Search Results (217)

Increasing soil contamination by potentially toxic elements (PTEs) compromises environmental quality and ecosystem health, reinforcing the need for effective remediation strategies. Phytoremediation uses plants to remove, immobilize, or neutralize contaminants and represents a sustainable approach for restoring contaminated soils. Although nickel (Ni) is an essential plant micronutrient, elevated concentrations can cause phytotoxicity. This integrative review aimed to synthesize and critically analyze the scientific literature on the phytoremediation of Ni-contaminated soils published between 2000 and 2026, focusing on the plant species evaluated, their phytoremediation potential, and the main research trends and knowledge gaps. The Web of Science Core Collection search identified 230 records. Original research articles addressing the phytoremediation of Ni-contaminated soils and providing sufficient information to characterize phytoremediation potential were considered eligible, resulting in 91 included studies. Plant responses varied according to species and Ni concentration. Among 449 plant records, defined as the occurrence of a plant taxon within a study, more than 86% corresponded to herbaceous plants; Poaceae accounted for 27.2% of the records, followed by Brassicaceae (15.1%). Brassica juncea was consistently identified as a promising species for Ni phytoremediation, showing Ni tolerance, phytoextraction, and hyperaccumulation across different studies. Alyssum murale stood out among the reported hyperaccumulators for its high Ni accumulation and phytoextraction potential. Overall, the reviewed evidence supports phytoremediation as a sustainable strategy for Ni-contaminated soils. However, important knowledge gaps remain, particularly the scarcity of long-term field studies, methodological heterogeneity, limited understanding of plant–soil–microbiota interactions, underrepresentation of major Ni-producing regions, and insufficient evidence on technical and economic feasibility. Future research should address these gaps through standardized approaches and integrated field assessments under contrasting edaphoclimatic conditions to advance the effective and sustainable application of Ni phytoremediation. Full article

Halophytes are recognized for their adaptive capacity and potential applications in phytomanagement and ecosystem restoration. This study investigates the comparative physiology and antioxidant responses of two native halophytes, Caroxylon vermiculatum (L.) and Mesembryanthemum nodiflorum L., growing naturally in saline and metal-affected coastal environments. A comprehensive set of physiological and biochemical parameters was assessed, including macro- and microelements (Na, K, Ca, Fe, Zn, Cd), photosynthetic pigments (chlorophyll a, chlorophyll b, and carotenoids), soluble sugars, and proteins. In addition, oxidative stress markers (hydrogen peroxide, H₂O₂, and malondialdehyde, MDA), enzymatic antioxidants (superoxide dismutase, SOD, catalase, CAT, and guaiacol peroxidase, GPX), and non-enzymatic antioxidants (total phenolics, flavonoids, and proanthocyanidins) were evaluated. Antioxidant activities, including DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging and reducing power, were also measured. The results revealed clear species-specific adaptive strategies. Mesembryanthemum nodiflorum exhibited higher accumulation of Na and K, together with elevated levels of carotenoids and oxidative stress markers. This species showed translocation factors (TF > 1) for Na (~1.60) and K (~1.90), indicating efficient ion transport to aerial parts, while displaying low bioconcentration (BCF < 0.5 for most trace elements) and biological accumulation factors (BAF < 1), suggesting limited capacity for heavy metal accumulation. In contrast, Caroxylon vermiculatum showed higher concentrations of chlorophylls, carotenoids, phenolic compounds, flavonoids, and proteins, along with stronger superoxide dismutase activity. It also exhibited lower translocation of trace elements (TF < 1) and higher root retention of metals (BCF up to ~0.5), indicating a more effective exclusion and detoxification strategy. Overall, these findings demonstrate that M. nodiflorum relies on ion accumulation and translocation, whereas C. vermiculatum exhibits stronger ion regulation and antioxidant protection. Given the moderate BAF and BCF values observed, both species are more likely to contribute to phytomanagement through ion regulation and phytostabilization rather than efficient phytoextraction. Full article

Antimony (Sb) is an emerging environmental pollutant due to its toxicity, persistence, and extensive industrial applications. Despite the growing need for sustainable remediation strategies, research on the potential of phytoremediation for Sb-contaminated soils remains limited. This study investigates the suitability of Cynara cardunculus (cardoon), a high-biomass bioenergy crop, for the remediation of Sb-polluted soils and evaluates the effect of Fe(II) supplementation on plant performance and Sb behavior. Pot experiments were conducted using soils amended with 10–40 mg Sb kg⁻¹, under treatments with and without Fe(II). In the absence of iron, cardoon showed high tolerance to Sb exposure, with no significant growth inhibition even at 40 mg Sb kg⁻¹ after 30 days of cultivation. Iron addition significantly enhanced plant growth, resulting in a 2.3-fold increase in aboveground biomass compared with non-amended soils under the 20 mg Sb kg⁻¹ treatment after 45 days of cultivation. Sb accumulation was mainly restricted to the root system, indicating limited phytoextraction capacity. However, the species demonstrated strong phytostabilization potential, as the presence of plants reduced the water-soluble Sb fraction in soil by up to 50% compared with unplanted controls. These results suggest that C. cardunculus is a promising candidate for phytostabilization of Sb-contaminated soils. Its combined use with iron amendments may enhance biomass production and support integrated soil remediation and bioenergy production strategies. Full article

Elevated atmospheric carbon dioxide (ECO₂) is a key climatic factor influencing the resilience of plant–microbial symbiotic systems against heavy metal contamination. Robinia pseudoacacia–rhizobia symbiosis shows great potential for cadmium (Cd) remediation. However, the mechanism by which ECO₂ regulates Cd phytostabilization in symbiosis remains unclear. This study conducted a 90-day experiment in growth chambers to investigate the effects of ECO₂ on the growth, Cd accumulation and chemical forms, as well as nutrient uptake and antioxidant system in Robinia pseudoacacia–rhizobia symbiosis. Results indicated that ECO₂ significantly increased plant biomass and photosynthetic efficiency while significantly raising Cd content in roots (34.5%, p < 0.001) and decreasing it in shoots (31.4%, p < 0.001). This resulted in a significant reduction in Cd translocation factor (TF). Meanwhile, ECO₂ markedly increased Cd accumulation in roots (81.2%, p < 0.001) and reduced the bioavailability of Cd in the symbiosis. Moreover, ECO₂ promoted the content of nutrients and stimulated the antioxidant system. The random forest model indicated that root weight, Cd and Mn contents are the core factors for ECO₂-driven Cd phytostabilization. This study demonstrates that ECO₂ enhanced Cd phytostabilization by optimizing the resistance of symbiosis to Cd, offering a novel perspective for predicting plant–microbe joint restoration of heavy metal pollution under global climate change scenarios. Full article

Heavy metal deposition along high-traffic roadsides poses a persistent threat to agricultural safety, yet the partition barrier efficiency across rhizosphere–root–shoot interfaces in perennial nut crops remains poorly understood, representing a significant research gap. This study determined the concentrations of potentially toxic elements in the rhizosphere soils and distinct organs (leaves, pericarp, and edible seeds) of Siirt pistachio trees along a distance gradient (0, 50, and 100 m, plus a control site) in the Siirt and Tillo districts. To filter analytical baseline noise, all raw datasets were subjected to strict solid-matrix limit of detection (LOD) screening using a standardized dilution factor of 30 mL/g (DF = 15 mL final volume/0.5 g sample mass). Soil analysis revealed that the alkaline pH (6.90–7.27) and highly calcareous nature (21.97–65.75%) of the rhizosphere acted as a powerful edaphic barrier, immobilizing metals in the soil and limiting their translocation to aboveground tissues. Plant accumulation followed a leaf > pericarp > seed hierarchy, proving the canopy’s role as an effective vegetative filter. Crucially for food safety, highly toxic Cd (<1.74 µg/kg) and Bi remained entirely below detection limits in edible seeds. Cr peaked in leaves (730.42–795.00 µg/kg) but was highly restricted in seeds. Detected kernel concentrations of As, Co, Ni, Pb, and Sb were strictly below international toxic thresholds, while essential Cu physiologically concentrated in seeds and leaves. Consequently, the cumulative Hazard Index (HI) remained exceptionally below the 1.0 critical safety limit for both adults (<0.18) and children (<0.32). This confirms that roadside pistachios pose zero non-carcinogenic health hazards and are completely safe for human consumption. Full article

Uranium mining and processing have resulted in widespread environmental contamination by radionuclides and associated heavy metals, creating long-term ecological challenges because of their persistence, mobility, and bioavailability. The aim of this review is to evaluate knowledge on the uptake, accumulation, and biological effects of radionuclides and associated heavy metals in plants, identify the environmental factors governing their bioavailability, and assess recent advances in phytoremediation strategies for the sustainable restoration of uranium-contaminated ecosystems. A critical analysis of the published literature was conducted to evaluate contaminant sources, environmental factors regulating bioavailability, root and foliar uptake pathways, internal transport mechanisms, morphological, physiological, and biochemical biomarkers of plant stress, and phytoremediation approaches. The reviewed evidence demonstrates that plant responses occur at multiple levels of biological organization, including alterations in growth and anatomy, disturbances in photosynthesis and nutrient metabolism, and activation of antioxidant defense systems. Integrating these biomarkers provides a more comprehensive assessment of contaminant-induced stress than individual indicators alone. The literature further indicates that phytostabilization and phytoextraction, particularly when combined with soil amendments and beneficial rhizosphere microorganisms, represent promising approaches for reducing contaminant mobility and supporting ecosystem restoration. However, important knowledge gaps remain regarding native plant species and long-term field validation in uranium mining regions. This review provides a scientific basis for improving ecological monitoring, environmental risk assessment, and sustainable rehabilitation of uranium-contaminated ecosystems. Full article

The Murmansk Region (the Russian Arctic) faces severe environmental degradation due to heavy metal (HM) pollution from copper–nickel smelting, resulting in vast industrial barrens with elevated concentrations of copper (Cu) and nickel (Ni). Conventional phytostabilization methods are often ineffective or costly, necessitating alternative bioremediation strategies. This study evaluates the potential of microalgae and cyanobacteria for revegetating HM-contaminated substrates. Six strains of Nostoc-like morphotypes and three green microalgae were tested for Cu²⁺ tolerance (0.5–15 mg/L). While most strains exhibited growth inhibition at ≥3 mg/L Cu²⁺, Atlanticothrix sp. KPABG-154445, isolated from Tolbachik Volcano, showed positive growth at 2 mg/L Cu²⁺ under the tested conditions and recovering metabolic activity post-exposure. In sorption experiments, non-viable biomass achieved 68% Cu²⁺ removal at 2 mg/L, outperforming actively growing cultures. A microcosm experiment using copper-spiked nepheline slime (simulating mining waste) revealed Atlanticothrix sp. KPABG-154445’s ability to colonize nutrient-poor substrates, forming biocrusts covering 42% of the surface within one month, even under Cu²⁺ contamination (10 mg/kg). These findings highlight cyanobacteria, particularly strains such as KPABG-154445, as promising agents for the bioremediation of Arctic industrial barrens, leveraging their dual capacity for heavy metal tolerance and biocrust formation. Full article

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 salinization and contamination by potentially toxic elements (PTEs), hydrocarbons, and other pollutants represent interconnected environmental challenges, particularly in arid and coastal regions. Conventional remediation technologies are associated with elevated costs and environmental constraints, limiting their applicability in fragile saline environments. In this context, halophytic plants have emerged as promising biological tools for the phytoremediation of salt-affected and contaminated soils due to their adaptations to salinity stress. This review summarizes halophyte classification, salt-tolerance mechanisms, and their role in phytoremediation processes, including phytoextraction, phytostabilization, and phytodegradation. Particular attention is given to the interactions between salinity and contaminant mobility, highlighting the species-dependent effects of saline conditions on metal bioavailability and plant uptake. Evidence from both in situ and ex situ studies is discussed, emphasizing the advantages and limitations of halophyte-assisted remediation under saline conditions. Current evidence indicates that halophytes are generally more effective for phytostabilization and long-term risk mitigation than for rapid contaminant extraction. Overall, halophyte-based phytoremediation represents a sustainable strategy for the ecological rehabilitation of saline-degraded soils under increasing pressures associated with climate change and global soil salinization. Future advances integrating plant–microbe interactions, remote sensing technologies, and biomass valorization strategies may further enhance the implementation of halophyte-assisted remediation. 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

Reprocessing historical lead–zinc (Pb–Zn) slag offers a circular-economy pathway for secondary metal recovery, yet it can remobilize legacy contaminants where containment is inadequate, transferring risk to the surrounding land. Sustainable management of such sites requires frameworks that link contamination assessment to actionable remediation. We integrated ICP-OES geochemistry, native-plant biomonitoring, and US EPA RAGS-based risk modeling at an active Pb–Zn slag reprocessing site in Shymkent, Southern Kazakhstan. Twenty-four soil samples along four cardinal transects, two reference samples, and four composite plant samples (Centaurea pseudosquarrosa + Plantago lanceolata) were analyzed for ten metals by ICP-OES. UCC-referenced indices classified six metals as geoaccumulation Class 6 at most points (enrichment factors up to 90,871, confirming an exclusively anthropogenic origin). Peak concentrations reached 9350 mg·kg⁻¹ Pb, 290 mg·kg⁻¹ Cd, and 10,900 mg·kg⁻¹ As—exceeding Kazakhstan MPC by 72×, 290×, and 5450×. Worst-case carcinogenic risk reached 4.3 × 10⁻³ (43× above the US EPA threshold), driven almost entirely by arsenic (93%); ecosystem risk (RCR_total = 223) was dominated by cadmium (43%), arsenic (27%), and mercury (16%)—a disconnect between mass-based and toxicity-based prioritization. On this basis we propose a three-tier remediation framework (engineered containment, phytostabilization, monitored attenuation) that couples resource recovery with contamination control, is transferable to analogous Pb–Zn legacy sites, and supports sustainable land use, urban resilience, and responsible secondary-resource use. Full article

African soils face increasing levels of metal pollution due to industrialization, artisanal mining activities, improper waste management, and enhanced agricultural productivity. However, unlike many organic pollutants, heavy metals do not degrade naturally and therefore persist in environmental systems for prolonged periods. Heavy metals accumulate over many decades in the soil and bioaccumulate through the food chain causing severe health complications such as cancer, kidney problems, and neurological impairment. This paper reviews the current literature on the origin, prevalence, and behavior of the main pollutants Pb, Cd, Cr, As, Hg, and Cu. The major phytoremediation methods including phytoextraction, rhizofiltration, phytostabilization, and phytovolatilization are highlighted alongside in planta screening methods for hyperaccumulating plants including Berkheya coddii (Ni) and Haumaniastrum robertii (Co). The paper evaluates various enhancement techniques such as the use of chelators, Rhizobium inoculations, and genetic modifications. The significance of these approaches in tropical and subtropical climates is discussed. The paper suggests a holistic framework involving empirical kinetic modeling, geospatial machine learning (random forest, kriging), and molecular omics in prediction modeling. Major hurdles in such predictions include lack of field-based verification of the models, biotechnology safety of genetically modified (GM) organisms, and inadequate regulations. Future perspectives emphasize community-driven phytomining, biomass recycling, and resilient phytoremediation solutions. Full article

Sunflower (Helianthus annuus) can potentially be used for uranium (U) phytoremediation. However, the influence of arbuscular mycorrhizal fungi (AMF) on key rhizosphere processes and plant U uptake remains insufficiently researched. We hypothesized that AMF inoculation could enhance sunflower tolerance to U stress by improving plant physiological performance and modifying rhizosphere properties. To test this hypothesis, this study examined the effects of AMF (Funneliformis mosseae, Glomus etunicatum, and their co-inoculation) on sunflowers under U stress, encompassing plant growth and physiological traits, rhizosphere properties, enzyme activities in the rhizosphere soil, uranium speciation in the rhizosphere soil, and the accumulation and distribution of uranium within the plant. Results showed that AMF successfully colonized the roots, enhancing plant growth, biomass, and gas exchange, while improving photosynthetic efficiency and reducing non-photochemical quenching. In the rhizosphere, AMF elevated soil respiration, organic matter, dissolved organic carbon, and microbial biomass carbon; improved phosphatases, urease, catalase, and sucrase activities; also reshaped U speciation, increasing exchangeable and carbonate-bound fractions while decreasing those bound to organic matter, Fe/Mn oxides, and residual phases. Moreover, AMF reduced U concentration in leaves and stems, promoted U retention in belowground tissues, and significantly lowered the U translocation factor. These findings demonstrate that AMF inoculation improves sunflower tolerance to U stress by enhancing physiological performance, modifying rhizosphere properties, and immobilizing U in roots, supporting its potential use in phytoremediation strategies for U-contaminated environments. Full article

Mine tailings are highly disturbed technogenic materials whose low mechanical stability may limit mine closure and long-term land rehabilitation. This study evaluates the geomechanical potential of Chrysopogon zizanioides (L.) Roberty, commonly known as vetiver grass, to improve the shear-strength response of filtered mine tailings under controlled laboratory and numerical modelling conditions. The study does not constitute field-scale validation of phytostabilization; rather, it examines the contribution of vetiver roots to apparent cohesion and shallow slope stability. A combined experimental–numerical framework was implemented, including laboratory characterization of unreinforced and root-reinforced tailings, derivation of Mohr–Coulomb shear-strength parameters, and limit-equilibrium slope-stability analysis under predefined root-growth and root-orientation scenarios. The results indicate that vetiver roots increased apparent cohesion by up to 34.6%, whereas changes in friction angle remained below 10%, suggesting that the dominant reinforcement mechanism is pseudo-cohesive rather than frictional. The calculated factors of safety varied according to slope geometry, assumed root length, root orientation, and simplified water-condition scenarios. However, the findings remain limited to controlled experimental and numerical conditions. Field-scale validation, long-term root monitoring, moisture variability, nutrient availability, phytotoxicity, contaminant immobilization, and life-cycle performance should be assessed before practical implementation. This study provides preliminary geomechanical evidence of vetiver-induced root reinforcement in filtered mine tailings. Full article

Metal-contaminated dredged sediments represent heterogeneous environmental matrices in which remediation responses are frequently constrained by elevated background metal loads and complex geochemical conditions. Within such systems, phytoremediation has been discussed as a nature-based management approach whose outcomes depend on plant biomass, internal metal allocation, and context-dependent interactions between plants and sediment. The present study evaluated whether bacterial and fungal plant growth-promoting microorganisms (PGPMs) were associated with changes in plant metal uptake and internal allocation in Sorghum bicolor L. and Cannabis sativa L. grown in dredged sediment collected from the Bega Canal. An outdoor pot experiment was conducted under environmentally relevant conditions, including bacterial and fungal inoculation treatments alongside non-inoculated controls, with plant responses to Cr, Ni, Cu, Zn, As, Cd, and Pb characterized using concentration- and mass-based uptake metrics, root–shoot partitioning, and sediment geochemical assessment based on pseudo-total concentrations and BCR sequential extraction fractions. Across treatments, plant responses were largely governed by intrinsic species traits and biomass production, while PGPM-associated effects remained modest and variable. Root-dominated metal retention and limited translocation were evident irrespective of species, consistent with a phytostabilization-type response rather than systematic extraction. Absolute metal uptake accounted for only a minor fraction of total sediment metal pools, underscoring the importance of interpreting concentration-based indices jointly with mass-based metrics when evaluating system-scale responses. Altogether, the findings indicate that under the investigated outdoor dredged sediment pot conditions, PGPM inoculation acts primarily as a context-specific modulator of plant responses rather than a driver of enhanced phytoremediation performance, reflecting the central role of intrinsic plant traits and stabilization-oriented processes in complex sediment systems. Full article