Search Results (3,409)

Metal-contaminated mining soils require management options that reduce environmental risk while enabling the controlled reuse of degraded land. Following the PRISMA extension for Scoping Reviews (PRISMA-ScR), this review synthesizes evidence on the use of non-food crops for the phytomanagement of metal-contaminated mining soils, with particular emphasis on crop establishment, agronomic performance, metal uptake and partitioning, biomass safety, valorisation pathways, and safe land reuse. Searches conducted in Web of Science, Scopus, and ScienceDirect, complemented by Google Scholar and manual screening, identified 7223 records; after duplicate removal and eligibility assessment, 85 publications were included in the final synthesis. The evidence indicates that non-food crops can support phytostabilization, exclusion-based phytomanagement, biomass production, and, in selected cases, phytoextraction. However, their suitability is strongly site-specific and depends on substrate constraints, contaminant behaviour, biomass quality, and residue-management requirements. Field and pilot-scale evidence remains less frequent than pot and greenhouse studies, which limits the direct transfer of findings to heterogeneous post-mining landscapes. Biomass safety emerged as a critical decision point because harvested biomass and conversion residues may become secondary contamination pathways. Based on the evidence map, this review proposes a seven-step conceptual decision-support framework linking site diagnosis, management objective definition, crop pre-selection and field-performance screening, metal-risk behaviour assessment, biomass safety assessment, land-reuse matching, and adaptive monitoring. The proposed framework is intended as a screening and planning tool and requires site-specific validation before operational implementation. Full article

Soil contamination with heavy metals (including Cu, Zn, Cd, and Pb), alongside climate change, represents a key challenge for the sustainability of forest ecosystems. Sycamore maple (Acer pseudoplatanus L.), as a pioneer species with high phytostabilization potential, can play a significant role in ensuring forest persistence in areas affected by industrial emissions. In this context, the abundance of natural sycamore maple regeneration was determined along a transect originating at the “Gilów” Extractive Waste Treatment Facility in Poland. On 13 research plots arranged along the transect, the share of sycamore maples was assessed within height classes of up to 0.5 m, 0.5–1.5 m, and above 1.5 m. Furthermore, the soil content of Cu, Zn, Mn, Fe, Pb, Cd, Ni, and Cr, among others, was determined for each plot. The results showed a statistically significant positive correlation between Acer pseudoplatanus regeneration and the soil content of iron and nickel, as well as a statistically significant negative correlation with lead content. The results concerning nickel suggest that low concentrations of this element may stimulate the natural regeneration of sycamore maple. Full article

Artificial soils derived from coal combustion by-products and industrial waste have been successfully used for mine spoil reclamation; however, their ecological risk and toxic element migration in the soil–plant system have not been assessed. The objective of this study was to evaluate the ecological risks in soil substitute covers after five years of their exposition, using the ecological risk factor (ERⁱ), potential ecological risk index (PERI) and geoaccumulation index. The modified BCR-sequential extraction method was applied to determine the chemical partitioning of the most toxic heavy metals (Cd, Cr, Cu, Ni, Pb, Zn). Additionally, the bioconcentration and translocation factors were used to assess the uptake of toxic elements by Phragmites australis. Findings from PERI indicate a moderate risk (239 and 258), mainly associated with moderate and considerable ERⁱ for Cd and Hg, respectively. The other toxic metals are associated with a low risk (ERⁱ < 40). Sequential extraction results showed the lowest concentrations of heavy metals in F1 fraction (0–30%) and increased in subsequent fractions: F2 (1–43%), F3 (10–62%) and F4 (10–89%). The calculated BCF values were below 1, indicating that the concentration of toxic metals in plants was lower than that in the soil substitute. The only exception was observed for Mn and Sn (BCF > 1). The results suggest that the tested soil substitutes are suitable for the reclamation of post-mining areas and may support sustainable biomass production. However, due to industrial atmospheric deposition and ecological risk associated with selected trace elements, continued monitoring of toxic metals is recommended. Full article

This study characterizes the physicochemical properties of coal gangue in Huainan, a typical coal resource-based city in China, and evaluates variations in its chemical composition and associated ecological risks. The results show that the coal gangue in the Huainan mining area is composed mainly of quartz and clay minerals, with SiO₂ and Al₂O₃ together accounting for over 86% of the total composition. Rare earth element concentrations are generally higher than background levels, whereas heavy metal concentrations are generally below the risk screening values for soil contamination of agricultural land. Complex associations are observed among the elements in coal gangue. The correlation coefficients between SiO₂ and the other oxides or heavy metals range from −0.750 to −0.993, indicating significant negative correlations and suggesting that the silicate mineral phase occurs independently of other element-enriched phases. The potential ecological risk index (RI) for heavy metals ranges from 33.75 to 300.71 and is driven primarily by Hg and Cd. The RI for rare earth elements ranges from 98.9 to 220.3, with Lu as the key influencing element. The predicted probability of adverse biological effects is 14–15%. Overall, classified management of coal gangue in the Huainan mining area is recommended, together with strengthened continuous monitoring of Hg and Cd and optimization of ecological disposal strategies by integrating potential ecological risk assessment with analysis of adverse biological effects, thereby further supporting the green transition of resource-depleted cities. Full article

This review provides a comparative critical synthesis of biochar and enhanced rock weathering (ERW), identifies key trends and gaps in soil carbon research, and outlines pathways for improving carbon sequestration and monitoring in soil systems. From a global perspective, materials and agricultural studies were read to examine the properties of these amendments and their effects in cropland and forest soils. The main research question guiding this literature review was as follows: What are common trends in published biochar and ERW studies? Major themes were derived from the stated question and structure the Discussion. The Web of Science provided access to relevant literature for both biochar and ERW, and a total of 38 articles (biochar: 17; ERW: 21) were read and covered in this paper. The findings conveyed the growing number of Chinese studies on these amendments to resolve climate-related soil quality affecting crop yields and potential for carbon sequestration, namely carbon dioxide removal or CDR—which sequesters CO₂ that is already in the atmosphere. Studies commonly used application rates of <5% for biochar and 5 or 50 t/ha for ERW, with (wood) biochar commonly processed at temperatures of 500–550 °C. Finer powders were known to be more effective due to their increased surface area, although there were emissions trade-offs to consider for climate change mitigation. There were options for using glacial rock flour (GRF) as an alternative. For ERW, the type of minerals matters, with basaltic amendments being most investigated and minerals like zeolite, for example, having quick responses and potential to filter out heavy metals. Depth of analysis was an issue in the studies, especially affecting ERW work—which needs to adopt greater depths (>60 cm) and both soil organic carbon (SOC) and soil inorganic carbon (SIC) or total carbon need address, particularly for ERW since studies only provided selective coverage. Biochar studies tended to focus more on crop yields and were not as concerned as ERW studies in CDR. Many studies agreed that these are promising products that need to be economically compared before being applied at a large scale. More field studies are needed to test biochar, while limitations imposed by soil pH (acidification affecting dissolution and nutrient availability) and climate need consideration for ERW—especially since it works best in warm, humid climates. The application rate and duration are important variables to also consider for ERW, and both SOC and SIC dynamics are subsystem components requiring consideration. Ultimately, studies call for field trials executed in the long term at greater depth and in different climates and representing different soil types. Full article

Soil pollution constitutes a critical global environmental challenge driven by industrialization, intensive agriculture, urban expansion, mining, and the application of synthetic agrochemicals. This article presents seven annotated Python-based Machine Learning (ML) workflows for soil pollution assessment, structured around five contaminant groups: heavy metals, pesticides, microplastics, per- and polyfluoroalkyl substances (PFAS), and excess macronutrients. The contribution has three distinct components. First, a literature synthesis drawing on more than 100 peer-reviewed studies contextualizes each contaminant group within current spectroscopic, geochemical, and ML-based detection frameworks. Second, a conceptual six-step workflow links field sampling, ML-based analysis, and scenario-based risk modelling to soil ecosystem service (SES) assessment. Third, seven executable Python scripts—implementing Random Forest regression, XGBoost with SHAP explainability, 1-D Convolutional Neural Networks, LSTM time-series forecasting, PCA-based dimensionality reduction, Monte Carlo uncertainty propagation, and GeoPandas geospatial mapping—serve as illustrative demonstrations using a benchmark dataset. All reported performance metrics are derived from synthetic data and represent workflow demonstrations, not validated field results. Radionuclides are acknowledged as an important contaminant class but fall outside the defined scope of this study. The scripts are provided as reproducible templates for adaptation to real contaminated-site datasets. Full article

A new fractional Brownian vector field (FBVF) is created for modeling multidimensional and multivariate fractal data. It is shown that the FBVF is a multidimensional and multivariate generalization of the classical Kolmogorov–Wiener process, allowing the distribution of field increments to be defined solely through fractal Euclidean distances between observation points. Conditions are established under which the family of field distributions satisfies the Kolmogorov consistency theorem. Maximum likelihood and variogram-based methods are developed to analytically estimate the mean and covariance of the FBVF, while the Hurst parameter is computed using an one-variable optimization algorithm. A kriging method is constructed for solving prediction problems using observations of fractal data. For computer simulation of field realizations, recursive and kriging-based algorithms are applied. A computational Monte Carlo experiment confirms the reliability of the proposed methods, particularly in accurately estimating the Hurst parameter. Applications to heavy metal concentrations in soil and climate data analysis demonstrate the effectiveness of the model in representing and analyzing multifractal, multidimensional processes. Full article

Spaceborne imaging spectroscopy has created new opportunities for monitoring soil properties at regional scales. Its use for predicting soil heavy metal concentrations in mountainous environments, however, remains insufficiently tested, especially when EMIT hyperspectral data are used. In this study, EMIT Level-2A surface reflectance data were integrated with DEM-derived terrain variables to estimate soil arsenic (As), copper (Cu), and zinc (Zn) concentrations in Renhuai, Guizhou Province, Southwest China. Only soil samples falling within valid EMIT coverage were used for element-specific modeling, resulting in 139 samples for As, 136 for Cu, and 130 for Zn. To reduce redundancy among predictors, EMIT spectral variables and terrain factors were screened before model construction. Random forest and XGBoost models were then tested using repeated spatial cross-validation. The best-performing model for As combined EMIT predictors with elevation and achieved a validation R² of 0.460. Model performance was considerably weaker for Cu, with a validation R² of 0.188. For Zn, the model failed to outperform the mean-based benchmark, producing a negative validation R² of −0.028. The spatial prediction maps and residual patterns suggested that the EMIT-based prediction showed moderate potential for As, limited predictive value for Cu, and exploratory rather than reliable mapping capability for Zn under the current sample and predictor conditions. Full article

Heavy metal (HM) contamination near mining operations in Kazakhstan poses a serious threat to the environment. However, data on the state of chernozem soils in this region is limited. This study assessed the bioaccumulation of HMs and translocation within the soil–sunflower (Helianthus annuus L.) system in a southern Calcic Chernozem in the Kostanay region (Northern Kazakhstan), which is located 50 km from the nearest mining facility. The content of seven HMs (Cd, Co, Cr, Cu, Ni, Pb, and Zn) and arsenic (As), as well as five macroelements (K, Ca, S, Mg, and P), was determined in 18 soil samples from the complete soil pedon (0–150 cm) and in eight anatomical parts of six sunflower plants at physiological maturity. Most metals exhibited a deficiency relative to upper continental crustal Clarke values (Clarke of Concentration (CC) < 1 for Cr, Cu, Ni, Pb, and Zn), with a moderate lithogenic anomaly for Cd (CC = 1.65–3.57) and a localized Co anomaly in the Bk horizon (56.26 mg kg⁻¹), indicating no pronounced HM contamination at the investigated agricultural site. Metal distribution exhibited strong organ specificity in sunflower plants. Cd, Cu, and Zn accumulated preferentially in the leaves, whereas Ni and Co were more concentrated in the seeds and stems, respectively. Only cadmium exceeded the threshold values for both BCF > 1 (1.01) and TF > 1 (1.47), confirming the status of sunflower as a cadmium accumulator. These results provide a preliminary reference dataset of the organ-specific distribution of heavy metals in H. annuus L. plants, which can serve as a local baseline for sunflower growth in uncontaminated southern Chernozems. This information can contribute to future environmental monitoring purposes in the region, acting as an exploratory benchmark. Full article

Severe Cu and Pb enrichment in loess areas of northwestern China, mainly associated with mining and smelting activities, has increased the demand for efficient soil decontamination. Electrokinetic (EK) remediation is a promising in situ technology because it can drive ionic contaminants through low-permeability porous media with limited excavation and relatively low secondary disturbance. In this study, the effects of electric field strength, electrode type, and catholyte pH on Cu and Pb removal from contaminated loess were systematically evaluated using a large-scale EK reactor. The full name of EKG is electrokinetic geosynthetics. During treatment, pH, electrical conductivity, electric current, cumulative electroosmotic flow (EOF), and the spatial distributions of Cu and Pb were monitored. Increasing the electric field from 1.0 to 2.0 V cm⁻¹ increased current and EOF and accelerated anodic acid-front propagation, but it also strengthened cathodic alkalization and precipitation. Compared with graphite electrodes, electrokinetic geosynthetics (EKG) electrodes maintained higher current and EOF, generated stronger acidification, and increased Cu and Pb removal by approximately 25% and 5%, respectively. Among the tested catholyte conditions, pH 7.0 provided the best balance between electromigration and electroosmosis, achieving overall soil-phase removal efficiencies of approximately 19.0% for Cu and 8.0% for Pb. These results show that coordinated regulation of the electric field, electrode architecture, and electrolyte chemistry can mitigate the focusing effect in loess, although further enhancement is still required for field-scale decontamination. Full article

Heavy metal contamination of soils represents a persistent environmental challenge, for which in situ immobilization has emerged as a cost-effective and technically viable alternative to conventional invasive remediation technologies. This review comparatively evaluates three distinct categories of soil amendments—biochar, zeolite and attapulgite—within a unified analytical framework integrating extractable fractions (TCLP, DTPA, and CaCl₂) and geochemical fractionation approaches (BCR and Tessier). The novelty of this study lies in the systematic assessment of the dominant immobilization mechanisms associated with each amendment in relation to soil properties and the chemical speciation of the target metal, as well as in distinguishing between an apparent reduction in metal extractability and a genuine shift toward more stable geochemical fractions. The findings identify ion exchange as the primary immobilization mechanism in zeolites (NaA zeolite, 1–5% w/w, 96% reduction in TCLP-extractable Pb and 91% reduction in TCLP-extractable Cd), the synergistic action of adsorption, complexation, and precipitation in biochar systems (manure-derived biochar, 0–5% w/w, 97.4% reduction in the exchangeable Pb fraction according to the Tessier scheme), and the critical role of surface modification in attapulgite-based amendments (C-ATP, 4% w/w, 95.1% and 74.3% reductions in TCLP-extractable Pb and Cd, respectively). Because these efficiencies were obtained using different extraction protocols, they are not directly comparable. At the same time, cases of adverse responses were identified, including increased As extractability following the application of phosphate-modified biochar and the redistribution of Pb and Cd after amendment with natural zeolite in industrially contaminated soil. These observations highlight that amendment performance is not an intrinsic property of the material itself, but rather the outcome of specific geochemical interactions occurring within the soil system. Increased soil pH emerged as the principal common factor promoting metal stabilization across all amendment categories, whereas substantial variability in amendment dosage, incubation period, and analytical methodology limited direct quantitative comparisons among studies. Consequently, the selection of an appropriate soil amendment should be based on the integrated evaluation of soil physicochemical properties, contaminant speciation, and the intended scale of application, supported by long-term monitoring under field conditions. Full article

In the current study, soil samples were collected from regions contaminated with industrial waste containing petroleum and its derivatives, including areas around a tire factory in Kırşehir, a chrome factory in Mersin and Kazanlı, and the Karaduvar refinery regions in Mersin, Türkiye. A total of 40 bacteria were isolated from the soil samples. The isolates were identified using molecular methods as well as morphological, physiological, and biochemical tests. Based on the results of 16S rRNA sequence analysis, it was revealed that the isolates belonged to the genera Bacillus, Diaphorobacter, Cupriavidus, Acinetobacter, Massilia, Staphylococcus, and Azospirillum. The antibiotic and heavy metal resistance of the strains were determined. Furthermore, the Drop Collapse method was employed to evaluate the biosurfactant production abilities of the strains, confirming that certain strains possess biosurfactant-producing capabilities. Consequently, distinct bacterial species capable of degrading polyaromatic hydrocarbons, resisting antibiotics and heavy metals, and producing biosurfactants were successfully isolated from contaminated areas in the current study. It is thought that the utilization of species with these properties in bioremediation studies will contribute to the restoration of ecosystem balance. Full article

Polymetallic mining severely disrupts farmland soil ecosystems, yet the vertical migration of heavy metals, interlayer pollution disparities between topsoil and deep soil, and quantitative source apportionment of composite pollutants remain poorly understood in mining–agricultural overlapping zones. Two core hypotheses were accordingly proposed: mining-derived heavy metals can migrate downward and accumulate in deep soil layers, and the coupling of geostatistical analysis and receptor modeling enables reliable differentiation between geogenic and anthropogenic pollution sources. To test these hypotheses, 512 topsoil and 148 deep soil samples were collected from the Fenghuang Mining Area for quantification of eight metals and metalloids (including As). Geostatistical approaches, the single pollution index (Pi), and Nemerow comprehensive pollution index (P_N) were utilized to characterize spatial heterogeneity and evaluate pollution severity, while a coupled PCA–PMF receptor model was adopted for quantitative source identification; vertical comparisons of element concentrations across soil profiles further validated the robustness of source apportionment outputs. The results revealed extensive heavy metal enrichment in both soil layers, with only topsoil Cd exceeding China’s risk screening value for agricultural land. Hg exhibited pronounced spatial variability and prominent anthropogenic fingerprints, and all target metals displayed consistent spatial distribution patterns along vertical soil profiles. Four distinct pollution sources were discriminated: geogenic sources dominating Cu, Zn, Cr, and Ni accumulation, mining-industrial emissions as the major contributor to Hg pollution, mixed industrial–agricultural inputs governing As and Pb enrichment, and traffic activities serving as the primary Cd source. Cd was identified as the priority pollutant threatening local farmland security. Confirmed downward percolation of anthropogenic metals creates persistent latent ecological risks across the study area, where mining and industrial discharges represent the dominant anthropogenic pollution inputs. This work systematically elucidates the geochemical signatures, vertical migration pathways, and quantitative source contributions of heavy metals in mining-disturbed farmlands, delivering solid scientific support for targeted source control, tiered risk management, and soil ecological remediation within the Fenghuang Mining Area. Moreover, the multi-method integrated analytical framework developed herein provides transferable guidance for heavy metal pollution mitigation in global polymetallic mining–agricultural regions with analogous geological and industrial backgrounds. Full article

Despite extensive studies, global patterns governing the accumulation of essential and non-essential elements in grapevine leaves remain insufficiently understood. Therefore, a comprehensive literature survey of 148 studies (selected according to PRISMA 2020 guidelines) was compared with authentic elemental analyses of young and mature leaves of the white cultivar Rhein Riesling and the red cultivar Cabernet Sauvignon to identify the major drivers of grapevine leaf ionome composition. In unstressed grapevine leaves, macroelements followed the concentration order Ca > K > Mg > P, whereas microelements decreased in the order Fe > Mn > Cu > B > Zn > Mo. Seasonal development was associated with opposite trends between Ca and Mg versus K and P. Geographic origin and berry color were associated mainly with differences in Ca, P, Mn, Cu and Fe concentrations. In our authentic samples, potentially toxic elements occurred at substantially lower concentrations than commonly reported in the literature (mainly Pb, Co, As, Cd, Cs, Al, Sr, Ba, Li and Zr). Mature leaves accumulated higher levels of non-essential elements than young leaves, although bioaccumulation from soil remained generally low. Correlation analyses further demonstrated cultivar-dependent relationships among elements, particularly involving Mg. Multivariate analyses revealed that leaf developmental stage represented the primary factor shaping elemental composition, while cultivar-specific effects constituted a secondary but detectable source of variation. Our results identify phenological stage as a dominant factor controlling ionomic composition and suggest that Mg-, Fe-, Zn-, and Cu-associated processes may contribute to the regulation of the accumulation of toxic elements in grapevine leaves. Full article

Soil contamination around iron ore complexes in semiarid zones is usually described by total metal concentrations, which underestimate the labile mobile pool. At the Sokolovka-Sarbai mining and beneficiation complex (SSGPO, Northern Kazakhstan), total (EPA 3051A) and mobile (neutral NH₄OAc, pH 7) forms of ten heavy metals were analyzed in 87 site-horizon composites (29 sites × 3 pits × 3 horizons; 261 field samples). Descriptive indices flag Co as the only moderately contaminated element (I_geo 1.16) and Mn as the only one in persistent deficit (Kc_total 0.62); Co and Mn show the largest mobility-factor increments above background (Δ_MF +17.8 and +22.3 p.p.). The priority toxic elements As, Cd and Pb remain at or near depth-matched background in the total fraction (median Kc_total 0.98–1.09; I_geo < 0 for all three), although Pb shows a moderate mobile-fraction enrichment (median Kc_mobile 2.6); mercury was not among the ten metals analyzed. Factor analysis of mobile forms resolves two independent sources (F1-siderophile Cr-Ni-Fe-Mn-Co; F2-Zn-dominant, non-sphalerite) and a humus-driven sorption pool (F3), coherently localized in the dump2A-pit2 sector; mobile-fraction attribution greatly outperforms the total fraction (21 vs. 0 FDR-significant trends). The raw Mn-deficit-Co-mobility correlation (ρ = −0.54) is fully mediated by humus (partial ρ = +0.05). Total Mn deficit and enhanced Co lability are therefore interpreted as coupled consequences of a single humus-Ca-pH Kastanozem geochemistry rather than a causal “Mn-buffer depletion → Co mobilization” chain. Because the dataset is cross-sectional, this distinction remains correlational; sequential fractionation and mineralogical verification are priorities for future work. Full article