-2) may be used as a universal soil matrix for the initial assessment of humic products. To summarize their quality as potential soil improvers, the proposed remediation index is calculated by the data of chemical, bioindication, and ecotoxicological studies of soil treated with humic products.

Melanin formation in fungi used to indicate chemical and radiation contamination of soils depends on the composition of the environment and nutritional conditions. The relevance of this study is due to the assessment of the indicator significance of melanin-containing fungi under different conditions. The structure of mycobiota was studied in technosoil samples from organic composted wastes and in natural soils differing in the content of heavy metals (HMs) and available sources of carbon nutrition (C-org.). The total number of micromycetes, diversity, and representation of melanin-containing fungi were assessed by inoculation method and using high-throughput genome sequencing. Both methods showed an increase in the number of colony-forming units (CFU) of melanin-containing fungi with an increase in the load of HMs in samples of soddy-podzolic soils. However, the traditional inoculation method also revealed a noticeable effect of the content of C-org. on the increase in melanized forms in the formed mycobiota of soils with HMs. Thus, in slightly humus soil (C-org. = 1.3%), the introduction of HMs led to an increase in the number of CFU for melanized forms by 38%, in highly humus soil (C-org. = 3.9) only by 18%. The obtained data confirm the proposition that in substrates depleted of carbohydrate nutrition, melanin formation contributes to an increase in resistance to redox stress. In the techno-soil from composted waste, despite the significant content of HMs, in particular, cadmium, the proportion of melanized fungi is small, which is probably due to the immaturity of fungal communities in the waste. A conclusion was made about the greater bioindicative informativeness of the microbiological inoculation method before expensive metagenomic sequencing, and the effectiveness of its use in environmental monitoring of soil pollution.

Comprehensive studies of soil contamination were performed in the area of settlement Kichi-Kemin (Kyrgyz Republic). Soils of the Kyrgyz Republic are exposed to waste (tailings) of many industrial enterprises of the mining industry not far from the village of A k-Tuz, located 145 km from the capital of Kyrgyz Republic, Bishkek, at an altitude of 2300 m above sea level. It is noted that 4.17 million tons of radioactive waste from one of the enterprises were once disposed of at four tailings in the Kichi-Kemin Valley. The main waste elements are radioactive thorium, heavy metals such as cadmium, molybdenum, lead, zinc, beryllium, and oxides of hafnium and zirconium. The impact of these wastes on soil ecotoxicity and microbial communities is not yet well understood. In this work, soil environmental assessment near waste deposits were investigated using an integrated method known as the Triad approach. The integral index of soil disturbance was calculated from the data of ecological observations of soil microbial communities (bioindication), data of ecotoxicological index by phytotesting approach (bioassay), and chemical index reflecting the results of a quantitative chemical analysis of the content of pollutants. The ecological index, calculated from the bioindication parameters of the soil microbiota communities, has become a reputable indicator of the state of soils from vulnerable mountain ecosystems. Studies of soil microorganisms have shown a decrease in species diversity in contaminated soils. The most resistant species of fungi were Aspergillus and Penicillium. Among the actinomycetes of the genus Streptomyces, the Albus and Cinereus sections proved to be stable. Estimation of anthropogenic impacts on mountain ecosystems in the Kyrgyz Republic using the Triad approach has shown that the most sensitive toxicity index in the soils of the Ak-Tuz is the ecotoxicological indicator litoxRI; determined by the phytotesting method. The integrated index calculated on the basis of the Triad method gave a more complete picture of the influence of pollutants on the soils ecosystem of the Ak-Tuz, characterizing its severe deterioration.