Hyperaccumulator Plant Species Research Articles

Vitality behind desolation: Characteristics and succession process of plant communities in the Chongqing special steel plant brownfield

Phytoremediation is a sustainable way to clean contaminated urban soil, but selecting the right plants and designing communities is crucial. This study focuses on the vegetation in a disused steel plant in Chongqing, China, abandoned for nearly two decades. The goal is to reveal the plant community and succession patterns to inform the restoration of brownfield sites. This study combined the sample line and plot to investigate the vegetation and its growth environment in the Steel Plant. Information was recorded, including plant species, quantity, distribution, soil nutrients, humidity, and light. Cluster analysis categorized plant community types, and redundancy analysis examined the link between environmental conditions and plant types. The study found that: 1) There are 65 plant species (including 13 native trees) in the steel plant’s brownfield area, with Broussonetia papyrifera, Pteris vittata, and Debregeasia orientalis being the most abundant. The plants inside the plant were divided into seven groups based on species composition. 2) Soil moisture showed a significant positive correlation (Pearson index of 0.628) with plant survival, followed by a notable correlation with light intensity. 3) Environmental conditions partly influenced plant species composition and abundance variations. 4) 11 hyper-accumulating plant species were identified, focusing on three: the As hyper-accumulator Pteris vittata and the Cd hyper-accumulators Solanum nigrum and Debregeasia orientalis. The findings of this research will offer valuable insights for applying phytoremediation techniques in addressing contamination issues in brownfields within steel plants.

Enhanced Phytoremediation of Heavy Metals By Soil-applied Organic And Inorganic Amendments: Heavy Metal Phytoavailability, Accumulation, And Metal Recovery

ABSTRACT Phytoremediation, an eco-friendly and cost-effective technique for remediating heavy metal-contaminated soils, can be significantly enhanced through the application of soil amendments. This study investigates the impact of Foliar spraying of both organic (fulvic acid, auxin, Compost, and coconut coir) and inorganic (sulfur) amendments on the phytoavailability, accumulation, and recovery of heavy metals: Arsenic-As, Mercury-Hg, Cadmium-Cd and Lead-Pb in contaminated soils. Field experiment was conducted using hyperaccumulator plant species; T. capensis and H. psittacorum with varying amendment treatments to assess their effectiveness in improving phytoremediation outcomes. The results demonstrate that specific amendments significantly increase heavy metal uptake and translocation within plants by altering soil pH, cation exchange capacity, and microbial activity, thus enhancing metal solubility and bioavailability. Furthermore, the study evaluates the potential of these amendments to not only facilitate metal recovery but also to restore soil health and fertility. The findings underscore the potential of tailored amendment strategies in optimizing phytoremediation processes, offering a sustainable solution for heavy metal remediation in polluted environments.

Phytoremediation potential and vegetation assessment of plant species growing on multi-metals contaminated coal mining site

This study aims to evaluate the plant species potential to accumulate, concentrate and translocate the heavy metals around the coal mining contaminated site with heavy metals at Harnoi, Abbottabad. The phytosociological surveys involve the systematic study of plant communities within the particular area to show their composition, structure and distribution showed that the contaminated coal mining-associated area was poor in vegetation. Among these, 11 plant species with higher important values (IV) are collected with associated soil and analyzed for the total concentrations of Cadmium (Cd), Copper (Cu), Chromium (Cr), Lead (Pb) and Nickel (Ni) using Atomic Spectrophotometer. The phytoremediation indices (BAF, BCF, TF and TI) were used to evaluate the multi-metals hyperaccumulator and stabilizer plant species. Dodonaea viscosa was evaluated as multi-metals (Cd, Cu and Ni) stabilizer. While the Ajuga bracteosa and Sonchus espera, Sisybrium officinale and Platango ovata stabilize Cd and Cr respectively. The other plant species that can stabilize as single heavy metal are Ajuga bracteosa and Sonchus espera (Cd), Sisybrium officinale and Platango ovata (Cr) and Amaranthus spinosus (Ni) respectively. While the multi-metals accumulator plant species are Bidens pilosa (Cu, Pb and Ni), Chenopodium ambrosioides (Cd, Cu and Ni), Amaranthus spinosus (Cd, Cu and Cr), Ajuga bracteosa (Pb and Ni) and Rumex hastatus (Cd and Ni). However, the single heavy metal accumulator plant species are Sonchus espera (Pb), Conyzea Canadensis (Ni), Platango ovata and Malvastrum coromandelianum (Cu) respectively. These plants could find valuable applications in practical phytoremediation for the remediation near mining tailings at Abbottabad. Moreover, the use of local plants is a promising approach not only for in situ accumulation and stabilization of heavy metals but also for tolerance and environmental adaptations in the contaminated area.

Folic acid supplementation improves seed germination, seedling growth and cadmium uptake in a mining ecotype of Solanum nigrum L.

Cadmium (Cd) contamination poses a significant threat to global agricultural production and hyperaccumulating plant species, such as Solanum nigrum (L.), face challenges in phytoremediation due to limited biomass production. Application of plant growth regulators such as, folic acid (FA) is a promising strategy to increase biomass production in these plant species. Therefore, a study was conducted to assess the interaction between FA and Cd in the mining ecotype of S. nigrum. The study involved two phases: germination and growth. In the first phase, seeds were exposed to different concentrations of CdCl2 (i.e. 0, 10, 25, 50, 100, 200, and 400 µM) in the presence (0, 25, 50 and 100 µM) or absence of FA for ten days. Results showed that FA enhanced seed germination under Cd stress and acted as an antioxidant and stimulated germination and emergence at moderate concentrations. At higher concentrations, it reduced germination percentage. The study also found significant variations (P <0.05) in growth attributes and Cd uptake in all FA concentrations. Cd was generally higher in shoots than roots, with the highest Cd concentration found in T6 (200 µmol Cd + 50 µmol/L FA) with a 170-fold difference (mean value: 1690 mg/kg) from control (10 mg/kg). Furthermore, an increase in exposure time led to a 2-fold increase in reduced glutathione (GSH) level in leaves at T3 (100 µmol/L Cd + 50 µmol/L FA).Therefore, we concluded that FA is a biostimulant that activates protective mechanism, alleviates oxidative stress and improves Cd uptake and accumulation in hyper-accumulating species.

“Mining” the herbarium for hyperaccumulators: Discoveries of nickel and zinc (hyper)accumulation in the genus Noccaea (Brassicaceae) through X‐ray fluorescence herbarium scanning

AbstractX‐ray fluorescence spectroscopy (XRF) is a relatively new method for non‐destructive elemental analysis of herbarium material that meets the scientific interest in being capable of discovering new hyperaccumulator plant species. Since the genus Noccaea (Brassicaceae family) is known to be one of the most numerous in term of the hyperaccumulator plant species it contains, especially those that hyperaccumulate Ni, the herbarium material available worldwide represents a great resource for expanding our knowledge of their elemental profiles. In this first systematic XRF scanning of herbarium specimens of the genus Noccaea, a total of 794 specimens from the collection of the National Museum of Natural History in Paris (MNHN) were analyzed, and the raw values obtained were corrected using regression formulas against inductively coupled plasma atomic emission spectroscopy data. Hyperaccumulation of Ni was detected in 90 specimens covering 21 taxa, with Ni concentrations reaching up to 48,700 mg kg−1 in Noccaea cappadocica, an ultramaficophyte from Syria. Zinc concentrations above the hyperaccumulation threshold were found in 210 specimens covering 23 taxa, most of which belonged to different subspecies of Noccaea caerulescens, with the highest concentration reaching up to 56,200 mg kg−1 in N. caerulescens subsp. caerulescens. Although the accumulation of Ni and Zn is contrasting in most of the specimens studied, in 10 specimens, predominantly belonging to N. caerulescens, simultaneous hyperaccumulation of Ni and Zn was found. This study also revealed previously unknown hyperaccumulation of Ni in several Noccaea taxa, as well as a simultaneous hyperaccumulation of Ni and Zn that needs to be confirmed by further experimental and field studies.

Soil Phytomining: Recent Developments—A Review

Phytomining (PM) is defined as the process of using plants capable of bio-extracting metals from soil in order to explore them economically. This relatively new, innovative method has been gathering significant attention in both the academic and commercial domains. Conventional mining methods are often economically unviable when applied to lean ores, and they can lead to secondary pollution in soil—a situation that applies to all excavated metals. On the other hand, PM is an environmentally friendly and economically viable solution that addresses the growing demands for metal resources, while simultaneously contributing to energy production by harnessing biomass energy. This comprehensive review presents the current PM techniques, challenges, and the hyperaccumulator plant species that may be used for the extraction of the main targeted elements in the process. Typically, the targeted metals are those of economic value, which can later be deposited or sold to various industries. This review also analyzes the factors influencing the economic viability of PM and proposes potential enhancements. Undeniably, PM offers the opportunity for economically sustainable exploration of metal-rich soils, but its full commercial viability remains constrained under current conditions as scientists are actively searching for the identification and utilization of new hyperaccumulator plant species in different locations worldwide, while creating new relationships and business avenues within the mining industry. Overall, this review highlights the current status of PM technology and the plants used, emphasizing the need for further research to enhance its commercial implementation and its potential to assist the mining industry. We conclude that PM, although a relatively new and unexplored concept, may provide economic and environmental benefits to soil end-users and managers who must cultivate on metal-contaminated soils as PM may turn yield shortages (of specific commercial crops) to benefits if high-yield hyperaccumulators are cultivated for industrial valorization of their high metal-content biomass.

Effects of metal amendment and metalloid supplementation on foliar defences are plant accession-specific in the hyperaccumulator Arabidopsis halleri.

Soil pollution by metals and metalloids as a consequence of anthropogenic industrialisation exerts a seriously damaging impact on ecosystems. However, certain plant species, termed hyperaccumulators, are able to accumulate extraordinarily high concentrations of these metal(loid)s in their aboveground tissues. Such hyperaccumulation of metal(loid)s is known to act as a defence against various antagonists, such as herbivores and pathogens. We investigated the influences of metal(loid)s on potential defence traits, such as foliar elemental, organic and mechanical defences, in the hyperaccumulator plant species Arabidopsis halleri (Brassicaceae) by artificially amending the soil with common metallic pollutants, namely cadmium (Cd) and zinc (Zn). Additionally, unamended and metal-amended soils were supplemented with the metalloid silicon (Si) to study whether Si could alleviate metal excess. Individuals originating from one non-/low- and two moderately to highly metal-contaminated sites with different metal concentrations (hereafter called accessions) were grown for eight weeks in a full-factorial design under standardised conditions. There were significant interactive effects of metal amendment and Si supplementation on foliar concentrations of certain elements (Zn, Si, aluminium (Al), iron (Fe), potassium (K) and sulfur (S), but these were accession-specific. Profiles of glucosinolates, characteristic organic defences of Brassicaceae, were distinct among accessions, and the composition was affected by soil metal amendment. Moreover, plants grown on metal-amended soil contained lower concentrations of total glucosinolates in one of the accessions, which suggests a potential trade-off between inorganic defence acquisition and biosynthesis of organic defence. The density of foliar trichomes, as a proxy for the first layer of mechanical defence, was also influenced by metal amendment and/or Si supplementation in an accession-dependent manner. Our study highlights the importance of examining the effects of co-occurring metal(loid)s in soil on various foliar defence traits in different accessions of a hyperaccumulating species.

Endophyte Community Changes in the Seeds of Eight Plant Species following Inoculation with a Multi-Endophytic Bacterial Consortium and an Individual Sphingomonas wittichii Strain Obtained from Noccaea caerulescens.

Noccaea caerulescens, a hyperaccumulator plant species known for its metal tolerance and accumulation abilities, harbours a microbiome of interest within its seed. These seed-associated bacteria, often referred to as seed endophytes, play a unique role in seed germination and plant growth and health. This work aimed to address how inoculating seeds of eight different plant species-Medicago sativa (alfalfa), Zea mays (corn), Raphanus sativus (radish), Helianthus annus (sunflower), Cucurbita pepo subsp. pepo (squash), Beta vulgaris subsp. cicla (rainbow chard), Arabidopsis thaliana (thale cress), and Noccaea caerulescens (penny cress)-with a bacterial consortium made from the seed endophytes of N. caerulescens would affect the seed microbiome of each test plant species, as well as inoculation with a strain of the bacterium Sphingomonas wittichii, which was previously isolated from seeds of N. caerulescens. Additionally, we aimed to offer preliminary plant tests in order to determine the best seed treatment plan for future research. The results showed that inoculation with the bacterial consortium held the most potential for increasing plant size (p < 0.001) and increasing germination rate (p < 0.05). The plant that responded best to inoculation was N. caerulescens (penny cress), likely because the microbes being introduced into the seed were not foreign. This paper also offers the first insight into the seed endophytes of Beta vulgaris subsp. cicla, highlighting an abundance of Proteobacteria, Firmicutes, and Actinobacteriota.

Effects of resource availability on the growth, Cd accumulation, and photosynthetic efficiency of three hyperaccumulator plant species

Plants that hyperaccumulate heavy metals such as cadmium (Cd) are important agents of phytoremediation. Availability of resources such as light, nutrients, and water can affect heavy metal accumulation by plants, but the responses of hyperaccumulators to different levels of resource availability remain little studied. To test such responses, three Cd hyperaccumulators, Solanum nigrum, Bidens pilosa, and Taraxacum mongolicum, were grown in Cd-contaminated soil; subjected to three levels of light, nutrient, or water availability; and measured for growth, Cd accumulation, and photosynthetic efficiency. All three species accumulated more total biomass and grew taller if given high than low water or light (each P < 0.001). Species accumulated four to eight times more Cd (190−309 versus 24−68 μg Cd g−1 mass) under high than low light. High water availability increased Cd accumulation by 89% in B. pilosa but decreased it by 31% and 40% in S. nigrum and B. pilosa, respectively. Effects of nutrients on both growth and accumulation varied between species; Cd accumulation by S. nigrum and T. mongolicum was respectively 14% and 54% lower at high than low nutrients, while it was 130% higher in B. pilosa. Light but not water or nutrient availability affected effective and maximum quantum yields and electron transport rate. Findings from this study suggest that low levels of light may constrain phytoremediation of Cd in soil and that testing species of Cd hyperaccumulators individually for responses to levels of water and nutrients will inform selection of species for phytoremediation.

Bacteria associated with Zn-hyperaccumulators Arabidopsis halleri and Arabidopsis arenosa from Zn–Pb–Cd waste heaps in Poland as promising tools for bioremediation

To identify metal adapted bacteria equipped with traits positively influencing the growth of two hyperaccumulator plant species Arabidopsis arenosa and Arabidopsis halleri, we isolated bacteria inhabiting rhizosphere and vegetative tissues (roots, basal and stem leaves) of plants growing on two old Zn–Pb–Cd waste heaps in Bolesław and Bukowno (S. Poland), and characterized their potential plant growth promoting (PGP) traits as well as determined metal concentrations in rhizosphere and plant tissues. To determine taxonomic position of 144 bacterial isolates, 16S rDNA Sanger sequencing was used. A metabolic characterization of isolated strains was performed in vitro using PGP tests. A. arenosa and A. halleri accumulate high amounts of Zn in their tissues, especially in stem leaves. Among in total 22 identified bacterial taxa, the highest level of the taxonomical diversity (H’ = 2.01) was revealed in A. halleri basal leaf endophytes originating from Bukowno waste heap area. The 96, 98, 99, and 98% of investigated strains showed tolerant to Cd, Zn, Pb and Cu, respectively. Generally, higher percentages of bacteria could synthesize auxins, siderophores, and acetoin as well as could solubilize phosphate. Nine of waste heap origin bacterial strains were tolerant to toxic metals, showed in vitro PGP traits and are potential candidates for bioremediation.

Reflectance spectroscopy as a promising tool for ‘sensing’ metals in hyperaccumulator plants

Main conclusionThe VNIR reflectance spectra of nickel hyperaccumulator plant leaves have spectral variations due to high nickel concentrations and this property could potentially be used for discovery of these plants. Hyperaccumulator plants accumulate high concentrations of certain metals, including manganese, cobalt, or nickel. Of these metals, the divalent ions of nickel have three absorption bands in the visible to near-infrared region which may cause variations in the spectral reflectance of nickel hyperaccumulator plant leaves, but this has not been investigated previously. In this shortproof-of-concept study, the spectral reflectance of eight different nickel hyperaccumulator plant species leaves were subjected to visible and near-infrared and shortwave infrared (VNIR-SWIR) reflectance spectrum measurements in dehydrated state, and for one species, it was also assessed in hydrated state. Nickel concentrations in the plant leaves were determined with other methods and then correlated to the spectral reflectance data. Spectral variations centred at 1000 ± 150 nm were observed and had R-values varying from 0.46 to 0.96 with nickel concentrations. The extremely high nickel concentrations in nickel hyperaccumulator leaves reshape their spectral reflectance features, and the electronic transition of nickel-ions directly contributes to absorption at ~ 1000 nm. Given that spectral variations are correlated with nickel concentrations it make VNIR-SWIR reflectance spectrometry a potential promising technique for discovery of hyperaccumulator plants, not only in the laboratory or herbarium, but also in the field using drone-based platforms. This is a preliminary study which we hope will instigate further detailed research on this topic to validate the findings and to explore possible applications.

Foraging for selenium: a comparison between hyperaccumulator and non-accumulator plant species

Selenium (Se) hyperaccumulators are a unique group of plants that can accumulate this element in their aerial parts at concentrations exceeding 100 mg kgDW−1. These plants actively search for Se in the soil, a phenomenon known as root foraging, reported to date only by few studies. In this study, the effect of localized Se enrichment, in the form of selenite and selenate, was investigated on the root architecture of two Se-hyperaccumulators (Stanleya pinnata and Astragalus bisulcatus) and two non-accumulators (Brassica juncea and Medicago sativa). Rhizoboxes were divided into two halves: one half was filled with control soil while the other with selenate or selenite (30 mg kgDW−1) spiked soil. Seedling were transferred into the interface of the two soils and allowed to grow for three weeks under controlled light and temperature conditions. Staneya pinnata exhibited equal root density in both halves of the rhizobox when grown in control/control and selenite/control soil treatments. However, in the presence of selenate, S. pinnata developed 76% of the roots towards the selenate-enriched half, indicating an active root foraging. In contrast, A. bisulcatus and the non-accumulators B. juncea and M. sativa did not show any preferential distribution of roots. This study revealed that only S. pinnata showed the ability to detect and forage for Se when provided as selenate. Non-accumulators did not show any morphological or Se-accumulation difference associated with the presence of Se in soil in either form.

Phytoremediation: A Sustainable Approach to Combat Heavy Metal Contaminated Soil - A Review

A significant threat to the environment is the contamination of soil with hazardous metals. Chemical methods to remove heavy metals from the environment, such as heat treatment, electroremediation, soil replacement, precipitation, and chemical leaching, are typically very expensive and inapplicable to land for farming. However, other methods are being employed to clean up polluted environmental systems. One of these is phytoremediation, which relies on the use of hyper-accumulator plant species that can withstand significant concentrations of hazardous HMs in the soil. In this technique, harmful metals are removed, degraded, or detoxified using green plants. The efficacy of plants as candidates for HMs decontamination can be improved by applying phytoremediation assisted with chemical inducers or chelating agents, plant growth-promoting bacteria, and AMF inoculation. The present review discusses the toxicity of HMs and the environmentally friendly methods used to clean them up, with a particular emphasis on phytoremediation. Moreover, some advanced and sustainable modern technologies for enhancing phytoremediation potential of plants are also discussed.

Zinc Supply Affects Cadmium Uptake and Translocation in the Hyperaccumulator Sedum Plumbizincicola as Evidenced by Isotope Fractionation.

This study employs stable isotope analysis to investigate the mechanisms of cadmium (Cd) and zinc (Zn) interaction in the metal hyperaccumulating plant species Sedum plumbizincicola. To this end, the Cd and Zn isotope compositions of root, stem, leaf, and xylem sap samples were determined during metal uptake and translocation at different Cd and Zn concentrations. The enrichment of light isotopes of both elements in plants during uptake was less pronounced at low metal supply levels, likely reflecting the switch from a low-affinity to a high-affinity transport system at lower levels of external metal supply. The lower δ114/110Cd values of xylem sap when treated with a metabolic inhibitor decreasing the active Cd uptake further supports the preference of heavier Cd isotopes during high-affinity transport. The Δ66Znplant-initialsolution or Δ66Znplant-finalsolution values were similar at different Cd concentrations, indicating negligible interaction of Cd in the Zn uptake process. However, decreasing Zn supply levels significantly increased the enrichment of light Cd isotopes in plants (Δ114/110Cd = -0.08‰) in low-Cd treatments but reduced the enrichment of light Cd isotopes in plants (Δ114/110Cd = 0.08‰) under high Cd conditions. A systematic enrichment of heavy Cd and light Zn isotopes was found in root-to-shoot translocation of the metals. The Cd concentrations of the growth solutions thereby had no significant impact on Zn isotope fractionation during root-to-shoot translocation. However, the Δ114/110Cdtranslocation values hint at possible competition between Cd and Zn for transporters during root-to-shoot transfer and this may impact the transport pathway of Cd. The stable isotope data demonstrate that the interactions between the two metals influenced the uptake and transport mechanisms of Cd in S. plumbizincicola but had little effect on those of Zn.

The Chemistry and Toxicity of Chromium Pollution: An Overview

As a heavy metal, chromium (Cr) has significant importance in the current industrial scenario, however, it poses an environmental threat as well. Generally, there are two stable forms of Cr available in environmental matrices, the relatively less toxic trivalent Cr(III) and the highly toxic hexavalent Cr(VI). Industrial sites release hazardous Cr(VI) with effluents during the post-production stage, causing water and soil pollution worldwide. Cr(VI) is one of the priority pollutants as per USEPA (United States Environmental Protection Agency) classification and it is one of the well-known carcinogens. In most cases, it is released from anthropogenic activities like mining, steel making, welding, tanning, textile dyeing, wood polishing, etc. Whenever Cr(VI) contamination exceeds the threshold limits, it has a deleterious impact on public health and the vegetation of the site contaminated. In the present investigation, the major focus is on the anthropogenic sources of Cr(VI) release into water bodies and soil, its adverse effects, as well as remediation of these emerging environmental problems. The present review focuses on the removal of Cr from environmental media by conventional biological methods. Many advanced technologies have been developed and applied recently to remove Cr from contaminated soils and water, including membrane technology, electrocoagulation, ion exchange, and electrodialysis. In addition, alternative techniques like phytoremediation processes were established which offer an environmentally sustainable, eco-friendly, and cost-effective approach to removing Cr. With an emphasis on the cleanup of soils and water systems contaminated by Cr, this review summarizes the bioavailability of Cr, the uptake pathways, the accumulation process, and the current status of phytoremediation research. A recent finding about Cr localization in hyperaccumulator plant species is also described in this paper. This review describes the process of plant metabolism changes in response to Cr stress and the mechanisms that allow plants to remove Cr through the phytoremediation process.

Positive Effect of High Zinc on Growth of Sedum alfredii

Sedum alfredii Hance (S. alfredii) is a native hyperaccumulator plant species in China that has strong tolerance and accumulation ability for Zn and Cd. In addition, it is a good material for the phytoextraction of soil heavy metal pollutants. However, the specific effect of high Zn concentrations on the growth of S. alfredii and its metabolic mechanisms are not clear. Using an untargeted metabolomics method, we analysed the differential metabolites of the two ecotypes in S. alfredii roots under different Zn treatments. The results showed that high Zn levels significantly promoted plant growth in the hyperaccumulating ecotype (HE), while growth was inhibited in the non-hyperaccumulating ecotype (NHE). We detected 624 metabolites in the roots of S. alfredii. Under the high Zn treatment, lots of lipids and lipid-like molecules, such as glyceryl monooleate and 9,12,13-trihydroxyoctadecane-10-enoic acid, along with organic acids, such as lauramidopropylbetaine, L-malic acid, and their derivatives, decreased significantly in HE roots. Differential metabolites, such as some lipids and lipid-like molecules, were significantly upregulated in NHE roots. The above results indicate that the exogenous high Zn treatment induces the downregulation of HE differential metabolites in response to Zn, but significantly induces the upregulation of differential metabolites in NHE.

The seed germination properties of two hyperaccumulator plant species with the potential for Ni agromining

The aim of this study is to investigate the effect of different nickel concentrations and light in combination with storage conditions and storage time on the seed germination ability of two serpentine-endemic nickel hyperaccumulating species (Bornmuellera emarginata and B. tymphaea). The seeds of both species were collected from natural populations in the Pindus Mountain range, Greece in early July and stored in a refrigerator (4?C) and in laboratory conditions (22?C). The seeds were exposed to a range of nickel concentrations typical of non-ultramafic-ultramafic gradient in two light environments (12 h photoperiod and continuous darkness). The nickel concentration only had a significant effect on B. emarginata, decreasing its seed germination rate with increasing Ni concentrations. The storage temperature significantly affected the germination percentage of both species and it was higher at 4?C compared to 22?C. A higher germination rate (&gt; 60%) was observed for 5-8-month-old seeds, but both species generally showed significantly higher germination rates in the tests conducted seven months after seed ripening in the field. A higher germination rate was observed in a 12-hour photoperiod than in continuous darkness only for B. tymphaea. This study provides guidelines on the germination capacity of two obligate nickel hyperaccumulators with a potential for use in agromining systems.

Phytoaccumulation of zinc from contaminated soil using ornamental plants species Helianthus annuus L. and Tagetes erecta L.

Intensive research on hyperaccumulator plant species provides an alternative method to cleanup heavy metal contaminated sites using these plants. Helianthus annuus and Tagetes erecta are suitable hyperaccumulator plant species for removing zinc (Zn) from contaminated soil because of their high phytoremediation effectiveness. The present study focused on to evaluate comparative efficacy of Zn accumulation using H. annuus and T. erecta. Plantlets were exposed to different Zn concentrations (10, 50, 100, 300, and 500 mg kg−1) for 20, 40, and 60 days while changes in morphological, biochemical, and enzyme activity markers were evaluated. The concentration of Zn in various plant parts was determined using an atomic absorption spectrophotometer (AAS). After 60 days H. annuus showed greatest accumulation of Zn in the root and shoot (216.7 and 109.5 mg kg−1), whereas the Zn accumulation T. erecta (209.5 and 97.84 mg kg−1) was found comparatively less in the root and shoot. The result showed increased polyphenol and proline concentrations with increasing Zn concentrations which were maximal in H. annuus 6.642 mg g−1 and 25.474 µmol g−1, respectively. At 60 days, APX (4.145 mM mg−1), CAT (2.558 mM mg−1), and GR (52.23 mM mg−1) antioxidant enzymatic activities were observed with higher concentrations. Analysis of ultrastructure confirmed Zn transport and localization in root and shoot tissues examined through FESEM-EDX, Fluorescence microscopy, and optical microscopy. The present research findings concluded with the high amount of removal of Zn from contaminated soil using H. annuus and T. erecta for ecofriendly approach to soil cleanup followed by sustainable agriculture.

Protein Analysis of A. halleri and N. caerulescens Hyperaccumulators When Exposed to Nano and Ionic Forms of Cd and Zn

Hyperaccumulator plant species growing on metal-rich soils can accumulate high quantity of metals and metalloids in aerial tissues, and several proteomic studies on the molecular mechanisms at the basis of metals resistance and hyperaccumulation have been published. Hyperaccumulator are also at the basis of the phytoremediation strategy to remove metals more efficiently from polluted soils or water. Arabidopsis halleri and Noccea caerulescens are both hyperaccumulators of metals and nano-metals. In this study, the change in some proteins in A. halleri and N. caerulescens was assessed after the growth in soil with cadmium and zinc, provided as sulphate salts (CdSO4 and ZnSO4) or sulfide quantum dots (CdS QDs and ZnS QDs). The protein extracts obtained from plants after 30 days of growth were analyzed by 2D-gel electrophoresis (2D SDS-PAGE) and identified by MALDI-TOF/TOF mass spectrometry. A bioinformatics analysis was carried out on quantitative protein differences between control and treated plants. In total, 43 proteins resulted in being significatively modulated in A. halleri, while 61 resulted in being modulated in N. caerulescens. Although these two plants are hyperaccumulator of both metals and nano-metals, at protein levels the mechanisms involved do not proceed in the same way, but at the end bring a similar physiological result.

Nickel Hyperaccumulator Biochar Sorbs Ni(II) from Water and Wastewater to Create an Enhanced Bio-ore.

Nickel (Ni) hyperaccumulators make up the largest proportion of hyperaccumulator plant species; however, very few biochar studies with hyperaccumulator feedstock have examined them. This research addresses two major hypotheses: (1) Biochar synthesized from the Ni hyperaccumulator Odontarrhena chalcidica grown on natural, metal-rich soil is an effective Ni sorbent due to the plant's ability to bioaccumulate soluble and exchangeable cations; and (2) such biochar can sorb high concentrations of Ni from complex solutions. We found that O. chalcidica grew on sandy, nutrient-poor soil from a Minnesota mining district but did not hyperaccumulate Ni. Biochar prepared from O. chalcidica biomass at a pyrolysis temperature of 900 °C sorbed up to 154 mg g-1 of Ni from solution, which is competitive with the highest-performing Ni sorbents in recent literature and the highest of any unmodified, plant-based biochar material reported in the literature. Precipitation, cation exchange, and adsorption mechanisms contributed to removal. Ni was effectively removed from acidic solutions with initial pH > 2 within 30 min. O. chalcidica biochar also removed Ni(II) from a simulated Ni electroplating rinsewater solution. Together, these results provide evidence for O. chalcidica biochar as an attractive material for simultaneously treating high-Ni wastewater and forming an enhanced Ni bio-ore.