Phytoremediation Effect Research Articles

Assisted Phytostabilization of Mine-Tailings with Prosopis laevigata (Fabaceae) and Biochar.

Phytoremediation is a cost-effective technique to remediate heavy metal (HM) polluted sites. However, the toxic effects of HM can limit plant establishment and development, reducing phytoremediation effectiveness. Therefore, the addition of organic amendments to mine wastes, such as biochar, improves the establishment of plants and reduces the bioavailability of toxic HM and its subsequent absorption by plants. Prosopis laevigata can establish naturally in mine tailings and accumulate different HM; however, these individuals show morphological and genetic damage. In this study, the effect of biochar on HM bioaccumulation in roots and aerial tissues, HM translocation, morphological characters and plant growth were evaluated, after three and six months of exposure. Plants grown on mine tailings with biochar presented significantly higher values for most of the evaluated characters, in respect to plants that grew on mine tailing substrate. Biochar addition reduced the bioaccumulation and translocation of Cu, Pb, and Cd, while it favored the translocation of essential metals such as Fe and Mn. The addition of biochar from agro-industrial residues to mine tailings improves the establishment of plants with potential to phytoextract and phytostabilize metals from polluted soils. Using biochar and heavy metal accumulating plants constitutes an assisted phytostabilization strategy with great potential for HM polluted sites such as Cd and Pb.

Polyaspartic acid assisted-phytoremediation of cadmium-contaminated farmland: Phytoextraction efficiency, soil quality, and rhizosphere microbial community

Cadmium is highly toxic and one of the most dangerous metal pollutants in soil, and poses a serious threat to human health through soil-crop-food chain transmission. Polyaspartic acid (PASP) is a biodegradable additive that is environment-friendly compared to traditional chelating agents. Current studies have explored its effect on auxiliary phytoextraction at a laboratory scale; however, the method is still rarely reported at the field scale. Therefore, this study used two ecotypes of Pennisetum sinese in a field experiment for 3 years in Jiaoxi Township, Liuyang City, Hunan Province, China, to understand the effect of PASP on the phytoremediation of Cd-contaminated soil and soil quality through long-term field studies. Moreover, because the soil microbial community responds well to the phytoremediation effect of heavy metal (including Cd)-contaminated soil, the changes in rhizosphere soil microbial community diversity and composition were analyzed. After 2 years of PASP-enhanced phytoremediation, the PASP application increased the total Cd reduction in soil by 237 % and 255 %, and the soil DTPA-extractable Cd content decreased to 0.092 and 0.087 mg kg−1. When the application of PASP ceased in the third year, the two ecotypes of P. sinese obtained after harvest could achieve feed safety. Our study showed that the application of PASP could significantly increase the Cd extraction capacity and shoot biomass of P. sinese, and maintain soil health by optimizing the composition and structure of rhizosphere bacterial communities. The rhizosphere bacterial community structure was improved and dominated by Acidobacteriota, Proteobacteria, and Chloroflexi at the phylum level, and the increased abundance of Acetobacter, Enterobacter, Pseudomonas, and Stenotrophomonas at the genus level may promote heavy metal detoxification in soil, plant growth, and phytoremediation. Long-term field monitoring demonstrated that the low-cost and eco-friendly features of PASP made it a good candidate for enhancing phytoextraction efficiency and regulating soil microbial communities for remediation.

Effects of Heavy Metal Stress on Physiology, Hydraulics, and Anatomy of Three Desert Plants in the Jinchang Mining Area, China.

The physiological mechanisms and phytoremediation effects of three kinds of native quinoa in a desert mining area were studied. We used two different types of local soils (native soil and tailing soil) to analyze the changes in the heavy metal content, leaf physiology, photosynthetic parameters, stem hydraulics, and anatomical characteristics of potted quinoa. The results show that the chlorophyll content, photosynthetic rate, stomatal conductance, and transpiration rate of Kochia scoparia were decreased, but intercellular CO2 concentration (Ci) was increased under heavy metal stress, and the net photosynthetic rate (Pn) was decreased due to non-stomatal limitation. The gas exchange of Chenopodium glaucum and Atriplex centralasiatica showed a decrease in Pn, stomatal conductance (Gs), and transpiration rate (E) due to stomatal limitation. The three species showed a similar change in heavy metal content; they all showed elevated hydraulic parameters, decreased vessel density, and significantly thickened vessel walls under heavy metal stress. Physiological indicators such as proline content and activity of superoxide dismutase (SOD) and peroxidase (POD) increased, but the content of malondialdehyde (MDA) and glutathione (GSH), as well as catalase (CAT) activity, decreased in these three plants. Therefore, it can be concluded that these three species of quinoa, possibly the most dominant 30 desert plants in the region, showed a good adaptability and accumulation capacity under the pressure of heavy metal stress, and these plants can be good candidates for tailings remediation in the Jinchang desert mining area.

Co-planting improves the phytoremediation efficiency of combined phenanthrene and copper co-contaminated soils

Co-contamination from both organic and inorganic pollutants is widely distributed in soils and is more difficult to remediate compared to single-type pollution. The co-planting pattern is an ideal phytoremediation strategy to remediate contaminated soils owing to their incomparable benefits originating from plant-plant interactions, but how to choose the best plant combinations and which factors affect the final remediating efficiency are still unclear. In this study, phytoremediation with different planting strategies of three herbaceous species, namely ryegrass (Lolium perenne), Dahurian wildrye (Elymus dahuricus), and Creeping bentgrass (Agrostis stolonifera), was conducted to remediate soils contaminated with both copper (Cu) and phenanthrene (PHE). The residual PHE content of all planting patterns was significantly lower compared to the unplanted bulk soil. More than 99% of total PHE losses were related to plant-stimulated microbial degradation, and plant intake was a minor pathway for PHE removal (accounting for less than 1%). The phytoextraction was the main Cu removal process by plants and the root uptake ability of Cu was the highest in Creeping bentgrass (an average of 708.9 mg kg−1) compared to the other two plants of ryegrass (an average of 269.9 mg kg−1) and Dahurian wildrye (an average of 268.0 mg kg−1). Two species co-planting combinations (ranging from an average of 264.4–302.3 mg m−2) greatly increased the total accumulated Cu content compared to single planting patterns (ranging from an average of 163.0–263.3 mg m−2). Combing the PHE removal results, the combination of Ryegrass x Creeping bentgrass, or Creeping bentgrass x Dahurian wildrye, where one species had a high biomass and the other species had a high uptake capacity, was a successful co-planting mode for the phytoremediation of multi-contaminated soils. Furthermore, microbes e.g. Massilia affiliated to Oxalobacteraceae, Sphingomonas affiliated to Sphingomonadaceae and Burkholderiaceae that can potentially degrade PAHs, as well as Rhizobium affiliated to Rhizobiaceae, Mucilaginibacter affiliated to Sphingobacteriaceae, and Caulobacter affiliated to Caulobacteraceae that can tolerate Cu stress were enriched in the rhizosphere. Overall, our study emphasizes the plant-plant interaction and the plant-microbe association, that both regulate phytoremediation effects on co-contaminated soils.

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.

Combined effects of Bacillus sp. M6 strain and Sedum alfredii on rhizosphere community and bioremediation of cadmium polluted soils.

Concerns regarding inevitable soil translocation and bioaccumulation of cadmium (Cd) in plants have been escalating in concomitance with the posed phytotoxicity and threat to human health. Exhibiting a Cd tolerance, Bacillus sp. M6 strain has been reported as a soil amendment owing to its capability of reducing metal bioavailability in soils. The present study investigated the rhizospheric bacterial community of the Cd hyperaccumulator Sedum alfredii using 16S rRNA gene sequencing. Additionally, the Cd removal efficiency of strain Bacillus sp. M6 was enhanced by supplementing with biochar (C), glutamic acid (G), and rhamnolipid (R) to promote the phytoremediation effect of hyperaccumulator S. alfredii. To the best of our knowledge, this is the first time the amendments such as C, G, and R together with the plant-microbe system S. alfredii-Bacillus sp. M6 has been used for Cd bioremediation. The results showed that soil CaCl2 and DTPA (Diethylenetriamine penta-acetic acid) extractable Cd increased by 52.77 and 95.08%, respectively, in all M6 treatments compared to unamended control (CK). Sedum alfredii with Bacillus sp. M6 supplemented with biochar and rhamnolipid displayed a higher phytoremediation effect, and the removal capability of soil Cd (II) reached up to 16.47%. Moreover, remediation of Cd polluted soil by Bacillus sp. M6 also had an impact on the soil microbiome, including ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA), and cadmium transporting ATPase (cadA) genes. Quantitative PCR analysis confirmed the Bacillus sp. M6 strain increased the abundance of AOB and cadA in both low Cd (LC) and high Cd (HC) soils compared to AOA gene abundance. Besides, the abundance of Proteobacteria and Actinobacteria was found to be highest in both soils representing high tolerance capacity against Cd. While Firmicutes ranked third, indicating that the additionof strain could not make it the most dominant species. The results suggested the presence of the hyperaccumulator S. alfredii and Cd tolerant strain Bacillus sp. M6 supplemented with biochar, and rhamnolipid, play a unique and essential role in the remediation process and reducing the bioavailability of Cd.

Reactive effects of pre-sowing magnetic field exposure on morphological characteristics and antioxidant ability of Brassica juncea in phytoextraction.

As magnetic fields constantly act on living and biochemical processes, it is reasonable to hypothesize that magnetic field treatment of plant seeds would enhance the uptake capacity of non-essential elements. To verify this hypothesis, seeds of Brassica juncea were treated with 50, 100, 150, 200, and 400mT fields, and the dry weight, Cd uptake capacity, ferritin content, antioxidant enzyme activity, and phytoremediation effects of the plant were compared at the end of the experiment. Relative to the control, low- and moderate-intensity fields (50-200mT) enhanced the dry weight of plant leaves by 15.1%, 24.5%, 35.8%, and 49.1%, respectively, whereas the high-intensity field (400mT) decreased the biomass yield by 18.9%. The content of Cd in the above-ground tissues of B. juncea enhanced with the increasing field intensity, accompanied by an increase in oxidative damage. The activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) increased with exposure to low (50 and 100mT) and moderate (150 and 200mT) intensities, followed by a reduction at a high intensity (400mT). Catalase activity (CAT) and ferritin content exhibited an increasing trend with increasing intensity. The Cd decontamination index of B. juncea increased with the increasing magnetic field intensity until it reached a peak at 150mT, after which the values remained constant. Considering the phytoremediation effect and energy consumption, 150mT was the optimal scheme for magnetic-field-assisted phytoremediation using B. juncea. This study suggests that a suitable magnetic field can be regarded as an ecologically friendly physical trigger to improve the phytoextraction effect of B. juncea.

Nature-Based Solutions for Restoring an Agricultural Area Contaminated by an Oil Spill.

A feasibility study is presented for a bioremediation intervention to restore agricultural activity in a field hit by a diesel oil spill from an oil pipeline. The analysis of the real contaminated soil was conducted following two approaches. The first concerned the assessment of the biodegradative capacity of the indigenous microbial community through laboratory-scale experimentation with different treatments (natural attenuation, landfarming, landfarming + bioaugmentation). The second consisted of testing the effectiveness of phytoremediation with three plant species: Zea mays (corn), Lupinus albus (lupine) and Medicago sativa (alfalfa). With the first approach, after 180 days, the different treatments led to biodegradation percentages between 83 and 96% for linear hydrocarbons and between 76 and 83% for branched ones. In case of contamination by petroleum products, the main action of plants is to favor the degradation of hydrocarbons in the soil by stimulating microbial activity thanks to root exudates. The results obtained in this experiment confirm that the presence of plants favors a decrease in the hydrocarbon content, resulting in an improved degradation of up to 18% compared with non-vegetated soils. The addition of plant growth-promoting bacteria (PGPB) isolated from the contaminated soil also promoted the growth of the tested plants. In particular, an increase in biomass of over 50% was found for lupine. Finally, the metagenomic analysis of the contaminated soil allowed for evaluating the evolution of the composition of the microbial communities during the experimentation, with a focus on hydrocarbon- oxidizing bacteria.

Phytoremediation and Bioconcentration of Mineral and Heavy metals in Zea mays Inter-planted with Striga hermonthica in Soils from Mechanic Village Wukari

Phytoremediation involves the use of plants to remediate contaminated sites. This study evaluates the effect of phytoremediation on mineral and heavy metal concentration in agricultural soil within the vicinity of mechanic village Wukari using Zea mays interplanted with Striga hermonthica (SMV-MS), Zea mays alone (SMV-M), Zea mays inter-planted with Striga hermonthica alongside the application of fertilizer (SMV-MSF) and Zea mays alone alongside fertilizer application (SMV-MF). The bioconcentration of mineral and heavy metal and their translocation factors from the root to shoot of maize plants were estimated using empirical models. The result reveals that the efficiency of phytoextraction of the mineral and heavy metals were within the range: P (3.12 – 44.71 %), K (16.89 – 96.32 %), Mg (0.013 – 94.12 %), Mn (2.31 – 99.98 %), Si (20.92 – 52.07 %), Zn (2.74 – 21.65 %), Pb (10.44 – 100 %), Cd (0.75 – 42.85 %), Fe (7.42 – 98.57 %) and Al (19.14 – 98.69 %) respectively. The mean root and shoot bioconcentration factors (BCFs) of K, Mg, Mn and Al were greater than one indicating higher accumulation of the elements in the root and shoot of the maize plants. The root BCF of the elements was generally in the order: Mn > K > Mg > Cd > S i > Al > P > Fe > Zn > Pb while the shoot BCF was in the order: Mn > K > Mg > Al > Fe > Cd > S i > P > Zn > Pb. The mean root to shoot translocation factors (TF) of P, Mn, Zn, Pb, Cd, Fe and Al were greater than one indicating effective translocation of the elements from the root to shoots. The translocation factors were generally in the order: Fe > Al > Pb > Mn > Zn > P > Cd > Mg > S i > K.

Assessing the suitable regions and the key factors for three Cd-accumulating plants (Sedum alfredii, Phytolacca americana, and Hylotelephium spectabile) in China using MaxEnt model

Phytoremediation is an effective way to remove metals from contaminated soil, and selecting remediation plants suitable for climate conditions is a prerequisite for effective phytoremediation. In this study, a MaxEnt model was applied to investigate the potential distribution and habitat suitability of three Cd-accumulating plants in China- Sedum alfredii, Phytolacca americana, and Hylotelephium spectabile and explore the key environmental factors that affect their habitat suitability. A total of 44 environmental parameters, including bioclimatic variables, altitude, and soil property parameters were used. The results showed that: (1) For S. alfredii, suitable areas account for 14.9 % of the area of China, which are mainly distributed in the middle and lower reaches of the Yangtze River. (2) The suitable areas of P. americana account for 22.7 % of China and are mainly located in the regions of the Qinling Mountains and the south of China. (3) While that for H. spectabile are mainly located in the regions of northeastern China and certain regions of central China, with suitable areas account for 8.3 % of the area of China. (4) The distribution of these three plants is significantly affected by precipitation; specifically, solar radiation is an influential factor for the distribution of S. alfredii and H. spectabile, and temperature limits the distribution of P. americana. The selection and agronomic management of hyperaccumulators for phytoremediation requires multifactor consideration (e.g., climate, soil conditions and planting patterns). The results can provide guidance for identifying suitable areas for planting these three accumulating plants, which could not only prevent the unscientific cultivation of them in unsuitable habitats but also enhance the efficiency of phytoremediation. Meanwhile, these findings are expected to contribute to agronomic management for improved phytoremediation effects in different Cd-contaminated regions of China.

A Review on Potential of Field Crops in Phytoremediation

Heavy metals (HMs) are unique products, and as a result of their uniqueness, they cannot be converted into non-toxic forms. Both natural and man-made sources, such as mining, industry, and automobile emissions, release heavy metals into the environment. They enter subsurface waters through waterways or are carried away by runoff into surface waters, damaging both the water and the land at the same time. Because of population growth, industrialisation, and urbanisation, HM pollution is on the rise. Organic and inorganic pollutants are now poisoning a large area of the world, with heavy metal pollution becoming a serious problem in recent years. Toxic heavy metal has a detrimental influence on plant growth, which also damages DNA, and causes cancer in animals and humans. To remove, transport, stabilise, and breakdown contaminants from soil, sediment, and water, phytoremediation employs plants. Rhizofiltration, phytostabilization, phytovolatization, phytodegradation, and phytotransformation are some of its processes. Due to its advantages as a low-cost, effective, and environmentally friendly way of eliminating dangerous metals from the soil, phytoremediation has grown in favour in recent years. Field crops can create a thick green canopy on disturbed soil, improving the landscape and reducing contaminant movement through water, wind, and percolation. This increases the effectiveness of phytoremediation. More than 400 plant species, including the well-known Ricinus communis, Thlaspi, Brassica, and Arabidopsis, Helianthus annuus, Zea mays, and Brassica napus, have been identified as having potential for soil and water remediation. In this review article, we discuss the factors that contribute to heavy metal pollution, phytoremediation technology, the method by which heavy metals are taken up, and various studies that describe its practical use.

Role of Sedum alfredii and soil microbes in the remediation of ultra-high content heavy metals contaminated soil

Ultra-high content of heavy metals (UHHMs) poses a threat to soil health and agricultural products safety, in turn causing harm to human health through the food chain. Phytoremediation has proven to be an effective technique for restoration of soil contaminated with a single or several conventional content of heavy metals, whereas the effectiveness of phytoremediation for UHHMs-contaminated soil is unclear. In this study, we investigated the effectiveness of phytoremediation for UHHMs-contaminated soil and the role of soil microbes in the process of phytoremediation. Results showed that the Sedum alfredii grew well in UHHMs-contaminated soil, although the shoot height, biomass, and accumulation of heavy metals were slightly reduced due to the stress of UHHMs. Soil microbiome analysis demonstrated that both the number and diversity of microbes decreased in UHHMs-contaminated soil. However, the dominant species Patescibacteria proliferated to varying degrees under the exposure of various UHHMs. Patescibacteria is closely related to the functional genes regarding transport of various heavy metals. Given that Patescibacteria exhibits a strong migration ability in soil, it is likely involved in the transport of various heavy metals from the bulk soil to the rhizosphere. This enhanced the availability of heavy metals in the rhizosphere, which in turn improved the phytoremediation efficiency of the Sedum alfredii. This was further confirmed by structural equation modeling analysis and microbial phenotypes prediction. Findings suggest that using Sedum alfredii to remedy UHHMs-contaminated soil is feasible owing to the facilitation by soil microbes.

Temporal effect of phytoremediation on the bacterial community in petroleum-contaminated soil

Phytoremediation is a promising bio-technology where plants associated with microbes are employed to remediate sites co-contaminated with petroleum. With the in-depth study of plant restoration, it is necessary to explore the dynamic changes of microbial communities in petroleum-contaminated soil. This study investigated the effects of Ryegrass on bacterial community and diversity in petroleum contaminated soil. High-throughput sequencing technology was used to compare the bacterial communities in 14 groups samples at different repair stages. It was concluded that different responses were observed to promote or inhibit microbial reproduction. The most significant bacterial family were Comamonadaceae, Nocardiaceae, Blastocatellaceae, and Cytophagacea. Comamonadaceae showed the highest level of remediation in non-petroleum-contaminated soils at 90 days. However, Blastocatellaceae and Cytophagaceae exhibited high microbial contents in petroleum-contaminated soil at 0 and 40 days, respectively. In all samples, plants improved the remediation of petroleum-contaminated soil and the highest abundance of microbial communities were found after 90 days. These data indicate that not only rhizosphere secretions but also petroleum, will promote microbial growth. Moreover, the repair time has a vital effect on microbial community changes. This study supports the foundation to control soil pollution and highlight the periodic dynamic of microbial community diversity and structure.

Cadmium-resistant Chryseobacterium sp. DEMBc1 strain: characteristics and potential to assist phytoremediation and promote plant growth.

The effectiveness of phytoremediation is closely related to the various interactions between pollutants, soil particles, rhizosphere microorganisms, and plants. Therefore, the object of current study was a cadmium-tolerant bacterium isolated from the rye rhizosphere, with a high degree of genetic similarity to the genus Chryseobacterium. Chryseobacterium sp. DEMBc1 was able to grow with 36 different BiologGN2 carbon sources and show the adaptation to stress factors such as Cd (100 μg ml-1), low temperature (8 °C), and salinity (2% NaCl). Furthermore, it was shown that DEMBc1 had the characteristics of plant growth-promoting microorganisms: it was able to produce ammonia, indole acetic acid, 1-aminocyclopropane-1-carboxylic acid deaminase, and siderophores, as well as solubilize Ca3(PO4)3. After inoculation with DEMBc1, a significant decrease in the concentration of Cd was observed in the roots of Festuca ovina grown in Cd-polluted soil, compared to the non-inoculated Cd-polluted soil. It was also noticed that DEMBc1 produced a large amount of extracellular polymeric substances that were significantly higher than the cellular biomass. These polymers can form a barrier to reduce the translocation of Cd from the growth medium to the plant roots. According to the current study, DEMBc1 has a stabilizing potential and can decrease the mobility of Cd in the F. ovina rhizosphere, bioaccumulate metals in plant tissues, and effectively improve the bioavailability of nutrients, especially Fe, N, and P in a polluted environments.

​​Marigold (Tagetes spp.): A Diverse Crop with Multipurpose Value for Health and Environment: A Review

Marigold (Tagetes spp.) is one of the most popular flower crop commercially exploited for multipurpose use. Apart from great demand of marigold flowers, the plants use in phytoremediation and allelopathic effect has been greatly exploited. Marigolds can be used against plant parasitic nematodes as a cover crop in rotation, as an intercrop, or as a crop residue amendment. Successful use of marigold as trap crop is well on record whereas its use as potential natural herbicide needs to be explored. Essential oils obtained from marigold possess antibacterial and antifungal properties and are widely used in perfumery industries, as insect repellent and as flavor component. Its extracts can be explored as alternative natural insecticides towards the stored products. Use of marigold for its medicinal value for curing various diseases has been well documented. Carotenoids extracted from flowers are being used commercially in pharmaceuticals. Marigold extract also finds application in coloring foods and various dairy products. Marigold petals are used as additives for poultry feed, as they provide bright colors in egg yolks, skin and fatty tissues and also as emulsifying gum. Silver and gold nanoparticles have been synthesized from marigold for antimicrobial activity. This review paper discusses the research undertaken for various uses of marigold plant worldwide.

Influence of Growing Miscanthus x giganteus on Ecosystem Services of Chernozem

The paper investigates the optimization of ecosystem services of podzolized heavy loamy chernozem (black soil) as a result of the cultivation of the perennial energy culture of Miscanthus x giganteus. The research was conducted on an experimental land plot during 2016–2021. No fertilization was applied to the soil during the experiments, and over the years of research, the growing seasons were accompanied by abnormal droughts, but even under such conditions, the plants of Miscanthus x giganteus gradually increased their yield. At the initial stage of research, in the third year of cultivation, dry biomass of Miscanthus x giganteus was obtained at 14.3 t/ha, in the fourth year–18.6 t/ha, and already in the fifth and sixth years, 21.7 and 24.5 t/ha, respectively. That is, energy-wise, the harvest for the last year was equivalent to 15.9 tons of coal or 12,618 m3 of natural gas. Cultivation of Miscanthus x giganteus on black soil for six years has improved the provision of its ecosystem services, regulation, and ecosystem maintenance services. The possibility of growing perennial energy crops on agricultural soils has been proven by obtaining a significant amount of biomass and a positive phytoremediation effect on the soil by reducing erosion, preserving biodiversity, sequestering carbon, and sustainably improving the ecological situation.

Phytoremediation potential of flowering plants in relation to copper under the conditions of a model laboratory experiment

This paper describes the results of studying the phytoremediation potential of flowering plants in relation to copper ions in laboratory experiment conditions. The test crops were tansy-leaved phacelia, white mustard, small-flowered marigolds and a mixture of grasses consisting of red fescue, pasture ryegrass and meadow bluegrass in a ratio of 40%, 50%, 10% respectively. Under experimental conditions copper ions in concentrations of 2 and 10 MPC were introduced into the soil selected from the territory of agricultural lands (leached medium-sized heavy loamy chernozem with a high content of humus, mobile phosphorus and exchangeable potassium and a low content of nitrate nitrogen, gross and mobile forms of copper). It has been found that all the selected crops accumulated copper ions from the soil to varying degrees, which makes them suitable for phytoremediation of agricultural lands planned for organic farming. The ability to accumulate copper ions increases in a row: white mustard small-flowered marigolds tansy-leaved phacelia a mixture of grasses. The maximum effect of phytoremediation of the soil in relation to copper ions has been revealed in the variant with a cereal mixture: the content of copper ions in the soil decreases by 38,8% when applying 2 MPC, by 47,8% when applying 10 MPC.

Effect of arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) on microorganism of phenanthrene and pyrene contaminated soils

A pot experiment was performed to investigate the effect of phytoremediation (CK, using tall fescue), fungi remediation (GV, using Glomus versiforme), bacterial remediation (PS, using Pseudomonas fluorescens Ps2-6), and microbial-phytoremediation (GVPS, using three species) on removing polycyclic aromatic hydrocarbons (PAHs) and the microbial diversity in soils. Inoculation with G. versiforme and P. fluorescens could increase the biomass of tall fescue and the accumulation of phenanthrene (PHE) and pyrene (PYR) in plants. Among them, the highest PHE and PYR removal efficiencies and highest biomass of tall fescue were observed in the GVPS treatment and the microbial diversity in contaminated soil was changed, the result revealed that Proteobacteria and Ascomycota were the dominant bacterial phylum and fungal phylum in all treatments, while more Proteobacteria were detected in GVPS treatment. At the genus level, the abundance of Sphingomonas (3.17%), Pseudomonas (2.05%), and Fusarium (8.65%) treated with GVPS increased compared with other treatments. These pieces of evidence contribute to a better understanding of the mechanisms involved in the combined microbial-phytoremediation strategies for PAHs-contaminated soils, especially the effects of microbial-phytoremediation on rhizosphere microbial diversity.

Assessment of the phytoremediation effectiveness in the restoration of uranium mine tailings

Uranium (U) contamination due to mining and metallurgical operations is a serious problem and poses a high potential threat to humans and other organisms. The application of amendments and/or plants, known as assisted phytoremediation, can accelerate the adsorption, complexation and precipitation processes in soil, and therefore can facilitate the restoration of U mining areas. This study located in the central-west of peninsular Spain was focussed on two different U mine waste dumps (MWD), where the assisted phytoremediation process was implemented. At each MWD, an area of 10 ha (approx.) was selected for sugar lime (SL) application, at a rate of 75 T ha −1. In addition, after SL addition, common grasses Cynodon dactylon, Secale cereale, and the leguminosae Vicia sativa were seeded. Evolution of soil physico-chemical properties and plant development was monitored for 69 months in Top, Medium and Low areas of both MWDs. The main results indicated a positive effect of the amendment, improving the development of the spontaneous and induced vegetation and the accumulation of soil organic matter. Values of pH were maintained in the range of the neutrality during all the experimentation period. In general, total concentrations of trace elements (including U) presented a high variability. Values were similar in the different studied areas of each MWD (Top, Medium and Low) and did not change in time. Trace elements contents were, in general, higher than those found in non-contaminated soils. However, U and Mn availability decreased with time, as well as the accumulation of trace elements (especially U and Mn) in the studied plants. Moreover, these contents were lower than the permitted limit for animal consumption. In conclusion, application of phytoremediation contributed to the stabilization of U within the soil-plant system, mainly by its positive effects on vegetation cover and the consequent increase in soil organic matter.

EFFICIENCY OF PHYTOREMEDIATION OF SOIL CONTAMINATED BY HEAVY METALS BY CULTIVATION OF SPOTTED MILK THISTLE

In contrast to air and water environments, soils do not have the ability to quickly clean, so toxic substances that enter it from the outside can be stored for a long time. At the same time, toxicants, being included in the food chain of soil - plants - living organisms, can reach high levels and have a long duration of action. It is known that the accumulation of heavy metals in the soil occurs under the influence of emissions from industrial enterprises, during irrigation with wastewater, removal of sludge to agricultural lands after wastewater treatment, due to the application of mineral and organic fertilizers, etc. When heavy metals affect soils, there is a change in the soil environment, the occurrence of erosion processes, contamination of agricultural products, etc., which necessitates the search for productive and safe methods of their cleaning. The article presents the results of a study of the effectiveness of phytoremediation of soil when growing milk thistle when it is fertilized in the conditions of the Right-Bank Forest-Steppe. Based on the results of the analysis of primary sources, the current problems of soil degradation, their contamination with heavy metals, and the role of phytoremediation are determined. As a result of the research, certain changes in the intensity of the removal of lead, cadmium and zinc from the soil were found when it was fertilized with mineral fertilizers - ammonium nitrate (60 kg/ha), simple superphosphate (60 kg/ha), potassium chloride (60 kg/ha), NPK mixture fertilizers (60/60/60 kg/ha) and organic fertilizers - humus (20 t/ha), sugar beet lime sludge compost (6 t/ha) and green manure (mustard). It was established that fertilizing gray forest soils with ammonium nitrate, simple superphosphate, potassium chloride, and a mixture of NPK fertilizers contributed to the increase of removal with vegetative mass and seeds of milk thistle: lead by 2.14 times, 54.3%, 52.2%, and 87.5 %; cadmium – 3.5 times, 41.9%, 71.1%, 2.2 times; zinc - 2.8 times, 22.7%, 20.1%, 2.6%, respectively. Fertilizing the soil with humus, sugar beet lime sludge compost, green manure increased lead removal from the soil by milk thistle by 60.1%, 42%, 3.9%; cadmium - by 58.0%, 31.3%, 3.2%, zinc - by 2.03 times, 24%, 13.6%, respectively.