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In response to global agricultural challenges, this review examines the synergistic impact of bioslurry and biogenic nanoparticles on soil amelioration. Bioslurry, rich in N, P, K and beneficial microorganisms, combined with zinc oxide nanoparticles synthesized through eco-friendly methods, demonstrates remarkable soil improvement capabilities. Their synergistic effects include enhanced nutrient availability through increased soil enzymatic activities, improved soil structure via stable aggregate formation, stimulated microbial activity particularly beneficial groups, enhanced water retention due to increased organic matter and modified soil surface properties and reduced soil pH fluctuations. These mechanisms significantly impact soil physico-chemical properties including cation exchange capacity, electrical conductivity and nutrient dynamics. This review analyses these effects and their implications for sustainable agricultural practices, focusing on crop yield improvements, reduced chemical fertilizer dependence and enhanced plant stress tolerance. Knowledge gaps such as long-term nanoparticle accumulation effects and impacts on non-target organisms are identified. Future research directions include optimizing bioslurry-nanoparticle ratios for various soil types and developing "smart" nanoparticle-enabled biofertilizers with controlled release properties. This innovative approach contributes to environmentally friendly farming practices, potentially enhancing global food security and supporting sustainable agriculture transitions. The integration of bioslurry and biogenic nanoparticles presents a promising solution to soil degradation and agricultural sustainability challenges., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

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., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

The rapid expansion of degraded soil puts pressure on agricultural crop yield while also increasing the likelihood of food scarcity in the near future at the global level. The degraded soil does not suit plants growth owing to the alteration in biogeochemical cycles of nutrients, soil microbial diversity, soil organic matter, and increasing concentration of heavy metals and organic chemicals. Therefore, it is imperative that a solution should be found for such emerging issues in order to establish a sustainable future. In this context, the importance of plant growth-promoting rhizobacteria (PGPR) for their ability to reduce plant stress has been recognized. A direct and indirect mechanism in plant growth promotion is facilitated by PGPR via phytostimulation, biofertilizers, and biocontrol activities. However, plant stress mediated by deteriorated soil at the field level is not entirely addressed by the implementation of PGPR at the field level. Thus, emerging methods such as CRISPR and nanotechnological approaches along with PGPR could manage degraded soil effectively. In the pursuit of the critical gaps in this respect, the present review discusses the recent advancement in PGPR action when used along with nanomaterials and CRISPR, impacting plant growth under degraded soil, thereby opening a new horizon for researchers in this field to mitigate the challenges of degraded soil., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Current study was conducted to evaluate the effect of important land uses and soil depth on soil organic carbon pools viz. total organic carbon, Walkley and black carbon, labile organic carbon, particulate organic carbon, microbial biomass carbon and carbon management index (CMI) in the north Western Himalayas, India. Soil samples from five different land uses viz. forest, pasture, apple, saffron and paddy-oilseed were collected up to a depth of 1 m (0-30, 30-60, 60-90 cm). The results revealed that regardless of soil depth, all the carbon pools differed significantly ( p  < 0.05) among studied land use systems with maximum values observed under forest soils and lowest under paddy-oilseed soils. Further, upon evaluating the impact of soil depth, a significant ( p  < 0.05) decline and variation in all the carbon pools was observed with maximum values recorded in surface (0-30 cm) soils and least in sub-surface (60-90 cm) layers. CMI was higher in forest soils and lowest in paddy-oilseed. From regression analysis, a positive significant association (high R-squared values) between CMI and soil organic carbon pools was also observed at all three depths. Therefore, land use changes and soil depth had a significant impact on soil organic carbon pools and eventually on CMI, which is used as deterioration indicator or soil carbon rehabilitation that influences the universal goal of sustainability in the long run., Competing Interests: The authors declare there are no competing interests., (©2023 Mir et al.)

Recent results revealed that considerable Pb accumulation in plants is possible under specific soil conditions that make Pb phytoavailable. In this review, the sources and transformations of Pb in soils, the interaction of Pb with bacteria and specifically the microbiota in the soil, factors and mechanisms of Pb uptake, translocation and accumulation in plants and Pb toxicity in living organisms are comprehensively elaborated. Specific adsorption and post-adsorption transformations of Pb in soil are the main mechanisms affecting the mobility, bioavailability, and toxicity of Pb. The adsorption ability of Pb largely depends on the composition and properties of soils and environmental conditions. Microbial impact on Pb mobility in soil and bioavailability as well as bacterial resistance to Pb are considered. Specific mechanisms conferring Pb-resistance, including Pb-efflux, siderophores, and EPS, have been identified. Pathways of Pb entry into plants as well as mechanisms of in planta Pb transport are poorly understood. Available evidence suggests the involvement of Ca transporters, organic acids and the phytochelatin pathway in Pb transport, mobility and detoxification, respectively., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The manuscript presents the materials of soil fertility analysis of agricultural lands in the north-eastern forest-steppe of the Republic of Bashkortostan in the conditions of the Salavatskiy district of the republic (Russian Federation). Agrochemical analysis of the humus accumulation, mobile phosphorus, exchangeable potassium was carried out, morphological properties were studied, the thickness of the humus horizon, granulometric composition and soil erosion were determined. During the 49-year period of agricultural land use, it was revealed some of the medium-humus soils passed into the category of high-humus, caused by the fact that the arable lands were not used for cultivating crops and they were withdrawn from circulation and sown with many-year-old grasses. As to the thickness of the humus horizon, low-yielding soils predominate, which occupy 60.11%, average 32.9%. The main land area belongs to slightly washed soils of 67,445.2 ha (58.2%) and unwashed 36,985.5 ha (31.9%). Agricultural lands are mainly characterized as medium-humus (80.3%) and obese (12.1%) ones. Based on the results of the research, an adjustment, digitization and a new soil map of the Salavatskiy district was made with the allocation of the main types and subtypes of soils with the indication of varieties on a scale of 1:25,000., (© 2022. The Author(s).)

The study was conducted to evaluate the suitability of different weed management practices under influence of varying levels of N doses to test their effects on the various soil microflora and dehydrogenase enzyme activity in the winter onion field during 2016-2017 and 2017-2018. There were a total of twenty eight treatments replicated three times under the split-plot design (SPD). The treatments associated with weed management practices were applied to the main plots and the different N doses were given in each subplot. Microbial population and dehydrogenase enzyme activity in soil and crop weed competition index were determined. The two-hand weeding (HW) at 20 and 40 days after transplanting (DAT) of onion seedlings as well as preplant application of oxyfluorfen along with one HW at 40 DAT, exhibited a significant increase in dehydrogenase activity and microbial population in the soil when the N was applied at 100 kg ha -1 . The study suggests that suitable weed management practices for the winter onion exerts a transient impact on soil microbial population, maintained good soil health and reduced crop-weed competition (CWC) with relatively less environmental hazards., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The spatial and temporal distribution pattern is an outstanding feature of the relationship among ecosystem services (ESs) that explains links between human activities and disturbed chemical composition of ecosystems. This study investigated the spatiotemporal variation of land use/cover changes (LUCC) and quantifies the change in four essential ecosystem services with an emphasis on soil (nutrient delivery ratio, carbon storage, crop production, and water yield) and their relationships in the Jiroft plain, Iran, during 1996-2016 through analytical tools including Land Change Modeler, and the Integrated Valuation of Ecosystem Services and Tradeoff. During the 20-year concentrate period, there was a considerable overall gain in cropland (5396 km 2 ) and urban (1787 km 2 ), loss of unused land (5692 km 2 ), water (2088 km 2 ), and forest (1083 km 2 ). As a result of LUCC, while crop production and nutrient delivery ratio showed a rising trend, overall carbon storage and water yield decreased. The spatiotemporal trade-off between carbon storage and crop production, the temporal trade-off between crop production and water yield, and synergy between water yield and crop production were widespread in Jiroft plain. These results showed that the interaction among ESs mutates over time and can be changed under planning and policies. This study will enrich the research of the geographical distribution of ESs interaction in dryland ecosystems to provide practical ecosystem management under local conditions., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

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 Cа 2+ , Mg 2+ , SO 4 2- partly bonded as ion pairs. Oversaturation of the soil solution with CaCO 3 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 Pb 2- 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.3 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 Pb 2+ 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., (Copyright © 2020. Published by Elsevier Inc.)

Complex studies of soil cover within the urbanized areas represent one of the main research directions in environmental geochemistry. Urban soil geochemistry depends on a combination of natural and urbanization factors unique to each urban environment. Although Tyumen, in Western Siberia, is an intensively developing urban city, a detailed geochemical survey of its soils has never been performed. In this study, we conducted a systematic geochemical soil survey across the urbanized area of Tyumen, Russian Federation. Surface soil samples (0-10 cm) were collected from 241 sampling sites: 1 × 1 km regular grid for highly urbanized areas, and 4 × 4 km grid for peripheral parts of the city. The contents of V, Cr, Co, Ni, Cu, Zn, As, Sr, and Pb were determined using XRF analysis. Data were interpreted using GIS and multivariate statistical analyses, including hierarchical cluster analysis and principal components analysis. The results showed a non-uniform spatial distribution of individual metals, associated with natural soil-lithological conditions and urban environment characteristics. Our data showed that variation in soil element content was origin dependent: V, Cr, and Co contents were related to their natural origin; As and Pb to their anthropogenic origin; and Ni, Cu, and Zn to their mixed origin. Elevated V, Cr, Co, Ni, Cu, and Zn contents correlated with proximity to motorway networks and machinery. Strong As and Pb anomalies were associated with the activity of battery enterprises. The spatial distribution of Sr was significantly different from other studied elements - anomalous content of this metal was confined to hydromorphic boggy landscapes of the city's northern part. In general, Tyumen territory was slightly polluted with metals. Zn and Pb contents were slightly lower than in most cities with similar population levels, while those of V and Co were higher. Other metal contents were comparable to those in large cities, with a long history of industrial development. Elevated Cr, Ni, Zn, Cu, As, Pb, and Co contents were observed in areas that developed during mid last century., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Polycyclic aromatic hydrocarbons (PAHs) are widely distributed environmental toxicants primarily formed during the incomplete combustion of organic materials (for example, coal, oil, gasoline and wood). Power energy plants are the main sources of organic contaminants including PAHs. The purpose of the present research was to study the Novocherkassk Electric Power Station (NEPS) emission effects of PAHs accumulation in soils. The regional levels, types (groups) and spatial distribution of 16 priority PAHs were investigated. The monitoring sites were located on fallow lands of the 20 km around NEPS. PAHs extraction from collected soil samples was performed using the ecologically clean express-method of subcritical water extraction. The total PAHs content gradually increased in soil of the studied territories during 2016-2017 due to an increase in contaminants emission. Accordingly 16 priority PAHs were determined in the soil samples collected from the sites located to the northwest from NEPS in direction of predominant winds. The 5-km zone situated in direction of predominant winds was highly subjected to PAHs contamination, with maximal accumulation at a distance of 1.6 km from the source. The ratio of high- and low-molecular weight PAHs content in soils of monitoring sites was taken as an index of environmental soil contamination. The high-molecular weight PAHs concentration prevailed in monitoring sites soils situated in direction of predominant winds from NEPS, while the concentration of low-molecular weight PAHs prevailed in the monitoring sites soils situated around NEPS. Soil properties also influenced PAHs accumulation. Polyarenes content in Haplic Chernozems and Haplic Chernozems (Stagnic) was higher versus Fluvisols. This study provides the understanding and model the fate of PAHs in regional technogenic landscape., (Copyright © 2018 Elsevier B.V. All rights reserved.)

AGRICULTURE productivity is severely hampered by salinity stress in many parts of the world, including the Ararat Plain in Armenia. The need for food security is growing worldwide, and new strategies are essential to meet this challenge. In the context of the Ararat Plain, this paper examines the potential utility and promising role of biogenic nanoparticles (NPs) and biochar in reducing salinity stress, boosting crop resilience, and guaranteeing sustainable food production. This paper involves the mechanisms underlying salinity stress, as well as the properties and synthesis of biogenic nanoparticles and biochar, and their applications in increasing plant salinity tolerance. The potential application of biogenic nanoparticles and biochar to mitigate the adverse effects of salinity on crops, soil, and water resources has been recently illustrated by several case studies and research findings. Additionally, we go over the safety issues, environmental implications, and potential applications of biogenic nanoparticles and biochar in sustainable agriculture on the Ararat Plain and elsewhere. This paper advances our knowledge of innovative strategies for addressing salinity stress and improving food security in areas with comparable problems. [ABSTRACT FROM AUTHOR]

This study examines the adaptation of an undocumented halophyte, Dandur, to salt stress in different soil mediums. The Dandur plant physiological, morphological, and biochemical analyses show that it can withstand salinity stress. Dandur plants grown in clay and clay loam soil experienced significant decreases in height and stem diameter under extreme salinity conditions compared to non-saline soil. The fresh weight of root and shoot decreased by 70.4% and 84.8%, respectively, and dry weight by 48.5% and 79.7%. These findings underscore the importance of maintaining saline soil conditions for plant growth. Dandur unique ability to avoid dehydration and maintain growth traits, particularly in clay soil, holds promise for further exploration in agricultural research and food security-related issues caused by climate change in saline areas of Armenia and other European countries. [ABSTRACT FROM AUTHOR]

The research of the fundamentals of the behavior of behavior in the soil–plant system during their co-contamination is of high interest because of the absence of technologies for the creation of effective, environmentally friendly and cost-effective remediation methods, as well as integrated systems for predicting the quality of soils co-contaminated with HMs and PAHs. The unique model vegetation experiment was studied with Haplic Chernozem contaminated by one of the priority organic toxicants, benzo[a]pyrene (BaP), applied alone and co-contaminated with Cu with the subsequent vegetation of tomato (Solanum lycopersicum) and spring barley plants (Hordeum sativum Distichum). Biochar obtained from sunflower husks was used as a sorbent for the remediation of the contaminated soil. It was established that by increasing the BaP amount applied to the soil, the rate of BaP degradation improved. The effect was enhanced in the presence of biochar and decreased in the case of joint co-contamination with Cu, which is especially expressed for the soil of tomato plants. The half-degradation time of the BaP molecule varied from 8 up to 0.2 years for tomatoes and barley. [ABSTRACT FROM AUTHOR]

Conventional fertilizers and pesticides are not sustainable for multiple reasons, including high delivery and usage inefficiency, considerable energy, and water inputs with adverse impact on the agroecosystem. Achieving and maintaining optimal food security is a global task that initiates agricultural approaches to be revolutionized effectively on time, as adversities in climate change, population growth, and loss of arable land may increase. Recent approaches based on nanotechnology may improve in vivo nutrient delivery to ensure the distribution of nutrients precisely, as nanoengineered particles may improve crop growth and productivity. The underlying mechanistic processes are yet to be unlayered because in coming years, the major task may be to develop novel and efficient nutrient uses in agriculture with nutrient use efficiency (NUE) to acquire optimal crop yield with ecological biodiversity, sustainable agricultural production, and agricultural socio-economy. This study highlights the potential of nanofertilizers in agricultural crops for improved plant performance productivity in case subjected to abiotic stress conditions. [ABSTRACT FROM AUTHOR]

It was evaluated the impact of biochar on the petroleum hydrocarbons degradation intensity and the ecological condition of Haplic Chernozem. The study was conducted in the model experiment conditions with Haplic Chernozem contaminated with 5% of petroleum hydrocarbons with application of 10 and 20% biochar. The number of soil bacteria, the activity of catalase and dehydrogenases, germination ability and radish root and shoot length, soil respiration considered to evaluate biological activity. It has been established that 10% biochar application led to intensification of petroleum hydrocarbons degradation up to 17% compare to contaminated soil. Upon adding 10% biochar the -2 emission increased up to 70-85% on the 18-19th days, then reduced by the 28-30th days till soil emission with the application of biochar in the amount of 20% from soil mass. Activity of dehydrogenases of Haplic Chernozem were stimulated after application of 10% biochar up to 49% compared to control. Biochar application in the doses of 10 and 20% increased the number of soil bacteria up to 209 and 203%, respectively. Application of 20% biochar intensified the germination and early growth of radish seeds. The germination ability, length of radish shoots and roots increased to 44, 66 and 44%, respectively, compare to control. The biochar application in petroleum contaminated soil increased the activity of catalase, dehydrogenases and the number of soil bacteria. Biochar using in doses 10% and 20% contributes to acceleration of petroleum hydrocarbons degradation and improvement of the soil ecological condition. [ABSTRACT FROM AUTHOR]

The growth and development of plants is one of the criteria for assessing the degree of soil pollution with heavy metals. Morphological and anatomical changes in test plants affected by pollutants, such as growth retardation, shoot bending, and decreased root length and mass, indicate the worsening of environmental conditions. The effect of various ratios of soil and sand polluted with copper (Cu) on morphobiometric parameters of spring barley (Hordeum sativum distichum), Ratnik variety, was studied in a model vegetative experiment. Haplic calcic chernozem was used as a substrate with different ratios of soil/sand. It was determined that an addition of sand into the soil in the amounts of 25%, 50% and 75% of soil mass resulted in the alteration of the physical properties of the chernozem, which was reflected in the morphometric parameters of the plants. The most notable changes in the parameters were observed after pollution of soil-sand substrates with Cu(CH3COO)2 in the amounts of 250 mg/kg, 500 mg/kg, 1000 mg/kg and 2000 mg/kg. The maximum growth and development retardation of the barley plants was found at the maximum content of sand and the maximum concentration of Cu. The pollutant reduced the root length and, to a lesser degree, the height of the aboveground components of the plant, which as a result, decreased the total plant biomass. [ABSTRACT FROM AUTHOR]

Thallium (Tl) was introduced into Haplic Chernozem in the amounts of 3, 30, and 300 mg/kg, and biological indicators were observed at 10, 30, and 90 days after incubation in the laboratory experiment. An increase in biological activities; i.e., the total number of bacteria, Azotobacter spp. abundance, enzymes (catalase, dehydrogenases), and phytotoxic indicators (germination rate of radish) after 30 days of Tl exposure were noted. The total number of bacteria and Azotobacter spp. abundance, enzyme activity, and phytotoxicity were more sensitive (16-76%) and informative (12-65%) indicators compared to the control, respectively. Integral biological indicators of soil state (IIBS) noted at 10, 30, and 90 days decreased at a dose of 30 and 300 mg/kg by 13-43% in relation to the control. An increase in Tl concentration and duration of exposure (up to 90 days) inhibited biological properties and caused ecotoxicological effects, respectively. We concluded that the use of individual indicators served as an indicator of the state of the soil. [ABSTRACT FROM AUTHOR]

Nanotechnology paradigm is to endow the agriculture with new tools to increase sustainable food production. Although numerous benefits, the unsafe discharge of nanoparticles (NPs) in the environment is an issue. The unregulated exposure to the soil is expected to impair plant growth and accumulate into edible tissues. As a consequence, human exposure becomes inevitable. The problems of detecting NPs in soil and uptake mechanism in plants are ones of the critical aspects that necessitate being determined and understood. Therefore, the accurate determination of environmentally released NPs and their accumulation in plants, and the impact on health are imperative to assess. [ABSTRACT FROM AUTHOR]

Laboratory-dried specimens yield distorted information about the state of hydromorphic soil. Changes in the gas medium, humidity, temperature, aggregation capacity and illumination have an irreversible impact on the dried and powdered soil specimen. Properties of the dried hydromorphic soil can be altered significantly. Most altered are (1) the colour of the hydromorphic soils, (2) the рН value, and (3) the content of mobile trace metal (TM) compounds after drying the wet soil. Colour change (browning) of the hydromorphic soil is related to the oxidation of Fe(II). In a highly ferruginous soil, the browning is rapid and visible even to the naked eye. In the weakly ferruginous gley, the colour change is invisible to the naked eye, but instrumental field measurements reveal a slow and slight yellowing of the dried gley. In dried soils, laboratory рН values determined in soil suspension differ from the values determined in soil solution at the same time. The process of drying provokes a significant decrease in the content of mobile TM compounds, resulting in the illusion of less soil contamination than the real situation during hydromorphic soil humidification. When studying hydromorphic soils, it is desirable to accomplish the maximum possible field measurements. Laboratory analyses should only be carried out for specimens stored under dark conditions since they retain the initial humidity, temperature and gas composition. [ABSTRACT FROM AUTHOR]

This study is aimed at elucidating the fractionation of Cu and Zn in Haplic Chernozem and its alteration under the contamination to evaluate the extraction selectivity of different extractants and thus the efficiency of three sequential extraction schemes (Tessier and McLaren five-step and modified BCR three-step methods). General trends in the distribution of Cu and Zn speciations revealed with these three fractionation schemes suggest that they can be applied for the soils and the obtained results can be compared. Low mobility of potentially toxic metals (PTM) in the studied soil is suggested not only by their high content in residual fraction, but also by low contents of exchangeable and carbonate bound fractions (not more than 4-5% Cu and 5-7% Zn in the first two fractions). The highest contribution to the absorption and retention of Cu delivered from anthropogenic sources is made by organic matter and sesquioxides (up to 29%); for Zn, by the nonsilicate Fe and Mn compounds (up to 25%). However, the pattern of PTM extraction from soils varies during the application of different fractionation methods. The Tessier method is distinguished by a higher extractability relative to organic matter and sesquioxides. Therefore, this method is more informative for the contaminated soils. The McLaren method makes it possible to track the weakly bound species of compounds without the risk of involving other soil components. The BCR method is marked by simplicity of application and, therefore, recommended only for the noncalcic or low-calcic soils. [ABSTRACT FROM AUTHOR]

The speciation of Cu, Pb, and Zn compounds in Haplic Chernozem under the anthropogenic impact of a power plant mainly operating on coal was studied. General tendencies in the distributions of Cu, Pb, and Zn among the compound forms were revealed using selective sequential extractions (Miller method modified by Berti and Jacobs (1996)), which is based on the nature of metals and the participation of soil components. In an uncontaminated soil occurring far from the emission source, 55–85% of total Cu, Zn, and Pb fractions are concentrated in the residual fraction characterizing the metal bond with silicates. In uncontaminated soils, the contents of Cu, Pb, and Zn in crystallized Fe compounds are largely higher than in its amorphous forms. Metals accumulate in the soil occurring near the power plant, which increases the total contents of Cu, Pb, and Zn in 1.3–2.5 times and their mobile (water-soluble, exchangeable, and carbonate-bound) compounds in 2–12 times. The largest contributions to the adsorption and retention of metals are made by silicates, as well as soil organic matter for Cu and Pb and nonsilicate Fe compounds for Zn. A significant increase in the exchangeable Zn fraction is observed in studied soils. The estimation of the degree of metal fixation in the soil was calculated Partition index of element, which reflects the degree of metal-soil bonding. It showed that the highest parameter value for the studied metals was found for the soils located at 15 km from the NPP, where the Index values approach 1; the lowest Index value is noted for contaminated soils nearby from the enterprise. Thus, sequential extraction is an effective tool to check the affinity of the soil components for Cu, Pb and Zn. Image 1 • The metals fractional distributions in soil under contamination was studied. • Soil organic matter for Cu and Pb is the main soil binding compound under contamination. • Zn content bound to amorphous and crystalline Fe was increased under contamination. [ABSTRACT FROM AUTHOR]

Humic substances (HS) are widely used for diverse purposes. The effect of HS on the metal's status in contaminated soils is contradictory. The aim of this work was to investigate the Cu migration in soils treated with HS. A model field experiment with the addition of Cu (1.243 mg Cu/kg) and HS Extra® (potassium humate) was performed. The Cu addition resulted in acidification (by 0.7 pH) after 3 months. The major part of the added Cu remained in the upper 7-cm-thick soil layer; 4% reached the lower soil layer, while only 0.1% were removed beyond the profile. The addition of HS mitigated soil acidification increased the content of Cu bound to solid-phase organic substances and abruptly reduced the Cu activity in the soil liquid phase. Simultaneously, the HS addition increased the water-soluble organic substances (WSOS) by four times, including those in the hydrophilic and hydrophobic fractions, resulting in a twofold increase in the content of soluble Cu. Copper complexes with hydrophilic WSOS mainly reached lysimeters, and hydrophobic organic substances were absorbed by the soil. The HS addition to a slightly acidic soil can accelerate the migration of Cu to adjacent environments. [ABSTRACT FROM AUTHOR]