Search Results (38)

Understanding heavy metal behavior in arid saline soils is critical for phytoremediation in degraded lands. This study investigated metal distribution and plant enrichment in the Tarim Basin using 323 soil and 55 plant samples (Populus euphratica, Tamarix ramosissima, cotton, jujube). Analyses included redundancy analysis (RDA) and bioconcentration factor (BCF) assessments. Key findings reveal that elevated salinity (total salts, TS > 200 g/kg) and alkalinity (pH > 8.5) immobilized As, Cd, Cu, and Zn. Precipitation and competitive leaching reduced metal mobility by 42–68%. Plant enrichment strategies diverged significantly: P. euphratica hyperaccumulated Cd (BCF = 1.59) and Zn (BCF = 2.41), while T. ramosissima accumulated As and Pb (BCF > 0.05). Conversely, cotton posed Hg transfer risks (BCF = 2.15), and jujube approached Cd safety thresholds in phosphorus-rich soils. RDA indicated that pH and total salinity (TS) jointly suppressed metal bioavailability, explaining 57.6% of variance. Total phosphorus (TP) and soil organic carbon (SOC) enhanced metal availability (36.8% variance), with notable TP-Cd synergy (Pearson’s r = 0.42). We propose a dual-threshold management framework: (1) leveraging salinity–alkalinity suppression (TS > 200 g/kg + pH > 8.5) for natural immobilization; and (2) implementing TP control (TP > 0.8 g/kg) to mitigate crop Cd risks. P. euphratica demonstrates targeted phytoremediation potential for degraded saline agricultural systems. This framework guides practical management by spatially delineating zones for natural immobilization versus targeted remediation (e.g., P. euphratica planting in Cd/Zn hotspots) and implementing phosphorus control in high-risk croplands. Full article

Land degradation from trace metal pollution in North Africa severely compromises soil fertility. This study investigates the synergistic remediation potential of Eucalyptus biochar (EuB) and Casuarina glauca in iron mine soil contaminated with Fe, Zn, Mn, Pb, Cd, and As. Seedlings were grown for six months in: non-mining soil (NMS), contaminated soil (CS), and CS amended with 5% EuB (CS + EuB). Comprehensive ecophysiological assessments evaluated growth, water relations, gas exchange, chlorophyll fluorescence, oxidative stress, and metal accumulation. EuB significantly enhanced C. glauca tolerance to multi-trace metal stress. Compared to CS, CS + EuB increased total dry biomass by 14% and net photosynthetic rate by 22%, while improving predawn water potential (from −1.8 to −1.3 MPa) and water-use efficiency (18%). Oxidative damage was mitigated. EuB reduced soluble Fe by 71% but increased Zn, Mn, Pb, and Cd mobility. C. glauca exhibited hyperaccumulation of Fe, Zn, As, Pb, and Cd across treatments, with pronounced Fe accumulation under CS + EuB. EuB enhanced nodule development and amplified trace metals sequestration within nodules (Zn: +1.4×, Mn: +2.4×, Pb: +1.5×, Cd: +2.0×). The EuB-C. glauca synergy enhances stress resilience, optimizes rhizosphere trace metals bioavailability, and leverages nodule-mediated accumulation, establishing a sustainable platform for restoring contaminated lands. Full article

In China, soil contamination by heavy metals is a widespread issue, with substantial increases in lead(Pb), cadmium(Cd), copper(Cu), and zinc(Zn) levels observed across various regions. Particularly, the concentrations of Pb and Cd significantly exceed their natural background levels. P-ATPases, a group of proteins, utilize energy from ATP hydrolysis to support the transmembrane movement of metal ions. This group encompasses several Heavy Metal Associated Transporter (HMA) ATPases. Studies on hyperaccumulators have shown the critical role of HMAs in the movement and reduction in Zn and Cd toxicity in plant systems. This research identifies a protein encoded by the SpHMA gene from Sedum plumbizincicola, a species noted for aiding Zn/Cd hyperaccumulators, which enhances tolerance to Cd and Zn. We detail a protein encoded by SpH/A within the HMA family that enhances Cd tolerance. Real-time fluorescence quantification (RT-PCR) indicates that SpHMA3 expression in Arabidopsis thaliana and Zea mays KN5585 correlates with high Cd tolerance, linked to Cd accumulation in Zea mays. In addition, homozygous Arabidopsis thaliana AtHMA3 mutants exhibited increased Cd sensitivity compared to the wild type (WT). Notably, plants of Arabidopsis thaliana and maize overexpressing SpHMA3 showed enhanced Cd stress tolerance compared to WT. Enhanced Cd accumulation in tissues was observed when SpHMA3 was overexpressed, as revealed by subcellular distribution analysis. We propose that SpHMA3 augments maize tolerance to Cd and Zn stresses through enhanced cellular uptake and translocation of Cd ions. This investigation clarifies the gene function of SpHMA3 in Cd and Zn stress response, offering insights for enhancing heavy metal absorption traits in maize varieties and phytoremediation methods for soils contaminated with heavy metals. Full article

Phytoremediation has been reported as a more energy-efficient, and therefore cost-effective, method of environmental restoration compared to traditional remediation methods for heavy-metal-contaminated soils. Biochar has been shown to have variable effects on remediation potential in heavy-metal-contaminated soils. The objective of this study was to evaluate the effects of soil contamination level (i.e., low, medium, and high), industrial hemp (Cannabis sativa L.) cultivar (i.e., ‘Carmagnola’ and ‘Jinma’), biochar rate (i.e., 0, 2, 5, and 10% by volume), and their interactions on root tissue Cd, Pb, and Zn concentrations and uptakes; whole-plant Cd, Pb, and Zn uptakes; and translocation factors after 90 days of hemp growth in contaminated soil from the Tar Creek Superfund Site near Picher, Oklahoma. Hemp removal of Cd, Pb, and Zn differed between soil contamination levels (p < 0.01), but was unaffected (p > 0.05) by the hemp cultivar or biochar rate, except for total Zn uptake. Total Zn uptake was affected (p = 0.02) by the biochar rate in the medium- and high-contaminated soils, where total plant Zn uptake in the high-contaminated soil was numerically the largest with 10% biochar (0.28 mg cm⁻²) and in the medium-contaminated soil was numerically the largest with 2% biochar (0.07 mg cm⁻²), but was unaffected (p > 0.05) by the biochar rate in the low-contaminated soil. The translocation factor for Zn uptake in the low and medium soils was >1, indicating industrial hemp as a potential Zn hyper-accumulator up to a threshold soil contamination level. Results demonstrate that biochar amendment has the potential to enhance hemp’s remediation capability of heavy-metal-contaminated soils. Full article

Tragus racemosus often grows in close proximity to motorways. The aim of this work was to determine whether the seeds of the species can grow under salt (NaCl) stress, how the plants are able to accumulate heavy metals and what plant architecture prerequisites they have for spreading. It was found that the structure of the plant consists of a single rosette of the first order, from which shoots of the first order develop, on which rosettes of the second order grow, and this is repeated modularly. Higher-order rosettes can produce their own root systems. Research on this species revealed its small salt and heavy metal tolerances during germination and early development. The concentration of metals in the above-ground parts of plants was of the following rank: Fe >> Zn > Ni ≥ Pb > Cu; for soil, it was Fe >> Pb > Cu > Ni. The plant germinates successfully and grows in environments containing NaCl up to 0.50% (including solutions of 0.12% and 0.25%). However, higher salt contents of 0.99% and 1.96% proved lethal for seed germination. This tolerance to salt explains why T. racemosus commonly grows along motorways where winter road maintenance involves the application of salt. These adaptations give the species a competitive advantage in these human-modified environments. Furthermore, T. racemosus turned out to be a possible Ni hyperaccumulator. Full article

This work aims to assess the bioavailability and bioaccumulation of Cr, Cu, Pb, and Zn in the soil–plant system (Erigeron canadensis L.) in the zone of anthropogenic impact in Dnipro city, a significant industrial and economic centre of Ukraine. Sampling was carried out at three locations at distances of 1.0 km, 5.5 km, and 12.02 km from the main emission sources associated with battery production and processing plants in Dnipro. The concentrations of heavy metals such as Cr, Cu, Pb, and Zn were analysed using atomic emission spectrometry from soil and parts of Erigeron canadensis L. The highest concentrations of elements in the soil, both for the mobile form and the total form, were determined to be 48.96 mg kg⁻¹ and 7830.0 mg kg⁻¹, respectively, for Pb in experimental plot 1. The general ranking of accumulation of elements in all experimental plots, both for the plant as a whole and for its parts, was as follows: Zn > Cu > Cr > Pb. Zn for plants was the most available heavy metal among all studied sites and had the highest metal content in the plant (339.58 mg kg⁻¹), plant uptake index (PUI-506.84), bioabsorption coefficient (BAC-314.9), and bioconcentration coefficient (BCF-191.94). According to the results of the study, it is possible to evaluate Erigeron canadensis L. as a hyperaccumulator of Zn, Cu, and Cr and recommend it for phytoextraction of soils contaminated with Zn, Cu, and Cr and phytostabilization of soils contaminated with Pb. Full article

The increasing demand for mineral resources has generated mine tailings with heavy metals (HM) that negatively impact human and ecosystem health. Therefore, it is necessary to implement strategies that promote the immobilization or elimination of HM, like phytoremediation. However, the toxic effect of metals may affect plant establishment, growth, and fitness, reducing phytoremediation efficiency. Therefore, adding organic amendments to mine tailings, such as biochar, can favor the establishment of plants, reducing the bioavailability of HM and its subsequent incorporation into the food chain. Here, we evaluated HM bioaccumulation, biomass, morphological characters, chlorophyll content, and genotoxic damage in the herbaceous Crotalaria pumila to assess its potential for phytostabilization of HM in mine tailings. The study was carried out for 100 days on plants developed under greenhouse conditions under two treatments (tailing substrate and 75% tailing/25% coconut fiber biochar substrate); every 25 days, 12 plants were selected per treatment. C. pumila registered the following bioaccumulation patterns: Pb > Zn > Cu > Cd in root and in leaf tissues. Furthermore, the results showed that individuals that grew on mine tailing substrate bioaccumulated many times more metals (Zn: 2.1, Cu: 1.8, Cd: 5.0, Pb: 3.0) and showed higher genetic damage levels (1.5 times higher) compared to individuals grown on mine tailing substrate with biochar. In contrast, individuals grown on mine tailing substrate with biochar documented higher chlorophyll a and b content (1.1 times more, for both), as well as higher biomass (1.5 times more). Therefore, adding coconut fiber biochar to mine tailing has a positive effect on the establishment and development of C. pumila individuals with the potential to phytoextract and phytostabilize HM from polluted soils. Our results suggest that the binomial hyperaccumulator plant in combination with this particular biochar is an excellent system to phytostabilize soils contaminated with HM. Full article

Mining activities produce waste materials and effluents with very high metal concentrations that can negatively impact ecosystems and human health. Consequently, data on soil and plant metal levels are crucial for evaluating pollution severity and formulating soil reclamation strategies, such as phytoremediation. Our research focused on soils and vegetation of a highly contaminated site with potentially toxic metals (Pb, Zn, and Cu) in the Touissit mining districts of eastern Morocco. Vegetation inventory was carried out in three mine tailings of the Touissit mine fields using the “field tower” technique. Here, 91 species belonging to 23 families were inventoried: the most represented families were Poaceae and Asteraceae, and the biological spectrum indicated a predominance of Therophytes (55.12%). From the studied areas, 15 species were selected and collected in triplicate on the tailings and sampled with their corresponding rhizospheric soils, and analyzed for Pb, Zn, and Cu concentrations. Reseda lutea, lotus marocanus, and lotus corniculatus can be considered as hyperaccumulators of Pb, as these plants accumulated more than 1000 mg·kg⁻¹ in their aerial parts. According to TF, these plant species could serve as effective plants for Pb phytoextraction. Full article

Wastewater generation is a major concern, as most of it goes untreated. Industries, urban areas, and agriculture are the major contributors to wastewater. Phytoremediation is an effective method of wastewater treatment. However, the potential of local aquatic species for hyper-accumulation of heavy metals remains elusive. This study focuses on evaluating the native macrophyte Eichhornia crassipes for phytoremediation potential in different source-based water environments: freshwater (FW), industrial (IW), and urban wastewater (UW). Physico-chemical analysis was conducted on water samples (five samples from each source) along with the corresponding E. crassipes plants for assessing physiological, nutritional, and heavy metal parameters. The results showed distinct characteristics among the water sources. The FW had a high pH, and the IW exhibited elevated levels of electrical conductivity (EC: 1746 μS cm⁻¹), total dissolved solids (TDS: 864 mg L⁻¹), chloride (Cl⁻: 557.83 mg L⁻¹), sulfate (SO₄⁻: 137.27 mg L⁻¹), and calcium (Ca⁺⁺: 77.83 mg L⁻¹) ions. The UW exhibited high bicarbonate (HCO₃⁻: 123.38 mg L⁻¹), sodium (Na⁺: 154 mg L⁻¹), and potassium (K⁺: 37.12 mg L⁻¹) ions. The Cd contamination exceeded World Health Organization (WHO) limits (0.003 mg L⁻¹) in the FW (0.05 mg L⁻¹ in FW-5) and UW (0.05 mg L⁻¹ in UW-3); Cr contamination was higher than the permissible limits of the WHO, National Environmental Quality Standards (NEQS), and the European Union (EU) (0.05 mg L⁻¹) in FW, IW, and UW; arsenic (As) in IW exceeded the WHO, United States Environmental Protection Agency (USEPA), and EU limits of 10 μg L⁻¹, and Pb in UW exceeded the WHO (0.01 mg L⁻¹), NEQS (0.05 mg L⁻¹), and EU (0.01 mg L⁻¹) limits. E. crassipes displayed different traits depending on the water sources. FW-grown plants had a higher biomass and chlorophyll-b content, while UW-grown plants had higher photosynthesis rates and chlorophyll-a content. Shoots accumulated more Na⁺, K⁺, and Ca⁺⁺ ions than roots. Metal translocation from roots to shoots followed specific patterns for each source: the TFs of Zn = 3.62 in FW > Cd = 2.34 in UW > Cr = 1.61 and Pb = 1.29 in IW and BCFs were found in ascending order: Zn > Ni > Cd > As > Pb in FW, Cd > Zn > Ni > Cr > Pb > As in IW, and Cd > Ni > Pb > Cr > Zn > As in UW. The bioconcentration factor was higher in the roots than in the shoots. These findings suggest that E. crassipes shows promise as a phytoremediation option for heavy metal-contaminated wastewater due to its ability to thrive in harsh wastewater conditions with a higher TF > 1 and BCF > 1. Therefore, the utilization of these macrophytes holds potential for wastewater treatment. Full article

Tea (Camellia sinensis) is the second most consumed beverage worldwide, playing a key role in the human diet. Tea is considered a healthy drink, as its consumption has been linked to a lower risk of cardiovascular disease-related events and death, stroke, metabolic syndrome and obesity. However, several studies have shown that C. sinensis is a hyperaccumulator of Al and other elements that are considered potentially toxic. In the present study, the contents of 15 elements (both essential and toxic) were determined for the first time in tea leaves collected in tea gardens located in six different European countries and processed to provide black and green tea. The results showed that Al was the major toxic element detected, followed by Ni, Cr, Pb, As, Cd, Ag, and Hg. Essential elements were detected in the order of Mn, Fe, Zn, Cu, Co, and Se. Statistically significant correlations (p < 0.05) were found in the distribution of some elements, highlighting mechanisms of synergic or antagonist interaction. Multivariate analysis revealed that geographical origin was the main driver in clustering the samples, while the different treatment processes (black or green) did not significantly affect the contents of elements in the leaves. The estimation of potential non-carcinogenic risk revealed no risk for the consumption of European teas for consumers in terms of potentially toxic elements. Full article

Trace metal pollution in farmland threatens the health of both crops and humans. Restoring these polluted farmlands safely and utilizing them to elevate farmers‘ incomes are extremely needed. Phytoremediation is a promising method for metal extracting but its popularization is limited by both its low efficiency and the low economic value of the plants used. Herein, a field study was conducted to investigate the potential of using a rotation with the hyperaccumulator of Sedum plumbizincicola and kenaf (Hibiscus cannabinus) for combined heavy-metal-contaminated farmland remediation. Results showed that the kenaf obtained an aerial biomass of up to 21 Mg ha⁻¹ under combined heavy metal contaminations, which was significantly higher than that for S. plumbizincicola (<8 Mg ha⁻¹). However, the concentrations of Cd, Cu, Pb, and Zn in S. plumbizincicola were at least 100, 2, 8, and 75 fold higher than that for kenaf, respectively. The removal of Cd, Pb, and Zn for S. plumbizincicola can be more than 3800, 720, and 104,347 g ha⁻¹, which was at least 38, 3, and 27 times higher than that for kenaf, respectively. Finally, the removal of Cd, Cu, Pb, and Zn by rotation of the two crops was increased by 7.88%, 126%, 33.5%, and 4.39%, respectively, compared with the S. plumbizincicola monoculture. Hence, the rotation with kenaf and S. plumbizincicola can not only remove more heavy metals from the contaminated soil and accelerate the phytoremediation pace, but also can supply a large number of raw materials for industrial applications. Full article

Heavy metals like cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn), resulting from anthropogenic activities, are elements with high persistence in nature, being able to accumulate in soils, water, and plants with significant impact to human and animal health. This study investigates the phytoremediation capacity of Silphium perfoliatum L. as a specific heavy metal hyperaccumulator and the effects of Cu, Zn, Cd, and Pb on some physiological and biochemical indices by growing plants under floating hydroponic systems in nutrient solutions under the presence of heavy metals. One-year-old plants of S. perfoliatum grown for 20 days in Hoagland solution with the addition of (ppm) Cu-400, Zn-1200, Cd-20, Pb-400, and Cu+Zn+Cd+Pb (400/1200/20/400) were investigated with respect to the control. The level of phytoremediation, manifested by the ability of heavy metal absorption and accumulation, was assessed. In addition, the impact of stress on the proline content, photosynthetic pigments, and enzymatic activity, as being key components of metabolism, was determined. The obtained results revealed a good absorption and selective accumulation capacity of S. perfoliatum plants for the studied heavy metals. Therefore, Cu and Zn mainly accumulate in the stems, Cd in the roots and stems, while Pb mainly accumulates in the roots. The proline tended to increase under stress conditions, depending on the pollutant and its concentration, with higher values in leaves and stems under the associated stress of the four metals and individually for Pb and Cd. In addition, the enzymatic activity recorded different values depending on the plant organ, its type, and the metal concentration on its substrate. The obtained results indicate a strong correlation between the metal type, concentration, and the mechanisms of absorption/accumulation of S. perfoliatum species, as well as the specific reactions of metabolic response. Full article

Heavy metal pollution is a worldwide environmental and human health problem. Prosopis laevigata is a hyperaccumulator legume that bioaccumulates Pb, Cu and Zn. With interest in designing phytoremediation strategies for sites contaminated with heavy metals, we isolated and characterized endophytic fungi from the roots of P. laevigata growing on mine tailings located in Morelos, Mexico. Ten endophytic isolates were selected by morphological discrimination and a preliminary minimum inhibitory concentration was determined for zinc, lead and copper. A novel strain of Aspergillus closest to Aspergillus luchuensis was determined to be a metallophile and presented a marked tolerance to high concentrations of Cu, Zn and Pb, so it was further investigated for removal of metals and promotion of plant growth under greenhouse conditions. The control substrate with fungi promoted larger size characters in P. laevigata individuals in comparison with the other treatments, demonstrating that A. luchuensis strain C7 is a growth-promoting agent for P. laevigata individuals. The fungus favors the translocation of metals from roots to leaves in P. laevigata, promoting an increased Cu translocation. This new A. luchuensis strain showed endophytic character and plant growth-promotion activity, high metal tolerance, and an ability to increase copper translocation. We propose it as a novel, effective and sustainable bioremediation strategy for copper-polluted soils. Full article

Endophytes within plants are known to be crucial for plant fitness, and while their presence and functions in many compartments have been studied in depth, the research on seed endophytes is still limited. This work aimed to characterize the seed endophytic and rhizospheric bacterial community of two Noccaea caerulescens Pb-Zn hyperaccumulator populations, growing on two heavy-metal-polluted sites in Belgium. Cultured representatives were evaluated for their potential to enhance seed germination and root length of the model species Arabidopsis thaliana. The results indicated that the community structure within the seed is conserved between the two locations, comprising mainly of Proteobacteria (seeds), and Actinobacteria in the bulk soil. Root length of A. thaliana was significantly increased when inoculated with Sphingomonas vulcanisoli. The results of this paper offer insights into the importance of the selection of the core seed endophytic microbiome and highlight the precarious symbiotic relationship they have with the plant and seed. Full article

The aim of the present study was to evaluate tolerance to salinity and different heavy metals as well as the phytoextraction potential of Ranunculus sceleratus plants from a brackish coastal sandy beach habitat. Four separate experiments were performed with R. sceleratus plants in controlled conditions: (1) the effect of NaCl gradient on growth and ion accumulation, (2) the effect of different Na⁺ and K⁺ salts on growth and ion accumulation, (3) heavy metal tolerance and metal accumulation potential, (4) the effect of different forms of Pb salts (nitrate and acetate) on plant growth and Pb accumulation. A negative effect of NaCl on plant biomass was evident at 0.5 g L⁻¹ Na⁺ and growth was inhibited by 44% at 10 g L⁻¹ Na⁺, and this was associated with changes in biomass allocation. The maximum Na⁺ accumulation (90.8 g kg⁻¹) was found in the stems of plants treated with 10 g kg⁻¹ Na⁺. The type of anion determined the salinity tolerance of R. sceleratus plants, as Na⁺ and K⁺ salts with an identical anion component had a comparable effect on plant growth: nitrates strongly stimulated plant growth, and chloride treatment resulted in slight but significant growth reduction, but plants treated with nitrites and carbonates died within 4 and 5 weeks after the full treatment, respectively. The shoot growth of R. sceleratus plants was relatively insensitive to treatment with Mn, Cd and Zn in the form of sulphate salts, but Pb nitrate increased it. Hyperaccumulation threshold concentration values in the leaves of R. sceleratus were reached for Cd, Pb and Zn. R. sceleratus can be characterized as a shoot accumulator of heavy metals and a hyperaccumulator of Na⁺. A relatively short life cycle together with a high biomass accumulation rate makes R. sceleratus useful for dynamic constructed wetland systems aiming for the purification of concentrated wastewaters. Full article