Hyperaccumulator Plants Research Articles

Determination of Heavy Metal Remediation to Soil from Community Buildings’ Rooftop

Considering the importance of water in the world, the amount of usable water is not sufficient throughout the world, the existing available fresh water resources are not enough, therefore, water shortages may be encountered in the following years. Keeping the quality of water as it is demanded gains more importance than before. Particularly, heavy metals begin to interfere with groundwater resources, and the quantity of pollution growing due to industrialization, and urbanization. In the present study, the quantitative analysis of heavy metals in harvested rainwater from the rooftop of public buildings in Bornova, Izmir is investigated. The results show that a minimum of 5 μg of copper, 4 μg of zinc, 2.69 μg of lead, 0.095 μg of cadmium, 0.55 μg of chromium, 89,7 μg of iron, 0.96 μg of arsenic, 0.0119 μg of mercury and 3.88 μg of nickel should be tossed away for obtaining a liter of potable water. In conclusion, first flush diverters are recommended to convert these non-point pollutants to point source. Thus, municipalities can take necessary measures to protect the environment such as using phytoremediation and hyperaccumulator plants in sewages.

Facile Synthesis of Magnetic Iron-Based Nanoparticles from the Leach Solution of Hyperaccumulator Plant Pinus brutia for the Antibacterial Activity and Colorimetric Detection of Ascorbic Acid.

It has been well known that metallic nanoparticles with striking properties possess wide application prospects in the processes of colorimetric detection, catalysis, disease diagnosis and treatment, energy, wastewater treatment, remediation, and antibacterial activity in recent years. Herein, iron-based nanoparticles (FeNPs), metallic nanoparticles, were synthesized via a facile chemical reduction method using a hyperaccumulator plant. Also, their use in antibacterial activity applications and colorimetric ascorbic acid (AA) detection was investigated. It was observed that FeNPs presented high antibacterial potency against Gram-positive bacteria of Listeria monocytogenes and Staphylococcus aureus and also Gram-negative bacteria of Escherichia coli(O157: H7), E. coli(ATCC 25922), Salmonella enteritidis, and Salmonella typhimurium. Moreover, it was found that FeNPs exhibited superior peroxidase-like activity to catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to produce a blue color product, oxidized TMB (oxTMB), in the presence of H2O2. The colorimetric AA detection could be carried out by making the solution color lighter owing to the antioxidant property of AA. The quantitative detection of AA could be performed simply, selectively, and sensitively with FeNPs with a detection limit (LOD) of 0.5462 μM in a linear range of 30-200 μM.

Agronomic Evaluation of Recycled Polyurethane Foam-Based Growing Media for Green Roofs

Green roofs are very popular and their individual surface area is constantly growing. Considering that the organo-mineral materials used in planting growing media (GM) are often non-renewable resources, the search for alternative materials from waste recycling is a challenge. Among these, recycled polyurethane (PU) foams are light and porous. The objective of this study was to evaluate the potential agronomic valorisation of PU foams for extensive green roofs. Three GM based on compost, PU foam and topsoil were developed and tested in situ for 18 months along with four plant species in containers containing 15 cm of GM. The agronomic properties of the GM and their contaminant contents were evaluated, as well as the plant aerial and root biomasses and trace element levels. The main results of this work are that GM are suitable for plant growth. Compost ratio effect resulted in a lower pH and higher exchangeable cations in GM1, whereas topsoil proportion effect mainly decreased macroporosity and increased nutrient contents. Furthermore, due to the high trace element load in the compost, hyperaccumulator plants such as Hypericum calycinum and Stipa tenuissima should be preferred. Ecotoxicological analyses will be carried out to validate the absence of risk of PU foam contaminants being released in the environment before proposing these types of GM to green roof developers.

A Review of Research on the Use of Selected Grass Species in Removal of Heavy Metals

Soil and air pollution are main problems posing a serious threat to human health. Traditional physical and chemical soil remediation methods affect the soil ecosystem and are rather costly. Since the main purpose of soil remediation is not only to remove pollutants but also to restore soil health, the method of phytoremediation is becoming extremely relevant. Phytoremediation is an environmentally friendly and natural process of removing pollutants from the environment. Cleaning up contaminated sites and enabling re-use without harming future users requires the implementation of environmentally friendly and economically attractive technologies. Phytoremediation does not adversely affect the structure and biological life of the soil. Concerning on-site cleaning in situ. Hyperaccumulator plants can accumulate heavy metals from the soil, which is the so-called phytoextraction. The ability of trees and shrubs to effectively remove solid particles from the air has also been proven. However, it is not always possible to grow large plants in polluted areas. Therefore, the main goal of the research was to explore previous studies on the phytoremediation capability of herbaceous plants, in particular, their phytoextraction capacity. Another major issue was to study the main methods of improving plant phytoextraction. The results obtained show that grass can be a good solution for natural ecosystem cleanup. It is also necessary to pay attention to the impact of phytoextraction-improving substances on soil health.

Identifying candidates for the phytoremediation of copper in viticultural soils: A systematic review

For many years, copper-based fungicides have been used in viticulture and have contributed to increasing concentrations in soils. Today, it is not uncommon to find vineyard soils with total copper topsoil concentrations above 100 mg kg−1, which may have consequences for both the environment and human health. Phytoremediation, the use of plants to remove heavy metals from soils, is a promising and environmentally-friendly method to extract copper from soils. The objectives of this study were to review and synthesise the current knowledge on copper phytoremediation in vineyard soils and identify future applications. A systematic literature search in Web of Science was conducted on 19 July 2022 and resulted in twenty-seven papers meeting the inclusion criteria. Approximately one third of the papers were from Brazil and most of the experiments had been carried out in pots. In some studies, the addition of bacteria or chelators was also evaluated. Some species, such as Plantago lanceolata L. or Ricinus communis L., can accumulate copper in their tissues at concentrations above 1000 mg kg−1. Addition of bacteria and chelators to the soil can also increase the copper uptake capacity by plants. However, most of the species evaluated accumulate copper in the roots, rather than in the shoots, thus limiting the implementation of this method in practice. Further studies are thus needed to find other hyperaccumulator plants. Future research should focus primarily on the ability of plants to accumulate copper in their aerial parts, their ability to transfer copper from roots to shoots, and their biomass production under high soil copper concentrations. Longer-term experiments and more in situ testing are also needed to evaluate the potential for development and use of copper phytoremediation in vineyards. To conclude, species of the Poaceae and Lamiaceae families are the most promising so far for phytoremediation. Identifying plants able to translocate copper from the roots to the aerial parts will be an important factor in the success of this method.

Insight into the synergistic effect and products distribution during co-pyrolysis of phytoremediation residue and municipal sewage sludge through experiment and reaction force field simulation

We co-pyrolyzed municipal sewage sludge (MS) and Sedum Alfredii L. (SA, a heavy metal hyperaccumulator plant) for the first time to solve their disposal issue. Experimental and simulation results show that synergistic effects exist during the co-pyrolysis process. The thermal decomposition mechanism, kinetics, and product distribution of MS and SA at different mixing ratios (1:0, 3:1, 1:1, 1:3, 0:1) were investigated by thermogravimetric analysis and co-pyrolysis experiments. According to thermogravimetric results, the decomposition of all feedstocks can be divided into three stages. FWO method and Master plot method were used to calculate the activation energy and determine the reaction mechanism. When the addition ratio of SA was 75 %, the difference between theoretical and practical activation energies was greatest, indicating that the best synergy could be achieved at this mixing ratio. Co-pyrolysis experiment shows that more bio-oil and gas were produced. The synergistic effect between MS and different fractions of SA was studied using Reaction Force Field simulation, revealing that the free radicals generated by MS and SA advance the MS decomposition time while increasing the decomposition degree of SA. In addition, we built an artificial neural network with a 3 × 21 × 1 structure to predict the degradation process of various mixtures, which exhibits a high agreement with the experimental results. This study can provide a new idea for the disposal of SA and MS, i.e., co-pyrolysis, by solving their disposal issue while obtaining valuable products.

The role of metal transporters in phytoremediation: A closer look at Arabidopsis

Pollution of the environment by heavy metals (HMs) has recently become a global issue, affecting the health of all living organisms. Continuous human activities (industrialization and urbanization) are the major causes of HM release into the environment. Over the years, two methods (physical and chemical) have been widely used to reduce HMs in polluted environment. However, these two methods are inefficient and very expensive to reduce the HMs released into the atmosphere. Alternatively, researchers are trying to remove the HMs by employing hyper-accumulator plants. This method, referred to phytoremediation, is highly efficient, cost-effective, and eco-friendly. Phytoremediation can be divided into five types: phytostabilization, phytodegradation, rhizofiltration, phytoextraction, and phytovolatilization, all of which contribute to HMs removal from the polluted environment. Brassicaceae family members (particularly Arabidopsis thaliana) can accumulate more HMs from the contaminated environment than those of other plants. This comprehensive review focuses on how HMs pollute the environment and discusses the phytoremediation measures required to reduce the impact of HMs on the environment. We discuss the role of metal transporters in phytoremediation with a focus on Arabidopsis. Then draw insights into the role of genome editing tools in enhancing phytoremediation efficiency. This review is expected to initiate further research to improve phytoremediation by biotechnological approaches to conserve the environment from pollution.

Microbial functional communities and the antibiotic resistome profile in a high-selenium ecosystem

Enshi City, in the Hubei Province of China, is known as the world capital of selenium with the most abundant selenium resource. An important selenium hyperaccumulator plant, Cardamine violifolia, was found to naturally grow in this high-selenium ecosystem. However, relatively little is known about the impact of the selenium levels on microbial community and functional shifts in C. violifolia rhizosphere. Here, we tested the hypothesis that underground microbial diversity and function vary along a selenium gradient, including antibiotic resistance genes (ARGs). Comprehensive metagenomic analyses, such as taxonomic investigation, functional detection, and ARG annotation, showed that selenium, mercury, cadmium, lead, arsenic, and available phosphorus and potassium were correlated with microbial diversity and function. Thaumarchaeota was exclusively dominant in the highest selenium concentration of mine outcrop, and Rhodanobacter and Nitrospira were predominant in the high-selenium ecosystem. The plant C. violifolia enriched a high concentration of selenium in the rhizosphere compared to those in the bulk soil, and it recruited Variovorax and Polaromonas in its rhizosphere. Microbial abundance showed a trend of increasing first and then decreasing from low to high selenium concentrations. Annotation of ARGs showed that the multidrug resistance genes adeF, mtrA, and poxtA, the aminoglycoside resistance gene rpsL, and the sulfonamide resistant gene sul2 were enriched in the high-selenium system. It was discovered that putative antibiotic resistant bacteria displayed obvious differences in the farmland and the soils with various selenium concentrations, indicating that a high-selenium ecosystem harbors the specific microbes with a higher capacity to enrich or resist selenium, toxic metals, or antibiotics. Taken together, these results reveal the effects of selenium concentration and the selenium hyperaccumulator plant C. violifolia on shaping the microbial functional community and ARGs. Metalloid selenium-inducible antibiotic resistance is worth paying attention to in future.

SaMT3 in Sedum alfredii drives Cd detoxification by chelation and ROS-scavenging via Cys residues

Metallothioneins (MTs), a group of cysteine-rich proteins, are effective chelators of cadmium (Cd) and play a key role in plant Cd detoxification. However, little is known about the role of single cysteine (Cys) residues in the MTs involved in the adaptation of plants to Cd stress, especially, in hyperaccumulators. In the present study, we functionally characterised SaMT3 in S. alfredii, a Cd/Zn hyperaccumulator native to China. Our results showed that the C- and N- terminal regions of SaMT3 had differential functional natures in S. alfredii and determined its Cd hypertolerance and detoxification. Two CXC motifs within the C-terminal region were revealed to play a crucial role in Cd sensing and binding, whereas the four Cys-residues within the N-terminal region were involved in scavenging reactive oxygen species (ROS). An S. alfredii transgenic system based on callus transformation was developed to further investigate the in-planta gene function. The SaMT3-overexpressing transgenic plant roots were more tolerant to Cd than those of wild-type plants. Knockout of SaMT3 resulted in significantly decreased Cd concentrations and increased ROS levels after exposure to Cd stress. We demonstrated the SaMT3-mediated adaptation strategy in S. alfredii, which uses metal chelation and ROS scavenging in response to Cd stress. Our results further reveal the molecular mechanisms underlying Cd detoxification in hyperaccumulating plants, as well as the relation between Cys-related motifs and the metal binding properties of MTs. This research provides valuable insights into the functions of SaMT3 in S. alfredii, and improves our understanding of Cd hyperaccumulation in plants.

Accumulation of elements in vegetation spontaneously developing on self-heating waste dumps in the Upper Silesia area (Poland)

Accumulation of 34 trace and major elements was analysed in 9 plant species ( Tussilago farfara , Arctium tomentosum , Solidago canadensis , Populus L., Eupatorium cannabinum , Verbascum sp., Solanum nigrum , Rumex crispus L., Betula pendula ) and one fungus ( Schizophyllum commune ) collected from coal, PbZn-smelting, and mixed-type waste heaps in Upper Silesia (Poland). The most persistent and extreme enrichment was found in the burnt bark of Betula pendula from Bytom. Enrichment factors in relation to the geometric mean of elevated (PE) and hyperaccumulator (PH) plant contents show extreme values for elements toxic to vegetation, such as Zn (EF PE up to 13, EF PH up to 17), Pb (EF PH up to 4, EF PE up to 161), Tl (EF PE up to 8), Cd (EF max of 327), Hg (EF PH up to 3), and Ag (maximum EF PE of 14). Elevated are also V (EF PN up to 13), Sc (EF PN up to 14), Ni (EF PN up to 17), Se (EF PN up to 16), Fe (EF PN up to 48), Co (EF PN up to 23), Sb (EF PN up to 31), and Bi (EF PN up to 34). Although the levels of the elements studied were usually below potentially toxic levels, they were often above the normal ones. Furthermore, significant differences in the contents between different plant tissues were observed, as reflected in the translocation factor (TF). Verbascum sp. and S. nigrum accumulate such elements mostly in their above-ground tissues, and may thus be considered useful in phytoextraction of Zn, Pb and other elements. Sl. canadensis and E. cannabinum mostly display the opposite strategy, with element immobilization in their roots. Extreme Zn contents in E. cannabinum , peaking in its roots, suggest it to be a potential Zn phytostabilizer.

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.

Human health risk mitigation from arsenic in rice by crop rotation with a hyperaccumulator plant.

Exposure to arsenic (As) from a diet of contaminated rice is a widespread problem and a serious concern in several parts of the world. There is a need to develop sustainable, effective, and reliable strategies to reduce As accumulation in rice. Our goal was to develop and test a simple crop rotation method of alternating rice with the As hyperaccumulator plant, Chinese brake fern (Pteris vitatta L.), to reduce As concentrations in rice grains. A greenhouse column study was performed for 2years using As-contaminated rice paddy soil from West Bengal. Rice was grown under flooded conditions and irrigated with As-contaminated water to simulate field conditions. Chinese brake fern was grown between two rice cycles in experimental columns, while control columns were left unplanted. Our results show that at the end of two cycles, there was a statistically significantdecrease in soil As concentrations in the treatment columns compared to the control columns. After one rotation with the fern, there was a significant decline in As concentrations in rice grains in treatment plants and a concomitant decline in both noncarcinogenic and carcinogenic health risks. Our results indicate that there could be substantial benefit in implementing this simple crop rotation model to help lower human health risks from As exposure via rice ingestion.

Synchrotron XFM tomography for elucidating metals and metalloids in hyperaccumulator plants.

Visualizing the endogenous distribution of elements within plant organs affords key insights in the regulation of trace elements in plants. Hyperaccumulators have extreme metal(loid) concentrations in their tissues, which make them useful models for studying metal(loid) homeostasis in plants. X-ray-based methods allow for the nondestructive analysis of most macro and trace elements with low limits of detection. However, observing the internal distributions of elements within plant organs still typically requires destructive sample preparation methods, including sectioning, for synchrotron X-ray fluorescence microscopy (XFM). X-ray fluorescence microscopy-computed tomography (XFM-CT) enables "virtual sectioning" of a sample thereby entirely avoiding artefacts arising from destructive sample preparation. The method can be used on frozen-hydrated samples, as such preserving "life-like" conditions. Absorption and Compton scattering maps obtained from synchrotron XFM-CT offer exquisite detail on structural features that can be used in concert with elemental data to interpret the results. In this article we introduce the technique and use it to reveal the internal distribution of hyperaccumulated elements in hyperaccumulator plant species. XFM-CT can be used to effectively probe the distribution of a range of different elements in plant tissues/organs, which has wide ranging applications across the plant sciences.

Effects of Lead, Copper and Cadmium on Bioaccumulation and Translocation Factors and Biosynthesis of Photosynthetic Pigments in Vicia faba L. (Broad Beans) at Different Stages of Growth

Trace elements in the environmental media contribute to toxicities of different types. Their presence in the arable pedosphere is a human-health risk factor. This study focused on Vicia faba represented by two Tunisian varieties of bean (Mamdouh) and faba bean (Badii). The objective was to analyze the effects of lead, copper and cadmium on their growth, chlorophyll-content and carotenoids-content, as well as the bioaccumulation and translocation factor, at different stages of growth. For each metal, the concentrations the plants were subjected to were 6, 0.3 and 0.03 mg/L of the metal in the compound for lead nitrate, copper nitrate and cadmium acetate, respectively. The analysis was carried out using an atomic absorption spectrophotometer (ICP-MS), encompassing all the parts of the plant. The authors detected a perceptible decrease in the fresh weight of roots and shoots, as well as a drop in the chlorophyll and carotenoid, for all the three heavy metals. Cadmium turned out to be the most toxic of the three metals and copper (which is incidentally an essential micronutrient for plant growth) the least. As far as the bioaccumulation factor was concerned, bean and faba bean exhibited different behaviours, both with regard to the growth stages and the heavy metal absorbed. During the vegetative growth stage, both were accumulators of all the three heavy metals (a translocation factor less than unity). However, in the flowering stage, faba bean was a hyper-accumulator of copper (TF > 1); while the bean plants accumulated a lot of lead in the pods-stage (TF > 1). It is worthwhile to pose new research questions and try to answer them in this study, if legumes are accumulator or hyper accumulator plants in which stage and in where organ accumulate more HMs.

Amendment-Enhanced Phytoextraction of Cadmium from Contaminated Soil Integrating with Ramie as Hyperaccumulator Plant

Amendment-Enhanced Phytoextraction of Cadmium from Contaminated Soil Integrating with Ramie as Hyperaccumulator Plant

Pengaruh Kuantitas Tanaman Melati Air (Echinodorus palaefolius) sebagai Fitoremediator Limbah Cair Penyamakan Kulit Proses Tanning

Phytoremediation is an effort to restore polluted land by absorbing, degrading, removing, stabilizing, or transforming pollutants using hyperaccumulator plants. Mexican Sword plants in phytoremediation are used as hyperaccumulators that can reduce heavy metal content by rhizofiltration mechanism. This study aims to determine the effect of mexican sword plant quantity on chromium concentration, pH value, and Dissolved Oxygen (DO). The research was conducted using an experimental method using a Completely Randomized Design (CRD), with 4 treatments, P0 = 0 mexican sword plants, P1 = 4 mexican sword plants, P3 = 6 mexican sword plants, P4 = 8 mexican sword plants. Repetition was carried out five times for each treatment. The data obtained were analyzed statistically by Analysis of Variance at = 5% and if there is a significant difference, further tests will be carried out using the Tukey test. The results showed that there was a significant difference (P<0.05) for each quantity of mexican sword plants concerning chromium concentration, pH value, and Dissolved Oxygen (DO). The best treatment results were shown by the quantity of 6 individuals (P2) with a Chromium concentration of 16.87 mg/L, a pH value of 8.45, and a DO of 1.3%.

Cadmium phytoremediation potential of Brassica genotypes grown in Cd spiked Loamy sand soils: Accumulation and tolerance.

Phytoremediation acts as an efficient methodology for management of toxic elements spiked soils. The accumulation and tolerance potential of hyper-accumulator plants for toxic elements act as an index for in-situ removal of toxic elements. Extraction of cadmium (Cd) through its accumulation in harvestable parts of plants has attracted attention as the economic and environment friendly technique. Brassica genotypes have greater potential to accumulate Cd when grown in Cd spiked soils. Therefore, for evaluation of comparative efficiency of three Brassica genotypes (B. juncea, B. campestris and B. napus) in phytoremediation of Cd spiked soils, a pot study was carried out in Cd contaminated soil with 6 levels as 0, 5, 10, 20, 40, and 80mgkg-1 soil. Results indicated that dry biomass production of Brassica genotypes declined with the enhanced Cd contamination in soil. The reduction in grain and shoot yield varied from 2.87 to 1.85 and 11.85 to 8.00g pot-1 with increased Cd contamination from 5 to 80mgkg-1 soil. Similarly, increased levels of Cd contamination resulted in enhanced concentration and accumulation in grains as well as shoots of all Brassica genotypes. Among Brassica genotypes, B. juncea recorded the highest production of dry biomass (12.8g pot-1), Cd accumulation (736.0μg pot-1). Also, the bioaccumulation coefficient and tolerance index indicated that B. juncea is the most tolerant genotype to Cd contamination in soil. Therefore, B. juncea could act as the most potential genotypes for decontamination of Cd spiked soils by preventing its entry into food chain.

Phytoremediation of heavy metals in soil and water: An eco-friendly, sustainable and multidisciplinary approach.

Rapid industrialization, increased waste production and surge in agricultural activities, mining, contaminated irrigation water and industrial effluents contribute to the contamination of water resources due to heavy metal (HM) accumulation. Humans employ HM-contaminated resources to produce food, which eventually accumulates in the food chain. Decontamination of these valuable resources, as well as avoidance of additional contamination has long been needed to avoid detrimental health impacts. Phytoremediation is a realistic and promising strategy for heavy metal removal from polluted areas, based on the employment of hyper-accumulator plant species that are extremely tolerant to HMs present in the environment/soil. Green plants are used to remove, decompose, or detoxify hazardous metals in this technique. For soil decontamination, five types of phytoremediation methods have been used viz. phytostabilization, phytodegradation, rhizofiltration, phytoextraction and phytovolatilization. Traditional phytoremediation methods, on the other hand, have significant limits in terms of large-scale application, thus biotechnological efforts to modify plants for HM phytoremediation ways are being explored to improve the efficacy of plants as HM decontamination candidates. It is relatively a new technology that is widely regarded as economic, efficient and unique besides being environment friendly. New metal hyperaccumulators with high efficiency are being explored and employed for their use in phytoremediation and phytomining. Therefore, this review comprehensively discusses different strategies and biotechnological approaches for the removal of various HM containments from the environment, with emphasis on the advancements and implications of phytoremediation, along with their applications in cleaning up various toxic pollutants. Moreover, sources, effects of HMs and factors affecting phytoremediation of HMs metals have also been discussed.

Enzymative activity of technogenic surface formations of Kuzbass

The coal mining is one of the leading industries in the global energy balance. Kuzbass is the main region of Russia that specializes in coal mining. About 60 % of the country's coal is mined there. Coal mining is carried out mainly by the open-pit method. As a result, some 178 thousand hectares ha of disturbed land are formed. Enzymatic activity is an indicator of soil self-repair. The aim of the work was to study the enzymatic activity of technogenic surface formations of the Kuzbass to assess their toxicity and further selection of destructor microorganisms, rhizobacteria and hyperaccumulator plants, which will be further used at the biological stage of recultivation. As objects of research, the samples of technogenic surface formations taken on the territory of the Barzassky and Mokhovsky coal dumps. Enzymatic activity of technogenic surface formations of dumps was: invertase – 2,24 and 2,12 mg of sucrose split 1 g soil in 1 h; nitrite reductase – 0,57 and 0,07 mg reduced NO2- per 1 g soil in 24 h; asparaginase – 71,22 and 60,63 mg NH3 per 1 g soil in 24 h, respectively. When studying the enzymatic activity, it was assumed that the native microflora uses low- and high-molecular hydrocarbons (alkanes, polycyclic aromatic hydrocarbons (PAH), etc.) as carbon sources. The content of mobile forms of heavy metals (HM) in the studied samples exceeds the maximum allowable concentration by 1,2-2,6 times. In the course of statistical analysis, it was revealed that the gross and mobile forms of zinc and copper are nitrite reductase inhibitors, the gross and mobile form of nickel is an asparaginase activator, in technogenic disturbed formations of the studied coal dumps. Nickel is also an invertase inhibitor in the Mokhovsky coal dump.

Natural Molecular Mechanisms of Plant Hyperaccumulation and Hypertolerance towards Heavy Metals.

The main mechanism of plant tolerance is the avoidance of metal uptake, whereas the main mechanism of hyperaccumulation is the uptake and neutralization of metals through specific plant processes. These include the formation of symbioses with rhizosphere microorganisms, the secretion of substances into the soil and metal immobilization, cell wall modification, changes in the expression of genes encoding heavy metal transporters, heavy metal ion chelation, and sequestration, and regenerative heat-shock protein production. The aim of this work was to review the natural plant mechanisms that contribute towards increased heavy metal accumulation and tolerance, as well as a review of the hyperaccumulator phytoremediation capacity. Phytoremediation is a strategy for purifying heavy-metal-contaminated soils using higher plants species as hyperaccumulators.